sourish bhattacharyya

1

Industrial TRAINING

AT

COAL INDIA LIMITED

DANKUNI COAL COMPLEX

DANKUNI, HOOGHLY

WEST BENGAL

SOUTH EASTERN COALFIELDS LTD.

2

TRAINEE NAME: - SOURISH BHATTACHARYYA

INSTITUTE: - HOOGHLY ENGINEERING AND

TECHNOLOGY COLLEGE

DEPARTMENT: - ELECTRICAL ENGINEERING

QUALIFICATION: - B.TECH, 6TH SEMESTER, 3RD YEAR

TRAINING PERIOD: - 16.06.2014 - 12.07.2014

Under The Guidance of

Mr. Sudipta Pal

S.E. (Chem.), I/C-Training

DANKUNI COAL COMPLEX

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ACKNOWLEDGEMENT

I am fortunate to receive a hearty Co-Operation and Support from “Dankuni Coal Complex” 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. S. K. Neogi (G.M) for allowing me to undergo the Industrial Training.

I express my sincere most gratitude to Mr. Sudipta Pal, S.E. (Chem.), I/C-Training, Anirudha Chakraborty, S.E. (EE) for constructive ideas and suggestions in preparation of this Project. I acknowledge him once more for extending me to the Infrastructural Facilities of this Plant and for providing valuable Information regarding completion of my Summer Industrial Training.

I am grateful to the whole staff of Dankuni Coal Complex.

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PREFACE

Practical knowledge means the visualization of the knowledge, which we read in our books. For this, we perform experiments and get observations. Practical knowledge is very important in every field. One must be familiar with the problems related to that field so that he may solve them and become a successful person. After achieving the proper goal in life, an engineer has to enter in professional life.

As a student of B.Tech in Electrical Engineering, I was

sent to Dankuni Coal Complex, Hooghly to undergo my

Industrial Training during Summer Vacation. The 30 day

training was commenced from 16th June – 12th July.

In the following few pages, I have prepared a

Comprehensive Report on my observation and experience

in Dankuni Coal Complex.

Although the Training Period was not so long to cover up

the entire Industry and its various systems due to its

vastness, I have tried my best to absorb it in the outmost.

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COVER INDEX

CONTENT PAGE NO

BRIEF HISTORY OF D.C.C.

PROCESS DIAGRAM OF D.C.C.

07

08

POWER DISTRIBUTION SYSTEM

ONE LINE DIAGRAM OF SUBSTATION

09

11

MATERIAL HANDELLING PLANT

COAL HANDELLING SECTION

MAIN COMPONENTS OF COAL HANDELLING PLANT

CRUSHING/SCREENING SECTION

COKE HANDELLING SECTION

13

13

15

16

17

PRODUCER GAS PLANT

TYPES OF ELECTRICAL DRIVES IN P.G.P.

17

18

RETORT HOUSE

BRIEF INFORMATION ABOUT THE MAIN COMPONENT USED IN RETORT HOUSE

18

20

GAS CLEANING PLANT

VARIOYS UNITS OF G.C.P. AUXILIARY DRIVES IN THE GAS

COMPRESSSOR SECTION

21

22

23

6

TAR DISTILLATION PLANT 23

UTILITIES 24

BRIEF IDEA ABOUT INDUCTION

MOTORS

BASIC CONSTRUCTION AND

OPERATING PRINCIPAL

TYPES OF INDUCTION MOTORS

STARTING METHOD OF THREE PHASE

INDUCTION MOTORS

COMPARISON OF THE MOTOR

STARTING METHOD

PROTECTION

TYPICAL NAME PLATE OF AN

INDUCTION MOTOR

MOTOR DUTY CYCLE AS PER IEC

STANDARDS

25

26

26 28 29 29 31

32

RATINGS OF MACHINES USED IN D.C.C. 33

TROUBLESHOOTINGS 40

CONCLUSION 41

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BRIEF HISTORY OF D.C.C. Dankuni Coal Complex was set up by Coal India Ltd. under the recommendation

of the Fuel Policy Committee, to meet the growing needs of “Environmental

Friendly Fuel at requirements of domestics & industrial sectors. The foundation

stone of this plant was laid by the late Prime Minister Smt. Indira Gandhi way

back in 1981.

The factory of Dankuni Coal Complex under Coal India Limited was set up

in May, 1990 at Dankuni in the district of Hooghly (W.B.) in between Durgapur

Express Highway and Howrah-Bardhaman Chord Line adjacent to Janai Railway

Station (Eastern Railway). The Factory has a total area of 121 acres of land and is

engaged in carbonisation of coal and recovery of by-products.

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, Bilaspore, Pin: 495001(C.G)

Products Manufactured: CIL Coke, Light Oil, Heavy Oil, CVR Oil,

Dehydrated Tar, Pitch, Coal Gas

Category of Industry: Red (Large Scale)

No. of Shifts: 3 Shifts per day in rotation & also General

Shift

Total Area: 120 acres

Nearest Railway Station: Janai Road

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PROCESS FLOW DIAGRAM OF D.C.C

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Power Distribution System

Power Supply to DCC comes from WBSEB Substation at Rishra via 33KV

Double Ckt. 3 Phase 3 Wire Feeders. 33 KV supply voltage is step down to 6.6 KV

to distribute throughout the Plant by 2 nos. of 33/6.6KV, 10/12.5MVA DY11

transformer. Power at 6.6 KV is received by 4 units Substations where it is Step

down to 415 A.C by two nos. of 6600/415V, 1600KVA (U/S 1),2000KVA (U/S 2, 3,

4) DY11 transformer for utilization to provide Power to Motors, Lightning, Air

Conditioning & other Loads. One line from the 33 KV substations directly goes to

the Gas Compressors where the TOSHIBA motors require an input of direct

6.6KV

Each Substation supplies Power to a no. of Motor Control Centre (MCC) which is

located near individual load centers.

To supply survival power to plant in case of power failure from WBSEB there are

4nos. of emergency Diesel Generators of rating 500KVA, 200KVA.

For purpose of correction each Substation is equipped with 125KVAR capacity 3

Phase Capacitor 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.

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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

for operation 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.

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ONE LINE DIAGRAM OF SUBSTATION

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The main plants/units of the factory engaged

in production process are:

1) Material handling Plant (MHP): This section has two

parts as follows.

(i) Coal Handling Section

(ii) Crushing Section

(iii) Coke Handling Section

2) Retort House (RH)

3) Producer Gas Plant (PGP)

4) Gas Cleaning Plant (GCP)

5) Tar Distillation Plant (TDP)

6) Utility (Boiler, Air Compressor, De-Mineralized Water,

Pump House, Effluent Treatment Plant)

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MATERIAL HANDELLING PLANT

Material Handling Section is designed for the receipt of Coal (400mm) in Railway

Wagons & other raw material (including stones, dust and coal fines) by tracks &

for dispatch coke & coal fines. Elaborate System of Belt Conveyors is provided for

the transport of Coal & Coke within the Plant.

The total MHP is divided into 3 sections:-





The purpose of the Coal Handling Section is to receive coal by broad gauge open

railway wagons and other raw materials and then dispatch of coke and coal fines.

Elaborate arrangements of 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 coal is unloaded by the Rotary Wagon Tippler, rotating the whole railway

wagon by an angle of 165º.The sized coal (-200 mm) unloaded from the wagon

tippler will be received in the hoppers having two openings each. The hopper

which is provided with rack and pinion gate feeds the coal 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

storage bunker 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 coal on the open ground. This open yard coal is loaded into tripper truck

with the help of pay loader which is unloaded in the manual bunker C-1 as and

when required. This operation generally occurs when there is no coal supply from

outside, by wagons. About 3000 tons of coal can be stacked in open coal stock pile.

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The conveyor C-4 above coal storage and out loading bunker has a mobile tripper

to fill up twenty stock bunkers. There is also one direct bunker which is filled up

with the spillage from belt. Capacity of each bunker is 500 tons. The storage

bunker feeds the coal to conveyor C-5 through discharge chutes.

Reclaim conveyer C-5 will feed the coal through inclined conveyer C-6 from the

coal storage bunker to crusher/screen house for crushing and screening. A belt

weigher is provided on this belt conveyer for recording the quantities of coal to

crusher/screen house.

The magnetic separator is suitably provided on this inclined conveyer to remove

iron impurities from coal and prevent the crusher from damage.

Besides these, a metal detector is also mounted over the conveyer for detecting any

metallic pieces are 40 mm sizes and stopping the conveyer in case of their

detection. Detection shall be indicated through a suitable hooter system.

Feeding section:

In this section different mesh size coal are fed to different plants of the industry as

required. Coal from above conveyer C-6 is fed from single deck vibratory screen via

discharge chutes over size coal+100to -200 are being separated in the screen is fed

to the double roll crusher for crushing below 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.

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Main components of Coal Handling Plant

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.

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.

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.

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).

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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.

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.


The coal received in Crusher House is first separated into above 100mm and below 100mm size with the help of a single deck vibratory screen and a discharge chute with a flap gate. Coal of +100 sizes is then fed to the roll crusher for crushing to below 100mm; this crushed coal is then screened by a double deck vibratory screen with screens of sizes 40mm and 25mm in sequence. This screening provides us with the following 3 fractions: The size -25 to -40mm coal will be fed to the conveyer C-8 with belt weigh for

feeding Producer Gas Plant.

The sized coal +40 to -100 mm is fed to conveyer C-7 with the belt weigh for

feeding the Retort via fixed tripper and discharge chute at the end.

Sizes of-25 mm coals are called coal fines which are conveyed by conveyer C-9.

The coal fine bunker has 170 tons capacity. These are then sold to Thermal Power

Plants.

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-25mm : coal fines (despatched to NTPC)

-40 and +25: For feeding to Producer Gasifiers.

+40 and -100: For feeding to Retorts.


Conveyers (C0-1, CO-2, CO-3 & CO-4) bellow the four rows of Retorts through

travelling Coke chute and transfer to conveyer (C0-5/6) in front of Retort House

through Discharge Chute with Flap 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 feed Coke.

PRODUCER GAS PLANT Objective:

The main aim of this plant is burning of coal in presence of air and steam to

produce clean and low Calorific value fuel gas to heat 5 benches of Continuous

Vertical Retort (CVR) located in the Retort House.

PGP unit‟s main responsibility is providing fuel (flue gas) to Retort House. PGP generates the Flue Gas required as a fuel in the Retort House by Fischer Process, burning -40 and +25 sized coal in limited supply of air (i.e. oxygen, incomplete combustion). This unit consists of 5 Double Stage Gasifiers with Lock Hopper system.

The top gas (120‟C) obtained from the distillation zone contains large amount of volatile materials and tar which is separated by passing it through Tar Knock-Out pots and Electrostatic Precipitator (ESP).The bottom gas obtained from the gasification zone is at comparatively higher temperature (650‟C) is dust and ash prone and hence passed through dust cyclone separator.

The cleaned top and bottom gases are then mixed and this Mixed Producer Gas (>200‟C) is sent to the Retort House for internal plant consumption as fuel through PG main.

.

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TYPES OF ELECTRICAL DRIVES /EQUIPMENTS in P.G.P

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.

Vibrating Screens: These Motors driven screens are used to feed properly sized coal

from individual Coal Bunkers into the Lock Hopper of the Gasifiers.

Coal Fines Conveyers: Down sized Coal from the vibrating Screens are carried by this

Chain Conveyer for Storage in Storage Bunker.

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.

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.

RETORT HOUSE Here Coal is carbonized in Continuous Vertical Retorts while continuously

moving downward through the Carbonizing Zone. Destructive distillation of coal

is the process of pyrolysis conducted in a distillation apparatus retort in absence of

air to form the volatile products, which are collected from the top and solid

residue from the bottom. This application relates to a method and apparatus in

which coal is converted to gas, liquid and solid products by an integral

combination of pyrolysis, gasification and possibly Fischer- Tropsch synthesis.

Destruction distillation is not a unit operation like distillation, but a set of

chemical reactions. The process entails the “cracking” (breaking up of

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macromolecules into smaller, more volatile, components and this remains a viable

route to many compounds).

Low Temperature Carbonization (LTC) of Coal is carried out in the Continuous

Vertical Retorts (CVR) producing Coal Gas and increasing the Fixed Carbon

Content from 45% (Coal) to 60% (Coke).

Objective:

Here in this part of D.C.C the non- coking coal of sizes +40 mm to-100 mm, having

moisture content of 3-5%, is fed into a continuous vertical retort from the top and

is carbonized while moving down wards through the retort. Due to the

carbonization of coal, the products formed are:

(a) Solid: Carbonized Coke.

(b) Liquid: Tar

(c) Gaseous: Coal Gas

Thus the objective of this process is the production of coke, tar and gases.

Gas consisting of:

CO2,CO,CH4,N2,O2,H2, Unsaturated Hydrocarbons[Pure Coal Gas

components];

Ammonia, H2S, Naphthalene, Tar [Impurities to be removed in GCP]

Production:-

About 800 tons per day of solid smokeless coal branded as CILCOKE is

manufactured from low ash, 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

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Brief Information about the Main

Components used in Retort House

Hydraulic Pump Motors: This Motor provides pressurized Oil needed to work

Hydraulic circuits in the Coke Discharge of the Retort.

Flushing Liquor Pump Motor: It circulates Ammoniacal Liquor for spraying at the

gas off-take of individual Retort in order to cool the gas, temperature to 80 ̊C for

condensation of Tar & Ammonia which are collected in suitable time, otherwise this Tar

would clog the Steam gas pipe & equipment.

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.

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 from the Retort House through Vent Valve to the Atmosphere.

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.

Coke Trolley: These are basically discharge Chutes mounted on Motor driven Trolley

cars & facilitates the discharge of Coke on the Coke belts.

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.

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.

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GAS CLEANING PLANT Objective:

The Gas Cleaning Plant helps in the removal of impurities (tar, NH3, H2S) from

the coal gas from retort.

Process description:

The coal gas together with (tar, NH3, H2S) enters the GCP section from retort

house. A negative pressure in GCP is maintained by 2 exhausters: one is driven by

motors and the other is driven by steam. The gas first enters the primary cooler

where the gas is cooled from 75-35°C. There are 3 vertical primary coolers in GCP.

Here 75-80% tar together with ammoniacal liquor is separated 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 rest of tar is completely separated from the gas. There are 3 detarrers in

GCP. The tar from the detarrer and from the primary cooler is cooled in the

decanter. The mixture of ammoniacal liquor and 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 5-6% H2SO4 pre heated at 60°C .The slurry is collected at the bottom of the

absorber, then passed at the centrifuge from where solid (NH4)2 SO4 is obtained

as a fertilizer.

After NH3 absorber the gas enters the naphthalene washer, where naphthalene is

removed by wash oil. The H2S is removed from the coal gas by absorption. STRED

FORD LIQUOR consists 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 FORD LIQUOR in the special wooden packing.

The base of the washer allows sufficient delay time for the Oxidant of the H2S ions

to freed Sulphur by Pentavalent Vanadium in the STRED FORD LIQUOR. In this

way H2S is removed.

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Production:

About 18 million cft of coal gas per day for supply in and around Kolkata and

Howrah. Gases fuels being very clean in nature, would subsequently contribute to

the reduction of pollution level of Howrah and Kolkata. D.C.C serves as gas

supplier for GCGSC (Greater Calcutta Gas Supply Commission).

VARIOUS UNITS OF G.C.P

Primary Coolers: - 3nos. of Primary Cooling Tower Pumps are used to circulate water

to Primary Cooling Towers for cooling of incoming Coal gas from Retort House. They

also supply Cooling water to interstate Coolers of the Gas Compressors. The action is

facilitated by the use of 4nos. of Cooling Fans.

Exhauster:- The Electrical Motor driven unit consists of a variable speed Squirrel Cage

Induction Motor which drives as a Gas Compressor used to transport the gas from

Retort House through other sections 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 produced at the Retort. This is achieved by passing the gas in Potential

Difference (30KV DC). At such a high Potential Difference, ionization of Tar particles is

achieved by the effect of negative Corona.

Ammonia Absorber: - Here Ammonia (NH3) is reacted with dil.H2SO4 to form

Ammonium Sulphate. Motor Coupled to 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 being drawn by Gas Compressors. The Gas Holder being a Water Seal

type has a built arrangement for Pressure Release. It has 3 Zones to avoid excessive

Pressure inside the Holder or when the gas has higher content of Impurities.

Gas Compressor: - There are 3 Gas Compressors. These are mainly reciprocating type,

3 Stages & used for Compressing the Gas to 19.5 kg/cm2. These are driven by 1500KW

Synchronous Motors & are used to extract gas from the Gas Holder. These Synchronous

Motors are used for Power Factor correction of the Plant as whole.

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There are many interstate Coolers & Separators present. Water flows in the Shell side

& Gas in the tube Side. Coolers are used to increase the Differential Pressure of the Gas

& reduce the temperature rise due to High Pressure.

Gas Chilling & Dehydration Unit: - In Dehydration unit Gas is 1st Dehydrated to

Prevent the condensation of L.O. & Moisture. Then it goes to the Chilling unit where it

is chilled with Refrigerator Freon. This condenses the Moisture & L.O present in the Gas

which is knocked off in a Separator. The gas is chilled from 40°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

the Compressor.

Oil Pump Motor/Lubrication Pump: - This is used to provide Lubricating oil

to different parts of the Gas Compressor.

Solvent Injection Pump: - This Motor driven Pump is used to spray the Tar

dissolving chemicals 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 the help of Baring Gear at a very low speed prior to actual Start up.

TAR DISTILLATION PLANT

Coal tar is a black, viscous and sometimes semisolid fluid possessing an odor. The

tar collected in all the gas separators located in PGP, Retort and GCP are all

collected in 2 intermediate storage tanks, where ammonia liquor is separated from

which the tar ultimately reaches Tar Storage Tank. The tar is sent to the

dehydration unit after being heated to 120„C using steam which results in tar

moisture converting to steam.

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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.

UTILITIES

Utility is very important part of an Industry. So every Industry whatever it may be

must have a Utility 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. As the water contains minerals it

is highly corrosive in nature which may be harmful to the equipments 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 is supplied from the Pump House. To meet the

requirement of Service Water there are two nos. of Motor driven Vertical Shaft

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Pumps. Similarly for the Fire Water there are two nos. of Motor driven 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, Domestic Sewage, 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 source coal and then limiting the operating

temperature and pressure etc. Generally two types of analysis are done:

1. Proximate analysis

2. Ultimate analysis

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 bodily injury. 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

BRIEF IDEA ABOUT INDUCTION MOTORS

INTRODUCTION

AC 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, low maintenance and direct connection to an AC power source are the main advantages of AC induction motors. Various types of AC induction motors are used in different sections of Dankuni Coal Complex. Different motors are suitable for different applications. Although

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AC induction motors are easier to design than DC motors, the speed and the torque control in various types of AC induction motors require 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, their characteristics, the selection criteria for different applications and basic control techniques.

BASIC CONSTRUCTION AND OPERATING PRINCIPLE

Like most motors, an AC induction motor has a fixed outer portion, called the Stator and a Rotor that spins inside with a carefully engineered air gap between the two.

Stator

The stator is made up of several thin laminations of aluminum or cast iron. They are punched and clamped together to form a hollow cylinder (stator core) with slots. Coils of insulated wires are inserted into these slots. Each grouping of coils, together with the core it surrounds, forms an electromagnet (a pair of poles) on the application of AC supply. The number of poles of an AC induction motor depends on the internal connection of the stator windings. The stator windings are connected directly to the power source. Internally they are connected in such a way, that on applying AC supply, a rotating magnetic field is created.

Rotor

The rotor is made up of several thin steel laminations with evenly spaced bars, which are made up of aluminum or copper, along the periphery. In the most popular type of rotor (squirrel cage rotor), 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 normally kept longer than the other for driving the load.

TYPES OF INDUCTION MOTORS

Generally, induction motors are categorized based on the number of stator windings. They are: • Single-phase induction motor • Three-phase induction motor

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Single-Phase Induction Motor

There are probably more single-phase AC induction motors in use today than the total of all the other types put together. It is logical that the least expensive, lowest maintenance type motor should be used most often. The single-phase AC induction motor best fits this description. As the name suggests, this type of motor has only one stator winding (main winding) and operates with a single-phase power supply. In all single-phase induction motors, the rotor is the squirrel cage type. 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 a Pulsating Magnetic Field. Due to induction, the rotor is energized. As the main magnetic field is pulsating, the torque necessary for the motor rotation is not generated. This will cause the rotor to vibrate, but not to rotate. Hence, the single-phase induction motor is required to have a starting mechanism that can provide the starting kick for the motor to rotate. The starting mechanism of the single-phase induction motor is mainly an additional stator winding (start/ auxiliary winding). The start winding can have a series Capacitor and/or a Centrifugal switch. When the supply voltage is applied, current in the main winding lags the supply voltage due to the main winding impedance. At the same time, current in the start winding leads/lags the supply voltage depending on the starting mechanism impedance. Interaction between magnetic fields generated by the main winding and the starting mechanism generates a resultant magnetic field rotating in one direction. The motor starts rotating in the direction of the resultant magnetic field. Once the motor reaches about 75% of its rated speed, a centrifugal switch disconnects the start winding. From this point on, the single-phase motor can maintain sufficient torque to operate on its own.

Three-Phase Induction Motor

Three-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 other starting device. They produce medium to high degrees of starting torque. The power capabilities and efficiency in these motors range from medium to high compared to their single-phase counterparts. Popular applications include grinders, lathes, drill presses, pumps, compressors, conveyors, also printing equipment, farm equipment, electronic cooling and other mechanical duty applications.

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STARTING METHODS of THREE PHASE

INDUCTION MOTORS

Once a supply is connected to a Three Phase Induction Motor a Rotating Magnetic Field will be set up in the Stator; this will link and cut the Rotor bars which in turn will induce Rotor currents and create a Rotor field which will interact with the Stator field and produce rotation. Of course this 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 reduce heavy 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 Starter

Direct On Line (DOL) Starter

This is the most common and simple Starting Method. The components consist of only a main Contactor and Thermal or Electronic Overload Relay. The disadvantage with this method is that it gives the highest possible starting current. A normal value is between 6 to 7 times the rated motor current but values of up to 9 or 10 times the rated current exist. During a Direct-on-Line start, the starting torque is also very high, and is usually higher than required for most applications. The main components in DOL Starter Panel of a Motor are:

i. Fuse-Disconnector-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.

Star/Delta Starter

It achieves an effective reduction of starting current by initially connecting the stator windings in star configuration which effectively places any two phases in series across the supply. Starting in star not only has the effect of reducing the motor‟s start current but also the starting torque. Once up to a particular running speed a Triple Pole Double Throw Switch changes the winding arrangements from star to delta whereupon full running torque is achieved. Such an arrangement means that the ends of all stator windings must be brought to terminations outside the casing of the motor.

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This starting method only works when the application is light loaded during the start. If the motor is too heavily loaded, there will not be enough torque to accelerate the motor up to speed before switching over to the delta position. When starting up, the load torque is low at the beginning of the start and increases with the square of the speed. When reaching approximately 80-85% of the motor rated speed the load torque is equal to the motor torque and the acceleration ceases. To reach the rated speed, a switch over to delta position is necessary, and this will very often result in high transmission and current peaks. In some cases the current peak can reach a value 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

Current

High Low

Voltage

Sags

Severe

> 0.5 p.u.

Less Severe

< 0.2 p.u.

Harmonics More Less

Transients Severe Less Severe

PROTECTION

The 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

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vii. Faults in Relays

viii. Combined Overload or Earth Leakage Fault

The 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 Breaker

viii. Vacuum Circuit Breaker

Maintenance in D.C.C can be broadly classified as

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.

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

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TYPICAL NAME PLATE OF AN AC INDUCTION MOTOR

A typical name plate on an AC induction motor has: Term Description

Volts 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 continuous 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

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MOTOR DUTY CYCLE TYPES AS PER IEC STANDARDS

No. Ref. Duty Cycle Type Description

1. 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

with starting


consisting of a significant period of

starting, a period under constant load and

a rest period. 5. S5. Intermittent periodic

duty

with electric braking

A sequence of identical cycles, each

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

periodic duty


consisting of a period of operation

at constant load and a period of

operation at no-load. 7. S7. Continuous operation

periodic duty with

electric

braking


consisting of a period of starting, a

period of operation at constant load,

followed by an electric braking. 8. S8. Continuous operation

periodic duty with

related

load and speed

changes


consisting of a period of operation

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

load and speed

variations

Duty in which, generally, the load and

the speed vary non-periodically within

the permissible range. This duty includes

frequent overloads that may

exceed the full loads.

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RATINGS OF MACHINES USED IN D.C.C

SECTION: MATERIAL HANDELLING PLANT

RATING OF MOTORS

NAME RATING SPEED VOLTAGE CURRENT DUTY C1 22 1500 415 40 S1 C2 125 1485 415 216.5 S1 C3 75 1480 415 133 S1 C4 125 1485 415 216.5 S1 C5 55/75 1465 415 96 S1 C6 75 1482 415 127 S1 C7 75 1480 415 133 S1 C8 15 1460 400/440 29.5 S1 C9 12 1460 415 40 S1 C10 22/30 1460 415 38 S1 C11 9.3 1450 415 17 S1 C12 9.3 1450 415 17 S1 CO1 7.5 1450 415 13 S1 CO2 7.5 1450 415 13 S1 CO5 11 1450 415 20.5 S1 CO6 11 1450 415 20.5 S1 CO7 30 1470 415 52 S1 CO8 30 1470 415 52 S1 CO9 18.5 1470 415 32 S1 CO10 18.5 1470 415 32 S1 CO11 18.5 1470 415 32 S1 CO12 18.5 1470 415 32 S1 WAGON TIPPLER

55/75 741 415Y 104 S3-40%

INHAULER 75 1520 415 127 S1 OUT HAULER

55 1500 415 96 S1

VS 1

18.5 1500 415 32 S1

VDS 1 22 1500 415 40 S1

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SECTION: PRODUCER GAS PLANT (PGP)

RATING OF MOTORS

NAME

RATING (KW/HP)

VOLTAGE (V)

CURRENT (I)

SPEED (R.P.M)

DUTY

HYDRAULIC PUMP FOR GASIFIER(5+1)

22/33 415 40 1460 S1

AIR BLOWER 30/40 400/400 53 1465 S1

VIBRATING SCREEN(5)

5.5 9.6 1500 S1

CHAIN CONVEYOR MOTOR

2.2/2.5 415 4 1500 S1

TAR TRANSFER PUMP

4.5/5.5 415 8 1500 S1

SECTION: RETORT HOUSE

RATING OF MOTORS

NAME RATING (K.W/H.P)

VOLTAGE (V)

CURRENT (I)

SPEED (R.P.M)

DUTY

HYDRAULIC POWERUNIT MOTOR

3.7 415 7.9 1500 CR

FLUSH 11 415 20 1500 S1

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LIQOUR PUMP ID FAN MOTOR

30HP 415 43 1500 S1

ASCANIA VALVE

1.5/2 415 43 1500 S1

COKE TROLLEY

0.75 415 3.4 1500 S1

COKE QUENCHING

18.5,15,22 415 32,29,40 1500 S1

SECTION: GAS CLEANING PLANT

RATING OF MOTORS


VOLTAGE (V)

CURRENT (I)

SPEED (R.P.M)

DUTY

GAS COMPRESSOR 1500 375 6600 136 CONTINIOUS SOLVENT INJECTOR PUMP

0.25 1395 220 1.36 CONTINIOUS

LUB.OIL PUMP 0.37 1400 415 1.17 CR

AUX.OIL PUMP 5.5 1445 415 11.4 CR BEARING GEAR 11 1450 415 21 CONTINIOUS EXHAUSTER 290 1492 500 400 S1 INSTRUMENT AIR COMPRESSOR

110 1475 415 189 CMR

PROCESSOR AIR COMPRESSOR

55/75 1475 415 102 S1

GAS COMPRESSOR AIR

2.2 2860 415 4.3 CONTINIOUS

PRESSURIZATION BLOWER MOTOR

2.2 2860 415 4.3 CONTINIOUS

OIL COOLER PUMP

75 2950 415+6% 124 S1

SUMP PIT PUMP 1.5 1405 415 3.4 S1 SUMP PIT PUMP 0.75 1400 415 2.1 S1 H2S WASHER 75 2980 415 130 CONTINIOUS

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SULPHUR FILTER DRIVER

0.75/1 1395 415 1.84 CR

SECTION: TAR DISTILATION PLANT

RATING OF MOTORS


VOLTAGE (V)

CURRENT (I)

SPEED (R.P.M)

DUTY

CRUDE TAR PUMP

7.5/10 2865 415 14 S1

CAUSTIC DOZING PUMP

0.37 1410 415 0.9 S1

PITCH CIRCULATION PUMP

5.5 2865 415 10 S1

PITCH PRODUCT PUMP

1.5/2 2850 415 4 S1

PITCH PRODUCT PUMP(NEW)

2.5/3 2850 415 4.6 S1

FUEL OIL PUMP

1.1/1.5 1450 415 2.7 S1

CIRCULATION PUMP

3.7 1430 415+6% 8 S1

CRUDE ACID PUMP

2.2/3 2840 415 4.7 S1

PURE TAR ACID PUMP

1.0/5.5 2850 415 8 S1

PITCH PUMP 3 2850 415 6 S1 TAR ACID PUMP

2.2 2850 415 4.6 S1

FIRE WATER PUMP

45/60 1470 415 81 S1

FEED PUMP 11/16 2900 415 21 S1 BLOWER 15/20 2900 415 28 S1

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OIL PUMP 2.2 1400 415 4.6 S1 EFFLUENT PUMP

5.5/7.5 1440 415 11.9 S1

RATING OF RECTIFIER TRANSFORMER (DETARER)

SECTION: GAS CLEANING PLANT (GCP)

MAKE: ADVANI OVERLIKON LTD.

TRANFORMER

KVA : 21.2

AC INPUT : 415V, 51A

FREQUENCY : 50Hz

PHASE : Single

TYPE OF COOLING : ON

PEAK VOLTAGE : 33000V, 350MA

OPERATION VOLTAGE : 25000V, 250MA

LINEAR REACTOR

KVAR : 7.6

VOLTAGE : 149V

AMPS : 51A

PHASE : Single

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

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HIGH VOLTAGE TRANSFORMER

RECTIFIER UNIT AT E.S.P (P.G.P)

MAKE: HIND RECTIFIERS LTD.

TYPE : OHTA/43/100

AC INPUT : 360 V, 19.71A

AC OUTPUT : 19450V, 0.1435A

KVA : 7.096

FREQUENCY : 50Hz

PHASE : SINGLE

DC VOLTAGE : 70KV/100MA

MAX.TEMP : 50degree centigrade

ACTIVE WEIGHT : 350kg

TANK : 160kg

OIL : 440kg

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RATING OF CIRCUIT BREAKER USED

IN SUBSTATIONS

MAKE ASEA : MINIMUM OIL CIRCUIT BREAKER

TYPE : 12/240

VOLTAGE : 12KV

INSULATION LEVEL : 75/35KV

FREQUENCY : 50Hz

NORMAL CURRENT : SYM/ASYM

40/44KA

STANDARD : IEC 56

OIL : 8kg

WITH BUILT IN FUSE : 6600/1100V

40

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

Rotor Defective Look for Broken Rings Poor Stator Coil Connections

Remove End Shields

Mechanical Locking in Bearing or Air Gap

Dismantle and Repair

Wrong Rotation Reverse connections at switch board or at Motor

Motor`s one Phase Open Check to make sure all leads are connected properly

Grounded Coil Locate and Repair Unequal Terminal Voltage Check Leads and

Connections Single Phase Operation Check for Open Contacts Brushes are not in Proper Position

See that the Brushes are Properly seated.

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CONCLUSION

During the last 30 days, I have been on Summer Industrial Training in

Dankuni Coal Complex. I have gained Basic knowledge about Practical

Applications of Engineering Theory into Practice.

I am very much hopeful that in the coming years of my career, this

Experience will help me integrate Theory and Practical and develop myself into

through bred professional. As a student of Technical Education it is very fortunate

to me that to me that all types of Live Problems and their Remedies are seen by me.

I have gathered in these days is about Precautions and Safety measures. I

once again like to thank sincerely all those who have extended their co-operation

to make my Training Days in Dankuni Coal Complex a success.

I am thankful to all the Employs and Managements for giving me their

Valuable Time in their occupational Busy Schedules.