Coke oven flue gas desulfurization, denitrification and dust removal system with waste gas circulation function and method thereof

Abstract

The invention particularly relates to a coke oven flue gas desulfurization, denitrification and dust removal system with a waste gas circulation function and a method thereof. According to the processthat dry desulfurization is carried out firstly, then integrated dust removal and denitration are carried out, and gas obtained after desulfurization, denitration and dust removal is recycled to control the gas before combustion, the emission indexes of NOx, SO2 and dust of the coke oven flue gas can meet the requirements of ultralow emission indexes correspondingly; ammonia evaporation and ammonia gas mixing adopt circulating purified coke oven flue waste gas subjected to desulfurization and denitrification, waste heat of the flue waste gas is fully recycled, energy is greatly saved, meanwhile, ammonia gas is diluted and mixed into purified flue gas, the situation that redundant air is brought into an ammonia gas mixing form by adopting air is avoided, and stabilization of emission indexes is better facilitated; sodium sulfate and sodium sulfite generated in the desulfurization section are filtered on the surface layer of a catalyst when passing through a denitration reaction device,a compressed air system is used for back flushing and ash removal, blown accumulated ash and particles are fed into a bottom ash bin and are recycled and treated in a centralized mode, and the service life of the dust removal and denitration equipment is prolonged.

Description

Technical field [0001] The invention relates to the technical field of ultra-low emission of coke oven flue gas desulfurization, denitrification and dust removal, in particular to a coke oven flue gas desulfurization, denitrification and dust removal system and method with exhaust gas circulation. Background technique [0002] In the coking industry, when coke oven gas is burned to heat the coke oven, a large amount of air pollutants, including SO2, NOx, and soot, etc., are generated. Such pollutants are continuously discharged into the atmosphere through the coke oven chimney as an organized elevated point source. The environment causes pollution and seriously endangers human health. Therefore, coke oven flue gas desulfurization, denitration and dust removal is imperative. After recent years of development, the mainstream technology for desulfurization is dry desulfurization, and the mainstream technology for denitration is pre-combustion control technology and combustion Post-c...

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Problems solved by technology

[0003] Chinese patent CN103816780B discloses an integrated process for low-temperature flue gas desulfurization, denitrification and ammonia removal, which is suitable for flue gas temperatures greater than 180°C, SO 2 Content less than 150mg / Nm 3 The desulfurization and denitrification of coke oven flue gas, which adopts the process of dry desulfurization first and then SCR denitrification. This invention uses the composite structure of bag-ammonia removal catalyst as the means of dust removal and denitrification. According to the national emission standard value, the cloth bag-ammonia removal catalyst composite structure is a high temperature resistant filter bag on the outer surface + an ammonia removal catalyst layer in the middle layer + a filter material skeleton in the inner layer, but the filter bag with this composite structure has poor wear resistance and long service life. short, needs to be replaced frequently

[0004] Chinese patent CN103816796B discloses a low-temperature coke oven flue gas desulfurization and denitrification process, by spraying fluidized NaHCO into the flue gas conveying pipeline 3 Fine powder dry method to remove most of SO in waste gas 2 At the same time, the denitrification catalyst structural layer is used in combination with the ammonia removal catalyst structural layer to efficiently remove NOx in the coke oven flue gas. The denitrification catalyst adopts a filter cartridge structure, and its structure is similar to the filter bag in the bag filter. The filter cartridge is processed by a catalyst, and the pores of the catalyst are PM2.5 micropores. The preparation process of the filter cartridge-shaped catalyst is relatively difficult, so the catalyst is expensive

[0005] Chinese patent CN108854529A discloses an integrated emission purification device for coke oven flue gas, dust, sulfur and nitrate, which effectively integrates traditional dry desulfurization, filter dust removal and low-temperature SCR denitrification, and uses ceramic catalytic filter tubes as the processing core The ceramic catalytic filter reactor was first applied in the field of coke oven flue gas treatment, which can make the emission indicators of coke oven flue gas NOx and dust reach 50mg / Nm respectively 3 and 5mg / Nm 3 The ultra-low emission index requirements, the process uses a Venturi mixer to strengthen the mixing effect of flue gas and desulfurizer, installing a Venturi mixer on the coke oven flue will increase the flue resistance and increase the fan load

[0008] To sum up, there are some advantageous technologies for coke oven flue gas desulfurization, denitrification, and dust removal, including dry desulfurization, SCR denitrification, ceramic fiber dust removal, and pre-combustion control of exhaust gas circulation. However, flue gas desulfurization, denitrification, Dust removal and pre-combustion control of exhaust gas circulation The technology of coupling several technologies has not yet been patented

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