A method and device for recovering NO2 and SO2 in flue gas by rectification

Abstract

The invention mainly belongs to the field of rectification and separation of low-temperature chemical gas, and particularly relates to a method and device for rectifying and recovering NO2 and SO2 influe gas. The method combines a high-pressure rectification operation process and a low-pressure rectification operation process, high-pressure rectification of a first rectification tower can reducea relatively low boiling point caused by relatively low partial pressure of NO2 and SO2, and normal-pressure rectification of a second rectification tower ensures the relatively low separation difficulty of NO2 and SO2; by using the semi-continuous rectification method, the liquid holdup in the tower bottom of a first rectification column reaches 50-90%, then liquid enters the second rectificationtower for rectification, and the second rectification tower is controlled well; and meanwhile, the device has an anti-corrosion function.

Description

technical field [0001] The invention mainly belongs to the field of rectification and separation of low-temperature chemical gas, and specifically relates to a rectification recovery of NO in flue gas. 2 and SO 2 methods and devices. Background technique [0002] my country is a big coal-burning country in the world. Coal accounts for about 75% of my country's energy. Coal-burning can produce a lot of NO X and SO 2 . Currently SO 2 The treatment mainly includes three categories: wet method, semi-dry method and dry method. In recent years, electron beam flue gas desulfurization technology, pulse corona discharge flue gas desulfurization technology, membrane absorption method, microbial desulfurization technology, etc. have been developed. But they are all in the experimental stage. At present, flue gas denitrification technologies are mainly put into production, such as selective catalytic reduction (SCR), selective non-catalytic reduction (SNCR), and SNCR-SCR combined ...

AI Technical Summary

Problems solved by technology

Therefore, in terms of cryogenic gas distillation, there is currently no NO 2 and SO 2 In terms of flue gas pollutant treatment, the main idea of ​​existing flue gas resource utilization is transformation and removal rather than recovery. For example, SCR denitrification removes NO by spraying ammonia X react to N 2 and H 2 0, to achieve pollution-free treatment, but can not recover NO X Resources; the calcium method, magnesium method, sodium method, ammonia method and organic alkali method of FGD flue gas desulfurization technology are also converted into corresponding sulfates and sulfites by adding other substances, and converted from gas resources to solid resources, but low yield and high cost

[0005] In addition, there are the following technical problems in the prior art: (1) The separation of gases in the current rectification tower is mainly to separate some common gases such as air, hydrocarbon gas, natural gas to remove acid gas, and to separate isotopes, etc., and there are almost no rectification towers that can deal with NO 2 and SO 2 This acidic corrosive gas system; (2) The current low-temperature rectification is either pure low-pressure rectification such as air separation, or pure high-pressure rectification such as natural gas removal of CO 2 , the requirements for the component concentration of the feed gas are relatively high, and generally require a high concentration of the main components of the rectification; (3) Most of the current low-temperature rectification devices are continuous rectification, with continuous feed and output

Images