Block Diagram of a Thermal Power Plant
A thermal power plant converts heat energy into electrical energy through a series of interconnected processes. The block diagram below outlines the major components and their functions in a typical coal-fired thermal power plant.
1. Coal Handling Plant (CHP)
The process begins with the coal handling plant, where raw coal is transported from mines via rail or road. The coal is crushed into fine powder to improve combustion efficiency and then fed into the boiler through conveyor belts.
2. Boiler
The pulverized coal is burned in the boiler furnace, producing high-temperature flue gases. Water inside the boiler tubes absorbs this heat, converting it into high-pressure steam. Modern boilers use superheaters to further increase steam temperature for higher efficiency.
3. Turbine
The high-pressure steam enters the steam turbine, where it expands and rotates the turbine blades. The turbine is typically divided into high-pressure (HP), intermediate-pressure (IP), and low-pressure (LP) sections to maximize energy extraction.
4. Generator
Connected to the turbine shaft, the generator converts mechanical energy into electrical energy through electromagnetic induction. The output voltage is stepped up using transformers before transmission to the grid.
5. Condenser
After passing through the turbine, exhaust steam is condensed back into water using cooling towers or a water source (river/sea). This condensation creates a vacuum that improves turbine efficiency by reducing backpressure.
6. Cooling Tower
In open-loop systems, hot water from the condenser is cooled in cooling towers before being recirculated. These towers release excess heat into the atmosphere through evaporation or forced air cooling.
7. Feedwater Pump
The condensed water is pumped back into the boiler using feedwater pumps, completing the Rankine cycle—a continuous loop of steam generation, expansion, condensation, and reheating.
8. Ash Handling System
Combustion residues (fly ash and bottom ash) are collected and transported to disposal sites or reused in construction materials like cement production to minimize environmental impact.
9. Flue Gas Treatment (FGT)
Before releasing exhaust gases into the atmosphere, they pass through electrostatic precipitators (ESPs) or scrubbers to remove particulate matter (PM), sulfur dioxide (SO₂), and nitrogen oxides (NOₓ).
Conclusion
Thermal power plants rely on precise coordination between these subsystems to ensure efficient