Concentration and separation method for ultralow-concentration coal bed gas

Abstract

The invention discloses a concentration and separation method for methane in ultralow-concentration coal bed gas. The concentration and separation method comprises the following steps: sequentially compressing and purifying the ultralow-concentration coal bed gas, and sequentially carrying out first-stage pressure swing adsorption deoxidation treatment and second-stage pressure swing adsorption denitrification concentration treatment, so as to realize concentration and separation of methane in the ultralow-concentration coal bed gas. According to the pressure swing adsorption concentration and separation method for methane in the ultralow-concentration coal bed gas, the ultralow-concentration coal bed gas is used as a raw material, compression and purification are firstly carried out, and then the methane in the coal bed gas is separated and concentrated by adopting a two-stage pressure swing adsorption method according to the gas source concentration, so that the concentration of the methane in the coal bed gas is increased to 10-20% from 2-5% of the raw material gas. According to the concentration and separation method, the purposes of CH4 concentration and deoxidation can be achieved by only selecting one carbon molecular sieve (BM-1 type carbon molecular sieve), the concentration and separation efficiency is remarkably improved, and the concentration and separation method has important significance and application value in the aspect of industrial popularization of coal bed gas.

Description

technical field [0001] The invention belongs to the field of gas separation, and in particular relates to an ultra-low concentration coal bed gas concentration and separation method. Background technique [0002] Coalbed methane refers to the natural combustible gas that exists in underground coal seams, and its main component is CH 4 (contains CH 4 , N 2 , O 2 and CO 2 ). my country is rich in coalbed methane resources, and the proven shallow reserves above 2000m are (30~35)×10 12 m 3 , equivalent to natural gas reserves. Coalbed methane can be divided into surface extraction and underground extraction according to the extraction method. CH in the surface extraction of coalbed methane 4 The concentration can reach more than 90%. However, due to the infiltration of a large amount of air during the underground extraction of coalbed methane, CH 4 The concentration varies from 20% to 40%. Ultra-low concentration coalbed methane refers to the CH in coalbed methane 4 T...

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Problems solved by technology

[0003] At present, the separation and concentration of coalbed methane by pressure swing adsorption mostly removes the oxygen in the coalbed methane first, and then concentrates and separates it. However, the process of direct pressure swing adsorption concentration and separation of ultra-low concentration coalbed methane has not been successfully reported. One time concentration cannot be completely separated and CH 4 The effect of enrichment is not good, and it is impossible to realize the popularization and application of industrialization. At the same time, it is also a big difficulty that a suitable adsorbent can separate multi-component gases at the same time. Many scholars are working on this aspect.

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