Technique and device for recovering tetrahydrofuran by pervaporation method

Abstract

The invention relates to a technique for recovering tetrahydrofuran by a pervaporation method, which comprises the following steps: adding crude tetrahydrofuran into a distillation kettle, adding acid or alkali to regulate the pH value to a neutral state, adding a reducer to remove peroxides in the crude tetrahydrofuran, distilling by heating, condensing the distilled hydrous tetrahydrofuran, collecting the hydrous tetrahydrofuran in a storage tank, discharging salt, heavy organic substance and part of water from the kettle bottom, delivering the hydrous tetrahydrofuran to a preheater through a pressure pump, exchanging heat with high-purity tetrahydrofuran steam at the preheater, sending into an evaporator, and sending the hydrous tetrahydrofuran from the evaporator into a pervaporation membrane separator, wherein the infiltration side of the pervaporation membrane separator is connected with a vacuum system; condensing infiltration water by an infiltration liquid condenser, sending into an infiltration liquid tank, and obtaining high-purity tetrahydrofuran at the trapping side of the pervaporation membrane separator; and passing the high-purity tetrahydrofuran through a preheater, condensing through a finished product condenser, and sending into a product tank. The invention has the advantages of simple technical process, high safety factor, low equipment investment, high energy utilization efficiency and high recovery rate.

Description

technical field [0001] The invention relates to a process for recovering tetrahydrofuran, in particular to a process for recovering tetrahydrofuran by a pervaporation method, which belongs to the application field of pervaporation membranes. Background technique [0002] Tetrahydrofuran is an important organic chemical and fine chemical raw material. It has good solubility to many organic and inorganic substances. It can dissolve all compounds except polyethylene, polypropylene and fluororesin. It is widely used as a reactive solvent. "Universal solvent". [0003] In industrial production, when tetrahydrofuran is used as a solvent, impurities such as water are often brought in, so that tetrahydrofuran cannot be reused due to impurities, and it is discarded directly, which is wasteful and pollutes the environment, which does not meet the development requirements of energy saving and emission reduction. In recent years, with the increasing market demand for high-purity tetrah...

AI Technical Summary

Problems solved by technology

[0004] (1) Atmospheric pressure distillation: The azeotrope of tetrahydrofuran and water is obtained by distillation and separation under normal pressure. This azeotrope still contains a certain amount of water. Or the means of fractionation can no longer separate THF from the water in the azeotrope, so some extremely low moisture requirements cannot be met, and the energy consumption and cost of this process are relatively high

[0005] (2) Extractive distillation: add the extractant of the third component during the rectification process to change the relative volatility between the components to achieve the separation of the original azeotrope, but the amount of extractant used in the process of extractive distillation is relatively large , energy consumption and equipment investment are also relatively large, and the third component may be brought into THF products

However, the pressure swing rectification equipment is complex, requiring more theoretical plates and higher energy consumption

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