Reaction recovery system for continuous synthesis of polyamide and method thereof

Abstract

The invention provides a reaction recovery system for continuous synthesis of polyamide. The system comprises a multi-stage internal circulation tower reactor and a diamine recovery tower, wherein thereactor is beneficial to promote liquid phase recycle mixing in each stage of reaction unit, and the diamine recovery tower can separate and recover diamine components in mixed steam in time. The whole reaction recovery system has the advantages of high heat exchange efficiency, low energy requirement, low equipment investment and maintenance expenditure and the like. The invention further provides a continuous synthesis method of polyamide. The polyamide is synthesized in a multi-stage liquid-phase recycle mixing and pressure controllable decreasing mode. The gas phase pressure of differentreaction stages is adjusted, so that the boiling evaporation amount of water and diamine in a liquid phase and the reaction degree of polyamide salt are effectively controlled, the whole polycondensation process is carried out under the trend that the pressure is gradually reduced, the coordination and distribution of heat supply quantity in different reaction stages are facilitated, the improvement of the polymerization degree of a polyamide product is promoted, the polymerization degree of a final product reaches 10-60, and the requirements of a subsequent decompressor are reduced or eliminated.

Description

technical field [0001] The present invention relates to a continuous polymerization method for producing polyamide and an equipment system capable of performing the polymerization method. More precisely, the present invention relates to a continuous polyamide synthesis method and a reaction recovery system, the system includes a multi-stage internal circulation tower reactor and a diamine recovery tower. Background technique [0002] Processes for the continuous production of polyamide materials such as Nylon 66 are known in the prior art, and a typical production flow consists of 3-5 different reaction vessels connected in series. Evaporation concentration, high-pressure pre-condensation, flash evaporation, atmospheric pressure final polycondensation and vacuum polycondensation are carried out in sequence. Each reaction step is separated in space, and the reaction vessel used is usually a tubular reactor or a stirred tank. U.S. Patent US3402152 discloses the continuous pol...

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Problems solved by technology

[0004] The vertical multi-stage reaction equipment disclosed in Chinese patent CN201910063549.8 has the characteristics of gas-liquid parallel flow, and the gas phase pressure at the inlet is relatively high, which improves the shortcomings of the above-mentioned integrated equipment to a certain extent. The bubbling stirring effect in the tray forces most of the gas to flow continuously from top to bottom, and even requires additional inert gas to ensure the stirring and mixing effect. Therefore, it is necessary to equip multi-layer decompression devices to achieve the effect of gradually decreasing pressure. Not only the structure is complex but also the pressure drop is relatively uncontrollable

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