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

DEPARTMENT

1

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)

PAGE INDEX

3

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

10. INSTRUMENTS USED: 31

4

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.

9

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

Incorporated in 1979,

Established in 1985 Cement

Production (Expected)-1.20 million

tones

UNIT -2 at Beawar Distt: Ajmer

Put up in 1997

Cement Production -2.10 million

tones

UNIT -3 at Ras Distt: Pali

Incorporated in 2005

Cement Production - 1.0 million

tones

UNIT -4 at Ras Distt: Pali

Cement Production - 1.0 million

tones

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

Production – 1.00 million tones each

(also having a world record of 367

days)

Khuskheda Grinding unit (Distt.

Alwar)

Suratgarh & Roorkee Grinding unit

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.

11

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 cement1.3.2 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 ce-ments madefrom other natural or artificial pozzolans. In countries where vol-

13

canic 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 COOLER

Weighment with air (11 Fans)

Solid flow meter

BALL MILL CEMENT SILOS (5nos.) PACKING

(Add Gypsum)

FIG. 1.1 OVERALL PROCESS

14

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.

18

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 homoge-

nizationand storage of cement raw meal,where the material is extracted simul-

taneouslyat 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) decom-

poses to calcium carbonate, MgO and CO2.

24

650 to 900 °C - calcium carbonate reacts with SiO2 to form belite(Ca2-

SiO4).

900 to 1050 °C - the remaining calcium carbonate decomposes to cal-

cium oxide and CO2.

1300 to 1450 °C - partial (20–30%) melting takes place, and belite re-

acts 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 low-

pressure 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.

CHAPTER -928

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 at-

tached to cement tank. The gate valve is connected tosolenoid valve. The ca-

pacity of tank is 45 tons. To measure the temperature of cement, aRTD is con-

nected 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

CHAPTER- 10

30

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.

FIG.10.1 RTD

10.1.2 THERMOCOUPLES:

31

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 char-

acteristics 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 be-

tween 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 elec-

tronic circuitry.

FIG. 10.2THERMOCOUPLE

10.1.3 PYROMETERS:

32

PYROMETERS are used where hot bodies are moving, where thermometers

are cannot brought in contact. Measurements is done by measuring energy ra-

diated 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

FIG. 10.3 RADIATION PYROMETER

10.2 FOR PRESSURE:33

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 mecha-

nisms resulted in the development of the metallic bellows pressure sensing ele-

ment. The metallic bellows is most accurate when measuring pressures from

0.5 to 75 psig. However, when used in conjunction with a 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:

34

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 posi-

tion of the pointer attached to the rotating shaft.

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

35

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 nui-

sance 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 in-

terfacing 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 calibra-

tion. 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 pro-

36

vide an electrical output that is a linear function of applied load if the propor-

tional 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.

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

37

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.

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 38

switch and operates the contacts. The switch reset automatically when the

belt resumes normal running.

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:

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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

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.

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The flowcontrolled by varying the speed of the weigh feeder. The

weigh feeder works only in conjunction with the respective group control

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

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Belt Load is measured by the Load Cell & beltspeed is measured by Tacho.FLOW RATE= BELT LOAD BELT SPEED=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 44

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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