Desulfuration and mercury-removing combined smoke purifying process and system based on magnesium oxide method desulfuration process

Abstract

The invention discloses a desulfuration and mercury-removing combined smoke purifying process and system based on a magnesium oxide method desulfuration process. The desulfuration and mercury-removing combined smoke purifying process comprises the steps of: improving a pre-washing tower in the magnesium oxide method desulfuration process, circularly spraying original smoke by adopting a halogen oxidant solution to realize full oxidization of elementary substance mercury Hg0 in smoke; transforming oxidized gas-phase bivalent mercury ions into liquid-phase bivalent mercury ions through an improved wet-type magnesium oxide method desulfuration process; and transforming the liquid-phase bivalent mercury ions in a wastewater treatment system into a stable mercuric sulfide precipitate through adding a mercury stabilizing agent. The system mainly comprises the pre-washing tower, a desulfuration tower, a cyclone separator, a vacuum belt fulter, a wastewater basin and a sedimentation basin, wherein the pre-washing tower is used for preparing a mercury oxidant and a magnesium oxide solution and oxidizing mercury; the desulfuration tower is used for carrying out desulfuration and mercury removal on smoke; the cyclone separator and the vacuum belt fulter are used for treating side products; and the wastewater basin and the sedimentation basin are respectively used for treating wastewater and the mercuric sulfide precipitate. The process can be used for effectively removing divalent mercury and elementary substance mercury in the smoke on the premise of ensuring the advantages of the magnesium oxide method desulfuration process, and is suitable for reconstructing the traditional magnesium oxide method desulfuration process.

Description

technical field [0001] The invention relates to a flue gas purification process, in particular to a combined desulfurization and demercuration flue gas purification process and system based on a magnesium oxide desulfurization process, which belongs to the field of environmental protection. Background technique [0002] Coal is an unclean energy source that releases various pollutants during combustion. At present, the control of coal-fired flue gas pollutants mainly focuses on dust control, SO 2 control, NOx control. Mercury is a poisonous trace element in coal. Mercury pollution is extremely harmful to human beings and the biological environment. Mercury pollution from coal burning has become another major pollution problem recognized around the world after coal burning sulfur pollution. [0003] Mercury in the flue gas of coal-fired power plants is mainly in the form of elemental mercury (Hg 0 ), oxidized mercury (Hg 2+ ) and particulate mercury (Hg p ) exist in thre...

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Problems solved by technology

[0005] The invention patent with the publication number CN 101310834A mentions the staged desulfurization and mercury removal process suitable for the lime/limestone-gypsum method, but in this process, the raw flue gas first passes through the desulfurization absorption tower, and then enters the secondary desulfurization and mercury removal absorption after desulfurization In the tower, on the one hand, due to the low temperature of the flue gas after desulfurization, after entering the secondary absorption tower for desulfurization and mercury removal, the temperature of the flue gas is greatly reduced, and the flue gas discharge needs to be heated again, resulting in energy loss. The flue gas is directly discharged after the mercury removal method, which will cause highly corrosive liquid droplets to be entrained in the flue gas, which will have a great impact on the operation and maintenance of the equipment.

The invention patent with publication number CN 101157003A proposes a combined de

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