An environment-friendly and pollution-free tail gas purification device in the production of chlorinated benzene

Abstract

The invention provides a tail gas purification device in the environment-friendly pollution-free chlorobenzene production. The tail gas purification device comprises N stages of purification units; anumber m stage purification unit in the N stages of purification units comprises a number m benzene absorption device and a number m hydrogen chloride absorption device; the number m benzene absorption device comprises a number m benzene absorption tower, a number m benzene circulation tank and a number m benzene circulation pump; and the number m hydrogen chloride absorption device comprises a number m hydrogen chloride absorption tower, a number m hydrogen chloride circulation tank and a number m hydrogen chloride circulating pump. Second-stage tail gas containing benzene and chlorinated benzene sequentially passes through the N stages of purification units, organic gas of the benzene and chlorinated benzene, and hydrogen chloride gas are completely absorbed, and the remaining inert gasis emptied in a high position. The characteristics of absorption and adsorption operation of two units are fully utilized; the absorption operation is suitable for large-component-concentration operation, the processing amount is large, and the energy consumption is low; and the adsorption operation can further reduce the content of organic matters in the tail gas, so that the tail gas is up to the emission standard.

Description

technical field [0001] The invention relates to the technical field of chlorinated benzene tail gas equipment, in particular to an environment-friendly and pollution-free tail gas purification device in the production of chlorinated benzene. Background technique [0002] Chlorinated benzene is a basic organic chemical raw material. The main raw materials are benzene and chlorine gas. After drying, pure benzene undergoes a chlorination reaction with chlorine gas in a chlorinator through the action of a catalyst. The acidic chlorinated liquid obtained after the reaction is dehydrated, Alkali washing treatment, after drying, enter the crude and rectification tower for distillation to obtain the finished chlorinated benzene. The production of chlorinated benzene is the chlorination of benzene in a boiling state, and the product contains chlorinated benzene and hydrogen chloride gas. Due to the high-temperature continuous chlorination process, the removal of reaction heat is rea...

AI Technical Summary

Problems solved by technology

Due to the high-temperature continuous chlorination process, the removal of reaction heat is realized by the evaporation and gasification of benzene, so the generated tail gas mainly contains hydrogen chloride gas, benzene vapor and a small amount of chlorinated benzene vapor. Direct discharge will not only cause waste of resources, but also affect the environment. serious pollution

In the existing technology, the falling film circulation tank is replaced with fresh absorption liquid every eight hours. During the refueling process, the benzene content in the tail gas is unstable, and the highest can rise to several hundred ppm, which has a great impact on the safety and energy consumption of the subsequent system.

The falling film tail gas enters the hydrochloric acid absorption system and is absorbed by washing wastewater mixed with tap water. The water contains acid and the water volume is difficult to control. The three absorption towers are distributed in order from high to low. When it is thick, it is thin and unstable; the tail gas is directly emptied after passing through the last-stage packed tower. The tail gas often contains a large amount of HCl gas and benzene vapor. After analysis, the second-stage tail gas produced by chlorinated benzene contains 2000-6000ppm of benzene, which is not only harmful to the environment. Pollution has also caused great harm to employees, and it has been difficult to effectively solve it

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