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CertificateThis is to certify that the Seminar entitled ________ being

submitted by ______ bearing Registration No.____ in partial

fulfillment of the requirement for the award of the degree of Bachelor

of Technology in Mechanical Engineering at BRMIIT.

Seminar In-charge:

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cknowledgementI am extremely grateful to______, H.O.D of Mechanical Dept. for giving me his

consent to carry out the seminar. I like to thank _________ for her support and

input which not only helped me prepare the seminar but also present it

successfully.

I would also like to thank other teaching staffs of Mechanical EngineeringDepartment for their active involvement in the entire process from the beginning.I would take the opportunity of thanking my parents and not to forget my Groupmates from who inspired a lot.

______________

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PREFACE

A student gets theoretical knowledge from classroom and gets practical knowledge from

industrial training. When these two aspects of theoretical knowledge and practical experience

together then a student is full equipped to secure his best. In conducting the project study in an

industry, students get exposed and have knowledge of real situation in the work field and gains

experience from them. The object of the summer training cum project is to provide an

opportunity to experience the practical aspect of Technology in any organization. It provides a

chance to get the feel of the organization and its function. The fact that thermal energy is the

major source of power generation itself shows the importance of thermal power generation in

India more than 60 percent of electric power is produced by steam plant in India. In steam

power plants, the heat of combustion of fossil fuels is utilized by the boilers to raise steam at

high pressure and temperature. The steam so produced is used in driving the steam turbine

coupled to generators and thus in generating ELECTRICAL ENERGY

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ABSTRACT

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 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. 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. 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.

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1-INTRODUCTION

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. 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 by 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 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

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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 nuclear 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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Fig-1-Working model of a Thermal power Generation

FIGURE DESCRIBTION

In a thermal power station fuel such as coal, oil or gas is burned in a furnace to produce heat -

chemical to heat energy.

This heat is used to change water into steam in the boiler.

The steam drives the turbine - heat to kinetic energy

This drives the generator to produce electricity - kinetic to electrical energy.

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2-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 they encores the hose

power. A power station (also referred to as a generating station, power plant, or powerhouse) is

an industrial facility for thegeneration of electric power. Almost allcoal,nuclear,

geothermal,solar thermal electric, and waste incineration plants, as well as many natural gas

power plants are thermal.Natural gas is frequently combusted ingas turbines as well as boilers.

The waste heat from a gas turbine can be used to raise steam, in acombined cycleplant that

improves overall efficiency. Power plants burning coal,oil, ornatural gas are often referred to

collectively asfossil-fuel power plants. Somebiomass-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. A thermal power

station is apower plant in which theprime mover issteam driven. Water is heated, turns into

steam and spins a steam turbine which either drives an electrical generator or does some other

work, likeship propulsion. After it passes through the turbine, the steam iscondensed in a

condenser and recycled to where it was heated; this is known as a Rankin 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 centerbecause such facilities convert forms ofheatenergy into electrical

energy. In thermal power stations, mechanical power is produced by a heat engine that

transformsthermal energy,often fromcombustion of afuel,into rotational energy. Most thermal

power stations produce steam, and these are sometimes called steam power stations. Not all

http://www.google.com/url?q=http%3A%2F%2Fgeneration&sa=D&sntz=1&usg=AFQjCNHOicx1fndz7NwImKrCGkvz4iq5Jghttp://www.google.com/url?q=http%3A%2F%2Fpower&sa=D&sntz=1&usg=AFQjCNE5cbI557xXosIpgh_IVmsVU1zj6ghttp://www.google.com/url?q=http%3A%2F%2Fcoal&sa=D&sntz=1&usg=AFQjCNEGoIuTNqbQniey6_lpS_Jjs9ey1Ahttp://www.google.com/url?q=http%3A%2F%2Fpower&sa=D&sntz=1&usg=AFQjCNE5cbI557xXosIpgh_IVmsVU1zj6ghttp://www.google.com/url?q=http%3A%2F%2Fpower&sa=D&sntz=1&usg=AFQjCNE5cbI557xXosIpgh_IVmsVU1zj6ghttp://www.google.com/url?q=http%3A%2F%2Felectric&sa=D&sntz=1&usg=AFQjCNFYStp1GwFuigWxOo2m2u-6cjd4xQhttp://www.google.com/url?q=http%3A%2F%2Fincineration&sa=D&sntz=1&usg=AFQjCNFWfUqpzpEF-xfYAHzUbDMMvBcutghttp://www.google.com/url?q=http%3A%2F%2Fgas&sa=D&sntz=1&usg=AFQjCNEzTzSopnGRTcxYwDL5bNEDWL_4OAhttp://www.google.com/url?q=http%3A%2F%2Fcombustion&sa=D&sntz=1&usg=AFQjCNE4XGWRJ5kviJwFgpJN8R4RHkps1ghttp://www.google.com/url?q=http%3A%2F%2Fturbine&sa=D&sntz=1&usg=AFQjCNElIdZfmvhp1-SBkRKfUuDOU0bz7Ahttp://www.google.com/url?q=http%3A%2F%2Fcycle&sa=D&sntz=1&usg=AFQjCNGNfxD4ZQGCkeAeRQkGhBIbSTsLDQhttp://www.google.com/url?q=http%3A%2F%2Foil&sa=D&sntz=1&usg=AFQjCNGoQxl7O7tOziS1_KdSpbTz-0VIVghttp://www.google.com/url?q=http%3A%2F%2Fgas&sa=D&sntz=1&usg=AFQjCNEzTzSopnGRTcxYwDL5bNEDWL_4OAhttp://www.google.com/url?q=http%3A%2F%2Fplant&sa=D&sntz=1&usg=AFQjCNGYTYGsrgmfvPHDv5GFW24CRi4G7whttp://www.google.com/url?q=http%3A%2F%2Fbiomass&sa=D&sntz=1&usg=AFQjCNFTuWJECc4Ppa1GXcK86jgyQeWIxAhttp://www.google.com/url?q=http%3A%2F%2Fcogeneration&sa=D&sntz=1&usg=AFQjCNFumyeXjS-oOE2WcYZPFGtSFqXIVQhttp://www.google.com/url?q=http%3A%2F%2Fplant&sa=D&sntz=1&usg=AFQjCNGYTYGsrgmfvPHDv5GFW24CRi4G7whttp://www.google.com/url?q=http%3A%2F%2Fmover&sa=D&sntz=1&usg=AFQjCNF4NfdX_514Ssdlnp-jZSc92VxBHghttp://www.google.com/url?q=http%3A%2F%2Fsteam&sa=D&sntz=1&usg=AFQjCNGmD1d-HywwdgFbV5rhwoiuoNv0Ughttp://www.google.com/url?q=http%3A%2F%2Fturbine&sa=D&sntz=1&usg=AFQjCNElIdZfmvhp1-SBkRKfUuDOU0bz7Ahttp://www.google.com/url?q=http%3A%2F%2Fgenerator&sa=D&sntz=1&usg=AFQjCNEyoMwTr1M2KrU6gJDnsv4yiaMXkwhttp://www.google.com/url?q=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FShip%23Ship&sa=D&sntz=1&usg=AFQjCNFHeW9OljfCk02e6LRFJEXYXkCXZwhttp://www.google.com/url?q=http%3A%2F%2Fcondensation&sa=D&sntz=1&usg=AFQjCNGYXci9ficsNKPeB_SWplMPqrnQwghttp://www.google.com/url?q=http%3A%2F%2Fcondenser&sa=D&sntz=1&usg=AFQjCNFyMgT70fIeOtRMLWM_qvl0q65VTghttp://www.google.com/url?q=http%3A%2F%2Fcycle&sa=D&sntz=1&usg=AFQjCNGNfxD4ZQGCkeAeRQkGhBIbSTsLDQhttp://www.google.com/url?q=http%3A%2F%2Fheat&sa=D&sntz=1&usg=AFQjCNFZBlTsD-Cwd4d3SiSdbZ0wpVjRAghttp://www.google.com/url?q=http%3A%2F%2Fenergy&sa=D&sntz=1&usg=AFQjCNHXo-_7lABsMzKhoZS6-1OgLeTmbghttp://www.google.com/url?q=http%3A%2F%2Fengine&sa=D&sntz=1&usg=AFQjCNF13YN9O_XHctCkT_etnarzi2Y6wwhttp://www.google.com/url?q=http%3A%2F%2Fenergy&sa=D&sntz=1&usg=AFQjCNHXo-_7lABsMzKhoZS6-1OgLeTmbghttp://www.google.com/url?q=http%3A%2F%2Fcombustion&sa=D&sntz=1&usg=AFQjCNE4XGWRJ5kviJwFgpJN8R4RHkps1ghttp://www.google.com/url?q=http%3A%2F%2Ffuel&sa=D&sntz=1&usg=AFQjCNFIgf-PeIHo7pmUiVnluqyEfR7B0whttp://www.google.com/url?q=http%3A%2F%2Ffuel&sa=D&sntz=1&usg=AFQjCNFIgf-PeIHo7pmUiVnluqyEfR7B0whttp://www.google.com/url?q=http%3A%2F%2Fcombustion&sa=D&sntz=1&usg=AFQjCNE4XGWRJ5kviJwFgpJN8R4RHkps1ghttp://www.google.com/url?q=http%3A%2F%2Fenergy&sa=D&sntz=1&usg=AFQjCNHXo-_7lABsMzKhoZS6-1OgLeTmbghttp://www.google.com/url?q=http%3A%2F%2Fengine&sa=D&sntz=1&usg=AFQjCNF13YN9O_XHctCkT_etnarzi2Y6wwhttp://www.google.com/url?q=http%3A%2F%2Fenergy&sa=D&sntz=1&usg=AFQjCNHXo-_7lABsMzKhoZS6-1OgLeTmbghttp://www.google.com/url?q=http%3A%2F%2Fheat&sa=D&sntz=1&usg=AFQjCNFZBlTsD-Cwd4d3SiSdbZ0wpVjRAghttp://www.google.com/url?q=http%3A%2F%2Fcycle&sa=D&sntz=1&usg=AFQjCNGNfxD4ZQGCkeAeRQkGhBIbSTsLDQhttp://www.google.com/url?q=http%3A%2F%2Fcondenser&sa=D&sntz=1&usg=AFQjCNFyMgT70fIeOtRMLWM_qvl0q65VTghttp://www.google.com/url?q=http%3A%2F%2Fcondensation&sa=D&sntz=1&usg=AFQjCNGYXci9ficsNKPeB_SWplMPqrnQwghttp://www.google.com/url?q=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FShip%23Ship&sa=D&sntz=1&usg=AFQjCNFHeW9OljfCk02e6LRFJEXYXkCXZwhttp://www.google.com/url?q=http%3A%2F%2Fgenerator&sa=D&sntz=1&usg=AFQjCNEyoMwTr1M2KrU6gJDnsv4yiaMXkwhttp://www.google.com/url?q=http%3A%2F%2Fturbine&sa=D&sntz=1&usg=AFQjCNElIdZfmvhp1-SBkRKfUuDOU0bz7Ahttp://www.google.com/url?q=http%3A%2F%2Fsteam&sa=D&sntz=1&usg=AFQjCNGmD1d-HywwdgFbV5rhwoiuoNv0Ughttp://www.google.com/url?q=http%3A%2F%2Fmover&sa=D&sntz=1&usg=AFQjCNF4NfdX_514Ssdlnp-jZSc92VxBHghttp://www.google.com/url?q=http%3A%2F%2Fplant&sa=D&sntz=1&usg=AFQjCNGYTYGsrgmfvPHDv5GFW24CRi4G7whttp://www.google.com/url?q=http%3A%2F%2Fcogeneration&sa=D&sntz=1&usg=AFQjCNFumyeXjS-oOE2WcYZPFGtSFqXIVQhttp://www.google.com/url?q=http%3A%2F%2Fbiomass&sa=D&sntz=1&usg=AFQjCNFTuWJECc4Ppa1GXcK86jgyQeWIxAhttp://www.google.com/url?q=http%3A%2F%2Fplant&sa=D&sntz=1&usg=AFQjCNGYTYGsrgmfvPHDv5GFW24CRi4G7whttp://www.google.com/url?q=http%3A%2F%2Fgas&sa=D&sntz=1&usg=AFQjCNEzTzSopnGRTcxYwDL5bNEDWL_4OAhttp://ww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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 ordistrict heating, the power plant is referred to as

cogeneration power plant or CHP (combined heat-and-power) plant. In countries where district

heating is common, there are dedicated heat plants calledheat-only boiler stations.An important

class of power stations in the Middle East uses by-product heat for thedesalination of water.

3-NEED FOR THERMAL POWER GENERATION

Scarcity of water resources: Water resources are not abundantly available and are geographically

unevenly distributed. Thus hydel power plants cannot be installed with ease and are limited to

certain locations. Widely available alternate flues: Many alternate fuels such as coal, diesel,

nuclear fuels, geo-thermal energy sources, solar-energy, and biomass fuels can be used to

generate power using steam cycles. Maintenance and lubrication cost is lower: Once installed,

these require less maintenance costs and on repairs. Lubrication is not a major problem

compared to hydel power plant. Coal is abundant: Coal is available in excess quantities in India

and is rich form of energy available at relatively lower cost. Working fluid remains within the

system, and need not be replaced every time thus simplifies the process.

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4-CLASSIFICATION

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

4.1-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 underground 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.

4.2-BY PRIME MOVER

Steam turbine plants use the dynamic pressure generated by expanding steam to turn the blades

of a turbine Gas 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

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power outage Micro turbines, Sterling 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

5-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.

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6-BASIC DEFINITIONS

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

7-TYPICAL 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.

8-TYPICAL GENERATOR

A boiler or steam generator is a device used to create 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 (1300 si/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 required. The form

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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 an isolated 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 heat supplied to the system and T is the absolute

temperature of the system.

9-FUNCTIONING OF THERMAL POWER PLANT

In a thermal power plant, one of coal, oil or natural gas is used to heat the boiler to convert the

water into steam. The steam is used to turn a turbine, which is connected to a generator. When

the turbine turns, electricity is generated and given as output by the generator, which is then

supplied to the consumers through high-voltage power lines.

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10-INPUTS OF THERMAL POWER PLANT

1. Boiler steam drum

2. Bottom ash hopper

3. Steam Control valve

4. Super heater

5. Transmission line (3-phase)

6. Deaerator

7. Reheater

8. Economizer

9. Flue gas stack

10.Surface condenser

11.Combustion air intake

11-ELEMENTS OF THERMAL POWER STATION

11.1-D.M. Plant

For the generation of steam De-mineralize water prepared removing minerals & impurities

to remove the minerals several chemicals are used.

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11.2-DEAERATOR

Deaerator is placed at the height of 26 m to provide the appropriatesuction pressure for

boiler feed pump. The main function of deaerator is:-

1. To remove the air bubbles from the water entered into boiler feed pump.

2. To provide the suction head to the boiler feed pump.

11.3-Boiler feed pump

Boiler feed pump pumps the water coming from deaerator to the H.P. heater. Boiler feed

pump consists of a motor coupled with the pump through hydraulic coupling. On passing

through the boiler feed pump the pressure of the water becomes about ten times of the suction

pressure.

11.4-Economizer

It consists of a large number of closely spaced parallel tubes of thin walls and smaller

diameter. The feed water is passed through the economizer before supplying it to boiler. The heat

of flue gases which would be lost is used to raise the temperature of the feed water due to which

the efficiency of the boiler increases.

11.5-Air Pre-Heater

In the second path of flue gases, just below the economizer Air pre-heater is

placed. It raise the temperature of the atmospheric air, coming from the PA and FD

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fans , for the dryness of the coal which confirms the proper combustion of coal used.

To raise the temperature of the air heat of flue gases is used , hence the efficiency of

the plant is increased.

11.6-Boiler

Boiler is used for the generation of steam from the feed water. After passing through

economizer feed water enters into the boiler drum. From drum, with the help of down commers it

enters into the water walls where the heat coming from the furnace converts water into the steam.

A boiler (or steam generator) is a closed vessel in which water, under pressure is converted into

steam. It is one of the major components of a thermal power plant. A boiler is always designed to

absorb maximum amount of heat released in process of combustion. This is transferred to the

boiler by all the three modes of heat transfer i.e. conduction, convection and radiation.

12-Boilers are classified as:-

12.1-Fire tube boiler:-

In this type the products of combustion pass through the tubes which are surrounded by water.

These are economical for low pressure only.

12.2-Water tube boiler:-

In this type of boiler water flows inside the tubes and hot gases flow outside the tubes. These

tubes are interconnected to common water channels and to steam outlet.

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g to rapid and uniform circulation of water in tubes.

12.3-BOILER DRUM

The drum is a pressure vessel. Its function is to separate water and steam from mixture (of steam

& water) generated in the furnace walls. It provides water storage for preventing the saturation of

tubes. It also houses the equipment needed for purification of steam. The steam purification

primarily depends on the extent of moisture removal, since solids in steam are carried by the

moisture associated with it. The drum internals reduce the dissolved solids content of the steam

to below the acceptable limit. drum is made up of two halves of carbon steel plates having

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thickness of 133 mm. The top half and bottom half are heated in a plate heating furnace at a very

high temperature and are pressured to form a semi cylindrical shape. The top and bottom semi

cylinders with hemispherical dished ends are fusion welded to form the boiler drum. The drum is

provided with stubs for welding all the connecting tubes i.e. down comer stubs, riser tubes stubs

and super-heater outlet tube stubs. Boiler drum is located at a height of 53m from ground. The

drum is provided with manholes and manhole covers. Manhole is used for facilitating the

maintenance person to go inside the drum for maintenance.

12.4-TECHNICAL SPECIFICATION OF BOILER

1. Type: Direct fired, natural circulation

2. No. of Units. : Two.

3. Make: BHEL.

4. Capacity. : 375 tonnes per hour.

5. Steam Pressure. : 139 Kg. /Cm2

6. Efficiency: 86.6 %.

12.4.1-Steam Drum

The drum form the part of boiler circulating system i.e. movement of fluid from the drum

to the combustion zone and back to boiler drum. Feed water is supplied to the drum from

the economizer through feed nozzles. Water from the drum goes to water walls through

six down comers.

Main parts of boiler drum are:-

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12.4.2-Super heater

A number of super heaters are used to make a super- heat steam coming from the boiler

drum. There are ten super heaters, one de-super heat one Platon and a final super heater to

convert the wet steam into the super heated steam. Heat of flue gases is used to dry the wet

steam.

12.4.3-Turbine

Turbine converts the heat energy of the steam into mechanical energy. The super

heated steam works on the blades of the turbine and hence the blades starts rotating to

produce the mechanical energy . The mechanical energy then converted into the electrical

energy with the help of generator. A series of three turbines is used to convert the heat energy

into mechanical energy.

1) High pressure turbine

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2) Intermediate Pressure turbine

3) Low pressure turbine

12.4.4-Condenser

The function of condenser is to create suction at very low pressure to the exhaust of

turbine thereby it permits the expansion of steam in primary to a very low pressure. The exhaust

steam is condensed in the condenser and then again fed into the boiler.

13-SUPER HEATER

Superheated steam is that steam, which contains more heat than the saturated Steam at the same

pressure i.e. it, has been heated above the temperature corresponding to its pressure. This

additional heat provides more energy to the turbine and thus the electrical power output is more.

A super heater is a device which removes the last traces of moisture from the saturated steam

leaving the boiler tubes and also increases its temperature above the saturation temperature.

The steam is superheated to the highest economical temperature not only to increase the

efficiency but also to have following advantages

high internal energy reduces the turbine size.

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resistance to the flow of steam over them is small resulting in high efficiency.

14-RE-HEATER

Re-heaters are provided to raise the temperature of the steam from which part of energy has

already been extracted by HP turbine. This is done so that the steam remains dry as far as

possible through the last stage of the turbine. A re-heater can also be convection, radiation or

combination of both.

15-CIRCULATION SYSTEM

In natural circulation system, water delivered to steam generator from header, which are at a

temperature well below the saturation value corresponding to that pressure. After header, it is

delivered to economizer, which heated to above the saturation temperature. From economizer the

water enters the drum and thus joins the circulation system through down covering water wall

tubes. In water wall tubes a part of the water is converted to steam due to boiler and the mixture

flows back to the drum. In the drum, the steam is separated out through the steam separators and

passed to the super heater. After the super heater when the steam temperature becomes high and

pressure upto 150 Kg./cm3 steam is allowed to enter the turbine to convert potential energy to

kinetic energy.

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16-WORKING PRINCIPLE

A gas turbine, also called a combustion turbine, is a rotary engine that extracts energy from a

flow of combustion gas. It has an upstream compressor coupled to a downstream turbine, and a

combustion chamber in-between. Energy is added to the gas stream in the combustion chamber,

where air is mixed with fuel and ignited. Combustion increases the temperature, velocity and

volume of the gas flow. This is directed through a nozzle over the turbines blades, spinning the

turbine and powering the compressor. Energy is extracted in the form of shaft power,

compressed air and thrust, in any combination, and used to power aircraft, trains, ships,

generators, and even tanks.

The thermodynamic cycle upon which all gas turbines operate is called the Brayton cycle. The

Figure below shows the classical pressure-volume (PV) and temperature entropy (PS) diagrams

for this cycle.

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Here, path 1 to 2 represents the compression occurring in the compressor, path 2 to 3 represents

the constant-pressure addition of heat in the combustion systems, and path 3 to 4 represents the

expansion occurring in the turbine. The path from 4 back to 1 on the cycle diagrams is indicative

of a constant-cooling process.

GAS TURBINES IN IOCL, DIGBOI

IOCL, Digboi has four gas turbines which generates electricity with three of them having a

capacity of 8.5 MW and one 20 MW generator, the total capacity being 44.5 MW. Each of the

three 8.5 MW unit is accompanied by 3 HRSG (Heat Recovery steam Generator) of capacity

37.5 TPH and the 20 MW unit is accompanied by 1 HRSG of capacity 100 TPH.

When the exhaust from the turbines are recycled with the help of the HRSG unit, the cycle

followed by the gas turbine is known as co-gen Cycle and when the exhaust is directly released

into the atmosphere, the cycle of the turbine is known as Simple Cycle. The cycle which is used

mostly in IOCL, Digboi is the Co-gen Cycle.

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CALCULATION

Energy efficiency

During energy transformations, energy can neither be created nor destroyed. However energy

can be degraded, that is there is less useful energy after the change than there was before. This is

because some of the original energy has been changed into heat or sound and lost to the

surroundings.

General and credit level equations

Useful equations for energy calculations in power stations include:

gravitational potential: Ep = mgh

kinetic energy: Ek mv2(credit level only)

electrical power: P=IV

also, for all forms of energy: E=Pt

Calculating efficiency (credit level only)

The percentage of total energy output compared to the total input energy is its energy efficiency

PROCESS: THARMAL TO ELECTRICITY

We will see how the whole process of generation of electricity from the initial stage i.e. when

coal burns. For burning the coal we require three

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4. The pump to send back condensed water to boiler

Now let us have close look of the working of each equipments of thermal power plant.

1. Feed water enters the boiler at the high pressure and low temperature and it is converted

into high pressure and high temperature. Steam in the boiler. The heat required to convert

feed water to steam is obtained from the heat released from the combustion of fuels

burned in the furnace.

2. High pressure and high temperature steam from the boiler passes through the turbine

blades and expands from boiler pressure, to the condenser pressure. The work performed

in this process is transmitted through the shaft to the shaft of the electric generator, where

the mechanical energy is converted to electrical energy.

3. The low pressure and low temperature exhaust steam from turbine is condensed into

water in a condenser. The heat removal for condensation is done by cooling water

through circulating water pumps.

4. The condensate from the condenser is pumped, by the boiler feed pump (B.F.P) as high

pressure and low temperature water which is feed to boiler.

5. And this cycle goes on.

The following medium for thermal power plant cycle is steam and before we go into the details

of the steam power cycle, we should know about steam.

The use of steam can be traced back as far 56 AD when it provided the mysterious-motive-power

of Greek temple after the sacred fires had been lit. It may have been used even earlier for the

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same purpose by Egyptians but it was not until 1712 that any development of an industrial nature

took place.

In those pioneer days of boiler development the life of an operator was not without dangers

because explosions were frequent.

This led to the development of steam generators and also the establishment of the excellent codes

of safety which we know today.

We used coals as fuel for the generation of heat energy. As the water in the Boiler evaporated

due to the intense heat, it becomes high-pressurized steams.

And the steams are passing through a conduit (there is a turbine at the other end of the tunnel), it

forces its way through the Turbine, thus rotating the Turbine. (As the steams are high-

pressurized, the Turbine will rotate very fast.)

The Turbine is connected to a Generator via a coupler. As the Turbine is rotating (from the force

of the steams), electrical energy is being produced.

After the steams have passed through the turbine, it enters a Condenser. The Condenser has got a

cooling agent (namely seawater) and the steam will go through the cooling agent via a pipe. The

steam thus changes back to its liquid form and returns to the Boiler.

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Diagram of the Basic Operation of a Thermal Power Station

METHODOLOGY

STARTING SYSTEM

Before the gas turbine can be fired and staged it must be rotated or cranked by accessory

equipment to obtain a sustainable speed. This is accomplished by a diesel engine operating

through a torque converter to provide the power required by the turbine for startup. Once it

reaches the sustainable speed the gas turbine is driven through the accessory gear by the diesel

engine, torque converter output gear and the starting clutch.

INLET AIR SYSTEM

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Gas turbine performance and reliability is a function of the quality and cleanliness of the inlet air

entering the turbine. Therefore, for most efficient operation, it is necessary to treat the

atmospheric air entering the turbine and filter out contaminants. It is the function of the air inlet

system its specially designed equipment and ducting to modify the quality of the air under

various temperature, humidity and contamination situations and make it more suitable for use in

the unit. This system combines the functions of filtering and silencing the inlet air with the

function of directing the air into the turbine compressor. This system basically includes self

cleaning air filters which including the job of filtering the air cleans itself after a fixed interval of

time.

COMPRESSOR SECTION

In the compressor, air is confined to the space between the rotor and stator where it is

compressed in stages by an alternate series of rotating (rotor) and stationary (stator) airfoil

shaped blades. Rotor blades supply the force needed to compress the air in each stage and the

stator blades guide the air so that it enters the following rotor stage at the proper angle. The

compressed air exits through the compressor discharge casing to the combustion chambers. Air is

also extracted from the compressor for turbine cooling and for bearing in the lube oil extracted

from the compressor for turbine cooling and for bearing in the lube oil sealing.

COMBUSTION SECTION

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The combustion section consists of combustion chambers, fuel nozzles, crossfire tubes and

transition pieces. Air for combustion is supplied directly from the axial- flow compressor to the

combustion chambers. This arrangement is called a reverse flow system. Each combustion

chamber is equipped with a fuel nozzle that introduces fuel into the combustion liner. Gaseous

fuel is admitted directly into each chamber through metering holes. When liquid fuel is used, it is

atomized in the nozzle swirl chamber by means of high-pressure air.

The combustion chambers are interconnected by means of crossfire tubes. These tubes enable

flame from the fired chambers containing spark plugs to propagate to the unfired chambers

during startup. Combustion of the fuel and air mixture is initiated by spark plugs with retracting

electrodes. The spark plugs are installed in two of the combustion chambers.

During operation, it is essential that an indication of the presence or absence of flame be

transmitted to the control system. For this reason, a flame monitoring system is used control

system. For this reason, a flame a flame monitoring system is used consisting of multiple

sensors, which are installed on combustion chamber. The ultraviolet flame sensor consists of a

flame sensor containing a gas-filled detector. The gas within this flame sensor detector is

sensitive to the presence of ultraviolet radiation, which is emitted by a hydrocarbon flame.

TURBINE SECTION:

The hot gases from the combustion chambers flow through separate transition pieces. The gases

then enter the two stage turbine section of the machine. Both stages consist of a row of fixed

nozzles followed by a row of rotating turbine buckets. In each nozzle row, the kinetic energy of

the jet is increased, with an associated pressure drop in the following row of moving buckets: a

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portion of the kinetic energy of the jet is absorbed as useful work on the turbine rotor. After

passing through the 2nd stage buckets, the gases are directed into the exhaust hood and diffuser,

which contain a series of turning

Vanes to turn the gases from an axial direction to a radial direction to minimize exhaust losses.

The gases then pass into the exhaust plenum and are introduced to atmosphere through the

exhaust stack. Resultant shaft rotation is used either to turn a Generator rotor for electrical power

production, or to drive a centrifugal compressor in industrial process application.

EXHAUST SYSTEM

Hot exhaust gases produced as result of combustion in the turbine are cooled and attenuated in

the exhaust system ducting before being released to atmosphere. These exhaust emissions must

meet certain environmental standards of cleanliness and acoustic levels depending on site

location. The noise generated during gas turbine operation is attenuated by means of absorptive

silencing material and devices built into the inlet and exhaust sections which dissipate or reduce

the acoustical energy to an acceptable level.

WORKING PRINCIPLE

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A schematic diagram for a simple-cycle, single shaft gas turbine which is used in the 20 MW

units is shown in the figure below:

STEPS:

Air enters the axial flow compressor at point 1. Air entering the compressor at point 1 is

compressed to some higher pressure which raises the air temperature so that the air at the

discharge of the compressor is at a higher temperature and pressure.

Upon leaving the compressor, air enters the combustion system at point 2 where fuel is

injected and combustion occurs. The combustion process occurs at essentially constant

pressure.

When the combustion mixture leaves the combustion system and enters the turbine at point 3.

it is at a mixed average temperature. In the turbine section of the gas turbine, the energy of

the hot gases is converted into work. This conversion actually takes place in two steps. In the

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nozzle section of the turbine the hot gases are expanded and a portion of the thermal energy

is converted into kinetic energy. in the subsequent bucket section of the turbine, a portion of

the kinetic energy is transferred to the rotating buckets and converted to work. Some of the

work developed by the turbine is used to drive the compressor, and the remainder is available

for useful work at the output flange of the gas turbine. As shown in figure above, single-shaft

gas turbines are configured in one continuous shaft and therefore all stages operate at the

same speed. These units are typically used for generator-drive applications where significant

speed variation is not required.

A schematic diagram for a simple-cycle, dual shaft gas turbine used in the three 8.5 MW units is

shown in the Figure below:

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Here, the low-pressure or power turbine rotor is mechanically separate from the high pressure

turbine and compressor rotor. This unique feature allows the power turbine to be operated at a

range of speeds and makes two-shaft gas turbines ideally suited for variable speed applications.

All of the work developed by the power turbine is available to drive the load equipment since the

work developed by the high-pressure turbine supplies all the necessary energy to drive the

compressor. The starting requirements for the gas turbine load train are reduced because the load

equipment is mechanically separate from the high- pressure turbine.

ELECTRO-STATIC PRECIPITATOR

SCOPE & PRINCIPLE OF OPERATION

For general mankind, today an Eco friendly industry is must. As far as air pollution is concerned

now a days various flue gases filter are there in service. The choice depends on the size of

suspended particle matter. These filters are E.S.P. Fabric filter high efficiency cyclone

separations and sitelling room. Fop fly ash , where the particle size vary from 0.75 microns to

100 micron use gradually use E.S.P. to purify the flue gases due to its higher efficiency & low

running cost etc. In an ESP the dust lidder gas is passed through an intense electric field, which

causes ionization of the gases & they changed into ion while traveling towards opposite charged

electrode get deposited as particles and thus dust is electric deposited an electrode creating the

field. It is continuous process.

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CONTROLLER

Now a day micro-processor based intelligent controllers are used to regulate the power fed to the

HVR. The controls the firing / ignition angle of the thyristor connected in parallel mode. Input

out waves of the controller and HVR are also shown above, which clearly indicates that average

power fed to ESP field can be controlled by variation of the firing angle of thyristor. The output

of controller with respect to time is also controlled by microprocessor, so that ESP operation is

smooth and efficient. The chars are as shown: As can be seen in the event of spark between

electrodes the output of controller is reduced to zero for few millisecond for quenching the spark.

Controller also takes place care of fault in KVR and gives a trapping and non-trapping alarm as

per the nature of fault.

DETAILED PROCESS OF POWER GENERATION IN A THERMAL

POWER PLANT

Water intake: Firstly, water is taken into the boiler through a water source. If water is available

in a plenty in the region, then the source is an open pond or river. If water is scarce, then it is

recycled and the same water is used over and over again.

Boiler heating: The boiler is heated with the help of oil, coal or natural gas. A furnace is used to

heat the fuel and supply the heat produced to the boiler. The increase in temperature helps in the

transformation of water into steam.

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Steam Turbine: The steam generated in the boiler is sent through a steam turbine. The turbine

has blades that rotate when high velocity steam flows across them. This rotation of turbine blades

is used to generate electricity.

Generator: A generator is connected to the steam turbine. When the turbine rotates, the generator

produces electricity which is then passed on to the power distribution systems.

Special mountings: There is some other equipment like the economizer and air pre-heater. An

economizer uses the heat from the exhaust gases to heat the feed water. An air pre-heater heats

the air sent into the combustion chamber to improve the efficiency of the combustion process.

Ash collection system: There is a separate residue and ash collection system in place to collect

all the waste materials from the combustion process and to prevent them from escaping into the

atmosphere. Apart from this, there are various other monitoring systems and instruments in place

to keep track of the functioning of all the devices. This prevents any hazards from taking place in

the plant.

The second law of thermodynamics states that any closed-loop cycle can only convert a fraction

of the heat produced during combustion into mechanical work. The rest of the heat, called waste

heat, must be released into a cooler environment during the return portion of the cycle. The

fraction of heat released into a cooler medium must be equal or larger than the ratio of absolute

temperatures of the cooling system (environment) and the heat source (combustion furnace).

Raising the furnace temperature improves the efficiency but also increases the steam pressure,

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complicates the design and makes the furnace more expensive. The waste heat cannot be

converted into mechanical energy without an even cooler cooling system. However, it may be

used in cogeneration plants to heat buildings, produce hot water, or to heat materials on an

industrial scale, such as in some oil refineries, cement plants, and chemical synthesis plants.

Typical thermal efficiency for electrical generators in the electricity industry is around 33% for

coal and oil-fired plants, and up to 50% for combined-cycle gas-fired plants.

HOW ELECTRICITY IS GENERATED?

The complete and complex process of electricity generation in TPS can be divided into four

major cycles for the sake of simplicity. The main systems are discussed in these cycles in a step

by step manner and some useful drawings are also enclosed. The four cycles are

1. Coal Cycle

2. Oil Cycle

3. Air and Flue Gas Cycle

4.Steam Water Cycle

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COAL CYCLE

The simplest of the above four cycles is the coal cycle. In this cycle as explained earlier crushed

coal of about 20mm is transported by conveyor belts to the coal mill bunkers. From here the coal

goes to coal mills through raw coal feeders. In the coal mills the coal is further pulverized

(crushed) to powder form. The temperature of the coal mills are maintained at 180-200 degree

centigrade by a suitable mixture of hot & cold air.

The air comes from Primary Air fans (P.A FANS) which are 2 in Nos. - A&B. The outlet duct

after combining gets divided into two. One duct goes to the Air Heaters (A.H- A&B) where

primary air is heated by the hot flue gases in a Heat Exchanger. This duct provides hot air & the

other one provides cold primary air. A suitable mixture of this hot & cold air is fed to the coal

mills to maintain their temperature. This is done to remove moisture of coal. More over this

primary air is also used for transportation of powdered coal from coal mills to the four corners of

the boiler by a set of four pipes. There are six coal mills A, B, C, D, E&F and their outlets in

the Boiler are at different elevations. The high

Temperature of the primary air does not allow the air coal mixture to choke the duct from mill to

boilers. A portion of the primary air is further pumped to high pressure and is known as seal air.

It is used to protect certain parts of mills like bearings etc. where powered coal may pose certain

problems in the functioning of the mill. When the air coal mixture enters the boiler it catches fire

in the firing zone and some ash along with clinkers settles down. This is removed periodically by

mixing it with water to make slurry.

OIL CYCLE

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In the oil cycle the oil is pumped and enters the boiler from four corners at three elevations. Oil

guns are used which sprays the oil in atomized form along with steam so that it catches fire

instantly. At each elevation and each corner there are separate igniters which ignite the fuel oil.

There are flame sensors which sense the flame and send the information to the control roam.

AIR & FLUE GAS CYCLE

For the proper combustion to take place in the boiler right amount of Oxygen or air is needed in

the boiler. The air is provided to the furnace in two ways - Primary Air & Secondary Air.

Primary air is provided by P.A. fans and enters the boiler along with powdered coal from the

mills. While the secondary air is pumped through Forced Draft fans better known as F.D Fans

which are also two in numbers A&B. The outlet of F.D fans combine and are again divided into

two which goes to Steam coiled Air pre heaters (S.C.A.P.H) A&B where its temperature is raised

by utilizing the heat of waste steam. Then it goes to Air Pre heater-A&B where secondary air is

heated further utilizing the heat of flue gases. The temperature of air is raised to improve the

efficiency of the unit & for proper combustion in the furnace. Then this air is fed to the furnace.

From the combustion chamber the fuel gases travel to the upper portion of the boiler and give a

portion of heat to the Platen Super Heater. Further up it comes in contact with the Reheater and

heats the steam which is inside the tubes of reheater. Then it travels horizontally and comes in

contact with Final Super Heater. After imparting the heat to the steam in super heater flue gases

go downward to the Economizer to heat the cold water pumped by the Boiler Feed Pumps

(B.F.P.) these all are enclosed in the furnace. After leaving the furnace the fuel gases go to the

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Air Heaters where more heat of the flue gases is extracted to heat primary and secondary air.

Then it goes to the Electrostatic Precipitators (E.S.P.) Stage A&B where the suspended ash from

the flue gases is removed by passing the fuel gas between charged plates. Then comes the

induced draft fan (I.D Fan) which sucks air from E.S.P. and releases it to the atmosphere through

chimney. The pressure inside the boiler is kept suitably below the atmospheric pressure with the

help of 1.0. Fans so that the flame does not spread out of the openings of boiler and cause

explosion. Further very low pressure in the boiler is also not desirable because it will lead to the

quenching of flame.

STEAM WATER CYCLE

The most complex of all the cycles is the steam & water cycle. Steam is the working substance in

the turbines in all the thermal and nuclear power plants. As there is very high temperature and

pressure inside the boiler, initially water has to be pumped to a very high pressure. Water has

also to be heated to a suitably high temperature before putting it inside the boiler so that cold

water does not cause any problem. Initially cold water is slightly heated in low pressure heaters.

Then it is pumped to a very high pressure of about 200 Kg/Cm2 by boiler feed pumps A & B.

After this it is further heated in high pressure heaters by taking the heat from the high pressure

steam coming from various auxiliaries and / or turbines. Then this water goes to the economizer

where its temperature is further raised by the flue gases.

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This hot water then goes to the boiler drum. In the boiler drum there is very high temperature and

pressure. It contains a saturated mixture of boiling water and steam which are in equilibrium.

The water level in the boiler is maintained between certain limit. From here relatively cold water

goes down to the water header situated at the bottom, due to difference in density. Then this cold

water rises gradually in the tubes of the boiler on being heated. The tubes are in the form of

water walls. These tubes combine at the top in the hot water header. From here the hot water and

steam mixture comes back to the boiler drum completing the small loop.

From the boiler drum hot steam goes to platen super heater situated in the upper portion of the

boiler. Here the temperature of the steam is increased. Then it goes to final super heater. Here its

temperature is further increased.

The turbine is a three cylinder machine with high pressure (H.P), intermediate pressure (I.P) &

low pressure (L.P) casings taking efficiency into account the .The turbine speed is controlled by

hydro dynamic governing system. The three turbines are on the same shaft which is coupled with

generator. The generator is equipped with D.C excitation system. The steam from the final super

heater comes by main steam line to the H.P turbine. After doing work in the H.P turbine its

temperature is reduced. It is sent back to the boiler by cold reheat line to the reheater. Here its

temperature is increased and is sent to the I.P turbine through hot reheat line. After doing work in

the I.P turbine steam directly enters L.P turbine.

The pressure of L.P turbine is maintained very low in order to reduce the condensation point of

steam. The outlet of L.P turbine is connected with condenser. In the condenser, arrangement is

made to cool the steam to water. This is done by using cold water which is made to flow in tubes.

This secondary water which is not very pure gains heat from steam & becomes hot. This

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secondary water is sent to the cooling towers to cool it down so that it may be reused for cooling.

The water thus formed in the condenser is sucked by condensate water pumps (C.W. PUMPS)

and is sent to deaerator. A suitable water level is maintained in the hot well of condenser.

Water or steam leakages from the system are compensated by the make up water, line from

storage tanks which are connected to the condenser. The pressure in side condenser is

automatically maintained less then atmospheric pressure and large volume of steam condense

here to form small volume of water. In the deaerator the water is sprayed to small droplets & the

air dissolved in it is removed so that it may not cause trouble at high temperatures in the Boiler.

Moreover, the water level which is maintained constant in the deaerator also acts as a constant

water head for the boiler feed pumps. Water from deaerator goes to the Boiler feed pumps after

the heated by L.P. Heaters. Thus the water cycle in the boiler is completed and water is ready for

another new cycle. This is a continuous and repetitive process.

ADVANTAGES

1.The fuel used is quite cheap.

2. Less initial cost as compared to other generating plants.

3. It can be installed at any place irrespective of the existence of coal. The coal can be

transported to the site of the plant by rail or road.

4. It requires less space as compared to Hydro power plants.

5. Cost of generation is less than that of diesel power plants.

6.This plants can be quickly installed and commissioned and can be loaded when compare to

hydel power plant

7.It can meet sudden changes in the load without much difficulty controlling operation to

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increase steam generation

8.Coal is less costlier than diesel

9.Maintenance and lubrication cost is lower

DISADVANTAGES

1. It pollutes the atmosphere due to production of large amount of smoke and fumes.

2.It is costlier in running cost as compared to Hydro electric plants.

3.Well, stations always take up room for the environment which could be cultivated for the

use of growing food etc. which is a great disadvantage is our day and age, as food is

necessary to live.

4.However, this could create more jobs for a lot of people thus increasing in a good way our

5.current economic situation which by is failing miserably.

6.Over all capital investment is very high on account of turbines, condensers, boilers

reheaters etc .maintenance cost is also high on lubrication, fuel handling, fuel processing.

7.It requires comparatively more space and more skilled operating staff as the operations are

complex and required precise execution

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8.A large number of circuits make the design complex

9.Starting of a thermal power plant takes fairly long time as the boiler operation and steam

generation process are not rapid and instantaneous.

FUTURE PROSPECTS

Effective Use of Fossil Fuels and Reduction in CO2 Emissions by Improving the Efficiency of

Thermal Power Generation At present, thermal power generation accounts for approximately

70% of the total amount of electricity produced around the world. However, thermal power

generation, which uses fossil fuels, causes more CO2 emissions than other power generation

methods. In order to reduce CO2emissions per unit power produced, Toshiba Group is

enveloping next-generation thermal power technologies aimed at improving plant efficiency and

commercializing the CCS*1 (CO2 capture and storage) system.

To improve the efficiency of thermal power generation, it is of vital importance that the

temperature of the steam or gas used to rotate the turbines is raised. Toshiba Group is working on

the development of ultra-high-temperature materials and cooling technologies in order to

commercialize an A-USC*2 system (Advanced Ultra-Super Critical steam turbine system) more

efficient than previous models, which is designed to increase steam temperature from 600C

to above the 700C mark. In the area of combined cycle power generation using a

combination of gas and steam turbines, we are also engaged in jointly developing a power

generation system designed to increase gas temperature to the level of 1,500C with the U.S.

Company General Electric, which is starting commercial operation in July 2008 in Japan.

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Accelerating the Development of CO2 Capture and Storage technology the Key to Realizing

Next-generation Power Generation System Toshiba Group is engaged in the development of

CO2 capture and storage (CCS) technology designed to separate and capture CO2 emitted from

thermal power plants and other such facilities and then store it underground. More specifically,

this development is aimed at commercializing CCS technology. In order to commercialize this

technology, it is essential that we develop a system that makes it possible to separate and capture

CO2 without reducing the economic performance of a power plant. In the course of its basic

research, Toshiba Group has developed a high-performance absorbent that minimizes the energy

consumption required for the CO2 capture process. Experiments conducted using small-scale test

equipment has confirmed that its level of performance is the best in the industry.

Preventive Maintenance Technologies That Support the Long-term, Stable Operation of

Facilities and Extension of the Service Life of High-temperature Gas Turbine Parts

The use of combined cycle power generation facilities using gas turbines is increasing year by

year for the purpose of achieving the reduction in CO2 emissions required to create a low-carbon

society, increasing energy use efficiency and improving economic performance. Toshiba Group

is developing various technologies that support the long-term, stable operation of facilities.

In order to analyze and assess high-temperature gas turbine parts, which are used in harsh

environments and to determine their remaining service lives based on the level of degradation,

we developed a technology for making highly accurate diagnoses by combining a number of

methods, including the finite element method (FEM) and methods for testing cleavage strength,

tensile strength, durability and fatigue strength. We are also working to commercialize service

life extension and repair technologies aimed at recycling gas turbine rotor/stator blades and

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extending their service lives. Based on the BLE (Blade Life Extension) concept unique to

our company group, we repeatedly reuse old rotor blades that meet our repair standards instead

of simply discarding them. The repair and recycling of these parts not only reduces running costs

and improves economic performance, but also effectively minimize the environmental impact.

OVERVIEW OF THERMAL POWER PLANT

A typical Thermal Power Plant Operates on a Cycle which is shown below.

A typical Thermal Power Plant Operates on a Cycle

The working fluid is water and steam. This is called feed water and steam cycle. The ideal

Thermodynamic Cycle to which the operation of a Thermal Power Station closely resembles is

the RANKINE CYCLE.

InSteam boilerthe water is heated up by burning the fuel in air in the furnace & the function of

the boiler is to give dry super heated steam at required temperature.

The steam so produced is used in driving the Steam Turbines. This turbine is coupled

tosynchronous generator(usually three phase synchronous alternator), which generates electrical

energy.

The exhaust steam from the turbine is allowed to condense into water in steam condenser of

turbine,which creates suction at very low pressure and allows the expansion of the steam in the

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turbine to a very low pressure. The principle advantages of condensing operation are the

increased amount of energy extracted per kg of steam and thereby increasing efficiency and the

condensate which is fed into the boiler again reduces the amount of fresh feed water.

The condensate along with some fresh make up feed water is again fed into the boiler by pump

(called the boiler feed pump).

In condenser the steam is condensed by cooling water. Cooling water recycles through cooling

tower. This constitutes cooling water circuit.

The ambient air is allowed to enter in the boiler after dust filtration. Also the flue gas comes out

of the boiler and exhausted into atmosphere through stacks. These constitute air and flue gas

circuit. The flow of air and also the static pressure inside thesteam boiler(called draught) is

maintained by two fans called Forced Draught (FD)fan and Induced Draught (ID)fan.

The total scheme of a typical thermal power station along with different circuits is illustrated

below.

Inside the boiler there are various heat exchangers, viz.Economiser, Evaporator (not shownin the fig above, it is basically the water tubes, i.e. down comer riser circuit), Super Heater(sometimes Reheater, air preheater arealso present).

In Economiser the feed water is heated to considerable amount by the remaining heat of flue gas.

The Boiler Drum actually maintains a head for natural circulation of two phase mixture (steam +

water) through the water tubes.

There is also Super Heater which also takes heat from flue gas and raises the temperature of

steam as per requirement.

PROTECTION

1. Field Protection.

2. Pole Slipping.

3. Plane Overload Protection.

4. Inter-turn Fault

5. Negative Phase Sequence Protection.

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6. Reverse Power Protection.

7. Forward Power Protection.

8. under Frequency & Over Frequency Protection.

9. Generator Voltage Protection.

REFERENCES

-thermal-power-plant.html

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

BOOKS

Electrical Power by J.B.Gupta

Generation of Electrical Power by B.R.Gupta

Power System by V.K.Mehta.

Power System Design & Analysis by B.R.Gupta

Steam & Gas turbines and Power Plant Engineering by R.Yadav.