• 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.

• As we know thermal power plant is conventional type power source.• In thermal power plant coal is use as fuel.• 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 depending on its location in the world

• 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 electricalgenerating stations in New York and London, in 1882, also used reciprocating steam engines. • As generator sizes increased, eventually turbines took over.

WORKING PRINCIPAL:Thermal power plant is simply work on

the steam generation and driven generator.

High potential steam is rotate turbine ,thus generator operate.

Construction:

1. Cooling tower 2. Cooling water3. transmission line4. Step-up transformer5 . Electrical generator6. Low pressure steam

turbine7. Condensate pump8. Surface condenser9. Intermediate pressure

steam turbine10. Steam Control valve11. High pressure steam

turbine.

12. Deaerator13. Fee-dwater heater14. Coal conveyor15. Coal hopper16. Coal pulverizer17. Boiler steam drum18. Bottom ash hopper19. Super-heater20. Forced draught (draft)

fan21. Re-heater22. Combustion air intake23. Economiser24. Air pre-heater

OPERATIONS OF A THERMAL POWER STATION:

Below is a Diagram of the Basic Operation of a Thermal Power Station.

•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 , it forces its way through the Turbine, thus rotating the Turbine. • The Turbine is connected to a Generator via a coupler. As the Turbine is rotating electrical energy is being produced.• After the steams have passed through the turbine, it enters a Condenser. The Condenser has got a cooling agent 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.

  Then the quantity of coal required per hour would be given by Weight of Coal Required ==> Capacity * Steam Requirement * Heat Delivered/Calorific Value of Coal * Efficiency of Boiler

  

•Steam is generated in the boiler of the thermal power plant using heat of the fuel burnt in the combustion chamber. •The steam generated is passed through steam turbine where part of its thermal energy is converted into mechanical energy which is further used for generating electric power. •The steam coming out of the steam turbine is condensed in the condenser and the condensate is supplied back to the boiler with the help of the feed pump and the cycle is repeated. •The function of the Boiler is to generate steam. The function of the condenser is to condense the steam coming out of the low pressure turbine.

The function of the steam turbine is to convert heat energy into mechanical energy.

The function of the condenser is to increase the pressure of the condensate from the condenser pressure to the boiler pressure.

The other components like economizer, super heater, air heater and feed water heaters are used in the primary circuit to increase the overall efficiency of the plant

 

In general, both the construction and operation of a power plant requires the existence of some conditions such as water resources and stable soil type.. The following list corers most of the factors that should be studied and considered in selection of proper sites for power plant construction: •Transportation network: Easy and enough access to transportation network is required in both power plant construction and operation periods.

•Gas pipe network: Vicinity to the gas pipes reduces the required expenses

•Power transmission network: To transfer the generated electricity to the consumers, the plant should be connected to electrical transmission system.Therefore the nearness to the electric network can play a roll

•Geology and soil type: The power plant should be built in an area with soil and rock layers that could stand the weight and vibrations of the power plant. •Earthquake and geological faults: Even weak and small earthquakes can damage many parts of a power plant intensively. Therefore the site should be away enough from the faults and previous earthquake areas. •Topography: It is proved that high elevation has a negative effect on production efficiency of gas turbines. In addition, changing of a sloping area into a flat site for the construction of the power plant needs extra budget. Therefore, the parameters of elevation and slope should be considered.

Water resources: For the construction and operating of power plant different volumes of water are required. This could be supplied from either rivers or underground water resources. Therefore having enough water supplies in defined vicinity can be a factor in the selection of the site.

Population centers: For the same reasons as above, the site should have an enough distance from population centers.

Environmental resources: Operation of a power plant has important impacts on environment. Therefore, priority will be given to the locations that are far enough from national parks, wildlife, protected areas, etc.

PARTS OF THERMAL POWER PLANT

Steam generator: In fossil-fueled power plants, steam generator refers to a furnace that burns the fossil fuel to boil water to generate steam.

The steam generating boiler has to produce steam at the high purity, pressure and temperature required for the steam turbine that drives the electrical generator.

A fossil fuel steam generator includes an economizer, a steam drum, and the furnace with its steam generating tubes and superheater coils.

Necessary safety valves are located at suitable points to avoid excessive boiler pressure.

Boiler: Boiler is a cylindrical closed vessel made from the steel is called boiler. In which by boiling water high pressure stem can be produce.

In boiler coal is mainly used as fule.The other material like oil , wood, gas, sawdust ,bagasse etc are used as fuel.

Boiler is a heart of the thermal power plant system

The types of boilers use in thermal power plant are as below:

(1)Circulating fluidzed bed boiler. (2)Water fired tube shell boiler. (3)Water tube boiler. (4)Fully automatic oil &and gas fired boiler.

Boiler furnace and steam drumOnce 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 the chemical 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.

SuperheaterFossil fuel power plants can have a superheater

and/or reheater section in the steam generating furnace

In a fossil fuel plant, after the steam is conditioned by the drying equipment inside the steam drum, it is piped from the upper drum area into tubes inside an area of the furnace known as the superheter.

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 called thermal power plant.

Fuel preparationIn coal-fired power stations, the raw feed coal

from the coal storage area is first crushed into small pieces and then conveyed to the coal feed hoppers at the boilers.

The coal is next pulverized into a very fine powder. The pulverizers may be ball mills, rotating drum grinders, or other types of grinders.

Some power stations burn fuel oil rather than coal. The oil must kept warm in the fuel oil storage tanks to prevent the oil from congealing and becoming un-pumpable.

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

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

• Auxiliary systems:• Fly ash collection: Fly ashis captured and removed from

the flue gas by electrostatic precipitators or fabric bag filters located at the outlet of the furnace and before the induced draft fan.

• The fly ash is periodically removed from the collection hoppers below the precipitators or bag

• 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.

• 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.

Steam turbine-driven electric generator:The steam turbine generator being rotating

equipment generally has a heavy, large diameter shaft.

The shaft therefore requires not only supports but also has to be kept in position while running. To minimise the frictional resistance to the rotation, the shaft has a number of bearings

• Barring gear:• Barring gear or turning gear is the mechanism

provided to rotate the turbine generator shaft at a very low speed after unit stoppages

• 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 by flowing over the tubes as shown in the adjacent diagram.

• For best efficiency, the temperature in the condenser must be kept as low as practical in order to achieve the lowest possible pressure in the condensing steam.

Since the condenser temperature can almost always be kept significantly below 100 °C where the vapor pressure of water is much less than atmospheric pressure, the condenser generally works under vacuum. Thus leaks of non-condensible air into the closed loop must be prevented

Feedwater heater: 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 thermalshock to the boiler metal when the feed-water is introduced back into the steam cycle.

Deaerator: 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.

There are many different designs for a deaerator and the designs will vary from one manufacturer to another

Auxiliary systems Oil systemAn auxiliary oil system pump is used to supply oil

at the start-up of the steam turbine generator.Generator heat dissipation The electricity generator requires cooling to

dissipate the heat that it generates. While small units 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 windage losses

Generator high voltage systemThe generator voltage 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.

The generator high voltage channels 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

Other systemsMonitoring and alarm systemBattery supplied emergency lighting and

communication

Efficiency

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

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

• The electric efficiency of a conventional thermal power station, considered as saleable energy (in Mwe ) produced at the plant bus-bars 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.

AdvantagesThe fuel used is quite cheap.Less initial cost as compared to other generating

plants.It can be installed at any place irespective of the

existence of coal. The coal can be transported to the site of the plant by rail or road.

It require less space as compared to Hydro power plants.

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

Disadvantages:It pollutes the atmosphere due to production of

large amount of smoke and fumes.It is costlier in running cost as compared to

Hydro electric plants.

SPACIFICATION OF THERMAL POWER PLANT:

(1)Power plant should be far away from the recidential area

(2)Plant should have enough space for the future implimention

(3)The physical west should be remove at proper place to avoid its harm effect.

(4)Plants machinery should be maintain well and their inspection must done the proper time interval

(5)Safety of the plant worker or employ should be maintain

(6)All machinery of plant should as per standard regulation by Government.

(7)Policy of worker and machinery should be paid at proper time

 

THERMAL POWER PLANT IN GUJARAT: (1)Gandhinagar thermal power station-870. (2)Ukai thermal power plant-850mw. (3)Wanakbori power plant-1470mw (4) Sikka thermal power station-240mw THERMAL POWER PLANT IN INDIA:

(1)Anpara power station-Utter pradesh

(2)Bakreswar power plant-West Bengal

(3)Panipat thermal power station-Panipat (H.P)

(4)Deenbandhu Chhou ram power station-Yamunanagar(H.R)

(5)Rajiv Gandhi thermal power plant-Hissar(H.P)