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Submitted in the partial fulfillment of the requirement for the award of thecertificate

for

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About NTPC

NTPC, the largest power Company in India, wassetup in 1975 to accelerate power developmentin the country.

NTPC has installed capacity of 29,394 MW. It has 15 coal based power stations (23,395 MW) 7 gas based power stations (3,955 MW) 4 power stations in Joint Ventures (1,794 MW).

The company has power generating facilities inall major regions of the country. It plans to be a 75,000 MW company by 2017.

http://www.ntpc.co.in/cms/index.php?page=Installed-Capacityhttp://www.ntpc.co.in/cms/index.php?page=Installed-Capacity

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Generation of Electricity

Prime mover coupled toAlternator

Prime mover is driven byenergy obtained from various

sources such as burning of fuel pressure of water Force of wind etc .

Fig. Fundamental of generation of Electricity

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Thermal Power Plant A generating station which converts heat energy of coal combustion

into electrical energy is known as a steam power station.

Steam is produced in the boiler by utilizing the heat of coalcombustion. The steam is then expanded in the steam turbine and iscondensed in a condenser to be fed into the boiler again. The steamturbine drives the alternator which converts mechanical energy of theturbine into electrical energy.

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WORKING OF STEAM POWERPLANT

Coal is burnt in a boiler ,which converts water into steam. The steam is expanded in a turbine used to drive alternator. The steam expanded is condensed in a condenser to be feed into the

boiler again. The entire arrangement of steam power plant can be divided into :

a. fuel and ash plant.b. air and fuel gas plant.c. feed water and steam plant.d. cooling water plant.

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The most important constituents of a steam power stationare:

a. Steam generating equipmentb. Condenser c. Prime mover d. Cooling towerse. Electrical equipment

Steam generating equipment includes:

Boiler Boiler furnace Superheater Economiser Air Pre-heater

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Boiler A boiler is closed vessel in which water is converted into steam byutilising the heat of coal combustion.

Steam boilers are broadly classified into following two types:(a) Water tube boilers (b) Fire tube boilers

In a water tube boiler , water flows through the tubes and the hot gases

of combustion flow over these tubes. Water-tube boilers are used for high-pressure boilers

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In a fire tube boiler , the hot products of combustion pass through thetubes surrounded by water.

The heated water then rises into the steam drum. Here, saturatedsteam is drawn off the top of the drum. The steam will reenter thefurnace in through a superheater in order to become superheated.Superheated steam is used in driving turbines. Since water droplets canseverely damage turbine blades, steam is superheated to 730F(390C) or higher in order to ensure that there is no water entrained in

the steam.

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Super heater

A device which removes last traces of moisture.

It helps in reduction in requirement of steam quantity. steam being dry reduces the mechanical

resistance of turbine. No corrosion at the turbine blades.

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Economiser and Air Pre-heater

They are such devices which recover theheat from the flue gases on their way tochimney and raise the temperature of feedwater.

Economiser raises boiler efficiency. Air Pre-heaters recover the heat from the

flue gases leaving the economiser andheat the incoming air required for combustion

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Condenser

Which condenses the steam at the exhaust of turbine.

It creates a very low pressure at the exhaust of

turbine, this helps in converting heat energy of steam into mechanical energy in the primemover.

The condensed steam can be used as feed

water to the boiler.

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Prime Mover (i.e. Turbine) A steam turbine is a mechanical device that extracts thermal energyfrom pressurized steam, and converts it into mechanical energy.

About 86% of all electric generation in the world is by use of steamturbines.It has almost completely replaced the reciprocating piston steamengine.

BOILER GENERATOR

STEAM TURBINE

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Cooling Towers

Remove heat from thewater discharged fromthe condenser so that the

water can be dischargedto the river or recirculated and reused.

Air can be circulated inthe cooling towers

through natural draft andmechanical draft.

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Electrical EquipmentsAlternator

An alternator is coupled to a steam turbine and converts mechanicalenergy of the turbine into electrical energy.It may be hydrogen or air cooled.The necessary excitation is provided by means of main and pilot excitersdirectly coupled to the alternator shaft.

Transformers(a) main step-transformers, which steps-up generated voltagetransmission of power (b) station transformers, general purpose(c) auxiliary transformers, which supply to individual unit-auxiliaries.Switchgearwhich locates fault on the system and isolate faulty part from healthysection.It contains circuit breakers, relays, switches and other control devices.

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Coal Handling Plant Details Source of coal = Northern Coalfield Limited, Nigahi(M.P.)

Location = Near Singrauli

Distance = 100 Kms.

Type of coal = F-grade (Washed) E grade (Raw) Coal requirement = 13,000 MT/Day ( 04 rakes )

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Ash Handling Technique

A natural result from the burning of fossil fuels,particularly coal, is the emission of flyash. Ash is mineralmatter present in the fuel. For a pulverized coal unit, 60-80% of ash leaves with the flue gas.

Two emission control devices for flyash are the fabricfilters and electrostatic precipitators.

Electrostatic precipitators have collection efficiency of 99%, but do not work well for flyash with a high electricalresistivity (as commonly results from combustion of low-sulfur coal). In addition, the designer must avoidallowing unburned gas to enter the electrostatic

precipitator since the gas could be ignited.

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Top View of ESP Schematic Diagram

The fluegas laden with flyash is sent through pipes having negativelycharged plates which give the particles a negative charge. The particlesare then routed past positively charged plates, or grounded plates, whichattract the now negatively-charged ash particles.

The particles stick to the positive plates until they are collected. The air that leaves the plates is then clean from harmful pollutants.

Side view of ESP Schematic Diagram

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Coal Ash can be used in : Construction of embankments and fills Construction of road in sub-base Manufacture of cement Manufacture of bricks/blocks Filling as flowable fill material Agriculture as soil amendment/source of

essential plant nutrients

SPECIAL PICTURES

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SPECIAL PICTURES

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