The principal items of
conventional or steam power plant are the boiler and the turbine. For these
units a number of auxiliary units are also required. A boiler uses coal, oil or gas as the fuel. For this purpose, the fuel is stored in the
coolant, a fuel handing plant is necessary to maintain a regular supply of fuel
to the boiler. This may again involved a
number of smaller units.
Since the total weight of
the fuel is not decomposed during combustion in the furnace while firing the
boiler, thus a certain percentage of the fuel is collected as waste. In case of coal fired boiler, almost 10-15%
of the total weight of coal fired is collected in the form of ash. Thus a station using 200,000 tonnes of
coal/annum will produce in the average about 25,000 tonnes of ash. Such a huge
quantity of ash from the furnace requires an ash handing equipment which will
transfer ash from boiler furnace to ash storage.
Besides, air heaters may be
used in plant to make use of the heat of flue gases which are always at
elevated temperature. Flue gases go to
the atmosphere through the chimney, induced or forced draft fans may be used to
create the necessary draft.
Steam from the boiler is
supplied to the turbine where it expands thereby doing work. Exhaust steam is passed to the condenser
where it is condensed. The condensate
(i.e. H20) is pumped to the boiler by passing through high and low
pressure heaters.
Condensers use H2O
for condensing steam. H2O at the outlet of the condenser is relatively
hot and may be cooled in the cooling tower and then recirculated.
Turbine is couple to the
generator. Output of the generator is
supplied to consumer is relatively hot and may be cooled in the cooling tower
and then recalculated.
Turbine is coupled to the
generator. Output of the generator is
supplied to consumers through circuit breakers, transformers etc.
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