.

REPORT ON VOCATIONAL TRAINING

4TH JULY,2016 TO 16TH JULY,2016

Prepared by:

DEBOKTI GHOSH 3RD YEAR,

ELECTRONICS & COMMUNICATION ENGINEERING,

ACADEMY OF TECHNOLOGY,

HOOGHLY.

UNIVERSITY ROLL NO:16900313038.

Submitted in partial fulfillment of the requirements for the degree of:

Bachelor of Technology.

CALCUTTA ELECTRICAL SUPPLY CORPORATION

(A flagship company of the RP-Sanjiv Goenka Group)

TITAGARH GENERATING STATION

2 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

ACKNOWLEDGEMENT:

This Training cum 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 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 07.07.2014 to 19.07.2014.

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

vacational training.

15 July 2016. DEBOKTI GHOSH

ACADEMY OF TECHNOLOGY

3 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

Table of Contents:

1.About CESC

2.About Titagarh Generating Station

3.Thermal Power Plants

4.Rankine Cycle

5.Cycles in a power plant

6.Coal Handling Plant

7.Water Treatment Plant

8.FAN(PA,FD & ID)

9.Boiler and its auxiliaries

10.Distributed Control System(DCS)

11.Conclusion

12.Bibliography

4 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

ABOUT CESC:

CESC is India’s first fully integrated electrical utility company and CESC has been

on an epic ride ever since 1897 in generating and distributing power in Kolkata and

Howrah.

CESC have private participation in generation, transmission and distribution of

electrical power.

CESC are the sole distributor of electricity within an area of 567sq km in the state

capital and serve 2.9 million consumers which include domestic, industrial and

commercial users.

CESC own & operate three thermal power plants generating 1125 MW of power. These

are: Budge Budge Generating Station (750 MW), Southern Generating Station (135

MW), & Titagarh Generating Station (240 MW)

From these three generating stations, CESC accomplishes 88% of their customer’s

electricity requirement and remaining 12% is achieved by purchase of electricity from

third parties.

More than 50% of coal is sourced from captive mines for generation of electricity in

their generating stations.

The Transmission and Distribution system comprises of 474 km circuit of transmission

lines linking the company’s generating & receiving stations with 105 distribution

stations, 8,211 circuit km of HT lines further linking distribution stations with LT

substations, large industrial consumers and 12,269 circuit km of LT lines connecting the

LT substations to LT consumers.

5 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

ABOUT 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.

It has total installed capacity of 240 MW comprising four units each rated 60

MW.

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.

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 132KV in the receiving station

& is sent to distribution station & stepped down to 11KV. Thereafter it is again

stepped down to 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

equipment are done by company’s test department.

Boiler specifications: ABL make (Front fired PF)

Steam O/L pr. 91.4 kg/sq.cm.

Turbo Alternator: NEI Parsons, U.K.

Impulse Reaction, Condensing, Non-reheat

Generator: Air Cooled

Stator Voltage: 10.5kV

Stator Current: 3881A.

Performance parameters:

Year 2007-08 2008-09 2009-10 2010-11 2011-12 2012-13 2013-14 2014-15

Target

Generation(MU)

1858.1900 1926.7100 1864.0400 1868.0000 1689.0000 1755.0000 1683.0000 1573.0000

Units

Generated(MU)

1942.6251 1933.6849 1888.7906 1866.0116 1716.6021 01549.5400 1776.0090 1684.2202

Aux.Power

Consumption(%)

8.79 8.49 8.32 8.17 8.35 8.23 8.25 8.43

Plant Load

Factor(%)

92.15 91.98 89.84 88.75 81.38 78.46 84.48 80.11

Plant

Availability (%)

95.80 96.29 96.32 96.75 96.15 87.08 96.59 96.25

Coal Fig.(Gen) 0.605 0.630 0.652 0.664 0.636 0.631 0.644 0.660

Oil Fig(Gen) 0.940 0.850 1.63 1.09 1.17 0.78 0.76 0.92

6 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

7 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

THERMAL POWER PLANTS-An Overview:

A thermal power station is a power plant in which the prime

mover is steam driven. Water is heated, turns into steam and spins a steam turbine

which drives an electrical generator. After it passes through the turbine, the steam is

condensed in a condenser; this is known as a Rankine cycle. The greatest variation in

the design of thermal power stations is due to the different fuel sources. Some prefer

to use the term energy center because such facilities convert forms of heat energy into

electrical energy. However, power plant is the most common term in Asia Pacific, while

power station prevails in many Commonwealth countries and especially

in the United Kingdom, almost all coal, nuclear, geothermal, solar thermal electric,

and waste incineration plants, as well as many natural gas power plants are thermal.

Natural gas is frequently combusted in gas turbines as well as boilers. The waste heat

from a gas turbine can be used to raise steam, in a combined cycle plant that improves

overall efficiency. Such power stations are most usually constructed on a very large

scale and designed for continuous operation.

History -reciprocating steam engines have been used for mechanical power sources since

the 18th Century, with notable improvements being made by James Watt. The very first

commercial central electrical generating stations in New York and London, in 1882, also

used reciprocating steam engines. As generator sizes increased, eventually turbines took

over due to higher efficiency and lower cost of construction. By the 1920s any central

station larger than a few thousand kilowatts would use a turbine prime mover. Efficiency -

The electric efficiency of a conventional thermal power station, considered as saleable

energy produced at the plant bus bars compared with the heating value of the fuel consumed,

is typically 33 to 48% efficient, limited as all heat engines are by the laws of

thermodynamics (See: Carnot cycle). The rest of the energy must leave the plant in the

form of heat. This waste heat can be disposed of with cooling water or in cooling towers.

If the waste heat is instead utilized for e.g. district heating, it is

called cogeneration. An important class of thermal power station are associated with

desalination facilities; these are typically found in desert countries with large

supplies of natural gas and in these plants, freshwater production and electricity are

equally important co-products.

Since the efficiency of the plant is fundamentally limited by the ratio of the absolute

temperatures of the steam at turbine input and output, efficiency improvements

require use of higher temperature, and therefore higher pressure, steam. Historically,

other working fluids such as mercury have been experimentally used in a mercury

vapour turbine power plant, since these can attain higher temperatures than water at

lower working pressures. However, the obvious hazards of toxicity, and poor heat

transfer properties, have ruled out. mercury as a working fluid.

8 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

Schematic of Coal Fired Power Plant

What a power plant looks like

9 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

RANKINE CYCLE:

The Rankine cycle is a model that is used to predict the performance of steam turbine systems. 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. It is named after William

John Macquorn Rankine, a Scottish polymath and Glasgow University professor. The Rankine cycle closely

describes the process by which steam-operated heat engines commonly found in thermal power generation

plants generate power. The heat sources used in these power plants are usually nuclear fission or the

combustion of fossil fuels such as coal, natural gas, and oil.

The efficiency of the Rankine cycle is limited by the high heat of vaporization of the working fluid. Also,

unless the pressure and temperature reach super critical levels in the steam boiler, the temperature range

the cycle can operate over is quite small: steam turbine entry temperatures are typically around 565°C and

steam condenser temperatures are around 30°C. This gives a theoretical maximum Carnot efficiency for

the steam turbine alone of about 63% compared with an actual overall thermal efficiency of up to 42% for

a modern coal-fired power station. This low steam turbine entry temperature (compared to a gas turbine)

is why the Rankine (steam) cycle is often used as a bottoming cycle to recover otherwise rejected heat

in combined-cycle gas turbine power stations.

The working fluid in a Rankine cycle follows a closed loop and is reused constantly. The

water vapor with condensed droplets often seen billowing from power stations is created by the cooling

systems (not directly from the closed-loop Rankine power cycle) and represents the means for (low

temperature) waste heat to exit the system, allowing for the addition of (higher temperature) heat that can

then be converted to useful work (power). This 'exhaust' heat is represented by the "Qout" flowing out of

the lower side of the cycle shown in the T/s diagram below. Cooling towers operate as large heat

exchangers by absorbing the latent heat of vaporization of the working fluid and simultaneously

evaporating cooling water to the atmosphere. While many substances could be used as the working fluid

in the Rankine cycle, water is usually the fluid of choice due to its favorable properties, such as its non-

toxic and unreactive chemistry, abundance, and low cost, as well as its thermodynamic properties. By

condensing the working steam vapor to a liquid the pressure at the turbine outlet is lowered and the

energy required by the feed pump consumes only 1% to 3% of the turbine output power and these factors

contribute to a higher efficiency for the cycle. The benefit of this is offset by the low temperatures of

steam admitted to the turbine(s). Gas turbines, for instance, have turbine entry temperatures approaching

1500°C. However, the thermal efficiencies of actual large steam power stations and large modern gas

turbine stations are similar.

Physical layout of the four main devices used in the Rankine cycle

10 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

There are four processes in the Rankine cycle. These states are identified by numbers (in brown) in the

above T-s diagram.

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 graphically, using an enthalpy-entropy chart (aka h-s chart or Mollier diagram), or

numerically, using 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 chart or tables noted above.

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

become a saturated liquid.

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 net work 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 vapor ending up in the superheat region after the expansion in the

turbine, [1] which reduces the energy removed by the condensers.

The actual vapor power cycle differs from the ideal Rankine cycle because of irreversibilities in the

inherent components caused by fluid friction and heat loss to the surroundings; fluid friction causes

pressure drops in the boiler, the condenser, and the piping between the components, and as a result the

steam leaves the boiler at a lower pressure; heat loss reduces the net work output, thus heat addition to the

steam in the boiler is required to maintain the same level of net work output.

T-s diagram of a typical Rankine cycle operating between pressures of 0.06bar and 50bar

11 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

FOUR BASIC CYCLES ON WHICH A POWER

GENERATING PLANT OPERATES

Any COAL FIRED Power Generating Plant operates on the following four basic

cycles:

1. Coal & Ash cycle

2. Air & Flue Gas cycle

3. Water & Steam cycle

4. Cooling Water cycle

Of all the above four mentioned cycles, the fist two i.e. COAL & ASH CYCLE &

AIR & FLUE GAS CYCLE are called OPEN CYCLES.

The next i.e. WATER & STEAM CYCLE is a CLOSED CYCLE.

The fourth and the last mentioned cycle i.e. THE COOLING WATER CYCLE occurs

in the condenser.

COAL ASH CYCLE

Raw coal is fed into the Coal Handling Plant (CHP) after which it is sent to the coal

bunker.Then through the coal feeder the coal is fed into the pulveriser/ crusher where

the coal (50mm dia.) is pulverized. After that the pulverized coal is fed through the

24(6x4) 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 Economiser. From the Economiser

also bottom ash is obtained. 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 economiser and the Air Preheaters (APH).Then from the

Electrostatic Precipitator (ESP) the flue gas is vent out into the atmosphere by ID fans

through the chimney. The ESP collects 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 slurry. The slurry (of bottom ash +

fly ash) is collected in the Ash Slurry Sump. The slurry from the sump by a set of

three ash slurry pumps is sent to the Ash Pond .This ash is used in several applications

like cement industry, manufacture of bricks, etc.

AIR-FLUE GAS CYCLE

AIR CIRCUIT:

12 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

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 which is the secondary air goes directly to the furnace wind box and 20% of

the air goes to the mill via primary air fans. This air is known as the 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

exchanger 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

sulpher dioxide. If the operating temperature goes below the dew point of the vapours

then the vapours get condensed and react with sulpher dioxide and sulphuric acid is

former 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 passing 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 is used 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

air line before it enters into the mills. The 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 preheater 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 leaving the boiler furnace

carries with it particles like ash, unburnt carbon etc. 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 PATH

WATER & STEAM CYCLE

Feed water is supplied to the boiler drum from economiser outlet header through

13 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

economiser links and these two links at the point of entering the drum have been

divided into 4 branch pipes. Altogether there are 8 downcomers from boiler drum, out

of which two downcomer 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 saturated steam is led to the roof radiant inlet header

and from there to the final SH outlet header via LTSH and platen superheater stages.

The steam is superheated to the designed temperature and from the superheater 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 block.

SCHEMATIC DIAGRAMS:

14 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

->Air flue Gas cycle

15 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

16 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

COAL HANDLING PLANT

Coal is a primary fuel. Source of coal varies from thermal power plants of

CESC as per design parameters of individual boiler. Much coal is supplied by ECL

from Rani gaunge and Mugma fields, BCCL from Barakar and Kusunda areas and by

ICML. Coal is transported through railway linkages from respective fields to

generating stations. Requirement of coal at TGS is about TGS is about 3000 tones per

day.There are some properties of coals which are used in TGS.

SWELLING INDEX: Some types of coal during and after release of volatile

matter become soft and pasty and form agglomerates called caking coals.

GRINDABILITY: This property is measured by grindability index.

WEATHERABILITY: It is a measure of how coal can be stockpiled for long

periods of time without crumbling to pieces.

SULPHER CONTENT: Sulpher content in coal is combustible but the product

after combustion i.e.SO2 is a major source of atmospheric pollution.

HEATING VALUE: The coal used in TGS has4000-5000 kcal/kg of heating

value.

PROCESS: First the coal is coming in the station .then with the help of tipplers or

bull dozer, coal from wagon or reclaim hopper is dropped to vibrating feeder through

a 30mm mesh. Any large coal chunk is broken manually and then fed. The first

conveyer belt starts below the ground and with an angle of 18 deg. with the ground. It

comes out and discharges the coal to another conveyer belt. This also with an angle of

18 deg. makes the coal reach the crusher. But before the crusher, impurities like iron

parts, which get carried so far, are separated by a magnetic separator which is oriented

in cross way. The coal is then dropped to the vibrating screen. The coal chunks are

already less then 20mm and go to stock. In the crusher, solid metallic, non ferrous

crushing wheels are used to crush the coals to 20 mm. From the crusher, coal goes to

the bunkers. From these bunkers they are dropped in ball & race mill. Here, huge solid

metallic balls are used to pulverize the coal to 75 micro meters. Then the coal is fed to

furnace. By primary air coal is dried from any moisture and also carries the pulverized

coal to furnace. At the starting of combustion, oil is required. The volatile matter in

coal starts to burn at a temp. near about 400 deg.C. This is temperature is attained by

burning oil which is LDO for industrial purposes. Sometimes oil is also required to

fire the furnace when the quality of coal is not up to mark or when there is high

moisture content in the coal. The main function of the Coal Handling Plant (CHP) is

to feed crushed coal up to the bunker. In the 4th Unit of DTPS there are 6 nos. of

17 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

bunkers as well as coal mills.

The CHP is divided into three zones:

ZONE 1 --- Unload uncrushed coal from wagon tippler up to UNCRUSHED

COAL YARD. Equipments: WAGON TIPPLER, VIBRATOR, CONVEYER BELT.

ZONE 2 --- Taking uncrushed coal from yard for crushing and send it to crushed yard.

Equipments: BELT, SCREEN, CRUSHER, VIBRATOR, DISCHARGE BELT.

ZONE 3 --- Taking crushed coal from yard through reclaim hopper (7, 8, 9 and 10)

and send it to the bunker. Equipments: BELT, VIBRATOR, TIPPER CAR.

COMPONENTS OF DIRECT FIRING SYSTEM ARE AS FOLLOWS:

1.Raw coal feeders.

2. Source to supply hot primary air to the pulverizer for drying the coal.

3. Pulverizer fan, also known as primary air fan arranged as a blower.

4. Pulverizer arranged to operate under pressure.

5. Burners.

TRANSMISSION OF COAL:(Coal yard to furnace)

1. Coal is brought by rail wagons, which the Indian Railways deliver till the coal yard

of TGS. From there, six to eight wagons are separated and are pulled to the Wagon

Tripler where there are unloaded one by one.

2. Wagon Tripler is a device by which the wagon is tripled to unload the coal to the

bunker. The Wagon Tripler consists of a moveable platform, which also acts as a

Computerized Weight Bridge A single wagon is first brought to the platform.

Then by a pulley and weight arrangement Powered by an electric motor, the

platform is tilted towards the bunker by 140 degree while a support from the top

catches the wagon and tilts it which causes the coal to fall down to the bunker. While

the unloading is done, water is sprayed on the coal to avoid spreading of coal dust.

3. From the coal bunker, the different varieties of coal. May be mixed by Dozers and

the coal from there is sent to the crusher.

4. In the crusher, coal is broken into small pieces of sizes not exceeding 20 mm in

diameter. From there by conveyor belt, the coal is taken through the chute and sent to

the top of. the main building

5. The coal is then dumped into an area from where it is fed into by conveyor belts to

the coal trolley which gathers the coal, decides which bunker requires coal, then it

rolls over to the of that bunker and pours the required amount of coal in it.

18 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

6. From the bunker, the coal comes down through the Hopper to the Besta Feeder.

7. The Besta Feeder controls the rate of the amount of coal to be fed tot the

pulverizer.Besta Feeder is a device consisting of a conveyor belt, which transfers the

coal from the hopper to the mouth of the pulverizer. The transfer rate of coal is

controlled from the controlled room by monitoring the speed of the Besta feeder. This

is because as the coal is grounded in the pulverizer, it becomes explosive in nature and

cannot be stored.

8. The coal is sent to the Pulverizer to get crushed into the size of 200 micron in

diameter.The Pulverizer consists of an enclosing cylinder with a channel comprising

of large Steel balls. These balls are rotated under pressure and coal is fed into this

channel where due to movement of these balls, it gets grounded. This procedure is

taken to achieve complete combustion of coal, better control of furnace temperature

and increasing the efficiency of the boiler.

9. From the Pulveriser the coal dust and air mixture is blown to the furnace by

PRIMARY AIR FAN.

COAL PULVERIZATION

Coal is pulverized in order to increase it’s 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 pulverizer. 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 pulverinizer 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.

SOME SPRECIFICATION ABOUT FHP

RH1------------------------ ECL

RH2------------------------- ICML, ECL

RH3------------------------- ICML

CRUSHER HOUSE SPECIFICATION

The no of convert belt----------------------- 18

It’s area---------------------------------------- Wagon tippler to bunker

Crusher speed--------------------------------- 750rpm

19 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

Shaft per crasher------------------------------ 4

The no of hammers inside the shaft-------- 18

The no of Gates------------------------------- 19

BUNKER SPECIFICATION

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 hrs

Time require for transport of coal from

Wagon tippler to bunker--------- 5-6min

A typical coal handling plant

Belt Conveyor:

20 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

Layout of CHP:

A wagon tippler, crusher house, a bowl

mill.(Clockwise)

21 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

WATER TREATMENT PLANT & ITS OPERATION 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 clariflocculator 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,

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.

DEMINIRELIZED WATER 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.Uper portion of the water 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. Clarified water pump, drinking water pump, service water pump.

PROCESS:

The clarified water is fed to pressure sand filter (PSF). There are three

numbers of 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

22 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

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

& bacteria. From ACF 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.

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 + H2O

The other part of the water goes to the non-dmplant from the clarifloculator. Now

from this the water is pumped out by service water pump & drinking water pump. The

water from the service water pump goes to clarified water pump the water of which is

used as heat absorber in case of ID,FD,PAF,generator air compressor etc. & this water

is cooled by raw ganga water tapped from the condenser. The water from service

water pump is also used as heat exchanger for ash water system bearing & rotary

unloader bearing. Now the water from drinking watrer pump goes to bathroom etc.&

the etc. part goes to the drain from the drain the water goes to the ETP1(effluent

treatment plant). The water then passes through ETP2,ETP3,&ETP4 & then it goes to

the circular reservoir after passing through the oil scheamer. While passing through

ETP3 chemical dodging was done. Finally the water from circular reservoir the water

goes to the non-dmplant. When the water flooded in ETP then to extract this extra

flooded water a tapping was done which is connected directly to the ganga & when it

returns to its normal condition then again it get back to the tapping line of condenser.

Again from the sump where water comesby tapping raw ganga water; the water goes

to the ash water pump & by creating a slury the ashes goes to the hydrabin & then to

the EADA(ash pond) from which the water goes to the ETP1 & ETP2. Now water

from demineralised water tank goes to CST(condensate storage tank). From which it

goes to the RFW(reserve feed water tank) by which the level of hot well is

maintained. The warter from CST also goes for deareator cold filling, boiler cold

filling & condensate emergency filling. Thus we can explain the full water treatment

cycle in a power plant.

SPECIFICATIONS:

In lower tower there are 9 IM PUMP used.

It’s voltage-------- 415v, speed-------- 2920rpm, current---------- 31amp………

There are used three type of pumps:

1. Service water pump---------------- 3

2. Drinking water pump--------------- 2

3. Clarified water pump---------------- 4

There is Oil skinning station where removes oil from the water.

Outer premises of D.M plant

23 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

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.

Inner premises of D.M plant

Effluent recircular system

The no of PSF( pressure sand filter) vessel------------------------ 2

The no of ACF (Activated charcoal filter) vessel------------------ 2{[A]---2kg/cm.sq

[B]---2.4kg/cm.sq

The no of SAC (SULPHURIC acidic cation) vessel -------------------3{[A] ---off,[B]--

0.5kg/cm.sq

,[C]---2kg/cm.sq

DEGASSED WATER PUMPS

Pump3 ------------1kg/cm.sq

Pump 4------------1kg/cm.sq

Pump1-----------------5kg/cm.sq.

MB air blasts: Not running-----------2, mixed bed===== 3, pressure-----6kg/cm.sq

Strong base anion (SBA) basin------------- 3

Weak base anion (WBA) basin----------------3

Each of pressure----------------------------------2kg/cm.sq

WBA(Weak Base Anion)

24 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

SAC(Strong Acid Cation)

SBA(Strong Base Anion)

25 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

ACF(Activated Carbon Filter)

MBA(Mixed Bed Anion)

26 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

PSF (Pressurized Sand Filter)

Clarifoculator

27 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

Addition Of Chlorine

28 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

FAN PRIMARY AIR FAN: It is used for pulverized system. Primary air has two

functions. First one is dozing coal & transportation the coal to furnace.

No of fan per boiler 5

Motor type 3 phase AC 50 HZ IM

Rating(KW/HP) 235/315

Rated voltage 6.6 KV

P.F. at full load 0.87

Rated speed 1490 RPM

INDUCED DRAFT FAN: It is used only in balanced draft units to stuck the

gasses out of the furnace & throw them into the stack.

No of fans per boiler 2

Motor rating(KW/HP) 450/603

Rated voltage 6.6 KV

P.F. at full load 0.85

Rated speed 740RPM

FORCED DRAFT FAN: It is used to take air from atmosphere at ambient

temperature to supply essentially all the combustion air. It can either be sized to

overcome all the boiler losses (pressurized system) or just put the air in furnace

(balanced draft units).

FD FAN SPECIFICATION

No of fans per boiler 2

Motor rating (KW/HP) 270/362

Rated voltage 6.6 KV

P.F. at full load 0.85

Rated speed 985 RPM

PRIMARY AIR FAN

29 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

Induced Draft Fan

Forced Draft Fan

30 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

BOILER & THEIR AUXILLIARIES Boiler is a steam raising unit of single radiant furnace type with auxiliary designated

to generate 272 kg/hr. at 91.4 kg/sq. cm pressure. The unit burns pulverized coal and

is equipped with oil burners. This plant is designated to operate at a 475m above sea

level .the ambient temperature is 40

0

C with a humidity of 70%. Furnace consists of

walls, tangent bare water tubes. Rear water tubes from a cavity for the pendant super

heater. A boiler or steam generator is a device used creates steam by applying heat

energy to water. Although the definitions are somewhat flexible, it can be said that

older steam generators were commonly termed boilers and worked at low to medium

pressure

(1–300 psi/0.069–20.684 bar; 6.895–2,068.427 KPa), but at pressures above this it is

more usual to speak of a steam generator. A boiler or steam generator is used

wherever a source of steam is required. Here in T.G.S steam is generated 318ton/hour

at 89.5kg/cm.sq. pressure and 515 °C in boiler.

Steam generator (component of prime mover)

The steam generator or boiler is an integral component of a steam engine when

considered as a prime mover; however it needs be treated separately, as to some

extent a variety of generator types can be combined with a variety of engine

units. A boiler incorporates a firebox or engine units. A boiler incorporates

a firebox orfurnace in order to burn the fuel and generate heat; the heat is

initially transferred to water to make steam; this produces saturated

steam at ebullition temperature saturated steam which can vary according to the

pressure above the boiling water. The higher the furnace temperature, the faster

the steam production. The saturated steam thus produced can then either be

used immediately to produce power via a turbine and alternator, or else may be

further superheated to a higher temperature; this notably reduces suspended

water content making a given volume of steam produce more work and creates a

greater temperature gradient in order to counter tendency to condensation due

to pressure and heat drop resulting from work plus contact with the cooler walls

of the steam passages and cylinders and wire-drawing effect from strangulation

at the regulator. Any remaining heat in the combustion gases can then either be

evacuated or made to pass through an economizers, the role of which is to warm

the feed water before it reaches the boiler.

DESIGN DATA:

Steam pressure --------------------------------91.4 kg/sq.cm.

Steam temperature ----------------------------515 deg.C

Furnace volume--------------------------------- 1558 m3

Drum:

Length-------------------------------------------- 12.97 m

Pressure-------------------------------------------- 102.7 kg/cm

2

Temperature---------------------------------------- 312 deg. C

Pulvarizer:

Type --------------------------------------------------Ball & race

31 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

Capacity----------------------------------------------- 15 T/hr * 5 Nos.

Speed ---------------------------------------------------49 rpm

Required power----------------------------------------- 100 KW

Feeder:

Type------------------------------------------------------- Drag Link

Control Device- ------------------------------------------- Thyristor

Technicial data of T.G.S drum:

Length=12.93Mtr

Weight=56tons

O.D=1724mm

DESIGN press=102.7Kg/cm.sq.

Shell thickness=105mm

Design temp= 312

0

c

Head thickness=90mm

Types of firing: a> perfect mixing of air & fuel

b> for complete combustion the optimum fuel &air ratio is maintained.

c> continuous and reliable ignition of fuel.

d>adequate control over point of formation& accumulation of ash when coal is fuel.

DIAGRAM SHOWING LOCATION OF FANS

32 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

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:

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

2. It as the collecting space for the steam produced.

3. The separation of water and steam tube place here.

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

the drum.

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. 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. It is composed of four sections, a platen section, pendant section, rear

horizontal section and steam cooled wall and roof radiant section. The platen section

is located directly above the furnace in front of the furnace arch. it is composed of 29

assemblies spaced at 457.2mm centers from across the width of the furnace. The

pendant section is located in the back of the screen wall tubes. It is composed of 119

assemblies at 1114mm centers across the furnace width. The horizontal section of the

33 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

superheater is located in the rear vertical gas pass above the economizer. Itis

composed of 134 assemblies spaced at 102 mm centers across furnace width. The

steam cooled wall section from the side front and rear walls and the roof of the

vertical gas pass. The superheater works like coils on an air conditioning unit,

however to a different end. The steam piping (with steam flowing through it) is

directed through the flue gas path in the boiler furnace. This area typically is between

1,300–1,600 degree Celsius (2,372–2,912 °F). Some superheaters are radiant type

(absorb heat by thermal radiation), others are convection type (absorb heat via a fluid

i.e. gas) and some are a combination of the two. So whether by convection or

radiation the extreme heat in the boiler furnace/flue gas path will also heat the

superheater steam piping and the steam within as well. It is important to note that

while the temperature of the steam in the superheater is raised, the pressure of the

steam is not: theturbine or moving pistons offer a "continuously expanding space" and

the pressure remains the same as that of the boiler.

The process of superheating steam is most importantly designed to remove all droplets

entrained in the steam to prevent damage to the turbine blading and/or associated

piping. Superheating the steam expands the volume of steam, which allows a given

quantity (by weight) of steam to generate more power. When the totality of the

droplets are eliminated, the steam is said to be in a superheated state.

Water tube boiler: Another way to rapidly produce steam is to feed the water under

pressure into a tube or tubes surrounded by the combustion gases. The earliest

example of this was developed by Goldsworthy Gurney in the late 1820s for use in

steam road carriages. This boiler was ultra-compact and light in weight and this

arrangement has since become the norm for marine and stationary applications. The

tubes frequently have a large number of bends and sometimes fins to maximize the

surface area. This type of boiler is generally preferred in high pressure applications

since the high pressure water/steam is contained within narrow pipes which can

contain the pressure with a thinner wall. It can however be susceptible to damage by

vibration in surface transport appliances. In a iron sectional boiler, sometimes called a

"pork chop boiler" the water is contained inside cast iron sections. These sections are

mechanically assembled on site to create the finished boiler. High pressure water tube

boilers generate steam rapidly at high temperatures that can be increased by

lengthening the tubes.

34 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

STEAM DRUM

BURNER

RISERS AND DOWNCOMERS

BOILER FAILURE:

35 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

1. overpressurisation of the boiler.

2. insufficient water in the boiler causing overheating and vessel failure.

3. pressure vessel failure of the boiler due to inadequate construction or maintenance.

FUEL PREPARATION SYSTEM: In coal-fired power stations, the raw feed coal from the coal storage area is first

crushed into small pieces and then conveyed to the coal feed hoppers at the boilers.

The coal is next pulverized into a very fine powder. The pulverizers may be ball mills,

rotating drum grinders, or other types of grinders. Some power stations burn fuel

oil rather than coal. The oil must kept warm (above its pour point) in the fuel oil

storage tanks to prevent the oil from congealing and becoming unpumpable. The oil is

usually heated to about 100 °C before being pumped through the furnace fuel oil spray

nozzles.

Boilers in some power stations use processed natural gas as their main fuel. Other

power stations may use processed natural gas as auxiliary fuel in the event that their

main fuel supply (coal or oil) is interrupted. In such cases, separate gas burners are

provided on the boiler furnaces.

Air path: External fans are provided to give sufficient air for combustion. The

forced draft fan takes air from the atmosphere and, first warming it in the air preheater

for better combustion, injects it via the air nozzles on the furnace wall.The induced

draft fan assists the FD fan by drawing out combustible gases from the furnace,

maintaining a slightly negative pressure in the furnace to avoid backfiring through any

opening.

AUXILIARY SYSTEMS: Fly ash collection: Fly ash is captured and removed from the flue gas by electrostatic

precipitators or fabric bag filters (or sometimes both) located at the outlet of the

furnace and before the induced draft fan. The fly ash is periodically removed from the

collection hoppers below the precipitators or bag filters. Generally, the fly ash is

pneumatically transported to storage silos for subsequent transport by trucks or

railroad cars.

Bottom ash collection and disposal:

At the bottom of the furnace, there is a hopper for collection of bottom ash. This

hopper is always filled with water to quench the ash and clinkers falling down from

the furnace. Some arrangement is included to crush the clinkers and for conveying the

crushed clinkers and bottom ash to a storage site.

36 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

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.

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 240-280°C. 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

37 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

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. Except on recommendation of the boiler manufacturer

the spray water flow rate must never exceed the flow specified for maximum designed

boiler rating. Excessive attemperation may cause over heating of the super heater

tubes preceding the attemperator, since the steam generated by evaporation of spray

water and it does not pass through the tubes. Care must also be taken not to introduce

so much that the unevaporated water enters the secondary stage of the super heater.

38 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

SPRAY ATTEMPERATOR

ELECTROSTATIC PRECIPITATOR: 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.

Factors affect the dust removal by an ESP:

a) Particle size:- 0.01μ or less

b) Particle resistivity:- 104 to 1010 ohm-cm

Both low and high resistivity beyond the stipulated value is detrimental to ESP

performances because high resitivity leads to ‘back corona’ causing re-entrainment

of deposited particle back to gas stream from the collecting electrode whereas dust

particles of low resitivity (below 108 ohm-cm) get neutralized so fast as soon as they

reach the +ve plates that particles still remain residual momentum that bounced

them of the collecting plates and caused re-entrainment.

c) Field strength,

d) Corona Characteristic,

e) Flue gas velocity :-1.5 to 2.5 meter /sec.,

f) Area of collecting surface,

g) Rapping frequency.

h) Presence sulfur, carbon particles, moisture, affects the performances of the ESP

i) Flue gas temperature should be within 140 to 1600 C

39 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

SAFETY VALVE: A safety valve 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 preset limits. It is part of a bigger set named Pressure Safety Valves (PSV) or

Pressure Relief Valves (PRV). The other parts of the set are named relief valves,

safety relief valves, pilot operated safety relief valves, low pressure safety valves,

vacuum pressure safety valves. Safety valves were first used on steam boilers during

the industrial revolution. Early boilers without them were prone to accidental

explosion when the operator allowed the pressure to become too high, either

deliberately or through incompetence.

40 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

BOILER LOSSES

FEEDWATER HEATER:

In the case of a conventional steam-electric power plant

utilizing a drum boiler, the surface condenser removes the latent heat of vaporization

from the steam as it changes states from vapour to liquid. The heat content

(joules or Btu) in the steam is referred to as enthalpy. The condensate pump then

pumps the condensate water through a feedwater heater. The feedwater heating

equipment then raises the temperature of the water by utilizing extraction steam from

various stages of the turbine. Preheating the feedwater reduces the irreversibilities

involved in steam generation and therefore improves thethermodynamic efficiency of

the system. This reduces plant operating costs and also helps to avoid thermal shock to

the boiler metal when the feedwater is introduced back into the steam cycle.

41 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

CONDENSER: The surface condenser is a shell and tube heat exchanger in which cooling water is

circulated through the tubes. The exhaust steam from the low pressure turbine enters

the shell where it is cooled and converted to condensate (water) by flowing over the

tubes as shown in the adjacent diagram. Such condensers use steam ejectors or rotary

motor-driven exhausters for continuous removal of air and gases from the steam side

to maintain vacuum. For best efficiency, the temperature in the condenser must be

kept as low as practical in order to achieve the lowest possible pressure in the

condensing steam. Since the condenser temperature can almost always be kept

significantly below 100 °C where the vapor pressure of water is much less than

atmospheric pressure, the condenser generally works under vacuum. Thus leaks of

non-condensable air into the closed loop must be prevented. Plants operating in hot

climates may have to reduce output if their source of condenser cooling water

becomes warmer; unfortunately this usually coincides with periods of high electrical

demand for air conditioning. The condenser generally uses either circulating cooling

water from a cooling tower to reject waste heat to the atmosphere, or once-through

water from a river.

42 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

DEAERATOR: A steam generating boiler requires that the boiler feed water should be devoid of air

and other dissolved gases, particularly corrosive ones, in order to avoid corrosion of

the metal. Generally, power stations use adeaerator to provide for the removal of air

and other dissolved gases from the boiler feed water. A deaerator typically includes a

vertical, domed deaeration section mounted on top of a horizontal cylindrical vessel

which serves as the deaerated boiler feedwater storage tank. There are many different

designs for a deaerator and the designs will vary from one manufacturer to another.

The adjacent diagram depicts a typical conventional trayed deaerator. If operated

properly, most deaerator manufacturers will guarantee that oxygen in the deaerated

water will not exceed 7 ppb by weight (0.005 cm³/L).

43 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

BOILER FEED PUMP A boiler feedwater pump is a specific type of pump used to pump feedwater into

a steam boiler. The water may be freshly supplied or returning condensate produced as

a result of the condensation of the steam produced by the boiler. These pumps are

normally high pressure units that take suction from a condensate return system and

can be of the centrifugal pump type or positive displacement type. Feedwater pumps

range in size up to many horsepower and the electric motor is usually separated from

the pump body by some form of mechanical coupling. Large industrialcondensate

pumps may also serve as the feedwater pump. In either case, to force the water into

the boiler, the pump must generate sufficient pressure to overcome the steam pressure

developed by the boiler. This is usually accomplished through the use of a centrifugal

pump. Feedwater pumps sometimes run intermittently and are controlled by a float

switch or other similar level-sensing device energizing the pump when it detects a

lowered liquid level in the boiler. The pump then runs until the level of liquid in the

boiler is substantially increased. Some pumps contain a two-stage switch. As liquid

lowers to the trigger point of the first stage, the pump is activated. If the liquid

continues to drop (perhaps because the pump has failed, its supply has been cut off or

exhausted, or its discharge is blocked), the second stage will be triggered. This stage

may switch off the boiler equipment (preventing the boiler from running dry and

overheating), trigger an alarm, or both.

44 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

TURBINE SECTION 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 feedwater heaters.

DESIGN DATA:

Economical and max. continuous rating------------------------------- 60 MW

Steam pressure at emergency stop valve------------------------------- 89kg./sqr.cm.

Steam temp. at emergency stop valve ------------------------------------510°C

Absolute pressure at exhaust------------------------------------------------ 0.088kg./sq.cm

Rotational speed---------------------------------------------------------------- 3000 r.p.m

Tripping speed-------------------------------------------------------------------- 3375r.p.m

ALTERNATOR: An alternator is an electrical generator that converts mechanical energy to electrical energy in the form

ofalternating current.[2] For reasons of cost and simplicity, most alternators use a rotating magnetic

field with a stationary armature.[3] Occasionally, a linear alternator or a rotating armature with a stationary

magnetic field is used. In principle, any AC electrical generator can be called an alternator, but usually the

term refers to small rotating machines driven by automotive and other internal combustion engines. An

alternator that uses apermanent magnet for its magnetic field is called a magneto. Alternators in power

stations driven by steam turbines are called turbo-alternators. Large 50 or 60 Hz three phase alternators in

power plants generate most of the world's electric power, which is distributed by electric power grids

A conductor moving relative to a magnetic field develops an electromotive force (EMF) in it (Faraday's

Law). This emf reverses its polarity when it moves under magnetic poles of opposite polarity. Typically, a

rotating magnet, called the rotor turns within a stationary set of conductors wound in coils on an iron core,

called the stator. The field cuts across the conductors, generating an induced EMF (electromotive force),

as the mechanical input causes the rotor to turn.

The rotating magnetic field induces an AC voltage in the stator windings. Since the currents in the stator

windings vary in step with the position of the rotor, an alternator is a synchronous generator.[3]

The rotor's magnetic field may be produced by permanent magnets, or by a field coil electromagnet.

Automotive alternators use a rotor winding which allows control of the alternator's generated voltage by

varying the current in the rotor field winding. Permanent magnet machines avoid the loss due to

magnetizing current in the rotor, but are restricted in size, due to the cost of the magnet material. Since the

permanent magnet field is constant, the terminal voltage varies directly with the speed of the generator.

Brushless AC generators are usually larger than those used in automotive applications.

45 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

An automatic voltage control device controls the field current to keep output voltage constant. If the

output voltage from the stationary armature coils drops due to an increase in demand, more current is fed

into the rotating field coils through the voltage regulator (VR). This increases the magnetic field around

the field coils which induces a greater voltage in the armature coils. Thus, the output voltage is brought

back up to its original value.

Alternators used in central power stations also control the field current to regulate reactive power and to

help stabilize the power system against the effects of momentary faults. Often there are three sets of stator

windings, physically offset so that the rotating magnetic field produces a three phase current, displaced by

one-third of a period with respect to each other.

46 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

ALTERNATOR SPECIFICATIONS:

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

47 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

EXCITATION SYSTEM:

Main Exciter:

Pilot Exciter:

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

48 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

DISTRIBUTED CONTROL SYSTEM(DCS):

Distributed control systems (DCSs) are dedicated systems used to control manufacturing processes that

are continuous or batch-oriented, such as oil refining, petrochemicals, central station power generation,

fertilizers, pharmaceuticals, food and beverage manufacturing, cement production, steelmaking, and

papermaking. DCSs are connected to sensors and actuators and use setpoint control to control the flow of

material through the plant. The most common example is a setpoint control loop consisting of a pressure

sensor, controller, and control valve. Pressure or flow measurements are transmitted to the controller,

usually through the aid of a signal conditioning input/output (I/O) device. When the measured variable

reaches a certain point, the controller instructs a valve or actuation device to open or close until the fluidic

flow process reaches the desired setpoint. Large oil refineries have many thousands of I/O points and

employ very large DCSs. Processes are not limited to fluidic flow through pipes, however, and can also

include things like paper machines and their associated quality controls (see quality control system

QCS), variable speed drivesand motor control centers, cement kilns, mining operations, ore

processing facilities, and many others.

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

executing from 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. Modern DCSs also support neural

networks and fuzzyapplication. Recent research focuses on the synthesis of optimal distributed

controllers, which optimizes a certain H-infinity or H-2 criterion.[1][2]

DCSs are usually designed with redundant processors to enhance the reliability of the control system.

Most systems come with displays and configuration software that enable the end-user to configure the

control system without the need for performing low-level programming, allowing the user also to better

focus on the application rather than the equipment. However, considerable system knowledge and skill is

required to properly deploy the hardware, software, and applications. Many plants have dedicated

personnel who focus on these tasks, augmented by vendor support that may include maintenance support

contracts.

DCSs may employ one or more 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.

49 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

FOXVIEWTM DCS OUTPUT

50 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

INSTRUMENTS REQUIRED:

RESISTANCE TEMPERATURE DETECTOR(RTD)

THERMOCOUPLE

SMART TRANSDUCER

51 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

ORIFICE PLATE

DEAD WEIGHT TESTER

52 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

CONCLUSION

From the above stated facts, we can get an in depth view of what a Power plant is, what it

looks like, the various components in a power plant, etc. This was organized by CESC, Kolkata

and its Subsidiary, Titagarh Generating Station, Titagarh, North 24 Parganas, Kolkata-700 119.

This training comprised of hourly time bound classes as well as visits to the sites

corresponding to the theoretical facts provided. The faculty members have been extremely

helpful in explaining and clarifying our issues.

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.

This training thus has been extremely helpful to me and I would cordially thank everyone

involved with me concerning the training.

53 | VOCATIONAL TRAINING, SUMMER 2016, TITAGARH GENGERATING STATION

BIBLIOGRAPHY/WEBLIOGRAPHY/REFERENCES:

For completion of this report, a handful of resources has been helpful to me. Some of

them are mentioned here:

https://www.cesc.co.in/?page_id=532

https://www.cesc.co.in/?page_id=509

https://en.wikipedia.org/wiki/Thermal_power_station

Power Plant Engineering Paperback – 14 Aug 2007-by PK Nag

Steam Power Plant Engineering- by Gebhardt, George Frederick