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Industrial Training

Report

On

Thermal Power plant

For

partial fulfillment of requirements for the degree

of

B.TECH, EIE, ( VIIth Sem)

At

Rajiv Gandhi Thermal Power Plant( hisar)

A Unit Of

Haryana Power Generation Corporation Ltd. (HPGCL)

Submitted by:

Shiksha

Roll No. 11080857

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Maharishi Markandeshwar University, Mullana

(Ambala)

ACKNOWLEDGEMENT

I am highly indebted to RGTPP Rajiv Gandhi Thermal Power Station Khedar, one of the

having new technology organizations of our nation, for letting me undertake six weeks

training course with them. It was really a very nice experience as we came to know how

actually Electricity generate.

I would like to express my gratitude towards Mr. Surender Parasher (General Manager)

who allowed us to join RGTPP as a trainee, & helped us in every possible way so that we

could complete our training successfully. I also thank Mr. Virender Singh who was there to

Provide training &support us whenever we needed help at every point of our training.

Last but not least I would like to thank all the staff members of RGTPP, especially member

of C&I Deptt, who made this training a rich experience & a success

Name:- Roll No. :-

Shiksha Goyat 11080857

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PREFACE

With the ongoing revolution in electronic where innovations are taking at the

blink of eye, it is impossible to keep the pace with the emerging trends.

Excellence is an attitude that that whole of human race is born with. It is the

environment that makes sure that whether the result of this attitude is visible

or otherwise. A Well planned, properly executed and evaluated industrial

training helps a lot in inculcating a professional attitude. It provides a

linkage between the student and industry to develop an awareness of

industrial approach to problem solving, based on a broad understanding of

process and mode of operation of organization.

During this period, the student gets the real experience for working in the actual Industry

environment. Most of the theoretical knowledge that has been gained during the course of

their studies is put to test here. Apart from this the student gets an opportunity to learn the

latest technology, which is immensely helps in them in building their career.

I had the opportunity to have a real experience on many ventures, which increased my

sphere of knowledge to great extent. I got a chance to learn new technology and was also

interfaced to many instruments.

And all this credit goes to organization Rajiv Gandhi Thermal Power Plant.

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Contents

Sr. No. Topic

1. Introduction 2. History

3. Deal with reliance

4. Constructional View of Thermal Power Station

5. Classification

6. Functional description

7. Components of Plant

8. Auxiliary systems

9. Electric generator

10. Advantages & Disadvantages of coal based thermal Power Plant

11. Thermocouple

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INTRODUCTION

In Rajiv Gandhi Thermal Power Plant .The work for 1200 MW Coal fire

power plant was awarded during 2007. The total estimated cost of the project

is around Rs 4297O crores. The cost of Rs 3.19 crore for MW for this project

is lowest among all the power plants. The first of two 600 MW was

commissioned

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 b oilers. The

waste heat from a gas turbine can be used to raise steam, in a combined cycle

plant that improves overall efficiency. Power plants burning coal, oil, or

natural gas are often referred to collectively as fossil-fuel power plants.

Some biomass-fueled thermal power plants have appeared also. Non-nuclear

thermal power plants, particularly fossil-fueled plants, which do not use

cogeneration, are sometimes referred to as conventional power plants.

In thermal power stations, mechanical power is produced b y a heat engine

that transforms thermal energy, often from combustion of a fuel, into

rotational energy. Most thermal power stations produce steam, and these are

sometimes called steam power stations. Not all thermal energy can be

transformed into mechanical power, according to the second law of

thermodynamics. Therefore, there is always heat lost to the environment. If

this loss is employed as useful heat, for industrial processes or district

heating, the power plant is referred to as a cogeneration power plant or CHP

(combined heat-and-power) plant. In countries where district heating is

common, there are dedicated heat plants called heat-only boiler stations. An

important class of power stations in the Middle East uses by-product heat for

http://en.wikipedia.org/wiki/Coalhttp://en.wikipedia.org/wiki/Coal

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the desalination of water.

Commercial electric utility power stations are most usually constructed on a

very large scale and designed for continuous operation. Electric power plants

typically use three-phase or individual-phase electrical generators to produce

alternating current (AC) electric power at a frequency of 50 Hz or 60 Hz

(hertz, which is an AC sine wave per second) depending on its location in the

world. Other large companies or institutions may have their own usually

smaller power plants to supply heating or electricity to their facilities,

especially if heat or steam is created anyway for other purposes. Shipboard

steam-driven power plants have been used in various large ships in the past,

but these days are used most often in large naval ships. Such shipboard power

plants are general lower power capacity than full-size electric company

plants, but otherwise have many similarities except that typically the main

steam turbines mechanically turn the propulsion propellers, either through

reduction gears or directly by the same shaft. The steam power plants in such

ships also provide steam to separate smaller turbines driving electric

generators to supply electricity in the ship. Shipboard steam power plants can

be either conventional or nuclear; the shipboard nu clear plants are mostly in

the navy. There have been perhaps about a dozen turbo-electric ships in

which a steam-driven turbine drives an electric generator which powers an

electric motor for propulsion.

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

either drives an electrical generator or does some other work, like ship

propulsion. After it passes through the turbine, the steam is condensed in a

condenser and recycled to where it was heated; 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.

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HISTORY

Reciprocating steam engines have been used for mechanical power sources

since the 18th Century, with notable improvements being made by J ames

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 theyencres the hose

power

Deal with reliance

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Reliance Infrastructure, part of the Anil Dhirubhai Ambani Group, Sunday said it has

commissioned a 600 MW unit at the Rajiv Gandhi Khedar Thermal Power Plant

(RGKTPP) at Hisar in Haryana.

The company said this was the countrys largest thermal power generating unit.

The Rs.3,800-crore project, with a total capacity of 1,200 MW, is being set up by the

state government-run Haryana Power Generation Corp and executed by Reliance

Infrastructure.

This project will not only benefit the state by adding 28.8 million units of energy per

day but will also create 15,000 job opportunities in the field of construction, operations

and maintenance, said S.C. Gupta, director-operations for Reliance Infrastructure.

The Reliance Anil Dhirubhai Ambani Group, a zero net debt company, has a market

capitalisation of around $30 billion, net worth in excess of $13.6 billion, operating cash

flow of $2.8 billion and net profit of around $1.8 billion.

Where RGTPP transmit energy?

It transmit electricity to two station one is KIRORY & FATEHABAD. These two are

grid. For transmission we have to use step down transformer to reduce danger. There istransmission from switch yard to grid.

Constructional View of Thermal Power Station

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 and recycled to where it was

heated; 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 electricity [1 ]. Some thermal power plants also deliver

heat energy for industrial purposes, for district heating, or for desalination of

http://en.wikipedia.org/wiki/Power_planthttp://en.wiktionary.org/wiki/prime_moverhttp://en.wiktionary.org/wiki/prime_moverhttp://en.wikipedia.org/wiki/Steamhttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Condensationhttp://en.wikipedia.org/wiki/Surface_condenserhttp://en.wikipedia.org/wiki/Rankine_cyclehttp://en.wikipedia.org/wiki/Heathttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Thermal_power_station#cite_note-0http://en.wikipedia.org/wiki/Thermal_power_station#cite_note-0http://en.wikipedia.org/wiki/District_heatinghttp://en.wikipedia.org/wiki/Desalinationhttp://en.wikipedia.org/wiki/Desalinationhttp://en.wikipedia.org/wiki/District_heatinghttp://en.wikipedia.org/wiki/Thermal_power_station#cite_note-0http://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Heathttp://en.wikipedia.org/wiki/Rankine_cyclehttp://en.wikipedia.org/wiki/Surface_condenserhttp://en.wikipedia.org/wiki/Condensationhttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Steamhttp://en.wiktionary.org/wiki/prime_moverhttp://en.wiktionary.org/wiki/prime_moverhttp://en.wikipedia.org/wiki/Power_plant

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water as well as delivering electrical power. A large part of human

CO 2 emissions comes from fossil fueled thermal power plants; efforts to

reduce these outputs are various and widespread.

Typical diagram of a coal-fired thermal power station

1. Cooling tower 10. Steam Control valve 19. Super heater

2. Cooling water pump11. High pressure steam

turbine

20. Forced draught

(draft) fan

3. transmission line (3-phase) 12. Deaerator 21. Reheater

4. Step-up transformer (3-phase) 13. Feedwater heater 22. Combustion air intake

5. Electrical generator (3-phase) 14. Coal conveyor 23. Economiser

6. Low pressure steam turbine 15. Coal hopper 24. Air preheater

7. Condensate pump 16. Coal pulverizer 25. Precipitator

8. Surface condenser 17. Boiler steam drum26. Induced draught

(draft) fan

9. Intermediate pressure steam

turbine18. Bottom ash hopper 27. Flue gas stack

CLASSIFICATION

http://en.wikipedia.org/wiki/Cooling_towerhttp://en.wikipedia.org/wiki/Control_valvehttp://en.wikipedia.org/wiki/Superheaterhttp://en.wikipedia.org/wiki/Cooling_tower_systemhttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Centrifugal_fanhttp://en.wikipedia.org/wiki/Electrical_power_transmissionhttp://en.wikipedia.org/wiki/Three-phasehttp://en.wikipedia.org/wiki/Deaeratorhttp://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Three-phasehttp://en.wikipedia.org/wiki/Feedwater_heaterhttp://en.wikipedia.org/wiki/Combustionhttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Three-phasehttp://en.wikipedia.org/wiki/Coalhttp://en.wikipedia.org/wiki/Conveyorhttp://en.wikipedia.org/wiki/Economiserhttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Coalhttp://en.wikipedia.org/wiki/Air_preheaterhttp://en.wikipedia.org/wiki/Condensate_pumphttp://en.wikipedia.org/wiki/Pulverizerhttp://en.wikipedia.org/wiki/Electrostatic_precipitatorhttp://en.wikipedia.org/wiki/Surface_condenserhttp://en.wikipedia.org/wiki/Steam_drumhttp://en.wikipedia.org/wiki/Centrifugal_fanhttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Bottom_ashhttp://en.wikipedia.org/wiki/Flue_gas_stackhttp://en.wikipedia.org/wiki/File:PowerStation2.svghttp://en.wikipedia.org/wiki/Flue_gas_stackhttp://en.wikipedia.org/wiki/Bottom_ashhttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Centrifugal_fanhttp://en.wikipedia.org/wiki/Steam_drumhttp://en.wikipedia.org/wiki/Surface_condenserhttp://en.wikipedia.org/wiki/Electrostatic_precipitatorhttp://en.wikipedia.org/wiki/Pulverizerhttp://en.wikipedia.org/wiki/Condensate_pumphttp://en.wikipedia.org/wiki/Air_preheaterhttp://en.wikipedia.org/wiki/Coalhttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Economiserhttp://en.wikipedia.org/wiki/Conveyorhttp://en.wikipedia.org/wiki/Coalhttp://en.wikipedia.org/wiki/Three-phasehttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Combustionhttp://en.wikipedia.org/wiki/Feedwater_heaterhttp://en.wikipedia.org/wiki/Three-phasehttp://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Deaeratorhttp://en.wikipedia.org/wiki/Three-phasehttp://en.wikipedia.org/wiki/Electrical_power_transmissionhttp://en.wikipedia.org/wiki/Centrifugal_fanhttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Cooling_tower_systemhttp://en.wikipedia.org/wiki/Superheaterhttp://en.wikipedia.org/wiki/Control_valvehttp://en.wikipedia.org/wiki/Cooling_tower

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Thermal power plants are classified by the type of fuel and the type of prime mover

Installed.

By fuel

Nuclear power plants use a nuclear reactor's heat to operate a steam turbine

generator.

Fossil fuelled power plants may also use a steam turbine generator or in the

case of natural gas fired plants may use a combustion turbine. A coal-fired

power station produces electricity by burning coal to generate steam, and has

the side-effect of producing a large amount of carbon dioxide, which is

released from burning coal and contributes to global warming

Geothermal power plants use steam extracted from hot u nderground rocks.

Biomass Fuelled Power Plants may be fuelled by waste from sugar cane,

municipal solid waste, landfill methane, or other forms of biomass.

Solar thermal electric plants use sunlight to boil water, which turns the

generator.

By prime mover

Steam turbine plants use the dynamic pressure generated by expanding steam

to turn the blades of a turbineGas turbine plants use the dynamic pressure from flowing gases (air and

combustion products) to directly operate the turbine.

Combined cycle plants have both a gas turbine fired by natural gas, and a

steam boiler and steam turbine which use the hot exhaust gas from the gas

turbine to produce electricity

Reciprocating engines are used to provide power for isolated communities

and are frequently used for small cogeneration plants. Hospitals, office

buildings, industrial plants, and other critical facilities also use them to

provide backup power in case of a power outage

Microturbines, Stirling engine and internal combustion reciprocating engines

are low-cost solutions for using opportunity fuels, such as landfill gas,

digester gas from water treatment plants and waste gas from oil production

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Efficiency

Power is energy per unit time. The power output or capacity of an electric

plant can be expressed in units of megawatts electric (MWe). The electric

efficiency of a conventional thermal power station, considered as saleable

energy (in MWe) produced at the plant busbars as a percent of the heating

value of the fuel consumed, is typically 33% to 48% efficient. This efficiency

is limited as all heat engines are governed 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 go through a condenser and be disposed of with

cooling water or in cooling towers. If the waste heat is instead utilized for

district heating, it is called cogeneration. An important class of thermal

power station is 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 vapor 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.

BASIC DEFINITIONS

Steam is vaporized water and can be produced at 100C at standardatmosphere.

In common speech, steam most often refers to the visible white mist that

condenses above boiling water as the hot vapor mixes with the cooler air.

Turbine A turbine is a rotary engine that extracts energy from a fluid or air

flow and converts it into useful work.

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The simplest turbines have one moving part, a rotor assembly, which is a

shaft or drum, with blades attached. Moving fluid acts on the blades, or the

blades react to the flow, so that they move and impart rotational energy to the

rotor. Early turbine exare windmills and waterwheels.

Fig turbine:-

Electric generator An electric generator is a device that converts mechanical

energy to electrical energy. A generator forces electrons in the windings to

flow through the external electrical circuit. It is somewhat analogous to a

water pump, which creates a flow of water but does not create the water

inside.

Fig Generator:-

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A boiler or steam generator is a device used to create steam by applyingheat

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

(1300 psi/0.06920.684 bar; 6.8952,068.427 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 requ ired.

The form and size depends on the application: mobile steam engines such as

steam locomotives, portable engines and steam -powered road vehicles

typically use a smaller boiler that forms an integral part of the vehicle;

Second law of thermodynamics The second law of thermodynamics is an

expression of the universal principle of entropy, stating that the entropy of

anisolated system which is not in equilibrium will tend to increase over time,

approaching a maximum value at equilibrium; and that the entropy change

dSof a system undergoing any infinitesimal reversible process is given by dq

/ T, where dq is the hea t suppli ed to the sys tem and T is the abs olute

temperature of the system.

Coal Handling Plant (CHP):- Extent of work: - In brief we can say that receipt of coal from coal

mines, weighing of coal, crushing it to required size and transferring

the quanta of coal to various coal mill bunkers. This is the

responsibility and duty of the CHP and its staff.

CHP is (C- Coal, H- Handling, P- Plant) a plant which handles the coal

from its receipt to transporting it to Boiler and store in Bunkers. It also

processes the raw coal to make it suitable for Boiler Opeartion.Receipt of Coal:-

Normally Thermal Power Station receives the coal by three modes of

transportation.

1. By Railway (80-90% of the requirement is fulfilled by this way)

2. By Road ( if required 5-10% of the requirement is fulfilled by this

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way)

3. By Arial ropeways

.. Arial ropeway is available only to the power stations which are near

the coal mines

Cost of coal transportation by road is much higher than that for rail

transport hence most of the coal requirement of the power stations is

fulfilled by railway transport.

Demurrage calculations on coal Rakes:-

We receive the coal wagons in the form of rakes (55-60 wagons in each

rake).

These coal rakes are to be unloaded in given free time normally 12-

14 hrs. from the time of receipt of coal rakes.

Free time is calculated from the receipt of written intimation of coal

rakes from the railway and written intimation of empty rake formation

from MSEB to railway.

Rate of demurrage is Rs.1/- per ton per hour.

If coal rake is not unloaded in given free time the demurrage shall be

charged on complete capacity (approx. 3300 metric ton) of coal rake at

the rate of Rs. 1/- per ton per hour

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FUNCTIONAL DESCRIPTION

Diagram of a typical coal-fired thermal power station

The superheated steam from the final superheater is taken to the High Pressure Steam

Turbine (HPT). In the HPT the steam pressure is utilized to rotate the turbine and the

resultant is rotational energy. From the HPT the out coming steam is taken to the

Reheater in the boiler to increase its temperature as the steam becomes wet at the HPT

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outlet. After reheating this steam is taken to the Intermediate Pressure Turbine (IPT) and

then to the Low Pressure Turbine (LPT). The outlet of the LPT is sent to the condenser

for condensing back to water by a cooling water system. This condensed water is

collected in the Howells and is again sent to the boiler in a closed cycle. The rotational

energy imparted to the turbine by high pressure steam is converted to electrical energy in

the Generator.

Components of Coal Fired Thermal Power Station:

Coal Preparation

i) 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 hoppersat the boilers. The coal is next pulverized into a very fine powder, so that coal will

undergo complete combustion during combustion process.

ii) Dryers: they are used in order to remove the excess moisture from coal mainly wetted

during transport. As the presence of moisture will result in fall in efficiency due to

incomplete combustion and also result in CO emission.

iii) Magnetic separators: coal which is brought may contain iron particles. These iron

particles may result in wear and tear. The iron particles may include bolts, nuts wire fish

plates etc. so these are unwanted and so are removed with the help magnetic separators.

The coal we finally get after these above process are transferred to the storage site.

Purpose of fuel storage is two

Fuel storage is insurance from failure of normal operating supplies to arrive. Storage permits some choice of the date of purchase, allowing the purchaser to take

advantage of seasonal market conditions. Storage of coal is primarily a matter of

protection against the coal strikes, failure of the transportation system & general

coal shortages.

There are two types of storage:

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1. Live Storage (boiler room storage): storage from which coal may be withdrawn tosupply combustion equipment with little or no remanding is live storage. This storage

consists of about 24 to 30 hrs. of coal requirements of the plant and is usually a

covered storage in the plant near the boiler furnace. The live storage can be provided

with bunkers & coal bins. Bunkers are enough capacity to store the requisite of coal.

From bunkers coal is transferred to the boiler grates.

2. Dead storagestored for future use. Mainly it is for longer period of time, and it isalso mandatory to keep a backup of fuel for specified amount of days depending on

the reputation of the company and its connectivity.

There are many forms of storage some of which are

1. Stacking the coal in heaps over available open ground areas.2. As in (I). But placed under cover or alternatively in bunkers.

3. Allocating special areas & surrounding these with Live Storage(boiler roomstorage): storage from which coal may be withdrawn to supply combustion equipment

with little or no remanding is live storage. This storage consists of about 24 to 30 hrs.

of coal requirements of the plant and is usually a covered storage in the plant near the

boiler furnace. The live storage can be provided with bunkers & coal bins. Bunkers

are enough capacity to store the requisite of coal. From bunkers coal is transferred to

the boiler grates.

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.

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Boiler furnace and steam drum

Once water inside the boiler or steam generator, the process of adding the latent heat of

vaporization or enthalpy is underway. The boiler transfers energy to the water by thechemical reaction of burning some type of fuel.The water enters the boiler through a

section in the convection pass called the economizer. From the economizer it passes to

the steam drum. Once the water enters the steam drum it goes down the down comers to

the lower inlet water wall headers. From the inlet headers the water rises through the

water walls and is eventually turned into steam due to the heat being generated by the

burners located on the front and rear water walls (typically). As the water is turned into

steam/vapor in the water walls, the steam/vapor once again enters the steam drum. The

steam/vapor is passed through a series of steam and water separators and then dryers

inside the steam drum. The steam separators and dryers remove water droplets from the

steam and the cycle through the water walls is repeated. This process is known as natural

circulation.

The boiler furnace auxiliary equipment includes coal feed nozzles and igniter guns, soot

blowers, water lancing and observation ports (in the furnace walls) for observation of the

furnace interior. Furnace explosions due to any accumulation of combustible gases after a

trip-out are avoided by flushing out such gases from the combustion zone before igniting

the coal.

The steam drum (as well as the superheater coils and headers) have air vents and drains

needed for initial startup. The steam drum has internal devices that remove moisture from

the wet steam entering the drum from the steam generating tubes. The dry steam then

flows into the superheater coils.

Superheater

Coal based power plants can have a superheater and/or reheater section in the steam

generating furnace. Nuclear-powered steam plants do not have such sections but produce

steam at essentially saturated conditions. In a coal based plant, after the steam is

conditioned by the drying equipment inside the steam drum, it is piped from the upper

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drum area into tubes inside an area of the furnace known as the superheater, which has an

elaborate set up of tubing where the steam vapor picks up more energy from hot flue

gases outside the tubing and its temperature is now superheated above the saturation

temperature. The superheated steam is then piped through the main steam lines to the

valves before the high pressure turbine.

Reheater

Power plant furnaces may have a reheater section containing tubes heated by hot flue

gases outside the tubes. Exhaust steam from the high pressure turbine is rerouted to go

inside the reheater tubes to pickup more energy to go drive intermediate or lower pressure

turbines. This is what is called as thermal power.

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 a deaerator 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 feed water storage tank

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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 induceddraft 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.

Boiler make-up water treatment plant and storage

Since there is continuous withdrawal of steam and continuous return of condensate to the

boiler, losses due to blow down and leakages have to be made up to maintain a desired

water level in the boiler steam drum. For this, continuous make-up water is added to the

boiler water system. Impurities in the raw water input to the plant generally consist of

calcium and magnesium salts which impart hardness to the water. Hardness in the make-

up water to the boiler will form deposits on the tube water surfaces which will lead to

overheating and failure of the tubes. Thus, the salts have to be removed from the water,

and that is done by a waterdemineralising treatment plant (DM). A DM plant generally

consists of cation, anion, and mixed bed exchangers. Any ions in the final water from this

process consist essentially of hydrogen ions and hydroxide ions, which recombine to

form pure water. Very pure DM water becomes highly corrosive once it absorbs oxygen

from the atmosphere because of its very high affinity for oxygen.

The capacity of the DM plant is dictated by the type and quantity of salts in the raw water

input. However, some storage is essential as the DM plant may be down for maintenance.

For this purpose, a storage tank is installed from which DM water is continuously

withdrawn for boiler make-up. The storage tank for DM water is made from materials not

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affected by corrosive water, such as PVC. The piping and valves are generally of

stainless steel. Sometimes, a steam blanketing arrangement or stainless steel doughnut

float is provided on top of the water in the tank to avoid contact with air. DM water

make-up is generally added at the steam space of the surface condenser (i.e., the vacuum

side). This arrangement not only sprays the water but also DM water gets deaerated, with

the dissolved gases being removed by an air ejector attached to the condenser.

Generator cooling

While small generators may be cooled by air drawn through filters at the inlet, larger

units generally require special cooling arrangements. Hydrogen gas cooling, in an oil-

sealed casing, is used because it has the highest known heat transfer coefficient of any

gas and for its low viscosity which reduces wind age losses. This system requires special

handling during start-up, with air in the generator enclosure first displaced by carbon

dioxide before filling with hydrogen. This ensures that the highly flammable hydrogen

does not mix with oxygen in the air.

The hydrogen pressure inside the casing is maintained slightly higher than atmospheric

pressure to avoid outside air ingress. The hydrogen must be sealed against outward

leakage where the shaft emerges from the casing. Mechanical seals around the shaft are

installed with a very small annular gap to avoid rubbing between the shaft and the seals.

Seal oil is used to prevent the hydrogen gas leakage to atmosphere.

The generator also uses water cooling. Since the generator coils are at a potential of about

22 kV and water is conductive, an insulating barrier such as Teflon is used to

interconnect the water line and the generator high voltage windings. Demineralized water

of low conductivity is used.

Generator high voltage system

The generator voltage for modern utility-connected generators ranges from 11 kV in

smaller units to 22 kV in larger units. The generator high voltage leads are normally large

aluminum channels because of their high current as compared to the cables used in

smaller machines. They are enclosed in well-grounded aluminum bus ducts and are

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supported on suitable insulators. The generator high voltage leads are connected to step-

up transformers for connecting to a high voltage electrical substation (of the order of 115

kV to 520 kV) for further transmission by the local power grid.

The necessary protection and metering devices are included for the high voltage leads.

Thus, the steam turbine generator and the transformer form one unit. Smaller units may

share a common generator step-up transformer with individual circuit breakers to connect

the generators to a common bus.

Condenser

Diagram of a typical water-cooled surface 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

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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, lake or ocean.

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 Air ejector

condenser and Gland steam exhauster condenser. From there the condensate goes to the

deareator where the condenstae system ends and the Feedwater system begins.

Preheating the feedwater reduces the irreversibilities involved in steam generation and

therefore improves the thermodynamic 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.

Conveyor system

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A conveyor system is a common piece of mechanical handling equipment that moves

materials from one location to another. Conveyors are especially useful in applications

involving the transportation of heavy or bulky materials. Conveyor systems allow quick

and efficient transportation for a wide variety of materials, which make them very

popular in the material handling and packaging industries. Many kinds of conveying

systems are available, and are used according to the various needs of different industries.

There are chain conveyors as well. Chain conveyors consist of enclosed tracks, I-Beam,

towline, power & free, and hand pushed trolleys.

Care and Maintenance of Conveyor Systems

Poor take-up adjustment

Lack of lubrication Product Handling: Bad Belt Tracking or Timing

Cooling tower

A cooling tower is a heat rejection device, which extracts waste heat to the atmosphere

though the cooling of a water stream to a lower temperature. The type of heat rejection in

a cooling tower is termed evaporative in that it allows a small portion ofthe water

being cooled to evaporate into a moving air stream to provide significant cooling to the

rest of that water stream. The heat from the water stream transferred to the air stream

raises the airs temperature and its relative humidity to 100%, and this air is discharged to

the atmosphere. Evaporative heat rejection devices such as cooling towers are commonly

used to provide significantly lower water temperatures than achievable with air cooled

or dry heat rejection devices, like the radiator in a car, thereby achieving more cost-

effective and energy efficient operation of systems in need of cooling. The cooling towers

are of two types: -

1. Natural Draft Cooling Tower2. Mechanized Draft Cooling Tower

i. Forced Draft cooling tower

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ii. Induced Draft cooling tower

iii. Balanced Draft cooling tower

Auxiliary systems

Oil systemAn auxiliary oil system pump is used to supply oil at the start-up of the steam turbine

generator. It supplies the hydraulic oil system required for steam turbines main inlet

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steam stop valve, the governing control valves, the bearing and seal oil systems, the

relevant hydraulic relays and other mechanisms.

At a preset speed of the turbine during start-ups, a pump driven by the turbine main shafttakes over the functions of the auxiliary system.

Monitoring and alarm systemMost of the power plant operational controls are automatic. However, at times, manual

intervention may be required. Thus, the plant is provided with monitors and alarm

systems that alert the plant operators when certain operating parameters are seriously

deviating from their normal range.

Battery supplied emergency lighting and communicationA central battery system consisting of lead acid cell units is provided to supply

emergency electric power, when needed, to essential items such as the power plants

control systems, communication systems, turbine lube oil pumps, and emergency

lighting. This is essential for a safe, damage-free shutdown of the units in an emergency

situation.

Electric generator

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In electricity generation, an electric generator is a device that converts mechanical

energy to electrical energy. A generator forces electrons in the windings to flow

through the external electrical circuit. It is somewhat analogous to a water pump,

which creates a flow of water but does not create the water inside. The source of

mechanical energy may be a reciprocating or turbine steam engine, water falling

through a turbine or waterwheel, an internal combustion engine, a wind turbine, a

hand crank, compressed air or any other source of mechanical energy.

The reverse conversion of electrical energy into mechanical energy is done by

an electric motor, and motors and generators have many similarities. In fact many

motors can be mechanically driven to generate electricity, and very frequently

make acceptable generators. a

Alternator

Without a commutator, a dynamo becomes an alternator, which is a synchronous

singly-fed generator. When used to feed an electric power grid, an alternator must

always operate at a constant speed that is precisely synchronized to the electrical

frequency of the power grid. A DC generator can operate at any speed within

mechanical limits, but always outputs direct current.

The primary advantage of the alternator is that the field windings can be swapped

from the exterior non-rotating shell to the interior rotating shaft, and the current

producing windings are on the exterior shell. This allows for extremely thick

current producing windings that stay in a fixed position with permament non-

moving wiring.

The rotating field coil by contrast can operate at high voltage and low current so

that only small, simple, and low-cost slip rings are needed. For example,

automotive alternators commonly only use a single carbon brush to supply power

to the field coil; the other end of the coil is attached to the vehicle ground by way

of the rotor bearings.

By using a rotary transformer to convey power to the rotating field coil, no

rubbing physical contacts are needed at all, and the alternator becomes an almost

maintenance-free power generation device

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Tachogenerator

Tachogenerators are frequently used to power tachometers to measure the speeds

of electric motors, engines, and the equipment they power. Generators generate

voltage roughly proportional to shaft speed. With precise construction and design,

generators can be built to produce very precise voltages for certain ranges of shaft

speeds

Sources of error:-

The common error sources of a PRT are:

Interchangeability: the closeness of agreement between the specific PRT's

Resistance vs. Temperature relationship and a predefined Resistance vs.

Temperature relationship, commonly defined by IEC 60751.

Insulation Resistance: Error caused by the inability to measure the actual resistance

of element. Current leaks into or out of the circuit through the sheath, between the

element leads, or the elements.

Stability: Ability to maintain R vs T over time as a result of thermal exposure.

Repeatability: Ability to maintain R vs T under the same conditions after

experiencing thermal cycling throughout a specified temperature range.

Hysteresis: Change in the characteristics of the materials from which the RTD is

built due to exposures to varying temperatures.

Stem Conduction: Error that results from the PRT sheath conducting heat into or

out of the process.

Calibration/Interpolation: Errors that occur due to calibration uncertainty at the cal

points, or between cal point due to propagation of uncertainty or curve fit errors.

Lead Wire: Errors that occur because a 4 wire or 3 wire measurement is not used,

this is greatly increased by higher gauge wire.

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2 wire connection adds lead resistance in series with PRT element.

3 wire connection relies on all 3 leads having equal resistance.

Self Heating: Error produced by the heating of the PRT element due to the power

applied.

Time Response: Errors are produced during temperature transients because the PRT

cannot respond to changes fast enough .Thermal EMF: Thermal EMF errors are

produced by the EMF adding to or subtracting from the applied sensing voltage,

primarily in DC systems

Advantages of coal based thermal Power Plant

They can respond to rapidly changing loads without difficulty A portion of the steam generated can be used as a process steam in different

industries

Steam engines and turbines can work under 25 % of overload continuously Fuel used is cheaper Cheaper in production cost in comparison with that of diesel power stations

Disadvantages of coal based thermal Power Plant

Maintenance and operating costs are high Long time required for erection and putting into action A large quantity of water is required Great difficulty experienced in coal handling Presence of troubles due to smoke and heat in the plant Unavailability of good quality coal Maximum of heat energy lost

Thermocouple

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Thermocouple plugged to a multimeter displaying room temperature in C.

A thermocouple is a junction between two different metals that produces a voltage related

to a temperature difference. Thermocouples are a widely used type of temperature sensorfor measurement and control and can also be used to convert heat gradient into

electricity. They are inexpensive and interchangeable, are supplied fitted with standard

connectors, and can measure a wide range of temperatures. The main limitation is

accuracy: system errors of less than one degree Celsius (C) can be difficult to achieve.

Any junction of dissimilar metals will produce an electric potential related to

temperature. Thermocouples for practical measurement of temperature are junctions of

specific alloys which have a predictable and repeatable relationship between temperature

and voltage. Different alloys are used for different temperature ranges. Properties such as

resistance to corrosion may also be important when choosing a type of thermocouple.

Where the measurement point is far from the measuring instrument, the intermediate

connection can be made by extension wires which are less costly than the materials used

to make the sensor. Thermocouples are usually standardized against a reference

temperature of 0 degrees Celsius; practical instruments use electronic methods of cold-

junction compensation to adjust for varying temperature at the instrument terminals.

Electronic instruments can also compensate for the varying characteristics of the

thermocouple, and so improve the precision and accuracy of measurements.

Thermocouples are widely used in science and industry; applications include temperature

measurement for kilns, gas turbine exhaust, diesel engines, and other industrial processes.

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Principle of operation:-

In 1821, the GermanEstonian physicist Thomas Johann Seebeck discovered that when

any conductor is subjected to a thermal gradient, it will generate a voltage. This is now

known as the thermoelectric effect or Seebeck effect. Any attempt to measure this voltage

necessarily involves connecting another conductor to the "hot" end. This additional

conductor will then also experience the temperature gradient, and develop a voltage of its

own which will oppose the original. Fortunately, the magnitude of the effect depends on

the metal in use. Using a dissimilar metal to complete the circuit creates a circuit in

which the two legs generate different voltages, leaving a small difference in voltage

available for measurement. That difference increases with temperature, and is between 1

and 70 microvolts per degree Celsius (V/C) for standard metal combinations.

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The voltage is not generated at the junction of the two metals of the thermocouple but

rather along that portion of the length of the two dissimilar metals that is subjected to a

temperature gradient. Because both lengths of dissimilar metals experience the same

temperature gradient, the end result is a measurement of the temperature at the

thermocouple junction.

High Static Gauge Pressure Transmitter

The high performance gauge pressure transmitter model EJA440A can be used to

measure liquid, gas, or steam pressure. It outputs a 4 to 20 mA DC signal corresponding

to the measured gauge pressure.

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The EJA Series is available with BRAIN, HART, FOUNDATION fieldbus or

PROFIBUS PA communication protocols.

Features

Excellent performance and stabilityThe EJA series uses a silicon resonant sensor formed from monocrystal silicon, a

perfect material which has no hysteresis in pressure or temperature changes. The sensor

minimizes overpressure, temperature change, and static pressure effects, and thus offers

unmatched long-term stability.

Compact and light-weight designHalf the weight of conventional models thanks to miniaturization of the casing

with the amplifier ASIC, pressure cell structure, and flange. The ASIC uses the minimum

number of parts and improves the reliability of the amplifier.

Fieldbus communication capabilityFieldbus is a digital two-way communication system. It is a revolutionary

technology for configuring instrumentation control systems and a promising successor to

the standard 4 to 20 mA analog communication used in most field instruments today.

EJA series offers two types of fieldbus models, FOUNDATION fieldbus Low Voltage

Mode and PROFIBUS PA devices, which ensure interoperability between Yokogawa and

other manufactures. As for software, the EJA series incorporates two AI function blocks

that compute differential and static pressures to allow flexible configuration of

instrumentation.

Specifications of Gauge Pressure Transmitter

C Capsule D Capsule

Range -0.1 to 32 MPa

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Accuracy 0.12% 0.12%

Certificates FM, CENELEC ATEX, CSA, IECEx

Output 4 to 20 mA DC or FOUNDATION fieldbus or PROFIBUS PA 2-wire system

with digital communication

Ambient temperature -40 to 85 deg C (-40 to 185 deg F) (general use type)

-30 to 80 deg C (-22 to 176 deg F) (with integral indicator)

Process temperature -40 to 120 deg C (-40 to 248 deg F) (general use type)

Maximum overpressure 48 MPa (6750 psig) 60 MPa (8500 psig)

Absolute and Gauge Pressure Transmitter

The general purpose absolute and gauge pressure transmitter EJX510A and EJX530A

feature single crystal silicon resonant sensor and are suitable to measure liquid, gas, orsteam pressure.

The multi-sensing technology provides the advanced diagnostic function to detect such

abnormalities as an impulse line blockage or heat trace breakage.

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The EJX series is available with BRAIN, HART, and FOUNDATION fieldbus

communication protocols.

Specifications :-

Accuracy 0.1%

Supply voltage BRAIN and HART:10.5 to 42 V DC

(10.5 to 30 V DC for Intrinsically safe type)

Ambient temperature -40 to 85 deg C (-40 to 185 deg F) (general use type)

-30 to 80 deg C (-22 to 176 deg F) (with integral indicator)

Process temperature -40 to 120 deg C (-40 to 248 deg F) (general use type)