Chp

FMAC: Coal Handling System Maintenance Guide

Technical Report

Effective December 6, 2006, this report has been made publicly available in accordance with Section 734.3(b)(3) and published in accordance with Section 734.7 of the U.S. Export Administration Regulations. Regulations. As a result of this publication, this this report is subject subject to only copyright protection and does not require any license agreement from EPRI. This notice supersedes the export control restrictions and any proprietary licensed material notices embedded in the document prior to publication.

FMAC: Coal Handling System Maintenance Guide 1013349

Final Report, December 2006

EPRI Project Manager A. Grunsky

ELECTRIC POWER RESEARCH INSTITUTE 3420 Hillview Avenue, Palo Alto, California 94304-1338 • PO Box 10412, Palo Alto, California 94303-0813 • USA 800.313.3774 • 650.855.2121 • [email protected] • www.epri.com

DISCLAIMER OF WARRANTIES AND LIMITATION OF LIABILITIES THIS DOCUMENT WAS PREPARED BY THE ORGANIZATION(S) NAMED BELOW AS AN ACCOUNT OF WORK SPONSORED OR COSPONSORED BY THE ELECTRIC POWER RESEARCH INSTITUTE, INC. (EPRI). NEITHER EPRI, ANY MEMBER OF EPRI, ANY COSPONSOR, THE ORGANIZATION(S) BELOW, NOR ANY PERSON ACTING ON BEHALF OF ANY OF THEM: (A) MAKES ANY WARRANTY OR REPRESENTATION WHATSOEVER, EXPRESS OR IMPLIED, (I) WITH RESPECT TO THE USE OF ANY INFORMATION, APPARATUS, METHOD, PROCESS, OR SIMILAR ITEM DISCLOSED IN THIS DOCUMENT, INCLUDING MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, OR (II) THAT SUCH USE DOES NOT INFRINGE ON OR INTERFERE WITH PRIVATELY OWNED RIGHTS, INCLUDING ANY PARTY'S INTELLECTUAL PROPERTY, OR (III) THAT THIS DOCUMENT IS SUITABLE TO ANY PARTICULAR USER'S CIRCUMSTANCE; OR (B) ASSUMES RESPONSIBILITY FOR FOR ANY DAMAGES OR OTHER LIABILITY WHATSOEVER (INCLUDING ANY CONSEQUENTIAL DAMAGES, EVEN IF EPRI OR ANY EPRI REPRESENTATIVE HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES) RESULTING FROM YOUR SELECTION OR USE OF THIS DOCUMENT OR ANY INFORMATION, APPARATUS, METHOD, PROCESS, OR SIMILAR ITEM DISCLOSED IN THIS DOCUMENT. ORGANIZATION(S) THAT PREPARED THIS DOCUMENT Electric Power Research Institute (EPRI)

NOTE For further information about EPRI, call the EPRI Customer Assistance Center at 800.313.3774 or e-mail [email protected]. Electric Power Research Institute and EPRI are registered service marks of the Electric Power Research Institute, Inc. Copyright © 2006 Electric Power Research Institute, Inc. All rights reserved.

CITATIONS This report was prepared by Electric Power Research Institute (EPRI) Fossil Maintenance Applications Center (FMAC) 1300 W.T. Harris Blvd. Charlotte, NC 28262 This report describes research sponsored by EPRI. The report is a corporate document that should be cited in the literature in the following manner: FMAC: Coal Handling System Maintenance Guide. EPRI, Palo Alto, CA: 2006. 1013349.

iii

REPORT SUMMARY

The Coal Handling System Maintenance Guide provides fossil plant maintenance personnel with current maintenance information on this system. This report will assist plant maintenance personnel in improving the reliability of and reducing the maintenance costs for the coal handling system.

Background In 2003, the Fossil Maintenance Applications Center (FMAC) member utilities completed a survey on maintenance issues. Several topics, two of which were fly ash handling and coal handling, ranked high as chronic problems with high impact to plant reliability. From the survey responses, the FMAC Steering Committee recommended the development of guidance targeted at these two major systems. FMAC has produced related guides addressing maintenance issues for sootblowing, bottom ash, and electrostatic precipitator systems. In 2005, FMAC completed the Ash Handling System Maintenance Guide (1011684). It is now time to address specific concerns regarding the upstream processes for coal handling from the time the coal is unloaded until it enters the plant to be pulverized.

Objectives To describe the typical equipment and components of a coal handling system •

•

To provide guidance on preventive maintenance, repair and replacement, and troubleshooting recommendations for coal handling equipment

Approach The intent of the Coal Handling System Maintenance Guide is to address various engineering, maintenance, and operations issues regarding coal handling system maintenance. Key suppliers of coal handling system designs and components were solicited for assistance to ensure that the report reflects the latest technologies available in the industry. A technical advisory group was formed that consisted of coal handling equipment owners from the EPRI FMAC utility members. Input was solicited for current maintenance issues for the coal handling system. Experienceproven practices and techniques were identified during this effort and are compiled in this report.

v

Results This technical report provides an overview of system design parameters and familiarizes maintenance and engineering personnel at a fossil power plant with the components composing a typical coal handling/conveying system and their functions. The focus of the report is providing guidance for performing preventive maintenance on the numerous system components. The report also provides guidance regarding the repair and replacement of system components and which components are typically repaired or refurbished on site. Troubleshooting guidance is provided for those components for which it is applicable. Personnel qualification and safety guidelines are included, and the user is also provided with sources of training, repair, and consulting services related to coal handling systems. EPRI Perspective The information contained in this report represents a significant collection of technical and human performance information, including techniques and good practices, related to the design, maintenance, and operation of coal handling systems common at most domestic fossil power generating stations. Assemblage of this information provides a single point of reference for plant engineering and maintenance personnel, both now and in the future. Through the use of this report in close conjunction with the industry guidance provided by major coal handling component suppliers, EPRI members should be able to significantly improve and consistently implement the processes associated with the safe and reliable operation of their coal handling systems. Keywords Coal handling Maintenance Preventive maintenance Preventive maintenance basis Reliability Troubleshooting

vi

ACKNOWLEDGMENTS FMAC would like to acknowledge the following individuals for their contributions during the development of this report. Listed here are the technical advisory group members. Name

Utility/Location

Dennis Child

Eskom/Kendal Power Station

Wayne Crawford

EPRI/Charlotte

Jack Dickerson

Wisconsin Energies/Pleasant Prairie Power Plant

David Farnsworth

Great River Energy/Coal Creek Generating Station

Robert Jones

Wisconsin Energies/Oak Creek Power Plant

Nathan McNeil

Wisconsin Energies/Corporate

James Peterson


Derek Stock

Wisconsin Energies/Valley Generating Station

Scott Skousen

Salt River Project/Coronado Generating Station

Bob Wiese


Rob Woodall

Tarong Energy/Tarong Power Station

In addition to the individuals noted, the following companies provided technical material, the use of figures, and review of the guide. Their support and willingness to provide the majority of the technical guidance contained in this report is greatly appreciated. Name

Company Name

Chris Thompson

Airtrol Inc.

Bob Wolz

Carman Industries, Inc.

Gary J. Blankenheim

Dings Magnetic Group

Phil Cummings

ENCO Engineering

Russ Leets

FMC Technologies (Bulk Conveying)

Dick Reeves

General Kinematics Headquarters

Steve Zawrotuk

Heyl & Patterson, Inc.

Lee Doyer

Pennsylvania Crusher Corporation

Charles Fleishman, PE

Pennsylvania Crusher Corporation vii

Bob Williams

Roberts & Schaefer Company

Kevin Peterson

Salina Vortex Corporation

John Towers

Thermo Electron Corporation, Sampling Equipment Group

Bill Ripka

Thermo Electron Corporation, Weighing and Inspection Group

FMAC was supported in this effort by Sequoia Consulting Group, Inc. (M. Tulay, principal investigator) and RPA Associates, Inc. (R. Aulenbach, principal investigator).

viii

CONTENTS

1 INTRODUCTION INTRODUCTION .......................... ....................................... .......................... ........................... ........................... .......................... ........................... ........................1-1 ..........1-1

1.1

Purpose ............ .......................... ........................... .......................... ........................... ........................... ........................... ........................... ..........................1-1 .............1-1

1.2

Scope of Equipment and System Components .......................... ........................................ ............................ ...................1-1 .....1-1

1.2.1

Overview of the Coal Handling System......................... System....................................... ............................ ........................1-1 ..........1-1

1.2.2

Uniqueness of Each Coal Handling System ................................... ................................................. ....................1-3 ......1-3

1.2.3

Using the Guidance in This Report ........................... ......................................... ........................... ........................... ................ 1-7

1.3

Report Structure and Content Overview ............ ......................... ........................... ............................ ........................... .................1-7 ....1-7

1.4

Glossary of Terms and Acronyms........................ Acronyms...................................... ........................... ........................... ............................ ................ 1-8

1.4.1

Industry Definitions and Nomenclature ........................... ......................................... ........................... ......................1-8 .........1-8

1.4.2

Acronyms .......................... ........................................ ........................... .......................... ........................... ........................... .......................... ............... ..1-9 1-9

1.5

Relationship with EPRI FMAC and to Other EPRI Reports ............ .......................... ...........................1-10 .............1-10

1.5.1

Component Maintenance Guidance............................ Guidance.......................................... ........................... ........................1-11 ...........1-11

1.5.2

Programmatic Maintenance and Process Guidance............ Guidance .......................... .............................1-11 ...............1-11

1.6

Key Points................................ Points............................................. .......................... ........................... ........................... .......................... ........................... ................1 ..1-12 -12

2 INTRODUCTION INTRODUCTION TO COAL AND COAL HANDLING SYSTEM COMPONENTS.................2-1 COMPONENTS.................2-1

2.1

Coal Types and Characteristics............. Characteristics ........................... ........................... ........................... ........................... ........................... ................ ..2-1 2-1

2.1.1

General Coal Characteristics ........................... ......................................... ............................ ........................... .......................2-1 ..........2-1

2.1.2

Categories and Ranks of Coal ........................... ......................................... ............................ ............................ .....................2-1 .......2-1

2.1.2.1

Anthracite Coal ........................... ........................................ ........................... ............................ ........................... .........................2-2 ............2-2

2.1.2.2

Bituminous Coal............ Coal ......................... ........................... ........................... .......................... ........................... ...........................2-3 .............2-3

2.1.2.3

Subbituminous Coal............. Coal .......................... ........................... ............................ ........................... ........................... ...................2-3 .....2-3

2.1.2.4

Lignite Coal ............ .......................... ............................ ........................... ........................... ........................... ........................... ...................2-3 .....2-3

2.1.3

Chemistry of Coal........................... Coal......................................... ........................... .......................... ........................... ........................... ............... ..2-3 2-3

2.1.4

Coal Hardness and Heating Values ............ .......................... ............................ ............................ ............................2-4 ..............2-4

2.2

Sources of Coal in the United States .......................... ........................................ ............................ ............................ .....................2-5 .......2-5

2.3

Introduction to Coal Handling System Components ............................ .......................................... ........................2-6 ..........2-6

2.3.1

Belt Scales ............ .......................... ........................... ........................... ........................... .......................... ........................... ...........................2-6 .............2-6 ix

2.3.2

2.3.2.1

Rotary Railcar Dumper .......................... ........................................ ........................... ........................... ........................... ............... 2-8

2.3.2.2

Turnover Railcar Dumper............................. Dumper........................................... ............................ ........................... ...................2-10 ......2-10

2.3.2.3

Train Positioner......................... Positioner....................................... ........................... ........................... ........................... .........................2-10 ............2-10

2.3.2.4

Railcar Indexer....................... Indexer.................................... ........................... ........................... .......................... ........................... ................2-1 ..2-11 1

2.3.2.5

Traveling Hammermill ............ .......................... ............................ ........................... ........................... ........................... ............... 2-12

2.3.2.6

Continuous Barge Unloader.............................. Unloader............................................ ............................ ........................... ............... 2-12

2.3.2.7

Grab Bucket Barge Unloader............ Unloader .......................... ........................... ........................... ........................... .................2-13 ....2-13

2.3.3

Unloading Hoppers ........................... ........................................ ........................... ........................... ........................... ........................2-14 ..........2-14

2.3.4

Sampling Equipment ........................... ........................................ ........................... ........................... .......................... ......................2-15 .........2-15

2.3.4.1

Introduction to Coal Sampling............ Sampling .......................... ............................ ............................ ............................ ................ 2-15

2.3.4.2

Coal Sampling System Components ............................ ......................................... ........................... .................2-16 ...2-16

2.3.4.3

Primary Sampling Machine ........................... ......................................... ............................ ........................... ..................2-18 .....2-18

2.3.4.4

Primary Belt Feeder ........................... ......................................... ........................... ........................... ........................... ................2-19 ...2-19

2.3.4.5

Coal Sampler Crusher ........................... ........................................ .......................... ........................... ...........................2-19 .............2-19

2.3.4.6

Secondary Belt Feeder/Secondary Sweep Sampler................................. Sampler................................... ..2-19 2-19

2.3.4.7

Sample Collector........................... Collector......................................... ........................... ........................... ............................ .....................2-20 .......2-20

2.3.4.8

Reject Return Conveyor........................... Conveyor........................................ ........................... ........................... ........................2-21 ...........2-21

2.3.4.9

Electrical Control Panel............................. Panel........................................... ............................ ........................... ......................2-21 .........2-21

2.3.5

Coal Crushers ............ ......................... ........................... ........................... ........................... ........................... .......................... ....................2-21 .......2-21

2.3.5.1

Mechanical Reduction Methods............ Methods .......................... ............................ ............................ ..........................2-21 ............2-21

2.3.5.2

Breakers.......................... Breakers........................................ ........................... ........................... ........................... .......................... ......................2-23 .........2-23

2.3.5.3

Cage Mills ............ .......................... ........................... .......................... ........................... ........................... ........................... ....................2-25 ......2-25

2.3.5.4

Granulators .......................... ....................................... ........................... ........................... .......................... ........................... ..................2-26 ....2-26

2.3.5.5

Hammermills ........................... ........................................ .......................... ........................... ........................... .......................... ............... ..2-28 2-28

2.3.6

Reclaim Hoppers.......................... Hoppers....................................... ........................... ........................... .......................... ........................... ................2-3 ..2-30 0

2.3.7

Discharge Hopper Feeders ........................... ......................................... ........................... ........................... .........................2-33 ...........2-33

2.3.8

Magnetic Separators ........................... ......................................... ........................... ........................... ............................ .....................2-34 .......2-34

2.3.8.1

Self-Cleaning Overhead Magnets............ Magnets .......................... ........................... ........................... ........................2-34 ..........2-34

2.3.8.2

Stationary Overhead Magnets ............ .......................... ............................ ........................... ........................... ................ 2-36

2.3.8.3

Rectifiers ............ ......................... .......................... ........................... ........................... ........................... ........................... ......................2-38 .........2-38

2.3.9

x

Unloading Equipment........................ Equipment..................................... ........................... ........................... ........................... ..........................2-8 ............2-8

Slide Gates........................ Gates...................................... ............................ ........................... ........................... ........................... .........................2-38 ............2-38

2.3.9.1

Horizontal Slide Gates .......................... ........................................ ............................ ........................... ..........................2-38 .............2-38

2.3.9.2

Actuators.................................. Actuators..................... ........................... ........................... .......................... ........................... ...........................2-42 .............2-42

2.3.9.3

Seals ........................... ........................................ ........................... ........................... ........................... ........................... ..........................2-42 .............2-42

2.3.9.4

Construction Materials ........................... ........................................ .......................... ........................... ...........................2-42 .............2-42

2.3.9.5

Position Indication...................... Indication.................................... ........................... ........................... ............................ ........................2-43 ..........2-43

2.3.10

Dust Control Systems.............................. Systems........................................... ........................... ............................ ........................... ................2-43 ...2-43

2.3.10.1

General Operation .......................... ........................................ ........................... .......................... ........................... ..................2-44 ....2-44

2.3.10.2

Configuration Options .......................... ....................................... ........................... ........................... ..........................2-46 .............2-46

2.3.11

Conveyor Belts, Pulleys, Idlers, and Rollers................................... Rollers................................................. ..................2-47 ....2-47

2.3.11.1

Types of Conveyor Belts Used in Coal Handling Systems .......................2-47 .......................2-47

2.3.11.2

Conveyor Belt System Components ............ .......................... ............................ ........................... .................2-48 ....2-48

2.3.11.3

Conveyor Belt System Attributes and Terms ........................... ........................................ .................2-52 ....2-52

2.3.12

Movable Belt Tripper Devices ...................................... ................................................... ........................... .......................2-54 .........2-54

2.3.12.1

Motor-Propelled Tripper ............................ ......................................... ........................... ........................... .....................2-56 ........2-56

2.3.12.2

Cable-Propelled Tripper............. Tripper ........................... ........................... ........................... ........................... ......................2-56 .........2-56

2.3.12.3

Belt-Propelled Tripper .......................... ........................................ ............................ ........................... .........................2-56 ............2-56

2.3.13

Gearboxes............. Gearboxes .......................... ........................... ........................... .......................... ........................... ........................... ........................2-56 ...........2-56

2.3.13.1

Gear Arrangement ........................... ......................................... ........................... .......................... ........................... .................2-56 ...2-56

2.3.13.2

Gearbox Applications......................... Applications...................................... ........................... ............................ ........................... ............... 2-60

2.3.14

Flexible Shaft Couplings..................... Couplings.................................. ........................... ........................... ........................... ......................2-61 ........2-61

2.3.14.1

Overview of Metallic Flexible Shaft Couplings .......................... ........................................ ................ ..2-61 2-61

2.3.14.2

Overview of Elastomeric Flexible Shaft Couplings ............ .......................... .......................2-62 .........2-62

PREVENTIVE MAINTENANCE MAINTENANCE FOR COAL HANDLING SYSTEM COMPONENTS COMPONENTS ...........3-1 3 PREVENTIVE

3.1

General Guidance...................... Guidance................................... .......................... ........................... ........................... .......................... ........................... ................3 ..3-1 -1

3.1.1

3.1.1.1

Predictive Maintenance........................... Maintenance........................................ ........................... ........................... ...........................3-2 ..............3-2

3.1.1.2

Periodic Maintenance ............ .......................... ............................ ........................... ........................... ........................... ................3-2 ...3-2

3.1.2 3.2

Preventive Maintenance......................... Maintenance....................................... ............................ ........................... ........................... ....................3-1 ......3-1

Corrective Maintenance ............ .......................... ........................... ........................... ........................... ........................... ....................3-3 ......3-3

Coal Handling System Component Maintenance Guidance ........................... ........................................3-4 .............3-4

3.2.1

Belt Scales ............ .......................... ........................... ........................... ........................... .......................... ........................... ...........................3-4 .............3-4

3.2.1.1

General Preventive Maintenance Guidance ........................... ........................................ ......................3-4 .........3-4

3.2.1.2

NIST Preventive Maintenance Guidance ............................ .......................................... ..........................3-6 ............3-6

3.2.2


3.2.2.1


3.2.2.2

Turnover Railcar Dumper............................. Dumper........................................... ............................ ........................... ...................3-10 ......3-10

3.2.2.3

Train Positioner......................... Positioner....................................... ........................... ........................... ........................... .........................3-11 ............3-11 xi

3.2.2.4

Traveling Hammermill ............ .......................... ............................ ........................... ........................... ........................... ............... 3-13

3.2.2.5

Stationary Barge Unloader............................. Unloader........................................... ............................ ........................... .................3-15 ....3-15

3.2.2.6

Bucket Barge Unloader............ Unloader ......................... ........................... ............................ ........................... ..........................3-16 .............3-16

3.2.3


3.2.4


3.2.4.1

Lock-Out/Tag-Out Procedure.............................. Procedure............................................ ............................ ..........................3-18 ............3-18

3.2.4.2

Housekeeping ........................... ........................................ ........................... ............................ ........................... .........................3-18 ............3-18

3.2.4.3

Daily Walk Through............................. Through.......................................... ........................... ........................... ........................... ................ ..3-19 3-19

3.2.4.4

Periodic Maintenance ............ .......................... ............................ ........................... ........................... ........................... ............... 3-20

3.2.5

Coal Crushers ............ ......................... ........................... ........................... ........................... ........................... .......................... ....................3-25 .......3-25

3.2.5.1


3.2.5.2

Cage Mills ............ .......................... ........................... .......................... ........................... ........................... ........................... ....................3-26 ......3-26

3.2.5.3

Granulators .......................... ....................................... ........................... ........................... .......................... ........................... ..................3-27 ....3-27

3.2.5.4

Hammermills ........................... ........................................ .......................... ........................... ........................... .......................... ............... ..3-30 3-30

3.2.6


3.2.7


3.2.8


3.2.9


3.2.9.1

Cleaning and Washdown Procedures.............. Procedures ............................ ............................ ............................ ................ 3-35

3.2.10

Dust Control System ............................ ......................................... ........................... ............................ ........................... ...................3-36 ......3-36

3.2.11


3.2.11.1

General Guidance.............. Guidance ............................ ........................... ........................... ........................... ........................... .................3-38 ...3-38

3.2.11.2

Periodic Maintenance ............ .......................... ............................ ........................... ........................... ..........................3-38 ............3-38

3.2.11.3

Additional Preventive Maintenance Actions............. Actions ........................... ............................ ...................3-41 .....3-41

3.2.11.4

Cleaning Belts and Conveyor Components ........................... ......................................... ...................3-42 .....3-42

3.2.12

Movable Tripper Devices............................... Devices............................................. ............................ ........................... .......................3-43 ..........3-43

3.2.13

Gearboxes............. Gearboxes .......................... ........................... ........................... .......................... ........................... ........................... ........................3-45 ...........3-45

3.2.13.1

Condition Monitoring of Gearbox Gearbo x Assemblies.............. Assemblies ........................... ........................... ................ ..3-45 3-45

3.2.13.2

Preventive Maintenance Activities ........................... ........................................ ........................... ....................3-48 ......3-48

3.2.14

Flexible Shaft Couplings..................... Couplings.................................. ........................... ........................... ........................... ......................3-53 ........3-53

3.2.14.1

Lubricated Couplings (Grid and Gear Types) ........................... ......................................... ................ ..3-53 3-53

3.2.14.2 Metallic Element Nonlubricated Couplings (Elastomeric, Disk, and Diaphragm) .......................... ....................................... ........................... ........................... .......................... ........................... ........................... ...................3-54 ......3-54

xii

4 PREVENTIVE PREVENTIVE MAINTENANCE BASIS............................ BASIS......................................... .......................... ........................... ........................... ............... 4-1

4.1

Background.................................. Background..................... ........................... ............................ ........................... ........................... ........................... .........................4-1 ............4-1

4.2

Failure Locations, Degradation Mechanisms, and PM Strategies ........................... ...............................4-2 ....4-2

4.3

PM Tasks and Their Degradation Mechanisms ............ .......................... ............................ ............................ .................4-17 ...4-17

4.4

Preventive Maintenance Template .......................... ........................................ ........................... ........................... .......................4-29 .........4-29

4.5

Description of Preventive Maintenance Tasks................................... Tasks................................................. ........................4-31 ..........4-31

5 REPAIR REPAIR AND REPLACEMENT FOR COAL HANDLING SYSTEM COMPONENTS ...........5-1

5.1

General Guidance...................... Guidance................................... .......................... ........................... ........................... .......................... ........................... ................5 ..5-1 -1

5.1.1

Quantifiable Factors for Economic Cost Study .................................... .................................................. ................ 5-4

5.1.2

Key Qualitative Factors in the Decision-Making Process................................... Process..................................... 5-5

5.2

Repair and Replacement of Coal Handling System Components ............................ ...............................5-5 ...5-5

5.2.1

Belt Scales ............ .......................... ........................... ........................... ........................... .......................... ........................... ...........................5-6 .............5-6

5.2.2


5.2.2.1


5.2.2.2

Train Positioner........................ Positioner...................................... ........................... .......................... ........................... ........................... ............... ..5-8 5-8

5.2.2.3

Traveling Hammermill ............ .......................... ............................ ........................... ........................... ........................... ................5-9 ...5-9

5.2.2.4

Stationary Barge Unloader............................. Unloader........................................... ............................ ........................... .................5-10 ....5-10

5.2.2.5

Bucket Barge Unloader............ Unloader ......................... ........................... ............................ ........................... ..........................5-11 .............5-11

5.2.3


5.2.4


5.2.5

Crushers....................... Crushers..................................... ........................... .......................... ........................... ........................... .......................... ..................5-13 .....5-13

5.2.5.1


5.2.5.2

Cage Mills ............ .......................... ........................... .......................... ........................... ........................... ........................... ....................5-14 ......5-14

5.2.5.3

Granulators .......................... ....................................... ........................... ........................... .......................... ........................... ..................5-15 ....5-15

5.2.5.4

Hammermills ........................... ........................................ .......................... ........................... ........................... .......................... ............... ..5-16 5-16

5.2.6


5.2.7


5.2.8


5.2.8.1

Procedure for Adjusting the the Tracking/Tension of the Self-Cleaning Belt ....5-19

5.2.9


5.2.10

Dust Control System ............ .......................... ........................... ........................... ............................ ........................... .....................5-21 ........5-21

5.2.11


5.2.11.1

Tracking Procedure for Conveying Systems.............................. Systems............................................ ................ 5-22

5.2.11.2

Belt Splicing: Centerline Method ............ ......................... ........................... ............................ ........................5-23 ..........5-23 xiii

5.2.12

Movable Tripper Devices............................... Devices............................................. ............................ ........................... .......................5-25 ..........5-25

5.2.13

Gearboxes ............ .......................... ........................... .......................... ........................... ........................... .......................... ......................5-26 .........5-26

5.2.13.1

Typical Procedure for Gearbox Disassembly............... Disassembly............................. ............................ ................ 5-26

5.2.13.2

Inspection and Maintenance of Gears ........................... ......................................... ...........................5-30 .............5-30

5.2.13.3

Maintenance of Bearings ........................... ......................................... ........................... ........................... ....................5-32 ......5-32

5.2.13.4

Typical Procedure for Gearbox Reassembly ............ .......................... ............................ ..................5-34 ....5-34

5.2.14

Flexible Shaft Couplings........................ Couplings..................................... ........................... ............................ ........................... ............... ..5-37 5-37

5.2.14.1

Maintaining Proper Fits Associated with Couplings ........................... ..................................5-37 .......5-37

5.2.14.2

Maintaining Alignment of Couplings................................ Couplings.............................................. ..........................5-43 ............5-43

5.2.14.3

Installation of Couplings............. Couplings ........................... ........................... ........................... ............................ ......................5-43 ........5-43

5.2.14.4

Balancing of Couplings ............................ .......................................... ............................ ............................ .....................5-45 .......5-45

6 COAL HANDLING SYSTEM/COMPONENT SYSTEM/COMPONENT TROUBLESHOOTING TROUBLESHOOTING ............................ ....................................6-1 ........6-1

6.1

System Troubleshooting ........................... ......................................... ........................... ........................... ........................... ..........................6-1 .............6-1

6.1.1 6.2

Typical Coal Handling Systems ................................. .............................................. ........................... ............................6-4 ..............6-4

Troubleshooting Components Installed Installed in Coal Handling/Conveying Handling/Conveying Systems ...........6-5

6.2.1

Belt Scales ............ .......................... ........................... ........................... ........................... .......................... ........................... ...........................6-5 .............6-5

6.2.2


6.2.3

Unloading Hoppers ........................... ........................................ ........................... ........................... ........................... ..........................6-7 ............6-7

6.2.4

Sampling Equipment ........................... ........................................ ........................... ........................... .......................... ........................6-7 ...........6-7

6.2.4.1

Common Problems ............ .......................... ........................... .......................... ........................... ........................... .....................6-7 ........6-7

6.2.4.2

Determining the Location of Problems............ Problems .......................... ........................... ........................... ...................6-9 .....6-9

6.2.4.3

Using the Operator Interface to Locate Problems............ Problems .......................... ...........................6-10 .............6-10

6.2.4.4

Resolving Problems ............ .......................... ........................... ........................... ............................ ........................... .................6-10 ....6-10

6.2.5

Coal Crushers ............ ......................... ........................... ........................... ........................... ........................... .......................... ....................6-11 .......6-11

6.2.6


6.2.7


6.2.8


6.2.9


6.2.10 Dust Control Systems ............................ ......................................... ........................... ........................... ........................... ...................6-20 .....6-20 6.2.11 Conveyor Belts, Pulleys, Idlers, and Rollers ............................ .......................................... .........................6-24 ...........6-24 6.2.12 Movable Tripper Devices ........................... ........................................ ........................... ............................ ........................... ............... 6-31 6.2.13 Gearboxes.........................................................................................................6-31

xiv

6.2.13.1

Abnormally High Temperature ........................... ........................................ ........................... ..........................6-33 ............6-33

6.2.13.2

Low Oil Pressure.............................. Pressure........................................... ........................... ............................ ........................... ................6-33 ...6-33

6.2.13.3

Unusual or Excessive Noise ............ .......................... ............................ ............................ ............................ ................ 6-34

6.2.13.4

Excessive Vibration............................. Vibration........................................... ........................... ........................... ...........................6-34 .............6-34

6.2.13.5

Foaming ........................... ........................................ ........................... ........................... .......................... ........................... ....................6-34 ......6-34

6.2.13.6

No Sensor Readings............ Readings .......................... ........................... ........................... ........................... ........................... ................ 6-34

6.2.14

Flexible Shaft Couplings........................ Couplings..................................... ........................... ............................ ........................... ............... ..6-35 6-35

6.2.14.1

Configuration of Rotational System ............................... ............................................. ...........................6-35 .............6-35

6.2.14.2

Material Incompatibility and Misapplication................ Misapplication.............................. ............................ .................6-40 ...6-40

6.2.14.3

Installation Practices ........................... ......................................... ............................ ............................ ..........................6-41 ............6-41

7 PERSONNEL PERSONNEL

7.1

QUALIFICATION, TRAINING, AND SAFETY ISSUES .......................... ..................................7-1 ........7-1

Personnel Qualification and Training ............................ .......................................... ........................... ........................... ....................7-1 ......7-1

7.1.1

Coal Handling System Operators............................ Operators......................................... ........................... ........................... .................7-1 ....7-1

7.1.2

First-Line Supervisors ............ .......................... ........................... ........................... ........................... ........................... .......................7-1 .........7-1

7.1.3

Coal Handling System Maintenance Personnel ............ ......................... ........................... .........................7-2 ...........7-2

7.2

Personnel Safety Issues .......................... ........................................ ............................ ........................... ........................... ...........................7-2 .............7-2

7.2.1

Belt Scales ............ .......................... ........................... ........................... ........................... .......................... ........................... ...........................7-3 .............7-3

7.2.2


7.2.3

Unloading Hoppers ........................... ........................................ ........................... ........................... ........................... ..........................7-3 ............7-3

7.2.4

Sampling Equipment ........................... ........................................ ........................... ........................... .......................... ........................7-3 ...........7-3

7.2.5

Coal Crushers ............ ......................... ........................... ........................... ........................... ........................... .......................... ......................7-4 .........7-4

7.2.6

Reclaim Hoppers.......................... Hoppers....................................... ........................... ........................... .......................... ........................... ..................7-4 ....7-4

7.2.7

Discharge Hopper Feeders ........................... ......................................... ........................... ........................... ...........................7-4 .............7-4

7.2.8

Magnetic Separators .......................... ........................................ ........................... ........................... ........................... ........................7-5 ...........7-5

7.2.9

Slide Gates........................ Gates..................................... ........................... ........................... .......................... ........................... ........................... ............... ..7-6 7-6

7.2.10 Dust Control Systems ........................... ........................................ .......................... ........................... ........................... ......................7-7 .........7-7 7.2.11 Conveyor Belts, Pulleys, Idlers, and Rollers ............................ .......................................... ...........................7-8 .............7-8 7.2.12 Movable Tripper Devices ........................... ........................................ ........................... ............................ ........................... ................7-9 ...7-9 7.2.13 Gearboxes......................... Gearboxes...................................... .......................... ........................... ........................... .......................... ........................... ................7-9 ..7-9 7.2.14 Flexible Shaft Couplings ........................... ......................................... ............................ ........................... ........................... ................ 7-10 8 INDUSTRY INDUSTRY

RESOURCES FOR COAL HANDLING SYSTEM TRAINING, CONSULTING, AND REPAIR.............. REPAIR ........................... .......................... ........................... ........................... .......................... ........................... ...................8-1 .....8-1 ........................................ ........................... ........................... .......................... ........................... ........................... .........................9-1 ............9-1 9 REFERENCES ........................... BIBLIOGRAPHY 10 BIBLIOGRAPHY

.......................... ........................................ ........................... ........................... ........................... ........................... ............................ ..................10-1 ....10-1

xv

....................................... ........................... ........................... .......................... ..................... ........ A-1 A LISTING OF KEY INFORMATION ..........................

A.1

Key O&M Cost Points ........................... ........................................ ........................... ........................... .......................... ........................... ................. ... A-1

A.2

Key Technical Technical Points .......................... ....................................... ........................... ............................ ........................... ........................... .................. .... A-2

A.3

Key Human Performance Points................................................................................. A-4

TRANSLATED TABLE OF CONTENTS ......................... ...................................... ........................... ........................... .......................... ............. B-1 B TRANSLATED

(French) ......................... ...................................... ........................... ........................... .......................... ........................... ........................... ..................... ........ B-2 Français (French) Japanese)........................ ............................ ........................... ........................... ........................... ........................... ............................ .................. .... B-17 日本語 (Japanese).......... Spanish) .......................... ....................................... ........................... ........................... ........................... ........................... .......................... ................. .... B-34 Español (Spanish)

xvi

LIST OF FIGURES Figure 1-1 Coal Handling System Isometric ............................ .......................................... ............................ ........................... ......................1-4 .........1-4 Figure 1-2 Coal Handling System Isometric ............................ .......................................... ............................ ........................... ......................1-5 .........1-5 Figure 1-3 Coal Handling System Isometric ............................ .......................................... ............................ ........................... ......................1-6 .........1-6 Figure 1-4 Scope and Content of This EPRI Report .......................... ........................................ ............................ ..........................1-8 ............1-8 Figure 2-1 Types of Coal ............................ .......................................... ............................ ........................... ........................... ............................ ........................2-2 ..........2-2 Figure 2-2 Coal Regions in the United States....................................... States..................................................... ............................ .......................2-5 .........2-5 Figure 2-3 2 -3 Belt Conveyor Scale Components................ Components.............................. ............................ ............................ ............................ ..................2-7 ....2-7 Figure 2-4 Rotary Railcar Dumper ............................ ......................................... ........................... ............................ ............................ ........................2-8 ..........2-8 Figure 2-5 Rotary Railcar Dumper Schematic .......................... ........................................ ............................ ............................ .....................2-9 .......2-9 Figure 2-6 Turnover Railcar Dumper .......................... ........................................ ............................ ............................ ............................ ...................2-10 .....2-10 Figure 2-7 2 -7 Train Railcar Positioner ............................ .......................................... ............................ ............................ ............................. ....................2-11 .....2-11 Figure 2-8 Rotary Railcar Indexer.............. Indexer ............................ ............................. ............................. ............................ ............................ .....................2-11 .......2-11 Figure 2-9 Traveling Hammermill............................. Hammermill........................................... ............................ ............................ ............................ ......................2-12 ........2-12 Figure 2-10 Continuous Barge Unloader ........................... ......................................... ............................ ............................ ..........................2-13 ............2-13 Figure 2-11 Movable Grab Bucket Barge Unloaders ............................ .......................................... ............................ .....................2-14 .......2-14 Figure 2-12 Unloading Hoppers: Elevation View ........................... ......................................... ............................ ........................... ............... 2-15 Figure 2-13 High-Flow, As-Received, Coal Sampling Configuration ............................ .......................................2-17 ...........2-17 Figure 2-14 Low- to Medium-Flow, As-Fired, Coal Sampling Configuration............................2-18 Figure 2-15 Primary Sweep-Type Sampling Machine ............................ .......................................... ............................ ...................2-19 .....2-19 Figure 2-16 Pennsylvania Roller-Mounted Bradford Breaker ............................ .......................................... ......................2-24 ........2-24 Figure 2-17 Pennsylvania Bradpactor with Screen Plates Removed to Show Rotor...............2-25 Figure 2-18 Cage Mill................................ Mill.............................................. ............................ ............................ ............................ ............................ .......................2-26 .........2-26 Figure 2-19 Cut-Away View of Granulator ............................ ......................................... ........................... ............................ ........................2-27 ..........2-27 Figure 2-20 Outline Drawing of Granulator ............................ .......................................... ............................ ........................... ......................2-27 .........2-27 Figure 2-21 Reversible Hammermill .......................... ........................................ ............................ ............................ ............................ ....................2-29 ......2-29 Figure 2-22 Reversible Hammermill for Coal .......................... ........................................ ............................ ............................ .....................2-30 .......2-30 Figure 2-23 Drawdown Reclaim Hopper.............. Hopper ............................ ............................ ............................ ........................... ..........................2-31 .............2-31 Figure 2-24 Cut-Away View of Drawdown Reclaim Hopper .......................... ........................................ ..........................2-31 ............2-31 Figure 2-25 Outdoor Storage Problems............. Problems ........................... ............................ ............................ ........................... ........................... ................ 2-32 Figure 2-26 Bottom View of a Vibratory Coal Feeder ........................... ......................................... ............................ .....................2-33 .......2-33 Figure 2-27 Outline View of a Suspended Vibratory Coal Feeder ............................. ...........................................2-34 ..............2-34

xvii

Figure 2-28 Self-Cleaning Overhead Magnetic Separator .......................... ........................................ ............................ ................ 2-35 Figure 2-29 Suspended Magnetic Separator Machine ............................ .......................................... ............................ ..................2-35 ....2-35 Figure 2-30 Mounting Options ........................... ......................................... ............................ ............................ ............................ ............................2-36 ..............2-36 Figure 2-31 Stationary Overhead Magnetic Separator Se parator ............................ .......................................... ............................ ..................2-37 ....2-37 Figure 2-32 Operation of a Stationary Overhead Magnet ............................ .......................................... ........................... ............... 2-37 Figure 2-33 Typical Rectifier Used with Electromagnetic Separators ............................ ......................................2-38 ..........2-38 Figure 2-34 Typical Roller-Type Slide Gate ........................... ......................................... ............................ ............................ ......................2-39 ........2-39 Figure 2-35 Typical Aggregate-Type Slide Gate ............................ .......................................... ............................ ............................2-40 ..............2-40 Figure 2-36 2-3 6 Aggregate Diverter Slide Gate................................... Gate................................................ ........................... ............................ ................ ..2-40 2-40 Figure 2-37 Seal Tite ® Slide Gate ........................... ......................................... ........................... ........................... ............................ ........................2-41 ..........2-41 Figure 2-38 Coal Unloading Station Dust Collection System................................. System............................................... ..................2-44 ....2-44 Figure 2-39 Typical Dust Collection System ........................... .......................................... ............................. ............................ ....................2-45 ......2-45 Figure 2-40 Typical Dust Collection Configuration Options ........................... ......................................... ..........................2-46 ............2-46 Figure 2-41 Typical Filter Access Options ........................... ......................................... ............................ ............................. ........................2-46 .........2-46 Figure 2-42 Typical Inlet Connection Options ........................... ......................................... ............................. ............................. ..................2-47 ....2-47 Figure 2-43 Corrugated Sidewall Belts ........................... ......................................... ........................... ........................... ............................ ................ ..2-48 2-48 Figure 2-44 2-4 4 Conveyor Belt System Components.................. Components................................ ............................ ............................ .......................2-49 .........2-49 Figure 2-45 Motor-Propelled Belt Tripper ............................ ......................................... ........................... ............................ .........................2-55 ...........2-55 Figure 2-46 Cable-Propelled Belt Tripper ............................ ......................................... ........................... ............................ .........................2-55 ...........2-55 Figure 2-47 2-4 7 Parallel-Shaft Gearbox ............................ .......................................... ........................... ........................... ............................ ....................2-57 ......2-57 Figure 2-48 Vertical Offset Parallel-Shaft Gear Drive Arrangements........................ Arrangements...................................... ................ 2-57 Figure 2-49 2-4 9 In-Line Parallel-Shaft Gear Gea r Drive.............. Drive ............................ ............................ ............................ ............................ ..................2-58 ....2-58 Figure 2-50 Right-Angle Bevel Gear Drive Arrangement...................... Arrangement.................................... ............................ .....................2-58 .......2-58 Figure 2-51 Bevel Helical Gear Drive .......................... ........................................ ............................ ............................ ............................ ..................2-59 ....2-59 Figure 2-52 Bevel Planetary Gear Drive ........................... ......................................... ........................... ........................... ............................2-60 ..............2-60 Figure 2-53 Motor-Driven Gearbox for a Coal Conveyor .......................... ........................................ ............................ .................2-60 ...2-60 Figure 3-1 Sectional Drawing of a Granulator...................... Granulator.................................... ............................ ............................ ........................3-28 ..........3-28 Figure 3-2 Elements of a Preventive Maintenance Program for Gearboxes ...........................3-49 ...........................3-49 Figure 5-1 Generic Repair vs. Replace Evaluation ........................... ......................................... ............................ ...........................5-2 .............5-2 Figure 5-2 Factors Considered During the Decision-Making Process ........................... .......................................5-3 ............5-3 Figure 5-3 Configuration for Adjusting Magnetic Separator Belt Tracking/Tension .................5-20 .................5-20 Figure 5-4 Tooth Contact Patterns................................ Patterns.............................................. ............................ ............................ ............................ .................5-31 ...5-31 Figure 6-1 Generic Process for System Troubleshooting (Preliminary Evaluation)...................6-2 Figure 6-2 Generic Process for System Troubleshooting (Detailed System Troubleshooting) ............................. ........................................... ............................ ............................ ............................ ............................ .......................... .............. 6-3

xviii

LIST OF TABLES Table 2-1 Overview of Metallic Flexible Shaft Couplings............. Couplings ........................... ............................ ............................ ................ ..2-61 2-61 Table 2-2 Overview of Elastomeric Flexible Shaft Couplings ............................ .......................................... ......................2-63 ........2-63 Table 3-1 Recommended Preventive Maintenance for Belt Scales.................................. Scales...........................................3-7 .........3-7 Table 3-2 Recommended Preventive Maintenance for Rotary Railcar Dumpers ......................3-9 ......................3-9 Table 3-3 Recommended Preventive Maintenance for Turnover Railcar Dumpers.................3-11 Dumpers.................3-11 Table 3-4 Recommended Preventive Maintenance for a Train Positioner System.................. System..................3-11 3-11 Table 3-5 Recommended Preventive Maintenance for Traveling Hammermills......................3-14 Table 3-6 Recommended Preventive Preventive Maintenance for Stationary Barge Unloaders .............. ..............3-16 3-16 Table 3-7 Recommended Preventive Maintenance for Bucket Barge Unloaders....................3-17 Table 3-8 Recommended Preventive Preventive Maintenance for Coal Unloading Hoppers ...................3-18 ...................3-18 Table 3-9 Recommended Preventive Maintenance for Coal Sampling Equipment .................3-20 .................3-20 Table 3-10 Recommended Preventive Maintenance for Breakers/Compactors......................3-25 Table 3-11 Recommended Preventive Maintenance for Cage Mills ........................... ........................................3-27 .............3-27 Table 3-12 Recommended Preventive Maintenance for Granulators ........................... ......................................3-28 ...........3-28 Table 3-13 Recommended Preventive Maintenance for Hammermills ............................ ....................................3-30 ........3-30 Table 3-14 Recommended Preventive Maintenance for Vibratory Drawdown Reclaim Hoppers................................ Hoppers.............................................. ............................ ............................ ............................ ............................ ............................ ......................3-31 ........3-31 Table 3-15 Recommended Preventive Maintenance for Discharge Hopper Feeders..............3-32 Feeders..............3-32 Table 3-16 Recommended Preventive Maintenance for Magnetic Separators........................3-34 Separators........................3-34 Table 3-17 Recommended Preventive Maintenance for Slide Gates ........................... ......................................3-35 ...........3-35 Table 3-18 Recommended Preventive Maintenance for Dust Collection Equipment ..............3-37 Table 3-19 Recommended Preventive Maintenance Inspections for Conveyor Belt Systems ........................... ......................................... ............................ ........................... ........................... ............................ ............................ ........................ .............3-39 ...3-39 Table 3-20 Recommended Preventive Maintenance for Motor-Propelled Belt Trippers..........3-43 Table 3-21 Recommended Preventive Maintenance for Cable-Propelled Belt Trippers..........3-44 Table 3-22 Types of Thermocouples ............................ .......................................... ............................ ............................ ............................ .................3-46 ...3-46 Table 3-23 Preventive Maintenance Schedule Overview ........................... ......................................... ............................ ................ 3-50 Table 4-1 Failure Locations, Degradation Mechanisms, and PM Strategies for Coal Handling System Components................... Components................................. ............................ ............................ ............................ ........................... ................4-4 ...4-4 Table 4-2 PM Tasks and Their Degradation Mechanisms for Coal Handling System Components.............. Components ............................ ........................... ........................... ............................ ............................ ............................ ............................ ....................4-18 ......4-18 Table 4-3 PM Template for Coal Handling System Components ............................ .......................................... ................4-3 ..4-30 0

xix

Table 5-1 Recommended Repairs and Replacements for Belt Scales ............................. ......................................5-6 .........5-6 Table 5-2 Recommended Repairs and Replacements for Rotary Railcar Dumpers..................5-6 Dumpers..................5-6 Table 5-3 Recommended Repairs and Replacements for Train Positioners.............................5-8 Table 5-4 Recommended Repairs and Replacements for a Traveling Hammermill..................5-9 Table 5-5 Recommended Repairs and Replacements for a Stationary Barge Unloader.........5-10 Table 5-6 Recommended Repairs and Replacements for a Bucket Barge Unloader..............5-11 Table 5-7 Recommended Repair and Replacement Activities for Coal Sampling Equipment .......................... ........................................ ............................ ............................ ........................... ........................... ............................ ....................... ........... ..5-12 5-12 Table 5-8 Recommended Repair and Replacement Activities for Breakers/HybridBreakers............. Breakers .......................... ........................... ............................ ............................ ............................ ............................ ............................ ....................... .............5-13 ....5-13 Table 5-9 Recommended Repair and Replacement Activities Activities for Cage Mills .........................5-14 .........................5-14 Table 5-10 Recommended Repair and Replacement Activities for Granulators......................5-15 Granulators......................5-15 Table 5-11 Recommended Repair and Replacement Activities for Hammermills ...................5-16 ...................5-16 Table 5-12 Recommended Repairs and Replacements for Vibratory Drawdown Reclaim Hoppers................................ Hoppers.............................................. ............................ ............................ ............................ ............................ ............................ ......................5-17 ........5-17 Table 5-13 Recommended Repairs and Replacements for Discharge Hopper Feeders.........5-18 Table 5-14 Recommended Repairs and Replacements for Magnetic Separators...................5-19 Table 5-15 Recommended Repairs and Replacements Replacements for Slide Gates ............................ .................................5-20 .....5-20 Table 5-16 Recommended Repairs and Replacements for Dust Collection Equipment..........5-21 Table 5-17 Recommended Repairs and Replacements for Motor-Propelled Belt Tripper Devices ........................... ......................................... ............................ ........................... ........................... ............................ ............................ ........................ ..............5-25 ....5-25 Table 5-18 Recommended Repairs and Replacements for Cable-Propelled Belt Tripper Devices ........................... ......................................... ............................ ........................... ........................... ............................ ............................ ........................ ..............5-26 ....5-26 Table 5-19 Recommended Tightening Torques ........................... ......................................... ............................ ........................... ............... ..5-36 5-36 Table 5-20 Table of Interferences.......................... Interferences........................................ ............................ ............................ ............................. ........................5-40 .........5-40 Table 5-21 Expressing Tapers.............. Tapers ............................ ............................. ............................. ............................ ............................ ..........................5-41 ............5-41 Table 6-1 Recommended Troubleshooting for Coal Handling/Conveying Handling/Conveying Systems ..................6-4 ..................6-4 Table 6-2 Recommended Troubleshooting for Coal Handling System Belt Scales...................6-5 Table 6-3 Recommended Troubleshooting for Vibratory Drawdown Reclaim Hoppers...........6-12 Table 6-4 Recommended Recommended Troubleshooting for Para-Mount Discharge Discharge Hopper Feeders ........6-13 Table 6-5 Recommended Troubleshooting for Para-Mount II Discharge Hopper Feeders......6-14 Table 6-6 Recommended Troubleshooting for Coal Handling System Magnetic Separators................................. Separators................... ............................ ............................ ........................... ........................... ............................ ............................ ..................6-16 ....6-16 Table 6-7 Recommended Troubleshooting for Slide Gates.............. Gates ............................ ............................ .........................6-18 ...........6-18 Table 6-8 Recommended Troubleshooting Troubleshooting for Dust Collection/Suppression Equipment ........6-20 Table 6-9 Recommended Troubleshooting for Conveyor Belt Systems ............................. ..................................6-24 .....6-24 Table 6-10 Recommended Troubleshooting for Belt Trippers ........................... ......................................... ......................6-31 ........6-31 Table 6-11 Troubleshooting Matrix for Gearboxes ........................... ......................................... ............................ .........................6-31 ...........6-31 Table 6-12 Detailed Troubleshooting Guidance for Flexible Mechanical (Gear and Grid) Couplings .......................... ........................................ ............................ ............................ ............................ ............................ ............................ ....................... ........... ..6-35 6-35

xx

Table 6-13 Detailed Troubleshooting Guidance for Flexible Metallic (Disk and Diaphragm) and Elastomeric Couplings.................................. Couplings................................................ ........................... ...........................6-38 ..............6-38 Table 6-14 Common Metallurgical Problems and Troubleshooting ............................ .........................................6-40 .............6-40 Table 6-15 Installation Practices Leading to Flexible Shaft Coupling Failure ..........................6-41 ..........................6-41 Table 7-1 Typical Expertise and Experience Level: Coal Handling System Operators .............7-1 Table 7-2 Typical Expertise and Experience Level: First-Line Supervisors...............................7-2 Table 7-3 Typical Expertise and Experience Level: First-Line System Maintenance Personnel .......................... ........................................ ............................ ............................ ............................ ............................ ............................ ....................... .............7-2 ....7-2 Table 8-1 Industry Resources for Coal Handling System Training, Consulting, and Repair................................. Repair............................................... ............................ ........................... ........................... ............................ ............................ ....................... .............8-2 ....8-2

xxi

1

INTRODUCTION

1.1

Purpose

This report provides maintenance personnel at fossil plants with guidelines on safe and effective maintenance practices for system components associated with coal unloading, sampling, and handling as the coal is conveyed into a fossil power plant.

1.2

Scope of Equipment and System Components

1.2.1 Overview of the Coal Handling System In a coal-fired power plant, the coal handling system provides the following functions: •

Unload the coal from railroad cars, dump trucks, barges, ships, and so on.

•

Weigh the coal received by the plant.

•

•

•

•

Transport (typically by conveyor belts) the coal from the unloading site to the crushing equipment, from the crushing equipment to an active coal pile or the interior of the plant, from the coal pile or plant to bunkers or silos, and, finally, from bunkers or silos to the coal feeders. Crush the coal so it can be moved by a conveyor system into the plant. The equipment used to crush the coal might be located at a point before or after the coal goes to the active coal pile and before the coal is moved into the plant. Separate tramp iron from the incoming coal. Store coal in bunkers or silos to provide an adequate supply of coal to the plant if a malfunction of the coal handling equipment should occur. The bunkers are sized to store a 12- to 24-hour supply of coal, sometimes more.

For stations with railroad delivery of coal, the cars are capable of holding 70–110 tons (64–100 metric tons) of coal. It is necessary to weigh the coal in each railroad car. This can be done using electronic scales on the track to weigh the car full, weigh the car empty, and then subtracting to find the weight of the unloaded coal. Also, the coal can be weighed on a scale below the unloading area grating or on belt scales along the conveyor.

1-1

Introduction

A locomotive or mechanical positioner is used to position the cars directly over the unloading hoppers. The cars can be unloaded from the bottom doors with car shakers to loosen the coal from the cars. The cars can also be turned upside down in a rotary dumper. From the unloading hoppers, the coal is transported to the crushers, where the coal is broken into smaller, finer particles. Coal sampling equipment is positioned near the conveyor belt to take uncrushed coal for testing. Typically, crushers are motor-driven equipment that use rolling rings or ring hammers to reduce the chunks of coal to pieces smaller than 1 in. (2.5 cm). The crushed coal is then placed on a series of conveyor belts propelled by a drum that is most typically coupled directly to the gear/speed reducer gearbox and a motor. The belt rests on idlers that are evenly spaced under the belt. In one scenario, these belts transport the coal to the active storage pile. Coal is temporarily stored on an active storage pile before being transported into the plant. Coal from the active storage pile gravitates into the active storage reclaim hopper. A vibrator feeder or variable-speed rotary feeder is located at the discharge of the hopper. Variable-speed rotary feeders provide improved control of the feed rate. The coal falls onto the conveyor and is transported into the plant. In another common scenario, the coal system allows the plant to be fueled directly from the train. This eliminates the need to run two conveyors to fuel the plant (that is, bypasses the reclaim system) and is done as often as possible for this reason. This coal handling configuration saves wear and tear on equipment and frees up operators. Many plants burn more than one type of coal for economic or environmental reasons. Coals with various sulfur contents or other characteristics might be blended to achieve the most effective mixture. Each type of coal is stored in separate piles and reclaimed at specific rates to achieve the desired blend. Reclaim conveyors under each pile release the coal onto the main conveyor that transports the coal into the plant. While being conveyed into the plant, the coal travels beneath a magnetic separator, which might be located in a crusher house or the plant itself. This device pulls out any metal material that can be attracted by a magnet, such as iron and steel. The transfer conveyor then unloads the coal onto a conveyor with a movable tripper device. The tripper device is positioned over each silo or bunker. Some plants use a cascade system of conveyors instead of a movable tripper. The coal then flows to a coal silo (circular shape with conical outlet) or a coal bunker (rectangular shape with a pyramidal outlet). The outlet from the silo or bunker is usually equipped with a fully enclosed slide gate. The slide gate can be manually operated or motor operated. There is usually one silo or bunker for each feeder and one feeder for each pulverizer mill. The coal moves through the silo or bunker, through the feeder, and then enters the pulverizer. Because of the strict regulations concerning fugitive dust emissions and the explosive nature of coal dust, dust control is required on the coal handling system. The dust control system might inject a water/chemical mixture at different points along the coal path. The dust control system 1-2

Introduction

might also use water to cover the surface of the coal on the belt. Other types of dust control include transfer chutes designed to direct the coal onto the belt at the same speed and angle of the belt to minimize dust creation. Additional control is obtained by using dry fogging systems or dust collectors. Some very dusty coals can require the addition of air-supported conveyors in place of the more conventional idler-supported conveyors. The air-supported conveyors use a cushion of lowpressure air to support the belts and are totally enclosed on the load side to reduce any dust creation.

1.2.2 Uniqueness of Each Coal Handling System Given the significant number of components comprising a typical coal handling system, it is safe to say that no two are exactly alike. The first differentiating factor is the means by which the coal is transported to the plant—by barge, railcar, trucks, or direct feed from the mine. Other factors affecting the design of the system and the components composing the system are the following: •

Types/blends of coal burned at the plant

•

Proximity of the unloading station to the plant

•

Geographical concerns and general terrain

Although no two systems are exactly alike with regard to the types, sizes, and models of components composing the system, the functions described in Section 1.2.1 are fairly common to all systems. As such, this report provides maintenance guidance on the following major groups of equipment, which tend to be common to all coal handling systems: •

Belt scales

•

Unloading equipment

•

Unloading hoppers

•

Sampling equipment

•

Coal crushers

•

Reclaim hoppers

•

Discharge hopper feeders

•

Magnetic separators

•

Slide gates

•

Dust control systems

•

Conveyor belts, pulleys, idlers, and rollers

•

Movable tripper devices

•

Gearboxes

•

Flexible shaft couplings 1-3

Introduction

Figures 1-1 through 1-3 illustrate the complexity of a typical coal handling system and the general proximity of the components to the plant.

Figure 1-1 Coal Handling System Isometric Courtesy of Eskom, Kendal Power Station

1-4

Introduction


1-5

Introduction


The following system components and/or topics are not within the scope of this report: •

Railroad cars

•

Locomotives

•

Trucks used in coal transportation

•

Barges

•

Bulldozers

•

Coal pile management

•

Coal bunkers or silos

1-6

Introduction

1.2.3 Using the Guidance in This Report Due to the unique nature of each coal handling system with regard to the sizes, types, and models of components installed, care should be taken when using the maintenance guidance provided in this report. Specifically, plant maintenance personnel should not use the guidance in this report to supersede the equipment-specific instructions that might have been provided for each station’s currently installed equipment. Instead, the maintenance guidance should be used as a template for establishing or enhancing a maintenance program at the station. Some of the guidance might not be applicable to all stations depending on the particulars of the equipment installed. Also, some of the detailed guidance might not be applicable in all cases due to the differences in a particular component’s design versus those components for which the guidance was compiled. The guideline does provide a sound technical basis on which to develop a preventive maintenance (PM) program; for each component included, it provides examples of PM activities, repair/replacement activities, and troubleshooting guidance, where applicable. Again, plant maintenance personnel should not use the guidance in this report in lieu of the equipmentspecific instructions that might exist for each station’s currently installed equipment.

1.3

Report Structure and Content Overview

Figure 1-4 illustrates the general structure and content of this technical report. The figure identifies key sections in the report that provide guidance to owners to effectively address coal handling system maintenance issues.

1-7

Introduction

Figure 1-4 Scope and Content of This EPRI Report

This section provides an introduction to the report, and Section 2 provides an overview of system design parameters and familiarizes the user with the components comprising a typical coal handling/conveying system and their functions. The focus of the report is Section 3, which provides guidance for performing PM on the numerous system components. Section 4 establishes a PM basis for components in a coal handling system. Section 5 discusses the many factors involved in determining whether to repair, replace, or defer maintenance on a system component, and provides guidance on repair and replacement. Section 6 provides the owner with troubleshooting guidance. Personnel qualification and safety guidelines are provided in Section 7, and Section 8 provides the user with sources of training, repair, and consulting services related to coal handling/conveying systems. A complete listing of references used during the development of this report is provided in Sections 9 and 10.

1.4

Glossary of Terms and Acronyms

1.4.1 Industry Definitions and Nomenclature Corrective maintenance – Maintenance tasks generated as a result of equipment failure. Corrective tasks are generated when equipment is purposely operated to failure and also when equipment failure is not desired or planned. It is the most basic form of maintenance and also the most expensive. Most plants are moving away from corrective maintenance, but there will always be some maintenance performed as a result of equipment failure.

1-8

Introduction

Elective maintenance – The classification of any work on power block equipment in which identified potential or actual degradation is minor and does not threaten the component’s design function or performance criteria. Facilities – Structures, systems, and components not associated with power generation. Structures can include training facilities, warehouses, maintenance shops, and administrative offices. Systems can include fire protection, plumbing, lighting, sewer, and drainage. Periodic maintenance – Time-based PM actions taken to maintain a piece of equipment within design operating conditions and to extend its life. Predictive maintenance – Maintenance tasks performed based on equipment condition. Predictive maintenance relies on technologies to determine the current condition of the equipment so that only the required maintenance is performed before equipment failure. Preventive maintenance – Maintenance tasks performed based on a time or interval basis to avoid catastrophic equipment failure. PM performs maintenance tasks on a planned rather than reactive basis and avoids the losses associated with unplanned downtime. The penalty of PM is that some tasks are performed that are unnecessary and costly. Proactive maintenance – Maintenance tasks that determine the root cause of an equipment problem. Chronic problems require advanced technologies, additional resources, and time to provide a final solution for an equipment problem. The problem can be the result of poor design, inadequate maintenance practices, or incorrect operating procedures. Qualified individual – For the purposes of concurrent verification and independent verification, a person who has been determined by station management to be qualified to perform verification activities. As a minimum, this individual shall be trained in human performance verification techniques. Work instructions – Instructions for performance of the work to be accomplished, the level of detail of which is dependent on the assigned planning level. When applicable, approved procedures might be referenced and might suffice as work instructions. Work order – A document used to control work and/or testing activities.

1.4.2 Acronyms ACAA

American Coal Ash Association Association

CAER

Center for Applied Energy Research

CARRC

Coal Ash Resources Research Consortium

CBRC

Combustion Byproducts Recycling Consortium

CCP

coal combustion products 1-9

Introduction

CPCA

Canadian Portland Cement Association

Cv

flow coefficient

EPRI

Electric Power Research Institute

ESP

electrostatic electrostati c precipitator

FGD

flue gas desulfurization

FMAC

Fossil Maintenance Applications Center

ICAR

International Center for Aggregates Research

ICCI

Illinois Clean Coal Institute

IGCC

integrated-gasification–combined-cycle

MRI

Material Research Institute

NIST

National Institute of Standards and Technology

NLGI

National Lubricating Grease Institute

NTEP

National Type Evaluation Program

O&M

operations and maintenance

OCDO

Ohio Coal Development Office

OEM

original equipment manufacturer

PM

preventive maintenance

psig

pound(s) per square inch gauge

scfm

static cubic feet per minute

SRM

Standard Reference Materials (program)

SSC

systems, structures, and components

tph

tons per hour

TR

technical report

1.5

Relationship with EPRI FMAC and to Other EPRI Reports

The development of this report was made possible through the close working relationship between the member fossil utility personnel and EPRI’s Fossil Maintenance Applications Center (FMAC). EPRI FMAC continues to serve as a key resource for maintenance personnel by providing a wide range of products, including technical reports addressing maintenance processes and system/equipment maintenance guidance, both with a focus on improving equipment reliability.

1-10

Introduction

1.5.1 Component Maintenance Guidance During the development of this report, EPRI products were identified that already provide detailed guidance regarding coal handling system components and their functions. These existing EPRI reports were primarily used as source material to ensure consistency of applied guidance among users. They include Gearbox and Gear Drive Maintenance Guide [1] and Flexible Shaft Couplings Maintenance Guide [2]. In addition, the following reports can be referred to in order to determine recommended PM activities for either commodity-type components installed in the coal handling system or for major fossil power plant components installed in other major systems: •

Ash Handling System Maintenance Guide [3]

•

Pulverizer Maintenance Guide, Volume 1: Raymond Bowl Mills [4]

•

Pulverizer Maintenance Guide, Volume 2: B&W Roll Wheel™ Pulverizers [5]

•

Pulverizer Maintenance Guide, Volume 3: Ball/Tube Mills [6]

•

Troubleshooting of Electric Motors [7]

•

•

Electric Motor Predictive and Preventive Maintenance Guide [8] Forced Draft and Induced Draft Fan Maintenance Guide [9]

•

Bearing Technology Topics, Volume 1: Various Var ious Technical Reports [10]

•

Bearing Technology Topics, Volume 2: Various Var ious Technical Papers [11]

•

Survey of the State of the Art of Coal Handling During Freezing Weather [12] [12]

1.5.2 Programmatic Maintenance and Process Guidance In addition to the EPRI reports noted under “Component Maintenance Guidance,” the following reports were identified that already provide programmatic and process-level guidance that supports the detailed component-level maintenance guidance contained in this report: •

Guideline for System Monitoring by System Engineers [13]

•

Lifting, Rigging, and Small Hoist Usage Program Guide [14]

•

Metrics for Assessing Maintenance Effectiveness [15]

•

System and Equipment Troubleshooting Guideline [16]

1-11

Introduction

1.6

Key Points

Throughout this report, key information is summarized in Key Points. Key Points are boldlettered boxes that succinctly restate information covered in detail in the surrounding text, making the key point easier to locate. The primary intent of a Key Point is to emphasize information that will allow individuals to take action for the benefit of their plant. The information included in these Key Points was selected by FMAC personnel, consultants, and utility personnel who prepared and reviewed this report. The Key Points are organized according to three categories: O&M Cost, Technical, and Human Performance. Each category has an identifying icon, as shown, to draw attention to it when quickly reviewing the guide. Key O&M C ost ost Point

Emphasizes information that will result in overall reduced costs and/or increase in revenue through additional or restored energy production. Key Technical Point

Targets information that will lead to improved equipment reliability. Key Human Perfor Perfor mance Point Point

Denotes information that requires personnel action or consideration in order to prevent personal injury, equipment damage, and/or improve the efficiency and effectiveness of the task.

The Key Points Summary section (Appendix A) of this guide contains a listing of all key points in each category. The listing restates each key point and provides a reference to its location in the body of the report. By reviewing this listing, users of this guide can determine if they have taken advantage of key information that the writers of this guide believe would benefit their plants.

1-12

2

INTRODUCTION TO COAL AND COAL HANDLING SYSTEM COMPONENTS

2.1

Coal Types and Characteristics

2.1.1 General Coal Characteristics The degree of change undergone by a coal as it matures from peat to anthracite—a process known as coalification—has an important bearing on its physical and chemical properties and is referred to as the rank of of the coal. Low-rank coals, such as lignite and subbituminous coals, are typically softer, friable materials with a dull, earthy appearance. They are characterized by high moisture levels and low carbon content and, therefore, a low energy content. High-rank coals are generally harder and stronger and often have a black vitreous luster. They contain more carbon, have lower moisture content, and produce more energy. Anthracite is at the top of the rank scale and has a correspondingly higher carbon and energy content and a lower level of moisture.

2.1.2 Categories and Ranks of Coal The term coal is used to describe a variety of fossilized plant materials, but no two coals are exactly alike. Heating value, ash melting temperature, sulfur and other impurities, mechanical strength, and many other chemical and physical properties must be considered when matching specific coals to a particular application. Coal is classified into four general categories, or ranks. They range from lignite through subbituminous and bituminous to anthracite, reflecting the progressive response of individual deposits of coal to increasing heat and pressure. The carbon content of coal supplies most of its heating value, but other factors also influence the amount of energy it contains per unit of weight. (The amount of energy in coal is expressed in British thermal units per pound. A Btu is the amount of heat required to raise the temperature of one pound of water one degree Fahrenheit, or 1 Btu/lb- °F = 4 kJ/kg- °K.)

2-1

Introduction to Coal Coal and Coal Handling Handling System Components Components

About 90% of the coal in the United States falls in the bituminous and subbituminous categories, which rank below anthracite and, for the most part, contain less energy per unit of weight. Bituminous coal predominates in the eastern and mid-continent coal fields, while subbituminous coal is generally found in the western states and Alaska. Lignite ranks the lowest and is the youngest of the coals. Most lignite is mined in Texas, but large deposits also are found in Montana, North Dakota, and some Gulf Coast states. Figure 2-1 compares the properties of the major classifications of coal.

Figure 2-1 Types of Coal Courtesy of the World Coal Institute

2.1.2.1

Anthracite Coal

Anthracite is coal with the highest carbon content—between 86% and 98%—and a heat value of nearly 15,000 Btu/lb (34.9 MJ/kg). Most frequently associated with home heating, anthracite is a very small segment of the U.S. coal market. There are 7.3 billion tons (6.6 billion metric tons) of anthracite reserves in the United States, found mostly in 11 northeastern counties in Pennsylvania. Anthracite is actually considered a metamorphic rock due to the process (high heat and pressure that stops just short of melting the sedimentary rock) that forms anthracite and distinguishes it from bituminous coal.

2-2


2.1.2.2

Bituminous Coal

The most plentiful form of coal in the United States, bituminous coal is used primarily to generate electricity and make coke for the steel industry. Bituminous coal in the United States is between 100 and 300 million years old. The fastest-growing market for coal, though still a small one, is supplying heat for industrial processes. Bituminous coal has a carbon content ranging from 45% to 86% carbon and a heat value of 10,500–15,500 Btu/lb (24.4–36 MJ/kg).

2.1.2.3

Subbituminous Coal

Ranking below bituminous is subbituminous coal with 35–45% carbon content and a heat value between 8,300 and 13,000 Btu/lb (19.3 and 30.2 MJ/kg). Most subbituminous coal in the United States is at least 100 million years old. Over 40% of the coal produced in the United States is subbituminous. Reserves are located mainly in a half-dozen western states and Alaska. Although its heat value is lower, this coal generally has a lower sulfur content than other types, which makes it attractive for use because it is cleaner burning.

2.1.2.4

Lignite Coal

Lignite is a geologically young coal that has the lowest carbon content (25–35%) and a heat value ranging between 4000 and 8300 Btu/lb (9.3 and 19.3 MJ/kg). Sometimes called brown coal, it is mainly used for electric power generation. Lignite coal tends to come from relatively young coal deposits that were not subjected to extreme heat or pressure. Lignite is crumbly and has high moisture content. About 8% of the coal produced in the United States is lignite, and most of it comes from Texas and North Dakota.

2.1.3 Chemistry of Coal Coal can be defined as a sedimentary rock that burns (although some consider anthracite to be more like metamorphic rock because of its formation under extreme heat and pressure). It was formed by the decomposition of plant matter, and it is a complex substance that can be found in many forms. Elemental analysis gives empirical formulas such as C 137H97O9NS for bituminous coal and C 240H90O4NS for high-grade anthracite.

Anthracite coal is a dense, hard rock with a jet-black color and a metallic luster. It contains between 86% and 98% carbon by weight, and it burns slowly, with a pale-blue flame and very little smoke. Bituminous coal, or soft coal, contains between 69% and 86% carbon by weight and is the most abundant form of coal. Subbituminous coal contains less carbon and more water, and is therefore a less efficient source of heat. Lignite coal, or brown coal, is a very soft coal that contains up to 70% water by weight.

2-3


2.1.4 Coal Hardness and Heating Values Coal is a solid fuel created from deposits of ancient vegetation that have undergone a series of metamorphic changes resulting from pressure, heat, submersion, and other natural formative processes occurring over a long period. Because of the different combinations of these processes acting on the vegetation and the widely differing forms of vegetation involved, coal is a complex and nonuniform substance. The formation of peat represents a pre-coal stage of development. After increased pressure and time, lignite begins to form. The next stage is subbituminous, followed by bituminous, and then anthracite. Each of these stages is characterized by an increase in the hardness of the coal. Anthracite is the hardest of the coals. Graphite represents a post-coal developmental stage and cannot be used for heating purposes. Coal is often classified into the four categories or ranks noted previously according to the degree of metamorphic change it has undergone. Anthracite is a clean, hard coal that burns with little or no luminous flame or smoke. It is difficult to ignite, but burns with a uniform, low flame once the fire is started. Anthracite contains approximately 14,440 Btu/lb (33.5 MJ/kg) and is used for both domestic and industrial heating purposes. Its major disadvantage as a heating fuel is its cost. Anthracite coal is divided by size into a number of different grades. Each of these grades (for example, egg size, buckwheat size, and pea size) is suitable for a specific size firepot. The term bituminous coal actually covers a whole range of coals, many of which have widely differing combustion characteristics. Some of the coals belonging to this classification are hard, whereas others are soft. A great amount of smoke will result if it is improperly fired. The available heat for bituminous coal ranges from a low of 11,000 Btu/lb (25 MJ/kg) for Indiana bituminous to a high of 14,100 Btu/lb (32.8 MJ/kg) for Pocahontas bituminous. The heat value of the latter approximates that of anthracite (about 14,400 Btu/lb [33.5 MJ/kg]); however, unlike anthracite coal, it is available in far greater supply, a factor that makes it a very economical solid fuel. Subbituminous coal is a soft coal that ignites slowly and burns with a medium-length flame. Because it produces so little smoke, it is sometimes referred to as smokeless coal. Lignite (sometimes referred to as brown coal) ignites slowly, produces very little smoke, and contains a high degree of moisture. In structure, it is midway between peat and bituminous coal. Lignite contains approximately half the available heat of anthracite (or about 7400 Btu/lb [17.2 MJ/kg]), and burns with a long flame. Its fire is almost smokeless, and it does not coke, a characteristic it shares with anthracite. Lignite is considered a low-grade fuel, and its calorific value is low when compared with the other coals. Moreover, it is difficult to handle and store.

2-4


2.2

Sources of Coal in the United States

Coal reserves are beds of coal still in the ground waiting to be mined. The United States has the world’s largest known coal reserves, about 275 billion short tons (250 billion metric tons). This is enough coal to last over 200 years at today’s level of use. Coal production is the amount of coal that is mined and sent to market. The United States produces over a billion short tons (over 907 million metric tons) of coal each year, over one-fifth of the world’s coal. Coal is mined in 27 states. Wyoming mines the most coal, followed by West Virginia, Kentucky, Pennsylvania, and Texas. Coal is mainly found in three large regions, the Appalachian coal region, the Interior coal region, and Western coal region (includes the Powder River Basin), as illustrated in Figure 2-2.

Figure 2-2 Coal Regions in the United States Courtesy of Department of Energy – Energy Information Administration

Appalachian coal region: •

The region annually produces about 35% of total U.S. coal production.

•

It contains large underground mines and small surface mines.

•

Coal mined in the Appalachian coal region is primarily used for steam generation for electricity and metal production and for export.

2-5


Interior coal region: •

The region annually produces approximately 13% of total U.S. coal production.

•

It contains mid-sized surface mines.

•

It contains mid- to large-sized companies.

Western coal region: •

•

•

The region annually produces about 52% of total U.S. coal production. Wyoming produces more coal than any other state and accounts for over 30% of total U.S. coal production. The region contains large surface mines and the largest coal mines in the world.

2.3

Introduction to Coal Handling System Components

This section provides a tutorial regarding the major components comprising a coal handling conveying system installed at fossil power plants, and design features/functions associated with each of them.

2.3.1 Belt Scales A belt conveyor scale is a device that measures the rate at which bulk material (coal, for example) is conveyed and delivered on a moving conveyor belt. Further, it can compute the total mass of coal conveyed over a given period. Belt conveyor scales provide a means of weighing bulk material while in motion. The obvious advantage over static weigh systems is that the flow of material need not be interrupted. As in batch weighing, accurate sensing of the weight of material is required. Belt conveyor scales also require accurate sensing of the motion of the bulk material. The weight on the conveyor belt is measured by sensing the force on one or more conveyor idlers. The motion of the material is measured by sensing travel of the belt with a device that produces an output representing a fixed distance of belt travel. Because the measured force represents weight per unit length (for example, kg/m or lb/ft), it can be multiplied by the belt travel to acquire total weight (for example, kg/m x m = kg; lb/ft x ft = lb). This function can be accomplished with an electromechanical or electronic integrator. With proper scaling, total weight can be measured in tons, long tons, or metric tons (1 long ton = 2240 lb, 1 short ton = 2000 lb, 1 metric ton = 2204 lb). In addition to displaying total weight passed over the belt conveyor scale, most modern integrators also display instantaneous rate (that is, kg/hour or tons/hour) and provide transmitted outputs for remote monitoring and control requirements. Most viable belt conveyor scale systems operate by the mentioned method of measuring weight per unit length and multiplying that by belt travel to determine total material 2-6


weight. To provide a better understanding of the theory of operation of all belt conveyor scales, the following sections describe the individual components of a conveyor scale system. The basic components of a belt conveyor scale are shown in Figure 2-3, with descriptions of their functions following.

Figure 2-3 Belt Conveyor Scale Components Courtesy of Thermo Electron Corporation

Scale carriage (scale suspension) – This component transmits the forces resulting from the belt load and directs those forces to the load sensor(s). Load sensor – Each load sensor transduces the load force to a form acceptable to the mass totalizer. Belt travel speed pickup – This component contacts the belt and transmits belt travel (speed) to the speed sensor. Belt travel (speed) sensor – This component transduces the belt travel (speed) to a form acceptable to the mass totalizer. Mass totalizer – This component, often referred to as an integrator , computes the total mass that has passed over the belt conveyor scale and indicates and records that value. Typically, the mass totalizer will also provide a mass flow rate indication.

2-7


2.3.2 Unloading Equipment

2.3.2.1

Rotary Railcar Dumper

The rotary railcar dumper is an efficient device for almost all railcar offloading applications, and is especially effective for high-speed automatic dumping of rotary-coupled cars. Typically custom designed, this cost-effective, all-purpose workhorse can be used for random car applications. The rotary railcar dumper requires low horsepower (typically around 150 hp) to operate the dumper. It can be employed in low or extremely high throughput plants. Dumping cycle times can be as fast as 30 seconds per car, and when used in a tandem configuration, tonnage throughput can reach 10,000-plus tons/hour (9078-plus metric tons/hour). Figure 2-4 illustrates a rotary railcar dumper.

Figure 2-4 Rotary Railcar Dumper Courtesy of Heyl & Patterson, Inc.

2-8


Most rotary railcar dumpers can be equipped with various accessory equipment, such as certifiable weigh scales, vibrators, car retarders, wheel chocks, and car-reading devices. Optional choices also exist for drives and clamping systems. Figure 2-5 is a schematic of a typical rotary railcar dumper and its various components.

Figure 2-5 Rotary Railcar Dumper Schematic Courtesy of Heyl & Patterson, Inc.

2.3.2.1.1

C-Shape Rotary Railcar Dumper Model CR

The C-shape rotary railcar dumper model, often referred to as the CR dumper , provides highspeed dumping of random and non-rotary-coupled cars. This machine is a variation on the basic rotary design with an open rear side. This dumper delivers low power advantages, fast cycle times, and maximum productivity when combined with multiple positioners or indexers to accurately spot cars for discharge. The system features automation in order to obtain high throughput capability.

2-9


2.3.2.2

Turnover Railcar Dumper

This machine is designed for low to moderate throughput applications of up to 15 cars per hour. The turnover railcar dumper is the choice when owners want to decrease costs and erection schedules due to site construction that calls for shallow foundations and track-level receiving hoppers. The turnover railcar dumper raises the car and discharges the load parallel to the track in an arcing movement, not an axial rotation like the rotary dumper. By using the turnover design, the pit can be as shallow as 26 ft (7.9 m). The turnover dumper uses more horsepower than the rotary-style dumper, however. Figure 2-6 illustrates a typical turnover railcar dumper in operation.

Figure 2-6 Turnover Railcar Dumper Courtesy of Heyl & Patterson, Inc.

2.3.2.2.1

C-Shape Turnover Railcar Dumper Model CT

The C-shape turnover is a variation of the standard turnover design. The open rear truss, opposite the spill side, permits side-arm-positioning equipment access to accurately spot random cars within the machine. By employing the C-shape design along with indexing and positioning equipment, the railcar handling can be automated for increased throughput.

2.3.2.3

Train Positioner

The train positioner is typically employed in high-capacity, rotary-coupled, unit train applications, where fast, automatic cycle times can eliminate the need for operator intervention. Durable and efficient, the train positioner is capable of moving a loaded train or car for a precise distance at variable speeds. This powerful device can move entire trains for unloading in conjunction with rotary dumpers; train lengths as long as 200 cars have been accommodated. The train positioner can be driven with wire rope or rack and pinion. The positioner can be retrofit into existing installations. Figure 2-7 illustrates a train positioner. 2-10


Figure 2-7 Train Railcar Positioner Courtesy of Heyl & Patterson, Inc.

2.3.2.4

Railcar Indexer

Designed for up to 30 railcars in a string, the railcar indexer should be considered when the job is to handle both rotary-coupled cars and random car applications. The indexers move a car or string of cars onto the dumper for semiautomatic operation and eliminate the need for locomotive assistance during offloading. Indexers can be completely automated or manually controlled. The indexer can be retrofit into existing installations. Figure 2-8 illustrates a train railcar indexer.

Figure 2-8 Rotary Railcar Indexer Courtesy of Heyl & Patterson, Inc.

2-11


2.3.2.5

Traveling Hammermill

The traveling hammermill, which has seen deployment in many coal handling applications, is designed to eliminate the problem of frozen or oversized material, which can block openings in the screen (the screen is commonly referred to as the grizzly). Delays are minimized when the hammermill’s hammers, mounted on a rotating shaft, traverse the hopper below a car dumper and break up oversized or frozen material. Fully automated, this labor-saving machine maintains high offloading rates for lumpy or frozen material. Each machine is engineered to fit a specific application and can be fit to any new or existing dumper system. Figure 2-9 illustrates a traveling hammermill.

Figure 2-9 Traveling Hammermill Courtesy of Heyl & Patterson, Inc.

2.3.2.6

Continuous Barge Unloader

The continuous barge unloader (CBU) is designed to unload materials such as coal from barges at digging rates of up to 5000 tons/hour (4539 metric tons/hour). This extremely efficient machine maintains a much higher average offloading rate than other types of barge unloaders, although horsepower requirements are less than in pneumatic systems. The CBU is very easy to operate, does not degrade fragile products, and can be installed quickly due to modular construction. Dust collection units are optional. Figure 2-10 illustrates a CBU.

2-12


Figure 2-10 Continuous Barge Unloader Courtesy of Heyl & Patterson, Inc.

2.3.2.7

Grab Bucket Barge Unloader

Grab-style unloaders achieve free digging rates of up to 1500 tons/hour (1362 metric tons/hour). The grab bucket unloader has been field-proven to offer maximum availability when compared to other low- to mid-capacity barge unloaders. They are environmentally sound and can accommodate dust suppression or collection systems. Grab bucket barge unloader designs include stationary as well as traveling machines, and can be employed in complement with barge hauls. Figure 2-11 illustrates a pair of movable grab bucket barge unloaders.

2-13


Figure 2-11 Movable Grab Bucket Barge Unloaders Courtesy of Heyl & Patterson, Inc.

2.3.3 Unloading Hoppers Unloading hoppers are structures used for interim transfer of coal immediately after it is unloaded from the railcars, trucks, or barges. The hoppers are typically made of carbon steel plate (3/8- to 1/2-in. [9.5- to 12.7-mm] thick), with stiffeners to ensure that there is no deformation when fully loaded. The insides of the hoppers are often lined with stainless steel, the thickness of which varies depending on its relative position within the hopper. Figure 2-12 illustrates an elevation view of unloading hoppers installed inside a building as a means to contain the spread of coal dust.

2-14


Figure 2-12 Unloading Hoppers: Elevation View Courtesy of Roberts & Schaefer Company

At the discharge of the unloading hoppers are often installed vibratory feeder mechanisms to facilitate the even distribution and flow of coal discharging from the hoppers onto the conveying system. These feeder mechanisms are discussed in Section 2.3.7 of this report.

2.3.4 Sampling Equipment

2.3.4.1

Introduction to Coal Sampling

Sampling is a method of obtaining a smaller amount of material from a larger group, with the sample representing the characteristics of the larger group. If done correctly, this representative sample can be analyzed to determine the physical properties of the whole group. The relatively small size of the sample makes it much easier to perform tests on the sample than on the whole group. There are many reasons to sample coal and other bulk materials. With proper collection procedures, a sample can be used to determine any physical characteristic that is of interest for bulk material. Those characteristics can be used for process control, basis of payment, quality control, and to satisfy government regulations.

2-15


Sampling bulk materials can help determine the efficiency of the process and whether there need to be changes to the process to improve yields. Used correctly, information obtained from sampling bulk materials can help improve almost any process. Many times, a contract written between a seller and buyer of coal sets the price of the materials based on a physical characteristic other than weight. For example, coal is often paid for based on the amount of heat energy it contains. It is possible to estimate the amount of heat energy by measuring the number of tons delivered and using an assumed value for the heat energy per ton. However, there can be a lot of variability in coal. An estimate could easily be many percent off of the true value, which could add up to a significant amount of money over a one-year period. Key O&M C ost ost Point

Using a coal sampling system can help he lp ensure that the utility gets what it pays for and that the mine gets the amount of money the coal is worth.

It is important to define the meaning of automatic when talking about coal sampling systems. When speaking about sampling systems, automatic means that a central mechanism controls the timing of sampling-equipment operations. Nowadays, that almost always refers to a programmable logic controller (PLC). The central PLC for the sampling system typically has internal timers and logic that determine when and how long each piece of equipment will operate. The PLC also has functions that will purge and stop the sampling system if the main conveyor stops running. Another part of the automatic function of the sampling system is to shut down the sampling system if a failure is detected in one of the components. The opposite of automatic in this context would be manual. In a manual sampling system, there would be no timers to control when a sampler operates. In order to take a sample, operators would have to push a button each time they wanted to take a sample, and they would have to turn each piece of equipment on and off. What the term automatic does not mean is autonomous. The sampling system will not operate correctly without the oversight of trained and competent operators and maintenance personnel. In order to obtain the best performance, the sampling system requires routine inspections, cleaning, and maintenance, as described in Section 3 of this report.

2.3.4.2

Coal Sampling System Components

Figures 2-13 and 2-14 illustrate two common configurations for coal sampling systems and the typical components comprising a coal sampling system. Both figures illustrate a modular type of sampling system, which is very common at coal-fired power plants and includes two major modules—the primary sampling machine(s) and the self-contained sampling unit (SCSU).

2-16


Figure 2-13 illustrates a high-flow, as-received coal sampling configuration. In this system, coal is sampled at rates up to 6–7 thousand tons/hour (5.4–6.4 metric tons/hour) as it is received from the railcar, barge, or truck. The lot size then could be measured in terms of as-received tonnage (for example, 10,000 tons/railcar [9078 metric tons/railcar]). In this system configuration, located near the unloading equipment, approximately 5-in. (12.7-cm) coal is conveyed on large belts (for example, 60 in. [152.4 cm] wide).

Figure 2-13 High-Flow, As-Received, Coal Sampling Configuration Courtesy of Thermo Electron Corporation

Figure 2-14 illustrates a low- to medium-flow, as-fired coal sampling configuration. In this system, coal is sampled at rates less than 1000 tons/hour (907.8 metric tons/hour) as it is conveyed into the plant. The lot size then could be measured in terms of bunkered coal tonnage per 8-, 12-, or 24-hour shift. In this system configuration, located closer to the entry to the plant, approximately 2-in. (5.1-cm) coal is typically conveyed on dual medium-sized belts (for example, 24–48 in. [61–122 cm] wide).

2-17


Figure 2-14 Low- to Medium-Flow, As-Fired, Coal Sampling Configuration Courtesy of Thermo Electron Corporation

2.3.4.3

Primary Sampling Machine

The primary sampling machine is typically designed to accurately extract samples of dry, freeflowing coal from a moving conveyor belt. The sampler extracts sample increments by traveling through the flow of material on the conveyor. The amount of sample extracted can be varied by changing the frequency of passes through the material stream. Care should always be taken when adjusting sample extractions, as increasing the amount of sample taken could overload the sampling system and cause material plugging and equipment damage. Figure 2-15 illustrates a typical sweep-type primary sampling machine.

2-18


Figure 2-15 Primary Sweep-Type Sampling Machine Courtesy of Thermo Electron Corporation

2.3.4.4

Primary Belt Feeder

The primary belt feeder is designed to accurately feed materials at a predetermined rate or a variable rate, depending on application requirements. This feeder is commonly equipped with a variable-speed alternating current (ac) drive. This drive often incorporates a three-phase ac motor and gear reducer with a variable-frequency drive (VFD). By adjusting the frequency of the ac power delivered to the motor, the speed of the motor is changed. The feeder is equipped with a material shear gate that can be raised and lowered to control the depth of material on the belt. The proper setting for the gate is determined by the material size and extraction rates. The feeder is also commonly equipped with a zero-speed indicator. This device is used by the control system to identify problems with the feeder.

2.3.4.5

Coal Sampler Crusher

The crusher is designed to reduce coal to sizes conforming to the applicable American Society for Testing and Materials (ASTM) standard(s). The side housings typically have wear plates and breaker plates that need inspection every month. There are no adjustments to the plates. The crusher hammers and screens/grate bars are accessible and replaceable by opening the upper housing of the crusher.

2.3.4.6

Secondary Belt Feeder/Secondary Sweep Sampler

The secondary belt feeder is designed to accurately feed materials at a predetermined rate or a variable rate, depending on application requirements. This feeder is equipped with a mechanical variable-speed gear reducer. The variable-speed reducer uses an adjustable traction mechanism to vary the final reduction ratio. It can be adjusted by turning an adjustment dial on the top of the reducer. 2-19


Key Human Perfor Perfor mance Point Point

Never adjust a mechanical variable-speed reducer unless the feeder is running. Adjusting these reducers while not running could severely damage them.

The feeder is equipped with a material shear gate that can be raised and lowered to control the depth of material on the belt. The proper setting for the gate is determined by the material size and extraction rates. The feeder is equipped with a zero-speed indicator. This device is used by the control system to identify problems with the feeder. Like the primary sampler, the secondary sweep sampling machine is typically designed to accurately extract samples of dry, free-flowing coal from a moving conveyor belt. The sampler extracts sample increments by traveling through the flow of material on the conveyor. The amount of sample extracted can be varied by changing the frequency of passes through the material stream. Care should always be taken when adjusting sample extractions, as increasing the amount of sample taken could overload the sampling system and cause material plugging and equipment damage. The secondary sweep sampler is typically operated by a constant-speed chain-drive mechanism. The chain drive has a guide block assembly that reverses the output of the drive while the motor turns in one direction. A cutter assembly is attached to the output of the drive. The cutter is supported by and travels on support wheels. To take a sample increment, the sample cutter travels perpendicularly through the falling material stream. The material removed by the sample cutter is directed to the sample discharge chute while the rejected material is allowed to continue falling through the bottom of the sampler to the reject chute. Sample extraction rates can be changed by two methods. First, the cutter lips can be adjusted to increase or decrease the cutter opening. Keep in mind that the minimum opening should be three times larger than the largest particle size anticipated. The second method is to change the timer setting to increase or decrease the number of cuts taken in a given period.

2.3.4.7

Sample Collector

The sample can be collected either in a single-collection can or a multiple-can rotary carousel device containing multiple containers for the storage of dry, free-flowing material samples. The collector is designed to direct the final sample into one of the sample containers at the machine at any given time. The sample containers sit on a rotary platform. When one of the sample containers is full, the collector can be indexed to an empty one. This collecting machine is dust-tight and prevents sample contamination.

2-20


2.3.4.8

Reject Return Conveyor

The reject material is returned onto the main conveyor by either another belt, a bucket elevator, a screw conveyor, or tube conveyor. The reject return conveyor is designed to transport material at variable feed rates. It might have a trough belt with 35° troughing idlers. The conveyor typically has a fixed-speed drive, and is often equipped with a zero-speed indicator. This device is used by the control system to identify problems with the feeder.

2.3.4.9

Electrical Control Panel

The electrical control panel for the sampling system controls the operation of the entire sampling system. It most often will contain an industrial PLC, relays, fuses, power supplies, and other components for controlling the sampling system. Connected to the control panel is often a graphical operator interface. The operator interface provides the ability to change certain system timers and gives appropriate messages about the status of the sampling system. A size sampler is typically required when non-domestic coal is used at either a U.S. or international fossil power plant. For situations where a domestic fossil power plant was using U.S. coal, a size sampler would not typically be integral to the sampling system. A size sweep sampler is designed to accurately sweep samples of dry, free-flowing material off a conveyor belt. The sample cutter is operated by an electric brake motor through a speed reducer. The reducer is mounted on the shaft of the sample cutter. As the reducer output makes one full revolution, the sample cutter is moved through the material on the conveyor belt. The sample cutter removes material from the belt and discharges it out the side of the sampler. An adjustable brush assembly is provided on the back of the sample cutter to help remove all of the sample increment from the conveyor belt. A magnetic limit switch is used to determine when the cutter is located in the material stream. After the cutter has left the material stream, the limit switch signals for the motor to shut off and the brake stops the cutter outside of the material stream. The sample extraction rates are changed by increasing or decreasing the time interval between sample increments.

2.3.5 Coal Crushers

2.3.5.1

Mechanical Reduction Methods

There are four basic ways to reduce a material—by impact, attrition, shear, or compression—and most crushers employ a combination of all these crushing methods.

2-21


2.3.5.1.1

Impact

In crushing terminology, impact refers refers to the sharp, instantaneous collision of one moving object against another. Both objects might be moving, such as a baseball bat connecting with a fast ball, or one object might be motionless, such as a rock struck by a hammer. There are two variations of impact: gravity impact and dynamic impact. Coal dropped onto a hard surface such as a steel plate is an example of gravity impact. Gravity impact is most often used when it is necessary to separate two materials with relatively different friabilities. The more friable material is broken, while the less friable material remains unbroken. Separation can then be done by screening. Material dropping in front of a moving hammer (both objects in motion) illustrates dynamic impact. When crushed by gravity impact, the free-falling material is momentarily stopped by the stationary object. But when crushed by dynamic impact, the material is unsupported and the force of impact accelerates movement of the reduced particles toward breaker blocks and/or other hammers. Dynamic impact has definite advantages for the reduction of many materials and it is specified under the following conditions: •

•

•

•

When a cubical particle is needed When finished product must be well-graded and must meet intermediate sizing specifications, as well as top and bottom specifications When ores must be broken along natural cleavage lines in order to free and separate undesirable inclusions (such as mica in feldspars) When materials are too hard and abrasive for hammermills, but where jaw crushers cannot be used because of particle shape requirements, high moisture content, or capacity

2.3.5.1.2

Attrition

Attrition is a term applied to the reduction of a material by scrubbing it between two hard surfaces. Hammermills operate with close clearances between the hammers and the screen bars and they reduce by attrition combined with shear and impact reduction. Though attrition consumes more power and exacts heavier wear on hammers and screen bars, it is practical for crushing the less abrasive materials, such as coal.

Attrition crushing is most useful when material is friable or not too abrasive, or when a closedcircuit system is not desirable to control top size.

2-22


2.3.5.1.3

Shear

Shear consists of a trimming or cleaving action rather than the rubbing action associated with attrition. Shear is usually combined with other methods. For example, single-roll crushers employ shear together with impact and compression. Shear crushing is normally called for under these conditions: •

When material is somewhat friable and has a relatively low silica content

•

For primary crushing with a reduction ratio of 6:1

•

When a relatively coarse product is desired, usually larger than 1½ in. (38 mm) top size

2.3.5.1.4

Compression

As the name implies, crushing by compression is done between two surfaces, with the work performed by one or both surfaces. Jaw crushers using this method of compression are suitable for reducing extremely hard and abrasive rock. However, some jaw crushers employ attrition as well as compression and are not as suitable for abrasive rock, because the rubbing action accentuates the wear on crushing surfaces. As a mechanical reduction method, compression should be used as follows: •

If the material is hard and tough

•

If the material is abrasive

•

If the material is not sticky

•

•

Where the finished product is to be relatively coarse (for example, 1½ in. [38 mm] or larger top size) When the material will break cubically

2.3.5.2

Breakers

These machines are used for crushing, sizing, and cleaning run-of-mine coal and other friable materials. They are used to produce a product that is relatively coarse, with minimum fines, and that is 100% to size. Many breakers crush by gravity impact only. A large cylinder made of perforated screen plates is fitted with internal shelves. As the cylinder rotates, the shelves lift the feed and, in turn, the feed slides off the shelves and drops onto the screen plates below, where it shatters along natural cleavage lines. The size of the screen plate’s perforations determines the product size. Sized product falls through these perforations but oversized pieces will again be lifted and dropped by the shelves until they, too, pass through the screen plates. Tramp iron, lumber, or other uncrushable debris that enters the breaker along with the feed is transported to the discharge end of the cylinder. There, these uncrushables are scooped out continuously by a refuse plow, which channels this debris out of the cylinder and into a disposal bin. 2-23


Often a breaker will be used merely to clean debris from coal that has already been sized. This gives some indication of the economy of operation and versatility of this machine. Breaker cylinders rotate at slow speeds of 12–14 rpm depending upon cylinder diameter. Compared with most crushers, breakers are extremely long-lived. Screen plates, for example, frequently last 10 years or more, crushing millions of tons of coal, and there are numerous examples of breakers in continuous service for upwards of 40 years. Some manufacturers have also designed the screen plates in the breakers to be interchangeable so that the screen plates from the feed end, where wear is greatest, can be switched with screen plates from other areas of the cylinder where there is less wear. The profile of the perforations in the screen plates has been scientifically designed to obtain a maximum self-cleaning effect, without product bridging across the perforation itself. Figure 2-16 illustrates a roller-mounted Bradford Breaker, which is suited for coal mines where the feed often includes unusually large pieces of coal. This model will readily accept these larger pieces of coal without blocking the entry.

Figure 2-16 Pennsylvania Roller-Mounted Roller-Mounted Bradford Breaker Courtesy of Pennsylvania Crusher Corporation

The hybrid breaker is an innovation based on the breaker design and technology. In the hybrid breaker, the breaker cylinder is equipped with a rotor that is mounted with a series of paddle hammers. The rotor runs the entire length of the cylinder and the speed of the rotor can be varied. This gives operators the ability to tune the hybrid breaker to the type of friable material that is to be crushed. The paddles impact against the oversized material dropped into their path by the rotating cylinder. The paddles drive the material against the cylinder walls until the product is sized and screened out through the screen plate’s holes. 2-24


By varying the rotor speed, impact force as well as fines can be controlled. Compared with a breaker, a hybrid breaker gives greater capacity while occupying far less space than a conventional breaker. Figure 2-17 illustrates a Pennsylvania Bradpactor ® type of hybrid breaker, which can also be referred to as a compactor .

Figure 2-17 Pennsylvania Bradpactor Bradpactor with Screen Plates Removed to Show Rotor Courtesy of Pennsylvania Crusher Corporation

2.3.5.3

Cage Mills

This type of crusher is employed for size reduction of many types of friable, dry bulk substances, such as chemicals, grain, fertilizer, coal, slag, glass, soap, and many others. It is also used for beneficiation of materials that vary in hardness. In this type of equipment, material is reduced in size purely by impact. Feed enters the innermost cage, where it is initially struck by the first row of sleeves. The sleeves scatter the shattered material toward the next row, which rotates in the opposite direction. Further reduction occurs in each successive row until the material exits the final row, to be thrown against impact plates that line the crushing chamber. The sized material then discharges through the open bottom of the mill. For production of fine, medium, or coarse sizes, the spacing between sleeves on each row can be selected. Product size can also be changed by varying the speed of the cages. A typical configuration of a cage mill is illustrated in Figure 2-18.

2-25


Figure 2-18 Cage Mill Courtesy of Pennsylvania Crusher Corporation

2.3.5.4

Granulators

Granulators use rows of ring hammers, which crush with a slow, positive rolling action. This produces a granular product with minimum fines. Granulators come in many styles and sizes, and are used for crushing coals for power plants. Granulators crush by a combination of impact and rolling compression, producing high reduction ratios at high capacities. Product size is determined by screen openings, and is adjusted by changing the clearance between the cage and the path of the ring hammers. Some granulators can be provided with an external adjustment for the cage assembly, which is operable while the crusher is running. Granulators also have a tramp iron pocket for continuous removal of uncrushables from the crushing zone. Figures 2-19 and 2-20 give a cut-away view and outline drawing, respectively, of a typical granulator.

2-26


Figure 2-19 Cut-Away View of Granulator Courtesy of Pennsylvania Crusher Corporation

Figure 2-20 Outline Drawing of Granulator Courtesy of Pennsylvania Crusher Corporation

2-27


2.3.5.5

Hammermills

Hammermills are among the oldest, yet still most widely used, crusher designs. Although recent years have witnessed the introduction of new types of crushers, many are a refinement of the basic hammermill design to serve more specialized purposes. Most hammermills crush material in two stages: first, the material is reduced by dynamic impact; crushing then occurs by attrition and shear in the second zone, where small clearances exist between hammers and screen bars. This second zone is the final sizing zone for the product. A hammermill crushes material that is friable by impacting it against a rotating hammer (typically traveling between 750 rpm and 1800 rpm). Then the material is impacted against a rugged solid plate called a breaker plate that further degrades the particle size. Finally, the material is forced over a discharge grate by the hammers, where crushed finer particles drop through the discharge grate and larger particles travel around for another crushing cycle, until they fall through the discharge grid. During the entire time the material is traveling around in the hammermill, it is constantly impacted by the hammers and the grate assembly, causing breakage of the particles. This sequence repeats itself 750–1800 times each minute, until the particle is crushed fine enough to fall through the discharge grid. One big drawback to hammermills is that they wear, due to the abrasiveness of the material being crushed and the high speed of the mill. A hammermill should not be used to grind any material harder than a medium-hard limestone. Hammermills are used most in crushing coal, but are also common in limestone operations. Large particles cannot usually be crushed in hammermills, so they are almost never used for run-of-mine material or primary crushers, but secondary or tertiary crushers. A typical top size of feed for hammermills is 6–8 in. (15.2– 20.3 cm). On the positive side, hammermills are relatively inexpensive as crushers go, can produce relatively fine material (1/4 in. [6.4 mm] to -10-mesh) from 6–8 in. (15.2–20.3 cm) feed in one step, and they take up relatively little floor space. They are easily repaired and simple to operate. Production-size hammermills can generate output ranging from 1 in. (2.5 cm) to as fine as 10-mesh or finer, depending upon the material being crushed. One advantage of hammermills is their ability to produce the specified top size without the need for a closed-circuit crushing system. Hammermill crushing produces a cubical product with a minimum of flats and slivers, and is recommended when the material to be crushed is not unusually abrasive. In a hammermill, large particles cannot escape the cage bars until sized, resulting in great product uniformity with a minimum of oversize. Hammermills have high reduction ratios and will produce high capacities whether used for primary, secondary, or tertiary crushing. Cages can be adjusted to regulate product size, and a tramp iron pocket is standard on all models. Figure 2-21 illustrates a typical reversible hammermill configuration.

2-28


Figure 2-21 Reversible Hammermill Courtesy of Pennsylvania Crusher Corporation

Reversible hammermills are symmetrically designed crushers with a rotor that can be run clockwise or counterclockwise. Reversal of the rotor permits the operator to use the opposite face of the hammer daily for maximum hammer sharpness. This ability to reverse totally eliminates the requirement of manual hammer reversal. In addition to more effective use of the hammers, reversal also brings the opposing set of breaker blocks and screen bars into use. The user of a reversible hammermill has virtually two crushers in one machine, reversal being done with a simple motor switch. Some reversible hammermills are specifically designed for the reduction of pulverizer coals, cyclone fuel, and other finely crushed coal. To produce the smaller product sizes required, these models have more rows of hammers than are found in the reversible hammermills that might be used for stone or rock. The internal configurations of the coal and rock models differ, though the crushing actions are similar, as illustrated in the outline drawing provided in Figure 2-22.

2-29


Figure 2-22 Reversible Hammermill for Coal Courtesy of Pennsylvania Crusher Corporation

2.3.6 Reclaim Hoppers These types of hoppers are used to reclaim temporarily stored/piled coal for re-entry into the coal handling and conveying system. Some reclaim hoppers have no moving parts and are very similar to an unloading hopper. However, some reclaim hoppers, which are also known as drawdown hoppers, have electric-motor-driven vibratory mechanisms integral to their design. As shown in Figures 2-23 and 2-24, the drawdown hopper is a conical vibrating machine designed to promote flow of granular products from storage piles. It is not a device to control the rate of flow from a storage pile.

2-30


Figure 2-23 Drawdown Reclaim Hopper Courtesy of Carman Industries, Inc.

Figure 2-24 Cut-Away View of Drawdown Reclaim Hopper Courtesy of Carman Industries, Inc.

These types of hoppers use a single exciter, which imparts an elliptical stroke pattern in the horizontal plane. Through the use of a unique outer projection ring, these forces are transmitted into the storage pile at a 45 ° angle. The hopper uses a single foot-mounted motor and normal V-belts to drive a shaft-mounted eccentric weight to create all the drive forces. 2-31


Drawdown hoppers are a means to minimize and, in some cases, eliminate outdoor stockpile storage and reclaim problems. These problems include coring, bridging, and minimal active reclaim. Drawdown hoppers use vibratory action to transmit energy directly into the stockpile, encouraging sloughing into the flow stream and maximizing active reclaim. Figure 2-25 illustrates these various types of outdoor storage problems.

Figure 2-25 Outdoor Storage Problems Courtesy of Carman Industries, Inc.

Outdoor storage problems, including coring and bridging, are usually related to compaction resulting from one or more of the following conditions: •

High moisture

•

Heat or cold

•

Pressure of material on itself

•

Compaction caused by bulldozers and other material-handling equipment

•

Continuous operation of drawdown hoppers

Coring – Coring occurs when the material in the core of the pile discharges while material on the periphery resists movement. The projection ring of the drawdown hopper, which is always exposed to the pile, transmits vibration and energy directly into the pile. As the central column of flow is drawn down, fracture lines encourage sloughing into the flow stream, eliminating coring. Bridging – Bridging is the arch-like formation of material over either the static hopper inlet or outlet. It results from improperly designed hoppers or when the outlet is too small. Bridging also masks the location of the flow stream, a potentially dangerous condition for on-pile equipment operators. Drawdown hoppers have command of the material equal to the drawdown diameter. This results in an initial flow column equal to the inside diameter of the projection ring. A highly visible flow stream also improves the safety of on-pile equipment operators. Minimal active reclaim – By using a static hopper and feeder, active reclaim is limited to within approximately 40° of the stored material's natural angle of repose. Drawdown hoppers consistently increase active reclaim to within 5–10° of a material’s natural angle of repose. A properly designed drawdown hopper can provide four to five times the reclaim of an equally sized static hopper with a feeder.

2-32


2.3.7 Discharge Hopper Feeders Car dumper discharge hopper coal feeders are capable of providing over 1500 tons/hour (1362 metric tons/hour) of coal flow, which can vary depending on the type of coal used. Some feeders are equipped with variable-speed motors and drives, which control the flow of coal by varying the feeder motor speed. In other cases, the feeders are equipped with a constant-speed motor with variable counterweight wheels that are mounted on the ends of each motor (typically two per motor). In this design, coal flow is controlled by varying the position of the piston slug in each counterweight wheel. This increases or decreases the amplitude of vibration, thereby increasing or decreasing coal flow. An electrohydraulic control (EHC) system is often provided for positioning the piston slugs in the counterweight wheels. The EHC power unit typically consists of a pump with a small (1-hp) motor and a hydraulic reservoir. In some cases, two identical power units are installed (one for a backup) and are operated from the dumper control room through the distributed control system (DCS). Servo-amplifiers convert the coal flow control signal from the DCS into a 120-V ac signal, which is used to control the EHC converters. The EHC converters consist of an actuator and a hydraulic pressure regulator. Figures 2-26 and 2-27 illustrate a typical configuration of a discharge hopper vibratory coal feeder.

Figure 2-26 Bottom View of a Vibratory Coal Feeder Courtesy of General Kinematics Corporation

2-33


Figure 2-27 Outline View of a Suspended Vibratory Vibratory Coal Feeder Courtesy of General Kinematics Corporation

2.3.8 Magnetic Separators An electromagnetic separator attracts ferrous (magnetic) material. Typically suspended above a conveyor belt, mild steel objects are lifted out of the nonmagnetic material (coal) conveyed beneath the separator. Attracted steel is held against the underside surface of the separator until removed—automatically on self-cleaning models, which have a belt that travels continuously around the magnet, or by switching off the power for a stationary model. Suspended overhead magnets are available for either over-the-belt (crossbelt) or over-the-headpulley (in-line) installations. The preferred location for most applications is in-line above the conveyed material trajectory as it is discharged from the conveyor belt. Separating efficiency is greater because the conveyed material is less compacted while being projected directly toward the magnetic surface of the separator.

2.3.8.1

Self-Cleaning Overhead Magnets

In the vast majority of cases in a coal handling system at a fossil power plant, the magnetic separator used is a self-cleaning overhead magnet. This device provides continuous removal of metals from the coal and is best used in applications where large amounts of metal need to be removed. In most designs, a thick, heavy-duty rubber belt moves continuously around the magnet, intercepting attracted metal and sweeping it off the magnet. This design prevents an excessive buildup of iron from covering the face of the magnet and possibly shorting out the 2-34


magnetic field. Rubber cleats (often 1 in. [2.5 cm] high) vulcanized to the belt prevent round metal fragments from rolling and staying in the magnetic field. Vulcanizing also prevents metal from becoming entrapped under the cleat. Figure 2-28 illustrates the overall configuration of a self-cleaning overhead magnet.

Figure 2-28 Self-Cleaning Self-Cleaning Overhead Magnetic Separator Courtesy of Dings Company Magnetic Group

Figure 2-29 illustrates a suspended magnetic separator machine typically used in a coal handling system.

Figure 2-29 Suspended Magnetic Separator Machine Courtesy of Dings Company Magnetic Group

2-35


Depending on plant-specific designs, either an in-line or a crossbelt mounting installation can be used, as shown in Figure 2-30.

Figure 2-30 Mounting Options Courtesy of Dings Company Magnetic Group

An in-line installation is preferred for most applications because the magnet is installed over the conveyor head pulley with its cleaning belt running parallel to the trajectory of material falling off the conveyor head pulley. Because the material being conveyed is less compact as it is discharged from the head pulley, less magnetic force is required to separate the metal. This is the most economical configuration because a smaller magnet would be required. When space is a consideration, a crossbelt installation might be necessary. In this case, the magnet is mounted over any straight section of a conveyor, with its cleaning belt running perpendicular to the conveyor travel direction.

2.3.8.2

Stationary Overhead Magnets

For intermittent metal removal, a stationary overhead magnet might be sufficient. Figure 2-31 illustrates the overall configuration of a stationary overhead magnet.

2-36


Figure 2-31 Stationary Overhead Magnetic Separator Courtesy of Dings Company Magnetic Group

The advantage of a stationary overhead magnet is that there are no moving parts, and the magnet requires little maintenance because there is nothing to lubricate, tighten, or replace. Most stationary overhead magnets come equipped with a three-point cable sling suspension system. Figure 2-32 illustrates the simple operation of a stationary overhead magnet.

Figure 2-32 Operation of a Stationary Overhead Magnet Courtesy of Dings Company Magnetic Group

The stationary magnet can be suspended either over the conveyor or over the head pulley. Connecting the magnet to a direct current (dc) power source is all that is necessary to operate the device. When the magnetic surface becomes filled, the magnet is swung away from the conveyor to a discharge bin and the power is shut off. Attracted metal falls freely into the bin. The magnet can then be swung back over the conveyor to resume operation after restoring dc power to the unit.

2-37


2.3.8.3

Rectifiers

A rectifier is auxiliary equipment that supplies electric power to electromagnetic separators. It converts the ac from a local power source to the dc needed by such separators. The rectifier typically consists of a hinged door cabinet and an internal assembly of electrical components. Ratings and sizes of components in solid-state silicon-diode designs determine output in volts and watts. Rectifiers are available in a wide range of wattages to handle the power requirement of any size electromagnetic separator. A rectifier cabinet should be selected in a particular National Electrical Manufacturers Association (NEMA) enclosure according to the proposed rectifier location within the coal handling system. Figure 2-33 illustrates a typical configuration of a rectifier used with magnetic separators.

Figure 2-33 Typical Rectifier Used with Electromagnetic Electromagnetic Separators Courtesy of Dings Company Magnetic Group

2.3.9 Slide Gates

2.3.9.1

Horizontal Slide Gates

Horizontal slide gates are very versatile pieces of equipment. They can be as basic as a gate containing a manually operated blade, or as complicated as a fast-acting, totally automatic, totally sealed, quadruple-blade, dewatering gate with continuous position feedback, close pocket, and infinitely variable blade position.

2-38


Horizontal slide gates require little headroom, are very durable, and can be easily maintained. Depending on the flow characteristics of the material being controlled, horizontal slide gates can be used to regulate flow into a process or onto a conveyor. Materials with bridging and rat-holing problems generally require other methods of flow regulation, but the horizontal slide gate is still useful as a flow shutoff device. The compact design of the horizontal slide gate facilitates sealing the system in which it is installed; this prevents any escape of dust particles. The precise control with which the blade can be positioned and the potentially high blade speed (up to 2.5 ft/second [750 mm/second]) make the horizontal slide gate suitable for precise batching operations. Figure 2-34 illustrates a typical roller-type horizontal slide gate.

Figure 2-34 Typical Roller-Type Slide Gate Courtesy of Salina Vortex Corporation

Another type of slide gate common in coal handling systems is the aggregate type. The aggregate gate is designed for high-volume, larger particulate-sized applications. It features the following design elements: •

Gravity flow

•

Ability to handle abrasive material

•

Horizontal valve orientation

•

Open/closed or volume metering of material

•

Modifications available for a variety of environments

Figure 2-35 illustrates a typical aggregate-type slide gate.

2-39


Figure 2-35 Typical Aggregate-Type Slide Gate Courtesy of Salina Vortex Corporation

A third type of slide gate common in coal handling systems is the diverter-type gate. These gates are used to separate the flow path and divert the flow to one of several paths. Depending on the application, these gates can be designed to provide varying levels of sealing capability. Figures 2-36 and 2-37 illustrate two types of aggregate diverter gates.

Figure 2-36 Aggregate Diverter Slide Gate Courtesy of Salina Vortex Corporation

2-40


Figure 2-37 Seal Tite Slide Gate Courtesy of Salina Vortex Corporation

2.3.9.1.1

Applications

The wide range of sizes available makes these types of gates suitable for a very large number of applications within a coal handling and conveying system. Double-blade gates can be used to provide flow regulation of coal onto high-capacity reclaim conveyors from open storage piles, storage buildings, or vertical silos. These gates can be preceded by pile activators to prevent arching and rat-holing. Typically, these gates will be mounted perpendicular to the reclaim conveyor to facilitate loading coal onto the center of the conveyor. This system is sometimes preferred to large mass-flow hoppers and mass-flow gates. Horizontal slide gates can also be used to reclaim from coal stockpiles at low to moderate rates for raw coal or clean coal, with flow regulation handled by trim gates downstream of the reclaim gate or by another flow regulator, such as a vibrating feeder. Quadruple-blade horizontal slide gates are sometimes used to transfer a large amount of coal from a surge bin or silo into a weigh bin very rapidly and, by using one or more set points, control the shutoff very accurately. Other applications are used as emergency shutoff gates to allow maintenance of downstream equipment without unloading the material in storage, and to control discharge from bins, silos, or open storage into trucks or railcars.

2-41


2.3.9.2

Actuators

The actuators available for use on horizontal slide gates include the following types: •

Hydraulic

•

Electric over hydraulic

•

Electric

•

Pneumatic

2.3.9.3

Seals

Seals are available for a wide range of applications, including: •

To prevent or reduce escaping dust

•

To isolate the gate from vibration

•

To prevent the transfer of forces between the gate and other structures or equipment

•

To prevent the escape of water or to direct water to a collection point

2.3.9.4

Construction Materials

Horizontal and diverter slide gates can be fabricated from or equipped with a wide range of construction materials, depending on the characteristics of the bulk material being handled. Some examples of construction materials for different applications are: •

•

•

•

Carbon steel with abrasion-resistant liners to protect the blade supports can be used for most applications. Polished stainless steel blade liners can be used to reduce the friction between the bulk material and the gate blade, thereby reducing the force required to open the blade. Stainless steel can be used in all areas in contact with acidic material to prevent corrosion. In some instances, it might be necessary to fabricate the entire gate from stainless steel. Blade supports can be commercially available as needle bearing rollers, stainless steel rollers, or low-friction plastic slide bearings.

2-42


2.3.9.5

Position Indication

Especially for totally sealed gates, it is important to have a method of determining the position of the gate blade. For gates used to adjust the flow of material, it is necessary to monitor the position of the blade at all times. For some gates it is necessary to determine when they are closed, for others when they are open, and for others when they are both open and closed. Some of the devices available to determine the gate blade position are: •

•

•

•

•

A limit switch can be used to detect whether the gate is closed, open, or at any preset intermediate position. A proximity switch can be used to detect the closed, open, or any preset intermediate position. A sensor can be used to continually detect the gate blade position. For visual indication, a rod attached to the gate blade can be extended outside the gate through a grommet to indicate the blade position. Integral position indication is available from actuator manufacturers to indicate the gate blade position.

2.3.10 Dust Control Systems There are many configurations of dust control systems that can be found in a typical coal handling system. For the purposes of this report, the dust collection systems discussed will be limited to those typically found at an unloading station, a reclaim area, crusher house, and a junction house. house. Depending Depending on the location of of the dust collection collection system, system, dust pickup pickup locations locations can include any of the following: •

Head ends of feeders

•

Tail ends of conveyors

•

Silos

•

Surge bins

•

Head ends of conveyors

A dust collection system installed at a coal unloading area is shown in Figure 2-38.

2-43


Figure 2-38 Coal Unloading Station Dust Collection System Courtesy of Airtrol, Inc.

2.3.10.1

General Operation

A typical dust collection system is illustrated in the cut-away drawing shown in Figure 2-39.

2-44


Figure 2-39 Typical Dust Collection System Courtesy of Airtrol, Inc.

During normal operation, dust-laden air enters the body inlet section. The cyclonic action developed by the involute inlet causes the heavier dust particles to drop directly into the hopper below. A flow straightener baffle helps to evenly distribute the dust-laden air around the filter tubes. The dust collects on the outside surface of each filter tube, where it forms a cake that aids in filtering efficiency. Filtered (clean) air passes through each filter tube into the clean air plenum, where it is discharged through the clean air outlet. During the bag cleaning, pressurized air is discharged from an air reservoir into the 360° revolving manifold arm(s). The open-and-close time of the diaphragm valve is typically controlled by a solid-state timer that energizes the pilot solenoid valve and opens the diaphragm valve. When the diaphragm valve opens, a high volume of air is directed through the manifold arms and is discharged into the filter tubes, forcing the collected dust to fall from the exterior of the filter tubes into the hopper below.

2-45


2.3.10.2

Configuration Options

As noted previously, there are many different combinations of dust control equipment configurations available to each fossil plant owner. Figures 2-40 through 2-42 illustrate different configurations for dust collection, filter access, and inlet connections, respectively.

Figure 2-40 Typical Dust Collection Configuration Options Courtesy of Airtrol, Inc.

Figure 2-41 Typical Filter Access Options Courtesy of Airtrol, Inc.

2-46


Figure 2-42 Typical Inlet Connection Options Courtesy of Airtrol, Inc.

2.3.11 Conveyor Belts, Pulleys, Idlers, and Rollers

2.3.11.1

Types of Conveyor Belts Used in Coal Handling Systems

Magnetic separator belt – These belts revolve around a magnet that is typically suspended over the conveyor. These magnets attract unwanted scrap metal from the material (coal) being conveyed and pull the metal up against the belt. With the help of cleats, the unwanted metal is transported out of the magnetic field and discharged into a collection area. These belts are available in compounds such as rubber, urethane, and PVC. Cleats can be vulcanized to the belt cover or attached with nonmagnetic elevator bolts. Magnetic separator belts are typically spliced with nonmagnetic lace. Illustrations of belts used on magnetic separators are provided in Section 2.3.8 of this report. Coal sampling belts – Coal sampling belts are often furnished with standard side flange heights of 1/2 in. up to 1½ in. (1.3–3.8 cm). Side flanges can be notched, siped, drilled and siped, or solid. Siping is a process of cutting thin slits across a rubber surface to improve traction in wet or icy conditions. Sampling belts can be provided with different types of splices, and cover grades often include fire-resistant materials.

2-47


Corrugated sidewall belts – Sidewall belts carry material in any plane, from horizontal to vertical. The most common conveyor shapes include straight-incline, “L,” and “S” shapes. Each sidewall belt typically consists of two corrugated sidewalls bonded to a cross-rigid base belt. Cleats are often hot-molded to the base belt between the walls for steep angle material handling. The walls can be recessed for clearance and belt support through bend sections. Figure 2-43 illustrates the general configurations of some corrugated sidewall belts.

Figure 2-43 Corrugated Sidewall Belts Courtesy of Beltservice Corporation

Coal feeder conveyor belts – Coal feeder belts are often furnished with the following types of splices and features: •

Vulcanized splice coal feeder belts

•

Recessed covered coal feeder belts

•

Mechanically fastened coal feeder belts

In some cases, the belt can be provided in bulk quantity and cut to fit the application.

2.3.11.2

Conveyor Belt System Components

Figure 2-44 illustrates the basic configuration of a conveyor belt system and identifies some of the major components composing such a system.

2-48


Figure 2-44 Conveyor Belt System Components Components Courtesy of Beltservice Corporation

Angle of incline – The degree a conveyor is tilted from horizontal. Conveyor holdbacks – A ratchet- or clutch-type device that prevents an inclined conveyor from running in reverse. Crowns – Crowned pulleys for a lightweight conveyor belt can be trapezoidal or radial in shape. Georgia Duck has products to accommodate both styles; however, the amount of crown in either case should not exceed 1/8 in./ft (3.2 mm/30.5 cm) on the diameter and should not exceed 1/8 in. (3.2 mm) total. The rate of crown seems to be very important, as does the total amount of crown in the system.

On short-center conveyors, we recommend no crown on the drive (avoid crowns on the drive in every case, unless the drive is an end pulley) and to crown the end pulleys. In a few cases, we would also crown additional pulleys, but that will depend on the entire design and the amount of crown used. For crowns to be effective, there must be enough free span/transition for the belt to elongate and conform. Pretension to get pulley-crown conformation is very important, but too much pretension can cause pulley deflection and bearing problems. Georgia Duck has specific carcass ( carcass is the strength member in the rubber belt) constructions to meet very shortcenter, wide-belt applications in the 1:1 ratio of length to width, and even less. Please consult the manufacturer if you have needs in this area. Crowned pulleys are not recommended for high modulus bulk haulage belting. Steel cord belting requires fully machined, straight-faced pulleys throughout the system. If a crowned pulley is used on nylon, polyester, or aramid-style belting, the crown should be placed only in a 2-49


low-tension area, such as the tail on a conventional head-drive conveyor. The tracking forces that the crown exhibits do not affect high modulus bulk haulage belting because the system lacks enough tension to make the crown effective. If you could exert enough tension on the belt to force the belt to conform to the crown, the belt would be subjected to excessive stretch and splice failure could result. Drive pulley – Pulley connected to a power source used to drive conveyor. Usually the drive pulley is the head pulley, but on some kinds of systems (including many package-handling conveyors), the drive pulley is located under the conveyor. Gravity takeup – Device used to remove slack and stretch in a conveyor belt. A free weight is suspended from an idler on the return side of the belt. The takeup is free to lower as needed to remove any slack as the belt is operated. The gravity takeup is usually located as close to the drive pulley as possible. Head pulley – Pulley at discharge end of belt. The head pulley is usually powered by a conveyor drive source. Pulley pulls belt along the conveyor. Pulleys/rollers/idlers – All pulleys, snub rollers, carrying idlers, and return idlers must be square with the frame (perpendicular to the belt centerline), parallel to each other, and level. Return idler – Idlers used to support belt as it passes underneath the conveyor structure. Roller bed – Free-wheeling, usually closely spaced rollers used to support the conveyor structure. Screw takeup – Device with a bolt construction used to lengthen the conveyor to remove slack in the conveyor belt. By moving a bolt, the tail pulley is pushed away from the head pulley, thus removing slack from the belt. Skirtboard rubber – Skirtboard rubber is primarily used at the loading point to guide the product into the center of the belt and to prevent spillage. Slider bed – Smooth, flat surface (usually steel or wood) on which the loaded conveyor belt rides. Snub idler – Idler used to increase the amount of belt in contact with the pulley or to deflect the belt in a different direction. Snubbing a belt near a pulley can increase the effectiveness of the pulley. Squaring – Squaring with the frame is a good preliminary adjustment. The final adjustment, however, requires that this squaring be done with the belt centerline as the reference. All pulleys must be at right angles to the direction of belt travel (belt centerline).

2-50


Supporting structure – The supporting structure is designed to hold conveyor sections firmly and in proper alignment. If it does not, for whatever reason, it is likely to have an effect on belt tracking. Support structure should be checked as a first step in belt tracking. Has a forklift run into the supporting structure and buckled it? Are the anchors firm? Conveyor sections are bolted to the supporting structure. They should be square and horizontal (side to side). If the section is racked, it must be straightened. Measure diagonals across the frame: they should be equal. Repeat for the total, assembled bed.

Conveyor bed sections (slider or roller) must be properly aligned with no vertical offset between sections. A taut line should be stretched over the top surface of the bed and adjustments made so that all points are in contact. The entire bed (and each section) must be horizontal (across the width). If they are not, the belt will be pulled by gravity and will drift toward the low side unless a compensating force of some kind is exerted on that belt. Switches and instrumentation – Instrumentation and switches on conveying systems will vary from plant to plant. Common switches that are typically found on a coal handling conveying system include the following: •

•

•

•

Speed switches – These switches can be located at various points along the conveying path and typically consist of a magnetic pickup at the end of the pulley that controls the speed of the conveyor. Misalignment switches – These switches are typically located along the sides of the belts and are designed to trip the conveying if the belts become misaligned or off track. Pull-cord safety switches – These switches, which are manually activated by pulling a nylon cord, are selectively positioned along the conveying route to allow an operator to stop the conveying should an unsafe situation arise. Chute plug switches – These switches are designed to stop the conveying when the chute or hopper trough becomes plugged or bridged.

Tail pulley – Pulley at the beginning of the carrying run of the conveyor. The tail pulley is usually free-wheeling. Takeup device – The takeup device in a conveyor belt system has three major functions:

1. To establish, and preferably maintain, a predetermined tension in the belt 2. To remove the accumulation of slack in the belt at startup or during momentary overloads, in addition to maintaining the correct operating tension 3. To provide sufficient reserve belt length to enable resplicing, if necessary Both manual and automatic takeup devices are normally used in a typical conveyor belt system. The manual or screw takeup consists of a tension pulley (frequently the tail) that can be moved to tighten the belt by means of threaded rods or steel cables that can be wound on a winch. Manual takeup devices give no indication of the tension they establish and are adjusted by trial methods until slippage is avoided. They are unable to compensate for any length changes in the 2-51


belt between adjustments and thus permit wide variation in belt tension. Use is generally restricted to short and/or lightly stressed conveyors. The manual takeup must operate in such a way that when tension is applied to the pulley, the pulley remains at right angles to the direction of belt travel. Also, the tension must be high enough to allow elastic recovery of elongation due to starting forces, load changes, and so on. Automatic takeups depend upon suspending a predetermined weight (gravity) by activation of a torque motor, by hydraulic pressure, or by spring loading. These devices maintain a predetermined tension at the point of takeup regardless of length changes resulting from load change, startup, stretch, and so on. This permits running the belt at the minimum operating tension and should be used on all long conveyors and moderately to highly stressed conveyors. The automatic takeup alignment must be such that the pulley or pulleys are maintained at right angles to the direction of belt travel. In a gravity or spring-loaded takeup, the carriage must be guided to maintain the pulley axis on a line perpendicular to the belt centerline. Adequate takeup is essential to satisfactory operation of a belt conveyor. The amount required depends on the type of belting and on service conditions. Refer to the belt manufacturer for recommendations. Key Technical Point

Normally, when a new belt has been properly installed and tensioned, the takeup roll or pulley (automatic takeup) will be initially set at a position of 25% along the line of travel, leaving 75% of the takeup area available for elongation.

Troughing idlers – Grouping of idlers on the carrying side of the conveyor designed to make the conveyor belt curve into a cupped shape, increasing conveyor capacity. Troughing idlers are usually 20º, 35º, or 45º.

2.3.11.3

Conveyor Belt System Attributes and Terms

2.3.11.3.1

Balanced/Neutral

It is extremely important that the final belt construction be balanced or neutral in terms of the internal stresses imparted to the belt during manufacture. Any unbalanced stress remaining in the belt will likely cause problems in tracking. Conveyor belts have two basic components: the carcass, or strength member, and the rubber, which protects the carcass. Typical belt carcass designs usually use a plain weave or twill weave. The crimp imposed upon the warp yarns (lengthwise yarns) in these types of weaves, as well as the warp tension necessary at the loom, are difficult to control. Unbalanced stresses can result. Many manufacturers have a patented tensioning system to minimize this problem.

2-52


The resulting straight/balanced carcass is kept straight by tensioning during the impregnation and curing steps of manufacture, resulting in a straight belt that is balanced and, therefore, easy to track. 2.3.11.3.2

Camber

If unbalanced warp tensions exist in a conveyor belt, that belt will usually assume a crescent or banana shape when laid flat upon a horizontal surface. This deviation from a straight line is hereby defined as camber. To measure belt camber, it is recommended that the belt be unrolled on a flat surface like the warehouse floor, a flat horizontal driveway, or similar. Next, one end of that belt (and one end only) should be grasped and the belt dragged in a perfectly straight line for approximately 10 ft (3 m). If the belt is too heavy for one person to move, one end should be clamped to a forklift and the same procedure performed. At this point, the belt should lie flat. Unequal and unresolved warp tensions in the belt will cause it to assume a crescent or banana shape. Camber is measured by drawing a taut line along one edge of the belt and measuring the distance from that line to the belt at the point of maximum deviation. Compute the percent camber as follows: % Camber = Maximum deviation (in.[cm]) x 100 Length of taut line (in.[cm])

If the percent camber exceeds one-half of 1%, it is recommended that the belt manufacturer be contacted. In lightweight, unit/package handling, 0.25% is the maximum. Camber can be instilled into a belt during the slitting operation if one of the slitting knives is dull. A dull slitting knife will tear the fill yarns (crosswise yarns) rather than cut them. (While the belt is in roll form, the side of the belt that had gone through the dull knife will exhibit a fuzzy appearance due to the torn fill yarns.) Usually this type of camber will be less than onequarter of 1% and can be pulled out handily when the belt is properly tensioned. 2.3.11.3.3

Skew (Bow)

The fill yarns (weft yarns) in the belt carcass will usually lie along the perpendicular to the belt centerline. Any deviation from this perpendicular line by the fill yarn is hereby defined as skew or bow. A skewed pick in a plain weave or twill weave is cause for concern, because it is generally indicative of unbalanced warp tensions and will usually go hand-in-hand with a significant camber. In a straight warp or solid woven carcass design, however, skew is of little significance. It is a cosmetic defect and is not indicative of a cambered belt.

2-53


2.3.11.3.4

Belt Tension

Belt tension must be great enough to prevent slippage between the drive pulley and belt. Tension must also be enough to cause the belt to conform to the crowns, if present. Slippage will cause excessive wear to both drive pulley lagging and the belt. Further, an excessive heat buildup on the drive pulley lagging can result in rubber reversion. Key Technical Point Reversion is

the softening of vulcanized rubber when it is heated too long or exposed to elevated temperatures. It is characterized by deterioration in physical properties and frequently results in tackiness, gumming of the rubber, or loss of tensile strength.

Once the pulley lagging has reverted, it frequently will offset onto the bottom side of the conveyor belt, which will then distribute the reverted rubber throughout the slider or roller bed of the system. The resulting tackiness between the bed and the belt will certainly drive horsepower consumption up; it can actually result in a stalled system and severe tracking problems. 2.3.11.3.5

Square Ends

Accurate squaring of the belt ends prior to splicing is essential to belt tracking and helps distribute stress evenly throughout the splice. To properly square the belt ends, many manufacturers recommend the centerline method, which is described in Section 5 of this report.

2.3.12 Movable Belt Tripper Devices Like the name implies, a belt tripper is used to trip the material off the conveyor at locations between the terminal pulleys. A tripper can either be fixed-position or movable and consists of a structure with two pulley assemblies. As the belt passes over the upper pulley, the material is discharged from the belt into a collection chute. The material is then diverted to one side or both sides of the belt for discharge, or back onto the belt if the desired discharge position is at the end of the conveyor. Several powered drive options and chute configurations are available for any belt tripper. Belt trippers are designed for continuous operation and to discharge the material from the belt at one or more points, or along the length of the conveyor. Figures 2-45 and 2-46 illustrate the general configuration of belt tripper devices.

2-54


Figure 2-45 Motor-Propelled Belt Tripper Courtesy of AB Conveyor, Inc.

Figure 2-46 Cable-Propelled Cable-Propelled Belt Tripper Courtesy of FEECO, Inc.

There are two basic designs of belt trippers that can be installed in a coal handling system—the motor-propelled belt tripper and the cable-propelled belt tripper. Each tripper can be a singledischarge, a double-discharge, or a combination with the added ability of feeding over the tripper head back to the belt through a diverter gate arrangement. A third type, the belt-propelled tripper, is not as common in coal handling systems and will not be discussed in any further detail in this report.

2-55


2.3.12.1

Motor-Propelled Tripper

The motor-propelled tripper is used where continuous and uniform distribution of material along the conveyor is required or where the tripper is to be moved or reversed frequently. Propelled by an independent electric motor, it can be automatically reversed at each end of its travel by limit switches carried on the tripper and actuated by stops placed where desired along the runway. Push buttons are provided for manual control to permit continued discharge at any desired location. The tripper can be moved when the conveyor belt is moving or stationary.

2.3.12.2

Cable-Propelled Cable-Propelle d Tripper

The cable-propelled tripper is for installations where powering a propelled tripper is required, but where the electrical conductors or trolley wires needed for a motor-propelled tripper are undesirable. Movement of the tripper, either for automatic reversing or for movement to specific locations, is obtained by a single wire rope suitably reeved through the tripper and a stationary sheave, and driven by a winding machine. The single wire rope drive ensures tripper alignment throughout the travel distance.

2.3.12.3

Belt-Propelled Tripper

The belt-propelled tripper is used where travel distance and direction will be manually controlled. Power to move the tripper is obtained from the conveyor belt. It is transmitted from a pulley shaft to a countershaft through manually engaged friction wheels. From the countershaft, it is then sent by a chain drive to the tripper wheels.

2.3.13 Gearboxes A gearbox is a mechanical device that adjusts the speed, torque, and direction of rotational forces between a motor (the driver), and in the case of coal handling systems, a conveyor belt. The gearbox can be connected to the drivers with a number of different types of couplings, including fluid, flexible shaft, or rigid.

2.3.13.1

Gear Arrangement

2.3.13.1.1

Parallel-Shaft Gear Drives

These drives consist of gear elements whose shaft centerlines are parallel and located in the same plane. This is the most prevalent design used in power plant applications. Parallel-shaft gear drives are used in many industries and can be supplied for both high-speed and low-speed applications. Horizontal parallel-shaft gear drives – As shown in Figure 2-47, these drives consist of gears whose shaft centerlines are parallel and located in a horizontal plane.

2-56


Figure 2-47 Parallel-Shaft Gearbox Courtesy of Philadelphia Gear Corporation

Vertical offset parallel-shaft gear drives – These drives consist of gears whose shaft centerlines are parallel and located in a vertical plane. In the high-over-low arrangement shown on the left side of Figure 2-48, the high-speed pinion is located above the low-speed gear. In the low-over-high arrangement, the low-speed gear is located above the high-speed pinion.

Figure 2-48 Vertical Offset Parallel-Shaft Gear Drive Arrangements Courtesy of Philadelphia Gear Corporation

In-line parallel-shaft gear drives – These drives consist of multiple sets of parallel-shaft gear sets arranged so that the gear drive input shaft and output shaft are on the same vertical plane (centerline). This arrangement is illustrated in Figure 2-49.

2-57


Figure 2-49 In-Line Parallel-Shaft Parallel-Shaft Gear Drive Courtesy of Philadelphia Gear Corporation

2.3.13.1.2

Right-Angle Bevel Gear Drives

These drives consist of right-angle bevel gears, which orient the gear drive’s input and output shafts at right angles. Input and output shafts can be located in any plane. An example of a rightangle bevel gear drive arrangement is shown in Figure 2-50.

Figure 2-50 Right-Angle Right-Angle Bevel Gear Drive Arrangement Courtesy of Philadelphia Gear Corporation

2-58


2.3.13.1.3

Hybrid Gear Drives

Hybrid gear drives consist of two or more gear sets of like or different gear types, and allow for more application design flexibility than any one type alone could provide. Combination parallel-shaft gear drives – These drives consist of multiple parallel-shaft gear sets with single input and single output shafts. Within this gear configuration are multiple power paths (split gear trains) used to transmit load that could not be accommodated by a single power path. Bevel helical gear drives – As shown in Figure 2-51, these drives consist of multiple gear sets, including both bevel and helical parallel-shaft gear types.

Figure 2-51 Bevel Helical Gear Drive Courtesy of Philadelphia Gear Corporation

Bevel planetary gear drive – As shown in Figure 2-52, these drives consist of multiple gear sets, including both bevel and epicyclical planetary gear types.

2-59


Figure 2-52 Bevel Planetary Gear Drive Courtesy of Philadelphia Gear Corporation

2.3.13.2

Gearbox Applications

Figure 2-53 illustrates a planetary gearbox drive between an electric motor and a coal conveyor. The output drives the conveyor with a chain drive. This drive typically has a 9.3:1 ratio and drives the output shaft at approximately 188 rpm. The conveyor speed is further reduced by the difference in size between the sprockets.

Figure 2-53 Motor-Driven Motor-Driven Gearbox for a Coal Conveyor Courtesy of Rota-tech, Inc.

2-60


2.3.14 Flexible Shaft Couplings

2.3.14.1

Overview of Metallic Flexible Shaft Couplings

Table 2-1 illustrates a number of distinguishing design features for metallic flexible shaft couplings. Table 2-1 Overview of Metallic Flexible Shaft Couplings [2] Differentiating Differenti ating Criteria

General-Purpose General-Pu rpose Couplings

High-Performance High-Performa nce Couplings

Types of designs

Gear, grid, disk, and diaphragm

Gear, disk, and diaphragm

Metallurgy

AISI 1045

AISI 4140

Heat treatment

Flame-hardened gears

Nitrite-hardened gears

Coupling size (see note)

1½ to 5

3 to 6

HP at rpm ranges

0–1000 HP at 3000 rpm

>1000 HP at 3600+ rpm

>1000 HP at 1800 rpm Balancing

Not balanced

Balanced

Configuration

Sometimes with spacers

Always with spacers

Lubrication

Gear – Lubricated

Gear – Lubricated

Grid – Lubricated Disk – Nonlubricated

Disk – Nonlubricated

Diaphragm – Nonlubricated

Diaphragm – Nonlubricated

Limited end float

Gear and grid types

Gear type only

Types of shaft fit

Gear – Interference

Gear – Interference

Grid – Clearance

Type of movement to accommodate misalignment

Disk – Interference

Disk – Interference

Diaphragm – Interference

Diaphragm – Interference

Gear – Slides

Gear – Slides

Grid – Slides Disk – Bends/flexes

Disk – Bends/flexes

Diaphragm – Bends/flexes

Diaphragm – Bends/flexes

Note: Users should coordinate with the coupling manufacturer on a case-by-case basis to ensure that the coupling size specified is bored to either U.S. or metric requirements as needed.

2-61


Metallic flexible shaft couplings can be sorted into two primary categories—general-purpose and special-purpose, as shown in Table 2-1. Note that the grid coupling type is not available for highperformance applications. 2.3.14.1.1

General-Purpose Couplings

General-purpose couplings can generally be classified according to size and speed. A coupling connected to a rotating machine operating less than 100 hp is classified as small, and is sometimes referred to as low. Between 100 and 1000 hp is characterized as medium. Usually, horsepower over 1000 is considered critical and the couplings, therefore, are often considered to be special-purpose or high-performance. The majority of couplings in a power station are of the general-purpose type. These couplings can be divided into separate classes by the type of coupling—balanced or unbalanced. Materials can vary within the general-purpose category. 2.3.14.1.2

High-Performance Couplings

Special-purpose couplings are similar to general-purpose couplings. They are designed to perform the same functions as general-purpose couplings, but at higher speeds and horsepower. Due to this improvement in performance, elastomer couplings do not qualify as special-purpose couplings. For the purposes of this report, special-purpose couplings will be referred to as high-performance couplings. High-performance couplings can be gear, disk, or diaphragm types, and usually employ a spacer between shafts. The later versions of high-performance couplings might employ reduced-moment designs. These couplings are designed to operate at high velocities at the periphery of the coupling. It is not uncommon for couplings of this type to operate up to and including 20,000 rpm. For a typical coupling mounted to a 4-in. (10.2-cm) shaft operating at these speeds, this can translate into a periphery speed or velocity of nearly 1000 ft/second (304.8 m/second). These couplings are typically a continuous lubrication type, but a few are not (they are dry). Typically, there are two general categories of high-performance couplings—lubricated and nonlubricated. High-performance gear couplings (mechanical element) usually require continuous oil lubrication.

2.3.14.2

Overview of Elastomeric Flexible Shaft Couplings

Table 2-2 illustrates a number of distinguishing design features for elastomeric flexible shaft couplings. One important feature of elastomeric flexible shaft couplings is that they are limited to general-purpose applications, and typically are not available for high-performance applications. Elastomer-type couplings allow misalignment and axial motion through flexing or compression of the elastomeric elements. 2-62


Table 2-2 Overview of Elastomeric Flexible Shaft Couplings [2] Differentiating Differentiating Criteria

General-Purpose General-Purpose Couplings Couplings

Types of elastomeric flexible shaft couplings

Synthetic gear, jaw/spider, tire (urethane or corded), donut

Metallurgy

Carbon steel or cast iron

Heat treatment

Not heat treated

Coupling size (see note)

1/2 to 2½

Hp at rpm ranges

0–1000 hp at 3000 rpm

Balancing

Not balanced

Configuration

Sometimes with spacers

Lubrication

Nonlubricated

Limited end float

Not applicable (except for block type)

Type of force on elastomeric element

Synthetic gear – Compression Jaw/spider – Compression Tire (urethane or corded) – Shear Donut – Compression

Types of fit

Clearance (except for block type and some synthetic gear types that might have interference fits)

Type of movement to accommodate misalignment

Synthetic gear – Slides Jaw/spider – Slides Tire (urethane or corded) – Bends/flexes Donut – Bends/flexes Resilient block – Slides/flexes

Note: Users should coordinate with the coupling manufacturer on a case-by-case basis to ensure that the coupling size specified is bored to either U.S. or metric requirements as needed.

Additional guidance regarding the design, types, and functionality of various metallic and elastomeric couplings is provided in the EPRI report Flexible Shaft Couplings Maintenance Guide [2].

2-63

3

PREVENTIVE MAINTENANCE FOR COAL HANDLING SYSTEM COMPONENTS

3.1

General Guidance

The following sections provide an overview of the various types of maintenance activities that can be performed on the coal handling/conveying system or a particular system component.

3.1.1 Preventive Maintenance PM tasks are performed based on a time or interval basis to avoid catastrophic equipment failure. PM performs maintenance tasks on a planned rather than reactive basis and avoids the losses associated with unplanned downtime. The penalty of PM is that some tasks are performed that are unnecessary and costly. The following subcategories of PM are based on scheduling of the actions: •

•

•

Grace period PM – Any PM task that is to be performed beyond its original due date but prior to the late date for that activity. Normally, this time period (due date to late date) is an additional 25% of the original schedule interval for the PM task. No engineering evaluation is required. The grace period is provided as reasonable flexibility to allow for alignment with surveillance activities and functional equipment group bundling and to better manage the use of station resources. Deferred PM – A PM task that exceeds its original late date with an approved engineering evaluation determining the acceptability for extension to a new due date, prior to the original late date being exceeded. Delinquent (overdue) PM – A PM task that exceeds its late date (grace period) without an approved extension or deferral.

The distinction between predictive maintenance and periodic maintenance is presented in the next two sections.

3-1

Preventive Maintenance for Coal Handling System Components

3.1.1.1

Predictive Maintenance Key Technical Point

Predictive maintenance tasks are performed based on equipment condition. Predictive maintenance relies on technologies to determine the current condition of the equipment so that only the required maintenance is performed before equipment failure.

Examples of predictive maintenance follow: •

•

Vibration analysis for all rotating equipment Thermography for temperature surveys on electrical equipment, leak detection, overheating, and so on

•

Oil analysis (tribology) to determine the equipment condition and also the lubricant condition

•

Electrical testing for motor and generators

3.1.1.2

Periodic Maintenance Key Technical Point

Periodic maintenance consists of time-based PM actions taken to maintain a piece of equipment within design operating conditions and to extend its life.

Periodic maintenance can be performed to prevent breakdown and can involve servicing such as lubrication, filter changes, cleaning, testing, adjustments, calibrations, and inspections. Periodic maintenance can also be initiated because of the results of predictive maintenance, vendor recommendation, or experience. Examples of periodic maintenance: •

•

•

•

3-2

Scheduled valve repacking because of anticipated leakage based on previous experience Replacement of bearings or pump realignment as indicated from vibration analysis and/or lubrication oil analysis Major or minor overhauls based on experience factors or vendor recommendations Instrument calibrations used to meet plant specifications that are not part of a routine surveillance


3.1.2 Corrective Maintenance Key Technical Point

Corrective maintenance tasks are generated as a result of equipment failure. Corrective tasks are generated when equipment eq uipment is purposely operated to failure and also when equipment failure is not desired or planned. It is the most basic form of maintenance and also the most expensive. Most plants are moving away from corrective maintenance, but there will always be a portion of maintenance performed as a result of equipment failure.

As a rule, if the specific component requiring maintenance is substantially degraded (for example, packing or bearing degradation) or failed, the action required to repair it is classified as corrective maintenance. To be considered corrective maintenance, the component must have failed in a way that it cannot meet its intended functions, or, for degradation identified during a PM, the component will reach this state before the next scheduled PM. There might be cases in which corrective maintenance could include standing PM orders/procedures specifically invoked to correct anticipated component degradation. If the degradation does not meet these criteria, it should be considered elective maintenance. maintenance. A component should be considered failed or significantly degraded if the deficiency is similar to any of the following conditions: •

•

•

•

•

•

It is removed from service because of actual or incipient failure. Significant component degradation that affects system operability: the component might be determined operable by engineering assessment, but the degradation is significant and requires immediate corrective action. It creates the potential for rapidly increasing component degradation. It releases fluids that create significant exposure or contamination concerns: minor leaks that can be controlled and managed by simple drip catch containments would not be included here. It adversely affects controls or process indications that directly or indirectly impair operator ability to operate the plant or that reduce redundancy of important equipment. Significant component degradation identified from the conduct of predictive, periodic, or PM, which, if not resolved, could result in equipment failure or significant additional damage prior to its next scheduled PM.

Detailed guidance regarding the repair of coal handling system components is provided in Section 5 of this report.

3-3


3.2

Coal Handling System Component Maintenance Maintenanc e Guidance

Sections 3.2.1 through 3.2.14 summarize guidance for performing PM on the components typically installed in coal-conveying systems. The tables and accompanying text provide a list of the various components, the recommended PM activities (tests, inspections, parts replacements, refurbishment, and so on), and the frequency with which these maintenance activities should be performed.

3.2.1 Belt Scales

3.2.1.1

General Preventive Maintenance Guidance

Belt conveyor scales have become an important part of most bulk material handling facilities. However, being relatively unobtrusive in most coal conveyor systems, they are often overlooked or ignored after their initial installation. Lack of simple maintenance can cause significant reduction in the accuracy capabilities of these instruments. Most belt conveyor scales are capable of providing reliable results with ±0.5% of their full-scale rating. Belt conveyor scales that have been certified through the National Type Evaluation Program (NTEP) are capable of providing results that meet the criteria of the National Institute of Standards and Technology (NIST) Handbook 44 [17], which is 0.25%. This is defined as being within 0.25% of actual material load and repeatable within a 0.25% bandwidth. Regardless of the accuracy capability of the scale design, it is unlikely that these devices will perform as promised if simple maintenance procedures are not strictly adhered to. Every scale installation will develop its own set of operating characteristics; therefore, it is absolutely necessary to monitor the scale’s performance and provide routine maintenance as required. It is generally advised throughout the belt-scale industry that calibration checks be made frequently during the weeks after initial installation, then to increase the timeframe between calibrations as statistical results are obtained. Although this is a simple suggestion to follow, all too frequently the increase in time between calibration verification defaults to the time when a problem is suspected. By then it is too late: incorrect weights have been recorded, processes have been interrupted, and inventory levels need other means of verification. Establishment of a routine inspection procedure, including not only the belt conveyor scale but the entire coal handling system, will result in an increased confidence in the scale and ultimately greater control of the accuracy it is providing. It is important to remember that the entire conveyor in which the belt scale is installed becomes part of the weighing system, and that any changes that occur or are performed within this conveyor can and probably will affect the performance of the scale. Therefore, in addition to a routine scale maintenance procedure, it becomes imperative that any and all maintenance performed on the conveyor be reported to the individual or organization responsible for the scale’s performance.

3-4


Check points – Routine inspection of the following points should be conducted before performing maintenance calibration:

1. Inspect for material wedged in the weighbridge or excessive buildup on the weighbridge indicating conveyor belt overloads. 2. Be alert and watch for evidence of conveyor maintenance that has occurred in the scale area since the last calibration. Scale area is defined as the dimensional area between minus-five approach scale service idler and plus-five retreat scale service idler. If maintenance has been performed in this area, scale alignment should be checked and corrected if necessary. 3. Measure the weigh span on both sides of the conveyor during calibration. Weigh span dimension should never change. 4. Do not attempt calibration during adverse weather conditions such as high winds, rain, and snow. Calibrations should correlate with average weather and operating conditions. 5. Most calibration errors can be traced to mechanical alignment, housekeeping, and belt overloads. These problems tend to be overlooked in an electromechanical belt scale. Expected accuracy is proportional to maintenance. 6. Calibration should be performed only after the belt has been running for at least 30 minutes. The optimum time is immediately after the belt has been used. Key Technical Point Frequent checkpoints – Each belt scale installation should be checked frequently to determine when calibration is required. It is recommended that the zero calibration be checked every day and that calibration be checked every week for several months after installation. Observe the results and lengthen the period between calibration checks, depending upon the accuracy de sired.

Cleaning – Keep scale area clean of rocks, dust, and material buildup. Lubrication – The weigh idlers should be greased once or twice a year. Overloading the weigh idlers with grease can change the tare weight and place the scale out of calibration. Zero calibration is necessary after greasing. Belt training – The belt must be trained to run true to the centerline of the idlers in the area of the scale while running empty, as well as under loaded conditions. Where this cannot be accomplished due to off-center loading, the loading should be modified. Where a belt does not train while empty but does train while loaded, it will be necessary to train the belt over the scale area at least during the calibration checks.

3-5


Belt tension – It is important that conveyor conditions remain constant at all times. Therefore, gravity-type takeups are recommended on all conveyors where belt scales are installed. Conveyors, which do not have a constant tension device, will require calibration whenever the belt tension changes and the takeup is readjusted. Belt loading – Extreme loading conditions, which cause flow rate of material above the range of the instrument, must be avoided. Belt loading should be adjusted to stay within the instrument range. Belt loading equal to 80% of range is recommended. Conversely, very low flow rates, with respect to full-scale range, can produce low accuracy. Where extremely high or low flow rates (as described herein) persist, the scale range should be changed. Material sticking to the belt – Material can form a film on the belt, with the film carried continually around the belt and never discharged. This condition often occurs when the belt handles wet, fine material. Belt scrapers might correct this condition. If the film cannot be removed, the tare will have to be adjusted. Any change in the buildup of the film adhering to the belt will require further adjustment. Skirt boards and covers – Skirt boards should not be placed too close to the weigh idlers.

3.2.1.2

NIST Preventive Maintenance Guidance

The following guidance is an excerpt from NIST Handbook 44, Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices [17]. Belt conveyor scales and idlers shall be maintained and serviced in accordance with manufacturer’s instructions and the following: a. The scale and and area surrounding surrounding the scale shall be kept clean of debris debris or other other foreign material that can detrimentally affect the performance of the system. b. There shall be provisions provisions to ensure ensure that weighed weighed material does not adhere to the the belt and return to the scale system area. c. Simulated load load tests or material tests and zero load tests tests shall be conducted at periodic intervals between official tests in order to provide reasonable assurance that the device is performing correctly. The action to be taken as a result of the material tests or simulated load tests is as follows: •

•

3-6

If the error is less than 0.25%, no adjustment is to be made. If the error is at least 0.25% but not more than 0.6%, adjustment may be made if the official with statutory authority is notified.


If the error is greater than 0.6% but does not exceed 0.75%, adjustments shall be made only by a competent service person and the official with statutory authority shall be notified. After such an adjustment, if the results of a subsequent test require adjustment in the same direction, an official test shall be conducted.

•

If the error is greater than 0.75%, an official test is required.

•

d. Scale Alignment Alignment – Alignment Alignment checks checks shall be conducted in accordance with the manufacturer’s recommendation when conveyor conveyor work is performed in the scale area. A material test is required after any realignment. e. Simulated Load Equipment Equipment – Simulated load equipment equipment shall shall be clean and properly maintained. f.

Zero Load Load Reference Information – When When zero load reference reference information information is is recorded for a delivery, the information must be based upon zero load tests performed as a minimum both immediately before and immediately after the totalized load.

Table 3-1 sets forth the recommended PM for belt scales. Table 3-1 Recommended Preventive Maintenance for Belt Scales Courtesy of Thermo Electron Corporation Item

Preventive Maintenance Activities

Frequency

Area around the scale

Clean scale area of debris. Determine the cause of debris and take steps to remedy the buildup.

Daily

Calibration

Perform calibration in accordance with equipment manufacturer’s recommendations/procedure. If change is >0.25%, identify cause and correct. Record results.

Daily

Idler rolls

Visually inspect idlers for wear/damage. Replace rolls or bearings as needed.

Weekly

Span calibration

Perform simulated load tests and check repeatability. Refer to NIST HB-44 [17] for actions if error exceeds 0.25%.

Weekly

Belt scraper

Check operation and adjust or replace blades if worn.

Weekly

Takeup mechanism

Visually inspect for cuts, tears, or worn edges.

Monthly

Speed pulley

Visually inspect for wear, material buildup, and belt warp. Check bearings.

Monthly

Speed sensor coupling

Visually inspect for tightness, wobble, and corrosion.

Monthly

Load cell

Test offset to ensure that no load output is within 1% of rated maximum (typical S cell is ±0.3 mV).

Quarterly

Balance multiple load cell scales to within 1 mV. Static weight device

Check static weight mechanism for corrosion, location, and clearances.

Quarterly

3-7


Table 3-1 (continued) (continued) Recommended Preventive Maintenance for Belt Scales Courtesy of Thermo Electron Corporation Item


Frequency

Revolution time

Verify and record time for one belt revolution at maximum speed.

Quarterly

Zero reference number

Compare zero reference number with manufacturer’s reference number to ensure that change is no more than 2% per year.

Quarterly

Line voltage

Measure hot-to-neutral, hot-to-ground, and neutral-to-ground voltages, and correct as needed.

Quarterly

Alignment

Perform alignment procedure per manufacturer’s recommendations.

Annually

Excitation

Measure and verify excitation value and stability factor.

Annually

Belt length

Measure and verify belt length.

Annually

Check rods

Visually inspect check rods to ensure that they are straight and washers are not corroded.

Annually

Input/output (I/O) integrity

Verify performance of all I/O used.

Annually

Dead band

Confirm dead band settings and adjust per manufacturer’s recommendations if needed.

Annually

Auto zero track limit

Measure and record data for future comparative analysis.

Annually

Auto zero track correction

Measure and record data for future comparative analysis.

Annually

Passwords

Confirm and revise as needed.

Annually

Wire terminations

Visually inspect for corrosion and tightness.

Annually

Cable integrity

Visually inspect for corrosion, moisture, and deterioration. Check resistance (ohm) readings.

Annually

Spherical washers

Inspect for corrosion or pitting. Replace if necessary.

Annually

Material factors

Verify material with weighed load test.

Annually


3.2.2.1


Table 3-2 summarizes typical PM activities for a rotary railcar dumper, which might require a one- to two-week maintenance outage due to the dumper’s near-continuous usage as coal is delivered. The annual outage is often scheduled concurrently with the shutdown of the coal mine(s) supplying the coal to the plant. Because of the unique designs of this type of equipment, care should be taken to first refer to the maintenance activities recommended by each site’s specific equipment manufacturer. The manufacturer’s recommendations should be the primary source of guidance in these cases. 3-8


Table 3-2 Recommended Preventive Maintenance Maintenance for Rotary Railcar Dumpers Courtesy of Heyl & Patterson, Inc. Item


Frequency

Platen

Visually inspect the locking device to ensure that proper alignment with rack is obtained soon after loaded l oaded car comes into contact with spill plate and dumper begins to rotate.

Daily

Clamp brake

Visually inspect clamp break and adjust parts as necessary. Adjust jack screw to achieve uniform clearance between band and drum when released. Adjust spring(s) for proper extensions when brake is set. Visually inspect length of spring(s) to ensure proper extended lengths.

Weekly

Car clamps

Operate dumper empty to ensure that each clamp operates smoothly without binding. Visually inspect to ensure that the droop of the outer ends of the clamps is present (excessive droop will cause severe over-stressing of the tag line).

Weekly

Visually inspect sheaves, rollers, and chains to ensure that there is no corrosion or physical degradation. Visually inspect tag line spring to ensure that it retains its initial tension. Visually inspect welds for fracture or excessive corrosion. Ensure that keeper bars are properly seated. Visually inspect bolts, confirming that they are tightened to manufacturer’s recommended torque values. Limit switches

Operate the dumper with an empty car to ensure that the limit switches function properly as described in the manufacturer’s operations and maintenance manual.

Weekly

Dumper rotating and platen rails

Visually inspect dumper and platen rails for cracks or loose bolts.

Weekly

Visually inspect clearance between platen rails and yard rails mounted on foundation. There should be about 1/2 in. (12.7 mm) in clearance.

Dumper structure and machinery

Visually inspect the structure for excessive corrosion, bending, or physical deformation. Perform painting repairs as needed.

Monthly

Speed reducer

Drain and refill after first month of operation, then replace lubricant every six months.

As noted

Dumper rotating drive and car clamp chains

Visually inspect chains for rusting and loose pins, paying particular attention to bolts and pins at anchor points.

Weekly

Spray car clamp chains with mixture of two parts kerosene to one part light oil. Grease clamp chain anchor pins.

3-9


Table 3-2 (continued) (continued) Recommended Preventive Maintenance Maintenance for Rotary Railcar Dumpers Courtesy of Heyl & Patterson, Inc. Item


Frequency

Platen thrust wedges

Visually inspect wedges to ensure that there is about a 1/4-in. (6.4-mm) gap between the wedges on the foundation and those mounted on the platen. The platen might shift to one end of the dumper pit due to locomotive traction forces.

Monthly

Platen rollers

The platen rollers should be rotated about 90°. In order to accomplish this, the empty dumper should be rotated to the dump position and the roller turned by hand.

Every six months

End ring rails and wheels

Visually inspect end ring rails for cracks and loose bolts. Do not permit ring rails to have a gap under the base of the rail between hold-down bolts.

Monthly

Drive brakes

Visually inspect brake shoes for wear and the brake drum for any scoring or cracks. Confirm that the shoes are not dragging on the drum.

Monthly

Maintain brake adjustment in accordance with the manufacturer’s recommendations. Car spotter sensors

Check operability of sensors.

Monthly

Clean transmitter and receiver lenses as needed. Positioner carriage rollers

Visually inspect positioner rollers for excessive tread wear and corrosion.

Monthly


To prevent rotation of the rotary car c ar dumper when taken out of service for maintenance or repair, a positive lock should be provided. The positive lock should consist of a pair of come-alongs or chain falls tied off by chain or cables to the dumper drive chain or rotate structure, with the come-alongs or chain fall anchored to the foundation. The positive locks are required any time the drive train is broken or the dumper drive d rive brake is deactivated for service or repair. Failure to lock the dumper in the seated position could cause misalignment problems after repairs or servicing are complete, damage to the dumper, or injury to maintenance personnel.

3.2.2.2

Turnover Railcar Dumper

Table 3-3 summarizes typical PM activities for a turnover railcar dumper. Because of the unique designs of this type of equipment, care should be taken to first refer to the maintenance activities recommended by each site’s specific equipment manufacturer. The manufacturer’s recommendations should be the primary source of guidance in these cases.

3-10


Table 3-3 Recommended Preventive Maintenance for Turnover Railcar Dumpers Courtesy of Heyl & Patterson, Inc. Item


Frequency

Platen

Lubricate platen roller pins (pressure fitting).

Every 8 hours

Platen lock assembly pin

Lubricate lock arm pin (pressure fitting).

Every 8 hours

Dumper drive

Lubricate reducer, couplings, and pinion.

Every six months

Lubricate pillow blocks.

Every 8 hours

Trunnion pillow block Lubricate pillow blocks. assembly

Every 8 hours

Platen lock support

Every 8 hours

3.2.2.3

Lubricate platen hook pin (pressure fitting).

Train Positioner

Table 3-4 summarizes typical PM activities for a train positioner, wheel chock, and rope tensioner hydraulic system. Because of the unique designs of this type of equipment, care should be taken to first refer to the maintenance activities recommended by each site’s specific equipment manufacturer. The manufacturer’s recommendations should be the primary source of guidance in these cases. Table 3-4 Recommended Preventive Maintenance for a Train Positioner System Courtesy of Heyl & Patterson, Inc. Item Hydraulic system


Frequency

Check the pressure switch setting on the pumps to ensure that the pumps unload properly and that the accumulators are properly charged. Failure to pump to unload indicates the pressure switch is inoperative or set too high or the relief valve setting is too low. Proper functioning of the pressure switch and accumulator is indicated when the pressure gauge adjacent adj acent to the switch shows a slow uniform decay of pressure in the system of each cycle until the pump cut-in pressure is reached. A definite i ncrease in the rate of decay of the pressure in the late stage of the cycle indicates in dicates that the pump cut-in pressure is below that of the charge of the accumulator.

Monthly

Visually inspect all manual valves on the drain line to the reservoir: they must be closed during startup; otherwise, pressure cannot build up.

At startup

Visually inspect the cushioning of the arm-actuating cylinder and adjust the valve if necessary to obtain a smooth stop of the positioner arm at the end of its stroke.

Monthly

Visually inspect return line filters for cleanliness.

Monthly

3-11


Table 3-4 (continued) (continued) Recommended Preventive Maintenance for a Train Positioner System Courtesy of Heyl & Patterson, Inc. Item


Frequency

Positioner overtravel limit switches

The positioner overtravel limit switches are typically magnetic proximity limit switches that require a visual inspection and operability check to ensure that they are functioning properly. Ensure that the switches are set accurately to the manufacturer’s recommendations. Improper setting can cause a malfunction and wreck the dumper positioner.

Monthly

Positioner reference switches

The positioner reference switch is typically located on the positioner runway and is used to calibrate cal ibrate the resolver with respect to the location of the positioner. Check the switches to ensure that they are working properly and being actuated by the striker located on the bottom of the carriage hold-down bracket.

Monthly

Resolver and speed increaser

The resolver is typically located on the rear of the drum base next to the drum pinion shaft. The resolver, stub shaft, and couplings should be checked for proper alignment al ignment and operation. Excessive play or budding in any of these parts will result in erroneous positioning of the railcars. The positioner cannot operate with a resolver.

Monthly

Arm positioner sensing element

The arm positioner sensing elements typically consist of photoelectric sensors. Clean their projectors and reflectors to prevent malfunction.

As needed

Positioner wheel chocks

Visually inspect chocks to ensure that they move freely.

Monthly

Apply grease to pins and other miscellaneous items. Ensure that the car wheels are not battering the sloping portions that actually contact the wheels. Visually inspect to ensure that anchor bolts are tight. Ensure that chocks retract readily from beneath the wheels.

Positioner ropes

Visually inspect ropes to ensure that there is no excess slack.

Weekly

Positioner rope roller supports

Visually inspect supports to ensure that rope support rollers turn freely.

Monthly

Visually inspect rope guides for wear, corrosion, or fracture. Visually inspect rollers for excessive wear, corrosion, or fracture. Oil tight gear guards

Change oil after the first month of o peration and every six months thereafter. Breakers should be cleaned and re-oiled at about every 160 hours of operation.

3-12

As noted


Table 3-4 (continued) (continued) Recommended Preventive Maintenance for a Train Positioner System Courtesy of Heyl & Patterson, Inc. Item


Bearings

Bearings should be inspected daily during operating hours. They should be checked to ensure that they are not overheating, leaking lubricant, or have lost their alignment.

Frequency As noted

Lubricate bearings in accordance with the be aring manufacturer’s recommendations. Gear reducers

Refer to Section 3.2.13 of this report for guidance on gearboxes and gear reducers.

As noted

Gear guards

Replace lubricant.

Every six months

Gear coupling

Replace lubricant.

Every six months

Bolts

Visually inspect foundation bolts, housing bolts, and fittings on all machinery for tightness, as vibration tends to loosen them. Ensure that bolts are tightened in accordance with the manufacturer’s recommended torque values.

Weekly

Couplings

Visually inspect lubrication levels and to ensure that lubricant is free Every six of contaminants. months

Wire rope

Lubricate wire rope with the lubricant recommended by the manufacturer. Lubrication should be done at intervals so that at least a light film of lubricant is on the ropes and sheaves at all times.

As noted

Visually inspect rope on a weekly basis to observe normal wear and to ensure that there is no excessive wear occurring due to rope contact with stationary parts. On a monthly basis, measure rope diameter d iameter with an accurate set of calipers across the rope’s largest diameter di ameter to ensure that the number of worn outer wires is not excessive. Sheaves and drums

3.2.2.4

Visually inspect sheaves and drums for excessive scoring or cuts and for improperly fitting grooves or broken flanges.


Table 3-5 summarizes typical PM activities for a rotary railcar dumper traveling hammermill. Because of the unique designs of this type of equipment, care should be taken to first refer to the maintenance activities recommended by each site’s specific equipment manufacturer. The manufacturer’s recommendations should be the primary source of guidance in these cases.

3-13


Table 3-5 Recommended Preventive Maintenance for Traveling Hammermills Courtesy of Heyl & Patterson, Inc. Item Rotor drive chains and sprockets

Preventive Maintenance Activities Visually inspect for abnormal wear on the sides of the sprocket teeth and on the sidebars of the chain. The wear will indicate misalignment in the drive.

Frequency Monthly

Visually inspect shaft and sprocket alignment. This check can reveal misalignment problems before wear on chai n and sprockets becomes apparent. Visually inspect for scratches, galls, grooves, or visible changes in tooth form. As the drive runs in, the working faces of the sprocket teeth should develop a bright, polished appearance. Check for abnormal chain elongation. A gradual increase in chain length is the result of normal wear. A sudden increase in slack indicates trouble in the drive and possible slippage in the rotate motor slide base. Clean chains and sprockets of dirt or foreign material packed into the chain or sprocket teeth. Debris can cause unnecessary wear or even chain or sprocket breakage. Visually inspect to ensure that chain tension is in accordance with the manufacturer’s recommendations. Hammer and T-bolts

Check the nuts for presence of the appropriate size bolts that prevent the nuts from turning loose.

Weekly

Check condition of T-bolt heads and grooves in lugs. Check hammers and/or bolts for wear by measuring distance from centerline of bolt to end of hammer, with hammer hanging vertically. Traverse chains

Visually inspect for rusting and loose pins, paying particular attention to pins at anchor points.

Weekly

Clean and lubricate per the manufacturer’s recommendations. Remove excess slack from chains by means of takeup furnished by the manufacturer. Check sprockets for excessive wear. Bearings


As noted

Lubricate bearings in accordance with the be aring manufacturer’s recommendations. Gear reducer

3-14


As noted


Table 3-5 (continued) (continued) Recommended Preventive Maintenance for Traveling Hammermills Courtesy of Heyl & Patterson, Inc. Item


Frequency

Bolts

Foundation bolts, housing bolts, and fittings on all machinery should be checked for tightness, as vibration tends to loosen them.

Monthly

Couplings

Lubricate couplings in accordance with the coupling manufacturer’s recommendations.

As noted

3.2.2.5

Stationary Barge Unloader

Table 3-6 summarizes typical PM activities for a stationary barge unloader. Because of the unique designs of this type of equipment, care should be taken to first refer to the maintenance activities recommended by each site’s specific equipment manufacturer. The manufacturer’s recommendations should be the primary source of guidance in these cases.

3-15


Table 3-6 Recommended Preventive Maintenance for Stationary Barge Unloaders Courtesy of Heyl & Patterson, Inc. Item


Frequency

Trolley runway rails

Visually inspect trolley runway rails for cracks, loose joints, and misalignment.

Weekly

Structural joints and sheave supports

Visually inspect for loose rivets, cracked members, rust, excessive wear, or other signs of deterioration.

Monthly

Engine reducers

Check oil level in reducers on hold, close, trolley, and barge haul engines. Add oil if needed.

Weekly

Bearings


As noted

Lubricate bearings in accordance with the bea ring manufacturer’s recommendations. Ropes, drums, sheaves, and rails

Ensure that ropes, drum scores, sheave grooves, trolley rails, and wheels are coated with a film of lubricant to minimize wear, in accordance with the manufacturer’s lubrication instructions.

Monthly

Hold-and-close ropes

Advance the hold-and-close ropes approximately 50–100 ft (15–30 m) after 200,000 tons (181,400 metric tons) of material have been unloaded.

As noted

Hold-and-close engine

Lubricate in accordance with manufacturer’s recommendation.

Per manufacturer

Reeving winch Bucket Barge haul engines Sheave supports Barge haul cable hoist

3.2.2.6

Bucket Barge Unloader

Table 3-7 summarizes typical PM activities for a bucket barge unloader. Because of the unique designs of this type of equipment, care should be taken to first refer to the maintenance activities recommended by each site’s specific equipment manufacturer. The manufacturer’s recommendations should be the primary source of guidance in these cases.

3-16


Table 3-7 Recommended Preventive Maintenance for Bucket Barge Unloaders Courtesy of Heyl & Patterson, Inc. Item


Frequency

Sheave and drum

Visually inspect sheave and drum to ensure that they are not excessively scored or have improperly fitting grooves or broken flanges. Welds on drums are typically stress-relieved during the manufacturing process, but the drums should be visually inspected to identify any cracked welds. The most convenient time to inspect the drums and sheaves is when the mating rope is lubricated or replaced.

As noted

Gear guards

Oil-tight guards are typically provided where constant oiling is required. All guards containing oil should have the oil changed after the first 30 days of operation and an d every six months thereafter. Oil level should be checked daily. Breathers should be cleaned and reoiled every 160 hours of operation.

As noted

Bearings


As noted

Lubricate bearings in accordance with the bearing manufacturer’s recommendations. Gear reducer


As noted

Bolts

Foundation bolts, housing bolts, and fittings on all machinery should be checked for tightness, as vibration tends to loosen them.

Monthly

Couplings

Lubricate couplings in accordance with the coupling manufacturer’s recommendations.

As noted

Trolley rails and wheels

Visually inspect rails and wheels for loose connections on the trolley stringers.

Monthly

Check track gauge to ensure that it is within the manufacturer’s allowable tolerances. Visually inspect trolley wheels to ensure that the treads are not severely worn or the flanges cracked. Trolley travel ropes

Visually inspect travel ropes to ensure that slack is not excessive.

Weekly

Trolley thrust rollers

Visually inspect thrust rollers to ensure that they are making proper contact with the rail head and that there is no excessive play.

Weekly

Barge haul ropes

Visually inspect haul ropes to ensure that there are no fraying, cuts, bends, or excessive wear spots.

Weekly

Lubricate ropes in accordance with the manufacturer’s recommendations. Hoists

Hoists should be maintained in accordance with the manufacturer’s recommendations. Additional guidance is provided in the EPRI report Lifting, Rigging, and Small Hoist Usage Program Guide [14]. [14].

As noted

3-17


3.2.3 Unloading Hoppers Because most unloading hoppers do not contain any moving parts, the PM activities consist primarily of visual inspections of the hopper cone and support structure. Inspections of the hopper walls are most effective when the hopper is empty. Table 3-8 summarizes these inspections. Table 3-8 Recommended Preventive Maintenance for Coal Unloading Unloading Hoppers Courtesy of Roberts & Schaefer Company Item


Hopper walls

Frequency

Visually inspect hopper walls for excessive corrosion and wear.

Monthly

Perform ultrasonic thickness tests.

Quarterly

Hopper liner

Visually inspect hopper liner for cracks, excessive corrosion, wear, and separation from the hopper wall.

Monthly

Hopper structure

Visually inspect the hopper structure for loose or missing bolts, failed welds, excessive corrosion, or physical deformation that could adversely affect the structural integrity of the hopper assembly.

Monthly


3.2.4.1

Lock-Out/Tag-Out Lock-Out/Tag-O ut Procedure

As with any industrial equipment, a sampling system can be hazardous if proper care is not taken during operation and maintenance activities. An appropriate lock-out/tag-out procedure should always be followed when working on the sampling system. The lock-out/tag-out procedures should comply with all local regulations, plant rules, and standard safety practices.

3.2.4.2

Housekeeping Key Human Perfor Perfor mance Point Point

Housekeeping is the first component of maintaining a sampling system. Keeping the sampling system clean is very important to the long-term performance of a sampling system.

Small amounts of material leaking from the sampling system are normal and can come from various places. It can come from improperly adjusted skirts, conveyor belts, or open doors. In order to minimize material leakage: •

All skirt boards should be properly adjusted.

•

All doors should be closed tightly.

3-18

Preventive Maintenance for Coal Handling System Components •

All gaskets should be in place and in good condition.

•

All dust seals should be in good condition and properly adjusted.

•

Belt scrapers should be in good condition and properly adjusted.

Excess piles of material can affect the sampling system in many ways. Material that builds up inside of chutes and flow areas can cause material plugs. Material that builds up around the outside of feeders can cause belt tracking problems and damage to the equipment. Excess dirt and material built up around lubricated components like bearings or roller chains can shorten their service life. Finally, piles of material can get in the way or hide problems when sampling equipment is serviced. •

•

•

•

•

Any piles of material around the sampling system should be removed daily. Piles of material under a feeder or conveyor should never be allowed to build to the point that they come in contact with the belt. Any material around bearings and idlers should be removed. Motors and reducers should be thoroughly cleared of dirt, dust, and buildup at least once per month. This will ensure their ability to run cool and not overheat. The equipment should be visually inspected for significant rust. Paint should be touched up as required. Key Human Perfor Perfor mance Point Point

Good housekeeping of the sampling system and minimizing the amount of fugitive coal particles greatly reduces the risk of fire from spontaneous combustion.

3.2.4.3

Daily Walk Through

In order to ensure its proper functioning, the sampling system should be inspected daily. Before the system is placed in service for the day, an operator should walk through the sampling system and visually inspect all of the equipment. The operator should use this inspection checklist: •

•

Check that all of the containers on the sample collector are empty and ready to go. Open all accessible access points and verify that there is no material buildup and that chutes are clear.

•

All guards and covers should be in place. All doors should be closed.

•

The sampling system should be clear of all debris and obstructions.

•

All spilled material should be removed, following good housekeeping practices.

•

Look for any mechanical problems with the equipment.

•

Look for leaking fluids. 3-19


After the initial walk through, the sampling system can be operated in automatic mode. While the system is running in automatic, another walk through should be performed. Check the following things while the system is running: •

Listen for unusual noises from mechanical components. A squealing bearing or grinding reducer can indicate imminent mechanical failure.

•

Check the tracking on all belts.

•

Look for excess dust or material spilling from the system.

•

Verify that settings are correct on the operator interface.

Experience will show if there are any additional items that need to be added to the daily inspection. Any specific causes for concern should be communicated to the next shift so that any unresolved potential problem areas can be fixed or closely watched.

3.2.4.4

Periodic Maintenance

Proper lubrication of the sampling system is imperative for continued performance. A lubrication schedule should be set up and strictly followed. Reference the information on the individual pieces of equipment for specific PM and activities, including lubrication schedules, in Table 3-9. Table 3-9 Recommended Preventive Maintenance for Coal Sampling Equipment Courtesy of Thermo Electron Corporation Item Primary sampling machine

Preventive Maintenance Activities Periodically check sample cutter for wear. Keep as clean as possible, cleaning every 30 days or fewer. Adjust cutter brushes and wipers as required. Grease the main bearings with Keystone #84H Light or equal. Check oil level in gearbox. 15–60°F (-9.4–15.5°C) use AGMA Lube #2. 50–125°F (10–51.6°C) use AGMA Lube #4.

3-20

Frequency Monthly


Table 3-9 (continued) (continued) Recommended Preventive Maintenance for Coal Sampling Equipment Courtesy of Thermo Electron Corporation Item Primary belt feeder

Preventive Maintenance Activities Periodically check the gear reducer lubricant. Refer to the manufacturer’s specifications for proper lubricants.

Frequency Monthly

Note: the Note: the mechanical variable-speed reducers use a special synthetic traction fluid in their variable reduction mechanism. It is critical that the proper fluid be used in these reducers or equipment damage could occur. Check belt feeder after initial break-in period for belt stretch and proper training. Lubricate bearings with Mobilux EP2 or equal grease. Periodically check drive speed to see that it has not drifted out of adjustment. Coal sampling crusher (see Notes 1 and 2)

Check to ensure that bearings do not run hot or noisy.

Weekly

Check bolt connections frequently, particularly in the beginning of using machine, in order to establish if any bolt connection has a tendency to work loose. Check inside the machine to make certain that no problems exist. Check entire drive to see that sheaves have not worked loose on their shafts and the bolts have the correct tension. The shaft in this crusher is equipped with high-quality bearings. The bearings are pre-lubricated when the crusher is shipped.

Monthly

The bearings should be re-lubricated as per the instructions located in the crusher manual. It is recommended that the bearings be lubricated at least monthly, but experience with the crusher and observation will dictate the appropriate i nterval. The bearings are typically lubricated through a lubrication line connector, one on each side of the machine. Secondary sweep sampler

Periodically check sample cutter for wear.

Monthly

Keep as clean as possible, cleaning every 30 days or fewer. Adjust cutter brushes and wipers as required. Grease the main bearings with Keystone #84H Light or equal. Check oil level in gearbox. 15–60°F (-9.4–15.5°C) use AGMA Lube #2 50–25°F (10–51.6°C) use AGMA Lube #4.

3-21


Table 3-9 (continued) (continued) Recommended Preventive Maintenance for Coal Sampling Equipment Courtesy of Thermo Electron Corporation Item Secondary feeder

Preventive Maintenance Activities Periodically check the gear reducer lubricant. Refer to the manufacturer’s specifications for proper lubricants.

Frequency Monthly

Note: the Note: the mechanical variable-speed reducers use a special synthetic traction fluid in their variable reduction mechanism. It is critical that the proper fluid be used in these reducers or equipment damage could occur. Check belt feeder after initial break-in period for belt stretch and proper training. Lubricate bearings with Mobilux EP2 or equal grease. Periodically check drive speed to see that it has not drifted out of adjustment. Sample collector

Reject return conveyor

The can-collecting machine has a drive supplied with oil filler and vent plugs. The gearbox can be topped up using a standard gear lubricant, such as Mobil EP-90. The gear oil level should be checked periodically to ensure correct level. Before removing the filler plug, the area around the filler hole should be completely cleaned of contaminating material. Any abrasive material entering the gearbox will cause damage to the gear train and eventual failure of the drive.

Monthly

The gearbox oil should be drained and replaced with fresh oil after at least every two years of operation.

As noted

Periodically check the gear reducer lubricant. Refer to the manufacturer’s specifications for proper lubricants.

Monthly

Check belt feeder after initial break-in period for belt stretch and proper training. Lubricate bearings with Mobilux EP2 or equal grease. Periodically check drive speed to see that it has not drifted out of adjustment.

3-22


Table 3-9 (continued) (continued) Recommended Preventive Maintenance for Coal Sampling Equipment Courtesy of Thermo Electron Corporation Item Sweep sampler


Frequency

The sweep sampler requires regular maintenance in o rder to reach peak performance. Inspect the sampler daily at first, paying particular attention to the stopping distance of the cutter. After the initial break-in period, check the sampler operation weekly.

As noted

Check the adjustment of the magnetic limit switch and the target. The limit switch and target should indicate i ndicate whenever the sample cutter is in the material stream. It is a critical component for safe operation of the sweep sampler. Check all fasteners and set screws for proper tightness. Adjust the sweep brush and wiper as they wear. Adjust the brake as necessary. The brake will need adjustment periodically to maintain the proper cutter stopping distance. The discharge position is at the eight-o’clock position. The sample cutter should normally stop between the nine-o’clock and oneo’clock positions. The interval between brake adjustments will depend on the frequency of operation of the sampler. Check the skirt board adjustments, making sure they are ad justed down to the belt. The oil level in the gear reducer should be checked periodically. The first oil change should be after 800 hours of operation and every 8000 hours thereafter. The pillow block bearings should be greased at least once every 1000 hours of operation with Lithium Base No. 2 grease. Notes and Warnings: 1. Before any assembly, disassembly, disassembly, or maintenance maintenance is started, make certain certain that power to the machine machine is locked out and cannot, by any means, be unintentionally restored. 2. To keep the machine operating at maximum maximum capacity and to to avoid unscheduled interruptions interruptions due to breakdown or other events, events, a regular inspection and maintenance program is required.

3.2.4.4.1

Plugged Chute Sensors

Plugged chute sensors should periodically be checked for proper operation. Test to make sure that the sampling system indicates a plugged chute if material is placed in front of the sensors for longer than the failure timers are set for. The plugged chute sensors should be checked monthly at a minimum. Experience might dictate a more frequent inspection.

3-23


3.2.4.4.2

Sample Cutter Lips

The lips on sample cutters are designed to provide long service life and wear resistance. However, they are subjected to a great amount of material impact and will eventually wear to the point that they need replacing. Sample cutter lips should be inspected at least monthly, more often in extreme service conditions. They should be checked for excessive wear. If adjustable, they should also be checked for proper opening adjustment. 3.2.4.4.3

Primary Sampler

The primary sampler often encounters a very severe service environment and might need special attention. The following inspection should be performed weekly at a minimum, but experience might dictate an increased inspection frequency. With the sample cutter in manual mode, move the cutter through its range of motion. Verify that the brushes and wipers are in contact with the belt across the entire belt. The sampler should stop correctly at about the nine-o’clock position at the end of travel. 3.2.4.4.4

Additional Sweep Sampler Adjustments

Sweep samplers need periodic adjustments for proper performance. The following adjustments should be checked weekly. Extreme service conditions or other factors could require an increase in the frequency of these inspections and adjustments. •

•

•

•

Check the brush assembly on the sample cutter for proper adjustment. Check the adjustment of the cutter position target. It should be tight on the cutter shaft and should not have moved from the correct position. Check the adjustment of the brake. It should properly stop the sample cutter outside of the material stream on the belt. Check the adjustment of the skirts and seals on the sweep sampler to limit material leakage.

3.2.4.4.5

Feeder/Conveyor Inspections

Sample feeders and conveyors need periodic inspections to ensure proper service. These inspections should be performed monthly, or more often in severe service conditions. •

•

Check the adjustment of any skirts and dust seals to limit material leakage. Verify that feeders with variable-speed adjustments are set to the correct belt speed. Note: never adjust a mechanical variable-speed reducer unless the feeder is running. Adjusting these reducers while not running could severely damage them.

•

Check belt scrapers for excess wear and/or proper adjustment.

•

Check takeup adjustment and belt tracking.

3-24



All disassembling, assembling, and adjustment of parts should be executed only by personnel who have good fundamental and practical knowledge of machines and mechanical devices.

3.2.5 Coal Crushers Tables 3-10 through 3-13 provide PM activities for the types of coal crushing equipment most commonly installed at a fossil power plant.

3.2.5.1

Breakers

Table 3-10 provides the recommended PM activities and their frequencies for breakers/compactors. Table 3-10 Recommended Preventive Maintenance for Breakers/Compactors Breakers/Compactors Courtesy of Pennsylvania Crusher Corporation Item


Frequency

Feed chute and first section of cylinder

Visually inspect for any plugging in the feed chute and the first section of the cylinder.

Weekly

Tires

Check that tires are tracking on wheels without excessive thrust on wheel flanges.

Weekly

Ejection assembly

Visually inspect to ensure that the amount of coal in the refuse ejection assembly is not excessive.

Monthly

Wheel bearings and chain casing

Check oil level.

Monthly

Visually inspect wheel bearings, chain casing, and reducer for lubricant loss. Replace if necessary.

Semiannually

Ensure that wheel bearing temperatures are not excessive.

Cylinder

Lubricate wheel bearings in accordance with manufacturer’s recommendations.

Semiannually

Visually inspect chain casing lubricant for excessive signs of sludge. Change if needed.

Semiannually

Inspect casing and seals for excessive wear. Re-lubricate and clean chain casing.

Annually

Inspect cylinder interior for wear and loose or missing parts.

Semiannually

Note and report any unusual noise or vibration.

3-25


Table 3-10 (continued) (continued) Recommended Preventive Maintenance for Breakers/Compactors Breakers/Compactors Courtesy of Pennsylvania Crusher Corporation Item Screen plate bolts


Frequency

Visually inspect screen plate bolts for tightness. Retighten bol ts as needed.

Semiannually

Tighten all screen case bolts. Gear couplings

Lubricate gear couplings in accordance with manufacturer’s recommendations.

Semiannually

Friction pads

Visually inspect fluid coupling friction pads for excessive wear or deformation. Replace if necessary.

Semiannually

Reducer seals

Lubricate reducer seals in accordance with manufacturer’s recommendations.

Semiannually

Beam liners

Visually inspect longitudinal beam liners for wear and tightness.

Semiannually

Check and tighten spider/longitudinal beam bolts. Check spiders for wear on cones. Check longitudinal beams for wear.

Annually

Clutch coupling

Visually inspect clutch coupling, alignment, and shoe wear.

Annually

Drive base plate

Check and tighten bolts on drive base plate.

Annually

Sprocket

Visually inspect sprocket teeth for excessive wear.

Annually

Chain

Visually inspect chain for tightness in accordance with manufacturer’s recommendations.

Annually

3.2.5.2

Cage Mills

Table 3-11 provides the recommended PM activities and their frequencies for cage mills.

3-26


Table 3-11 Recommended Preventive Maintenance for Cage Mills Courtesy of Pennsylvania Crusher Corporation Item


Frequency

Cage assembly

Visually inspect the cage assembly for physical damage, loose bolts, and broken or worn welds.

Monthly

Sleeve

Visually inspect sleeve for excessive wear or physical damage.

Monthly

Inner cage sleeve


Monthly

Outer cage sleeve


Monthly

Bearings and shaft

Lubricate bearings in accordance with the manufacturer’s recommendations.

Monthly

Housing liners

Visually inspect liners to ensure that there is no excessive wear, especially during the first few days of operation. Inspections should be performed monthly after that.

As noted

Labyrinth seal

Lubricate seals in accordance with the manufacturer’s recommendations.

Monthly

Tapered bearing

Visually inspect bearing for excessive wear, noise, vibration, or overheating.

Monthly

Locking assembly

Adjust as needed. Visually inspect assembly for missing parts, loose bolts, or signs of excessive wear or damage.

Monthly

Inner and outer shafts shafts

Visually inspect shafts for excessive wear or physical damage as evidenced by excessive noise, vibration, or heat.

Monthly

V-belt drive

Visually inspect belt to ensure that it is not worn, cut, frayed, or stretched from its original configuration.

Monthly

3.2.5.3

Granulators

Figure 3-1 illustrates the primary assemblies of a granulator requiring PM activities.

3-27


Figure 3-1 Sectional Drawing of a Granulator Courtesy of Pennsylvania Crusher Corporation

Table 3-12 provides the recommended PM activities and their frequencies for granulators. Table 3-12 Recommended Preventive Maintenance for Granulators Courtesy of Pennsylvania Crusher Corporation Item Rotor (see Note 1)

Preventive Maintenance Activities Visually inspect hammers for corrosion, physical deformation, and excessive or irregular wear. Check disk clamp nuts for tightness. If not tight, suspension arms will loosen and cause wear on the rotor key, rotor shaft, and suspension arm bore. In addition, vibration can occur.

3-28

Frequency Weekly


Table 3-12 (continued) (continued) Recommended Preventive Maintenance for Granulators Courtesy of Pennsylvania Crusher Corporation Item Bearings (see Note 2)

Preventive Maintenance Activities Visually inspect area in and around the bearing housings for excessive dirt and clean when necessary.

Frequency Semiannually

Visually inspect bearings for excessive wear. Lubricate, if needed, in accordance with the bearing manufacturer’s recommendations. Visually inspect bearing housing cap bolts and bearing housing hold-down bolts for tightness and tighten when necessary. Visually inspect the drive bearing to ensure that the stabilizing ring is free of corrosion and physical deformation and holds the bearing in place. Cage (see Note 3)

Visually inspect cage frame for loose bolts, corrosion, and signs of physical deformation or fracture.

Semiannually

Visually inspect cage breaker plate and screen plates for excessive wear and physical deformation. Liners

Visually inspect liners to ensure that fasteners remain tight and that there are no signs of excessive wear.

Semiannually

Tramp iron trap (see Note 4)

Clean trap of all accumulated material. This is typically performed through the frame top cover inspection doors usually located on the rear of the granulator. At this time, when the trap is empty, the hammers can be inspected for wear.

Semiannually

Upper and lower kickoff plates (see Note 5)

Visually inspect kickoff plates to ensure that mounting bol ts remain tight. Inspect for signs of excessive wear.

Semiannually

Notes: 1.

The hammers installed in the rotor of a granulator are typically manufactured from forged alloy heat-treated steel. The number of rows and hammer arrangement varies depending on the application.

2.

In many cases, granulator bearings are anti-friction, spherical, self-aligning roller bearings with a taper bore. To prevent axial movement, the bearing on the drive side of the granulator is often stabilized (held) in the bearing housing by a stabilizing ring. The stabilizing ring is omitted from the floating (free) bearing housing on the side opposite the drive to allow equal axial movement of the roller bearing in both directions. Although termed stabilized and and floating, the floating, the bearing housings are often identical.

3.

The granulator cage typically consists of the cage frame, cage breaker plate, and screen plates. The cage is often adjustable, mainly to compensate for wear and to vary the product size to some extent.

4.

Many granulators are equipped with a tramp iron trap that will collect finer sizes of crushed coal. Material that cannot physically be crushed (that is, steel, wood, and so on) that enters the granulator is carried around the length of the cage and past the kickoff plates by the rotating hammers. The centrifugal force that is developed is released as the uncrushed material passes into the tramp iron trap. The trap is usually filled with fine crushable material that forms a cushion to catch the uncrushed foreign materials.

5.

The kickoff plates are stationary extensions of the adjustable cage. They are typically perforated with openings to produce the required product. Normally, the kickoff plates do not wear with the same frequency as screen plates and do not require replacement as often.

3-29


3.2.5.4

Hammermills

Table 3-13 provides the recommended PM activities and their frequencies for hammermills. Table 3-13 Recommended Preventive Maintenance for Hammermills Courtesy of Pennsylvania Crusher Corporation Item Rotor (see Note 1)

Preventive Maintenance Activities Visually inspect hammers for corrosion, physical deformation, and excessive or irregular wear.

Frequency Weekly

Visually inspect for excessive wear on suspension su spension bars and cotter pins on each end of the suspension bars. Check disk clamping nuts for tightness. If not tight, suspension disks will loosen and cause wear on the rotor key, rotor shaft, and suspension disk bore. In addition, addi tion, vibration may occur.

Semiannually

Visually inspect suspension bar holes in suspension disks for any elongation. After a long period of service, this can occur. Visually inspect outside diameter of the suspension disks in relation to the suspension bar holes to determine that the wear is not approaching close to the suspension bar holes. Liners

Visually inspect liners to ensure that fasteners remain tight and that there are no signs of excessive wear.

Semiannually

Cage assembly

Visually inspect cage frame for loose bolts, corrosion, and signs of physical deformation or fracture.

Semiannually

Visually inspect cage breaker plate, tie plates, and screen plates for excessive wear and physical deformation. Bearings (see Note 2)

Visually inspect area in and around the bearing housings for excessive dirt, and clean when necessary.

Semiannually

Visually inspect bearings for excessive wear. Lubricate, if needed, in accordance with the bearing manufacturer’s recommendations. Visually inspect bearing housing cap bolts and bearing housing hold-down bolts for tightness and tighten when necessary. Visually inspect the drive bearing to ensure that the stabilizing ring is free of corrosion and physical deformation and is holding the bearing in place. Notes: 1.

Hammermill rotors are typically equipped with differentially heat-treated, forged-alloy steel hammers. The heat treatment provides a 500–550 Brinell hardness pre-hardened head (to resist wear), with progressively lower hardness in the shank and eye for toughness.

2.

In many cases, hammermill bearings are anti-friction, spherical, self-aligning roller bearings with a taper bore. To prevent axial movement, the bearing on the drive side of the machine is often stabilized (held) in the bearing housing by a stabilizing ring. The stabilizing ring is omitted from the floating (free) bearing housing on the side opposite the drive to allow equal axial movement of the roller bearing in both directions. Although termed stabilized and and floating , the bearings are often identical.

3-30


3.2.6 Reclaim Hoppers A vibratory, drawdown type of reclaim hopper uses a foot-mounted motor, standard V-belts, and pulleys to drive a shaft-mounted eccentric weight, which causes the vibration necessary to move the coal. Under normal operating conditions, these drives are very reliable. However, a regular maintenance schedule is required for trouble-free operation. Table 3-14 provides the recommended PM activities and their frequencies. Table 3-14 Recommended Preventive Maintenance for Vibratory Drawdown Reclaim Hoppers Courtesy of Carman Industries, Inc. Item Foot-mounted motor

Preventive Maintenance Activities Visually inspect motor to ensure that leads are properly connected and the motor is grounded in accordance with the manufacturer’s recommendations.

Frequency As noted

Lubricate the motor in accordance with the manufacturer’s procedure. Drive shaft bearings

Visually inspect bearings for abnormal wear, vibration, or excessive noise or heat.

As noted

Lubricate and clean out bearings in accordance with the manufacturer’s procedure. The lubrication and clean-out frequencies will vary depending on the type of bearing and the severity of the service. V-belt

Visually inspect V-belt for cracks, tears, uneven wear patterns, or excessive stretching.

Weekly

Pulleys

Visually inspect pulleys for fractures, deformation, corrosion, and signs of excessive wear.

Weekly

Bolts and fasteners

Visually inspect bolts and fasteners for excessive wear and corrosion. Ensure that they are tightened in accordance with the torque values recommended by the manufacturer.

Monthly

Shaft-mounted eccentric weight

Visually inspect weight and shaft to ensure proper fit and tightness. Ensure that they are not corroded, cracked, or bent.

Weekly

3-31


3.2.7 Discharge Hopper Feeders Table 3-15 provides the recommended PM activities and their frequencies for discharge hopper feeders. Table 3-15 Recommended Preventive Maintenance for Discharge Hopper Feeders Courtesy of General Kinematics Corporation Item Feeder motor

Preventive Maintenance Activities Lubricate per motor manufacturer’s recommendations or as follows: Clean the exterior of the motor.

Frequency 6000 to 8000 hours for normal conditions

Remove both the grease plug and relief plug (if supplied). If grease has hardened, run a rod or wire a short distance into the chamber to break grease. In severe conditions, run motor until bearing chamber becomes heated. Re-grease motor with low-pressure grease gun.

3000 to 4000 hours for severe conditions

For optimum operation, the bearing chamber should be threequarters full of grease. Operate motor for a minimum of one hour. Replace grease plug(s). Ground strap

Visually inspect fasteners for tightness. Also, check for corrosion buildup between the strap and grounding structure.

Weekly

Wire rope and safety cables

Check for any signs of corrosion or excessive excessi ve wear on the wire rope and safety cables, which are required on all suspensionmounted units. All cable clips should be regularly checked for tightness to prevent slippage.

Weekly

Motor cables

Make periodic checks of all electric motor cables for wear or damage. All ground wires should be securely and properly fastened.

Weekly

Fasteners

Visually inspect fasteners (bolts) and tighten as needed.

Monthly

Stroke plate

The vibration amplitude or stroke of the trough is the indicator of the unit’s performance. Visually inspect the stroke of the un it to ensure that it is operating at the intended stroke. The stroke varies for each unit depending on its i ts application. In most cases, the required stroke will be shown on the manufacturer’s drawings or maintenance instructions.

Daily

Wheel rotary joints

Rotary joints often have seals with an oil wick that keeps the seal faces lubricated. The oil wick should be lubricated per the manufacturer’s recommended intervals (typically every 200 to 300 hours of operation).

As noted

3-32


Table 3-15 (continued) (continued) Recommended Preventive Maintenance for Discharge Hopper Feeders Courtesy of General Kinematics Corporation Item Air line filter

Preventive Maintenance Activities To maintain maximum filtering efficiency and to avoid excessive pressure drop, the filter must be kept clean. On standard filters, open drain cock periodically and drain off any bowl accumulation before it reaches level of baffle. Bowl drainage is automatic in the piston drain and auto drain; however, manual draining can also be done. A visible coating of dirt or condensate on the filter element ele ment surface or an excessive pressure drop is an indication that cleaning is necessary.

Frequency Monthly

3.2.8 Magnetic Separators As noted in Section 2 of this report, PM activities are required only for the overhead continuousremoval magnetic separators because the stationary design has no moving parts. Key Human Perfor Perfor mance Point Point

With the exception of taking some electrical e lectrical readings that require the magnet to be energized, all routine maintenance should be performed with the magnet deenergized and the drive motor off and locked out so it cannot be accidentally started. If the magnet has been on for a long time, it should be allowed to cool down, which can take several hours.

Table 3-16 summarizes the PM activities recommended by most manufacturers of magnetic separators.

3-33


Table 3-16 Recommended Preventive Maintenance for Magnetic Separators Courtesy of Dings Company Magnetic Group Item


Frequency

Magnet gearmotor

Visually inspect motor to ensure that it remains clean and the ventilation openings are clear of dust or other debris. Additional preventive guidance for gearboxes is provided in Section 3.2.13 of this report.

Weekly

Magnet bearings

Lubricate with lithium-based grease conforming to National Lubricating Grease Institute (NLGI) Grade 2.

Every two to six months (if clean) Monthly (if dirty)

Visually inspect hex-head screws and bearing bolts for tightness and corrosion. Tighten if loose.

Monthly

Magnet cooling oil (transformer-type)

Visually inspect oil level.

Quarterly

Self-cleaning belt

Periodically inspect for signs of wear and the vulcanized bond of the cleats.

Monthly

Fasteners

Visually inspect for wear, especially on the underside.

Monthly

Tracking of belt

Visually inspect belt to ensure that it is tracking correctly without overrun and rubbing along the sides. Ensure that belt tightness is appropriate and it is free of tears and cracks.

Monthly

Zero-speed switch

Visually inspect shaft seal for leakage or ingress of dirt. Visually inspect bearings for cleanliness and structural integrity.

Monthly

Pulley/shaft assembly

Visually inspect all crown curved pulley compression hubs to Every two to six ensure that they are properly tightened to the months manufacturer’s recommended torque. After startup, the hub bolts should be re-tightened to the following torques: 1 15/16–2 7/16 in. (4.9–6.2 cm) diameter shafts 180 in. lb (20.3 N-m) 2 15/16 in. (7.5 cm) diameter shafts 360 in. lb (40.7 N-m)

Rectifier

3-34

Visually inspect for cleanliness and to ensure that air inlets and outlets are free of dirt and dust. Clean and remove dust and debris from rectifier components and bottom surface inside of cabinet.

Quarterly


3.2.9 Slide Gates A specific maintenance schedule for each slide gate or diverter valve is dependent on cycle frequency, materials handled, temperature, velocity, and other factors. Routine inspection is recommended for determining maintenance needs. When placing a slide gate or diverter valve in a corrosive environment, care should be taken to ensure that all components are compatible with the environment and material handled. Corrosion of components can cause excessive heat buildup when operating slide gates and diverter valves. Inadequate cleaning of the valve could cause corrosion, resulting in friction, excessive heat generation, or erratic blade movement. Operating the gate/valve without regular scheduled maintenance could cause the mechanism to become rough-running and cause friction and heat generation. Scheduled maintenance is determined by the application and use of the gate/valve. Table 3-17 summarizes the PM activities recommended by most manufacturers of horizontal slide gates and diverter valves. Table 3-17 Recommended Preventive Maintenance for Slide Gates Courtesy of Salina Vortex Corporation Item


Frequency

Fasteners

Visually inspect all fasteners for tightness. Do not exceed fastener torque recommendations. All fasteners must be tight to ensure proper valve function.

Safety covers

Visually inspect covers to ensure that they are secure at all times.

Conduit and terminal connections

Visually inspect all electrical conduit connections and terminal connections for tightness and contact.

Weekly

Seals

If material leakage occurs to the exterior of the slide gate or diverter valve, seal adjustment or replacement is required. Please refer to the specific maintenance instructions provided with the manufacturer’s manual.

Weekly

Valve exterior

Clean the surface of the slide gate or diverter to keep all safety and functional decals visible.

3.2.9.1

Weekly

Daily

As needed

Cleaning and Washdown Procedures Key Human Perfor Perfor mance Point Point

De-energize the gate/diverter valve by removing electrical power, compressed air, and hydraulic power, and relieve any residual pressure or stored energy before removing covers.

3-35


3.2.9.1.1

External Cleaning

Many standard slide gates and diverter valves are designed to accommodate low-pressure water washdown. Cleaning should be done either with a vacuum cleaner approved for use in explosive zones, or with a damp cloth. Solvents or dry wool cloths must never be used for cleaning purposes. 3.2.9.1.2

Internal Cleaning

Before performing any internal washdown procedures, make sure the gate/diverter valve has the proper seal modifications for washdown. Additionally, if chemicals are added to the wash, care should be taken to ensure that the seals are compatible with the chemical. Do not wash the gate/diverter valve with the blade in the closed position. Cycling of the gate/diverter valve during washdown is an acceptable method of preventing liquid head pressure above the gate/diverter valve. Key Human Perfor Perfor mance Point Point

Never place hands, arms, fingers, or other body parts in the gate/diverter valve’s blade path.

Removal of the gate/diverter valve’s safety covers might be required for thorough cleaning. After washdown and cleaning, the internal components of the gate/diverter valve must be thoroughly dried before re-introducing material to the gate/diverter valve. Failure to dry thoroughly can cause material buildup and gate/diverter valve failure.

3.2.10 Dust Control System Table 3-18 summarizes PM activities typically performed on dust collection/suppression equipment installed in a coal handling system.

3-36


Table 3-18 Recommended Preventive Maintenance for Dust Collection Equipment Courtesy of Airtrol, Inc. Item


Frequency

Air exhaust

Visually inspect conditions of the air exhaust from the collector. If indication of dirty air appears, prepare to inspect filter bags for holes at the earliest opportunity.

Daily

Differential pressure indicator

Visually inspect and measure differential pressure. It should typically read between 3 in. and 6 in. (8 cm and 15 cm). Never allow pressure to exceed 9 in. (23 cm).

Daily

Dust handling system

Check dust handling system for proper operation.

Daily

Dust hopper

Visually inspect hopper for any evidence evi dence of dust accumulation or bridging.

Daily

Collector air header

Visually inspect for air leaks at the collector air header system and establish that the solenoid properly activates the diaphragm valve.

Weekly

Cleaning air pressure

Check air pressure during cleaning (pressure shoul d not exceed 10 psig [68.9 kPa]).

Weekly

Bearings

Visually inspect bearings and moving parts, and lubricate in accordance with each manufacturer’s recommendations.

Monthly

Filter bags

Visually inspect filter bags. Look for holes or tears that could decrease collection efficiency.

Quarterly

Access doors

Visually inspect access doors and ports for any signs of leakage.

Quarterly

Chains and belts

Check chains and belts to ensure that tension is within manufacturer’s recommended criteria.

Quarterly

Clean air plenum

Visually inspect the condition of the clean air plenum. There should be no dust on the tube sheet.

Quarterly

Rotating manifold

Check the operation of the rotating manifold.

Quarterly

3-37


3.2.11 Conveyor Belts, Pulleys, Idlers, and Rollers

3.2.11.1

General Guidance

Cleanliness is essential to good belt tracking. A buildup (of whatever material) on pulleys and rolls can easily destroy the perpendicularity of the roll or pulley face. Foreign matter, in essence, creates a new roll or pulley crown and thus adversely affects tracking. Likewise, cleanliness is essential to slider bed operation. A buildup of foreign materials (or a roughened portion of the slider bed face) will result in a differential of warp tensions across the width of the belt and can very easily throw a belt off-center. This can seriously affect training. To keep the rolls free from buildup, scrapers can be applied directly to bend rolls at the takeup area on a gravity takeup system. Ploughs installed prior to the tail roll under the loading section will prevent belt and pulley damage due to carryback.

3.2.11.2

Periodic Maintenance

The first step in performing PM to a conveyor belt system is to inspect the conveyor belt when the system is shut down and empty. This provides the opportunity to check for any damage to the belt or splice. Table 3-19 summarizes the PM activities recommended by most manufacturers of conveyor belt systems.

3-38


Table 3-19 Recommended Preventive Maintenance Inspections Inspections for Conveyor Belt Systems Courtesy of Georgia Duck-Enerka Status Shut down and empty (see Notes 1 and 2)

Preventive Maintenance Inspection Activities Check to ensure that the tail pulley pul ley is free from buildup and trapped material.

Frequency Weekly

Check for tail pulley damage. Check for physical damage or missing skirting in the loading area. Check for impact bed or impact idler damage. Ensure that slider bed is clean and smooth. Check for carrying-side idler damage. Ensure that carrying-side self-trainers are operational and not tied off. At any secondary loading stations, check for physical damage or missing skirting and for impact bed or impact idler damage. Check for any damage to the tripper frame. Ensure that the tripper discharge pulley is clean. Ensure that the tripper bend pulleys are clean. Check head pulley and/or drive pulley to ensure that they are clean and free of worn lagging (re-lag drive pulley if rubber is old, worn, smooth, and hard). Verify that head pulley cleaner or scraper is operational. Ensure that head pulley snub is clean. Verify that return idlers are clean and turning freely. Ensure that bend pulleys are clean. Ensure that takeup is clean. Ensure that return-side self-trainers are operational and not tied off. Ensure that there is no damage to return-side frame due to mistraining. Verify that plow or scraper in front of tail pulley is operational. Lubricate switches per manufacturer’s recommendations, and visually inspect switches to ensure that they are free of dirt and debris. Visually inspect conveyor holdback to ensure that it is free of corrosion and is not physically damaged.

Monthly

3-39


Table 3-19 (continued) (continued) Recommended Preventive Maintenance Inspections Inspections for Conveyor Belt Systems Courtesy of Georgia Duck-Enerka Status Belt running empty

Preventive Maintenance Inspection Activities The conveyor should be turned on and running. While it is empty, walk the conveyor to check for any tracking problems. Before any adjustments are made to correct a tracking problem, the system will need to be inspected under running conditions when loaded, because empty belts and loaded belts do not necessarily track the same way.

Frequency Daily

Verify the operability of conveyor holdbacks to ensure that any inclined belts do not run in reverse when stopped. Belt running loaded

Ensure that the tail pulley is turning freely without bearing noise, Daily product buildup, or carryback. Ensure that belt is tracking satisfactorily. Verify that there is no load area spillage. Ensure that the carry-side idlers are turning freely. Verify that the carry-side self-trainers are functioning. Verify that there is no secondary loading station spillage. Ensure that the tripper area is tracking properly and free of spillage. Verify that the head pulley and/or drive pulley are running smoothly and demonstrate no slippage when starting or running. Ensure that belt cleaners are functioning and that the belt is tracking. Verify that the head pulley snub is turning freely without bearing noise and is clean. Check that return idlers are clean and turning freely. Check that bend pulleys are turning freely without bearing noise and are clean. Ensure that the takeup pulley is turning freely without bearing noise, is clean, and is moving freely in the frame. Verify that the return-side self-trainers are functioning. Verify that the belt is tracking properly. Verify that the plow or scraper in front of the tail pulley i s functioning. Verify that various switches (for example, the speed switch, misalignment switch, safety switch, chute plug switch, and so on) are functioning properly.

Notes: 1.

The conveyor should be locked out while making this inspection.

2.

Numerous inspection items in the table contain the words clean or or operational . Pulleys or idlers with buildup will cause tracking problems. The same can be said for pulleys that have some of the rubber lagging worn off. Scrapers, plows, and self-trainers must be operational to perform their tasks. Belt damage, pulley damage, and tracking problems will result if these accessory pieces of hardware are not maintained.

3-40


3.2.11.3

Additional Preventive Maintenance Actions

Additional PM actions that should be considered include the following: Minimizing carryback – A conveyor system with carryback on the return side is the single most common reason that conveyor belts need to be replaced, return idlers and pulleys need to be replaced, and the structure is worn through. Material buildup on the belt and hardware causes tracking problems that will lead to edge damage, which in turn necessitates a new belt and new idlers. Most manufacturers strongly recommend the use of scrapers on the head pulley and plows in front of the tail pulley as prevention for damage.

Some sticky materials present a real challenge when it comes to preventing carryback. The following guidance should be considered when handling these products: •

•

•

•

•

•

Cleated belts can be reversed to allow better release at the discharge point. A dual scraper system on the head pulley is the most common way to eliminate product carryback. A water spray on the belt cover along with wiper blades will effectively prevent most products from sticking to the cover. A series of out-of-round (cam-shaped) return idlers will also assist in cleaning. These idlers are spiral-wound from the edges towards the center of the idler and are based on a turning beater bar arrangement. A compressed air blast has been successfully used on materials like coal and fine wet sand. A power-driven revolving brush will help remove product from the belt. This method is rarely used because the bristles tend to clog up with material and wear out quickly. A brush is sometimes the only solution for cleated belts.

Minimizing product buildup – Product buildup on return-side pulleys is a major concern. If the belt is not effectively clean on the return run, any bend pulley or head snub pulley that comes in contact with the carry side of the belt will accumulate product. The following guidance should be considered for pulley and idler cleaning: •

•

•

•

All return-side pulleys that come in contact with the carry cover can be lagged with a soft rubber vulcanized to the pulley. The constant flexing action of the soft lagging will cause material to fall off and reduce material accumulation. A lever-weighted urethane scraper pressed against the pulley face is an excellent way to remove buildup. This system causes additional wear on the pulley face, so it is suggested to use heavier walled return bend pulleys when using a scraper. If a scraper is applied to a head snub or bend pulleys at the takeup area, deflector plates will have to be installed to deflect the buildup away from the belt. Return idlers can be rubber-covered and will help prevent the coal product from sticking to the return idlers. Return idlers that are nothing more than disks mounted on a shaft are available. These disks can be made of soft rubber, urethane, or ceramic. This type of return idler can be very 3-41


effective in preventing buildup. The major problem with this style of return roller is that the manufacturers do not put enough disks on the shaft to effectively support the belt in the middle, nor to support the edges of the belt if any mis-tracking occurs. •

Another effective measure is called a turnover system. A series of rollers flips the belt over at the head and at the tail on the return side. This allows the belt to run the return side with the carry side (dirty side) up and the pulley side (clean side) down in contact with the return rollers. Any spillage from the product carryback will be limited to the two twist areas.

3.2.11.4

Cleaning Belts and Conveyor Components

Special care should be exercised to keep the return rolls and snub pulleys clean. Buildup of materials on this equipment has a destructive effect upon training, with the result that the belt can run against the structure and damage itself. Wherever possible, it is advisable that return idlers be suspended far enough below the structure so that any misalignment or dirty idlers can be easily seen. Keeping the return rolls and snubs clean requires that the belt be clean when it enters the return run. Scraping is the most common method of doing this. Rubber scrapers can be made by clamping rubber slabs 1/2-in. to 1-in. (1.3-cm to 2.5-cm) thick—not old belting—between two metal or wooden bars. Extend the rubber about twice its thickness beyond the bars and suspend the mechanism with a counterweight to provide pressure against the belt. Replace the rubber when it wears down near the bars. Two or three such scrapers can be used in succession. The most common steel scraper is a series of blades mounted diagonally on the end of a leaf spring to maintain pressure against the belt. These will scrape sticking materials that rubber scrapers might ride over. Washing the belt with a water spray before wiping with a rubber scraper will do a good cleaning job on almost almost any material, material, including including coal. Dry materials materials can be be cleaned off the belt belt with rotating rotating bristle or rubber vane brushes driven at fairly high surface speed, usually three to five times the belt speed. Such brushes wear rapidly, require considerable maintenance, and are likely to fill up solid if used with wet or sticky materials. It is often preferable to clean just after the head pulley and before the snub. An exception to this is that sticky material often requires scraping on the head pulley. This is because a large part of the fine material sticks to the belt and must be scraped into the chute. In some cases, the best possible cleaning is insufficient and steps must be taken to compensate for the effect of a dirty belt. Buildup on snub pulleys can be prevented with the use of soft rubber lagging or by scraping directly against the pulley. Diagonal grooving will distort and discharge accumulations on these pulleys. Rubber disk or spiral return rolls prevent buildup on themselves and thus avoid a training problem. The only cleaning typically required on the pulley side is removal of material, principally lumps, that might fall or bounce onto the return run and be carried between the belt and tail pulley if not 3-42


removed. Rubber-faced plows immediately in front of the tail pulley are often used for this purpose. They are usually held against the belt by gravity and set at an angle to the direction of belt travel.

3.2.12 Movable Tripper Devices Tables 3-20 and 3-21 summarize typical PM activities for motor-propelled and cable-propelled belt tripper devices, respectively, that can be installed in a coal handling system. Table 3-20 Recommended Preventive Maintenance for Motor-Propelled Motor-Propelled Belt Trippers Courtesy of FMC Technologies, Inc. Item


Frequency

Belt

Adjust the tripper to correct for conveyor belt run-out after it has been definitely determined that causes for the run-out are not in the conveyor belt itself.

As needed

Rails

Visually inspect tripper rails for location with respect to centerline of belt and for gauge, straightness, and levelness. Reset if necessary.

Monthly

Frame

Visually inspect tripper frame for position with respect to rails. Frame should be centered with the rails and sides parallel to the rails.

Monthly

Axles

Visually inspect axles to ensure that they are located at right angles to rails and tripper sides. Wheels should be tight on axles and properly centered in the frame within roller bearings that are provided. With rails in proper position sideward, the float of the tripper frame should not exceed 1/16 in. (1.6 mm) at any point along run. Reset to reduce float if necessary.

Monthly

Pulley shafts

Visually inspect pulleys to ensure that they are centered in frame and tight on the shaft. Shaft collars should be tight and located to hold shaft in i n centered position. Shafts should be level and at right angles to frame sides.

Monthly

Belt scraper or brush

Adjust when necessary. As the rubber scraper blade wears, adjust it within the frame by loosening the clamping bolts. Reverse blade when original surface has worn beyond point of further use. Avoid buildup of material on pulleys, as this will cause the belt to run off center. Keep rolls clear for tripper wheels.

As needed

Worm gear speed reducer

Change oil in worm g ear speed reducer and re-grease motor and roller bearings as specified in instructions furnished with the tripper by the origi nal manufacturer. Grease babbitted bearings regularly.

Quarterly

3-43


Table 3-21 Recommended Preventive Maintenance for Cable-Propelled Cable-Propelled Belt Trippers Courtesy of FMC Technologies, Inc. Item


Frequency

Belt

Adjust the tripper to correct for conveyor belt run-out after it has been definitely determined that causes for the run-out are not in the conveyor belt itself.

As needed

Rails

Visually inspect tripper rails for location with respect to centerline of belt and for gauge, straightness, and levelness. Reset if necessary.

Monthly

Frame

Visually inspect tripper frame for position with respect to rails. Frame should be centered, with the rails and sides parallel to the rails.

Monthly

Axles

Visually inspect axles to ensure that they are located at right angles to rails and tripper sides. Wheels should be tight on axles and properly centered in the frame within roller bearings that are provided. With rails in proper position sideward, float of tripper frame should not exceed 1/16 in. (1.6 mm) at any point along run. Reset one rail to reduce float if i f necessary.

Monthly

Pulley shafts

Visually inspect pulleys to ensure that they are centered in frame and tight on the shaft. Shaft collars shoul d be tight and located to hold shaft in centered position. Shafts should be level and at right angles to frame sides.

Monthly

Belt scraper

Adjust when necessary. As the rubber scraper blade wears, adjust it within the frame by l oosening the clamping bolts. Reverse blade when original surface has worn beyond point of further use. Avoid buildup of material on pulleys, as buildup will cause the belt to run off-center. Keep rolls clear for tripper wheels.

As needed

Propelling cable

To obtain maximum traction, wipe surface grease and d irt from the wire cable and sheave grooves of the haulage machine.

Monthly

Adjust the length of wire cable as the tensioning sheave reaches its end of travel. To adjust cable length, screw in either or both eye bolts at dead-ends of cable. Do not twist cable when adjusting the eye bolts. When adjustment limit is reached, screw eye bolts out and shorten wire cable in accordance a ccordance with the manufacturer’s cable reeving instructions. Tripper

Grease sheave pins in towing bracket and babbitt bearings in wheels and pulley shafts. Grease roller bearings as specified in the manufacturer’s tripper lubrication instructions.

Quarterly

Cable supporting rollers

Grease cable supporting rollers and tail sheave pin as needed.

As needed

Haulage machine

Change oil in worm gear speed reducer and re-grease motor, outboard bearing, and coupling as specified in the manufacturer’s specific instructions furnished with the haulage machine. Grease sheave bearing and pivot of tensioning sheave as needed.

Quarterly

3-44


3.2.13 Gearboxes

3.2.13.1

Condition Monitoring of Gearbox Assemblies

Gearbox instrumentation is often furnished by the manufacturer to accommodate condition monitoring of certain performance parameters in the field. The following performance parameters can be monitored by plant personnel in accordance with the guidance discussed in this section: •

Temperature

•

Oil pressure

•

Noise and/or vibration

•

Oil flow

Additionally, the condition monitoring of the lubricant furnished with the gearbox is critical to ensuring design performance. 3.2.13.1.1

Temperature Measurement

Temperature is an important indicator of the operation of any gear system. The actual point of measurement is determined by which performance characteristic the user is interested in monitoring. On a splash-lubricated unit, housing temperature is a common area of concern for trouble-free operation. In a pressure-lubricated system, inlet and outlet oil temperatures will give a good indication of both the lubrication system and gearbox health. In critical and high-speed applications, the ability to determine the actual operating temperatures of the individual bearings, in addition to the previously discussed monitoring, is beneficial in determining changes in component health and potential future failures. Thermometers – These are the simplest of all gearbox temperature monitoring devices. They are usually used to report oil temperature in the gearbox supply or drain lines. Thermometers are slow to respond to changes and require visual examination and human input to evaluate the operational health of the gearbox. Temperature switches – These are mechanical switches that open and close as temperatures reach predetermined set points. This device can be used to automatically activate alarms or shutdowns when equipment exceeds predetermined acceptance levels. Thermocouples – These simple and rugged instruments are highly reliable and produce a voltage output, which requires additional equipment to read. This signal can be used to read actual temperature at remote locations and activate alarms or shutdowns when equipment exceeds predetermined acceptance levels. A thermocouple consists of two dissimilar metals that produce a known voltage as the temperature varies. There are seven metal combinations used in the gear industry, and, therefore, the type of thermocouple should be known in order to determine the temperature. Table 3-22 lists these metal combinations.

3-45


Table 3-22 Types of Thermocouples Thermocouples Courtesy of Philadelphia Gear Corporation Thermocouple Type

Metal Combinations

T (most common)

Copper-constantan

J

Iron-constantan

E

ChromelTM-constantan

K

ChromelTM-alumelTM

B

Rhodium-platinum (30%)

R


S


The most common problems encountered with thermocouples arise from different metal combinations than those to which the reading equipment was set, and using extension wires that are not the same metal combinations as the thermocouple to which they are connected. Resistance temperature detectors – Resistance temperature detectors (RTDs) are devices that contain an electric circuit formed of solid conductors (usually a wire). The most common conductors are platinum, iron, and copper. The resistance varies with temperature and this resistance change can be used to determine the temperature at the tip of the sensor. This signal can be used to activate alarms or shutdowns when equipment exceeds predetermined acceptance levels. RTDs are not as rugged as thermocouples and care must be taken to ensure that the conductor is not damaged in operation due to handling or vibration. RTDs can be installed in the oil flow path to measure oil temperature, or they can be installed in fluid film bearings to read bearing babbitt temperature. Infrared thermography – Infrared thermography has gained favor in recent years in helping troubleshoot problem areas where high temperatures are present. The thermal picture indicates where excessive temperature is typically a problem. 3.2.13.1.2

Oil Pressure Measurement

Pressure is one of the most important indicators of the effectiveness of a pressure-lubricated system’s capability to meet its design function. Pressure is typically measured on a gearbox with either a pressure gauge or pressure switch. Pressure gauges – Pressure gauges are visual devices that display the pressure at a particular monitoring point. They are usually used to observe oil pressure in the gearbox lubrication system. Pressure gauges require both visual examination and human input to evaluate the operational health of the lubricant supply system.

3-46


Pressure switches – Pressure switches are mechanical devices that open and close as pressure reaches predetermined set points. These devices can be used to automatically activate alarms or shutdowns when equipment exceeds predetermined acceptance levels. 3.2.13.1.3

Noise/Vibration Measurement

Vibration measurement is an indication of the condition of the mechanical components of the gearbox. It is extremely useful in evaluating fitness for service for both new units and in predicting potential operating problems for installed equipment. Every mechanical system has a vibration signature. A change in a vibration signature over time is a useful PM tool, and, therefore, both the current signature and historical signature are often required to properly diagnose a problem. The key vibration characteristics that are useful in evaluating a gearbox’s health are the frequency of vibration and the magnitude of vibration. Magnitude is expressed as either movement (displacement), speed (velocity), or rate of acceleration. Proximity probes – Proximity probes are electrical devices that sense the distance from a metal body to the tip of the probe. This type of displacement measurement device is used to determine the movement of a shaft within the bearings and housing. To accomplish this, two probes at 90° apart are needed per shaft. Proximity probes are best used for detecting balance, instability, and misalignment problems and require a probe driver and accompanying readout. These are also particularly useful for lower frequency vibrations, such as shaft rotation frequencies. Velocity pickups – Velocity pickups are transducers that detect the velocity (speed) of a surface (usually a gear case) to which it is attached. Vibration is the physical movement of an object during operation. The movement is usually so small that it is not obvious with the naked eye, but a velocity pickup can detect the actual speed of the surface movement. Because it is often difficult to determine the optimum location for placement of the transducer, the velocity should be measured in all three directions (horizontal, vertical, and axial) in order to ensure that complete and accurate data are obtained. Velocity pickups are also capable of identifying moderately high frequencies, such as higher frequency structural resonance and lower tooth passing frequencies. Accelerometers – Accelerometers are similar to velocity transducers except that in the case of accelerometers, the transducers display the acceleration of the monitored surface (usually the gear case) as opposed to the velocity. They are also similar in that it is often difficult to determine the optimum location for placement of the accelerometer. And, as is the case with velocity transducers, care should be taken to measure acceleration in all three directions in order to ensure that complete and accurate data is obtained. This equipment is capable of identifying high frequencies, such as tooth passing frequencies.

3-47


Noise measurement – Abnormal noise can result from excessive vibration of the gearbox assembly or its internal sub-assemblies. Detecting the following types of abnormal sounds can be helpful in identifying problems that precede major failures of the gearbox components: •

Roughness (possibly indicating poor meshing of gear teeth)

•

Grinding of gear teeth (possibly indicating gear tooth failure)

•

Clashing (possibly indicating misalignment or poor meshing of gear teeth)

•

Whining (possibly indicating partial seizure, high friction, or partial loss of lubricant)

3.2.13.1.4

Oil Flow Measurement

Flow measurement is used to verify and monitor gearbox lubrication system operation. Gearbox lubrication systems depend on proper oil flow and distribution to perform. During gearbox testing, flow is measured to ensure that the oil being supplied to the drive is in agreement with the design requirements. After gear drive installation, a flow monitor should be used to identify changes in the lubrication system performance. The changes can be due to anything from a pump failing to a clogged filter or oil supply line. Visual flow monitors – Visual flow monitors are the most basic of flow-measuring devices. The most common of these devices is a simple sight window with a paddle, or a flow indicator with a dial gauge. Both devices indicate the presence or absence of oil flow. Visual flow monitors can be used on the supply-side or return-side oil lines. However, these devices are usually of very low accuracy and their response varies greatly with temperature and operating conditions. Some of these monitors can be supplied with a switch to allow remote notification of an abnormal occurrence. Flow sensors (flow meters) – Flow sensors and transducers are available in a wide range of sizes and accuracies. These devices generate an electric signal proportional to the flow passing through the device. These devices are usually not supplied with commercial equipment but are widely used in laboratories and testing facilities. These devices are significantly more expensive than the visual flow monitors usually supplied with gearboxes.

3.2.13.2


A complete PM program for a gearbox should include the elements shown in Figure 3-2. The figure illustrates how a combination of visual inspections, condition monitoring, regular lubricant analysis, and lubricant change all contribute to ensuring optimum performance of the equipment.

3-48


Figure 3-2 Elements of a Preventive Maintenance Program for Gearboxes [1]

Section 5 of this report discusses several maintenance activities that require gearbox disassembly and would be performed in most cases to address a known failure or degraded gearbox performance. 3.2.13.2.1

Maintenance of Gearbox Lubrication Systems Key Technical Point

The most important facet of a PM program for a gearbox is the regular regu lar inspection, analysis, and changing of the lubricant.

Table 3-23 illustrates that maintenance activities regarding the lubrication system are performed at various intervals, some of them on a daily basis.

3-49


Table 3-23 Preventive Maintenance Schedule Overview Courtesy of Lufkin, Inc. Frequency Daily

Preventive Maintenance Activities Check oil temperature. Check oil pressure. Check for vibration. Check for excessive noise. Check for oil leaks.

Monthly

Check operation of auxiliary equipment. Check operation of alarms. Check for oil contamination.

Quarterly

Analyze oil sample.

Annually

Check bearing clearance and end-play. Check tooth contact pattern. Visually inspect couplings and check alignment. Inspect tags and labels showing replacement part numbers. Inspect safety warning signs and caution labels.

Initial lubricant change period – The initial startup and operating oil of a new gear drive should be thoroughly drained after a period of 500 operating hours or four weeks, whichever occurs first. The importance of a thorough gear case cleaning with flushing oil to remove particle matter during the first lubricant change cannot be overemphasized. Consult the manufacturer if this is intended to be a fill-for-life application. Subsequent lubricant change interval – Under normal operating conditions, the lubricants should be changed every 2500 operating hours or six months, whichever occurs first. Extending the change period might be acceptable based on the type of lubricant, amount of lubricant, system downtime, or environmental consideration of the used lubricant. This can be done by proper implementation of a comprehensive monitoring program. Such a program can include examining for any of the following parameters: •

•

Lubricant viscosity – A rapid change in viscosity can be caused because gear oil is sheared as it lubricates the meshing gear teeth. This shearing eventually causes the oil to thin out and lose its film thickness. A rapid decrease could mean oxidation. A decrease of 10% is excessive. Lubricant oxidation (that is, total acid number) – Check if the total acid number increases by two. For example: new oil might have a total acid number of 0.4. When this number increases to 2.4 or above, the oil should be changed. This acid number increase is associated with oxidation of the oil, which results in oil breakdown.

3-50

Preventive Maintenance for Coal Handling System Components •

•

Water concentration – Water concentration should not exceed 0.1%. Water in oil causes the oil to lose its film strength and also will cause corrosion to gear elements and bearings. Contaminant concentration – Contaminant concentration limits are typically established based on plant-specific operating experience. For example, based on the experience at one site, the oil is considered dirty if the silicon content is above 50 parts per million (ppm). Similarly, contaminant concentration of iron content above 200 ppm is considered unacceptable. Key Technical Point

Trending contaminant concentrations is important because it provides an indication of significant increases over time. In some cases, an increase of only 10 ppm of iron is significant because iron contamination indicates contamination from gear wear particles. •

Percentage sediment and sludge.

•

Additive depletion.

•

Change in appearance and odor.

An alternative method of establishing change-out periods that is gaining acceptance is to change oil only when change is needed based on tests. This means reliance on leading indicators of change, such as additive depletion and contaminant concentration. When following indicators, such as viscosity and oxidation, are used, and significant change is observed, it is already too late to save the oil. New lubricant specification should be used to establish a baseline for comparison. Follow unit manufacturer’s and lubricant supplier’s recommendations for appropriate subsequent testing intervals. Cleaning and flushing – When the gear drive reaches normal operating temperature, lubricant should be drained immediately after shutdown. The drive should be cleaned with a flushing oil. Flushing oil must be clean and compatible with the operating oil. Oils specially blended for flushing or clean operating oil are commonly used for flushing. •

•

Cleaning with solvents – The use of a solvent should be avoided unless the gear drive contains deposits of oxidized or contaminated lubricant that cannot be removed with a flushing oil. When persistent deposits necessitate the use of a solvent, a flushing oil should then be used to remove all traces of solvent from the system. Caution: when solvents are used, consult the unit manufacturer to verify compatibility with paint, seals, sealant, and other components. Used lubricants – Used lubricant and flushing oils should be completely removed from the system to avoid contaminating the new charge, and properly disposed. Caution: care must be exercised to not mix lubricants of different additive chemistry.

3-51


Protective coatings – For gearing that might be subjected to extended shipment or storage periods, consideration should be given to applying a protective coating formulated to prevent rusting. These coatings must be compatible with the lubricant to be used in service and all other components. Caution: some lubricants might foam due to reaction with rust preventatives. If necessary, flush out residues from the unit. Filtration – Gear drives with pressurized oil systems should have a filter on the pressure side of the system to remove contamination particles. As a guideline, in the absence of specific manufacturer’s recommendations, the filter should be no coarser than 50 μ m (microns) absolute for gear drives with ball or roller bearings, and 25 mm absolute for gear drives with journal bearings. In addition, a screen can be used on the suction side to protect the pump. This should be in combination with a filter and must have a coarse mesh to avoid flow restriction. Caution: lubricants should not be filtered through fuller’s earth or other types of filters that could remove the additives of the original formulation. Gear tooth wear – There are numerous modes of damage associated with gear teeth. Therefore, proper selection, application, and maintenance of lubricants are essential to avoiding premature wear. If premature wear occurs, lubricant selection should be reviewed. As a guide, if rapid increases of any of the following materials are detected, the probable origins of that material are listed: •

Alloy steel: gear teeth and bearings

•

Mild steel: oil pump, slinger, or baffle-rubbing gear case

•

Cast iron: oil pump

•

Aluminum: oil seal, seal guards, or carriers

•

Babbitt: journal bearings

3.2.13.2.2

Preventive Maintenance for Gearbox Couplings

In many cases, the coupling gets neglected during corrective maintenance activities on the adjoining machines. Once the coupling and all of its parts are removed, its component parts can be placed in appropriate packaging (bag or box), and set in a corner somewhere until the machine(s) are reassembled. The coupling can then be taken out of temporary storage, possibly cleaned without much observation to the condition, and reinstalled. To ensure optimum performance and reliability, the coupling should be checked thoroughly during maintenance activities. Placing a worn or damaged coupling back in service not only leaves one open for operational problems, but machine problems, and the potential for catastrophic damage or personal injury. Comprehensive guidance regarding PM activities for flexible shaft couplings is provided in the EPRI report Flexible Shaft Couplings Maintenance Guide [2]. 3-52


3.2.13.2.3

Protecting Gearboxes from Moisture

In some cases, gearboxes operate in a humid, moist environment. The following common-sense approach can effectively protect gearbox internals from excessive moisture and subsequent corrosion. •

•

•

Educate maintenance staff to avoid direct jetting of water at ingression points, such as shaft seals, breathers, and so on. If water spray is inevitable, use passive shields and deflectors to avoid direct water spray on shafts, dipsticks, fill-caps, breathers, and so on. Use high-performance seals that suffer less wear and offer better protection against contaminants.

•

Regularly inspect and maintain gaskets on fill-caps, hatches, and so on.

•

Replace dipsticks with level indicators.

•

Keep hatches closed tight.

•

Replace basic vent breather with a desiccant breather, which dehydrates incoming air, or an expansion chamber, which allows the system to breathe without ingesting external air.


3.2.14.1

Lubricated Couplings (Grid and Gear Types)

The following activities are recommended as general PM measures to identify premature failure or accelerated degradation: •

Visually inspect for wear, corrosion, cracking, or leakage of lubricant.

•

Verify that proper lubricant is being used.

•

Perform stroboscopic inspection while operating.

•

Disassemble clean and replace lubricant; after greasing, ensure that coupling is not bound.

•

Perform infrared thermography.

•

Perform a precision shaft alignment after each lubrication.

•

Inspect gaskets and O-rings for elasticity.

A number of manufacturers specify PM and lubrication schedules based on six months of operation. Due to the long fuel cycles in most plants, this is not always feasible. The coupling manufacturer should be consulted concerning length of operation without lubrication inspections. As a minimum, lubricated couplings should be inspected during each major outage.

3-53


3.2.14.2

Metallic Element Nonlubricated Couplings (Elastomeric, Disk, and Diaphragm)

The following activities are recommended as general PM measures to identify premature failure or accelerated degradation: •

Visually inspect for wear, corrosion, or cracking while the machine is idle.

•

Disassemble, clean, and replace flex element as required.

•

Perform a precision shaft alignment after each coupling inspection.

As a minimum, nonlubricated couplings should be inspected each time the machine is scheduled for routine refurbishment or inspection (or every three years, whichever is less). Additional details on what to look for during inspections of the couplings are provided in Sections 4 and 5 of the EPRI report Flexible Shaft Couplings Maintenance Guide [2].

3-54

4

PREVENTIVE MAINTENANCE BASIS

The purpose of this section is to establish a PM Basis document for the various components typically installed in a coal handling system.

4.1

Background

Many power plants are in the process of reducing PM costs and improving equipment performance by matching PM tasks with the functional importance of the equipment. For this to succeed, utilities require information on the most appropriate tasks and task intervals for the important equipment types, while accounting for the influences of functional importance, duty cycle, and service conditions. An early approach to optimizing PM activities was the use of reliability-centered maintenance (RCM). RCM was developed in the 1960s by the commercial airline industry to apply reliability concepts to maintenance and the design of maintenance programs. The RCM approach to preventing equipment failure is to perform maintenance tasks that are specifically aimed at preventing component failure mechanisms from occurring. Many nuclear power plants used the RCM process to improve their PM programs. In 1991, the Nuclear Regulatory Commission issued 10CFR50.65, “Requirements for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants,” also called the Maintenance Rule. In brief, the Maintenance Rule required nuclear power plants to develop a reliability and availability monitoring program for the systems, structures, and components considered to be within the scope of the rule. The monitoring part of the rule included determining the effectiveness of the maintenance performed on the components. In addition, the Maintenance Rule required the utility to evaluate industry operating experience and to use that experience when modifying the maintenance program. When maintenance practices have been changed, the most common action is to modify the PM tasks for the components. Initially, PM tasks were assigned based on vendor recommendations and plant experience. In modifying or optimizing the PM tasks, one vital piece of information was missing—the time to failure for the components. Because the time to failure was not known, it was difficult to justify the PM task intervals. Also missing was the understanding of the factors that influence the progression of the degradation mechanisms for the component.

4-1

Preventive Maintenance Basis

As a result of the need to comply with the Maintenance Rule and to optimize the PM tasks for more effective maintenance, the PM Basis project was proposed by EPRI. The PM Basis objectives were the following: •

•

To provide a summary of industry experience that the PM tasks and task intervals were based on To establish the relationship between the degradation mechanisms, the progression of the mechanisms to failure, and the opportunities available to discover the failure mechanisms before component failure occurred

During the 1996–1998 timeframe, 39 PM Basis documents were developed for major components in the nuclear power plants. The components included various style valves, switchgear, motor control centers, motors, pumps, compressors, HVAC (heating, ventilation, and air conditioning) components, inverters, batteries, relays, heat exchangers, turbines, transformers, and I&C (instrumentation and control) components. The PM Basis documents can be found in the EPRI report Preventive Maintenance Basis Volumes 1–38 (TR-106857). Currently, there are over 73 component types in an electronic PM database. The database can be accessed by logging onto and searching for PMBD: Preventive Maintenance Basis Database, Version 5.1.1 (PMBDv5.1.1) (EPRI report 1010919). The product can be downloaded from www.epri.com; however, it is best to order the CD from the EPRI Customer Assistance Center at 1-800-313-3774. Although fossil power plants do not have the same regulatory requirements as nuclear power plants, the establishment of the PM Basis for critical components provides valuable information for optimizing maintenance programs. The next step in the development of this PM Basis document is an additional review with plant personnel. The PM tasks are further analyzed for criticality, condition monitoring options, and other parameters before being added to the EPRI PM database. The information used in the development of the PM Basis was gathered from the manufacturer, industry literature, and input from utility maintenance personnel. The following is a description of the tables generated by the PM Basis document.

4.2

Failure Locations, Degradation Mechanisms, Mechanisms, and PM Strategies

Table 4-1 contains the following fields of information: •

•

4-2

Failure locations – A list of the most common components. Degradation mechanisms – The cause of the component failing at the specified failure location.


•

•

•

•

•

Degradation influence – Aspects of the environment, plant operations, maintenance, or design that cause the initiation of degradation processes or can affect how rapidly the degradation progresses. Degradation progression – Whether the degradation progress is present most of the time (continuous) or whether it would not normally be present but might exist or initiate in a haphazard (random) way. Failure timing – The relevant time period that the component would be free from failure. Discovery opportunity – Reasonable, cost-effective opportunities for detecting the failure mechanism. PM strategy – The choice of PM tasks where the discovery of the failure mechanism can occur.

4-3


Table 4-1 Failure Locations, Degradation Mechanisms, Mechanisms, and PM Strategies for Coal Handling System Components Failure Location Scales

Unloading Equipment – Rotary Railcar Dumper

4-4

Degradation Mechanism Out of calibration range

Fails to operate properly

Degradation Influence

Degradation Progression

Failure Timing

Discovery Opportunity

PM Strategy

Scale area full of rocks, dust, and material buildup

Random

Random

Cleaning, Visual Inspection

Cleaning, Visual Inspection

Idlers rolls worn

Continuous

Continuous

Visual Inspection

Visual Inspection

Belt not running true to the centerline of the idlers

Continuous

Continuous

Visual Inspection

Visual Inspection

Changing belt tension (for belts not equipped with gravity-type takeups)

Continuous

Continuous

Visual Inspection

Visual Inspection

Overloading belts

Random

Random

Calibration

Calibration

Film Buildup on Belt

Random

Random

Visual Inspection

Visual Inspection

Skirt Boards and Covers too close to the weigh idlers

Random

Random

Visual Inspection

Visual Inspection

Platen is out of alignment

Random

Random

Visual Inspection

Visual Inspection

Clamp brake is out of adjustment

Random

Random

Visual Inspection

Visual Inspection

Car clamps are binding

Random

Random

Visual Inspection

Visual Inspection


Table 4-1 (continued) (continued) Failure Locations, Degradation Mechanisms, Mechanisms, and PM Strategies for Coal Handling System Components Failure Location Unloading Equipment – Rotary Railcar Dumper (cont.)

Unloading Equipment – Traveling Hammermill

Degradation Mechanism Fails to operate properly

Not functioning properly



Failure Timing


PM Strategy

Limit switches out of adjustment

Continuous

Continuous

Calibration

Calibration

Speed reducer is malfunctioning

Random

Random

Lubrication

Lubrication

Loose bolts on end ring rails and wheels

Random

Random

Visual Inspection

Visual Inspection

Drive brakes are out of adjustment

Random

Random

Visual Inspection

Visual Inspection

Car spotter sensors out of adjustment

Random

Random

Calibration

Calibration

Dumper rotating drive and car clamp chains malfunctioning

Random

Random

Visual Inspection,

Visual Inspection,

Lubrication

Lubrication

Speed reducer not working

Random

Visual Inspection, Lubrication

Visual Inspection,

Rotor drive chains and sprockets worn

Continuous

Continuous

Visual Inspection

Visual Inspection

Hammer and Tbolts worn

Continuous

Continuous

Visual Inspection

Visual Inspection

Traverse chains worn

Continuous

Continuous



Random

Lubrication

4-5


Table 4-1 (continued) (continued) Failure Locations, Degradation Mechanisms, Mechanisms, and PM Strategies for Coal Handling System Components Failure Location Unloading Equipment – Traveling Hammermill (cont.)

Unloading Equipment – Stationary Barge Unloader

4-6

Degradation Mechanism Not functioning properly




Failure Timing


PM Strategy

Bearings failed lack of lubrication

Continuous

Continuous




Random

Random


Visual Inspection,

Loose bolts

Continuous

Continuous

Visual Inspection

Visual Inspection

Couplings binding

Continuous

Continuous

Lubrication

Lubrication

Trolley runway rails out of alignment

Continuous

Continuous

Visual Inspection

Visual Inspection

Structural joints and sheave supports deteriorated

Continuous

Continuous

Visual Inspection

Visual Inspection


Random

Random


Visual Inspection,

Bearings failing

Continuous

Continuous



Ropes, drums, sheaves, and rails worn

Continuous

Continuous



Hold-and-close engine not working

Random

Random



Lubrication

Lubrication


Table 4-1 (continued) (continued) Failure Locations, Degradation Mechanisms, Mechanisms, and PM Strategies for Coal Handling System Components Failure Location Unloading Equipment – Bucket Barge Unloader

Degradation Mechanism Not functioning properly



Failure Timing


PM Strategy

Sheave and drum scored

Continuous

Continuous

Visual Inspection

Visual Inspection

Bearings failing

Continuous

Continuous




Random

Random


Visual Inspection,

Loose bolts

Continuous

Continuous

Visual Inspection

Visual Inspection

Couplings binding

Continuous

Continuous

Lubrication

Lubrication

Trolley rails and wheels loose, worn, or cracked

Continuous

Continuous

Visual Inspection

Visual Inspection

Trolley travel ropes slack

Continuous

Continuous

Visual Inspection

Visual Inspection

Trolley thrust rollers excessive play

Continuous

Continuous

Visual Inspection

Visual Inspection

Barge haul ropes damaged

Continuous

Continuous

Visual Inspection

Visual Inspection

Hoists not working

Continuous

Continuous

Visual Inspection

Visual Inspection

Lubrication

4-7


Table 4-1 (continued) (continued) Failure Locations, Degradation Mechanisms, Mechanisms, and PM Strategies for Coal Handling System Components Failure Location

Degradation Mechanism

Unloading Equipment – Train Positioner


4-8



Failure Timing


PM Strategy

Hydraulic system not functioning

Random

Random

Visual Inspection

Visual Inspection

Positioner overtravel and reference limit switches out range

Continuous

Continuous

Calibration

Calibration

Resolver and speed increaser out of alignment

Continuous

Continuous

Calibration

Calibration

Arm positioner sensing element not working

Continuous

Continuous

Calibration

Calibration

Positioner wheel chocks malfunctioning

Continuous

Continuous

Visual Inspection

Visual Inspection

Positioner ropes are slack

Continuous

Continuous

Visual Inspection

Visual Inspection

Positioner rope roller supports not working

Continuous

Continuous

Visual Inspection

Visual Inspection

Bearings failing

Continuous

Continuous




Random

Random






Unloading Equipment – Train Positioner (cont.)


Unloading Hoppers

Sampling Equipment



Failure Timing


PM Strategy

Loose bolts

Continuous

Continuous

Visual Inspection

Visual Inspection

Couplings binding

Continuous

Continuous

Lubrication

Lubrication

Gear guards binding

Continuous

Continuous

Lubrication

Lubrication

Wire rope worn

Continuous

Continuous




Continuous

Continuous

Visual Inspection

Visual Inspection

Holes in hoppers and/or hopper liner

Corrosion, wear, cracks

Continuous

Continuous

Visual Inspection

Visual Inspection

Hopper structure failed

Corrosion, wear, cracks

Continuous

Continuous

Visual Inspection

Visual Inspection

Primary sampling machine not working

Plugged chutes

Random

Random

Visual Inspection

Visual Inspection

Plugged chute sensors not working

Out of calibration

Random

Random

Calibration

Calibration

Primary or secondary sampling machine failure

Insufficient oil level in gearbox

Random

Random

Operator Checks

Operator Checks

4-9




Sampling Equipment (cont.)

Sweep sampler not working

Crushers

Grandulators not working

Hammermills not working

4-10



Failure Timing


PM Strategy

Magnetic limit switch and target out of adjustment

Random

Random

Calibration

Calibration

Brake out of adjustment

Random

Random

Calibration

Calibration

Pillow block bearings seized

Random

Random

Lubrication

Lubrication

Worn hammers and suspension bars

Continuous

Continuous

Visual Inspection

Visual Inspection

Failed bearings from lack of lubrication

Random

Random

Lubrication

Lubrication

Tramp iron trap not working

Continuous

Continuous

Visual Inspection

Visual Inspection

Worn hammers, suspension bars, and cotter pins

Continuous

Continuous

Visual Inspection

Visual Inspection


Random

Random

Lubrication

Lubrication




Reclaim Hoppers

Vibratory Drawdown Reclaim Hopper not working

Discharge Hopper Feeders



Failure Timing


PM Strategy

Failed motor or drive shaft bearings from lack of lubrication

Random

Random

Lubrication

Lubrication

Shaft mounted eccentric weight corroded, cracked, or bent

Continuous

Continuous

Visual Inspection

Visual Inspection

Torn or damaged V-belt

Continuous

Continuous

Visual Inspection

Visual Inspection

Damaged pulleys

Continuous

Continuous

Visual Inspection

Visual Inspection

Motor not working

Bearings failed from lack of lubrication

Random

Random

Lubrication

Lubrication

Stroke plate not working

Stroke out of calibration

Random

Random

Calibration

Calibration

Rotary joints binding

Lack of lubrication

Random

Random

Lubrication

Lubrication

Clogged air line filter

Filter not cleaned

Random

Random

Visual Inspection

Visual Inspection

4-11


Table 4-1 (continued) (continued) Failure Locations, Degradation Mechanisms, Mechanisms, and PM Strategies for Coal Handling System Components Failure Location Magnetic Separator

Slide Gates

4-12




Failure Timing


PM Strategy

Magnet gearmotor not working


Random

Random

Lubrication

Lubrication

Self-cleaning belt not working

Worn belt

Random

Random

Visual Inspection

Visual Inspection

Belt not tracking

Belt out-ofalignment

Random

Random

Visual Inspection

Visual Inspection

Pulley/shaft assembly not working

Hubs are not tightened properly

Random

Random

Visual Inspection

Visual Inspection

Zero-speed switch not working

Switch out of calibration

Random

Random

Calibration

Calibration

Rectifier not working

Dust and debris clogging rectifier

Random

Random

Visual Inspection

Visual Inspection

Fasteners limiting gate movement


Random

Random

Lubrication

Lubrication

Conduit and terminal connections not working

Loose fasteners

Random

Random

Visual Inspection

Visual Inspection

Leaking seals

Loose electrical connections

Random

Random

Visual Inspection

Visual Inspection


Table 4-1 (continued) (continued) Failure Locations, Degradation Mechanisms, Mechanisms, and PM Strategies for Coal Handling System Components Failure Location Dust Control System




Failure Timing


PM Strategy

Not functioning properly – Excessive pressure drop

Timer, solenoid/ diaphragm valves, timer, blower, manifold, fans, hopper (and so on) not working correctly

Random

Random

Calibration

Calibration

Not functioning properly – Low pressure drop

Clogged pressure lines

Random

Random

Visual Inspection

Visual Inspection

Belt not tracking

Bags are worn, excessively clean, improperly installed

Random

Random

Visual Inspection

Visual Inspection

Excessive dusting

Bags are worn, excessively clean, improperly installed

Random

Random

Visual Inspection

Visual Inspection

Check operating temperature, pH, moisture, physical constraints

Random

Random

Visual Inspection

Visual Inspection

Obstruction, air leaks, speed too slow

Random

Random

Visual Inspection

Visual Inspection

Premature bag failure Fan not working

4-13


Table 4-1 (continued) (continued) Failure Locations, Degradation Mechanisms, Mechanisms, and PM Strategies for Coal Handling System Components Failure Location Dust Control System (cont.)

Conveyor Belts, Pulleys, Idlers, and Rollers

4-14

Degradation Mechanism Motor not working



Failure Timing


PM Strategy

Bearing failure

Random

Random

Lubrication

Lubrication

Tripper rails out of alignment

Random

Random

Visual Inspection

Visual Inspection

Tripper frame out of alignment

Random

Random

Visual Inspection

Visual Inspection

Axles out of alignment

Random

Random

Visual Inspection

Visual Inspection

Conveyor belts not holding coal

Corrosion

Random

Random

Calibration

Calibration

Loose conveyor belts

Torn/damaged belting

Random

Random

Visual Inspection

Visual Inspection

Belt not tracking

Takeup pulley not functioning

Random

Random

Visual Inspection

Visual Inspection

Idlers/rollers not functioning

Out of adjustment

Random

Random

Calibration

Calibration

Worn idlers/rollers

Continuous

Continuous

Visual Inspection

Visual Inspection

Failed tail pulley

Random

Random

Visual Inspection

Visual Inspection


Table 4-1 (continued) (continued) Failure Locations, Degradation Mechanisms, Mechanisms, and PM Strategies for Coal Handling System Components Failure Location Movable Tripper Devices




Failure Timing


PM Strategy

Motor driven/cablepropelled belt tripper not working

Lack of lubrication

Random

Random

Lubrication

Lubrication

Pulley shafts out of alignment

Random

Random

Visual Inspection

Visual Inspection

Belt scraper or brush worn

Continuous

Continuous

Visual Inspection

Visual Inspection

Worm gear speed reducer lack of lubrication

Random

Random

Lubrication

Lubrication

Motor and roller bearings lack of lubrication

Random

Random

Lubrication

Lubrication

Propelling cable out of adjustment

Continuous

Continuous

Visual Inspection

Visual Inspection

Tripper lack of lubrication

Random

Random

Lubrication

Lubrication

Cable supporting rollers lack of lubrication

Random

Random

Lubrication

Lubrication

4-15


Table 4-1 (continued) (continued) Failure Locations, Degradation Mechanisms, Mechanisms, and PM Strategies for Coal Handling System Components Failure Location Gearboxes

Flexible Shaft Couplings

Degradation Mechanism Gearbox not functioning

Fatigue

Wear

Seizure

4-16



Failure Timing


PM Strategy

Lack of lubrication

Random

Random

Lubrication

Lubrication

Lubricant contamination

Random

Random

Oil Analysis

Oil Analysis

High vibration

Random

Random

Vibration Analysis

Vibration Analysis

Coupling failure

Random

Random

Vibration Analysis

Vibration Analysis

Worn gears

Continuous

Continuous

Vibration Analysis, Oil Analysis

Vibration Analysis, Oil Analysis

Misalignment, Imbalance of coupling or rotor shafts

Random

Random

Vibration

Vibration Analysis,

Noise

Operator Checks

Broken teeth, sheared key, broken bolts

Random

Vibration

Vibration Analysis,

Noise

Operator Checks

Overheating

Random

Random

Temperature check

Operator Check

Inadequate/impro per lubrication

Continuous

Continuous

Lubrication

Lubrication

Noise

Operator Checks

Improper tolerances

Continuous

Visual Inspection

Visual Inspection

Random

Continuous


4.3

PM Tasks and Their Degradation Mechanisms

Table 4-2 contains the PM tasks and intervals for the various components of a coal handing system. The PM tasks and the degradation mechanisms are listed from the previous table. The corresponding PM task interval is then given for each applicable PM task.

4-17


Table 4-2 PM Tasks and Their Degradation Mechanisms for Coal Handling System Components Component

Scales

Location/Degradation Calibration

Cleaning

Lubrication

Oil Analysis

Operator Checks

Vibration Analysis

Visual Inspection

DailyWeeklyMonthly

Weekly

Monthly-3 Months-6 Months

Monthly – 3 Months

DailyWeeklyMonthly

Monthly-3 Months

DailyWeeklyMonthly

Scale area full of rocks, dust, and material buildup

X

X

Idlers rolls worn

X

Belt not running true to the centerline of the idlers

X

Changing belt tension (for belts not equipped with gravity type takeups)

X

Overloading belts

4-18

PM Task and Interval

X

Film Buildup on Belt

X

Skirt Boards and Covers too close to the weigh idlers

X


Table 4-2 (continued) (continued) PM Tasks and Their Degradation Mechanisms for Coal Handling System Components Component

Unloading Equipment – Rotary Railcar Dumper

Location/Degradation

PM Task and Interval Calibration

Cleaning

Lubrication

Oil Analysis

Operator Checks

Vibration Analysis

Visual Inspection

DailyWeeklyMonthly

Weekly



DailyWeeklyMonthly

Monthly-3 Months

DailyWeeklyMonthly

Platen is out of alignment

X

Clamp brake is out of adjustment

X

Car clamps are binding

X

Limit switches out of adjustment

X

Speed reducer is malfunctioning

X

Loose bolts on end ring rails and wheels

X

Drive brakes are out of adjustment

X

Car spotter sensors out of adjustment

X

Dumper rotating drive and car clamp chains malfunctioning

X

X


X

X

4-19



Unloading Equipment – Traveling Hammermill



Cleaning

Lubrication

Oil Analysis

Operator Checks

Vibration Analysis

Visual Inspection

DailyWeeklyMonthly

Weekly



DailyWeeklyMonthly

Monthly-3 Months

DailyWeeklyMonthly

Rotor drive chains and sprockets worn

X

Hammer and T-bolts worn

X

Traverse chains worn

X

X

Bearings failed lack of lubrication

X

X


X

X

Loose bolts Couplings binding Unloading Equipment – Stationary Barge Unloader

4-20

X X

Trolley runway rails out of alignment

X

Structural joints and sheave supports deteriorated

X


X

X

Bearings failing

X

X



Unloading Equipment – Bucket Barge Unloader



Cleaning

Lubrication

Oil Analysis

Operator Checks

Vibration Analysis

Visual Inspection

DailyWeeklyMonthly

Weekly



DailyWeeklyMonthly

Monthly-3 Months

DailyWeeklyMonthly

Ropes, drums, sheaves, and rails worn

X

X

Hold-and-close engine not working

X

X


X

Bearings failing

X

X


X

X

Loose bolts Couplings binding

X X

Trolley rails and wheels loose, worn, or cracked

X

Trolley travel ropes slack

X

Trolley thrust rollers excessive play

X

Barge haul ropes damaged

X

Hoists not working

X

4-21



Unloading Equipment – Train Positioner

Location/Degradation Calibration

Cleaning

Lubrication

Oil Analysis

Operator Checks

Vibration Analysis

Visual Inspection

DailyWeeklyMonthly

Weekly



DailyWeeklyMonthly

Monthly-3 Months

DailyWeeklyMonthly X

Hydraulic system not functioning Positioner overtravel and reference limit switches out range

X

Resolver and speed increaser out of alignment

X

Arm positioner sensing element not working

X

Positioner wheel chocks malfunctioning

X

Positioner ropes are slack

X

Positioner rope roller supports not working

X

Bearings failing

X

X


X

X

Loose bolts

4-22


X



Unloading Equipment – Train Positioner (cont.)

Unloading Hoppers

Sampling Equipment



Cleaning

Lubrication

Oil Analysis

Operator Checks

Vibration Analysis

Visual Inspection

DailyWeeklyMonthly

Weekly



DailyWeeklyMonthly

Monthly-3 Months

DailyWeeklyMonthly

Couplings binding

X

Gear guards binding

X

Wire rope worn

X

X


X

Holes in hoppers and/or hopper liner

X

Hopper structure failed

X

Primary sampling machine not working

X

Sample cutters not working

X

Out of calibration

X X

Insufficient oil level in gearbox Magnetic limit switch and target out of adjustment

X

Brake out of adjustment

X

4-23




Sampling Equipment (cont.)

Pillow block bearings seized

Crushers

Worn hammers and suspension bars Failed bearings from lack of lubrication

Reclaim Hoppers

Calibration

Cleaning

Lubrication

Oil Analysis

Operator Checks

Vibration Analysis

Visual Inspection

DailyWeeklyMonthly

Weekly



DailyWeeklyMonthly

Monthly-3 Months

DailyWeeklyMonthly

X

X X

Tramp iron trap not working

X

Worn hammers, suspension bars, and cotter pins

X


X

Failed motor or drive shaft bearings from lack of lubrication

X

Shaft mounted eccentric weight corroded, cracked, or bent

4-24


X



Reclaim Hoppers (cont.) Discharge Hopper Feeders



Cleaning

Lubrication

Oil Analysis

Operator Checks

Vibration Analysis

Visual Inspection

DailyWeeklyMonthly

Weekly



DailyWeeklyMonthly

Monthly-3 Months

DailyWeeklyMonthly

Torn or damaged V-belt

X

Damaged pulleys

X X

Bearings failed from lack of lubrication Stroke out of calibration

X

Rotary joints binding

X

Clogged air line filter Magnetic Separator

X X

Bearings failed from lack of lubrication Worn belt

X

Belt out-of-alignment

X

Hubs are not tightened properly

X

Switch out of calibration

X

Dust and debris clogging rectifier Bearings failed from lack of lubrication

X X

4-25



Slide Gates

Dust Control Systems



Cleaning

Lubrication

Oil Analysis

Operator Checks

Vibration Analysis

Visual Inspection

DailyWeeklyMonthly

Weekly



DailyWeeklyMonthly

Monthly-3 Months

DailyWeeklyMonthly

Conduit and terminal connections not working

X

Leaking seals

X

Excessive pressure drop

X

Low pressure drop

X

Excessive dusting

X

Premature bag failure

X

Fan not working

X

Motor not working Conveyor Belts, Pulleys, Idlers, and Rollers

Conveyor belts not holding coal

X

Loose conveyor belts

X

Belt not tracking

X

Out of adjustment Failed tail pulley

4-26

X

X X



Movable Tripper Devices


Lack of lubrication


Cleaning

Lubrication

Oil Analysis

Operator Checks

Vibration Analysis

Visual Inspection

DailyWeeklyMonthly

Weekly



DailyWeeklyMonthly

Monthly-3 Months

DailyWeeklyMonthly

X

Tripper rails out of alignment

X

Tripper frame out of alignment

X

Axles out of alignment

X

Pulley shafts out of alignment

X

Belt scraper or brush worn

X

Worm gear speed reducer lack of lubrication

X

Motor and roller bearings lack of lubrication

X

Propelling cable out of adjustment

X

4-27



Movable Tripper Devices (cont.) Gearboxes



Cleaning

Lubrication

Oil Analysis

Operator Checks

Vibration Analysis

Visual Inspection

DailyWeeklyMonthly

Weekly



DailyWeeklyMonthly

Monthly-3 Months

DailyWeeklyMonthly

Tripper lack of lubrication

X

Cable supporting rollers lack of lubrication

X

Lack of lubrication

X

Lubricant contamination

X

High vibration

X

Coupling failure

X

Worn gears Flexible Shaft Couplings

Fatigue Wear Seizure

4-28

X

X X

X

X

X X


4.4

Preventive Maintenance Template

The PM template in Table 4-3 summarizes the program of tasks and task intervals for the equipment type. Each plant should base its program on the manufacturers’ recommendations and its own history of equipment performance. The PM template can serve as a beginning for development of a PM program for the equipment, and changes can be made as a result of feedback received during implementation of the program. The PM template contains the following information: •

Conditions. Columns 1 through 8 list the 8 sets of conditions for the Coal Handling system components. Each column corresponds to the combined choices of critical or non-critical equipment, high or low duty cycle, and severe or mild service conditions. Time intervals for the performance of each task are entered at the intersections of the task rows and columns 1 through 8.

The definitions of template application conditions are the following: •

Critical

Yes. Functionally important; that is, risk significant, required for power production, safety related, or other regulatory requirement. No. Functionally not important, but economically important for any of the following reasons: high frequency of resulting corrective maintenance, more expensive to replace or repair than to do PM, high potential to cause the failure of other critical or economically important equipment. •

Duty Cycle

High. Frequently cycled or partially loaded during the greater part of its operational time. Low. Fully loaded during the greater part of its operation time. •

Service Condition

Severe. High or excessive humidity, excessively high or low temperatures, excessive temperature variations, excessive environmental conditions (such as salt, corrosive, spray, steam, or low-quality suction air), high vibration. Mild. Clean area (not necessarily air-conditioned), temperatures within OEM specifications, normal environmental conditions. •

PM Tasks. The PM tasks provide a cost-effective way to intercept the causes and mechanisms that lead to degradation and failure. The PM tasks can be used to develop a complete PM program or to improve an existing program. These tasks are intended to complement and not to replace the PM recommendations given by the manufacturer. A brief description of the PM tasks follows the PM Template. 4-29


Table 4-3 PM Template for Coal Handling System Components Conditions Conditions Critical:

Yes

1

2

3

4

X

X

X

X

No Duty Cycle: High

X X

Low Service Condition: Condition:

Severe

X

X

6

7

8

X

X

X

X

X X

X

PM Tasks:

X X

X X

Mild

5

X

X

X

X

X

Frequency Interval

Calibration

Daily

Weekly

Weekly

Weekly

Monthly

Monthly

Monthly

Monthly

Cleaning

Daily

Weekly

Weekly

Weekly

Monthly

Monthly

Monthly

Monthly

Lubrication

Monthly

3 Months

3 Months

3 Months

6 Months

6 Months

6 Months

6 Months

Oil Analysis

Monthly

Monthly

Monthly

Monthly

3 Months

3 Months

3 Months

3 Months

Operator Checks

Daily

Weekly

Weekly

Weekly

Monthly

Monthly

Monthly

Monthly

Vibration Analysis

Monthly

Monthly

Monthly

Monthly

3 Months

3 Months

3 Months

3 Months

Visual Inspection

Daily

Weekly

Weekly

Weekly

Monthly

Monthly

Monthly

Monthly

4-30


4.5

Description of Preventive Maintenance Tasks

The following is a brief description of PM tasks used in the PM Template. •

•

•

•

•

•

•

Calibration – Calibration of the coal handling equipment includes the setting and verification of instruments and components. Instruments include thermocouples, resistance temperature detectors (RTDs), pitot tubes, and pressure gauges. Some examples of calibration are for the scales, the zero load reference should be checked every other day and the calibration be checked every week for several months after installation. Simulated load tests or material tests, and zero load tests should be conducted at periodic intervals between official tests in order to provide reasonable assurance that the device is performing correctly. The limit switches on the rotary railcar dumpers should be checked weekly and the car spotter sensors monthly. Cleaning – The cleaning of equipment and components is very important in the coal handling system. The appearance of black dust on all equipment limits the operations and maintenance personnel from seeing the movement, position, or location of many components. The accumulation of coal dust can clog filters, jam rollers, interfere with limit switch operation, and so on. Whenever coal is unloaded or moved, the entrainment of coal dust in the air and onto equipment occurs. Persistent cleaning will allow the components to function as intended. Lubrication – The addition and changing of lubrication is a very critical function for the coal handling system components. The coal dust can contaminate lubrication and destroy bearings. The frequency of lubrication and changing lubrication varies with the equipment Oil analysis – Oil analysis is valuable predictive maintenance technology for detecting problems in equipment before failure occurs. For the coal handling equipment, oil samples should be taken and analyzed for the gearboxes and any other rotating equipment. Samples should be analyzed for contamination and oil properties. The results of the oil analysis can alert personnel that bearings are failing, and plans can be made to monitor the operation of the equipment, take more frequent samples, or shut the equipment down. Operations check – Operations check includes an external visual inspection of the coal handling equipment. This includes listening for noises, smelling for smoke, checking temperatures, checking pressures, looking for leaks, checking oil levels, and so on. Vibration analysis – Monitoring of the coal handling with vibration sensors and performing vibration data analysis prevents component forced outages. When abnormal vibration is detected, then further investigation is warranted. Detection of failing bearings can allow the component to be repaired before it fails. Visual inspection – The single most important PM task is visual inspection. The operations or maintenance personnel should be looking for any abnormal activity, missing bolts, failed welds, excessive corrosion, physical deformation, and so on.

4-31

5

REPAIR AND REPLACEMENT FOR COAL HANDLING SYSTEM COMPONENTS

5.1

General Guidance

Figure 5-1 illustrates a generic process for determining whether to repair or replace a system component that is no longer performing in accordance with design requirements.

5-1

Repair and Replacement Replacement for Coal Handling System Components

Figure 5-1 Generic Repair vs. Replace Evaluation [18]

The question of whether to repair, replace, or defer maintenance on a system component is often a complicated one to answer. The issue is further complicated by whether the analysis is performed for an entire system or simply a particular component of an existing coal handling/ conveying system. In most cases, a thorough economic cost study is the only effective way to obtain a quantified answer. Key O&M Cost Point

As a general rule, if the repair costs 50% or less of the replacement cost, repair should be considered. If the percentage is greater, replacement is generally the best option.

5-2


This rule is generally effective if the system can be taken out of service during replacement construction. Of course, one option is to do nothing or defer the maintenance. Figure 5-2 illustrates a number of factors that should be considered when performing a comprehensive analysis. Some of the factors are easier to quantify than other factors, and in some cases, actual costs can be estimated. To quantify the results of the analysis, some factors can be weighted as to their relative importance in the calculation.

Figure 5-2 Factors Considered During the Decision-Making Decision-Making Process [18]

Because of the complexity of the analysis and the varying relevancy of each factor, this report does not attempt to provide a mathematical equation for performing such a calculation. The reader should also note that some of the factors are more qualitative in nature and, as such, tend to be more difficult to quantify where an economic cost study is desired. Each of the factors illustrated in Figure 5-2 is discussed in “Quantifiable Factors for Economic Cost Study.” The reader should recognize that this list of factors is not all-inclusive and is provided for illustrative purposes only.

5-3


5.1.1 Quantifiable Factors for Economic Cost Study As noted in the previous section, some factors are easier to quantify than other factors, and in some cases, costs can be estimated for each course of action. A brief discussion of the quantifiable factors and costs follows: Cost of the repair – One of the primary factors that should be considered is the cost of the repair. This cost is typically composed of the costs for materials, equipment, labor, and preparation needed to perform the repair. For the purposes of this report, this cost would not include follow-on maintenance costs associated with maintaining the repaired components over the life of the operating system.

•

Cost of replacement – Another primary factor that should be considered is the cost of replacement. This can apply to either the entire system or a particular component under evaluation. Similar to estimating the cost of a repair, replacement costs should include the costs for materials, equipment, labor, and preparation needed to replace the existing component(s). Likewise, for the purposes of this report, this cost would not include follow-on maintenance costs associated with maintaining the replaced components over the life of the operating system.

•

Anticipated maintenance costs – When making the decision to replace or repair a particular component, the manager should consider the anticipated maintenance costs associated with either action. Whether an item is replaced or repaired, there will be costs associated with maintaining it for some period of time. An estimation of projected maintenance costs should include the following components:

•

– Maintenance equipment costs – Special equipment and/or tools are often required to perform a repair or to replace a given item. The costs of using these items should be factored into the decision whether to replace or repair it. – Labor costs – The labor costs associated with projected or anticipated maintenance are important to consider, because they can constitute a significant component if the life expectancy of the operating system or component is high. Labor costs can be affected by the availability of maintenance personnel, whether special or unique skills are required, and/or whether the maintenance personnel are in-house or contracted. •

•

5-4

Demolition costs – In many cases, there are significant demolition costs associated with a replacement that are not necessarily as important when performing a repair. Demolition costs should include costs associated with preparing the system or structure for the replacement, removal of the components that have been replaced, and disposal of the waste. Hazardous materials handling costs – In some cases, there are costs associated with handling certain hazardous materials (such as asbestos, lead paint, and hazardous chemicals) that should be factored into the overall cost of performing maintenance and/or repair on existing operating systems and their components. These costs might be so significant that the most economical option is to defer the maintenance or repair until the end of the service life of the facility.


5.1.2 Key Qualitative Factors in the Decision-Making Process Several key qualitative factors that should be considered in the analysis are discussed in more detail: •

Rate of deterioration – The rate of deterioration is another factor that should be considered when comparing the cost benefits of repairing and replacing a system component. The rate of deterioration primarily influences the urgency with which the item needs to be addressed. For an item failing at a slow rate, the system owner is afforded additional time to decide what course of action to take. In some cases, the rate of deterioration can be so slow that the best course of action is to defer any action until the component’s condition becomes more severe. Items failing at a faster rate require that more prompt action be taken.

•

•

•

•

5.2

Age of the system/component – The age of the operating system and its components should be factored into the evaluation for a number of reasons. First, the older the system, the less likely it will be that repairs will be feasible. Conversely, the newer the system, the less likely that it would be beneficial to replace the entire system and the more likely that it would be to perform repairs of specific components. Second, older systems might have a number of maintenance issues that need to be considered simultaneously. As such, the repair costs of these multiple issues should be considered together and not separately. Risk to process outage/stoppage – The risks associated with inadvertently interrupting the process(es) should be considered from two perspectives—short term and long term. In the short-term perspective, the system owner should consider which action, repair, or replacement might present the least risk to interrupting the processes. In some cases, a repair can be performed without any disruption to the processes, whereas a replacement might require that the process equipment be shut down until the replacement is complete. When this is the case, the system owner might also consider the cost of lost production necessitated by the replacement. Expected life of the replacement or repair – Other factors that should be considered are the expected life of the replaced or repaired component. Regardless of what action is taken, the restored condition will not last forever. In time, the item will either have to be initially repaired, repeatedly repaired, or replaced again. How much time elapses before one of these follow-on activities occurs will vary and depend on the maintenance decisions made now. Regulatory issues – Any regulatory issues that have arisen or new regulations that have been enacted since the original construction of the system should also be considered when deciding the optimum maintenance action to take.

Repair and Replacement of Coal Handling System Components

Sections 5.2.1 through 5.2.14 summarize guidance regarding the repair or replacement of coal handling system components. Because of the complexity of many of the system components integral to a coal handling system, most are repaired as needed until they have reached the end of their service life. Depending on the extent of the repair and the skill of the craft within the maintenance organization, assistance from an authorized service representative recommended by the original equipment manufacturer might be warranted. 5-5


5.2.1 Belt Scales Table 5-1 summarizes the typical repairs and replacements that can be conducted on site for belt scales installed in a coal handling system. Table 5-1 Recommended Repairs and Replacements for Belt Scales Courtesy of Thermo Electron Corporation Item

Repair and Replacement Activities

Idler rolls

Replace rolls or bearings as needed.

Belt scraper

Replace blades if worn.

Speed pulley

Replace bearings if worn.

Speed sensor coupling

Replace coupling if worn. Realign if needed.

Alignment

Perform alignment procedure per manufacturer’s recommendations.


5.2.2.1


Table 5-2 summarizes typical repair and replacement activities for a rotary railcar dumper. Depending on the particular make, model, and manufacturer of the equipment, the extent to which assemblies are repaired or replaced in their entirety will vary from plant to plant. As such, Table 5-2 provides a generic scope of corrective maintenance activities that typically could be performed on site using utility maintenance personnel with assistance from the manufacturer’s service representatives. Table 5-2 Recommended Repairs and Replacements for Rotary Railcar Dumpers Courtesy of Heyl & Patterson, Inc. Item


Speed reducer

Replace speed reducer. (Refer to the EPRI report Gearbox and Gear Drive Maintenance Guide [1] [1] for repairs and replacement of speed reducer/gearbox sub-assemblies.) Gear guards should be replaced as needed.

Flex coupling

Replace flexible coupling. (Refer to the EPRI report Flexible Shaft Couplings Maintenance Guide [2] [2] for repairs and replacement of flexible mechanical couplings.)

Pinion shaft assembly

Replace shaft assemblies as needed. Assemblies can be repaired by replacing items such as the shaft, coupling, pillow block(s), spur pinion, and sprockets.

Intermediate shaft assembly Idler shaft assembly

5-6


Table 5-2 (continued) (continued) Recommended Repairs and Replacements for Rotary Railcar Dumpers Courtesy of Heyl & Patterson, Inc. Item


Drive chain connecting pin

This heat-treated steel drive chain connecting pin should be replaced as needed.

Rotating wheel pin assembly

Replace assembly as needed. Assembly can be repaired by replacing items such as the pin, wheel, spacers, end plates, roller bearings, and end seals.

Clamp chain

There should be no slack in the clamp chains. If a chain link breaks, the entire length of drive chain should be replaced due to chain wear. Replacing on broken chain link can cause more downtime when the other worn links start to fail.

Tag Lines

Replace tag lines (and fittings) as needed.

Tag line spring yoke assembly

Replace assembly as needed. Assembly can be repaired by replacing items such as the spring yoke(s), stem, yoke plate, and spring.

Clamp lock helical compression springs

Replace as needed.

Car wheel platen roller

This item can be replaced as needed (typically provided with bronze bushings).

Limit switches

Replace switches as needed and in accordance with the limit switch manufacturer’s recommendations.

Drive chain

Adjust the slack in the drive chain so that there is about 2½ in. (6.35 cm) of sag. Adjustment can be made by using the two adjustment bolts at either end of the chain. These two bolts are typically part of the chain anchors. If a chain link breaks, the entire length of drive chain should be replaced due to chain wear. Replacing on broken chain link can cause more downtime when the other worn links start to fail. Drive chains should be free to pivot on chain pins. Failure to lubricate chain will cause chain links to freeze up and jam in the drive sprockets and overload the drive.

Platen

Add or remove counterweights to ensure proper clearance and engagement.

Platen hold-down brackets

Platen hold-down brackets engage the hold-down beam and prevent the platen from dropping when the dumper is rotated without a car. Brackets must be adjusted to have a minimum clearance (typically 5/16 in. [7.9 mm]).

5-7


Table 5-2 (continued) (continued) Recommended Repairs and Replacements for Rotary Railcar Dumpers Courtesy of Heyl & Patterson, Inc. Item


Platen rails

Tighten loose bolts and replace missing bolts. Replace rusted or damaged tread bolts. Adjustment of platen rails within 1/8 in. (3.2 mm) minimum difference of elevation of the yard rails should be maintained. Shims are typically furnished under the platen to allow al low for such adjustments.

Platen thrust wedges

Adjust with the addition or removal of shims.

End ring rails and wheels

Wheels with cracked flanges and severely worn treads should be replaced. If bolts are loose, replace per manufacturer’s recommendations. Replace any broken, rusted, and damaged thread bolts. Bolts should be tightened in areas where end ring rails are in contact with the trunnion wheels.

Positioner carriage rollers

Replace rollers when the treads become severely worn.

5.2.2.2

Train Positioner

Table 5-3 summarizes typical repair and replacement activities for a train positioner. Table 5-3 Recommended Repairs and Replacements for Train Positioner Courtesy of Heyl & Patterson, Inc. Item


Train positioner, wheel chock, and rope tensioner hydraulic system

Repeated solenoid burnout indicates that the oil should be checked. If necessary, replace the oil, clean and an d flush the system and reservoir, and replace the strainer. Oil should be filtered to 10 μm before oil is poured into the reservoirs. The positioner rope length should be adjusted so that the piston rod of the takeup cylinder operates normally about two-thirds within the cylinder. Replace return line filter elements when the filter requires cleaning.

Positioner ropes

As the positioner is used, the ropes will stretch, causing slack. Removal of slack is accomplished continuously by a hydraulic cylinder. Excess slack, once the cylinder stroke is used up, should be removed by following the manufacturer’s specific procedures.

Positioner rope roller supports

Replace any worn rollers (minimum diameter is typicall y specified by the manufacturer).

Bolts

If, for any reason, the threads are stripped or rusted, or if a bolt is broken, the bolt should be replaced immediately with a new bolt. Refer to the manufacturer’s recommendations for the correct size and material of the replacement bolt.

5-8


Table 5-3 (continued) (continued) Recommended Repairs and Replacements for Train Positioner Courtesy of Heyl & Patterson, Inc. Item


Shims

Throughout the overall installation, shims have been employed to bring dimensions of the machinery within the desired operational dimensional tolerances. If, for any reason, shims have to be replaced, or if the machinery that sits on them is removed, the following action is suggested for replacement. Before tightening the anchor bolts, ensure that the base sits evenly on all the required shims so that distortion after tightening the bolts will not occur. Before starting the equipment, check for alignment of couplings and gear teeth with all anchor points bolted bol ted down tight. If misalignment is detected, correction should be made by insertion of proper shims before the unit is put into operation.

Couplings

Adjust angular alignment and offset alignment in accordance with procedures provided by the coupling manufacturer.

Wire rope

Replace wire rope if worn, bent, or frayed.

Sheaves and drums

Re-groove, re-turn, or replace sheaves and drums if they have improperly fitting grooves or broken flanges. Repair drums in the case of failed or cracked welds.

5.2.2.3


Table 5-4 summarizes typical repair and replacement activities for a traveling hammermill. Table 5-4 Recommended Repairs and Replacements for a Traveling Hammermill Courtesy of Heyl & Patterson, Inc. Item


Traverse chain sprockets

Replace sprockets when badly worn.

Hammer and T-bolts

Replace hammer and/or bolt when measurement indicates wear of approximately 1/2 in. (12.7 mm).

Bolts

If the threads are stripped or rusted or if a bolt is broken, the bolt bol t should be replaced immediately with a new bolt. Refer to the manufacturer’s recommendations for the correct size and material of the replacement bolt.

Couplings

Adjust angular alignment and offset alignment in accordance with procedures provided by the coupling manufacturer.

5-9


5.2.2.4

Stationary Barge Unloader

Table 5-5 summarizes typical repair and replacement activities for a stationary barge unloader. Table 5-5 Recommended Repairs and Replacements for a Stationary Barge Unloader Courtesy of Heyl & Patterson, Inc. Item


Hold-and-close ropes

Replace ropes after that part of the rope running through the bucket sheaves begins to show wear. (This procedure is often referred to as paying out .) .) The time interval between changes and the amount of rope to be replaced are left for field fiel d determination after ropes have been observed in operation. Paying out the ropes should be performed in accordance with the manufacturer’s procedure(s).

Hold-and-close rope reels

When one of the reels becomes empty, place a new reel on the stand and attach the new rope to the end of the old rope by means of a cable grip (typically 1 in. [25.4 mm]). The new rope should then be reeved into the system by following the manufacturer’s procedure. When pulling rope through the system with the hoisting drum, operate the drum until the cable grip with the new rope comes into the machinery room. Disconnect the new rope and run all the old rope off of the drum. Connect the new rope to the drum, and then run the engine until the rope on the drum reaches the mark where the old rope left the drum.

Bucket

Reeve the new bucket in accordance with the manufacturer’s procedures.

Trolley rope

Tighten trolley rope by means of ratchet takeup on the end of the trolley, using a socket and ratchet wrench.

Trolley runway rails

Paint structure as needed to repair excessive corrosion.

Barge haul rope

Replace when worn, in accordance with manufacturer’s recommended procedure.

5-10


5.2.2.5

Bucket Barge Unloader

Table 5-6 summarizes typical repair and replacement activities for a bucket barge unloader. Table 5-6 Recommended Repairs and Replacements for a Bucket Barge Unloader Courtesy of Heyl & Patterson, Inc. Item


Sheaves and drums

If the sheaves or drums are scored or cut from the old rope, they should be renewed so that the re-lubricated or renewed rope will not receive undue wear. Also, if the sheaves and drums have improperly fitting grooves or broken flanges, they should be re-grooved, returned to the manufacturer for refurbishment, or replaced in their entirety.

Bolts

If for any reason the threads are stripped or rusted, or if a bolt is broken, the bolt should be replaced immediately with a new bolt. Refer to the manufacturer’s recommendations for the correct size and material of the replacement bolt.

Bucket

Reeve the new bucket in accordance with the manufacturer’s procedures.

Shims

Throughout the overall installation, shims have been employed to bring dimensions of the machinery within the desired operational dimensional tolerances. If for any reason shims have to be replaced, or if the machinery that sits on them is removed, the following action is suggested for replacement. Before tightening the anchor bolts, ensure that the base sits evenly on all the required shims so that distortion after tightening the bolts will not occur. Before starting the equipment, check for alignment of couplings and gear teeth with all anchor points bolted bol ted down tight. If misalignment is detected, correction should be made before the unit is put into operation by insertion of proper shims.

Boom hoist rope

Replace in accordance with manufacturer’s recommended procedure.

Barge haul rope

Replace when worn, in accordance with manufacturer’s recommended procedure.

5.2.3 Unloading Hoppers Repair of unloading hoppers typically consists of replacing worn pieces of hopper wall or liner. In some cases, repair or replacement of structural members might be called for, depending on the severity of the wear and degradation.

5.2.4 Sampling Equipment Table 5-7 summarizes typical repair and replacement activities for coal sampling equipment installed in a coal handling system. 5-11


Table 5-7 Recommended Repair and Replacement Activities for Coal Sampling Equipment Courtesy of Thermo Electron Corporation Item Primary sampling machine

Repair and Replacement Activities Replace sample cutter if worn. Adjust cutter brushes and wipers as required. Replace main bearings as needed.

Primary belt feeder

Replace bearings as needed. Repair/replace conveyor belt in accordance with manufacturer’s recommended procedures.

Coal sampling crusher

Replace bearings as needed. Replace worn, loose, or corroded fasteners.

Secondary sweep sampler

Replace sample cutter if worn. Adjust cutter brushes and wipers as required. Replace main bearings as needed.

Secondary feeder


Sample collector

Any repairs or replacement of sample collector parts shoul d be performed in accordance with the manufacturer’s recommended procedures.

Reject return conveyor


Sweep sampler

Replace limit switch as needed. Replace worn, stripped, or corroded fasteners and set screws. Replace the sweep brush and wiper if i f they are worn. Replace pillow block bearings as needed.

5-12


5.2.5 Crushers Tables 5-8 through 5-11 summarize various repair and replacement activities undertaken for various types of coal-crushing equipment installed in a coal handling system.

5.2.5.1

Breakers

An antirotation device is typically provided on a breaker/hybrid-breaker that prevents the cylinder from rotating during maintenance. The mechanism is typically located on the discharge end wheelstand, and should be engaged prior to conducting any repairs or replacements. Table 5-8 Recommended Repair and Replacement Activities for Breakers/Hybrid-Breakers Breakers/Hybrid-Breakers Courtesy of Pennsylvania Crusher Corporation Item


Wheel bearings

Replace when worn, in accordance with manufacturer’s recommendations.

Chain

Replace chain if broken or excessively worn.

Cylinder drive

Overhaul speed reducer and, when complete, ensure the following:

Spider clearance

•

Bearings, chain, and reducer are properly lubricated.

•

Clutch coupling is aligned.

•

Driving and driven sprockets are aligned.

•

Chain tension is correct.

•

Chain casing and other safety guards are installed.

Confirm that clearance between casing seal retainer plates and spiders is correct. Confirm that clearance between feed and refuse chutes and spiders is correct.

Cylinder

Balance the cylinder in accordance with manufacturer’s recommended procedures. Confirm that the cylinder interior arrangement is properly assembled. Confirm that the cylinder is free of loose l oose foreign articles.

Lifting shelves

Adjust lifting shelves for either neutral, retard, or advance positions, as needed.

Deflectors

Adjust deflectors in the event that the 45° initial angle setting is not sufficient to convey coal or the deflector has moved after operation.

Tires

Replace tires in accordance with manufacturer’s recommended procedure when worn or deformed.

Wheels

Replace wheels in accordance with manufacturer’s recommended procedure when tires are worn or deformed.

Fasteners

Replace if broken or missing.

5-13


5.2.5.2

Cage Mills

Table 5-9 summarizes the repair and replacement activities recommended by most manufacturers of cage mills. Table 5-9 Recommended Repair and Replacement Activities for Cage Mills Courtesy of Pennsylvania Crusher Corporation Item


Cage assembly

Overhaul the cage assembly in accordance with the manufacturer’s detailed procedure.

Sleeve

Balance sleeve in accordance with the manufacturer’s recommendations.

Inner cage sleeve

Replace if worn or damaged.

Outer cage sleeve


Bearings and shaft

Replace bearings, bearings shaft, and frame if worn or damaged, in accordance with the manufacturer’s recommended procedure.

Housing liner

Replace liners prior to wearing completely through.

Tapered bearing


Locking assembly

Adjust as needed. Replace if worn or damaged.

V-belt drive

Replace belt if worn, cut, frayed, or stretched from its origi nal configuration.

5-14


5.2.5.3

Granulators

Table 5-10 summarizes the repair and replacement activities recommended by most manufacturers of granulators. Table 5-10 Recommended Repair and Replacement Activities for Granulators Courtesy of Pennsylvania Crusher Corporation Item


Rotors

In most cases, it is recommended that worn or damaged rotors be returned to the manufacturer for disk replacement and/or other repair. Refer to the manufacturer’s instructions for rotor removal and installation.

Bearings

Replace bearings when worn, in accordance with the manufacturer’s instructions.

Hammers

Hammers are considered worn when the teeth projections are barely noticeable and the ring body has been reduced to approach one-half the original thickness. Hammers should be replaced a t this point. With further wear, the rings will elongate and eventually break. Replacement hammers might need balancing, which should be performed in accordance with the manufacturer’s recommended procedure.

Cage

Screen plate and cage breaker plate replacements are normal maintenance items. Generally, screen plates require replacement more often than the cage breaker plate. Frequency will depend on the wearing characteristics of the material, tonnage crushed, and frequency of tramp iron.

Frame

Repair coating on frame as needed.

Liner

Liners can be considered worn when exposed faces have worn to the point where there is danger of a hole developing. At this point, material could be driven through holes and cause frame wear. Generally, liners should be replaced when an area or spot on the liner has worn to a thickness of 1/4 in. (6.35 mm).

Upper and lower kickoff plates

Normally, kickoff plates do not wear with the same frequency as screen plates and do not require replacement as often. Kickoff plates can be considered ready for replacement when any section of the part has been worn to a thickness of approximately 5/8 in. (15.8 mm). Further wear will make the plate susceptible to breakage under a crushing load or the passage of uncrushed coal.

5-15


5.2.5.4

Hammermills

Table 5-11 summarizes the repair and replacement activities recommended by most manufacturers of hammermills installed in a coal handling system. Table 5-11 Recommended Repair and Replacement Activities for Hammermills Courtesy of Pennsylvania Crusher Corporation Item


Rotors

In most cases, it is recommended that worn or damaged rotors be returned to the manufacturer for disk replacement and/or other repair. Refer to the manufacturer’s instructions for rotor removal and installation. If it is necessary to weld on any part of the rotor disks, the disks must be grounded to prevent any arcing through the be arings.

Hammers

Replacement of hammers is recommended when the crushed product becomes too coarse to be acceptable. Replacement and installation should be in accordance with the manufacturer’s instructions. Replacement hammers might need balancing, which should be performed in accordance with the manufacturer’s recommended procedure.

Liner

Liners can be considered worn when an area or spot has decreased to 1/4 in. (6.35 mm) or less, and should be replaced in accordance with the manufacturer’s instructions.

Cage assembly

Replacement of normal wearing parts, such as breaker plates, screen plates, and tie plates, is recommended when the amount of wear affects the crushed product. Replacement and installation should be in accordance with the manufacturer’s instructions.

Bearings

Replace bearings when worn, in accordance with the manufacturer’s instructions.

5-16


5.2.6 Reclaim Hoppers Table 5-12 summarizes typical repair and replacement activities for a vibratory drawdown type of reclaim hopper. Table 5-12 Recommended Repairs and Replacements for Vibratory Drawdown Reclaim Hoppers Courtesy of Carman Industries, Inc. Item Driven shaft assembly

Repair and Replacement Activities V-belt pulleys and tapered bushings – The pulley and tapered bushing can be removed in the same manner as any standard pulley and tapered bushing. First, remove the bolts (generally three) that hol d the bushing and pulley together. Next, using the same bolts as jack screws, screw the bolts into the tapped holes in the tapered bushing. Tighten them uniformly, forcing the bushing apart from the pulley. Remove pulley and bushing. Both the motor (drive) pulley and shaft (driven) pull ey can be removed in this manner. Bearing end caps, floating and fixed – Each bearing housing assembly has an aluminum cap. The pulley end of the shaft has the floating end cap. The other end has the fixed end cap. The fixed end cap conceals a lock nut and tabwasher, which fixes, or locks, the shaft to the bearing. If care is taken, the shaft may be removed from the unit by removing only the floating end bearing assembly. If this is done, be careful not to damage the seal on the fixed end bearing housing. To remove the fixed end cap, simply remove the socket head cap screws that hold the cap to the bearing housing and lift off. Bearing housings – Be sure to support the shaft before attempting to disassemble. To remove the fixed end bearing housing, the shaft lock nut and tabwasher must be removed. Remove these by first bending back the locking tab of the tabwasher. Now unscrew and remove the lock nut from the shaft. (Omit this step for the floating end housing.) The fixed end bearing housing or floating end housing can now be removed. Unbolt the bearing housing from the drive plates. The housings are bolted in place with grade 5 hex-head machine bolts and self-locking nuts. If any thread damage is evident on bolts bol ts or nuts, replace both with new ones. Now the housing is ready for removal. Eccentric weight assembly and driven shaft – Before the driven shaft can be removed, the eccentric weight assembly must be loosened. Before loosening the eccentric weight or adder weights, note the eccentric weight’s amount and thickness of adders. A measurement from the side plates to center of the eccentric weight must be made and recorded to ensure that the drive is reassembled properly. Note: the eccentric weight is positioned symmetrical with respect to the drive rings (top and bottom plates). Begin by first removing the retaining collar below the eccentric weight hub. This collar clamps around the shaft to prevent the eccentric weight from sliding or working its way down the shaft. Next, loosen the two set screws in the eccentric weight hub. Check and see if the eccentric weight is loose. The driven shaft can now be removed. Caution: Caution : use care, as the eccentric weight assembly is heavy. It is advisable to support the eccentric weight assembly while removing the shaft. Once the shaft is removed, the eccentric weight can be removed.

5-17


Table 5-12 (continued) (continued) Recommended Repairs and Replacements for Vibratory Drawdown Reclaim Hoppers Courtesy of Carman Industries, Inc. Item


Drive shaft bearings

Replace bearings as needed in accordance with the manufacturer’s recommendations.

V-belt

Tighten V-belts per manufacturer’s belt-tensioning specification.

Bolts and fasteners

Replace missing bolts and fasteners as needed.

5.2.7 Discharge Hopper Feeders Table 5-13 summarizes typical repair and replacement activities for a vibratory discharge hopper feeder. The extent to which assemblies are repaired or replaced in their entirety will vary from plant to plant and will depend on the particular make, model, and manufacturer of the equipment. Table 5-13 provides a generic scope of corrective maintenance activities that typically could be performed on site by utility maintenance personnel with assistance from the manufacturer’s service representatives. Table 5-13 Recommended Repairs and Replacements for Discharge Hopper Feeders Courtesy of General Kinematics Corporation Item


Drive motor

Replace motor as needed. Motor assembly can be repaired by replacing items such as the electrical cable, cord grip, self-locking bolts and washers, and sealing material.

Ground strap

Replace ground strap. Ensure that there is slack in the grounding strap to compensate for the up-and-down motion of the unit while the unit is running with and without material load.

Reactor spring assembly

Replace reactor spring as needed, and replace hex-head bolts, washers, and lock nuts.

Rocker leg assembly

Replace rocker leg as needed, and replace hex-head bolts, washers, lock nuts, and bushings.

Eye bolt assembly

Replace eye bolt as needed, and replace washers and lock nuts.

Taper-lock bushings

Replace bushings in accordance with manufacturer’s instructions.

5-18


5.2.8 Magnetic Separators Table 5-14 summarizes the repair and replacement activities recommended by most manufacturers of magnetic separators. Table 5-14 Recommended Repairs and Replacements for Magnetic Separators Courtesy of Dings Company Magnetic Group Item


Magnet bearings

Replace bearings if worn.

Magnet cooling oil (transformer type)

The oil should be laboratory tested every 12 months for moisture, contaminants, and dielectric strength. The oil only needs to be changed if it fails the dielectric test, has been contaminated with moisture, or is dark and turbid (cloudy) or smells burnt.

Self-cleaning belt

Replace belts in accordance with manufacturer’s recommendations.

Fasteners

Replace worn, corroded, stripped, or fractured fasteners.

Tracking of belt

Adjust belt tracking/tension in accordance with manufacturer’s recommendations. See Section 5.2.8.1.

Zero-speed switch

Replace switch in accordance with manufacturer’s recommendations.

5.2.8.1

Procedure for Adjusting the Tracking/Tension of the Self-Cleaning Belt

Belt tracking and belt tension should be checked at least every 3 hours for the first two days of operation, and once every three days after that. If the magnetic separator is to be installed on an angle (inclined crossbelt), most manufacturers recommend that the belt be tracked with the magnet level, then suspend it at its intended position. The maximum recommended angle of tilt for a crossbelt separator is 20° on a standard design. If the belt is running off towards the lower side, tighten the takeup on the high side or the side that the belt is traveling away from. Figure 5-3 illustrates how belt tracking and tension can be adjusted.

5-19


Figure 5-3 Configuration for Adjusting Magnetic Separator Belt Tracking/Tension Courtesy of Dings Company Magnetic Group

In general, one of the following two procedures should be followed: 1) looking at the takeup end of the magnet for a four-pulley design, tighten the left takeup to move the belt to the left, or tighten the right takeup to move the belt to the right; or 2) looking at the takeup end of the magnet for a two-pulley design, tighten the right takeup to move the belt to the left, or tighten the left takeup to move the belt to the right.

5.2.9 Slide Gates Table 5-15 summarizes the repair and replacement activities recommended by most manufacturers of slide gates. The only parts on a slide gate that would typically be replaced are the gate blades and inlet seals due to wear. An example of an inlet seal replacement procedure follows Table 5-15 and is provided for illustrative purposes. Occasionally, fasteners need replacing if lost or damaged during long-term operation. If the slide gate is operated with an air actuator, piston seals can be replaced in accordance with the manufacturer’s detailed instructions. Table 5-15 Recommended Repairs and Replacements for Slide Gates Courtesy of Salina Vortex Corporation Item


Gate blade

Replace if worn after long-term operation of the slide gate or if damaged.

Gate inlet seals

Replace if worn after long-term operation of the slide gate or if damaged.

Fasteners

Replace if lost or damaged during long-term operation of the slide gate.

Air piston seals


5-20


Many slide gates and aggregate gates use abrasion-resistant, reinforced rubber seals in handling that demand material such as sand, gravel, whole grains, and coal. As with any slide gate or diverter valve, read and follow all safety instructions prior to installing, maintaining, or operating equipment. The following procedure for replacing inlet seals is provided for illustrative purposes and might not be applicable to all types of slide gates and diverter valves. Note that inlet seals are typically located behind the seal retainers. With the blade in the open position, perform the replacement as follows: 1. Remove, in this order, the end seal retainer and rubber end seal, the right- and left-side seal retainers and rubber side seals, the upper bonnet seal retainer, and rubber upper bonnet seal. If the lower bonnet seal is being replaced (located under the upper bonnet seal, beneath the blade), remove the lower bonnet seal retainer at this time. Replace the lower bonnet seal prior to progressing to Step 2. 2. Insert the new upper bonnet seal behind the upper bonnet seal retainer and install. 3. Close the blade prior to installing the remainder of the inlet seals. 4. When installing the side seals, ensure that the notch is indexed to the bottom and inserted into the side of the rear bonnet seal. 5. Insert the right-side seal behind the right-side seal retainer and install. Use a putty knife to seat the seal on the blade as each screw is tightened. Install the left-side seal in the same manner. 6. Insert the end seal behind the end seal retainer, making sure it is seated against the blade as each screw is tightened.

5.2.10 Dust Control System Table 5-16 summarizes typical replacements that can be accomplished in the field for dust collection equipment installed in a coal handling system. Because of the complexity and uniqueness of dust collection/suppression systems, system owners should consult the guidance provided by each manufacturer for any additional repairs or replacement of major components within the system. Table 5-16 Recommended Repairs and Replacements for Dust Collection Equipment Courtesy of Airtrol, Inc. Item


Filter bags

Replace when needed (excessive holes result in decreased filtering efficiency).

Bearings

Replace in accordance with the manufacturer’s recommended procedure(s).

Chains and belts

Replace in accordance with the manufacturer’s recommended procedure(s).

5-21


5.2.11 Conveyor Belts, Pulleys, Idlers, and Rollers The two most common types of corrective maintenance on a conveyor belt system are retraining the belt travel and splicing new sections of conveyor belt material. Idlers, pulleys, rollers, instrumentation, and switches are typically replaced in kind, and in accordance with each manufacturer’s specific instructions.

5.2.11.1

Tracking Procedure for Conveying Systems

Tracking the belt is a process of adjusting idlers, pulleys, and loading conditions in a manner that will correct any tendencies of the belt to run other than true. A normal sequence of training is to start with the return run, working toward the tail pulley, and to follow with the top run in the direction of belt travel. Start with the belt empty. After tracking is completed, run the belt with a full load and recheck tracking. Tracking adjustment is done while the belt is running and should be spread over some length of the conveyor preceding the region of trouble. The adjustment might not be immediately apparent, so permit the belt to run for several minutes and at least three full belt revolutions after each idler adjustment to determine if additional tracking is required. After adjustment, if the belt has overcorrected, it should be restored by moving back the same idler, and not by shifting additional idlers or rollers. If the belt runs to one side at a particular point or points on the conveyor structure, the cause will probably be due to the alignment, the leveling of the structure, the idlers and pulleys immediately preceding that particular area, or a combination of these factors. If a section or sections of the belt run off at all points along the conveyor, the cause is possibly in the belt itself, in the belt not being joined squarely, or in the loading of the belt. With regard to the belt, this will be due to camber. The condition should improve after the belt is operated under full load tension. It is a rare occasion when a cambered belt (less than 0.5%) needs to be replaced. These basic rules can be used to diagnose a belt running poorly. Combinations of these rules sometimes produce cases that do not appear clear-cut as to cause, but if there is a sufficient number of belt revolutions, the running pattern will become clear and the cause disclosed. In those unusual cases where a running pattern does not emerge, it is quite likely that at some point the belt is running so far off that it is fouling structure or mounting brackets, bolts, or some other part. This results in highly erratic performance and can be a real problem. We would suggest that in this event, the full tracking procedure be employed. It is quite likely that the erratic performance will be resolved in the process.

5-22


When replacing a used belt, go through the system and square and level all rollers, idlers, pulleys, and bed before training a new belt. The basic/primary rule of tracking is illustrated in the following Key Technical Point. Key Technical Point

The basic, primary rule that must be kept in mind when tracking a conveyor belt elt m oves oves towar towar d whichever whichever end of the r olle ollerr /idler /idler it conta conta cts is simple. The b elt first.

Readers can demonstrate this for themselves very easily by laying a small dowel rod or round pencil on a flat surface in a skewed orientation. If a book is now laid across the dowel rod and gently pushed by one’s finger in a line directly away from the experimenter, the book will tend to shift to the left or right depending upon which end of that dowel rod the moving book contacts first.

5.2.11.2

Belt Splicing: Centerline Method

To establish the belt centerline, start near the belt end. Measure the belt width at seven points approximately 1 ft (30.5 cm) apart. Divide each measurement in two and mark these center points. Using these seven center points, pop a chalk line to form the belt’s centerline. Next, using a carpenter square or T-square, draw a cut line across the width of the belt near the belt end. Repeat this for the other belt end. Using the cut line as the guide, cut off the end of the belt with a sharp razor knife. Make sure that the cut is clean and vertical. This operation should then be repeated on the other end of the belt. (Keep in mind that the final belt length might need to include an allowance for such things as diagonal splice, skive taper length, skive overlap, finger punching loss, fastener extension, and so on, depending upon what kind of splice is being performed.) After establishing the centerline, pick a point on the centerline that is approximately two or three times the belt width from the belt end. An arc is now struck. A nail can be used as the pivot point and a length of twine as the arm of the arc. A pencil or crayon can be tied to the other end of the twine to serve as the marker of the arc. A second set of arcs is now struck, but the pivot point in this case is on the centerline and is close to the belt end. The arc length is slightly less than one-half of the belt width. Now draw a line from one pair of intersecting arcs to the other. This is the cut line, and it should be perpendicular to the centerline of the belt. The relative position of the top and bottom covers or surfaces of the belt should be considered when positioning the roll for threading. Once the roll of belting has been brought to the point of installation, it should be mounted on a shaft for purposes of unrolling and threading onto the conveyor. In some cases where headroom does not permit maneuvering a roll, the belt might 5-23


have to be pulled off the roll and reefed. Great care should be exercised to see that the loops have large bends to avoid kinking or placing undue strain on the belt. Weight should never be placed on the belt when it is in a reefed position. Another method of handling belting under certain conditions would be to lay the roll on a turntable with a vertical spindle. The belting should now be pulled onto the conveyor either by attaching it to one end of the old belt that has been cut or, in the case of a new installation, by threading by hand. It can also be installed by first threading a rope or cable around the idlers and pulleys and subsequently connecting that cable or rope to the new belt by means of a clamp that will evenly distribute the tensile load over the width of the belt. Come-alongs, which do not evenly distribute the tensile load over the width of the belt, can cause damage to the new belt, with poor tracking characteristics one possible result. Various types of splices are used on conveyors. However, by far the most common method of joining belt belt ends is the metal metal fastener, fastener, such as the the clipper types types of the alligator alligator construction constructions. s. Fastener manufacturer catalogs should be consulted for proper size and method of application. The wire lace type of fastener consists of many wires pressed into the belt, forming a series of wire locks extending beyond the ends of the belts. The belt ends, each containing one-half of the fasteners, are meshed together and the pin is inserted like a door hinge. A machine must be used for proper installation of the fasteners into the belt. This type of fastener is typically available in different sizes, which should accommodate virtually any belt used on a coal handling system. The alligator steel hinge type of lace can be applied with a hammer. The belt is simply laid down on a flat surface and the ends of the prongs merely driven into the belt. The two belt ends are meshed together and a steel hinge is used in a manner similar to that previously described. For heavier belts, plate fasteners are available, both with and without hinge pins, and with either screw or rivet components. Rivet types are usually preferred because they cause the least amount of damage to the belt warp yarns. It is extremely important that the fastener manufacturer’s instructions be followed. A perfectly square belt end can be rendered quite un-square by improper installation of the fastener. It is a good idea to actually measure how far the fastener projects beyond the end of the belt at one edge as compared to the other—projection should be equal. The size of the fastener used is governed by the thickness of the belt and the diameter of the smallest pulley involved. The metal fastener manufacturer’s instructions should be used to install and connect the fasteners that are used. If leakage is a problem with the metal fasteners, the joints can be covered with either a hot or hybrid splice. cold cure material to stop leakage of fines. The result is usually referred to as a hybrid splice Conveyor belts can be spliced endless using a variety of techniques, including: •

Step splice

•

Finger splice

•

Skived splice

5-24


Step splices are normally used in conventional plied rubber constructions. Straight warp or solid woven carcasses are typically joined with either a finger splice technique or a skived splice technique. Belt manufacturers should be contacted to obtain the appropriate splice kits.

5.2.12 Movable Tripper Devices Tables 5-17 and 5-18 summarize repair and replacement activities typically undertaken for belt tripper devices. Table 5-17 Recommended Repairs and Replacements for Motor-Propelled Belt Tripper Devices Courtesy of FMC Technologies, Inc. Item Belt tripper

Repair and Replacement Activities Replace the reel, wheel, and wheel guard. Replace the rail clamp assembly and the limit switch. Replace the axle for babbitted bearings and roller bearings for axle shaft. Replace or rewind the motor. Replace the pulley. Replace the current collector. Replace the pulley, pulley shaft for babbitted bearings, and babbitted bearings for pulley shaft. Replace roller chain.

Belt scraper assembly

Replace spring. Replace maple bar, rod, and rubber strip.

Clamp assembly

Replace stationary jaw and movable jaw. Replace pin and bracket. Replace handwheel and handwheel stud.

5-25


Table 5-18 Recommended Repairs and Replacements for Cable-Propelled Belt Tripper Devices Courtesy of FMC Technologies, Inc. Item


Tripper

Replace wheel, wheel guard, axle for babbitted be arings, and axle for roller bearings. Replace the pulley, pulley shaft for babbitted bearings, and babbitted bearings for pulley shaft. Replace propelling cable (typically plow p low steel wire rope with hemp center). Replace outboard bearings.

Towing bracket assembly

Replace rope sheaves, sheave bearing, sheave pins, an d sheave pin thimble.

Belt scraper assembly

Replace spring. Replace wooden bar, rod, and rubber strip.

Haulage machine

Replace worm gear speed reducer. Replace double-groove sheave. Replace pivot pin and single-groove sheave pin. Replace reversing limit switch assembly. Replace or rewind motor. Replace motor flexible coupling.

5.2.13 Gearboxes The maintenance activities recommended in this section are generic in nature and might not be applicable, in whole or in part, to all gearboxes installed in power generating facilities. Each user of this report should apply the guidance in this report in conjunction with the equipment-specific guidance provided by each particular gearbox manufacturer when performing gearbox maintenance.

5.2.13.1

Typical Procedure for Gearbox Disassembly

5.2.13.1.1

General Guidance

The following disassembly sequence is provided in this report for information purposes only and should not be used without reference to the manufacturer’s instructions that are specific to the actual gearbox being maintained. Note that any work done on equipment during the manufacturer’s warranty period without the written approval of an authorized manufacturer’s representative could void the warranty. 5-26


Lock-out/tag-out procedure – These steps should be followed to complete lock-out/tag-out: •

Identify the energy sources used and all control devices.

•

Notify all affected personnel.

•

Turn off all operating controls.

•

Lock out or tag out all switches and energy controls to their off or safe positions.

•

Test all operating controls to ensure that no power is getting to equipment.

•

Perform required maintenance.

Visual inspection – The following sequence is for complete disassembly. Visual inspection of the gearing through the inspection cover might provide the information necessary to determine the cause of a problem without complete disassembly. 5.2.13.1.2

Tools Required

For disassembly and reassembly, several commonly available tools might be required. No special tools or fixtures are required for the housing and gears, and oftentimes no tools for assembly/disassembly are provided by the manufacturer. Following is a list of some tools that can be useful: •

Crane or hoist, along with soft slings or chains

•

Eye bolts

•

Dial indicator

•

Pry bar

•

Crocus cloth or fine steel wool

•

Wrenches, screwdrivers, and torque wrench

•

Prussian blue or similar dye for tooth contact check

•

Loctite® No. 49-31 Plastic Gasket or equivalent plastic gasket material

5.2.13.1.3

Spare Parts

Parts such as gaskets should be replaced when disassembly is performed. The manufacturer should be contacted to obtain a list of recommended spare parts because they vary from one manufacturer to another and from one mode to another. 5.2.13.1.4

Removal of Gear Cover

Inspections typically performed prior to gear cover removal include as-found alignment conditions and various end-play checks and verifications. 5-27


Throughout the disassembly sequence, observe carefully what might have occurred inside the unit and record the position and condition of any failed parts. Note any parts, bolts, nuts, or holes that are numbered or match-marked; they must be reassembled as matched for correct assembly. The disassembly sequence for the gear cover is as follows: 1. Remove any deflectors, baffles, or coupling guards. 2. Disconnect the high-speed and low-speed couplings. 3. Disconnect any piping, conduit, or wiring that joins the housing sections. 4. Remove any bearing temperature sensor service heads, probes, or other auxiliary instruments that could be damaged by removal of the cover. 5. Remove the cap screws in the upper half of the seals, end caps, and thrust bearing housing; if lock-wiring is supplied, cut where necessary. 6. Remove end caps, seals, and gaskets. 7. Carefully loosen the thrust-bearing housing. (Use the jacking screw holes to loosen from gear housing.) 8. Remove all cap screws and nuts on the parting line. Leave studs in place to serve as guides for cover removal. 9. Break the parting-line seal by using jacking screws in the jacking screw holes located on each end of the gear unit. Some sharp raps with a rawhide hammer at the corner positions and prying with a large screwdriver might be needed to loosen the parting-line joint. 10. Attach a crane or hoist to the lifting provisions in the cover and carefully lift the cover by lifting both ends equally about 1/4 in. (6 mm). Check that bearings remain seated and no conduit or wiring that crosses the parting line is still connected. 11. Check the upper and lower speed bearing halves to see if they are stuck in the cover. If they are, carefully pry them out or push them out with a rod inserted through the bearing thermometer holes. 12. Carefully lift the cover straight up until it clears the gearing. The cover will need enough clearance above the gear and studs for the cover to be removed. Caution: do not bump gear assembly with the raised cover. 13. Place the cover on wood blocks so that the machined split line will not be damaged. Care should be taken to ensure that internal lubrication lines are not damaged. 5.2.13.1.5

Removal of Pinion, Gear, and Bearings

Removal of gearing from housing is not required if only the rotating element inspection is needed. Radial bearings can be removed and replaced by rolling shells out of housing, one bearing at a time (replace each bearing after inspecting it and prior to inspecting other bearings). The thrust bearing is typically more difficult to remove and reinstall than the radial bearings, and detailed guidance is provided in the following section.

5-28


Following is the sequence for removal of the pinion, gear, and bearings: 1. Mark the location of each bearing in the housing so that it can be reassembled correctly. 2. With the bearings in place, remove the pinion using a soft sling on each side of the mesh. Place the shaft on a soft material (such as wood or rubber) or a padded V-rack, taking care not to damage the gear teeth. 3. Remove the upper half of the low-speed bearings. 4. Remove the low-speed gear and shaft assembly with a chain inserted through a lifting hole or eye bolts inserted into the gear. Care should be taken to protect the teeth by placing wood blocks between the chain and the sides of the gear. 5. Place the gear on wood or another soft surface, taking care not to damage the teeth. Block each side to prevent the gear from rolling. 6. Gears can be inspected at this time in accordance with the guidance provided in this report. Key Technical Point

When the lubrication system is inoperable, it is advisable to pour a small amount of oil on each bearing or journal surface in the gearbox to provide an oil film when rotating the rolling gear elements.

5.2.13.1.6

Thrust Bearing Removal

The thrust bearing might contain temperature sensors, and the lead wires exit the bearing housing through the oil fitting. Following is a sequence for removal of the thrust bearing: 1. Remove the temperature sensors from the thrust-bearing shoes with a small hooked probe to pull out the star washer through the access cover adjacent to the sensor connection heads. 2. Remove the thrust-bearing end-cap bolts. 3. Remove the end cap and shims from the thrust-bearing housing. 4. Use wide jaw pliers to pull the outer backing ring a short distance out of the thrust-bearing housing. 5. Remove the outer backing ring and thrust pads. Mark the position of pads containing embedded temperature sensors so they can be returned to their original locations. 6. Remove the axial probe target plate. 7. Loosen the set screws or locking tabs in the thrust collar lock nut. Note that some thrust collars are integral to the shaft. 8. Remove the lock nut by turning it counterclockwise. Use a spanner wrench or a small punch inserted into the spanner holes to loosen the nut. 9. Insert cap screws into the threaded puller holes in the thrust collar. 10. Carefully remove the thrust collar. Do not allow the collar to drop down and damage the lock nut threads as it is being removed. 11. Mark the position of the inner thrust pads containing embedded temperature sensors so they can be returned to their original positions. Remove the shoes and inner backing ring. 5-29


Oil sample collection – If needed, an oil sample (typically a full quart or liter) can be collected at this time for later analysis.

5.2.13.2

Inspection and Maintenance of Gears

5.2.13.2.1

Introduction

The purpose of this section is to describe why gear tooth contact should be checked regularly, how the actual check is made, and how to interpret the tooth contact check on power transmission gearing with involute double helical teeth and parallel input and output shafts. 5.2.13.2.2

Purpose of Checking Tooth Contact

Gear teeth must have an even load across the entire face width to minimize stress on the teeth. The contact between gear teeth is line contact; therefore, the alignment between the rotating elements (pinion and gear) is critical. Tooth alignment is controlled by the accuracy of the rotating elements, the housing, and the bearings assembly. 5.2.13.2.3

When to Check Tooth Contact

Tooth contact should be checked on all new installations, after any disassembly of the gear unit, and after any major housing-to-foundation change. It might also be checked as part of routine annual maintenance or when a problem related to alignment is suspected. Contact should be checked on the foundation being replaced to be sure the unit will operate properly. 5.2.13.2.4

How to Check Tooth Contact

The contact can be checked two ways: Soft blue – Apply soft machinist’s bluing or transfer bluing to the teeth of one gear and roll that gear by hand through mesh with its mating gear. (The terms blue and bluing are used for convenience; the dye is available in other colors. A soft blue check is usually run across another element that is coated with another color, such as soft yellow. This contrast results in a more distinct, representative contact pattern.) The transfer of the blue from one gear to the other gear is read as the contact. Hard blue – Paint the gear teeth with hard or layout blue, run the gear unit, and observe the pattern of wear-off of the bluing.

Contact checking can usually be accomplished through the inspection cover port. Occasionally, soft blue checking is done with the housing cover removed, such as during the reassembly process.

5-30


5.2.13.2.5

Interpretation of Tooth Contact

The following is information to be used only for guidance in deciding if tooth contact is adequate. In most cases, the gearbox manufacturer should be consulted on how to correct poor contact. Assuming properly manufactured parts, minor corrections can be made to the tooth contact by shimming the gear housing. Exactly what contact should be acceptable should be based on the manufacturer’s recommendations and experience. Maintenance personnel should remember that tip or root relief modifications are designed to improve load distribution when a unit is operating under load, but they can make the contact appear quite bad under no load, as in a soft blue check. Generally, with a soft blue check, one is looking for some blue to transfer, usually in a line that covers at least 80% of the face width, a centralized 60% coverage, or acceptable contact patterns consistent with those illustrated in Figure 5-4. Do not be alarmed by a lack of blue covering the flank of the tooth; flank contact should normally not extend entirely to the tip of the tooth. Figure 5-4 illustrates various examples of tooth contact patterns. Keep in mind that a soft blue contact will not produce impressions as dark as those made by hard blue—look for the same pattern in a sketchy impression.

Figure 5-4 Tooth Contact Patterns Courtesy of Lufkin, Inc.

5-31


The hard blue operational/running tooth contact check can be done from no load to full load, and the results will vary with the load condition. If the unit is run at no load, the test will usually appear similar to a soft blue check. More blue will wear off the pinion than the gear due to the higher number of cycles the pinion sees. As the load increases, blue will wear off more of the tooth flank. Look for evidence of even load across as much of the gear tooth, both flank and face width, as possible.

5.2.13.3

Maintenance of Bearings

5.2.13.3.1

Bearing Clearance

Measurement of bearing clearances can be accomplished while the gear is stopped by lifting the shaft and measuring the distance traveled with a dial indicator or by using feeler gauges, carefully sliding a feeler gauge between the top of the bearing bore and the shaft. Some wear should be expected, especially on a gear that is stopped and started frequently. The bearing can be considered operational as long as the measured clearance does not exceed the design clearance by more than 0.004 in. (101.6 μ m). m). Note that if shaft vibration is excessive, this clearance increase might not be acceptable, especially on large or small bearings. For instance, a small, 3-in.-diameter (10.16-cm-diameter), high-speed bearing with a design clearance of 0.003– 0.005 in. (76.2–127 μ m) m) could not withstand a clearance increase of 0.004 in. (101.6 μ m). m). The clearances on the tilt pad bearings are difficult to check accurately and can normally be classified as acceptable if they show no signs of distress, damage, or excessive wear. 5.2.13.3.2

Bearing Contact Correction

After bearing contact is satisfactory, it might be possible to improve gear tooth contact by adjusting the shims under the unit. Do not attempt to modify the bearing contact of the tilt pad journal bearing bearing in any manner except except to remove remove any localized localized nicks or dings (high (high spots). Sometimes gear tooth contact can be corrected by scraping and polishing one of the bearings loaded in the bottom section to spread the contact along the face width. If this is necessary, the manufacturer should be contacted. After correcting bearing and tooth contact and before putting the cover on the gearbox unit, the bearings should be liberally lubricated with clean oil to provide for initial startup lubrication. 5.2.13.3.3

Correcting Bearing High Spots

Bearing high (bright) spots should be lightly scraped and polished with fine steel wool or crocus cloth until they blend in with the rest of the bearing.

5-32


5.2.13.3.4

Flaking of Babbitt

If flaking is caught in the early stages, the bearing can be repaired by scraping and polishing. The cause of vibration or hammering should be corrected before the gearbox unit is put back in service. In the advanced stages of flaking, the load-carrying area of the bearing is typically destroyed and the bearing must be replaced. 5.2.13.3.5

Correcting Bearing Scoring

A little scoring is not serious, and the bearing can be polished with fine steel wool to remove any rough edges caused by scoring. Any foreign particles embedded in the babbitt that could score the journal should be carefully picked out, and that area should then be polished smooth. Scoring becomes serious when it significantly reduces the bearing area. In this case, the bearing should be replaced and the gearbox unit drained and flushed out with a solvent. 5.2.13.3.6

Correcting Bearing Wiping

If wiping is localized in a small spot, the bearing can be repaired by scraping and polishing the spot until it blends in with the remainder of the bearing. Otherwise, the bearing must be replaced. Bearing scraping requires experience and expertise, however, as well as sound judgment when deciding whether to dress or replace the item. Key Technical Point

Before replacing a wiped bearing, determine and correct the cause of the wipe.

5.2.13.3.7

Replacement Bearings

The manufacturer’s parts list should be referenced if it is determined that bearings need to be replaced. If new bearings are used, the following precautions should be taken: 1. Remove all nicks and burrs from the housing and bearing shell. 2. Ensure that journals are free of nicks and high spots. These can be removed using a fine hone and polishing with crocus cloth. 3. Obtain the proper bearing contact as described in the manufacturer’s technical literature. 4. After bearings are fitted and lower halves are installed in the housing, check the radial clearance using feeler gauge or plastic gauge material. Check end-play by barring the shaft axially.

5-33


5.2.13.4

Typical Procedure for Gearbox Reassembly

5.2.13.4.1

Preparation

The following reassembly sequence is provided for information purposes only, and should not be used without reference to the manufacturer’s instructions that are specific to the actual gearbox installed at the site. Note that any work done on equipment during the manufacturer’s warranty period without the written approval of an authorized manufacturer’s representative could void the warranty. This procedure assumes that the gear housing is not removed from its foundation/support and that the original shaft alignment was correct. Additional information regarding shaft alignment techniques is provided in the EPRI report Shaft Alignment Guide [19]. Following is the reassembly sequence for the gearbox: 1. Clean all interior surfaces of the housing, the housing cover, and all components that will be reused. Parting line surfaces must be clean and smooth; use a spray-on paint and gasket remover fluid and/or carefully scrape the surfaces if necessary. Corroded spots can be cleaned by using a fine emery cloth, rubbing shafts in a rotary or circumferential direction. Do not rub shafts in a lengthwise direction as it can cause seal leaks. 2. Check the bearing shells, the parting line, and the housing bores for any burrs or nicks: remove with a fine file. 3. Put a coat of light oil on all parts to help assembly and to prevent rust during reassembly. Use fresh oil from the gearbox supply for this. Do not use special oils (STP ®, for example) because their separate additives might cause operational problems. The guidance in the following sections assumes that the entire unit must be reassembled. Note: tighten connectors uniformly; when tightening bolts, studs, or screws on an assembled portion with three or more holes, always partially tighten connectors equally in a cross pattern to avoid torquing, binding, or warping the section. 5.2.13.4.2

Typical Reassembly Sequence

Although instructions include using sealer between housing sections, this should actually be done on the final assembly, and only after tooth contact has been checked and proper alignment of the unit has been ascertained. Following is the procedure for reassembling the bearing, gear, and pinion assembly. 1. Install journal bearings – Before installing journal bearings, note that pressure dam bearings are match-marked and are not interchangeable. a. Install the lower half of the low-speed journal bearings (the half with the slot for the roll pin, if there is one) in the housing in the position for which they were marked at disassembly, keeping parting lines on bearing and housing even.

5-34


b. Check with a 0.0015-in. 0.0015-in. (38.1- μ m) m) feeler gauge to see that lower halves are seated. Consideration can be given to measuring bearing clearance by direct measurement of the inner diameter (ID) and the shaft journal outer diameter (OD). Another alternative is to use a commercially available plastic gauge (for example, Perfect Circle Plastigage ®). c. Ensure that the pressure dam is seated in the correct location. d. Check bearing contact as described in the instructions specific to the size, type, and model bearing in use. Do not attempt to install shafts with lower halves of thrust bearing in housing; babbitt-faced thrust faces might be damaged. e. Rethread any temperature sensor wires from bearing through housing. 2. Install gear – Lift the low-speed gear and carefully place the assembly in its correct location in the gear housing and bearings. Use care to avoid bumping housing or edges of bearings. 3. Set the top of the gear bearings in place and secure bolts or bearing straps if supplied. Turn bearings in bore if necessary. 4. Install pinion – Install the pinion bearings on the pinion, ensuring that the pinion is level, and line it up in mesh with the gear. 5. Carefully set the pinion and its bearings in mesh with the gear, and roll along gear until bearings are seated in the housing. 6. Line up the pins in the housing grooves and rotate bearings until seated. Following is a typical procedure for assembling the gear cover: 1. Lower the cover over the studs carefully to prevent damage to gearing. It will need to be suspended high enough to reach RTD holes. 2. Thread the temperature sensor wires from the bearings as necessary to retain the leads extending into the housing. 3. Coat the split line with a small bead of sealer, such as Loctite ® No. 49-31 Plastic Gasket, or an equivalent plastic gasket material. Circle all studs to ensure sealing of oil, but avoid feeder groove areas. 4. Seat the cover onto the bottom section and install the cylindrical dowel pins. Caution: do not assume doweling is accurate. Straight dowels have clearance, which over time can become out of tolerance. Consideration might be given to using tapered dowels if dowel clearances prevent the proper seating and positioning of the gearbox cover.

5. Tighten all cap screws and studs in accordance with the manufacturer’s recommended instructions. Typical torque values for grade 5 bolts and studs are provided in Table 5-19.

5-35


Table 5-19 Recommended Tightening Torques Courtesy of Lufkin, Inc. Nominal Size

Tightening Torque for Bolts

Tightening Torque for Studs

in.

mm

ft.lb

N-m

ft.lb

N-m

1/2

12.7

75

102

87

117

5/8

15.9

150

203

173

234

3/4

19.0

266

360

307

416

1

25.4

644

873

742

1006

1¼

28.8

1120

1519

1484

2012

1½

38.1

1949

2643

2582

3501

1¾

44.5

2286

3100

4073

5522

6. Perform a soft-blue gear tooth contact check in accordance with the guidance contained in this report. 7. If the contact is not acceptable, check for improperly meshed gears, burrs on shafts or housing bores, or twisted housing. If no satisfactory explanation can be found, contact the manufacturer. 8. Install thrust bearing: a. Replace the inner backing ring. It must be firmly seated against the wall of the housing. b. Thoroughly clean each thrust-bearing shoe. c. Apply a liberal quantity of thick grease to the back side of each thrust shoe. The grease will serve as a temporary adhesive to keep the shoes positioned in the backing ring as they are installed. d. Install the inner thrust shoes, taking care to place each shoe that has an embedded temperature sensor in its original position. e. Install and tighten the thrust collar lock nut and tighten the two thrust collar set screws. f. Install the axial probe target plate. g. Place the outer backing ring on a flat surface. Apply a liberal quantity of grease to the back side of each outer thrust pad and position the thrust shoes on the backing ring. Ensure that the shoes with embedded temperature sensors are located in their original positions. h. Lift the outer backing ring assembly and install it into the thrust-bearing housing.

5-36


i. Install the adjusting shims and thrust-bearing end cap and tighten securely. Be very careful while handling and installing the shims, because torn or crimped shims can cause incorrect adjustments. j. Install temperature sensors in their shoes through the access covers. 9. Measure to ensure that the low-speed shaft has specified axial movement. (Use a pry bar to move gear from side to side if necessary.) Also check that the high-speed pinion can float axially. 10. Mount the shaft seals, end plates, and other auxiliary equipment that might have been disconnected during disassembly. 11. Reconnect any junction box plate and wiring as necessary. 12. Reconnect any instrumentation and lubrication lines as necessary. 13. Couple unit to driver and driven machines. 14. Install inspection covers with gaskets and sealers. 15. Align the unit. 16. Spin the unit slowly with no load, if possible, to verify correct reassembly. Ensure that the unit rotates freely and quietly. 17. Confirm proper shaft alignment and tooth contact. 18. Follow the manufacturer’s startup procedures.


5.2.14.1

Maintaining Proper Fits Associated with Couplings

5.2.14.1.1

Shaft to Hub Fits

The type of fit between a shaft and a hub can be one of three types: •

Clearance fit with key

•

Interference or shrink fit with key

•

Keyless interference fit

Interference-fit coupling hubs on straight shafts require a method of removal to avoid damage to the shaft or the coupling.

5-37


When coupling hubs are received, whether bored to size or rough-bored, they typically do not have holes tapped to facilitate a puller. Unless specified, the hub is often provided without puller holes. The manufacturer can usually provide guidelines for the hole size, thread, and location for layout of the holes. High-performance couplings are sometimes furnished with two keys to distribute the shear stress on two keys instead of only one. Care should be taken when using a hub and shaft, which employ two keys. The coupling and the shaft should be match-marked to ensure that the coupling is returned to the same orientation on the shaft each time. This is especially true when rotor balancing is to be performed. Lubrication of the key with a slight coat of nickel Never-Seez™ or N-5000 will prevent galling. 5.2.14.1.2

Clearance Fit with Key

Some coupling manufacturers recommend clearance fits that can be used on up to 4 in. (10.2 cm) of shaft diameter. A large shaft and a combination of large misalignment can create bending moments and thus flexing of the hub to the shaft. In practice, clearance fits should not be used above a diameter of 2.75 in. (7.0 cm). However, the manufacturer of the equipment and the coupling manufacturer should always be consulted to provide the appropriate fit for the equipment in question. Speed and torque should also be considered when determining the type of fit. Torque is transmitted through the keys on all keyed couplings. Clearance fits should be limited to small horsepower applications. Set screws are used to minimize play between the hub and shaft and to also limit movement of the hub and/or key in the axial direction. Clearance fits are not normally used on shafts with speeds above 1800 rpm. Key Technical Point

Coupling key clearance fits should be limited to 0.002 in. (51 µm) maximum. On larger diameter shafts, this might require heat to expand the hub.

5.2.14.1.3

Couplings with Shrink or Interference Fits

Couplings with shrink fits to shafts provide for a tight fit, resist forces and moments applied across the coupling, and prevent rocking on the shaft. This benefit subsequently prevents fretting, which can result in failure of the shaft and/or the coupling. An excessively tight fit with keyed hubs induces stresses and can cause cracking of the hub; thus, care should be taken to avoid this condition. The American Gear Manufacturers Association (AGMA) and American Petroleum Institute (API) 671 are quite explicit concerning these shrink fits. The hubs on shrink-fit shafts are driven by the key(s). The fit is to prevent rocking and axial movement of the hubs.

5-38


The following guidance should be considered for maintaining shrink fits on straight shafts: •

•

•

Some coupling manufacturers provide a calculated interference based on the size of the shaft. This generally ranges from 0.00075 in. to 0.001 in. (19 to 25 μ m) m) per inch (25.4 mm) of shaft diameter. Experience has shown that, more commonly, these numbers should be reduced to around 0.0005 in. (12.7 μ m) m) per inch (25.4 mm) of shaft diameter. For a 3-in. (76.2-mm) shaft, a maximum of 0.002 in. (51 μ m) m) is typical. For shafts larger than 3 in. (76.2 mm), a good rule is to use 0.00025 in. (6.35 μ m) m) for each additional inch (25.4 mm) of shaft diameter. Manufacturers also provide heating instructions for hubs. These recommendations usually request that a heater of some sort be used instead of an open flame from a torch. Oven heating in something similar to a welding rod oven is generally one of the better methods. Oil-bath-type heaters might also be considered, but care should be taken to ensure that the elevated hub temperature remains well below the flash point of the oil. Manufacturer’s limits on heating should be followed and often limit heating to less than 250°F (121.1°C). This can be verified with a Temp Stik rated for the desired temperature. Experience has shown that a good method for determining if the hub is hot enough to be installed is to use a measuring device. One of the preferred methods is to use a telescoping gauge set slightly larger (0.0005–0.001 in. [12.7–25.4 μ m]) m]) than the interference fit. When the temperature is acceptable for installation, the gauge should easily pass through the hub. Key Human Perfor Perfor mance Point Point Caution : when heating a coupling, care must be taken to prevent contact with the hub because contact will cause severe burns. A threaded rod inserted in the puller holes works well to handle heated components during installation. The use of welder’s gloves can prevent burns.

•

The interference fits recommended by manufacturers are generally acceptable numbers for installation of the hubs. However, the numbers recommended give one the added advantage of removing the hub without problems such as galling occurring. Key Human Perfor Perfor mance Point Point

An important reminder is that usually a torch is required to remove the hub at the equipment location. If the location of the equipment is such that the environment is volatile, the rotor should be removed and transported to an area where conditions are safer. •

Large interference fits also pose problems when spacing between shafts is minimal. In some cases, the hub must be allowed to cool while a different fixture is used to continue pulling the hub. In this case, the hub must be heated a second time for removal. 5-39


The following guidance should be considered when maintaining shrink fits on tapered shafts: tapered coupling fits (shafts) are common on many equipment applications. The taper provides for an easy installation and removal, all the while allowing for a proper and tight fit from the hub to the shaft. Second, tapered shafts are common on what are typically referred to as high-energy machines, such as feedwater pumps, large fans, compressors, and so on. Shafts are manufactured using various tapers, normally ranging from 1/2 in./ft to 1¼ in./ft (4.2 cm/m to 10.4 cm/m). Manufacturers design a particular taper based on the fit required and the size of shaft. Tapers can be described either in terms of a ratio or a taper per foot. The most common tapers are 1/2, 5/8, and 1¼ in. per foot (4.2 cm, 5.2 cm, and 10.4 cm per meter). Table 5-20 sets forth a table of interferences. Table 5-20 Table of Interferences [2] Coupling Hub Bores and Shafts Bore Shape

Straight

Drive method

Keyed

Keyed

Hydraulic

Interference

0.5–2 mils (12.7–51 μm) total

1 mil/in. dia. (1 μm/mm)

1.5–2.5 mils/in. (1.5–2.5 μm/mm)

Taper

Tapered

5/8 in./ft (5.2 cm/m) 3/4 in./ft (6.25 cm/m) 1 1/4 in./ft (10.4 cm/m)

Minimum contact area Bore out of roundness (Max) to 4 in. over 4 in. (10.2 cm over 10.2 cm)

70%

80%

0.2 mil (5 μm) total indicator runout (TIR)

The following example can be used to calculate the advance or pull-up of a coupling. In this example, assume the following: Shaft diameter = 5 in. (12.7 cm) Taper per foot = 1¼ in./ft (10.4 cm/m) Interference = 0.001 in./in. = 0.005 in. (127 μ m) m) Advance is calculated by dividing I t (total interference) by T pi (taper per inch). Advance = It / / Tpi Advance

=

.005 = .048 inch (1.22 mm) 1.25 12

5-40


Tapers can also be expressed as a ratio. This ratio is based on the distance of a taper to change the shaft size or diameter by 1 in. (2.5 cm). For example, a shaft having a 1/2-in. taper per foot would be 1:24 taper, changing by 1 in. for every 24 in. in length (4.2 cm per meter is a 1:4 taper, changing by 1 cm for every 4 m in length). Table 5-21 illustrates the relationship between expressing tapers as inches per foot and ratios. Table 5-21 Expressing Tapers [2] Taper Expressed as Inches per Foot

Corresponding Corresponding Taper Expressed as a Ratio

1/2 in. taper per foot (4.2 cm/m)

1:24 (1:4)


1:20 (1:5)


1:16 (1:6)

1 in. taper per foot (8.3 cm/m)

1:12 (1:8)

1¼ in. taper per foot (10.4 cm/m)

1:8 (1:10)

Proper heating of a tapered hub is extremely important—in many cases, more so than with a straight shaft. Overheating the hub will allow it to travel further on the shaft, making it almost impossible to remove when and if the time comes. This problem can be remedied with a stop installed behind the hub. But by being too hot, it is also difficult to keep it on the taper. If the correct temperature is used, the hub can be maintained on the taper until the shaft nut is installed. When the hub has cooled, it will also shrink some amount in the length direction. The coupling nut should then be tightened again, and secured with set screw(s) into the face of the shaft or hub. Key Technical Point

Proper heating of a tapered hub is extremely important and in many cases c ases is more so than with a straight shaft.

Sometimes there is not enough room between the hub and bearing housing to install a stop device. When this is the case, one of several alternative methods can be used to stop the hub. If a rotating seal is used on the bearing housing and set screws are provided to secure the seal to the shaft, they can sometimes be used and set in a location to stop the hub. After the hub is secured, the seal can be re-set to the proper location. If the seal is of a type that cannot be moved, shims such as feeler gauges can be placed between the hub and the seal to limit the travel of the hub. Another option is to bolt a strong-back across the coupling face. A bolt in the center can be used as an adjustable contact stop with the end of the shaft.

5-41


The following guidance should be considered for maintaining keyless interference fits: •

•

A keyless interference fit is usually referred to as a hydraulically dilated coupling. The hydraulically dilated coupling hub is used in locations where heat or open flame is not acceptable. This is an excellent method of installing and operating a coupling. The hydraulically dilated coupling hub is keyless and is tapered at 1/2 in. per foot (4.2 cm per meter). The coupling hub has O-rings and Teflon™-type backup rings on both ends of the coupling. A hydraulic pump should be used to pressurize inside the coupling through drilled passages in the shaft. (Note: some coupling hubs have grooves to accommodate this, which facilitates installation/removal.) The coupling nut is two-piece and should have Orings and backup rings inside of it. When the hub is pressurized, the valve is diverted to push the piston inside the coupling nut and advance the hub the prescribed amount. The pressure is then released between the coupling and the shaft, and the hub shrinks to the shaft. Once this is accomplished, the pressure is relieved on the nut and the pump is removed. The inner portion of the nut is then tightened against the outer ring and set screwed to the shaft. Key Human Performance Point

Ensure that hydraulic equipment is in good working order to preclude the danger of hydraulic hoses under high pressure separating and causing personnel injury.

The following guidance should be considered for maintaining proper contact of tapered hubs to shafts: •

•

Table 5-20 shows the acceptable contact between the coupling hub and the shaft, for example, 70% contact by blue on a keyed shaft and 80% by blue on a keyless shaft. The shaft should be dyed using Prussian blue, and the coupling hub should be pushed straight up on the shaft in a swift, firm motion. Do not slam the hub home. When installed properly, the hub can then be removed, sometimes with assistance from a mallet. The blue contact area can then be checked on the shaft to determine if the amount of contact is satisfactory. If contact is not satisfactory, lapping must be done to one or both of the pieces. Key Technical Point

Under no circumstances should the taper bore coupling be lapped to the shaft. This will create a step on the shaft over which the coupling hub h ub must pass, leaving a non-contacting area under the coupling hub. •

The shaft and coupling hub can be lapped with a ring-and-plug gauge. Ring-and-plug gauges are devices fabricated, usually by the coupling manufacturer, to check contact of shafts and hubs. The ring is a female fit for the shaft and the plug is a male fit for the hub. These are used as standards to verify correct fits of hubs and shafts. The original ring-and-plug should not be used for lapping. A reproduction of these manufactured from highly finished cast iron should be used for lapping.

5-42

Repair and Replacement Replacement for Coal Handling System Components •

API 671 states that the machinery supplier responsible for supplying the coupling for a tapered shaft fit should also supply a ring-and-plug gauge to verify the correct taper and fit of a coupling hub to the shaft. This is to be used as a standard to dye (blue) the shaft and hub for proper fits. Reproductions of these standards can be used to lap a shaft and hub to achieve the proper blue contact of the two parts.

5.2.14.2

Maintaining Alignment of Couplings

Coupling misalignment differs from shaft misalignment. Shaft misalignment is measured in offset and angularity. Coupling misalignment is measured in an angle of degrees of misalignment. Whether the shaft has offset or angularity or both, the coupling misalignment is at an angle. Manufacturers might provide an offset as related to an angle for the design length of the coupling. Each flex plane of the coupling can have a different amount of misalignment. The distance between flex planes and the angle of misalignment can be converted into offset at the coupling flex planes or the two shafts it connects. How much misalignment can a coupling compensate for? This depends on the type of coupling, the torque applied, and the distance between flex planes. Most couplings for rotating machinery in the power station are designed for a range of 1/4–1/2° of misalignment. This can still pose a problem for machinery if operated with this misalignment. Key Technical Point

Coupling misalignment differs from shaft misalignment. Shaft misalignment is measured in offset and angularity. Coupling misalignment is measured in an angle of degrees of misalignment.

5.2.14.3

Installation of Couplings

5.2.14.3.1

Installation of Gear and Grid Couplings

When couplings are installed on shafts, a sequence of events should take place to ensure that the couplings are installed properly. For close coupled applications, either one of the machines must be moved to make room for installation or the rotor must be removed to facilitate installation. If the rotor is removed, an opportunity arises to install one-half of the coupling on the removed rotor at this point in time. The other half is installed on the machine left in place.

5-43


With spacer-type couplings, this problem is avoided, as typically there is room to install both halves without removing component parts such as rotors and without having to move one machine out of the way. If the coupling that was removed from the shaft(s) is the one being reinstalled, the processes of installation are usually streamlined by ensuring that: •

Coupling halves are installed in the correct position on the shaft.

•

Shaft separation is correct.

•

Gaskets are in good condition and in place.

•

Bolts are tightened properly.

•

Shaft alignment is performed to align the two machines within specifications for the running position (operating conditions such as pipe strain and temperature).

If the coupling installation uses a new coupling, the installation becomes more involved and includes the following: •

•

•

•

Ensure that the coupling hub(s) are bored to the proper dimension without run-out. Ensure that the keyway is broached properly and is on centerline, not skewed off centerline in one direction. Confirm that the keyway depth is correct to ensure that the hub will travel across the key during installation and the key size (height and width) is correct. If the coupling is heated for installation to facilitate an interference fit, the hub will stand off the shaft at the key location after cooling. Key Technical Point

The hub will stand off the shaft at the key location after cooling if the coupling is heated for installation to facilitate an interference fit. •

Ensure that the shaft-to-shaft (hub-to-hub) dimension is correct after installation.

•

The coupling should be lubricated if grease is used while the coupling is apart.

•

Manufacturer’s specifications should be followed closely when greasing a coupling.

•

After the coupling is bolted together, shaft alignment should be performed to align the two machines within specifications for the running position (operating conditions such as pipe strain and temperature).

5-44


5.2.14.3.2

Installation of Disk and Diaphragm Couplings

The installation process described for gear coupling hubs typically applies to disk or nonlubricated coupling hubs. The difference is that disk and diaphragm couplings are more restricted in the amount of axial movement they can accommodate. For this reason, the shaft-to-shaft spacing is critical. The disks or diaphragm must be in a neutral position when shafts are in their running position. The spring rate (stiffness) of a disk or diaphragm coupling dictates how much tolerance from neutral the disk or diaphragm can demonstrate as a result of shaft separation.

5.2.14.4

Balancing of Couplings

Users are often unsure about coupling imbalance, whether there is a need to balance the coupling or the coupling is already balanced. The AGMA publishes data concerning coupling balance. Unless special-ordered, most likely the couplings in service have not been dynamically balanced, because most couplings in use in power plant applications fall into the general-purpose category. Imbalance can be defined as a force caused by eccentricity or weight. Residual imbalance is the remaining imbalance of a rotor or part—residual imbalance below the required imbalance or criteria specified by industry standards.

Couplings, unlike shafts, must have mandrels or arbors inserted to achieve balancing. Methods of balancing couplings are component balancing and complete dynamic balancing of the entire coupling. As noted, the majority of couplings in a generating station are not balanced. However, the individual hubs are normally balanced with the rotor of a machine. In most instances, this is acceptable for an unbalanced coupling. If balancing is specified for a coupling, either by the end user or the equipment supplier, the coupling can be component-balanced or dynamically balanced, depending on what is necessary as determined by the coupling and the equipment manufacturers. Key Technical Point

The majority of couplings in a generating station are not balanced.

A typical coupling is balanced as follows: 1. Balance each hub separately. 2. Balance the sleeve separately. 3. Balance the hardware (bolts, nuts, and washers) by weight balance. 4. Balance as an assembly with corrections made to the sleeves. 5. Match-mark parts before removing from the balancing mandrel. 5-45


(Note: when balancing a gear coupling as a unit, take extra care to ensure that the tooth clearance is correct. If a shrink fit is used in the coupling design, the test stand might require a shrink fit as well to expand the hub to obtain proper tooth tip clearance.) Imbalance is usually expressed in terms of weight times distance (for example, ounce-inches or gram-inches). If an imbalance weight of 1 ounce (28.3 g) exerted at a radius 4 in. (10.2 cm) on the coupling, the total imbalance would be 4 ounce-inches. This can also be mathematically changed into some convenient measuring form for the balancing machine. The centrifugal force of the imbalance can be specified in g force or in micro-inches of eccentricity by AGMA. The primary goal is to reduce the centrifugal forces generated at a given speed. The force can be calculated as shown in the following example: Ounce-inch of imbalance at 2000 rpm and 4000 rpm F @ 2000 rpm = 14.1 lb (6.34 kg) F @ 4000 rpm = 56.6 lb (25.5 kg) Therefore, if the speed doubles, the same amount of imbalance produces four times the force.

5-46

6

COAL HANDLING SYSTEM/COMPONENT SYSTEM/COMPONENT TROUBLESHOOTING

6.1

System Troubleshooting Troubleshooting

Figure 6-1 illustrates the generic process for performing preliminary troubleshooting of a given power plant system, such as the coal handling conveying system. The figure emphasizes the need to define the problem, determine and validate system operating conditions, and subsequently determine whether the symptoms adversely affect system/component performance or reliability.

6-1

Coal Handling System/Component Troubleshooting

Figure 6-1 Generic Process for System Troubleshooting Troubleshooting (Preliminary Evaluation) [16]

Figure 6-2 illustrates the detailed system troubleshooting process that can be undertaken to investigate the symptoms and performance problems being experienced. The figure emphasizes the need to identify failure modes, develop a troubleshooting plan (especially if the system is evaluated while on-line), identify the cause(s) of the problem, and restore system performance. Additional guidance regarding system and component troubleshooting is provided in the EPRI report System and Equipment Troubleshooting Guideline [16].

6-2


Figure 6-2 Generic Process for System Troubleshooting Troubleshooting (Detailed System Troubleshooting) Troubleshooting) [16]

Tables 6-1 and 6-2 summarize troubleshooting guidance at a system level for the four different types of system designs discussed in this report.

6-3


6.1.1 Typical Coal Handling Systems Table 6-1 summarizes troubleshooting guidance for a typical coal handling/conveying system. The table lists system-level failure mechanisms, the potential causes for failure, and frequently used solutions to restore the system to an operational state. Table 6-1 Recommended Troubleshooting for Coal Handling/Conveying Systems Failure Mechanism(s) Inadequate coal flow

Cause(s)

Frequently Used Solutions Solutions

Reclaim hoppers are plugged or unable to provide sufficient quantities of coal.

Clear blockage in hopper.

Discharge hopper feeders are plugged or fouled.

Clear blockage in hopper feeder or trough.

Coal size is too large, causing plugging of chutes, troughs, trippers, or gates.

Check operability of crushing equipment.

Slide gates are plugged, closed, or fouled.

Open slide gates and clear any blockage.

Conveyor belt is torn or misaligned, causing coal to drop from the belt. b elt.

Repair belt and realign.

Tripper devices are inadvertently diverting coal.

Adjust tripper device as needed.

Conveyor belt speed is too slow.

Check gearboxes and couplings to ensure that drive mechanisms are providing the appropriate torque and motor force to the conveying system.

Coal size inadequate

Crushing equipment is not functioning properly.


Coal contaminated with foreign material

Magnetic separator is not functioning properly.

Check operability of magnetic separator.

Crushing equipment is not functioning properly.


6-4


6.2

Troubleshooting Troubleshooting Components Installed in Coal Handling/Conveying Handling/Conveying Systems

Sections 6.2.1 through 6.2.14 summarize troubleshooting guidance for the various components comprising a coal handling/conveying system. Each table and accompanying text lists the component type, its failure mechanisms, the causes for failure, and frequently used solutions to restore the system to an operational state.

6.2.1 Belt Scales Table 6-2 Recommended Troubleshooting for Coal Handling System Belt Scales Failure Mechanism(s)

Cause(s)


Calibration shifts: frequent calibration shifts should be isolated to zero shifts or span shifts. Zero calibration shifts: zero shifts are normally associated with the conveying system. When a zero shift occurs, the span will shift by a like number of tons per hour; this then appears as a span shift.

Material buildup on the carriage/weighbridge Rocks lodged in the carriage/weighbridge Conveyor belt tracking Nonuniform conveyor training Conveyor belt belting stretch due to material temperature variations Trouble in the electronic measuring components Severely overloaded load cell

Span calibration shifts: span shifts are normally associated with the electronic measuring of components of the system, with one exception—conveyor belt tension. A span shift is present if both points change by the same percentage tons per hour.

Change in conveyor belting tension Speed sensor roll buildup and/or slipping Conveyor scale alignment Severely overloaded load cell Trouble in electronic measuring components

6-5


Table 6-2 (continued) (continued) Recommended Troubleshooting for Coal Handling System Belt Scales Failure Mechanism(s) Loss of circuit integrity

Cause(s) Short or open circuit of field wiring Faulty field wiring and loose connections

Frequently Used Solutions Solutions Check for proper interconnection between components of the system. All wiring must be as specified on the field wiring drawing. (see Note 1.) Check all wiring and connections for continuity, shorts, and grounds using an ohmmeter. Loose connections, poor solder joints, shorted or broken wires, wires, and unspecified grounds in wiring will cause erratic readings and shifts in weight readings. Check that grounding of all cable shields is made at only the locations specified on the field wiring drawing. Check load cells by resistance and millivolts. (see Notes 2 and 3.)

1.

Caution: Caution: do not use a megger for checking field wiring.

2.

Load cell check by resistance (manufacturer should use precision strain gauge load cells with 3 mV/volt sensitivity). sensitivity). To verify its operation, use the following procedure:

3.

6-6

a)

Disconnect load cell wires from field terminals in exciter digitizer.

b)

Using ohmmeter, check resistance between signal wires. Resistance should be 350 ohms ±5 ohms.

c)

Using ohmmeter, check resistance between excitation wires. Resistance should be 400 ohms ±10%.

d)

Check continuity between shield and all wires. All leads should be open (infinite) from shield.

Load cell check by millivolt. Verify load cell operation by using a dc voltmeter capable of reading millivolts and using the following procedure: a)

Complete resistance check.

b)

Reconnect all four excitation wires. Do not reconnect red and white signal wires.

c)

Measure excitation voltage across excitation wires. Voltage should be 10 volts direct current (Vdc) ±5%.

d)

Measure signal voltage across signal positive and signal negative on each load cell. Reading must be within 0–30 millivolts direct current (mVdc).

e)

The millivolt output is a direct relationship to weight applied. As weight is increased, output should increase.

f)

When the weighbridge is properly balanced, the output from each load cell should be the same within 1.0 mVdc.

g)

If a zero shift is suspected, reinstall the shipping locks and measure all load cell outputs. A normal reading is 0 mVdc. A slight positive shift of 0.1 or 0.2 mVdc is acceptable, but a negative shift would indicate a failure.


6.2.2 Unloading Equipment Because of the size, complexity, and uniqueness of coal-unloading equipment, most manufacturers provide troubleshooting information on an equipment-specific basis and not in a generic context that would be appropriate for inclusion in this technical report. Most major manufacturers include some degree of troubleshooting information in each equipment’s operations manual that is typically provided to each owner when the equipment is delivered onsite and installed. As such, the users of this report should refer to their operations/maintenance manual to obtain troubleshooting guidance specific to the type, size, make, and model of equipment installed at their site.

6.2.3 Unloading Hoppers Because there are typically no moving parts on an unloading hopper, there are no troubleshooting procedures included in this report. Failures of the hopper to properly discharge coal without coring, bridging, or rat-holing are most often attributable to the hopper design.


6.2.4.1

Common Problems

6.2.4.1.1

Sample Cutter in Material Stream Key Technical Point

The most critical failure in a sampling system occurs when a sample cutter stops in the stream of material. If a primary sample cutter were to become stuck in the stream of material on a conveyor belt, be lt, it is possible that hundreds of pounds of material could be displaced each second. This makes it imperative that these types of failures be identified immediately.

Every sampler has a mechanism to determine when the cutter is in the home position. Failure timers are included in the automatic control system. When the control system initiates a sampling operation, the failure timer for the sampler will begin counting down. If the sampler does not return to the home position before the timer ends, the system will go into alarm mode and shut down. If it is a primary sampler that fails, a signal is sent to the main control system for the plant to shut down the affected conveyor. It is extremely important that only qualified people make adjustments to failure timers. Improperly adjusted failure timers could cause equipment failure or damage. If a cutter is stopped in a material stream, it is important that the situation be rectified before starting any equipment feeding the sampler. Failure to do so could result in additional equipment damage. 6-7


6.2.4.1.2

Plugged Chutes

Plugged chutes can occur for a variety of reasons. Oversized material or foreign objects could get into the sampling system, blocking chutes. Excessively wet material can stick to the sides of chutes and buildup. As the material builds up on the side of the chute, it reduces the opening in the chute until the opening becomes completely blocked. Material fines can also build up on the sides of chutes over time and block the chute. Sampling systems have multiple plugged chute detectors located in different areas. When one of these sensors is tripped, the system PLC will shut down all equipment upstream of the plugged chute and display an alarm condition. Plugged chutes could also cause alarms in other equipment. If a chute without a plugged chute detector becomes blocked, material will build up above the blockage until it reaches the piece of equipment above it. When the plug reaches that far, it can cause the equipment to stall out, tripping the sampling system alarm. 6.2.4.1.3

Equipment Not Running

The most obvious problem that can occur with a sampling system is when equipment simply does not run when it is supposed to. There are many reasons this could occur: •

Failure of timers

•

Mechanical failure

•

Tripped circuit breaker

•

Overheated motors

•

Tripped safety switches

•

Loose wires

•

Downstream failures

All possibilities should be investigated when determining the cause of equipment non-operation. Thorough inspections of the equipment should be made before restarting equipment. Often, one type of failure will lead to another. For example, a mechanical failure could cause the circuit breaker for the motor to trip. If the breaker is simply reset and the equipment restarted, the original mechanical failure could cause additional damage. 6.2.4.1.4

Zero-Speed Sensors Activate

Sample feeders and conveyors typically have a zero-speed sensor to indicate a mechanical problem. Sometimes, though, the zero-speed sensor itself can fail. A feeder with a failed zerospeed sensor will run in manual mode. However, when the system is started in automatic mode, the feeder will shut down after a few seconds after the failure timer times out. 6-8


If the zero-speed sensor is a non-contact style with a proximity probe, it is possible that the sensor is out of adjustment. Otherwise, the sensor could be faulty. If a faulty zero-speed sensor is found, the zero-speed sensor can be temporarily disabled in the control system by connecting a jumper across across the appropriate appropriate terminals terminals in the control control panel. panel. See the wiring wiring diagrams diagrams for the control system for the correct terminals. If it is necessary to disable a faulty zero-speed sensor, the sensor should be replaced as soon as possible. While the sensor is disabled, the control system might not be able to tell if the equipment stops running. 6.2.4.1.5

Sample Collector Full

The sampling system PLC will shut down the sampling system and display an alarm whenever it determines that all of the containers in a sample collector are full. Although this is not considered a failure, it can often look like one initially because the system will shut down and display an alarm similar to a failure. For this reason, it is important to empty the sample containers and reset the system properly before all the containers become full. Remember to check the sample collector when an alarm is displayed and no other cause is apparent.

6.2.4.2

Determining the Location of Problems

In automatic mode, the sampling system PLC starts up the equipment in a sequential order. The reject is always the first piece of equipment to start up, followed by the equipment feeding the reject. The equipment continues to start up sequentially until the primary sampler is enabled. The startup sequence for most sampling systems is: 1. Reject conveyor 2. Tertiary sampler 3. Tertiary feeder 4. Crusher 5. Secondary feeder 6. Secondary sampler 7. Sample transfer conveyor 8. Size sampler 9. Primary feeder 10. Primary sampler In order for a piece of equipment to run in automatic mode, the sampling system needs confirmation that the downstream equipment is functioning. For example, the system PLC needs to have a signal that says the reject conveyor is running in order for the tertiary sampler to run. The tertiary sampler needs to be running in order for the tertiary feeder to function. 6-9


When an alarm is present, all equipment upstream from the alarm is shut down while the system is in automatic mode. So, if the crusher fails or if the plugged chute switch above the crusher is tripped, everything between the crusher and the primary sampler will be disabled. If the reject conveyor fails, the entire system will be disabled. By paying close attention to which equipment is still running, it can be determined where to focus troubleshooting efforts when responding to alarms.

6.2.4.3

Using the Operator Interface to Locate Problems

The operator interface has many tools to help locate problems with the sampling system. When responding to a sampling system alarm, it is best to always look at the operator interface first. When an alarm condition happens, the sampling system sends only a single alarm to the plant PLC. However, the operator interface displays information that is much more detailed. A quick investigation of the operator interface can allow the user to quickly identify the type or location of the problem, thereby saving time when responding to an alarm. There are many different alarms that the control system can display. These include alarms for safety pull switches, plugged chute sensors, or zero-speed sensors. If possible, the operator interface will display what the alarm is and which piece of equipment the alarm belongs to. Looking for the alarm messages on the operator interface can direct troubleshooting efforts and find problems much more quickly than walking through the entire sampling system. Another method of using the operator interface to locate problems is to look at which pieces of equipment are still running. As discussed earlier, the equipment will only run in a sequential manner while the system is in automatic mode. The operator interface provides information on which pieces of equipment are running and which are stopped. By observing on the operator interface which equipment is still running, the problem area can be isolated.

6.2.4.4

Resolving Problems

In order to ensure the best possible service from the sampling system, these instructions should be followed whenever a system alarm has been activated. It is important to determine a cause for an alarm before pushing the alarm reset button. •

Investigate the operator interface for alarm messages.

•

Determine the approximate location of the problem.

•

Inspect the affected equipment for damage or mechanical problems.

•

Look inside the access panels for material plugs.

6-10

Coal Handling System/Component Troubleshooting •

•

If a cause for an alarm is found, turn the system off or to manual operation and take appropriate action to fix the problem. If no plugs or equipment failures are present, push the alarm reset button to clear the alarm and allow the sampler to start sampling in automatic mode. Observe the equipment closely for problems.

To avoid making a problem worse, it is important to determine if there are problems before pushing the alarm reset button.

6.2.5 Coal Crushers Because of the size, complexity, and uniqueness of coal-crushing equipment, most manufacturers provide troubleshooting information on an equipment-specific basis and not in a generic context that would be appropriate for inclusion in this technical report. Most major manufacturers include some degree of troubleshooting information in each equipment’s operations manual that is typically provided to each owner when the equipment is delivered on-site and installed. Thus, the users of this report should refer to their operations/maintenance manual for obtaining troubleshooting guidance specific to the type, size, make, and model of equipment installed at their site.

6.2.6 Reclaim Hoppers Table 6-3 summarizes troubleshooting guidance for vibratory, drawdown types of reclaim hoppers. Most vibratory drawdown hoppers are designed to operate at a low noise level if properly maintained. Should a malfunction occur, the following troubleshooting guidance lists possible causes and remedies.

6-11


Table 6-3 Recommended Troubleshooting for Vibratory Drawdown Reclaim Hoppers Courtesy of Carman Industries, Inc. Failure Mechanism(s) Motor does not run

Cause(s)


Low motor voltage

Ensure that nameplate voltage is maintained.

Open circuit

Check control fuses, overload relays, and so on.

Broken lead

Inspect leads in conduit box, ensuring that they are properly packed with the manufacturer’s recommended sealant.

One phase open

Locate fault with testing device and repair.

Bearing failure

Replace bearing.

Motor runs, then stalls

Power failure

Check for loose connections in control and/or conduit box.

Motor does not reach speed

Open circuit

Locate fault with testing device and repair.

V-belt failure or slippage

Belt loose

Adjust belt tension.

Unusual drive belt wear

Belt loose

Adjust belt tension.

Pulley misaligned

Check all pulley alignment and realign.

Over-lubricated

Replace bearing and lubricate in accordance with the manufacturer’s recommendations.

Under-lubricated

Replace bearing and lubricate in accordance with the manufacturer’s recommendations.

Wrong grease

Lubricate in accordance with the manufacturer’s recommendations.

Contaminated grease

Keep drive area clean. Lubricate in accordance with the manufacturer’s recommendations.

Bearing failure

6.2.7 Discharge Hopper Feeders Tables 6-4 and 6-5 summarize troubleshooting guidance for discharge hopper feeders. Most vibratory feeders are designed to operate at a low noise level if properly maintained. Should a malfunction occur, the following troubleshooting guidance lists possible causes and remedies.

6-12


Table 6-4 Recommended Troubleshooting for Para-Mount Discharge Hopper Feeders Courtesy of General Kinematics Corporation Failure Mechanism(s) Stroke or capacity increase

Stroke or capacity decrease

Excessive noise

Spring failure

Material conveying to one side

Cause(s)


Rubber shear mount worn.

Replace rubber shear mount.

Improper rubber shear mount compression.

Refer to manufacturer’s guidance for setting and/or replacement.

Material buildup.

Clean trough.

Additional trough weight.

Contact the manufacturer for guidance.

Material buildup.

Clean trough.

Trough is hitting stationary equipment.

Check clearance on general arrangement drawing.

Counterweight wheel is worn or physically degraded.

Replace wheels; check air and hydraulic fluid flow.

Loose bolts.

Tighten to proper torque.

Broken or loose bolts/spring.

Replace broken spring.

Rocker leg loose or broken.

Replace rocker leg; tighten bolts to proper torque.

Hitting stationary skirt.

Adjust to provide necessary clearance.

Weld breakage.

Contact the manufacturer for repair guidance.

Material buildup.

Clean trough.

Pipe spacer continues to rattle after security lock nuts are tightened.

Replace through-rod, pipe spacer, hardened steel washers, and security lock nuts.

Loose bolts.

Tighten bolts to proper torque.

Fatigue.

Replace spring.

Material buildup.

Clean trough.

Loose bolts.


Isolation spring broken.

Replace isolation spring.

Eye bolt or cable broken.

Replace eye bolt or broken cable.

Material loaded to one side of feeder.

Correct loading path and orientation.

6-13


Table 6-4 (continued) (continued) Recommended Troubleshooting for Para-Mount Discharge Hopper Feeders Courtesy of General Kinematics Corporation Failure Mechanism(s) Material not conveying or low capacity

Motor failure

Cause(s)


Obstruction in trough.

Remove obstruction and clean trough.

Gate closed.

Open the gate.


Replace wheels; check air and hydraulic fluid flow.

Insufficient pressure for adjustable feeder.

Check air supply and air lines.

Improper voltage.

Check general arrangement drawing for proper voltage and circuit routing.

Disconnect or starter malfunction.

Reset and check overload heater size.

Single phasing.

Check cable, wire lead, and cable connection.

Table 6-5 Recommended Troubleshooting for Para-Mount II Discharge Hopper Feeders Courtesy of General Kinematics Corporation Failure Mechanism(s) Stroke or capacity increase

Stroke or capacity decrease

Excessive noise

6-14

Cause(s)

Frequently Used Solutions

Reactor spring loose.


Reactor spring breakage.

Replace spring.

Material buildup.

Clean trough.

Additional trough weight.

Contact the manufacturer for guidance.

Material buildup.

Clean trough.

Trough is hitting stationary equipment.

Check clearance on general arrangement drawing.


Replace wheels; check air and hydraulic flui d flow.

Loose bolts.

Tighten to proper torque.

Broken or loose spring.

Replace broken spring.

Rocker leg loose or broken.

Replace rocker leg; tighten bolts to proper torque.

Hitting stationary skirt.

Adjust to provide necessary clearance.

Weld breakage.

Contact the manufacturer for repair guidance.


Table 6-5 (continued) (continued) Recommended Troubleshooting for Para-Mount II Discharge Hopper Feeders Courtesy of General Kinematics Corporation Failure Mechanism(s) Rocker leg failure

Spring failure

Material conveying to one side

Material not conveying or low capacity

Motor failure

Cause(s)


Loose bolts.


Bushing failure.

Replace bushing.

Material buildup.

Clean trough.

Loose bolts.


Fatigue.

Replace spring.

Material buildup.

Clean trough.

Rocker leg failure.

Replace rocker leg.

Loose bolts.


Isolation spring broken.

Replace isolation spring.

Eye bolt or cable broken.

Replace eye bolt or broken cable.

Material loaded to one side of feeder.

Correct loading path and orientation.

Obstruction in trough.

Remove obstruction and clean trough.

Gate closed.

Open the gate.


Replace wheels; check air and hydraulic flui d flow.

Insufficient pressure for adjustable feeder.

Check air supply and air lines.

Improper voltage.

Check general arrangement drawing for proper voltage and circuit routing.

Disconnect or starter malfunction.

Reset and check overload heater size.

Single phasing.

Check cable, wire lead, and cable connection.

6-15


6.2.8 Magnetic Separators Table 6-6 summarizes troubleshooting guidance for magnetic separators. A qualified electrician should perform any procedure involving the electrical components of the magnetic separator system. Extreme caution should be used, as live electrical equipment will be tested. Before starting the manufacturer’s testing procedure, turn off and lock out any surrounding equipment that could pose a danger during testing. If the magnet is self-cleaning, turn off and lock out the power to the self-cleaning belt motor. Table 6-6 Recommended Troubleshooting for Coal Handling System Magnetic Separators Courtesy of Dings Company Magnetic Group Failure Mechanism(s) Belt not tracking

Belt does not move or magnet does not attract metal

Cause(s)


Bearing housings are not bolted down to frame tightly.

Tighten bearing housings to the frame in accordance with manufacturer’s recommended torque.

Bearings moved or shifted.

Adjust or replace bearings.

Top two idler pulleys and the drive pulley are no longer at right angles to the frame.

Adjust position of idler and drive pulleys so they are perpendicular to the frame.

Magnet self-cleaning frame is twisted or bent.

Straighten frame if possible. If not, consult manufacturer for possible means to replace bent frame sections.

Self-cleaning belt has been stretched so that one side is longer than the other.

Replace belt.

The ends of the belt have not been cut square to the edge of the belt prior to the splice being installed.

Re-cut ends of belt so splice is clean and perpendicular (if there is enough belt material available). If not, replace belt.

Blown fuse(s).

Visually inspect fuses and replace if needed.

Loose or broken wiring.

Secure all wiring. Mend broken wires as needed.

Internal rectifier components are worn or missing.

Repair internal rectifier in accordance with manufacturer’s recommended procedures.

Starter is inoperable.

Check all overloads (bimetallic components) to determine if any have tripped. Wait several minutes before restarting. Determine if correct heaters for selected voltage(s) are installed and that the load does not exceed nameplate rating.

6-16


Table 6-6 (continued) (continued) Recommended Troubleshooting for Coal Handling System Magnetic Separators Courtesy of Dings Company Magnetic Group Failure Mechanism(s) Rectifier Fails to Operate

Cause(s)


Blown fuse(s).

Visually inspect fuses and replace if needed.

Loose or broken wiring.

Secure all wiring. Mend broken wires as needed.

Internal rectifier components are worn or missing.

Repair internal rectifier in accordance with manufacturer’s recommended procedures.

Incorrect voltages at line connections and at secondary transformer.

Check for equal phase-to-phase voltages at line connections and at secondary transformer.

Loose, open, or shorted diodes.

Replace shorted diodes. Restore circuit integrity of loose diodes.

Starter is inoperable.

Check all overloads (bimetallic components) to determine if any have tripped. Wait several minutes before restarting. Determine if correct heaters for selected voltage(s) are installed and that the load does not exceed nameplate rating.

6-17


6.2.9 Slide Gates Table 6-7 summarizes troubleshooting guidance for slide gates most commonly installed in a coal handling system. Table 6-7 Recommended Troubleshooting for Slide Gates Courtesy of Salina Vortex Corporation Failure Mechanism(s) Compressed airoperated gate/diverter does not actuate or actuates slowly or erratically

Cause(s) Insufficient compressed air pressure and inadequate volumes of compressed air pressure are the most common causes of airoperated gates and diverters not functioning properly.

Frequently Used Solutions Solutions Check the air pressure at the gate/diverter. Gates/diverters require a minimum of 80 psig (551.6 kPa) to function properly. Demands for air by other air-operated equipment might be reducing air pressure and/or volume needed for the gate/diverter. Check the size of the compressed air lines. Compressed air lines that are too small significantly reduce the volume of compressed air to the gate/diverter’s air cylinder. Check the Cv factor of the air control assembly, particularly if the air control assembly was not supplied by the manufacturer. Air control assemblies with small Cv factors significantly reduce the volume of compressed air to the gate/diverter’s air cylinder. (See note.) Make sure that compressed air line connections are tight and air supply controls are fully open. Check compressed air lines for moisture. Moisture in compressed air lines can prevent proper function of air control assemblies or air cylinders. Check electrical power and control of air control assemblies.

6-18


Table 6-7 (continued) (continued) Recommended Troubleshooting for Slide Gates Courtesy of Salina Vortex Corporation Failure Mechanism(s)

Cause(s)


Compressed air supply checks out or electrically operated gates/diverters have power, but the gate/diverter fails to move or moves slowly or erratically

Flanges are are bent bent or deformed.

Make sure that the mating flanges to which the gate/diverter is attached are flat and true. Bent or untrue mating flanges can cause the gate/diverter to be in a bind.

Air cylinder is out of ali alignment. gnment.

Make sure that the air cylinder is aligned and supported (larger gates/diverters).

Weight above or below the gate/diverter is not properly supported.

Make sure that the weight above or below the gate/diverter is properly supported. Each gate/diverter has its own weight rating. As a general rule, no more than 200 lb (90.72 kg) should be supported or suspended from a gate/diverter.

Temperatures above the gate/diverter’s ratings can result in damage to the gate/diverter’s seals, causing failure to operate properly.

Adjust operating temperatures, if possible.

Material buildup on gate/diverter’s blade or seals can cause failure to operate properly.

Clear built-up material.

High moisture conditions or wet material can cause gate/diverter to operate improperly if seals are not rated for these conditions.

Adjust moisture conditions, if possible. Remove wet material from flow path.

Improper shimming can cause gate/diverter to operate improperly.

Adjust or replace shims.

Actuator is disconnected or inoperable.

Electrically actuate gate/diverter. Review installation and operating manual for proper electrical connections.

Note: C v factor is the number of U.S. gallons of water per minute that will pass through a valve with a pressure drop of one psi at 60oF (15.6oC).

6-19


6.2.10 Dust Control Systems Table 6-8 summarizes troubleshooting guidance for dust collection/suppression equipment installed in a typical coal handling system. Table 6-8 Recommended Troubleshooting for Dust Collection/Suppression Equipment Courtesy of Airtrol, Inc. Failure Mechanism(s) Excessive pressure drop

6-20

Cause(s)


Timer is not functioning properly.

Check air pressure in header (7–10 psig [48.3– 68.9 kPa]). Check if timer is functioning properly. Decrease off time to 3–4 seconds and repeat operations described under the manufacturer’s startup instructions.

Solenoids or diaphragm valves are not functioning properly.

Check solenoid and diaphragm valves to see that they are all operating properly.

Loose wiring.

Check for loose wiring and repair as needed.

Timer, blower, and cleaning manifold are not functioning as a unit.

Run timer, blower, and cleaning manifold with main fan off for 15–30 minutes.

Fan is not functioning without a dust load.

Start fan (with no dust load) and run for 15 minutes, observing pressure drop across bags.

Main air flow volume is inadequate.

Check main air flow volume with pitot tube or equivalent measuring equipment and compare with air volumes for which unit was originally designed.

Dust particle size is non-conforming to design criteria.

Check dust particle size and dust loading in air stream and compare to design specifications. Particle sizes below 10 μm have greatest effect on pressure drop.

Bags are too tight.

Check that bags aren’t skin-tight on cages. Bags must be free on cage for proper flexing.

Hopper is overloaded.

Check hopper for overload. Check dust discharge mechanism for proper operation and capacity. Correct if necessary. Do not use the hopper for material storage, unless system has been designed for this function.

Dust material is bridging across hopper.

Check for material bridging across hopper or sticking to hopper.

Hopper heater device is inoperable.

Ensure that heater in hopper enclosure is operating during cold weather.


Table 6-8 (continued) (continued) Recommended Troubleshooting for Dust Collection/Suppression Equipment Courtesy of Airtrol, Inc. Failure Mechanism(s) Extremely low pressure drop

Secondary dusting – primary dusting

Poor bag life

Cause(s)


Clogged or obstructed pressure gauge or manometer lines.

Clean out differential pressure gauge or manometer lines.

Bags are worn or have developed holes.

Check for holes in bags or worn bags and replace if necessary.

Bags are improperly installed.

Check to make sure that bags are installed properly (see bag installation for instructions).

Bags are excessively clean.

Check for excessive cleaning.

Bags are new and not properly dusted.

Allow unit to run 48–96 hours or longer after initial installation of bags before performing checks. This running time allows bags to reach their operating efficiency. Dusting might stop.

Bags are worn or have developed holes.

Check filter bags for holes and wear. Replace if necessary.

Bags are improperly installed.

Check for faulty bag installation.

Improper operating temperature.

Check operating temperature to see that it is within limits of the filter bag material.

pH of dust is non-conforming to original design criteria.

Check pH of dust to establish that proper filter bags are used for conditions.

Baghouse air-to-cloth ratio is nonconforming to design criteria.

Check baghouse air-to-cloth ratio vs. original specifications. Excessively high ratio will shorten bag life.

High moisture content.

Check for moisture and dew point in unit. High moisture will cause certain filter materials to shrink and shorten bag life.

Localized abrasion of bags.

If localized abrasion of bags is observed, an impingement baffle might be required.

Corrosion is occurring on cages.

Check for corrosion on cages. Rough surfaces will cause excess bag wear. Epoxy-coated or stainless cages will solve the problem.

6-21


Table 6-8 (continued) (continued) Recommended Troubleshooting for Dust Collection/Suppression Equipment Courtesy of Airtrol, Inc. Failure Mechanism(s) Fan capacity or pressure below rating

Cause(s)


Total system resistance is higher than design.

Increase fan speed. Consult the manufacturer before making any other system operating adjustments.

Speed is too low.

Check drive system.

Dampers or vanes are not properly adjusted.

Reset to correct position.

Poor fan inlet or outlet conditions.

Increase speed. Provide turning vanes or baffles in ductwork.

Air leaks in system.

Repair ductwork and wheel, then balance.

Damaged wheel.

Excessive vibration and noise

6-22

Rotation direction is incorrect.

Reverse electrical polarity to change direction of rotation.

Misalignment of drive belts, sheaves, or coupling.

Refer to the manufacturer’s recommended procedures to correct these deficiencies or nonconformances.

Unstable foundation. Foreign material in fan is causing unbalance.

Clean per manufacturer’s recommendations.

Worn bearings.

Replace bearings per manufacturer’s recommendations.

Damaged wheel or motor.

Replace or repair, and balance wheel.

Broken or loose bolts.

Tighten or replace bolts, as needed.

Bent shaft.

Replace shaft.

Worn coupling.

Replace coupling.

Fan wheel or drive is unbalanced.

Balance in place per manufacturer’s recommended procedure.

120-cycle magnetic hum due to electrical input.

Check input line for high or unbalanced voltage.

Fan delivers more than rated capacity.

Reduce speed; close dampers.

Loose dampers or vanes.

Tighten or replace, as needed.

Speed is too high or fan is rotating in the wrong direction.

Reduce speed, check electrical connections, and reinstall fan wheel.

Vibration transmitted to fan from other source.

Consider modifying installation and equipment arrangement.


Table 6-8 (continued) (continued) Recommended Troubleshooting for Dust Collection/Suppression Equipment Courtesy of Airtrol, Inc. Failure Mechanism(s) Overheated bearings

Cause(s)


Too much grease in bearings.

Clean and re-grease per manufacturer’s recommendations.

Poor alignment.

Realign bearings per manufacturer’s recommendations.

Bent shaft.

Replace with new shaft.

Dirt in bearings.

Clean and re-grease per manufacturer’s recommendations.

Excessive belt tension.

Realign and tension per manufacturer’s recommendations.

Speed is too high.

Recheck driver selection and size.

Volume flow rate is over capacity because system resistance is lower than design.

Consult manufacturer for input to design modification(s).

Driver is rotating in the wrong direction.

Reverse electrical polarity to change direction of rotation.

Motor vibration and noise

Armature is unbalanced.

Replace armature.

Loose hold-down bolts.

Tighten to manufacturer’s recommended torque values.

Motor laboring

Low or high voltage.

Check supply voltage and ensure that correct voltage is restored.

High temperature

Overloaded condition(s).

Clean dirt from windings.

Armature rubs against stator

Worn bearings.

Replace bearings as needed.

Low insulation resistance

Moisture.

Check resistance with megohm meter.

Overheated driver

6-23


6.2.11 Conveyor Belts, Pulleys, Idlers, and Rollers Table 6-9 summarizes troubleshooting guidance for conveyor belt systems. Table 6-9 Recommended Troubleshooting for Conveyor Belt Systems Courtesy of Georgia Duck-Enerka Failure Mechanism(s) Belt runs off at tail pulley

Belt runs to one side for long distance or entire length of conveyor

Particular section of belt runs to one side at all points on conveyor

6-24

Cause(s)


Belt running off-center around the tail pulley and through the loading area.

Install training idlers on the return run prior to tail pulley.

Material spillage and buildup: improve loading and transfer conditions.

Install cleaning devices; improve maintenance.

Idlers or pulleys out of square with centerline of belt: readjust idlers in affected area.

Readjust idlers in affected area.

Dirty, stuck, or misaligned return rolls: remove accumulations; install cleaning devices.

Use self-cleaning return rolls; improve maintenance and lubrication.

Counterweight is too light.

Add counterweight or increase screw takeup tension to value determined from calculations.

Belt is running off-center around the tail pulley and through the loading area.

Install training idlers on the return run prior to tail pulley.

Off-center loading or poor loading.

Adjust chute to place load on center of belt; discharge material in direction of belt travel at or near belt speed.

Buildup of material on idlers.

Remove accumulation; improve maintenance. Install scrapers or other cleaning devices.

Idlers or pulleys are out of square with centerline of belt.


Belt is not joined squarely.

Remove affected splice and re-splice.

Bowed belt.

For new belt, this condition should disappear during break-in; in rare instances, belt must be straightened or replaced. Check storage and handling of belt rolls.

Worn edge.

Press edge.


Table 6-9 (continued) (continued) Recommended Troubleshooting for Conveyor Belt Systems Courtesy of Georgia Duck-Enerka Failure Mechanism(s) Belt runs off at head pulley

Conveyor runs to one side at given point on structure

Belt runs true when empty, crooked when loaded

Belt slips

Cause(s)


Pulley lagging worn.

Replace pulley lagging.

Material spillage and buildup.

Improve loading and transfer conditions; install cleaning devices; improve maintenance.

Idlers or pulleys out of square with centerline of belt.


Idler stands not centered on belt.


Buildup of material on idlers.

Remove accumulation; improve maintenance. Install scrapers or other cleaning devices.

Sticking idlers.

Free idlers and improve maintenance and lubrication.

Idlers or pulleys out of square with centerline of belt.


Conveyor frame or structure is crooked.

Straighten in affected area.

Idler stands are not centered on belt.


Structure is not level.

Level structure in affected area.

Off-center loading or poor loading: adjust chute to place load on center of belt.

Discharge material in direction of belt travel at or near belt speed.

Variations in nature and formation of load.

Use notched chute to keep load peak in exact center of belt.

Belt is not making good contact with all idlers.

Adjust height so all idlers contact belt.

Insufficient traction between belt and pulley.

Lag drive pulley; increase belt wrap; install belt cleaning devices.

Pulley lagging is worn.






Sticking idlers.


Pulleys are too small.

Use larger diameter pulleys.

6-25


Table 6-9 (continued) (continued) Recommended Troubleshooting for Conveyor Belt Systems Courtesy of Georgia Duck-Enerka Failure Mechanism(s) Belt slips on starting

Excessive belt stretch

Grooving, gouging, or stripping of top cover

6-26

Cause(s)


Insufficient traction between belt and pulley.

Lag drive pulley; increase belt wrap; install belt cleaning devices.







Improper initial positioning of counterweight in its carriage, causing apparent excessive belt stretch.

Check with manufacturer for recommended initial position.

Insufficient counterweight travel.

Consult manufacturer for recommended minimum distances.

Tension too high: increase speed, same tonnage, same speed.

Reduce friction with better maintenance and replacement of damaged idlers; decrease tension by increasing arc of contact or go to lagged pulley; reduce counterweight to minimum amount.

System is underbelted.

Recalculate belt tensions and select proper belt.

Counterweight is too heavy.

Lighten counterweight to value required by calculations.

Improper belt installation is causing apparent excessive belt stretch.

Pull belt through counterweight with a tension equal to at least empty running tension; run belt in with mechanical fasteners.

Insufficient counterweight travel.

Consult manufacturer for recommended minimum distances.

Skirt boards are improperly adjusted or of wrong material.

Adjust skirt board supports to minimum 1 in. (2.5 cm) between metal and belt, with gap increasing in direction of belt travel; use skirt board rubber (not old belt).

Load jams in chute.

Redesign chute for proper angle and width.

Material hanging in or under chute: improve loading to reduce spillage; install baffles.

Widen chute.

Impact of material on belt.

Reduce impact by improving chute design; install impact idlers or impact bed.

Sharp edges of material or tramp iron coming in contact with cover.

Use jingle bars, impact idlers, or magnetic removal equipment.


Table 6-9 (continued) (continued) Recommended Troubleshooting for Conveyor Belt Systems Courtesy of Georgia Duck-Enerka Failure Mechanism(s) Excessive top cover wear, uniform around belt

Severe pulley cover wear

Cause(s)


Dirty, stuck, or misaligned return rolls.

Remove accumulations; install cleaning devices; use self-cleaning return rolls; improve maintenance and lubrication.

Cover quality is insufficient.

Replace with belt of heavier cover gauge or higher quality rubber or other elastomer.





Excessive sag between idlers causing load to work and shuffle on belt as it passes over idlers.

Increase tension, and if unnecessarily low, reduce idler spacing.

Sticking idlers.


Slippage on drive pulley.

Increase tension through screw takeup or add counterweight; lag drive pulley; increase arc of contact.



Material trapped between belt and pulley.

Install plows or scrapers on return run ahead of tail pulley.

Bolt heads protrude above lagging.

Tighten bolts; replace lagging; use vulcanizedon lagging.

Excessive forward tilt of trough rolls.

Reduce forward tilt of idlers to no more than 2° from vertical.

6-27


Table 6-9 (continued) (continued) Recommended Troubleshooting for Conveyor Belt Systems Courtesy of Georgia Duck-Enerka Failure Mechanism(s) Longitudinal grooving or cracking of bottom cover

Cause(s)


Sticking idlers.




Slippage on drive pulley.

Increase tension through screw takeup or add counterweight; lag drive pulley; increase arc of contact.



Excessive sag between idlers causes load to work and shuffle on belt as it passes over idlers.

Increase tension, and if unnecessarily low, reduce idler spacing.

Covers harden or crack

Heat or chemical damage.

Use belt designed for specific condition.

Improper storage or handling.

Refer to the manufacturer’s guidance for proper storage or handling instructions.

Cover swells in spots or streaks

Spilled oil or grease: overlubrication of idlers.

Improve housekeeping; reduce quantity of grease used; check grease seals.

Belt breaks at or behind fasteners; fasteners pull out

Fastener plates too long for pulley size.

Replace with smaller fasteners; increase pulley size.

Wrong type of fastener.

Fasteners too tight or too loose: use proper fastener and splice technique; set up schedule for regular fastener inspection.

Tension too high for fasteners.

Use vulcanized splice.

Pulleys too small.


Interference from belt scrapers.

Adjust belt scrapers.

Belt carcass is too light.

Select stronger carcass.

6-28


Table 6-9 (continued) (continued) Recommended Troubleshooting for Conveyor Belt Systems Courtesy of Georgia Duck-Enerka Failure Mechanism(s) Vulcanized splice separation

Excessive edge wear, broken edges

Transverse breaks at belt edge

Cause(s)


Belt is improperly spliced.

Re-splice using proper method as recommended by the manufacturer.



Tension is too high.

Increase speed, same tonnage, same speed; reduce friction with better maintenance and replacement of damaged idlers; decrease tension by increasing arc of contact or go to lagged pulley; reduce counterweight.



Improper transition between troughed belt and terminal pulleys.

Adjust transition in accordance with manufacturer’s catalog.





Belt hitting structure.

Install training idlers on carrying and return run.

Bowed belt.

For new belt, this condition should disappear during break-in; in rare instances, belt must be straightened or replaced. Check storage and handling of belt rolls.

Belt misalignment.

See training recommendations.

Belt improperly spliced.

Re-splice using proper method as recommended by the manufacturer.

Belt edges are folding up on structure.

Readjust idlers in affected area; straighten conveyor frame or structure in affected area; readjust idlers in affected area; install li mit switches; provide more clearance.



Severe convex (hump) vertical curve.

Decrease idler spacing in curve; increase curve radius.

6-29


Table 6-9 (continued) (continued) Recommended Troubleshooting for Conveyor Belt Systems Courtesy of Georgia Duck-Enerka Failure Mechanism(s)

Cause(s)


Short breaks in carcass parallel to belt edge; star breaks in carcass

Impact of material on belt.

Reduce impact by improving chute design; install impact idlers, or impact bed.



Ply separation

Insufficient transverse stiffness.

Replace with the proper belt.







Severe convex (hump) vertical curve.

Decrease idler spacing in curve; increase curve radius.

Excessive forward tilt of trough rolls.

Reduce forward tilt of idlers to no more than 2° from vertical.

Excess gap between idler rolls.

Replace idlers with heavier belt.

Insufficient transverse stiffness.

Replace with the proper belt.

Excessive sag between idlers causing load to work and shuffle on belt as it passes over idlers.

Increase tension if unnecessarily low; reduce idler spacing.

Cover cuts or very small cover punctures allow fines to work under cover and cut cover away from carcass.

Make spot repair with vulcanizer or self-curing repair material.

Spilled oil or grease.

Over-lubrication of idlers: improve housekeeping; reduce quantity of grease used; check grease seals.

Spilled oil or grease.

Over-lubrication of idlers: improve housekeeping; reduce quantity of grease used; check grease seals.



Carcass fatigue at idler junction

Cover blisters or sand blisters

Belt cupping on old belt that did not cup when new

6-30


6.2.12 Movable Tripper Devices Table 6-10 summarizes troubleshooting guidance for belt tripper devices. Table 6-10 Recommended Troubleshooting for Belt Trippers Courtesy of FMC Technologies, Inc. Failure Mechanism(s) Belt runs to one side

Cause(s) Left and right bearings need adjustment.

Frequently Used Solutions Solutions If belt runs to the right on top pulley, when facing in the direction of belt travel, move right bearing forward or left bearing slightly backward. If belt runs off to the right of lower pulley, move right bearing to the rear or left bearing slightly forward. If belt runs off to the left, reverse movement of the bearings.

6.2.13 Gearboxes Table 6-11 provides summary troubleshooting guidance for gearboxes. The table identifies a number of problems associated with degraded or abnormal gearbox operation and presents probable causes and suggested corrective actions. More detailed guidance is provided in the sections immediately following the table. Table 6-11 Troubleshooting Matrix for Gearboxes Courtesy of Lufkin, Inc. Problem/Symptom Problem/Symptom Abnormally high temperature

Possible Cause Oil level is too high.

Corrective Action Check sight gauge operation. Ensure proper drainage.

Housing is coated with foreign material, preventing heat dissipation.

Clean outside of housing.

High ambient temperature.

Provide adequate ventilation.

Lack of oil to bearings and/or mesh (indicated by low oil pressure).

Check lubrication system.

6-31


Table 6-11 (continued) (continued) Troubleshooting Matrix for Gearboxes Courtesy of Lufkin, Inc. Problem/Symptom Problem/Symptom Low oil pressure

Possible Cause

Corrective Action

Use of lubricant with lower viscosity than required.

Use correct viscosity lubricant.

Low lubricant viscosity from high lubricant temperature.

Take corrective actions as noted under Abnormally High Temperature.

Clogged oil filter.

Replace filter element.

Clogged air filter.

Clean or replace filter element.

Pump cavitation.

Maintain proper oil level in reservoir.

Air leak in suction line.

Check and tighten all pipe fittings.

Incorrect relief valve setting.

Set relief valve correctly.

Worn parts.

Pinpoint noise with mechanic’s stethoscope. Replace part.

Coupling misalignment.

Realign coupling.

Worn gearing.

Replace worn parts.

Transmission from other equipment.

Add sound blanket or enclosure.

Insufficient foundation rigidity or grout voids.

Reinforce or repair foundation.

Dynamic instability (critical speed).

Design to attenuate critical speeds in operating range.

Unbalanced parts.

Determine which parts require balancing and which have been balanced.

Loose foundation bolting.

Tighten bolting.

Excessive foaming

Air in oil.

Add anti-foaming agent.

No sensor readings

No power.

Check power supply and repair or restore.

Faulty gauge or recording device.

Test gauge or recording equipment.

Failed sensor.

Replace sensor.

Lead wire braid rubbed through (wire contacting metal).

Replace lead wire.

Unusual noise

Excessive noise

Excessive vibrations

6-32


6.2.13.1

Abnormally High Temperature

Oil level too high – If the oil level in a gearbox is so high that the gear runs in the oil, the resulting churning action will heat the oil. Check the sight gauge while the unit is running. A full gauge can indicate inadequate drainage. Coated housing – If the gear housing should get coated with a foreign material that will not permit natural heat removal by convection, high temperature can result. To prevent this, the unit should be cleaned periodically. Hot weather – Obviously, a high ambient temperature will cause abnormally high oil temperature. To prevent this, provide adequate ventilation around the gear. Low oil pressure – If the oil flow to the bearing and gear mesh is below normal (indicated by below-normal oil pressure), the heat created by friction at the mesh and bearings will cause abnormally high temperatures. To correct this situation, check the lubrication system for proper operation.

6.2.13.2

Low Oil Pressure

Use of a lubricant with inadequate viscosity – There are several orifices in the lubrication system that are sized for lubricants with a particular viscosity. A lubricant with less than this normal viscosity will pass through the orifices without building up pressure. This situation can be prevented by using the lubricant viscosity grade designated on the nameplate of the gear unit. Abnormally low viscosity can also result from high lubricant temperatures. Clogged oil filter – Replacing the filter will allow more oil to flow through it, thus bringing the oil pressure back to normal. Clogged air filter – Cleaning or replacing the filter will allow more air to flow through it, allowing the gearbox to equalize to atmospheric pressure. Pump cavitation – Should the oil level in the reservoir get so low that the pump suction line sucks both air and oil, the oil pressure will drop. This problem can be cured by maintaining proper oil level in the reservoir. Air leak in the suction line to the pump – This situation is similar to pump cavitation in that air gets in the oil and results in low oil pressure. To remedy this problem, check and tighten all pipe fittings in the suction line. Incorrect relief valve setting – Adjusting the relief valve setting will avoid venting the pump discharge line back to the sump.

6-33


6.2.13.3

Unusual or Excessive Noise

Worn parts – One common cause of unusual noise is worn parts. If a part wears enough to cause slack in the system, the slack might be heard as a rattle or noise of some sort. A mechanic’s stethoscope can be used to pinpoint the worn part, which should be replaced. Misalignment – A coupling that is out of alignment might also cause noisy operation. The misaligned coupling causes misalignment in the gear train, which then produces noise or vibrations. The coupling should be immediately realigned before damaging wear occurs. Transmitted sound – Occasionally, other machinery or equipment might be transmitting excessive noise. Enclose one or the other, or use a sound blanket.

6.2.13.4

Excessive Vibration

Soft foundation or grout voids – A foundation that is not sufficiently rigid can cause vibration problems. To correct this, reinforce the foundation. Critical speeds – At certain speeds, a rotating shaft will become dynamically unstable and the resulting vibrations and deflections that occur can cause damage to the gear unit. The speeds at which the shaft becomes unstable are called critical speeds. They are a function of the shaft geometry and the type and spacing of the supporting bearings. If such dynamic instability is suspected, the manufacturer should be contacted for consultation.

6.2.13.5

Foaming

Excessive foaming – Some foam in a gear unit is generally acceptable and inevitable. If the foam exceeds 2 or 3 in. (5.05 or 7.52 cm) in the sump, most manufacturers recommend adding an anti-foaming agent (such as Dow Corning 200 ® fluid, or equivalent) at approximately 0.075 ml per gallon (3.78 liters) of oil. If excessive foaming persists, the manufacturer should be contacted. Care should be taken when measuring the anti-foaming agent: too much anti-foam agent will stabilize the foam, destroy the load capacity of the oil, and require a complete oil change.

6.2.13.6

No Sensor Readings

Various sensing devices for temperature and vibration are typically installed to provide warnings that can prevent catastrophic failure. If no readings are being received, before disassembling the unit, check for the following: No power – Check that the power supply to the devices is on. Failed equipment – Check that the monitoring or recording equipment is functioning.

6-34


Worn wires – If the sensor has failed, partial disassembly might be needed to replace the sensor. Visual inspection of lead wire over-braids is necessary to ensure that moving parts are not rubbing through the lead wires and causing shorting out. Replace any worn wires.

6.2.14 Flexible Shaft Couplings The first step when troubleshooting a failure of a flexible shaft coupling is to determine if there is any variance from design parameters. Specifically, the licensee should determine if the coupling was used in an application suitable for its design, and whether it was exposed to different design parameters (such as torque, rotational velocity, and so on) or ambient conditions other than those specified to the manufacturer. The troubleshooting of flexible shaft couplings is somewhat unique in that unlike the machines to which they are attached, the machine most often must be shut down to make an in-depth analysis and troubleshoot the problem in detail. To troubleshoot couplings, the problems with the adjoining machines should be addressed first from a troubleshooting standpoint. The coupling is typically not the first component in the system to be investigated. In fact, it might be one of the last components evaluated when the system is not performing as designed, but should be part of the overall analysis. The next step is to determine if there have been any modifications (planned or inadvertent) to the rotational system. Tables 6-12, 6-13, and 6-14 provide troubleshooting guidance based on the type of coupling and each type’s inherent design characteristics.

6.2.14.1

Configuration of Rotational System

Table 6-12 provides a number of typical symptoms of premature wear and their causes that can lead to degraded performance of mechanical (gear and grid) couplings. Table 6-12 Detailed Troubleshooting Guidance for Flexible Mechanical (Gear and Grid) Couplings [2] Symptom Torsional or speed differentials across the coupling

Possible Causes of Problem Broken teeth

Recommended Actions Visually inspect the coupling. Replace the coupling if required.

Sheared key

Remove the coupling hubs and replace the key. Inspect shaft and coupling for damage. Replace coupling if damaged.

Broken bolts

Determine cause and replace bolts and/or coupling as required.

6-35


Table 6-12 (continued) (continued) Detailed Troubleshooting Guidance for Flexible Mechanical (Gear and Grid) Couplings [2] Symptom Excessive vibration measured at either machine

Possible Causes of Problem Excessive shaft misalignment

Recommended Actions Perform hot alignment (that is, running to cold shutdown). Implement alignment changes while at shutdown.

Pump or motor imbalance

Check balance of the motor or the pump.

Imbalance of the coupling

Monitor for imbalance location. Attempt to dynamically balance the coupling if coupling is found to be the problem. Check for dynamic balance spanning the adjoining machines.

Noise

Lack of lubrication

Visually inspect surfaces of adjoining equipment for signs of lubricant. Add lubricant if needed at shutdown.

Improper enclosure

Redesign configuration of the enclosure to reduce windage or install replacement.

Loose coupling fit on a shaft

Visually inspect with a strobe light to identify slippage or movement. Inspect shaft and coupling at shutdown. Replace or repair as necessary with coupling of proper fit.

Broken teeth

Visually inspect the coupling. Replace the coupling at shutdown.

Excessive shaft misalignment

Perform hot alignment (that is, running to cold shutdown). Implement alignment changes while at shutdown.


Visually inspect with a strobe light to identify if bolts or parts are missing and causing the imbalance. Monitor for imbalance location. Attempt to dynamically balance the coupling if possible. Check for dynamic balance spanning the adjoining machines.

6-36


Table 6-12 (continued) (continued) Detailed Troubleshooting Guidance for Flexible Mechanical (Gear and Grid) Couplings [2] Symptom Overheating

Possible Causes of Problem Excessive misalignment

Recommended Actions Perform hot alignment (that is, running to cold shutdown). Implement alignment changes while at shutdown.

Lack of lubrication

Visually inspect surfaces of adjoining equipment for signs of lubricant. Add lubricant if needed at shutdown.

Improper enclosure

Redesign configuration of the enclosure and install replacement.

Tooth wear

Visually inspect the coupling. Replace the coupling.

Leakage of lubricant

Excessive misalignment

Perform hot alignment (that is, running to cold shutdown). Implement alignment changes while at shutdown. Add lubricant.

Failed gaskets

Inspect gaskets and replace as needed. Replace lubricant. Torque bolts to design parameters.

Over/excessive lubrication

Check for overheating of the coupling due to inability to transfer heat. Visually inspect surfaces of adjoining equipment for signs of lubricant. Add lubricant if needed.

Improper lubricant

Determine suitability of the lubricant that is installed through analysis. Replace if it is unsuitable.

6-37


Table 6-13 provides a number of typical symptoms of premature wear and their causes that can lead to degraded performance of metallic (disk and diaphragm) couplings. Table 6-13 Detailed Troubleshooting Guidance for Flexible Metallic (Disk and Diaphragm) and Elastomeric Couplings Couplings [2] Symptom Torsional or speed differentials across the coupling

Possible Causes of Problem

Recommended Actions

Sheared key

Remove the coupling hubs and replace the key. Replace coupling if damaged.

Fractured diaphragm or disk

Remove the coupling hubs and replace the disk. Install new diaphragm coupling.

Shear of elastomeric elements

Separate the hubs and install a new element.

Broken bolts

Determine cause and replace bolts and/or coupling as required.



Excessive vibration measured at either machine

6-38



Pump or motor imbalance

Check balance of the motor or the pump.


Visually inspect with a strobe light to identify any missing or broken parts that cause the imbalance. Attempt to dynamically balance the coupling if possible. Check for dynamic balance spanning the adjoining machines.


Table 6-13 (continued) (continued) Detailed Troubleshooting Guidance for Flexible Metallic (Disk and Diaphragm) and Elastomeric Couplings Couplings [2] Symptom Noise

Possible Causes of Problem

Recommended Actions

Broken diaphragm or disk

Remove the coupling and replace the diaphragm or disk pack. Replace the diaphragm coupling.

Broken elastomeric element

Separate the hubs and install a new element.

Improper enclosure


Loose coupling fit on a shaft

Visually inspect with a strobe light to identify looseness. Inspect shaft for damage. Replace the coupling with correct item.



Overheating


Visually inspect with a strobe light to identify any missing or broken parts that cause the imbalance. Attempt to dynamically balance the coupling if possible. Check for dynamic balance spanning the adjoining machines.



Improper enclosure


Fretting or fatigue of the flex elements (for example, metallic disks or elastomers)

Remove the coupling hubs and replace the disk pack or elastomeric flex element. el ement.

6-39


6.2.14.2

Material Incompatibility Incompatibilit y and Misapplication

Table 6-14 illustrates various failure mechanisms and metallurgical problems common to flexible shaft couplings. The table should assist in troubleshooting the cause of metallurgical failure and offers proposed solutions. Table 6-14 Common Metallurgical Problems and Troubleshooting [2] Failure Mechanisms Fatigue failure of coupling elements (such as disks, teeth, keys, elastomers, and housings)

Cause Lack of lubrication (gear or grid coupling)

Frequently Used Solutions Solutions Visually inspect surfaces of adjoining equipment for signs of lubricant. Visually inspect lubrication levels. Add lubricant if needed.


Perform hot alignment (that is, running to cold shutdown). Implement alignment changes while at shutdown. Add lubricant.

Corrosive atmosphere (for example, exposure to moisture, oils, chemicals, particulates, and so on)

Eliminate the source of the corrosive particulates. Inspect and reconfigure the coupling guard or enclosure where corrosive liquid or particulates can enter. Isolate the corrosive liquid or particulates from affecting the coupling.

Unsuitable material

6-40

Analyze the design. Consult manufacturer for recommended alternative materials.


6.2.14.3

Installation Practices

Premature failure of couplings can be a result of improper installation practices. Table 6-15 provides a checklist that can be used to determine possible causes for the failure of the coupling. Table 6-15 Installation Practices Leading to Flexible Shaft Coupling Failure [2] Improperly locating the hub onto the shaft Installing an improperly sized coupling given the established distance between shaft ends Installing a properly sized coupling between shafts that are not at the prescribed end distance Attempting to install a coupling without the necessary fit or clearance between the coupling and the shaft Installing couplings with keys that are too tight Installing a coupling into a system that exhibits more misalignment than the coupling is designed to accommodate Improperly setting shaft spacing for motors with sleeve bearings Failing to use the appropriate lubricant and/or failing to apply the correct amount of lubricant Over or under torque of bolts used to secure the coupling components Improper machining of the bore (usually performed in the field) immediately prior to installation of the coupling (that is, coupling run-out)

6-41

7

PERSONNEL QUALIFICATION, TRAINING, AND SAFETY ISSUES

7.1

Personnel Qualification and Training

The purpose of this section is to provide guidance regarding typical qualifications for personnel associated with the operation and maintenance of coal handling conveying systems. Care should be taken not to interpret these as minimum requirements for qualification or certification purposes, but rather as a benchmark for use within each owner’s plant-specific program.

7.1.1 Coal Handling System Operators Table 7-1 describes typical expertise and experience levels for a coal handling system operator. Table 7-1 Typical Expertise and Experience Level: Coal Handling System Operators Entry level with minimal or no experience as a fossil power plant system operator op erator and: and: Completion of applicable apprenticeship program or five years o f applicable trade experience, and a high school diploma or equivalent; or Two years’ experience in fossil power plant maintenance, engineering, or operations, with an associate’s degree in engineering or related physical science; or One year’s experience in fossil power plant maintenance, engineering, or operations, with a BS in engineering or related physical science. (See note to Table 7-2.)

7.1.2 First-Line Supervisors Table 7-2 describes typical expertise and experience levels for a first-line supervisor of a coal handling system.

7-1

Personnel Qualification, Training, and Safety Issues

Table 7-2 Typical Expertise and Experience Level: First-Line Supervisors Five years’ experience in maintenance, engineering, o r fossil power plant operations, with an associate’s degree in engineering or related physical science; or Two years’ experience in maintenance, engineering, or fossil power plant operations, with a BS in engineering or related physical science. (See no te.) Note: Individuals with BS degrees who are working in this context might be doing so only for a limited time in order to gain supervisory experience, a necessary qualification for higher level management.

7.1.3 Coal Handling System Maintenance Personnel Table 7-3 describes typical expertise and experience levels for coal handling system maintenance personnel. Table 7-3 Typical Expertise and Experience Level: First-Line System Maintenance Personnel Entry level with minimal or no experience performing fossil power plant system maintenance and: and: Completion of applicable apprenticeship program or five years’ applicable fossil power plant maintenance experience, and a high school diploma or equivalent; or Two years’ experience in fossil power plant maintenance or engineering, or an associate’s degree in engineering or related physical science; or One year’s experience in fossil power plant maintenance, engineering, or operations, with a BS in engineering or related physical science.

7.2

Personnel Safety Issues

Safety is a basic factor that must be considered at all times during the installation, operation, and maintenance of mechanical equipment. Through the use of proper tools, clothing, and procedures, serious injury and property damage can be prevented. Any accident, regardless of the situation, is generally the result of someone’s carelessness or neglect. No amount of training or instruction can replace common sense, sound judgment, and acceptable work practices. In this section, a few general safety precautions are listed for each major type of equipment described in this report. The following general safety guidance should be followed when performing preventive or corrective maintenance on each of the following general types of equipment that are integral to the coal handling system.

7-2


7.2.1 Belt Scales For belt scales, observe the following safety precautions: •

•

•

•

Do not use the equipment for any use other than that for which it is intended. Never operate the equipment without all required safety devices in position and operable. Any caution or warning stickers affixed to the equipment should always remain in plain view of operating and maintenance personnel. Never walk, sit, or lean on or under the idlers or any portion of the equipment while the unit is in operation or is not in the zero-mechanical state. Never place hands or feet in any rotating elements until the equipment has completely come to rest and electric power has been locked out.

7.2.2 Unloading Equipment For unloading equipment, observe the following safety precautions: •

•

•

Never operate the equipment without all required safety devices in position and operable. Any caution or warning stickers affixed to the equipment should always remain in plain view of operating and maintenance personnel. Personnel should remain clear of unloading area at all times when the coal is being unloaded and the equipment is in operation.

7.2.3 Unloading Hoppers For unloading hoppers, observe the following safety precautions: •

•

•

•

Personnel should remain clear of hopper discharge area at all times. Always provide the necessary protective clothing, eye protection, and headgear for operating personnel. To avoid inadvertent discharge of coal and entry into the hopper bin, personnel should never enter into the hopper unless the unloading equipment is completely locked out or removed from the vicinity of the hopper. Never place hands in hopper discharge opening(s) until the equipment has completely come to rest and electric power has been locked out.

7.2.4 Sampling Equipment Safety precautions noted for crushers and conveying equipment should be referenced because these types of equipment are integral to coal sampling systems discussed in this report.

7-3


7.2.5 Coal Crushers For coal crushers, observe the following safety precautions: •

•

•

•

•

•

•

•

Cylinders installed on crushing equipment must be restrained from rotating when personnel are working on the unit. A rotating cylinder can cause serious injury. Care should be taken when removing the cage bolts because the cage will be entirely supported by the lifting device the moment the cage breaks free from the hub. Never adjust a cage unless the rotor rotation is toward the cage to be adjusted. Never operate the equipment without all required safety devices in position and operable. Any caution or warning stickers affixed to the equipment should always remain in plain view of operating and maintenance personnel. Never walk, sit, or lean on or under the troughs, covers, grid section, or any portion of the equipment while the unit is in operation or is not in the zero-mechanical state. Never place hands or feet in any equipment openings until the equipment has completely come to rest and electric power has been locked out. When lifting a rod, it is possible that the pocket might open from its own weight, causing the rod to thrust outward from the frame. For this reason, it is best to stand to one side when opening the pocket. Ensure that any debris (sometimes uncrushed coal) is removed prior to equipment startup.

7.2.6 Reclaim Hoppers For reclaim hoppers, observe the following safety precautions: •

•

•

Do not attempt to grease, adjust, repair, or perform any work on the hoppers while equipment is in operation. Keep all guards in place. Do not remove any guards for access to the drive assembly until the equipment has been locked out electrically for service. Replace all guards before the equipment is placed into operation. Personnel should stand clear of the hopper opening at all times to avoid inadvertent falling or personal injury.

7.2.7 Discharge Hopper Feeders For discharge hopper feeders, observe the following safety precautions: •

•

7-4

Do not use the equipment for any use other than that for which it is intended. Do not operate vibratory equipment until the unit is properly installed. Also before operating the equipment, ensure that the path of material flow is clear of any obstructions, all operating personnel are standing clear of the equipment, all shipping braces have been removed, the equipment has been fully checked for loose bolts, and so on.

Personnel Qualification, Training, and Safety Issues •

•

•

•

•

•

•

•

•

Never operate the equipment without all required safety devices in position and operable. Any caution or warning stickers affixed to the equipment should always remain in plain view of operating and maintenance personnel. Never walk, sit, or lean on or under the troughs, covers, grid section, or any portion of the equipment while the unit is in operation or is not in the zero-mechanical state. Never place hands or feet in any equipment openings until the equipment has completely come to rest and electric power has been locked out. Before performing any maintenance, ensure that the unit is in the zero-mechanical state (that is, all power to the complete system is turned off and locked out, pneumatic/hydraulic lines are relieved of all pressure, all safety stops are in position, and so on). Always provide the necessary protective clothing for operating personnel if the conveying material has a tendency to splash out of the unit’s trough. Always have a clear view of the material loading and unloading points on the equipment as well as immediate access to all emergency stop and safety devices for the equipment. Do not allow the accumulation of rubbish, tools, discarded parts, or any other material to clutter the path of material flow. Keep the area around and under the equipment free of spilled material and debris. Always regularly check for any signs of corrosion or excessive wear on the wire rope and safety cables, which are required on all suspension-mounted units. All cable clips should be regularly checked for tightness to prevent slippage. Always make periodic checks of all electric motor cables for wear or damage. All ground wires should be securely and properly fastened.

7.2.8 Magnetic Separators The following safety precautions should be considered during maintenance and operation activities associated with a magnetic separator in a coal handling system: •

•

•

•

With the exception of taking some electrical readings, which require the magnet to be energized, all routine maintenance should be performed with the magnet de-energized and the drive motor off and locked out so it cannot be accidentally started. The surface of the magnet can reach temperatures of up to 230°F (110°C) while operating. If the magnet has been on for a long time, it should be allowed to cool down, which can take several hours. When electrical power remains on, care should be taken to ensure that no magnetic objects are placed near the separator or between the separator and the operator. Hands, arms, and tools should remain clear of belt and pulley mechanisms.

7-5


•

•

•

The magnetic separator emits a powerful magnetic field when energized. Persons with pacemakers should exercise extreme care when in the vicinity of the magnetic separator, and should guard against entry into the electromagnetic field. Care should be taken to ensure that all support slings, connectors, turnbuckles, and other lifting/rigging hardware are rated for the weight of the magnetic separator. Each leg of the suspension sling should be able to support the full weight of the separator. Under no circumstances should personnel stand beneath the separator while it is in operation, during installation/removal, or during routine maintenance.

7.2.9 Slide Gates The following safety precautions should be considered prior to installation of a slide gate in a coal handling system: •

Slide gates and diverter valves contain moving parts, including sliding blades, that can cause severe injury and amputation.

•

Use extreme caution with these products.

•

Never place any body part in the path of the blade.

•

Never operate this product with the safety guards removed.

•

Do not energize this product until installation has been completed and all safety/precautionary steps have been taken.

The following safety precautions regarding hazard labels should be considered when operating or maintaining a slide gate: •

Do not install this product if hazard labels are not present.

•

Install this product in a manner that prominently displays the hazard label.

•

•

•

The hazard label must be readily visible to all who approach, and from any direction. If hazard labels are obscured due to equipment installation, contact the equipment manufacturer immediately to request additional hazard labels. If hazard labels become damaged or additional labels are required, contact the equipment manufacturer immediately. If the meaning of the hazard label is unclear, contact the equipment manufacturer immediately.

The following safety precautions should be considered regarding the weight of a typical slide gate installed in a coal handling system: •

•

7-6

Avoid supporting excess weight, or hanging excess weight, from slide gates. As a general rule, weights greater than 200 lb (91 kg) should not be supported or hung by a typical slide gate.


•

•

Refer to product specification sheets for specific weight restrictions. Large gates (12-in. [31-cm] and larger) or diverters (6-in. [15-cm] and larger) with air cylinders or electric actuators require support of the actuators to ensure proper blade alignment. Refer to product specification sheets for actuator support recommendations. Never

use a gate or its actuator as a step.

The following safety precautions should be considered when performing maintenance on bolted flange connections of a typical slide gate: •

•

Mating flanges must be straight, flat, and free of old sealing material. Both holes of mating flanges must match those of the gate/diverter. Use all bolt connections to ensure a proper seal and proper support.

•

Do not drill through a valve’s blind flange. The warranty will most likely be voided.

•

Use grade 5, or better, bolts and nuts with recommended flat and lock washers.

•

•

Do not over-tighten nuts on valves with protruding threaded studs. (Maximum torque is 7 ft [2.1 m].) Use soft, conforming gaskets to avoid gate/valve deflection.

The following safety precautions should be considered when performing maintenance on compression coupling connections of a typical slide gate: •

•

•

Support a horizontal conveying line on either side of the gate/diverter to prevent the gate/diverter from being placed in a bind. Avoid supporting or hanging excess weight (more than 200 lb [91 kg]) from the gate/diverter to prevent the gate/diverter from being placed in a bind. To prevent the gate/diverter from being placed in a bind, allow for expansion and contraction of conveying lines when placing a gate/diverter in the conveying line.

7.2.10 Dust Control Systems The primary safety concern with a dust control/collection/suppression system is the fans. Improperly installed or operated fans are a hazard to both people and property. Only trained and experienced personnel should install fans. Installations must meet all pertinent state and local safety codes and the requirements of the Occupational Safety and Health Act (OSHA). Each fan is designed to operate safely up to a stated maximum speed (rpm) and temperature. Do not exceed these limits . Fans are specialized equipment that involve high-speed rotating elements that can be dangerous if handled improperly. Individuals who are not familiar with the equipment and proper servicing methods might not realize the harm they can do to themselves or the fan and should never be permitted to work on the fan. Fans are sold with the understanding that customers will recognize the risk of high-speed rotating elements and understand that only people who are aware of the risks associated with the essential operating characteristics of a fan should be permitted to work on them. 7-7


The following safety guidance should be followed regarding the fans installed in a coal handling dust collection/suppression system: •

•

•

•

•

•

•

Flexible couplings and V-belt drives must have guards that completely encase the rotating parts. Do not start or operate the equipment without guards. Shaft guards should be provided for some fans (as recommended by the manufacturer). Guards should extend from one bearing to the other. Screens should be provided for open inlet fans and for outlets not connected to ductwork. Accessories with moving parts, such as tachometers, turning gears, and heat slingers, must have guards. Before startup, be sure that all parts are tight, that all tools and materials have been removed from the area, and that all personnel are cleared from the area. The periodic maintenance and lubrication procedures outlined in the manufacturer’s manual should be followed. A lock-out procedure to ensure that the fans cannot start when maintenance personnel are performing service functions is mandatory. It is customary to lock out the power from the drive and use red tags to alert personnel to the shutdown.

Only well-trained personnel should assemble, maintain, or replace the fans installed in the dust collection system. •

Never

allow an untrained person to work on the fan.

•

Never

remove warning labels nor this report from the fan.

•

Never

run the fan without all safety guards in place.

7.2.11 Conveyor Belts, Pulleys, Idlers, and Rollers Safe practices for operating belt conveyors are provided in American Society of Mechanical Engineers (ASME)/American National Standards Institute (ANSI) B20.1-2001 Safety Standard for Conveyors and Related Equipment [20]. Proper personnel safety equipment and clothing should be worn and only persons completely familiar with these standards should be permitted to operate or maintain this type of equipment. Failure to observe these safety precautions and other specific procedures emphasized throughout the manufacturer’s instructions can result in personnel injury or damage to equipment. •

•

7-8

Before installing any belt conveyor, idlers, or return rollers on an existing belt conveyor, ensure that the conveyor is stopped and locked out to avoid personal injury and property damage. Conveyor belts stopped with conveyed material on the belt might require substantial blocking to raise the belt line off the idler being installed.


•

•

•

•

•

Open conveyor frames without decking can present additional hazards to personnel safety when idler frames are being positioned or fastened in place. Exercise extreme care when placing and removing any temporary blocking, decking, or scaffolding that might be required. Remove any temporary blocking, decking, or temporary scaffolding before starting the belt conveyor. Extreme caution should be taken when clamp bolts need to be removed. Because the best results will be obtained if the idlers are lubricated while the conveyor is running, to avoid injury, personnel must wear suitable clothing and exercise care when wiping fittings and attaching a grease hose to fittings. Ensure that all safety switches are operational and can be manually activated by using the pull-cord provided by the manufacturer.

7.2.12 Movable Tripper Devices •

Do not use the equipment for any use other than that for which it is intended.

•

Always ensure that wheel guards are properly installed and secure.

•

Always keep hands, arms, and loose clothing away from rotating elements.

•

Do not operate the conveyor belt over the tripper unless the cable is attached and properly prepared to hold and control the traversing movement of the tripper between reversing limit switches.

7.2.13 Gearboxes •

Never remove the inspection cover while the machinery is in operation. Always lockout/tag-out all power sources while performing maintenance.

•

Never block the gear mesh by inserting material into the gear elements.

•

Shaft and coupling guards must be securely in place before operation.

•

Never work on machinery that is still in operation or is still moving.

•

Use of hearing protection should be considered when working near any noisy equipment.

•

Do not use the gearbox for any use other than that for which it is intended. Following are some possible misuses of gear units that might be encountered. Caution: To prevent injury/death of personnel and/or damage to equipment, the operator should avoid the following:

– Overloading the gear (increasing torque above nameplate data) – Running the gear above rated speeds – Reversing rotation 7-9


– Changing lubricant type or grade – Providing inadequate lubrication – Operating at temperatures above recommended levels – Operating with vibration above recommended levels – Misalignment of the unit 7.2.14 Flexible Shaft Couplings •

•

•

•

•

Ensure that equipment is tagged out or locked out prior to performing any maintenance on equipment. Care should be taken when making coupling changes on all machinery, but especially highenergy machines, such as steam generators or reactor feed pumps. Manufacturers should be consulted prior to making such changes. Placing a worn or damaged coupling back in service not only leaves one open for operational problems, but machine problems, and the potential for catastrophic damage or personal injury. Care must be taken to prevent contact with the hub, as contact will cause severe burns. A threaded rod inserted in the puller holes works well to handle heated components during installation. Ensure that hydraulic equipment is in good working order to preclude the danger of hydraulic hoses under high pressure separating and causing injury to personnel.

7-10

8 INDUSTRY RESOURCES FOR COAL HANDLING SYSTEM TRAINING, CONSULTING, AND REPAIR

The purpose of this section is to provide a listing of organizations capable of providing various services to utility personnel with respect to coal and coal handling. The information presented here was compiled through searches on the Internet and World Wide Web. Users of this report should recognize that the information provided in this section was current at the time of publication, and as such, might no longer be valid. Listing of these organizations does not imply any recommendation from EPRI FMAC regarding the applicability, accuracy, or competency of the organizations cited or the services they provide. Each user of this report should evaluate the current services provided by each organization listed to determine their applicability and suitability to plant-specific needs on a case-by-case basis. Training services – The organizations listed have capabilities to provide technical training to utility personnel in the areas of coal chemistry, conveyance, handling, disposal, transport, or usage in other industries. The types of training offered by each institution vary, and could include college-level classes, technical seminars, trade shows and exhibitions, and association technical meetings. Consulting services – Consulting services provided by the organizations listed might include design of coal handling/conveying systems and components and/or maintenance and operation of coal handling/conveying systems. Repair services – The organizations listed are typically manufacturers of coal handling system components who have the capability to provide repair services, either on-site or at refurbishment facilities.

Table 8-1 provides a compilation of the organizations researched for inclusion in this report.

8-1

Industry Resources Resources for Coal Handling Handling System Training, Training, Consulting, and Repair

Table 8-1 Industry Resources for Coal Handling System Training, Consulting, and Repair Organization

Location

Training

Consulting

Repair

Airtrol, Inc. – Control systems, dust collectors. http://www.airtrol.com/ http://www.airtrol.com/

Fenton, MO

X

X

X

Belt-Way Scales, Inc. – Manufacturer of scales, conveyors, flow meters. http://www.beltwayscales.com

Rock Falls, IL

X

X

B.E.S.T., Inc. (Bulk Equipment Systems Technology, Inc.) – Pneumatic and electric vibrators. Vibratory feeders, tables, conveyors, R.R. car shakers, screens, vibrator accessories, isolation mountings.

Brunswick, OH

X

X

Continental Conveyor and Equipment Co. – Manufacturer of idlers, conveyor pulleys. http://www.continentalconveyor.com

Winfield, AL

X

X

Dings Company (Magnetic Group) – Complete line of magnetic separators, includi ng magnetic plates, grates, hoppers and chutes for removing fine iron from powder or granular material; overhead magnets, pulleys and drums. http://www.dingsmagnets.com http://www.dingsmagnets.com

Milwaukee, WI

X

X

Dover Conveyor and Equipment Co., Inc. – Manufacturer of conveyors. http://web.tusco.net/dce http://web.tusco.net/dce

Midvale, OH

X

Enerfab, Inc. – Manufacturer of coal handling equipment. Capabilities include new system equipment installation, conveyor systems, pulverizer repair and overhaul, coal pipe, AR tiles, and ash hopper lining and relining. http://www.enerfab.com

Cincinnati, OH

X

Eriez, Inc. – Manufacturer of magnetic, vibratory, and metal detection equipment. http://www.eirez.com

Erie, PA

X

FMC Technologies, Inc., Material Handling Systems Div. – Manufacturers of conveyors and related equipment. http://www.fmcgvs.com http://www.fmcgvs.com

Chalfont, PA

X

X

X

General Kinematics Corp. – Manufacturers of vibratory screens, vibratory feeders, fixed and variable rate; vibrating conveyors, types and sizes for all process applications. Conveyor designs. http://www.generalkinematics.com http://www.generalkinematics.com

Crystal Lake, IL

X

X

X

Heyl & Patterson, Inc. – Specialty railcar offloading systems, including car dumpers and train positioners. High-capacity barge unloading systems, grab bucket and continuous bucket elevator unloaders for bulk materials. http://www.heylpatterson.com http://www.heylpatterson.com

Pittsburgh, PA

X

X

X

8-2

X


Table 8-1 (continued) (continued) Industry Resources for Coal Handling System Training, Consulting, and Repair Organization Organizati on

Location

Training

Kolman Div., The Conveyor Company – Specializing in the design and manufacture of conveyor Sibley, IA systems for industrial purposes. Overland conveyors and systems; top-fold, fixed-height, sidefold, and mast-type radial stackers; stinger stackers; stationary conveyors; shuttle/grasshopper conveyors; trap loaders; cold feed plants; vibrating screens and grizzlies; pugmills; portable screening plants; mega screens; portable pugmill p lants; ash blenders; rear dump truck unloaders and drive-over truck unloaders; belt feeders and plate feeders; and crushers. http://www.kolman.com

Consulting

Repair

X

X

Magnetic Products, Inc. – Rotary feeders, conveying equipment, separation equipment, electromagnets, magnetic materials, automated parts handling, holding and fixturing. http://www.mpimagnet.com

Highland, MI

X

Metso Minerals Processing – Equipment and systems for mineral processing operations. Products include equipment for grinding, classifying, washing and pretreating, mineral separation, slurry handling and processing, and thermal drying. http://www.metsominerals.com http://www.metsominerals.com

York, PA

X

PEBCO Inc. – Bulk handling equipment for all i ndustries, dustless loading spouts, slide gates, diverters, belt feeders, fluidized conveyors, mass flow feeders, ramp valves, and flapper valves. http://www.pebco.com

Paducah, KY

Pennsylvania Crusher Corp. – Granulators, shredders, hammermills. http://www.penncrusher.com

Broomall, PA

Plattco Corp. – Manufacturer of double-flap airlock valves, slide gates, custom valves that prevent leakage, back flow, reduce wear/maintenance. Eliminate pneumatic system/equipment pressure loss, reduces fan. http://www.plattco.com

Plattsburgh, NY

X

ProFog – Manufacturer and distributor of coal handling, dust suppression, and air pollution control equipment. System design and engineering services. Replacement parts, training and dealer support. http://www.profogusa.com http://www.profogusa.com

Phoenix, AZ

X

Puritan Magnetics, Inc. – Full range of magnetic products featuring magnetic separation products for capturing, controlling, and removing ferrous metal contaminants from products and processing systems. http://www.puritanmagnetics.com http://www.puritanmagnetics.com

Oxford, MI

X

X

X

X

X

X

X

8-3


Table 8-1 (continued) (continued) Industry Resources for Coal Handling System Training, Consulting, and Repair Organization Organizati on

Location

Training

Consulting

Repair

Salina Vortex Corp. – Manufacturer of material handling equipment and sl ide gates. http://www.salinavortex.com

Salina, KS

X

X

X

Shields Co. – Manufacturer of permanent magnetic sweepers and magnetic retrieval devices. http://www.shieldscompany.com

Ventura, CA

Stock Equipment Company, Inc. – Designs and manufacturers precision bulk material feed systems (gravimetric and volumetric), valves (burner line, bulk material), electrostatic precipitator controls, acoustic pyrometers, combustion. http://www.stockequipment.com

Chagrin Falls, OH

Thermo Electron Corp., Bulk Material Handling – The Ramsey product li ne offers industrial inmotion weighing, inspection, monitoring, and control equipment, such as belt conveyor scales, weigh-belt feeders, tramp metal detectors, sampling systems, level indicators, conveyor safety switches, and a variety of other specialty process instruments. These products are used for automation, process control, and production. http://www.thermo.com/bulk-handling http://www.thermo.com/bulk-handling

Minneapolis, MN

Westmont Industries – Design, fabricate, and install complete turnkey, custom coal handl ing equipment and systems for industrial applications. http://www.westmont.com/material/material.html

Santa Fe Springs, CA

8-4

X

X

X

X

X

X

X

X

9 REFERENCES

1. Gearbox and Gear Drive Maintenance Guide. EPRI, Palo Alto, CA: 2004. 1009831. 2. Flexible Shaft Couplings Maintenance Guide. EPRI, Palo Alto, CA: 2003. 1007910. 3. Ash Handling System Maintenance Guide. EPRI, Palo Alto, CA: 2005. 1011684. 4. Pulverizer Maintenance Guide, Volume 1: Raymond Bowl Mills. EPRI, Palo Alto, CA: 2004. 1005061. 5. Pulverizer Maintenance Guide, Volume 2: Babcock & Wilcox Roll Wheel EPRI, Palo Alto, CA: 2004. 1009508.

™

Pulverizers.

6. Pulverizer Maintenance Guide, Volume 3: Ball/Tube Mills. EPRI, Palo Alto, CA: 2006. 1010443. 7. Troubleshooting of Electric Motors. EPRI, Palo Alto, CA: 2000. 1000968. 8. Electric Motor Predictive and Preventive Maintenance Guide. EPRI, Palo Alto, CA: 1992. NP-7502. 9. Forced Draft and Induced Draft Fan Maintenance Guide. EPRI, Palo Alto, CA: 2004. 1009651. Var ious Technical Reports. EPRI, Palo Alto, CA: 10. Bearing Technology Topics, Volume 1: Various 1999. TR-113059-V1. Var ious Technical Papers. EPRI, Palo Alto, CA: 11. Bearing Technology Topics, Volume 2: Various 2000. TR-113059-V2.

12. Survey of the State of the Art of Coal Handling During Freezing Weather EPRI, Palo Alto, CA: 1981. CS-1780. .

13. Guideline for System Monitoring by System Engineers. EPRI, Palo Alto, CA: 1997. TR-107668. 14. Lifting, Rigging, and Small Hoist Usage Program Guide. EPRI, Palo Alto, CA: 2003. 1007914. 15. Metrics for Assessing Maintenance Effectiveness. EPRI, Palo Alto, CA: 2003. 1007604. 16. System and Equipment Troubleshooting Guideline. EPRI, Palo Alto, CA: 2002. 1003093. 17. U.S. Department of Commerce. National Institute of Standards and Technology. Handbook 44: Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices. Washington, D.C.: 2006. 18. Facilities Maintenance Guide. EPRI, Palo Alto, CA: 2004. 1009670. 9-1

References

19. Shaft Alignment Guide. EPRI, Palo Alto, CA: 1999. TR-112449. 20. ASME/ANSI B20.1 Safety Standard for Conveyors and Related Equipment. American Society of Mechanical Engineers, New York, and American National Standards Institute, Washington, Washington, D.C.: 2001.

9-2

10 BIBLIOGRAPHY

Beltservice Corporation. Bulletin 0101, “Products and Services Catalog.” Beltservice Corporation, Corporation, St. Louis, MO: 2006. ———. Bulletin 0102, “Heavy Duty Conveyor and Elevator Belting.” Beltservice Corporation, St. Louis, MO: 2006. ———. Bulletin 0301, “Beltwall Brochure.” Beltservice Corporation, St. Louis, MO: 2006. ———. Bulletin 0601, “Feeder Belts.” Beltservice Corporation, St. Louis, MO: 2006. ———. Bulletin 0602, “Self-Cleaning Magnetic Separator Belts.” Beltservice Corporation, St. Louis, MO: 2006. Dings Company Magnetic Group. “Dings Electro Overhead Magnets.” Dings Company Magnetic Group, Milwaukee, WI: 2006. ———. “Installation and Maintenance Manual for Dings Self-Cleaning Electro Overhead Magnets.” Dings Company Magnetic Group, Milwaukee, WI: 2006. ———. Bulletin No. 2530S, “Rectifiers – Specifications and Data.” Dings Company Magnetic Group, Milwaukee, WI: 1998. ———. Bulletin No. 2530F, “Rectifiers – Instructions.” Dings Company Magnetic Group, Milwaukee, WI: 2005. ———. Bulletin No. 3200S, “Electro Overhead Magnetic Separator – Specifications and Data.” Dings Company Magnetic Group, Milwaukee, WI: 2002.

FMC Technologies Inc. Service Instructions and Parts List 2446, “Series 51M Motor Propelled Belt Trippers.” FMC Technologies Inc., Chalfont, PA: 2006. ———. Service Instructions and Parts List 2685, “Series 51C Cable Propelled Belt Trippers.” FMC Technologies Inc., Chalfont, PA: 2006. General Kinematics Corporation. Service Manual QSR-73-200-02, “Vibratory Feeder.” General Kinematics Corporation, Corporation, Crystal Lake, IL: 2005. Georgia Duck-Enerka. Conveyor Belt Maintenance. Georgia Duck-Enerka, Scottdale, GA: 2006.

10-1

Bibliography

———. Conveyor Belt Troubleshooting. Georgia Duck-Enerka, Scottdale, GA: 2006. ———. Belt Tracking Handbook . Georgia Duck-Enerka, Scottdale, GA: 2006. Goodyear. Conveyor and Elevator Belt Installation and Maintenance. Goodyear, AC Supply, Inc., Milwaukee, WI: 2000. Heyl & Patterson, Inc. Instruction Manual 6761-3, “Maintenance, Lubrication and Installation Manual for a Rotary Railroad Car Dumper and Positioner.” Heyl & Patterson, Inc., Pittsburgh, PA: 2001. ———. Instruction Manual 6773-3, “Installation, Operation, and Maintenance Manual for a Traveling Hammermill.” Heyl & Patterson, Inc., Pittsburgh, PA: 2001. ———. Instruction Manual 6714-3, “Installation, Lubrication and Maintenance Manual for a Bucket Elevator Barge Unloader.” Heyl & Patterson, Inc., Pittsburgh, PA: 2001. ———. Instruction Manual 6758, “Instructions for Operation, Maintenance, Lubrication, and Erection of Turnover Railroad Car Dumper with Vibrator Located on Rear Truss.” Heyl & Patterson, Inc., Pittsburgh, PA: 2002. ———. Instruction Manual 6650-3, “Instructions for Operation, Maintenance and Lubrication of 1400 Ton per Hour Stationary Barge Unloader.” Heyl & Patterson, Inc., Pittsburgh, PA: 2001. NORD Gear Corporation. Corporation. BIM 1040, “Unicase ® 90.1 & 92 Series Helical Bevel Gearboxes – Installation and Maintenance Instructions.” NORD Gear Corporation, Waunakee, WI: 2005. ———. BIM 1004, “MOTORS – AC Induction, Single and Polyphase Installation and Maintenance Instructions.” NORD Gear Corporation, Waunakee, WI: 2005. Pennsylvania Crusher Corporation. Bulletin 4050-D, “Handbook of Crushing.” Pennsylvania Crusher Corporation, Broomall, PA: 2003. Stephens-Adamson Corporation. Instruction Manual 2820, “Series 6326 and 6327 Belt Conveyor Idlers.” Stephens-Adamson Corporation, Appleton, WI: 1992. Thermo Electron Corporation. Catalog 10.050, “Thermo Ramsey Belt Conveyor Scale Handbook.” Thermo Electron Corporation, Minneapolis, MN: 2001.

Ripka, William. “Belt Scale Maintenance.” Thermo Electron Corporation, Minneapolis, MN: 2005. ———. Catalog 3962, Revision D, “Series 10-14 Belt Scales.” Thermo Electron Corporation, Minneapolis, Minneapolis, MN: 2004. ———. Ramsey Sampling Systems, “Training Manual for Chuquicamata.” Thermo Electron Corporation, Minneapolis, MN: 2006. 10-2

Bibliography

———. Performance Testing of Sampling Systems. Thermo Electron Corporation, Minneapolis, MN: 2004. ———. Sampling Handbook . Thermo Electron Corporation, Minneapolis, MN: 2001. ———. Catalog 100.700, “Ramsey Primary Sweep Type Sampling Machine.” Thermo Electron Corporation, Minneapolis, MN: 2002.

10-3

A LISTING OF KEY INFORMATION

A.1

Key O&M Cost Co st Point Poi nt s Key O&M Cost Point

Emphasizes information that will result in overall reduced costs and/or increase in revenue through additional or restored energy production. Referenced Section

Page Number

2.3.4.1

2-16

Using a coal sampling system can help ensure that the utility gets what it pays for and that the mine gets the amount of money the coal is worth.

5.1

5-2

As a general rule, if the repair costs 50% or less of the replacement cost, repair should be considered. If the percentage is greater, replacement is generally the best option.

A.2

Key Point

Key Tech ni cal Point Poi nt s Key Technical Point

Targets information that will lead to improved equipment reliability. Referenced Section

Page Number

Key Point

2.3.11.2

2-52

Normally, when a new belt has been properly installed and tensioned, the takeup roll or pulley (automatic takeup) will be initially set at a position of 25% along the line of travel, leaving 75% of the takeup area available for elongation.

2.3.11.3

2-54

Reversion is

3.1.1.1

3-2

the softening of vulcanized rubber when it is heated too long or exposed to elevated temperatures. It is characterized by deterioration in physical properties and frequently results in tackiness, gumming of the rubber, or loss of tensile strength. Predictive maintenance tasks are performed based on equipment condition. Predictive maintenance relies on technologies to determine the current condition of the equipment so that only the required maintenance is performed before equipment failure.

A-1

Listing of Key Information

Referenced Section

Page Number

3.1.1.2

3-2

Periodic maintenance consists of time-based PM actions taken to maintain a piece of equipment within design operating conditions and to extend its life.

3.1.2

3-3

Corrective maintenance tasks are generated as a result of equipment failure. Corrective tasks are generated when equipment is purposely operated to failure and also when equipment failure is not desired or planned. It is the most basic form of maintenance and also the most expensive. Most plants are moving away from corrective maintenance, but there will always be a portion of maintenance performed as a result of equipment failure.

3.2.1.1

3-5

Frequent checkpoints – Each belt scale installation should be checked frequently to determine when calibration is required. It is recommended that zero be checked every other day and that calibration be checked every week for several months after installation. Observe the results and lengthen the period between calibration checks, depending upon the accuracy desired.

3.2.13.2

3-49

The most important facet of a PM program for a gearbox is the regular inspection, analysis, and changing of the lubricant.

3.2.13.2

3-51

Trending contaminant concentrations is important because it provides an indication of significant increases over time. In some cases, an increase of only 10 ppm of iron is significant because iron contamination indicates contamination from gear wear particles.

5.2.11.1

5-23

The basic, primary rule that must be kept in mind when tracking a conveyor belt is simple. The belt moves toward whichever end of the roller/idler it contacts first.

5.2.13.1

5-29

When the lubrication system is inoperable, it is advisable to pour a small amount of oil on each bearing or journal surface in the gearbox to provide an oil film when rotating the rolling gear elements.

5.2.13.3

5-33

Before replacing a wiped bearing, determine and correct the cause of the wipe.

5.2.14.1

5-38

Coupling key clearance fits should be limited to 0.002 in. (51 µm) maximum. On larger diameter shafts, this might require heat to expand the hub.

5.2.14.1

5-41

Proper heating of a tapered hub is extremely important and in many cases is more so than with a straight shaft.

5.2.14.1

5-42

Under no circumstances should the taper bore coupling be lapped to the shaft. This will create a step on the shaft over which the coupling hub must pass, leaving a non-contacting area under the coupling hub.

5.2.14.2

5-43

Coupling misalignment differs from shaft misalignment. Shaft misalignment is measured in offset and angularity. Coupling misalignment is measured in an angle of degrees of misalignment.

A-2

Key Point


Referenced Section

Page Number

5.2.14.3

5-44

The hub will stand off the shaft at the key location after cooling, if the coupling is heated for installation to facilitate an interference fit.

5.2.14.4

5-45

The majority of couplings in a generating station are not balanced.

6.2.4.1

6-7

The most critical failure in a sampling system occurs when a sample cutter stops in the stream of material. If a primary sample cutter were to become stuck in the stream of material on a conveyor belt, it is possible that hundreds of pounds of material could be displaced each second. This makes it imperative that these types of failures be identified immediately.

A.3

Key Point

Key Human Hum an Perfo Per fo rm anc e Point Poi nt s Key Human Performance Point

Denotes information that requires personnel action or consideration in order to prevent personal injury, equipment damage, and/or improve the efficiency and effectiveness of the task. Referenced Section

Page Number

Key Point

2.3.4.6

2-20

Never adjust a mechanical variable-speed reducer unless the feeder is running. Adjusting these reducers while not running could severely damage them.

3.2.2.1

3-10

To prevent rotation of the rotary car dumper when taken out of service for maintenance or repair, a positive lock should be provided. The positive lock should consist of a pair of come-alongs or chain falls tied off by chain or cables to the dumper drive chain or rotate structure, with the come-alongs or chain fall anchored to the foundation. The positive locks are required any time the drive train is broken or the dumper drive brake is deactivated for service or repair. Failure to lock the dumper in the seated position could cause misalignment problems after repairs or servicing are complete, damage to the dumper, or injury to maintenance personnel.

3.2.4.2

3-18

Housekeeping is the first component of maintaining a sampling system. Keeping the sampling system clean is very important to the long-term performance of a sampling system.

3.2.4.2

3-19

Good housekeeping of the sampling system and minimizing the amount of fugitive coal particles greatly reduces the risk of fire from spontaneous combustion.

3.2.4.4

3-25

All disassembling, assembling, and adjustment of parts should be executed only by personnel who have good fundamental and practical knowledge of machines and mechanical devices.

A-3


Referenced Section

Page Number

Key Point

3.2.8

3-33

With the exception of taking some electrical readings that require the magnet to be energized, all routine maintenance should be performed with the magnet de-energized and the drive motor off and locked out so it cannot be accidentally started. If the magnet has been on for a long time, it should be allowed to cool down, which can take several hours.

3.2.9.1

3-35

De-energize the gate/diverter valve by removing electrical power, compressed air, and hydraulic power, and relieve any residual pressure or stored energy before removing covers.

3.2.9.1

3-36

Never place hands, arms, fingers, or other body parts in the gate/diverter valve’s blade path.

5.2.14.1

5-39

Caution: when heating a coupling, care must be taken to prevent

contact with the hub because contact will cause severe burns. A threaded rod inserted in the puller holes works well to handle heated components during installation. The use of welder’s gloves can prevent burns. 5.2.14.1

5-39

An important reminder is that usually a torch is required to remove the hub at the equipment location. If the location of the equipment is such that the environment is volatile, the rotor should be removed and transported to an area where conditions are safer.

5.2.14.1

5-42

Ensure that hydraulic equipment is in good working order to preclude the danger of hydraulic hoses under high pressure separating and causing personnel injury.

A-4

B TRANSLATE TRANSL ATED D TA TA B L E OF CONTENTS CONTENTS

DISCLAIMER OF WARRANTIES AND LIMITATION OF LIABIL ITIES

THIS DOCUMENT WAS PREPARED BY THE ORGANIZATION(S) NAMED BELOW AS AN ACCOUNT OF WORK SPONSORED OR COSPONSORED BY THE ELECTRIC POWER RESEARCH INSTITUTE, INC. (EPRI). NEITHER EPRI, ANY MEMBER OF EPRI, ANY COSPONSOR, THE ORGANIZATION(S) BELOW, NOR ANY PERSON ACTING ON BEHALF OF ANY OF THEM: (A) MAKES ANY WARRANTY WARRANTY OR REPRESENTATION WHATSOEVER, EXPRESS EXPRESS OR IMPLIED, (I) WITH RESPECT TO THE USE OF ANY INFORMATION, APPARATUS, METHOD, PROCESS, OR SIMILAR ITEM DISCLOSED IN THIS DOCUMENT, INCLUDING MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, OR (II) THAT SUCH USE DOES NOT INFRINGE ON OR INTERFERE WITH PRIVATELY OWNED RIGHTS, INCLUDING ANY PARTY'S INTELLECTUAL PROPERTY, OR (III) THAT THIS DOCUMENT IS SUITABLE TO ANY PARTICULAR USER'S CIRCUMSTANCE, (IV) THAT ANY TRANSLATION FROM THE ENGLISH-LANGUAGE ENGLISH-LANGUAGE ORIGINAL OF THIS DOCUMENT IS WITHOUT ERROR; OR (B) ASSUMES RESPONSIBILITY RESPONSIBILITY FOR ANY DAMAGES DAMAGES OR OTHER LIABILITY WHATSOEVER WHATSOEVER (INCLUDING ANY CONSEQUENTIAL DAMAGES, EVEN IF EPRI OR ANY EPRI REPRESENTATIVE REPRESENTATIVE HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES) RESULTING FROM YOUR SELECTION OR USE OF THIS DOCUMENT OR ANY INFORMATION, APPARATUS, METHOD, PROCESS, OR SIMILAR ITEM DISCLOSED IN THIS DOCUMENT. THE TRANSLATION OF THIS DOCUMENT FROM THE ENGLISH-LANGUAGE ORIGINAL HAS BEEN PREPARED WITH LIMITED BUDGETARY RESOURCES BY OR ON BEHALF OF EPRI. IT IS PROVIDED FOR REFERENCE PURPOSES ONLY AND EPRI DISCLAIMS ALL RESPONSIBILITY FOR ITS ACCURACY. THE ENGLISH-LANGUAGE ORIGINAL SHOULD BE CONSULTED TO CROSS-CHECK TERMS AND STATEMENTS IN THE TRANSLATION. ORGANIZATION(S) THAT PREPARED THIS DOCUMENT Electric Power Research Insti tute (EPRI) (EPRI)

B-1

Translated Table of Contents

RESUME

Le guide de maintenance de système de manutention man utention de charbon fournit au personnel de maintenance des centrales l'information de maintenance sur ce système. Ce rapport aidera le personnel de maintenance de centrale en améliorant la fiabilité et en réduisant les coûts de maintenance pour le système de manutention de charbon.

Contexte En 2003, les membres du centre d'applications de maintenance fossile (FMAC) ont complété une étude sur des questions de maintenance. Plusieurs sujets étaient la manutention de cendres volantes et la manutention de charbon. Des réactions d'étude, le comité de restructuration de FMAC a recommandé le développement des conseils pour ces deux systèmes principaux. FMAC a produit les guides relatifs aux questions q uestions de maintenance pour sootblowing, cend re inférieure, et systèmes de dépoussiéreur électrostatique. En 2005, FMAC a complété le guide de maintenance de système de manutention de cendre (1011684). Il est maintenant temps d'adresser la préoccupation particulière concernant les procédés pour la manutention du charbon du temps où le charbon est déchargé jusqu'à ce qu'il entre dans la centrale à pulvériser.

Objectifs Décrire le matériel et les composants typiques d'un système de manutention de charbon •

•

Fournir des conseils sur la maintenance, le dépannage et le remontage, et les recommandations préventives de détection des pannes pour le matériel de manutention de charbon

Appr Ap proc oche he L'intention du guide de maintenance de système de manutention de charbon est d'aborder la l’ingénierie, la maintenance, et les questions de fonctionnement concernant la maintenance de système de manutention de charbon. Des fournisseurs principaux des modèles et des composants de système de manutention de charbon ont été sollicités pour l'aide pour s'assurer que le rapport reflète les dernières technologies de l'industrie. On a con stitué un groupe consultatif technique qui s'est composé des propriétaires de matériel de manutention de charbon des membres d'utilitaire d'EPRI FMAC.

B-2


Résultats Cet rapport technique fournit une vue d'ensemble des paramètres de modèle de système et familiarise le personnel de maintenance et d'ingénierie à une centrale fossile de puissance avec les composants typiques de charbon et leur fonctionnement. Le centre du rapport fournit des conseils pour exécuter la maintenance préventive sur les nombreux composants du système. Le rapport fournit également des conseils concernant le dépannage et le remontage des composants de système et des composants réparés ou reconditionnés sur le site. Des conseils de détection des pannes sont donnés pour ces composants pour lesquels ils sont applicables. Les directives de qualification et de sécurité de personnel sont incluses. Persp Persp ectiv e d'EPRI L'information contenue dans cet rapport représente une collecte significative d'information technique et humaine de rendement, y compris des techniques et de bonnes pratiques, liées au modèle, à la maintenance, et au fonctionnement des systèmes de manutention de charbon courants à la plupart des postes générateurs de puissance fossiles domestiques. L'assemblage de cette information fournit une référence pour le personnel d'ingénierie et de maintenance de centrale, maintenant et à l'avenir. Par l'utilisation de ce rapport dans la conjonction proche avec les conseils d'industrie fournis par les fournisseurs constitutifs de manutention principale de charbon, les membres d'EPRI devraient être en mesure d'améliorer de manière significative et mettre en application conforme les procédés liés au fonctionnement sûr et fiable de leurs systèmes de manutention de charbon. Mots-clés Manutention de charbon Maintenance Maintenance préventive Base préventive de maintenance Fiabilité Détection des pannes

B-3


TABLE DES MATIERES

1

INTRODUCTION INTRODUCTION .......................... ........................................ ............................ ............................ ............................ ............................ ........................... .................. ..... 1-1

1.1 Objectif ............. .......................... ........................... ............................ ............................ ............................ ............................ ............................ ....................... ............ ... 1-1 1.2 portée des composants com posants de matériel et de système ............ ........................... ............................. ............................ .............. 1-1 1.2.1 Vue d'ensemble du système sys tème de manutention de charbon ............. ........................... ........................ .......... 1-1 1.2.2 Unicité de chaque système de manutention de charbon ............. ............................ .......................... ........... 1-3 1.2.3 Utilisation des conseils dans cet c et rapport ............... ............................. ............................ ............................ .................... ...... 1-7 1.3 Structure S tructure et vue d'ensemble ............ .......................... ............................ ............................ ............................ ........................... ...................... ......... 1-7 1.4 Glossaire des conditions et des acronymes a cronymes ............. ........................... ............................ ............................ ......................... ........... 1-8 1.4.1 Définitions et nomenclature d'industrie ............... ............................. ............................ ............................ ....................... ......... 1-8 1.4.2 Acronymes .............. ............................ ............................ ........................... ........................... ............................ ............................ .......................... ............ 1-9 1.5 Le rapport avec EPRI FMAC et EPRI ............. ........................... ............................ ............................ ............................ .................. .... 1-10 1.5.1 Conseils constitutifs de maintenance .............. ............................ ............................ ............................ ........................ .......... 1-11 1.5.2 Conseils selon les programmes de maintenance et de procédé .............. ......................... ........... 1-11 1.6 Points clés .............. ............................ ............................ ............................ ............................ ............................ ........................... ........................... .................. .... 1-12 INTRODUCTION INTRODUCTION AUX COMPOSANTS DE SYSTEME DE CHARBON ET DE MANUTENTION DE CHARBON CHARB ON ............................ .......................................... ........................... ........................... ............................ ........................ .......... 2-1

2.1 Types et caractéristiques de charbon .............. ............................ ............................ ............................ ............................ ................... ..... 2-1 2.1.1 Caractéristiques générales de charbon .............. ............................ ............................ ............................ ....................... ......... 2-1 2.1.2 Catégories et types de charbon .............. ............................. ............................. ............................ ............................ .................... ...... 2-1 2.1.2.1 Charbon anthracite ............ .......................... ............................ ............................ ............................ ............................ .................... ...... 2-2 2.1.2.2 Houille H ouille ggrasse rasse ............. ........................... ............................ ............................ ............................ ............................ ........................... ............. 2-3 2.1.2.3 Charbon de Subbituminous Subbitumin ous .............. ............................ ............................ ............................ ........................... ................... ...... 2-3 2.1.2.4 Charbon de lignite ............. ........................... ............................ ............................ ............................ ........................... ..................... ........ 2-3 2.1.3 Chimie de charbon ............. ........................... ............................ ............................ ............................ ........................... ........................... .............. 2-3 2.1.4 Dureté de charbon cha rbon et valeurs calorifiques c alorifiques .............. ............................ ............................ ............................ ................... ..... 2-4 2.2 Sources de charbon aux Etats-Unis ............ .......................... ............................ ............................ ............................ ........................ .......... 22-5 -5 2.3 Introduction aux composants de système de manutention de charbon ............ ........................ ............ 2-6 B-4


2.3.1 Échelles de courroie courr oie ............. ........................... ............................ ............................ ........................... ........................... .......................... ............ 2-6 2.3.2 Déchargeant le matériel .............. ............................ ............................ ........................... ........................... ............................ ................... ..... 2-8 2.3.2.1 Dumper rotatoire de Railcar ............ .......................... ............................. ............................. ............................ .................... ...... 2-8 2.3.2.2 Dumper de Railcar de renouvellement ............. ........................... ............................ ............................ ................ 2-10 2.3.2.3 Positionneur de train .............. ............................ ............................ ............................ ............................ ............................ .............. 2-10 2.3.2.4 Sélecteur de Railcar ............. ........................... ............................ ............................ ............................ ............................ .................. 2-11 2.3.2.5 Hammermill de déplacement ............ .......................... ............................ ............................ ............................ ................. ... 2-12 2.3.2.6 Déchargeuse continue de chaland .............. ............................ ............................. ............................. ................... ..... 2-12 2.3.2.7 Déchargeuse de chaland de position d'encavateur ............. ............................ ........................ ......... 2-13 2.3.3 Déchargement Déch argement des distributeurs .............. ............................ ............................ ............................. ............................. ................. ... 2-14 2.3.4 Équipement d'échantillonnage ............... ............................. ............................ ............................. ............................. ................... ..... 2-15 2.3.4.1 Introduction au prélèvement de charbon ............. ............................ ............................. ......................... ........... 2-15 2.3.4.2 Composants de système de prélèvement de charbon ................................. 2-16 2.3.4.3 Machine primaire de prélèvement ...................................... .................................................... .......................... ............ 2-18 2.3.4.4 Départ primaire de courroie .............. ............................ ............................ ............................ ............................ ................. ... 2-19 2.3.4.5 Broyeur d'échantillonneur de charbon ............. ........................... ............................ ............................ .................. 2-19 2.3.4.6 Départ secondaire de courroie/échantillonneur secondaire de mouvement circulaire ............ .......................... ............................ ............................ ............................ ............................ ........................... ............. 2-19 2.3.4.7 Collecteur témoin ............. ........................... ............................ ............................ ............................ ............................ .................... ...... 2-20 2.3.4.8 Convoyeur de renvoi d'anomalie .............. ............................ ........................... ........................... ........................ .......... 2-21 2.3.4.9 Panneau électrique de commande ............. .......................... ........................... ............................ ...................... ........ 2-21 2.3.5 Broyeurs de charbon ............. .......................... ........................... ............................ ............................ ............................ ....................... ......... 2-21 2.3.5.1 Méthodes mécaniques de réduction .............. ............................ ............................ ............................. .................. ... 2-21 2.3.5.2 Rupteurs ............ .......................... ............................ ............................ ............................ ............................ ........................... .................... ....... 2-23 2.3.5.3 Fraises ............ .......................... ............................ ............................ ............................ ............................ ............................ ........................ .......... 2-25 2.3.5.4 Granulatoires .............. ............................ ............................ ............................ ........................... ........................... .......................... ............ 2-26 2.3.5.5 Hammermills ............. ........................... ............................ ............................ ............................ ............................ ........................... ............. 2-28 2.3.6 Distributeurs de récupération récu pération .............. ............................. ............................. ............................ ............................ ..................... ....... 2-30 2.3.7 Départs de distributeur dis tributeur de débit ............. ........................... ............................ ........................... ........................... .................... ...... 2-33 2.3.8 Séparateurs magnétiques m agnétiques .............. ............................ ............................ ............................ ............................ ........................... ............. 2-34 2.3.8.1 Aimants supplémentaires autonettoyants ............. ........................... ............................. ......................... .......... 2-34 2.3.8.2 Aimants supplémentaires stationnaires ............ .......................... ............................. ............................. .............. 2-36 2.3.8.3 Redresseurs ............. ........................... ............................ ............................ ............................ ............................. ........................... ............ 2-38 2.3.9 Grilles .............. ............................ ............................ ............................ ............................ ........................... ........................... ............................ ................. ... 2-38 2.3.9.1 Grilles horizontales de guide ............. ............................ ............................. ............................ ............................ .................. 2-38 B-5


2.3.9.2 Dispositifs d'entraînement ............. ........................... ............................ ............................ ............................ ..................... ....... 2-42 2.3.9.3 Joints ............ .......................... ............................ ............................ ............................ ............................ ............................ ......................... ........... 2-42 2.3.9.4 Matériaux de construction c onstruction ............. .......................... ........................... ............................ ............................ ...................... ........ 2-42 2.3.9.5 Signe de position ............... ............................. ............................ ............................ ............................ ............................ .................. .... 2-43 2.3.10 Systèmes de commande de la poussière ............ .......................... ............................ ............................ .................. .... 2-43 2.3.10.1 Fonctionnement général ............. ........................... ............................ ............................ ............................ ..................... ....... 2-44 2.3.10.2 Options de configuration ............ .......................... ............................. ............................. ............................ ..................... ....... 2-46 2.3.11 Bandes de convoyeur, poulies, renvois, et galets ............. ........................... ............................ .................. .... 2-47 2.3.11.1 Types de bandes de convoyeur utilisées dans des systèmes de manutention de charbon ............. ........................... ............................ ............................ ............................ ........................... ..................... ........ 2-47 2.3.11.2 Composants de système de d e bande de convoyeur .............. ............................ ....................... ......... 2-48 2.3.11.3 Attributs et conditions de système de bande de convoyeur ....................... 2-52 2.3.12 Dispositifs mobiles d'excursion de courroie ............... ............................. ............................ .......................... ............ 2-54 2.3.12.1 Moteur-Actionné ............. ........................... ............................ ........................... ........................... ............................ ..................... ....... 2-56 2.3.12.2 Câble-Actionné C âble-Actionné ............. ........................... ............................ ............................ ............................ ........................... ..................... ........ 2-56 2.3.12.3 Courroie-Actionné .............. ............................ ........................... ........................... ............................ ............................ ................. ... 2-56 2.3.13 Boîtes de vitesse ............... ............................. ............................ ............................ ............................ ............................ ........................ .......... 2-56 2.3.13.1 Agencement de trains ............ .......................... ............................ ............................ ............................ .......................... ............ 2-56 2.3.13.2 Applications de boîte de vitesse .............. ............................ ............................ ............................ ...................... ........ 2-60 2.3.14 Couplages d'arbre souple s ouple .............. ............................ ............................ ............................ ............................ .......................... ............ 2-61 2.3.14.1 Vue d'ensemble des couplages d'arbre souple métalliques .............. ...................... ........ 2-61 2.3.14.2 Vue d'ensemble des couplages d'arbre souple élastomères ............. ..................... ........ 2-62 MAINTENANCE ET MESURES PREVENTIVES PREVENTIVES POUR DES COMPOSANTS DE SYSTEME DE MANUTENTION DE CHARBON CHARB ON .......................... ....................................... ........................... ............................ ................ .. 3-1

3.1 Conseils généraux .............. ............................ ............................ ............................ ........................... ........................... ............................ ...................... ........ 3-1 3.1.1 Maintenance préventive ............ .......................... ............................ ............................ ............................ ............................ .................... ...... 3-1 3.1.1.1 Maintenance Mai ntenance prédictive ............ .......................... ............................ ............................ ............................ ........................... ............... 3-2 3.1.1.2 Maintenance périodique .............. ........................... ........................... ............................ ............................ .......................... ............ 3-2 3.1.2 Maintenance corrective ............. .......................... ........................... ............................ ............................ ............................ ..................... ....... 3-3 3.2 Conseils constitutifs de maintenance de système de manutention de charbon ............ 3-4 3.2.1 Échelles de courroie cour roie ............. ........................... ............................ ............................ ........................... ........................... .......................... ............ 3-4 3.2.1.1 Conseils préventifs généraux de maintenance mainte nance .............. ........................... ........................... ................... ..... 3-4 3.2.1.2 Conseils préventifs de maintenance de NIST N IST .............. ............................ ............................ .................... ...... 3-6 3.2.2 Déchargeant le matériel .............. ............................ ............................ ........................... ........................... ............................ ................... ..... 3-8 3.2.2.1 Dumper rotatif de Railcar R ailcar ............. ........................... ............................ ............................ ............................ ........................ .......... 3-8 B-6


3.2.2.2 Dumper de Railcar de renouvellement ............. ........................... ............................ ............................ ................ 3-10 3.2.2.3 Positionneur de train .............. ............................ ............................ ............................ ............................ ............................ .............. 3-11 3.2.2.4 Hammermill de déplacement ............ .......................... ............................ ............................ ............................ ................. ... 3-13 3.2.2.5 Déchargeuse stationnaire de chaland ............. ........................... ............................. ............................. ................ 3-15 3.2.2.6 Déchargeuse de chaland de position ....................................... ..................................................... .................... ...... 3-16 3.2.3 Déchargeant Déch argeant des distributeurs .............. ............................. ............................. ............................ ............................. .................... ..... 3-18 3.2.4 Équipement d'échantillonnage ............... ............................. ............................ ............................. ............................. ................... ..... 3-18 3.2.4.1 Verrouillage/procédure À l'extérieur ............. ........................... ............................ ........................... .................... ....... 3-18 3.2.4.2 Ménage ............. .......................... ........................... ............................ ............................ ............................ ............................ ...................... ........ 3-18 3.2.4.3 Ronde quotidienne par l'entremise de .............. ............................ ............................ ............................ ................ 3-19 3.2.4.4 Maintenance périodique .............. ........................... ........................... ............................ ............................ ........................ .......... 3-20 3.2.5 Broyeurs de charbon ............. .......................... ........................... ............................ ............................ ............................ ....................... ......... 3-25 3.2.5.1 Rupteurs ............ .......................... ............................ ............................ ............................ ............................ ........................... .................... ....... 3-25 3.2.5.2 Fraises de cage ............. ........................... ............................ ............................ ............................ ............................ ...................... ........ 3-26 3.2.5.3 Granulatoires .............. ............................ ............................ ............................ ........................... ........................... .......................... ............ 3-27 3.2.5.4 Hammermills ............. ........................... ............................ ............................ ............................ ............................ ........................... ............. 3-30 3.2.6 Distributeurs de récupération récu pération .............. ............................. ............................. ............................ ............................ ..................... ....... 3-31 3.2.7 Départs de distributeur dis tributeur de débit ............. ........................... ............................ ........................... ........................... .................... ...... 3-32 3.2.8 Séparateurs magnétiques m agnétiques .............. ............................ ............................ ............................ ............................ ........................... ............. 3-33 3.2.9 Grilles .............. ............................ ............................ ............................ ............................ ........................... ........................... ............................ ................. ... 3-35 3.2.9.1 Nettoyage et procédures de Washdown ............. ........................... ............................. ........................... ............ 3-35 3.2.10 Système de commande de la poussière .............. ............................ ............................ ............................ ................. ... 3-36 3.2.11 Bandes de convoyeur, poulies, renvois, et galets ............. ........................... ............................ .................. .... 3-38 3.2.11.1 Conseils généraux ............. .......................... ........................... ............................ ............................ ............................ ................. ... 3-38 3.2.11.2 Maintenance périodique .............. ............................ ............................ ............................ ............................ ..................... ....... 3-38 3.2.11.3 Actions préventives supplémentaires de maintenance .............. ............................ ................ .. 3-41 3.2.11.4 Courroies de nettoyage et composants de convoyeur ............................... ............................... 3-42 3.2.12 Dispositifs mobiles .............. ............................ ............................ ............................ ............................ ............................ ...................... ........ 3-43 3.2.13 Boîtes de vitesse ............... ............................. ............................ ............................ ............................ ............................ ........................ .......... 3-45 3.2.13.1 Contrôle de condition des boîtes de vitesse vitess e ............ ........................... ............................. ................... ..... 3-45 3.2.13.2 Activités préventives p réventives de maintenance ..................................... ................................................... ................... ..... 3-48 3.2.14 Couplages d'arbre souple s ouple .............. ............................ ............................ ............................ ............................ .......................... ............ 3-53 3.2.14.1 Couplages lubrifiés (types de grille et de trains) ............. ........................... ........................... ............. 3-53 3.2.14.2 Couplages métalliques de Nonlubricated d'élément (élastomères, disque, et membrane) .............. ............................ ............................ ........................... ........................... ............................ ..........................3-54 ............3-54 B-7


BA SE DE MA INTENANCE ET MESURES PREVENTIVES ......................... ....................................... .......................... ............ 4-1

4.1 Contexte .............. ............................ ............................ ........................... ........................... ............................ ............................ ............................ ...................... .......... 4-1 4.2 Emplacements de défaut, mécanismes de dégradation, et stratégies de P.M. ............ 4-2 4.3 Tâches de P.M. et leurs mécanismes de dégradation ............. ........................... ............................. ..................... ...... 4-17 4.4 Descripteur Des cripteur préventif de maintenance .............. ............................ ........................... ........................... ............................ .................. .... 4-29 4.5 Description des tâches préventives prév entives de maintenance .............. ............................ ............................ ...................... ........ 4-31 DEPANNAGE ET REMONTAGE REMONTAGE POUR DES COMPOSANTS COMPOSANTS DE SYSTEME SYSTEME DE MANUTENTION DE CHARBON CHARB ON ............................ .......................................... ........................... ........................... ............................ ........................ .......... 5-1

5.1 Conseils généraux .............. ............................ ............................ ............................ ........................... ........................... ............................ ...................... ........ 5-1 5.1.1 Facteurs quantifiables pour l'étude de coût économique ............. ........................... ......................... ........... 5-4 5.1.2 Facteurs qualitatifs principaux dans le processus décisionnel ............. ........................... ................. ... 5-5 5.2 Dépannage et remontage des composants de système de manutention de charbon ............. ........................... ............................ ........................... ........................... ............................ ............................ ............................ ........................ ................. ....... 5-5 5.2.1 Échelles de courroie courr oie ............. ........................... ............................ ............................ ........................... ........................... .......................... ............ 5-6 5.2.2 Déchargeant le matériel .............. ............................ ............................ ........................... ........................... ............................ ................... ..... 5-6 5.2.2.1 Dumper rotatoire de Railcar ............ .......................... ............................. ............................. ............................ .................... ...... 5-6 5.2.2.2 Positionneur de train .............. ............................ ............................ ............................ ............................ ............................. ................. 5-8 5.2.2.3 Hammermill de déplacement ............ .......................... ............................ ............................ ............................ ................... ..... 5-9 5.2.2.4 Déchargeuse stationnaire de chaland ............. ........................... ............................. ............................. ................ 5-10 5.2.2.5 Déchargeuse de chaland de position ....................................... ..................................................... .................... ...... 5-11 5.2.3 Déchargeant Déch argeant des distributeurs .............. ............................. ............................. ............................ ............................. .................... ..... 5-11 5.2.4 Équipement d'échantillonnage ............... ............................. ............................ ............................. ............................. ................... ..... 5-11 5.2.5 Broyeurs ............ .......................... ............................ ............................ ............................ ............................ ............................ ........................... ............... 5-13 5.2.5.1 Rupteurs ............ .......................... ............................ ............................ ............................ ............................ ........................... .................... ....... 5-13 5.2.5.2 Fraises ............ .......................... ............................ ............................ ............................ ............................ ............................ ........................ .......... 5-14 5.2.5.3 Granulatoires .............. ............................ ............................ ............................ ........................... ........................... .......................... ............ 5-15 5.2.5.4 Hammermills ............. ........................... ............................ ............................ ............................ ............................ ........................... ............. 5-16 5.2.6 Distributeurs de récupération récu pération .............. ............................. ............................. ............................ ............................ ..................... ....... 5-17 5.2.7 Départs-papier de distributeur de débit ............ ........................... ............................. ............................ ...................... ........ 5-18 5.2.8 Séparateurs magnétiques m agnétiques .............. ............................ ............................ ............................ ............................ ........................... ............. 5-19 5.2.8.1 Procédure pour régler le rail/tension de la courroie autonettoyante autonettoyante ............ 5-19 5.2.9 Grilles .............. ............................ ............................ ............................ ............................ ........................... ........................... ............................ ................. ... 5-20 5.2.10 Système de commande com mande .............. ............................ ........................... ........................... ............................ ............................ .................. 5-21 5.2.11 Bandes de convoyeur, poulies, renvois, et galets ............. ........................... ............................ .................. .... 5-22 5.2.11.1 Pprocédure pour donner des systèmes sys tèmes ............ .......................... ............................. ........................... ............ 5-22 B-8


5.2.11.2 Épissure de courroie : Méthode d'axe ............ .......................... ............................ ............................ ................ 5-23 5.2.12 Dispositifs mobiles .............. ............................ ............................ ............................ ............................ ............................ ...................... ........ 5-25 5.2.13 Boîtes de vitesse ............... ............................. ............................ ............................ ............................ ............................ ........................ .......... 5-26 5.2.13.1 Procédure type pour le démontage de boîte de vitesse ............... ............................ ............. 5-26 5.2.13.2 Inspection et maintenance des trains ............... ............................. ............................ ........................... ............. 5-30 5.2.13.3 Maintenance des roulements ............. ........................... ............................ ............................ ............................ .............. 5-32 5.2.13.4 Procédure type pour le remontage de boîte de vitesse ............ .......................... ................. ... 5-34 5.2.14 Couplages d'arbre souple s ouple .............. ............................ ............................ ............................ ............................ .......................... ............ 5-37 5.2.14.1 Les ajustements appropriés de mise à jour se sont associés aux couplages ............. ........................... ............................ ............................ ............................ ............................. ............................. ............................ .............. 5-37 5.2.14.2 Cadrage de mise à jour des couplages .............. ............................. ............................. ........................ .......... 5-43 5.2.14.3 Installation des couplages c ouplages ............. ........................... ............................ ............................ ............................. ................... .... 5-43 5.2.14.4 Équilibrage des couplages c ouplages .............. ............................ ............................ ............................ ............................. ................... 5-45 SYSTEME DE MANUTENTION DE CHA RBONS/DETECTION RBONS/DETECTION DES PA NNES CONSTITUTIVE CONSTITUTIVE .......................... ........................................ ............................ ............................ ............................ ........................... ........................... ........................ .......... 6-1

6.1 Detection des pannes pa nnes de système ............. ........................... ............................ ............................ ............................ ......................... ........... 6-1 6.1.1 Systèmes types de manutention de charbon .............. ........................... ........................... ............................ ................ 6-4 6.2 Composants de detection des pannes montés dans la manutention de charbon/donnants des systèmes ............. ........................... ............................. ............................. ............................ ............................ ................... ..... 6-5 6.2.1 Échelles de courroie courr oie ............. ........................... ............................ ............................ ........................... ........................... .......................... ............ 6-5 6.2.2 Déchargeant le matériel .............. ............................ ............................ ........................... ........................... ............................ ................... ..... 6-7 6.2.3 Déchargeant D échargeant des distributeurs ............. ........................... ............................. ............................. ............................ ....................... ......... 6-7 6.2.4 Équipement d'échantillonnage .............. ............................ ............................ ............................ ............................ ....................... ......... 6-7 6.2.4.1 Problèmes Problèm es courants ............. ........................... ............................. ............................. ............................ ............................ ................. ... 6-7 6.2.4.2 Détermination de l'emplacement des problèmes ............. ........................... ............................ .................. 6-9 6.2.4.3 Utilisation de la surface adjacente de conducteur pour localiser des problèmes .............. ............................ ........................... ........................... ............................ ............................ ............................ ............................ ................ 6-10 6.2.4.4 Problèmes.......................... Problèmes........................................ ........................... ........................... ............................ ............................ .................... ...... 6-10 6.2.5 Broyeurs de charbon ............. .......................... ........................... ............................ ............................ ............................ ....................... ......... 6-11 6.2.6 Distributeurs de récupération récu pération .............. ............................. ............................. ............................ ............................ ..................... ....... 6-11 6.2.7 Départs de distributeur dis tributeur de débit ............. ........................... ............................ ........................... ........................... .................... ...... 6-12 6.2.8 Séparateurs magnétiques m agnétiques .............. ............................ ............................ ............................ ............................ ........................... ............. 6-16 6.2.9 Grilles .............. ............................ ............................ ............................ ............................ ........................... ........................... ............................ ................. ... 6-18 6.2.10 Systèmes de commande ............ .......................... ............................ ............................ ............................ ............................ ................ 6-20 6.2.11 Bandes de convoyeur, poulies, renvois, et galets ............. ........................... ............................ .................. .... 6-24 B-9


6.2.12 Dispositifs mobiles d'excursionniste d'exc ursionniste ............... ............................. ............................ ............................ ....................... ......... 6-31 6.2.13 Boîtes de vitesse ............... ............................. ............................ ............................ ............................ ............................ ........................ .......... 6-31 6.2.13.1 Anomalies à hautes températures .............. ............................ ............................ ............................ ................... ..... 6-33 6.2.13.2 pression d'huile inférieure ............. ........................... ............................ ............................ ............................. ................... .... 6-33 6.2.13.3 Bruit exceptionnel ou excessif ............. ........................... ............................ ............................ .......................... ............ 6-34 6.2.13.4 Vibration excessive ............. ........................... ........................... ........................... ............................ ............................ .................. 6-34 6.2.13.5 Émulsion .............. ............................. ............................. ............................ ............................ ............................ ............................ ................ 6-34 6.2.13.6 Relevés de détecteur .............. ............................ ............................ ............................ ............................ ......................... ........... 6-34 6.2.14 Couplages d'arbre souple s ouple .............. ............................ ............................ ............................ ............................ .......................... ............ 6-35 6.2.14.1 Configuration de système de rotation ............. .......................... ........................... ............................ .................. 6-35 6.2.14.2 Incompatibilité et application matérielles .............. ............................ ............................ ....................... ......... 6-40 6.2.14.3 L'installation pratique ............. ........................... ............................ ............................ ............................ .......................... ............ 6-41 QUALIFICATION QUAL IFICATION DES PERSONNELS, PERSONNELS, FORMATION, ET EMISSIONS EMISSIONS DE SECURITE SECURITE ...... 7-1

7.1 Qualification et formation de personnel ............ .......................... ............................ ............................ ............................ ................... ..... 7-1 7.1.1 Opérateurs du système de manutention de charbon ............. ........................... ............................ ................. ... 7-1 7.1.2 Superviseurs principaux .............. ............................ ............................ ............................ ........................... ........................... ................... ..... 7-1 7.1.3 Personnel de maintenance de système de manutention de charbon .................... 7-2 7.2 Émissions de sécurité de personnel .............. ............................ ............................ ............................ ............................ ...................... ........ 7-2 7.2.1 Échelles de courroie cour roie ............. ........................... ............................ ............................ ........................... ........................... .......................... ............ 7-3 7.2.2 Déchargeant le matériel .............. ............................ ............................ ........................... ........................... ............................ ................... ..... 7-3 7.2.3 Déchargeant D échargeant des distributeurs ............. ........................... ............................. ............................. ............................ ....................... ......... 7-3 7.2.4 Équipement d'échantillonnage .............. ............................ ............................ ............................ ............................ ....................... ......... 7-3 7.2.5 Broyeurs de charbon ............. .......................... ........................... ............................ ............................ ............................ ......................... ........... 7-4 7.2.6 Distributeurs de récupération réc upération .............. ............................. ............................. ............................ ............................ ....................... ......... 7-4 7.2.7 Départs de distributeur dis tributeur de débit ............. ........................... ............................ ........................... ........................... ...................... ........ 7-4 7.2.8 Séparateurs magnétiques m agnétiques .............. ............................ ............................ ............................ ............................ ............................ ................ 7-5 7.2.9 Glissent des grilles ............. ........................... ............................ ........................... ........................... ............................ ............................ .............. 7-6 7.2.10 Systèmes de commande de la poussière ............. .......................... ........................... ............................ .................... ...... 77-7 -7 7.2.11 Bandes de convoyeur, poulies, renvois, et galets ............. ........................... ............................ .................... ...... 7-8 7.2.12 Dispositifs mobiles .............. ............................ ............................ ............................ ............................ ............................ ........................ .......... 7-9 7.2.13 Boîtes de vitesse vitess e ............... ............................. ............................ ............................ ............................ ............................ .......................... ............ 7-9 7.2.14 Couplages d'arbre souple s ouple .............. ............................ ............................ ............................ ............................ .......................... ............ 7-10 RESSOURCES 8 RESSOURCES

INDUSTRIELLES INDUSTRIELLES POUR LE DE FORMATION, DE CONSULTATION, ET DE DEPANNAGE DE SYSTEME DE MANUTENTION DE CHARBON ............................ ............................ ............8-1

B-10

Translated Table of Contents 9

REFERENCES REFERENCES ........................... ........................................ ........................... ............................ ........................... ........................... ........................... ...................... ......... 9-1

BIBLIOGRAPHIE 10 ........................... ......................................... ............................ ............................ ........................... ........................... ........................... ............. 10-1 LISTING D'INFORMATION PRINCIPALE .......................... ........................................ ........................... .......................... ........................ ........... A-1

Remarques principales de coût de l’organisation scientifique du travail ............. ............................ ................. A-1 Remarques techniques principales ............. ........................... ............................. ............................. ............................. ............................ ............. A-2 Le rendement humain principal se dirige .............. ............................ ............................ ............................. ............................. .................. .... A-4

B-11


LISTE DE FIGURES Figure système de manutention de charbon isométrique ............. ........................... ............................ ............................ ................ 1-4 Figure système de manutention de charbon isométrique ............. ........................... ............................ ............................ ................ 1-5 Figure système de manutention de charbon isométrique ............. ........................... ............................ ............................ ................ 1-6 Figure portée et contenu de ce rapport d'EPRI ............. ........................... ............................ ............................ ............................ ................. ... 1-8 Figure types ty pes de charbon .............. ............................ ............................ ........................... ........................... ............................ ............................ ....................... ......... 2-2 Figure régions de charbon aux Etats-Unis .............. ............................ ............................ ............................ ............................ ....................... ......... 2-5 Figure composants d'échelle de convoyeur convoy eur à bande ............. ........................... ............................. ............................. ..................... ....... 2-7 Figure dumper rotatif Railcar .............. ............................ ............................ ........................... ........................... ............................ ............................ .................. 2-8 Figure schéma s chéma de dumper Railcar .............. ............................ ............................ ............................ ........................... ........................... ...................... ........ 2-9 Figure dumper Railcar de renouvellement ............. ........................... ........................... ........................... ............................ ........................ .......... 2-10 Figure positionneur po sitionneur Railcar Railc ar de train ............. ........................... ............................ ............................ ........................... ........................... .................... ...... 2-11 Figure sélecteur rotatif ............. ........................... ........................... ........................... ............................ ............................ ............................ ........................ ............ 2-11 Figure Hammermill Hamm ermill de déplacement .............. ............................ ............................ ............................ ........................... ........................... ................. ... 2-12 Figure déchargeuse déchargeus e continue de chaland ............. ........................... ............................ ............................ ............................. ....................... ........ 2-13 Figure déchargeuses mobiles de chaland de position .............. ............................ ............................ ............................ .................. .... 2-14 Figure déchargeant des distributeurs : Vue d'élévation d' élévation ............. ........................... ........................... ........................... ................. ... 2-15 Figure configuration de prélèvement de charbon c harbon .............. ............................ ........................... ........................... ......................... ........... 2-17 Figure, configuration de prélèvement de charbon ............. ........................... ........................... ........................... ......................... ........... 2-18 Figure Type primaire machine de prélèvement ............. ........................... ........................... ........................... ............................ ................ 22-19 -19 Figure rupteur Galet-Monté par Pennsylvanie Bradford ............. ........................... ............................ ............................ ................ 2-24 Figure Pennsylvanie Bradpactor des plaques d'écran étant coupées pour montrer le rotor ............ .......................... ............................ ............................ ............................ ........................... ........................... ............................ .......................... ................... ....... 2-25 Figure la fraise ............. ........................... ............................ ........................... ........................... ............................ ............................ ............................ ....................... ........... 2-26 Figure la vue du granulatoire .............. ........................... ........................... ............................ ............................ ............................ ............................ .............. 2-27 Figure le retrait d'ensemble du granulatoire .............. ............................ ............................ ............................ ............................ ................... ..... 2-27 Figure Hammermill réversible ............. ........................... ............................ ............................ ............................ ............................ ........................... ............. 2-29 Figure Hammermill réversible pour le charbon .............. ............................ ............................ ............................ ........................... ............... 2-30 Figure le distributeur de récupération de l'abaissement du niveau......................................... 2-31 Figure coupée du distributeur de récupération d'abaissement du niveau ............. ........................... ................. ... 2-31 Figure les problèmes extérieurs du stockage ............. ........................... ............................ ............................ ............................ .................. .... 2-32 2 -32 Figure inférieure d'un départ-papier vibratoire de charbon c harbon ............. ........................... ........................... ......................... ............ 2-33 Figure la vue d'ensemble d'un départ-papier vibratoire suspendu de charbon ............. ..................... ........ 2-34 B-12


Figure le séparateur magnétique supplémentaire autonettoyant ............. ............................ ............................. ................ 2-35 Figure la machine magnétique de séparateur suspendue...................................................... 2-35 Figure les options du support................................. support............................................... ............................ ............................ ............................ ....................... ......... 2-36 Figure le séparateur magnétique supplémentaire stationnaire s tationnaire ............. ........................... ............................ ................... ..... 2-37 Figure le fonctionnement d'un aimant supplémentaire s upplémentaire stationnaire ............. ........................... .......................... ............ 2-37 Figure le redresseur type utilisé avec les séparateurs séparateurs électromagnétiques .............. .......................... ............ 2-38 Figure le Galet-Type type grille de guide .............. ............................ ............................ ........................... ........................... ........................ .......... 2-39 Figure le Total-Type type grille de guide ............ .......................... ............................ ............................ ............................ .......................... ............ 2-40 Figure la grille globale de guide de l'aiguillage ............. ........................... ............................ ............................ ............................ .................. 2-40 Figure la grille de guide de Tite® du joint ............. ........................... ............................ ............................ ............................ ........................ .......... 2-41 Figure le système de dépoussiérage dépou ssiérage de poste ............. ........................... ............................ ............................ ............................ ................ 2-44 Figure le système sys tème type de dépoussiérage dépo ussiérage ............. ........................... ............................ ............................ ........................... ....................... .......... 2-45 Figure les options types de configuration de dépoussiérage.................................................. 2-46 Figure les options types d'Access du filtre ............. ............................ ............................. ............................ ............................. ...................... ....... 2-46 Figure les options de connexion types du bras de mer .............. ............................ ............................ ............................. ................. 2-47 Figure les courroies de flanc ridées par............. par ........................... ............................. ............................. ............................. .......................... ........... 2-48 Figure les composants de système de bande de convoyeur.................................................. 2-49 Figure l'excursionniste l'excursionnis te de courroie Moteur-Actionné .............. ............................ ............................ ............................ .................... ...... 22-55 -55 Figure l'excursionniste l'excurs ionniste de courroie courroi e Câble-Actionné ............. ........................... ............................ ............................ ....................... ......... 2-55 Figure la boîte de vitesse du Parallèle-Arbre .............. ............................ ............................ ............................ ............................ .................. .... 2-57 Figure les agencements excentrés d'entraînement de Parallèle-Pignon à queue .............. ..................2-57 ....2-57 Figure en ligne l'entraînement du Parallèle-Pignon ............... ............................. ............................ ............................ ..................... ....... 2-58 Figure l'agencement à angle droit d'entraînement du pignon conique................................. conique.................................... ... 2-58 Figure l'entraînement hélicoïdal conique des trains ............. ........................... ............................ ............................ ....................... ......... 2-59 Figure l'entraînement planétaire conique des trains ............. ............................ ............................. ............................ ..................... ....... 2-60 Figure la boîte de vitesse entraînée par un moteur électrique pour un convoyeur de charbon ............ .......................... ............................ ............................ ............................ ........................... ........................... ............................ ........................ ............. ... 2-60 Figure le retrait sectionnel d'un granulatoire .............. ............................ ............................ ............................ ............................ .................. .... 3-28 Figure les éléments d'un régime préventif de maintenance pour des boîtes de vitesse ........ 3-49 Figure le dépannage générique contre changent l'évaluation ............. ........................... ............................ ...................... ........ 5-2 Figure les facteurs considérés pendant le processus décisionnel .............. ............................ ............................ ................ 5-3 Figure la configuration pour régler le cheminement P.R. magnétique de séparateur/tension ............. ........................... ............................ ............................ ............................ ............................ ............................ ...................... ........ 5-20 Figure les configurations de contact dentaire ............. ............................ ............................. ............................ ............................ ................. ... 5-31 Figure le procédé générique pour la detection des pannes de système (l'évaluation préliminaire) ............ .......................... ............................ ............................ ............................ ........................... ........................... ............................ ...................... ........ 6-2 Figure le procédé générique pour la detection des pannes de système (detection des pannes détaillée de système) ............ .......................... ............................. ............................. ............................ ............................ ...................... ........ 6-3

B-13


LISTE DE DE TABL EAUX Vue d'ensemble des couplages d'arbre souple métalliques ............. ........................... ............................ ....................... ......... 2-61 Vue d'ensemble des couplages d'arbre souple élastomères ............... ............................. ............................ .................... ...... 2-63 La maintenance préventive préventiv e pour des échelles é chelles de courroie .............. ............................ ............................ .......................... ............ 3-7 La maintenance préventive recommandée pour les dumpers rotatoires de Railcar ................ 3-9 Maintenance préventive recommandée pour des dumpers de Railcar de renouvellement ... 3-11 La maintenance préventive pour un système s ystème de positionneur de train ............ .......................... ...................... ........ 3-11 Lla maintenance préventive recommandée pour Hammermills de déplacement .............. .................. .... 3-14 La maintenance préventive recommandée pour les déchargeuses stationnaires de chaland ............. ........................... ............................ ........................... ........................... ............................ ............................ ............................ ........................ ............. ... 3-16 Maintenance préventive recommandée pour des déchargeuses de chaland de position ..... 3-17 Maintenance préventive recommandée pour le charbon déchargeant des distributeurs ...... 3-18 Maintenance préventive recommandée pour l'équipement d'échantillonnage de charbon .... 3-20 Maintenance préventive recommandée pour des rupteurs/compacteurs ............. ........................... ................. ... 3-25 Maintenance préventive recommandée pour des fraises de cage ............. ........................... ........................... ............. 3-27 Maintenance préventive recommandée pour des granulatoires .............. ............................ ............................ ................ .. 3-28 Maintenance préventive recommandée pour Hammermills H ammermills ............. .......................... ........................... ......................... ........... 3-30 Maintenance préventive pour les distributeurs vibratoires de récupération d'abaissement du niveau maintenance préventive pour des départs-papier de distributeur de débit .... 3-32 Maintenance préventive recommandée pour les séparateurs magnétiques .............. ......................... ........... 3-34 La maintenance préventive pour des grilles de guide ........................................ ...................................................... .................... ...... 3-35 Maintenance préventive recommandée pour le matériel de dépoussiérage ............. ......................... ............ 3-37 Inspections préventives de maintenance recommandées pour des systèmes de bande de convoyeur........................ convoyeur...................................... ............................ ............................ ............................ ............................ ............................ ..................... ....... 3-39 Maintenance préventive pour les excursionnistes Moteur-Actionnés de courroie .............. ................. ... 3-43 Maintenance préventive pour les excursionnistes Câble-Actionnés de courroie ................... 3-44 types de thermocouples ............. ........................... ............................ ............................ ........................... ........................... ............................ ....................... ......... 3-46 Vue d'ensemble préventive de programme de la maintenance.............................................. 3-50 Les emplacements du défaut, les mécanismes de dégradation, et les stratégies de P.M. pour des composants de système s ystème de manutention de charbon .............. ............................ ......................... ........... 4-4 Les tâches. et leurs mécanismes de dégradation pour des composants de système de manutention de charbon Descripteur pour des composants de système de manutention de charbon .............. ......................... ........... 4-30 Dépannages et des remontages pour des échelles de courroie ............. ............................ ............................. .................. .... 5-6 B-14


Dépannages et les remontages remontages recommandés pour les dumpers rotatoires de Railcar ......... 5-6 Dépannages et des remontages pour des positionneurs de train .............. ............................ ............................ ................ 5-8 Dépannages et les remontages remontages recommandés pour un Hammermill de déplacement ........... 5-9 Dépannages et les remontages recommandés pour une déchargeuse stationnaire de chaland ............. ........................... ............................ ........................... ........................... ............................ ............................ ............................ ........................ ............. ... 5-10 Dépannages et les remontages recommandés pour une déchargeuse de chaland de position ............. ........................... ........................... ........................... ............................ ............................ ............................ ............................ ........................ ............. ... 5-11 Activités de dépannage recommandées et de remontage pour l'équipement d'échantillonnage de charbon .............. ............................ ............................ ............................ ............................ ............................ ................... ..... 5-12 Les activités de dépannage recommandées et de remontage pour des rupteurs/HybrideRupteurs.................................... Rupteurs.................................................. ............................ ............................ ........................... ........................... ............................ ................. ... 5-13 Activités de dépannage recommandées et de remontage pour des fraises de cage ............ 5-14 Activités de dépannage recommandées et de remontage pour des granulatoires ............ ................ .... 5-15 Activités de dépannage recommandées et de remontage pour Hammermills ....................... 5-16 Dépannages et les remontages pour l'abaissement du niveau vibratoire récupèrent des distributeurs 5-17 Des dépannages et des remontages pour des départs-papier départs-papier de distributeur de débit ........ 5-18 Dépannages et les remontages recommandés pour les séparateurs magnétiques .............. 5-19 Dépannages et des remontages pour des grilles de guide ............... ............................. ............................. ....................... ........ 5-20 Dépannages et les remontages recommandés pour le matériel de dépoussiérage .............. 5-21 Dépannages et des remontages pour les dispositifs Moteur-Actionnés d'excursionniste de courroie dépannages et des remontages pour les dispositifs Câble-Actionnés d'excursionniste de courroie .............. ............................ ............................ ............................ ............................. ............................. .....................5-26 .......5-26 Couples .............. ........................... ........................... ............................ ............................ ............................ ............................ ............................ ....................... ................... .......... 5-36 Tableau des interférences ............. ........................... ............................ ............................ ............................ ........................... ........................... ................... ..... 5-40 Cônes ............ .......................... ............................ ............................ ............................ ............................ ........................... ........................... .......................... ........................ ............ 5-41 Detection des pannes recommandée pour la manutention de charbon/les systèmes de transmettre ............ .......................... ............................ ............................ ............................ ............................ ............................ ........................... ...................... ........... 6-4 La detection des pannes pour des échelles de courroie de système de manutention de charbon ............ .......................... ............................ ............................ ............................ ........................... ........................... ............................ ........................ ............... ..... 6-5 Detection des pannes pour les distributeurs vibratoires de récupération d'abaissement du niveau ............. ........................... ............................ ............................ ........................... ........................... ............................ ............................ ....................... ........... 6-12 Detection des pannes pour des départs-papier de distributeur de débit de Paramount ........ 6-13 Detection des pannes pour des départs-papier de distributeur de débit de Paramount II ..... 6-14 Detection des pannes recommandée pour les séparateurs magnétiques de système de manutention de charbon .............. ........................... ........................... ............................ ............................ ............................ ........................ .......... … 6-16 Detection des pannes pour des grilles de guide ............ ........................... ............................. ............................ ........................... ............. 6-18 Detection des pannes recommandée pour le dépoussiérage/matériel d'élimination ............. 6-20 La detection des pannes recommandée pour des systèmes de bande de convoyeur .......... 6-24 Detection des pannes recommandée recommandée pour des excursionnistes de courroie .............. ........................ .......... 6-31 Modification de la detection des pannes pour des boîtes de vitesse ............... ............................. ...................... ........ 6-31 B-15


Conseils de detection des pannes détaillés pour (des trains et grille) les couplages mécaniques souples .............. ............................ ............................ ............................ ............................ ............................ ............................ ...................6-35 .....6-35 Conseils de detection des pannes détaillés pour le métallique (disque et membrane) et élastomère souple de couplages ........... ........................ ........................... ........................... .......................... .......................... .......................... ................6-38 ...6-38 Problèmes métallurgiques courants et la detection des pannes ............. ........................... ............................ ................. ... 6-40 Pratiques en matière de l'installation menant au défaut de couplage d'arbre souple ............ 6-41 L'expertise type et l'expérience de niveau : Opérateurs du système de manutention de charbon ............ .......................... ............................ ............................ ............................ ........................... ........................... ............................ ........................ ............... ..... 7-1 Expertise type et expérience des Superviseurs principaux ............. ........................... ............................ .......................... ............ 7-2 Expertise type et expérience du Personnel principal de maintenance de système .............. ..................7-2 ....7-2 Ressources d'industrie pour la formation, la consultation, et le dépannage de système de manutention de charbon .............. ............................ ............................ ............................ ............................ ........................... ....................... .......... 8-2

B-16


•

石炭の取扱いシステムの典型的な装置と機器を示すこと

•

石炭の取扱いシステムについての予防保全，修理取替え，とトラブルシューティングの推奨事項に関するガイドを提供すること

B-17


....................... ........................ ....................... ........................ ..................... 1-1

1

1.1目的 .......................................................................................................................

1-1

1.2装置およびシステムコンポーネントの範囲 .............................................................. 1-1 1.2.1石炭取扱いシステムの概要 .............................................................................. 1-1 1.2.2個々の石炭取扱いシステムの特徴 .................................................................... 1-3 1.2.3本レポートガイドの使用 .................................................................................. 1-7 1.3レポートの構造と内容の概要 .................................................................................. 1-7 1.4用語および略称 ......................................................................................................

1-8

1.4.1産業界の定義および専門用語 ........................................................................... 1-8 1.4.2略称 ................................................................................................................

1-9

1.5 EPRI FMACと他のEPRIレポートとの関係 ................................................................ 1-10 1.5.1機器の保全ガイド ..........................................................................................

1-11

1.5.2プログラムに関連しあた保全およびプロセスガイド ........................................ 1-11 1.6キーポイント ........................................................................................................

1-12

................. ......................... ................ ................. ........... 2-1

2

2.1石炭のタイプおよび特性 ......................................................................................... 2-1 2.1.1汎用石炭の特性 ...............................................................................................

2-1

2.1.2石炭のカテゴリそしてランク ........................................................................... 2-1 2.1.2.1無煙炭 .....................................................................................................

B-18

2-2


2.1.2.2れき青炭 ..................................................................................................

2-3

2.1.2.3 亜れき青炭 ..............................................................................................

2-3

2.1.2.4亜炭の石炭 ...............................................................................................

2-3

2.1.3石炭の化学成分 ...............................................................................................

2-3

2.1.4石炭の硬度および発熱量 .................................................................................. 2-4 2.2米国の石炭の産地 ...................................................................................................

2-5

2.3石炭取扱いシステムのコンポーネントの概要 ........................................................... 2-6 2.3.1ベルトスケール ...............................................................................................

2-6

2.3.2荷下し装置 ......................................................................................................

2-8

2.3.2.1回転式レールカーダンプ ........................................................................... 2-8 2.3.2.2ターンオーバー式レールカーダンプ ........................................................ 2-10 2.3.2.3トレインポジショナー ........................................................................... 2-10 2.3.2.4 レールカーインデクサー ................................. ................ .................................. .................................. ..................... .... 2-11 2.3.2.5移動式ハンマーミル .............................................................................. 2-12 2.3.2.6連続的なはしけによる荷下し機 ............................................................... 2-12 2.3.2.7グラブバケット式のはしけによる荷下し機 .............................................. 2-13 2.3.3荷下しホッパー .............................................................................................

2-14

2.3.4サンプリング装置 ..........................................................................................

2-15

2.3.4.1石炭のサンプリングの概要 ..................................................................... 2-15 2.3.4.2石炭サンプリングシステムの機器 ........................................................... 2-16 2.3.4.3一次サンプリング機械 ............................................................................

2-18

2.3.4.4一次ベルト送り装置 ...............................................................................

2-19

2.3.4.5石炭サンプラーの粉砕機 ......................................................................... 2-19 2.3.4.6二次ベルト送り装置 /二次スイープサンプラー ........................................ 2-19 2.3.4.7サンプルコレクター .............................................................................. 2-20

B-19


2.3.4.8リジェクトリターンコンベヤー ................................. ................ ................................... ............................. ........... 2-21 2.3.4.9電気制御表示 .........................................................................................

2-21

2.3.5石炭クラッシャ .............................................................................................

2-21

2.3.5.1機械的減少方法 ......................................................................................

2-21

2.3.5.2ブレーカ ................................................................................................

2-23

2.3.5.3ケージミル .............................................................................................

2-25

2.3.5.4造粒機 ...................................................................................................

2-26

2.3.5.5 ハンマーミル ....................................................................................... 2-28 2.3.6再生ホッパー ............................................................................................... 2-30 2.3.7排出ホッパー送り装置 ...................................................................................

2-33

2.3.8磁気分離器 ....................................................................................................

2-34

2.3.8.1自動クリーニング式オーバーヘッド磁石 ................................................. 2-34 2.3.8.2静止型オーバーヘッド磁石 ..................................................................... 2-36 2.3.8.3整流器 ...................................................................................................

2-38

2.3.9スライド・ゲート ..........................................................................................

2-38

2.3.9.1水平のスライド・ゲート ......................................................................... 2-38 2.3.9.2アクチュエーター .................................. ................. .................................. ................................... ............................... ............. 2-42 2.3.9.3シール ...................................................................................................

2-42

2.3.9.4建築材 ...................................................................................................

2-42

2.3.9.5位置指示 ................................................................................................

2-43

2.3.10防塵システム ...............................................................................................

2-43

2.3.10.1運転概要 ..............................................................................................

2-44

2.3.10.2コンフィギュレーションオプション ...................................................... 2-46 2.3.11コンベヤーベルト、プーリー、アイドラーおよびローラー ........................... 2-47 2.3.11.1石炭取扱いシステムで使用されるコンベヤーベルトのタイプ ................. 2-47

B-20


2.3.11.2コンベヤーベルトシステムの機器 ......................................................... 2-48 2.3.11.3コンベヤーベルトのシステム属性および用語 ......................................... 2-52 2.3.12移動可能なベルト・トリッパー装置 ............................................................. 2-54 2.3.12.1モーター推進ベルトトリッパー ............................................................ 2-56 2.3.12.2ケーブル推進ベルトトリッパー ............................................................ 2-56 2.3.12.3ベルト推進ベルトトリッパー ............................................................... 2-56 2.3.13変速機.........................................................................................................

2-56

2.3.13.1ギヤの機器 ...........................................................................................

2-56

2.3.13.2変速機のアプリケーション ................................................................... 2-60 2.3.14フレキシブル軸継手 .....................................................................................

2-61

2.3.14.1金属フレキシブル軸継手の概要 ............................................................. 2-61 2.3.14.2エラストマーフレキシブル軸継手の概要 ............................................... 2-62

3

...................... ...................... ................ 3-1

3.1一般的ガイド ..........................................................................................................

3-1

3.1.1予防保全 .........................................................................................................

3-1

3.1.1.1予知保全 ..................................................................................................

3-2

3.1.1.2定期保守 ..................................................................................................

3-2

3.1.2事後保全 .........................................................................................................

3-3

3.2石炭の取扱いシステム機器の保全のガイド .............................................................. 3-4 3.2.1ベルトのスケール ............................................................................................

3-4

3.2.1.1一般的予防保全ガイド .............................................................................. 3-4 3.2.1.2 NISTの予防保全ガイド ............................................................................ 3-6 3.2.2荷下し装置 ......................................................................................................

3-8

3.2.2.1回転式レールカーダンプ ........................................................................... 3-8 3.2.2.2ターンオーバー式レールカーのダンプ ..................................................... 3-10

B-21


3.2.2.3トレインのポジショナー .................................. ................ ................................... .................................. ..................... .... 3-11 3.2.2.4移動式ハンマーミル .............................................................................. 3-13 3.2.2.5静止したはしけによる荷下し機 ............................................................... 3-15 3.2.2.6バケット式のはしけによる荷下し機 ........................................................ 3-16 3.2.3荷下しホッパー .............................................................................................

3-18

3.2.4サンプリング装置 ..........................................................................................

3-18

3.2.4.1ロックアウト /タグアウトプロシージャ ................................................... 3-18 3.2.4.2整理整頓 ................................................................................................

3-18

3.2.4.3毎日の歩行による監視 ............................................................................ 3-19 3.2.4.4定期保守 ................................................................................................

3-20

3.2.5石炭クラッシャ .............................................................................................

3-25

3.2.5.1ブレーカ ................................................................................................

3-25

3.2.5.2ケージミル .............................................................................................

3-26

3.2.5.3造粒機 ...................................................................................................

3-27


3-32

3.2.8磁気分離器 ....................................................................................................

3-33

3.2.9スライド・ゲート ..........................................................................................

3-35

3.2.9.1クリーニングおよび洗浄手順 .................................................................. 3-35 3.2.10防塵システム ...............................................................................................

3-36

3.2.11コンベヤーベルト、プーリー、アイドラーおよびローラー ........................... 3-38

B-22

3.2.11.1汎用ガイド ...........................................................................................

3-38

3.2.11.2定期保守 ..............................................................................................

3-38

3.2.11.3追加予防保全の処置 .............................................................................

3-41


3.2.11.4クリーニングベルトおよびコンベヤーの機器 ......................................... 3-42 3.2.12移動可能なトリッパー装置 ........................................................................... 3-43 3.2.13変速機.........................................................................................................

3-45

3.2.13.1変速機アセンブリの状態監視 ............................................................... 3-45 3.2.13.2予防保全活動 .......................................................................................

3-48

3.2.14フレキシブル軸継手 .....................................................................................

3-53

3.2.14.1潤滑されたカップリング (グリッドおよびギヤタイプ ) ........................... 3-53 3.2.14.2金属要素の潤滑装置のないカップリング (エラストマー、ディスクおよ .................. .................................. ................................... ................................... .......................... ......... 3-54 びダイヤフラム ) ...................................

4

....................... ........................ ....................... ........................ ........... 4-1

4.1背景 .......................................................................................................................

4-1

4.2故障位置、劣化メカニズムおよび予防保全の戦略 .................................................... 4-2 4.3 PMタスクおよび劣化のメカニズム ........................................................................ 4-17 4.4予防保全のテンプレート .......................................................................................

4-29

4.5予防保全の記述 ..................................................................................................... 4-31

5

..................... ....................... ....................... .. 5-1

5.1汎用ガイド .............................................................................................................

5-1

5.1.1経済費用検討のための定量化ファクタ .............................................................. 5-4 5.1.2意思決定過程の主要な定性的ファクタ .............................................................. 5-5 5.2石炭取扱いシステム機器の修理そして取替え ........................................................... 5-5 5.2.1ベルトのスケール ............................................................................................

5-6

5.2.2荷下し装置 ......................................................................................................

5-6

5.2.2.1回転式レールカーのダンプ ....................................................................... 5-6 5.2.2.2トレインポジショナー ............................................................................. 5-8 5.2.2.3移動式ハンマーミル ................................................................................ 5-9

B-23


5.2.2.4静止したはしけによる荷下し機 ............................................................... 5-10 5.2.2.5バケット式はしけによる荷下し機 ........................................................... 5-11 5.2.3荷下しホッパー .............................................................................................

5-11

5.2.4サンプリング装置 ..........................................................................................

5-11

5.2.5粉砕機 ..........................................................................................................

5-13

5.2.5.1ブレーカ ................................................................................................

5-13

5.2.5.2ケージミル .............................................................................................

5-14

5.2.5.3造粒機 ...................................................................................................

5-15


5-18

5.2.8磁気分離器 ....................................................................................................

5-19

5.2.8.1自動クリーニング式ベルトのトラッキング，張力調整手順 ....................... 5-19 5.2.9スライド・ゲート ..........................................................................................

5-20

5.2.10防塵システム ...............................................................................................

5-21

5.2.11コンベヤーベルト、プーリー、アイドラーおよびローラー ........................... 5-22 5.2.11.1コンベヤーシステムのトラッキング手順 ............................................... 5-22 5.2.11.2ベルトの接続: 中心線方法 ..................................................................... 5-23 5.2.12移動可能なトリッパー装置 ........................................................................... 5-25 5.2.13変速機.........................................................................................................

5-26

5.2.13.1変速機の分解の典型的なプロシージャ ................................................... 5-26 5.2.13.2ギヤの点検そして保全 .......................................................................... 5-30 5.2.13.3ベアリングの保全 .................................................................................

5-32

5.2.13.4変速機の再組立ての典型的なプロシージャ ............................................ 5-34 5.2.14フレキシブル軸継手 .....................................................................................

B-24

5-37


5.2.14.1カップリングの適切な嵌めあいの維持 .................................................... 5-37 5.2.14.2カップリングのアラインメントの維持 ................................................... 5-43 5.2.14.3カップリングの据付け .......................................................................... 5-43 5.2.14.4カップリングのバランス ....................................................................... 5-45

6

/

...................... ...................... ....... 6-1

6.1システムのトラブルシューティング ........................................................................ 6-1 6.1.1典型的な石炭取扱いシステム ........................................................................... 6-4 6.2石炭の取扱い /運搬システムに取付けられている機器のトラブルシューティング ........ 6-5 6.2.1ベルトスケール ...............................................................................................

6-5

6.2.2荷下し装置 ......................................................................................................

6-7

6.2.3荷下しホッパー ...............................................................................................

6-7

6.2.4サンプリング装置 ............................................................................................

6-7

6.2.4.1よくある問題 ........................................................................................... 6-7 6.2.4.2問題の位置の決定 ..................................................................................... 6-9 6.2.4.3問題を見つけるための運転操作盤 ........................................................... 6-10 6.2.4.4問題解決 ................................................................................................

6-10

6.2.5石炭クラッシャ .............................................................................................

6-11

6.2.6再生ホッパー ............................................................................................... 6-11 6.2.7排出ホッパー送り装置 ...................................................................................

6-12

6.2.8磁気分離器 ....................................................................................................

6-16

6.2.9スライド・ゲート ..........................................................................................

6-18

6.2.10防塵システム ...............................................................................................

6-20

6.2.11コンベヤーベルト、プーリー、アイドラーおよびローラー ........................... 6-24 6.2.12移動可能なトリッパー装置 ........................................................................... 6-31 6.2.13変速機.........................................................................................................

6-31

B-25


6.2.13.1異常に高い温度 ....................................................................................

6-33

6.2.13.2低い油圧 ..............................................................................................

6-33

6.2.13.3異常なまたは過度の異音 ....................................................................... 6-34 6.2.13.4過度の振動 ...........................................................................................

6-34

6.2.13.5泡の発生 ..............................................................................................

6-34

6.2.13.6センサーの読みの喪失 .......................................................................... 6-34 6.2.14フレキシブル軸継手 .....................................................................................

6-35

6.2.14.1回転システムの機器 .............................................................................

6-35

6.2.14.2材料の不整合および誤用 ....................................................................... 6-40 6.2.14.3据付け方法 ............................................................................................ 6-41 ..................... ....................... ....................... .. 7-1

7

7.1人の認定およびトレーニング .................................................................................. 7-1 7.1.1石炭取扱いシステムの操作員 ........................................................................... 7-1 7.1.2第一線のスーパーバイザー ............................................................................. 7-1 7.1.3石炭取扱いシステム保全の担当者 .................................................................... 7-2 7.2人身安全の問題 ......................................................................................................

7-2

7.2.1ベルトスケール ...............................................................................................

7-3

7.2.2荷下し装置 ......................................................................................................

7-3

7.2.3荷下しホッパー ...............................................................................................

7-3

7.2.4サンプリング装置 ............................................................................................

7-3

7.2.5石炭クラッシャ ...............................................................................................

7-4

7.2.6再生ホッパー ................................................................................................. 7-4 7.2.7排出ホッパー送り装置 ..................................................................................... 7-4

B-26

7.2.8磁気分離器 ......................................................................................................

7-5

7.2.9スライド・ゲート ............................................................................................

7-6


7.2.10防塵システム .................................................................................................

7-7

7.2.11コンベヤーベルト、プーリー、アイドラーおよびローラー ............................. 7-8 7.2.12移動可能なトリッパー装置 ............................................................................. 7-9 7-9

7.2.14フレキシブル軸継手 .....................................................................................

7-10

..................8-1

8

........................ ....................... ........................ ........................ ....................... ... 9-1

9

10

A

7.2.13変速機...........................................................................................................

..................... ......................... ........................ ......................... ............... 10-1

............................................................................................... A-1

A.1O&Mコストに関するキーポイント .................. ........................... .................. .................. .................. ................... ................... ........... .. A-1 A.2技術的なキーポイント .................. ............................ ................... .................. .................. .................. ................... ................... .................. ......... A-2 A.3人間過誤に関するキーポイント ................... ............................ .................. .................. .................. ................... ................... .............. ..... A-4

B-27


図1-1石炭取扱いシステムアイソメ図 ................................................................................ 1-4 図1-2石炭取扱いシステムアイソメ図 ................................................................................ 1-5 図1-3石炭取扱いシステムアイソメ図 ................................................................................ 1-6 図1-4本EPRIレポートの範囲と内容 ................................................................................... 1-8 図2-1石炭のタイプ...........................................................................................................

2-2

図2-2米国の石炭地域 ....................................................................................................... 2-5 図2-3ベルト・コンベヤースケールの機器 ......................................................................... 2-7 図2-4回転式レールカーダンプ .......................................................................................... 2-8 図2-5回転式レールカーダンプの概要図 ............................................................................ 2-9 図2-6ターンオーバー式レールカーダンプ ....................................................................... 2-10 図2-7トレインレールカーポジショナー ......................................................................... 2-11 図2-8回転式レールカーインデクサー ............................................................................. 2-11 図2-9移動式ハンマーミル ............................................................................................. 2-12 図2-10連続的なはしけによる荷下し機 ............................................................................ 2-13 図2-11移動可能グラブバケット式のはしけによる荷下し機 .............................................. 2-14 図2-12荷下しホッパー : 正面図 ....................................................................................... 2-15 図2-13高流量，受け取り，石炭のサンプリングコンフィギュレーション .......................... 2-17 図2-14中-低流量，燃焼時の，石炭のサンプリングコンフィギュレーション ..................... 2-18 図2-15一次スィープタイプサンプリング機械 .................................................................. 2-19 図2-16ペンシルバニア・ローラー取付け・ブラッドフォードブレーカ ............................. 2-24 図2-17回転子を示すためスクリーン板を取除いたペンシルバニア・ブラッドパクター ...... 2-25 図2-18ケージミル ..........................................................................................................

B-28

2-26


図2-19造粒機の断面図 ...................................................................................................

2-27

図2-20造粒機の外形図 ...................................................................................................

2-27

図2-21可逆ハンマーミル ............................................................................................... 2-29 図2-22石炭用可逆ハンマーミル ..................................................................................... 2-30 図2-23ドローダウン再生ホッパー .................................................................................. 2-31 図2-24ドローダウン再生ホッパーの断面図 ..................................................................... 2-31 図2-25屋外の保管の問題 ................................................................................................

2-32

図2-26振動式給炭機の下面図 ......................................................................................... 2-33 図2-27吊下げ式振動式給炭機の外形図 ............................................................................ 2-34 図2-28自動クリーニング式オーバーヘッド磁気分離器 ..................................................... 2-35 図2-29吊下げ式磁気分離器 .............................................................................................

2-35

図2-30土台オプション ...................................................................................................

2-36

図2-31静止型オーバーヘッド磁気分離器 ......................................................................... 2-37 図2-32静止型オーバーヘッド磁石の運転 ......................................................................... 2-37 図2-33電磁石分離器によって使用される典型的な整流器 ................................................. 2-38 図2-34典型的なローラータイプ・スライド・ゲート ........................................................ 2-39 図2-35典型的なアグリゲートタイプ・スライド・ゲート ................................................. 2-40 図2-36アグリゲート・ダイバーターのスライド・ゲート ................................................. 2-40 図2-37シールのTite®のスライド・ゲート ....................................................................... 2-41 図2-38石炭荷下し場集じんシステム ............................................................................... 2-44 図2-39典型的な集じんシステム ...................................................................................... 2-45 図2-40典型的な集じんの形態のオプション ..................................................................... 2-46 図2-41典型的なフィルターアクセスオプション ............................................................... 2-46 図2-42典型的な入口の接続オプション ............................................................................ 2-47 図2-43コルゲートサイドウォールベルト ......................................................................... 2-48 図2-44コンベヤーベルトのシステム機器 ......................................................................... 2-49 図2-45モーター推進ベルト・トリッパー ........................................................................ 2-55 図2-46ケーブル推進ベルト・トリッパー ........................................................................ 2-55 B-29


図2-47平行シャフト変速機 .............................................................................................

2-57

図2-48垂直オフセット平行シャフトギア駆動機構 ........................................................... 2-57 図2-49インライン平行シャフトギア駆動機構 .................................................................. 2-58 図2-50垂直-斜角ギヤ駆動機構 ........................................................................................ 2-58 図2-51斜角ヘリカルギヤ駆動機構 ................................................................................... 2-59 図2-52斜角遊星ギア駆動機構 ......................................................................................... 2-60 図2-53石炭コンベヤのためのモータ駆動変速機 ............................................................... 2-60 図3-1造粒機の断面図 .....................................................................................................

3-28

図3-2変速機のための予防保全プログラムの要素 ............................................................. 3-49 図5-1一般的な修理か取替えかの評価 ................................................................................ 5-2 図5-2意思決定過程の中で考慮されるの要因 ...................................................................... 5-3 図5-3磁気分離機のベルトトラッキング /張力調節のための形状 ........................................ 5-20 図5-4歯接触パターン .....................................................................................................

5-31

図6-1システムトラブルシューティング (予備評価)のための一般的なプロセス ..................... 6-2 図6-2システムトラブルシューティング (詳細なシステムトラブルシューティング )のためのの一般的なプロセス .............................................................................................. 6-3

B-30


表2-1金属フレキシブル軸継手の概要 .............................................................................. 2-61 表2-2エラストマーフレキシブル軸継手の概要 ................................................................ 2-63 表3-1ベルトスケールのための予防保全に関する推奨 ........................................................ 3-7 表3-2回転式レールカーダンプの予防保全に関する推奨 ..................................................... 3-9 表3-3ターンオーバー式レールカーダンプの予防保全に関する推奨 .................................. 3-11 表3-4トレインのポジショナーシステムの予防保全に関する推奨 ...................................... 3-11 表3-5移動のハンマーミルの予防保全に関する推奨 .......................................................... 3-14 表3-6静止したはしけによる荷下し機の予防保全に関する推奨 ......................................... 3-16 表3-7バケット式のはしけによる荷下し機の予防保全に関する推奨 .................................. 3-17 表3-8石炭荷下しホッパーの予防保全に関する推奨 .......................................................... 3-18 表3-9石炭のサンプリング装置の予防保全に関する推奨 ................................................... 3-20 表3-10ブレーカ /コンパクターの予防保全に関する推奨 ................................................... 3-25 表3-11ケージミルの予防保全に関する推奨 ..................................................................... 3-27 表3-12造粒機の予防保全をに関する推奨 ......................................................................... 3-28 表3-13ハンマーミルの予防保全に関する推奨 .................................................................. 3-30 表3-14振動式ドローダウン再生ホッパーのための予防保全に関する推奨 .......................... 3-31 表3-15排出ホッパー送り装置の予防保全に関する推奨 ..................................................... 3-32 表3-16磁気分離器のための予防保全に関する推奨 ........................................................... 3-34 表3-17スライド・ゲートの予防保全に関する推奨 ........................................................... 3-35 表3-18吸塵装置の予防保全に関する推奨 ......................................................................... 3-37 表3-19コンベヤーベルトシステムのための予防保全の点検に関する推奨 .......................... 3-39 表3-20モーター推進ベルトトリッパーのための予防保全に関する推奨 ............................. 3-43

B-31


表3-21ケーブル推進ベルトトリッパーのための予防保全に関する推奨 ............................. 3-44 表3-22熱電対のタイプ ...................................................................................................

3-46

表3-23予防保全のスケジュールの概要 ............................................................................ 3-50 表4-1石炭取扱いシステム機器のための故障位置、劣化メカニズムおよび PM戦略 ............... 4-4 表4-2石炭取扱いシステム機器のための PMタスクおよび劣化のメカニズム ........................ 4-18 表4-3石炭取扱いシステム機器のための PMテンプレート .................................................. 4-30 表5-1ベルトスケールの修理と取替えに関する推奨 ............................................................ 5-6 表5-2回転式レールカーダンプのための修理と取替えに関する推奨 .................................... 5-6 表5-3トレインポジショナーのための修理と取替えに関する推奨 ........................................ 5-8 表5-4移動式ハンマーミルのための修理と取替えに関する推奨 ........................................... 5-9 表5-5静止したはしけによる荷下し機のための修理と取替えに関する推奨 ........................ 5-10 表5-6バケット式バージ荷下し機のための修理と取替えに関する推奨 ............................... 5-11 表5-7石炭のサンプリング装置のための修理と取替え作業に関する推奨 ............................ 5-12 表5-8ブレーカ /ハイブリッドブレーカのための修理と取替え作業に関する推奨 ................. 5-13 表5-9ケージミルのための修理と取替え作業に関する推奨 ................................................ 5-14 表5-10造粒機のための修理と取替え作業に関する推奨 ..................................................... 5-15 表5-11ハンマーミルのための修理と取替え作業に関する推奨 ........................................... 5-16 表5-12振動式ドローダウン再生ホッパーの修理と取替えに関する推奨 5-17 表5-13排出ホッパー送り装置のための修理と取替えに関する推奨 .................................... 5-18 表5-14磁気分離器のための修理と取替えに関する推奨 ..................................................... 5-19 表5-15スライド・ゲートのための修理と取替えに関する推奨 ........................................... 5-20 表5-16吸塵装置のための修理と取替えに関する推奨を ..................................................... 5-21 .............. 5-25 表5-17モーター推進式ベルトトリッパー装置のための修理と取替えに関する推奨 .............. .............. 5-26 表5-18ケーブル推進式ベルトトリッパー装置のための修理と取替えに関する推奨 ..............

表5-19締め付けトルクに関する推薦 ............................................................................... 5-36 表5-20嵌め合いに関する表 .............................................................................................

5-40

表5-21テーパの表現 .......................................................................................................

5-41

表6-1石炭の /取扱い /運搬システムのトラブルシューティングをに関する推奨 ..................... 6-4 B-32


表6-2石炭取扱いシステムベルトスケールのためのトラブルシューティングに関する推奨 ............................................................................................................................

6-5

表6-3振動式ドローダウン再生ホッパーのためのトラブルシューティングに関する推奨 .... 6-12 表6-4パラマウント排出ホッパー送り装置のためのトラブルシューティングをに関する推奨 .......................................................................................................................

6-13

表6-5パラマウントII排出ホッパー送り装置のためのトラブルシューティングをに関する推奨 ........................................................................................................................ 6-14 表6-6石炭取扱いシステム磁気分離器のためのトラブルシューティングに関する推奨 ......… 6-16 表6-7スライド・ゲートのためのトラブルシューティングに関する推奨 ............................ 6-18 表6-8吸塵 /塵埃抑制装置のためのトラブルシューティングに関する推奨 ........................... 6-20 表6-9コンベヤーベルトシステムのためのトラブルシューティングに関する推奨 .............. 6-24 表6-10ベルトトリッパーのためのトラブルシューティングに関する推奨 .......................... 6-31 表6-11変速機のためのトラブルシューティングのマトリックス ....................................... 6-31 表6-12フレキシブル機械 (ギヤおよびグリッド)カップリングのためのトラブルシューティングに関する詳細ガイド ...................................................................................... 6-35 表6-13フレキシブル金属性 (ディスクおよびダイヤフラム )カップリングおよびエラストマーカップリングのためのトラブルシューティングの詳細ガイド .............................. 6-38 表6-14共通の冶金問題およびトラブルシューティング ..................................................... 6-40 表6-15フレキシブル軸継手の故障となるインストール方法 .............................................. 6-41 表7-1典型的な専門知識および経験レベル : 石炭取扱いシステム操作員 ............................... 7-1 表7-2典型的な専門知識および経験レベル : 第一線のスーパーバイザー .............................. 7-2 表7-3典型的な専門知識および経験レベル : 第一線のシステム保全員 ................................... 7-2 表8-1石炭取扱いのシステムのためのレーニング，相談および修理に関する産業界の情報リソース ...............................................................................................................

8-2

B-33


RESUMEN DEL INFORME La guía de mantenimiento del sistema de manipulación de carbón proporciona información actualizada sobre el mantenimiento en este sistema al personal de mantenimiento de las centrales de combustibles fósiles. Gracias a este informe, el personal de mantenimiento de dichas centrales podrá mejorar la fiabilidad y reducir los costes de mantenimiento del sistema de manipulación de carbón.

Antecedentes En 2003, el FMAC (Centro de Aplicaciones de Mantenimiento Fósil) terminó un estudio sobre aspectos relacionados con mantenimiento. Determinados aspectos, dos de los cuales eran la manipulación de carbón y de las cenizas volantes, se catalogaron como problemas crónicos con un impacto alto en la fiabilidad de la planta. Basándose en los resultados del estudio, el comité de dirección del FMAC recomendó el desarrollo de unas directrices orientadas a dar respuesta a los problemas de estos dos importantes sistemas. El FMAC ha creado guías de mantenimiento para sistemas del precipitator electroestático, de eliminación del hollín por soplado y de la ceniza de fondo de horno. En 2005, el FMAC terminó la guía de mantenimiento del sistema de manipulación de ceniza (1011684). Ahora es el momento de tratar aspectos específicos relacionados con los procesos “aguas arriba” para la manipulación de carbón desde el momento que el carbón se descarga hasta que entra en la central para ser pulverizado.

Objetivos •

•

Describir el equipo y los componentes típicos de un sistema de manipulación de carbón Ofrecer directrices para la reparación, la substitución y el mantenimiento preventivo, así como recomendaciones de localización y resolución de averías para el equipo de manipulación de carbón

Enfoque La intención de la guía de mantenimiento del sistema de manipulación de carbón es tratar determinados aspectos de ingeniería, mantenimiento y operación relacionados con el mantenimiento del sistema de manipulación de carbón. Se le solicitó la colaboración de algunos de los principales proveedores de diseños y componentes del sistema de manipulación de carbón para lograr que el informe mostrase las últimas tecnologías y tendencias del sector. Se constituyó un grupo de asesores técnicos formado por propietarios de equipos de manipulación de carbón que son socios de FMAC & EPRI. Igualmente, se solicitó información para poder documentar los temas relacionados con el mantenimiento del sistema de manipulación de carbón, detectándose una serie de prácticas y técnicas basadas en la experiencia que son las que se muestran en este documento. B-34


Resultados Este informe técnico ofrece una visión general de los parámetros de diseño del sistema, mostrándole al personal de ingeniería y mantenimiento de las centrales eléctricas de combustibles fósiles cuáles son los componentes y funciones de un sistema típico de transformación/manipulación de carbón. El objetivo del informe es servir de guía para la realización del mantenimiento preventivo en los numerosos componentes que integran el sistema. El informe también ofrece directrices con respecto a la reparación y substitución de componentes del sistema, así como referencias sobre los componentes que normalmente se reparan o restauran en la propia central. Asimismo, se presenta una guía de identificación y resolución de problemas para componentes y se incluyen directrices para la seguridad y cualificación del personal, ofreciéndole al usuario fuentes de formación, reparación, y servicios de consultoría relacionados con los sistemas de manipulación de carbón.

Perspectiva de EPRI La información contenida en este informe representa una recopilación importante de información de funcionamiento técnico y humano, incluyendo técnicas y buenas prácticas relacionadas con el diseño, el mantenimiento y la operación de los sistemas de manipulación de carbón más usados por la mayor parte de las centrales de generación de combustibles fósiles. La recopilación de dicha información ofrece un punto de referencia común para el personal de ingeniería y mantenimiento de las centrales, tanto ahora como en el futuro. Mediante la utilización de este informe y de las directrices ofrecidas por los principales proveedores de componentes de equipos de manipulación de carbón, los socios de EPRI deberían ser capaces de perfeccionar e implantar de forma coherente los procesos relacionados con la operación segura y fiable de sus sistemas de manipulación de carbón.

Palabras claves Manipulación de carbón Mantenimiento Mantenimiento preventivo Base de mantenimiento preventivo Fiabilidad Identificación y resolución de problemas

B-35


CONTENIDO

1

INTRODUCCIÓN INTRODUCCIÓN .......................... ........................................ ........................... .......................... ........................... ........................... ........................... ..................... ....... 1-1 1.1 Propósito ........................... ........................................ ........................... ............................ ........................... ........................... ........................... ........................ ........... 1-1 1.2 Alcance de los componentes del equipo y del sistema ........................... ......................................... ...................... ........ 1-1 1.2.1 Visión general del sistema sistema de manipulación de carbón carbón ........................... ....................................... ............ 1-1 1.2.2 Singularidad de cada sistema de manipulación de carbón ............................ .................................. ...... 1-3 1.2.3 Utilización de las directrices directrices establecidas en este informe informe ............................ ................................... ....... 1-7 1.3 Visión general del contenido y la estructura de este informe ............................ ........................................ ............ 1-7 1.4 Glosario de términos y siglas ........................... ......................................... ........................... ........................... ........................... .................... ....... 1-8 1.4.1 Definiciones y nomenclatura del sector ............................ .......................................... ............................ ....................... ......... 1-8 1.4.2 Siglas ........................... ........................................ ........................... ............................ ........................... ........................... ........................... ...................... ......... 1-9 1.5 Relación con el programa FMAC de EPRI y con otros informes de EPRI ................. ................. 1-10 1.5.1 Guía de mantenimiento de componentes ........................... ......................................... ............................ ................... ..... 1-11 1.5.2 Guía de procesos y mantenimiento programático .......................... ........................................ ...................... ........ 1-11 1.6 Puntos principales ............................ ......................................... ........................... ............................ ........................... ........................... ..................... ....... 1-12

INTRODUCCIÓN A LOS COMPONENTES DEL SISTEMA DE CARBÓN Y DE MANIPULACIÓN DE CARBÓN .......................... ....................................... .......................... .......................... .......................... .......................... ................ ... 2-1 2

2.1 Características y tipos de carbón ........................... ......................................... ............................ ............................ ........................... ............. 2-1 2.1.1 Características generales del carbón ............................ .......................................... ............................ .......................... ............ 2-1 2.1.2 Categorías y grados del carbón ........................... ......................................... ............................ ............................ ..................... ....... 2-1 2.1.2.1 Carbón de antracita ............ .......................... ............................ ........................... ........................... ........................... .................... ....... 2-2 2.1.2.2 Carbón bituminoso ........................... ......................................... ............................ ........................... ........................... ..................... ....... 2-3 2.1.2.3 Carbón sub-bituminoso................... sub-bituminoso................................ ........................... ........................... ........................... ........................ .......... 2-3 2.1.2.4 Carbón lignito .......................... ........................................ ........................... ........................... ............................ ........................... ................ ... 2-3 2.1.3 Química del carbón ............ ......................... ........................... ........................... .......................... ........................... ........................... ................ ... 2-3 2.1.4 Dureza del carbón y valores caloríficos ................................... ................................................. ........................... ................ ... 2-4 2.2 Fuentes del carbón en los lo s Estados Unidos ............................ .......................................... ............................ ......................... ........... 2-5 2.3 Introducción a los componentes del sistema de manipulación de carbón ................... ................... 2-6

B-36


2.3.1 Básculas de correa............. correa ........................... ........................... ........................... ............................ ........................... ........................... ................ .. 2-6 2.3.2 Descarga del equipo ............ .......................... ............................ ........................... ........................... ........................... ........................... .............. 2-8 2.3.2.1 Volquete rotatorio automotor ........................... ........................................ ........................... ........................... .................... ....... 2-8 2.3.2.2 Giro del volquete rotatorio automotor ............................ .......................................... ............................ ................ .. 2-10 2.3.2.3 Posicionador del tren ........................... ........................................ ........................... ........................... ........................... ................ .. 2-10 2.3.2.4 Indexador automotor ........................... ......................................... ........................... ........................... ............................ ................ .. 2-11 2.3.2.5 Trituradora móvil ........................... ......................................... ........................... ........................... ............................ ....................... ......... 2-12 2.3.2.6 Gabarra de descarga contínua ........................... ......................................... ........................... ........................... .............. 2-12 2.3.2.7 Gabarra de descarga (cuchara)....................... (cuchara).................................... ........................... ............................ .................. .... 2-13 2.3.3 Descarga de d e tolvas ........................... ........................................ ........................... ........................... ........................... ........................... ............. 2-14 2.3.4 Equipo de muestreo ........................... ......................................... ........................... ........................... ............................ ........................ .......... 2-15 2-1 5 2.3.4.1 Introducción al muestreo de carbón ................................... ................................................. .......................... ............ 2-15 2.3.4.2 Componentes del sistema de muestreo de carbón ........................... ..................................... .......... 2-16 2.3.4.3 Máquina primaria de muestreo ............ .......................... ........................... ........................... ........................... ............... .. 2-18 2.3.4.4 Alimentador primario de la cinta ........................... ......................................... ........................... ......................... ............ 2-19 2.3.4.5 Trituradora del muestreador de carbón .......................... ........................................ ............................ ................ 2-19 2.3.4.6 Alimentador del cinturón secundario/muestreador de barrido secundario.... 2-19 2.3.4.7 Colector de muestras ........................... ........................................ ........................... ............................ ........................... ............... .. 2-20 2.3.4.8 Transportador de retorno de desechos .................................. ................................................ ...................... ........ 2-21 2.3.4.9 Panel de control eléctrico .................................... ................................................. ........................... ........................... ............... 2-21 2.3.5 Trituradoras de carbón ............ .......................... ........................... ........................... ............................ ........................... ..................... ........ 2-21 2.3.5.1 Métodos mecánicos de reducción ............ .......................... ............................ ............................ ....................... ......... 2-21 2.3.5.2 Disyuntores ............ .......................... ........................... ........................... ............................ ........................... ........................... .................. .... 2-23 2.3.5.3 Molinos jaula ........................... ......................................... ........................... ........................... ............................ ........................... ............... 2-25 2.3.5.4 Granuladores ........................... ........................................ ........................... ............................ ........................... ........................... .............. 2-26 2.3.5.5 Trituradoras ........................... ......................................... ............................ ........................... ........................... ........................... ................ ... 2-28 2.3.6 Tolvas de recuperación ............................ ......................................... ........................... ............................ ............................ .................. .... 2-30 2.3.7 Alimentadores de la tolva de descarga ........................... ......................................... ............................ ....................... ......... 2-33 2.3.8 Separadores magnéticos ........................... ......................................... ............................ ........................... ........................... ................. ... 2-34 2.3.8.1 Imanes aéreos autolimpiables ............................ .......................................... ........................... ........................... .............. 2-34 2.3.8.2 Imanes aéreos estacionarios ........................... ........................................ ........................... ........................... ................. .... 2-36 2.3.8.3 Rectificadores ............................ ......................................... ........................... ........................... ........................... .......................... ............ 2-38 2.3.9 Compuertas deslizantes ........................... ........................................ ........................... ........................... .......................... ................... ...... 2-38 2.3.9.1 Compuertas deslizantes horizontales ............ .......................... ............................ ............................ ................... ..... 2-38

B-37


2.3.9.2 Activadores ............ .......................... ........................... ........................... ............................ ........................... ........................... .................. .... 2-42 2.3.9.3 Sellos .......................... ........................................ ............................ ........................... ........................... ........................... .......................... ............. 2-42 2.3.9.4 Materiales de construcción ............ .......................... ........................... ........................... ............................ ..................... ....... 2-42 2.3.9.5 Indicación de posición ........................... ........................................ ........................... ............................ ........................... ............. 2-43 2.3.10 Sistemas de eliminación de polvo ........................... ......................................... ............................ ........................... ............... 2-43 2.3.10.1 Operación general .......................... ........................................ ............................ ........................... ........................... .................. .... 2-44 2.3.10.2 Opciones de configuración ............ .......................... ............................ ............................ ............................ .................. .... 2-46 2.3.11 Cintas transportadoras, poleas, rodillos de cintas y rodillos .............................. .............................. 2-47 2.3.11.1 Tipos de cintas transportadoras usadas en los sistemas de manipulación de carbón ........................... ......................................... ............................ ............................ ............................ ...................... ........ 2-47 2.3.11.2 Componentes del sistema de la cinta transportadora ................................ ................................ 2-48 2.3.11.3 Características y terminología del sistema sistema de la cinta transportadora ....... 2-52 2.3.12 Dispositivos móviles del disparador de la cinta ............................ .......................................... ..................... ....... 2-54 2.3.12.1 Disparador auto-propulsado .......................... ........................................ ........................... ........................... ................. ... 2-56 2.3.12.2 Disparador propulsado por cable.................................... cable.................................................. ............................ .............. 2-56 2.3.12.3 Disparador propulsado por correas ............ .......................... ............................ ............................ ................... ..... 2-56 2.3.13 Reductoras ............ .......................... ............................ ........................... ........................... ........................... ........................... ....................... ......... 2-56 2.3.13.1 Disposición de los engranajes ............ .......................... ............................ ............................ ........................... ............. 2-56 2.3.13.2 Aplicaciones de la reductora ............ .......................... ............................ ............................ ............................ ................ .. 2-60 2.3.14 Acoplamientos flexibles de árbol ........................... ......................................... ............................ ........................... ................. .... 2-61 2.3.14.1 Visión general de los acoplamientos del árbol metálico flexible................. 2-61 2.3.14.2 Visión general de los acoplamientos flexibles del árbol elastómero/elastomérico ........................... ......................................... ........................... ........................... ............................ ...................... ........ 2-62 3

MANTENIMIENTO PREVENTIVO DE LOS COMPONENTES DEL SISTEMA DE MANIPULACIÓN DE CARBÓN CARBÓN ......................... ...................................... .......................... .......................... .......................... .......................... ................ ... 3-1 3.1 Guía general ............ ......................... .......................... .......................... .......................... .......................... ........................... ........................... ....................... .......... 3-1 3.1.1 Mantenimiento preventivo ............................ ......................................... ........................... ........................... ........................... ................. ... 3-1 3.1.1.1 Mantenimiento predictivo ........................... ........................................ ........................... ........................... ......................... ............ 3-2 3.1.1.2 Mantenimiento periódico ........................... ........................................ ........................... ............................ .......................... ............ 3-2 3.1.2 Mantenimiento correctivo ............ .......................... ........................... ........................... ............................ ........................... ................... ...... 3-3 3.2 Guía de mantenimiento de los componentes del sistema de manipulación de carbón .......................... ........................................ ........................... ........................... ........................... .......................... ........................... ............................ ..................... ....... 3-4 3.2.1 Básculas de correa ............ .......................... ........................... .......................... ........................... ........................... .......................... ................. .... 3-4 3.2.1.1 Guía general de mantenimiento preventivo ............ .......................... ............................ ......................... ........... 3-4 3.2.1.2 Guía de mantenimiento preventivo del NIST ............................ .......................................... ..................... ....... 3-6

B-38


3.2.2 Descarga del equipo ............ .......................... ............................ ........................... ........................... ........................... ........................... .............. 3-8 3.2.2.1 Volquete rotatorio automotor ........................... ........................................ ........................... ........................... .................... ....... 3-8 3.2.2.2 Giro del volquete rotatorio automotor ........................... ......................................... ........................... .................. ..... 3-10 3.2.2.3 Posicionador del tren ........................... ........................................ ........................... ........................... ........................... ................ .. 3-11 3.2.2.4 Trituradora móvil .......................... ........................................ ........................... ........................... ........................... ....................... .......... 3-13 3.2.2.5 Gabarra de descarga estacionaria......................... estacionaria...................................... ........................... .......................... ............ 3-15 3.2.2.6 Gabarra de descarga (cubetas) ........................... ......................................... ............................ ........................... ............. 3-16 3.2.3 Descarga de d e tolvas ........................... ........................................ ........................... ........................... ........................... ........................... ............. 3-18 3.2.4 Equipo de muestreo ........................... ......................................... ........................... ........................... ............................ ........................ .......... 3-18 3-1 8 3.2.4.1 Procedimiento de descargo/cierre ........................... ......................................... ............................ ....................... ......... 3-18 3.2.4.2 Limpieza ........................... ......................................... ............................ ........................... ........................... ........................... .................... ....... 3-18 3.2.4.3 Ronda diaria ........................... ........................................ ........................... ........................... ........................... ............................ ................ .. 3-19 3.2.4.4 Mantenimiento periódico ........................... ......................................... ........................... ........................... ........................ .......... 3-20 3.2.5 Trituradoras de carbón ............ .......................... ........................... ........................... ............................ ........................... ..................... ........ 3-25 3.2.5.1 Disyuntores ............ .......................... ........................... ........................... ............................ ........................... ........................... .................. .... 3-25 3.2.5.2 Molinos jaula ........................... ......................................... ........................... ........................... ............................ ........................... ............... 3-26 3.2.5.3 Granuladores ........................... ........................................ ........................... ............................ ........................... ........................... .............. 3-27 3.2.5.4 Trituradoras ........................... ......................................... ............................ ........................... ........................... ........................... ................ ... 3-30 3.2.6 Tolvas de recuperación ............................ ......................................... ........................... ............................ ............................ .................. .... 3-31 3.2.7 Alimentadores de las tolvas de descarga............ descarga .......................... ............................ ............................ ..................... ....... 3-32 3.2.8 Separadores magnéticos ........................... ......................................... ............................ ........................... ........................... ................. ... 3-33 3.2.9 Compuertas deslizantes ........................... ........................................ ........................... ........................... .......................... ................... ...... 3-35 3.2.9.1 Procedimientos de limpieza y lavado.................................... lavado.................................................. ........................ .......... 3-35 3.2.10 Sistema de eliminación de polvo ............................ ......................................... ........................... ........................... ................ ... 3-36 3.2.11 Cintas transportadoras, poleas, rodillos de cintas y rodillos .............................. .............................. 3-38 3.2.11.1 Guía general ............ .......................... ............................ ........................... ........................... ........................... ........................... .............. 3-38 3.2.11.2 Mantenimiento periódico ........................... ......................................... ........................... ........................... ...................... ........ 3-38 3.2.11.3 Acciones adicionales de mantenimiento preventivo ............................. .................................. ..... 3-41 3.2.11.4 Limpieza de los componentes de las cintas y arrastradores ............ ...................... .......... 3-42 3.2.12 Dispositivos móviles del disparador ........................... ......................................... ............................ ......................... ........... 3-43 3.2.13 Reductoras ........................... ......................................... ........................... ........................... ........................... ........................... ....................... ......... 3-45 3.2.13.1 Monitorización del estado de las reductoras ............................... ............................................. ................ 3-45 3.2.13.2 Actividades de mantenimiento preventivo ............................ .......................................... ..................... ....... 3-48 3.2.14 Acoplamientos flexibles de árbol ........................... ......................................... ........................... ........................... .................. .... 3-53

B-39


3.2.14.1 Acoplamientos lubricados (de rejilla y engranaje) ........................... ..................................... .......... 3-53 3.2.14.2 Acoplamientos no lubricados de elementos metálicos (elastómero, disco, y diafragma) ........................... ......................................... ........................... ........................... ............................ ........................... .................3-54 ....3-54

BASE 4 BASE

DE MANTENIMIENTO PREVENTIVO ........................... ........................................ ........................... ........................... ................. .... 4-1

4.1 Antecedentes .......................... ........................................ ........................... .......................... ........................... ........................... ........................... ................... ..... 4-1 4.2 Localización de fallos, mecanismos mecanismos de degradación y estrategias de M.P. M.P. ............ ................. ..... 4-2 4.3 Tareas de M.P. y sus mecanismos de degradación ............................ .......................................... ....................... ......... 4-17 4.4 Patrón Pa trón de mantenimiento preventivo ........................... ......................................... ............................ ............................ .................... ...... 4-29 4.5 Descripción de tareas de mantenimiento preventivo ............................ .......................................... ...................... ........ 4-31 5

REPARACIÓN Y SUBSTITUCIÓN DE COMPONENTES DEL SISTEMA DE MANIPULACIÓN DE CARBÓN CARBÓN ......................... ...................................... .......................... .......................... .......................... .......................... ................ ... 5-1 5.1 Guía general ............ ......................... .......................... .......................... ........................... ........................... .......................... .......................... ....................... .......... 5-1 5.1.1 Factores cuantificables para el estudio de coste económico .............................. ................................ .. 5-4 5.1.2 Principales factores cualitativos en el procedimiento de toma de decisiones ....... 5-5 5.2 Reparación y substitución de componentes del sistema de manipulación de carbón ........................... ........................................ .......................... ........................... ........................... .......................... ........................... ............................ ..................... ....... 5-5 5.2.1 Básculas de correa ............ .......................... ........................... .......................... ........................... ........................... ........................... ................. ... 5-6 5.2.2 Descarga del equipo ............ .......................... ............................ ........................... ........................... ........................... ........................... .............. 5-6 5.2.2.1 Volquete rotatorio automotor ............ .......................... ........................... .......................... ........................... ..................... ....... 5-6 5.2.2.2 Posicionador del tren ........................... ........................................ ........................... ........................... ........................... .................. .... 5-8 5.2.2.3 Trituradora móvil .......................... ........................................ ........................... .......................... ........................... .......................... ............ 5-9 5.2.2.4 Gabarra de descarga estacionaria ................................... ................................................. ........................... ............... 5-10 5.2.2.5 Gabarra de descarga (cubetas) ........................... ......................................... ............................ .......................... ............ 5-11 5.2.3 Descarga de tolvas ........................... ........................................ ........................... ........................... ........................... ........................... ............. 5-11 5.2.4 Equipo de muestreo ........................... ......................................... ........................... ........................... ............................ ........................ .......... 5-11 5.2.5 Trituradoras ............ .......................... ........................... ........................... ........................... .......................... ........................... .......................... ............ 5-13 5.2.5.1 Disyuntores ............ .......................... ........................... ........................... ............................ ........................... ........................... .................. .... 5-13 5.2.5.2 Molinos jaula ........................... ......................................... ........................... ........................... ............................ ........................... ............... 5-14 5.2.5.3 Granuladores ........................... ........................................ ........................... ............................ ........................... ........................... .............. 5-15 5.2.5.4 Trituradoras ........................... ......................................... ........................... ........................... ............................ ........................... ................ ... 5-16 5.2.6 Tolvas de recuperación ........................... ......................................... ............................ ............................ ............................ .................. .... 5-17 5.2.7 Alimentadores de la tolva de descarga ........................... ......................................... ............................ ....................... ......... 5-18 5.2.8 Separadores magnéticos ........................... ......................................... ........................... ........................... ............................ ................. ... 5-19 5.2.8.1 Procedimiento para ajustar el rastreo/tensión rastreo/tensión de la cinta autolimpiable ...... 5-19

B-40


5.2.9 Compuertas deslizantes ........................... ........................................ ........................... ........................... .......................... ................... ...... 5-20 5.2.10 Sistema de eliminación de polvo ............................ ......................................... ........................... ........................... ................ ... 5-21 5.2.11 Cintas transportadoras, poleas, rodillos de cintas y rodillos .............................. .............................. 5-22 5.2.11.1 Procedimiento de rastreo para los sistemas de transporte......................... transporte......................... 5-22 5.2.11.2 Empalme de la cinta: método del eje de simetría ............................ ...................................... .......... 5-23 5.2.12 Dispositivos móviles del disparador ........................... ......................................... ............................ ......................... ........... 5-25 5.2.13 Reductoras ........................... ......................................... ........................... ........................... ........................... ........................... ....................... ......... 5-26 5.2.13.1 Procedimiento típico para el desmontaje de la reductora .......................... .......................... 5-26 5.2.13.2 Inspección y mantenimiento de los engranajes ............................. ......................................... ............ 5-30 5.2.13.3 Mantenimiento de cojinetes ............ .......................... ........................... ........................... ............................ .................. .... 5-32 5.2.13.4 Procedimiento típico para el re-montaje re-montaje de la reductora ........................... ........................... 5-34 5.2.14 Acoplamientos del árbol flexible ........................... ........................................ ........................... ........................... .................. ..... 5-37 5.2.14.1 Mantenimiento de ajustes apropiados para para los acoplamientos ................. ................. 5-37 5.2.14.2 Mantenimiento del alineamiento de los acoplamientos acoplamientos ............................. ............................. 5-43 5.2.14.3 Instalación de los acoplamientos ............................ .......................................... ............................ ..................... ....... 5-43 5.2.14.4 Equilibrado de los acoplamientos ........................... ......................................... ............................ ..................... ....... 5-45 6 SISTEMA

DE MANIPULACIÓN DE CARBÓN/IDENTIFICACIÓ CARBÓN/IDENTIFICACIÓN N Y RESOLUCIÓN RESOLUCIÓN DE PROBLEMAS EN LOS COMPONENTES ......................... ....................................... ........................... .......................... .................... ....... 6-1 6.1 Identificación y resolución de problemas del sistema ............................ .......................................... ....................... ......... 6-1 6.1.1 Sistemas típicos de manipulación de carbón ........................... ......................................... ........................... ............... .. 6-4 6.2 Componentes de identificación y resolución de problemas instalados en los sistemas de manipulación/ transporte de carbón........................ carbón...................................... ............................ ........................... ............. 6-5 6.2.1 Básculas de correa ............ .......................... ........................... .......................... ........................... ........................... .......................... ................. .... 6-5 6.2.2 Descarga del equipo ............ .......................... ........................... ........................... ............................ ........................... ........................... .............. 6-7 6.2.3 Descarga de tolvas .......................... ........................................ ............................ ........................... ........................... ............................ ................ 6-7 6.2.4 Equipo de muestreo ........................... ......................................... ........................... ........................... ........................... .......................... ............. 6-7 6.2.4.1 Problemas comunes ........................... ........................................ ........................... ............................ ........................... .................. ..... 6-7 6.2.4.2 Localización de problemas .......................... ........................................ ............................ ........................... ...................... ......... 6-9 6.2.4.3 Utilización de la interfaz del operador para localizar problemas .................. 6-10 6.2.4.4 Resolución de problemas prob lemas ........................... ......................................... ........................... ........................... ...................... ........ 6-10 6 -10 6.2.5 Trituradoras de carbón ............ .......................... ........................... ........................... ........................... ........................... ...................... ........ 6-11 6.2.6 Tolvas de recuperación ........................... ......................................... ............................ ............................ ............................ .................. .... 6-11 6.2.7 Alimentadores de la tolva de descarga ............................ .......................................... ............................ ..................... ....... 6-12 6.2.8 Separadores magnéticos ........................... ......................................... ........................... ........................... ............................ ................. ... 6-16

B-41


6.2.9 Compuertas deslizantes ........................... ........................................ ........................... ........................... .......................... ................... ...... 6-18 6.2.10 Sistemas de eliminación de polvo ........................... ......................................... ............................ ........................... ............... 6-20 6.2.11 Cintas transportadoras, poleas, rodillos de cintas y rodillos .............................. .............................. 6-24 6.2.12 Dispositivos móviles del disparador ........................... ......................................... ............................ ......................... ........... 6-31 6.2.13 Reductoras ........................... ......................................... ........................... ........................... ........................... ........................... ....................... ......... 6-31 6.2.13.1 Temperatura alta anormal............................ anormal......................................... ........................... ........................... .................... ....... 6-33 6.2.13.2 Presión de aceite baja ............ .......................... ........................... ........................... ........................... ........................... .............. 6-33 6.2.13.3 Ruido inusual o excesivo ........................... ........................................ ........................... ............................ ..................... ....... 6-34 6.2.13.4 Vibración excesiva .......................... ........................................ ............................ ........................... ........................... .................. .... 6-34 6.2.13.5 Espumación .......................... ....................................... ........................... ........................... .......................... ........................... ................. ... 6-34 6.2.13.6 Ausencia de lecturas del sensor ........................... ......................................... ........................... ....................... .......... 6-34 6.2.14 Acoplamiento flexible ............ .......................... ............................ ........................... ........................... ........................... ...................... ......... 6-35 6.2.14.1 Configuración del sistema rotatorio ........................... ......................................... ............................ .................. .... 6-35 6.2.14.2 Aplicación errónea e incompatibilidad de materiales ........................... ................................. ...... 6-40 6.2.14.3 Prácticas de instalación ........................... ......................................... ............................ ............................ ....................... ......... 6-41 7 APTITUD APTITUD

DEL PERSONAL, FORMACIÓN Y ASPECTOS RELACIONADOS CON LA SEGURIDAD .......................... ....................................... ........................... ........................... .......................... ........................... ........................... ........................... ................. ... 7-1 7.1 Cualificación y formación del personal ........................... ......................................... ............................ ............................ ................... ..... 7-1 7.1.1 Operadores del sistema de manipulación de carbón ........................... ......................................... ................ .. 7-1 7.1.2 Primera línea de supervisores .......................... ........................................ ............................ ........................... ......................... ............ 7-1 7.1.3 Personal de mantenimiento del sistema de manipulación de carbón .................. .................. 7-2 7.2 Aspectos relacionados con la seguridad del personal ............................. ........................................... ..................... ....... 7-2 7.2.1 Básculas de correa ............ .......................... ........................... ........................... ........................... .......................... ........................... ................. ... 7-3 7.2.2 Descarga del equipo ............ .......................... ............................ ........................... ........................... ........................... ........................... .............. 7-3 7.2.3 Descarga de d e las tolvas ........................... ........................................ ........................... ........................... ........................... ....................... ......... 7-3 7.2.4 Equipo de muestreo ........................... ......................................... ........................... ........................... ............................ .......................... ............ 7-3 7.2.5 Trituradoras de carbón ............ .......................... ........................... ........................... ............................ ........................... ....................... .......... 7-4 7.2.6 Tolvas de recuperación ............................ ......................................... ........................... ............................ ............................ .................... ...... 7-4 7.2.7 Alimentadores de la tolva de descarga ............................ .......................................... ............................ ....................... ......... 7-4 7.2.8 Separadores magnéticos ........................... ......................................... ............................ ........................... ........................... ................... ..... 7-5 7.2.9 Compuertas deslizantes ........................... ........................................ ........................... ........................... .......................... ..................... ........ 7-6 7.2.10 Sistemas de eliminación de polvo ........................... ......................................... ............................ ........................... ................ ... 7-7 7.2.11 Cintas transportadoras, poleas, rodillos de cintas y rodillos ................................ ................................ 7-8 7.2.12 Dispositivos móviles del disparador ........................... ......................................... ............................ ........................... ............. 7-9

B-42


7.2.13 Reductoras ........................... ......................................... ........................... ........................... ........................... ........................... ......................... ........... 7-9 7.2.14 Acoplamiento flexible ............ .......................... ............................ ........................... ........................... ........................... ...................... ......... 7-10 8

RECURSOS DEL SECTOR PARA CONSULTAR, REPARAR Y FORMAR EN EL SISTEMA DE MANIPULACIÓN MANIPULACIÓN DE CARBÓN CARBÓN .......................... ....................................... .......................... .......................... ...................8-1 ......8-1 9 REFERENCIAS

......................... ....................................... ........................... .......................... ........................... ........................... .......................... ........................ ........... 9-1

BIBLIOGRAFÍA ......................... ....................................... ........................... ........................... ........................... .......................... ........................... ..................... ....... 10 BIBLIOGRAFÍA A LISTA

10-1

DE INFORMACIÓN CLAVE .......................... ....................................... ........................... ........................... .......................... .................. ..... A-1

A.1 Principales aspectos de coste de O&M ............ .......................... ........................... ........................... ........................... ................... ...... A-1 A.2 Principales aspectos técnicos .......................... ........................................ ............................ ........................... ........................... ................... ..... A-2 A.3 Principales aspectos de comportamiento comportamiento humano .......................... ....................................... ........................... ................ .. A-4

B-43


LISTA DE FIGURAS Figura 1-1 Isométrico del sistema sistema de manipulación de carbón ........................... ........................................ .................... ....... 1-4 Figura 1-2 Isométrico del sistema sistema de manipulación de carbón ........................... ........................................ .................... ....... 1-5 Figura 1-3 Isométrico del sistema sistema de manipulación de carbón ........................... ........................................ .................... ....... 1-6 Figura 1-4 Alcance y contenido de este informe de EPRI ............................ .......................................... ........................... ............. 1-8 Figura 2-1 Tipos de carbón ........................... ......................................... ............................ ........................... ........................... ........................... .................... ....... 2-2 Figura 2-2 Regiones productoras de carbón en los Estados Unidos ............................ ....................................... ........... 2-5 Figura 2-3 Componentes del instrumento de arrastre de las cinta ........................... ......................................... ................ .. 2-7 Figura 2-4 Volquete rotatorio automotor ............ .......................... ............................ ........................... ........................... ........................... ................ ... 2-8 Figura 2-5 Esquema del volquete rotatorio automotor ...................................... .................................................... ....................... ......... 2-9 Figura 2-6 Giro del volquete rotatorio automotor .......................... ........................................ ............................ ........................... ............... 2-10 Figura 2-7 Posicionador del tren automotor............. automotor ........................... ............................ ............................ ............................ ..................... ....... 2-11 Figura 2-8 Indexador automotor ............ .......................... ........................... ........................... ............................ ........................... ......................... ............ 2-11 Figura 2-9 Trituradora móvil ............ .......................... ............................ ........................... ........................... ........................... ........................... ................... ..... 2-12 Figura 2-10 Gabarra de descarga contínua ........................... ......................................... ............................ ........................... ..................... ........ 2-13 Figura 2-11 Gabarra de descarga (cuchara) ............ .......................... ............................ ............................ ............................ .................... ...... 2-14 Figura 2-12 Descarga de tolvas: Vista aérea................................... aérea................................................. ............................ ......................... ........... 2-15 Figura 2-13 Configuración de muestreo de carbón, caudal alto, as-received (en el estado que se ha h a recibido) ........................... ........................................ ........................... ............................ ............................ ......................... ........... 2-17 Figura 2-14 Configuración de muestreo de carbón, caudal medio-alto, as-fired (en el estado que entra al horno) ........................... ......................................... ........................... ........................... ........................... .......................... ............. 2-18 Figura 2-15 Máquina del muestreo del tipo de barrido primario ........................... ......................................... .................. .... 2-19 Figura 2-16 Disyuntor Bradford Pennsylvania montado sobre rodillos ............................ ................................... ....... 2-24 Figura 2-17 Modelo Bradford Pennsylvania con las placas de pantalla quitadas para mostrar el rotor ............ ......................... ........................... ........................... .......................... ........................... ........................... .......................... ................... ...... 2-25 Figura 2-18 Molino jaula ........................... ......................................... ............................ ........................... ........................... ........................... ....................... .......... 2-26 Figura 2-19 Vista en corte del granulador ........................... ......................................... ............................ ............................ ....................... ......... 2-27 Figura 2-20 Plano de proyecto del granulador ............................ .......................................... ............................ ........................... ............... .. 2-27 Figura 2-21 Trituradora reversible ........................... ........................................ ........................... ............................ ........................... ..................... ........ 2-29 Figura 2-22 Trituradora reversible para carbón ........................... ......................................... ............................ ............................ .............. 2-30 Figura 2-23 Tolva de recuperación de descenso de nivel ........................... ......................................... ........................... ............. 2-31 Figura 2-24 Vista en corte de la tolva de recuperación de descenso de nivel........................ 2-31 Figura 2-25 Problemas de almacenamiento en el exterior .......................... ........................................ ........................... ............. 2-32

B-44


Figura 2-26 Vista inferior de un distribuidor de carbón vibratorio ........................... ......................................... ................ .. 2-33 Figura 2-27 Vista esquemática de un distribuidor de carbón vibratorio en suspensión.......... 2-34 Figura 2-28 Separador magnético aéreo autolimpiable ........................... ......................................... ............................ ................. ... 2-35 Figura 2-29 Separador magnético suspendido .......................... ........................................ ............................ ............................ ................ .. 2-35 Figura 2-30 Opciones de montaje................................ montaje............................................. ........................... ........................... ........................... ................... ..... 2-36 Figura 2-31 Separador magnético aéreo estacionario.............. estacionario ............................ ............................ ............................ .................. .... 2-37 Figura 2-32 Operación del imán aéreo estacionario.............. estacionario ............................ ............................ ............................. ..................... ...... 2-37 Figura 2-33 Rectificador típico utilizado utilizado con los separadores electromágneticos ................. ................. 2-38 Figura 2-34 Típica compuerta deslizante de tipo rodillo ........................... ......................................... ............................ ................ 2-39 Figura 2-35 Típica compuerta deslizante de tipo agregado ........................... ......................................... ........................ .......... 2-40 Figura 2-36 Compuerta deslizante derivadora de agregado ............ .......................... ............................. ........................ ......... 2-40 Figura 2-37 Compuerta deslizante Seal Tite® ........................... ......................................... ............................ ............................ ................ .. 2-41 Figura 2-38 Sistema de eliminación de polvo en la estación de descarga de carbón ........... 2-44 Figura 2-39 Típico sistema de eliminación de d e polvo ........................... ......................................... ............................ ...................... ........ 2-45 Figura 2-40 Típicas opciones para la configuración de eliminación de polvo......................... 2-46 Figura 2-41 Opciones típicas de acceso al filtro ........................... ......................................... ............................ ............................ .............. 2-46 Figura 2-42 Opciones típicas de conexión de entrada ........................... .......................................... ............................. ................. ... 2-47 Figura 2-43 2-4 3 Cintas laterales corrugadas ............ .......................... ............................ ............................ ............................ ........................... ............. 2-48 Figura 2-44 Componentes del sistema de la cinta transportadora ............ ........................... ............................. .............. 2-49 Figura 2-45 Disparador auto-propulsado de la cinta ....................................... ..................................................... ....................... ......... 2-55 Figura 2-46 Disparador de cinta propulsado por cable ............ ........................... ............................. ............................ ................. ... 2-55 Figura 2-47 Eje paralelo del rectificador ............................ .......................................... ............................ ........................... ......................... ............ 2-57 Figura 2-48 Disposición del accionador de los engranajes del eje paralelo en ángulo recto ........................... ........................................ .......................... ........................... ........................... ........................... ........................... .......................... ..................... ........ 2-57 Figura 2-49 Accionador de los engranajes del eje paralelo en línea ............................ ..................................... ......... 2-58 Figura 2-50 Disposición del accionador de los engranajes engranajes de bisel de ángulo recto ............. 2-58 Figura 2-51 Accionador de los engranajes helicoidales de bisel ............................ .......................................... ................ .. 2-59 Figura 2-52 Accionador de los engranajes planetarios de bisel ............................ .......................................... ................. ... 2-60 Figura 2-53 Reductora motorizada de una transportadora de carbón ............................ ................................... ....... 2-60 Figura 3-1 Gráfico seccional de un granulador ............................ .......................................... ............................ ........................... ............... 3-28 Figura 3-2 Elementos de un programa de mantenimiento preventivo para las reductoras reductoras ... 3-49 Figura 5-1 Comparación entre reparación genérica y evaluación de substitución ................... ................... 5-2 Figura 5-2 Factores considerados durante el procedimiento de toma de decisiones .............. 5-3 Figura 5-3 Configuración para el ajuste de la alineación/tensión de la cinta separadora magnética.............................. magnética........................................... .......................... ........................... ........................... ........................... ........................... ....................... .......... 5-20 Figura 5-4 Patrones de contacto de los dientes ............................ .......................................... ............................ ........................... ............. 5-31 Figura 6-1 Proceso genérico para la identificación y resolución de problemas en el sistema (evaluación preliminar) .......................... ........................................ ............................ ........................... ........................... .................... ...... 6-2

B-45


Figura 6-2 Proceso genérico para la identificación y resolución de problemas en el sistema (identificación y resolución de problemas detallada del sistema)........................ 6-3

B-46


LISTA DE TABLAS Tabla 2-1 Visión general del acoplamiento flexible de metal ........................... ........................................ ....................... .......... 2-61 Tabla 2-2 Visión general del acoplamiento flexible de elastómero ............................ ......................................... ............. 2-63 Tabla 3-1 Mantenimiento preventivo recomendado para p ara las básculas de correa .................... 3-7 Tabla 3-2 Mantenimiento preventivo recomendado para los volquetes rotatorios automotores ........................... ........................................ ........................... ........................... ........................... ........................... .......................... ....................... .......... 3-9 Tabla 3-3 Mantenimiento preventivo recomendado para los volquetes de giro automotores .......................... ........................................ ........................... .......................... ........................... ........................... .......................... ....................... .......... 3-11 Tabla 3-4 Mantenimiento preventivo recomendado para un sistema de posicionador del tren ............ .......................... ........................... ........................... ........................... .......................... ........................... ........................... .......................... ....................... .......... 3-11 Tabla 3-5 Mantenimiento preventivo recomendado para las trituradoras móviles.................. móviles.................. 3-14 Tabla 3-6 Mantenimiento preventivo recomendado para la gabarra de descarga estacionaria ............................ ......................................... ........................... ........................... ........................... ............................ ........................... .................... ....... 3-16 Tabla 3-7 Mantenimiento preventivo recomendado para la gabarra de descarga (cubetas) .......................... ........................................ ............................ ........................... ........................... ............................ ........................... ......................... .............. 3-17 Tabla 3-8 Mantenimiento preventivo recomendado para las tolvas de descarga de carbón .......................... ....................................... ........................... ........................... .......................... ........................... ........................... .......................... ................... ...... 3-18 Tabla 3-9 Mantenimiento preventivo recomendado para el equipo de muestreo de carbón ........................... ........................................ ........................... ........................... ........................... ........................... .......................... ........................... ................. ... 3-20 Tabla 3-10 Mantenimiento preventivo recomendado para los disyuntores/compactadores disyuntores/compactadores... ... 3-25 Tabla 3-11 Mantenimiento preventivo recomendado para los molinos jaula ......................... ......................... 3-27 Tabla 3-12 Mantenimiento preventivo recomendado para los granuladores ......................... ......................... 3-28 Tabla 3-13 Mantenimiento preventivo recomendado para las trituradoras ............................ ............................ 3-30 Tabla 3-14 Mantenimiento preventivo recomendado para las tolvas vibratorias de recuperación de descensos de nivel ........................... ......................................... ........................... ........................... .........................3-31 ...........3-31 Tabla 3-15 Mantenimiento preventivo recomendado para los distribuidores de tolva de descarga ............................ ......................................... ........................... ........................... ........................... ............................ ........................... ........................ ........... 3-32 Tabla 3-16 Mantenimiento preventivo recomendado para los separadores magnéticos ....... 3-34 Tabla 3-17 Mantenimiento preventivo recomendado para las compuertas deslizantes ........ 3-35 Tabla 3-18 Mantenimiento preventivo recomendado para el equipo de eliminación de polvo ............ ......................... ........................... ........................... ........................... ........................... .......................... ........................... ........................... ..................... ........ 3-37 Tabla 3-19 Inspecciones de mantenimiento preventivo recomendadas para los sistemas de la cinta transportadora ........................... ......................................... ............................ ........................... ........................... ........................... ............. 3-39 3 -39 Tabla 3-20 Mantenimiento preventivo recomendado para los disparadores autopropulsados de la cinta ........................... ......................................... ........................... ........................... ............................ ........................... ................ ... 3-43

B-47


Tabla 3-21 Mantenimiento preventivo recomendado para los disparadores de cinta propulsados por cable............ cable .......................... ........................... ........................... ............................ ........................... ........................... ..................... ....... 3-44 Tabla 3-22 3-2 2 Tipos de termopares ............................ .......................................... ............................ ........................... ........................... ....................... ......... 3-46 Tabla 3-23 Visión general del programa de mantenimiento preventivo ............................. .................................. ..... 3-50 Tabla 4-Localización de fallos, mecanismos de degradación y las estrategias del M.P. para los componentes componentes del sistema sistema de manipulación de carbón carbón ........................... ..................................... .......... 4-4 Tabla 4-2 Tareas de M.P. y sus mecanismos de degradación para los componentes del sistema de manipulación de carbón ........................... ......................................... ............................ ........................... ........................4-18 ...........4-18 Tabla 4-3 Patrón de M.P. para los componentes del sistema de manipulación de carbón ... 4-30 Tabla 5-1 Reparaciones y sustituciones recomendadas para las básculas de correa ............ 5-6 Tabla 5-2 Reparaciones y sustituciones recomendadas para los volquetes rotatorios automotores .......................... ........................................ ........................... .......................... ........................... ........................... .......................... ......................... ............ 5-6 Tabla 5-3 Reparaciones y sustituciones recomendadas para los posicionadores del tren ..... 5-8 Tabla 5-4 Reparaciones y sustituciones recomendadas para una trituradora móvil ............... 5-9 Tabla 5-5 Reparaciones y sustituciones recomendadas para una gabarra de descarga estacionaria ........................... ......................................... ............................ ........................... ........................... ........................... ........................... ..................... ....... 5-10 Tabla 5-6 Reparaciones y sustituciones recomendadas para una gabarra de descarga (cubetas) ........................... ........................................ ........................... ........................... .......................... ........................... ........................... .......................... ............. 5-11 Tabla 5-7 Actividades de reparación y sustitución recomendadas para el equipo de muestreo del carbón ............ .......................... ............................ ........................... ........................... ........................... ........................... ....................... ......... 5-12 Tabla 5-8 Reparaciones y sustituciones recomendadas de los interruptores e interruptores híbridos ............ .......................... ........................... ........................... ........................... ........................... ............................ ...................... ........ 5-13 Tabla 5-9 Actividades de reparación y sustitución sustitución recomendadas para los molinos jaula .... 5-14 Tabla 5-10 Actividades de reparación y sustitución sustitución recomendadas para los granuladores ... 5-15 Tabla 5-11 Actividades de reparación y sustitución recomendadas para las trituradoras...... 5-16 Tabla 5-12 Reparaciones y sustituciones recomendadas para las tolvas vibratorias de recuperación de descenso d escenso de nivel ........................... ......................................... ............................ ........................... ..........................5-17 .............5-17 Tabla 5-13 Reparaciones y sustituciones recomendadas para los distribuidores de las tolva de descarga ............ .......................... ........................... ........................... ........................... .......................... ........................... ........................... ............... 5-18 Tabla 5-14 Reparaciones y sustituciones recomendadas para los separadores magnéticos .......................... ........................................ ........................... .......................... ........................... ........................... .......................... ........................ ........... 5-19 Tabla 5-15 Reparaciones y sustituciones recomendadas para las compuertas deslizantes ........................... ........................................ ........................... ............................ ........................... ........................... ........................... ...................... ......... 5-20 Tabla 5-16 Reparaciones y sustituciones recomendadas para el equipo de eliminación de polvo ........................... ......................................... ........................... ........................... ............................ ........................... ........................... .......................... .............. 5-21 Tabla 5-17 Reparaciones y sustituciones recomendadas para los dispositivos autopropulsados del disparador de cinta ............................ .......................................... ............................ ............................ ........................5-25 ..........5-25 Tabla 5-18 Reparaciones y sustituciones recomendadas para los dispositivos disparo de la cinta propulsados por cable ........................... ......................................... ............................ ............................ ............................ ....................5-26 ......5-26 Tabla 5-19 Pares de apriete recomendados ............................ .......................................... ........................... ........................... ................... ..... 5-36 Tabla 5-20 Tabla de interferencias ............................ .......................................... ........................... ........................... ............................ ................... ..... 5-40 Tabla 5-21 Ratio de conicidades ............................ .......................................... ........................... ........................... ............................ ....................... ......... 5-41

B-48


Tabla 6-1 Identificación y resolución de problemas recomendada para el sistema de manipulación / transporte de carbón ............ .......................... ............................ ........................... ........................... ........................... ............... 6-4 Tabla 6-2 Identificación y resolución de problemas recomendada para las básculas de correa del sistema de manipulación de carbón ........................... ......................................... ........................... ...................... ......... 6-5 Tabla 6-3 Identificación y resolución de problemas recomendada para las tolvas vibratorias de recuperación de descensos de nivel ........................... .......................................... ............................ ............. 6-12 Tabla 6-4 Identificación y resolución de problemas recomendada para los distribuidores de las tolva de descarga de tipo para-mount ............................ .......................................... ........................... ....................... .......... 6-13 Tabla 6-5 Identificación y resolución de problemas recomendada para los distribuidores de las tolva de descarga de tipo para-mount II ........................... ......................................... ............................ ..................... ....... 6-14 Tabla 6-6 Identificación y resolución de problemas recomendada para los separadores magnéticos del sistema sistema de manipulación de carbón ............ .......................... ............................. ....................... ........ … 6-16 Tabla 6-7 Identificación y resolución de problemas recomendada para las compuertas deslizantes ............ ......................... ........................... ........................... .......................... ........................... ........................... .......................... .......................... ............. 6-18 Tabla 6-8 Identificación y resolución de problemas recomendada para la eliminación de polvo/ equipo de supresión .......................... ........................................ ............................ ........................... ........................... ......................... ........... 6-20 Tabla 6-9 Identificación y resolución de problemas recomendada para los sistemas de la cinta transportadora ............ .......................... ........................... ........................... ............................ ........................... ........................... ....................... ......... 6-24 Tabla 6-10 Identificación y resolución de problemas recomendada para los disparadores de la cinta .......................... ........................................ ............................ ........................... ........................... ........................... ........................... ......................... ........... 6-31 Tabla 6-11 Matriz de identificación y resolución de problemas para las reductoras .............. 6-31 Tabla 6-12 Guía detallada de identificación y resolución de problemas para los acoplamientos mecánicos flexibles (engranaje y rejilla) ............................ ........................................... ......................6-35 .......6-35 Tabla 6-13 Guía detallada de identificación y resolución de problemas para los acoplamientos mecánicos elastómero (disco y diafragma) ..................... ................................... ........................6-38 ..........6-38 Tabla 6-14 Problemas metalúrgicos comunes e identificación y resolución de problemas ... 6-40 Tabla 6-15 Prácticas de instalación que conducen al fallo del acoplamiento flexible ............ 6-41 Tabla 7-1 Nivel de experiencia y conocimiento típico: Operadores del sistema de manipulación de carbón ........................... ......................................... ........................... ........................... ........................... ........................... ................. ... 7-1 Tabla 7-2 Nivel de experiencia y conocimiento conocimiento típico: Primera línea de supervisores supervisores ............ 7-2 Tabla 7-3 Nivel de experiencia y conocimiento típico: Primera línea del personal de mantenimiento del sistema ............ ......................... .......................... ........................... ........................... ........................... ........................... ................7-2 ...7-2 Tabla 8-1 Recursos del sector para la reparación, consultoría y formación del sistema de manipulación de carbón ............ .......................... ........................... ........................... ............................ ........................... ........................... .............. 8-2

B-49

Export Control Restrictions

The Electric Power Research Institute (EPRI)

Access to and use of EPRI Intellectual Property is granted with

The Electric Power Research Institute (EPRI), with major locations in

the specific understanding and requirement that responsibility

Palo Alto, California, and Charlotte, North Carolina, was established

for ensuring full compliance with all applicable U.S. and

in 1973 as an independent, nonprofit center for public interest

foreign export laws and regulations is being undertaken by

energy and environmental research. EPRI brings together members,

you and your company. This in cludes an obligation obl igation to ensure

participants, the Institute’s scientists and engineers, and other leading

that any individual receiving access hereunder who is not a

experts to work collaboratively on solutions to the challenges of electric

U.S. citizen or permanent U.S. resident is permitted access

power. These solutions span nearly every area of electricity generation,

under applicable U.S. and foreign export laws and

delivery, and use, including health, safety, and environment. EPRI’s

regulations. In the event you are uncertain whether you or

members represent over 90% of the electricity generated in the

your company may lawfully obtain access to this EPRI

United States. International participation represents nearly 15% of

Intellectual Property, you acknowledge that it is your

EPRI’s total research, development, and demonstration program.

obligation to consult with your company’s legal counsel to determine whether this access is lawful. Although EPRI may

Together...Shaping the Future of Electricity

make available on a case-by-case basis an informal assessment of the applicable U.S. export classification for specific EPRI Intellectual Property, you and your company acknowledge that this assessment is solely for informational purposes and not for reliance purposes. You and your company acknowledge that it is still the obligation of you and your company to make your own assessment of the applicable U.S. export classification and ensure compliance accordingly. You and your company understand and acknowledge your obligations to make a prompt report to EPRI and the appropriate authorities regarding any access to or use of EPRI Intellectual Property hereunder that may be in violation of applicable U.S. or foreign export laws or regulations.

Program: © 2006 Electric Power Power Research Institute (EPRI), Inc. All rights reserved. Electric Power Research Institute and EPRI are registered service marks of the Electric Power Research Institute, Inc.

Fossil Maintenance Applications Center (FMAC)

Printed on recycled paper in the United States of America

1013349

ELECTRIC POWER RESEARCH INSTITUTE

3420 Hillview Avenue, Palo Alto, California 94304-1338 • PO Box 10412, Palo Alto, California 94303-0813 USA 800.313.3774 • 650.855.2121 • [email protected] • www.epri.com

Chp

Recommend Documents