PROJECT REPORT ON TITAGARH

GENERATING STATION

CESC LIMITED

AVISHEK GHOSH JADAVPUR UNIVERSITY, KOLKATA

VACATIONAL TRAINING PROJECT REPORT 13/6/2016 – 25/6/2016 (2 WEEKS)

AT TITAGARH GENERATING STATION , B.T.ROAD ,KHARDAH ,NORTH 24-PARGANAS ,

WEST BENGAL ,PIN-700119 .

AVISHEK GHOSH 1

The Project report is not just mine. It is a collective effort of many people who helped me

a lot to successfully complete this project report and without the support of whom this

project report would not have been implemented. I thank Mr.Hirak Das (HRD) for

providing me with important data, description of the whole process and assisting us

throughout the training.

I would also thank Mr. Monotosh Chowdhury (Asst.Manager, HRD) of CESC LTD for

allowing me to have training under his careful supervision at TGS.

I am also grateful to Mr. Debdutta Maitra (GM, HR), Mr. D Basak (Station Manager), for

providing me with important data, description of the whole process and assisting us

throughout the training.

I am very grateful to Joydeb da for making me understand the operations and instruments

from the very grassroots level.

I would also thank all the employees of Instrumentation Maintenance Department for

explaining the operation details of the instruments at TGS.

Lastly I would like to thank the entire staff at TGS for their support. It has been a privilege

to have them by my side throughout the training period from 13.06.2016 to 25.06.2016.

Their tireless guidance, co-operation has led me to successful completion of this

vacational training.

DATE: 25th JUNE, 2016 AVISHEK GHOSH

(3RD YEAR MECHANICAL)

JADAVPUR UNIVERSITY

KOLKATA

ACKNOWLEDGEMENT

AVISHEK GHOSH 2

SL. No. TOPIC Pg. No. 1 ACKNOWLEDGEMENT 1

2 ABOUT CESC LIMITED 3

3 TITAGARH GENERATING STATION (TGS) 4 4 LOCATION OF A POWER PLANT 5

5 CYCLES OF A THERMAL POWER PLANT 7 6 ENERGY TRANSFORMATION IN STEAM POWER PLANT 10

7 THERMODYNAMIC CYCLES IN STEAM POWER PLANT 10

i) RANKING CYCLE 10 ii) REGENERATIVE RANKING CYCLE 12

8 DE-MINERALISED WATER PLANT 13 9 COAL HANDLING PLANT 16

10 BOILER 22 11 TURBINE 27

12 CONDENSER 28

13 ALTERNATOR 29 14 ELECTRO-STATIC PRECIPATOR 31

15 ASH REMOVAL SYSTEM 33 16 BASIC INSTUMENTS AT TGS 35

17 DISTRIBUTED CONTROL SYSTEM 37

18 CONCLUSION 39

CONTENTS

AVISHEK GHOSH 3

History and Generating capacity of different plants of CESE Limited.

STATS DATA CESE LIMITED LICENSE AREA 567 Sq.Km

No OF CONSUMERS 2.9 Million

No OF EMPLOYEES 10000 (approx.) GENERATION CAPACITY 1125 MW

SUBSTATION CAPACITY 7483 MW POWER GENERATION IN YEAR 2010-2011 8756 MU

Few stats about CESE Limited.

Generating Station

Year of starting

Installed

capacity

Feature of

boiler

Titagarh (TGS)

1983

(4X60)MW

Pulverized fuel

Southern (SGS)

1991

(2x67.5)MW

Pulverized fuel

Budge Budge (BBGS)

1997

(3x250)MW

Pulverized fuel

Calcutta has come a long way on the wings of power. CESC Ltd, a power utility

in India was set up in 1897. It was first Thermal Power Generation Co. in

India. In 1989 CESC became a part of RPG group which has a strong presence

in the fields of power generation, transmission network & distribution

network.

From its first DC station at Emambaugh Lane operating from April of 1899.

Units of CESC now became an ISO 9001: 2008 & 14001:2004 Company &

established. Its latest station at Budge Budge (1997) with a capacity of 750

MW which is one of the largest ever private industrial investments in West

Bengal.

ABOUT CESE LIMITED

AVISHEK GHOSH 4

TITAGARH GENERATING STATION (TGS)

TGS is one of the oldest generating station & is the first pulverized fuel thermal station of

CESC situated on B.T. road, Titagarh, West Bengal. It has total installed capacity of 240

MW (4x60). Its generating voltage is 10.5 KV. The plant started commercial generation

since 1983, when the first unit started operating. Subsequently the other three units

started in the years 1983, 1984 & 1985.

Plant Load Factor (P.L.F) of this plant is generally high (87.39) in 2006-07 & P.A.F. is 94.79

(2006-07). TGS is committed to ensuring required power supply to the CESC’s

distribution network in line with the varying level of electricity demand. In TGS the

generating voltage 10.5 KV is stepped up by generating transformer to 33KV. This 33 KV

supply is again stepped up to 132 KV in the receiving station & is sent to distribution

station & stepped down to 11KV.

Thereafter it is again stepped down to 6.6 KV, 415 V for distributing to consumers.

Operation & maintenance of the plant is part of the business activity of TGS. CESC

Central Turbine Maintenance department (CTM) is responsible for Turbo-Alternator sets

while, testing & calibration of protection metering equipments are done by company’s

test department. In 2006-2007 TGS captured the 5th position all over India due to its

great performance.

Currently TGS is used as a supporting unit to produce excess power during the time of

large demand (summer), and only one of the four boiler is functional and a power of

60MW is being produced. It does not have a re-heat cycle so is overall efficiency is also

low compared to ultra-modern power plants.

AVISHEK GHOSH 5

Location of a power plant is dependent on various factors as discussed below -

LOCATION OF A POWER PLANT

Site Requirements: The size of the required depends on several factors like

the fuel used and its mode of delivery to the site, the area to be provided for the fuel storage, cooling towers, switch yards, space needs for store yards, workshops etc. The following factors are to be taken into consideration: a) Station building b) Coal store and siding c) Cooling towers d) Switch yard compound e) Surrounding area and approaches

Water for Power Station: The water requirement for thermal stations

come under two main groups, the first requirement for steam generation and second for cooling purpose. As far as the water for steam generation is concerned, the problem is not of quantity but is quality. The requirement of steam cycle is of the order of 3 to 4 ton/hr./MW. The amount of water required for compensating is quite sufficient. In once through system of circulating water the amount required will be approx. 20,000 m^3 / hr. / 100MW

Coal for Power Station: The main areas where coal mines are located are

eastern region i.e. Bihar, Bengal, Central region, Singraull coal fields, Tamil-nadu , Neyvell and small sources of coal are located in rest of the country as well. The economic and efficient utilization of high ash content coals for thermal power generation calls for special consideration. Firstly it is economical to haul this coal over long distance because any transportation means paying freight and handling charges on the useless ash; thereby adversely affecting the cost of useful heat that can be recovered from the coals.

Transportation: In case of thermal power stations, the problem of transport

is to be considered mainly from the view point of fuel viz. coal economics and for initial erection of the plant. Modes of transport are also to be considered but may not be overriding factor in decision regarding feasibility. At this stage the possibility of rail and road connections capable of taking heavy and over-dimensioned loads of the machines are to be considered.

AVISHEK GHOSH 6

Disposal of Effluents: The major effluents in case of thermal stations are in

ash and the flue gases. The disposal of chemically treated water generated in the water treatment plant is also an effluent which requires attention for disposal. The disposal of the gases and ash concerns mainly the atmosphere and environment and that of water is concerned with the effect on marine life of the rivers and canals. The methods of disposal of ash has been by converting it into slurry and pumping the same by means of ash disposal pumps of hydro aces to waste lands.

Transmission: A route must be available for the transmission lines from the

site to the nearest grid system or major load point on the area board system which can accept the station output. Increasing opposition from the public, amenity societies and planners to Overhead lines makes the line increasingly difficult to obtain and sometimes the only solution is to lay underground sections of the line.

Climatic Conditions: Climatic conditions of a place play a significant part in

the economics of capital investment. The tropical climate existing in most parts of our country, calls for special attention to the ventilation and cooling arrangements.

Proximity to Airfields: Before the site is selected, its proximity to air fields

must be studied. The chimney height now goes up.

Fishers and marine life: The intake of large volume of water from the river

and consequent throw off at a higher temperature after being treated with chlorine will affect fishes. The effluent discharge from water treatment plant has to be treated suitably before discharging it to the river.

Personal requirement: The personal requirement will consist of persons

both in the skilled and unskilled labor categories. We may not find out any difficulty in getting the skilled personnel required for different specialized jobs.

Amenities: Some of the considerations kept in mind while locating a power

plant are also the availability of medical, education and related facilities. From the point of view of the power plant, availability of ancillary industrial units will also form one of the factors.

AVISHEK GHOSH 7

Any coal fired power generating station operates on the following four basic

cycles:

Pump

Boiler

Turbine

Condensor

CYCLES OF A THERMAL POWER PLANT

Coal-Ash Cycle Air-Flue Gas Cycle Water-Steam Cycle Cooling Water Cycle

Coal-Ash Cycle: Raw coal is fed into the Fuel Handling Plant (FHP) or Coal

Handling Plant (CHP) after which it is sent to the coal bunker through the crusher. Then through the coal feeder the coal is fed into the pulverizer where the coal (20mm dia.) is pulverized. After that the pulverized coal is fed through the 24 (4 X 6) coal burners by primary air fans into the boiler furnace. After proper combustion (determined by the 3-Ts: (temperature, time and turbulence) ash is formed. This ash is of two types. The heavier variety is called the Bottom Ash while the lighter variety passes out as flue gas into the Economizer. The bottom ash is also obtained from the economizer. The bottom ash is obtained as clinkers which are crushed into powder form by the scrapper-clinker grinder conveyer. Then the bottom ash thus obtained is converted to slurry by water through the ash water pumps. The flue gas from the furnace is fed to the economizer and the Air Pre-Heaters (APH). From the electrostatic precipitator (ESP) the flue gas is vented out into the atmosphere by the ID fans through the chimney. There is a government guideline as to allow only 150mg/Nm3 suspended particles and TGS employs opacity meter to allow only 35mg/Nm3. The ESP tries to collect all the suspended ash particles by high voltage discharge. The ash thus obtained is the second variety of ash and is called fly ash. This fly ash, as the bottom ash is converted into slurries. The slurry of both bottom ash and fly ash together is collected in the ash slurry sump. The slurries from the sump is sent to the ash pond employing three ash slurry pumps.

AVISHEK GHOSH 8

with it. The quantity of these matters

is small when oil is fired but it

becomes quite considerable when

coal is fired, particularly when high

ash content coal is fired. The ESP helps

in minimizing the dust concentration

of flue gas thus reducing the erosion

of ID FAN impellers, ducting and the

atmospheric pollution.

Air-Flue Gas Cycle: AIR CIRCUIT: The air requirement of the boiler is met by two forced draft fans (FD FANS). The forced draft fans supply the necessary primary and secondary air. About 80% of the total air (Secondary air) goes directly to the furnace wind box and 20% of the air goes to the coal-mill via primary air fans (Primary air). The air before it goes into the furnace or to the mill it is pre heated in the air pre heaters. The air pre heater installed is a tubular type heat exchanger in which the heat exchange takes place between flue gas and air. The flue gas flows through the tubes and air flows over the tubes. The air heater serves to recovers the useful heat in the outgoing flue gas (after recovery in the economizer) and thus improves the efficiency of the boiler. At the air heater cold end the outgoing flue gas contains constituents like sulphur dioxide. If the operating temperature goes below the dew-point of the vapour then the vapour get condensed and react with sulphur dioxide and sulphuric acid is formed which is corrosive in nature. The possibility of cold and corrosion is more during lighting up of the boiler and at low load. To avoid this corrosion problem the flue gas bearing the air is to be maintained at a higher temperature. This is accomplished by bypassing the Air Pre-heater during lighting up and low load condition when flue gas temperature is low. The primary air is supplied to the five mills by the five primary air fans. The primary air issued in the mill to dry the pulverized coal and to carry it into the furnace. To ensure drying of coal a portion primary air is taken after passing through the air pre-heater. A cold air line is also connected to the hot primary airline before it enters into the mills. Temperature of the coal air mixture at the mill outlet is controlled by admitting the cold and hot primary air proportionately. FLUE GAS CIRCUIT: The flue gases move upward in the furnace and through the rear gas pass in a downward direction to the air pre-heaters. The flue gas leaving the air pre-heater pass through the electrostatic precipitators and then the induced draft fan (ID FAN) sucks and forces the flue gas through the stack. The flue gas which leaves the boiler furnace carries particles like ash, un-burnt carbon, etc.

AVISHEK GHOSH 9

Water-Steam Cycle: Feed water is supplied to the boiler drum from economizer

outlet header through economizer links and these two links at the point of entering the drum have been divided into 4 branch pipes. Altogether there are 8 down-comers from boiler drum, out of which two down-comer pipes termed as ‘short loop’ (water platen) divided into 4 branches before entering the boiler and ultimately water flows to the drum through these 4 water platen outlet headers. The front & the rear wall inlet headers feed the front and rear furnace wall tubes. The furnace side walls are fed by two side wall inlet headers. The water in the furnace sidewall, water wall platen and the extended side wall absorb heat from the furnace. The resultant mixture of water and steam is collected in the outlet headers and discharged into the steam drum through a series of riser tubes. Steam generated in the front and the rear walls is supplied directly into the drum. In the drum separation of water and steam takes place. The boiler water mixes with the incoming water.

The steam is superheated to the designed temperature and from the super-heater outlet header the steam is led to the turbine via the main steam-line.

Cooling Water Cycle: There are NINE cooling tower fans each of voltage rating:

415 V. They are of ID fan type. All of them are controlled by MCC blocks.

Coo

ling

Tow

er

Condenser

Turbine

Steam

Steam

Condense Water

Discharge

Make-up

Water

AVISHEK GHOSH 10

RANKING CYCLE

The Thermodynamic Cycle generally in operation in any Steam Power Plant is Ranking Cycle

In modern Power plants Modified version of Ranking Cycle is used with Re-Heating.

Chemical Energy stored in Fossil Fuel

Boiler

Heat Energy in Super-Heated

Steam

Turbine

Mechanical Energy in the Shaft of

Turbine

Alternator

Electrical Energy in Generator

ENERGY TRANSFORMATION IN STEM POWER

PLANT

THERMODYNAMIC CYCLE IN STEM POWER

PLANT

AVISHEK GHOSH 11

The Processes involved are -

1-2 Isentropic compression in a pump 2-3 Constant pressure heat addition in a boiler

3-4 Isentropic expansion in a turbine 4-1 Constant pressure heat rejection in a condense

The Rankine cycle is a model that is used to predict the performance of steam engines. The

Rankine cycle is an idealized thermodynamic cycle of a heat engine that converts heat into

mechanical work. The heat is supplied externally to a closed loop, which usually uses water

as the working fluid. The Rankine cycle, in the form of steam engines, generates about 90%

of all electric power used throughout the world.

In an ideal Rankine cycle the pump and turbine would be isentropic, i.e., the pump and

turbine would generate no entropy and hence maximize the network output. Processes 1-2

and 3-4 would be represented by vertical lines on the T-S diagram and more closely

resemble that of the Carnot cycle. The Rankine cycle shown here prevents the vapour

ending up in the superheat region after the expansion in the turbine, which reduces the

energy removed by the condensers.

Process 1-2: The working fluid is pumped from low to high pressure. As the fluid is a

liquid at this stage, the pump requires little input energy. Process 2-3: The high pressure liquid enters a boiler where it is heated at constant

pressure by an external heat source to become a dry saturated vapour. The input energy required can be easily calculated using mollier diagram or h-s chart or enthalpy-entropy chart also known as steam tables.

Process 3-4: The dry saturated vapour expands through a turbine, generating power.

This decreases the temperature and pressure of the vapour, and some condensation may occur. The output in this process can be easily calculated using the Enthalpy-entropy chart or the steam tables.

Process 4-1: The wet vapour then enters a condenser where it is condensed at a

constant pressure to become a saturated liquid.

Efficiency of Ranking Cycle –

𝜂 𝑡ℎ = Wnet /Qin = 1- (Qout/Qin)

Wnet = Qin – Qout = Wturb, out – Wpump,in

AVISHEK GHOSH 12

In TGS, REGENERATIVE RANKINE CYCLE is used.

Closed Feed Water Heater Regenerative Ranking Cycle

The regenerative Rankine cycle is so named because after emerging from the condenser (possibly as a sub-cooled liquid) the working fluid is heated by steam tapped from the hot portion of the cycle. On the diagram shown, the fluid at 2 is mixed with the fluid at 4 (both at the same pressure) to end up with the saturated liquid at 7. This is called "direct contact heating". The Regenerative Rankine cycle (with minor variants) is commonly used in real power stations. Another variation is where bleed steam from between turbine stages is sent to feed water heaters to preheat the water on its way from the condenser to the boiler. These heaters do not mix the input steam and condensate, function as an ordinary tubular heat exchanger, and are named "closed feed water heaters". The regenerative features here effectively raise the nominal cycle heat input temperature, by reducing the addition of heat from the boiler/fuel source at the relatively low feed water temperatures that would exist without regenerative feed water heating. This improves the efficiency of the cycle, as more of the heat flow into the cycle occurs at higher temperature. This process ensures cycle economy.

AVISHEK GHOSH 13

The river water contains suspended matter with colloidal particles and some of organic and

inorganic impurities which make it necessary for chemical and mechanical treatment in WT

plant before being used as clarified and filtered water. The impurities in water are of two

kinds, volatile and non-volatile. Volatile impurities can be expelled from water to a very great

extent by it in fine streams or droplets into the atmosphere. By this means foul gases

dissolved in it are removed. By the Cascade Type, 5 Stage Aerator the iron dissolved in water

also is oxidised and thus precipitates, enabling easy

removal by filtration. The pH value of the water is

often increased due to aeration owing to the removal

of CO2 from it. Lime dosing is done to promote the

coagulation efficiency. It also helps to maintain the pH

value around 7.4 during coagulation.

The non-volatile impurities like clay, vegetable

matter, colouring matter and bacteria being minute

escape through filters. Hence alum is added to

sedimentation and hence, filtration. In the clari-

flocculator mechanical agitation is created and the

mixture is allowed to fall into a trough below for

integrate mixing with the chemicals used, creating violent turbulence. The flocculated water

is admitted into the clarifier tank from the bottom of the flocculator tank in a continuous

rotary upward movement that enhances the rate of deposition of sludge on the floor of the

tank. This sludge is removed by continuous sweeping through a desludging valve. The

clarified water is then collected in the gravity filter beds where they are filtered through a

layer of sand and gravel by the effect of gravity. Now to clean the pores in the filter bed,

DE-MINERALISED WATER PLANT

AVISHEK GHOSH 14

backwashing is done. This process of backwashing involves flushing by compressed air and

water from beneath the filter bed and simultaneous drainage of the turbid water. The

filtered water thus is collected in the filtered water sump from where through colony filter

pumps this water is supplied to the colony. Through plant filter pumps the clarified water is

supplied to the DM plant & the Bearing Cooling Water (BCW) sump or the non-dm plant.

Water is required for industrial process. From the Ganges the water is taken.The water is

first processed to deminarilize in DM plant. However natural water contains dissolved salts,

alkaline salts such as bicarbonates & carbonates of Ca, Na & Mg. there are also other

dissolved impurities such as sulphates, chlorides & nitrates of Ca, Mg & Na. Silica, dissolved

CO2 and metals like Fe, Mn & organic matters are also present. Ion exchange resins are

porous materials that contain inert base attached to which are free ions & can be free to

move about within the resin structure.

At first water is taken from Ganges is taken to main water bus and is sent to water chamber where alum is

mixed. By clarifoculator system and flushing of air the alum gets mixed properly in water and all the mud,

algae etc. settles down. Upper portion of the water which is collected in reservoir which is divided into

two sections. One portion goes for treatment & other is for cooling of machines, coal yard & other services.

There are three types of pump.

1. Clarified water pump 2. Drinking water pump 3. Service water pump

PROCESSES: The clarified water is fed to pressure sand filter (PSF). There are three PSF (A, B, C) & used

to remove sand, mud etc. From PSF the water is fed to the activated carbon filter (ACF). In the ACF it

absorbs any chlorine. There are 3 no’s of ACF (A, B, C) & used to remove the small particles & bacteria.

From AC the water is moved to Strong Acid Cation (SAC) which are three in no. (A, B, C). In SAC the cation

exchange resin causes removal of the cation & in their place hydrogen ions are released in the solutions.

AVISHEK GHOSH 15

REGENERATION: While supply of exchangeable ions within the resin is exhausted, the quality of

treated water from the resin deteriorates & the resin requires regeneration.

SAC: RNa + HCl = RH + NaCl ; R2Mg + H2SO4 = 2RH + MgSO4

SBA: RCl + NaOH = ROH + NaCl

WBA: RHCl + NaOH = R + H2O

SPECIFICATION: In lower tower there are 9 IM PUMP used.

There are used three types of pumps:

1. Service water pump 2. Drinking water pump 3. Clarified water pump.

There is Oil skinning station where removes oil from the water. 2 tanks are used. 1 tank is full& the other

tank is empty. A rotating device is attached on top & it rotates slowly along the tanks boundary.

Effluent re-circular system

De-Gassed Water Pumps MB Air Blasts

Pump3 1kg/cm2

Pump4 1kg/cm2

Pump1 5kg/cm2

PRESSURE SANK FILTER (PSF)

ACTIVATED CARBON

FILTER (ACF)

STRONG ACID

CATAION (SAC)

DE-GASSED WATER TANK

WEAK BASE

ANION (WBA)

STRONG BASE

ANAION (SBA)

MIXED BED

DM WATER TANK

CONDENSATE

STORAGE TANK (CST)

BOILER

SBA BASIN 3

WBA BASIN 3

PRESSURE 2kg/cm2

VOLTAGE 415 V

SPEED 2920 rpm

CURRENT 310 Amp

The no of PSF (pressure sand filter) vessel 2

The no of ACF (Activated charcoal filter) vessel 2{[A] ---2kg/cm2 ; [B]---2.4kg/cm2}

The no of SAC (SULPHURIC acidic cation) vessel 3{[A] ---off ; [B]--0.5kg/cm2 ; [C] ---2kg/cm2}

NOT RUNNING 2

MIXED BED 3

PRESSURE 6kg/cm2

AVISHEK GHOSH 16

In a coal based thermal power plant, the initial process in the power generation is “Coal Handling”. So in this article i will discuss the overall processes carried out at a Coal Handling plant in a coal based thermal power generating station. The huge amount of coal is usually supplied through railways. A railway siding line is taken into the power station and the coal is delivered in the storage yard. The coal is unloaded from the point of delivery by means of wagon tippler. It is rack and pinion type. The coal is taken from the unloading site to dead storage by belt conveyors. The belt deliver the coal to 0m level to the pent house and further moves to transfer point 8.

The transfer points are used to transfer coal to the next belt. The belt elevates the coal to breaker house. It consists of a rotary machine, which rotates the coal and separates the light dust from it through the action of gravity and transfer this dust to reject bin house through belt. The belt further elevates the coal to the transfer point 7 and it reaches the crusher through belt. In the crusher a high-speed 3-phase induction motor is used to crush the coal to a size of 50mm so as to be suitable for milling system. Coal rises from crusher house and reaches the dead storage by passing through transfer point 8.

Schematic of CHP of TGS

COAL HANDLNG PLANT

CHP (Coal Handling Plant)

Conveyer at CHP

AVISHEK GHOSH 17

Raw Coal (Grade 4-6 , Bituminous)

Wagon Trippler Grid (300mm-12'')

Crusser (20mm-3/4")

Coal Mill (75 Micron)

Furnace of Boiler

Pull Chord Switch: A series of such switches are arranged in series at a 1m

distance on the side of conveyor belt. The power supply to rotor of the conveyor belt is established only if all switches in series are connected.

Vibrating Feeder: The coal stored in a huge hub is collected on the belt through

vibrations created by the vibrating feeder.

Flap Gates: These are used to channelize the route of coal through another belt

in case the former is broken or unhealthy. The flap gates open let the coal pass and if closed stop its movement

Magnetic separator: These are used to separate the ferrous impurities from

the coal.

Metal Detector: These are detect the presence of any ferrous and non-ferrous

metal in the coal and send a signal to a relay which closes to seize the movement of belt until the metal is removed. It basically consists of a transmitter and a receiver. The transmitter consists of a high frequency oscillator, which produces an oscillations of 1500 Hz at 15V. The receiver receives this frequency signal. If there is any presence of metal in the coal. Then this frequency is disturbed and a tripping signal is send to relay to stop the conveyor belt.

Belt Weightier: It is used to keep an account of the tension on the belt carrying

coal and is moves accordingly to release tension on the belt.

Reclaim Hopper: Reclamation is a process of taking coal from the dead storage

for preparation or further feeding to reclaim hoppers. This is accomplished by belt conveyors.

AVISHEK GHOSH 18

F.D. FAN P.A. FAN

Wagon Tippler: Coal from the coal wagons

is unloaded in the coal handling plant. This unloading is done by the “Tipplers”. This coal is transported up to the raw coal bunkers with the help of conveyor belts.

Crush House: After hand picking foreign

material, coal is transported to the Crush house by conveyor belts where it is crushed to small pieces of about 20 mm diameter. The crushed coal is then transported to the store yard. Coal is transported to bowl mills by coal feeders.

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Blow Mill: The coal is pulverized in the

bowl mill, where it is grounded to a powder form. The mill consists of a round metallic table on which coal particles fall. This table is rotated with the help of a motor. There are three large steel rollers, which are spaced 120” apart. When there is no coal, these rollers do not rotate but when the coal is fed to the table it packs up between rollers and the table and these forces the rollers to rotate. Coal is crushed by the crushing actions between the rollers and rotating tables.

Blo

w M

ill

Furnace: This crushed coal is taken away

to the furnace through coal pipes with the help of hot and cold air mixture from P.A Fan. P.A Fan takes atmospheric air, a part of which is sent to Air pre-heaters for heating while a part goes directly to the mill for temperature control. Atmospheric air from F.D Fan is heated in the air heaters and sent to the furnace as combustion air.

AVISHEK GHOSH 19

P.A. Fan F.D. Fan I.D. Fan

No. of Fans per Boiler

Motor Type Rating (KW/HP)

Rated Voltage

P.F. at Full Load

Rated Speed

5 3 Phase AC 50Hz IM

235/315 6.6KV 0.87 1490 RPM

No. of Fans per Boiler

Rating (KW/HP)

Rated Voltage

P.F. at Full Load

Rated Speed

2 270/362 6.6 KV 0.85 985 RPM

No. of Fans per Boiler

Rating (KW/HP)

Rated Voltage

P.F. at Full Load

Rated Speed

2 450/603 6.6 KV 0.85 740 RPM

Coal is pulverized in order to increase its surface its surface exposure thus promoting

rapid combustion without using large quantities of excess air. In modern power plants,

lump coal, crushed to uniform size is continuously supplied to the pulverized

hopper from where it is fed into the pulverized through a feeder arrangement.

Combustion rate is controlled by varying the feeder speed thereby controlling the rate of

coal being fed to the pulveriser. It is swept out from the mill and floated to the burner

located in the furnace wall by admitting enough of the combustion air at the pulveriser

to accomplish air bone transportation. This air is called primary air as it is varied from as

little as 10% to almost the entire combustion air requirements, depending upon load.

P.A. Fan

F.D. Fan

I.D. Fan

AVISHEK GHOSH 20

Model of pulverizing mill

Pulverizing Mill In operation

Ring Granulator

AVISHEK GHOSH 21

RH1 ECL

RH2 ICML,ECL

RH3 ICML

The no of convert belt 18

It’s area Wagon tippler to bunker

Crusher speed 750rpm

Shaft per crasher 4

The no of hammers inside the shaft 18

The no of Gates 19

The no of bunker per unit 5

The no of wagon per bunker 5

The height of bunker 60

Timing of to fill up a bunker 30 to 45 min

Bunker division 1 ECL coal Bunker 4 ICML coal Bunker

Ability of supply of coal in a bunker 14-15 hours

Time require for transport of coal from

Wagon tippler to bunker

5-6 min

AVISHEK GHOSH 22

Boiler used in the power plant is suspended type. This prevents it from getting deformed, when a subjected to very high temperatures. The boiler is divided into two cylindrical parts namely the Primary and the Secondary boiler. Water from the boiler feed pump passes through economizer and reaches the boiler drum. Water from the drum passes through down comers and goes to bottom ring header. Water from the ring header is divided to all the four side of furnace. Due to heat and density difference the water rises up in the water wall tubes. Water is partly converted to steam as it rises up in the furnace. This steam and water mixture is again taken to the boiler drum where the steam is sent to super heaters for superheating.

The super heaters are located inside the furnace and the steam is superheated (540°C) and finally it goes to turbine. Flue gasses from the furnace are extracted by induced draft fan, which maintains balance draft in the furnaces with forced draft fan. These flue gasses emit their heat energy to various super heaters in the pant house and finally pass through air pre-heaters and goes to electrostatic precipitator where the ash particles are extracted. Electrostatic precipitator consists of metal plates, which are electrically charged. Ash particles are attracted on to these plates, so that they do not pass through the chimney to pollute the atmosphere. Regular mechanical hammers blows cause the accumulation of ash to fall to the bottom of the precipitator where the bottom of the precipitator where they are collected in a hopper for disposal. This ash is mixed with water to form slurry and is pumped to ash pond.

BOILER

Types of firing:

Perfect mixing of air & fuel

For complete combustion the optimum fuel &air ratio is maintained.

Continuous and reliable ignition of fuel.

Adequate control over point of formation& accumulation of ash when coal is fuel.

AVISHEK GHOSH 23

STEAM DRUM:

The steam drum is made up of high cast steel so that its thermal stress is very high. There is a

safety valve in the drum, which may be explored if the temperature and the pressure of the

steam are beyond to a set value.

The boiler drum has the following purpose:

It stores and supplies water to the furnace wall headers and the generating tubes.

It as the collecting space for the steam produced.

The separation of water and steam tube place here.

Any necessary blow down for reduction of boiler water concentration is done from the drum.

Length Weight O.D. Design Press Shell Thickness

Design Temp

Head Thickness

12.93 Mts 56 Tons 1724 mm 102.7 Kg/cm2 105 mm 312 C 90 mm

Steam pressure - 91.4kg/cm2

Steam temperature - 515oC

Furnace volume - 1558m3

Drum Length 14.97m

Pressure 102.7kg/cm2

Temperature 312oC

Type Ball & race

Pulveriser Capacity 15T/hr * 5

Speed 49rpm

Required power 100KW

Feeder Type Drag link

Control device Thyristor

AVISHEK GHOSH 24

RISER AND DOWN COMERS:

Boiler is a closed vessel in which water is converted into the steam by the application of the

thermal energy. Several tubes coming out from the boiler drum and make the water wall

around the furnace.

Outside the water wall there is a thermal insulation such that the heat is not lost in the

surroundings. Some of the tubes of the water wall known as the ‘down comer’, which

carries the cold water to the furnace and some of other known as the ‘riser comer’, which

take the steam in the upward direction. At the different load riser and the down comers

may change their property. There is a natural circulation of water in the riser and the

down comers due to different densities of the water and the steam water mixture. As the

heat is supplied, the steam is generated in the risers due to this density of the steam

water mixture is greater in the riser then in the down comer and the continuous flow of

water takes place. Down comer connected to the ‘mud drum’, which accumulates the mud

and the water. When the plant takes shut down the mud drum is allowed to clean

manually.

BURNERS:

15 Y jet sprayers are provided for lighting up and PF flame stabilization of 15 numbers burners.

There is a provision for firing both the heavy fuel oil and light diesel oil. The oil firing is done

initially during the starting up and when the coal used in TGS is of poor quality, then the plant is

allowed to run on oil support. In TGS light diesel oil (LDO) is used for the initiation for ignition of

the pulverized coal. The LDO charged into the furnace

through the oil burners. It increases the burning

capacity of the pulverized coal.

Heavy fuel oil passes through the pumping and

heating unit to reduce the viscosity as required for

firing. For LDO no heating is required. Separate oil

pumps are provided for LDO.

AVISHEK GHOSH 25

For both the type of oil, the oil pump discharge a pressure is 14 kg \ cm². Constant steam

pressure 10.5 kg \ cm² is maintained for oil atomization and oil heating. P 34 gas igniters are

provided for ignition.

SUPER HEATER:

The super heater rises the temperature of the steam above its saturation point and there are

two reasons for doing this:

FIRST- There is a thermodynamic gain in the efficiency.

SECOND- The super-heated steam has fewer tendencies to condense in the last stages of the

turbine.

ECONOMISER:

The heat of the flue gas is utilized to heat the

boiler feed water. During the start up when no

feed water goes inside the boiler water could

stagnate and over heat in the economizer. To

avoid this economizer re-circulation is provided

from the boiler drum to the economizer inlet.

SAFETY VALVE:

A safety is a valve mechanism for the automatic release of a gas from a boiler, pressure

vessel or other system when the pressure or temperature exceeds pre-set limits. It is a part

of a bigger set named Pressure Safety Valve (PSV) or Pressure Relief Valve (PRV). The other

parts of the set are named relief valves.

AVISHEK GHOSH 26

AIR HEATER or AIR PREHEATER:

The air heater is placed after the economizer in the path of the boiler flue gases and preheats

the air for combustion and further economy. There are 3 types of air pre heaters: Tubular

type, rotary type and plate type. Tubular type of air

heater is used in TGS. Hot air makes the combustion

process more efficient making it more stable and

reducing the energy loss due to incomplete

combustion and unburnt carbon. The air is sucked by

FD fan heated by the flue gas leaving the

economizer. The preheated air is sent to coal mill as

primary air where coal is pulverized. The air sucked is

heated to a temp. Of 240-280oC. The primary air

transports the pulverized coal through three burners

at TGS after drying in the mill.

SPRAY ATTEMPERATOR:

In order to deliver a constant steam temperature over a range of load, a steam generating

unit (Boiler) may incorporate a spray attemperator. It reduces the steam temperature by

spraying controlled amount of water into the super-heated steam the steam is cooled by

evaporating and super heating the spray water. The spray nozzle is situated at the entrance

to a restricted venture sections and introduces water into the steam. A thermal sleeve

linear protects the steam-line from sudden temperature shock due to impingement of the

spray droplets on the pipe walls. The spray attemperator is located in between the primary

super heater outlet and the secondary super heater inlet.

AVISHEK GHOSH 27

Turbine is a rotating device which converts heat energy of steam into mechanical energy. It is

a two cylinder machine of impulse reaction type comprising a single flow high pressure turbine

and a double flow low pressure turbine. The H.P. turbine shaft and the generator are all rigidly

coupled together, the assembly being located axially by a thrust bearing at the inlet end of H.P.

turbine.

The turbine receives high pressure steam from

the boiler via two steam chests. The H.P.

turbine cylinder has its steam inlets at the end

adjacent to the no. one bearing block, the

steam flow towards the generator. Exhaust

steam passes through twin over-head pipes to

the L.P. turbine inlet belt where the steam

flows in both directions through the L.P.

turbine where it exhausts into under slung condenser. Steam is extracted from both the

H.P. & L.P. turbine at various expansion stages & fed into four feed water heaters.

Main parts of a Turbine –

TURBINE

Over speed trip test plunger

Over speed governor

Worm

Speed indicator wheel

Breaking keep-no.1

Thrust collar

Bearing and thrust-no.1

Oil buffle-no.1

Labyrinth gland-no.1

Dummy piston

Nozzle chest

Impulse wheel

H.P. Turbine shaft

Reaction blading

Labyrinth gland-np.2

H.P. Exhaust

Oil buffle-no.2

Casing and block head

AVISHEK GHOSH 28

The steam coming out of the turbine no longer remains superheated, so this warm steam is

allowed to condense for recycling inside the condenser. The condensate is extracted from the

condenser extraction pump. This extraction should be kept free from the air & air rejecter.

Pipes serve this purpose. Then water from CEP enters

the drain cooler and warm water is cooled there and

increases boiler efficiency. In the drain cooler it gets the

temp. 0f 47oC & enters the L.P. heater 1, where water

temp. increases to 70oC and then it enters the L.P.

heater 2 n the temperature becomes 102oC

It has several functions.

To condensate the steam exhausted from the L.P. turbine.

To accept & condense the steam from drains &vents of heaters through flush box.

To maintain the vacuum.

To accommodate the air and non-condensable gases in the coolest zone of the condenser.

To receive make up water for the system & de-aerate the same.

To act as reservoir for the extraction pump.

Economical and max continuous rating 60MW

Steam pressure at emergency stop valve 89kg/cm2

Steam temperature at emergency stop valve 510oC

Absolute pressure at exhaust 0.088kg/cm2

Rotational speed 3000rpm

Tripping speed 3375rpm

CONDENSER

AVISHEK GHOSH 29

Alternator generates electricity. In general the electrical and magnetic circuits of the

generator are of conventional design. The generator stator casing contains the core and

windings which are enclosed at the ends with inner and outer and covers. At both sides of

casing, air coolers are mounted on the generator soleplate and connect to a re-circulatory

air ventilation system. The covers over the coolers direct air to and from the generator

casing via the air coolers. Two axial flow fans, one at each end of the rotor circulate the

cooling air through the generator and air coolers.

The generator rotor, when excited, provides the magnetic field for the generator. The shaft

is hollow bored at the exciter end and machined to carry the rotor winding. The rotor is

threaded through the bore of the generator stator and is supported at each end by a white

metal bearing. The alternator and main exciter are of the brushless type and copper links,

connect the rotor winding to a rotating rectifier on the main exciter shaft.

ALTERNATOR

AVISHEK GHOSH 30

MAIN EXCITER PILOT EXCITER

Maximum continuous rating 60 MW output

Maximum continuous rating 70.59 MVA o/p

Rated power factor 0.85 lagging

Rated terminal voltage 10500 volts

Rated phase current 3881 amps

Rated speed 3000 rpm

Frequency 50Hz

Number of phases 3

Number of poles 2

Short circuit ratio 0.6

Anti-condensation heater rating 6off-1KW,415V,3ph,4wires 50Hz

Number of phase 1

Rated peak voltage 130V rms

Power factor peak 0.9 Y -

Connection

Number of poles 8

Maximum continuous rating 207KW

Rated terminal volt at

rectifier DC term

225V

Rated current at rectifier 920A

Frequency 150Hz

Rated speed 3300 rpm

Number of poles 6

AVISHEK GHOSH 31

It is a device that separates fly ash from outgoing flue gas before it discharged to the stack.

There are four steps in precipitation.

Ionization of gases and charging of dust particles.

Migration of particle to the collector.

Deposition of charged particles on collecting surface.

Dislodging of particles from the collecting surface.

By the electrostatic discharge the ash particles are charged due to high voltage (56KV)

between two electrodes. Generally maximum amount of ash particles are collected in the

form of dry ash, stored inside the SILO. Rest amount of ash (minimum) are collected in the

form of bottom ash and stored under the water inside HYDROBIN

Control Circuit:

To control the operation & protection of the control circuit is provided which comprises the

following modules:

Ramp setting

Power supply

Power amplifier

Synchronizing & firing module

Flashing over sensing

Under alarm & voltage annunciation

ELECTRO-STATIC PRECIPERATOR

AVISHEK GHOSH 32

Operation of E.S.P:

Steady state load operation: During steady state resistance load it is a DC power supply

with a constant current, constant voltage characteristics where the limiting parameter can be

set under manual mode of operation. The limiting actions of parameters is achieved by

controlling the triggering angle of the thirstier of AC regulator.

Operation under Flashover Condition: When the spark occurs it is sensed & a common signal

is given to the reference by a set amount which in turn reduces the output voltage proportionally.

Dust of fly ash gets deposited in the plates which has to be regularly removed by doing raping.

Seven raping system is continuously operating through the microprocessor.

AVISHEK GHOSH 33

Bottom Ash Removal System: Here for removal

bottom ash “Zero Discharge System” is used. In this

system overflow transfer tank, overflow transfer

pump, two numbers of hydro bin, one number of

settling tank, one number of surge tank, three HP

pumps, two LP pumps, ejector and three number of

surge recirculation pumps are present.

The bottom ash hopper filled with the water. When

the bottom ash come into the contact of water it

forms clinker then the ash passes through flap gate

and goes to the clinker grinder to reduce the size

of the clinker formed ash. After clinker grinder it goes

to the ejector where power water create the jet

velocity to convey the bottom ash to the hydro bin.

Hydro bin is a conical shaped tank which can separate

the ash and the water. Here two numbers of hydro bin

are used. When one hydro bin is filled with the ash

other come into the service. Each hydro bin can store

four days ash. In the hydro bin a horizontal plate is

present that is baffle plate upon which the mouth of

the slurry pipes are opened. There is a little gap between the plate and the mouth of the pipe.

When the slurry water comes out from the pipe and falls on the plate the turbidity is reduced.

It helps the slurry water to settle down the ash at the bottom. The ash settle down in the

bottom and the water (not pure) is comes out from the vertical cylindrical centralised strainer.

ASH REMOVAL SYSTEM

AVISHEK GHOSH 34

The water from the upper most portion of the hydro bin means overflow water comes out and

goes to the settling tank for more settlement of ash. In the bottom portion there is a flap gate

for ash extraction through this gate the ash is collected in the truck to dispatch. In the surge

tank more ash is separated and this bottom ash is conveyed to the hydro bin through another

SRP. There is no overflow facility of the surge tank. The clear water from surge tank through

three number of HP pumps goes to the ejector as power water to convey the bottom ash.

Similarly, two LP pumps also connected with the surge tank. It convey the water to the

bottom ash hopper for sealing purpose. The overflow water of the bottom ash hopper goes

to the hydro bin through overflow transfer tank and overflow transfer pump. Here no water

comes out from the system. For this reason this system is called ““Zero Discharge System””.

AVISHEK GHOSH 35

Resistance temperature detectors (RTDs): Resistance thermometers, also

called resistance temperature detectors (RTDs), are sensors used to measure temperature

by correlating the resistance of the RTD element with temperature. Most RTD

elements consist of a length of fine coiled wire wrapped around a

ceramic or glass core. The element is usually quite fragile, so it

is often placed inside a sheathed probe to protect it. The

RTD element is made from a pure material, typically platinum, nickel or

copper. The material has a predictable change in resistance as the temperature changes

and it is this predictable change that is used to determine temperature.

Thermistor: A thermistor is a type of resistor whose resistance varies significantly

with temperature, more so than in standard resistors. Thermistors differ from resistance

temperature detectors (RTDs) in that the material used in a

thermis tor is generally a ceramic or polymer, while RTDs use pure

metals. The temperature response is also different; RTDs are

useful over larger temperature ranges, while thermistors typically

achieve a higher precision within a limited temperature range,

typically −90 °C to 130 °C.

Orifice plate: An orifice plate is a device used for

measuring flow rate, for reducing pressure or for

restricting flow (in the latter two cases it is often called

a restriction plate). Either a volumetric or mass flow

rate may be determined, depending on the calculation

associated with the orifice plate.

BASIC INSTRUMENTS AT TGS

AVISHEK GHOSH 36

Thermocouple: A thermocouple is a temperature-

measuring device consisting of two dissimilar

conductors that contact each other at one or more

spots. It produces a voltage when the temperature

of one of the spots differs from the reference

temperature at other parts of the circuit.

Thermocouples are a widely used type

of temperature sensor for measurement and control, and can also convert a temperature

gradient into electricity.

Smart transducer: A smart transducer is an analog or

digital transducer or actuator combined with a processing

unit and a communication interface. As sensors and

actuators become more complex they provide support for

various modes of operation and interfacing .Some

applications require additionally fault-tolerance and distributed computing. Such high-level

functionality can be achieved by adding an embedded microcontroller to the classical

sensor/actuator, which increases the ability to cope with complexity at a fair price. They are

often made using CMOS, VLSI technology.

Pressure measurement: Many techniques have been developed for the measurement

of pressure and vacuum. Instruments used to measure pressure are called pressure

gauges or vacuum gauges.

Bourdon: - The Bourdon pressure gauge uses the principle that

a flattened tube tends to straighten or regain its circular form in

cross-section when pressurized.

Bourdon

AVISHEK GHOSH 37

Titagarh Generating Station currently runs on Distributed Control System (DCS).

A distributed control system (DCS) refers to a control system usually of a manufacturing

system, process or any kind of dynamic system, in which the controller elements are not

central in location (like the brain) but are distributed throughout the system with each

component sub-system controlled by one or more controllers. The entire system of

controllers is connected by networks for communication and monitoring.

A DCS typically uses custom designed processors as controllers and uses both proprietary

interconnections and communications protocol for communication. Input and output

modules form component parts of the DCS. The processor receives information from input

modules and sends information to output modules. The input modules receive information

from input instruments in the process (a.k.a. field) and transmit instructions to the output

instruments in the field. Computer buses or electrical buses connect the processor and

modules through multiplexer or demultiplexers. Buses also connect the distributed

controllers with the central controller and finally to the Human-Machine Interface (HMI) or

control consoles.

A typical DCS consists of functionally and/or geographically distributed digital controllers

capable of executing from 1 to 256 or more regulatory control loops in one control box.

The input/output devices (I/O) can be integral with the controller or located remotely via

a field network. Today’s controllers have extensive computational capabilities and, in

addition to proportional, integral, and derivative (PID) control, can generally perform logic

and sequential control.

DISTRIBUTED CONTROL SYSTEM

AVISHEK GHOSH 38

DCSs may employ one or several workstations and can be configured at the workstation or

by an off-line personal computer. Local communication is handled by a control network

with transmission over twisted pair,

coaxial, or fiber optic cable. A server

and/or applications processor may

be included in the system for extra

computational, data collection, and

reporting capability.

AVISHEK GHOSH 39

CONCLUSION

CESC’s environmental management system focuses on continuous improvement and

upgradation with state-of-the-art principles and equipment, setting high targets and

reviewing its performances. CESC recognizes its responsibility towards protecting the

ecology, health and safety of the employees and consumers.

The vacational training has been organized by the CESC limited and has been undertaken

at the Titagarh Generating Station. The purpose of the vocational training is to get an

industrial exposure in our engineering career.

Students can learn a lot from different books about various subjects such as operations

of a plant, various constituents of a plant, power production, power distribution etc. but

a practical experience helps in better understanding and enhancement of knowledge in

various subjects. I am grateful to CESC limited for organizing this vacational training.

AVISHEK GHOSH 40

This is to certify that Mr. Avishek Ghosh, student of 3rd year Mechanical Engg.

Dept. Jadavpur University, has successfully completed his 2 weeks Vacational Training at

Titagarh Generating Station, CESC Limited, B.T.Road, Khardah, North 24-Parganas, WB,

PIN-700119 from 13th June to 25th June 2016.

He was punctual and his conduct during the training was good. I wish him

success in his future carrier.

Mr.Hirak Das Date

(Asst. Manager HRD)

DECLARATION

Name of Trainee – Avishek Ghosh

Class – 3rd year B.E. Mechanical

Name of College – Jadavpur University

Duration of Training – 13/6/16 – 25/6/16

Place of Training – Titagarh Generating Station