A coal power station turns the chemical energy in
coal into electrical energy that can be used in homes and businesses.
First the coal (1) is ground to a fine powder and
blown into the boiler (2), where it is burned, converting its chemical
energy into heat energy. Grinding the coal into powder increases its
surface area, which helps it to burn faster and hotter, producing as
much heat and as little waste as possible.
As well as heat, burning coal produces ash and
exhaust gases. The ash falls to the bottom of the boiler and is removed
by the ash systems (3). It is usually then sold to the building industry
and used as an ingredient in various building materials, like concrete.
The gases enter the exhaust stack (4), which
contains equipment that filters out any dust and ash, before venting
into the atmosphere. The exhaust stacks of coal power stations are built
tall so that the exhaust plume (5) can disperse before it touches the
ground. This ensures that it does not affect the quality of the air
around the station.
Burning the coal heats water in pipes coiled
around the boiler, turning it into steam. The hot steam expands in the
pipes, so when it emerges it is under high pressure. The pressure drives
the steam over the blades of the steam turbine (6), causing it to spin,
converting the heat energy released in the boiler into mechanical
energy.
A shaft connects the steam turbine to the turbine
generator (7), so when the turbine spins, so does the generator. The
generator uses an electromagnetic field to convert this mechanical
energy into electrical energy.
After passing through the turbine, the steam
comes into contact with pipes full of cold water. In coastal stations
this water is pumped straight from the sea (8). The cold pipes cool the
steam so that it condenses back into water. It is then piped back to the
boiler, where it can be heated up again, turn into steam again, and
keep the turbine turning.
Finally, a transformer converts the electrical
energy from the generator to a high voltage. The national grid uses high
voltages to transmit electricity efficiently through the power lines
(9) to the homes and businesses that need it (10). Here, other
transformers reduce the voltage back down to a usable level.
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