Workflow:
1. Coal combustion:
Use coal conveyor belts to transport coal from the coal yard to the coal hopper to improve coal combustion. efficiency, large thermal power plants. They burn coal. Therefore, the raw coal in the coal hopper must first be sent to the coal crusher to be crushed into pulverized coal. The crushed pulverized coal is transported by hot air and sent to the boiler furnace via the pulverizer fan for combustion. The hot flue gas formed after the combustion of pulverized coal flows along the horizontal flue and tail flue of the boiler, releases heat, and finally enters the dust collector.
Separate the burned coal ash. The clean combustion gases are evacuated to the atmosphere through the chimney under the action of the induced draft fan. The air of combustion is sent by the fan into the air preheater installed on the flue, and the hot combustion gases are used to heat the air. In this way, on the one hand, in addition to increasing the temperature of the air entering the boiler, which facilitates the ignition and combustion of the pulverized coal, on the other hand, it can also reduce the temperature of the exhaust fumes and improve the utilization rate. thermal energy.
The hot air discharged from the air preheater is divided into two streams: one stream goes to the coal crusher to dry and transport the pulverized coal, and the other stream is sent directly to the furnace to maintain combustion. The ashes from the burned coal fall into the slag hopper below the kiln and are washed with water in the mortar pump room with the fine ash separated from the dust collector, then the mortar is pumped to the ash pond.
2. Thermal energy is converted into energyie mechanical:
The water in the deaerator tank is boosted by the water supply pump and then sent to the economizer via the high pressure heater. In the economizer, the water is heated by the hot flue gases then enters the steam drum located at the top of the boiler. There are water pipes densely distributed around the boiler, called water-cooled walls.
The upper and lower ends of the water pipes of the water-cooled wall are connected to the steam drum through the collector. Water in the steam drum circulates continuously through the water-cooled wall, absorbing heat. released during the combustion of coal. Some of the water is heated and boiled in the cold wall and then vaporized into water vapor. Saturated steam flows from the top of the drum to the superheater.
The saturated steam continues to absorb heat in the superheater and becomes superheated steame. Superheated steam has very high pressure and temperature, so it has high thermal potential energy. After the superheated steam containing thermal potential energy is fed into the steam turbine through the pipeline, the thermal potential energy is converted into kinetic energy. The steam flowing at high speed causes the turbine rotor to rotate, thereby forming mechanical energy.
3. Conversion of mechanical energy into electrical energy:
The steam turbine rotor and the generator rotor are connected together by a coupling. When the turbine rotor rotates, it causes the generator rotor to rotate. There is a small DC generator called an exciter at the other end of the generator rotor. The DC power generated by the exciter is sent to the generator rotor coil, making the rotor an electromagnet and creating a magnetic field around it.
As the generator rotor rotates, the magnetic field also rotates and the generator stator wires cut the magnetic lines of force to induce current. In this way, the generator converts the mechanical energy of the turbine into electrical energy. Once the electrical energy is increased by the voltage passing through the transformer, it is sent to the electricity users via the transmission lines.
4. Water cycle:
The steam that releases thermal potential energy is discharged through the exhaust port at the bottom of the turbine, called waste steam. The spent steam is cooled by the cooling water sent to the condenser by the circulating water pump in the condenser and condenses back into water.for condensed water. The condensate water is sent to the low pressure heater by the condensate water pump and finally returns to the deaerator, thus completing a cycle.
During the circulation process, there will inevitably be sparkling water leakage, that is, sparkling water loss. Therefore, an appropriate amount of water must be supplied to the circulation system to ensure normal operation of the system. ride a bike. High and low pressure heaters are devices used to improve the thermal efficiency of the cycle, and degassers are used to remove oxygen from water to reduce corrosion of equipment and pipelines.
Detailed information:
Energy conversion process of a thermal power plant:
1. The chemical energy of the fuel is converted into thermal energy in the boiler equipment.
2. The conversion of thermal energy into mechanical energy is carried out in the steam turbine.
3. The conversion of mechanical energy into electrical energy is carried outed in the generator.
Main parameters and indicators of thermal power plants:
Classifications of fuels used in thermal power plants:
1. Coal-fired power plants: Coal includes anthracite, semi- There are five categories of bituminous coal, bituminous coal, lignite and low-grade coal.
2. Fuel-Fired Power Plants: Fuels include heavy oil, diesel, and crude oil. In general, fuel-fired power plants are not developed.
3. Gas Power Plant: Gas includes natural gas, artificial gas and underground gasification gas.