Ultralow emission treatment system and method for coke oven flue gas

Abstract

The invention provides a novel comprehensive treatment system and method for coke oven flue gas desulfurization, denitration, dust removal, waste heat utilization and white smoke elimination. The system and method have the characteristics that desulfurization byproducts can be utilized, secondary waste is avoided, the operation stability is high, the service life of a catalyst is long, the problems of white smoke trailing and the like are avoided, and the operation cost is low. The ultralow emission treatment system for the coke oven flue gas comprises a wet desulphurization device and a denitration device, wherein the wet desulphurization device is used for removing SO2 and smoke dust in coke oven flue gas, the denitration device is used for removing NOx in the coke oven flue gas, and thedenitration device is located at the downstream of the wet desulphurization device. According to the invention, a scheme of first desulfurization (and dust removal) and then denitration is adopted, so that the negative effects of SO2, smoke dust and tar on a denitration catalyst and subsequent waste heat boiler equipment are eliminated.

Description

technical field [0001] The invention belongs to the field of coking, and in particular relates to a coke oven flue gas ultra-low emission control system and method. Background technique [0002] Generally, flue gas has similar characteristics, containing SO 2 , NO x (nitrogen oxide) and dust, etc., all need desulfurization, denitrification and dust removal. However, the source differs in its content and composition of other pollutants, especially in temperature. The desulfurization, denitrification and dust removal of boiler flue gas are very mature, and can generally meet ultra-low emission standards (under 6% oxygen content, SO 2 ≤35mg / Nm 3 , NO x ≤50mg / Nm 3 , Dust≤10mg / Nm 3 ). In addition, in some urban areas or densely populated areas, there are temperature requirements for boiler flue gas emissions, and the exhaust gas temperature is required to be greater than 70-80°C to reduce the impact of white smoke pollution. [0003] However, in the field of coking, the ...

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Problems solved by technology

[0013] As far as the coupling method of flue gas desulfurization and denitrification is concerned, the above patent applications disclose a method of denitrification first and then desulfurization. This method has two problems: the first problem is the soot and tar in the coke oven flue gas It will stick to the catalyst, block the honeycomb holes, and increase the resistance of the reactor; the second problem is that there is a boiler with waste heat between the denitrification device and the desulfurization device, and it is easy for the boiler heat exchange tube to adhere to ammonium bisulfate, resulting in heat transfer. The problem of boiler blockage due to reduced efficiency eventually led to shutdown and high-pressure water flushing, which affected the stability and safety of production

In addition, if the post-desulfurization method adopts the wet method, because the exhaust gas temperature is low and the humidity of the flue gas is high, the problem of white smoke pollution usually occurs.

[0014] For this reason, there is also a coupling method that desulfurizes first and then denitrates. However, due to the high temperature of the flue gas, the traditional calcium desulfurization technology cannot be used, so sodium carbonate or sodium bicarbonate can only be used as the desulfurization reagent to obtain the desulfurization of sodium sulfate. By-products, such as Chinese patent applications CN105214478A, CN106731585A, CN206730850U, CN106925108A, CN207838677U, CN208066118U, CN108201781A, etc.

The disadvantage of this type of technology is that the price of desulfurizer is high and the use of by-products is small

[0015] It can be seen that the existing technology has problems such as high cost, difficult to reuse by-products, poor operation stability, short catalyst life, white smoke tailing, etc. Therefore, it is of great significance to develop a new coke oven flue gas comprehensive treatment and waste heat utilization technology

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