The invention relates to the technical field of low-temperature
methanol washing, in particular to an energy-saving low-temperature
methanol washing process which comprises the steps of
acid gas removal of
raw material gas in an absorption
tower,
desorption and regeneration of a rich solution after the
acid gas is absorbed, and cyclic utilization of a
methanol solution. Through functional differentiation of a
sulfur-containing semi-barren solution and a
sulfur-free semi-barren solution, the circulation amount of lean methanol is reduced compared with that of a traditional process, the load and steam consumption of a thermal regeneration
tower are directly reduced, the
sulfur-containing semi-barren solution selectively absorbs H2S in a desulfurization section, 50-60% of CO2 is removed, the load of a
decarburization section is reduced, the total number of
tower plates of an absorption tower is reduced, and the equipment investment is reduced; the desulfurization section is divided into two or three sections and is provided with a cooler, the temperature of each section is strictly controlled to be-50 DEG C to-60 DEG C, efficiency reduction caused by heat absorption and release is avoided, and the
decarburization section adopts barren liquor and sulfur-free semi-barren liquor combined absorption, so that the concentration of CO2 in purified gas is stabilized below 20ppm, and the requirements of high-end processes such as synthesis
ammonia and
coal hydrogen production on gas purity are met.