Wet flue gas advanced comprehensive treatment system and method for energy and water saving-type coal-fired boiler

Abstract

The invention discloses a wet flue gas advanced comprehensive treatment system for an energy and water saving-type coal-fired boiler. The wet flue gas advanced comprehensive treatment system comprisesan absorption heat pump, an air pre-heater, a coal economizer, an electric dust remover, an induced draft fan, a gas cooler, a desulfurization absorption tower, a flue gas condenser and a flue gas reheater, wherein the air pre-heater, the coal economizer, the electric dust remover, the induced draft fan, the gas cooler, the desulfurization absorption tower, the flue gas condenser and the flue gasreheater are sequentially communicated between a flue gas outlet of the tail portion of the boiler and a flue gas inlet of a chimney. A water outlet of the flue gas condenser communicates with a water inlet of the coal economizer. The absorption heat pump communicates with the coal economizer, the gas cooler, the flue gas condenser and the flue gas reheater. The invention further discloses a wetflue gas advanced comprehensive treatment method for the energy and water saving-type coal-fired boiler. By adoption of the method, recycled boiler flue gas waste heat is used for driving the absorption heat pump, and the saturated wet flue gas waste heat of a desulfurization absorption tower outlet is recycled; and meanwhile water vapor in the saturated wet flue gas of the desulfurization absorption tower outlet is condensed and recycled and zero-water-replenishing operation of the desulfurization system is realized. Meanwhile, multiple sorts of pollutants can be removed, and 'gypsum rain' and 'misty rain' nearby a chimney outlet can be treated.

Description

technical field [0001] The invention relates to the technical field of comprehensive utilization of industrial waste gas waste heat and pollutant treatment, in particular to an energy-saving and water-saving coal-fired boiler wet flue gas deep comprehensive treatment system and method. Background technique [0002] According to the statistics of China Electricity Council, about 97% of my country's coal-fired power generation units adopt wet desulfurization process (WFGD), including limestone-gypsum wet process, seawater process, ammonia process, sodium nitrite cycle process, magnesium oxide process, double alkali process Among them, the limestone-gypsum wet desulfurization process is the main one, accounting for about 91% of the coal-fired power units. Coal-fired boilers are affected by the low-temperature corrosion of the heating surface at the tail and the equipment. The exhaust gas temperature is generally controlled at 110°C to 160°C. In the wet desulfurization process, t...

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Problems solved by technology

However, this technology cannot remove the moisture content of wet flue gas, and may even increase the moisture content of wet flue gas, aggravating the white "smoke plume" phenomenon of the chimney, and has limited removal effect on heavy metals, trace elements and other pollutants; at the same time, wet electric Dust removal takes up a lot of space, high investment costs, and relatively high operating costs

[0005] The wet phase-change condensation dedusting system has a high removal efficiency for 0.1-1μm particles, which can be added directly after the wet desulfurization equipment, but the disadvantage of this technology is that it needs an additional cooling medium to cool the flue gas. Generally, the traditional wet desulfurization system is used Closed circulating water cooling water system, auxiliary cooling system requires large investment and difficult layout. While condensing water vapor in the flue gas, the cooling water system needs to consume at least the same amount of water resources as evaporation and sewage discharge. At the same time, the circulating water system needs to consume a certain amount of water. energy, higher operating costs

In addition, the cooled flue gas is still at the saturation temperature at the corresponding temperature, which cannot completely eliminate the white "smoke plume" phenomenon, which is not conducive to the lifting and diffusion of the flue gas

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