By N.Saravanan, Grinding Technology Department, FLSmidth Pvt Ltd., Chennai.
Purpose of bucket elevators * Bucket elevators are used to lift bulk material from one are a reliable and well-proven piece of equipment. * Bucket elevators are an ideal solution for vertical
height to another. They
transportation of bulk materials.
* Bucket elevators operate by using an endless belt or chain on which rectangular buckets are mounted. This belt or chain revolves between a top and bottom pulley and the buckets move with it. * At the bottom, the buckets pick up product fed into the elevator boot and at the top the product is discharged as the bucket turns downward over head pulley. * Along with each type of elevator, different styles of buckets have been developed which better suit the elevator or the materials to be handled.
Types of bucket elevators Centrifugal discharge elevator (CE) : This is the most commonly used type with bucket mounted on belt or chain for handling of free flowing or small particle. Continuous discharge elevators (CO) :
This type pf elevators are used for handling large lumps and material that cannot be handled by centrifugal discharge. The slow speed and gentle method of loading & discharging is the main feature. Positive discharge elevators (PO) : This is similar to centrifugal type except the bucket are end mounted with two strands of chain. Bucket speed is slower and suitable for light, aerated, sticky materials.
BELT BUCKET ELEVATOR INTRODUCION Bucket elevator belts and conveyor belts have different requirements.
For elevator service, you need to calculate the strength of the belt needed to support the weight of the bucket and the material being conveyed. In addition, you need to calculate the strength needed to handle the available horsepower. This is easy to accomplish. Since the weight of the buckets is essentially the same on both sides of the leg, the weight of the material is the difference.
Standard Elevator Bucket Punching
The type, size, weight, capacity, spacing, and projection of the buckets are critical factors in determining the correct belt for carrying the load and holding the buckets. The number, size and location of the bolts are also important.
Important advantages of belt bucket over chain bucket elevators * Lower wear and tear * Quiet operation * Higher specific conveying capacity * Lower power consumption * Most suitable for handling cement, raw meal, coal etc
TECHNICAL SPECIFICATION Equipment Material to be handled Bulk density Material Temperature Capacity (Design) C/C Distance Belt Belt strength Belt speed Bucket size
: Belt Bucket elevator : Raw meal : 0.8 to 0.9 T/M3 : Max. 120 0 C : 350 T/hr : 68.570 Mtrs : Steel Chord Belt 1050 mm width : 2000 kp/cm : 1.66 m/sec. : 900*335*5
TECHNICAL SPECIFICATION
Belt size Breaking Load Working load Belt strength Safety factor Bucket quantity Distance between two buckets Head and Tail pulley Dia Installed motor Casing size
: 1050 mm W * 141.50 M lg. : 185.800 KP : 15.500 KP : 2000 KP/CM : 12 : 306 : 460 mm : 1250 mm : 110 KW : 1310 W *2450 Box 780
TECHNICAL SPECIFICATION
BOLT SIZE
Torque
M 20 * 1.5
64 Nm/Bolt
M 24 * 2
1000 Nm/Bolt
M 30 * 2
2200 Nm/Bolt
DRIVES Auxiliary drive
: Geared motor- Greaves make GM 095, 5.5 KW, 56 output RPM with spiral Jaw coupling Make : MARK AEC
Safety Device
: Belt sway switch 220 V, 400 mA Electronic speed regulator
Painting
: 2 coats of primer after Sand blasting and 1 coat of final finish synthetic enamel paint by spray painting.
Material of construction Buckets
: 5 mm thick plate
– IS:2062
Head Casing
: 10 mm thick plate
- IS:2062
Boot Casing
: 16 mm thick plate
- IS:2062
Intermediate Casing : 5 mm thick plate
- IS:2062
SPARE PARTS LIST S.No
Item
Qty per assly
01
Buckets
306 Nos
02
Head shaft Bearing
2 Nos
03
Boot shaft Bearing
2 Nos
04
Belt
1 Length
05
Clamping device
1 Set
06
Bucket fixing bolt
2142 Nos
07
Tension Device Assly/ Bearing Bush
2 Nos
CONSTRUCTION DETAILS * Head casing * Lower head section * Head shaft assembly * Boot casing * Boot shaft assembly * special steel chord belt * Belt guide rollers * Buckets * Safety devices * Intermediate casing * Main drive ( Bevel Helical Gear box & Fluid coupling ) * Auxiliary drive * Maintenance platforms * Flanged inlet opening * Flanged dust collecting point at head casing
Erection The following * Storage at site * Safety * Preparation at site * Workmanship * Foundation checking * Guide frames erection * Fastening the side frame to the platform * Drive unit tied into elevator casing * Mounting of elevator belt * Mounting the buckets
Operational procedure The following check points should be reviewed before initial operation. * Head and boot shafts must be parallel to each other and pulleys in line * Casing plumb to within given tolerances * All bolts joining sections properly tightened * Reducer filled with oil to proper level * Correct motor rotation * Tighten all bucket moving bolts * All lateral supports in place and secured * Bearing lubrication * Guards should be provided * Inspection door should be closed * Check for interlocking controls & safety controls
Initial operation Particular attention should be directed to the following * Loud or unusual noise * Excess vibration * Bearing overheating * Drive unit overheating
MAJOR COMPONENTS MAINTENANCE CHECK LIST S.No 01
Item
Check point
Frequency
DRIVE UNITS Motor Gear Box
Lubricants, Heatup Lubricants, Heatup
Coupling
Alignment & Tightness of bolts
Geared motor
Lubricants, Heatup
Level switch
Electrical function
As per Manufactures Manuals
MAJOR COMPONENTS MAINTENANCE CHECK LIST S.No 02
Item
Check point
Frequency
Head casing Baffle plate
Wear out Position/ Fit out condition
Pillow Block in Head Shaft Assembly
Grease in bearing
Monthly
Every 3 months
General cleaning & Every 2 years Check for worn out of parts & replace if Required. Shaft assembly
Check for worn out Every 2 months parts
MAJOR COMPONENTS MAINTENANCE CHECK LIST
S.No
Item
Check point
Frequency
03
Take up
Tension in screw rods
Every 3 months
04
Inspection hole at boot casing
Material Weekly once accumulation during break down Foreign material in feed.
MAJOR COMPONENTS MAINTENANCE CHECK LIST S.No
05
Item
STUFFING BOX
Check point
Inspection of packing for wear & tear
Frequency
Monthly
Tightness of glands screws 06
BELT & BUCKETS
Tightness of Bolts & Nuts on Buckets
First 100 hours of operation
Inspection of belt for damage Every 3 months Inspection of bolts & tightness & completeness Deformed and damaged buckets to be replaced
MAJOR COMPONENTS MAINTENANCE CHECK LIST S.No
Item
07
Clamping Device
Check point
Tightness of bolts with torque wrench
Frequency
After 50 hours of operation After another 2 weeks After another 6 weeks After another 3 months
LUBRICATION CHART S.No
Lubrication point
Lubricant Specification or make of lubricant Grease
Qty
Frequency
Method of application
Servogem 2 of Indian oil
20 Gms
800 hours/ By Grease as and when Gun/ By required hand
01
Antifriction bearings in Plummer block
02
Motor
Grease
Servogem 3
20 Gms
Every year 10000 running hours
Grease Gun
03
Gear box
Lubricati ng oil
Servomesh SP 320 of Indian oil
100 Ltrs
6 Months
By pouring through oil plug
04
Fluid coupling
Lubricati ng oil
05
Geared motor
Lubricati ng oil
As per Manufacture’s Manuals
Troubleshooting Please see the “ Troubleshooting.doc “ file for various troubleshooting methods. This file is given along with Belt bucket elevators presentation
OPERATION OF BELT BUCKET ELEVATORS
HEAD PULLEY & BOOT CAGE Head pulley
Boot cage
BELT BUCKET ELEVATOR’S DRIVE
INCHING DEVICE This is normally a low speed geared motor. It permits low speed drive for inching and turning of large size and high speed bucket elevators in case of maintenance, inspection and test run
Jaw clutch
BELT & BUCKETS
TENSIONING DEVICE
BELTS & BELT JOINING METHODS
Bucket on belt attachment
Various types of Buckets joints
BUCKET SIZE & PUNCH STYLE
BUCKET SIZE & PUNCH STYLE
BUCKET SIZE & PUNCH STYLE
BUCKET SIZE & PUNCH STYLE
Advantages of Fluidomat Fluid Couplings:
Wear-free power transmission because of absence of mechanical connection between the input and output elements.
No-load start-up of motor irrespective of machine load. Motor peak torque utilized for machine acceleration.
Motor selection to operating HP rather than starting loads. Saving on energy cost and capital cost.
Simple control of maximum or limiting torque by easy variation of oil filling.
Added protection for motor and driven machine by limiting torque to a predetermined safe value.
Automatic unloading of prime mover in case of any sustained overload, by blowing-off of fusible plug on coupling, thus draining out oil.
Advantages of Fluidomat Fluid Couplings: * Automatic synchronization and load sharing in case of multi-motor drives * Effective dampening of shocks, load fluctuations and torsional vibrations. Helpful in improving the drive duty conditions in machines subjected to shock loads, frequent load changes, startups and reversals.
* Smooth and controlled acceleration of driven machines. Important for machines such as conveyors, wire drawing and textile machines. * Step less speed variation in wide range obtained in scoop type fluid couplings. * Continuous clutching and declutching of large drives obtained from SC type couplings. * Economy on machine and drive designs. * Energy saving
