Method for removing sulfur oxides and/or nitrogen oxides from flue gas

Abstract

The invention relates to a method for removing sulfur oxides and / or nitrogen oxides from flue gas. The method comprises: introducing an adsorbent into a flue gas adsorbing device while injecting a reducing agent, wherein the adsorbent adsorbs and removes sulfur oxides and partial nitrogen oxides from the flue gas, and simultaneously decomposes and removes the remaining nitrogen oxides to obtain purified flue gas; and introducing the spent adsorbent achieving the saturated adsorbing state into an adsorbent regenerating device, introducing a reducing gas into the adsorbent regenerating device, and at a temperature of 400-700 DEG C, carrying out desorption reduction on the sulfur oxides and / or nitrogen oxides adsorbed on the adsorbent to convert into hydrogen sulfide and nitrogen, wherein theregenerated adsorbent returns to the flue gas adsorbing device so as to be recycled, the reducing agent injected in the flue gas adsorbing device is a urea aqueous solution and / or ammonia gas, and the adsorbent is a catalytic cracking catalyst. According to the present invention, with the method, the reducing agent is injected into the flue gas adsorbing device, and the catalytic cracking regeneration flue gas in the high-temperature and pressure state is directly treated with the adsorbent, such that the removal rates of sulfur oxides and nitrogen oxides are high.

Description

technical field [0001] The invention relates to a method for removing pollutants in industrial flue gas, more specifically, to a method for removing sulfur oxides and / or nitrogen oxides in industrial flue gas at high temperature, which belongs to flue exhaust gas Comprehensive management technology field. Background technique [0002] In the catalytic cracking reaction-regeneration system, the catalyst circulates between the reactor and the catalyst regenerator. Usually, when leaving the reactor, the coke content on the ungenerated catalyst is about 3-10wt%, and the ungenerated catalyst enters the regenerator to burn and deposit The coke recovered catalytic activity, and then returned to the reactor for recycling. The coke deposited on the catalyst is mainly a reaction condensate, and its main components are carbon and hydrogen. When the cracking raw material contains sulfur and nitrogen, the coke also contains sulfur and nitrogen. Coke in the catalyst regenerator reacts w...

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Problems solved by technology

[0005] In the technology announced by CN101209391A, non-special adsorbent is used, and the catalytic cracking catalyst is excavated in the low temperature zone outside the catalytic cracking environment to SO x and NO x Adsorption of potential oxides is beneficial to reduce the cost of chemical agents, but the temperature window is limited to 100-400 °C; and it is difficult to optimize the project implementation when connecting the flue gas processor (adsorber) to the low-pressure area of ​​the flue gas

The two processes share the problems of secondary pollution and corrosive hazards of waste liquid and waste residue, and the first process is also due to the dry removal of NO x SO in process 2 Generate SO 3 side reactions, resulting in salt accumulation on the catalyst bed and blue feathers in the flue gas tail gas to form secondary pollution of the flue gas

[0009] The use of sulfur oxide transfer agent can control the SO in catalytic cracking regeneration flue gas to a certain extent without adding new equipment x , its temperature is 650~750℃ high temperature environment, but the sulfur transfer agent will affect the catalytic cracking reaction, and at the same time SO x The removal rate is relatively low, on the one hand, it cannot reach SO x On the other hand, it still affects the subsequent removal of NO at a slightly lower temperature. x Effect

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