Thermal coupling system and method for extractive distillation of normal hexane, isohexane and benzene

Abstract

The invention relates to a thermal coupling method for extractive distillation of normal hexane, isohexane and benzene. A rectifying tower consists of a dehydrating tower, an isohexane tower, a normal hexane extractive distillation tower, a first solvent recovery tower, a benzene extractive distillation tower and a second solvent recovery tower. Residue of the second solvent recovery tower respectively exchange heat with fed materials of the dehydrating tower and the benzene extractive distillation tower. Residue of the first solvent recovery tower is a heating medium of a reboiler of the isohexane tower, and products at the tops of the normal hexane extractive distillation tower and the benzene extractive distillation tower enter an argil adsorbent bed via two plate heat exchangers which are of all-welded type, so that all counter-current operation is realized. One of the plate heat exchanger uses the material discharged from the argil adsorbent bed as a heating medium, and all stream heats are adequately utilized. According to the invention, the power energy of the rectifying unit is greatly reduced, the production cost of the normal hexane is lowered, and the market competitiveness is improved.

Description

technical field [0001] The invention relates to a thermal coupling method capable of reducing energy consumption of a n-hexane, isohexane and benzene separation device, in particular to a thermal coupling system and method capable of reducing the extraction and rectification of n-hexane, isohexane and benzene. Background technique [0002] n-Hexane is a colorless transparent liquid, one of the widely used hydrocarbon solvents, and the most representative non-polar solvent. Industrial hexane solvent oil can be used in industries such as medicine, chemical industry, polymer materials, rubber industry and food. The market demand for n-hexane products is large. [0003] The main method of industrial production of n-hexane is: first obtain crude n-hexane from straight-run or raffinate by rectification or hydrogenation of platinum reformed raffinate, and then undergo molecular sieve adsorption and intermittent azeotropic distillation , extractive distillation and other methods t...

AI Technical Summary

Problems solved by technology

The yield of azeotropic distillation is high, but the purity of the product obtained is not high

The product purity of the extractive distillation method is higher, up to 99%, and has a higher yield. However, the existing extractive distillation process requires a large amount of steam for heating and a large amount of cooling water for cooling the material. , high energy consumption

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