Shree Cement Beawar Report

A SEMINAR REPORT On SUMMER TRAINING Undergone

“SHREE CEMENT LIMITED” Submitted BY “NARENDRA SINGH” Department of Electronic Instrumentation & Control Engineering

GLOBAL TECHNICAL CAMPUS GLOBAL INSTITUTE OF TECHNOLOGY ITS-1,IT PARK, EPIP SITAPURA JAIPUR

Year 2012-13 1

DEPARTMENT OF ELECTRONIC INSTRUMENTATION AND CONTROL ENGINEERING

CERTIFICATE This is to certify that a seminar report on summer training undergone at “SHREE CEMENT PVT. LTD.” is submitted by NARENDRA SINGH, student of B.tech IV year (VII semester) of Electronic Instrumentation and Control Engineering from Rajasthan Technical University, Kota during the academic year 2012-2013. The report has been found satisfactory and is approved for submission.

Mr. Sujeet Gupta

Mr. Mayank Vyas

Head Of Department

Seminar Coordinator

Deptt. Of EI&C

(AssistantProfessor) Deptt. Of EI&C

2

ACKNOWLEDGEMENT We the student of B.Tech considers the training to be challenging job. We feel that excellence in any field cannot be achieved without the help of our learned instructors. At the completion of our training in SHREE CEMENT LTD. We will prefer to make some acknowledgements, which is indeed a difficult task. First of all I would like to pay my sincere regards to Mr. GOPAL TRIPATHI sir for being so kind, co-perative and helping during the entire training period. I also express my thanks and sincere regards to my Head of Department Mr. ANIL SHARMA for his immense support and help for this report and other faculty members for their valuable support.

( NARENDRA SINGH)

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PAGE INDEX Topic

Page No.

1. INTRODUCTION

9

1.1 LOCATION OF PLANTS

11

1.2 COMPANY POLICY

12

1.3 CEMENT&TYPES

13

1.4 OVER ALL CEMENT PROCESS

14

2. MINES AND CRUSHING SECTION:

15

2.1 MINES

15

2.2 CRUSHING

16

3. HANDLING AND MAINTAINING:

17

3.1 STACKER

17

3.2 RECLAIMER

18

4. RAW MILL:

19

4.1 VERTICAL ROLLER MILL

20

4.2 C.F.SILO

21

5. CYCLONE PRE-HEATER:

22

5.1 4 STAGE CYCLONE PREHEATER

22

6. CEMENT KILNS

24

7. COOLERS

26

8. CEMENT MILL

27

9. FINAL PRODUCT AND PACKING

29

4

10. INSTRUMENTS USED:

31

10.1 TEMPERATURE MEASUREMENT

31

10.2 PRESSURE MEASUREMENT

34

10.3 LEVEL MEASUREMENT

36

10.4 INSTRUMENT USED IN PACKING PLANT

37

10.5 SAFETY INSTRUMENTS

38

10.6 WEIGH FEEDER

42

10.6 METAL DETECTOR

43

10.7MAGNETIC SEPERATOR

44

10.8FILTERS

45

11. BIBLIOGRAPHY

47

5

TABLE INDEX Table

Page No.

1.1 PLANTS LOCATION

11

6

FIGURE INDEX Figure

Page No.

1.1 CEMENT PROCESS

14

2.1 MINES SITE

15

2.2 ROTARY BREAKER

16

3.1 STACKER MACHINE

17

3.2 RECLAIMER MACHINE

18

4.1 VERTICAL RAW MILL

19

4.2 RAW MILL

21

4.3 C.F. SILO

22

5.1 FOUR STAGE CYCLONE PREHEATER

23

6.1 CEMENT KILL

24

6.2 ROTARY KILN TUBE

25

7.1 COOLERS

26

8.1 CEMENT MILL

27

9.1PACKING MACHINE

30

10.1 RTD

32

10.2 THERMOCOUPLE

33

10.3 RADIATION PYROMETER

34

10.4 BOLLEN TUBES

35

10.5 BALL FLOAT METHOD

35

10.6 COUNTERS USED IN PACKING PLANT

36

10.7 LOAD CELL

37 7

10.8 PULL CHORD SWITCH

38

10.9 BELT SWAY SWITCH

39

10.10 ZERO SPEED SWITCH

40

10.11 PROXIMITY SWITCH

41

10.12 WEIGH FEEDER

42

10.13 METAL DETECTOR

44

10.14 MAGNETIC SEPERATOR

45

10.15 ESP

46

8

ABSTRACT This report is intended to give necessary background to understand the process by which cement is manufactured at SHREE CEMENT LTD . It focuses on the role of instrumentation in the cement industry and the operation of an instrumentation system. Although this report only identifies the main components and techniques of a typical instrumentation system, it is not intended to give an all-inclusive operations of every possible instrumentation system present in the cement plant. Subsystems and topics include mines, raw mill, kiln, Preheater, cooler, cement mill, packing plant and the various instruments being used and also PLC. All the devices whether mechanical, electrical or instrument all are connected and controlled by the programmable logic controllers (PLC) and for the visual experience of this SCADA (supervisory control and data acquisition system) is used. SCADA is used to show the current condition of the process and also to keep the record of all the past data. Each of the above subsystems is explained in detail as to its function and utility. The report also includes information on temperature, pressure, flow, and level detection systems which are used in the cement plant. This information will provide personnel with an understanding of the basic operation of various sections of the cement plant, the role of instrumentation and control systems.

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CHAPTER -1 INTRODUCTION & COMPANY POLICY SHREE CEMENT LIMITED is an energy conscious & environment friendly business organization. Having ten Directors on its board under the chairmanship of Shri B.G. Bangur, the policy decisions are taken under the guidance of Shri H.M. Bangur, Managing Director. Shri M.K. Singhi, Executive Director of the company, is looking after all day to day affairs. The company is managed by qualified professionals with broad vision who are committed to maintain high standards of quality & leadership to serve the customers to their fullest satisfaction. The largest cement manufacturing plant at a single location in Northern India, under the flagship of Executive Chairman Shri B.G. Bangur& Managing Director Shri H.M. Bangur. The Company is aiming for 20 Million Ton Annual production by the year 2015

1.1 PLANT LOCATION: The plant is located near the city of Beawar, Dist. Ajmer inCentral Rajasthan, sate ling the Beawar city at radius of 10 Kms. However the Beawar subdivision is will connected through Rail and Road both, situated on National Highway No. 8. Some of another plant located in RAS. The RAS plants are far from Beawar at least 35 k.m. All the same activities are doing in this plant & this plant is used High grade material our compression in BEAWAR plant and this

10

material send in BEAWAR plant & mix both the Material & get the superior quality product. UNIT -1 at Beawar Distt: Ajmer

UNIT -2 at Beawar Distt: Ajmer

Incorporated in 1979, Established in 1985 Cement

Put up in 1997

Production (Expected)-1.20 million

Cement Production -2.10 million

tones

tones

UNIT -3 at Ras Distt: Pali

UNIT -4 at Ras Distt: Pali

Incorporated in 2005

Cement Production - 1.0 million

Cement Production - 1.0 million

tones

tones UNIT -5,6 &7 at Ras Distt: Pali

Khuskheda Grinding unit (Distt.

Production – 1.00 million tones each

Alwar)

(also having a world record of 367

Suratgarh & Roorkee Grinding unit

days)

of 1.5 & 1.0 MTPA under commissioning TAB.1 PLANTS LOCATION

One of newly grinding unit started in KHUSHKHERA–Distt-Bhiwadi, the plant is far from the BEAWAR plant almost 500 KM.

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1.2 COMPANY POLICY: QUALITY POLICY To provide products conforming to National standards and meeting customers requirements to their total satisfaction. To continually improve performance and effectiveness of quality management system by setting and reviewing quality objectives for:  Customer satisfaction  Cost effectiveness

“JO SOCHE, WOH PAAVE” ENVIRONMENT POLICY To ensure: 

Clean, green and healthy environment



Efficient use of natural resources, energy, plant and equipment



Reduction in emissions, noise, waste and green house gases



Continual improvement in environment management

HEALTH & SAFETY POLICY To ensure Good Health and Safe Environment for all concerned by: 

Promoting awareness on sound health and safe working practices



Identifying and minimising injury and health hazards by effective risk control measures



Complying with all applicable legislations and regulations

“PROSPERITY THROUGH HEALTH & SAFETY” 1.3 CEMENT& TYPES: 12

In the most general sense of the word, cement is a binder, a substance that sits and hardens independently, and can bind other material together. Cement is a fine,soft,powdery type substance. It is made from a mixture of elements that are found in natural materials such as limestone,clay,sand and slash or shale.when cement is mixed with water it can bind sand and gravel into a hard,solid mass called concrete.cement is usually gray.white cement can also be found but is usually more expensive than gray cement.  Cement mixed with water,sand and gravel forms concrete.  Cement mixed with water and sand forms cement plaster.  Cement mixed with water,lime and sand forms mortar.

TYPES 1.3.1. Ordinary Portland cement 1.3.2 Portland pozzolana cement

1.3.1. Ordinary Portland cement: Cement is made by heating limestone (calcium carbonate) with small quantities of other materials (such as clay) to 1450 °C in a kiln, in a process known as calcination, whereby a molecule of carbon dioxide is liberated from the calcium carbonate to form calcium oxide, or quicklime, which is then blended with the other materials that have been included in the mix. The resulting hard substance, called 'clinker', is then ground with a small amount of gypsum into a powder to make 'Ordinary Portland Cement', the most commonly used type of cement (often referred to as OPC.

1.3.2 Portland pozzolana cement : It includes fly ash cement, since fly ash is a pozzolan, but also includes cements madefrom other natural or artificial pozzolans. In countries where 13

volcanic ashes are available, these cements are often the most common form in use.

1.4Overall Process of Cement Manufacture:

MINES

CRUSHER

CONVEYING SYS.

STACKER

RECLAIMER

HOPPERS

VRM (350TPH)

C. F. SILO

HI GRADE AVERAGE GRADE LATRITE (IRON)

PRE-BIN

CYCLONE:

KILN

BURNER

(6 STAGES) heat transfer Weighment

COOLER

with air

(11 Fans)

Solid flow meter

BALL MILL

CEMENT SILOS (5nos.)

(Add Gypsum) FIG. 1.1 OVERALL PROCESS

14

PACKING

CHAPTER-2 MINES& CRUSHING 2.1 MINES: Limestone is the main raw material of cement. Shree cement has two mines first at Shree & another at RAS. Which is almost 35 KM far from Beawar. There are two plants having production capacity of almost 8000 M.T. of Clinker. For making 1 M.T. of clinker almost 1.5 MT lime stone is required and lime stone is sent by conveyer belt mines to plant.

FIG 2.1 MINES SITE

They have sufficient dumpers, cranes, excavator machines that are carrying the work smoothly and at high pace. In the mean time i.e. duration of two shifts blasting is done. Before blasting alarming by sound through specific equipment so that avoid the misshapen. In this way they may not face problem of shortfall of material during production schedule. We are also researching a lot in mines where to extract material and how much. 15

2.2 CRUSHING: At site itself I got acquainted that crushing is done by Impact crusher. The following activity is watched by me:  Approximately 100-150 cm rock is fed to hopper of crusher by dumper. If any rock is left outside the hopper then it is fed by dozer.  It goes slowly to the hopper of crusher by Apron feeder. I had seen that very small rock is dropped from Apron to the chute & directly goes to the belt with crushing product.  Water spraying is also done in the hopper of crusher.  This crushed product is directly come from mines to raw mill  Hopper through belt conveyor. For any cement plant essential thing is the availability of Limestone. It is the most important ingredient. For production of Cement 75% calcium carbonate (limestone) is required. Limestone is taken by open cast Mines.

FIG. 2.2 ROTARY BREAKER.

16

CHAPTER-3 HANDLING & MAINTAINING 3.1 STACKER: A stacker is the large machine which is used in bulk material handling applications.It is mainly used to arrange the incoming feed in piles. It is important to maintain the homogenous and uniformity before discharging to further process A stacker usually operates on a rail-like structure with movable wheels, but the main operation is performed on a fixed place.

FIG. 3.1 STACKER MACHINE.

17

3.2RECLAIMER: Its main function is to recover the material and at the same time maintaining uniformity. At this stage the material is collected in hoppers via conveyer belts.Reclaimers are volumetric machines and are rated in m3/h (cubic meters per hour) for capacity, which is often converted to t/h (tones per hour) based on the average bulk density of the material being reclaimed. Reclaimers normally travel on a rail between stockpiles in the stockyard. A bucket wheel reclaimer can typically move in three directions: horizontally along the rail; vertically by "luffing" its boom and rotationally by slewing its boom. Reclaimers are generally electrically powered by means of a trailing cable.

FIG. 3.2 RECLAIMER MACHINE.

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CHAPTER-4 VERTICAL ROLLER MILL (RAW MILL)

FIG. 4.1 VERTICAL RAW MILL.

Raw mill is grinding equipment which is used to grind the incoming feed fed through hoppers. There are three hoppers in each unit. The first one carrying high grade calcite from RAS mines. The second one contains the average grade limestone from Shree mines nearby and lastly the hopper containing Laterite(zinc slag i.e. molten residue at the bottom of zinc smelter). Laterite has a high percentage of iron.

19

FIG. 4.2 RAW MILL.

According to desired quality of cement, raw material (either of high grade, low grade) is taken with the help of apron feeder, weigh feeder, and belt conveyors taken to vertical raw mill... Vertical Raw Mill has got four hydraulic rollers and one horizontal circular disc. The material coming from hopper building is grind between horizontal circular disc & hydraulic rollers. The grinded material is sucked from top by raw mill fan and coarse material is recycled back to main feed to VRM. Fine material as sucked by raw mill fan goes to cyclones where the material is separated from air through these four cyclones and one bag house. The material is accumulated and with the help of screw conveyors feed back to CF silo. The material is blended with the help of compressed air and the material is discharged to kiln feed bin for onward transportation to Kiln for clinker production with the help of bucket elevator. There are two methods through which the material is lifted to pre heater either with the help of bucket elevator or through airlift. In case if bucket elevator fails because of any reason the material is lifted through airlift.

20

4.2 C.F.SILO

FIG. 4.3 C.F. SILO.

Are basically storage units the advantage of using them is that they not let the material stick together. That is why they are called CFS or Continuous Flow Silos. The CF (Controlled Flow) silo is a continuously operating system for homogenizationand storage of cement raw meal,where the material is extracted simultaneouslyat different flow rates froma number of outlets in the silo bottom.The CF system, including suitable kilnfeed equipment, ensures stable kilnfeed composition at minimum powerconsumption and investment cost.The efficient performance of the CFhomogenizing silo results in stable kilnoperation so that changes in kiln speedor firing rate are rarely needed andstable coating in the kiln is maintained.

21

CHAPTER-5 CYCLONE PRE-HEATERS 4 stage Cyclone PreHeater: The key component of the gas-suspension preheater is the cyclone. A cyclone is a conical vessel into which a dust-bearing gas-stream is passed tangentially. This produces a vortex within the vessel. The gas leaves the vessel through a co-axial "vortex-finder". The solids are thrown to the outside edge of the vessel by centrifugal action, and leave through a valve in the vertex of the cone. Cyclones were originally used to clean up the dust-laden gases leaving simple dry process kilns. If, instead, the entire feed of rawmix is encouraged to pass through the cyclone, it is found that a very efficient heat exchange takes place: the gas is efficiently cooled, hence producing less waste of heat to the atmosphere, and the rawmix is efficiently heated. This efficiency is further increased if a number of cyclones are connected in series.

FIG. 5.1 FOUR STAGE CYCLONE PREHEATER.

22

The number of cyclones stages used in practice varies from 1 to 6. Energy, in the form of fan-power, is required to draw the gases through the string of cyclones, and at a string of 6 cyclones, the cost of the added fan-power needed for an extra cyclone exceeds the efficiency advantage gained. It is normal to use the warm exhaust gas to dry the raw materials in the raw mill, and if the raw materials are wet, hot gas from a less efficient preheater is desirable. For this reason, the most commonly encountered suspension preheaters have 4 cyclones. The hot feed that leaves the base of the preheater string is typically 20% calcined, so the kiln has less subsequent processing to do, and can therefore achieve a higher specific output. Typical large systems installed in the early 1970s had cyclones 6 m in diameter, a rotary kiln of 5 x 75 m, making 2500 tonnes per day, using about 0.11-0.12 tonnes of coal fuel for every tonne of clinker produced. A penalty paid for the efficiency of suspension preheaters is their tendency to block up. Salts, such as the sulfate and chloride of sodium and potassium, tend to evaporate in the burning zone of the kiln. They are carried back in vapor form, and re-condense when a sufficiently low temperature is encountered. Because these salts re-circulate back into the rawmix and re-enter the burning zone, a recirculation cycle establishes itself. A kiln with 0.1% chloride in the rawmix and clinker may have 5% chloride in the mid-kiln material. Condensation usually occurs in the preheater, and a sticky deposit of liquid salts glues dusty rawmix into a hard deposit, typically on surfaces against which the gas-flow is impacting. This can choke the preheater to the point that air-flow can no longer be maintained in the kiln. It then becomes necessary to manually break the build-up away. Modern installations often have automatic devices installed at vulnerable points to knock out build-up regularly. An alternative approach is to "bleed off" some of the kiln exhaust at the kiln inlet where the salts are still in the vapor phase and discard the solids. 23

CHAPTER-6 CEMENT KILN

FIG. 6.1 CEMENT KILL.

Cement kilns are used for the pyroprocessing stage of manufacture of Portland and other types of hydraulic cement, in which calcium carbonate reacts with silica-bearing minerals to form a mixture of calcium silicates.In the second stage, the rawmix is fed into the kiln and gradually heated by contact with the hot gases from combustion of the kiln fuel. Successive chemical reactions take place as the temperature of the rawmix rises: 

70 to 110 °C - Free water is evaporated.



400 to 600 °C - clay-like minerals are decomposed into their constituent oxides; principally SiO2 and Al2O3. Dolomite (CaMg(CO3)2) decomposes to calcium carbonate, MgO and CO2.

24



650 to 900 °C - calcium carbonate reacts with SiO2 to form belite(Ca2SiO4).



900 to 1050 °C - the remaining calcium carbonate decomposes to calcium oxide and CO2.



1300 to 1450 °C - partial (20–30%) melting takes place, and belite reacts with calcium oxide to form alite (Ca3O·SiO4).

FIG. 6.2 ROTARY KILN TUBE.

The rotary kiln consists of a tube made from steel plate, and lined with firebrick. The tube slopes slightly (1–4°) and slowly rotates on its axis at between 30 and 250 revolutions per hour. Rawmix is fed in at the upper end, and the rotation of the kiln causes it gradually to move downhill to the other end of the kiln. At the other end fuel, in the form of gas, oil, or pulverized solid fuel, is blown in through the "burner pipe", producing a large concentric flame in the lower part of the kiln tube. As material moves under the flame, it reaches its peak temperature, before dropping out of the kiln tube into the cooler. Air is drawn first through the cooler and then through the kiln for combustion of the fuel. In the cooler the air is heated by the cooling clinker, so that it may be 400 to 800 °C before it enters the kiln, thus causing intense and rapid combustion of the fuel. 25

CHAPTER-7 COOLERS Coolers are used to cool the recently obtained clinkers from the kiln.

FIG. 7.1 COOLERS.

The energy obtained from the clinkers through heat transfer is recirculated in the kiln. Coolers in power plantused water as coolant. The second function for water in such a power plant is to cool the system so as to condense the lowpressure steam and recycle it. As the steam in the internal circuit condenses back to water, the surplus (waste) heat which is removed from it needs to be discharged by transfer to the air or to a body of water. This is a major consideration in sitting power plants.

26

CHAPTER-8 CEMENT MILL

FIG. 8.1 CEMENT MILL It is the heart of whole plant. Its main function is to convert CLINKER into finished product say to cement. Main Raw materials of CEMENT MILL are: 1-CLINKER 2-POZZOLONA 3-GYPSUM 4-FLY ASH For making the cement in this mill Gypsum & the pozzolona mixed with CLINKER in fixed ratio. Weight feeders are run with D.C. Motor. Speed of motor is controlled by thyristor. Grinding media is different compartment & these grinding media are helped in ground to the feed material. 27

Now in the CEMENT MILL the O/P is in the form of cement. The cement is transferred by the help of a BUCKET ELEVATOR. There are two BUCKET ELEVATORS. Capacity of each Elevator is 100 tonnes from the BUCKET ELEVATOR; cement is transferred by the air slide & pipes by the help of pump to the cement Silo for storage & packing purpose. A ball mill is a horizontal cylinder partly filled with steel balls (or occasionally other shapes) that rotates on its axis, imparting a tumbling and cascading action to the balls. Material fed through the mill is crushed by impact and ground by attrition between the balls. The grinding media are usually made of high-chromium steel. The smaller grades are occasionally cylindrical ("pebs") rather than spherical. There exists a speed of rotation (the "critical speed") at which the contents of the mill would simply ride over the roof of the mill due to centrifugal action. The critical speed (rpm) is given by: nC = 42.29/√d, where d is the internal diameter in metres. Ball mills are normally operated at around 75% of critical speed, so a mill with diameter 5 metres will turn at around 14 rpm.

28

CHAPTER -9

FINAL PRODUCT & PACKING UNIT 9.1 FINAL PRODUCT: These are the various products manufactured by the plant.  O.P.C. (Ordinary Portland Cement): no constituent other than clinkers and gypsum is introduced in the manufacture process, it is available in 43 grade and 53 grade in accordance with respective compressive strength.  P.P.C. (Portland Pozzolana Cement): this product contains a certain quantity of flyash as an additive along with gypsum. 9.2 PACKING UNIT: Being final product, the cement is stored in cement silos. There are five silos in our company, three for Unit-I and two for Unit-II. Cement is carried forward to an elevator and is collected in cement bin .Bin is connected to vibrating screen through which cement is passed down to cement tank. There is a valve attached between vibrating screen and cement tank which regulates the flow of cement, level sensor senses the level of hopper attached to cement tank. The gate valve is connected tosolenoid valve. The capacity of tank is 45 tons. To measure the temperature of cement, aRTD is connected to cement tank. There is also a direct pathway (optional) from vibrating screen bin to loader if there is no requirement for packing the cement.

29

FIG. 9.3PACKING MACHINE

30

CHAPTER- 10 INSTRUMENTS USED 10.1 FOR TEMPERATURE: 10.1.1 Resistance Temperature Detector: RTD, basically works on the principle, that the value of resistance changes with the change in temperature. It is a three terminal device. Two of its terminals are connected to the two ends of the platinum bulb, & the third terminal to one of its endof the bulb to nullify the effects due to the resistance of the transmission wires. The temperature dependency of the resister can be shown as, resistance temperature detector Rt= R0 (1+ αT) for positive temperature coefficient of platinum. The resistance thermometers can be made up of mainly three materials namely, platinum, nickel, copper, where each one is used according to its application.

31

FIG.10.1 RTD

10.1.2 THERMOCOUPLES: Thermocouples will cause an electric current to flow in the attached circuit when subjected to changes in temperature.The amount of current that will be produced is dependent on the temperature difference between the measurement and reference junction; the characteristics of the two metals used; and the characteristics of the attached circuit. Heating the measuring junction of the thermocouple produces a voltage which is greater than the voltage across the reference junction. The difference between the two voltages is proportional to the difference in temperature and can be measured on the voltmeter (in mill volts). For ease of operator use, some voltmeters are set up to read out directly in temperature through use of electronic circuitry.

32

FIG. 10.2THERMOCOUPLE

10.1.3 PYROMETERS: PYROMETERS are used where hot bodies are moving, where thermometers are cannot brought in contact. Measurements is done by measuring energy radiated by a hot body. It is used for the measurement of high temperature range which is about 600-3000`C.The intense heat needed to convert the raw meal into clinker in the preheater and kiln must be carefully controlled. PYROMETERS which is used in plants is basically of two types: i.

optical pyrometers

ii.

radiation pyrometers

33

FIG. 10.3 RADIATION PYROMETER

10.2 FOR PRESSURE: 10.2.1 PRESSURE TRANSDUCER: Bellows-Type Detectors The need for a pressure sensing element that was extremely sensitive to low pressures and provided power for activating recording and indicating mechanisms resulted in the development of the metallic bellows pressure sensing element. The metallic bellows is most accurate when measuring pressures from 0.5 to 75 psig. However, when used in conjunction with a 34

heavy range spring, some bellows can be used to measure pressures of over 1000 psig.

FIG. 10.4 BOLLEN TUBES

10.3 FOR LEVEL MEASUREMENT: BALL FLOAT: The operation of the ball float is simple. The ball floats on top of the liquid in the tank. If the liquid level changes, the float will follow and change the position of the pointer attached to the rotating shaft.

35

FIG. 10.5 BALL FLOAT METHOD

10.4 INSTRUMENT USED IN PACKING UNIT: 10.4.1 COUNTERS:

FIG. 10.6 COUNTERS USED IN PACKING PLANT COUNTER is a device which stores (and sometimes displays) the number of times a particular event or process has occurred. We offer a wide range cement bag counter which are specially developed for Indian bags and packing systems. These are accurate and take care of all 36

nuisance factors. Further these are available from 1 inch to 8 inches display size. Cement Bag counter for Truck Loader & Cement bag counter for wagon loader is most popular requirement now-a-days. These are having option of interfacing with all required devices & dispatch monitoring system.

10.4.2 LOAD CELL:

FIG. 10.7 LOAD CELL

LOAD CELL is the second most important device which is used in the packing unit as well as in weight-belt feeders. It is a transducer that is used to convert a force into electrical signal. This conversion is indirect. Accurate high capacity load cells are needed for press tonnage monitor calibration. They are also useful for some types of press testing. Calibration load cells have a metal structure to which strain sensors or strain gages are attached. The metal structure is compressed when subjected to load. The attached gages provide an electrical output that is a linear function of applied load if the proportional limit of the metal structure is not exceeded. Strain gage based load cells are available in capacities ranging from a few grams through 1,500 tons or more.

37

Weigh-belt feeders are key components in the production of portland cement as they are relied on to accurately proportion materials for both kiln feed preparation and finishing operations. Cement production weigh feeders are expected to perform very accurately and repeatably, while constantly enduring the harsh plant environment.

10.5 FOR SAFETY PURPOSE: 10.5.1 PULLCHORD SWITCH: Pull cord switch also known as Rope Operated Emergency switch is used as a safety switch to stop the conveyor belt in case of an emergency.It is also known as pull switch cord.

FIG. 10.8 PULLCHORD SWITCH OPERARTION: Pull cord switch is mounted on the walkway side of the conveyor belt, preferably at about every 20-25 meters. When the rope is pulled from any side. The switch get operated . Unless and until the handle is reset to normal position manually, the switch remains in operated condition.Pull Rope switch All the Pull Cord Switches installed along an individual belt are electrically wired in series and connected to the control station by a two core cable.

38

Therefore actuation of any one of these Pull Cord Switches will stop the concerned conveyor until the particular switch is manually reset.

10.5.2 BELT SWAY SWITCH: The switch allows smooth running of the conveyor and protects it from damages by over swaying which can occur due to uneven loading of material, worn out idler roller bearings etc. Belt sway switch is also known as Run Off Switch.

FIG.10.9 BELT SWAY SWITCH

OPERATION: For normal running of the belt with acceptable swaying, the belt-sway switch is generally mounted on both sides and near the edge of the conveyor belt. A is generally mounted on the both sides and near the edge of the conveyor belt. A small clearance is allowed between contact roller and the belt edge to allow the normal running of the belt with acceptable swaying. When swaying exceeds normal limit, the belt edge pushes the contact roller, which drives the switch and operates the contacts. The switch reset automatically when the belt resumes normal running. 39

10.5.3 ZERO SPEED SWITCH: Electronic Speed Monitor is used to monitor speed of conveyors, crushers, rolling mills, agitators, mixers, stirrers, screw conveyors, and other industrial machinery. This device actuates relay contacts at preset speed. Using these contacts desired control action such as zero speed protection/ under speed protection/ over speed protection can be achieved.

FIG.10.10 ZSS

Operation: The basic principle of speed monitor is comparison of pulses received from sensor with standard pulses. The unit consists of two parts: CONTROL UNIT and “SENSOR PROBE”. The sensor is to be installed with its sensing face in close proximity of rotating object. On this object, flags are to be fixed. The sensor products strong electromagnetic waves, which get disturbed by the flags, giving rise to corresponding pulses. These pulses are fed to the control unit where they are compared with standard pulses to sense the speed.

10.5.4 PROXIMITY SWITCH: When the object enters in the sensing zone of the switch, capacitance between two plates of capacitor (one plate is represented by electrode at sensing face of the switch and another by all surrounding material which is connected to the 40

earth) changes. As soon as capacitance value crosses preset level, oscillator starts. This change is detected and resulted in an output signal.

FIG.10.11 CAPACITIVE PROXIMITY SWITCH OPERATION: It has 3 cables which is apply to the contractors .It is generally NC(normally closed).When metal is placed in front of it then it is NO(normally open) .

10.6 OTHER INSTRUMENTS: 10.6.1 WEIGH FEEDER: It is used to measure & control conveying material’s quantity. The purpose of the system is to produce a flow of respective material, proportional to a demand flow rate signal over a wide range. Each weigh feeder is mounted at the bottom of a bin & the material is extracted out of the bin of the weigh feeder. The flowcontrolled by varying the speed of the weigh feeder. The weigh feeder works only in conjunction with the respective group control

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electronics. Weigh feeder maintain the output per time or the feed rate, weigh feeder employ a Closed loop feedback control system.

FIG.10.12 WEIGH FEEDER

OPERATION: Weigh feeder is machine through which, flow rate (TPH) of material is measured. The material passing over a belt conveyor exerts a down wards force proportional to its weight. The product of this force and the speed of the belt gives the rate of flow, the unit being Kg/min. or ton/hour. it consists of load cells for weight measurement and tacho for belt speed. Measuring Unit : TPH (TON PER HOUR) TPH = BELT LOAD X BELT SPEED X 3.6 = KG / MTR X MTR/ SEC X 3.6 Belt Load is measured by the Load Cell & beltspeed is measured by Tacho. FLOW RATE= BELT LOAD  BELT SPEED 42

=KG/MT  MT/SEC. =KG/ SEC. OR TPH The load is measured by a strain gauge load cell which does not have practically any deflection, and speed of the belt is measured by a Tacho. The quantity viz. load & speed available as electrical signals are then multiplied to set the rate of flow of material. The rate of material flow integrated in the time gives the total quantity of the material passed over the conveyor belt. It is obvious that the rate can be kept constant at any desired value either by varying load or speed.

10.6.2. METAL DETECTOR: The METAL DETECTING DEVICES are designed to be used on conveyor systems as they are employed in various industries, wherever metal pieces in the conveyed material may damage sensitive machinery, metal detecting devices will prevent expensive repairs & production breakdowns. Metal Detectors are used to detect metal pieces in the material to prevent damage to the processing machineries like crushers, grinders,etc.It is made of search&receivercoil. A high frequency electromagnetic field is set up in the search coil.When any ferrous metal passes through this field it gets detected by the receiver coil.

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FIG.10.13 METAL DETECTOR OPERATION: A high frequency alternating voltage is fed from the amplifier to a coil in the probe. This generates an electromagnetic field. If a metal piece comes into this field, induction current will generated that will drain power from the oscillators. If depending on the selected sensitivity an unwanted metal piece in the conveyed material is identified by the electronics in the amplifier, the output relay will switch to its other state for about 0.5 seconds. The output relay has two potential free NC/NO contacts that are wired to the terminal strip. These contacts can be used to stop the conveyor belt.

10.6.3 MAGNETIC SEPRATOR: Magnetic separation is a process in which magnetically susceptible material is extracted from a mixture using a magnetic force. Magnetic seprator consist of an electromaget which pulls any magnetic material placed on the surface of the material being conveyed by the conveyor

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belt.The undesired material such as nuts,bolts, screw etc are then collected in a reject chute.

FIG.10.14 MAGNETIC SEPARATOR

10.6.4 FILTERS 10.6.4.1 Electrostatic precipitator 10.6.4.2 Bag filters 10.6.4.1. Electrostatic precipitator Electrostatic precipitator is an apparatus which cleans process gases by using electrical forces to remove solid particles carried in the gas stream. The dirty gases are passed through an intense electrical field set up between electrodes of opposite polarity. The discharge electrodes -so called because of the corona discharge which results from the application of high voltage-impart a negative charge to the particles. These particles are then attracted to the collector 45

electrodes which are positive with respect to the discharge electrodes and in practice are connected to ground through the structure or through ground cables

FIG. 10.15 ESP

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BIBLIOGRAPHY

[1] VEHICULAR INSTRUMENTATION/TRANSDUCER COMMITTEE TELEMETRY GROUP RANGE COMMANDERS COUNCl, “INSTRUMENTATION ENGINEERS HANDBOOK published in December 2005 [2] http://en.wikipedia.org/wiki/Cement_mill [3] Shree cement mannuals

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