A coal-fired power plant, or PLTU, is a type of thermal power plant that generates electricity through a series of energy conversions. The process is a chain reaction that transforms the potential chemical energy stored in coal into usable electrical energy. This complex process can be broken down into three main stages.
Phase 1: From Chemical to Thermal Energy
The first and most fundamental step is to extract the energy from the coal itself. This is done through a process of combustion.
Fuel Preparation: Coal is transported to the power plant and stored. Before it can be burned efficiently, it is pulverized into a fine, talcum powder-like consistency. This increases its surface area, allowing it to ignite quickly and burn thoroughly. The powdered coal is then blown into the boiler.
Combustion in the Boiler: The boiler acts as the plant's furnace. Here, the powdered coal is ignited, creating an intense fire. This process releases the chemical energy stored in the coal's molecular bonds as immense heat. This heat is used to boil water that circulates in a network of pipes within the boiler, creating high-pressure steam.
This stage represents the conversion of the chemical energy in the coal into thermal energy (heat) in the steam.
Phase 2: From Thermal to Mechanical Energy
The high-pressure steam is the key to driving the next stage of the process, where thermal energy is converted into mechanical motion.
Driving the Turbine: The superheated, high-pressure steam is directed through a series of nozzles at the blades of a large steam turbine. The sheer force of the steam pushes against the turbine blades, causing the entire shaft to spin at a very high speed, often thousands of revolutions per minute.
Recycling the Steam: After passing through the turbine, the steam is no longer at high pressure. It is directed to a condenser, which uses cool water from a nearby river or cooling tower to condense the steam back into a liquid state. The water is then pumped back to the boiler to be reheated, completing the cycle.
The process of the steam spinning the turbine converts thermal energy into mechanical energy (the rotation of the turbine shaft).
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Phase 3: From Mechanical to Electrical Energy
The final stage is the direct generation of electricity, driven by the mechanical energy of the spinning turbine.
The Generator: The turbine shaft is directly connected to a generator. Inside the generator, a massive electromagnet rotates rapidly within a series of copper coils. This spinning motion in the magnetic field induces a flow of electrons, creating an electrical current.
Transmission: The electricity produced by the generator is at a relatively low voltage. It is then sent to a transformer, which steps up the voltage. This allows the electricity to be transmitted efficiently over long-distance power lines to the electrical grid, where it can be distributed to homes, businesses, and industries.
This final stage completes the energy conversion chain, transforming mechanical energy into the final product: electrical energy.
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