Method for liquefying and rectifying coalbed methane containing oxygen

Abstract

The invention relates to a method for liquefying and rectifying coalbed methane containing oxygen in the technical field of fuel gas purification. In the invention, after the coalbed methane containing oxygen is liquefied, impurity nitrogen and oxygen in the coalbed methane are separated off through a rectifying column so as to obtain a high-purity liquid product from the bottom of the column; the operation safety of a process flow is analyzed by applying an explosion limit theory, and an operation process which is easiest to cause explosion is determined; effective measures are taken to guarantee the operation safety of the operation process which is easiest to cause explosion so as to ensure that the operation of the whole process flow is safe and reliable; and a higher methane recovery rate can be also guaranteed so as to improve the energy utilization ratio.

Description

technical field [0001] The invention relates to a method in the technical field of gas purification, in particular to a method for liquefaction and rectification of oxygen-containing coal bed gas. Background technique [0002] Coal bed methane is a new type of clean energy. It is an unconventional natural gas associated with coal and self-generated and stored in coal seams in the form of adsorption. The potential of my country's coalbed methane resources is huge. Its development and utilization can increase new clean energy, reduce dependence on imported energy, effectively reduce greenhouse gas emissions, and can also reduce or avoid gas explosion accidents, which has a safety effect. [0003] There are two types of coalbed methane available for development and utilization. One is the coalbed methane extracted before coal mine mining. This gas has a methane content of more than 95% and has high utilization value. It can be directly pressurized for pipeline network transport...

AI Technical Summary

Problems solved by technology

Among them, the adsorption method often leads to a decrease in the product recovery rate. The membrane separation method uses the pressure difference as the driving force. The separation effect is affected by various factors such as the membrane permeability coefficient and the permeation area. It is not easy to operate, and high pressure will bring safety hazards. Through searching , the literature on coalbed methane deoxidation using these two methods is very rare

[0004] After searching the existing technology, it is found that the Chinese patent CN101613627A proposes to use the combustion method to make the methane in the coalbed gas react with oxygen to generate carbon dioxide and water, and reduce the oxygen concentration in the coalbed gas to below 0.2%. This method can Effective removal of oxygen in oxygen-containing coalbed methane with a concentration of 1%-15%, but the impurity gas of carbon dioxide produced by combustion also needs to be removed, which increases equipment investment and energy consumption

[0005] Further search found that in the Chinese patent CN200952872Y, a fractionation tower is used to remove oxygen in coalbed methane under low temperature conditions, but this patent does not consider the explosion limit problem in the separation process, and the safety of the operation process is not guaranteed

Chinese patent CN101531559A adopts low-temperature rectification method to remove oxygen in coalbed methane, and ensures the safety of operation by pre-rough deoxidation of raw material gas. Chinese patent CN101531560A also adopts low-temperature rectification method to remove oxygen in coalbed methane, through Control the temperature of the most explosive position in the rectification process to ensure operational safety, but for the lower concentration of coalbed methane, the methane recovery rate of these two patents is very low, resulting in low energy utilization

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