Flue gas waste heat utilization system of thermal power plant

Abstract

The invention discloses a flue gas waste heat utilization system of a thermal power plant. The system comprises an air pre-heater, a first heat exchanger, an electric dust collector, a second heat exchanger, a desulfurizing tower and a chimney. The flue gas inlet and outlet of the first heat exchanger are communicated with the flue gas inlet and outlet of the electric dust collector and the flue gas inlet and outlet of the air pre-heater through pipelines respectively, the flue gas inlet and outlet of the electric dust collector are communicated with the flue gas inlet and outlet of the second heat exchanger, and the flue gas inlet and outlet of the desulfurizing tower are communicated with the chimney and the flue gas inlet and outlet of the second heat exchanger respectively; the cold source outlet and inlet of the first heat exchanger are communicated with a cold source device through pipelines; the air inlet of the second heat exchanger is communicated with the air, and the air outlet of the second heat exchanger is communicated with an air inlet of the air pre-heater through a pipeline, and the air outlet of the air pre-heater is communicated with the hearth of a thermal power plant furnace through a pipeline. The system is capable of recovering the flue gas waste heat, desulfurizing water is saved, and power consumption of an air guiding fan and electric dust collector is reduced.

Description

technical field [0001] The invention belongs to the field of thermal power plants, in particular to a waste heat utilization system for flue gas in thermal power plants. Background technique [0002] Thermal power plants use the heat generated by the combustion of fuel such as coal to heat water into steam, and the pressure of the steam drives a steam turbine to do work to generate electricity. [0003] However, in the process of thermal power generation, the flue gas released by fuel combustion contains harmful substances such as dust, carbon dioxide, sulfur oxides, nitrogen oxides, mercury and their compounds. The direct emission of flue gas not only pollutes the atmosphere, but also brings harm to people's health. It may also cause acid rain, photochemical smog, ozone hole, greenhouse effect and other phenomena, further threatening the environment for human survival. Therefore, in recent years, my country has adhered to the principles of low-carbon, clean, and high-effic...

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Problems solved by technology

[0004] But at the same time, in the process of thermal power generation, due to reasons such as low coal mill outlet temperature, insufficient coal fineness, design coal type change, four-pipe scaling, untimely boiler soot blowing, and unreasonable design of the heating surface, etc., the furnace outlet , the outlet of the horizontal flue, the outlet of the economizer, and the outlet of the air preheater are usually at 130°C or even higher, especially when the unit is running at high load in summer, the flue temperature will be too high, and a large amount of heat will be discharged in vain along with the flue gas. In the atmosphere, the heat loss of exhaust smoke increases, which in turn causes a huge heat loss and thermal pollution to the environment, and also causes a lot of waste of desulfurization water

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