Tetrahydrofuran recovery system

Abstract

The invention relates to a tetrahydrofuran recovery system. A bottom outlet of a crude product tank is connected with a tube side inlet of a first heat exchanger through a first pump, a tube side outlet of the first heat exchanger is connected with a middle inlet of a first rectifying tower, a top outlet of the first rectifying tower is sequentially connected with a third pump through a first aircooler and a first collecting tank, an outlet of the third pump is connected with a shell side inlet of a second heat exchanger, and a shell side outlet of the second heat exchanger is connected withan inlet of a second rectifying tower; the bottom of the first rectifying tower is connected with a tube pass inlet of a third heat exchanger through a waste water receiving tank and a second pump, atube pass outlet of the third heat exchanger is connected with an upper portion inlet of a stripping tower, a lower portion heat medium inlet of the stripping tower is connected with a steam pipe, a bottom outlet of the stripping tower is connected with a waste water treatment device through a shell side of the third heat exchanger, and the top exhaust port of the stripping tower is connected witha reflux port of the crude product tank through a third air cooler. The device can reduce equipment investment, reduce sewage COD, save operation cost and increase product income.

Description

technical field [0001] The invention relates to a continuous production device for the purification of multiple components, in particular to a tetrahydrofuran recovery system, which belongs to the technical field of rectification recovery devices. Background technique [0002] 1,4 Butanediol (BDO) is a basic chemical and fine chemical raw material, widely used in the production of engineering plastics and fibers, such as: polybutylene terephthalate (PBT), elastic fiber, tetrahydrofuran (THF ), polytetramethylene glycol ether (PTMEG) and unsaturated polyester (UP), etc. There are many process routes for producing BDO, among which, in the process of producing BDO by the maleic anhydride method, a side reaction will occur in a high temperature environment to form tetrahydrofuran (THF). The amount of this part of THF is relatively large, which has obvious economic benefits and needs to be recycled. A typical device for recovering a large amount of THF is three-tower rectificati...

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Problems solved by technology

[0005] The traditional system has the following problems: 1. Two reboilers are installed in the No. 1 rectification column, and the investment cost is high

2. The waste water after rectification and separation in the No. 1 rectification tower directly enters the waste water treatment device. The THF content in the waste water is high, and the COD is as high as 25,000 to 40,000 mg / L. The treatment pressure of the waste water treatment device is high, and this part of THF is wasted

3. The No. 1 rectification tower and the No. 2 air cooler of the No. 3 rectification tower need to use a large amount of circulating cooling water. Taking the annual production of 2000t / a THF production line as an example, the annual consumption of circulating cooling water is 2.5-3 million m³; There is a relatively large fire separation distance between the utility workshop and the THF recovery device. The circulating water is in the utility workshop, with long transmission distance, large pressure drop, large motor power, and high energy consumption.

4. The pressure control of No. 1 rectification tower and No. 3 rectification tower is controlled by nitrogen pressurization and tail gas discharge, which not only wastes a lot of nitrogen, but also escapes a lot of THF

5. Single production of products cannot meet market changes

6. The low-emission sampling of the device is all discharged in situ, which pollutes the environment and has a lot of waste

7. Both the removal of light components and the removal of heavy components are released in the barrel on the spot, which poses a great safety hazard on site

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