Removing system and removing method for NOx and SOx in FCC regenerated flue gas

Abstract

The invention discloses a removing system and a removing method for NOx and SOx in FCC regenerated flue gas. The removing system comprises a waste heat boiler and a chimney, wherein a removing reaction device is arranged between the waste heat boiler and the chimney; the waste heat boiler comprises a high-temperature evaporation section and a low-temperature evaporation section; the high-temperature evaporation section is communicated with the low-temperature evaporation section through an SCR reactor and a first desulfurizing tower in sequence; the high-temperature evaporation section is communicated with a catalytic cracking regenerator through an overheat section and a three-stage cyclone separator; the low-temperature evaporation section is communicated with the chimney through a coaleconomizer and a second desulfurizing tower in sequence; the first desulfurizing tower is used for removing sulfur trioxide in the flue gas; the second desulfurizing tower is used for removing sulfurdioxide in the flue gas. The flue gas is subjected to denitration treatment before exhaust, and then the sulfur trioxide and the sulfur dioxide are respectively removed, so that on the one hand, removing efficiency of NOx and SOx in the flue gas can be effectively improved, and environmental pollution is avoided; on the other hand, corrosion to equipment caused by an acid solution formed by mixingthe sulfur trioxide with water vapor is effectively avoided.

Description

technical field [0001] The invention relates to the technical field of flue gas emission, in particular to a system for removing NOx and SOx in FCC regeneration flue gas. The present invention also relates to a removal method based on the above removal system Background technique [0002] At present, with the development of the economy and the progress of society, environmental issues have become a hot issue that people pay more and more attention to, especially the environmental protection work of some polluting enterprises. Enterprises need to discharge flue gas during the production process. In order to ensure that the flue gas emission meets environmental protection standards, the flue gas needs to be treated with catalytic cracking (FCC, that is, fluidcatalytic cracking) before the flue gas is discharged. However, a large amount of heat will be released during the catalyst regeneration stage. At the same time Generate SO x , NO x , particulate matter and other pollut...

AI Technical Summary

Problems solved by technology

Sulfur trioxide and water vapor combine to form an acidic aqueous solution on the inner wall of the equipment, which can easily lead to corrosion and cracking of the equipment, and deposit on the surface of the heat exchange element, causing scaling, fouling and corrosion. In addition, the existence of sulfur trioxide will also make the chimney The smoke exhaust produces colored plumes, which are prone to the problems of dust accumulation in the economizer and leakage of the low-temperature economizer

[0003] The Chinese patent "A Method for Dust Removal and Desulfurization of Regenerated Flue Gas from Catalytic Cracking Oil Refinery" (201310199692.2) discloses that sodium alkali and magnesium oxide are used as alkali absorbents to remove SOx from flue gas, but the patent cannot solve SOx 3 The problem that the formed aerosol is difficult to remove

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