The invention relates to a process for synthesizing
natural gas by performing
methanation on
coke oven gas. The process comprises the following steps of: dispersing a fresh
methanation catalyst into an
inert liquid-phase medium and putting the mixture into a
slurry bed methanation reactor for reducing; performing a methanation reaction on the reduced
coke oven gas, introducing
tail gas into a gas-liquid separator I, discharging a
slurry liquid-phase component in the
tail gas and the catalyst from the bottom of the gas-liquid separator I and exhausting a
gas phase in the
tail gas from the top of the gas-liquid separator I; introducing a part of catalyst-containing
inert liquid-phase media into a gas-liquid separator II, exhausting a
gas phase from the top of the gas-liquid separator II, combining the
gas phase with the gas phase exhausted from the top of the gas-liquid separator I, cooling and performing
pressure swing adsorption so as to obtain H2 and synthetic
natural gas; and discharging a methanation catalyst-containing
inert liquid-phase medium from the bottom, combining the methanation catalyst-containing inert liquid-phase medium with the
slurry liquid-phase component and the catalyst which are discharged from the bottom of the gas-liquid separator I, filtering a large-particle catalyst of less than 300 meshes out, separating a fine catalyst of more than 300 meshes from the inert liquid-phase medium and discharging, mixing the separated inert liquid-phase medium and the large-particle catalyst, exchanging heat between the mixture and
raw material gas, cooling, and introducing the mixture into the slurry
bed methanation reactor together with the methanation catalyst which is newly dispersed into the inert liquid-phase medium for the methanation reaction. The process has the advantages that: the process has low
energy consumption and small equipment investment, is easy to operate and can replace the catalyst on line.