Submitted By: KUMAR SAURABH B.Tech (4th Year) Electrical & Electronics EngineeringCAMELLIA INSTITUTE OF TECHNOLOGY MADHYAMGRAM, KOLKATA Under The Guidance of: Mr. Sudipta Pal S.E. (Chem), I/C-Training DANKUNI COAL COMPLEX DANKUNI COAL COMPLEX SOUTH EASTERN COALFIELDS LTD.
CERTIFICATEThis is to certify that B.Tech student KUMAR SAURABH of Camellia Instituteof Technology (CIT), Madhyamgram , Kolkata has undergone the One Month Vocational Training (11th June – 10th July) at Dankuni Coal Complex and has prepared this project report by virtue of his Diligence and self effort.He has successfully completed every aspect of this project with a lot of sincerity while abiding with the rules of the Company. This Technical Report is a record of the work done by him. Training In Charge
ACKNOWLEDGEMENTI am fortunate to receive a hearty Co-Operation and Support from “Dankuni CoalComplex” which is very important in making the Vocational Training a Success.I am glad to get a very homely atmosphere at DCC.I am thankful to Mr. N.K. Tripathi (G.M) for allowing me to undergo the IndustrialTraining.I express my sincere most gratitude to Mr. Sudipta Pal, S.E. (Chem), I/C-Trainingfor constructive ideas and suggestions in preparation of this Project. I acknowledgehim once more for extending me to the Infrastructural Facilities of this Plant andfor providing valuable Information regarding completion of my Summer IndustrialTraining.I am grateful to the whole staff of Dankuni Coal Complex.
PREFACEAs a student of B.tech in Electrical & Electronics Engineering, I was sent toDankuni Coal Complex, Hooghly to undergo my Industrial Training duringSummer Vacation. The 30 day training was commenced from 11 th June – 10th July.In the following few pages, I have prepared a Comprehensive Report on myobservation and experience in Dankuni Coal Complex.Although the Training Period was not so long to cover up the entire Industry andits various systems due to its vastness, I have tried my best to absorb it in theoutmost.
CONTENTS1. BRIEF HISTORY OF D.C.C.2. VARIOUS SECTIONS OF THE PLANT 2.1 POWER DISTRIBUTION SYSTEM 2.2 MATERIAL HANDELLING PLANT 2.3 PRODUCER GAS PLANT 2.4 RETORT HOUSE 2.5 GAS CLEANING PLANT 2.6 TAR DISTILLATION PLANT 2.7 UTILITIES3. BRIEF IDEA ABOUT INDUCTION MOTORS 3.1 INTRODUCTION 3.2 BASIC CONSTRUCTION AND OPERATING PRINCIPLE 3.3 TYPES OF AC INDUCTION MOTORS 3.4 STARTING METHODS 3.5 PROTECTION 3.6 TYPICAL NAME PLATE OF AN AC INDUCTION MOTOR 3.7 MOTOR DUTY CYCLE TYPES AS PER IEC STANDARDS4. RATINGS OF MACHINES USED IN D.C.C5. TROUBLESHOOTINGS6. CONCLUSION
1. BRIEF HISTORY OF D.C.C.Dankuni Coal Complex was set up by Coal India Ltd. under the recommendation of the FuelPolicy Committee, to meet the growing needs of “Environmental Friendly Fuel” at requirementsof domestics & industrial sectors. The foundation stone of this plant was laid by the late PrimeMinister Smt. Indira Gandhi way back in 1981.D.C.C is situated by the side of Durgapur Expressway in the north and Janai Road railwaystation of the grand chord in the south. The complex site spread over an area of 8.5 hectors.COMPANY SET UP-Name & Address: Dankuni Coal Complex South Eastern Coal Fields Ltd. Coal India Ltd. P.O: Dankuni, Dist: Hooghly, Pin:712310(W.B)Name & Address of Head Office: South Eastern Coal Fields Ltd. Coal India Ltd. Seepat Road, Bilaspur, Pin: 495001(C.G)Products Manufactured: CIL Coke, Light Oil, Heavy Oil, CVR Oil, Dehydrated Tar, PitchCategory of Industry: Red ( Large Scale )No. of Shifts: 3 Shifts per day in rotation & also General ShiftTotal Area: 120 acresNearest Railway Station: Janai Road
2.1 Power Distribution SystemPower Supply to DCC comes from WBSEB Substation at Rishra via 33KV Double Ckt. 3 Phase3 Wire Feeders. 33 KV supply voltage is step down to 6.6 KV to distribute through out the Plantby 2 nos. of 33/6.6KV, 10/12.5MVA DY11 transformer. Power at 6.6 KV is received by 4 unitsSubstations where it is Step down to 415 A.C by two nos. of 6600/415V, 1600KVA (U/S1)2000KVA (U/S 2, 3, 4) DY11 transformer for utilization to provide Power to Motors,Lightning, Air Conditioning & other Loads.Each Substation supplies Power to a no. of Motor Control Centre (MCC) which is located nearindividual load centers.To supply survival power to plant in case of power failure from WBSEB there are 4nos. ofemergency Diesel Generators of rating 500KVA, 200KVA.For purpose of correction each Substation is equipped with 125KVAR capacity 3 PhaseCapacitor Bank.All H.T circuit breakers used in 33KV & 6.6KV ckt. Are MOCB (make BHEL, SEIMENS,ASEA & TOSHIBA). All 415V L.T breakers are ACB (make EE & L&T).Each Motor Control Center is equipped with an incoming ckt. Breaker, Bus Bar System &Individual Motor Panels. Most of Drive Motors employ Direct Online Starter (DOL Starter),however there are some Drives which use Star/Delta Starting method.Each panel of MCC generally consists of:- 1. Fuse disconnector. 2. Magnetic Contactor with suitable rating. 3. Directly or CT operated Bimetal Thermal Overload Relay. 4. Emergency Stop Push Button. 5. Control & Power ckt. wiring. 6. Suitable terminal connectors for Control & Power ckt. 7. Ammeter.STATION BATTERIES:The 33KV Substation & Gas Compressor MCC are provided with 110V D.C supply foroperation of Control & trip.In 33KV Substation the Battery Bank consists of 30 nos. of 2V Lead Acid cells.Four Unit Substations are provided with 24V DC battery.For charging of these batteries individual battery charger are present at each substation.
2.2 MATERIAL HANDELLING PLANTMaterial Handling Section is designed for the receipt of Coal in Railway Wagons & other rawmaterial by tracks & for dispatch coke & coal fines. Elaborate System of Belt Conveyors isprovided for the transport of Coal & Coke within the Plant.The total MHP is divided into 3 sections:- COAL HANDELLING SECTION CRUSHING/SCREENING SECTION COKE HANDELLING SECTIONCOAL HANDELLING SECTIONThe purpose of the Coal Handling Section is to receive coal by broad gauge open railwaywagons and other raw materials and then dispatch of coke and coal fines. Elaborate arrangementsof belt conveyors are provided for the transport of coal and coke within the plant.The sections in this plant are unloading section and feeding section.Unloading section:The sized coal (-200 mm) unloaded from the wagon tippler will be received in the hoppershaving two openings each. The hopper which is provided with rack and pinion gate feeds thecoal to inclined belt conveyor(C-2) through heavy duty vibratory feeder and discharge chute.Coal (-200mm) from the conveyor C-2 will be fed either to the conveyer C-4 above coal storagebunker or to the conveyor C-3 above coal stock area.The conveyor C-3 above open coal stock is provided with mobile tripper for stock piling the coalon the open ground. This open yard coal is loaded into tripper truck with the help of pay loaderwhich is unloaded in the manual bunker C-1 as and when required. This operation generallyoccurs when there is no coal supply from outside, by wagons. About 3000 tons of coal can bestacked in open coal stock pile. The conveyor C-4 above coal storage and out loading bunker hasa mobile tripper to fill up twenty stock bunkers. There is also one direct bunker which is filled upwith the spillage from belt. Capacity of each bunker is 500 tons. The storage bunker feeds thecoal to conveyor C-5 through discharge chutes.Reclaim conveyer C-5 will feed the coal through inclined conveyer C-6 from the coal storagebunker to crusher/screen house for crushing and screening. A belt weigher is provided on thisbelt conveyer for recording the quantities of coal to crusher/screen house.The magnetic separator is suitably provided on this inclined conveyer to remove iron impuritiesfrom coal and prevent the crusher from damage.
Besides these, a metal detector is also mounted over the conveyer for detecting any metallicpieces are 40 mm3 sizes and stopping the conveyer in case of their detection. Detection shall beindicated through a suitable hooter system.Feeding section:In this section different mesh size coal are fed to different plants of the industry as required. Coalfrom above conveyer C-6 is fed from single deck vibratory screen via discharge chutes over sizecoal+100to -200 are being separated in the screen is fed to the double roll crusher for crushingbelow 100mm from single deck vibratory screen through discharge chute. The coal fraction -25,+25 to-40 and +40to-100 mm are separated in double deck vibratory screen. (a) -25 mm coal are called coal fines which are conveyed by conveyer C-9 this rejected coal fines are then accumulated in the coal fine bunker from C-9 conveyer. The coal fine bunker has 170 tons capacity and it has 2 openings with racks and pinion gates to load the cola fines into trucks. These are then sold to the Customers (Thermal Power Plants). (b) The Coal of size -25 to -40mm will be fed to the conveyer C-8 with belt weigh for feeding Producer Gas Plant. (c) The sized coal +40 to -100 mm is fed to conveyer C-7 with the belt weigher for feeding the Retort via fixed tripper and discharge chute at the end. Belt weighers are provided for recording the quantities of coal supplied to the retort house and producer gas plant. The crusher/screen house is provided with dust extraction system for generated in screens.Main components of Coal Handling Plant: (a) Wagon Tippler:- It is used for unloading of Incoming Coal Wagons & it is one of the most vital equipment. The Wagon Tippler has two nos. of Slip Ring Induction Motors of capacity 53KW each. Each Motor has 5-step rotor resistance. Step 1-4 are used for acceleration & Speed control of Tippler. Step 5 is permanently used in the Rotor Circuit. Each Motor has D.C Electromagnetic Brake. The Magnet operates to Release & Brake thereby allows Tippler to rotate. The cylindrical cage of the tippler consists of two circular ring fitted with gear teeth and connected to a platform with travel rails, support rollers, girders, counter weights, hydraulic clamping device for wagon, from top as well as side during tippling. These are giant machines having gear boxes and motor assembly and are used to unload the coal wagons into the coal hoppers in less time where it moves down to the vibratory feeder to the discharge chute.
(b) In hauler & Out hauler: - There is arrangement of shunting IN & OUT of individual Wagon from the Tippler. These are called : INHAULER: Used to transport Wagon into the Tippler prior to unloading. OUTHAULER: Used to transport Wagon out of the Tippler after unloading.(c) Vibrating feeders:- These are electromagnetic vibrating feeders or sometimes in the form of dragging chains which are provided below the coal hoppers. The equipment is used for control and continuous removal of coal and coal hopper. Thus we can say that a vibrating feeder is used to transfer the large size materials and granular materials from the hopper to receiving device uniformly, periodically and continuously in the production flow and to feed materials into the crusher continuously and uniformly. Characteristics of vibratory feeder:- Smooth vibration, reliable operation, long service life, low noise, low power consumption, easy to adjust, simple structure, easy to install, light weight, small volume, simple maintenance.(d) Belt conveyors: - These are synthetic rubber belts that moves on metallic rollers called idlers and are used for shifting of coal from one place to other places, conveyers are seen on virtually all in the Coal Handling Plant (CHP). The Main Conveyer Belt paths can be classified as :- COAL STORAGE ROUTE COAL CHARGING ROUTE COKE DISCHARGING ROUTE The efficiency of the CHP depends on the availability and reliability of the conveyer system. In this case of emergency sufficient measures have been taken to ensure safety. For example – a pull cord switch is available at regular intervals throughout the belt which helps in operating the belt at any position in order to prevent accident.(e) Mobile tripper: -It is the discharge outlet that helps in dropping the coal at a specified point. When this tripper fills up a particular space it is shown by an indication of the tippler shifts to next position. The main Drive Mechanism of Mobile Tippler consists of :- Main Drive Motor : This drives the moving carriage chain by Sprocket Mechanism. Hydraulic Thruster Motor : Used for Braking the Carriage. Cable Drum Drive Mechanism : It is used for Reeling of Power Cable.
CRUSHING/SCREENING SECTIONA magnetic separating system is arranged on the belts (C-6 & C-2) to remove magnetic materials(mainly iron) from Coal to protect the Crusher. A Metal Detector is also placed over theConveyer to detect metallic pieces. Coal from Storage Bunker is fed to the Single DeckVibrating Screen (VS-1/2) via Discharge Chute. After being separated from this Screen Coal isfed to fixed jaw roller crusher for crushing bellow 100mm. The output of the Crusher goes outvia Single Deck Vibrating Screen through Discharge Chute.Coal fractions are carried out in different places via different Conveyers.The size -25 to -40mm coal will be fed to the conveyer C-8 with belt weigh for feedingProducer Gas Plant.The sized coal +40 to -100 mm is fed to conveyer C-7 with the belt weigh for feeding the Retortvia fixed tripper and discharge chute at the end.Sizes of-25 mm coal are called coal fines which are conveyed by conveyer C-9. The coal finebunker has 170 tons capacity. These are then sold to Thermal Power Plants.COKE HANDELLING SECTIONConveyers (C0-1,CO-2,CO-3 & CO-4) bellow the four row of Retorts through travelling Cokechute and transfer to conveyer (C0-5/6) in front of Retort House through Discharge Chute withFlap Gate. Through Discharge Chute Coke is carried out to Connecting Conveyers (C0-7, CO-8)to Coke Screening House where it is lead to Single Storage Bunkers by Conveyers (CO-9, CO-10). The Coke Storage Conveyers (CO-9, CO-10) are provided with Mobile Tippler to feedCoke.
2.3 PRODUCER GAS PLANTObjective:The main aim of this plant is burning of coal in presence of air and steam to produce clean andlow Calorific value fuel gas to heat 5 benches of Continuous Vertical Retort (CVR) located inthe Retort House.Pyrolysis is the process of cracking of macromolecule into smaller more volatile components.This process of Pyrolysis is conducted in a Gasifier where coal is burnt with limited supply of airand steam to produce Top gas, Bottom gas and Solid residue (Cinder).During gasification the fuel( biomass) is heated to high temperature, which results in theproduction of volatile compounds and solid residues. The quantity and composition of thevolatile compounds depends on the reactor temperature and type, the characteristics of the fueland a degree to which various chemical reaction occur within the process. The primary reactionsthat occurs in presence of oxygen results in conversion of the fuel to CO and CO2. Thesereaction are very fast and exothermic which provide energy to sustain other gasification reaction.Gasification of other solid material occurs at high temperature and produces Gases, Tar and Ash.Generally these reactions are carried out in presence of reactive agents such as O2 and Steam.H2 produced is added to the reactor to aid in chemical conversion of char to volatile compound.TYPES OF ELECTRICAL DRIVES /EQUIPMENTS in P.G.P a. Hydraulic Pump for Gasifiers: This Motor driven pumps are used to supply high pressure Hydraulic fluid to a set of reciprocating cylinders which moves the Gasifiers Grate in a Circular motion thereby providing automatic removal of ash & Char from the Gasifier. The reciprocating motion of the Hydraulic cylinder is achieved through a no. of Electrically operated Solenoid Valves & Limit Switches. b. Vibrating Screens: These Motors driven screens are used to feed properly sized coal from individual Coal Bunkers into the Lock Hopper of the Gasifiers. c. Coal Fines Conveyers: Down sized Coal from the vibrating Screens are carried by this Chain Conveyer for Storage in Storage Bunker. d. Air Blower: The process of manufacture of producer Gas, air & Steam is required to be blown over bed of Red Hot Coal. Air Blower serves purpose of maintaining this Air flow.
This in turn helps to maintain positive Draft at the Inlet Header of the Gas Pipe of the Retort.e. Electrostatic Precipitators (ESP): Two nos. of ESP are used to separate Tar particles from Top Gas. This is achieved by passing the gas in between a Discharge Electrode and a Collecting Pipe maintained at very high Potential Difference (60 KV DC). At such a high Potential difference ionized air particles is achieved by the effect of negative Corona. The negatively charged particles are attracted to positive Collecting pipes (positive is earthen) and hence separated from the Top Gas.
2.4 RETORT HOUSEHere Coal is carbonized in Continuous Vertical Retorts while continuously moving downwardthrough the Carbonizing Zone. Destructive distillation of coal is the process of pyrolysisconducted in a distillation apparatus retort in absence of air to form the volatile products, whichare collected from the top and solid residue from the bottom. This application relates to a methodand apparatus in which coal is converted to gas, liquid and solid products by a integralcombination of pyrolysis, gasification and possibly Fischer- Tropsch synthesis. Destructiondistillation is not a unit operation like distillation, but a set of chemical reactions. The processentails the “cracking” (breaking up of macromolecules into smaller, more volatile, componentsand this remains a viable route to many compounds).Objective: Here in this part of D.C.C the non- coking coal of sizes +35 mm to-100 mm, having moisturecontent of 3-5%, is fed into a continuous vertical retort from the top and is carbonized whilemoving down wards through the retort. Due to the carbonization of coal, the products formedare: (a) Solid: carbonized coke. (b) Liquid: tar (c) Gaseous distillation product.Thus the objective of this process is the production of coke, tar and gases.Production:-About 800 tons per day of solid smokeless coal branded as CILCOKE is manufactured from lowash, low Phosphorous, low Sulphur Coal source.Fixed Carbon content: 62-67%Gas: 23%Volatile Matter: 3-5%Phosphorous: 0.03-0.04%Calorific Value: 5000-5500 Kcal/kg
Brief Information about the Main Components used in Retort House:-a. Hydraulic Pump Motors: This Motor provides pressurized Oil needed to work Hydraulic circuits in the Coke Discharge of the Retort.b. Flushing Liquor Pump Motor: It circulates Ammonical Liquor for spraying at the gas off - take of individual Retort in order to cool the gas , temperature to 80̊C for condensation of Tar & Ammonia which are collected in suitable time, otherwise this Tar would clog the Steam gas pipe & equipment.c. ID Fan Motors: These fans are used to circulate the flue gasses coming out of the Combustion Zone of CVR, through Fire Tubes of the Waste Heat Boilers.d. Askania: It is a Pressure Controlling Device . The Butterfly valve of Askania is kept within the Coal gas line in between the Gas Tank Pipe & Main pIpe to GCP . It maintains a positive pressure of 3.5 mm H2O Gauge inside the Retort so that infiltration is avoided. It consists of metallic diaphragm& Hydraulic system , similar to that of Retort . When the Pressure inside the Retort increases the Butterfly Valve opens to reduce the Pressure in Collecting Main & vice versa. A Bypass line is also present in the Coal Gas Line, before Askania Butterfly Valve System, which is operated manually to maintain positive pressure in case when the Askania fails. When Exhauster Gas Pressure is increased the Gas is vented fron the Retort House through Vent Valve to the Atmosphere.e. Goose neck: From the top each retort a goose neck comes out which is connected to the collecting main. As coal gas+ tar comes out in vaporized form through the neck of the retort, arrangement is made within the goose neck to cool it down from 200 deg C to 75 deg C by spraying NH3 Liquor.f. Coke Trolley: These are basically discharge Chutes mounted on Motor driven Trolley cars & facilitates the discharge of Coke on the Coke belts.g. Coke Quenching Water Pumps: These Motor driven pumps are used to supply water for Quenching of Red hot Coke discharged from the Retort onto the belt.h. Sump Pump Motors: Discharge system in the Retort as well as in other parts of the plants are designed so that Rain Water may be collected at some pits from where this water is collected & discharged into the drainage system of the plant with the help of Sump Pumps.
2.5 GAS CLEANING PLANTObjective:The Gas Cleaning Plant helps in the removal of impurities (tar, NH3, H2S) from the coal gasfrom retort.Process description:The coal gas together with (tar, NH3, H2S) enters the GCP section from retort house. A negativepressure in GCP is maintained by 2 exhausters: one is driven by motors and the other is drivenby steam. The gas first enters the primary cooler where the gas is cooled from 75-35°C. Thereare 3 vertical primary coolers in GCP. Here 75-80% tar together with ammoniacal liquor isseparated from the coal gas and is collected from the bottom of each collector.The gas from the cooler then passes through the exhauster and enters the detarrer. Here the restof tar is completely separated from the gas. There are 3 detarrers in GCP. The tar from thedetarrer and from the primary cooler is cooled in the decanter. The mixture of ammoniacal liquorand tar is collected in the liquor pit and pumped to the decanter by gravity settling tank resp.From the detarrer the gas enters the NH3 absorber section where NH3 is absorbed by 6% H2SO4pre heated at 60°C .the slurry is collected at the bottom of the absorber, then passed at thecentrifuge from where solid (NH4)2 SO4 is obtained as a fertilizer.After NH3 absorber the gas enters the naphthalene washer, where naphthalene is removed bywash oil. The H2S is removed from the coal gas by absorption. STRED FORD LIQUORconsists of soda ash , anthraquinone disulphonic acid and Sodium Ammonium Vanadate (SAV)gas enters from the lower section of H2S washer . Gas is contacted with STRED FORDLIQUOR in the special wooden packing.The base of the washer allows sufficient delay time for the Oxidant of the H2S ions to freedSulphur by Pentavalent Vanadium in the STRED FORD LIQUOR. In this way H2S is removed.Production:About 18 million cft of coal gas per day for supply in and around Kolkata and howrah. Gasesfuels being very clean in nature, would subsequently contribute to the reduction of pollutionlevel of howrah and Kolkata. D.C.C serves as gas supplier for GCGSC(Greater Calcutta GasSupply Commision).
VARIOUS UNITS OF G.C.P:-Primary Coolers:-3nos. of Primary Cooling Tower Pumps are used to circulate water to Primary Cooling Towersfor cooling of incoming Coal gas from Retort House. They also supply Cooling water tointerstate Coolers of the Gas Compressors. The action is facilitated by the use of 4nos. ofCooling Fans.Exhauster:-The Electrical Motor driven unit consists of a variable speed Squirrel Cage Induction Motorwhich drives as a Gas Compressor used to transport the gas from Retort House through othersections of P.G.P. & finally into the Gas Holder.Detarrer:-3nos. of Detarrer are available in D.C.C. to separate Tar fog from the Coal Gas being producedat the Retort. This is achieved by passing the gas in Potential Difference (30KV DC). At such ahigh Potential Difference, ionization of Tar particles is achieved by the effect of negativeCorona.Ammonia Absorber:-Here Ammonia (NH3) is reacted with dil.H2SO4 to form Ammonium Sulphate. Motor Coupledto the Pump, Slurry Pump & other Liquor Pump is main Drive in the Section.Gas Holder:-The capacity of the Gas Holder is 30000 m3. It contains clean Coal gas from GCP before beingdrawn by Gas Compressors. The Gas Holder being a Water Seal type has a built arrangement forPressure Release. It has 3 Zones to avoid excessive Pressure inside the Holder or when the gashas higher content of Impurities. The Pressure inside the Gas Holder remains 250 mm Hg WaterColumn & 10 m Height water seal is used to prevent the Gas Leakage.Gas Compressor:-There are 3 Gas Compressors. These are mainly reciprocating type, 3 Stages & used forCompressing the Gas to 19.5 kg/cm2. These are driven by 1500KW Synchronous Motors & areused to extract gas from the Gas Holder. These Synchronous Motors are used for Power Factorcorrection of the Plant as whole.There are many interstate Coolers & Separators present. Water flows in the Shell side & Gas inthe tube Side. Coolers are used to increase the Differential Pressure of the Gas & reduce thetemperature rise due to High Pressure.
Gas Chilling & Dehydration Unit:-In Dehydration unit Gas is 1 st Dehydrated to Prevent the condensation of L.O. & Moisture. Thenit goes to the Chilling unit where it is chilled with Refrigerator Freon. This condenses theMoisture & L.O present in the Gas which is knocked off in a Separator. The gas is chilled from40°C - 10°C & put in Gas grid Line.Auxiliary Drives in the Gas Compressor Section:-Blower:- It develops positive pressure to stop Combustible gasses from entering theCompressor.Oil Pump Motor/Lubrication Pump:- This is used to provide Lubricating oil to different partsof the Gas Compressor.Solvent Injection Pump:- This Motor driven Pump is used to spray the Tar dissolvingchemicals in to the Common Section header of the 1st Stage of the Compressor.Baring Gear Motor:- After the Auxiliaries are started the Synchronous Motor is started by thehelp of Baring Gear at a very low speed prior to actual Start up.
2.6 TAR DISTILLATION PLANTCoal tar is a black, viscous and sometimes semisolid fluid possessing an odor. The coal tar isfound condensed together in the aqueous gas liquor when the volatile products of the destructivedistillation of coal are cooled down.Objective:The primary objective of this plant is: (a) Dehydration of crude tar in the dehydrator column. (b) Removal of pitch from the dehydrated tar in the pitch column. (c) Separation of tar oils into light, medium and heavy fraction.The Various Sections of this Plant are: (a) Tar Distillation Section (b) Caustic Washing section. (c) De-Oiling & Springing Section. (d) De-Hydration & De-Pitching Section. (e) Primary Distillation Section. (f) Batch Distillation Section. (g) Solvent Recovery and BOD plant. (h) Tank Farm.
2.7 UTILITIESUtility is very important part of an Industry. So every Industry whatever it may be must have aUtility Section. In D.C.C the Utility Section can be divided into:De-Mineralized Water Plant:In D.C.C main water source is underground water. This water is obtained by deep tube well. Asthe water contains minerals it is highly corrosive in nature which may be harmful to theequipments used in D.C.C so the water needs to de-mineralized.Pump House:Process/Service water, Fire Water & Drinking water required for the operation of the plant issupplied from the Pump House. To meet the requirement of Service Water there are two nos. ofMotor driven Vertical Shaft Pumps. Similarly for the Fire Water there are two nos. of Motordriven Vertical Shaft Pumps and 1 Pump is Diesel Engine driven used for Emergency Section.Effluent Treatment Plant:Here the wastes from different sections of the Plants such as Solvent Recovery, DomesticSewage, Effluent from GCP, TDP and Retort House is treated and discharged.Central Laboratory:The laboratory holds the key for the formation of product by testing the raw cola or the sourcecoal and then limiting the operating temperature and pressure etc.Generally two types of analysis are done: 1. Proximate analysis. 2. Ultimate analysis.Coal gas testing is done by Orsat apparatus.Fire and Safety:Safety is the most Important Criteria of any plant. In D.C.C it has been given a main importance.Activities that seek to minimize or to eliminate Hazardous Conditions that can cause bodilyinjury. Hazards and following major emergencies are covered by this plan: 1 Fire in plant 2 Release of toxic gasses 3 Explosion 4 Collapse of structure
3. BRIEF IDEA ABOUT INDUCTION MOTORS3.1 INTRODUCTIONAC Induction Motors are the most common motors used in Industrial Motion Control Systems,as well as in main powered home appliances. Simple and rugged design, low-cost, lowmaintenance and direct connection to an AC power source are the main advantages of ACinduction motors.Various types of AC induction motors are used in different sections of Dankuni Coal Complex.Different motors are suitable for different applications. Although AC induction motors are easierto design than DC motors, the speed and the torque control in various types of AC inductionmotors require a greater understanding of the design and the characteristics of these motors.This application note discusses the basics of an AC induction motor; the different types, theircharacteristics, the selection criteria for different applications and basic control techniques.3.2 BASIC CONSTRUCTION AND OPERATING PRINCIPLELike most motors, an AC induction motor has a fixed outer portion, called the Stator and a Rotorthat spins inside with a carefully engineered air gap between the two.StatorThe stator is made up of several thin laminations of aluminum or cast iron. They are punched andclamped together to form a hollow cylinder (stator core) with slots. Coils of insulated wires areinserted into these slots. Each grouping of coils, together with the core it surrounds, forms anelectromagnet (a pair of poles) on the application of AC supply. The number of poles of an ACinduction motor depends on the internal connection of the stator windings. The stator windingsare connected directly to the power source. Internally they are connected in such a way, that onapplying AC supply, a rotating magnetic field is created.RotorThe rotor is made up of several thin steel laminations with evenly spaced bars, which are madeup of aluminum or copper, along the periphery. In the most popular type of rotor (squirrel cagerotor), these bars are connected at ends mechanically and electrically by the use of rings.The rotor is mounted on the shaft using bearings on each end; one end of the shaft is normallykept longer than the other for driving the load.
3.3 TYPES OF AC INDUCTION MOTORS:Generally, induction motors are categorized based on the number of stator windings. They are:• Single-phase induction motor• Three-phase induction motorSingle-Phase Induction MotorThere are probably more single-phase AC induction motors in use today than the total of all theother types put together. It is logical that the least expensive, lowest maintenance type motorshould be used most often. The single-phase AC induction motor best fits this description. As thename suggests, this type of motor has only one stator winding (main winding) and operates witha single-phase power supply. In all single-phase induction motors, the rotor is the squirrel cagetype.The single-phase induction motor is not self-starting. When the motor is connected to a single-phase power supply, the main winding carries an alternating current. This current produces aPulsating Magnetic Field. Due to induction, the rotor is energized. As the main magnetic field ispulsating, the torque necessary for the motor rotation is not generated. This will cause the rotorto vibrate, but not to rotate. Hence, the single phase induction motor is required to have a startingmechanism that can provide the starting kick for the motor to rotate.The starting mechanism of the single-phase induction motor is mainly an additional statorwinding (start/ auxiliary winding). The start winding can have a series Capacitor and/or aCentrifugal switch. When the supply voltage is applied, current in the main winding lags thesupply voltage due to the main winding impedance. At the same time, current in the startwinding leads/lags the supply voltage depending on the starting mechanism impedance.Interaction between magnetic fields generated by the main winding and the starting mechanismgenerates a resultant magnetic field rotating in one direction. The motor starts rotating in thedirection of the resultant magnetic field.Once the motor reaches about 75% of its rated speed, a centrifugal switch disconnects the startwinding. From this point on, the single-phase motor can maintain sufficient torque to operate onits own.Three-Phase Induction MotorThree-phase AC induction motors are widely used in industrial and commercial applications.They are classified either as Squirrel Cage or Wound-Rotor motors.Another class of Induction Motor is Synchronous Motor.These motors are self-starting and use no capacitor, start winding, centrifugal switch or otherstarting device.They produce medium to high degrees of starting torque. The power capabilities and efficiencyin these motors range from medium to high compared to their single-phase counterparts. Popularapplications include grinders, lathes, drill presses, pumps, compressors, conveyors, also printingequipment, farm equipment, electronic cooling and other mechanical duty applications.
3.4 STARTING METHODS of THREE PHASE INDUCTION MOTORSOnce a supply is connected to a Three Phase Induction Motor a Rotating Magnetic Field will beset up in the Stator; this will link and cut the Rotor bars which in turn will induce Rotor currentsand create a Rotor field which will interact with the Stator field and produce rotation. Of coursethis means that the three phase induction motor is entirely capable of self starting.The need for a starter therefore is not, conversely enough, to provide starting but to Reduceheavy Starting Currents and provide Overload and Under-Voltage Protection.The most commonly used Starters in D.C.C are:- 1. DOL ( Direct On Line ) Starter 2. Star/Delta Starter1. Direct On Line ( DOL ) StarterThis is the most common and simple Starting Method. The components consist of only a mainContactor and Thermal or Electronic Overload Relay. The disadvantage with this method is thatit gives the highest possible starting current. A normal value is between 6 to 7 times the ratedmotor current but values of up to 9 or 10 times the rated current exist. During a Direct-on-Linestart, the starting torque is also very high, and is usually higher than required for mostapplications.The main components in DOL Starter Panel of a Motor are: i. Fuse-Disconnecter-Switch unit commonly called Fuse Switch unit. ii. The Magnetic Capacitor of suitable Capacity. iii. Direct or CT operated Bimetal Thermal Overload Relays. iv. Control Circuit for Starting and Stopping the Motor.2. Star/Delta StarterIt achieves an effective reduction of starting current by initially connecting the stator windings instar configuration which effectively places any two phases in series across the supply. Starting instar not only has the effect of reducing the motor’s start current but also the starting torque. Onceup to a particular running speed a Triple Pole Double Throw Switch changes the windingarrangements from star to delta whereupon full running torque is achieved. Such an arrangementmeans that the ends of all stator windings must be brought to terminations outside the casing ofthe motor.This starting method only works when the application is light loaded during the start. If themotor is too heavily loaded, there will not be enough torque to accelerate the motor up to speedbefore switching over to the delta position. When starting up, the load torque is low at thebeginning of the start and increases with the square of the speed. When reaching approximately80-85% of the motor rated speed the load torque is equal to the motor torque and the accelerationceases. To reach the rated speed, a switch over to delta position is necessary, and this will veryoften result in high transmission and current peaks. In some cases the current peak can reach avalue that is even bigger than for a D.O.L start. Applications with a load torque higher than 50%of the motor rated torque will not be able to start using the star-delta starter.
The main components in Star/Delta Starter Panel of a Motor are: i. Fuse Switch unit for Isolation or Backup Protection. ii. Three nos. of Magnetic Capacitor:- Main, Star & Delta. iii. Direct or CT operated Bimetal Thermal Overload Relays. iv. Control Circuit for Starting and Stopping the Motor.COMPARISON OF THE MOTOR STARTING METHOD Criteria Direct-On-Line Star-Delta Inrush High Low Current Voltage Severe Less Severe Sags > 0.5 p.u. < 0.2 p.u. Harmonics More Less Transients Severe Less Severe
3.5 PROTECTIONThe main Electrical Faults occurring in Motor can be classified as follows:- i. Motor Overloading ii. Single Phasing iii. Stalled or Locked Rotor iv. Short Circuit v. Restricted Ventilation vi. Excessive Temperature rise of Motor vii. Faults in Relaysviii. Combined Overload or Earth Leakage FaultThe main Protective Devices used in D.C.C are:- i. Back Up HRC Fuses ( used in all MCC Panels ) ii. Thermal Overload Relays iii. Magnetic Overload Relays iv. Winding Temperature Detectors v. Combined Overload & Earth Leakage Protection vi. MCCB ( Molded Case Circuit Breaker ) vii. Oil Circuit Breakerviii. Vacuum Circuit BreakerMaintenance in D.C.C can be broadly classified as:- i. Corrective Maintenance/Breakdown Maintenance This type of maintenance is actively carried out whenever there is case of Discontinuation or Disruption in Service of particular running Machines. Common Break Down maintenance jobs are carried out by Shift Personals; include Basic Trouble Shooting, Diagnostic & appropriate Corrective actions. Problems related to Motor such as Bearing Damages, Damage/Burning terminal leads, Terminal box, Cooling fans, Fan Cover are undertaken at Site Workshop of Electrical Department. ii. Preventive Maintenance Preventive Maintenance or time based maintenance is carried out in order to maintain the health of Equipments and reduce the chances of failure during operation. These Maintenance Schedules include: Daily Maintenance Weekly Maintenance Monthly Maintenance Half Yearly Maintenance
3.6 TYPICAL NAME PLATE OF AN AC INDUCTION MOTORA typical name plate on an AC induction motor has:Term DescriptionVolts Rated terminal supply voltage.Amps Rated full-load supply current.H.P. Rated motor output.R.P.M Rated full-load speed of the motor.Hertz Rated supply frequency.Frame External physical dimension of the motor based on the NEMA standards.Duty Motor load condition, whether it is continuos load, short time, periodic, etc.Date Date of manufacturing.NEMA Design This specifies to which NEMA design class the motor belongs to.Service Factor Factor by which the motor can be overloaded beyond the full load.Efficiency Motor operating efficiency at full load.PH Specifies number of stator phases of the motor.Pole Specifies number of poles of the motor. Specifies the motor safety standard
3.7 MOTOR DUTY CYCLE TYPES AS PER IEC STANDARDSNo. Ref. Duty Cycle Type Description1. S1. Continuous running Operation at constant load of sufficient duration to reach the thermal Equilibrium.2. S2. Short-time duty Operation at constant load during a given time less than required to reach the thermal equilibrium followed by a rest.3. S3. Intermittent periodic duty A sequence of identical duty cycles, each including a period of operation at constant load and a rest (without connection to the mains).4. S4. Intermittent periodic duty A sequence of identical duty cycles, with starting each consisting of a significant period of starting, a period under constant load and a rest period.5. S5. Intermittent periodic duty A sequence of identical cycles, each with electric braking consisting of a period of starting, a period of operation at constant load, followed by rapid electric braking and a rest period.6. S6. Continuous operation A sequence of identical duty cycles, periodic duty each consisting of a period of operation at constant load and a period of operation at no-load.7. S7. Continuous operation A sequence of identical duty cycles, periodic duty with electric each consisting of a period of starting, a braking period of operation at constant load, followed by an electric braking.8. S8. Continuous operation A sequence of identical duty cycles, periodic duty with related each consisting of a period of operation load and speed changes at constant load corresponding to a predetermined speed of rotation, followed by one or more periods of operation at another constant load corresponding to the different speeds of rotation.9. S9. Duty with non-periodic Duty in which, generally, the load and load and speed variations the speed vary non-periodically within the permissible range. This duty includes frequent overloads that may exceed the full loads.
4.2 TABLE: 2 SECTION: PRODUCER GAS PLANT (PGP) RATING OF MOTORS NAME RATING VOLTAGE CURRENT SPEED DUTY (KW/HP) (V) (A) (RPM) HYDRAULIC PUMP FOR 22/33 415 40 1460 S1GASIFIER(5+1) AIR 30/40 400/400 53 1465 S1 BLOWER(3) VIBRATING 1500 S1 5.5 9.6 SCREEN (5) (Synchronous) CHAIN S1 1500 CONVEYOR 2.2/2.5 415 4 (Synchronous MOTOR TAR S1 1500 TRANSFER 4.5/5.5 415 8 (Synchronous PUMP
4.4 RATING OF RECTIFIER TRANSFORMER (DETARER) SECTION: GAS CLEANING PLANT (GCP) MAKE: ADVANI OVERLIKON LTD.1. TRANFORMER KVA : 21.2 AC INPUT : 415V, 51A FREQUENCY : 50Hz PHASE : Single TYPE OF COOLING : ON PEAK VOLTAGE : 33000V, 350MA OPERATION VOLTAGE : 25000V, 250MA2. LINEAR REACTOR KVAR : 7.6 VOLTAGE : 149V AMPS : 51A PHASE : Single3. ELECTRONIC CONTROLLER FOR HV RECTIFIER RATED INPUT VOLTAGE : 415V AC 50Hz RATED INPUT CURRENT : 51A RATED OUTPUT : 33000V, DC RATED OUTPUT CURRENT : 350MA, DC No of Electrodes : 145
5. TROUBLESHOOTINGS Problem Solution Motor Overloading Reduce Load or try to Start Uncoupled from Load. Control Gear Defective Examine each steps of Control Gear for bad contact or Open Circuit. Make sure that Brushes are making Good Contact with the Rings. Rotor Defective Look for broken Rings. Poor Stator Coil Connections Remove end Shields & check end Connections.Mechanical Locking in Bearing or Air Gap Dismantle and Repair, Clean air gaps if Chocked. Wrong Rotation This is caused by Wrong Sequence of Phases. Reverse Connections at Motor or at Switch Board. Motor’s One Phase Open Check to make sure all Leads are Connected Properly. Grounded Coil Locate and RepairMotor Overheat while running under Load May be caused if Rotor rubs Stator bore. If poor matching, replace worn bearings. Unequal Terminal Voltage Check Leads and Connections. Single Phase Operation Check for Open Contacts. Brushes are not in proper position See that Brushes are properly seated and shunt in Good Condition.
6. CONCLUSIONDuring the last 30 days, I have been on Vocational Summer Training in Dankuni Coal Complex.I have gained some basic knowledge about Practical Applications of Engineering Theory intoPractice. I am very much hopeful that in the coming years of my Career, this Experience willhelp me to integrate Theory and Practical and develop myself into a through bred professional.As a student of Technical Education it is very fortunate to me that all types of Live Problems andtheir Remedies are seen by me. I have seen how the Critical Problems may be solved in a Simpleway. Another experience that I have gathered in these days is about Precautions and Safetymeasures. I would once again like to thank sincerely all those who have extended their hand ofco-operation to make my Training days in Dankuni Coal Complex a success. I am thankful to allthe Employs and Managements for giving me their Valuable time in their Occupational BusySchedules.