The invention relates to a
sulfur methanation resistant process for preparing
substitute natural gas from synthetic gas. The process comprises the steps: enabling
raw material gas, which is formed through carrying out
hydrogen supplementing on the synthetic gas, to enter a
slurry-
bed reactor from the bottom of a
slurry bed, carrying out
methanation, discharging crude
product gas from the top of the
slurry-
bed reactor, enabling the crude
product gas to enter a gas-liquid-
solid separator, enabling a liquid-
solid phase, obtained through separating, and a catalyst containing an
inert medium, which is discharged from the bottom of the
slurry reactor, to enter a liquid-
solid separator together, discharging a solid phase separated by the liquid-solid separator from the bottom of the liquid-solid separator, enabling the separated solid phase to enter a
catalyst regeneration device, and carrying out
catalyst regeneration; and discharging a
liquid phase separated by the liquid-solid separator from the middle-upper part of the liquid-solid separator, returning the
liquid phase to the slurry-bed reactor, and purifying the crude
product gas separated by the gas-liquid-solid separator, thereby preparing the
natural gas. The process has the advantages of
high energy source utilization ratio, low equipment investment and operating costs and easiness in operation.