ABSTRACT This report covers the experience, which I got in "SUMMER TRAINING" Firstly I was introduced in the Cement Mill & Packing Plant section. In operation of cement mill the clinker first come from the clinker storage piles to the clinker hopper through the deep bucket conveyor. Then transferred to the polycom, where it crushes and then fed to cement mill for further grinding and mixing. There is also a recirculation system, which again feed the coarse material to the polycom. The very fine material from cement mill is then stored in the cement silo. From the cement silo the cement is fed to the packers, where it filled in the bags of 50 kg. Then I was introduced in the Raw Mill & Coal Mill section. In the field I got the knowledge of various Instruments like pressure transmitters, temperature transmitters, pressure gauge, proximity switches, flow switches, level switches, temperature sensors like RTDs & thermocouples, weigh feeders, metal detector & metal separator etc. The brief discription of various field Instruments are given seperately.
1
CHAPTER 1 ABOUT PLANT
1.1 INTRODUCTION Aditya Cement is a unit of Grasim Industries Ltd of Aditya Birla group. Aditya cement the plant with 1.5 million tones per Annum capacity was commissioned in a record time in March 1995. Aditya Cement has adopted the most modern dry process technology with sophisticated instrumentation ensuring uniform quality, thus making it a Cement plant of 21st Century. The product “BIRLA PLUS” is one of the market leaders and continuous to consolidate it’s leading position in the market. The total project cost of Aditya Cement was Rs.430 Corers. Aditya cement is one of the most modern cement plants with all its major equipments supplied by the world major and renowned Krupp Polysius of Germany and Quality Control systems by Gamma Matrix of USA. FIG 1. ADITYA BIRLA CEMENT PLANT
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CHAPTER 2 WEIGH FEEDER As the name suggests it feeds material to the next process while weighing the material in proper quantity. It is just like any conveyor belt but the belt speed is varied by weighing the material so as the feed to the next process remains constant. The material on the belt is weighed by load cell under the belt and the speed is varied by the speed control of dc motor. The signal from the load cell and speed (measured by Tachometer) are multiplied in microprocessor card. The resultant shows the feed in TPH. Further this TPH is compared by a set point given externally. Now the microprocessor controller generates the error which is amplified and given to the Thyristor controller, which controls the power fed to the DC motor which in accordance varies the speed of the belt with the gear box and hence control the feed.
2.1. SPECIFICATIONS • Microprocessor: 89c51 • Memory:
64K EPROM, 8k RAM with battery backup.
• Display:
2 lines*16 character LCD.
•
Operating temperature: -10 C to +50 C.
• Digital output: 4 relay contacts, 220Vac, 2 Amp. 2 o/p can be assigned as totalizer outputs. • Analog output: 0-20mA/4-20mA isolated o/p corresponding to any one function. - Actual federate
3
- Belt load - Belt speed - Weigh feeder set point. • Impulse o/p: 2-relay output corresponding to Totalizer1 & Totalizer2 • Interfaces: 2 digital I/O card (F-866) & 3 Analog I/O card (F-868) can be interfaced. • Power supply: 220Vac +/- 15%. WEIGH FEEDER
FIG. 2.1
4
2.2 LOAD CELL DATA measuring range
: 0 to 28 mV.
• supply voltage
: internal 12 V,110 mA.
• Cable
: 6 core, shielded.
2.3 TACHO DATA • input signal
: max. 15 V.
• measurement range : 10-2500 Hz,12V. • supply voltage
: internal 12 V,10 mA.
2.4 MODES OF OPERATION MODE
SETPOINT
Interlock-gravimetric Interlock-volumetric Deinterlock-gravimetric Deinterlock-volumetric Local mode
External External Tuc-4 Tuc-4 LCS TABLE 2.1
OPERATION
Regulated Un-regulated Regulated Un-regulated Un-regulated
2.5 OPERATION ON WEIGH FEEDER 2.5.1. ZEROING OF WEIGH FEEDER Belt related influences on the belt load can be compensated by means of zero correction. To do this , correction process is stated belt running idle. The zero correction value, with which the belt load is set off ,is calculated automatically after zero correction. Condition : • System in local/ deinterlock-volumetrick. • Belt running Display:
5
LED over >0<
flashing.
During one belt revolution the zero point is corrected in order to improve the measuring precision. The deviation from the zero is measured and stored with plus or minus prefix. This value is now considered with each measuring of momentary load. Zeroing should be affected at setting in operation, change of module, mechanical modification and if the belt gets dirty. 2.5.2. CALIBRATION Condition: Weigh Feeder in stop condition and Belt must be empty. • Press ECS & CL key simultaneously. •
Now TUC-4 will ask for password. Enter the correct password & press HORIZONTAL (enter) Key. If password is correct then display show-Y.
•
Scroll down to calibration with VERTICAL key press & enter key. TUC-4 will ask for RE_CALIBRATE?. Press enter for calibration.
• Display will show DEADLOAD in upper line while some count is displated in lower line. To tare this value simply presenter key. Now display will indicate 0000 d in lower line. • To move for SPAN calibration, press VERICAL key.
2.5.3. DROP TEST An exact calibration of the weigh feeder is possible only with original material since all
influences concerning belt, measuring system and material
characteristic are considered. 6
A. First WF is started and let it run for a while in order to have mechanical equipment and electronics in operational temperature. B.
With totalizer1 (∑ 1) reset a sufficient quantity is taken and this material is
reweighed on a static scale of an accuracy of better than 0.1%. The correction can be achieved by entering net Tachometer frequency which can be calculated as under: New Ft = old Ft * (value of ∑ 1/ actual material weight) PLC: TUC-4 has an in buit PLC, that is used to control the digital input, output & internal memory flags (marker). The PLC continuously operates on the control program in the following sequence: - Transfer hardware I/P into the RAM. -
Execute instruction in the control program (SPSS).
- Transfer output process image to the hardware outputs.
2.5.4. INPUT, OUTPUT & MARKER These are one bit variable that can have LOW or HIGH status. Inputs are signal from outside to the control program, and outputs are signal from the control program to the external system. Markers are internal variable and serve as memory within the control system. They are available outside the control system when they have been copied onto outputs.
This diagram depicts the basic process of cement blending and storage.
7
FIG. 2.2
CHAPTER 3 8
BELT WEIGHER It is a system used to measure the feed of material to any m/c through belt conveyor. We are using it in many location. In Raw mill it is being used.
3.1 PRINCIPLE OF OPERATION Mass of material flowing on BC is sensed by load cells. Loadcells are located under the belt in such a way that the force acting on the load cell is equal to amount of material on the 1/2 meter of the belt, hence it is represented in Kg/m. The belt speed is sensed by a speed transducer which is calibrated to give belt speed in m/sec. The integration of belt loading and belt speed will give you total material, where as multiplication of two gives instantaneous flow rate in Kgs/sec. Various indicators totalizers, alarms and control signals can be generated from flow rate signal. Flow rate = Belt loading*Belt speed= Kg/m*m/sec = Kgs/sec Flow rate in tones/hours = Kgs/sec*(3600/1000) Total material conveyed= Int. of (f/v)dt from 0 to l f = Belt loading l = distance between rollers v = belt speed It comprises of following 1.Transom assembly 2.loadcell 3.speed transducer 4.Main processing unit
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3.1.1.TRANSOM ASSEMBLY Three segment precisely machined roller having life lubricated seated bearing with labrine set form assembly. Transom assembly could be of single or multi rollers depending upon the accuracy required 3.1.2. LOAD CELL Precision strain gauge load cells are used in SANCO belt weigher. Aluminum along with labrine assembly makes the enclosure totally dustproof. Material weight is transferred to load cells through labrine, precision loadcell gives o/p in mV, which is processed in signal conditioner. Amplified o/p of load cell is transmitted to main processing unit. 3.1.3.TRANSDUCER SPEED Sanco has developed a special high resolution digital speed transducer. The o/p of this transducer is proportional to belt speed. These speed transducer senses the speed through contact wheel, or it can installed on extended shaft motor. 3.1.4. MAIN PROCESSING UNIT This unit contains following types of cards for manipulation of signals 1.Power supply for +5V(m-505) As the name suggest it generates the power supply for system. Since unit is based upon microprocessor so it need +5V supply free from ripple. 2.I/O board (m-501) This receives the techo output and 4 to 20 mA from local panel indicator of load signal here these are conditioned. 3.ADC card (m-502)
10
Here load signal is converted into digital form and given to processor card and o/p generated by processor card is converted into analog form for CCR indication. 4.Processor card (m-503) Here speed signal and load signal are multiplied in digital and o/p also in digital form is generated which the feed rate. Now this o/p goes to ADC card which converts it into analog form for CCR. 5.Isolated 4-20 mA Generated (m-504) This generates another 4-20 mA signals which are electrically isolated and sent for local indicator.
3.2 CALIBRATION PROCEDURE 1.Demand perticular belt in local and run it empty. 2.Tacho shaft must be moving , so that we get the tacho signal for computing TPH in main panel. 3.We must get 0.0 v dc at TP1 & TP2for both the load cells. If not getting adjust voltage by pot 1 & pot5. 4.Alongwith above voltages , we have to set 4 masignal of load cell through POT 3. 5.Now at main panel first press enter & see. There must not be any fault. -
Press enter key system will ask for code no.
- This will be displayed at counter 1 position. - Use data enter key and enter code 0100 - Press enter key.
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6.System will ask whather we went to run tare program(At counter 1). - 'No' will be displayed at counter - 2 position - For zeroing we have to run run Tare programme. For Yes(To run Tare programme) Press any data key.
-
- Display would change from'No' to 'Yes' - Press enter key to run programme. 7.Now tph indication will become 0.00 and counter 1&2 will be steady. 8.After one minute of starting the Tare programme check 4 ma O/P to CCR for empty belt. IF not 4 mas , adjust through POT in card M-504.
3.3 SPAN SETTING 1-Now put the Test Weight on each side of weighing - zone. 2-We have to check voltages at TP3 & TP4 AS PER BELOWBelt Capacity
Voltages
•
600TPH
3.0 V DC (Test weigh - 8 each side)
•
400TPH
3.0 V DC (Test weigh - 8 each side)
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CHAPTER 4 TEMPERATURE MEASURING INSTRUMENTS 4.1 THERMOCOUPLE The thermocouples are based on Thermo-electric effect is known as Seeback effect. A thermocouple consists of a pair of dissimilar metal wires joined together at one end (sensing or hot junction) and terminated at the other end (cold junction or reference), which is maintained at a known constant temperature (reference temperature).When a temperature difference exists between the sensing junction and reference junction an EMF is produced that causes the current to flow in the circuit. When the reference junctions terminated by a meter, the meter indication will be proportional to the temperature difference between the hot junction and the reference junction. Various types of thermocouples are: TYPE
MATERIAL USED J
Iron-constantan
K
Cromel-Alumel
R/S
Platinum-Rhodium
E
Chromel-Constantan
To ensure long life in its operation environment a thermocouple is protected in an open or closed metal protecting tube or well. Since the thermocouples usually in a location remote from the measuring instrument, connections are made using special extension wires called compensating lead.
13
THERMOCOUPLES IN CEMENT PLANT
FIG. 4.1
4.2 RESISTANCE TEMPRATURE DETECTOR (RTD) They employ a sensitive element of extremely pure Platinum, Copper or Nickel wire that provides a definite resistance value at each temperature with in its range R(t)=R(ref) (1+ $t) R (t)= Resistance of conductor at temperature "t" R (ref)= Resistance at reference temperature $= Temperature coefficient. Almost all metals have a positive temp. Coefficient of resistance so that their resistance increases with an increase in temperature. Some materials such as carbon and germanium have negative temperature coefficient of resistance, which signifies that their resistance decreases with increase in temperature. PT100 is an example of RTD that has 100 ohms resistance at zero degree resistance. Type of RTD -- PT-100,
14
4.3. KILN SHELL TEMPRATURE SCANNER It is used for precise evaluation of the refractory's condition at all times. Evan if a single brick falls out its location can be identified as a hot spot. It uses principles of non-contact temperature measurement. It measures an object naturally emitted infrared radiation to determine its temperature. Infrared radiation enters through a sensor window. A mirror rotating at 19.6 Hz receives infrared energy and reflects it on to a lens, which focuses it on to a thermoelectrically cooled detector. The detector receives energy from the target for every 90 degrees of rotation of the mirror. Rest remaining 270 degrees of rotation are used to self calibrate the instrument by reflecting infrared energy of two internal temperature indicators on to the detector. The incoming signal is sampled at 20 kHz, converted from analog to digital and translated by an internal microprocessor into temperature. For every rotation of mirror 256 measured values are possible which can be averaged to 128 or 64 measured signals. For data transmission an RS232 interface with switchable baud rate is available and allows transmission of pre-processed data to a PC.
4.4. RADIATION PYROMETER It is also detects the heat radiation emitted from the object. These radiation are finally converted into temperature using the necessary optics and electronic circuitry.
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CHAPTER 5 PRESSURING MEASURING INSTRUMENTS
5.1. PRESSURE TRANSMITTER Pressure is transmitted to a silicon pressure sensor through a diaphragm and a liquid filling. The pressure causes the sensors measuring diaphragm to distort. The resistance of four doped pizeo resistors in a bridge circuit in the measuring diaphragm changes. The change in resistance generates an o/p voltage in bridge circuit that is proportional to the measured pressure. The voltage is converted into periodic signal by an amplifier in a voltage/frequency convertor. A micro controller evaluates the signal, correct it with respect to linearity and temperature before passing it on to D/A convertor which gives 4 to 20 mA. Differential pressure is transmitted to a silicon pressure sensor through a diaphragm and a liquid filling. The differential pressure causes sensors measuring diaphragm to distort. The electronic circuit is same as that of pressure transmitter. The differential capacitance between the sensing diaphragm and capacitance plate is converted electrically to 4 to 20 mA. The process pressure is transmitted through an isolating diaphragm and oil fluid to a sensing diaphragm. The reference pressure is transmitted similarly to the other side of sensing .The displacement of sensing diaphragm is proportional to pressure difference across it. The position of the sensing diaphragm is detected by the capacitance plate on both sides of the sensing diaphragm. This capacitance is further treated to give 4 to 20 mA.
16
5.2 CALIBRATION OF PRESSURE TRANSMITTER 5.2.1. PREPARATION OF DEAD WEIGHT TESTER A) Top up the oil in the oil reservoir of Dead weight Tester (DWG). B) Keep lid open of oil reservoir. C) Open the isolation valve. Keep the screw at the maximum out position. D) Operate the screw in and out to remove the air bubbles from the oil. E) Release some oil from port before fixing the gauge. To ensure no air bubble in oil. F) Close the isolation valve tightly. 5.2.2. CALIBRATION A) Fix the test pressure Transmitter on the dead weight tester. B) Put the dead weights according to the range of the pressure Transmitter on the piston. C) Move the screw slowly inside so that the piston moves up and rotates freely on its axis when rotated and see red mark just visible margin. D) At this stage the test switch should operate and see the contact. E) Slowly reduce the pressure. 5.2.3 RECORDING OF MEASUREMENT: Note down the readings observed, during calibration in Equipment Calibration Report with accuracy of +/- 0.1 %. 5.2.4 STICKING OF CALIBRATION TAG :
17
Fix the calibration tag duly filled on the pressure Transmitter after calibration.
CHAPTER 6 LEVEL MEASURING INSTRUMENTS 6.1 NUCLEONIC LEVEL SENSOR These provide noncontact method of level monitoring. It utilizes the attenuation principle of gamma rays transmission. Since it does not come in contact with material so it is not affected by the physical conditions. Such type of level sensors have a source of gamma radiations and a detector. The source and detector are mounted opposite to each other. The source utilizes Ceasium137 or Cobalt 60 as a source of gamma radiations. The gamma radiation sees through the vessel wall and detector converts nuclear gamma ray radiations into electrical quantities related to level (generally in form of a counter) When the level of the material in the vessel exceeds the height of the gamma beam the beam is attenuated and the output relay switches. Intensity of the radiation received by the detector varies (1) in proportion to the thickness of the material between source and the detector. (2) inversely proportion to the square of the distance between the source and the detector
18
6.2 ULTRASONIC LEVEL SENSOR The emitter in the sensor is excited electrically and it sends an ultrasonic pulse in the direction of the surface of the product which partially reflects the pulse. The echo is detected by the same sensor and then converted back into electrical signal. The time between transmission and reception of pulse is directly proportional to the distance between the sensor and product suface. The distance is determined by the velocity of sound "c" and the run time "t" using the formula d=c.t/2
(where c=320mtr/sec)
6.3 RF TYPE LEVEL SENSOR It includes an electronic unit and a probe. The electronic unit consists of an oscillator, a detector and a output relay which is controlled by the detector .The probe contains an inner(active)section and outer section(shield),insulated from each other and from the vessel ground. The oscillator generates low power RF signal which is used to provide signals equal in frequency, amplitude and phase to both, active section and the shield section of the probe. The signals provided to shield held constant. The detector is then used to compare the fixed shield signal with the active signal which varies with the dielectric constant of the material in contact with the probe .Difference in signals compared by the detector cause the output relay to activate.
19
6.4 CAPACITANCE TYPE LEVEL SENSOR Capacitance is formed between the sensing probe and the vessel wall/ground. When the material level changes there is corresponding change in the value of this capacitance because of the difference in the dielectric constant of the material and that of air. The electronic circuit converts the capacitance into DC signal which causes the relay to operate.
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CHAPTER 7 ELECTRONIC SPEED SWITCH
The electronic speed switch is ideally suited to monitor any repetitive motion, whether rotational or translational. In fact it is best suited for the speed monitoring of critical element of any material handling system, such as belt /screw conveyor, elevators, crushers, drag chain, rotary feeders etc. It senses the under speed /over speed conditions in the systems by non contact method and provides out put contacts for protection, control and interlock purposes. Application include ,detection in jamming in feeders, sequential interlocking on conveyors, detection of blade breakage in reclaimer chain, motion detection, fan speed monitoring etc. The speed switch comprises of a sensor probe and a monitor unit. A sensor probe is a non contact type inductive proximity switch, which picks up speed information, evalutes it and provides necessary outputs. The proxi potted probe is dust and water tight and the monitor in steel sheet or cast Alluminium, epoxi printed housing is dust tight pulses are clearly visible through the transparent window on cover. The terminal strip which can accept conductor up to 2.5 square mm, speed setting knob, the range switch and the bypass trip setting knob all are accessible only after opening the cover. Proper markings are provided for test points and external conditions. Different housings are available to suit individual requirements. The sensor probe are available suit individual requirements. The sensor probe is available in threaded housing, either thermoplastic or metallic with two clamping nuts, maving size as per selection table. 21
With the unit connected the "SUPPLY ON" and "RELAY ON" LED light up as the supply is switched on During the initial bypass time, which is initiated by supply on the output relay remains picked, independent of speed. It is further held only. if the speed reaches the set value, before expiry of the bypass. The relay then drops whenever the speed falls below the set value. it can again pick up, if the system speed picks up to healthy running condition. The pulses LED on and off in response to the actuation and deactuation of the probe.
7.1 SELETION OF PULSE RATE The monitor units evaluates the duration between successive pulse from the probe output. Consequently, the tripping time is dependent upon available pulse rate. For example at a pulse rate of 12p/m, the duration between successive pulse is 5 sec
and hence the tripping
time slightly more than it. Therefore,it is
preferable to choose number of flags such that at a given speed, the pulse rate falls appro. between 60p/m to 180p/m, giving a tripping time of 1 sec and 1/3 sec respectively. Generally, the number of flags chosen are 1,2or 4 of practical convenience. Different types of probes are used for the according to the application. Infrared, inductance type, capacitance type, MSP3 etc are the probes used for different distances and for different m/cs. For example we use MSP3 probe in bucket elevators for ZSS signal due to its strength and high temperature resistance. We generally use inductance proximity switches where we have to sense metal if we need to sense material then it is good to use capacitance type probes.
22
CHAPTER 8 METAL DETECTOR
In our plant LS is queried from mines. So it may happen that some metal pieces can come together with .If these metal pieces allowed to pass through machinery it could damage machinery. So to detect metal, detecting device is used on the belt weigher which senses the metal and divert the material to right side for short duration.
8.1 DESIGN The metal detecting device consists of two components the probe and the amplifier, both which are interconnected with one coaxial cable. The probe will be furnished to match your conveyor belt width. There is a single probe and a tendom probe available. The planer single probe will usually be mounted underneath the conveyor belt. The tendom probe consists of two planer probes one of which will be mounted underneath the conveyor belt while the other probe will be held above the belt by special support.
8.2 FUNCTION A high frequency AC voltage is fed from the amplifier to a coil in the probe via a 75 ohms coaxial cable. This generates an electromagnetic field. If a metal piece comes into this field, induction currents will be generated that drain power from oscillator.
23
If depending upon the selected sensitivity an unwanted metal piece in the conveyed material is identified by the electronics. In the amplifier, the o/p relay will switch to its other state for about 0.5 seconds. The o/p relay has two potential free NO/NC contacts that are wired to the terminal strip. These contacts can be used to stop the conveyor belt or to activate an injection device.
8.3 CALIBRATION PROCEDURE 1- Operating state selector switch 1 sensitivity 2-
2.0
Check the voltage between m3(signal point ) & m1(graund) and it
would be 6.66 v dc by pot r 44. 3-
Check the voltage between m2 & m1 it should be between 5 -7 v dc
otherwise changed with pot r8. 4-
Check the voltage between m4 & m1 it should be between 14 v dcv
dc otherwise changed with pot r12. 5-
Check the voltage between m5 & m1 it should be between 5 v dc v
dcv dc otherwise changed with pot r13. 6-
Put the probe at sensitivity port and set 0.0 volt by use of r 32 pot.
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CHAPTER 9 OPACITY MONITOR Opacity refers to the amount of light being scattered or absorbed by particles in the light beam path. An Opacity or dust density monitor measures the particulate level of stack emissions. One of the most common reasons for measuring opacity is comply with Environment protection (EPA) or the national requirement. A transmissometer is used to ensure that the stack opacity does not exceed these prescribed limits.
9.1 SYSTEM DESCRIPTION The OPM 2000A Opacity/Dust monitor consists of a transmitter receiver (transceiver) module, a retroreflector module and a control room unit (CRU). The transreceiver and retroreflector modules are mounted on the stack
directly
opposite each other. The transceiver projects a controlled beam of light across the stack. Particles in the gas stream cause a certain amount of light to be scattered and absorbed. This amount varies depend upon the particulate content of the gas stream an the type and the size of the particles. The corner tube bounces the light back along a parallel path to the transreceiver. The light then strikes a detector, which converts the light into a voltage that can be processed. The detector signal is amplified by an independently powered detector/amplifier board. The amplified signal is then digitized and transmitted to the CRU calculates opacity, sends commands to the transceiver, and provides an operator interface for the system. Because the beam passes through the stack twice (once in each direction) the resulting value is double - pass transmitted measurement. By passing through the 25
smock twice, sensitivity to opacity level is increased and alignment of the modules is made easier. The measurement value is compared to a reference value previously determined with no smoke in the light path. The resulting ratio is a transmittance value for the measurement path. This ratio can then be converted to units of optical density and stack exit opacity and dust concentration.
9.2 TRANSCEIVER MODULE The main component of transceive module of optical assembly air lens assembly and blower motor. The three components are mounted to monitoring plate and enclosed in weather housign. The optical assembly contents all transceiver optical and electronic components.
9.3. OPTICAL SYSTEM The light source for the optical system is a special long -life incandescent lamp. The lamp contains a built-in that directs light forward to a 1/8-inch diameter cross-haired aperture. Two liquid crystal windows (LCW) function as shutters that either block or transmit light. The LCWs are made of a normally translucent film when an electric current is applied to the file, the LCWs becomes transparent, allowing light to pass. The sequence and duration that the LCWs turn on or off are under software control. Each of four-voltage measurement is produced by a different combination of LCWs being on or off during the measurement cycle. Each measurement cycle consists of four different light path modes, each of which produces different voltages. The four measurement modes STACK, AMBIENT, DARK and LAMP, as follows:
9.3.1. STACK MODE
26
During the stack mode, the light beam passes through the beam solitter. The beam travels through the objective lens,LCW2 (center segment), an air window, across the stack, into a retroreflector. The retroreflector, by means of a corner tube, reflects the light through the srack, air window, LCW2 and objective lens. The beam strikes the beam splitter and is reflected in the detector .The detector (a photo diode) converts the light to a voltage that can be processed. The desired spectro response is achieved by a narrow green band filter on the detector.
9.3.2 AMBIENT MODE In the ambient mode LCW 1 blocks the lamps light preventing it from ever reaching the detector. While the lamp light is blocked,LCW2 allows ambient light to reach the lens, solitter and the detector.
9.3.3. DARK MODE In the dark mode both LCWs are off. The voltage measured during the dark mode is used to compensate for any light leakage with in the transceiver.
9.3.4. LAMP MODE The lamp mode allows the OPM2000A to compensate for the effects of an aging bulb. In this mode the inner segment of LCW2 is off stopping the beam from reaching the air window, and preventing the entrance of ambient light. The lamp beam is directed through LCW2's outer ring segments to an internal retroreflector, located behind the ring segment. The beam is then directed to the beam splitter and into the detector. The detector voltage is used to compensate for the aging of the lamp and the components, as well as power fluctuations.
27
FIG. 9.1
CHAPTER 10
28
VIBRATION MONITOR
VIBROCONTROL 1000 Vibration monitoring system is used to monitor and measure machines vibrations. The system measures the rms value of vibration velocity in accordance .
10.1 PRINCIPAL OF OPERATION Electrodynamic vibration sensors converts mechanical motion into an analoge electrical signal. The o\p voltage supplied by the sensor is proportional to the vibratoion velocity. The ac signal supplied by the sensor is amplifired rectified and adapted to the measuring span in the measuring or monitoring amplifier. At the o/p of these ciruits, a dc voltage of 0 to 10 volts or a dc current signal of 4-20 ma is available, which can be fed to field mounted i/o cards, which is given to PLC system, further it is displayed on coros monitor. Each system has 5 calibrated measuring ranges for vibration velocity or vibration displacement. In addition the measuring amplifier enables 2 alarm limits to be set, a power relay is provided for each of the alarm limits, the throw-over contacts of which can be used to trip an alarm or shut-down the machine concerned. A supplementary ok relay monitors the power supply and the sensor circuit by means of a dc current passing through sensor coil.
10.2 SPECIFICATIONS 1. measuring principle:
Electrodynamoic sensor
2. direction of measurmemt :
horizontal +/- 5 deegree verticle +/- 20 degree verticle +/- 105 degree
29
3. no-load voltage :
100 mv/mm/s (ac) 50 mv /mm/s (ac)
4. natural frequency:
8 htz, 15 hz
5. working frequency:
10 to 2000 hz
CHAPTER 11
30
GAS ANALYSER 11.1 PRINCIPLE O2 MEASUREMENT - PARAMAGNETIC TYPE CO MEASUREMENT - INFRARED TYPE DUAL CHANNEL SAMPLE (1)
SAMPLE
SOV 2-5
ON
SAMPLE (1)
EXHAUST
SOV 2-4
ON
SAMPLE (1)
CLEAN
SOV 2-2 &2-1
ON
11.1.1 DEFINITION In order to obtain accurate results the analyser must be callibrate d with a gas of accurately known concentration of zero callibration gas as given or specified on the Test Certificate of Gas Cylinder supplier. ZERO GAS
:
CALLIBRATION GAS
100%Nitrogen :
CO O2 Bal. Nitrogen
Channel 1: Oxygen Channel 2: Carbon Mono Oxide
11.2 PROCEDURE 31
A) ADJUSTMENT OF ELECTRICAL ZERO, USING ZERO GAS -Open gas cylinder and set pressure to < 1.5 bar by regulator. -Turn the select knob to zero gas at panel. -Set the sample flow in rotameter between 0.3 to 1 ltr ./ min.
SELECT CHANNEL NO. -1 (OXYGEN ) & CALLIBRATE IT. KEY TO BE PRESS DISPLAY
COMMENT
FUNCTION
0-1(xxxx)
Channel - 1 selected i.e. Oxygen for zero
ENTER
CODE 0
Enter code 10 by pressing up & down keys
ENTER
O-1(xxxx)
Actual zero level will be displayed Wait at least the entering furnishing period.
If the actual & nominal values-levels agree, next function can be selected using function keys. If the two values disagrees Enter 0-1(0.00) this automatically adjusts zero for o2.
press function keys to finish the adjustment mode.
11.3. SPAN ADJUSTMENT
32
KEY TO BE PRESS DISPLAY
COMMENT
FUNCTION
0-1 (xxxx)
Channel - 1 selected i.e. Oxygen for zero
ENTER
S-1 (xxxx)
Enter the correct code,
if not already
entered. ENTER
S. -1(xxxx)
Feed the actual concentartion - level Wait at least the flushing period.
ENTER
s.-1
If necessary , enter the true gas set-point. (Taken from manufacturer's paper on gas bottle.)
CHAPTER 12 SAFETY 33
Safety is utmost requirement for any plant because by taking proper measures against accident we can increase the profit of company and can save manpower from injury. Safety is totally an Egineering system. According to Bell Telephone inotto “ No job or service is so urgent that we cannot take time to perform our work safely” “ Safety an attitude, a state of mind that must be sustained in work environment”
12.1 ACCIDENT Unwanted undesirable events which has potential to hit injury to a person or a loss of property” 12.1.1. CAUSE OF ACCIDENT Unsafe act Unsafe condition
85-90% 10-15%
UNSAFE ACT:
UNSAFE CONDITION:
Lack of knowledge No provision of safety attachment • Inattention Leakage of oil, water, steam etc • Hurry Dust fumes & temperature • Violating safety Condition of ladder/scrapped/stair • Overconfidence • Worry & hypertension • Lack of experience 12.1.2. HOW TO PREVENT ACCIDENTS? •
• Use of proper safety devices 34
• • • • •
Toxic & inflammable materials store process to be isolated Preventive & periodically maintenance of equipment By training of employees through video, audio , lectures etc To motive the people to make active part for creating awareness in the plant Use of personal protective equipment
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CHAPTER 13 PERSONALITY DEVELOPMENT ACTIVITIES & TRAININGS
During the period of ‘TECHNICAL TRAINING’ I had undergone through various technical training programme as well as personality development Programmes, that help me to develop myself as a professional as well as social acme. Some of them are:
13.1 TECHNICAL TRAININGS 1. Maintenance of electronic packers & their auxillaries 2. SIEMENS S5/S7 PLC 3. An orientation to cement manufacturing process
13.2 PERSONALITY DEVELOPMENT PROGRAME 1. Orientation programme for engineers 2. Socialisation in process industries
13.3 OTHERS 1. 2.
Seminar given by Siemens on various Drives, Relays, Transmitters etc. Failure analysis of rotary equipments (Mechanical Bearings).
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CHAPTER 14 CEMENT MANUFACTURING PROCESS There are four main process routes in the manufacturing of cement – the dry, semi-dry, semi-wet and wet process. Common to all these processes are the following sub-processes _ Quarrying. _ Raw materials preparation. _ Fuels preparation. _ Clinker burning. _ Mineral additions preparation. _ Cement grinding. _ Cement dispatch
14.1 QUARRYING Natural (“primary”) raw materials such as limestone/chalk, marl, and clay/shale are extracted from quarries which, in most cases, are located close to the cement plant. After extraction, these raw materials are crushed at the quarry site and transported to the cement plant for intermediate storage, homogenization and further preparation. “Corrective” materials such as bauxite, iron ore or sand may be required to adapt the chemical composition of the raw mix to the requirements of the process and product specifications. The quantities of these corrective materials are usually low compared to the huge mass flow of the main raw materials. To a limited extent, “secondary” (or “alternative”) raw materials originating from Industrial sources are used to substitute for natural raw materials and correctives. In the same way as traditional raw materials, they may be fed to the quarry crusher or – more commonly – directly to the cement plant’s raw material preparation system.
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Today, modern computerised methods are available to evaluate the raw material deposits and to optimise the long-term and short-term production schedule.
14.2 RAW MATERIALS PREPARATION After intermediate storage and pre-homogenisation, the raw materials are dried and ground together in defined and well-controlled proportions in a raw mill to produce a raw meal for the dry (and semi-dry) process. In the wet (and semi-wet) process, the raw materials are slurried and ground with addition of sufficient water to produce a raw slurry. Depending on the technological process applied, additional steps may be required such as preparing raw meal “pellets” from dry meal (semi-dry process) or “filter cake” by dewatering of the slurry in filter presses (semi-wet process). The resulting intermediate product – i.e. raw meal or raw slurry (or their derivatives) – is stored and further homogenised in raw meal silos, storage bins or slurry basins to achieve and maintain the required uniform chemical composition before entering the kiln system. As a rule of thumb, approximately 1.5 – 1.6 tons of (dry) raw materials are required to produce one ton of the burnt product clinker. More detailed figures on raw
14.3 FUELS PREPARATION Conventional (fossil) fuels used in the cement industry are mainly coal (lignitie and hard coal), petcoke (a product from crude oil refining), and heavy oil (“bunker C”). Natural gas is rarely used due to its higher cost. “Alternative” fuels – i.e. non-fossil fuels derived from industrial (“waste”) sources . Fuels preparation – i.e. crushing, drying, grinding, and homogenising – usually
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takes place on site. Specific installations are required such as coal mills, silos and storage halls for solid fuels, tanks for liquid fuels, and the corresponding transportand feeding systems to the kilns. The thermal fuel consumption is largely dependent on the basic process design applied in the burning of clinker.
14.4 CLINKER BURNING The prepared raw material (“kiln feed”) is fed to the kiln system where it is subjected to a thermal treatment process consisting of the consecutive steps of drying/preheating, calcination (e.g. release of CO2 from limestone), and sintering (or “clinkerisation”, e.g. formation of clinker minerals at temperatures up to 1450° C). The burnt product “clinker” is cooled down with air to 100-200° C and is transported to intermediate storage. The kiln systems commonly applied are rotary kilns with or without so-called “suspension preheaters” (and, in more advanced systems, “precalciners”) depending on the main process design selected. The rotary kiln itself is an inclined steel tube with a length to diameter ratio between 10 and 40. The slight inclination (2.5 to 4.5%) together with the slow rotation (0.5 – 4.5 revolutions per minute) allow for a material transport sufficiently long to achieve the thermal conversion processes required. Exhaust heat from the kiln system is utilised to dry raw materials, solid fuels or mineral additions in the mills. Exhaust gases are dedusted using either electrostatic precipitators or bag filter systems before being released to the atmosphere.
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14.5 CEMENT GRINDING
Portland cement is produced by intergrinding cement clinker with a few percent of natural or industrial gypsum (or anhydrite) in a cement mill. Blended cements (or “composite” cements) contain other constituents in addition such as granulated blast-furnace slag, natural or industrial pozzolana (for example, volcanic tuffs or fly ash from thermal power plants), or inert fillers such as limestone. Mineral additions in blended cements may either be interground with clinker or ground separately and mixed with Portland cement. Grinding plants may be located remotely from the clinker production facility. The different cement types have to be stored separately in cement silos prior to bagging and dispatch.
14.6 MINERALS ADDITION PREPARATION Mineral additions from natural or industrial sources intended to be used in blended cements may need to be dried, crushed or ground in separate installations on site. Separate “grinding plants” where mineral additions and blended cements only are produced may also be located remote from the clinker production facility.
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FIG. 14.1
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14.7 CEMENT DISPATCH Cement may be shipped as bulk cement or – usually to a lesser extent – packed into bags and palletised for dispatch. Transport methods used (i.e. road, railway, waterways) depend on local conditions and requirements.
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