Classified washing method in resin production
Through the classified washing method, the washing liquid of NMP and by-product salt is separated and entered into different evaporation systems respectively, which solves the high energy consumption problem caused by water washing in PPS resin production, achieves low-temperature concentration, and reduces steam consumption and production costs. .
Patent Information
- Application Number
- CN202411414488.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-11
- Publication Date
- 2025-01-10
AI Technical Summary
In PPS resin production, after solid-liquid separation of the polymerized product, water washing leads to an increase in the boiling point between NMP and by-product salt, resulting in high energy consumption during subsequent evaporation and concentration.
The classification washing method is used to separate the washing liquid containing the high boiling point NMP from the washing liquid containing the low boiling point by-product salt. The mixture of NMP enters the crystallization evaporation system, and the mixture of by-product salt enters the MVR or multi-effect evaporation system. Concentration was performed by cyclic reverse washing and under-pressure distillation.
Reduces energy consumption during evaporation and concentration, and saves steam consumption. Specifically, the energy consumption of NMP washing liquid entering the crystallization evaporation system alone is 1/3 of the original single-cycle evaporation, and the energy consumption of MVR evaporation is 1/2 of the original single-effect evaporation. 5.
Smart Images
Figure CN119285951A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of resin production, in particular to a method for classified washing in resin production. Background Art
[0002] In the production of PPS resin, sodium sulfide (or sodium hydrosulfide) and para-dichlorobenzene are used as raw materials, NMP is used as solvent, metal halide salts (such as lithium chloride) are used as auxiliary agents or other auxiliary agents soluble in NMP, etc., and resin is produced through dehydration, polycondensation and other process steps; the polymer product is in the form of solid-liquid slurry, and its main components include: PPS resin, auxiliary agents, by-product salts, NMP, etc. In conventional resin production, the polymer product is first separated from the solid and liquid, and then water is added to the solid resin for stirring and washing. Water can directly dissolve the by-product salts, and NMP and water are miscible in any ratio. Therefore, the mixed liquid obtained after water washing contains a certain amount of NMP, which leads to an increase in the boiling point of the mixed liquid. In the subsequent concentration, only single-effect evaporation can be used, which has high energy consumption. Summary of the invention
[0003] The object of the present invention is to provide a method for classified washing in resin production, wherein a washing liquid containing high-boiling-point NMP is separated from a washing liquid containing low-boiling-point by-product salts, and a mixed liquid for washing NMP enters a crystallization evaporation system alone; and a mixed liquid after washing by-product salts enters an MVR or multi-effect evaporation system for evaporation and dehydration, which requires a low temperature and can save steam consumption.
[0004] The present invention solves the technical problem by adopting the following technical solutions.
[0005] On the one hand, an embodiment of the present invention provides a method for classified washing in resin production, comprising the following steps:
[0006] S1, performing solid-liquid separation on the resin polymer product to obtain a mother liquor and a wet resin;
[0007] S2, washing NMP: adding saturated sodium chloride solution to the wet resin, circulating reverse washing, stirring and soaking;
[0008] S3, solid-liquid separation, to obtain a saturated sodium chloride liquid phase containing NMP and a solid phase containing resin and by-product salts, the liquid phase is added to a single-effect forced circulation evaporator for evaporation, and then vacuum distillation is performed;
[0009] S4, washing by-product salt: adding desalted water to the solid phase after solid-liquid separation in step S3, circulating countercurrent washing, solid-liquid separation, to obtain solid phase resin and liquid phase brine, adding the brine to the MVR evaporator for evaporation and concentration to obtain by-product salt.
[0010] In some embodiments of the present invention, in the step S1, the moisture content of the wet resin is 40-50%.
[0011] In some embodiments of the present invention, in S2, the temperature of the stirring and soaking is 40-60°C.
[0012] In some embodiments of the present invention, in S2, the stirring and soaking time is 1-2 hours.
[0013] In some embodiments of the present invention, in S2, the number of cyclic countercurrent washing is 2-3 times.
[0014] In some embodiments of the present invention, in S4, the number of cyclic countercurrent washing is 6-8 times.
[0015] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects:
[0016] The resin washing method provided by the present invention adopts different detergents for washing treatment for different substances, separates the washing liquid containing high-boiling-point NMP from the washing liquid containing low-boiling-point by-product salts, facilitates the subsequent concentration treatment of the washing liquid, reduces the energy consumption during evaporation and concentration, and reduces the production cost. Specifically, the mixed liquid for washing NMP enters the crystallization evaporation system alone; the mixed liquid after washing the by-product salts enters the MVR or multi-effect evaporation system for evaporation and dehydration, which requires a low temperature and can save steam consumption. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.
[0018] Figure 1 The following is a flow chart of the classification washing process according to an embodiment of the present invention. DETAILED DESCRIPTION
[0019] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.
[0020] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to specific embodiments.
[0021] On the one hand, an embodiment of the present invention provides a method for classified washing in resin production, comprising the following steps:
[0022] S1, the resin polymer product is subjected to solid-liquid separation to obtain a mother liquor and a wet resin; the mother liquor is directly subjected to evaporation and concentration treatment; the wet solid resin components are PPS particles and powder, by-product salt particles, NMP, etc., and the N-methylpyrrolidone (NMP) in the wet resin is about 1 / 4 of the NMP input before the polymerization reaction.
[0023] S2, washing NMP: adding saturated sodium chloride solution to the wet resin, circulating reverse washing, stirring and soaking; the sodium chloride solution displaces the NMP in the resin, that is, after washing with the saturated sodium chloride solution, the NMP in the wet resin enters the saturated sodium chloride solution;
[0024] S3, solid-liquid separation, to obtain a saturated sodium chloride liquid phase containing NMP, a solid phase containing resin and by-product salts, the liquid phase is added to a single-effect forced circulation evaporator for evaporation, and then vacuum distillation is performed to obtain NMP with a concentration of ≥99%. Compared with the mixed washing evaporation in the prior art, the evaporation amount is reduced by 2 / 3, which is 1 / 3 of the original single-cycle evaporation energy consumption.
[0025] S4, washing by-product salt: adding desalted water to the solid phase after solid-liquid separation in step S3, circulating countercurrent washing, solid-liquid separation, to obtain solid phase resin and liquid phase brine, adding the brine to the MVR evaporator for evaporation and concentration to obtain by-product salt. The energy consumption of MVR evaporation is 1 / 5 of that of single-effect evaporation.
[0026] In some embodiments of the present invention, in the step S1, the moisture content of the wet resin is 40-50%.
[0027] In some embodiments of the present invention, in S2, the temperature of stirring and soaking is 40-60° C. Stirring at this temperature can increase the solubility of NMP in the saturated sodium chloride solution and improve the washing efficiency.
[0028] In some embodiments of the present invention, in S2, the stirring and soaking time is 1-2 hours.
[0029] In some embodiments of the present invention, in S2, the number of cyclic countercurrent washing is 2-3 times.
[0030] In some embodiments of the present invention, in S4, the number of cyclic countercurrent washing is 6-8 times.
[0031] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.
[0032] Example 1
[0033] Sodium sulfide and p-dichlorobenzene are used as raw materials, NMP is used as solvent, lithium chloride is used as auxiliary agent, and other auxiliary agents are used to carry out polymerization reaction to produce PPS resin to obtain resin polymerization products. The resin polymerization products are classified and washed according to the following steps:
[0034] S1, the resin polymer product is subjected to solid-liquid separation to obtain a mother liquor and a wet resin; the mother liquor is directly subjected to evaporation and concentration treatment; the wet solid resin components are PPS particles and powder, by-product salt particles, NMP, etc., and the N-methylpyrrolidone (NMP) in the wet resin is about 1 / 4 of the NMP input before the polymerization reaction.
[0035] S2, washing NMP: adding saturated sodium chloride solution to the wet resin, circulate reverse washing for 3 times, and soak at 60°C with stirring for 2 hours; the sodium chloride solution displaces the NMP in the resin, that is, after washing with the saturated sodium chloride solution, the NMP in the wet resin enters the saturated sodium chloride solution;
[0036] S3, using a centrifuge to perform solid-liquid separation to obtain a saturated sodium chloride liquid phase containing NMP and a solid phase containing resin and by-product salts, adding the liquid phase to a single-effect forced circulation evaporator for evaporation, and then performing vacuum distillation to obtain NMP with a concentration of ≥99%;
[0037] S4, washing by-product salt: adding desalted water to the solid phase after solid-liquid separation in step S3, circulating countercurrent washing for 8 times, solid-liquid separation, obtaining solid phase resin and liquid phase brine, adding the brine to the MVR evaporator for evaporation and concentration, obtaining by-product salt.
[0038] Example 2
[0039] The resin polymer product obtained by the same process as in Example 1 is used as the washing object, and the resin polymer product is classified and washed according to the following steps:
[0040] S1, the resin polymer product is subjected to solid-liquid separation to obtain a mother liquor and a wet resin; the mother liquor is directly subjected to evaporation and concentration treatment; the wet solid resin components are PPS particles and powder, by-product salt particles, NMP, etc., and the N-methylpyrrolidone (NMP) in the wet resin is about 1 / 4 of the NMP input before the polymerization reaction.
[0041] S2, washing NMP: adding saturated sodium chloride solution to the wet resin, cyclically washing in reverse for 5 times, stirring and soaking at 40°C for 2 hours; the sodium chloride solution displaces the NMP in the resin, that is, after washing with the saturated sodium chloride solution, the NMP in the wet resin enters the saturated sodium chloride solution;
[0042] S3, using a centrifuge to perform solid-liquid separation to obtain a saturated sodium chloride liquid phase containing NMP and a solid phase containing resin and by-product salts, adding the liquid phase to a single-effect forced circulation evaporator for evaporation, and then performing vacuum distillation to obtain NMP with a concentration of ≥99%;
[0043] S4, washing by-product salt: adding desalted water to the solid phase after solid-liquid separation in step S3, circulating countercurrent washing for 10 times, solid-liquid separation, to obtain solid phase resin and liquid phase brine, adding the brine to the MVR evaporator for evaporation and concentration to obtain by-product salt.
[0044] Example 3
[0045] The resin polymer product obtained by the same process as in Example 1 is used as the washing object, and the resin polymer product is classified and washed according to the following steps:
[0046] S1, the resin polymer product is subjected to solid-liquid separation to obtain a mother liquor and a wet resin; the mother liquor is directly subjected to evaporation and concentration treatment; the wet solid resin components are PPS particles and powder, by-product salt particles, NMP, etc., and the N-methylpyrrolidone (NMP) in the wet resin is about 1 / 4 of the NMP input before the polymerization reaction.
[0047] S2, washing NMP: adding saturated sodium chloride solution to the wet resin, cyclically washing in reverse for 5 times, stirring and soaking at 60°C for 1 hour; the sodium chloride solution displaces the NMP in the resin, that is, after washing with the saturated sodium chloride solution, the NMP in the wet resin enters the saturated sodium chloride solution;
[0048] S3, using a centrifuge to perform solid-liquid separation to obtain a saturated sodium chloride liquid phase containing NMP and a solid phase containing resin and by-product salts, adding the liquid phase to a single-effect forced circulation evaporator for evaporation, and then performing vacuum distillation to obtain NMP with a concentration of ≥99%;
[0049] S4, washing by-product salt: adding desalted water to the solid phase after solid-liquid separation in step S3, circulating countercurrent washing for 10 times, solid-liquid separation, to obtain solid phase resin and liquid phase brine, adding the brine to the MVR evaporator for evaporation and concentration to obtain by-product salt.
[0050] In summary, the resin washing method provided by the present invention adopts different detergents for washing treatment for different substances, separates the washing liquid containing high-boiling-point NMP from the washing liquid containing low-boiling-point by-product salts, facilitates the subsequent concentration treatment of the washing liquid, reduces the energy consumption during evaporation and concentration, and reduces production costs. Specifically, the mixed liquid for washing NMP enters the crystallization evaporation system alone; the mixed liquid after washing the by-product salts enters the MVR or multi-effect evaporation system for evaporation and dehydration, which requires a low temperature and can save steam consumption. In step S2, the energy consumption is 1 / 3 of the original single-cycle evaporation energy consumption; in step S3, the MVR evaporation energy consumption is 1 / 5 of the original single-effect evaporation.
[0051] The embodiments described above are part of the embodiments of the present invention, rather than all of the embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
Claims
1. A method for classified washing in resin production, characterized in that: The following steps are involved: S1, performing solid-liquid separation on the resin polymer product to obtain a mother liquor and a wet resin; S2, washing NMP: adding saturated sodium chloride solution to the wet resin, circulating reverse washing, stirring and soaking; S3, solid-liquid separation, to obtain a saturated sodium chloride liquid phase containing NMP and a solid phase containing resin and by-product salts, the liquid phase is added to a single-effect forced circulation evaporator for evaporation, and then vacuum distillation is performed; S4, washing by-product salt: adding desalted water to the solid phase after solid-liquid separation in step S3, circulating countercurrent washing, solid-liquid separation, to obtain solid phase resin and liquid phase brine, adding the brine to the MVR evaporator for evaporation and concentration to obtain by-product salt.
2. The method for classified washing in resin production according to claim 1, characterized in that: In the step S1, the moisture content of the wet resin is 40-50%.
3. The method for classified washing in resin production according to claim 1, characterized in that: In S2, the temperature of the stirring and soaking is 40-60°C.
4. The method for classified washing in resin production according to claim 1, characterized in that: In S2, the stirring and soaking time is 1-2 hours.
5. The method for classified washing in resin production according to claim 1, characterized in that: In S2, the countercurrent washing is performed 2-3 times.
6. The method for classified washing in resin production according to claim 1, characterized in that: In S4, the number of cycles of countercurrent washing is 6-8 times.