Thermal power plant is abbreviated as thermal power plant. It is a factory that uses coal, oil, and natural gas as fuel to produce electricity. Its basic production process is: the fuel is burned in a boiler to heat water into steam, and the chemical energy of the fuel is converted into heat energy. The steam turbine is driven to rotate, and the thermal energy is converted into mechanical energy, and then the steam turbine drives the generator to rotate, which converts the mechanical energy into electrical energy.
What type of pumps are commonly used in thermal power plants?
In the thermal system of a thermal power plant, the pumps used in the power plant are divided into two major systems according to their functions: steam turbine auxiliary pumps (boiler feed pumps, front pumps, condensate pumps), desulfurization circulating pumps (main circulating desulfurization pumps, FGD peripheral pumps, absorption Tower system), there are boiler feed water pumps, condensate pumps and cooling water circulation pumps required for water vapor circulation, as well as front booster pumps, low-pressure heater drain pumps, high-pressure heater drain pumps, and ash pumps to remove boiler coal ash. When the power plant uses an auxiliary circulation drum boiler or a combined circulation boiler, a boiler circulation pump is also required. In the wet flue gas desulfurization system of thermal power stations, desulfurization pumps such as limestone slurry pump, slurry circulation pump and gypsum slurry pump are also installed. Pumps used in power plants have a wide range of applications.
1. Boiler feed water pump
With the improvement of power station technology, boiler feed water pumps are developing in the direction of large capacity and high head, and their operation is required to ensure safe and reliable operation, and even when the pump is severely cavitation or water intake is interrupted, it can continue to reliably "dry run" and The maintenance is convenient to reduce the economic loss caused by the shutdown of the unit.
2. Condensate pump
The condensate pump sucks water from the hot well of the condenser. Because the pressure in the condenser is very low, in order to avoid cavitation of the condensate pump, in addition to working in the reversed state, it is also required to have high anti-cavitation performance. With different heads, the condensate pump can be a single-stage pump or a multi-stage pump. It can be a vertical shaft pump or a horizontal shaft pump.
3. Heater drain pump
It is also used to transport condensate water. The low-pressure heater drain pump sucks condensate water from the low-pressure heater and delivers it to the water circulation pipeline. The high-pressure heater drain pump is used to ensure that the condensate in the high-pressure heater can be transported to the deaerator when the main steam turbine is under partial load. Therefore, power plant drain pumps, especially low-pressure heater drain pumps, have similar working conditions as condensate pumps, and their structure should have the same characteristics as condensate pumps.
4. Ash pump
The ash and slag pump is used to transport boiler coal ash and slag to a suitable place outside the plant or into a dam.
5. Boiler circulating pump
Boiler circulating pumps installed in drum boilers or combined circulation boilers used in large-capacity power stations are used to force boiler water to circulate. The pump head is not high, generally 30-60m, but the working conditions are harsh. The inlet pressure and temperature of the pump are both high and must have good sealing performance. Canned motor pumps or wet stator shaft-sealed pumps are often used.
6. Desulfurization pump
In the wet flue gas desulfurization system of coal-fired power stations, limestone swirl pumps, limestone slurry pumps, circulating slurry pumps, gypsum discharge pumps, filter pumps, waste water swirl pumps, flue gas cooling water pumps and other desulfurization pumps are also installed.
7. Circulating pumps for power plants
It is used to supply condensed water to the condenser. This kind of pump has a large flow rate, which can be 50 times the flow rate of the boiler feed water pump, and has a large geometrical size. It is a larger device in power generation auxiliary equipment. Because the amount of cooling water that depends on the condenser capacity changes with the seasons, the flow rate of the circulating pump also changes with the seasons. This kind of pump often runs under the inverted state, and often adopts a vertical shaft structure in which the impeller is submerged in water. Either a vertical axial flow pump or a centrifugal pump can be used as a circulating pump.
In addition to the above-mentioned various pumps, auxiliary mechanical equipment must be equipped for the normal operation of the main equipment of the power station. There are also various types of pump applications in these auxiliary equipment, including:
●Vacuum pump and jet pump in vacuum system of power station
●The production and domestic water supply pumps in the technical water supply system
●Various oil pumps in the oil supply system
●Sewage pump, submersible sewage pump and sewage pump in sewage system
●Fire pump in fire fighting system
●Sewage pumps and submersible sewage pumps used for seepage and accumulation of water in the plant
