System and method for lowering HCL content in pickling flue gas

Abstract

The invention discloses a system and method for lowering the HCL content in pickling flue gas. The system comprises a primary acid fog purification tower for primary purification of imported flue gasand a secondary acid fog purification tower for secondary purification of flue gas obtained after treatment of the primary acid fog purification tower. The system further comprises a water replenishing conveying mechanism performing circulating water replenishing on the primary acid fog purification tower and the secondary acid fog purification tower and an alkali liquor adding mechanism for adding alkali liquor to the secondary acid fog purification tower. Accordingly, by controlling the source to lower acid consumption and controlling the process to increasing the absorbing amount of an acidfog washing tower to HCL in exhausted flue gas, and finally the purpose of continuously lowering the content of the HCL in the exhausted flue gas is achieved.

Description

technical field [0001] The invention belongs to the technical field of environmental protection emission treatment in metallurgical processes, and in particular relates to a system and method for reducing HCL content in pickling flue gas. Background technique [0002] With the gradual improvement of people's awareness of environmental protection, environmental protection has attracted more and more attention from all over the country. The level of environmental protection has become an important part of steel companies' competitiveness, and it will also become an important issue that steel companies must attach great importance to. [0003] At present, the silicon steel plant has the following problems: 1. During the production of the pickling unit in the silicon steel plant, the regenerated acid (or new acid) is conveyed for 6m for every 100 tons of silicon steel produced according to the process requirements. 3 To the 4# circulation tank, and overflow to the 3#, 2#, 1# cir...

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Problems solved by technology

[0003] At present, the silicon steel plant has the following problems: 1. During the production of the pickling unit in the silicon steel plant, the regenerated acid (or new acid) is transported for 6m for every 100 tons of silicon steel produced according to the process requirements. 3 To the 4# circulation tank, and overflow to the 3#, 2#, 1# circulation tank in turn, when the concentration of the acid solution in the 1# circulation tank is reduced to waste acid after detection, start the waste acid pump to discharge the waste acid to the acid regeneration station At the same time, the new acid pump in the acid tank area starts to supply new acid to the 4# circulating tank

This intermittent acid supply mode has a big disadvantage, that is, the quality of on-site pickling is unstable. In order to ensure the pickling effect of strip steel, the concentration of acid supply for acid regeneration is relatively high, and the acid consumption is high.

2. The acid mist scrubber is a first-stage tower and a second-stage tower connected in series, and the circulating water at the bottom of the two towers is connected. Although the HCL content in the exhausted flue gas meets the environmental protection standard, there is sometimes a little sour taste in the smoke that needs to be improved.

3. In order to prevent the settlement and rupture of the pickling smoke extraction pipeline, the original design has 5 outlets. After the acid mist condenses, it is directly discharged into the trench. The sour smell is obvious in the trench area on site, and the pH value of the acid mist condensate is less than 1. Add alkali to neutralize The back row enters 301 water treatment, which not only affects the on-site production environment but also increases the burden of 301 water treatment station

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