Technology for high efficiently recycling methanol from process water in device for preparing propylene from methanol

The invention relates to a chemical technology, which is used for high efficiently recycling methanol from process water in a device for preparing propylene from methanol. The technology is characterized in that: equipment used by the technology comprises a combined tower, a reboiler, a condenser, a return tank, and a reflux pump; materials containing methanol and process water enter the combined tower from the middle of the combined tower, methanol is discharged from the top part of the combined tower and then condensed by the condenser, the condensed methanol enters the return tank and then goes through the reflux pump, part of the methanol goes back to the top part of the combined tower as a backflow of the combined tower, the rest of the methanol is extracted from the combined tower; the process diluted steam is extracted from the tower plates below the material feeding section of the combined tower and returned to the reaction unit; and the wastewater in the tower bottom is discharged from the bottom of the combined tower. The technology has the advantages that: by utilizing the large amount of generated process steam, the methanol concentration in wastewater in the bottom of the methanol recycling tower can be reduced to 1 ppm or less, so the technology has a prominent economic profit and environmental profit; furthermore, the technology avoids the individual arrangement of a process steam tower, solves the reboiler obstruction problem caused by the high concentration multiple of wastewater in the tower bottom, and prolongs the equipment operation period.