Washing method of crude adipic acid slurry in adipic acid production process

Abstract

The invention discloses a method for washing crude adipic acid slurry in the adipic acid production process. The method includes the following steps that firstly, the crude adipic acid slurry from the crude acid crystallization procedure is conveyed into a crude adipic acid thickener to obtain thickened adipic acid slurry; secondly, the thickened adipic acid slurry is conveyed into a crude acid centrifugal machine, washed with raw process water for liquid-solid separation, and wet adipic acid is obtained; thirdly, the wet adipic acid is conveyed into an acidic slurry washing tank and mixed with washing process water, and the materials are stirred, dispersed and mixed; fourthly, the material of the acidic slurry washing tank is conveyed into an industrial adipic acid thickener to be thickened; fifthly, the thickened material is conveyed into an industrial adipic acid centrifugal machine and washed with desalted water for liquid-solid separation, crude adipic acid is obtained, and the crude adipic acid is conveyed to the subsequent refining procedure. By means of the method, the content of nitrate in adipic acid is greatly reduced, and an adipic acid raw material low in nitrate content is provided for TPU and nylon spinning industries. The method further optimizes an original process water system, the process water is fully used, emission is reduced, and environment-friendly production is achieved.

Description

technical field [0001] The invention relates to a method for producing adipic acid, in particular to a method for washing crude adipic acid slurry. Background technique [0002] Adipic acid is an important chemical raw material, also known as fatty acid, which belongs to aliphatic dibasic acid. Adipic acid has the generality of aliphatic dibasic acid, including esterification reaction, amination reaction, and salt-forming reaction. At present, it is mainly used in the polyurethane and nylon salt industries in China, and due to the rapid development of the polyurethane industry, it accounts for 65% to 70% of the total domestic consumption of adipic acid, nylon 66 salt accounts for 20% to 25%, plasticizers, etc. Other areas accounted for 8% to 10%. The rapid development of domestic emerging thermoplastic polyurethane products (TPU) and nylon 66 has made the quality of purified adipic acid products, especially the content of nitrate, have higher requirements. [0003] The re...

AI Technical Summary

Problems solved by technology

The defects of the traditional method are: the content of nitrate and pseudo nitric acid is too high, and the content of nitric acid is 1.5 ~ 3mg / kg, which will lead to an increase in the broken end rate of nylon salt polymer spinning, which will occur in the TPU production process. Problems such as viscosity drop, yellow color, etc.

Therefore, it cannot meet the needs of spinning grade nylon 66 and thermoplastic polyurethane

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