Benzene chloride tail gas recovering and purifying method

Abstract

The invention discloses a benzene chloride tail gas recovering and purifying method. With the method, benzene consumption in benzene chloride technologies can be greatly reduced, and discharged tail gas can reach a ppm grade. Therefore, substantial economic and environment benefits are brought in. The benzene chloride tail gas recovering and purifying method provided by the invention comprises steps that: tail gas containing benzene chloride is processed by using a washing unit and an alkali washing unit, and is delivered into a benzene absorbing unit by using a blower; the tail gas is then delivered into a temperature swing adsorption system containing an absorbent; benzene and benzene chloride organic gas is absorbed by the absorbent, and other inert gas reaches a discharging standard and is discharged. According to the invention, the absorbent in the benzene absorbing unit is benzene chloride.

Description

technical field [0001] The invention relates to a method for recovering and purifying tail gas, in particular to a method for recovering and purifying chlorinated benzene tail gas. Background technique [0002] Chlorinated benzene is an important intermediate in dyes, medicines and organic synthesis, and one of the important organochlorine products. Using chlorinated benzene as raw material, a series of organic chemical products such as phenol, nitrochlorobenzene, dinitrochlorobenzene, and picric acid can be produced, and further processed to produce dyes, insecticides, rubber processing aids, and pharmaceuticals. At present, the domestic production of chlorinated benzene mainly adopts the benzene chlorination method, that is, reacts pure benzene and dry chlorine gas in a chlorination tower, and the resulting chlorinated liquid is washed with water, neutralized, and dried, and then sent to the crude and rectification towers Distillation to obtain finished chlorinated benzen...

AI Technical Summary

Problems solved by technology

The tail gas generated in the preparation process mainly contains hydrogen chloride gas, benzene vapor and a small amount of chlorobenzene vapor, and direct discharge causes waste of raw materials and serious environmental pollution

Taking the 120,000-ton / year chlorinated benzene project of Nanhua Company as an example, after preliminary analysis, the chlorinated benzene tail gas contains 7000-10000mg / m3 of benzene, and the exhaust gas volume per hour is 15000m3 / h, and the benzene-containing tail gas is discharged into the air, causing Great environmental pollution; at the same time, it causes material loss, and the benzene consumption of products remains high

In addition, the benzene content in the tail gas is relatively high, and it is easy to be enriched in the tail gas absorption tower. In case of lightning weather or static electricity, benzene explosion accidents are very likely to occur. Such accidents frequently occurred in the original chemical plant

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