CN-121990964-A - Solvent recovery method in polyphenylene sulfide resin production process

CN121990964ACN 121990964 ACN121990964 ACN 121990964ACN-121990964-A

Abstract

The invention belongs to the field of chemical material treatment, and particularly relates to a solvent recovery method in a polyphenylene sulfide resin production process, which comprises the steps of firstly cutting off an oligomer, then extracting and recovering N-methylpyrrolidone and paradichlorobenzene in a washing liquid, avoiding high-energy consumption operation of direct water evaporation, recovering an extractant in a raffinate phase in a pervaporation mode, utilizing the selective permeability of a membrane, and recovering the extractant in an azeotropic coupling stripping mode, wherein compared with the stripping separation efficiency, the energy consumption is low, on one hand, the energy consumption is reduced, on the other hand, the problem of acidification corrosion reboiler caused by heating and rectifying by a reboiler is solved, the residual components are subjected to decompression hypergravity rectification, unreacted paradichlorobenzene monomers are recovered and reused, and then NMP is subjected to treatment operations such as refining and purification, so that the efficient recovery of solvent NMP is realized.

Inventors

TIAN WEI
LI GANG
LI YUNFEI
DONG JINGHUI
LI ZHENGHUI
MA XIAO
LIU SHULIANG

Assignees

山东英联达新材料有限公司

Dates

Publication Date: 20260508
Application Date: 20251216

Claims (8)

1. The solvent recovery method in the polyphenylene sulfide resin production process is characterized by comprising the following specific steps: 1) Oligomer excision, namely settling the polyphenylene sulfide washing liquid in a settling tank provided with a filter screen to entrap the oligomer; 2) Regulating pH, namely placing the clear solution obtained by removing the oligomer in the step 1) into a pH regulating tank to regulate pH, and controlling the pH to be 6-7; 3) Continuous extraction, namely continuously extracting the solution obtained in the step 2) and the extractant in an extraction tower; 4) The light phase at the top of the extraction tower is sent to a pervaporation device for pervaporation treatment, extractant in the wastewater is recovered, and the wastewater after the extractant is recovered is sent to a factory biochemical sewage system for biochemical treatment; 5) Feeding the bottom oil phase obtained in the step 3) into an azeotropic distillation tower, obtaining a material at the top of the azeotropic distillation tower, feeding the material into a extraction tank for layering, washing the upper layer of water by using polyphenylene sulfide resin, and recycling the lower layer of extractant in a continuous extraction process; 6) The method comprises the steps of (1) conducting supergravity recovery of paradichlorobenzene, namely inputting bottom liquid of the azeotropic rectifying tower in the step 5) into a supergravity rectifying tower for supergravity rectification, obtaining water and paradichlorobenzene at the top of the supergravity rectifying tower, cooling to 40-60 ℃, layering paradichlorobenzene and water in a reflux tank connected with the top of the supergravity rectifying tower, recycling paradichlorobenzene at the lower layer as a reaction monomer in the polyphenylene sulfide production process, and washing water phase at the upper layer for the polyphenylene sulfide; 7) And (3) refining N-methylpyrrolidone, namely conveying the liquid in the tower bottom of the hypergravity rectifying tower in the step (6) to an NMP refining tower, performing reduced pressure distillation in the NMP refining tower, extracting NMP from the tower top, and conveying the liquid in the tower bottom of the NMP refining tower to the step (1) to repeat the solvent recovery treatment.
2. The method for recovering solvent in the production process of polyphenylene sulfide resin according to claim 1, wherein the polyphenylene sulfide washing liquid is derived from a polyphenylene sulfide purification washing device.
3. The method for recycling solvent in the production process of polyphenylene sulfide resin according to claim 1, wherein the sedimentation tank is provided with a three-layer filter screen with 80-200-80 meshes, a precise filter with 200-300 meshes is arranged at the water outlet of the sedimentation tank, and the trapped oligomer is sent to an oligomer crosslinking device for crosslinking after washing.
4. The method for recycling the solvent in the production process of the polyphenylene sulfide resin, which is characterized in that the extractant is selected from halogenated alkanes, the mass of the extractant is 1-3:1, the halogenated alkanes are selected from one or more of dichloromethane, chloroform and carbon tetrachloride, and the extraction tower adopts a plate tower, wherein the number of theoretical plates is 5-10.
5. The method for recycling solvent in the polyphenylene sulfide resin production process according to claim 1, wherein the pervaporation device is a pervaporation membrane separation device, and comprises a feed pretreatment system, a membrane module array with a built-in composite membrane, a low-temperature condensing system connected with the permeation side of the membrane module and a vacuum system connected with an outlet of the condensing system, 2 to 5 composite membrane modules connected in series are arranged in the pervaporation device, the composite membrane modules are PDMS/PVDF composite membranes, and the area of each PDMS/PVDF composite membrane module is 40 to 90 m 2 ; the mass content of the extractant in the top light phase of the extraction tower which is sent into the pervaporation treatment is 0.1-1%, the temperature of the side of the pervaporation feed liquid is 45-55 ℃, the side pressure of the pervaporation is 2-6Kpa, and the condensing temperature is-5 to-10 ℃.
6. The method for recovering solvent in the production process of polyphenylene sulfide resin according to claim 1, wherein the temperature of the tower bottom of the azeotropic distillation tower is 105-110 ℃, the temperature of the tower top is 50-80 ℃, and the temperature of injected steam is 180-200 ℃; And steam is input from the bottom of the azeotropic distillation tower, and is discharged from a product gas phase outlet at the top of the azeotropic distillation tower after the steam is input.
7. The method for recovering solvent in the production process of polyphenylene sulfide resin according to claim 1, wherein the rotating speed of the supergravity rectifying tower is 200-1000 r/min, the temperature of a tower bottom is 105-120 ℃, the temperature of a tower top is 90-110 ℃, the pressure of the tower top is 2-10 kPa, and the temperature of steam is 180-200 ℃.
8. The method for recovering solvent in the production process of polyphenylene sulfide resin according to claim 1, wherein the pressure at the top of the NMP refining tower is 2-10 kPa, the temperature at the bottom of the tower is 110-120 ℃, and the temperature at the top of the tower is 98-115 ℃.

Description

Solvent recovery method in polyphenylene sulfide resin production process Technical Field The invention belongs to the field of chemical material treatment, and particularly relates to a solvent recovery method in a polyphenylene sulfide resin production process. Background At present, the conventional preparation method of polyphenylene sulfide generally adopts paradichlorobenzene and sodium sulfide to carry out polymerization reaction in an NMP solvent system, and the polymerized resin is packaged and put in storage after washing and drying. The water washing liquid enters a solvent recovery system, and the main components in the washing liquid are water, NMP, oligomers, salt and unreacted monomers, wherein the water content is about 45% -50%, the NMP content is about 40% -45%, the salt content is about 2% -5%, and the other components are about 1% -3%. There are two main ways to treat the washing liquid, the current general method in industry is to directly distill and dehydrate, then decompress and distill NMP, and dry salt to be disposed of as dangerous waste. There are studies on recovery and refining of solvents by extraction, in which NMP in the washing solution is extracted with an extractant such as chloroform, the extractant in the extract phase is recovered by rectification, and the extractant entrained in the raffinate phase can be recovered by stripping. Compared with the first process scheme, the process for extracting and recovering the solvent can improve the recovery rate of the solvent NMP and the extractant, but the wastewater treatment difficulty is high, the extractant in the wastewater needs to be recovered, the mode of recovering chloroform in the raffinate phase has high energy consumption, if the chloroform is recovered in a distillation mode, the problem of residual extractant in a tower kettle exists, the extractant is easy to be decomposed and acidified by heating, the tower kettle is easy to corrode, the traditional extraction tower and the rectification tower are adopted, the separation efficiency is low, the number of plates of the rectification tower is high, and the comprehensive investment is high. Therefore, how to better process the polyphenylene sulfide washing liquid and realize the recovery of the solvent more efficiently at the same time is one of the problems to be solved in the field. Disclosure of Invention Aiming at the problems of high separation energy consumption, equipment corrosion and the like in the prior art, the invention provides a solvent recovery method in the polyphenylene sulfide production process, which comprises the specific steps of oligomer excision, pH regulation and control, continuous extraction, raffinate phase pervaporation treatment, extractant azeotropic distillation, paradichlorobenzene hypergravity recovery and N-methylpyrrolidone refining, firstly, the oligomer is cut off, then the N-methyl pyrrolidone and the paradichlorobenzene in the washing liquid are extracted and recovered by adopting a hydrophobic solvent, so that the high-energy consumption operation of direct water evaporation is avoided. The method comprises the steps of extracting the solvent from the extraction phase, recovering the extractant in the extraction phase by adopting an azeotropic coupling stripping mode, reducing the boiling point of the extractant, reducing the energy consumption on one hand, solving the problem of acidification corrosion of a reboiler caused by heating and rectifying by using the reboiler on the other hand, recovering and recycling unreacted paradichlorobenzene monomers by using reduced pressure hypergravity rectifying of the residual components, refining and purifying NMP and other treatment operations, realizing the efficient recovery of the solvent NMP, reducing the problems of solvolysis, pipeline corrosion blockage, low yield and high energy consumption in the traditional process, and has the characteristics of controllable process, high separation efficiency, low energy consumption, small pollution, high solvent purity and high yield. The main technical concept of the invention is as follows: In addition, after the water is distilled, NMP is purified, NMP is easily decomposed at the salt and high temperature, light components of decomposition products can be mixed into NMP at the top of the tower, condensed heavy components can form an adhesive body with the salt and residual oligomers, and the heat exchanger is corroded and blocked. The invention adopts the mode of coupling extraction, pervaporation, azeotropic distillation, hypergravity distillation and vacuum distillation to extract the effective components from water, then carries out low-temperature and high-efficiency separation on the effective components and the low-boiling point solvent, and realizes the recovery of NMP and paradichlorobenzene in washing water with high purity, high yield and low energy consumption. In the pervaporation process treatment, the extractant in the