Energy-saving and high-quality ammonia desulphurization process for ammonia sulfate recovery

Abstract

The invention belongs to flue gas desulphurization technology of the environmental protection field. To solve the problems of large energy consumption, lower product quality and large investment in recovering ammonia sulfate by an ammonia desulphurization technique, the invention provides an energy-saving and high-quality ammonia desulphurization process for ammonia sulfate recovery. The process adopts ammonia water as a desulfurizer, ammonium sulfite is produced after the ammonia water and flue gas are decarbolized completely, and ammonia sulfate is produced after the ammonium sulfite is forcibly oxidized in a tower; impurities in the ammonia sulfate solution is removed by filtering, the filtrate is contacted with high-temperature flue gas in a desulfurizing tower for heat exchange, and when flue gas is cooled, the ammonia sulfate solution is heated and saturated; and then after crystallization of the saturated ammonia sulfate solution for a period of time, high-quality ammonia sulfate is produced after centrifugal drying. By adopting the technical proposal of the invention, not only thermal energy of an ammonia sulfate product which is produced by drying process can be greatly saved, high-quality ammonia sulfate fertilizer can be recovered, occupation area can be reduced and investment can be save, but also flue gas emission can meet the standard, without resulting in secondary pollution such as waste water and the like.

Description

technical field [0001] The invention relates to air pollution control and desulfurization technology in the field of environmental protection, in particular to an ammonia desulfurization process for energy-saving and high-quality ammonium sulfate recovery. Background technique [0002] In recent years, my country's annual sulfur dioxide emissions have reached more than 20 million tons, ranking first in the world, and it has become the third largest acid rain area after Europe and North America. If sulfur dioxide is not controlled, urban air pollution will increase. Therefore, the control of sulfur dioxide emissions has become an urgent requirement for social and economic sustainable development, and it is imperative to control sulfur dioxide. [0003] Boilers or thermal power plants fueled by coal or petroleum, and sintering machines in iron and steel plants that use iron ore as raw materials emit a large amount of flue gas, and SO in the flue gas 2 The content is usually ...

AI Technical Summary

Problems solved by technology

[0006] 1) The circulating fluid contains SO 2 Ammonium sulfite with absorption function also contains a large amount of ammonium sulfate, and ammonium sulfate has a strong effect on SO 2 No absorption capacity, thus causing a large amount of ammonium sulfate solution to participate in empty circulation

On the one hand, it causes a large consumption of circulation pump power and increases the operating cost; on the other hand, due to the circulation of a large amount of ammonium sulfate solution in contact with the flue gas, the temperature loss of the flue gas discharged after purification and desulfurization is serious, and the exhaust gas temperature is too low (< 50°C), the water-saturated low-temperature flue gas will cause serious corrosion damage to the chimney for a long time, and the desulfurized flue gas has to be added to the GGH reheating system to raise the temperature to about 80°C before entering the chimney, resulting in investment and operating costs. further increase

[0007] 2) This technology oxidizes the ammonium sulfite product after desulfurization into ammonium sulfate in the desulfurization tower. Since the desulfurization product contains a large amount of ammonium sulfate, the existence of a large amount of ammonium sulfate hinders the oxidation of ammonium sulfite, and the oxidation rate reaches 80~ 90% is very difficult, so the ammonium sulfate product recovered in the latter stage contains a large amount of ammonium sulfite that has not been oxidized; ammonium sulfate product is used as a raw material for agricultural chemical fertilizer or compound fertilizer, and has fertilizer effect; while ammonium sulfite product has no fertilizer effect , if it is used in farmland, there will be burning of seedlings, causing accidents and serious consequences. Therefore, the quality of ammonium sulfate recovered by this method is low

[0008] 3) This technical method adopts the method of conventional evaporative drying to the removal of moisture in the product ammonium sulfate solution after desulfurization, which needs to consume a large amount of steam energy, and the average evaporation of each ton of water requires about 2 tons of steam; according to the current cost price, about The steam cost of 100 yuan is required, which is a huge expense for the long-term operation of large-scale power plant boilers. Therefore, the operation cost of extracting by-product sulfuric acid by this technology is very high, and the energy consumption is large

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