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Recovery method of solvent nmp in para-aramid fiber production process

A production process, para-aramid fiber technology, which is applied in the field of polymer synthesis, can solve the problems of acidification of chlorinated alkanes as extractants, reduce the thermal conductivity of reboilers, corrosion of reboilers, etc., achieve high recovery rate and solve thermal conductivity efficiency. The effect of low and low pollution emission

Active Publication Date: 2022-06-21
山东聚芳新材料股份有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, there are two problems in the separation and rectification process: one is the acidification of the extractant chlorinated alkanes
Due to its high density, the rectification waste liquid will be deposited in the reboiler at the bottom, which will reduce the heat transfer efficiency of the reboiler and cause corrosion to the reboiler

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] Extraction: The acid washing liquid produced in the production process of para-aramid fiber is neutralized and sent to the extraction tower for liquid-liquid extraction. The extraction agent is dichloromethane: carbon tetrachloride=1:1, and the solvent ratio is 1.5. The extract phase is sent to a low-high pressure rectifying column for preliminary separation of extractant and NMP.

[0018] Low-high pressure rectification: the extraction phase at the bottom of the extraction column is transported to the low pressure column for preliminary separation of the extractant and NMP, the operating pressure at the top of the column is controlled to be 40KPa, the reflux ratio is 0.1, the operating temperature of the gas phase at the top of the column is 50°C, and the operating temperature at the top of the column is 50°C. The lower layer extractant of the reflux tank is returned to the extraction tower for reuse, and the upper layer water phase is transported to the salt treatment ...

Embodiment 2

[0022] Liquid-liquid extraction: The acidic washing liquid produced in the production process of para-aramid fiber is neutralized and sent to the extraction tower for liquid-liquid extraction. The extraction agent is trichloroethane: dichloromethane=1:1, solvent The ratio is 2, and the extract phase is sent to a low-high pressure rectifying column for preliminary separation of extractant and NMP.

[0023] Low-high pressure rectification: the extraction phase at the bottom of the extraction column is transported to the low pressure column for preliminary separation of the extractant and NMP, the operating pressure at the top of the column is controlled to be 50KPa, the reflux ratio is 0.05, the operating temperature of the gas phase at the top of the column is 60°C, and the operating temperature at the top of the column is The lower layer extractant of the reflux tank is returned to the extraction tower for reuse, and the upper layer water phase is transported to the salt treatm...

Embodiment 3

[0027] Extraction: The acidic washing liquid produced in the production process of para-aramid fiber is neutralized and transported to the extraction tower for liquid-liquid extraction. The extraction agent is dichloroethane: chloroform=1:1, and the solvent ratio is 2.5. The extraction phase is sent to a low-high pressure rectifying column for preliminary separation of the extractant and NMP.

[0028] Low-high pressure rectification: the extraction phase at the bottom of the extraction column is transported to the low pressure column for preliminary separation of the extractant and NMP, the operating pressure at the top of the column is controlled to be 45KPa, the reflux ratio is 0.2, the operating temperature of the gas phase at the top of the column is 55°C, and the operating temperature at the top of the column is 55°C. The lower layer extractant of the reflux tank is returned to the extraction tower for reuse, and the upper layer water phase is transported to the salt treat...

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Abstract

The invention belongs to the technical field of polymer synthesis. For the extraction and rectification recovery process, the method of step-by-step removal in low and high-pressure towers is adopted to reduce the temperature in the tower; the flash distillation process is used to remove heavy components to avoid corrosion problems in reboilers. The recovery method of solvent NMP in the production process of para-aramid fibers involved in the present invention adopts an extraction and rectification process, which successively includes neutralization, extraction, low-pressure rectification, high-pressure rectification, deweighting and refining processes, through two steps of low and high pressure The extraction agent is recovered during rectification, and the calcium chloride and oligomers entrained in NMP are removed by thin film evaporation process; Distillate, get recovery NMP. The method for recovering solvent NMP in the para-aramid production process involved in the invention has good separation effect and high recovery rate. NMP has high purity, low water content, and low pollution discharge. It is suitable for the treatment of solvent-containing NMP wastewater and NMP recovery, especially for the recovery of solvent NMP in the production process of para-aramid fiber.

Description

technical field [0001] The invention belongs to the technical field of polymer synthesis, relates to waste water treatment technology, and particularly relates to a solvent recovery technology in waste water. Background technique [0002] Para-aramid fiber is para-aramid (PPTA) fiber, which is industrially synthesized by polycondensation of poly-p-phenylenediamine and terephthaloyl chloride. In its production process, the raw materials are p-phenylenediamine and terephthalic The acid chlorides all require the use of N-methylpyrrolidone (NMP) as the solvent for the polycondensation reaction. [0003] In the production process of para-aramid fiber, that is, para-aromatic polyamide, the existing NMP recovery methods mainly include direct distillation and extractive distillation. Among them, extractive distillation has become the main recovery method due to the high recovery rate of NMP. Extractive distillation is to use low-boiling chlorinated alkanes as extractant to extract...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D207/267
CPCC07D207/267
Inventor 杨颖郑亭路侯晓锋刘余田
Owner 山东聚芳新材料股份有限公司