Full liquefying separation process for air-containing coal bed gas

Abstract

The invention relates to a full liquefying separation process for an air-containing coal bed gas. In the process, equipment comprising a bilayer alkoxide separation tower and a nitrogen separation tower performs full liquefying separation on the air-containing coal bed gas, wherein the bilayer alkoxide separation tower comprises an upper tower and a lower tower; and a condensing evaporator is arranged between the upper tower and the lower tower. The process comprises the following steps of: introducing the air-containing coal bed gas into the lower tower after the coal bed gas is compressed and purified; condensing hydrocarbon into liquid to fall on the bottom of the lower tower through the heating of the bottom of the lower tower and condensation of the condensing evaporator to obtain liquefied natural gas; allowing the hydrocarbon-separated gas to rise to the top of the lower tower, to enter the top of the upper tower after throttling and to enter the nitrogen separation tower through the outlet on the top of the upper tower, or allowing the gas to enter the middle part of the nitrogen separation tower after throttling, wherein oxygen is condensed to liquefied oxygen on the top of the nitrogen separation tower, the liquefied oxygen returns to the bottom of the nitrogen separation tower, leaves from the outlet at the bottom of the nitrogen separation tower, returns to the top of the upper tower, and is output from the bottom of the upper tower; and outputting the nitrogen from the outlet of the top of the nitrogen separation tower, and cooling the nitrogen into liquefied nitrogen.

Description

technical field [0001] The invention relates to a gas liquefaction separation process, in particular to a full liquefaction separation process of air-containing coal bed gas. Background technique [0002] Coal bed methane, commonly known as gas, methane is adsorbed by coal during the formation of coal, that is, coal bed methane. my country's geological structure conditions are complex, and there are many high-gas mines and coal and gas outburst mines, accounting for 45% of the state-owned key coal mines alone. Gas is colorless, odorless, flammable and explosive, and will be separated and dispersed during the coal seam development process. When the gas concentration in the air is between 5.5% and 16% and there is an open flame, it is very easy to cause an explosion accident, which has become It has been a serious problem that has plagued coal mine safety production for a long time. More than 80% of the extraordinarily large and major accidents in my country's coal mines are c...

AI Technical Summary

Problems solved by technology

The separation of hydrocarbons, nitrogen and oxygen can be realized by two-stage rectification, but the two-stage rectification towers need to have independent reboilers and recondensers, and the equipment used is more, the process is more complicated, and the investment is higher. , although gas-liquid separation can be achieved and a certain amount of liquefied natural gas products can be obtained, but the complete separation of liquefied natural gas, liquid oxygen and liquid nitrogen cannot be achieved, and a part of the mixed gas in the middle is drawn out and released into the air, which will cause cause a certain waste

Although the single-stage rectification adopted in Chinese patent application No. 200610103425.0 has simplified equipment, it cannot realize the complete separation of natural gas, oxygen and nitrogen, and a part of the mixed gas in the middle is drawn out and released into the air, which will cause certain waste

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