A method for preparing dimethyl ether from methanol with low energy consumption

Abstract

The invention relates to a method for low energy consumption preparation of dimethyl ether from methanol, and belongs to the field of chemical engineering. The method comprises the following steps: 1, methanol from a tank area undergoes two-stage preheating by a wastewater cooler and a methanol preheater; 2, the preheated methanol is vaporized by a vaporizing tower, the vaporized methanol enters a reactor, reaction gas obtained after a reaction is divided into two flows, one of the two flows enters the methanol preheater, and the other flow enters one reboiler in the vaporizing tower; 3, the two reaction gas flows with the heat being partially used meet before entering a secondary methanol preheater, and exchange heat, and the obtained gas enters a rectifying tower from the bottom in a gas form; and 4, rectifying tower top dimethyl ether is cooled by an evaporative condenser, the cooled dimethyl ether enters a dimethyl ether refluxing tank, one part of the dimethyl ether is refluxed, and one part of the dimethyl ether is extracted as a product. Compared with the prior art, the method has the advantages of reasonable and full utilization of heat generated in the whole production system, saving of a large amount of process cooling water, optimized process route, reduction of the device investment, and suitableness for large-scale industrialization.

Description

technical field [0001] The invention relates to a low-energy-consuming method for preparing dimethyl ether from methanol, in particular to a low-energy-consuming method that makes full use of system reaction heat, reduces external heat source supply, and reduces production costs, and belongs to the technical field of chemical production. Background technique [0002] At present, the main production methods of dimethyl ether are the synthesis gas one-step method and the methanol method. The methanol method is divided into methanol gas-phase catalytic dehydration method and liquid-phase catalytic dehydration method. The one-step method of synthesis gas is in the stage of industrial exploration, and there is no report of industrialization. Methanol gas-phase catalytic dehydration method and methanol liquid-phase catalytic dehydration method have industrial production equipment abroad; while methanol gas-phase catalytic dehydration method has the characteristics of low investme...

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Problems solved by technology

[0004] Chinese patent document (CN 200810045127X) discloses "a low energy consumption method for producing dimethyl ether from methanol". The heat taken away by the cooling water in the distillation process makes the first methanol preheated; the second methanol enters the tower from the upper part of the methanol pressurized rectification tower as a cold reflux, and is heated under the action of the methanol reboiler. Exchange and transform into methanol vapor; in the present invention, the raw material methanol is heated through multiple heat exchanges, and the phase change heat of the gas phase dimethyl ether liquefaction and the heat of the bottom water discharged from the methanol pressurized rectification tower are utilized, but the residual heat of the reaction gas has not yet reached Fully utilized, there is still room for further improvement in waste heat utilization

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