Method and device for processing off-gases in productive process of polyester or copolyester

Abstract

The invention discloses a method and device for processing off-gases in the productive process of polyester or copolyester. The method comprises the following steps of: firstly leading the vacuum off-gases containing tetrahydrofuran to be in contact with water vapor and absorbed through a water vapor injection pump, then sending a mixture of the vacuum off-gases and the water vapor to a spray absorber for carrying out spraying absorption once again; and directly sending the ordinary pressure or positive pressure off-gases containing tetrahydrofuran to the spray absorber for spraying absorption. The method and device provided by the invention can be used for processing the industrial off-gases generated by different devices in the productive process of polyester or copolyester in a differentiation manner; as one or more than two automatic regulating valves are arranged in a pipeline by which the vacuum tail gases are communicated to the water vapor injection pump, the automatic regulating valves can lead the pressures of the vacuum off-gases under different operating conditions to be kept in a constant working range so that a system can operate in a more stable condition. The device provided by the invention can avoid the probability to the maximum degree that inflammable and explosive objects are in contact with open fire, thereby the corresponding potential safety hazard is eliminated fundamentally.

Description

technical field [0001] The invention relates to a method and a device for treating tail gas in the production process of polyester or copolyester. The tail gas contains both vacuum process tail gas and normal pressure process tail gas, and the process tail gas contains tetrahydrofuran. Background technique [0002] Polyesters and copolyesters are usually prepared by esterification or transesterification of aromatic dicarboxylic acids, aliphatic dicarboxylic acids and aliphatic diols, followed by polycondensation. As disclosed in US Pat. In production, the esterification reaction, transesterification reaction and polycondensation reaction are all carried out under vacuum and reduced pressure conditions. Under vacuum conditions, small molecular substances such as water, 1,4-butanediol and by-product tetrahydrofuran are more likely to be removed from the system. seperate. Therefore, in the production process of polyester and copolyester with 1,4-butanediol and dicarboxylic ac...

AI Technical Summary

Problems solved by technology

Unlike acetaldehyde, tetrahydrofuran is prone to explosion when mixed with air, so there is a certain risk in using compressed air as a gas lift or jet medium for gas-liquid separation or tail gas transportation. At the same time, the process tail gas containing THF Incineration treatment will inevitably also cause a large amount of waste of tetrahydrofuran emissions

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