What is the principle of thermal power generation

At present, the electrostatic precipitator commonly used in large thermal power plants can remove more than 99% of the dust in the flue gas, China's soot emissions in 1978 was 4 million t, in 2007 reduced to about 3 million t. In other words, although the power industry has vigorously developed, the emissions of smoke and dust have declined, and are basically the same as those of developed countries in the world.

In China, the desulfurization efficiency of flue gas desulfurization system can reach more than 93%, and the proportion of thermal power units equipped with desulfurization facilities has increased year by year, from 2005 to 2007 were 12%, 30% and 50%, and more than 60% in 2008. At the same time, the denitrification (nitrogen oxide) system of flue gas is also being promoted in China's large power plants, and the newly built 1000MW units will be simultaneously equipped with denitrification devices.

In the comprehensive utilization of ash residue, useful experience has been obtained, such as using ash residue to make building materials, extract rare metals, improve soil and so on. The state has banned the discharge of ash into rivers and lakes.

5. Process

The process of thermal power generation varies depending on the prime mover used. In the steam turbine power generation method, the basic process is to first send fuel into the boiler, at the same time into the air, the boiler injected chemical treatment of water, the use of fuel combustion released heat energy to make water into high temperature, high pressure steam, drive the turbine rotation and work to drive the generator power generation. The cogeneration method is to use the exhaust steam (or special extraction steam) of the prime mover to heat industrial production or residential life. In the gas turbine power generation mode, the basic process is to use the compressor to press the compressed air into the combustion chamber, mix and atomize with the injected fuel, and then burn, form high-temperature gas into the gas turbine to expand and do work, push the turbine blade to rotate and drive the generator to generate electricity. In diesel engine power generation, the basic process is to use fuel injection pump and injector to high-pressure fuel injection into the cylinder, forming a fog, mixed with air combustion, to promote the rotation of the diesel engine and drive the generator to generate electricity.

Step 6: Composition

According to the production process of thermal power generation, its basic composition includes the combustion system, the steam water system (gas turbine power generation and diesel power generation do not have this system, but the proportion of both in thermal power generation is not large), the electrical system, and the control system.

Combustion system

It is mainly composed of the combustion chamber of the boiler (that is, the furnace), the air supply device, the coal (or oil, natural gas) device, and the ash and slag discharge device. The main function is to complete the combustion process of the fuel, release the energy contained in the fuel in the form of heat energy, and use it to heat the water in the boiler. The main processes include flue gas flow, ventilation flow, ash discharge and slag flow, etc. The basic requirements of the combustion system are: to achieve complete combustion as far as possible, so that the boiler efficiency is ≥90%; Ash discharge in accordance with standard regulations.

Steam water system

It is mainly composed of feed pump, circulating pump, feed water heater, condenser, deaerator, water wall and pipeline system. Its function is to use the combustion of fuel to turn water into high temperature and high pressure steam, and to circulate water. The main processes include soda flow, recharge water flow, cooling water flow and so on. The basic requirement of soda water system is to minimize the loss of soda water; The condensate water is heated by extraction steam as much as possible to raise the feed water temperature.

Electrical system

It is mainly composed of power plant main wiring, turbine generator, main transformer, distribution equipment, switchgear, generator outlet, factory junction, factory transformer and reactor, factory motor, security power supply, battery DC system and communication equipment, lighting equipment, etc. The basic function is to ensure power supply to the load or power system according to power quality requirements. The main process includes power supply process and plant power supply process. The basic requirements of the electrical system are safe and reliable power supply; Flexible scheduling; Good adjustment and operation function to ensure the quality of power supply; The fault can be removed quickly to avoid the expansion of the accident.

Control system

It is mainly composed of boiler and its auxiliary system, steam turbine and its auxiliary system, generator and electrical equipment, and auxiliary system. The basic function is to implement automatic regulation and control of each production link of the thermal power plant to coordinate the working conditions of each part, so that the whole thermal power plant can operate safely, reasonably and economically, reduce labor intensity, improve productivity, and deal with faults quickly and correctly in order to avoid accidents. The main work flow includes steam turbine start-stop, automatic speed up control flow, boiler combustion control flow, fire protection system control flow, thermal measurement and control flow, automatic cutting electrical fault flow, ash and slag removal automatic flow.