Method for realizing methanation of coke oven gas through carbon-replenishing hydrogen-returning process for synthetic natural gas

Abstract

The invention relates to the field of coal coking production, in particular to a method for realizing methanation of coke oven gas through carbon-replenishing hydrogen-returning process for synthetic natural gas. The method comprises: pressurizing purified coke oven gas to 1 MPa; raising temperature to 250 DEG C for heat exchange; under the action of catalysts, performing three-stage methanation reaction of CO2 recycled by a low-partial-pressure system added with flue gas and H2 obtained through the separation of a membrane separation device after methanation to obtain synthetic gas of which the concentration of methane is over 94 percent. The method adopts a low-pressure non-cyclic methanation process, and the reaction temperature of the method is as follows: a primary stage is at 600 DEG C; a carbon-replenishing hydrogen-returning stage is at about 500 DEG C; a final stage is at 360 DEG C; and the temperature before every stage of methanation reaction is controlled at 250 DEG C through balancing control. Through a heat-insulating reactor and a waste-heat boiler heat exchange system, the method not only controls reaction temperature, but also produces steam serving as a byproduct at 3.8 MPa and 450 DEG C. Compared with other synthesis methods, waste heat energy produced during the methanation reaction is utilized more fully, so that the aims of saving energy, reducing emission and causing no environmental pollution are achieved while capacity is expanded.

Description

technical field [0001] The invention relates to the field of coal coking production, in particular to a method for synthesizing natural gas through methanation of coke oven gas through a process of replenishing carbon and returning hydrogen. Background technique [0002] Coke oven gas contains CO, CO 2 、H 2 S, CH 4 、H 2 , N 2 , SO 2 And impurities, directly used for combustion to obtain heat, not only can take advantage of the low calorific value, the general combustion calorific value is about 5000 kcal, but also the complex composition, insufficient combustion will pollute the environment, and the impurities contained will easily damage the facilities, purify the coke oven gas , Methanation synthetic natural gas can increase the calorific value of combustion to more than 8000 kcal. In the modern society of energy saving and emission reduction, it has become a hot topic for many enterprises and colleges. [0003] However, at present, most domestic coke oven gas metha...

AI Technical Summary

Problems solved by technology

[0012] ②The methanation reaction is a strong exothermic reaction. If the heat dissipation is not good, it is easy to cause local overheating of the catalyst and burn out the catalyst.

[0058] 3. Production cost - consumption quota of raw and auxiliary materials (calculated per ton of LNG)

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