Method containing carbon dioxide replacement for absorbing methane in condensed coal bed gas through pressure varying mode

Abstract

The present invention relates to a method which contains carbon dioxide replacement and is used for absorbing methane in condensed coal bed gas through pressure varying mode. The method mainly comprises the following steps: absorbing the feed gas, replacing the working substance gas, regenerating the bed layer, charging the secondary product gas, recovering the working substance gas, etc., wherein, the replacing of working substance gas adopts an operation mode of pressurized replacing or normal-pressure replacing, namely the carbon dioxide is used for replacing and absorbing the methane under the absorption pressure, or under the normal pressure. The invention causes that the methane becomes the tower top product thereby increasing the concentration and yield of methane of product gas. The product gas obtained from the coal bed gas with 20% of methane concentration. The recovery rate obtains 90%. The method of the invention is suitable for the coal bed gases with different methane contents. The coal bed gas with low methane concentration can be changed into the high-quality natural gas fuel with a low cost. The product gas can be conveyed through pipe and can be stored with pot.

Description

technical field [0001] The invention relates to the coalbed methane development technology in the field of clean energy, in particular to a method for concentrating coalbed methane by pressure swing adsorption including carbon dioxide replacement. Background technique [0002] Methane contained in coal seams is a high-quality gaseous fuel, and it is also an important source of underground disasters in coal mines and the greenhouse effect of the atmosphere. If the methane concentration in the coalbed methane reaches more than 80%, it can be directly used as a clean fuel, but the methane concentration in the drained coalbed methane is generally much lower than 80%. The coalbed methane released by coal mining in my country is as high as 6 billion cubic meters per year, accounting for 30% of the world's total emissions, while its utilization rate is only 7-8% [Zhang Xinmin, Coalbed methane - the heavy pressure of natural gas in my country Potential Fields, Natural Gas Chemical I...

AI Technical Summary

Problems solved by technology

If the product gas methane is used as the replacement gas, the concentration can be increased from 20% to 93.7%, but a high reflux ratio is required, resulting in low production efficiency, low recovery rate, and increased separation costs

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