A thermal power plant is a generating station that converts heat energy into electrical energy. The basic idea is simple. Fuel is burned to produce steam, the steam rotates a turbine, and the turbine drives a generator to produce electricity.
Layout of thermal power plant
Coal Handling Plant
The coal handling plant is the starting point of the layout. Coal is transported to the plant by rail or trucks and stored in the coal yard. From storage, coal is supplied to crushers where it is broken into smaller pieces and then fed into pulverizers. Pulverized coal is sent to the boiler furnace for combustion.
Boiler Section
The boiler is the heart of the thermal power plant. It consists of a furnace, water walls, drum, superheater, economiser, and air preheater.
Inside the furnace, pulverized coal is burnt. The heat produced converts water into high pressure steam. The economiser preheats the feed water using hot flue gases before it enters the boiler drum. The superheater increases the temperature of steam above its saturation point. The air preheater heats the incoming air using flue gases to improve combustion efficiency.
Steam Turbine Section
The superheated steam from the boiler is supplied to the steam turbine through a control valve. The turbine is mechanically coupled to the generator. As steam expands through turbine blades, it rotates the turbine shaft.
Generator Section
The generator is connected directly to the turbine shaft. When the turbine rotates, the generator converts mechanical energy into electrical energy based on the principle of electromagnetic induction. The generated power is then supplied to the transmission system.
Condenser and Cooling System
After passing through the turbine, the exhaust steam enters the condenser. The condenser converts steam back into water by circulating cold water through cooling tubes. Cooling water is supplied from a cooling tower or nearby water source.
The cooling tower removes heat from the circulating water and sends it back to the condenser for reuse.
Feed Water System
The condensed water, called condensate, is pumped back to the boiler using feed water pumps. Before entering the boiler, the water passes through low pressure and high pressure heaters to increase its temperature. This improves the overall efficiency of the plant.
Ash Handling Plant
During coal combustion, ash is produced. The ash handling plant collects bottom ash and fly ash and disposes of it safely. This section is important for environmental control.
Chimney
The chimney releases flue gases produced during combustion into the atmosphere at a safe height. It ensures proper draft inside the boiler.
Working of a Thermal Power Plant
The working of a thermal power plant is based on the Rankine cycle. First, coal is supplied from the coal storage to the boiler furnace where it is burnt. Heat produced during combustion converts water inside the boiler into high pressure steam. This steam is passed through a superheater to increase its temperature and then supplied to the steam turbine through the main control valve.
The steam expands in the turbine and rotates the turbine blades. The turbine shaft rotates the generator rotor, producing three phase electrical power. After expansion, the exhaust steam enters the condenser where it is cooled and converted into water. The condensate is pumped back to the boiler through feed water heaters and economiser. This cycle is repeated continuously for power generation.
