What is the principle of thermal power generation

1. Introduction

Due to the shortage of fossil fuels on the earth, human beings are trying to develop nuclear power generation, nuclear fusion power generation and high-efficiency solar power generation, in order to ultimately solve the energy problems faced by human society. The first thermal power generation was achieved in 1875 at the Gare du Nord station in Paris. With the improvement of generator and steam turbine manufacturing technology, the improvement of power transmission and transformation technology, especially the emergence of power system and the demand for electric energy in social electrification, after the 1930s, thermal power generation entered a period of great development. The capacity of thermal power generation units increased from 200 MW to 300 to 600 MW (mid-1950s), and by 1973, the largest thermal power units reached 1300 MW. Large units and large power plants have greatly improved the thermal efficiency of thermal power generation, and the construction investment and power generation cost per kilowatt have also been continuously reduced. By the late 1980s, the world's largest thermal power plant was the Kagoshima Thermal Power Plant in Japan, with a capacity of 4,400 megawatts. However, the unit is too large and brings about a reduction in reliability and availability, so by the early 1990s, the single capacity of thermal power generation was stable at 300 to 700 MW. It accounts for more than 70% of China's total installed capacity. Coal used in thermal power generation accounts for more than 50% of industrial coal. At present, the coal used for power generation and heating accounts for about 50% of the total coal production in China. About 90 percent of the country's sulfur dioxide emissions are generated by coal power, and 80 percent of carbon dioxide emissions are generated by coal power.

According to its function, thermal power generation is divided into simple power supply and both power generation and heating. According to prime mover divided into steam turbine power generation, gas turbine power generation, diesel power generation. According to the fuel used, there are mainly coal-fired power generation, oil-fired power generation, gas power generation. In order to improve the comprehensive economic benefits, thermal power generation should be carried out as close as possible to the fuel base. Cogeneration should be implemented in large cities and industrial areas.

2. Principles

Thermal power generation generally refers to the use of combustible combustion generated by the heat to heat water, so that the water into high temperature, high pressure water vapor, and then by the water vapor to promote the generator to generate electricity. Power plants that use combustible materials as fuel are collectively referred to as thermal power plants.

The main equipment system of thermal power plant includes: fuel supply system, water supply system, steam system, cooling system, electrical system and some other auxiliary processing equipment.

Most thermal power plants use coal as a primary energy source, the use of belt transmission technology, to transport the treated coal powder to the boiler, coal powder combustion heating boiler water into water steam, after a heating, water steam into the high-pressure cylinder. In order to improve the thermal efficiency, the water steam should be heated twice, and the water steam enters the medium pressure cylinder. By using steam from a medium pressure cylinder to push a turbogenerator to generate electricity. The middle pressure cylinder leads into the symmetrical low pressure cylinder. Part of the steam that has been worked is pumped out from the middle section to supply oil refining, fertilizer and other brother enterprises, and the rest of the water flows through the condenser to cool and become saturated water at about 40 degrees Celsius as reuse water. About 40 degrees of saturated water through the condensate pump, through the low-pressure heater to the deaerator, at this time is about 160 degrees of saturated water, through the deaerator deoxygenation, the use of feed water pump into the high-pressure heater, where the high-pressure heater uses reheating steam as heating fuel, and finally flows into the boiler for reuse. This is a production process.

Step 3: Type

According to its role, there are two categories: simple power supply and both power generation and heating (cogeneration thermal power plants).

According to the prime mover, there are mainly turbine power generation, gas turbine power generation, diesel engine power generation (other internal combustion engine power generation capacity is very small).

According to the fuel used, there are mainly coal-fired power generation, oil-fired power generation, gas (natural gas) power generation, garbage power generation (see garbage power station), biogas power generation (see biogas power station) and the use of industrial boiler waste heat power generation.

In order to improve economic benefits, reduce power generation costs, and protect the environment of large cities and industrial areas, thermal power generation should be carried out as close as possible to the fuel base, using high-voltage transmission or ultra-high-voltage transmission lines to transmit powerful electric energy to the load center. Cogeneration should be implemented in large cities and industrial areas.