The invention relates to a multi-effect rectifying process of
methanol, which belongs to the technical field of separation and purification of
chemical products. In the process, a crude
methanol raw material of
coal-to-
methanol is rectified by a pre-rectifying
tower, a pressurizing
tower I, a pressurizing
tower II, an atmospheric tower and a
recovery tower in turn at appropriate
temperature and pressure so as to obtain a high-purity refined methanol product according with quality requirements. In the flow, methanol steam on the top of the pressurizing tower I is used for providing heat for a
reboiler at the bottom of the pressurizing tower II, the methanol steam on the top of the pressurizing tower II is used for providing heat for a
reboiler at the bottom of the atmospheric tower, and the pressurizing tower I, the pressurizing tower II and the atmospheric tower form multi-effect rectification; and simultaneously, the methanol steam on the top of the
recovery tower is used for providing heat for a
reboiler at the bottom of the pre-rectifying tower, and the
recovery tower and the pre-rectifying tower form double-effect rectification. The invention provides an energy-saving methanol multi-effect rectifying process method which has the advantages of greatly reduced
energy consumption, more stable production process, more easily controlled product quality, higher methanol recovery rate and basically equivalent investment compared with a three-tower rectifying process.