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Method for continuously recovering caprolactam in polymerization production process of nylon 6 in zero emission manner

A technology for recovering nylon and caprolactam, applied in the directions of separation/purification of lactam, chemical instruments and methods, organic chemistry, etc., can solve problems such as difficulty in meeting large-capacity production requirements, secondary environmental pollution, strong equipment corrosion, etc. The effect of breaking through technical bottlenecks, reducing environmental pollution and improving product quality

Inactive Publication Date: 2016-06-08
JIANGSU HONGSHENG NEW MATERIAL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This process will cause a huge waste of resources, and it is difficult to meet the production requirements of large capacity
The second method: the concentrated caprolactam concentrated solution is subjected to intermittent depolymerization reaction in the depolymerization kettle through phosphoric acid and water. This process is highly corrosive to equipment, and the recovery cost is high. At the same time, it will cause secondary pollution to the environment.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] A method for zero-emission continuous recovery of caprolactam in the production process of nylon 6 polymerization comprises the following steps:

[0021] a (including single water collection step), nylon 6 slices are input from the top of the extraction tower at a speed of 4200 kg / hour and output from the bottom of the extraction tower, and hot water with a temperature of 3 The flow rate per hour is pumped from the bottom of the extraction tower and overflows from the top of the extraction tower. The caprolactam and oligomers in the nylon 6 slices are extracted into water by means of convection between hot water and nylon 6 slices. The overflow water overflowing from the top is concentrated and collected into the single return water tank to obtain the single water. After testing: the weight percentage of caprolactam and oligomers in the single water is 8%~10%;

[0022] b (solubilization and concentration step), add fresh caprolactam containing 0.8 to 1.2 times the mass ...

Embodiment 2

[0030] A method for zero-emission continuous recovery of caprolactam in the production process of nylon 6 polymerization comprises the following steps:

[0031] a (including the single water collection step), the nylon 6 slices are input from the top of the extraction tower at a speed of 4300 kg / hour and output from the bottom of the extraction tower, and the hot water at a temperature of 120~130°C is 3 The flow rate per hour is pumped from the bottom of the extraction tower and overflows from the top of the extraction tower. The caprolactam and oligomers in the nylon 6 slices are extracted into water by means of convection between hot water and nylon 6 slices. The overflow water overflowing from the top is concentrated and collected into the single return water tank to obtain monowater. After testing: the weight percentage of caprolactam in monowater is 8%~9%;

[0032] b (solubilization and concentration step), add fresh caprolactam containing 1.3 to 1.6 times the mass of cap...

Embodiment 3

[0040] A method for zero-emission continuous recovery of caprolactam in the production process of nylon 6 polymerization comprises the following steps:

[0041] a (including the single water collection step), the nylon 6 slices are input from the top of the extraction tower at a speed of 4100 kg / hour and output from the bottom of the extraction tower, and the hot water with a temperature of 95~110 ° C is 4.1~4.5m 3 The flow rate per hour is pumped from the bottom of the extraction tower and overflows from the top of the extraction tower. The caprolactam and oligomers in the nylon 6 slices are extracted into water by means of convection between hot water and nylon 6 slices. The overflow water overflowing from the top is concentrated and collected into the single return water tank to obtain monowater. After testing: the weight percentage of caprolactam in monowater is 8.5%~10.5%;

[0042] b (solubilization and concentration step), add fresh caprolactam containing 2.8~3.2 times t...

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PUM

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Abstract

The invention relates to a method for continuously recovering caprolactam in the polymerization production process of nylon 6 in a zero emission manner. The method comprises a step of monomer-containing water collection, a step of solubilization concentration, a step of monomer return water concentration, a step of distillation and concentration, a step of a pre-polymerization reaction, a step of a pre-polymerization pressurization reaction, a step of a post-polymerization reaction and a step of casting strip slicing. A caprolactam recovery process with slag and wastes discharged continuously is turned into a recovery process without slag and waste discharge, and caprolactam is completely recovered. The process for intermittently recovering caprolactam is turned into a continuous recovery process, and the technological difficulty that caprolactam is difficult to recover during high-capacity polymerization production of nylon 6 is overcome. The production rate of a nylon 6 product can be increased, the production cost is reduced, the product quality is improved, and pollution to the environment is reduced.

Description

technical field [0001] The invention relates to a method for recovering caprolactam, in particular to a method for zero-emission continuous recovery of caprolactam in the polymerization production process of nylon 6. Background technique [0002] At present, the hydrolytic polymerization method is mainly used to prepare high-quality nylon 6. Since the hydrolytic polymerization of caprolactam is a reversible reaction, 100% conversion of caprolactam cannot be achieved during the polymerization process, and the amount that does not fully participate in the reaction is about 10%, which includes caprolactam mono Body and oligomer, if this part of the substance is doped in the slice, it will seriously affect the quality of the product, so it needs to be extracted with high-temperature water, and the extracted monohydrate will be recycled. [0003] At present, there are mainly two types of recycled monomer water at home and abroad. The first one: use three-effect concentration and ...

Claims

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Application Information

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IPC IPC(8): C07D223/10C07D201/16
CPCC07D223/10C07D201/16
Inventor 倪利锋梁万志雷建龙
Owner JIANGSU HONGSHENG NEW MATERIAL