Cement kiln flue gas NOx ultra-low emission method and system

Abstract

The invention discloses a cement kiln flue gas NOx ultra-low emission method and system. The method comprises the steps that flue gas from a cement rotary kiln sequentially enters a decomposing furnace, a five-stage cyclone preheater, a waste heat boiler, a raw mill and a kiln tail dust collector through a kiln tail smoke chamber; the flue gas is sequentially treated by the decomposing furnace, the five-stage cyclone preheater, the waste heat boiler, the raw mill and the kiln tail dust collector, then is detected by a second CEMS, and finally is discharged by a kiln tail chimney; low-nitrogen transformation is carried out on the front section where the kiln tail smoke chamber and the decomposing furnace are located; intelligent SNCR ammonia spraying transformation is carried out on the middle section where the decomposing furnace and the five-stage cyclone preheater are located; and SCR denitration transformation is carried out on an outlet of a C1-stage preheater of the five-stage cyclone preheater and the tail section where the waste heat boiler is located. According to the method and system, by effectively combining the efficient low-nitrogen transformation technology, the intelligent SNCR denitration technology and the SCR denitration technology, ultra-low emission is achieved, meanwhile, the construction and operation cost of a denitration system is reduced, the ammonia water consumption is reduced, the ammonia emission concentration is reduced, and the usage amount of a catalyst is reduced.

Description

technical field [0001] The invention relates to the technical field of cement kiln flue gas treatment, in particular to a method and system for realizing ultra-low emission of NOx from cement kiln flue gas. Background technique [0002] Since the thermal power and iron and steel industries have fully implemented ultra-low emission transformation, NO x Implement 50mg / m 3 At the same time, the cement industry implements the "Emission Standard of Air Pollutants for the Cement Industry" (GB4915-2013), and the NOx emission limit is 400mg / m 3 (Special emission limit 320mg / m 3 ), the NOx emission per unit flue gas volume is 6.4-8 times that of thermal power and iron and steel industries, NO x The total emissions have leapt to the top of the total emissions from industrial pollution sources, and the pressure to reduce emissions is huge. The emission standards of air pollutants in the cement industry continue to be tightened. Henan Province and Hebei Province have officially issu...

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Problems solved by technology

[0003] At present, for cement kiln flue gas NOx emission concentration 3 The technology is relatively mature, but it needs to be further tightened to 50mg / m 3 , there are problems in the accessibility and stability of NOx indicators, ammonia emission concentration control, ammonia water consumption, construction and operation costs, etc., and there is no good response to cement kiln NOx emission concentration 3 patented technology

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