METHOD AND DEVICE FOR WASHING AND PURIFICATION WITH LOW-TEMPERATURE METHANOL

A method for washing and purification with a low-temperature methanol at least includes the following steps: condensing a raw shift gas and conducting a gas-liquid separation to obtain CO2-containing liquid and a separated raw material gas; and vaporizing the CO2-containing liquid and reducing a pressure by an expansion to obtain a CO2-containing gas; and washing the separated raw material gas with a methanol to obtain a purified gas. The present application combines CO2 condensation and an expander, so that the load of cooling capacity of the system for washing with a low-temperature methanol is reduced by 60%. At the same time, the external work done by the expander reduces the energy consumption of the system. After the CO2 in the purifying gas of desulfurization in the section A of the scrubber is condensed, the amount of CO2 entering the section B is reduced.