Method for making methane-enriched gas in low-temperature and heat exchange mode

The invention belongs to the technical field of coal chemical industries and relates to a method for making methane-enriched gas through industrial emission gas containing carbon and hydrogen, in particular to a method for making methane-enriched gas in a low-temperature and heat exchange mode. The method includes the following steps that 1, the pressure of raw material gas is raised to 0.5-3.5 Mpa through a compressor, and the raw material gas is purified, so that total sulfur is smaller than 0.1*10 mg/Nm ; 2, the raw material gas, steam and recycled gas are mixed and then enter a single-level low-temperature heat exchange methanation reactor, and a heat insulation catalyst layer is arranged at the position, below a column tube, of the reactor; 3, part of a byproduct, namely 5.0 MPa-10.0 MPa steam of methanation enters the reactor. According to the method, through process design of a low-temperature heat exchange single-level methanation reaction and performance improvement of the catalyst, the problem is solved, meanwhile the service life of the catalyst synthesized by methane is well prolonged, the utilization rate of energy is raised, device investment is effectively lowered, and the method can be used for industrial production of making substitute natural gas through carbon and hydrogen industrial emission gas.