Flue gas purification device and method combining photo-catalytic oxidization and double cyclic absorption

Abstract

The invention relates to a flue gas purification device and method combining photo-catalytic oxidization and double cyclic absorption. A first flue gas heat exchanger is arranged in a flue between an air pre-heater and an electrostatic dust remover and is used for conveying a compound oxidizing agent; after the compound oxidizing agent absorbs heat of flue gas to be atomized, the atomized compound oxidizing agent is catalyzed and activated in a photoassisted catalysis and activation reactor, various free radicals are generated and make contact with desulfurized and decarburized flue gas, in-situ oxidization reaction of various pollutants is performed, NO is converted into high-valence-state NOx, HgO is oxidized into Hg2+, NOx and Hg2+ enter a second-stage spraying tower along with the flue gas, supernatant of waste liquid of a first-stage spraying tower is mixed with second-stage absorbing liquid to form composite absorbing liquid, the composite absorbing liquid absorbs and removes NOx and Hg2+, and SO2 and CO2 are further removed; humic acid crystals are obtained through solid-phase drying and crystallizing of the two stages of spraying towers, reaction products including potassium sulphate, potassium carbonate, potassium nitrate, potassium nitrite and other agricultural common-use fertilizer are separated out through flue gas heating and drying of liquid phase, and resource utilization is facilitated.

Description

technical field [0001] The invention belongs to the technical field of flue gas purification, and in particular relates to a flue gas purification device and method with photocatalytic oxidation combined with double-cycle absorption. Background technique [0002] In recent years, due to the substantial increase in the number of power station boilers, industrial boilers and civil boilers, the emission of coal-fired flue gas pollutants has shown explosive growth, resulting in frequent occurrence of smog in my country, seriously endangering people's health and the ecological environment. Coal combustion flue gas pollutants mainly include particulate matter, SO 2 , NOx and trace heavy metals (Hg, As, etc.), and there are also a large number of greenhouse gases such as CO 2 and VOCs. [0003] Compared with industrial boilers and civil boilers, power plant boilers have adopted effective control measures for most of the above-mentioned pollutants. Among them, the mainstream desul...

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Problems solved by technology

From the perspective of ammonia utilization, SCR denitrification is only an expedient measure: ammonia is an important basic raw material in industrial production, and the ammonia synthesis reaction (N 2 +3H 2 =2NH 3 ) is an extremely important chemical reaction with high energy consumption, and in the utilization of ammonia, tens of thousands of tons of ammonia are used for SCR denitrification every year, and the final NH 3 and converted to N 2 , which is equivalent to the secondary consumption of energy, and it is also a huge waste of resources

[0005] In recent years, the ultra-low emission technology represented by the optimized double-cycle desulfurization system has been applied in some power plants. 2 However, the system has less control over other pollutants in coal-fired flue gas

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