A power plant that uses coal, oil, and natural gas to generate electricity is called a thermal power plant, and a thermal power plant that generates electricity and heat is called a thermal power plant (also called a thermal power plant). Thermal power plants can make full use of the waste heat released by power plants to make full use of fuel.
For example, in a power plant burning coal powder, the production process of a thermal power plant is: sending coal powder to a boiler for combustion. The heat is released, and the water in the boiler is heated to generate steam having a certain temperature and pressure. This process converts the chemical energy of the fuel into the internal energy of the steam. The steam with a certain temperature and pressure is sent into the steam turbine to drive the turbine rotor to rotate. This process converts the internal energy of the steam into the mechanical energy of the turbine. The steam turbine drives the generator on the same shaft to rotate and emit electricity. This process converts mechanical energy into electrical energy. According to the production process of a thermal power plant, its production system mainly includes a steam water system, a combustion system and an electrical system.
In the production process of a thermal power plant, the high-pressure hot steam entering the steam turbine is continuously expanded, the flow rate is increased, and the impeller of the steam turbine drives the generator to generate electricity. During the expansion process, the pressure and temperature of the steam are continuously reduced and finally discharged into the condenser. In the condenser, the steam discharged from the steam turbine is cooled by the cooling water to become condensed water. After the condensed water is boosted by the water pump, it is returned to the boiler to form a closed thermodynamic cycle system. However, the thermal efficiency of the cycle is very low, generally less than 40%, which means that 60% of the heat emitted by the fuel is lost, and most of it is the heat that the steam transfers to the cooling water in the condenser. Generally, the temperature of the cooling water is increased by about 10 °C after the heat is absorbed. Condensing 1 kilogram of steam, the quality of the cooling water that needs to pass through the condenser is about 40 to 50 times that of the steam. A lot of cooling water takes away a lot of heat. However, due to the large amount of water and low water temperature, this part of the heat is difficult to use. It is often sent to the river or cooling pool by the cooling water that takes away a lot of heat, and the heat is lost in the atmosphere.
If this part of the heat can be used, the fuel utilization rate can be improved and the economic efficiency of the power plant can be improved. We know that some industries need to use low-pressure steam, such as chemical, printing and dyeing, paper making, cotton spinning and other factories, and these factories often supply steam to their own boilers; as well as heating and domestic water in factories, mines, schools, schools and other units. Have to supply boilers to supply steam and hot water. If the steam of the power plant is used to solve their heating needs, many low-pressure boilers can be saved without the need to add equipment and consume fuel. Save a lot of manpower and material resources. A thermal power plant is such a power plant that supplies both electricity and heat.