A thermal power plant is a factory that uses coal, oil and natural gas as fuel to produce electricity. Its basic production process is as follows: fuel is burned in the boiler to heat water and turn it into steam. The chemical energy of the fuel is converted into thermal energy. Steam Pressure causes the steam turbine to rotate, converting thermal energy into mechanical energy. The steam turbine then turns the generator, converting mechanical energy into electrical energy. Thermal power plants are classified as follows: According to fuel: coal-fired power plants, oil-fired power plants, gas-fired power plants, waste heat power plants, power plants using garbage and industrial waste as fuel; temperature: the working fluids in the boiler are It is water. Cree settingsticks of water are: 22.064 MPa and 373.99 ℃ At this pressure and temperature, the density of water and steam is the same, which is called the critical point of water. The pressure of the working fluid in the furnace is less than this pressure and is called subcritical boilers, pressures higher than this are called supercritical boilers. The steam temperature in the oven is not lower than 593°C or the steam pressure is not lower. than 31MPa, which is called ultra-supercritical.
Medium and low pressure power plants (3.92 MPa, 450 degrees), high pressure power plants (9.9 MPa, 540 degrees), ultra high pressure power plants (13.83 MPa , 540 degrees), subcritical pressure power plants (16.77 MPa, 540 degrees), supercritical pressure power plants (22.11 MPa, 550 degrees); from the selection of parameters of supercritical or ultra-supercritical units that have been constructeds and under construction internationally and nationally, for supercritical and ultra-supercritical units There is no hard limit, it is simply a matter of knowing what the parameter value is. At present, domestic and international people generally think that as long as the main steam temperature reaches or exceeds 600°C, it is considered an ultra-supercritical unit. According to the prime mover: condensing steam turbine power plant, gas turbine power plant, internal combustion engine power plant, steam-gas turbine power plant, etc. depending on the energy produced, condensing steam plant (only produces electricity), thermal; power plant (produces electricity and heat); According to the installed capacity of power plants: small capacity power plants (less than 100 MW), medium capacity power plants (100-250 MW), large and medium power plantscapacity (250-1,000 MW), large capacity power plants (above 1,000 MW); thermal power plants. There are several types of wastewater produced: industrial wastewater, domestic wastewater, coal-containing wastewater, and acid-base wastewater. classification, and the processes are also different.
Water extracted from rivers by power plants is called "raw water", and water after chemical addition, clarification and filtration is called "purified water" (equivalent to tap water). Reclaimed water refers to industrial wastewater and recycled rainwater. This may be due to the fact that wastewater treatment does not meet certain indicators. For example, the acid content of gray flushing water is very high. Even if alkalis are added and combined, they will still be corrosive and therefore will not be released into circulating water. water system. (It can be used if the qwater quality complies with standards.)