Methyl alcohol double effect rectification refining unit and process method

The invention relates to a methyl alcohol double effect rectification refining unit and a process. The unit comprises a one-effect rectifying tower and a two-effect rectifying tower, wherein the one-effect rectifying tower is communicated with the two-effect rectifying tower, the tower bottom of the one-effect rectifying tower is provided with a one-effect reboiler which requires an external heatsource for heating, the tower bottom of the two-effect rectifying tower is provided with a coupling reboiler with tower top steam of the one-effect rectifying tower as a heat source, a one-effect backflow pot is arranged between a tower top backflow pipeline of the one-effect rectifying tower and the coupling reboiler, the upper end of the one-effect backflow pot is provided with a one-effect condenser, the tower top of the two-effect rectifying tower is successively communicated with a two-effect condenser, a two-effect trapping device and a two-effect backflow pot. Compared with common rectification, not only can tw