Flue gas purification method combining photocatalytic oxidation with double-cycle absorption

Abstract

The invention belongs to the technical field of flue gas purification, and discloses a microwave coupling ultraviolet photocatalytic oxidation desulfurization and denitration method. The method comprises the steps that NO gas and SO2 gas are mixed and diluted by nitrogen and oxygen and enter a SO2 pre-absorption system to remove the SO2 preliminarily, then the gases enter a microwave reactor whichsupplies microwaves and excites an inorganic lamp, and the temperature is raised simultaneously in the process to improve the oxidation efficiency of a liquid phase oxidizing agent; subsequently, a liquid phase composite oxidizing agent is subjected to catalyzed activation in a photocatalytic reactor, a variety of highly active free radicals are produced, and then the highly reactive free radicals oxidize NO; the newly formed nitrogen oxides are absorbed by a subsequent absorption device; and exhaust gas after absorption is finally discharged into the atmosphere. The microwave coupling ultraviolet photocatalytic oxidation desulfurization and denitration method can meet the latest ultra-low emission pollutant standards of thermal power plants. The treatment system is lower in capital construction and operation costs, can simultaneously perform desulfurization and denitrification process, reduces floor space, and is easy to operate, and the desulfurization and denitration effect is morerapid and efficient.

Description

technical field [0001] The invention belongs to the technical field of flue gas purification, and in particular relates to a method for catalytic oxidation desulfurization and denitration of microwave coupled ultraviolet light. Background technique [0002] Coal-fired power plants release a lot of NO and SO during coal-fired power generation 2 Such toxic gases have caused serious adverse effects on humans and the environment. China is a big coal-burning country, NO and SO 2 and other toxic gas pollution is extremely serious, so the Chinese government has promulgated the "Air Pollutant Emission Standard for Thermal Power Plants" (GB 13223-2011) to reduce NO X , SO 2 , emissions. On July 27, 2014, a new ultra-low emission concept was implemented, that is, the emission concentrations of soot, sulfur dioxide and nitrogen oxides (baseline oxygen content of 6%) did not exceed 5mg / m2 respectively. 3 , 35mg / m 3 , 50mg / m 3 . Therefore, it is very necessary to seek an efficien...

AI Technical Summary

Problems solved by technology

However, these technologies still have some disadvantages in application, such as high cost, high energy consumption for free radical excitation, and by-products such as toxic gases may be produced during the process.

[0004] According to the research of other researchers, the oxidation method has been proved to be one of the effective ways to remove NO, the key is to oxidize NO into water-soluble NO 2 , the oxidants that can be used include hydrogen peroxide, sodium persulfate, sodium chlorite and some free radicals, and ozone is also a very effective substance for oxidizing NO, which can oxidize it in a short time ( less than one second), but further improvement is needed due to the large energy consumption required for conventional ozone generation

[0005] In order to reduce the problems of high cost and large floor space of the existing SCR denitrification system, the present invention strives to achieve efficient oxidation of NO in coal-fired flue gas through microwave coupling with ultraviolet light. X , SO 2 common removal, and the removal products are recycled and reused

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