Thermal Power Plants work on the Rankine cycle. In a thermal power plant, the chemical energy of the fuel is converted into the heat energy in the boiler. This heat energy converts into kinetic energy by the turbine. The kinetic energy is converted into electrical energy with the help of an alternator (Synchronous generator).
In India, more than 60% of electricity generates from the thermal (coal) power plant. The thermal power plants is the most conventional and old plant. Generally, coal is used as a fuel in TPP. Coal has chemical energy. In a thermal power plant, chemical energy converts into electrical energy. Bituminous or brown coal is easily available in India. So, most of the power plants use this type of coal. This coal has 5 to 16% ash and 8 to 33% volatile content.
The components used in thermal power plant:
- Heat exchanger (Air preheater)
- Feed water heater
- Cooling tower
Working of Thermal Power Plants:
The boiler uses to increase the temperature of water and make hot water or steam and this steam is wet steam. So, wet steam passes through superheater and makes a very high-pressure and high-temperature steam. The deaerator use to remove oxygen and other dissolved gases from the supplied water.
This steam is sufficient to rotate the turbine at very high speed. So, high pressure and high-temperature steam is pass to the turbine, where thermal energy converts into (kinetic) rotational energy. The turbine connects with the shaft of the alternator. So, this mechanical energy converts into electrical energy with the help of alternators.
The heat exchanger uses to transfer heat from one medium to another medium. so, the heat exchanger use to increase efficiency and minimize losses. The economizer use to increase the streaming rate, saving fuel consumption, and boiler efficiency. The condensers use steam ejectors or rotary motor driven exhausts for continuous removal of air and gases from the steam side to maintain the vacuum. The temperature in the condenser must be kept as low as practical.
For more efficiency, two or three level turbine use. The feed water heater is equipment that uses to raises the temperature of the water by utilizing extraction steam from various stages of the turbine. Once steam passes through HT turbine, it again superheated and passes through LT turbine. After that, steam passes through economizers and cooling tower, which converts steam in water and this water again use in the boiler to generate steam.
After combustion of coal, ash remains at the bottom of the boiler, this ash pass to the ash handling plant. Where ash is stored and it is not allowed to pass into the atmosphere through the chimney. So this is how thermal power plants are works.
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