A device and method for double-circuit flue gas purification

Abstract

The invention relates to a double-loop flue gas purification device and method. Flue gas subjected to dust removal undergoes heat exchange of a heat exchanger and then enters a first-stage absorption tower to perform acid-base neutralization and absorb SO2, CO2, HCl and HBr, then the flue gas enters a second-stage absorption tower to perform multi-pollutant oxidation reaction, NO in the flue gas is converted into highly-charged NOx, Hg<0> is oxidized into Hg<2+>, the NOx and the Hg<2+> are absorbed and removed, and meanwhile the SO2, CO2, HCl and HBr are further absorbed and removed. First-stage absorption waste liquid supernate and second-stage absorption liquid are mixed to serve as the absorption liquid of the second-stage absorption tower, second-stage absorption is strengthened while secondary utilization, the precipitate of first-stage absorption waste liquid and the second-stage absorption liquid are fed into a liquid-solid separator to perform liquid-solid separation, humic acid crystals are obtained through solid phase drying and crystallization, a liquid phase is delivered to the heat exchanger to dissolve out salts through heating and drying of flue gas waste heat, including potassium sulfate, potassium nitrate, potassium nitrate, potassium carbonate and other agricultural fertilizers, and product resource utilization is achieved.

Description

technical field [0001] The invention belongs to the technical field of flue gas purification, and in particular relates to a double-circuit flue gas purification device and method. 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 smog in my country, which seriously endangers people's health and the ecological environment. Coal combustion flue gas pollutants mainly include particulate matter, SO 2 , NOx, a small amount of HCl and HBr, trace heavy metals (Hg, As, etc.), and coal-fired flue gas also contains a large amount of greenhouse gases such as CO 2 and VOCs. For the above pollutants, most industrial boilers and civil boilers do not have mature flue gas pollution control technologies. [0003] Power plant boilers have adopted effective control measures for most of the...

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Problems solved by technology

[0006] Aiming at the deficiencies of the existing technology, the present invention intends to optimize and improve the traditional dual-loop system, and strive to realize the efficient, coordinated removal and resource utilization of multiple pollutants in coal-fired flue gas by optimizing the dual-loop system, thereby avoiding the original SCR denitrification System, activated carbon injection mercury removal system, ionic liquid carbon capture system and tail wet electrostatic precipitator and other series-level arrangement of flue gas pollutant control systems

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