Method for separating dimethyl oxalate and dimethyl carbonate with low energy consumption

Abstract

The invention relates to a method for separating dimethyl oxalate and dimethyl carbonate with low energy consumption. The coupling reaction product flow enters the alcohol washing tower from the bottom, and the gas flow at the top outlet of the alcohol washing tower enters a cooler to cool and then circulates back to the esterification reactor. The cooler condensate produced by cooling the cooler and the supplementary methanol at the top of the alcohol scrubber are sprayed from the top of the alcohol scrubber; a sufficient amount of methanol is in countercurrent contact with the rising gas stream in the upper absorption zone of the alcohol scrubber, and the absorption zone in the alcohol scrubber goes down The liquid to the middle of the tower is taken out entirely or partly from the side outlet, and a certain amount of methanol is controlled to enter the lower condensation zone of the alcohol washing tower to contact with the coupling reaction product flow entering at the bottom in countercurrent, and the coupling reaction product flow is extracted from the bottom liquid stream of the alcohol washing tower. DMO, DMC and a small amount of methanol generated by the joint reaction. The invention can reduce the concentration of methanol in the tank of the alcohol washing tower under the premise of ensuring the spray density of the alcohol washing tower, thereby reducing the energy consumption in the separation process of DMO and DMC, and avoiding the problem of blockage and scaling of the tank of the alcohol washing tower.

Description

technical field [0001] The invention belongs to the technical field of chemical separation, and in particular relates to a method for separating dimethyl oxalate and dimethyl carbonate with low energy consumption. Background technique [0002] Dimethyl oxalate (DMO) is an important raw material for organic synthesis. The two-step technical route of producing DMO by gas-phase reaction of synthesis gas and hydrogenation to produce ethylene glycol is the commonly used "coal chemical industry route" to synthesize ethylene glycol. The method has good economy and competitiveness. The process is mainly divided into three steps: esterification, coupling and hydrogenation: the first step of esterification is to use nitrogen monoxide, oxygen and methanol as raw materials to generate methyl nitrite (MN); the second step of coupling is to Carbon monoxide and MN are used as raw materials to generate DMO, and a small amount of dimethyl carbonate (DMC) is produced in a side reaction; the ...

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to provide a method for separating dimethyl oxalate and dimethyl carbonate with low energy consumption. The technical problem to be solved is: under the premise of ensuring the spray density of the alcohol washing tower, reduce the concentration of methanol in the still of the alcohol washing tower, thereby reducing Energy consumption in the separation process of DMO and DMC, and avoiding the clogging and fouling of the alcohol washing column

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