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PRINCIPLE OF OPERATION AND
DESIGN OF A THERMAL POWER PLANT
(TPP/CHP)
5B04 Login Vadim
Thermal power plants (TPPs) run on fossil fuels. It burns in a furnace, and the energy of chemical bonds is
converted into heat energy from the products of combustion - water and carbon dioxide. The heat heats the
water in the steam boiler and turns it into hot steam, which rushes under tremendous pressure into the
turbine. At its blades, the steam's thermal energy is converted into mechanical energy. The steam cools and
expands, and the turbine spins and turns the rotor of the electric generator, which converts the mechanical
energy of rotation into electrical energy.
After passing through transmission lines and transformer substations, the electricity reaches homes, schools,
stores and factories. The described scheme is considered to be the classical scheme, and TPPs operating under
this scheme are called condensing, or CES.
Schematic diagram of a classical combined heat and power plant
PRINCIPLE OF OPERATION
The scheme of CHPP operation is quite simple. Fuel and heated air - oxidizer enter the furnace simultaneously. The most common fuel at Russian CHPPs is
pulverized coal. The heat from the combustion of coal dust turns the water
entering the boiler into steam, which is then fed under pressure to the steam
turbine. The powerful steam flow makes it rotate, driving the generator rotor,
which converts mechanical energy into electrical energy.
Then the steam, which has already significantly lost its original parameters - temperature and pressure - enters
the condenser, where after a cold «water shower» it becomes water again. Then the condensate pump pumps it
to the regenerative heaters and then to the deaerator. There, the water is freed from gases such as oxygen and
CO2, which can cause corrosion.The water is then heated again from steam and fed back to the boiler.
HEAT SUPPLY
The second, no less important function of the CHPP is to provide hot water
(steam) for the central heating systems of nearby settlements and for domestic
use. In special heaters, cold water is heated to 70 degrees in summer and 120
degrees in winter, after which it is supplied by network pumps to a common
mixing chamber and then through a system of heating mains to consumers. Water
reserves at the CHPP are constantly replenished.
HOW GAS-FIRED THERMAL POWER
PLANTS WORK
Compared to coal-fired TPPs, TPPs with gas turbine units are much more compact and environmentally friendly.
Suffice it to say that such a plant does not need a steam boiler. A gas turbine unit is essentially the same as a
turbojet aircraft engine, where, unlike it, the jet is not emitted into the atmosphere, but rotates the rotor of the
generator. At the same time, emissions of combustion products are minimal.
«OXYFUEL CAPTURE»
Here, too, pure oxygen is used as an oxidizing agent when burning coal. Only in
contrast to the previous method, steam is generated at the moment of
combustion, which drives the turbine into rotation. The ash and sulfur oxides are
then removed from the flue gases, cooled and condensed. The remaining carbon
dioxide is pressurized at 70 atmospheres into a liquid state and placed
underground.
«PRE-COMBUSTION»
Coal is burned in the "normal" mode - in the boiler mixed with air. The ash and
SO2 - sulphur oxide - are then removed. Next, CO2 is removed with a special
liquid absorbent, after which it is utilized by burial.
«OXYFUEL CAPTURE»
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