Deoxidation and denitrification system for oxygen-containing coal bed gas

Abstract

The invention discloses a deoxygenation and denitrification system for oxygen-containing coal bed gas. The system includes a cold box, a rectification tower, a coal bed gas deoxidation and denitrification mechanism, a mixed refrigerant circulation mechanism and a nitrogen refrigerant circulation mechanism; the mixed refrigerant circulation mechanism provides cooling capacity for the cold box; The cooling capacity is provided by the box and the rectification tower; the coalbed methane deoxygenation and denitrification mechanism includes the feed gas pipeline, the recondenser arranged at the top of the rectification tower and the reboiler arranged at the bottom of the rectification tower; the feed gas pipeline and all The above-mentioned cold box is connected, and then connected with the reboiler after being drawn out from the cold box; the feed gas pipeline is drawn out from the reboiler and then enters the cold box, and then connected with the rectification tower after being drawn out from the cold box; The gas phase outlet of the reboiler is connected with the cold box through the pipeline, and the pipeline is connected with the LNG storage tank after being cooled by the cold box. The invention can realize the liquefaction of coalbed methane with a methane content of 30-90% in raw material gas, reduce carbon emission, and recover natural gas resources to the greatest extent.

Description

technical field [0001] The invention relates to a deoxygenation and denitrification system for oxygen-containing coal bed gas, belonging to the technical field of natural gas liquefaction. Background technique [0002] The coalbed methane extracted during the coal mining process has relatively low methane content, usually 30% to 70% (volume fraction), and other components mainly include carbon dioxide and air. In 2010, 7.6 billion m3 of coalbed methane was extracted underground in my country, and the utilization amount was about 2.43 billion m3, which was less than 32%. my country's coalbed methane resources are abundant, but relatively little development, almost no industrial application. Because coalbed methane pours into the coal mine roadway or explodes, it will cause disasters. Therefore, the coal industry has always regarded coalbed methane as a disaster gas. At present, the drainage treatment of oxygen-containing coalbed methane mixed with air is only based on the s...

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Problems solved by technology

[0003] At present, there are several invention patent applications for the separation process and equipment of oxygen-containing coalbed methane, such as the Chinese patent application No. 200610080889.4. The stage rectification process is complicated, there are many equipments, and the pressure loss of the rectification tower is relatively large. Since the system adopts a low-pressure process, the energy consumption of the process is relatively high

No. 200610103425.0 Chinese patent application adopts cryogenic rectification method for the separation and liquefaction of oxygen-containing coalbed methane, but this process adopts conventional refrigeration methods such as mixed refrigeration or expansion refrigeration, and the auxiliary mechanical refrigeration efficiency such as turbo expander is low, which reduces the separation and liquefaction capacity

This process is relatively complicated, and it needs to consume a large amount of methane to react with oxygen, and the contained N 2 still needs further processing

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