JP2016030232A - Organic solvent refining system and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic solvent refining system where energy saving performance is excellent, the oxidation degradation of the organic solvent is hardly caused and ionic impurities can be removed with a small processing load.SOLUTION: An organic solvent refining system separating and refining an organic solvent from a mixed liquid containing the organic solvent such as N-methyl-2-pyrolidone (NMP) and the like whose boiling point at 1 atmospheric pressure is more than 100°C and water includes: a deaerator 21 removing a gas component contained in the supplied mixed liquid; a heating means such as a heat exchanger 12 heating the mixed liquid processed at the deaerator 21; and a pervaporation device 13 supplied with the heated liquid. The organic solvent is recovered from the concentration side of the pervaporation device 13. For example, a deaeration membrane is used as the deaerator 21.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a system and method for separating and purifying an organic solvent from a mixture of an organic solvent typified by N-methyl-2-pyrrolidone (hereinafter also referred to as NMP) and water. The present invention relates to an organic solvent purification system and method used.

  Some organic solvents have a high solubility in water. When such water-soluble organic solvents are used and recovered and reused, a mixture of organic solvent and water is often recovered, so the organic solvent to be reused is separated from this mixture. Need to be purified. The collected liquid mixture may contain impurities such as ionic substances and fine particles in addition to the organic solvent and water. Moreover, the mixed liquid contains dissolved gases such as dissolved oxygen and dissolved carbon dioxide, depending on the use form and recovery form of the organic solvent.

  NMP, which is one of organic solvents having high solubility in water, is applied, for example, to a slurry in which particles such as an electrode active material are dispersed on an electrode current collector in a manufacturing process of a lithium ion secondary battery and then dried. Thus, when forming an electrode, it is widely used as a slurry dispersion medium. NMP is recovered when the slurry is dried, and the recovered NMP can be reused after purification. In the recovery of NMP, the vaporized NMP is recovered by, for example, a water scrubber. Therefore, NMP is recovered as a mixed liquid in which NMP and water are mixed. At this time, the NMP concentration in the collected mixed liquid is about 70 to 90% by mass. Since a water scrubber is used, oxygen and carbon dioxide derived from the atmosphere are dissolved in the mixed solution.

  Conventionally, a distillation method is known as a method for separating and recovering an organic solvent from a mixed solution of an organic solvent and water, and in particular, a vacuum distillation method in which the mixed solution is distilled under reduced pressure is often used. However, the distillation method or the vacuum distillation method has a problem that a large amount of energy is required and a large-scale distillation facility is required when purifying an organic solvent to a desired purity. Therefore, a pervaporation (PV) method is known as a separation method that does not require large-scale equipment and has excellent energy saving performance.

  In the permeation vaporization method, a separation membrane (permeation vaporization membrane) having an affinity for a component to be subjected to separation processing (for example, moisture) is used, and a mixed liquid containing the target component (for example, mixing of an organic solvent and water) The liquid is supplied to the supply side of the separation membrane, and the pressure is reduced or the inert gas is supplied to the permeation side of the separation membrane, so that the separation is performed by the difference in permeation speed of each component in the separation membrane. As the separation membrane for allowing moisture to permeate, for example, a zeolite membrane is used. If only water moves to the permeation side by the separation membrane, the organic solvent remains on the supply side of the separation membrane, and the organic solvent can be recovered. When the water and the organic solvent are separated by the pervaporation method, heating is necessary for efficient separation.

  In Patent Literature 1, an osmosis vaporizer is used as an NMP separation system for separating NMP from a mixed liquid of NMP and water, and an ion exchange device is provided in the preceding stage of the osmosis vaporizer to remove ionic impurities. Is disclosed in which the mixed liquid is supplied to the pervaporation apparatus.

  FIG. 6 shows an example of the configuration of a conventional organic solvent refining system including an osmosis vaporizer and an ion exchange device provided in the preceding stage. A liquid mixture of NMP and water at normal temperature is supplied to the ion exchange device 11. A heat exchanger 12 is provided at the outlet of the ion exchange device to raise the temperature of the mixed solution with steam, and the mixed solution having a temperature of about 120 ° C. is supplied to the pervaporation device 13. In the pervaporation device 13, a pervaporation membrane 14 made of, for example, zeolite is provided. Moisture in the mixed solution permeates through the pervaporation membrane 14 and is then cooled and discharged by the heat exchanger 16 through cold water. On the other hand, since NMP does not permeate the pervaporation membrane 14, it is discharged from the concentration side of the pervaporation device 13 as a liquid. The NMP discharged from the pervaporation device 13 is cooled by the heat exchanger 15 through cold water. The room temperature NMP thus obtained is stored in, for example, a tank or sent to a process using NMP.

JP 2013-18747 A

  As a method for separating water from an organic solvent such as NMP, the pervaporation method is superior in energy saving performance compared to a distillation method or the like. However, when supplying to a pervaporation apparatus provided with a hydrophilic pervaporation film, the supply liquid to the pervaporation apparatus must be heated. This heating may oxidize and deteriorate the organic solvent.

  An object of the present invention is to provide an organic solvent refining system and method that are excellent in energy saving performance by using an osmosis vaporizer and are less susceptible to oxidative degradation of the organic solvent.

  The organic solvent refining system of the present invention is an organic solvent refining system for separating and purifying an organic solvent from a mixed solution containing water and an organic solvent having a boiling point of more than 100 ° C. at 1 atm. A degassing unit that removes a gas component contained in the liquid mixture when the liquid is supplied, a heating unit that heats the liquid processed by the deaeration unit, and an osmosis vaporizer that is supplied with the heated liquid. The organic solvent is recovered from the concentration side of the pervaporation device.

  The organic solvent purification method of the present invention is a method for separating and purifying an organic solvent from a mixed solution containing an organic solvent having a boiling point of more than 100 ° C. at 1 atm, and is contained in the mixed solution. From the concentration side of the pervaporation device, the degassing step of removing the gas component, the step of heating the liquid treated in the deaeration step, and the step of supplying the heated liquid to the pervaporation device Collect the organic solvent.

  According to the present invention, in an organic solvent purification system that includes an osmosis vaporizer and separates and purifies an organic solvent from a mixed liquid of an organic solvent and water, a degassing unit that removes a gas component contained in the mixed liquid is provided, By heating the degassed mixed liquid and then supplying it to the pervaporation device, the effect of suppressing oxidation and deterioration in NMP obtained from the pervaporation device can be obtained.

It is a figure which shows the structure of the organic-solvent refinement | purification system of one Embodiment of this invention. It is a figure which shows the structure of the organic-solvent refinement | purification system of embodiment which has an ion exchange apparatus. It is a figure which shows the structure of the organic-solvent refinement | purification system of another embodiment of this invention. It is a figure which shows the structure of the organic-solvent refinement | purification system of another embodiment of this invention. It is a figure which shows the structure of the organic solvent refinement | purification system in a comparative example. It is a figure which shows an example of a structure of the conventional organic solvent refinement | purification system.

  Next, a preferred embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an organic solvent purification system according to an embodiment of the present invention. This organic solvent refining system separates and purifies an organic solvent from a mixture of an organic solvent and water. For example, NMP (N-methyl-) recovered from a manufacturing process of a lithium ion secondary battery or the like. 2-pyrrolidone) and water are treated to separate and purify NMP. Hereinafter, the case where NMP is used as the organic solvent will be described. However, the organic solvent to which the present invention can be applied is not limited to NMP, and generally the boiling point at atmospheric pressure (0.1013 Mpa) is the boiling point of water. The present invention is also applied to an organic solvent having a boiling point higher than (100 ° C.), preferably 120 ° C. or higher, which is a general operating temperature of a pervaporation membrane apparatus at atmospheric pressure. Can do. Examples of such organic solvents are shown in Table 1. In Table 1, the boiling point is a value at 0.1013 MPa. Furthermore, as an organic solvent to which the present invention can be applied, an organic solvent that does not form an azeotrope with water (for example, in the organic solvents shown in Table 1, except for PGME, PEGMEA, and pyridine) is more preferable. .

  A degassing device 21 is provided to remove a gaseous component in the mixed solution by supplying a mixed solution of NMP and water at room temperature. A heat exchanger 12 that heats the mixed liquid by exchanging heat with steam is provided at the outlet of the degassing device 21, and the mixed liquid heated to, for example, about 120 ° C. by the heat exchanger 12 then permeates. It is supplied to the vaporizer 13. The pervaporation device 13 is provided with a pervaporation membrane 14 made of, for example, zeolite, where the mixed solution is separated into NMP and water. Since water permeates the pervaporation membrane 14, it flows out from the permeate side outlet of the pervaporation device 12 in the form of water vapor. The water vapor is cooled by the heat exchanger 16 through cold water and discharged as liquid water. On the other hand, since NMP does not permeate the pervaporation membrane 14, it is discharged from the outlet provided on the concentration side (that is, the inlet side across the permeation vaporization membrane 14) in the pervaporation device 13, and cooled by cold water in the heat exchanger 15. Is done. As a result, purified NMP at room temperature is obtained at the outlet of the heat exchanger 15.

  As the degassing device 21, for example, an oxygen removing device that removes oxygen by adding hydrogen to contact with a palladium catalyst can be used. However, in the case of the oxygen removing device, a gas component other than oxygen, for example, Dissolved carbon dioxide cannot be removed. Although it is possible to remove the dissolved oxygen and the like by blowing an inert gas such as nitrogen or argon into the liquid, it is not possible to perform the deaeration process quickly. From such a viewpoint, it is preferable to use the deaeration device 21 using a deaeration membrane. By using a degassing membrane, dissolved oxygen and other dissolved gases in the mixed solution can be quickly removed without supplying hydrogen, inert gas, or the like.

  Examples of the membrane material and potting material for constituting the deaeration membrane include polyolefin, polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), polyurethane, and epoxy resin. However, since NMP has a property of dissolving some organic materials, in this embodiment, it is preferable to form a degassing membrane by polyolefin, PTFE and PFA. The mechanical structure of the deaeration membrane includes a porous membrane assumed to be used in water and a non-porous membrane assumed to be used in a liquid having a smaller surface tension, but contains a large amount of NMP. In this embodiment for treating the mixed solution, it is preferable to use a non-porous film. An example of a degassing membrane that can be used in the present embodiment is a polyolefin membrane disclosed in Japanese Patent Application Laid-Open No. 2004-105797.

  In such an organic solvent refining system of this embodiment, a mixed liquid from which dissolved oxygen and dissolved carbon dioxide have been removed by the degassing device 21 is supplied to the ion exchange device 11. Thereafter, the mixed liquid is heated to, for example, about 120 ° C. by the heat exchanger 12 and then supplied to the pervaporation apparatus 13. Since dissolved oxygen in the mixed solution is reduced before heating, oxidation and deterioration of NMP can be suppressed as will be apparent from Examples described later.

  When an organic solvent is recovered from various manufacturing processes in the form of a mixed liquid of the organic solvent and water, the mixed liquid often contains ionic impurities. For example, when a mixed liquid of NMP and water is recovered from a manufacturing process of a lithium ion secondary battery or the like, the mixed liquid contains ionic impurities. When purifying the organic solvent, it is preferable to remove ionic impurities in the mixed solution. As a method for removing ionic impurities contained in an organic solvent, a method using an ion exchange resin is known. Since ion exchange resins exhibit higher ion removal performance in the presence of water, when separating and purifying an organic solvent from a mixture containing the organic solvent and water, the ion exchange resin must be ionized prior to separation of the organic solvent and water. It is advantageous to perform the treatment with an exchange resin.

  FIG. 2 shows an example of the configuration of the organic solvent purification system provided with an ion exchange device 11 for removing ionic impurities in the mixed liquid of NMP and water, in addition to the organic solvent purification system shown in FIG. Show. The ion exchange device 11 removes ionic impurities contained in the mixed solution, for example, one filled with an anion exchange resin, or one filled with an anion exchange resin and a cation exchange resin in a mixed bed. It is.

  In the configuration in which the ion exchange device 11 is provided in front of the pervaporation device 13, dissolved carbon dioxide or carbonate ions contained in a mixture of an organic solvent such as NMP and water are converted into the ion exchange device 11, particularly an anion contained therein. This is a heavy load on the exchange resin. Therefore, in the system shown in FIG. 2, the ion exchange device 11 is connected to the outlet of the deaeration device 21, the ion exchange treatment is performed on the mixed solution that has been deaerated by the deaeration device 21, and the ion exchange treatment is performed. The prepared mixed liquid is sent to the heat exchanger 12. The deaerator 21 is preferably one that can remove not only dissolved oxygen in the mixed solution but also dissolved carbon dioxide. For this reason, it is preferable to use one using a deaeration membrane.

  In the organic solvent refining system shown in FIG. 2, the mixed solution from which dissolved oxygen and dissolved carbon dioxide have been removed by the degassing device 21 is supplied to the ion exchange device 11, and then this mixed solution is transferred to the heat exchanger 12 by, for example, 120 After being heated to about 0 ° C., it is supplied to the pervaporation device 13. Since the amount of dissolved oxygen in the liquid mixture is reduced, oxidation and deterioration of NMP can be suppressed, and furthermore, the load on the ion exchange device 11 is reduced because the carbon dioxide concentration in the liquid mixture is reduced. As a result, the exchange cycle of the ion exchange resin in the ion exchange device 11 can be lengthened.

  FIG. 3 shows an organic solvent purification system according to another embodiment of the present invention. The organic solvent refining system shown in FIG. 3 is different from the organic solvent refining system shown in FIG. 2 in that a stock solution tank 31 for storing a mixed liquid of NMP and water, and a refining solution tank 32 for storing purified NMP are provided. A membrane deaerator 22 having a deaerator as a deaerator and two pumps 23 and 24 are added. In the organic solvent refining system of FIG. 3, the membrane degassing device 22 is not provided immediately before the ion exchange device 11, but is instead arranged to degas the mixed solution in the stock solution tank 31. Yes. A pipe 33 for connecting the bottom and top of the stock solution tank 31 and circulating the mixed solution by the pump 24 is provided. The membrane degassing device 22 is provided in the pipe 33, and the stock solution tank 31 is provided in the stock solution tank 31. The degassed mixed liquid is stored. The degassed mixed solution in the stock solution tank 31 is supplied to the ion exchange device 11 by the pump 23. The configuration from the ion exchange device 11 to the heat exchangers 15 and 16 in the organic solvent refining system shown in FIG. 3 is the same as that shown in FIG. The purified liquid tank 32 is connected to the outlet of the heat exchanger 15 and stores the purified NMP cooled by the heat exchanger 15.

  In general, the optimal liquid flow rate for membrane deaeration and the optimal liquid flow rate in the operation of the pervaporation device do not always match. In the configuration shown in FIG. 3, by independently controlling the two pumps 23 and 24, the flow rate of the mixed solution in the membrane degassing device 22 and the flow rate of the mixed solution supplied to the pervaporation device 13 are set independently. It is possible to perform membrane degassing and pervaporation under optimum conditions. Further, even during a period when NMP purification is not performed, only the membrane deaeration is continuously performed by the small-capacity pump 24, so that the start-up of the process at the start of NMP purification can be accelerated.

  FIG. 4 shows the configuration of an organic solvent purification system according to still another embodiment of the present invention. 1 to 3 uses a single-stage pervaporation device 13. In this case, moisture should remain in the obtained NMP or be discharged as waste water through the heat exchanger 16. NMP may remain in the water. Therefore, in the organic solvent refining system shown in FIG. 4, two pervaporation devices 13 and 25 are connected in series to perform pervaporation processing in two stages.

  Specifically, the organic solvent refining system shown in FIG. 4 supplies the liquid discharged from the concentration side of the pervaporation device 13 to the second-stage pervaporation device 25 in the system shown in FIG. . If attention is paid to the flow of NMP, these pervaporation devices 13 and 25 are connected in series. The second stage pervaporation apparatus 25 also includes an pervaporation membrane 26 made of, for example, zeolite. NMP is separated from the concentration side of the second stage pervaporation apparatus 25, and this separation is performed in the same manner as the system shown in FIG. The purified NMP is cooled by the heat exchanger 15, and the purified NMP is stored in the purified liquid tank 32. The water obtained from the permeation side of the second stage pervaporation device 25 is cooled by the cold water in the heat exchanger 27 and then returned to the front stage of the first stage pervaporation device 13 by the pipe 34. In the illustrated example, the water from the heat exchanger 27 is returned to the inlet of the membrane deaerator 22 or the stock solution tank 31, but the destination for returning the water from the heat exchanger 27 is the inlet of the membrane deaerator 22 or For example, the stock solution tank 31 may be returned to the inlet of the heater 12.

  The pervaporation membranes 14 and 26 used in the pervaporation devices 13 and 25 will be described. The dewatering performance of the pervaporation apparatuses 13 and 25 depends on the moisture density difference between both sides of the pervaporation membranes 14 and 26, that is, the concentration side space and the permeation side space, and the degree of vacuum on the permeation side. Specifically, the higher the moisture density in the concentrated space or the higher the degree of vacuum on the permeate side (the lower the absolute pressure), the better the dehydration performance. If the mixed liquid of NMP and water is recovered from the manufacturing process of the lithium ion secondary battery, the concentration of water in this mixed liquid is normally 10 to 30% by mass, so that the first stage The pervaporation apparatus 13 can separate a large amount of water due to a large water density difference. On the other hand, since the second stage pervaporation apparatus 25 processes the already dehydrated mixed liquid, the amount of water to be separated is small. On the other hand, the amount of NMP permeation through the pervaporation membrane does not depend greatly on the moisture density difference. For this reason, the NMP concentration in the water vapor that appears on the permeation side of the first stage pervaporation device 13 is extremely low, and the NMP concentration of the water vapor that appears on the permeation side of the second stage pervaporation device 25 becomes higher. In this embodiment, the NMP recovery rate is further improved by returning the moisture containing NMP, which appears on the permeation side of the second stage pervaporation apparatus 25, to the front stage of the first stage pervaporation apparatus 13, NMP release to the environment is suppressed. Note that the amount of moisture permeating through the second stage pervaporation device 25 is smaller than that in the first stage, and the reduction in dehydration efficiency due to returning this moisture to the previous stage of the first stage pervaporation device 13 is limited. Is.

  For the pervaporation membranes 14, 26, a zeolite membrane is preferably used. There are various types of zeolite such as A-type, Y-type, T-type, MOR-type, and CHA-type depending on the framework structure and the ratio of silicon and aluminum contained therein. The higher the proportion of silicon compared to aluminum, the richer the hydrophobicity. Among these zeolites, the A type is particularly excellent in dehydration efficiency, and can be used as the pervaporation membranes 14 and 26 of both pervaporation apparatuses 13 and 25 in this embodiment. In some cases, it is preferable to use, for example, a T-type, Y-type, or CHA-type zeolite membrane other than the A-type as the pervaporation membrane 14 of the first-stage pervaporation apparatus 13. A-type zeolite is likely to cause leaks and performance degradation when the water concentration is high or when impurities such as acids are contained in the mixed solution. On the other hand, zeolites other than the A type can maintain performance for a longer period in the above-described environment. As described above, the pervaporation membrane 14 of the first-stage pervaporation device 13 does not require higher dehydration performance than the pervaporation membrane 26 of the second-stage pervaporation device 25. Further, since the water vapor from the permeation side of the first stage pervaporation device 13 is released out of the system, the necessity to prevent the permeation vaporization membrane 14 from leaking is particularly high here. Therefore, as the pervaporation membrane 14 of the first stage pervaporation device 13, at least one type selected from A-type zeolite and the other zeolites described above (for example, T-type, Y-type, MOR-type, CHA-type). Those containing zeolite can also be used. In any case, it is desirable that the pervaporation membrane 26 of the second stage pervaporation device 25 is made of A-type zeolite. Since the inlet liquid of the second stage pervaporation apparatus 25 has already been dehydrated in a considerable amount and contains a small amount of water, it is unlikely that the water in the inlet liquid will adversely affect the membrane performance. Further, since the moisture in the inlet liquid is small, the driving force for dehydration is small, and membranes other than the A type require a larger membrane area than the A type. For this reason, apparatus scales and apparatus costs tend to increase with films other than A-type films.

  In addition, the dewatering performance of the pervaporation device has a positive correlation with the permeate vaporization membrane flow area per unit flow rate of the supplied liquid mixture (the value obtained by dividing the permeate vaporization membrane flow area by the flow rate of the liquid mixture). is there. Therefore, in order to obtain the required dewatering performance with a single pervaporation device, it is necessary to increase the permeate vaporization membrane channel area. On the other hand, the permeation amount of NMP is also positively correlated with the permeate vaporization membrane channel area. Therefore, when a single permeation vaporizer with a large channel area is used to improve dewatering performance, the permeation rate of NMP is also increased. It increases according to. On the other hand, in the present embodiment, the first stage pervaporation apparatus 13 only needs to dehydrate a part of the necessary dehydration amount, and it is not necessary to excessively increase the channel area. In the second stage pervaporation device 25, the permeated NMP is returned to the stock solution tank 31 side, so there is no problem even if the flow path area is increased in order to improve the dewatering performance. In other words, the first stage pervaporation apparatus 13 considers the balance between the dewatering amount and the NMP permeation amount, but the second stage pervaporation apparatus 25 does not need to consider such a balance. In this way, the two pervaporation devices 13 and 25 are provided in series, and the NMP that permeates the second permeation vaporization device 25 is collected in the stock solution tank 31 to obtain the necessary dehydration performance, and the NMP system The amount of external release can be suppressed.

  Next, the organic solvent purification system based on this invention is demonstrated in more detail using an Example.

(Example)
The organic solvent purification system shown in FIG. 3 was assembled, and an NMP aqueous solution having a water content of 20% by mass was adjusted in the stock solution tank 31. The pump 24 was driven to operate only the membrane degassing device 22 to degas the NMP aqueous solution. At this time, it was confirmed that the dissolved oxygen partial pressure in the NMP aqueous solution was 0.02 kPa using a dissolved oxygen meter (Orbis Fair, model 3600: hereinafter the same). Further, the concentration of N-methylsuccinimide, which is an oxidation product of NMP, in the stock solution tank 31 is confirmed by a GC-MS (gas chromatography-mass spectrometry) method (GC-2014 manufactured by Shimadzu Corporation is used hereinafter). As a result, it was 110 ppm.

  Next, the pump 23 was driven, the NMP aqueous solution in the stock solution tank 31 was supplied to the pervaporation apparatus 13, and the pervaporation process was performed at 120 ° C. to obtain NMP having a water content of 0.02%. The NMP thus obtained was stored in the purified liquid tank 32. The concentration of N-methylsuccinimide in NMP stored in the purified liquid tank 32 was observed over time by the GS-MS method. The results are shown in Table 2.

(Comparative example)
The organic solvent purification system shown in FIG. 5 was assembled. In this system, the membrane deaerator 22, the pump 24 and the pipe 33 are removed from the organic solvent purification system shown in FIG. 3 so that an NMP aqueous solution which has not been deaerated is supplied to the ion exchange device 11 and the pervaporation device 13. It is a thing.

  An NMP aqueous solution having a water content of 20% by mass was prepared in the stock solution tank 31, and it was confirmed that the dissolved oxygen partial pressure in the NMP aqueous solution was 20 kPa using a dissolved oxygen meter. Moreover, it was 110 ppm when the density | concentration of N-methylsuccinimide in the stock solution tank 31 was confirmed by GC-MS method.

  Next, the pump 23 was driven, the NMP aqueous solution in the stock solution tank 31 was supplied to the pervaporation apparatus 13, and the pervaporation process was performed at 120 ° C. to obtain NMP having a water content of 0.02%. The NMP thus obtained was stored in the purified liquid tank 32. The concentration of N-methylsuccinimide in NMP stored in the purified liquid tank 32 was observed over time by the GS-MS method. The results are shown in Table 2.

  As is apparent from Table 2, in Examples where degassing was performed and the dissolved oxygen concentration in the feed liquid to the pervaporation apparatus was sufficiently reduced, the concentration of oxide (N-methylsuccinimide) in the obtained purified NMP Changed little over time and was kept low. On the other hand, in the comparative example in which a liquid having a high dissolved oxygen concentration was supplied to the pervaporation apparatus without deaeration, the oxide in the obtained purified NMP increased greatly with time, and oxidation and degradation of NMP occurred. .

  From the above results, when separating and purifying NMP from a mixed liquid of NMP and water, the mixed liquid is degassed and then subjected to pervaporation treatment, so that the obtained purified NMP can be oxidized and deteriorated. It can be seen that it can be prevented.

DESCRIPTION OF SYMBOLS 11 Ion exchanger 12, 15, 16, 27 Heat exchanger 13, 25 Osmosis vaporizer 21 Deaerator 22 Membrane deaerator 31 Stock solution tank 32 Purified liquid tank

Claims (9)

An organic solvent refining system for separating and refining the organic solvent from a mixed liquid containing water and an organic solvent having a boiling point of more than 100 ° C. at 1 atm,
Degassing means for removing the gas component contained in the liquid mixture supplied with the liquid mixture;
Heating means for heating the liquid treated by the deaeration means;
A pervaporation apparatus to which the heated liquid is supplied;
An organic solvent refining system for recovering the organic solvent from the concentration side of the pervaporation apparatus.   The organic solvent purification system according to claim 1, wherein the organic solvent is N-methyl-2-pyrrolidone. An ion exchange device that performs an ion exchange treatment on the mixed solution treated by the degassing means;
The organic solvent refining system according to claim 1 or 2, wherein the mixed solution subjected to the ion exchange treatment is supplied to the heating means.   The organic solvent purification system according to any one of claims 1 to 3, wherein the deaeration means includes a deaeration membrane.   The organic solvent purification system according to claim 4, wherein the degassing membrane is a non-porous membrane made of at least one of polyolefin, polytetrafluoroethylene, and tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer. .   The organic solvent refining system according to claim 1, further comprising: a tank that stores the mixed liquid; and a pipe that circulates the mixed liquid between the deaeration unit and the tank. The pervaporation device is configured by connecting in series a first pervaporation device and a second pervaporation device supplied with liquid discharged from the concentration side of the first pervaporation device,
The organic solvent is recovered from the concentration side of the second pervaporation device;
The organic solvent refining system according to claim 6, further comprising a pipe for circulating the liquid discharged from the permeation side of the second pervaporation device to the front stage of the first pervaporation device.   The organic solvent purification system according to any one of claims 1 to 7, wherein the ion exchange device includes at least one of an anion exchange resin and a mixed bed ion exchange resin. A method for separating and purifying the organic solvent from a mixed liquid containing an organic solvent having a boiling point of more than 100 ° C. at 1 atm and water,
A degassing step of removing a gas component contained in the liquid mixture;
Heating the liquid treated in the degassing step;
Supplying the heated liquid to a pervaporation device;
And the organic solvent is recovered from the concentration side of the pervaporation apparatus.

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