Process and system for purifying and refining coal-bed gas

Abstract

The invention relates to a system for purifying and refining coal-bed gas, and the system for purifying and refining the coal-bed gas is used for solving the problems of high cost, high energy consumption and adversity to environmental protection of the existing coal-bed gas purification process. The system comprises a purification system, a pressurization and refrigeration system and a cryogenic distillation system; the purification system comprises a filter, a compressor, a washing tower and an adsorption system which are sequentially connected with one another; the pressurization and refrigeration system comprises a supercharger and a high-pressure heat exchanger; the cryogenic distillation system comprises a separator, a subcooler, a throttle valve and a cryogenic distillation tower; and the adsorption system is sequentially connected with the supercharger, the high-pressure heat exchanger, the separator, the throttle valve and the cryogenic distillation tower. The system for purifying and refining the coal-bed gas has the advantages of simple equipment, simplification of production process, more simplicity and convenience in system control, low cost for equipment investment and operation, short production period and high recovery ratio and purity of produced finished natural gas products, is applicable to coal-bed gases with different methane contents and has broad market application prospect.

Description

technical field [0001] The invention relates to the field of fuel gas purification, in particular to a coalbed gas purification and refining process and system. Background technique [0002] Coal bed methane, commonly known as coal mine gas, is natural gas. It is a gas resource that is associated and symbiotic with coal. Its main component is methane, and the methane content is generally 15% to 70%. Each ton of lignite can generate 38-50 cubic meters of coal-bed methane, and anthracite can generate 346-422 cubic meters of coal-bed methane. Calculated by calorific value, the calorific value of methane is 33.5~33.7kJ / Nm 3 (8000~9000kcal / Nm 3 ), which is higher than the calorific value of 1 kg of standard coal. [0003] The typical composition of CBM is shown in Table 1. [0004] Table 1 Typical composition of coalbed methane [0005] [0006] Coalbed methane can not only be used as fuel for power generation, industrial fuel and residential life, but also can be used a...

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Problems solved by technology

[0009] 1) Two-stage compression + reboiler refrigeration is used, the refrigeration effect is poor, and secondary cooling must be carried out, and the secondary cooling is limited by the cooling capacity provided by the outside world. In order to obtain high separation purity, the outside world needs to use the reboiler Provide sufficient cooling capacity, thereby increasing operating costs, which is not conducive to energy saving and consumption reduction;

[0010] 2) The impurity gas discharged from the rectification tower is still discharged from the system after the cold energy is recovered. The treatment of these tail gases not only requires expensive purification equipment, but also is not conducive to environmental protection

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