Method for producing liquefied natural gas from coke oven gas

Abstract

The invention relates to a method for producing liquefied natural gas by coke oven gas. The method comprises the following steps of adding waste gas and tail gas with certain pressure discharged by a gas plant or a smelting plant to coke oven gas, forming mixed coal gas, wherein the mol ratio of H2 to CO in the mixed coal gas is 3-3.2 : 1, or the mol ratio of H2 to CO2 is 4-4.2 : 1; purifying the mixed coal gas and performing methanation reaction. By adopting the method provided by the invention, the defect that the hydrogen is excessive in LNG (liquefied natural gas) products is overcome; the LNG is produced by a gas distribution method, the excessive H2 is converted into CH4, and the converted gas increases the content of CH4, and meanwhile, no H2 is contained; and in addition, the CH4 in the air is recovered by using PSA, and the recovered CH4 is returned to the coke oven gas to reuse, so that the purposes of energy-saving, environmental friendliness and increasing in yield and efficiency are realized.

Description

Technical field [0001] The invention relates to a method for industrial production of liquefied natural gas. Background technique [0002] Most of the existing industrial methods of producing liquefied natural gas are directly using coke oven gas to produce liquefied natural gas (LNG). The main disadvantage is that H in the coke oven gas 2 Obviously too much. When coke oven gas is directly used to produce LNG, H 2 Surplus, after the production is completed, the excess H 2 Separation from liquefied gas products results in high energy consumption, low product output, poor environmental protection, and poor factory efficiency. [0003] Existing H 2 There are roughly the following two processes for separation: primary separation and pre-separation. The pre-separation process uses different materials, and the membrane method and the PSA method. [0004] 1. One-time separation process (cold method) [0005] After being compressed, purified, and methanized, the coke oven gas is cooled and li...

AI Technical Summary

Problems solved by technology

[0002] Most of the existing industrial production methods of liquefied natural gas are to directly use coke oven gas to produce liquefied natural gas (LNG), and the main disadvantage is that H in coke oven gas 2 Obviously too much, when coke oven gas is directly used to produce LNG, H 2 Surplus, after the production is completed, it is necessary to put the surplus H 2 Separation from liquefied gas products, resulting in high energy consumption, low product output, poor environmental protection, and poor factory efficiency

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