Conveyor Belt A conveyor belt is the carrying medium of a belt conveyor system (often shortened to belt conveyor). A belt conveyor system is one of many types of conveyor systems. A belt conveyor system consists of two or more pulleys (sometimes referred to as drums), with an endless loop of carrying medium—the conveyor belt—that rotates about them. One or both of the pulleys are powered, moving the belt and the material on the belt forward. The powered pulley is called the drive pulley while the unpowered pulley is called the idler pulley. There are two main industrial classes of belt conveyors; Those in general material handling such as those moving boxes along inside a factory and bulk material handling such as those used to transport large volumes of resources and agricultural materials, such as grain, salt, coal, ore, sand, overburden and more. Today there are different types of conveyor belts that have been created for conveying different kinds of material available in PVC and rubber materials.
Transcript
Conveyor Belt A conveyor belt is the carrying medium of a belt conveyor system (often shortened to belt conveyor). A belt conveyor system is one of many types of conveyor systems. A belt conveyor system consists of two or more pulleys (sometimes referred to as drums), with an endless loop of carrying medium—the conveyor belt—that rotates about them. One or both of the pulleys are powered, moving the belt and the material on the belt forward. The powered pulley is called the drive pulley while the unpowered pulley is called the idler pulley. There are two main industrial classes of belt conveyors; Those in general material handling such as those moving boxes along inside a factory and bulk material handling such as those used to transport large volumes of resources and agricultural materials, such as grain, salt, coal, ore, sand, overburden and more.
Today there are different types of conveyor belts that have been created for conveying different kinds of material available in PVC and rubber materials.
The belt consists of one or more layers of material. Many belts in general material handling have two layers. An under layer of material to provide linear strength and shape called a carcass and an over layer called the cover. The carcass is often a woven fabric having a warp & weft. The most common carcass materials are polyester, nylon and cotton. The cover is often various rubber or plastic compounds specified by use of the belt. Covers can be made from more exotic materials for unusual applications such as silicone for heat or gum rubber when traction is essential.
A conveyer belt can be a slide and be controlled by the force of gravity.
Material flowing over the belt may be weighed in transit using a beltweigher. Belts with regularly spaced partitions, known as elevator belts, are used for transporting loose materials up steep inclines. Belt Conveyors are used in self-unloading bulk freighters and in live bottom trucks. Belt conveyor technology is also used in conveyor transport such as moving sidewalks or escalators, as well as on many manufacturing assembly lines. Stores often have conveyor belts at the check-out counter to move shopping items. Ski areas also use conveyor belts to transport skiers up the hill.
Belt conveyor systemsConveyors are durable and reliable components used in automated distribution and warehousing. In combination with
computer controlled pallet handling equipment this allows for more efficient retail, wholesale, and manufacturing distribution. It is
considered a labor saving system that allows large volumes to move rapidly through a process, allowing companies to ship or receive
higher volumes with smaller storage space and with less labor expense.
Rubber conveyor belts are commonly used to convey items with irregular bottom surfaces, small items that would fall in between rollers
(e.g. a sushi conveyor bar), or bags of product that would sag between rollers. Belt conveyors are generally fairly similar in
construction consisting of a metal frame with rollers at either end of a flat metal bed. The belt is looped around each of the rollers and when
one of the rollers is powered (by an electrical motor) the belting slides across the solid metal frame bed, moving the product. In heavy use
applications the beds which the belting is pulled over are replaced with rollers. The rollers allow weight to be conveyed as they reduce the
amount of friction generated from the heavier loading on the belting. Belt conveyors can now be manufactured with curved sections which
use tapered rollers and curved belting to convey products around a corner. These conveyor systems are commonly used in postal sorting
offices and airport baggage handling systems. A sandwich belt conveyor uses two conveyor belts, face-to-face, to firmly contain the
item being carried, making steep incline and even vertical-lift runs
achievable.
Belt conveyors are the most commonly used powered conveyors
because they are the most versatile and the least expensive. Product is conveyed directly on the belt so both regular and irregular shaped
objects, large or small, light and heavy, can be transported successfully. These conveyors should use only the highest quality
premium belting products, which reduces belt stretch and results in less maintenance for tension adjustments. Belt conveyors can be
used to transport product in a straight line or through changes in elevation or direction. In certain applications they can also be used for
static accumulation or cartons.
Cement Manufacturing process
1-Mining: The cement manufacturing process starts from the mining of limestone , which is the main raw material for making cement. Limestone is exacavatedfrom open cast mines afterdrilling and blasting and loaded on to the dumpers which transport the material and unloaded into the hoppers of limestone crusher.
2-Crushing Stacking & Reclaiming of Limestone: The l/s crusher crush theLimestone to minus 80mm size and discharge the material onto a belt conveyer which take it to the stacker via the bulk material analyser. The material is stacked in longitudinal stockpiles . Limestone is extract transversely from the stockpiles by the reclaimers and conveyed to the Raw Mill hoppers for grinding of raw meal.
3-Crushing Stacking& Reclaiming of coal: The process of making cement clinker requires heat . coal is used as the fuel for providing heat. Raw coal receive from the collieries is stored in a coal yard. Raw coal is dropon a belt conveyer from a hopper and is taken to and crushed in a crusher. Crushed coal discharge is stored in a longitudinal stockpiles from where it is reclaimed by a reclaimer and taken to the coal mill hopper grinding of fine coal.
4-Raw Meal Drying/Grinding &Homogenisation: Reclaimed l/s along with some laterite stored in their respective hoppers is fed to the Raw mill for fine grinding. The hot gasses coming from the clinkerisation
section are used in raw mill for drying and transport of the ground raw meal to the electrostatic precipitator /Bag house, where it is collected and then stored and homogenized in the concrete silo. Raw meal extracted from the silo(ne called kiln feed ) is feed to the top of the preheater for pyroprocessing.
5-Clinkerisation: Cement clinker is made by pyroprocessing of kiln feed in the preheater and the rotary kiln. Fine coal is fires as fuel to provided the necessary heat in the kiln and the precalciner located at the bottom of the 5/6 stage preheater. Hot clinker discharged from the kiln drops on the gate cooler and gets cooled. The cooler discharged the clinker onto the pan / bucket conveyer and it is transported to the clinker stockpiles/silp. The clinker is taken from the stockpiles/silo to the ball mill hoppers for cement grinding.
6-Cement Grinding & Storage: Clinker and Gypsum(for OPC) and also Pozzolana(for PPC) are extracted from their respected hoppers and feed to the cement mill. These ball mills ground the feed to a fine powder and the mill discharge is feed to an elevator, which takes the material to a separator, which separates fine product and the coarse the latter is sent to the mill inlet for regrinding and the fine product is stored in concrete silo.
7-Packing: Cement extracted from silos is conveyed to the automatic electronic packers where it is packed in 50 Kgs polythene bags and dispatched in trucks.
Mining
The major raw material for cement manufacturing is limestone. Limestone is excavated from open cast mines after drilling and blastin and loaded onto the dumper which is transported the material and unloaded into hopper of the limestone crusher.
Equipment Used in mining:
1. Compressor drilling machine.2. Shovels/Excavators-for lifting material onto dampers.3. Dumper- for carrying material.4. Buildozers.5. Payloaders.
Explosive:
1. Amonium nitrate(Fuel oil)2. Nitroglycerine.3. Amonium nitrate and slurry explosive.
Steps of Mining:
1. The first step of mining l/s the l/s has been located.2. Limestone mining is to remove the mines.3. The third step is to be taken as drilling.4. After drilling blasting is done.
Drilling and Blasting:
1. The large hole blasting method is not pre-dominated in quarrying in open pit.
2. The depth of the holes are more then 12m and 100-150mm dia.
Lime Stone CrusherLime stone crusher is the lead role playing equipment in this section. The raw lime stoe is carried out from the mines is introduced to the lime stone hopper through hole pack dumper of capacity 32 tons. The feed inside the impact crusher first enters to the crushing chamber with help of apron feed encounters. The impact bars mounted over the rotor &revolving with the circumfrencial velocity of 30-40 m/sec. Material are blown bars and stick on a impact arm. Here materials are initially install to hold these grinding bars. The squire impact arm is install just behind the impact path and having 12 liners. When the material get crushed enough for transportation towards stacker. A bag house is also installed to control the dust loss and pollution control.
Equipment Used in Crushing:
1. Crusher.2. Apron conveyer – for feeding l/s to crusher.3. Bag filter – for collecting dust.4. Belt conveyer- for transporting crushed material.
Make L&T L&TThis section is worked with Following equipment:
1. Impact crusher.2. Magnetic separator3. Limestone stacker&reclaimer4. Bag filtor5. Apron feeded6. Limestone hopper & laterite hopper
The important mode of transportation in this section is belt conveyer.
Main component of impact crusher:
Housing: housing of impact crusher is of studly steel fabricated and consist of three part.
Rotor: The rotor in the impact crusher is of s-type construction secured to the shaft by locking assembly. The blow bar are placed in to the rotor from the side and are secured against lateral moment by a suitable locking device at the extreme end. The rotor is dynamically arranged to avoide any undesireable stress on the bearing.
Blow bar: Blowbar is made from high quality alloyes steel. After the certain period in operation the blow bar can be taken out from the rotor and turned to other side or exchange.
Wear plates: housing is fitted with the resistance wear plates which are secured in position by special fastners which can be changed as and required.
Impact Arm: The impact crusher is fitted with the impact arm. The impact arms are each suspended in the housing parts by
means of knock out spindle and can be adjusted the desire gap setting from out side.
Hydraulic system: Impactors are depend on their size normally supplied with a hydraulic arrangement for setting of gap for grinding path lifting of the rear top housing.
Magnaetic Separator: A magenatic separator is installed just above belt conveyer between crusher and stacker. When the magenatic material are comes along with limestone ,they get seprated by magnetic separator. In the magnetic separator a permanent magnet and a continually moving belt beinfinuse.magnetic materials are attached by magnet due to cont. rotating of belt , material get seprated on removal of magnetic field.
Gamma Matrics: A gamma matric analyzer being used for analyze the chemical composition of lime stone. It also known as cross belt analyzer. In gamma metric analyzer we are using specily gamma rays, the gamma rays are fall on material and return back, according to absorption rays in to material we can determine the chemical composition of lime stone .
Stacking Of Lime stone:There are two main method being used for stacking of lime stone in cement industry. They are……..
1. Chevron Method2. Windrow Method
Technical Specification of Lime Stone Stacker:
Make =MANTAKRAF
Capacity=1400TPH
Reclaimer:
Reclaimer which is used in our industry is bridge type scrapping reclaimer. The bridge on which the racking down device is mounted accommodates a scraper chain conveyer whose blades shift the dis lodged material along to collacting belt conveyer that extent along one edge of stackpile. Reclaimer having harrow assembly.Reclaimer moves on a track for fast travel A.c. Motor being used and for slow traveling d.c.moter being used. Harrow are moves to and fro motion on an rack car which is driven by a motor. A limit sensor is installed for reverse and forword motion of harroe assembly. According to pile we can adjust the inclination of harrows. When harrows are moves they are scrap the material of each layer of stockpiles and material slides down due to gravity. A scraper chain take out the material and fed to belt conveyor material now get transported forwords limestone hoppers.
Technical Specification of Reclaimer:
Unit-1
Capacity =400TPH
Make =Bulkauwalf(India)
Unit-2
Capacity =550TPH
Make =Cimmco(India)
Raw mill:
This section is working with the fine grinding of raw material upto 90 microne for proper burning & proper calcinations of raw material. JaypeeRewa Plant have two raw mill. In Unit-1 krupppolusius mill has the capacity of 320TPH and unit-2 loesche mill has capacity of 440TPH installed for grinding of raw material. The mill are designed in a modular fashion and can be equipped as required with four rollers. Each roller together with rocker arm which is rigigly clamped the pedestal in whch the rocker arm is mounted and a hydro-pneumatic spring system represent a power unit.
Technical Specification of VRN unit-1:
Make Krupp polysius
Type LM K 54/27
Capacity 320 TPH
Classifire LNV
Gearbox RENK AG(2003)
Speed Ratio 990/23.53 RPM
Motor 3600KW(BHEL)
Feed Size 90mm+2%
Product Size 90micron -12%
Number of Rollers 2,In pair
Storage Silo C.B. Silo
Working principle of crupppolysius Mill:The material to be grounded is feed to the roller via an air lock. It drops the material in to the rotating grinding table thus transport under the grindingrollers. The double groove grinding rand and the adjustable height dam rings cause formation of material bed. The crushed material is transported out words over the edge of table, caught in to gas stream escaping from nozzle ring and conveyed to classifier locating directly above the grinding chamber. Classifier is classifies the finished product ,taling falls back in to middle of grinding table. Where as finished material is conveyed to esp by gas flow.
Grounded material falling through the nozzle ring is transported from discharge ringvia an air lock in to recalculating bucket elevator. After
passing through trap iron separator these return are passed back to grinding table via mill feed chute. Materisl of table is cast steel and interchanging grindingrings are made of wear resistance material. Grinding on material bed of grinding table which is rotate by motor and gear box. Each grinding roller is mounted on anty friction bearing on excel firmly clamped in to roller supports. The roller pair are guided bypins in corresponding guides on housing in such a way that they can move vertically and tilt about horizontal axis. This allows good adaptation to any changes in grinding bed height and means that the entire grinding area remains effective all time.
Raw Mill unit-2:Raw mill is one of the most important section of cement plant. In raw mill raw material is grounded enough to increase sufficient reactive surface area. So that,material can burn fasily.
The roller grinding mill can be delivered in various sizes. The characterization is described in smart form. For example:-LM50.40
In JRP vertical roller mill is used to grind the raw material. VRMconsist of four roller, which on functioning rolls over a circular table. This table is rotated with the help of a shaft attached to motor.material is introduced from the top of the VRM. Material falls down on table,and on coming in b/w roller and table get crushed. Roller and table have some specified minimum clearance b/w them, any material of large size than that clearance gets crushed inside VRM. Rollers are hydraulically supported to exert specified force on material. Crushed material gets lifted with the highly pressurized air and is taken out through an outlet to ESP.
Technical Specification of VRM unit-2:
Make Loeshe
Type LM 50.4
Capacity 450TPH
Classifier LNV
Gear box MAAG
Speed ratio 990/26RPM
Motor 5000Kw/BHEL
Feed size 100mm+2%
Residue 18%on 90 micron
No of roller 4
Storage silo C.F. silo
Working of loesche Mill:Raw material comes into raw mill from hopper through a belt conveyer via triple gate. The main function of triple gate is to prevent the entrance of falls air and to give air seales material flow. When material comes b/w rotor and roller they are crushed in to fine powder due to action of compression and alteration. Roller are hydraulically activated, a 65 bar pressure exerted by oil being used to operate the rollers. Hydraulic system is connected with rollers through connecting rod and rocker arm. Due to rotating of table, the material which is not crushed enough is rejected from mill and feed to reject bucket elevator through vibro feeder. Exit gasses from preheater and pre-calciners fed to raw mill via setting chamber to dry the raw material and to lift the fines the nuzzling velocity of air is 40-50 m/sec.
A classifier is installed just above the mill it classifies fines and course. Fineness of materials can be increased by increasing the speed of the classifier.
VRM is divided into three parts, they are:
1. Gas chamber.
2. Grinding chamber3. Classifier
Gas Chamber—In gas chamber, hot air from PC fan and PH fan enters lifts the material upward due to the counter flow. Material is taken to the cyclones by the air.Grinding chamber—In grinding chamber, grinding of material takes place b/w four rollers and the rotating table. Material in grinding chamber is introduced from hopper by belt conveyer through triple gate.Classifier—A classifier is the top most rotary part of the vertical roller mill. Here classification of material occurs. Fine particles pass through classifier and coarse particles are rejected and recycled for regrinding. According to the fineness required speed of the classifier rotor can be adjusted.
Electrostatic precipitator:Electrostaticprecipitator the dust loaded gas to flow through the chamber usally the horizontal direction in which it passes throughone or more high voltage electric from by alternate discharge electrodes and plate type collective electrodes.
Under action of the electric fields the dust particle whichhave become electrically change by the negative gas ion which are formed the discharge electrodes and attached them to the particle fly to the collecting electrodes and are deposited there the dust is rust from this electrodes by rapping and thus fall into the receive hopper at the base of the precipitator the electric charge acquired by the dust particle depend sustainability on their specific electric resistance in the lower range of opting temperature the specific resistance increase with rising temp as a result of diminishing surface couductivity.
Blending Of Raw Meal:The meal from the mill need storage and blending become different chemical composition of lime stone in different lot. They may vary the quality of lime stone.
Silo: Silos are huge construction of concrete and iron with aeration units to stone and blend the fine material such as raw material.
Continuous Blending Silo(C.B. Silo): It is suitable where sufficient degree of pre homogenization has takeplace.The raw meal is deposited in silo through several opening the actual blending take place during emptying of raw meal through the silo feed bins.
Continous Fluidize Silo: The raw meal is completely fluidized by admission of compressed air through the suitable inlets at the bottom of the silo. The air penetrates the mass of raw meal into the silo and reduces the inter particle friction forces. A circulatory motion is formed and thus homogenization is take place.
Preheater Tower:
As the name explains “Preheater Tower” is place to use for preheating the raw material. The material which comes from cf or cb silo. In other words preheater is a device in which heat transfer takes placefron hot gases which comes from kiln due to counter current flow of material
and hot gases. The raw mill is heated about 850oc before it enter it the kiln preheater with calcined system is most economical and hence the length of kiln is reduce preheater in Unit-1 and five stage in unit-2 with separator line calciner. These suspension preheaters are work in kiln string & pyro string with pre-calciner string successfully.
Reaction occurs in pre-heater:-
Temperature – range Type of Reaction100-300oc Loss of water
400-600oc Removal of inherent gases
500-600oc Structural change in silicate phase
600-850oc Dissociation of carbonate
Main part of suspension Pre-heater:
1. Cyclone: The cyclone is use for separation of raw meal from gas flow. For improving the separating efficiency of cyclones of top most preheater stage. We have designed as double separator.
2. Gas Duct: The gas duct are to join the individual cyclone stages to each other. The raw meal coming from next higher stage end in the gas duct underneath. The raw meal particles are entering by the upward flowing gas stream and taken to the next cyclone. The heal exchange is achieved by con-current flow. The gas ducts b/w stage 1 and 2 consist of the cylindrical suction.
3. The Double Flow Box: These are used for raw meal pipes in preheater system the flaps are consist in such a manner that a minimum flow of raw mill is always maintain. The full material causes a upward and downward moment of the pendulum flaps and thus and upward and downward rocking motion of the lever
arm with counter weight penetrating the single flaps. The upward and downward forces of flaps is remains constant.
4. Raw Material distributor: It is integral part of raw meal ducts and spits a downward flowing stream of raw meal in to raw meal duct. Basically the distributor has a two fold function.
Calciner:The main purpose of the precalciner is to let the calcinations process take place out side the rotary kiln. It causes in sufficient reduction of thermal load of the kiln burning as approximately 60% of total fuel is burn in to calciner. This has made possible to increase the production in the given size to about double compared to a conventional dry process kiln with suspension preheater.
The calciner consist of a vessel lined with heat resistance bricks.Calcine has three inputs and one output.
Input- 1. Fuel as Pulverized coal.2. Preheated material to approx 800oc3. Hot gases from kiln/coolers at 800oc
Output-Hot gases including combustion products and co2 from the calcinations process and material in form of dust carried with the hot gases.
Technical specification of Precalciner:
Coal firing 60%
Temperature 1000oc
Calcination 95%
Burner 2 nos
Burner capacity 20TPH
Amount of coal fire 18TPH
Rotary kiln:
Kiln is cylindrical rotary equipment rotating on supporting rollers at about 3.5 RPM. Discharge in its completing calcinations reaction. Firing is done from kiln outlet with the help of burner pipe.
Kiln inlet: Kiln inletis seated by sealing arrangement. Greasing is done by pneumatic pump seal. It consist of 10-14 segment so it can be mounted and disassembled from kiln inside. A conical section forms an extension of the inlet ring. A brick retaining ring has been mounted at the end of conical section.
Girth Gear: Kiln is rotating by Gear – pinion arrangement. Girth gear is mounted on kiln with the help of spring plates.
Thrust Roller: The function of thrust roller is to control axial moment of kiln in both upward & downward.
Supporting Roller &Tyre: Supporting roller are for support of kiln. They are in contact with tyre which are fitted in kiln shell.
Kiln Outlet: There is a sealing arrangement in kiln outlet.
Burner Pipe: It is for firing of fine coal into the kiln. Air is controlled by damper and fine coal by solid flow meter. Duplex type of burner is used in kiln unit-1 and swirlex type burner is used in kiln burner unit-2.
Kiln cooler:
Technical Specification of Grate cooler:
Type Folax
Make FLS(Germany)
Capacity 5500 TPD
Size 37.8m length*5.1m width
No. of gates 4 nos
No. of cooling Air fan 11 nos
Clinker cooler has two main function to perform. They are:-
1. To cool the hot clinker quickly.2. To provide necessary air for burning of coal in precalciner and kiln.
After introducing of red hot clinker into the cooler, mechanically driven gates moves it to the rear end of cooler. Three pair of gates are installed inside the cooler. A single pair consist of fixed gate and movable gate. Too and fro moment of movable gate pressurized which cools it quickly.
Clinker cools down gradually as it moves, due to the air blow by the fans which is taken from the atmosphere. Air falling over clinker is highly pressurized which cools it quickly.
Clinker escaping out of the cooler is fed to a hammer crusher, since lumpy material requires crushing. Crushed material is transported to clinker silo through deep bucket conveyor. Temperature of clinker escaping out of cooler is about 208oc.
Grate Cooler operation:The grate cooler operates with a cross current principle in which the clinker is moved across the grate while cooling air blow in from below
through the grate and clinker layer. The hot clinker falls from kiln and forms clinker bed on he grate and transported through the cooler over alternatively fixed and reciprocating grates. At the inlet of first great clinker is quenched and spread evently across the cooler width by the increased cooling air. The grate is fabricated to be as possible to obtained a thick clinker layer and a uniform distribution of air through the clinker bed in the interest of heat recovery. During the clinker transport from the cooler a part of dust and small size clinker is falls from the grates and collcted into hoppers under the grates. The drag chain and rotary air lock system fed these clinker and dust in clinker transport system. A dust collection ESP is also installed beside the cooler known as cooler ESP. Exhaust gases from collection is fed to the ESP for dust collection.Grate cooler consist of:-
Cooling grate Plates Standard Plates Cooling housing Drive unit Grate aeration system Clinker crusher Conveying unit(DBC) Cooling fan
Hammer Crusher:In discharge of cooler hammer crusher is provided consisting of a rotor with shaft. Hammer are mounted on each row. Hammer are casted
made of high chrome or manganese steel. Clinker is crushed to size 15-25mm by hammer crusher.
Coal Mill:
The raw mill is grounded dried swept away by fan through the separator to bag filter or ESP. finally it is stored in to the fine coal bin hot air for coal mill is supplied by cooler exhaust hot gases or preheater outlet gases before GTC circulation. The functionof coal mill is to ground suitable grate coal and for feeding the same in to the kiln and calciner in fluidized form. Coal from stock yard is fed for stacking and reclaiming in to the stacker and re-claimer. Pre-homogenized raw coal is feed in to the coal mill hopper with the help of belt conveyer. The
raw is then fed to the coal mill VRM via weigh feeder, drag chain and screw conveyer.
Technical Specification of Coal Mill:
Unit-1 Unit-2Make Krupp Polysius Loesche
Type RM K 25/12 26.3
Capacity 35TPH 55TPH
Gear box MAAG MAAG
Motor(Kw) 700 750
No. of roller 2 in pair 3
Important Parameters Of Coal:
Residue on 90 micron=18-20% Residue on 212micron=0.4-1% Moisture =1.5% Volatile Matter =20-30% Ash content =28-32%
Coal Mill Classifier:
Unit-1 Unt-2Make LNV LNV
Gear Box Sew MAAG
Input rpm 1480 1500
Motor(Kw) 37 50
Coal Mill:-
Coal Mill is an important integral part of cement plant. Here large size of approx size 600mm, is ground fine to the size of 90 micron. Coal from coal mill is used to feed kiln and calciner. Outlet tem of coal from coal mill is different in different seasons. It is 70-750c in dry season and 80-840c in rainy season.
Coal from mines is initially crushed at crusher site. Coal is then sent to stacking making mixture homogenized. Reclaimer picks up the coal and coal is fed to the coal mill hopper through belt conveyer. Coal taken out from hopper is feed inside VRM with the help of a screw conveyer which is mounted just below the hopper. Coal inside VRM is grounded between roller and table.
Hot air from cooler ESP fan is taken inside VRM and is used for drying of coal. Fine coal from VRM moves to the cyclone, where most of the coal is separated from air and the coal which does not get collected due to ultra fine size is separated with the help of ESP.
LV separator is for separating coarse and fine particles.
Now, coal is fed to screw conveyer through rotary lock, which transport it to the FK pumps. Two FK pump delivers material to the storage bins.
There are two Storage bins, They are:-1. Kiln Bin2. Precalciner Bin
Fine Coal is then transported to the kiln and precalciner by kiln firing FK pump and precalciner FK pump respectively.
Coal Mill(Unit-1):-The material to be grounded is fed to the roller mill viaweigh feeder and drag chain. It drops the material in to rotating grinding table thus transport under the grinding roller. The double groove grinding rand
and the adjustable height dam rings cause formation of material bed. The crushed material is transport out ward over the edge of table, caught in to gas stream escaping from nozzle ring and conveyed to classifier locating directly above the grinding chamber. Classifier is classified the finished product and tailing. Tailing falls back in to middle of grounding table. Whereas finished material is conveyed to bag filter by gas flow. The reject of mill is fed towards the reject side and removed manually.
Grinding is performed by total of two rollers, combined into two roller pair and rolling on material bed of grinding table which is rotating by motor and gear box. Each grinding roller is mounted on anti friction bearing on an excel firmly clamped in to the roller support. The roller pair are guided by pins in corresponding guides on housing in such a way that they can move vertically and tilt about horizontal axis. This allows good adaptation to any changes in grinding bed height and means that the entire grinding area remains effective at all time.
Coal Mill(Unit-2):-Raw coal comes in to coal mill from hopper through a drag chain and screw conveyor the entrance of fails air is avoid to give air sealed material flow .when material comes between rotor and roller they are crushed in to fine powder due to action of compression and alteration .Roller are hydraulically activated ,hydraulic system is connected with rollers through connecting rod and rocker arm .Due to rotation of table ,the material which is not crushed enough is reject and remove manually .Exhaust gasses from cooler is fed to the mill for the drying and lifting of fine coal.
Fine material is then classified by classifier located directly above the table oh mill .Fines are then fed to the cyclone separator for separation
of fines from contaminant gases ,and tailings are fall back on the table for further grinding ,Maximum separation takes place in the cyclone and the ultra fine material is get separated by ESP ,Now, coal is fed to screw conveyor through rotary lock ,which transport it to the FK pumps .Two FK pump delivers material to the storage bins.
1. Kiln bin2. Precalciner bin
Classifier: A classifier is the top most rotary part of the vertical roller Mill . Here classification of materials occurs .Fine particles pass through classifier andcourse particles are rejecter and recycled for regrinding.According to the finenessrequired speed of the classifier rotor can be adjusted.
Cement Mill: In this section the clinker exerted from clinker silo through belt conveyer fed to the ball mill along with fly ash and gypsum to grind in powder form. For making OPC clinker grind
along with gypsum and for PPC clinker is grounded along wiyh gypsum and fly ash. The homogenized product of cement mill is stored in to the specified cement storage silo.
Process:- The material to ground is extracted in certain portion from storage hopper, this mixture is uniformly fed to the mill by means of feeding device. Feed material enters the first grinding chamber of ball mill through the inlet device.In this chamber the material is pre-crushed due to catering action of grinding media, the pre-crushed material flow through a slotted lifter wall in to a fine grinding chamber where it is
ground in to end fineness. The material flow through the slot of lifter wall in to discharge device.
The air sucked through the mill by the fan serve for material transportaeration and hence for cooling of grinding chamber. It contains a considerable amount of fines therefore, the dust laden gases is handle to the dedusting plant (bag house of ESP) via a pre separator called multi cyclone. Pre separator material is led together with the lifter dust to the finished mill product. It is mixed and handled as end product to the finished cement storage silo.
Cement Mill: Cement Mill(Ball Mill) consist of mainly:-
A rotating Steel cyclone shell cylindrical shell supported at both ends on turn-on/slide shoe bearing.
Liners for protecting the inside surface of the shell.Diaphragrms for driving the mill into two or more compartments.Grinding balls.Mill cooling system.
Details of Liners: The line which protect the shell from wearing action of clinker
and additives, also help in the grinding process. In the second compartment ”classifying” liners are used which
help to segregate the grinding media according to it’s size larger balls towards the compartment. Small balls towards the discharge end.
Diapharagms: Mill diaphargms are provided with slots through which material and venting air pass from 1st compartment to 2nd
compartment.
Grinding Media: The mill chambers are partially filled with steel ball having diameter ranging from 90mm to 60mm in 1st compartment and from 50mm ball to 17mm ball in 2nd compartment.
Heat Generation: During grinding heat is generated in the mill which if not
controlled would raise the temperature and effect cement quality.
The grinding heat is dissipated by injecting atomized water in the mill chamber which on evaporation cools down the mill to acceptable.
Dynamic Separator: Material is fed in separating disc in the separating chamber inside dynamic separator. The spread material is divided into grift lines by a recirculating air current built by a fan fall on inner core. Fine particles get separated from reconciliatory air. Counter vanes with adjustable length are fitted above the separator plate to control the fineness of particles. The fan separator disc and counter vanes can be driven by single drive. The separator is preferred for coarse separation due to the lower specific consumption.
Size of Ball charges In Chambers:
Ball Size in 1st Chamber Ball Size In 2nd Chamber90mm 50mm80mm 40mm70mm 30mm60mm 25mm
20mm17mm
Amount of Ball chargers in Compound Mill:-
First Chamber:90mm=17.5 Tons80mm=21.0 Tons70mm=17.5 Tons60mm=13.0TonSTotal=69.0 Tons
Second Chamber:50mm=13.0 Tons
40mm=15.0 Tons
30mm=16.5 Tons
25-17mm=120.5Ton
Total=165 Tons
o-Sepa Air Separator:It gives sharp classification and save energy in grinding process. The material is introduced to the o-sepa air separator which is then directed on the dispersion plate. The plate is located on the top of rotor by feed clutch. The material is then distributed by centrifugal force in the angular gap b/w rotor and guide vanes it is then followed by buffer plate which is directed the material into the center or rotor. It exit the separator through outlet duct located on the top. The reject are collected in bottom and are discharge through a wall locating at the bottom.
There are three location for air flow to the separator, the primary air comprises mill bent and ambient air, inters through the inlet path in to the separator, secondary air comprised of bent air from equipment in guiding unit and ambient air inters the separator through the separator opening. Both primary and secondary air create a vertex in
separating of the separator. Fine particles which are discharge in to the hopper are also classified by tertiary air. Rotor speed can be adjusted by the variable speed drive motor. O-sepa air separators are highly efficient they classifies a higher proportion of feed particle in to product and reject.
Sepol Air separator: This type of separator is of single rotor type and was developed by F.L. Smidth. Its design is simple, compacting and highly efficient. The material is fed in to the separator from the mill in to an upward flow of air duct below the separator this results through dispersion of material. Proper dispersion of material is very important for obtaining the high separating efficiency. Suspended material flows into the separator via vertical guide vanes which maintain the uniform velocity and distributing of material. Guide vanes are also serves as collecting plates from coarse material reject from the rotor coarse fraction falls back into the reject cone from where it is discharge through the opening. The fine or finished material leaves the separator with the flow of air and is collected in cyclone or in bag filter.
Air entering at the bottom of sepol air separator can either fresh or dustloading and it permits any degree of recirculation. When fresh air isused. Fines and tailings are cooled down to 70-75 deg. There by reducing mill cooling requirement, the complete dispersion of material is riser duct combined with uniform distribution of air not only gives high efficiency but also produces low degree wear on the separator internal liner.
Packing Plant:
In this section the cement is extracted from several cement silos and fed to the rotary packer for packing in to the bags. The weight of each bag is 50kg.
Process:There are six silos in JAYPEE REWA PLANT. Each silos heaving specified type of cement. Cement is extracted from silo at eight aeration fluidized points, there are 2-3 air slides are installed below each silo for transportation of cement in to packet bucket elevator. The cement from silo through air slides fed to the bucket elevator. Cement is then passes through the vibratory screen, these screens are used for retaining the over size material and reject it because the over sizematerial is harm full for roto packer cement which passes through the screen comes into storage hopper above each packer.
This hopper having minimum and maximum level indicator. A rotary feed valve is used to control the material level in packing machine. Cement is now fed to packer hopper and then to packing machine and spillage hopper is installed to collect the return of cement below the rotopacker.
Bag Holding and Release System:-a) Bag chair cylinder- After releasing of a bag from spout as
spout advances, towards the operator the bag chain cylinder operators and the bag chair cylinder operates and bring the bags in position. When targeted 50kg weight is reached this cylinder causes tilting of bag chair and bag discharge on belt conveyer.
b)Bag Holding cylinder- When a bag is applied on spout bag holding cylinder ,cylinder holds the bag in position. It holds the bags till target weight is being achieved.
c) Limit Switches:- Each spout has two limit switches one for sensing the position of spout before discharge on belt and
other for sensing the position of spout after the bag are discharge.
Electronic Weighing System:- The electronic weighing system is provided is to measure the weight on bag chair with the help of load cell and also perform various logic control. This can give various facilities like counting of bags and totaling of weight etc.
Working Of Roto Packer:The cement is discharge by the impeller through the filling spout in to the bags standing on saddle, which is guided parallel by theroad. The loadis transmitted from the saddle through the tension rod to the equal arm weight beam comprising two levers inter connecting by cross piece. The weight box is suspended from weight-beam. The damper’s function only when the left arm of weigh beam is descends. For quickly cutting of feed flow when specified filling weight has beenachieved. The upper flange of the cross piece causes the small weight to tilt the spring on the damper assist this action. On removal of load the right arm of weight beam is rises, this action is done again and again to fill the cement in to the 50kg bags.
