What are the components of a typical Thermal Power Plant?

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Thermal Power Plant

A generating station which converts the heat energy of combustion of coal into electrical energy is called a thermal power plant or steam power station.

Schematic Arrangement of Thermal Power Plant

The thermal power plant has many arrangements for proper and efficient working. The schematic of a modern thermal power plant is shown in the figure. This whole schematic arrangement can be divided into the following segments −

Coal and Ash Handling Plant

The coal is transported to the site of power plant from the coal mines by rail or road and it is stored in the coal storage plant. From the coal storage plant, the coal is led to the coal handling plant where it is pulverised, i.e., crushed into small pieces, so that its effective surface area is increased which promotes the rapid combustion without using large quantity of excess air. This pulverised coal is fed to the boiler and it is burnt in the boiler.

Now, the ash produced by the complete combustion of coal is removed to the ash handling plant and then stored in the ash storage plant for the disposal.

Feed Water

The condensate from the condenser is used as feed water to the boiler for the production of steam. Some amount of water may be lost in the cycle which is taken from external sources of water. The feed water is preheated by the water heaters and economiser before feed it to the boiler. This increases the overall efficiency of the power plant.

Steam Generating Plant

The main component of the steam generating plant is the boiler which converts water into steam. In addition to the boiler, the steam generating plant also consists of many auxiliary equipment as −

  • Boiler – The boiler is a device which uses the heat of combustion of coal to convert water into steam at high temperature and pressure.

  • Super heater – The steam produced in the boiler is wet and it is passed through a super heater where it is dried and its temperature is increased above that of boiling point of water. The superheating increases the overall efficiency and avoids the too much condensation in the last stage of turbine.

  • Economiser – The economiser is nothing but a feed water heater. It uses the heat of flue gases to increase the temperature of the feed water. The feed water is fed to the economiser before supplying to the boiler.

  • Air Preheater – The air preheater is a device which is used to increase the temperature of the air supplied for combustion of coal by using the heat of the flue gases. The air preheating increases the thermal efficiency of the power plant.

Steam Turbine

The steam turbine unit converts the steam energy into mechanical energy. The superheated steam is fed to the steam turbine through the main valve. The heat energy of the steam when passing over the blades of the turbine is converted into mechanical energy.

Once the heat energy is given to the turbine, the steam is exhausted to the condenser which condenses the exhausted steam with the circulation of cold water.

Cooling Arrangement

The cooling arrangement mainly consists of condenser and cooling towers. The condenser is used to condense the steam exhausted from the turbine, so that the overall efficiency of the power plant can be improved. For condensation, water is drawn from a natural source (for example, rivers) and it is circulated through the condenser. This circulating water takes up the heat of the exhausted steam and itself becomes hot.

Finally, this hot water coming out from the condenser is discharged in the river. During the scarcity of water in the river, the hot water from the condenser is passed through the cooling towers where it is cooled. This cold water from the cooling towers is reused in the condenser.

Alternator

The alternator remains coupled to the turbine and converts the mechanical energy of the turbine into electrical energy output. The electrical energy is then transmitted and distributed to the consumers for the utilisation.

raja
Updated on 08-Feb-2022 11:20:47

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