THF rectification equipment for PBT production

Abstract

The invention relates to THF rectification equipment for PBT production, which includes a first rectification column, a second rectification column, a third rectification column and a fourth rectification column. The first rectification column is connected to a THF wastewater device. A top outlet of the first rectification column is connected to the middle upper part of the second rectification column. A gas phase outlet of the second rectification column is connected to an auxiliary reboiler shell inlet of the third rectification column. An auxiliary reboiler shell outlet of the third rectification column is connected to a recovery liquid tank and the middle upper part of the fourth rectification column in order. A side-draw outlet of the fourth rectification column is connected to a reflux tank of the first column through a side-draw pump, and a bottom product of the fourth rectification column is combined with the product of the first rectification column and then conveyed to a sewage treatment system. The bottom of the second rectification column is connected to the third rectification column through a pipeline, a heavy component is discharged from the bottom of the third rectification column and a THF product is produced from the column top. The equipment can effectively improve the THF yield, reduce energy consumption and effectively save the operation cost.

Description

technical field [0001] The invention belongs to the technical field of rectification of fine chemical products, in particular to a THF rectification device used for PBT production. Background technique [0002] PBT (polybutylene terephthalate) is an important thermoplastic polyester, one of the five major engineering plastics. The direct esterification method of PTA and BDO as raw materials is widely used at home and abroad, and THF wastewater is inevitably generated during the production process. . THF is an important organic chemical raw material and a good solvent. How to purify THF efficiently and energy-saving has always been an important topic in the research of PBT production. [0003] China Patent Authorization Announcement No. CN 208250196 U, the date of the authorized announcement is December 18, 2018. A tetrahydrofuran recovery device for removing low boilers will not be fouled and blocked, the backflow is stable, the energy consumption is low, and the hazardous ...

AI Technical Summary

Problems solved by technology

[0005] The second THF rectification tower is usually a pressurized tower, and the common operating pressure is 0.6-0.65MPa (G). Light exhaustion through the gas phase will cause a large amount of THF loss due to flash evaporation, and will also increase the load on the tail gas treatment system; due to THF and The reason for the azeotropic presence of water is that the material composition at the top of the second tower is about 10% water, about 85% THF, and the rest is light components, so the discharge of light components from the second tower will inevitably cause THF waste

The exhaustion of THF rectification unit will inevitably cause THF and heat loss, and there is still a need for improvement in the existing technology

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