Raw material liquid concentration system

Abstract

To provide a concentration system capable of efficiently and effectively reducing a volatile solvent with a small absorbent use amount from a raw material liquid containing water, the volatile solvent, and a solute.SOLUTION: This concentration system for reducing a concentration of a volatile solvent from a raw material liquid FS containing water, the volatile solvent, and a solute comprises: concentration means (concentration membrane distillation module 110) for contacting the raw material liquid FS with an absorbent CW for moving the volatile solvent from the raw material liquid FS via a hydrophobic porous membrane 12 to increase the concentration of the solute in the raw material liquid FS; and reproduction means (reproduction membrane distillation module 210) for continuously removing the volatile solvent moved to the absorbent CW.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a system for concentrating a raw material liquid. [Background technology]

[0002] In the production of chemicals and the like, a concentration step is often required after the synthesis step and the purification step. In the concentration step, when the target product must be left behind while removing the solvent, the solvent may contain an organic solvent, and the target product may be heat-sensitive. Conventionally, methods known for the concentration step include distillation (including vacuum distillation) accompanied by heating, membrane filtration (including filtration using microfiltration, ultrafiltration membranes, and reverse osmosis membranes), spray drying, and freeze drying.

[0003] However, distillation involving heating may result in thermal degradation of the target product. Furthermore, it is difficult to concentrate compounds with molecular weights smaller than the membrane cutoff when using membrane filtration. Furthermore, when pressure and shear are applied during filtration, the target substance may be destroyed or adhere to the membrane due to shear stress, resulting in a decrease in yield. Furthermore, spray drying and freeze drying take a very long time to concentrate. Therefore, in recent years, non-heated and non-pressurized concentration techniques using forward osmosis membranes and direct contact membrane distillation (DCMD) have been proposed.

[0004] In Patent Document 1, a membrane is applied to a raw material solution consisting of an organic solvent, water, and peptides, thereby attempting to remove the organic solvent and water at room temperature. Here, the forward osmosis membrane mainly removes water, while the direct contact membrane distillation membrane mainly removes the organic solvent.

[0005] Patent Document 2 attempts to transfer substances with low water distribution coefficients (e.g., organic compounds such as orange oil oxygenates and xylene) through a first membrane into an absorption solution mainly composed of water, and then recover the substances from the absorption solution using a second membrane.

[0006] Patent Document 3 attempts to transfer the volatile compounds from an aqueous emulsion solution containing the volatile compounds to an absorption liquid through a first membrane, and then to regenerate the absorption liquid by further removing the volatile compounds with a second membrane. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2021 / 054406 [Patent Document 2] Japanese Patent Application Publication No. 06-99005 [Patent Document 3] U.S. Patent No. 6,365,051 [Patent Document 4] Patent No. 5884349 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in Patent Document 1, the removal of organic solvents using a direct contact membrane distillation membrane utilizes the vapor permeation of volatile components, driven by the difference in vapor pressure of the solvent between the feed liquid and the absorption liquid, which are primarily composed of water, when the feed liquid and the absorption liquid are brought into contact through the membrane. Therefore, as the vapor pressure of the volatile solvent approaches equilibrium between the feed liquid and the absorption liquid, the vapor permeation rate decreases, and when equilibrium is finally reached, the apparent amount of vapor movement becomes zero. Therefore, there is a problem with direct contact membrane distillation in that there is a limit to the concentration reduction of the volatile solvent in the feed liquid.

[0009] In direct contact membrane distillation, it is possible to further reduce the concentration of the volatile solvent by appropriately replacing the absorbing liquid, thereby escaping the equilibrium state between the feed liquid and the absorbing liquid. However, this is unrealistic because a huge amount of absorbing liquid would be required. In addition, a technology has been proposed in the past that combines a process of contacting the raw liquid with the absorption liquid through a membrane, thereby transferring specific substances in the raw liquid to the absorption liquid, with a process of regenerating the absorption liquid.

[0010] Patent Document 2 does not consider the combination of a direct contact membrane distillation membrane with a regeneration mechanism. In addition, the regeneration mechanism in Patent Document 2 is based on a microporous membrane whose pores are liquid-sealed with squalane and a sheet without pores, and Patent Document 2 requires high affinity between the membrane of the regeneration mechanism and the organic compound recovered from the absorption liquid, which results in a problem of lack of versatility.

[0011] The technology of Patent Document 3 utilizes the high affinity between the membrane and the volatile compound, and therefore has the problem that there is no solution when the volatile solvent to be removed or recovered is hydrophilic. Patent Document 4 discloses the application of a pervaporation membrane containing zeolite as a method for dehydrating hydrophilic organic compounds. However, in the regeneration of an absorption solution consisting of a large amount of water and a small amount of volatile solvent, a large amount of water needs to be passed through, which has the problem of extremely low efficiency.

[0012] An object of the present invention is to provide a concentration system that can efficiently and effectively reduce the volatile solvent from a raw material liquid containing water, a volatile solvent, and a solute, using a small amount of absorption liquid. It is also an object of the present invention to provide a concentration method (eg, a method of operating such a concentration system) and a concentration device related to such a concentration system. [Means for solving the problem]

[0013] One aspect of the present invention is as follows. [1] A concentration system for reducing a concentration of a volatile solvent from a raw material liquid containing water, a volatile solvent, and a solute, comprising: a concentrating means for increasing the concentration of the solute in the raw material liquid by bringing the raw material liquid into contact with an absorption liquid for transferring the volatile solvent from the raw material liquid via a hydrophobic porous membrane; and a regeneration means for continuously removing the volatile solvent that has migrated to the absorption liquid. Concentration system. [2] When the hydrophobic porous membrane in the concentration means is referred to as a first hydrophobic porous membrane, The regeneration means has a second hydrophobic porous membrane using a membrane distillation method. Item 1. The concentration system according to item 1. [3] The membrane distillation method is a reduced pressure membrane distillation method. Item 2. The concentration system according to item 2. [4] The regeneration means reduces the concentration of the volatile solvent having an octanol / water partition coefficient (log Kow) of 1 or less. The concentration system according to any one of items 1 to 3. [5] The saturated vapor pressure of the volatile solvent at 0°C or higher and lower than 40°C is higher than the saturated vapor pressure of water. The concentration system according to any one of items 1 to 4. [6] The concentration of the volatile solvent in the absorption liquid is 30% by mass or less. 6. The concentration system according to any one of items 1 to 5. [7] The saturated vapor pressure of the volatile solvent at 20°C is 10 kPa or less. The concentration system according to any one of items 1 to 6. [8] In the regeneration means, the concentration of the volatile solvent in the absorption liquid is 30% by mass or less, the volatile solvent has an octanol / water partition coefficient (log Kow) of 1 or less; The saturated vapor pressure of the volatile solvent at 0°C or higher and lower than 40°C is higher than the saturated vapor pressure of water, and The saturated vapor pressure of the volatile solvent at 20°C is 10 kPa or less. 8. The concentration system according to any one of items 1 to 7. [9] The volatile solvent includes at least one selected from the group consisting of acetonitrile, ethanol, methanol, isopropyl alcohol, normal propyl alcohol, 1-butyl alcohol, 2-butyl alcohol, t-butyl alcohol, tetrahydrofuran, acetic acid, and trifluoroacetic acid. The concentration system according to any one of items 1 to 8.

[10] the second hydrophobic porous membrane in the regeneration means has a leakage pressure (LEP) of 150 kPa or more when a test liquid is a 20% by mass ethanol (EtOH) aqueous solution; The second hydrophobic porous membrane has an average pore size of 0.1 μm or more. The second hydrophobic porous membrane has a maximum pore size of less than 0.5 μm; Item 4. The concentration system according to item 2 or 3.

[11] The concentration system further includes a semipermeable membrane using a forward osmosis membrane method in parallel with the first hydrophobic porous membrane using the membrane distillation method, The regeneration means has the second hydrophobic porous membrane by the reduced pressure membrane distillation method, Item 4. The concentration system according to item 2 or 3.

[12] a concentration sensor for detecting the concentration of the volatile solvent in the absorption liquid; controlling the degree of pressure reduction in the regenerating means according to the result of the concentration sensor; 12. The concentration system according to any one of items 1 to 11.

[13] a mass sensor that measures at least the mass of the raw material liquid and the mass of the absorption liquid; a temperature sensor for measuring the temperature of the absorption liquid when the absorption liquid is introduced into the regeneration means and the temperature of the absorption liquid when the absorption liquid is discharged from the regeneration means; a flow rate sensor that measures the flow rate of the absorption liquid flowing through the regeneration means; and a mass of the volatile solvent transferred from the absorption liquid in the regeneration means is calculated based on information from the mass sensor, and further, a latent heat of the volatilized fluid is estimated based on at least one piece of information obtained from the temperature sensor and the flow rate sensor, and the degree of pressure reduction in the regeneration means is controlled. 13. The concentration system according to any one of items 1 to 12.

[14] A concentration method for reducing a concentration of a volatile solvent from a raw material liquid containing water, a volatile solvent, and a solute, comprising: a concentration step of increasing the concentration of the solute in the raw material liquid by bringing the raw material liquid into contact with an absorption liquid for transferring the volatile solvent from the raw material liquid via a hydrophobic porous membrane; a regeneration step of continuously removing the volatile solvent transferred to the absorption liquid; where: the regeneration step is a reduced pressure membrane distillation method using the hydrophobic porous membrane, The concentration method, wherein the absolute pressure in the reduced pressure membrane distillation system is reduced to a pressure lower than the saturated vapor pressure of the absorption liquid.

[15] In the vacuum membrane distillation method, The absolute pressure is reduced to a pressure that is greater than the saturated water vapor pressure and less than the saturated vapor pressure of the absorption liquid, The concentration of the volatile solvent in the absorption liquid is 30% by mass or less. the volatile solvent has an octanol / water partition coefficient (log Kow) of 1 or less; The saturated vapor pressure of the volatile solvent at 0°C or higher and lower than 40°C is higher than the saturated vapor pressure of water, and The saturated vapor pressure of the volatile solvent at 20°C is 10 kPa or less. Item 15. The concentration method according to Item 14.

[16] In the regeneration step, the temperature of the absorption solution when the volatile solvent transfers to the absorption solution is 5 to 40°C. Item 16. The concentration method according to Item 14 or 15.

[17] The volatile solvent includes at least one selected from the group consisting of acetonitrile, ethanol, methanol, isopropyl alcohol, normal propyl alcohol, 1-butyl alcohol, 2-butyl alcohol, t-butyl alcohol, tetrahydrofuran, acetic acid, and trifluoroacetic acid. 17. The concentration method according to any one of Items 14 to 16.

[18] A raw material liquid tank (FS tank) that stores the raw material liquid, An absorption liquid tank (CW tank) for storing absorption liquid; at least one concentration membrane distillation module (DCMD); at least one regenerative membrane distillation module (VMD); at least one cold trap in contact with the refrigerant; a pressure reducing pump; The concentration membrane distillation module comprises: The hydrophobic porous membrane is composed of a space A for contacting one side of the hydrophobic porous membrane with a raw material liquid, and a space B for contacting the other side of the hydrophobic porous membrane with an absorption liquid, a raw material liquid injecting port and a raw material liquid discharging port connected to the space A, and an absorption liquid injecting port and an absorption liquid discharging port connected to the space B, The regenerating membrane distillation module comprises: The hydrophobic porous membrane is composed of a space C for contacting one side of the hydrophobic porous membrane with an absorption liquid, and a space D for reducing the pressure on the other side of the hydrophobic porous membrane, an absorption liquid injection port and an absorption liquid discharge port connected to the space C, and at least one pressure reduction port connected to the space D; Here, the following (1) to (3); (1) the raw material liquid inlet port and the raw material liquid outlet port are connected to the raw material liquid tank; the absorption liquid inlet port and the absorption liquid outlet port are connected to the absorption liquid tank; The pressure reduction port and the pressure reduction pump are connected via the cooling trap. (2) the raw material liquid inlet port and the raw material liquid outlet port are connected to the raw material liquid tank; the absorption liquid discharge port of the space B and the absorption liquid injection port of the space C are connected in series, the absorption liquid inlet port of the space B and the absorption liquid outlet port of the space C are connected to the absorption liquid tank, The pressure reduction port and the pressure reduction pump are connected via the cooling trap. (3) the raw material liquid inlet port and the raw material liquid outlet port are connected to the raw material liquid tank; the absorption liquid discharge port of the space C and the absorption liquid injection port of the space B are connected in series, the absorption liquid inlet port of the space C and the absorption liquid outlet port of the space B are connected to the absorption liquid tank, The pressure reduction port and the pressure reduction pump are connected via the cooling trap. having at least one line configuration among Concentrator.

[19] a heat exchanger is not provided between the raw material liquid inlet port and the raw material liquid tank, and between the raw material liquid outlet port and the raw material liquid tank; Item 19. The concentrating device according to item 18.

[20] a draw solution tank and one or more forward osmosis membrane modules; The forward osmosis membrane module is composed of a semipermeable membrane, a space E for contacting one surface of the semipermeable membrane with a raw material liquid, and a space F for contacting the other surface of the semipermeable membrane with a draw liquid, a raw material liquid inlet port and a raw material liquid outlet port connected to the space E, and a guide liquid inlet port and a guide liquid outlet port connected to the space F, the raw material liquid inlet port and the raw material liquid outlet port are connected to the raw material liquid tank; The guiding liquid inlet port and the guiding liquid outlet port are connected to the guiding liquid tank. Item 20. The concentrating device according to item 18 or 19. [Effects of the Invention]

[0014] According to the present invention, it is possible to efficiently and effectively reduce the volatile solvent from a raw material liquid containing water, a volatile solvent, and a solute, using a small amount of absorption liquid. Furthermore, according to the present invention, it is possible to provide a concentration method (for example, a method for operating such a concentration system) and a concentration device related to such a concentration system. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing a configuration example of a concentration system according to one embodiment of the present invention. [Figure 2] 1 is a schematic diagram showing a configuration example of a concentration system according to one embodiment of the present invention. [Figure 3] 1 is a schematic diagram showing a configuration example of a concentration system according to one embodiment of the present invention. [Figure 4] 1 is a schematic diagram showing a configuration example of a concentration system according to one embodiment of the present invention. [Figure 5] FIG. 1 is a schematic diagram showing an example of the configuration of a concentration system, which is an embodiment of a comparative example of the present invention. [Figure 6] FIG. 2 is a schematic diagram showing a configuration example of a concentration membrane distillation module in one aspect of this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings, in which: FIG.

[0017] In the present specification, when a plurality of structures represented by the same symbol exist in the same formula, the structures may be independently selected and may be the same or different from each other, unless otherwise specified. When a plurality of structures represented by the same symbol exist in different formulas, the structures may be independently selected and may be the same or different from each other, unless otherwise specified.

[0018] In this specification, various measurements are carried out based on the methods described in the Examples unless otherwise specified. Furthermore, in this specification, the upper or lower limit value of a numerical range described in stages may be replaced with the corresponding upper or lower limit value of another numerical range described in stages, and may also be replaced with the corresponding value described in the examples. Furthermore, in this specification, the term "step" includes not only an independent step but also a step that cannot be clearly distinguished from other steps, as long as the function of the step is achieved. Similarly, in this specification, the term "means" includes not only an independent step but also a step that cannot be clearly distinguished from other steps, as long as the function of the means is achieved. In the contents shown in the drawings, scales, shapes and lengths may be exaggerated for greater clarity.

[0019] [First embodiment] [Concentration system] One aspect of this embodiment is a concentration system that reduces the concentration of a volatile solvent from a raw material liquid containing water, a volatile solvent, and a solute. Such a concentration system comprises: a concentrating means for increasing the concentration of the solute in the raw material liquid by bringing the raw material liquid into contact with an absorption liquid for transferring the volatile solvent from the raw material liquid via a hydrophobic porous membrane; and a regeneration means for continuously removing the volatile solvent that has migrated to the absorption liquid. According to one aspect of this embodiment, the concentrating means and the regenerating means are connected in series or in parallel in terms of the flow of the absorbing liquid.

[0020] According to this embodiment, the volatile solvent can be efficiently and effectively reduced from a raw material solution containing water, a volatile solvent, and a solute with a small amount of absorption liquid used. In particular, according to a preferred aspect of this embodiment, the concentration of the volatile solvent in the raw material solution can be further reduced. In this regard, according to this embodiment, heating and pressurization are not essential for reducing the concentration of the volatile solvent.

[0021] [Raw material liquid] <Water> The "water" contained in the raw material liquid includes cold water and hot water.

[0022] <Volatile solvent> The volatile solvent contained in the raw material liquid refers to a solvent having volatility, and in a preferred embodiment, the "volatile solvent" refers to a solvent whose saturated vapor pressure of the pure substance at 20°C is higher than that of water. The saturated vapor pressure of the volatile solvent at 20°C is preferably 2.5 kPa or higher, or 4.0 kPa or higher. When the vapor pressure of the volatile solvent alone is higher than that of water, it is easy to improve the efficiency of concentration in the concentration step. The saturated vapor pressure of the volatile solvent at 20°C is preferably 15 kPa or lower, 12 kPa or lower, 10 kPa or lower, or 9.0 kPa or lower.

[0023] The saturated vapor pressure of the volatile solvent at a temperature of 0° C. or higher and lower than 40° C. is preferably higher than the saturated vapor pressure of water, which makes it easier to improve the efficiency of concentration in the concentration step.

[0024] Specifically, the volatile solvent preferably includes at least one selected from the group consisting of acetonitrile, ethanol, methanol, 2-propanol (isopropyl alcohol), 1-propanol (normal propyl alcohol), 1-butanol (1-butyl alcohol), isobutanol (2-butyl alcohol), t-butyl alcohol, tetrahydrofuran, acetic acid, and trifluoroacetic acid. More preferably, the volatile solvent includes at least one selected from the group consisting of acetonitrile, methanol, ethanol, 1-propanol, and 2-propanol.

[0025] The solute contained in the raw material solution is a non-volatile substance that is soluble in water and a volatile solvent. The solute may include, for example, at least one selected from the group consisting of inorganic salts, amino acids, peptides, nucleic acids, and sugars. In addition, non-volatile organic compounds other than those exemplified above can also be used as the solute.

[0026] <Absorbent> The absorption liquid refers to a liquid for transferring a volatile solvent from a raw liquid. When the absorption liquid is referred to as a liquid for "absorbing" a volatile solvent from a raw liquid, such "absorption" may be interpreted as the above-mentioned "transfer." Here, the absorption liquid is sufficient as long as it can transfer at least a portion of the volatile solvent from the raw material liquid, and is not necessarily required to have the property of being able to transfer all of the volatile solvent from the raw material liquid.

[0027] The main component of the absorption liquid preferably has a higher boiling point than the volatile solvent and a low vapor pressure as a pure substance, such as water, glycerin, polyethylene glycol, and polypropylene glycol. More preferably, the main component of the absorption liquid is water. The main component referred to here refers to, for example, the component whose mass proportion is the largest in the absorption liquid.

[0028] The absorption liquid may contain a volatile solvent and a solute. The concentration of the volatile solvent in the absorption liquid is preferably 30% by mass or less or less than 30% by mass. A concentration of the volatile solvent in the absorption liquid of 30% by mass or less or less than 30% by mass can easily prevent the interfacial tension of the absorption liquid from decreasing, thereby preventing the hydrophobic porous membrane from becoming wet and the absorption liquid from permeating through to the other side of the membrane as a liquid. The concentration of the volatile solvent in the absorption liquid may be greater than 0. Furthermore, a concentration at which the molar ratio of the volatile solvent contained in the absorption liquid and the absorption liquid components is "volatile solvent / absorption liquid ≧ 2" at the vapor-liquid equilibrium at the operating temperature is preferred. If regeneration is performed in the regeneration step when the volatile solvent concentration in the absorption liquid is low, the proportion of the absorption liquid in the components obtained as vapor tends to increase, which can easily reduce regeneration efficiency. In other words, the total amount of latent heat required to remove a certain amount of volatile solvent increases, and in some cases, additional absorption liquid may need to be added.

[0029] The interfacial tension of the absorbing liquid is preferably 25 mN / m or more. More preferably, the interfacial tension of the absorbing liquid is 30 mN / m or more, 33 mN / m or more, 35 mN / m or more, 37 mN / m or more, 40 mN / m or more, 45 mN / m or more, or 50 mN / m or more. If the interfacial tension of the absorbing liquid is 25 mN / m or more, it is easy to prevent the hydrophobic porous membrane from becoming wet, and therefore it is easy to regenerate the absorbing liquid.

[0030] The viscosity of the absorbing solution is preferably 1000 mPa·s or less. More preferably, the viscosity of the absorbing solution is 700 Pa·s or less, 500 Pa·s or less, 300 Pa·s or less, 200 Pa·s or less, 150 Pa·s or less, 100 Pa·s or less, 50 Pa·s or less, or 25 mPa·s or less. A viscosity of 1000 mPa·s or less helps to avoid large liquid transport pressure losses when the absorbing solution is transported through the hydrophobic porous membrane. Large liquid transport pressure losses increase the transmembrane pressure difference across the hydrophobic porous membrane, resulting in a wetted hydrophobic porous membrane. This can result in liquid permeation through the membrane, making it impossible to regenerate the absorbing solution. Furthermore, a high viscosity of the absorbing solution tends to decrease the diffusion rate of the absorbing solution near the membrane surface, which increases the concentration of volatile solvents in the absorbing solution near the membrane surface. This, in turn, tends to reduce the vapor pressure difference of the volatile solvent across the membrane. As a result, the vapor transport rate may decrease and may also lead to wetting of the hydrophobic porous membrane.

[0031] [Concentration means] The concentrating means increases the concentration of the solute in the raw material liquid by bringing the raw material liquid into contact with an absorption liquid for transferring the volatile solvent from the raw material liquid via a hydrophobic porous membrane. That is, the concentrating means has such a hydrophobic porous membrane.

[0032] <Hydrophobic porous membrane> The hydrophobic porous membrane has pores through which gas (in one embodiment, vapor) can pass. In a system using a non-porous membrane with substantially no pores, the membrane tends to act as a pervaporation membrane by a solution-diffusion mechanism, and in this case, the membrane often allows volatile solvents to pass through. Pervaporation membranes generally have an extremely slow vapor permeation rate. Therefore, a porous membrane through which membrane distillation can proceed is required, rather than a pervaporation membrane.

[0033] The hydrophobic porous membrane preferably has an average pore size of 0.1 μm or more and / or a maximum pore size of 0.5 μm or less. The maximum pore size can be determined by the bubble point method, and the average pore size can be determined by measuring the pore size distribution using a porometer.

[0034] The hydrophobic porous membrane preferably has a property of being difficult to wet with liquids with low surface tension, for example, water repellency, which repels liquid. The water repellency referred to here can be evaluated by the pressure (liquid entry pressure, LEP) at which the membrane becomes wet when a predetermined test liquid is sealed in a membrane distillation module composed of the hydrophobic porous membrane. In this embodiment, when the test liquid is a 20% by mass ethanol (EtOH) aqueous solution, the pressure (LEP) at which leakage occurs is preferably 100 kPa or more, more preferably 150 kPa or more, 160 kPa or more, 170 kPa or more, 180 kPa or more, 190 kPa or more, or 200 kPa or more.

[0035] To further improve the hydrophobicity of the hydrophobic porous membrane, a portion of the hydrophobic porous membrane may be coated with a water-repellent polymer. The water-repellent polymer may be, for example, a polymer having a hydrophobic structure. Examples of the hydrophobic structure include a non-polar backbone and a low-polarity backbone. Examples of the non-polar group and the low-polarity backbone include a hydrocarbon backbone and a siloxane backbone.

[0036] Examples of this type of water-repellent polymer include polymers having siloxane bonds and fluorine atom-containing polymers, and more specifically, the following may be mentioned: (A) Polymers having siloxane bonds, such as dimethyl silicone gel, methylphenyl silicone gel, reactive modified silicone gels having organic functional groups (amino groups, fluoroalkyl groups, etc.), silicone polymers that form crosslinked structures by reacting with silane coupling agents, and polymer gels that are crosslinked products of these. (a) Fluorine atom-containing polymers are polymers having fluorine atom-containing groups in their side chains, where the fluorine atom-containing groups are (per)fluoroalkyl groups, (per)fluoropolyether groups, alkylsilyl groups, fluorosilyl groups, and the like.

[0037] In particular, the hydrophobic polymer is preferably a polymer of a (meth)acrylate monomer and / or a vinyl monomer having a (per)fluoroalkyl group with 1 to 12 carbon atoms and / or a (per)fluoropolyether group.

[0038] In addition, examples of this type of coating method include: (A) A method in which a porous membrane is impregnated with a solution containing an aqueous polymer, and then the porous membrane is removed from the solution and air-dried; (a) A method in which a water-repellent polymer solution is passed through a membrane module containing a porous membrane to wet the porous membrane with the water-repellent polymer, and then the membrane module is dried; etc.

[0039] The thickness of the hydrophobic porous membrane is the permeation resistance of the gas passing through it, and is therefore preferably 1000 μm or less, more preferably 500 μm or less, 400 μm or less, 300 μm or less, 250 μm or less, 200 μm or less, 150 μm or less, or 100 μm or less. On the other hand, if the thickness of the hydrophobic porous membrane is 100 μm or more, it is easy to prevent the membrane from being damaged by the liquid feeding pressure and the transmembrane pressure difference due to reduced pressure in the regeneration step.

[0040] The material of the hydrophobic porous membrane preferably contains at least one selected from the group consisting of polysulfone, polyethersulfone, polyacrylonitrile, polyethyleneimide, polyvinylidene fluoride, polytetrafluoroethylene, copolymer of tetrafluoroethylene and ethylene (ETFE), copolymer of ethylene and chlorotrifluoroethylene, polyethylene, polypropylene, polyamide, polyetheretherketone, polymers having a perfluoroalkyl group, and polysiloxane. More preferably, the material of the hydrophobic porous membrane includes at least one selected from the group consisting of polyvinylidene fluoride, polytetrafluoroethylene, a copolymer of tetrafluoroethylene and ethylene (ETFE), a copolymer of ethylene and chlorotrifluoroethylene, polyethylene, polypropylene, a polymer having a perfluoroalkyl group, and polysiloxane, and even more preferably includes at least one selected from the group consisting of polyvinylidene fluoride, polytetrafluoroethylene, a copolymer of tetrafluoroethylene and ethylene (ETFE), a copolymer of ethylene and chlorotrifluoroethylene, and a polymer having a perfluoroalkyl group. The hydrophobic porous membrane may be supported by coating or chemical bonding. The hydrophobic porous membrane may be in the form of a flat membrane or a hollow fiber, and is preferably in the form of a hollow fiber.

[0041] [Forward osmosis membrane module] It is preferable that the concentration system further includes a draw solution tank and one or more forward osmosis membrane modules. In a preferred aspect of this embodiment, a semipermeable membrane using a forward osmosis membrane system is further included in parallel with the concentration means (the first hydrophobic porous membrane using a membrane distillation system). This makes it easier to achieve the effects of this embodiment. Here, known forward osmosis membrane modules, semipermeable membranes, and draw liquids may be used.

[0042] When the concentration system includes a forward osmosis membrane module, a circulation line for the draw solution is configured including the forward osmosis membrane module, as described below. The circulation line for the draw solution may include sensors (e.g., a concentration sensor, a temperature sensor, a flow rate sensor, a mass sensor, etc.) as described below.

[0043] [Reproduction means] The regeneration means continuously removes the volatile solvent that has migrated to the absorption liquid. According to one aspect of this embodiment, the concentrating means and the regenerating means are connected in series or in parallel with respect to the flow of the absorption liquid.

[0044] When the hydrophobic porous membrane in the concentration means is referred to as a first hydrophobic porous membrane, it is preferable that the regeneration means has a second hydrophobic porous membrane using a membrane distillation method. Furthermore, in this case, it is preferable that the membrane distillation method is a reduced-pressure membrane distillation method. This facilitates operation without generating a transmembrane pressure difference across the first hydrophobic porous membrane, making it easier to achieve the effects of this embodiment. An undesirable example would be the case where the absorption liquid is directly distilled under reduced pressure. When the absorption liquid is reduced in pressure, a pressure difference occurs between the feed liquid side and the absorption liquid side of the first hydrophobic porous membrane, which increases the transmembrane pressure difference and may lead to wetting of the hydrophobic porous membrane. On the other hand, when the absorption liquid is regenerated using a reduced-pressure membrane distillation method using a second hydrophobic porous membrane, the decompression treatment is performed via the second hydrophobic porous membrane, making it difficult for a transmembrane pressure difference across the first hydrophobic porous membrane due to the decompression treatment.

[0045] The configuration of the hydrophobic porous membrane (second hydrophobic porous membrane) in the regeneration means may be the same as the configuration of the hydrophobic porous membrane (first hydrophobic porous membrane) in the concentration means, or they may be different from each other. For the hydrophobic porous membrane in the regeneration means, please refer to the section on hydrophobic porous membrane in the concentration means. When a reduced pressure membrane distillation method is used as the regeneration means, the second hydrophobic porous membrane is preferably operated under a high transmembrane pressure difference, since one side of the membrane is in contact with the absorption liquid and the other side of the membrane is subjected to reduced pressure treatment. The absorption liquid has a lower concentration of volatile solvent than the raw material liquid, but for more stable operation, it is preferable that the second hydrophobic porous membrane has a higher water repellency. Therefore, the second hydrophobic porous membrane is designed to be less likely to become wet, i.e., to efficiently remove the volatile solvent. The leakage pressure (LEP) when the test liquid is a 20% by mass ethanol aqueous solution is 150 kPa or more. The maximum pore size is less than 0.5 μm, and The average pore size is 0.1 μm or more. is preferred.

[0046] It is preferable to reduce the concentration of a volatile solvent having an octanol / water partition coefficient (log Kow) of 1 or less by the regeneration means. This makes it easier to achieve the effects of this embodiment. If a solvent having an octanol / water partition coefficient greater than 1, such as a hydrophobic volatile solvent, is used, the volatile solvent and the main components of the absorbing liquid are likely to separate in the absorbing liquid, and in this case, the volatile solvent concentration may become extremely high locally. Because volatile solvents generally have low interfacial tension, contact of a volatile solvent with low interfacial tension with the hydrophobic porous membrane may cause wetting of the hydrophobic porous membrane.

[0047] Regarding the regeneration means, "continuously removing the volatile solvent that has migrated to the absorption liquid" corresponds to this if the volatile solvent that has migrated to the absorption liquid can be continuously removed, and therefore corresponds to this if the absorption liquid to which the volatile solvent has been migrated can be continuously passed through the regeneration means. Even if the concentration system is operated intermittently, this also corresponds to the above if the absorption liquid can be continuously passed through the regeneration means over the predetermined period of operation. Also, for example, intermittent operation of the regeneration means, such as continuously operating the concentration means and continuously passing water through the regeneration means and reducing the pressure only when the absorption liquid reaches a predetermined concentration range, also corresponds to this. Such an embodiment is easily realized when the concentration system has at least one of a cold trap and a vacuum pump. That is, the embodiment having at least one of a cold trap and a vacuum pump is one of the preferred embodiments of the concentration system.

[0048] [Concentration sensor] The concentration system may include a concentration sensor for detecting the concentration of the volatile solvent in the absorption liquid, which allows the operation of the concentration system to be feedback-controlled based on the result of the concentration sensor.

[0049] The concentration sensor may be configured by combining one or more of a refractometer, a density meter, a gas chromatograph, a near-infrared spectrometer, an ultrasonic densitometer, an IR spectrometer, and a Raman spectrometer, for example. The concentration sensor may be incorporated in-line in the absorption liquid supply line, or may be disposed in the absorption liquid tank.

[0050] [Temperature sensor] The concentration system may have a temperature sensor for detecting the temperature of the feed liquid (temperature sensor for the feed liquid) and / or a temperature sensor for detecting the temperature of the absorption liquid (temperature sensor for the absorption liquid). By having these temperature sensors, the concentration system can perform feedback control of the operation of the system based on the results of the temperature sensors.

[0051] The temperature sensor may be of any type as long as it can acquire the desired temperature information, but for example, it may be configured by combining one or two of a thermocouple and a resistance temperature detector. The temperature sensor may be incorporated in-line into the feed line for the raw material liquid and into the feed line for the absorption liquid. The temperature sensor is The separator may be disposed on both the inlet side and the outlet side of the raw material liquid to the concentration means, The absorption liquid may be supplied to the concentration means on both the inlet side and the outlet side thereof. The separator may be disposed on both the inlet side and the outlet side of the absorption liquid to the regenerating means.

[0052] [Flow sensor] The concentration system may include a flow rate sensor for detecting the flow rate of the absorption liquid flowing through the regeneration means, and by including such a flow rate sensor, the operation of the concentration system can be feedback-controlled based on the results of the flow rate sensor.

[0053] The flow rate sensor may be of any type as long as it can acquire the desired flow rate information, and may be configured by combining one or more of known types such as Coriolis type, vortex type, ultrasonic type, thermal type, float type, etc. The flow rate sensor may be incorporated in-line in the feed line for the raw material liquid and in the feed line for the absorption liquid.

[0054] Here, the "flow rate of the absorbing liquid flowing through the regenerating means" is not limited to a value measured for the absorbing liquid in the space in the regenerating means, but also includes a value measured for the absorbing liquid flowing through a liquid supply line for the absorbing liquid introduced into the regenerating means.

[0055] [Mass sensor] The concentration system may have a mass sensor for detecting the mass of the raw material liquid (mass sensor for raw material liquid) and / or a mass sensor for detecting the mass of the absorption liquid (mass sensor for absorption liquid). By having these mass sensors, the concentration system can perform feedback control of the operation of the system based on the results of the mass sensors.

[0056] The mass sensor can be of any type as long as it can acquire the desired mass information, but it can be configured by combining one or more known types such as a platform scale, a load converter (load cell), etc. A mass sensor may be provided for the feed liquid and for the absorption liquid, respectively.

[0057] [Location relationship between concentration means and regeneration means] The regeneration means may be arranged in parallel with the concentration means or in series with respect to the absorption liquid tank (for example, the absorption liquid tank 20 shown in FIGS. 1 to 3). Preferably, the concentrating means and the regenerating means are arranged in series, whereby the absorbing liquid can be sent to both the concentrating means and the regenerating means using a common liquid sending pump from the absorbing liquid tank.

[0058] Here, by arranging the concentrating means and the regenerating means in series and providing the regenerating means after the concentrating means, the absorption liquid supplied to the regenerating means will be in a state in which it has received the volatile solvent in the concentrating means (i.e., in a state in which it has a relatively high concentration of volatile solvent while not excessively wetting the hydrophobic porous membrane in the concentrating means), and therefore the absorption liquid may be regenerated more effectively.

[0059] Furthermore, by connecting the concentrating means and the regenerating means in series and providing the regenerating means upstream of the concentrating means, the absorbing liquid cooled by the latent heat removed from the absorbing liquid by the regenerating means is supplied to the concentrating means. When the absorbing liquid is cooled more than the feed liquid, water also tends to migrate to the absorbing liquid. In the regenerating means, the vapors of the volatile solvent and water migrate to the cooling trap according to vapor-liquid equilibrium, so supplying water to the absorbing liquid is preferable for continuous operation, but depending on the design of the operating conditions, the water to be supplied may be supplied from the concentrating means. Furthermore, in the concentration means, sensible heat transfer occurs via the membrane, and a portion of the removed latent heat is supplied from the feed liquid. Therefore, it is easy to configure an embodiment in which a heat exchanger is not required in the regeneration means.

[0060] [Cold trap (volatile solvent condensation trap)] The cold trap can condense the gas (vapor) that has permeated the hydrophobic porous membrane (second hydrophobic porous membrane) in the regeneration means. The concentration system can have one or more cold traps, preferably two or more, which makes it easier to operate the system continuously. The cold traps may be arranged in parallel or in series, and preferably two or more cold traps are arranged in parallel.

[0061] In a preferred embodiment, when both a cold trap and a vacuum pump are provided, the cold trap is disposed between the hydrophobic porous membrane (second hydrophobic porous membrane) in the regeneration means and the vacuum pump, which facilitates condensation of the gas (vapor) drawn by the vacuum pump. Here, if the concentration system further includes a tank (recovered solvent tank) for storing the solvent recovered by condensing the gas (vapor) (also referred to as "recovered solvent"), it is preferable to further provide a cooling trap so that it can be applied to such a condensation tank.

[0062] The cold trap may be configured integrally with the regeneration means or may be configured separately. When the concentration system has multiple cold traps, some of the cold traps may be configured integrally with the regeneration means or may be configured separately.

[0063] The cold trap contains a refrigerant, which is brought into contact with the gas (vapor). The temperature of the refrigerant is preferably lower than the temperature of the absorption liquid in the regeneration means. More preferably, the temperature of the refrigerant is 0°C or lower, -10°C or lower, -20°C or lower, -30°C or lower, -40°C or lower, -50°C or lower, -60°C or lower, -70°C or lower, -80°C or lower, -90°C or lower, -100°C or lower, -150°C or lower, or -170°C or lower. More preferably, the upper limit of the refrigerant temperature is -30°C or lower, from the viewpoint of suppressing volatilization from the condensed recovered solvent, and even more preferably, it is lower than the freezing point of the condensed recovered solvent.

[0064] [Decompression pump] The vacuum pump can effectively recover the gas (vapor) generated in the regenerating means by negative pressure, and it is preferable that the vacuum pump has a predetermined exhaust capacity. The decompression pump may be configured integrally with the regeneration means, or may be configured separately.

[0065] [Concentrator] Another aspect of this embodiment is a concentrating device, which can easily realize the above-mentioned concentration system. The control of the concentrating device is realized by executing a program by a microcomputer installed in the concentration system, and the processing of information transmitted from various sensors is also performed by the microcomputer.

[0066] In the concentrator, a first line configuration in which the concentration means and the regeneration means are arranged in parallel; A second line configuration in which the inlet side and outlet side of the concentration means and the inlet side and outlet side of the regeneration means are arranged in series in this order in the flow of the absorption liquid; and a third line configuration in which the inlet side and outlet side of the regenerating means and the inlet side and outlet side of the concentrating means are arranged in series in this order in terms of the flow of the absorption liquid; At least one of the above line configurations may be adopted.

[0067] <Various configurations> Figures 1 to 3 are schematic diagrams for explaining the general configuration of a concentrating apparatus, in which Figure 1 shows the general configuration of a concentrating apparatus having a first line configuration, Figure 2 shows the general configuration of a concentrating apparatus having a second line configuration, and Figure 3 shows the general configuration of a concentrating apparatus having a third line configuration. In each figure, FS indicates the raw liquid, and the arrow accompanying FS indicates the flow direction of the raw liquid. CW indicates the absorption liquid, and the arrow accompanying CW indicates the flow direction of the absorption liquid.

[0068] As shown in the figure, in any line configuration, the concentrators (501, 502, 503) a raw material liquid tank 10 (FS tank) for storing the raw material liquid; an absorption liquid tank 20 (CW tank) for storing the absorption liquid; at least one concentration membrane distillation module 110 (DCMD); at least one regenerative membrane distillation module 210 (VMD); at least one cold trap 30 in contact with the refrigerant; and a pressure reducing pump 40.

[0069] where: The concentration membrane distillation module 110 includes: The hydrophobic porous membrane (12) (first hydrophobic porous membrane) is composed of a space (12A) for contacting one side of the hydrophobic porous membrane (12) with the raw material liquid, and a space (12B) for contacting the other side of the hydrophobic porous membrane (12) with the absorption liquid, A raw material liquid injection port 12A connected to the space 12A IN and raw material liquid discharge port 12A OUT and an absorption liquid injection port 12B connected to the space 12B. IN and absorbent discharge port 12B OUT It has the following features.

[0070] In addition, the regeneration membrane distillation module 210 is The hydrophobic porous membrane 22 (second hydrophobic porous membrane) is composed of a space 22C for contacting one side of the hydrophobic porous membrane 22 with the absorption liquid, and a space 22D for reducing the pressure on the other side of the hydrophobic porous membrane 22, An absorption liquid injection port 22C connected to the space 22C IN and absorbent discharge port 22C OUT and a decompression port 22D connected to the space 22D. PRE has at least one

[0071] For the raw liquid stored in the raw liquid tank 10 and the absorption liquid stored in the absorption liquid tank 20, the items in the [Concentration System] may be referred to. The raw material liquid tank 10 and the absorption liquid tank 20 may have known configurations.

[0072] The concentration membrane distillation module 110 (DCMD) may correspond to the concentration means in the [concentration system], and the regeneration membrane distillation module 210 (VMD) may correspond to the regeneration means in the [concentration system].

[0073] The cold trap 30 and the vacuum pump 40 may be referred to in the items on the cold trap and the vacuum pump in the [Concentration System].

[0074] Here, the concentrators (501, 502, 503) are connected to the raw material liquid injection port 12A. IN , and between the raw material liquid tank 10 and the raw material liquid discharge port 12A OUT and the raw material liquid tank 10. This embodiment is one of the preferred embodiments of the concentrating apparatus. As described above, this embodiment is easily realized in an embodiment in which the concentration membrane distillation module 110 and the regeneration membrane distillation module 210 are connected in series and the regeneration membrane distillation module 210 is provided upstream of the concentration membrane distillation module 110 (i.e., the concentrating apparatus 503 shown in FIG. 3).

[0075] <Sensors> (concentration sensor) The concentrators (501, 502, 503) each have a concentration sensor 61 for detecting the concentration of the volatile solvent in the absorption liquid in the absorption liquid feed line, specifically, in the feed line on the injection side of the concentration membrane distillation module 110 and the feed line on the injection side of the regeneration membrane distillation module 210. The concentration system can detect the concentration of the volatile solvent in the absorption liquid based on the information obtained by the concentration sensor 61.

[0076] (Temperature sensor) The concentrating devices (501, 502, 503) have a temperature sensor 62 (temperature sensor for raw liquid) for detecting the temperature of the raw liquid in the liquid supply line for the raw liquid, specifically in the liquid supply line on the injection side of the concentration membrane distillation module 110. The concentrators (501, 502, 503) also have temperature sensors 63 (temperature sensors for the absorption liquid) for detecting the temperature of the absorption liquid in the liquid supply lines for the absorption liquid, specifically, in the liquid supply lines on the injection side of the concentration membrane distillation module 110 and on the injection side of the regeneration membrane distillation module 210. Furthermore, the concentrators (501, 502, 503) have the temperature sensor 62 in the liquid transfer line on the discharge side of the concentration membrane distillation module 110. The concentrators (501, 502, 503) also have the temperature sensors 63 on the liquid feed lines on the injection side of the concentration membrane distillation module 110 and on the liquid feed lines on the injection side of the regeneration membrane distillation module 210, respectively. As described above, in this embodiment, these temperature sensors are arranged on both the inlet side and the outlet side of each module, which makes it easier to perform feedback control based on temperature information of the fluid flowing through each module. The concentration system can detect the temperature of the feed liquid and / or the absorption liquid based on the information obtained by the temperature sensors 62 and 63.

[0077] (flow sensor) The concentrating devices (501, 502, 503) each have a flow sensor 64 for detecting the flow rate of the absorbing liquid flowing through the regeneration means, in the liquid supply line for the absorbing liquid, specifically, in the liquid supply line on the injection side of the concentration membrane distillation module 110 and the liquid supply line on the injection side of the regeneration membrane distillation module 210. Based on the information obtained by the flow rate sensor 64, the concentration system can detect the flow rate of the absorption liquid introduced into the regeneration means.

[0078] (Mass sensor) The concentrating devices (501, 502, 503) have a mass sensor 65 (mass sensor for raw material liquid) for detecting the mass of the raw material liquid. Here, the mass sensor 65 for raw material liquid is configured as a platform balance, and the raw material liquid tank 10 is placed on the platform balance. The concentrators (501, 502, 503) also have a mass sensor 66 (mass sensor for the absorbing liquid) for detecting the mass of the absorbing liquid. Here, the mass sensor 66 for the absorbing liquid is configured as a platform balance, and the absorbing liquid tank 20 is disposed on the platform balance. The concentration system can detect the mass of the raw liquid and / or the absorption liquid based on the information obtained by the mass sensors 65 and 66.

[0079] [First line configuration] In the concentrator 501 having the first line configuration, The raw material liquid injection port 12A IN , and the raw material liquid discharge port 12A OUT is connected to the raw material liquid tank 10, The absorption liquid injection port 22C IN and the absorption liquid discharge port 22C. OUT is connected to the absorption liquid tank 20, The pressure reduction port 22D PRE The pressure reducing pump 40 and the recovered solvent tank 50 are connected via the cooling trap 30 .

[0080] In the concentrator 501, the raw material liquid stored in the raw material liquid tank 10 is introduced into the raw material liquid injection port 12A. IN The raw material liquid is introduced into the space 12A through the raw material liquid discharge port 12A. OUT The raw material liquid is collected in the raw material liquid tank 10 through the filtration. That is, the raw material liquid is supplied to the raw material liquid tank 10, the raw material liquid injection port 12A, IN , space 12A, and raw material liquid discharge port 12A OUT The raw material liquid is circulated in this order (circulation line).

[0081] At this time, the absorbing liquid stored in the absorbing liquid tank 20 is injected into the absorbing liquid injection port 12B IN and the absorbent is introduced into the space 12B through the absorption liquid discharge port 12B. OUT The absorbent liquid is collected in the absorption liquid tank 20 through the filter. The absorption liquid stored in the absorption liquid tank 20 is injected through the absorption liquid injection port 22C. IN and the absorbent is introduced into the space 22C through the absorption liquid discharge port 22C. OUT The absorbent liquid is collected in the absorption liquid tank 20 through the filter. That is, the absorption liquid is supplied to the absorption liquid tank 20, the absorption liquid injection port 12B IN , space 12B, and absorption liquid discharge port 12B OUT The above are circulated in this order (first circulation line for the absorption liquid). The absorption liquid is supplied to the absorption liquid tank 20, the absorption liquid injection port 22C, IN , space 22C, and absorption liquid discharge port 22C OUT The absorption liquid is also circulated in this order (second circulation line for the absorption liquid).

[0082] The concentrator 501 is provided with a liquid feed pump in each of the circulation lines for the raw liquid and the absorption liquid, which makes it easy to circulate the raw liquid and the absorption liquid in an appropriate manner. The concentrator 501 includes a raw material liquid tank 10 and a raw material liquid injection port 12A. IN The liquid supply line connecting the absorbent tank 20 and the absorbent injection port 12B has a liquid supply pump 13. INa liquid supply line connecting the absorption liquid tank 20 and the absorption liquid injection port 22C; IN and a liquid feed line connecting the first and second absorbing liquids, respectively, and liquid feed pumps 23, 24. However, the positions of the liquid feed pumps are not limited to this example, depending on the viewpoint of suitably circulating the raw material liquid and the second absorbing liquid. For example, here, the first absorbing liquid circulation line and the second absorbing liquid circulation line are each provided with liquid feed pumps 23, 24, but it is also possible to provide only one of the liquid feed pumps 23, 24, and have the first absorbing liquid circulation line and the second absorbing liquid circulation line share the same liquid feed pump.

[0083] [Second line configuration] In the concentrator 502 having the second line configuration, The raw material liquid injection port 12A IN , and the raw material liquid discharge port 12A OUT is connected to the raw material liquid tank 10, The absorption liquid discharge port 12B of the space 12B OUT and the absorption liquid injection port 22C of the space 22C. IN and are connected in series, The absorption liquid injection port 12B of the space 12B IN and the absorption liquid discharge port 22C of the space 22C. OUT and is connected to the absorption liquid tank 20, The pressure reduction port 22D PRE The pressure reducing pump 40 and the recovered solvent tank 50 are connected via the cooling trap 30 .

[0084] In the concentrator 502, the raw material liquid stored in the raw material liquid tank 10 is fed to the raw material liquid injection port 12A. IN The raw material liquid is introduced into the space 12A through the raw material liquid discharge port 12A. OUT The raw material liquid is collected in the raw material liquid tank 10 through the filtration. That is, the raw material liquid is supplied to the raw material liquid tank 10, the raw material liquid injection port 12A, IN , space 12A, and raw material liquid discharge port 12A OUTThe raw material liquid is circulated in this order (circulation line).

[0085] At this time, the absorbing liquid stored in the absorbing liquid tank 20 is injected into the absorbing liquid injection port 12B IN and the absorbent is introduced into the space 12B through the absorption liquid discharge port 12B. OUT Here, the absorbent liquid is discharged through the absorption liquid discharge port 12B OUT and absorption liquid injection port 22C IN and are connected in series as a liquid passage line, so that the absorption liquid discharge port 12B OUT The absorbent discharged through the absorbent injection port 22C is IN The absorption liquid is then introduced into the space 22C through the absorption liquid discharge port 22C. OUT The absorbent liquid is collected in the absorption liquid tank 20 through the filter. That is, the absorption liquid is supplied to the absorption liquid tank 20, the absorption liquid injection port 12B IN , space 12B, absorption liquid discharge port 12B OUT , absorption liquid injection port 22C IN , space 22C, and absorption liquid discharge port 22C OUT The absorbent is circulated in this order (absorption liquid circulation line).

[0086] The concentrator 502 is provided with a liquid feed pump in each of the circulation lines for the raw liquid and the absorption liquid, which makes it easy to circulate the raw liquid and the absorption liquid in an appropriate manner. The concentrator 502 includes a raw material liquid tank 10 and a raw material liquid injection port 12A. IN The liquid supply line connecting the absorbent tank 20 and the absorbent injection port 12B has a liquid supply pump 13. IN However, the position of the liquid feed pump is not limited to this example, depending on the viewpoint of suitably circulating the raw material liquid and the absorption liquid.

[0087] In the concentrating device 502, the absorption liquid concentrating means (membrane distillation module 110 for concentration) and the regeneration means (membrane distillation module 210 for regeneration) are arranged in series in this order in terms of the flow of the absorption liquid. In this case, it is easy to continuously reduce the volatile solvent that has migrated into the absorption liquid discharged from the concentration means in the regeneration means.

[0088] [Third line configuration] In the concentrator 503 having the third line configuration, The raw material liquid injection port 12A IN , and the raw material liquid discharge port 12A OUT is connected to the raw material liquid tank 10, The absorption liquid discharge port 22C of the space 22C OUT and the absorption liquid injection port 12B of the space 12B. IN and are connected in series, The absorption liquid injection port 22C of the space 22C IN and the absorption liquid discharge port 12B of the space 12B. OUT and is connected to the absorption liquid tank 20, The pressure reduction port 22D PRE The pressure reducing pump 40 and the recovered solvent tank 50 are connected via the cooling trap 30 .

[0089] In the concentrator 503, the raw material liquid stored in the raw material liquid tank 10 is introduced into the raw material liquid injection port 12A. IN The raw material liquid is introduced into the space 12A through the raw material liquid discharge port 12A. OUT The raw material liquid is collected in the raw material liquid tank 10 through the filtration. That is, the raw material liquid is supplied to the raw material liquid tank 10, the raw material liquid injection port 12A, IN , space 12A, and raw material liquid discharge port 12A OUT The raw material liquid is circulated in this order (circulation line).

[0090] At this time, the absorbing liquid stored in the absorbing liquid tank 20 is injected into the absorbing liquid injection port 22C. INand the absorbent is introduced into the space 22C through the absorption liquid discharge port 22C. OUT Here, the absorbent liquid is discharged through the absorption liquid discharge port 22C OUT and absorption liquid injection port 12B IN and are connected in series as a liquid passage line, so that the absorption liquid discharge port 22C OUT The absorbent discharged through the absorbent injection port 12B is IN The absorption liquid is then introduced into the space 12B through the absorption liquid discharge port 12B. OUT The absorbent liquid is collected in the absorption liquid tank 20 through the filter. That is, the absorption liquid is supplied to the absorption liquid tank 20, the absorption liquid injection port 22C IN , space 22C, absorption liquid discharge port 22C OUT , absorption liquid injection port 12B IN , space 12B, and absorption liquid discharge port 12B OUT The absorbent is circulated in this order (absorption liquid circulation line).

[0091] The concentrator 503 is provided with a liquid feed pump in each of the circulation lines for the raw liquid and the absorption liquid, which makes it easy to circulate the raw liquid and the absorption liquid in an appropriate manner. The concentrator 503 in this example is connected to the raw material liquid tank 10 and the raw material liquid injection port 12A. IN The liquid supply line connecting the absorbent tank 20 and the absorbent injection port 22C has a liquid supply pump 13. IN The liquid feed line connecting the above has a liquid feed pump 24. However, the position of the liquid feed pump is not limited to this example, depending on the viewpoint of suitably circulating the raw material liquid and the absorption liquid.

[0092] In the concentrating device 503, a regeneration means (membrane distillation module for regeneration 210) and an absorption liquid concentration means (membrane distillation module for concentration 110) are arranged in series in this order in terms of the flow of the absorption liquid. In this case, the absorption liquid discharged from the regeneration means can be easily concentrated continuously in the concentration means.

[0093] [Concentration and regeneration] In the concentrating devices 501, 502, and 503, regardless of which line configuration is used, the raw liquid and the absorption liquid come into contact with each other through the hydrophobic porous membrane 12 (first hydrophobic porous membrane 12) in the concentration membrane distillation module 110, and at this time, the volatile solvent in the raw liquid can be transferred to the absorption liquid.

[0094] Furthermore, in the concentrators 501, 502, and 503, regardless of which line configuration they have, the volatile solvent in the absorption liquid can be recovered through the hydrophobic porous membrane 22 (second hydrophobic porous membrane 22) in the regeneration membrane distillation module 210.

[0095] [Mechanism for capturing recovered solvent] Regardless of the line configuration, the concentrators 501, 502, and 503 each have a trapping mechanism that effectively traps the recovered solvent. The trapping mechanism includes, for example, a vacuum pump 40, a cooling trap 30, and a recovered solvent tank 50.

[0096] The volatile solvent component contained in the absorption liquid is drawn as vapor from the space 22C through the hydrophobic porous membrane 22 (second hydrophobic porous membrane 22) to the space 22D by the negative pressure of the vacuum pump 40. The volatile solvent component drawn to the space 22D is vaporized through the vacuum port 22D. PRE The solvent is discharged from the tank 30, condensed, i.e., liquefied, in the cold trap 30, and then stored in the recovered solvent tank 50.

[0097] [Forward osmosis membrane module] Regardless of the line configuration, the concentrators 501, 502, and 503 may further include a draw solution tank and one or more forward osmosis membrane modules.

[0098] Fig. 4 is a schematic diagram for further illustrating the general configuration of the concentrating apparatus. In the figure, the circulation line for the absorbing liquid is not shown, but any of the circulation lines for the absorbing liquid shown in Figs. 1 to 3 can be used as the circulation line for the absorbing liquid. As shown, the concentrator 504 includes: The system further comprises a draw solution tank 70 and one or more forward osmosis membrane modules 710 (FO), The forward osmosis membrane module 710 is composed of a semipermeable membrane 72, a space 72E for one side of the semipermeable membrane 72 to come into contact with the raw material liquid, and a space 72F for the other side of the semipermeable membrane 72 to come into contact with the draw liquid.

[0099] Here, the concentrators 501, 502, and 503 are: A raw material liquid injection port 72E connected to the space 72E IN and raw material liquid discharge port 72E OUT and a guide liquid injection port 72F connected to the space 72F. IN and induction fluid discharge port 72F OUT and The raw material liquid injection port 72E IN and the raw material liquid discharge port 72E OUT is connected to the raw material liquid tank 10, The induction fluid injection port 72F IN and the induction liquid discharge port 72F OUT is connected to the draw liquid tank 70.

[0100] In the concentrator 504, similarly to the concentrators 501, 502, and 503, the raw material liquid is supplied from the raw material liquid tank 10, the raw material liquid injection port 12A, IN , space 12A, and raw material liquid discharge port 12A OUT The above are circulated in this order (first circulation line for raw material liquid).

[0101] In the concentrator 504, the raw material liquid stored in the raw material liquid tank 10 is fed to the raw material liquid injection port 72E. IN The raw material liquid is introduced into the space 72E through the OUT The raw material liquid is collected in the raw material liquid tank 10 through the filtration. That is, the raw material liquid is supplied to the raw material liquid tank 10, the raw material liquid injection port 72E IN , space 72E, and raw material liquid discharge port 72E OUT The above are circulated in this order (second circulation line for raw material liquid).

[0102] In the concentrator 504, the induced liquid stored in the induced liquid tank 70 is fed to the induced liquid injection port 72F. IN and the induction liquid is introduced into the space 72F through the induction liquid discharge port 72F. OUT The liquid is collected in the draw liquid tank 70 through the draw liquid tank 70. That is, the guiding liquid is supplied to the guiding liquid tank 70, the guiding liquid injection port 72F, IN , space 72F, and induction fluid discharge port 72F OUT The following are circulated in this order (circulation line for the induction liquid).

[0103] The concentrator 504 is provided with a liquid feed pump 73 in the circulation line for the deriving liquid, which facilitates the circulation of the deriving liquid in a suitable manner. The concentrator 504 here includes a draw solution tank 70 and a draw solution injection port 72F. IN A liquid sending pump 73 is provided on the liquid sending line connecting the above.

[0104] The concentrator 504, or a concentration system using the same, As in the first circulation line of the raw material liquid, in the second circulation line of the raw material liquid, A temperature sensor 62 (temperature sensor for raw material liquid) for detecting the temperature of the raw material liquid may have In this embodiment, the concentrating device 504 or the concentration system using the same can easily and suitably detect the temperature of the raw material liquid flowing through the second circulation line for the raw material liquid based on the information acquired by these sensors.

[0105] The concentrator 504, or a concentration system using the same, In the circulation line of the above-mentioned deriving liquid, A temperature sensor 68 (temperature sensor for the induced liquid) for detecting the temperature of the induced liquid may have In such an embodiment, the concentrating device 504 or a concentration system using the same can easily and suitably detect the temperature of the draw liquid flowing through the draw liquid circulation line based on information acquired by these sensors.

[0106] The temperature sensors 62 may be arranged on both the inlet side and the outlet side of the feedstock liquid to the concentration membrane distillation module 110, and the temperature sensors 68 may also be arranged on both the inlet side and the outlet side of the draw liquid to the forward osmosis membrane module 710. Feedback control of the concentration system may be performed based on information from the temperature sensors arranged on the inlet side and the outlet side of each module.

[0107] In addition, the concentrator 504 or the concentration system using the same is a mass sensor 67 (mass sensor for the guiding liquid) for detecting the mass of the guiding liquid; Here, the mass sensor 67 is configured as a platform balance, and the induction liquid tank 70 is disposed on the platform balance. In such an embodiment, the concentrator 504, or a concentration system utilizing the same, is likely to suitably detect the mass of the draw liquid based on information obtained by such a sensor.

[0108] [Second embodiment] [Concentration method] Another aspect of the present embodiment is a concentration method for reducing the concentration of a volatile solvent from a raw material liquid containing water, a volatile solvent, and a solute. Such a method may be treated as a method for operating the concentration system.

[0109] The method in this embodiment includes: a concentration step of increasing the concentration of the solute in the raw material liquid by bringing the raw material liquid into contact with an absorption liquid for transferring the volatile solvent from the raw material liquid via a hydrophobic porous membrane; a regeneration step of continuously removing the volatile solvent transferred to the absorption liquid; where: the regeneration step is a reduced pressure membrane distillation method using the hydrophobic porous membrane, In the reduced pressure membrane distillation method, the absolute pressure is reduced to a pressure lower than the saturated vapor pressure of the absorbing liquid. According to this method, the volatile solvent can be efficiently and effectively reduced from a raw material liquid containing water, a volatile solvent, and a solute, using a small amount of absorption liquid.

[0110] The concentration step can be suitably achieved by the concentration means described above, and therefore reference may be made to the section entitled "Concentration Means." The regeneration step can be suitably achieved by the regeneration means described above, and therefore, the item [Regeneration Means] may be referred to.

[0111] <Decompression level> In order to effectively remove vapor through the membrane, the pressure is reduced to a level lower than the saturated vapor pressure of the absorption liquid. Therefore, the degree of reduction in pressure of the hydrophobic porous membrane (second hydrophobic porous membrane) in the regeneration step is preferably 16 kPaA or less in absolute pressure. More preferably, the degree of reduction is 14 kPaA or less, 12 kPaA or less, 10 kPaA or less, 8 kPaA or less, 7 kPaA or less, 6 kPaA or less, 5 kPaA or less, 4 kPaA or less, 3 kPaA or less, or 2.5 kPaA or less in absolute pressure. However, when the main component of the absorption liquid is water, the absorption liquid is water itself immediately after the start of operation of the concentration system, and therefore, if the absolute pressure is reduced to a level lower than the saturated vapor pressure of water, the water is likely to volatilize. Therefore, it is more preferable to set the degree of pressure reduction to a pressure higher than the saturated vapor pressure of water at the operating temperature.

[0112] Generally, when reducing the volatile solvent by vacuum distillation, the absorption tank is also put into a reduced pressure state, and therefore the space in the concentrating means connected to the absorption tank is also put into a reduced pressure state, and in this case, the differential pressure between the raw material liquid and the absorption liquid via the membrane of the concentrating means becomes large.

[0113] In the concentration step, the transmembrane pressure difference applied to the hydrophobic porous membrane is preferably 50 kPa or less. More preferably, the transmembrane pressure difference is 30 kPa or less, 20 kPa or less, 15 kPa or less, 10 kPa or less, or 5 kPa or less. If the transmembrane pressure difference is large, the hydrophobic porous membrane may become wet.

[0114] If the absorbent tank were to be directly distilled under reduced pressure rather than using a reduced-pressure membrane distillation method, a transmembrane pressure difference would be applied to the membrane in the concentration process depending on the degree of vacuum, which would require a tank for reduced-pressure distillation separate from the absorbent tank and a separation between the absorbent tank and the tank for reduced-pressure distillation to prevent fluid from passing between them. On the other hand, in this embodiment, by applying the membrane distillation method, such separation is not necessary, and the absorbent tank can be maintained at normal pressure. As a result, the transmembrane pressure difference of the membrane in the concentration process can be kept small. In other words, operation with a simple device configuration is possible.

[0115] Here, in the reduced pressure membrane distillation method, The absolute pressure is reduced to a pressure that is greater than the saturated water vapor pressure and less than the saturated vapor pressure of the absorption liquid, The concentration of the volatile solvent in the absorption liquid is 30% by mass or less, the volatile solvent has an octanol / water partition coefficient (log Kow) of 1 or less; The saturated vapor pressure of the volatile solvent at 0°C or higher and lower than 40°C is higher than the saturated vapor pressure of water, and The saturated vapor pressure of the volatile solvent at 20° C. is preferably 10 kPa or less. This makes it easier to achieve the effects of this embodiment. In the reduced-pressure membrane distillation method, if it is possible to avoid a situation in which the saturated vapor pressure of the volatile solvent is too high, it is easy to prevent the volatile solvent that has been liquefied (or solidified) through the cooling trap from volatilizing again under reduced pressure, and thus to prevent such volatile solvent components from flowing into the reduced-pressure pump. In this case, it is easy to prevent situations such as impeded control of the reduced pressure of the reduced-pressure pump, a decrease in the performance of the reduced-pressure pump, or a breakdown of the reduced-pressure pump.

[0116] When the concentration system further includes a concentration sensor (e.g., concentration sensor 61 in FIGS. 1 to 3), It is preferable to feedback-control the degree of pressure reduction in the regenerating means (ie, the degree of pressure reduction in space D) according to the result of the concentration sensor. If the concentration of the volatile solvent in the absorption liquid becomes too high, the hydrophobic porous membrane becomes easily wetted during the concentration step and the regeneration step, and in this case, the concentration or regeneration function may not be performed. On the other hand, if the concentration of the volatile solvent becomes too low, it becomes difficult to remove the volatile solvent during the regeneration step, and in this case, the proportion of water that migrates to the cooling trap increases, resulting in increased energy loss.

[0117] Therefore, while monitoring the concentration of the volatile solvent in the absorption liquid with a concentration sensor, When the system determines that the concentration is within a predetermined reference range, a vacuum membrane distillation regeneration step is initiated; and When the system determines that the concentration is below the standard range, the pressure reduction is stopped or reduced. It is preferable to adopt such a control, which allows the absorbing liquid to be efficiently regenerated. The degree of decompression in the regenerating means (that is, the degree of decompression in space D) can be controlled by controlling the driving state of the decompression pump.

[0118] (Latent heat estimation) Here, the concentration system is The mass sensor (for example, mass sensors 65 and 66 in FIGS. 1 to 3), The temperature sensor (for example, the temperature sensors 62 and 63 in FIGS. 1 to 3), The flow sensor (for example, the flow sensor 64 in FIGS. 1 to 3), When further comprising at least one of: Such a concentration system comprises: It is preferable to calculate the mass of the volatile solvent transferred from the absorption liquid in the regeneration means based on information from the mass sensor, and further to estimate the latent heat of the volatilized fluid based on at least one piece of information obtained from the temperature sensor and the flow rate sensor, and control the degree of pressure reduction in the regeneration means.

[0119] For example, the latent heat of the fluid reduced in the regeneration process can be estimated based on at least one piece of information, such as the amount of liquid reduced in the regeneration process, the flow rate of the absorption liquid used in the regeneration process, the liquid temperature of the absorption liquid before and after the regeneration process, and the specific heat of the absorption liquid, or by combining two or more pieces of information. The specific heat of the absorbing liquid may be assumed to be equal to that of water when the concentration of the volatile solvent is sufficiently low. If the composition of the absorbing liquid is known from a concentration sensor, the specific heat may be derived from that information using a correlation created separately.

[0120] For example, when the amount of liquid reduced in the regeneration process (regeneration means) is W [kg / hr], the flow rate of the absorbing liquid is Q [kg / hr], the liquid temperature of the absorbing liquid flowing into the regeneration process (regeneration means) is T1 [°C], the liquid temperature of the absorbing liquid discharged from the regeneration process (regeneration means) is T2 [°C], and the specific heat of the absorbing liquid is C [kJ / (kg·°C)], the latent heat of the fluid reduced in the regeneration process, J [kJ / hr], is calculated using the following formula: J={C×(QW)×T2}-{C×Q×T1} It can be estimated as follows. Here, the energy used to volatilize 1 kg of steam from the absorption liquid is calculated using the following formula: J / W={C×(Q / W-1)×T2}-{C×(Q / W)×T1} It can be expressed as follows.

[0121] When the latent heat is large, it indicates that the proportion of evaporated water is high, and therefore, from the viewpoint of energy efficiency, it is preferable to control the system by, for example, reducing the capacity of the regeneration process (for example, reducing the drive rate of the vacuum pump to shift the degree of vacuum toward normal pressure), or maintaining a high concentration of the volatile solvent in the absorbing solution in the regeneration process (for example, when a concentrating means is disposed in the stage preceding the regeneration means as shown in FIG. 2, reducing the flow rate of the absorbing solution to increase the concentration of the volatile solvent in the absorbing solution in the regeneration means as much as possible).When the latent heat is small, it indicates that the proportion of evaporated water is low, and therefore, it is preferable to control the system so that the volatile solvent can be actively reduced in the regeneration process (for example, increasing the drive rate of the vacuum pump to shift the degree of vacuum toward a deeper vacuum, etc.). In this way, estimating the latent heat and controlling the system based on this may allow for more energy efficient operation.

[0122] <Temperature difference> In this embodiment, the temperature of the raw material liquid is preferably controlled within a range of 5 to 70° C., and more preferably within a range of 5 to 40° C. The temperature of the raw material liquid can be controlled using a known temperature control device, and such a temperature control device may be one that uses cold water or hot water, or may be one that uses cold air or hot air. For example, if the temperature of the raw material liquid in the concentration step is 5°C or higher, it is easy to prevent the water in the system from freezing. If the temperature of the raw material liquid in the concentration step is 70°C or lower, it is easy to prevent the denaturation of the solutes in the raw material liquid.

[0123] Furthermore, if the temperature of the absorption liquid in the regeneration step is 5°C or higher, it is easy to prevent the water in the system from freezing, as described above. If the temperature of the absorption liquid in the regeneration step is 70°C or lower, it is easy to prevent the interfacial tension of the absorption liquid from decreasing significantly, which in turn prevents the hydrophobic porous membrane from becoming wet. According to a preferred aspect of this embodiment, in the regeneration step, the temperature of the absorbing solution when the volatile solvent migrates to the absorbing solution is 5 to 40°C, as described above.

[0124] In this embodiment, by controlling the temperature of the feed liquid to be relatively high and the temperature of the absorption liquid to be relatively low, it is possible to increase the vapor pressure difference between the two liquids. When the feed liquid and the absorption liquid share water as a common solvent, the temperature difference also increases the vapor pressure difference of water, making it easier to transfer water, along with the volatile solvent, from the feed liquid to the absorption liquid. However, the temperature of the feed liquid after the concentration step tends to decrease due to latent heat and sensible heat transfer through the membrane. Therefore, operating a concentration system while maintaining a temperature difference may require reheating the feed liquid. For effective heating, a heat exchanger is provided to heat the feed liquid, but localized excessive heating may lead to thermal denaturation of the solute. Therefore, the temperature difference between the feed liquid and the absorption liquid is preferably 10°C or less, more preferably 7°C or less, 5°C or less, 3°C or less, 2°C or less, or 1°C or less.

[0125] In this embodiment, by using other means in combination, it is possible to effectively remove solvents, impurities, and the like from the raw material liquid. Examples of other means include a microfiltration membrane, an ultrafiltration membrane, a nanofiltration membrane, a reverse osmosis membrane, and a forward osmosis membrane. The type of such other means and whether or not it is necessary can be selected taking into consideration the size of the solute, the pressure resistance of the membrane and solute, the resistance to the raw material liquid, and the like. It is particularly preferable to use a forward osmosis membrane, which can remove water without heating or pressurizing, as other means in the concentration step.

[0126] <Mass change of the induction liquid> If the concentration system further includes a draw liquid circulation line (e.g., the draw liquid circulation line described for the concentration device 504 in FIG. 4), It is preferable to calculate the amount of solvent reduced in the regenerating means by further using the results of the mass sensor in the circulation line of the draw liquid, which makes it easier to accurately calculate the amount of solvent reduced in the regenerating means.

[0127] [Other embodiments] This completes the description of this embodiment. A preferred aspect of this embodiment is In the regeneration means, the concentration of the volatile solvent in the absorption liquid is 30% by mass or less, the volatile solvent has an octanol / water partition coefficient (log Kow) of 1 or less; The saturated vapor pressure of the volatile solvent at 0°C or higher and lower than 40°C is higher than the saturated vapor pressure of water, and The saturated vapor pressure of the volatile solvent at 20°C is 10 kPa or less. It is a concentrated system.

[0128] In addition, a preferred aspect of this embodiment is the second hydrophobic porous membrane in the regeneration means has a leakage pressure (LEP) of 150 kPa or more when a test liquid is a 20% by mass ethanol (EtOH) aqueous solution; The second hydrophobic porous membrane has an average pore size of 0.1 μm or more. The second hydrophobic porous membrane has a maximum pore size of less than 0.5 μm; It is a concentrated system.

[0129] In addition, a preferred aspect of this embodiment is The concentration system further includes a semipermeable membrane using a forward osmosis membrane method in parallel with the first hydrophobic porous membrane using a membrane distillation method, The regeneration means has the second hydrophobic porous membrane by the reduced pressure membrane distillation method, It is a concentrated system.

[0130] In addition, a preferred aspect of this embodiment is a mass sensor that measures at least the mass of the raw material liquid and the mass of the absorption liquid; a temperature sensor for measuring the temperature of the absorption liquid when the absorption liquid is introduced into the regeneration means and the temperature of the absorption liquid when the absorption liquid is discharged from the regeneration means; a flow rate sensor that measures the flow rate of the absorption liquid flowing through the regeneration means; and a mass of the volatile solvent transferred from the absorption liquid in the regeneration means is calculated based on information from the mass sensor, and further, a latent heat of the volatilized fluid is estimated based on at least one piece of information obtained from the temperature sensor and the flow rate sensor, and the degree of pressure reduction in the regeneration means is controlled. It is a concentrated system.

[0131] However, the present invention is not limited to the above-described embodiment, and can be practiced with various modifications within the scope of the gist thereof.

[0132] For example, the concentration system may have a plurality of concentration means arranged in parallel or in series with the feed liquid tank. Similarly, the concentration system may have a plurality of regeneration means arranged in parallel or in series with the absorption liquid tank. The concentration system may be configured by appropriately combining the concentration devices shown in FIGS.

[0133] In the concentration system, the configuration and arrangement of the various tanks, pumps, sensors, etc. can be modified in various ways without departing from the spirit of the present invention.

[0134] In the concentration system, the configurations of the liquid transfer lines connecting the various tanks to the various ports and the liquid transfer lines connecting the various ports to each other may be the same or different.

[0135] The various modules, namely, the concentration membrane distillation module, the regeneration membrane distillation module, and the forward osmosis membrane module, may have any configuration that allows each module to perform its respective function appropriately.

[0136] FIG. 6 is a schematic diagram showing an example of the configuration of a concentration membrane distillation module in one aspect of the embodiment. For example, in a concentration membrane distillation module 110, a plurality of hollow fiber-shaped hydrophobic porous membranes 12 are housed in a housing 120, and both ends of the hydrophobic porous membranes 12 are adhesively fixed to the housing 120 with adhesive resin 130. Two housing side pipes are provided on the side of the housing 120. One of these housing side pipes is connected to an absorption liquid injection port (12B IN ), and the other is an absorption liquid discharge port (12B OUT )

[0137] The inside of the housing 120 is divided into two spaces, a space A through which the raw material liquid flows and a space B through which the absorption liquid flows, by the outer wall of the hydrophobic porous membrane 12 and the adhesive resin 130. The two spaces are fluidically isolated except that the solvent vapor can pass through the outer wall of the hydrophobic porous membrane 12. Both ends of the space A through which the raw material liquid flows are provided with raw material liquid injection ports 12A. IN and raw material liquid discharge port 12A OUT is provided.

[0138] Raw material liquid injection port 12A IN When the raw material liquid is introduced from the port 12A, the raw material liquid flows inside the hollow fiber hydrophobic porous membrane 12, i.e., through the space A, and then flows out of the raw material liquid discharge port 12A. OUT Similarly, the absorbent liquid flows out from the absorption liquid injection port 12B of the side pipe of the housing 120. IN When the absorption liquid is poured from the port 12B, the absorption liquid flows through the outer space of the hollow fiber hydrophobic porous membrane and reaches the absorption liquid discharge port 12B. OUT As a result, the raw material liquid and the absorption liquid can come into contact with each other via the hydrophobic porous membrane 12. At this time, the solvent vapor moves from the raw material liquid to the absorption liquid due to the difference in vapor pressure between the solvents in both liquids, and is liquefied in the absorption liquid.

[0139] The material of the housing 120 is selected from the viewpoints of chemical resistance, pressure resistance, heat resistance, impact resistance, weather resistance, etc., so that various performances will not be deteriorated by the components contained in the raw material liquid and the absorption liquid. For example, resin, metal, etc. can be used as the material of the housing 120, but from the above viewpoints, it is preferable to select the material from among resins such as polypropylene, polysulfone, polyethersulfone, polyvinylidene fluoride, ABS resin, fiber-reinforced plastic, and polyvinyl chloride resin; and metals such as stainless steel, brass, and titanium.

[0140] The adhesive resin 130 in Figure 6 is desirably one with good mechanical strength. Examples of resins that can be used as the adhesive resin 130 include thermosetting epoxy resins and thermosetting urethane resins. From the viewpoint of heat resistance, epoxy resins are preferred, but from the viewpoint of handleability, urethane resins are preferred. The method for adhesively fixing the hydrophobic porous membrane 12 to the housing 120 may follow known adhesive methods related to the production of hollow fiber membrane modules.

[0141] The regeneration membrane distillation module and the forward osmosis membrane module may also be configured in accordance with the configuration of the concentration membrane distillation module.

[0142] The hydrophobic porous membranes in the concentration membrane distillation module and the regeneration membrane distillation module, and the forward osmosis membrane in the forward osmosis membrane module may each be made of hollow fibers. For example, the hydrophobic porous membrane may be made of hollow fibers made of polyvinylidene fluoride, and the forward osmosis membrane may be made of hollow fibers made of polysulfone. The porosity of the hydrophobic porous membrane may be, for example, 60 to 90%. Also, for forward osmosis membranes, the inner surface of the hollow fibers may be coated with a cross-linked polyamide. However, the configuration of the membranes in these modules is not limited to the above. [Example]

[0143] The present embodiment will be described below with reference to examples and comparative examples. However, the present embodiment is not limited to the following examples. Regarding the examples and comparative examples, various productions, measurements, evaluations, etc. were performed by the following methods.

[0144] [Example 1] A concentration system having the following configuration was constructed in accordance with the concentration apparatus 501 shown in Figure 1. The system was continuously operated under the following conditions, and an attempt was made to concentrate the raw material liquid.

[0145] (Configuration of concentration system) Concentration means: A membrane module including a hydrophobic porous membrane (first hydrophobic porous membrane) was prepared by the following procedure. First, a hydrophobic porous membrane (first hydrophobic porous membrane) was prepared by bundling 70 hollow fiber polyvinylidene fluoride membranes (average pore size 0.2 μm, porosity 72%, membrane thickness 280 μm, inner diameter 0.72 mm, outer diameter 1.20 mm). The hollow fiber housing was then fixed with epoxy adhesive to prepare a membrane distillation module for concentration, with the non-adhesive portion of the hollow fiber measuring approximately 10 cm. Regeneration means: A membrane distillation module for regeneration, including a hydrophobic porous membrane (second hydrophobic porous membrane), was prepared in accordance with the example of preparing the concentration means.

[0146] The first and second hydrophobic porous membranes were coated with a water repellent agent by the following method. Two hundred and ten hollow fibers of the polyvinylidene fluoride membrane cut into 15 cm pieces were immersed in 100 mL of Fluorosurf FS-1610TH (solid concentration 1.0%), a water repellent solution manufactured by Fluoro Technology Co., Ltd., and shaken for 5 minutes. The hollow fibers were then removed and air-dried. Seventy of these fibers were used to fabricate a membrane distillation module.

[0147] (Operating conditions) Raw material solution: 1200 g of an aqueous solution consisting of 30% by mass of acetonitrile, 5% by mass of 2-propanol, 5% by mass of acetic acid, 0.1% by mass of glutathione disulfide, and water Absorbing liquid: 1100g water Operating temperature (i.e., the temperature of the feed liquid and the absorption liquid when the concentration system is operating): 25°C Flow rate of raw material liquid: 300 mL / min Absorption liquid flow rate: 300mL / min Pressure in space D: 5kPaA Refrigerant temperature in the cold trap: -78℃ Operating time: 7.5 hours

[0148] [Example 2] A concentration system having the following configuration was constructed in accordance with the concentration apparatus 503 shown in Figure 3. The system was continuously operated under the following conditions, and an attempt was made to concentrate the raw material liquid.

[0149] (Configuration of concentration system) Concentration means: As in Example 1, a membrane module including a water-repellent coated hydrophobic porous membrane (first hydrophobic porous membrane) was prepared. Regeneration means: Similar to the concentration means, a membrane module including a water-repellent coated hydrophobic porous membrane (second hydrophobic porous membrane) was prepared.

[0150] (Operating conditions) Raw material solution: 1200 g of an aqueous solution consisting of 30% by mass of acetonitrile, 0.1% by mass of glutathione disulfide, and water Absorbing liquid: 300g water Operating temperature (i.e., the temperature of the feed liquid and the absorption liquid when the concentration system is operating): 25°C Flow rate of raw material liquid: 300 mL / min Absorption liquid flow rate: 300mL / min Pressure in space D: 5kPaA Refrigerant temperature in the cold trap: -78℃ Operating time: 24 hours

[0151] [Example 3] A concentration system having the following configuration was constructed in accordance with the concentration apparatus 504 shown in Figure 4. The system was continuously operated under the following conditions in the raw material liquid tank 10 of the concentration system, and an attempt was made to concentrate the raw material liquid.

[0152] (Configuration of concentration system) Concentration means: As in Example 1, a membrane module including a water-repellent coated hydrophobic porous membrane (first hydrophobic porous membrane) was prepared. Furthermore, a forward osmosis membrane module was prepared by bundling 130 forward osmosis membranes (inner diameter 0.70 mm, outer diameter 1.0 mm) in which the inner surface of a polysulfone hollow fiber was coated with crosslinked polyamide. Regeneration means: Similar to the concentration means, a membrane module including a water-repellent coated hydrophobic porous membrane (second hydrophobic porous membrane) was prepared.

[0153] (Operating conditions) Raw material solution: 1200 g of an aqueous solution consisting of 30% by mass of acetonitrile, 0.1% by mass of glutathione disulfide, and water Absorbing liquid: 300g water Operating temperature (i.e., the temperature of the feed liquid and the absorption liquid when the concentration system is operating): 25°C Flow rate of raw liquid: 140mL / min Absorption liquid flow rate: 300mL / min Pressure in space D: 4kPaA Refrigerant temperature in the cold trap: -78℃ Operating time: 5 hours

[0154] [Example 4] A concentration system having the following configuration was constructed in accordance with the concentration apparatus 502 shown in Figure 2. The system was continuously operated under the following conditions, and an attempt was made to concentrate the raw material liquid.

[0155] (Configuration of concentration system) Concentration means: A membrane module including a hydrophobic porous membrane (first hydrophobic porous membrane) was prepared by the following procedure. First, a hollow fiber membrane module was produced using a hydrophobic porous membrane (first hydrophobic porous membrane) obtained by bundling 70 hollow fibers of a hollow fiber-shaped polyvinylidene fluoride membrane {average pore size 0.2 μm; porosity 72%; membrane thickness 280 μm; inner diameter (diameter) of the hollow fiber 0.72 mm, and outer diameter (diameter) of the hollow fiber 1.20 mm). In this example, the first hydrophobic porous membrane was produced without coating with a water repellent agent. Regeneration means: A membrane module including a hydrophobic porous membrane (second hydrophobic porous membrane) was prepared in accordance with the preparation example of the concentration means in Example 4. As in the preparation example of the concentration means in Example 4, the second hydrophobic porous membrane was prepared without being coated with a water repellent agent.

[0156] (Operating conditions) Raw material solution: 1200 g of an aqueous solution consisting of 2.0% by mass of acetonitrile, 0.1% by mass of glutathione disulfide, and water Absorbing liquid: 300g water Operating temperature (i.e., the temperature of the feed liquid and the absorption liquid when the concentration system is operating): 25°C Flow rate of raw material liquid: 300 mL / min Absorption liquid flow rate: 300mL / min Pressure in space D: 3kPaA Refrigerant temperature in the cold trap: -78℃ Operating time: 24 hours

[0157] [Example 5] A concentration system having the following configuration was constructed in accordance with the concentration apparatus 502 shown in Figure 2. The system was continuously operated under the following conditions, and an attempt was made to concentrate the raw material liquid.

[0158] (Configuration of concentration system) Concentration means: A membrane module including a hydrophobic porous membrane (first hydrophobic porous membrane) was prepared by the following procedure. First, a hollow fiber membrane module was produced using a hydrophobic porous membrane (first hydrophobic porous membrane) obtained by bundling 70 hollow fibers of a hollow fiber-shaped polyvinylidene fluoride membrane {average pore size 0.2 μm; porosity 72%; membrane thickness 280 μm; inner diameter (diameter) of the hollow fiber 0.72 mm, and outer diameter (diameter) of the hollow fiber 1.20 mm). In this example, the first hydrophobic porous membrane was produced without coating with a water repellent agent. Regeneration means: A membrane module including a hydrophobic porous membrane (second hydrophobic porous membrane) was prepared in accordance with the preparation example of the concentration means in Example 5. As in the preparation example of the concentration means in Example 5, the second hydrophobic porous membrane was prepared without being coated with a water repellent agent.

[0159] (Operating conditions) Raw material solution: 1200 g of an aqueous solution consisting of 20% by mass of ethanol, 0.1% by mass of glutathione disulfide, and water Absorbing liquid: 300g water Operating temperature (i.e., the temperature of the feed liquid and the absorption liquid when the concentration system is operating): 25°C Flow rate of raw material liquid: 300 mL / min Absorption liquid flow rate: 300mL / min Pressure in space D: 3kPaA Refrigerant temperature in the cold trap: -78℃ Operating time: 8 hours

[0160] [Comparative Example 1] The regeneration means was omitted from the concentration system of Example 1, and a concentration system having the following configuration was constructed as shown in Figure 5. The system was continuously operated under the conditions below, and an attempt was made to concentrate the raw material liquid.

[0161] FIG. 5 is a schematic diagram for explaining the general configuration of the concentrating device in this comparative example. As shown in the figure, the concentrator 605 has a circulation line for the raw liquid and a first circulation line for the absorption liquid, similar to the concentrator 501 in FIG. That is, the raw material liquid is supplied to the raw material liquid tank 10, the raw material liquid injection port 12A, IN , space 12A, and raw material liquid discharge port 12AOUT The absorbent is circulated in this order, and the absorbent is fed to the absorbent tank 20, the absorbent injection port 12B, and the IN , space 12B, and absorption liquid discharge port 12B OUT Cycle through in this order. Here, concentrator 605 differs from concentrator 501 in FIG. 1 in that the regeneration means is omitted as described above. In the concentrator 605, the absorption liquid tank and the absorption liquid transfer line were not connected to the vacuum pump and the cooling trap.

[0162] (Configuration of concentration system) Concentration means: A hydrophobic porous membrane module coated with a water repellent agent was prepared in the same manner as in Example 1.

[0163] (Operating conditions) Raw material solution: 1200 g of an aqueous solution consisting of 30% by mass of acetonitrile, 5% by mass of 2-propanol, 5% by mass of acetic acid, 0.1% by mass of glutathione disulfide, and water Absorbing liquid: 1100g water Operating temperature (i.e., the temperature of the feed liquid and the absorption liquid when the concentration system is operating): 25°C Flow rate of raw material liquid: 300 mL / min Absorption liquid flow rate: 300mL / min Operating time: 7.5 hours

[0164] Comparative Example 2 Based on the concentrator 605 shown in FIG. 5, a pressure reducing port 22D is provided at the top of the absorption liquid tank 20. PRE Connect the pressure reducing port 22D PRE The condenser 605 was connected to the vacuum pump 40 and the solvent recovery tank 50 via the cooling trap 30. That is, in the concentrating apparatus of this comparative example, the concentrating apparatus 605 was used, and the gas phase portion at the top of the absorption liquid tank was extracted by the vacuum pump via the cooling trap, thereby attempting to directly distill the absorption liquid under reduced pressure. Such a concentration system was operated under the following conditions, and an attempt was made to concentrate the raw material liquid.

[0165] (Configuration of concentration system) Concentration means: A hydrophobic porous membrane module coated with a water repellent agent was prepared in the same manner as in Example 1.

[0166] (Operating conditions) Raw material solution: 1000 g of an aqueous solution consisting of 15% by mass of acetonitrile, 0.1% by mass of glutathione disulfide, and water Absorbing liquid: 500g water Operating temperature (i.e., the temperature of the feed liquid and the absorption liquid when the concentration system is operating): 25°C Flow rate of raw material liquid: 300 mL / min Absorption liquid flow rate: 300mL / min Pressure in the gas phase of the absorption liquid tank: 3kPaA Refrigerant temperature in the cold trap: -78℃ Operating time: 2 hours

[0167] Comparative Example 3 A system was constructed by omitting the regeneration step from the concentrating apparatus 504 shown in Figure 4. The system was continuously operated under the following conditions, and an attempt was made to concentrate the raw material liquid. In the concentration system of Comparative Example 3, the absorbent tank and the absorbent liquid transfer line were not connected to the vacuum pump and the cooling trap.

[0168] (Configuration of concentration system) Concentration means: A membrane module including a hydrophobic porous membrane (first hydrophobic porous membrane) coated with a water repellent was prepared in the same manner as in Example 1. Furthermore, a forward osmosis membrane module was prepared by bundling 130 forward osmosis membranes (inner diameter 0.70 mm, outer diameter 1.0 mm) in which the inner surface of polysulfone hollow fibers was coated with crosslinked polyamide.

[0169] (Operating conditions) Raw material solution: 1000 g of an aqueous solution consisting of 30% by mass of acetonitrile, 0.1% by mass of glutathione disulfide, and water Absorbing liquid: 300g water Operating temperature (i.e., the temperature of the feed liquid and the absorption liquid when the concentration system is operating): 25°C Flow rate of raw liquid: 140mL / min Absorption liquid flow rate: 300mL / min Operating time: 5 hours

[0170] Comparative Example 4 A concentration system having the following configuration was constructed by omitting the regeneration means from the concentration system of Example 5. The system was continuously operated under the following conditions, and an attempt was made to concentrate the raw material liquid. In the concentration system of Comparative Example 4, the absorption liquid tank and the absorption liquid transfer line were not connected to the vacuum pump and the cooling trap.

[0171] (Configuration of concentration system) Concentration means: A hydrophobic porous membrane module not coated with a water repellent agent was prepared in the same manner as in Example 5.

[0172] (Operating conditions) Raw material solution: 1200 g of an aqueous solution consisting of 20% by mass of ethanol, 0.1% by mass of glutathione disulfide, and water Absorbing liquid: 300g water Operating temperature (i.e., the temperature of the feed liquid and the absorption liquid when the concentration system is operating): 25°C Flow rate of raw material liquid: 300 mL / min Absorption liquid flow rate: 300mL / min Operating time: 8 hours

[0173] [measurement] <End point composition of raw material liquid (composition of raw material liquid at the end of operation of the concentration system)> The composition of the raw material solution at the end of the operation of the concentration system was determined by gas chromatography using ethanol as an internal standard. Acetic acid was determined by ion chromatography.

[0174] <Break rate (%)> The absorption liquid was sampled at the start and end of operation, and the rejection rate (%) was calculated as follows. The solvent was removed from 100 mL of the sampled absorption liquid by vacuum drying at 70°C. The sample was then diluted to 10 mL with distilled water. The amount of sulfur atoms in the sample was quantified by ICP emission spectroscopy using the diluted solution obtained, and the amount of sulfur atoms was calculated using the following formula: Rejection rate (%) = [1 - (amount of glutathione disulfide transferred before and after operation) ÷ (amount of raw material solution reduced before and after operation)] × 100 The inhibition rate was calculated based on the above.

[0175] <Composition and mass of the liquid recovered in the cooling trap> The composition of the volatile solvent obtained in the cold trap was determined as follows: After the operation was completed, the cold trap was thawed. The thawed liquid (recovered liquid) was sampled and diluted 100 times with distilled water. Ethanol was added as an internal standard, and the concentration of each solvent was estimated by gas chromatography. The concentration of acetic acid was estimated by ion chromatography.

[0176] <Average concentration rate of raw material liquid in the concentration process> The average concentration rate of the raw liquid in the concentration step was calculated by dividing the change in weight of the raw liquid before and after the operation by the processing time.

[0177] [evaluation] <Evaluation of Examples> The results obtained by operating the concentration system in Example 1 are as follows: End point composition of volatile solvents in the raw material solution: acetonitrile 15.9 mass%, 2-propanol 3.8 mass%, acetic acid 5.7 mass% ·Block rate: 99.5% Liquid recovered in the cooling trap: acetonitrile 77.9% by mass, 2-propanol 9.4% by mass, acetic acid 0.1% by mass Average concentration rate of raw liquid in the concentration process: 28.40g / h

[0178] The results obtained by operating the concentration system in Example 2 are as follows: End point composition of volatile solvent in raw material solution: acetonitrile 7.8% by mass ·Block rate: 99.3% Composition of the volatile solvent obtained in the cold trap: acetonitrile 79% by mass Average concentration rate of raw liquid in the concentration process: 11.8g / h

[0179] The results obtained by operating the concentration system in Example 3 are as follows: End point composition of volatile solvents in the raw material solution: acetonitrile 8.4% by mass, 2-propanol 0.7% by mass, acetic acid 3.5% by mass ·Block rate: 99.7% Composition of the volatile solvent obtained in the cold trap: acetonitrile 81% by mass, 2-propanol 2.0% by mass, acetic acid 0.1% by mass Average concentration rate of raw liquid in the concentration process: 175.8g / h

[0180] The results obtained by operating the concentration system in Example 4 are as follows: End point composition of the volatile solvent in the raw material solution: acetonitrile 0.7% by mass ·Block rate: 99.7% Composition of the volatile solvent obtained in the cold trap: acetonitrile 21.5% by mass Average concentration rate of raw liquid in the concentration process: 0.75g / h

[0181] The results obtained by operating the concentration system in Example 5 are as follows: End point composition of volatile solvents in the raw material solution: ethanol 13.2% by mass ·Block rate: 99.9% Composition of the volatile solvent obtained in the cold trap: ethanol 47.2% by mass Average concentration rate of raw liquid in the concentration process: 14.0 g / h

[0182] <Evaluation of Comparative Examples> The results obtained by operating the concentration system in Comparative Example 1 are as follows. End point composition of volatile solvents in the raw material solution: acetonitrile 16.5% by mass, 2-propanol 4.3% by mass, acetic acid 5.1% by mass ·Block rate: 99.1% Composition of volatile solvents obtained in the cold trap: None Average concentration rate of raw liquid in the concentration process: 23.1g / h

[0183] The results obtained by operating the concentration system in Comparative Example 2 are as follows. End point composition of volatile solvent in raw material solution: acetonitrile 14.4% by mass Rejection rate: Glutathione disulfide could not be blocked due to membrane wetting.

[0184] The results obtained by operating the concentration system in Comparative Example 3 are as follows. End point composition of volatile solvents in the raw material solution: acetonitrile 19.1 mass%, 2-propanol 1.2 mass%, acetic acid 4.2 mass% ·Block rate: 99.2% Composition of volatile solvents obtained in the cold trap: None Average concentration rate of raw liquid in the concentration process: 164.2g / h

[0185] The results obtained by operating the concentration system in Comparative Example 4 are as follows. End point composition of volatile solvent in raw material solution: ethanol 16.5% by mass ·Block rate: 99.8% Composition of volatile solvents obtained in the cold trap: None Average concentration rate of raw liquid in the concentration process: 6.5g / h

[0186] The conditions and evaluation results of the examples and comparative examples are summarized in the table below. The abbreviations in the table are as follows: MeCN: acetonitrile IPA: 2-propanol AcOH: acetic acid GSSG: glutathione disulfide EtOH: ethanol DCMD: Concentration Membrane Distillation Module VMD: Regenerative membrane distillation module FO: Forward osmosis membrane module

[0187] [Table 1]

[0188] [Table 2]

[0189] As described above, the examples confirmed that the volatile solvent can be efficiently and effectively reduced from a raw material liquid containing water, a volatile solvent, and a solute using a small amount of absorption liquid. In particular, Example 1 confirmed that it was easy to preferably recover the organic solvent in the absorption liquid. Furthermore, Example 2 confirmed that it was easy to preferably achieve a reduction in the concentration of the volatile solvent in the raw liquid while preferably recovering the organic solvent in the absorption liquid. Furthermore, Example 3 confirmed that it was easy to achieve both a high concentration in the raw liquid and a reduction in the concentration of the organic solvent in the absorption liquid. Furthermore, Example 4 confirmed that it was easy to further reduce the concentration of the volatile solvent in the raw liquid. Furthermore, Example 5 confirmed that this embodiment can be implemented even with solvent types other than those in Examples 1 to 4. [Industrial Applicability]

[0190] The present invention can be suitably used in fields related to the production of chemical products and the like, and more broadly, in fields where it is required to concentrate a solute from a raw material liquid containing water, a volatile solvent, and a solute. [Explanation of symbols]

[0191] 10: Raw material liquid tank 110: Concentration membrane distillation module 12: Hydrophobic porous membrane (first hydrophobic porous membrane) 12A: Space (space for contacting one side of the first hydrophobic porous membrane with the raw material liquid) 12A IN : Raw material liquid injection port 12A OUT : Raw material liquid discharge port 12B: Space (space for contacting the other side of the first hydrophobic porous membrane with the absorption liquid) 12B IN : Absorbent injection port 12B OUT : Absorbent discharge port 13: Liquid transfer pump 20: Absorption tank 210: Regenerative membrane distillation module 22: Hydrophobic porous membrane (second hydrophobic porous membrane) 22C: Space (space for one side of the second hydrophobic porous membrane to come into contact with the absorption liquid) 22C IN : Absorbent injection port 22C OUT : Absorbent discharge port 22D: Space (space for decompressing the other side of the second hydrophobic porous membrane) 22D PRE : Pressure reducing port 23~24,73: Liquid transfer pump 30: Cooling trap 40: Pressure reducing pump 50: Tank for recovered solvent 61: Concentration sensor 62: Temperature sensor (temperature sensor for raw material liquid) 63: Temperature sensor (temperature sensor for absorption liquid) 64: Flow sensor 65: Mass sensor (mass sensor for raw material liquid) 66: Mass sensor (mass sensor for absorbing liquid) 67: Mass sensor (mass sensor for induction liquid) 68: Temperature sensor (temperature sensor for induction liquid) 70: Induction liquid tank 710: Forward osmosis membrane module 72: Semi-permeable membrane 72E: Space (space for one side of the semipermeable membrane to come into contact with the raw material liquid) 72E IN : Raw material liquid injection port 72E OUT : Raw material liquid discharge port 72F: Space (space for the other side of the semipermeable membrane to come into contact with the draw liquid) 72F IN : Induction fluid injection port 72F OUT : Induction liquid discharge port 73: Liquid transfer pump 120: Housing 130: Adhesive resin 501,502,503,504: Concentrator 605: Concentrator (comparative example) FS: Raw material liquid CW: Absorbent liquid

Claims

1. A concentration system for reducing a concentration of a volatile solvent from a raw material liquid containing water, a volatile solvent, and a solute, comprising: a concentrating means for increasing the concentration of the solute in the raw material liquid by bringing the raw material liquid into contact with an absorption liquid for transferring the volatile solvent from the raw material liquid via a hydrophobic porous membrane; and a regeneration means for continuously removing the volatile solvent that has migrated to the absorption liquid. Concentration system.

2. When the hydrophobic porous membrane in the concentration means is referred to as a first hydrophobic porous membrane, The regeneration means has a second hydrophobic porous membrane using a membrane distillation method. The concentration system of claim 1 .

3. The membrane distillation method is a reduced pressure membrane distillation method. The concentration system of claim 2 .

4. The regeneration means reduces the concentration of the volatile solvent having an octanol / water partition coefficient (log Kow) of 1 or less. The concentration system of claim 3 .

5. The saturated vapor pressure of the volatile solvent at 0°C or higher and lower than 40°C is higher than the saturated vapor pressure of water. The concentration system of claim 3 .

6. The concentration of the volatile solvent in the absorption liquid is 30% by mass or less. The concentration system of claim 3 .

7. The saturated vapor pressure of the volatile solvent at 20°C is 10 kPa or less. The concentration system of claim 3 .

8. In the regeneration means, the concentration of the volatile solvent in the absorption liquid is 30 mass% or less, the volatile solvent has an octanol / water partition coefficient (log Kow) of 1 or less; The saturated vapor pressure of the volatile solvent at 0°C or higher and lower than 40°C is higher than the saturated vapor pressure of water, and The saturated vapor pressure of the volatile solvent at 20°C is 10 kPa or less. The concentration system of claim 3 .

9. The volatile solvent includes at least one selected from the group consisting of acetonitrile, ethanol, methanol, isopropyl alcohol, normal propyl alcohol, 1-butyl alcohol, 2-butyl alcohol, t-butyl alcohol, tetrahydrofuran, acetic acid, and trifluoroacetic acid. The concentration system of claim 3 .

10. the second hydrophobic porous membrane in the regeneration means has a leakage pressure (LEP) of 150 kPa or more when a test liquid is a 20% by mass ethanol (EtOH) aqueous solution; The second hydrophobic porous membrane has an average pore size of 0.1 μm or more. The second hydrophobic porous membrane has a maximum pore size of less than 0.5 μm; The concentration system according to claim 3 or 8.

11. The concentration system further includes a semipermeable membrane using a forward osmosis membrane method in parallel with the first hydrophobic porous membrane using the membrane distillation method, The regeneration means has the second hydrophobic porous membrane by the reduced pressure membrane distillation method. The concentration system according to any one of claims 3 to 9.

12. a concentration sensor for detecting the concentration of the volatile solvent in the absorption liquid; controlling the degree of pressure reduction in the regenerating means according to the result of the concentration sensor; The concentration system of claim 3 .

13. a mass sensor that measures at least the mass of the raw material liquid and the mass of the absorption liquid; a temperature sensor for measuring the temperature of the absorption liquid when the absorption liquid is introduced into the regeneration means and the temperature of the absorption liquid when the absorption liquid is discharged from the regeneration means; a flow rate sensor that measures the flow rate of the absorption liquid flowing through the regeneration means; and further comprising at least one of: a mass of the volatile solvent transferred from the absorption liquid in the regeneration means is calculated based on information from the mass sensor, and further, a latent heat of the volatilized fluid is estimated based on at least one piece of information obtained from the temperature sensor and the flow rate sensor, and a degree of pressure reduction in the regeneration means is controlled. The concentration system of claim 3 .

14. A concentration method for reducing a concentration of a volatile solvent from a raw material liquid containing water, a volatile solvent, and a solute, comprising: a concentration step of increasing the concentration of the solute in the raw material liquid by bringing the raw material liquid into contact with an absorption liquid for transferring the volatile solvent from the raw material liquid via a hydrophobic porous membrane; a regeneration step of continuously removing the volatile solvent transferred to the absorption liquid; where: the regeneration step is a reduced pressure membrane distillation method using the hydrophobic porous membrane, The concentration method, wherein the absolute pressure in the reduced pressure membrane distillation system is reduced to a pressure lower than the saturated vapor pressure of the absorption liquid.

15. In the vacuum membrane distillation method, The absolute pressure is reduced to a pressure that is greater than the saturated water vapor pressure and less than the saturated vapor pressure of the absorption liquid, The concentration of the volatile solvent in the absorption liquid is 30 mass% or less, the volatile solvent has an octanol / water partition coefficient (log Kow) of 1 or less; The saturated vapor pressure of the volatile solvent at 0°C or higher and lower than 40°C is higher than the saturated vapor pressure of water, and The saturated vapor pressure of the volatile solvent at 20°C is 10 kPa or less. The method of claim 14.

16. In the regeneration step, the temperature of the absorption solution when the volatile solvent migrates to the absorption solution is 5 to 40°C. The method of claim 14.

17. The volatile solvent includes at least one selected from the group consisting of acetonitrile, ethanol, methanol, isopropyl alcohol, normal propyl alcohol, 1-butyl alcohol, 2-butyl alcohol, t-butyl alcohol, tetrahydrofuran, acetic acid, and trifluoroacetic acid. The method of claim 14.

18. a raw material liquid tank (FS tank) for storing the raw material liquid; an absorption liquid tank (CW tank) for storing the absorption liquid; at least one concentration membrane distillation module (DCMD); at least one regenerative membrane distillation module (VMD); at least one cold trap in contact with the refrigerant; a pressure reducing pump; The concentration membrane distillation module comprises: The hydrophobic porous membrane is composed of a space A for contacting one side of the hydrophobic porous membrane with a raw material liquid, and a space B for contacting the other side of the hydrophobic porous membrane with an absorption liquid, a raw material liquid injecting port and a raw material liquid discharging port connected to the space A, and an absorption liquid injecting port and an absorption liquid discharging port connected to the space B, The regenerating membrane distillation module comprises: The hydrophobic porous membrane is composed of a space C for contacting one side of the hydrophobic porous membrane with an absorption liquid, and a space D for reducing the pressure on the other side of the hydrophobic porous membrane, an absorption liquid injection port and an absorption liquid discharge port connected to the space C, and at least one pressure reduction port connected to the space D; Here, the following (1) to (3): （１） the raw material liquid inlet port and the raw material liquid outlet port are connected to the raw material liquid tank; the absorption liquid inlet port and the absorption liquid outlet port are connected to the absorption liquid tank; The pressure reduction port and the pressure reduction pump are connected via the cooling trap. （２） the raw material liquid inlet port and the raw material liquid outlet port are connected to the raw material liquid tank; the absorption liquid discharge port of the space B and the absorption liquid injection port of the space C are connected in series, the absorption liquid inlet port of the space B and the absorption liquid outlet port of the space C are connected to the absorption liquid tank, The pressure reduction port and the pressure reduction pump are connected via the cooling trap. （３） the raw material liquid inlet port and the raw material liquid outlet port are connected to the raw material liquid tank; the absorption liquid discharge port of the space C and the absorption liquid injection port of the space B are connected in series, the absorption liquid inlet port of the space C and the absorption liquid outlet port of the space B are connected to the absorption liquid tank, The pressure reduction port and the pressure reduction pump are connected via the cooling trap. having at least one line configuration among Concentrator.

19. a heat exchanger is not provided between the raw material liquid inlet port and the raw material liquid tank, and between the raw material liquid outlet port and the raw material liquid tank; 19. The concentrator of claim 18.

20. a draw solution tank and one or more forward osmosis membrane modules; The forward osmosis membrane module comprises a semipermeable membrane, a space E for contacting one surface of the semipermeable membrane with a raw material liquid, and a space F for contacting the other surface of the semipermeable membrane with a draw liquid, a raw material liquid inlet port and a raw material liquid outlet port connected to the space E, and a guide liquid inlet port and a guide liquid outlet port connected to the space F, the raw material liquid inlet port and the raw material liquid outlet port are connected to the raw material liquid tank; The guiding liquid inlet port and the guiding liquid outlet port are connected to the guiding liquid tank.

20. The concentrator of claim 19.

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