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

Abstract

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.

Description

technical field [0001] The invention relates to a chemical process, more specifically, to a process for recovering methanol from process water of a methanol-to-propylene plant. Background technique [0002] The methanol-to-propylene (MTP) process uses methanol as a raw material to produce hydrocarbon products mainly propylene through a series of reaction processes such as intermolecular dehydration and methanation. The reaction process of methanol to propylene is an exothermic gas-phase catalytic reaction. The reaction product is finally cooled in the quench tower, and the unreacted methanol is cooled and absorbed by the process water. At the same time, part of the heavy hydrocarbons and coke impurities generated by the reaction will also enter the process. in the water. [0003] As the main reaction process is the intermolecular dehydration of methanol to generate light olefins, the generated water needs to be discharged from the system eventually. In order to meet enviro...

AI Technical Summary

Problems solved by technology

By integrating the process steam tower with the methanol recovery tower, with the help of the high evaporation capacity of the process steam, the methanol content in the wastewater discharged from the bottom of the tower is reduced to below 1PPm; The water is kept in a cleaner state, which solves the problem of blockage of the bottom reboiler

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