Low-temperature methanol washing method for low-pressure raw gas

Abstract

The invention relates to a low-temperature methanol washing method for low-pressure raw gas, belonging to the technical field of gas purification. The method is characterized in that low-pressure raw gas containing H2S, CO2 and water is precooled to low temperature, and is washed with low-temperature partially stripped solvent in a prewashing tower, wherein the low-temperature partially stripped solvent is subjected to gas stripping of a low-temperature methanol washing device; the raw gas subjected to water removal and effective gas recycled in the low-temperature methanol washing device, i.e. circulating flash evaporation gas, converge, and are reheated and compressed, or directly compressed without reheating; and the raw gas, which is compressed to the required pressure, enters the subsequent low-temperature methanol washing device, thereby removing acid gas in the raw gas. The invention solves the problem that the low-pressure raw gas can not be purified by the low-temperature methanol washing technique since the sulfur-bearing water-containing raw gas which is gasified under low pressure can not be directly compressed by a compressor. The invention widens the application range of the low-temperature methanol washing technique, combines the prewashing dehydration technique and the conventional low-temperature methanol washing technique, and has the advantages of low energyconsumption and investment saving.

Description

technical field [0001] The invention belongs to the technical field of gas purification, and relates to a method for removing and recovering acid gas, in particular to removing acid gas by using a low-temperature methanol washing method for low-pressure raw gas. Background technique [0002] The low-temperature methanol washing process (Rectisol) is a physical absorption gas purification process jointly developed by the German Linde company and Lurgi company in the 1950s. This process uses low-temperature methanol as a solvent to remove raw material gas acid gas in. Low-temperature methanol washing purification process can remove H in raw gas 2 S, COS, RSH, CO 2 , HCN, NH 3 , NO, paraffin, aromatic hydrocarbon, crude gas oil and other components, and can be dehydrated to make the gas completely dry, and the absorbed useful components can be recovered in the process of methanol regeneration; at the same time, this process has a high degree of purification, It has the char...

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Problems solved by technology

[0015] The purpose of the present invention is to solve the problem of how the low-pressure feed gas is suitable for the low-temperature methanol washing and purification process, that is, pre-cooling and pre-washing the feed gas to dehydrate and dry the feed gas, so that the feed gas without water will not be compressed during the compression process. It will cause corrosion to the compressor, so that the low-pressure feed gas can be compressed to the pressure required by the low-temperature methanol washing unit

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