Separation and recycling system of NMP in salty solution

Abstract

The invention belongs to the technical field of mixed solution recycling devices, and particularly relates to a separation and recycling system of NMP in a salty solution. The separation and recyclingsystem is mainly used for separation and recycling of NMP and salt in a solvent which is washed and neutralized, and comprises an extraction device, a stripping tower, an extraction agent removing device, an NMP purifying device and an evaporating device. The recycling system adopts dynamic extraction at room temperature, not only achieves separation of the solvent from water, but also greatly improves the recycling rate of the solvent, and the recycling rate of the solvent is as high as 99.95% or above; salt in a waste salty solution is recycled through the evaporating device, reuse of the salty solution is achieved, the cost is lowered, low emission of waste liquid is achieved, and the requirement of national environment protection is conformed.

Description

technical field [0001] The invention belongs to the technical field of recovery devices for mixed solutions, and in particular relates to a system for separating and recovering NMP in saline solutions in the production process of para-aramid fiber. Background technique [0002] In the process of producing and synthesizing PPTA resin from aramid fiber, it is necessary to carry out low-temperature polycondensation reaction in an organic solvent with NMP (N-methylpyrrolidone) as solvent and calcium chloride as co-solvent, and the hydrochloric acid generated during the reaction is neutralized A large amount of hydrochloride will be produced. After the reaction, washing the reaction solution with water can remove the contained NMP, salt, water and trace oligomers to obtain the main product PPTA resin. Usually, the water consumption in the washing process of PPTA resin is relatively large, and The neutralized solution is an aqueous solution containing a large amount of organic sol...

AI Technical Summary

Problems solved by technology

Distillation directly after extraction and separation by this method will result in incomplete removal of the extractant, and hydrolysis of the extractant under high temperature conditions will easily cause severe corrosion of the equipment; and the products of hydrolysis of the extractant and impurities in the solution will accelerate the cracking of NMP , resulting in the loss of NMP, and there are more impurities in the NMP during recovery, which affects the polycondensation reaction of the later polymerization and the synthesis of PPTA; at the same time, the unpurified extraction agent will also affect its extraction effect in recycling

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