Coal mine downhole liquid-nitrogen-injecting permeability-increasing gas extraction system

Abstract

The invention discloses a coal mine downhole liquid-nitrogen-injecting permeability-increasing gas extraction system. The coal mine downhole liquid-nitrogen-injecting permeability-increasing gas extraction system comprises a liquid nitrogen injecting system, a nitrogen-methane extraction system, a nitrogen-methane separation system, a nitrogen purification system and a nitrogen liquefaction circulation system. According to the coal mine downhole liquid-nitrogen-injecting permeability-increasing gas extraction system, the processes of liquid nitrogen injecting for cracking, nitrogen-methane extraction and separation, and nitrogen liquefaction injection of a coal seam are achieved, the size of nitrogen injecting equipment is effectively decreased, a gas extraction method under a nitrogen-injecting permeability-increasing technology is provided, the extraction concentration rate is increased, the liquid nitrogen loss is effectively reduced, the cost of nitrogen-injecting permeability-increasing technological measures is reduced, resources are saved, the number of times of transportation of liquid nitrogen from the ground to a downhole is decreased, and material resources and manpowerare saved.

Description

technical field [0001] The invention relates to the technical field of gas drainage, in particular to an anti-permeability gas drainage system for underground injection of liquid nitrogen in coal mines. Background technique [0002] my country is a country with large coal resources and a large coal consumption country. With the development of mining activities, deep mining of coal resources has become a new normal, and deep buried coal seams are rich in gas, and gas disasters are also more serious. In order to effectively prevent gas disasters and improve the utilization rate of gas, more and more gas extraction before mining is used in coal mines as an effective outburst prevention measure. [0003] Among the anti-outburst measures of drainage before mining, coal seam permeability enhancement measures are the key technology to improve drainage efficiency. In recent years, liquid nitrogen fracturing anti-permeability technology has begun to gain attention in the field of sh...

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Problems solved by technology

[0004] The purpose of the present invention is to provide an anti-reflection gas drainage system for underground injection of liquid nitrogen in coal mines, which has the advantages of reducing the volume of equipment, improving the utilization rate of gas, reducing the loss of liquid nitrogen, and saving resources and costs. In the existing technology, there are problems such as large volume, high cost, high loss of liquid nitrogen, low concentration of gas extraction, waste of resources, etc.

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