Combination process for preparing liquefied natural gas (LNG) through high-oxygen-content and high-nitrogen-content coalbed methane

Abstract

A combination process for preparing liquefied natural gas (LNG) through high-oxygen-content and high-nitrogen-content coalbed methane is characterized in that processes such as a catalytic deoxidizing process, a deacidifying process, a dehydrating processes, debenzolizing and mercury removing processes, a liquefying process and a low-temperature rectifying process are carried out to obtain an LNG product, wherein the efficient pre-deoxidizing process enables the safe and stable operation of the whole liquefying device; the physical condition of each material is fully utilized; the pre-deoxidizing process can effectively avoid the problem of explosion limit of each material, thus the potential risk caused by oxygen can be removed from the source, and as a result, the operation safety and reliability of the processes can be ensured; the deacidifying, dehydrating, debenzolizing and mercury removing processes are mature and stable; the final low-temperature rectifying process is high in methane recovery rate, so that the energy utilization rate can be improved, and the LNG product quality can be ensured. According to the combination process, the process combination enables high safety, and the device treatment capacity can be improved, the carbon emission can be reduced, and the coalbed gas resource can be recovered to the maximum; 10% of investment can be saved, and more than 10% of operation cost can be reduced, by being compared with those of a PSA (Pressure Swing Adsorption) deoxidizing process.

Description

technical field [0001] The invention relates to IPC classification F25J3 / 08 technology for separating gas impurities from gas or gas mixture, belongs to the field of liquefied natural gas from coal bed methane, especially the process of coal bed methane containing high concentration of oxygen and nitrogen suitable for skid block combination installation, including Processes including deoxygenation and denitrogenation are used to prepare liquefied natural gas equipment. Background technique [0002] China is rich in coalbed methane resources, and the pumped coalbed methane is mainly the mixed coalbed methane produced by the dynamic mining area and the goaf during the coal mining process, which is doped with a lot of air, and the methane concentration varies widely, concentrating on 30%~ 80%, commonly known as "coal mine gas". At normal temperature and pressure, the explosion limit of methane in air is 5% to 15%. As the temperature and pressure increase, the explosion limit e...

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Problems solved by technology

[0006] Coal mines in some countries often adopt the method of first mining gas and then mining coal. In this case, the oxygen content of coalbed methane is usually low, and there are few studies on the removal of high oxygen content.

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