Process and device for producing liquefied natural gas by rectifying methane-rich gas to dehydrogenate nitrogen

Abstract

A process and device for the rectification and dehydrogenation of methane-rich gas to produce liquefied natural gas, including two parts: low-temperature liquefaction and rectification separation; low-temperature liquefaction includes hydrogen and nitrogen-rich methane first enters the cold box, and is supplied by a mixed refrigerant The cold capacity liquefies the methane component in the cold box; rectification separation includes: the liquefied methane-rich gas containing hydrogen and nitrogen directly enters the single-column rectification tower for rectification to remove hydrogen, nitrogen and a small amount of carbon monoxide; the rectification tower A mixture of hydrogen, nitrogen and a small amount of carbon monoxide is obtained at the top, and the mixed gas of hydrogen, nitrogen and carbon monoxide goes out of the cold box system after recovering the cooling capacity of the cold box; the liquid phase at the bottom of the rectification tower returns to the cold box for supercooling and then goes out of the system to obtain Liquefied natural gas products with hydrogen content ≤ 500ppm, nitrogen content ≤ 2%, and carbon monoxide ≤ 2%. The invention provides a process for liquefying methane-rich gas to produce liquefied natural gas while removing hydrogen, nitrogen and carbon monoxide, with relatively simple flow and low equipment investment cost.

Description

technical field [0001] The invention provides a process and device for rectifying methane-rich gas to dehydrogenate nitrogen and produce liquefied natural gas. Coal-based synthesis gas, coke oven gas, and methanized coke oven gas contain not only methane, but also nitrogen, hydrogen, and a small amount of carbon monoxide. In order to obtain liquefied natural gas, it must be removed to a certain extent before it can be used as liquefied natural gas. Natural gas (LNG) product output. Background technique [0002] Under the pressure of environmental protection and energy cost, the proportion of natural gas as primary energy in various fields of society is gradually increasing, and its application fields have gradually expanded to power generation, automobile gas, industrial gas, urban residential gas, chemical gas, etc. , the market demand is increasing rapidly. The traditional natural gas pipeline supply method is still the mainstream, but due to the limitations of raw mater...

AI Technical Summary

Problems solved by technology

The use of flash evaporation will inevitably cause a large amount of methane to be carried in the flash gas, and the amount cannot be precisely controlled, which will cause a large loss of methane components

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