A method for directly supplementing carbon dioxide from coke oven gas to produce synthetic natural gas

Abstract

The invention provides a method for producing synthetic natural gas through adopting coke oven gas to directly supplement carbon dioxide. The method comprises the main procedures of coke oven gas compression, purification, CO2 gasification, methanation and membrane separation, wherein the coke oven gas purification comprises initial desulfurization, temperature swing adsorption deep purification and fine desulfurization, and the methanation procedure is a three-stage methanation reaction. In the methanation reaction process, CO2 is supplemented, and full utilization of CO2 and H2 in mixed gas is achieved to a largest extent; through distribution of methanation syngas to go into reactors before a final-stage methanation reactor according to a certain proportion and partial inner circulation of methanation gas in methanation reactors before the final-stage methanation reactor, reaction equilibrium, reaction pressure and reaction heat release of the methanation reaction are effectively controlled, and the quite satisfactory technical effect is obtained. While the yield of CH4 in the synthetic natural gas is improved, the operation cost of the coke oven gas synthetic natural gas is reduced. At the same time, the method achieves emission reduction of greenhouse gas CO2, not only can produce quite good economic benefits, but also has good environmental benefits.

Description

technical field [0001] The invention relates to a method for preparing synthetic natural gas, in particular to a method for directly supplementing carbon dioxide with coke oven gas to prepare synthetic natural gas. Background technique [0002] Coke oven gas or coke oven gas to synthetic natural gas technology (including SNG, CNG and LNG), also known as coke oven gas or coke oven gas to synthetic natural gas technology, coke oven gas or coke oven gas to synthetic natural gas technology, etc. This technology is a new technology for comprehensive utilization of coke oven gas developed in the coking industry in recent years. At present, domestic coke oven gas-to-synthetic natural gas technology mainly consists of two types: "methanation process" and "separation process". Among them, the methanation process can be further divided into two types: "non-carbon replenishment methanation process" and "carbon supplementation methanation process". CH in coke oven gas 4 The volume fr...

AI Technical Summary

Problems solved by technology

However, the disadvantage of this technology is that carbon supplementation is added to the coke oven gas, just to optimize the H in the coke oven gas. 2 , CO, CO 2 The stoichiometric ratio of CO in syngas 2 Still not fully utilized, it is necessary to add a deep decarbonization process, and then remove the CO 2 Returning carbon replenishment gas for recycling also leads to an increase in investment costs

[0005] In addition, the Chinese invention patent with the publication number CN 101712897 A discloses a method for realizing the methanation of coke oven gas into natural gas through a carbon replenishment and hydrogen return process. reactor) supplemented with CO 2 And the H separated by the membrane separation device after the methanation reaction 2 , thus increasing the CO in the syngas 2 conversion, increased CH in product natural gas 4 However, this method needs to be realized through the methanation reaction with a large difference in the reaction temperature of the primary stage of about 600°C, the second stage (carbon replenishment and hydrogen return stage) of about 500°C, and the final stage of about 360°C. Its temperature control is relatively difficult, so the process is relatively complicated and the efficiency is not high

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