CN113105630B - Solvent recovery process in polyphenylene sulfide production process flow - Google Patents

Solvent recovery process in polyphenylene sulfide production process flow Download PDF

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CN113105630B
CN113105630B CN202110401653.0A CN202110401653A CN113105630B CN 113105630 B CN113105630 B CN 113105630B CN 202110401653 A CN202110401653 A CN 202110401653A CN 113105630 B CN113105630 B CN 113105630B
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sodium chloride
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CN113105630A (en
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贺鹏勇
马茂祥
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Shenzhen Huaying New Material Co ltd
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    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G75/00—Macromolecular compounds obtained by reactions forming a linkage containing sulfur with or without nitrogen, oxygen, or carbon in the main chain of the macromolecule
    • C08G75/02—Polythioethers
    • C08G75/0204—Polyarylenethioethers
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G75/00—Macromolecular compounds obtained by reactions forming a linkage containing sulfur with or without nitrogen, oxygen, or carbon in the main chain of the macromolecule
    • C08G75/02—Polythioethers
    • C08G75/0204—Polyarylenethioethers
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    • C08G75/0254—Preparatory processes using metal sulfides

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Abstract

The invention provides a solvent recovery process in a polyphenylene sulfide production process flow, which adopts polyhydrated vulcanizationSodium and p-dichlorobenzene as raw materials, N-methyl-2-pyrrolidone as a solvent, and dehydrating, polycondensing and the like to produce the polyphenylene sulfide resin, wherein a filter cake is a mixture of the polyphenylene sulfide resin, sodium chloride and an NMP solvent, and a filtrate is a mixture of NMP and H 2 O, an alkali metal organic salt and sodium chloride, adding a certain amount of water-soluble acidic substance to the filtrate, converting the alkali metal organic salt in the filtrate into an organic acid and an alkali metal water-soluble salt-sodium chloride, removing the organic acid and water by evaporation under reduced pressure, and then distilling, purifying and recovering the NMP solvent containing a small amount of water to obtain the NMP solvent with a purity of 99.96-99.98%.

Description

Solvent recovery process in polyphenylene sulfide production process flow
Technical Field
The invention relates to the technical field of recovery of high polymer materials, in particular to a solvent recovery process in a production process flow of polyphenylene sulfide resin.
Background
In U.S. patent numbers: 3354129 discloses a process for the production of polyarylene sulfide by polymerization of at least one polyhalo-substituted cyclic compound with an alkali metal sulfide in a reaction medium containing a polar organic solvent, as disclosed in the patents related to the invention of Edmond and Hill, which are incorporated herein by reference. Polyphenylene sulfide resins, hereinafter PAS for short, a semi-crystalline polyphenylene sulfide polymer is an important industrial raw material, hereinafter PPS for short, and its industrial production process is to mix the same amount of sodium sulfide, or a mixture of sodium hydrosulfide and sodium hydroxide in approximately equal molar amounts, with the subsequent addition of P-DCB in cyclic amides such as: NMP/N-methyl pyrrolidone in a reaction medium.
In the production of polyphenylene sulfide resins, several preferred methods of recovering the reaction product of polyphenylene sulfide are employed in a process of refluxing a solid filter cake impregnated with an initial solvent to wash the PPS reaction product, wherein steam is introduced as a separated polymer solid substance as the filter cake used therein, and the washing operation is mainly aimed at replacing the initial solvent in the wet solid filter cake with a washing solvent to wash out the solid substance which can be dissolved in the solid filter cake to the maximum extent, such as: multistage washing with a very large amount of washing solvent, with essentially no initial liquid solvent in the solid cake at the last stage of the washing operation, i.e. only washing solvent remaining in the cake, is economical to operate to the extent of washing, however, instead of completely replacing all of the initial liquid solvent with washing solvent, in the usual case, a small amount of initial liquid solvent remains in the solid cake after the washing operation.
The equipment installed for the reflux washing operation requires a suitable number of stages, typically 2 to 6 stages in the PPS washing operation scheme, to achieve a high desired, i.e., low level, ratio of the initial liquid solvent remaining in the filter cake at the last stage of the washing operation.
In the production process of polyphenylene sulfide resin, basically, sodium sulfide and P-dichlorobenzene (P-DCB) are used as raw materials, in the process of Producing Polyphenylene Sulfide (PPS) resin by polycondensation under the action of an alkali metal cosolvent, NMP (N-methylpyrrolidone) addition solution of alkali metal chloride is needed to complete polymerization reaction in the polymerization stage, compared with the cost of other raw materials, NMP and the alkali metal cosolvent occupy equivalent price proportion, but the solvent NMP and the cosolvent are not consumed in theory in the production process of PPS, therefore, whether the NMP solvent can be recovered at a higher recovery rate is the key of reducing the production cost of PPS.
After the polymerization reaction is finished, 50-60% of NMP can be recovered by a conventional method, but 48-38% of the residual NMP is combined with polyphenylene sulfide resin, an assistant and a byproduct, namely sodium chloride, and is wrapped in the polyphenylene sulfide resin, the assistant is an alkali metal organic acid salt dissolved in an NMP solvent, the melting point of some alkali metal organic acid salts is 200-204 ℃, the boiling point of some alkali metal organic acid salts is far higher than that of the NMP solvent, the alkali metal organic acid salts are extremely difficult to separate, the partial NMP cannot be recovered even under a vacuum condition, meanwhile, in the recovery process flow of the polyphenylene sulfide resin, a large amount of deionized water is needed to wash the polyphenylene sulfide resin, and further, the solvent to be recovered contains a large amount of water, sodium chloride and some organic impurities.
In the united states patent number US5711873, a technology for recovering the solvent in the production of polyphenylene sulfide resin is introduced, which uses a low boiling point solvent as the diluent of the reaction system, although the addition of a low boiling point organic solvent in the reaction system is helpful for the filtration of the reaction mixture, and the low boiling point solvent is also easy to recover and purify, the requirement on the material of the polymerization reaction kettle is high, if the low boiling point organic solvent is added in the later stage of the reaction system, the pressure of the reaction kettle is increased, and at the same time, the reaction kettle needs to be kept above the designed pressure, which may cause serious accidents.
In chinese patent No:201110229729.2 describes a solvent recovery process in a polyphenylene sulfide resin production process, which adopts sodium sulfide dihydrate and p-dichlorobenzene as raw materials to produce the polyphenylene sulfide resin through the process steps of dehydration, polycondensation and the like. After the polycondensation reaction is finished, the lithium chloride cosolvent is subjected to solid-liquid first-stage separation, then the solid-liquid first-stage separation is carried out, then a second-stage filtration, evaporation and further treatment are carried out by a single-screw evaporator, NMP crude solutions containing certain impurities are respectively obtained, the NMP solvent is further rectified and purified by a rectifying tower to obtain the NMP solvent with the purity of 99.98%, the NMP solvent is reused for synthesizing the polyphenylene sulfide resin, the recovery rate of the NMP solvent is 97-98.5%, the raw materials are saved, and the production cost of the PPS is reduced.
In chinese patent No:201110066328. a solvent and catalyst recovery technique in the production of polyphenyl thioether is introduced in X, after the polycondensation reaction is completed, 1-3mol/mol Na is added 2 And S, using fresh NMP solvent as a diluent, enabling the reaction system to obtain another mixture under the dilution of NMP, and respectively obtaining a mixed solution containing NMP and water and a powdery mixture containing a cosolvent and a byproduct after the mixture is filtered, extracted, evaporated and further processed by a spiral evaporator. The mixed solution of NMP and water is evaporated to remove water to obtain NMP solvent containing certain impurities, the NMP solvent is further rectified and purified by a rectifying tower to obtain NMP solvent with the purity of 99.98 percent, and the NMP solvent is reused for the synthesis of polyphenylene sulfide resin, and the catalyst lithium chloride with the recovery rate of 96 percent, the purity of 99.9 to 99.98 percent and the recovery rate of 98 to 99 percent is obtained.
Disclosure of Invention
The invention provides a solvent recovery process in a polyphenylene sulfide production process flow, and aims to create a new method for recovering a solvent in polyphenylene sulfide production, so that NMP and a cosolvent which are remained in a solid solution form can be efficiently recovered, the production cost of PPS is reduced, and meanwhile, the purity of the NMP solvent is improved on the basis of shortening the recovery process flow, so that the level of a similar foreign recovery device is reached or exceeded.
The technical scheme adopted by the invention is as follows:
the invention adopts sodium sulfide and p-dichlorobenzene as raw materials, N-methyl-2-pyrrolidone (NMP for short) as solvent, and produces polyphenylene sulfide resin through the process steps of dehydration, polycondensation and the like, wherein the filter cake is a mixture of the polyphenylene sulfide resin, sodium chloride and the NMP solvent, and the filtrate is NMP, H and the like 2 Adding a certain amount of water-soluble acidic substance into filtrate to convert the alkali metal organic acid salt in the filtrate into organic acid and alkali metal water-soluble salt-sodium chloride, and distilling and purifying the NMP solvent containing a small amount of water after removing the organic acid and the water by reduced pressure evaporation, wherein the NMP solvent recovery process comprises the following steps:
(1) 5-35% by weight of NMP, 1.5-3.5% by weight of alkali metal organic acid salts of sodium benzoate or sodium formate or sodium acetate or sodium propionate or sodium butyrate, 10-25% by weight of sodium chloride, 36.5-71.5% by weight of wtH to 100L with a stirring speed of 10-50 rpm 2 Adding 10-30L of hydrochloric acid or ammonium chloride water-soluble acidic liquid with the concentration of 3-8%v/v into the mixed liquid of O at the flow rate of 0.3-0.8L/min, and inputting the mixed liquid into a 316L stainless steel jacket evaporation kettle when the pH value of the mixed liquid is measured to be 0-4 by an on-line acidimeter; at this time the mixed liquid contains 10-30% wt of NMP, 1.0-3.0% wt of benzoic acid or formic acid or acetic acid or propionic acid or butyric acid organic acid, 10-22% wt of sodium chloride, 0.3-0.8% wt of water-soluble acidic liquid, 44.2-78.7% wt of H 2 O; if the water-soluble acidic liquid is ammonium chloride, NMP and H are contained 2 Acidifying the mixed liquid of O, alkali metal organic salt and sodium chloride, the mixed liquid containing NMP 10-30 wt%, sodium chloride 11-28 wt%, and wtH 44.2-78.7% 2 O, 0.3 to 0.8% by weight of an excess amount of water-soluble acid; 1.0 to 3.0% by weight of a composition comprising ammonium benzoate or ammonium formate or ammonium acetate or ammonium propionate or ammonium butyrate;
(2) The mixed solution acidified in the step (1) is put into a 200L 316L stainless steel jacket for evaporationThe kettle inputs heat-conducting oil from the bottom of a jacket of the 316L stainless steel jacket evaporation kettle, outputs the heat-conducting oil from the top of the jacket, and carries out heat exchange on the heat-conducting oil containing NMP and H 2 Heating the mixed liquid of O, organic acid and sodium chloride, stirring the mixed liquid at a stirring speed of 30-80 rpm, starting a vacuum pump when the temperature reaches 60-90 ℃, enabling water vapor to flow out of the top of a 316L stainless steel jacket evaporation kettle, cooling the mixed liquid by a condenser arranged at the top, flowing into a wastewater treatment process, treating the wastewater for recycling, inputting the mixed liquid into a solid-liquid separation centrifuge for separation when the solution in the 316L stainless steel jacket evaporation kettle is changed into brown, measuring the viscosity of the mixed liquid to be 2.0-6.0cPa.s by a linear viscometer when crystals are crystallized, detecting the water content in the mixed liquid to be 0.5-0.9 percent by weight by liquid chromatography, and inputting the solid into a recovery and drying device of the sodium chloride, wherein the solid is light green sodium chloride containing a small amount of NMP and organic impurities; inputting the filtrate into an NMP solvent recovery rectifying tower;
(3) Inputting the light green sodium chloride solid containing a small amount of NMP and organic impurities separated in the step (2) into a spiral dryer, respectively configuring a phi 60 steam outlet at the front part, the middle part and the tail part of the spiral dryer, connecting the outlet with the lower opening of a condenser tube side, connecting the upper outlet of the condenser tube side with the inlet of a vacuum pump, cooling the steam containing NMP evaporated from the spiral dryer by a condenser, and inputting the steam containing NMP and H 2 The mixed liquid of O, alkali metal organic acid salt and sodium chloride is acidified and concentrated, and then is input into a rectifying tower for rectification, cooling water is input from a lower opening of a shell pass of a condenser, and is output to a circulating water storage tank from an upper opening of the shell pass of the condenser for recycling;
(4) Separating the mixed liquid containing NMP obtained in the step (2), inputting the mixed liquid from the middle part of a rectifying tower at an input speed of 2-8L/min, assembling a 20L glass jacket evaporator at the lower part of the rectifying tower, assembling a magnetic stirrer below the glass jacket evaporator, stirring the mixed liquid containing the NMP solvent which is not evaporated at a stirring speed of 30-60 rpm, inputting heat conduction oil from the bottom of a glass jacket expander, outputting the heat conduction oil from the top of the glass jacket evaporator, inputting the evaporated NMP steam into a condenser arranged at the top of the rectifying tower, inputting the NMP steam from a tube pass bottom inlet of the condenser, connecting a top outlet of the condenser with an inlet of a vacuum pump, cooling the NMP steam by the condenser, flowing out from the lower end of a tube pass of the condenser, detecting the NMP content to be 99.96-99.98 wt by a liquid chromatograph, inputting the NMP storage tank, returning the unqualified NMP to a crude product temporary storage tank, and inputting the NMP into the rectifying tower for purification again; the cooling water of the condenser is input from the bottom inlet of the condenser shell pass, is output from the upper part of the condenser shell pass and flows into the circulating water storage tank, and is used after being cooled.
The process flow for recovering the polyphenylene sulfide resin production solvent has the following characteristics:
1. in the process of the invention, NMP and H are reduced 2 Concentrating the mixed liquid of O, alkali metal salt of organic acid and sodium chloride to remove water, and adding NMP and H 2 The mixed liquid of O, alkali metal organic acid salt and sodium chloride is acidified to reduce the viscosity of the concentrated mixed liquid, and analyzed to find that the mixed liquid contains NMP and H 2 In the mixed liquid of O, alkali metal organic acid salt and sodium chloride, the alkali metal organic acid salt, i.e. sodium benzoate, sodium acetate, sodium formate, sodium propionate and sodium butyrate, especially sodium benzoate and sodium butyrate, gradually reaches the saturated state with the evaporation of water, at this time, the water solution containing NMP, H and sodium chloride is not only enabled to be gradually saturated 2 The azeotropic point of the mixed liquid of O, alkali metal organic acid salt and sodium chloride is increased, and NMP and H are also added 2 The viscosity of the mixed liquid of O, alkali metal organic acid salt and sodium chloride obviously increases the current of a stirring motor, repeated experiments show that proper addition of water-soluble acidic liquid is helpful for reducing the viscosity of the residual solution after concentration and dehydration, and analysis shows that after the water-soluble acidic liquid is added, NMP and H are contained 2 In the mixed liquid of O, organic acid and sodium chloride, the organic acid, i.e. benzoic acid or formic acid or acetic acid or butyric acid or propionic acid, is removed along with the continuous evaporation of water, so that the content of NMP and H is reduced 2 The viscosity of the mixed liquid of O and sodium chloride is not increased, and NMP and H are not included 2 The azeotropic point of the mixed liquid of O and sodium chloride is increased, and simultaneouslyThe current of the stirring motor is kept stable, and the low boiling point organic acid such as benzoic acid, formic acid, acetic acid, butyric acid or propionic acid is removed by distillation of water.
2. In the process flow for recovering the polyphenylene sulfide resin production solvent, an online acidimeter is used for improving the production efficiency, and the aim is to reduce NMP and H 2 The measurement times of the pH value of the mixed liquid of O, organic acid and sodium chloride can be simultaneously reduced by online detection, the addition of the water-soluble acidic liquid can be reduced, and NMP and H can be contained 2 The acidification degree of the mixed liquid of O, organic acid and sodium chloride is effectively controlled, so that the production cost can be saved, the production efficiency can be improved, and if the hydrochloric acid is added excessively, the NMP solvent can be subjected to ring opening under the high-temperature condition, so that the recovery rate of the NMP solvent is reduced; if the addition amount of the hydrochloric acid is insufficient, the energy consumption of solvent recovery is increased.
3. In the process flow for recovering the polyphenylene sulfide resin production solvent, NMP and H are contained in order to save energy 2 In the evaporation process of acidified mixed liquid of O, organic acid and sodium chloride, on-line viscosity detection is adopted, so that NMP and H can be controlled to be contained 2 The concentration of residual liquid after the water content of the mixed liquid of O, organic acid and sodium chloride and the organic acid are evaporated and removed can be effectively controlled to contain NMP and H 2 The viscosity of the residual liquid after the mixed liquid moisture of O, organic acid and sodium chloride and the organic acid are evaporated and removed, and the input quantity of the heat conduction oil can be effectively controlled, so that the energy can be saved, the recovery efficiency of the NMP solvent can be improved, and the content of NMP and H can be effectively controlled 2 The water content of the mixed liquid of O, organic acid and sodium chloride and the water content of the residual liquid after the organic acid is removed by evaporation.
4. In order to recover and obtain high-purity NMP, the invention acidifies NMP and H 2 In the process of mixing O, alkali metal benzoate or acetate or formate or propionate or butyrate and sodium chloride mixed liquid, strong oxidizing acid or its strong oxidizing acid weak base salt is not used as far as possible, and the purpose is to avoid the use of strong oxidizing acid or its strong oxidizing acid weak base salt under the condition of strong oxidizing acid, especially under the condition of strong oxidizing acidThe use of a strong oxidizing acid for ring-opening the NMP solvent under heating not only reduces the recovery rate of the NMP solvent but also makes the NMP ring-opened product less likely to be removed by evaporation of water because the NMP ring-opened product has a high boiling point almost equivalent to that of the NMP solvent, and if the NMP solvent is ring-opened and forms a salt with another compound, the melting point of the salt is close to that of NMP and the contents of NMP and H are increased 2 The viscosity of the mixed liquid of O, organic acid and sodium chloride is reduced, and the ring opening rate of NMP solvent under strong acid condition is monitored by using an on-line acidimeter 2 The pH value of the mixed liquid of O, organic acid and sodium chloride can be detected, so that NMP and H can be detected 2 The pH value of the mixed liquid of O, organic acid and sodium chloride can be controlled, the addition amount of dilute hydrochloric acid or ammonium chloride can be controlled, and the content of NMP solvent containing NMP and H can be reduced 2 The yield of the ring-opening reaction occurs in the process of evaporating and removing water from the mixed liquid of O, benzoic acid or formic acid or acetic acid or propionic acid or butyric acid organic acid and sodium chloride, and the hydrochloric acid, benzoic acid and the like contain NMP and H along with the evaporation and removal of water, hydrochloric acid, benzoic acid and the like 2 The concentration of the mixed liquid of O and sodium chloride is lower and lower, so that the ring-opening decomposition of the NMP solvent can be controlled, the recovery rate of the NMP solvent can be improved, and the production cost of the polyphenylene sulfide resin can be reduced.
5. In the process of synthesizing the polyphenylene sulfide resin, in order to adjust the molecular weight distribution coefficient of the polyphenylene sulfide resin, after the heat preservation at 255 ℃, a certain molecular weight and molecular weight distribution coefficient regulator sodium benzoate or sodium formate or sodium acetate or sodium propionate or sodium butyrate is added.
6. In the process of recovering the NMP solvent, sodium chloride crystals are separated out from a tan solution, and the solution is in a light green solid in the air after solid-liquid separation, becomes a light red brown solid after air oxidation, and becomes a tan solid after being dried by a spiral dryer.
7. In the process of recovering the NMP solvent, a small amount of the polyphenylene sulfide resin enters the solvent containing NMP and H through the filter screen in the process of filtering the polyphenylene sulfide resin 2 In the mixed liquid of O, the alkali metal organic acid salt and sodium chloride, the polyphenylene sulfide resin is not dissolved in water and NMP solvent, and the amount is small, so that the polyphenylene sulfide resin can be ignored.
8. The composition of the mixed liquid of the present invention was measured using an Agilent1200 liquid chromatograph and a GC7900 gas chromatograph.
The process flow of the invention is briefly described as follows:
under a certain stirring condition, adding NMP and H 2 In the evaporation kettle of the mixed liquid of O, alkali metal organic acid salt and sodium chloride, water-soluble acidic liquid with certain concentration is added in a flowing line manner, and NMP and H are contained under the monitoring of a linear acidimeter 2 The pH value of the mixed liquid of O, organic acid and sodium chloride is controlled within the range of 0-4, and then NMP and H are contained 2 The mixed liquid of O, organic acid and sodium chloride is stirred by a magnetic stirrer to begin to evaporate water, excessive water-soluble acidic liquid and benzoic acid or formic acid or acetic acid or propionic acid or butyric acid generated by acidification, and then NMP and H are contained 2 Continuously concentrating mixed liquid of O, organic acid and sodium chloride, continuously increasing the concentration of system materials, under the monitoring of an linear viscometer, when the viscosity of the system reaches 2.0-6.0 cPa.s, the liquid in the system is changed into brown, and when sodium chloride crystals are separated out, performing solid-liquid centrifugal separation on the materials in the system, oxidizing solid substances by air to be light green, inputting the solid substances into a sodium chloride recovery process, and inputting filtrate into an NMP solvent recovery process.
Inputting light green solid sodium chloride containing small amount of NMP solvent, water, formic acid or acetic acid or propionic acid or butyric acid and other insoluble organic substances which are possibly generated after acidification treatment into a spiral dryer for drying, cooling and recovering the NMP solvent and water, and mixing with NMP, H and water 2 And mixing the mixed liquid of O, alkali metal organic acid salt and sodium chloride, and then recovering the NMP solvent.
Performing solid-liquid separation to obtain mixed liquid containing NMP, inputting the mixed liquid from the middle part of a rectifying tower at a certain input speed, assembling a glass jacket evaporator at the lower part of the rectifying tower, assembling a magnetic stirrer below the glass jacket evaporator, stirring the mixed liquid containing the NMP solvent which is not evaporated at a certain stirring speed, inputting heat conduction oil from the bottom of the glass jacket expander, outputting the heat conduction oil from the top of the glass jacket evaporator, inputting the evaporated NMP steam into a condenser arranged at the top of the rectifying tower, inputting the evaporated NMP steam from a bottom inlet of a tube pass of the condenser, connecting a top outlet of the condenser with an inlet of a vacuum pump, cooling the NMP steam by the condenser, then outputting the cooled NMP steam from the lower end of the tube pass of the condenser, detecting that the NMP content is 99.96-99.98 wt by a liquid chromatograph, inputting the cooled NMP steam into an NMP storage tank, returning the unqualified NMP to a crude NMP temporary storage tank, and inputting the NMP rectifying tower for rectification and purification again; the cooling water of the condenser is input from the inlet at the bottom of the shell pass of the condenser, is output from the upper part of the shell pass of the condenser and flows into the circulating water storage tank, and is reused after being cooled.
Detailed Description
Example 1
(1) 15% wt of NMP,1.5% wt of sodium benzoate, 10% wt of sodium chloride, 73.5% wt 2 Adding 30L of 3%v/v hydrochloric acid solution into the O mixed liquid, and inputting the mixed liquid into a 316L stainless steel jacket evaporation kettle when the pH value of the mixed liquid is 4 measured by an on-line acidimeter; at this time, the mixed liquid contained 10% wt of NMP,11% wt of sodium chloride, 0.3% wt of excess hydrochloric acid, 77.7% wt of H 2 O,1.0% by weight of benzoic acid;
(2) Inputting the acidified mixed solution in the step (1) into a 200L 316L stainless steel jacket evaporation kettle, inputting heat-conducting oil from the bottom of a jacket of the 316L stainless steel jacket evaporation kettle, outputting the heat-conducting oil from the top of the jacket, and carrying out reaction on the heat-conducting oil containing NMP and H 2 Heating the mixed liquid of O, benzoic acid and sodium chloride, stirring the mixed liquid at a stirring speed of 30rpm, starting a vacuum pump when the temperature reaches 60 ℃, enabling water vapor to flow out of the top of a 316L stainless steel jacket evaporation kettle, cooling the water vapor by a condenser arranged at the top, flowing into a wastewater treatment process, recycling the treated water vapor, and when 316L is not used, stirring the mixed liquid at a stirring speed of 30rpmWhen the solution in the evaporation kettle with the steel jacket becomes brown and crystals are separated out, the viscosity of the mixed liquid is measured to be 6.0cPa.s by an on-line viscometer, and when the water content in the mixed liquid reaches 0.5 percent by weight by liquid chromatography, the rest mixed liquid is input into a solid-liquid separation centrifuge for separation, the solid is light green sodium chloride containing a small amount of NMP and organic impurities, and the sodium chloride is input into a recovery and drying device; inputting the filtrate into an NMP solvent recovery rectifying tower;
(3) Inputting the light green sodium chloride solid containing a small amount of NMP and organic impurities separated in the step (2) into a spiral dryer, respectively configuring a steam outlet with phi 60 at the front part, the middle part and the tail part of the spiral dryer, connecting the outlet with the lower opening of a condenser tube pass, connecting the upper outlet of the condenser tube pass with the inlet of a vacuum pump, cooling the steam containing NMP evaporated from the spiral dryer by a condenser, and inputting the steam containing NMP and H 2 Acidifying and concentrating the mixed liquid of O, sodium benzoate and sodium chloride, then rectifying the mixed liquid in a rectifying tower, inputting cooling water from the lower opening of the shell pass of the condenser, and outputting the cooling water from the upper opening of the shell pass of the condenser to a circulating water storage tank for recycling;
(4) Separating the liquid mixture containing NMP from the step (2), inputting the liquid mixture from the middle part of the rectifying tower at an input speed of 2L/min, arranging a 20L glass jacket evaporator at the lower part of the rectifying tower, arranging a magnetic stirrer below the glass jacket evaporator, stirring the liquid mixture containing the NMP solvent which is not evaporated at a stirring speed of 30rpm, inputting heat conduction oil from the bottom of the glass jacket evaporator, outputting the heat conduction oil from the top of the glass jacket evaporator, inputting the evaporated NMP steam into a condenser arranged at the top of the rectifying tower, inputting the evaporated NMP steam from a tube pass bottom inlet of the condenser, connecting a top outlet of the condenser with an inlet of a vacuum pump, cooling the NMP steam by the condenser, flowing out from the lower end of a tube pass of the condenser, detecting the NMP content of 99.96 wt% by a liquid chromatograph, and inputting the cooled NMP steam into a storage tank, wherein the NMP solvent recovery rate of the experiment is 97.69%.
Example 2
(1) 35% wt of NMP to 100L, 3.5% wt of sodium benzoate, 25% wt36.5% of sodium chloride, 36.5% 2 Adding 10L of 8%v/v hydrochloric acid solution into the O mixed liquid, and inputting the mixed liquid into a 316L stainless steel jacket evaporation kettle when the pH value of the mixed liquid is 0 by using an on-line acidimeter; at this time, the mixed liquid contained 30% by weight of NMP,22% by weight of sodium chloride, 0.8% by weight of excess hydrochloric acid, 44.2% by weight of H 2 O,3.0% by weight benzoic acid;
(2) Inputting the acidified mixed solution in the step (1) into a 200L 316L stainless steel jacketed evaporation kettle, inputting heat-conducting oil from the bottom of a jacket of the 316L stainless steel jacketed evaporation kettle, outputting the heat-conducting oil from the top of the jacket, and carrying out treatment on the heat-conducting oil containing NMP and H 2 Heating the mixed liquid of O, benzoic acid and sodium chloride, stirring the mixed liquid at a stirring speed of 80rpm, starting a vacuum pump when the temperature reaches 90 ℃, enabling water vapor to flow out of the top of a 316L stainless steel jacket evaporation kettle, cooling the mixed liquid by a condenser arranged at the top, flowing into a wastewater treatment process, recycling the treated mixed liquid, inputting the rest of the mixed liquid into a solid-liquid separation centrifuge for separation when the solution in the 316L stainless steel jacket evaporation kettle is brownish and crystals are crystallized and precipitated, measuring the viscosity of the mixed liquid to be 2.0cPa.s by an on-line viscometer, and detecting the water content in the mixed liquid to be 0.9 wt by liquid chromatography, wherein the solid is light green sodium chloride containing a small amount of NMP and organic impurities, and inputting the mixed liquid into a sodium chloride recovery and drying device; inputting the filtrate into an NMP solvent recovery rectifying tower;
(3) Inputting the light green sodium chloride solid containing a small amount of NMP and organic impurities separated in the step (2) into a spiral dryer, respectively configuring a phi 60 steam outlet at the front part, the middle part and the tail part of the spiral dryer, connecting the outlet with the lower opening of a condenser tube side, connecting the upper outlet of the condenser tube side with the inlet of a vacuum pump, cooling the steam containing NMP evaporated from the spiral dryer by a condenser, and inputting the steam containing NMP and H 2 Acidifying and concentrating the mixed liquid of O, sodium benzoate and sodium chloride, then rectifying the mixed liquid in a rectifying tower, inputting cooling water from the lower opening of the shell pass of the condenser, and outputting the cooling water from the upper opening of the shell pass of the condenser to a circulating water storage tank for recycling;
(4) Separating the liquid mixture containing NMP obtained in the step (2), inputting the liquid mixture from the middle part of a rectifying tower at an input speed of 8L/min, assembling a 20L glass jacket evaporator at the lower part of the rectifying tower, assembling a magnetic stirrer below the glass jacket evaporator, stirring the liquid mixture containing the NMP solvent which is not evaporated at a stirring speed of 60rpm, inputting heat conduction oil from the bottom of a glass jacket expander, outputting the heat conduction oil from the top of the glass jacket evaporator, inputting the evaporated NMP steam into a condenser arranged at the top of the rectifying tower, inputting the NMP steam from a tube pass bottom inlet of the condenser, connecting a top outlet of the condenser with an inlet of a vacuum pump, cooling the NMP steam by the condenser, flowing out from the lower end of a tube pass of the condenser, detecting the NMP content of 99.98 wt% by a liquid chromatograph, and inputting the cooled NMP steam into an NMP storage tank, wherein the recovery rate of the NMP solvent in the experiment is 97.47%.
Comparative example 1
(1) 100L of NMP 15% by weight, 1.5% by weight of sodium benzoate, 10% by weight of sodium chloride, 73.5% by weight of wtH, with a stirring speed of 10rpm 2 The mixed liquid of O is input into a 316L stainless steel jacket evaporation kettle, the pH value of the mixed liquid is measured to be 9.3 by an on-line acidimeter, the heat-conducting oil is input from the bottom of the jacket of the 316L stainless steel jacket evaporation kettle, and is output from the top of the jacket, and the mixed liquid containing NMP and H is subjected to heat treatment 2 Heating a mixed liquid of O, sodium benzoate and sodium chloride, stirring the mixed liquid at a stirring speed of 30rpm, starting a vacuum pump when the temperature reaches 60 ℃, enabling water vapor to flow out of the top of a 316L stainless steel jacket evaporation kettle, cooling the mixed liquid by a condenser arranged at the top, flowing into a wastewater treatment process, treating the wastewater for recycling, inputting the rest mixed liquid into a solid-liquid separation centrifuge for separation when the solution in the 316L stainless steel jacket evaporation kettle is changed into tan and crystals are crystallized and precipitated, measuring the viscosity of the mixed liquid to be 33.1cPa.s by an online viscometer, and detecting the water content in the mixed liquid to reach 0.5 percent by weight by liquid chromatography, and inputting the rest mixed liquid into a recovery and drying device of sodium chloride, wherein the solid is light green sodium chloride containing a small amount of NMP and organic impurities; inputting the filtrate into an NMP solvent recovery rectifying tower;
(2) Inputting the light green sodium chloride solid containing a small amount of NMP and organic impurities separated in the step (1) into a spiral dryer, and respectively configuring a phi 60 solid at the front part, the middle part and the tail part of the spiral dryerThe outlet of the steam outlet is connected with the lower opening of the tube pass of the condenser, the upper outlet of the tube pass of the condenser is connected with the inlet of the vacuum pump, and the steam containing NMP evaporated from the spiral dryer is cooled by the condenser and then is input into the condenser to contain NMP and H 2 Acidifying and concentrating the mixed liquid of O, sodium benzoate and sodium chloride, then rectifying the mixed liquid in a rectifying tower, inputting cooling water from the lower opening of the shell pass of the condenser, and outputting the cooling water from the upper opening of the shell pass of the condenser to a circulating water storage tank for recycling;
(3) Separating the liquid mixture containing NMP from the step (1), inputting the liquid mixture from the middle part of a rectifying tower at an input speed of 2L/min, assembling a 20L glass jacket evaporator at the lower part of the rectifying tower, assembling a magnetic stirrer below the glass jacket evaporator, stirring the liquid mixture containing the NMP solvent which is not evaporated at a stirring speed of 30rpm, inputting heat conducting oil from the bottom of a glass jacket expander, outputting the heat conducting oil from the top of the glass jacket evaporator, inputting the evaporated NMP steam into a condenser arranged at the top of the rectifying tower, inputting the evaporated NMP steam from a tube pass bottom inlet of the condenser, connecting a top outlet of the condenser with an inlet of a vacuum pump, cooling the NMP steam by the condenser, flowing out from the lower end of a tube pass of the condenser, detecting the NMP content of 99.16 wt by a liquid chromatograph, returning the unqualified NMP steam to a crude NMP tank for temporary storage, and ensuring that the recovery rate of the NMP solvent in the experiment is 95.73%.
Example 3
(1) 20% wt of NMP,2.0% wt of sodium formate, 17.3% wt of sodium chloride, 60.7% wt of WtH, to 100L under the condition of stirring speed of 10-50 rpm 2 Adding 26L of 3.6% v/v hydrochloric acid solution into the mixed liquid of O, and feeding into a 316L stainless steel jacketed evaporation kettle when the pH value of the mixed liquid is 0.35 measured by an on-line acidimeter; at this time, the mixed liquid contained 18.6% by weight of NMP,15.61% by weight of sodium chloride, 0.4% by weight of excess hydrochloric acid, 63.76% by weight of H 2 O,1.63% by weight of formic acid;
(2) Inputting the acidified mixed solution in the step (1) into a 200L 316L stainless steel jacketed evaporation kettle, inputting heat-conducting oil from the bottom of a jacket of the 316L stainless steel jacketed evaporation kettle, outputting the heat-conducting oil from the top of the jacket, and carrying out treatment on the heat-conducting oil containing NMP and H 2 Heating the mixed liquid of O, formic acid and sodium chlorideStirring the mixed liquid at a stirring speed of 43rpm, starting a vacuum pump when the temperature reaches 71 ℃, enabling water vapor to flow out of the top of a 316L stainless steel jacket evaporation kettle, cooling the mixed liquid by a condenser arranged at the top, flowing into a wastewater treatment process, treating the wastewater for recycling, when the solution in the 316L stainless steel jacket evaporation kettle is changed into brown and crystals are separated out, measuring the viscosity of the mixed liquid to be 3.1cPa.s by an online viscometer, and measuring the water content in the mixed liquid to be 0.7 wt by liquid chromatography, inputting the rest of the mixed liquid into a solid-liquid separation centrifuge for separation, wherein the solid is light green sodium chloride containing a small amount of NMP and organic impurities, and inputting the light green sodium chloride into a sodium chloride recovery and drying device; inputting the filtrate into an NMP solvent recovery rectifying tower;
(3) Inputting the light green sodium chloride solid containing a small amount of NMP and organic impurities separated in the step (2) into a spiral dryer, respectively configuring a phi 60 steam outlet at the front part, the middle part and the tail part of the spiral dryer, connecting the outlet with the lower opening of a condenser tube side, connecting the upper outlet of the condenser tube side with the inlet of a vacuum pump, cooling the steam containing NMP evaporated from the spiral dryer by a condenser, and inputting the steam containing NMP and H 2 Acidifying and concentrating the mixed liquid of O, sodium formate and sodium chloride, then rectifying the mixed liquid in a rectifying tower, inputting cooling water from the lower opening of the shell pass of a condenser, and outputting the cooling water from the upper opening of the shell pass of the condenser to a circulating water storage tank for recycling;
(4) Separating the liquid mixture containing NMP from the step (2), inputting the liquid mixture from the middle part of a rectifying tower at an input speed of 4.3L/min, arranging a 20L glass jacket evaporator at the lower part of the rectifying tower, arranging a magnetic stirrer below the glass jacket evaporator, stirring the liquid mixture containing the NMP solvent which is not evaporated at a stirring speed of 41rpm, inputting heat conducting oil from the bottom of a glass jacket expander, outputting the heat conducting oil from the top of the glass jacket evaporator, inputting the evaporated NMP steam into a condenser arranged at the top of the rectifying tower, inputting the evaporated NMP steam from a tube pass bottom inlet of the condenser, connecting a top outlet of the condenser with an inlet of a vacuum pump, cooling the NMP steam by the condenser, flowing out from the lower end of a tube pass of the condenser, detecting the NMP content to be 99.97 wt by a liquid chromatograph, and inputting the cooled NMP steam into an NMP storage tank, wherein the solvent recovery rate of the experiment is 97.82%.
Example 4
(1) 25.6% wt of NMP,2.1% wt of sodium acetate, 21.4% wt of sodium chloride, 36.5-71.5% wt of sodium chloride to 100L at a stirring speed of 10-50 rpm 2 O, adding 29L of hydrochloric acid solution with a concentration of 4.6% v/v, and when the pH of the mixed solution measured by an on-line acidimeter is 1.3, feeding into a 316L stainless jacketed evaporation kettle; at this time, the mixed liquid contained 21.4% by weight of NMP,20.34% by weight of sodium chloride, 0.6% by weight of excess hydrochloric acid, 55.9% by weight of H 2 O,1.76% by weight of acetic acid;
(2) Inputting the acidified mixed solution in the step (1) into a 200L 316L stainless steel jacket evaporation kettle, inputting heat-conducting oil from the bottom of the jacket of the 316L stainless steel jacket evaporation kettle, outputting the heat-conducting oil from the top of the jacket, and carrying out heat treatment on the heat-conducting oil containing NMP and H 2 Heating the mixed liquid of O, acetic acid and sodium chloride, stirring the mixed liquid at a stirring speed of 56rpm, starting a vacuum pump when the temperature reaches 73.6 ℃, enabling water vapor to flow out of the top of a 316L stainless steel jacket evaporation kettle, cooling the mixed liquid by a condenser arranged at the top, flowing into a wastewater treatment process, recycling the wastewater after treatment, inputting the rest mixed liquid into a solid-liquid separation centrifuge for separation when the solution in the 316L stainless steel jacket evaporation kettle is changed into brown and crystals are crystallized, measuring the viscosity of the mixed liquid to be 4.3cPa.s by an online viscometer, and measuring the water content in the mixed liquid to be 0.7 wt by liquid chromatography, and inputting the rest mixed liquid into a recovery and drying device of sodium chloride, wherein the solid is light green sodium chloride containing a small amount of NMP and organic impurities; inputting the filtrate into an NMP solvent recovery rectifying tower;
(3) Inputting the light green sodium chloride solid containing a small amount of NMP and organic impurities separated in the step (2) into a spiral dryer, respectively configuring a phi 60 steam outlet at the front part, the middle part and the tail part of the spiral dryer, connecting the outlet with the lower opening of a condenser tube side, connecting the upper outlet of the condenser tube side with the inlet of a vacuum pump, cooling the steam containing NMP evaporated from the spiral dryer by a condenser, and inputting the steam containing NMP and H 2 Mixing O, sodium acetate and sodium chloride, acidifying, concentrating, and infusingThe cooling water is input from the lower opening of the shell pass of the condenser and is output to a circulating water storage tank from the upper opening of the shell pass of the condenser for recycling;
(4) Separating the liquid mixture containing NMP from the step (2), inputting the liquid mixture from the middle part of a rectifying tower at an input speed of 5L/min, arranging a 20L glass jacket evaporator at the lower part of the rectifying tower, arranging a magnetic stirrer below the glass jacket evaporator, stirring the liquid mixture containing the NMP solvent which is not evaporated at a stirring speed of 44rpm, inputting heat conducting oil from the bottom of a glass jacket expander, outputting the heat conducting oil from the top of the glass jacket evaporator, inputting the evaporated NMP steam into a condenser arranged at the top of the rectifying tower, inputting the evaporated NMP steam from a tube pass bottom inlet of the condenser, connecting a top outlet of the condenser with an inlet of a vacuum pump, cooling the NMP steam by the condenser, flowing out from the lower end of a tube pass of the condenser, detecting the NMP content to be 99.98 wt by a liquid chromatograph, and inputting the cooled NMP steam into a storage tank, wherein the recovery rate of the NMP solvent in the experiment is 97.61%.
Comparative example 2
(1) Under the condition of a stirring speed of 50rpm, 100L of 35% wt of NMP,3.5% wt of sodium formate, 25% wt of sodium chloride, 36.5% wt 2 The mixed liquid of O is input into a 316L stainless steel jacket evaporation kettle; the pH value of the mixed liquid measured by an on-line acidimeter is 9.9, the heat-conducting oil is input from the bottom of a jacket of a 316L stainless steel jacket evaporation kettle and output from the top of the jacket, and the mixed liquid containing NMP and H is subjected to reaction 2 Heating the mixed liquid of O, sodium formate and sodium chloride, stirring the mixed liquid at a stirring speed of 80rpm, starting a vacuum pump when the temperature reaches 90 ℃, enabling water vapor to flow out of the top of a 316L stainless steel jacket evaporation kettle, cooling the mixed liquid by a condenser arranged at the top, flowing into a wastewater treatment process, treating the wastewater for recycling, inputting the rest mixed liquid into a solid-liquid separation centrifuge for separation when the solution in the 316L stainless steel jacket evaporation kettle is brown and crystals are crystallized, measuring the viscosity of the mixed liquid to be 13.9cPa.s by an online viscometer, and detecting the water content in the mixed liquid to be 0.9 wt by liquid chromatography, and inputting the rest mixed liquid into a recovery and drying device of sodium chloride, wherein the solid is light green sodium chloride containing a small amount of NMP and organic impurities; filtrateInputting the mixture into an NMP solvent recovery rectifying tower;
(2) Inputting the light green sodium chloride solid containing a small amount of NMP and organic impurities separated in the step (1) into a spiral dryer, respectively configuring a steam outlet with phi 60 at the front part, the middle part and the tail part of the spiral dryer, connecting the outlet with the lower opening of a condenser tube pass, connecting the upper outlet of the condenser tube pass with the inlet of a vacuum pump, cooling the steam containing NMP evaporated from the spiral dryer by a condenser, and inputting the steam containing NMP and H 2 Acidifying and concentrating the mixed liquid of O, sodium formate and sodium chloride, then rectifying the mixed liquid in a rectifying tower, inputting cooling water from the lower opening of the shell pass of a condenser, and outputting the cooling water from the upper opening of the shell pass of the condenser to a circulating water storage tank for recycling;
(3) Separating the liquid mixture containing NMP from the step (1), inputting the liquid mixture from the middle part of a rectifying tower at an input speed of 8L/min, assembling a 20L glass jacket evaporator at the lower part of the rectifying tower, assembling a magnetic stirrer below the glass jacket evaporator, stirring the liquid mixture containing the NMP solvent which is not evaporated at a stirring speed of 60rpm, inputting heat transfer oil from the bottom of a glass jacket expander, outputting the heat transfer oil from the top of the glass jacket evaporator, inputting the evaporated NMP steam into a condenser arranged at the top of the rectifying tower, inputting the evaporated NMP steam from a tube pass bottom inlet of the condenser, connecting a top outlet of the condenser with an inlet of a vacuum pump, cooling the NMP steam by the condenser, flowing out from the lower end of a tube pass of the condenser, detecting the NMP content of 99.13 wt by a liquid chromatograph, returning the unqualified NMP steam to a crude NMP tank for temporary storage, and ensuring that the recovery rate of the NMP solvent in the experiment is 96.72%.
Example 5
(1) 30.1% wt of NMP,2.7% wt of sodium propionate, 23.1% wt of sodium chloride, 47.1% wt of WtH to 100L at a stirring speed of 43rpm 2 Adding 18L of 8%v/v ammonium chloride solution into the O mixed liquid, and inputting the mixed liquid into a 316L stainless steel jacket evaporation kettle when the pH value of the mixed liquid is 1.5 measured by an on-line acidimeter; at this time, the mixed liquid contained 28.3% wt of NMP,24.3% wt of sodium chloride, 0.5% wt of excess ammonium chloride, 44.7% wt of H 2 O,2.2% by weight ammonium propionate;
(2) Inputting the acidified mixed solution in the step (1) into a 200L 316L stainless steel jacketed evaporation kettle, inputting heat-conducting oil from the bottom of a jacket of the 316L stainless steel jacketed evaporation kettle, outputting the heat-conducting oil from the top of the jacket, and carrying out treatment on the heat-conducting oil containing NMP and H 2 Heating a mixed liquid of O, ammonium propionate and sodium chloride, stirring the mixed liquid at a stirring speed of 57rpm, starting a vacuum pump when the temperature reaches 80.3 ℃, enabling water vapor to flow out of the top of a 316L stainless steel jacket evaporation kettle, cooling the mixed liquid by a condenser arranged at the top, flowing into a wastewater treatment process, recycling the treated mixed liquid, inputting the residual mixed liquid into a solid-liquid separation centrifuge for separation when the solution in the 316L stainless steel jacket evaporation kettle is brownish and crystals are crystallized and precipitated, measuring the viscosity of the mixed liquid to be 2.3cPa.s by an on-line viscometer, and detecting the water content in the mixed liquid to be 0.5 wt by liquid chromatography, and inputting the solid to a sodium chloride recovery and drying device; inputting the filtrate into an NMP solvent recovery rectifying tower;
(3) Inputting the light green sodium chloride solid containing a small amount of NMP and organic impurities separated in the step (2) into a spiral dryer, respectively configuring a phi 60 steam outlet at the front part, the middle part and the tail part of the spiral dryer, connecting the outlet with the lower opening of a condenser tube side, connecting the upper outlet of the condenser tube side with the inlet of a vacuum pump, cooling the steam containing NMP evaporated from the spiral dryer by a condenser, and inputting the steam containing NMP and H 2 After acidification and concentration, the mixed liquid of O, sodium propionate and sodium chloride is rectified in a rectifying tower, cooling water is input from the lower opening of the shell pass of the condenser and is output to a circulating water storage tank from the upper opening of the shell pass of the condenser for recycling;
(4) Separating the liquid mixture containing NMP from the step (2), inputting the liquid mixture from the middle part of the rectifying tower at an input speed of 7L/min, arranging a 20L glass jacket evaporator at the lower part of the rectifying tower, arranging a magnetic stirrer below the glass jacket evaporator, stirring the liquid mixture containing the NMP solvent which is not evaporated at a stirring speed of 39rpm, inputting heat transfer oil from the bottom of the glass jacket evaporator, outputting the heat transfer oil from the top of the glass jacket evaporator, inputting the evaporated NMP steam into a condenser arranged at the top of the rectifying tower, inputting the evaporated NMP steam from a tube pass bottom inlet of the condenser, connecting a top outlet of the condenser with an inlet of a vacuum pump, cooling the NMP steam by the condenser, flowing out from the lower end of a tube pass of the condenser, detecting the NMP content of 99.97 wt by a liquid chromatograph, and inputting the cooled NMP steam into a storage tank, wherein the NMP solvent recovery rate of the experiment is 97.74%.
Example 6
(1) 28.6% wt of NMP,2.3% wt of sodium butyrate, 19.6% wt of sodium chloride, 59.5% wt of NMP to 100L at a stirring rate of 43rpm 2 Adding 30L of 6%v/v ammonium chloride solution into the O mixed liquid, and inputting the mixed liquid into a 316L stainless steel jacket evaporation kettle when the pH value of the mixed liquid is 0.8 measured by an on-line acidimeter; at this time, the mixed liquid contained 26.5% wt of NMP, 23.9% wt of sodium chloride, 0.7% wt of excess ammonium chloride, 46.93% wt of H 2 O,1.97% by weight ammonium butyrate;
(2) Inputting the acidified mixed solution in the step (1) into a 200L 316L stainless steel jacket evaporation kettle, inputting heat-conducting oil from the bottom of the jacket of the 316L stainless steel jacket evaporation kettle, outputting the heat-conducting oil from the top of the jacket, and carrying out heat treatment on the heat-conducting oil containing NMP and H 2 Heating the mixed liquid of O, butyric acid and sodium chloride, stirring the mixed liquid at a stirring speed of 73rpm, starting a vacuum pump when the temperature reaches 73.4 ℃, enabling water vapor to flow out of the top of a 316L stainless steel jacket evaporation kettle, cooling the mixed liquid by a condenser arranged at the top, flowing into a wastewater treatment process, recycling the wastewater after treatment, inputting the rest mixed liquid into a solid-liquid separation centrifuge for separation when the solution in the 316L stainless steel jacket evaporation kettle is changed into tan and crystal is crystallized, measuring the viscosity of the mixed liquid to be 5.1cPa.s by an on-line viscometer, and measuring the water content in the mixed liquid to be 0.7 wt by liquid chromatography, and inputting the rest mixed liquid into a recovery and drying device of sodium chloride, wherein the solid is light green sodium chloride containing a small amount of NMP and organic impurities; inputting the filtrate into an NMP solvent recovery rectifying tower;
(3) Inputting the light green sodium chloride solid containing a small amount of NMP and organic impurities separated in the step (2) into a spiral dryer, and respectively configuring a steam outlet with phi 60 at the front part, the middle part and the tail part of the spiral dryer, wherein the steam outlet is connected with a condenser tube passThe lower port is connected, the upper outlet of the condenser tube pass is connected with the inlet of a vacuum pump, and the vapor containing NMP evaporated from the spiral dryer is cooled by the condenser and then is input with NMP and H 2 After acidification and concentration, the mixed liquid of O, sodium butyrate and sodium chloride is input into a rectifying tower for rectification, cooling water is input from the lower opening of the shell pass of a condenser and is output from the upper opening of the shell pass of the condenser to a circulating water storage tank for recycling;
(4) Separating the liquid mixture containing NMP from the step (2), inputting the liquid mixture from the middle part of a rectifying tower at an input speed of 5L/min, assembling a 20L glass jacket evaporator at the lower part of the rectifying tower, assembling a magnetic stirrer below the glass jacket evaporator, stirring the liquid mixture containing the NMP solvent which is not evaporated at a stirring speed of 36rpm, inputting heat transfer oil from the bottom of the glass jacket evaporator, outputting the heat transfer oil from the top of the glass jacket evaporator, inputting the evaporated NMP steam into a condenser arranged at the top of the rectifying tower, inputting the evaporated NMP steam from a tube pass bottom inlet of the condenser, connecting a top outlet of the condenser with an inlet of a vacuum pump, cooling the NMP steam by the condenser, flowing out from the lower end of a tube pass of the condenser, detecting the NMP content of 99.96 wt% by a liquid chromatograph, and inputting the cooled NMP steam into a storage tank, wherein the recovery rate of the NMP solvent in the experiment is 97.71%.
Comparative example 3
(1) 15% wt of NMP,1.5% wt of sodium formate, 10% wt of sodium chloride, 73.5% wt of sodium chloride to 100L at a stirring speed of 10rpm 2 Adding 36L of 8%v/v ammonium chloride solution into the O mixed liquid, measuring the pH value of the mixed liquid to be-0.3 by using an on-line acidimeter, and inputting the mixed liquid into a 316L stainless steel jacket evaporation kettle; at this time, the mixed liquid contained 12.7% wt of NMP,10.7% wt of sodium chloride, 0.8% wt of excess ammonium chloride, 74.47% wt of H 2 O,1.33% wt. ammonium formate;
(2) Inputting the acidified mixed solution in the step (1) into a 200L 316L stainless steel jacketed evaporation kettle, inputting heat-conducting oil from the bottom of a jacket of the 316L stainless steel jacketed evaporation kettle, outputting the heat-conducting oil from the top of the jacket, and carrying out treatment on the heat-conducting oil containing NMP and H 2 Heating the mixed liquid of O, ammonium formate and sodium chloride, stirring the mixed liquid at a stirring speed of 30rpm, and when the temperature reaches 60 DEG CStarting a vacuum pump, enabling water vapor to flow out of the top of a 316L stainless steel jacket evaporation kettle, cooling the water vapor by a condenser arranged at the top, flowing into a wastewater treatment process, and recycling the wastewater after treatment, wherein when the solution in the 316L stainless steel jacket evaporation kettle is changed into brown and crystals are separated out, the viscosity of the mixed liquid is 7.3cPa.s measured by an online viscometer, and when the water content in the mixed liquid is detected to reach 0.5 wt% by liquid chromatography, the rest mixed liquid is input into a solid-liquid separation centrifuge for separation, the solid is light green sodium chloride containing a small amount of NMP and organic impurities, and the input sodium chloride is input into a recovery and drying device; inputting the filtrate into an NMP solvent recovery rectifying tower;
(3) Inputting the light green sodium chloride solid containing a small amount of NMP and organic impurities separated in the step (2) into a spiral dryer, respectively configuring a phi 60 steam outlet at the front part, the middle part and the tail part of the spiral dryer, connecting the outlet with the lower opening of a condenser tube side, connecting the upper outlet of the condenser tube side with the inlet of a vacuum pump, cooling the steam containing NMP evaporated from the spiral dryer by a condenser, and inputting the steam containing NMP and H 2 Acidifying and concentrating the mixed liquid of O, sodium formate and sodium chloride, then rectifying the mixed liquid in a rectifying tower, inputting cooling water from the lower opening of the shell pass of a condenser, and outputting the cooling water from the upper opening of the shell pass of the condenser to a circulating water storage tank for recycling;
(4) And (3) separating the mixed liquid containing NMP from the step (2), inputting the mixed liquid from the middle part of the rectifying tower at an input speed of 2L/min, assembling a 20L glass jacket evaporator at the lower part of the rectifying tower, assembling a magnetic stirrer below the glass jacket evaporator, stirring the mixed liquid containing the NMP solvent which is not evaporated at a stirring speed of 30rpm, inputting heat conduction oil from the bottom of the glass jacket evaporator, outputting the heat conduction oil from the top of the glass jacket evaporator, inputting the evaporated NMP steam into a condenser arranged at the top of the rectifying tower, inputting the evaporated NMP steam from a tube pass bottom inlet of the condenser, connecting a top outlet of the condenser with an inlet of a vacuum pump, cooling the NMP steam by the condenser, flowing out from the lower end of a tube pass of the condenser, detecting the NMP content of 98.98 wt by a liquid chromatograph, returning the unqualified NMP steam to a crude NMP tank for temporary storage, detecting the evaporated mixed liquid after acidification, and detecting that an open-ring compound exists.
Example 7
(1) 22% wt of NMP,3.3% wt of sodium acetate, 23.7% wt of sodium chloride, 51% wt H to 100L at a stirring speed of 23rpm 2 Adding 29L of 7%v/v ammonium chloride solution into the O mixed liquid, and inputting the mixed liquid into a 316L stainless steel jacket evaporation kettle when the pH value of the mixed liquid is 3.6 measured by an on-line acidimeter; at this time the mixed liquid contains 19.2% wt of NMP,20.3% wt of sodium chloride, 0.3% wt of excess ammonium chloride, 57.2% wt of H 2 O, 3.0%;
(2) Inputting the acidified mixed solution in the step (1) into a 200L 316L stainless steel jacketed evaporation kettle, inputting heat-conducting oil from the bottom of a jacket of the 316L stainless steel jacketed evaporation kettle, outputting the heat-conducting oil from the top of the jacket, and carrying out treatment on the heat-conducting oil containing NMP and H 2 Heating a mixed liquid of O, ammonium acetate and sodium chloride, stirring the mixed liquid at a stirring speed of 61rpm, starting a vacuum pump when the temperature reaches 83.8 ℃, enabling water vapor to flow out of the top of a 316L stainless steel jacket evaporation kettle, cooling the mixed liquid by a condenser arranged at the top, flowing into a wastewater treatment process, recycling the wastewater after treatment, inputting the rest mixed liquid into a solid-liquid separation centrifuge for separation when the solution in the 316L stainless steel jacket evaporation kettle is changed into brown and crystals are crystallized, measuring the viscosity of the mixed liquid to be 3.31cPa.s by an online viscometer, and measuring the water content in the mixed liquid to be 0.6 wt by a liquid chromatography, and inputting the rest mixed liquid into a sodium chloride recovery and drying device, wherein the solid is light green sodium chloride containing a small amount of NMP and organic impurities; inputting the filtrate into an NMP solvent recovery rectifying tower;
(3) Inputting the light green sodium chloride solid containing a small amount of NMP and organic impurities separated in the step (2) into a spiral dryer, respectively configuring a phi 60 steam outlet at the front part, the middle part and the tail part of the spiral dryer, connecting the outlet with the lower opening of a condenser tube side, connecting the upper outlet of the condenser tube side with the inlet of a vacuum pump, cooling the steam containing NMP evaporated from the spiral dryer by a condenser, and inputting the steam containing NMP and H 2 In the mixed liquid of O, sodium acetate and sodium chloride, thenAfter acidification and concentration, the mixture is input into a rectifying tower for rectification, cooling water is input from the lower opening of the shell pass of the condenser and is output from the upper opening of the shell pass of the condenser to a circulating water storage tank for recycling;
(4) Separating the liquid mixture containing NMP obtained in the step (2), inputting the liquid mixture from the middle part of a rectifying tower at an input speed of 3.7L/min, assembling a 20L glass jacket evaporator at the lower part of the rectifying tower, assembling a magnetic stirrer below the glass jacket evaporator, stirring the liquid mixture containing the NMP solvent which is not evaporated at a stirring speed of 48rpm, inputting heat conduction oil from the bottom of a glass jacket expander, outputting the heat conduction oil from the top of the glass jacket evaporator, inputting the evaporated NMP steam into a condenser arranged at the top of the rectifying tower, inputting the evaporated NMP steam from a tube pass bottom inlet of the condenser, connecting an inlet of a vacuum pump at the top of the condenser with an NMP steam outlet, cooling the NMP steam by the condenser, flowing out from the lower end of a tube pass of the condenser, detecting the NMP content of 99.96wt by a liquid chromatograph, and inputting the cooled NMP steam into a storage tank, wherein the recovery rate of the NMP solvent in the experiment is 97.95%.
Example 8
(1) By mixing at 47rpm, 30.3% wt of NMP to 100L, 2.6% wt of sodium benzoate, 14.6% wt of sodium chloride, 52.5% 2 Adding 30L of 3v/v ammonium chloride solution into the mixed liquid of O, and inputting the mixed liquid into a 316L stainless steel jacket evaporation kettle when the pH value of the mixed liquid is 3.4 measured by an on-line acidimeter; at this time, the mixed liquid contained 25.7% wt of NMP,18.7% wt of sodium chloride, 0.4% wt of excess ammonium chloride, 54.2% wt of H 2 O,1.0% by weight of ammonium benzoate;
(2) Inputting the acidified mixed solution in the step (1) into a 200L 316L stainless steel jacketed evaporation kettle, inputting heat-conducting oil from the bottom of a jacket of the 316L stainless steel jacketed evaporation kettle, outputting the heat-conducting oil from the top of the jacket, and carrying out treatment on the heat-conducting oil containing NMP and H 2 Heating the mixed liquid of O, ammonium benzoate, acetic acid and sodium chloride, stirring the mixed liquid at a stirring speed of 57rpm, starting a vacuum pump when the temperature reaches 86.4 ℃, allowing water vapor to flow out of the top of a 316L stainless steel jacket evaporation kettle, cooling by a condenser arranged at the top, allowing the water vapor to flow into a wastewater treatment process, and recycling the treated water, wherein when the mixed liquid in the 316L stainless steel jacket evaporation kettle is heatedWhen the solution (2) was brownish and crystals were crystallized, the viscosity of the mixed solution was 4.7cPa.s as measured by an in-line viscometer, and when the water content in the mixed solution reached 0.8% by weight as measured by liquid chromatography, the remaining mixed solution was fed to a solid-liquid separation centrifuge for separation, the solid was light green sodium chloride containing a small amount of NMP and organic impurities, and the sodium chloride was fed to a recovery drying apparatus; inputting the filtrate into an NMP solvent recovery rectifying tower;
(3) Inputting the light green sodium chloride solid containing a small amount of NMP and organic impurities separated in the step (2) into a spiral dryer, respectively configuring a phi 60 steam outlet at the front part, the middle part and the tail part of the spiral dryer, connecting the outlet with the lower opening of a condenser tube side, connecting the upper outlet of the condenser tube side with the inlet of a vacuum pump, cooling the steam containing NMP evaporated from the spiral dryer by a condenser, and inputting the steam containing NMP and H 2 Acidifying and concentrating the mixed liquid of O, sodium benzoate and sodium chloride, then rectifying the mixed liquid in a rectifying tower, inputting cooling water from the lower opening of the shell pass of the condenser, and outputting the cooling water from the upper opening of the shell pass of the condenser to a circulating water storage tank for recycling;
(4) Separating the liquid mixture containing NMP from the step (2), inputting the liquid mixture from the middle part of a rectifying tower at an input speed of 7.1L/min, arranging a 20L glass jacket evaporator at the lower part of the rectifying tower, arranging a magnetic stirrer below the glass jacket evaporator, stirring the liquid mixture containing the NMP solvent which is not evaporated at a stirring speed of 52rpm, inputting heat conducting oil from the bottom of a glass jacket expander, outputting the heat conducting oil from the top of the glass jacket evaporator, inputting the evaporated NMP steam into a condenser arranged at the top of the rectifying tower, inputting the evaporated NMP steam from a tube pass bottom inlet of the condenser, connecting an inlet of a vacuum pump to a top outlet of the condenser, cooling the NMP steam by the condenser, flowing out from the lower end of a tube pass of the condenser, detecting the NMP content to be 99.97 wt by a liquid chromatograph, and inputting the cooled NMP steam into an NMP storage tank, wherein the NMP recovery rate of the solvent in the experiment is 8978 zft 8978%.
Example 9
(1) 30.1% wt of NMP,2.7% wt of sodium propionate, 23.1% wt of sodium chloride, 47.1% wt to 100L at a stirring speed of 43rpmtH 2 Adding 18L of a 8%v/v hydrochloric acid solution into the O mixed liquid, and inputting the mixed liquid into a 316L stainless steel jacket evaporation kettle when the pH value of the mixed liquid is 1.5 measured by an on-line acidimeter; at this time, the mixed liquid contained 28.3% wt of NMP,24.3% wt of sodium chloride, 0.5% wt of excess hydrochloric acid, 44.7% wt of H 2 O,2.2% by weight propionic acid;
(2) Inputting the acidified mixed solution in the step (1) into a 200L 316L stainless steel jacketed evaporation kettle, inputting heat-conducting oil from the bottom of a jacket of the 316L stainless steel jacketed evaporation kettle, outputting the heat-conducting oil from the top of the jacket, and carrying out treatment on the heat-conducting oil containing NMP and H 2 Heating the mixed liquid of O, propionic acid and sodium chloride, stirring the mixed liquid at a stirring speed of 57rpm, starting a vacuum pump when the temperature reaches 80.3 ℃, enabling water vapor to flow out of the top of a 316L stainless steel jacket evaporation kettle, cooling the mixed liquid by a condenser arranged at the top, flowing into a wastewater treatment process, recycling the wastewater after treatment, inputting the rest mixed liquid into a solid-liquid separation centrifuge for separation when the solution in the 316L stainless steel jacket evaporation kettle is changed into brown and crystals are crystallized, measuring the viscosity of the mixed liquid to be 2.3cPa.s by an online viscometer, and measuring the water content in the mixed liquid to be 0.5 wt by liquid chromatography, and inputting the rest mixed liquid into a recovery and drying device of sodium chloride, wherein the solid is light green sodium chloride containing a small amount of NMP and organic impurities; inputting the filtrate into an NMP solvent recovery rectifying tower;
(3) Inputting the light green sodium chloride solid containing a small amount of NMP and organic impurities separated in the step (2) into a spiral dryer, respectively configuring a phi 60 steam outlet at the front part, the middle part and the tail part of the spiral dryer, connecting the outlet with the lower opening of a condenser tube side, connecting the upper outlet of the condenser tube side with the inlet of a vacuum pump, cooling the steam containing NMP evaporated from the spiral dryer by a condenser, and inputting the steam containing NMP and H 2 After acidification and concentration, the mixed liquid of O, sodium propionate and sodium chloride is rectified in a rectifying tower, cooling water is input from the lower opening of the shell pass of the condenser and is output to a circulating water storage tank from the upper opening of the shell pass of the condenser for recycling;
(4) Separating the liquid mixture containing NMP from the step (2), inputting the liquid mixture from the middle part of the rectifying tower at an input speed of 7L/min, arranging a 20L glass jacket evaporator at the lower part of the rectifying tower, arranging a magnetic stirrer below the glass jacket evaporator, stirring the liquid mixture containing the NMP solvent which is not evaporated at a stirring speed of 39rpm, inputting heat transfer oil from the bottom of the glass jacket evaporator, outputting the heat transfer oil from the top of the glass jacket evaporator, inputting the evaporated NMP steam into a condenser arranged at the top of the rectifying tower, inputting the evaporated NMP steam from a tube pass bottom inlet of the condenser, connecting a top outlet of the condenser with an inlet of a vacuum pump, cooling the NMP steam by the condenser, flowing out from the lower end of a tube pass of the condenser, detecting the NMP content of 99.98 wt by a liquid chromatograph, and inputting the cooled NMP steam into a storage tank, wherein the NMP solvent recovery rate of the experiment is 97.73%.
Comparative example 4
(1) By adding 30.1% wt of NMP,2.5% wt of sodium butyrate, 18.6% wt of sodium chloride, 48.9% wt of WtH to 100L with a stirring speed of 43rpm 2 Adding 13L of hydrochloric acid solution with a concentration of 13% v/v into the mixed liquid of O, and introducing into a 316L stainless steel jacketed evaporation kettle when the pH of the mixed liquid is-0.1 measured by an on-line acidimeter; at this time, the mixed liquid contained 28.4% wt of NMP,2.1% wt of butyric acid, 20.6% wt of sodium chloride, 0.5% wt of excessive hydrochloric acid, 48.4% wt of H 2 O；
(2) Inputting the acidified mixed solution in the step (1) into a 200L 316L stainless steel jacket evaporation kettle, inputting heat-conducting oil from the bottom of the jacket of the 316L stainless steel jacket evaporation kettle, outputting the heat-conducting oil from the top of the jacket, and carrying out heat treatment on the heat-conducting oil containing NMP and H 2 Heating the mixed liquid of O, butyric acid and sodium chloride, stirring at 63rpm, when the temperature reaches 76.1 deg.C, starting vacuum pump, allowing water vapor to flow out from the top of 316L stainless steel jacketed evaporation kettle, cooling by condenser arranged at the top, flowing into wastewater treatment process, treating, recycling, when the solution in 316L stainless steel jacketed evaporation kettle becomes brown and has crystal crystallized, measuring viscosity of the mixed liquid at linear viscometer to be 13.7cPa.s, measuring water content in the mixed liquid by liquid chromatography to reach 0.7 wt%, separating the rest mixed liquid in solid-liquid separation centrifuge, wherein the solid is light green sodium chloride containing small amount of NMP and organic impurities, and feeding sodium chloride backA drying device; inputting the filtrate into an NMP solvent recovery rectifying tower;
(3) Inputting the light green sodium chloride solid containing a small amount of NMP and organic impurities separated in the step (2) into a spiral dryer, respectively configuring a phi 60 steam outlet at the front part, the middle part and the tail part of the spiral dryer, connecting the outlet with the lower opening of a condenser tube side, connecting the upper outlet of the condenser tube side with the inlet of a vacuum pump, cooling the steam containing NMP evaporated from the spiral dryer by a condenser, and inputting the steam containing NMP and H 2 Acidifying and concentrating the mixed liquid of O and sodium chloride, and then rectifying the mixed liquid in a rectifying tower, wherein cooling water is input from the lower opening of the shell side of the condenser and output from the upper opening of the shell side of the condenser to a circulating water storage tank for recycling;
(4) And (3) separating the mixed liquid containing NMP from the step (2), inputting the mixed liquid from the middle part of the rectifying tower at an input speed of 6L/min, assembling a 20L glass jacket evaporator at the lower part of the rectifying tower, assembling a magnetic stirrer below the glass jacket evaporator, stirring the mixed liquid containing the NMP solvent which is not evaporated at a stirring speed of 49rpm, inputting heat conduction oil from the bottom of the glass jacket evaporator, outputting the heat conduction oil from the top of the glass jacket evaporator, inputting the evaporated NMP steam into a condenser arranged at the top of the rectifying tower, inputting the evaporated NMP steam from a tube pass bottom inlet of the condenser, connecting a top outlet of the condenser with an inlet of a vacuum pump, cooling the NMP steam by the condenser, flowing out from the lower end of a tube pass of the condenser, detecting the NMP content of 98.93 wt by a liquid chromatograph, then returning the unqualified NMP steam to a NMP crude NMP temporary storage tank, wherein the recovery rate of the NMP solvent in the experiment is 95.45%, and the mixed liquid evaporated NMP solvent after the detection and the acidification, a ring-opening compound exists.

Claims (6)

1. A solvent recovery process in the production process flow of polyphenylene sulfide adopts sodium sulfide dihydrate and p-dichlorobenzene as raw materials, N-methyl-2-pyrrolidone as a solvent, and polyphenylene sulfide resin is synthesized and produced through dehydration and polycondensation process steps, and is characterized in that: wherein the filter cake is a mixture of polyphenylene sulfide resin, sodium chloride and NMP solvent, and the filtrate is NMP and H 2 O, alkali metalAdding a certain amount of water-soluble acidic substance into the filtrate, converting the alkali metal organic acid salt in the filtrate into organic acid and alkali metal water-soluble salt-sodium chloride, removing the organic acid and water by reduced pressure evaporation, and then distilling and purifying the NMP solvent containing a small amount of water to recover the NMP solvent used for synthesizing the polyphenylene sulfide resin; the NMP solvent recovery process flow comprises the following steps:
(1) NMP and H were added to 100L at a stirring speed of 10 to 50rpm 2 Adding 10-30L of water-soluble acidic liquid with the concentration of 3-8%v/v into mixed liquid of O, alkali metal organic acid salt and sodium chloride at the flow rate of 0.3-0.8L/min, and inputting the mixed liquid into a 316L stainless steel jacket evaporation kettle when the pH value of the mixed liquid is measured to be 0-4 by an on-line acidimeter;
(2) Inputting the acidified mixed solution obtained in the step (1) into a 200L 316L stainless steel jacket evaporation kettle, inputting heat conducting oil from the bottom of the jacket of the 316L stainless steel jacket evaporation kettle, and outputting the heat conducting oil from the top of the jacket to the evaporation kettle containing NMP and H 2 Heating the mixed liquid of O, organic acid and sodium chloride, stirring the mixed liquid at a stirring speed of 30-80 rpm, starting a vacuum pump when the temperature reaches 60-90 ℃, allowing water vapor to flow out of the top of a 316L stainless steel jacket evaporation kettle, cooling the mixed liquid by a condenser arranged at the top, allowing the cooled mixed liquid to flow into a wastewater treatment process, treating the wastewater for recycling, allowing the solution in the 316L stainless steel jacket evaporation kettle to be brownish, detecting the viscosity of the mixed liquid to be 2.0-6.0cPa.s by an online viscometer when crystals are crystallized, detecting the water content in the mixed liquid to be 1.5-1.8 wt by liquid chromatography, inputting the mixed liquid into a solid-liquid separation centrifuge for separation, inputting light green sodium chloride solid containing a small amount of NMP and organic impurities, and inputting the light green sodium chloride into a sodium chloride recovery and drying device; inputting the filtrate into an NMP solvent recovery rectifying tower;
(3) Inputting the light green sodium chloride solid containing a small amount of NMP and organic impurities separated in the step (2) into a spiral dryer, respectively configuring a steam outlet with phi 60 at the front part, the middle part and the tail part of the spiral dryer, connecting the steam outlet with the lower opening of a condenser tube pass, and connecting the upper outlet of the condenser tube pass with the lower opening of the condenser tube passThe inlet of the vacuum pump is connected, and the vapor containing NMP evaporated from the spiral dryer is cooled by the condenser and then is fed with NMP and H 2 The mixed liquid of O, alkali metal organic acid salt and sodium chloride is acidified and concentrated, and then is input into a rectifying tower for rectification, cooling water is input from a lower opening of a shell pass of a condenser, and is output to a circulating water storage tank from an upper opening of the shell pass of the condenser for recycling;
(4) And (3) inputting the mixed liquid containing NMP obtained by separation in the step (2) from the middle of a rectifying tower at an input speed of 2-8L/min, assembling a 20L glass jacket evaporator at the lower part of the rectifying tower, assembling a magnetic stirrer below the glass jacket evaporator, stirring the mixed liquid containing the NMP solvent which is not evaporated at a stirring speed of 30-60 rpm, inputting heat conduction oil from the bottom of the glass jacket evaporator, outputting the heat conduction oil from the top of the glass jacket evaporator, inputting the evaporated NMP steam into a condenser arranged at the top of the rectifying tower, inputting the NMP steam from a tube side bottom inlet of the condenser, connecting an inlet of a vacuum pump to a top outlet of the condenser, cooling the NMP steam after being cooled by the condenser, flowing out from the lower end of a tube side of the condenser, detecting the NMP content of 99.96-99.98 percent by weight through a liquid chromatograph, inputting the NMP into a storage tank, returning the unqualified NMP to a crude product rectifying tank, inputting the NMP into the NMP rectifying tower again for purification, inputting cooling water from a bottom inlet of a shell side of the condenser, outputting the water from the upper part of the shell side of the condenser, and flowing into a circulating water storage tank after cooling.
2. The solvent recovery process in the polyphenylene sulfide production process flow according to claim 1, characterized in that: the water-soluble acidic liquid is hydrochloric acid and ammonium chloride aqueous solution.
3. The solvent recovery process in the polyphenylene sulfide production process flow according to claim 1, characterized in that: the alkali metal organic acid salt is sodium benzoate, sodium formate, sodium acetate, sodium propionate and sodium butyrate; the organic acid is benzoic acid, formic acid, acetic acid, propionic acid or butyric acid.
4. According toThe solvent recovery process in the polyphenylene sulfide production process flow of claim 1, wherein: the composition contains NMP and H 2 O, an alkali metal organic acid salt, sodium chloride, 15 to 35% by weight of NMP,1.5 to 3.5% by weight of an alkali metal organic acid salt, 10 to 25% by weight of sodium chloride, 36.5 to 71.5% by weight of WtH 2 O。
5. The solvent recovery process in the polyphenylene sulfide production process flow according to claim 1, characterized in that: the composition contains NMP and H 2 The mixed liquid of O, alkali metal organic acid salt and sodium chloride is acidified to contain 10-30% by weight of NMP, 11-28% by weight of sodium chloride, 44.2-78.7% by weight of wtH 2 O, 0.3 to 0.8% by weight of an excess amount of water-soluble acid.
6. The solvent recovery process in the polyphenylene sulfide production process flow according to claim 2, characterized in that: when the water-soluble acidic liquid is ammonium chloride, the mixed liquid contains ammonium benzoate, ammonium formate, ammonium acetate, ammonium propionate and ammonium butyrate; the content is 1.0 to 3.0 percent by weight.
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JPH0722645B2 (en) * 1988-10-18 1995-03-15 出光石油化学株式会社 Polyarylene sulfide manufacturing solvent recovery method
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