Vent gas treatment method and treatment device

Abstract

The invention provides a treatment method of synthesized vent gas. The method comprises a first film separation work procedure, a converting work procedure, a decarburization work procedure and a second film separation work procedure, wherein in the first film separation work procedure, a methanol synthesized vent gas flow carries out the first film separation to obtain a first hydrogen-rich gas flow and a first target gas flow, the methanol synthesized vent gas flow comprises hydrogen gas, carbon monoxide, carbon dioxide, methanol, nitrogen gas and other light dydrocarbon; in the converting work procedure, the carbon monoxide carries out conversation reaction to be converted into the carbon dioxide, at the same time, partial new hydrogen gas is generated, and a second target gas flow is obtained; in the decarburization work procedure, solvents are used for absorbing the carbon dioxide for removing the carbon dioxide to obtain a third target air flow; and in the second film separation work procedure, the third target air flow carries out second film separation to obtain a second hydrogen-rich gas flow and a fourth target gas flow. Compared with the prior art, the invention effectively recovers and utilizes the hydrogen gas and the carbon monoxide in the methanol synthesized vent gas, natural gas is finally prepared through the treatment processes stage by stage, and the light hydrocarbon gas such as methanol and the like in the vent gas is fully utilized.

Description

technical field [0001] The invention relates to the fields of coal chemical industry and petroleum and natural gas chemical industry, in particular to a method for treating purge gas of synthetic methanol or synthetic ammonia. Background technique [0002] Methanol has a wide range of uses. For example, it can be used to produce various organic products such as formaldehyde, acetic acid, methyl chloride, and methylammonia in the fine chemical industry. It is also one of the important raw materials for pesticides and medicines. In addition, methanol can be used as a new type of clean fuel after deep processing, and can be added to gasoline to make methanol gasoline. [0003] At present, a common technique for preparing methanol known to those skilled in the art is to gasify coal to obtain a raw material gas, which undergoes a series of purification and compression processes to obtain the main substance as H 2 +CO+CO 2 The gas is then subjected to a synthesis reaction to pro...

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Problems solved by technology

[0006] When membrane separation is used to treat methanol to synthesize purge gas, most of the H in the purge gas 2 , CO 2 , part of CO, etc. is obtained as low-pressure permeate gas at the bottom of the tower, and returns to the methanol synthesis system after being compressed by a hydrogen compressor; while most of the CH 4 , N 2 , Ar and a small part of H 2 , CO 2 and part of CO as high-pressure non-permeable gas are burned as fuel gas in the plant after depressurization, which not only loses pressure but also wastes hydrocarbons

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