Flue-gas purifying system for boiler

Abstract

The invention discloses a flue-gas purifying system for a boiler. The flue-gas purifying system comprises a mixed reaction tower and a dust and nitrate filter which are communicated. The flue-gas purifying system is characterized in that flue gas is firstly desulfurized by the mixed reaction tower, then is dedusted and denitrified by the dust and nitrate filter, and the flue-gas flow is firstly dedusted and then is denitrified when passing through the dust and nitrate filter. Therefore, the flue gas is purified according to the sequence of desulfurization, dedusting and denitrification, so that the generation of NH4HSO4 in denitrification of the flue gas is avoided, further ash blocking of an air preheater and corrosion of equipment are avoided, and the catalyst poisoning caused by alkali metal and dust particles in the flue gas is avoided to guarantee the efficiency of denitrifying reaction.

Description

technical field [0001] The invention relates to the technical field of flue gas purification, in particular to a flue gas purification system for a boiler. Background technique [0002] Pollutants emitted by industrial boilers mainly include soot, sulfur oxides, nitrogen oxides, etc. Among them, the existence of sulfur oxides will cause corrosion of power station equipment, increase of flue gas opacity, formation of acid rain, etc., and will be discharged into the air It can also cause respiratory diseases in humans. [0003] At present, commonly used industrial boiler flue gas treatment systems such as figure 1 as shown, figure 1 It is a structural schematic diagram of the flue gas purification system in the prior art, and its flue gas treatment process route is: after the flue gas from the boiler 1' is discharged from the economizer 8', it enters the denitrification reactor 3', and the ammonia water injector 31' sprays the ammonia water Into the denitrification reactor ...

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Problems solved by technology

[0004] When the flue gas flows through the above-mentioned flue gas purification system, the denitration reaction is carried out first, and then the dust removal and desulfurization reactions are carried out. This process has the following disadvantages: the catalyst in the denitrification reactor 3' will make the SO in the flue gas 2 is oxidized to SO 3 , SO 3 with escaped NH 3 Generate NH 4 HSO 4 and (NH 4 ) 2 SO 4 , NH 4 HSO 4 It is corrosive and viscous, which can lead to blockage of the air preheater 2' and corrosion of subsequent equipment. At the same time, it can also cause catalyst poisoning and affect the efficiency of denitrification reaction

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