Membrane separation device, membrane separation system, and method for operating membrane separation device

Abstract

The present invention provides a membrane separation device suitable for inhibiting the hygienic state inside the membrane separation device from deteriorating. The membrane separation device is equipped with a spiral membrane element. The membrane element comprises: a center tube having through holes; and a membrane leaf wound around the center tube and including a pervaporation membrane for separating a fermentation broth containing a volatile organic compound into a penetrant and a retentate. During operation of the membrane separation device, the retentate is prevented from flowing into the space adjoining the outer peripheral surface of the membrane element.

Description

Membrane separation device, membrane separation system, and method for operating a membrane separation device

[0001] The present invention relates to a membrane separation device, a membrane separation system, and a method for operating a membrane separation device.

[0002] Methods have been developed for producing volatile organic compounds (fermented products) such as alcohols by fermenting carbon sources such as glucose using microorganisms. Fermentation of the carbon source is carried out, for example, in an aqueous solution. In this method, microbial fermentation may cease if the content of the fermented product in the aqueous solution increases. To continuously produce microbial fermented products, it is necessary to separate the fermented product from the aqueous solution.

[0003] One example of a method for separating volatile organic compounds from an aqueous solution containing the organic compounds is pervaporation using a separation membrane. Pervaporation is suitable for separating volatile organic compounds from an aqueous solution containing various substances. Compared to distillation, pervaporation also tends to reduce energy consumption and carbon dioxide emissions. By combining a membrane separation device that performs pervaporation with a fermenter that produces a fermented product, it is possible to continuously produce a fermented product. For example, Patent Document 1 discloses a membrane separation system that combines a membrane separation device and a fermenter.

[0004] JP 2010-161987 A

[0005] The pervaporation method may use a membrane separation apparatus equipped with a spiral membrane element having a pervaporation membrane. For example, as shown in FIG. 14 , one such membrane separation apparatus includes a spiral membrane element and a casing housing the membrane element. In the membrane separation apparatus 200 shown in FIG. 14 , non-permeated fluid s2 may flow into a space adjacent to the outer peripheral surface 35 s of the spiral membrane element 35, specifically, a space 45 formed between the outer peripheral surface 35 s and the inner peripheral surface 32 s of the casing 32. If non-permeated fluid s2 remains in the space 45, sanitation conditions will deteriorate, so it is necessary to minimize this retention.

[0006] Therefore, an object of the present invention is to provide a membrane separation device suitable for suppressing deterioration of the sanitary condition inside the membrane separation device.

[0007] The present invention provides a membrane separation apparatus equipped with a spiral-type membrane element, wherein the membrane element includes a central tube having through-holes, and a membrane leaf wound around the central tube, the membrane leaf having a pervaporation membrane that separates a fermentation liquid containing volatile organic compounds into a permeate fluid and a non-permeate fluid, and wherein, during operation, the non-permeate fluid is prevented from flowing into a space adjacent to the outer peripheral surface of the membrane element.

[0008] In another aspect, the present invention provides a membrane separation apparatus equipped with a spiral-type membrane element, wherein the membrane element includes a central tube having through-holes and a membrane leaf wound around the central tube, the membrane leaf having a pervaporation membrane that separates a fermentation liquor containing volatile organic compounds into a permeate fluid and a non-permeate fluid, wherein the following condition (1) or (2) is satisfied: (1) A space adjacent to the outer peripheral surface of the membrane element is sealed, and (2) A space adjacent to the outer peripheral surface of the membrane element forms a flow path for a fluid other than the non-permeate fluid.

[0009] In yet another aspect, the present invention provides a membrane separation system including the membrane separation device of the present invention.

[0010] In yet another aspect, the present invention provides a method for operating a membrane separation apparatus equipped with a spiral-type membrane element, wherein the membrane element includes a central tube having through-holes and a membrane leaf having a pervaporation membrane and wound around the central tube, the method comprising: supplying a fermentation broth containing volatile organic compounds to the membrane separation apparatus; separating the fermentation broth into a permeate fluid and a non-permeate fluid by the pervaporation membrane; and discharging the non-permeate fluid from the membrane separation apparatus while preventing the non-permeate fluid from flowing into a space adjacent to the outer peripheral surface of the membrane element.

[0011] According to the present invention, a membrane separation device suitable for suppressing deterioration of the sanitary condition inside the membrane separation device can be provided.

[0012] FIG. 1 is a schematic cross-sectional view showing a membrane separation apparatus of embodiment 1. FIG. 2 is an exploded perspective view schematically showing a spiral membrane element provided in the membrane separation apparatus of this embodiment. FIG. 3 is a schematic cross-sectional view of the spiral membrane element of FIG. 2. FIG. 4 is a schematic cross-sectional view of a pervaporation membrane provided in the membrane separation apparatus of this embodiment. FIG. 5 is a schematic cross-sectional view showing a membrane separation apparatus of embodiment 2. FIG. 6 is a schematic cross-sectional view showing a membrane separation apparatus of embodiment 3. FIG. 7 is a schematic cross-sectional view showing a membrane separation apparatus of embodiment 4. FIG. 8 is a schematic cross-sectional view showing a membrane separation apparatus of embodiment 5. FIG. 9 is a schematic cross-sectional view showing a membrane separation apparatus of embodiment 6. FIG. 10 is a schematic cross-sectional view showing a membrane separation apparatus of embodiment 7. FIG. 11 is a schematic cross-sectional view showing a membrane separation apparatus of embodiment 8. FIG. 12 is a schematic configuration diagram showing a membrane separation system of this embodiment. FIG. 13 is a schematic configuration diagram showing a first modified example of the membrane separation system of this embodiment. FIG. 14 is a schematic configuration diagram showing a second modified example of the membrane separation system of this embodiment. FIG. 15 is a schematic cross-sectional view showing a membrane separation apparatus equipped with a conventional spiral membrane element.

[0013] A membrane separation device according to a first aspect of the present invention is a membrane separation device equipped with a spiral membrane element, wherein the membrane element includes a central tube having through-holes, and a membrane leaf having a pervaporation membrane that separates a fermentation liquid containing volatile organic compounds into a permeate fluid and a non-permeate fluid, and wound around the central tube, and wherein the non-permeate fluid is prevented from flowing into a space adjacent to the outer peripheral surface of the membrane element during operation.

[0014] A membrane separation device according to a second aspect of the present invention is a membrane separation device equipped with a spiral membrane element, wherein the membrane element includes a central tube having through-holes and a membrane leaf wound around the central tube, the membrane leaf having a pervaporation membrane that separates a fermentation liquor containing volatile organic compounds into a permeate fluid and a non-permeate fluid, and wherein the following condition (1) or (2) is met: (1) A space adjacent to the outer peripheral surface of the membrane element is sealed, and (2) A space adjacent to the outer peripheral surface of the membrane element forms a flow path for a fluid other than the non-permeate fluid.

[0015] In a third aspect of the present invention, for example, in the membrane separation device according to the first or second aspect, the outer peripheral surface of the membrane element is made of a flow path material.

[0016] In a fourth aspect of the present invention, for example, the membrane separation device according to any one of the first to third aspects further comprises a seal portion disposed around the membrane element.

[0017] In a fifth aspect of the present invention, for example, in the membrane separation device according to the fourth aspect, the sealing portion has a through-hole through which the fermentation liquid flows into the space.

[0018] In a sixth aspect of the present invention, for example, in the membrane separation device according to the fourth aspect, the space is sealed by two of the seal portions.

[0019] In a seventh aspect of the present invention, for example, in the membrane separation device according to the sixth aspect, the sealing portion contains a casting agent.

[0020] In an eighth aspect of the present invention, for example, in the membrane separation device according to the first or second aspect, the space is sealed by filling the space with a filler.

[0021] In a ninth aspect of the present invention, for example, in the membrane separation device according to the first or second aspect, the space is filled with a material having a thermal conductivity of 0.1 W / m·K or more.

[0022] In a tenth aspect of the present invention, for example, in the membrane separation device according to any one of the first to ninth aspects, the membrane element is configured to be detachable from a casing.

[0023] A membrane separation system according to an eleventh aspect of the present invention includes the membrane separation device according to any one of the first to tenth aspects.

[0024] In a twelfth aspect of the present invention, for example, the membrane separation system according to the eleventh aspect further includes a tank for storing the fermentation liquid to be supplied to the membrane separation device.

[0025] In a thirteenth aspect of the present invention, for example, in the membrane separation system according to the eleventh or twelfth aspect, the membrane separation system includes a plurality of the membrane separation devices, and the plurality of membrane separation devices are connected to each other in series or in parallel.

[0026] A method for operating a membrane separation apparatus according to a fourteenth aspect of the present invention is a method for operating a membrane separation apparatus equipped with a spiral-type membrane element, wherein the membrane element includes a central tube having through holes and a membrane leaf having a pervaporation membrane and wound around the central tube, and the operating method includes: supplying a fermentation broth containing volatile organic compounds to the membrane separation apparatus; separating the fermentation broth into a permeate fluid and a non-permeate fluid by the pervaporation membrane; and discharging the non-permeate fluid from the membrane separation apparatus while preventing the non-permeate fluid from flowing into a space adjacent to the outer peripheral surface of the membrane element.

[0027] A membrane separation apparatus according to a fifteenth aspect of the present invention is a membrane separation apparatus comprising a spiral membrane element and a casing that houses the membrane element, wherein the membrane element comprises a central tube having through holes and a membrane leaf wound around the central tube, the membrane leaf having a pervaporation membrane that separates a fermentation liquid containing volatile organic compounds into a permeate fluid and a non-permeate fluid, and wherein during operation, the non-permeate fluid does not flow into the space between the outer peripheral surface of the membrane element and the inner peripheral surface of the casing.

[0028] A membrane separation apparatus according to a sixteenth aspect of the present invention is a membrane separation apparatus comprising a spiral membrane element and a casing that houses the membrane element, wherein the membrane element comprises a central tube having through-holes and a membrane leaf wound around the central tube, the membrane leaf having a pervaporation membrane that separates a fermentation liquor containing volatile organic compounds into a permeate fluid and a non-permeate fluid, and wherein the following condition (1) or (2) is met: (1) The space between the outer peripheral surface of the membrane element and the inner peripheral surface of the casing is sealed. (2) The space between the outer peripheral surface of the membrane element and the inner peripheral surface of the casing constitutes at least one flow path selected from the group consisting of the fermentation liquor and an effluent generated when the fermentation liquor flows out from the outer peripheral surface of the membrane element.

[0029] A method for operating a membrane separation apparatus according to a seventeenth aspect of the present invention is a method for operating a membrane separation apparatus comprising a spiral membrane element and a casing that houses the membrane element, wherein the membrane element comprises a central tube having through holes and a membrane leaf having a pervaporation membrane and wound around the central tube, and the operating method comprises: supplying a fermentation liquor containing volatile organic compounds to the membrane separation apparatus; separating the fermentation liquor into a permeate fluid and a non-permeate fluid by the pervaporation membrane; and discharging the non-permeate fluid from the membrane separation apparatus so that the non-permeate fluid does not flow into a space between the outer peripheral surface of the membrane element and the inner peripheral surface of the casing.

[0030] The present invention will be described in detail below, but the following description is not intended to limit the present invention to a specific embodiment.

[0031] <Embodiment of Membrane Separation Apparatus> The membrane separation apparatus of this embodiment includes a spiral membrane element. The membrane element includes a central tube with through holes and a membrane leaf wrapped around the central tube, the membrane leaf having a pervaporation membrane that separates a fermentation liquor containing volatile organic compounds into a permeate fluid and a non-permeate fluid. The membrane separation apparatus of this embodiment is an apparatus that performs membrane separation of a fermentation liquor containing volatile organic compounds using a pervaporation membrane during operation.

[0032] In the membrane separation apparatus of this embodiment, the inflow of non-permeating fluid into the space adjacent to the outer peripheral surface of the membrane element is prevented during operation. From another aspect, the membrane separation apparatus of this embodiment satisfies the following condition (1) or (2): (1) The space adjacent to the outer peripheral surface of the membrane element is sealed. (2) The space adjacent to the outer peripheral surface of the membrane element forms a flow path for a fluid other than the non-permeating fluid. The fluid other than the non-permeating fluid is at least one selected from the group consisting of a fermentation broth, an effluent produced when the fermentation broth flows out from the outer peripheral surface of the membrane element, and a heat medium for heating the membrane element.

[0033] Preferred examples of the present embodiment, that is, embodiments 1 to 8, will be described below with reference to Figures 1 to 11. Elements common to embodiments 1 to 8 will be given the same reference numerals, and their description may be omitted. The descriptions of embodiments 1 to 8 may be mutually applied unless technically inconsistent. Furthermore, embodiments 1 to 8 may be combined with each other unless technically inconsistent.

[0034] [Embodiment 1] Fig. 1 is a schematic cross-sectional view showing a membrane separation apparatus 100 of Embodiment 1. As shown in Fig. 1, the membrane separation apparatus 100 of Embodiment 1 includes a spiral membrane element 15 and a casing 12 that houses the membrane element 15. In the membrane separation apparatus 100, a space 25 adjacent to the outer peripheral surface 15s of the membrane element 15 is a space formed between the outer peripheral surface 15s of the membrane element 15 and the inner peripheral surface 12s of the casing 12. In the membrane separation apparatus 100 of Embodiment 1, the space 25 forms a flow path for an effluent S3 generated when the fermentation broth S flows out from the outer peripheral surface 15s of the membrane element 15.

[0035] Fig. 2 is an exploded perspective view schematically showing a membrane element 15 included in the membrane separation apparatus of this embodiment. Fig. 3 is a schematic cross-sectional view of the membrane element 15 of Fig. 2. The membrane element 15 includes a central tube 15 having through holes 16h and a membrane leaf 17a wound around the central tube 15 and having a pervaporation membrane 11 that separates the fermentation broth S into a permeate fluid S1 and a non-permeate fluid S2.

[0036] 2 and 3, the membrane element 15 includes a laminate 17. The laminate 17 is wound around the central tube 15 and disposed around the central tube 15. A feed space and a permeate space are formed inside the laminate 17.

[0037] The fermentation broth S is supplied into the membrane element 15 from one end face of the stack 17 and flows through the supply space parallel to the longitudinal direction of the central tube 16. That is, the fermentation broth S is a fluid supplied from the upstream end face of the stack 17 provided in the membrane element 15. Of the fluids flowing through the supply space parallel to the longitudinal direction of the central tube 16, the fluid that flows out from the outer circumferential surface 15s of the membrane element 15 corresponds to the effluent S3. In the membrane element 15, the fermentation broth S is separated to produce a permeated fluid S1 and a non-permeated fluid S2. The permeated fluid S1 is guided to the outside through the central tube 16. The non-permeated fluid S2 is discharged to the outside of the membrane element 15 from the other end face of the stack 17. That is, the non-permeated fluid S2 is a fluid discharged from the downstream end face of the stack 17 provided in the membrane element 15.

[0038] As shown in FIG. 3 , the laminate 17 has multiple membrane leaves 17a. Each membrane leaf 17a has a pervaporation membrane 11 and a permeate-side channel material 19. In FIG. 3 , the permeate-side channel material 19 is indicated by a dashed line. Specifically, the membrane leaf 17a has two pervaporation membranes 11. The two pervaporation membranes 11 are stacked on top of each other and sealed at three sides to form a bag-like structure. The two pervaporation membranes 11 are sealed using, for example, an adhesive layer 11a containing an adhesive. A permeate-side channel material 19 is disposed between the two pervaporation membranes 11 so as to be located inside the bag-like structure. The permeate-side channel material 19 ensures a space (permeation space) between the two pervaporation membranes 11 as a channel for the permeating fluid S1. In this way, the permeate-side channel material 19 is combined with the pervaporation membrane 11 for use. The number of membrane leaves 17a is not particularly limited and may be, for example, 2 to 30.

[0039] The laminate 17 further has a feed-side channel material 18. In Fig. 3, the feed-side channel material 18 is indicated by a dashed line. The feed-side channel material 18 is located outside the above-mentioned bag-like structure and is laminated on the membrane leaf 17a. In detail, the laminate 17 has a plurality of feed-side channel materials 18, and a plurality of feed-side channel materials 18 and a plurality of membrane leaves 17a are laminated alternately. The feed-side channel material 18 ensures a space (supply space) as a channel for the fermentation liquid S between the membrane leaves 17a.

[0040] As shown in Figures 2 and 3, the central tube 16 is typically tubular, particularly cylindrical. The central tube 16 serves to collect the permeate fluid S1 that has permeated through each pervaporation membrane 11 and guide it to the outside of the membrane element 15. The central tube 16 is provided with through-holes 16h that communicate the internal space of the central tube 16 with the external space. The through-holes 16h are formed, for example, in the wall surface of the central tube 16. The number of through-holes 16h is not particularly limited and may be one or two or more. The central tube 16 may be provided with a plurality of through-holes 16h at predetermined intervals along the direction in which the central tube 16 extends. The number of rows of the plurality of through-holes 16h provided along the direction in which the central tube 16 extends is not particularly limited and may be one or two or more. The central tube 16 may be provided with two rows of the plurality of through-holes 16h that face each other in a cross-sectional view. The outer diameter of the central tube 16 is, for example, 10 to 100 mm, and preferably 12 to 50 mm.

[0041] Examples of materials for the central tube 16 include resins such as acrylonitrile butadiene styrene copolymer resin (ABS resin), polyphenylene ether resin (PPE resin), and polysulfone resin (PSF resin); and metals such as stainless steel and titanium.

[0042] The membrane element 15 may further include a flow path material 19c. The flow path material 19c is indicated by a dashed line in FIG. 3 . The flow path material 19c is located between the central tube 16 and the stack 17 and is wound around the central tube 16 closer to the central tube 16 than the stack 17. The flow path material 19c ensures a space for a flow path of the permeate fluid S1 between the stack 17 and the central tube 16. The flow path material 19c is connected to the open end of the membrane leaf 17a described above. This connects the permeate-side flow path material 19 of the membrane leaf 17a to the flow path material 19c. The flow path material 19c is in contact with the through-hole 16h of the central tube 16. This allows the permeate fluid S1 to flow from the flow path material 19c into the interior of the central tube 16 through the through-hole 16h.

[0043] As the feed-side flow path material 18, the permeate-side flow path material 19, and the flow path material 19c, for example, a resin net, woven fabric, or knitted fabric made of polyethylene, polypropylene, polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polysulfone (PSU), or ethylene-chlorotrifluoroethylene copolymer (ECTFE) can be used.

[0044] As shown in FIG. 1 , in the membrane separation apparatus 100 of the first embodiment, the outer peripheral surface 15s of the membrane element 15 is formed of a flow path material 26. In other words, the membrane element 15 includes a flow path material 26 that surrounds the laminate 17. With this configuration, as shown in FIG. 1 , the effluent S3 generated when the fermentation liquor S flows out of the outer peripheral surface 15s of the membrane element 15 flows into the space 25. The effluent S3 that flows into the space 25 flows along the space 25. That is, in the membrane separation apparatus 100, the above-mentioned condition (2) is met. More specifically, in the membrane separation apparatus 100, the space 25 forms a flow path for the effluent S3. The effluent S3 that flows through the space 25 is discharged to the outside of the membrane separation apparatus 100 together with the fermentation liquor S (non-permeated fluid S2) that did not permeate the pervaporation membrane 11 of the membrane element 15. Therefore, in the membrane separation apparatus 100, the non-permeated fluid S2 is prevented from flowing into the space 25.

[0045] As the flow path material 26, it is possible to use the materials exemplified as the feed-side flow path material 18, the permeate-side flow path material 19, the flow path material 19c, and the flow path material 26. The flow path material 26 may be the same as the feed-side flow path material 18.

[0046] The membrane separation apparatus 100 of the first embodiment further includes a seal unit 24 disposed around the membrane element 15. One end of the space 25 is sealed by the seal unit 24. For example, the seal unit 24 may be a seal with a U-shaped cross section, an O-ring seal, or the like.

[0047] In the membrane separation apparatus 100 of the first embodiment, the seal unit 24 is disposed in one location. In other words, one end of the space 25 is sealed by one seal unit 24. That is, in the membrane separation apparatus 100, one seal unit 24 is used as the seal unit 24.

[0048] 1, the seal unit 24 is preferably disposed at the upstream end 15a of the membrane element 15. The seal unit 24 may also be disposed slightly downstream of the upstream end 15a of the membrane element 15. Even with such a structure, the same effect can be expected.

[0049] In the membrane separation apparatus 100 of the first embodiment, the seal portion 24 has a ring shape and circumferentially surrounds the membrane element 15. The seal portion 24 may be the same as the seal member 44 used in the conventional membrane separation apparatus 200 shown in Fig. 11, which will be described later.

[0050] In this embodiment, the shape of the casing 12 is not particularly limited as long as it can accommodate the membrane elements 15. The shape of the casing 12 may be, for example, a cylindrical shape or a rectangular tubular shape. Fig. 1 illustrates an example in which the casing 12 has a cylindrical shape.

[0051] As illustrated in FIG. 1 , in this embodiment, the casing 12 includes a casing body 12a, a first end plate 12b, and a second end plate 12c. The casing body 12a has a cylindrical shape and is made of a material with sufficient pressure resistance. The casing 12 may be a high-pressure vessel used for reverse osmosis membranes. The first end plate 12b is attached to an upstream end 23a of the casing 12. The end 23a of the casing 12 is closed by the first end plate 12b. The second end plate 12c is attached to a downstream end 23b of the casing 12. The end 23b of the casing 12 is closed by the second end plate 12c.

[0052] The casing 12 has ports 21a, 21b, and 22b. These ports are used to connect the inside and outside of the casing 12. Port 21a is provided at an upstream end 23a of the casing 12. Ports 21b and 22b are provided at a downstream end 23b of the casing 12.

[0053] 1, the port 21a may be provided in the first end plate 12b, and the port 22b may be provided in the second end plate 12c. The port 21b and the port 22b may be provided in the second end plate 12c.

[0054] The port 22b may be provided in the first end plate 12b, that is, the port 21a and the port 22b may be provided in the first end plate 12b.

[0055] 1 , in this embodiment, an upstream space 25a is formed between the inner surface 12bs of the first end plate 12b and the upstream end face 15as of the membrane element 15. A downstream space 25b is formed between the inner surface 12cs of the second end plate 12c and the downstream end face 15bs of the membrane element 15. The space 25 is separated from the upstream space 25a by a seal portion 24.

[0056] Although not shown in the figures, in the membrane separation apparatus 100, an end member may be attached to one or both axial ends of the membrane element 15. The end member is also called an anti-telescope member or an anti-telescope material. In this case, the seal portion 24 seals one end of the space 25 via the end member arranged at the upstream end 15a of the membrane element 15. When an end member is attached to one or both axial ends of the membrane element 15, the outer peripheral surface 15s of the membrane element 15 also includes the outer peripheral surfaces of the end members.

[0057] In this embodiment, the membrane element 15 is placed horizontally so that its longitudinal direction is along the horizontal direction. When the membrane element 15 is placed horizontally, the port 21b may be located above the second end plate 12c. In this case, the port 21a may be located below the first end plate 12b. The membrane element 15 may be placed vertically so that its longitudinal direction is along the vertical direction, or may be placed obliquely so that its longitudinal direction forms an angle greater than 0° and less than 90° with respect to the horizontal direction.

[0058] The fermentation liquid inlet 13a is an opening for supplying the fermentation liquid S to the membrane separation apparatus 100. The permeate fluid outlet 14b is an opening for discharging the permeate fluid S1 from the membrane separation apparatus 100. The non-permeate fluid outlet 13b is an opening for discharging the fermentation liquid S that has not permeated the pervaporation membrane 11 (non-permeate fluid S2) from the membrane separation apparatus 100. The fermentation liquid inlet 13a and port 21a are connected to each other, and port 21a is used as the inlet for the fermentation liquid S. The central tube 16 is connected to port 22b at the permeate fluid outlet 14b. That is, port 22b is used as the outlet for the permeate fluid S1. The non-permeate fluid outlet 13b is connected to port 21b, and port 21b is used as the outlet for the non-permeate fluid S2. Each port may be a simple opening or a nozzle-shaped opening as shown in FIG. 1.

[0059] In this embodiment, the membrane element 15 may be configured to be detachable from the casing 12. In other words, the membrane element 15 may be configured as a cartridge, and the membrane element 15 may be configured to be replaceable with respect to the casing 12. With such a configuration, the time required for the membrane element 15 replacement work can be shortened.

[0060] In this embodiment, the diameter of the membrane element 15 may be 8 inches (approximately 201 mm) or less. A membrane separation device equipped with a membrane element 15 of this size is highly portable.

[0061] The membrane separation device of this embodiment may separate the fermentation liquid S into a permeated fluid S1 and a non-permeated fluid S2 in a state where the supply space of the membrane element 15 is filled with the fermentation liquid S.

[0062] The membrane separation device of this embodiment is suitable for a continuous membrane separation method, but may also be used for a batch membrane separation method.

[0063] (Pervaporation Membrane) The pervaporation membrane 11 is a separation membrane that generates a permeating fluid S1, a gas containing volatile organic compounds, by pervaporation. In other words, the pervaporation membrane 11 is a membrane that preferentially allows the organic compounds contained in the fermentation liquor S to permeate. Therefore, the content of organic compounds in the permeating fluid S1 is higher than the content of organic compounds in the fermentation liquor S. On the other hand, the content of organic compounds in the non-permeating fluid S2 is lower than the content of organic compounds in the fermentation liquor S.

[0064] Figure 4 is a schematic cross-sectional view of a pervaporation membrane 11 included in the membrane separation device of this embodiment. As shown in Figure 4, the pervaporation membrane 11 includes, for example, a separation function layer 1 and a porous support 2 that supports the separation function layer 1. The pervaporation membrane 11 may further include a protective layer (not shown) that protects the separation function layer 1. The separation function layer 1 is in direct contact with, for example, the porous support 2. For example, the main surface 11a of the pervaporation membrane 11 on the separation function layer side is exposed to the supply space, and the main surface 11b on the porous support side is exposed to the permeation space.

[0065] (Separation functional layer) The separation functional layer 1 is a layer that allows preferential permeation of organic compounds contained in the fermentation broth S. The separation functional layer 1 includes, for example, a hydrophobic material. In this specification, the term "hydrophobic material" refers to a material that has a static contact angle with water of more than 90° when a 10 μL water droplet (at 25° C.) is dropped onto the surface of a test piece made of the material. The static contact angle with water can be measured using a commercially available contact angle meter.

[0066] Examples of hydrophobic materials include compounds having a siloxane bond (Si—O—Si bond), olefin-based polymers, oils, and fluorine-based compounds. The separation functional layer 1 preferably contains a compound having a siloxane bond as the hydrophobic material. Compounds having a siloxane bond are typically silicone-based polymers. Silicon-based polymers may be solid or liquid at 25°C. Specific examples of silicone-based polymers include polydimethylsiloxane (PDMS). Specific examples of olefin-based polymers include polyethylene and polypropylene. Examples of oils include hydrocarbon oils such as liquid paraffin. Specific examples of fluorine-based compounds include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers (PFA). The hydrophobic materials can be used alone or in combination of two or more.

[0067] The separation functional layer 1 may contain a hydrophobic material as a main component, or may be composed essentially of a hydrophobic material. The "main component" refers to the component that is contained in the separation functional layer 1 in the largest amount by weight.

[0068] The separation functional layer 1 may include a matrix containing a hydrophobic material and a filler dispersed in the matrix. The filler is embedded in the matrix. Within the matrix, all of the fillers may be spaced apart from one another or may be partially aggregated.

[0069] The filler includes, for example, an inorganic material such as zeolite, silica, or bentonite. The zeolite contained in the filler is preferably a high-silica zeolite having a high ratio of silica to alumina. High-silica zeolite has excellent hydrolysis resistance and is therefore suitable for separating the aqueous solution S1. Examples of high-silica zeolites that can be used include HSZ (registered trademark) manufactured by Tosoh Corporation, HiSiv (registered trademark) manufactured by Union Showa Corporation, USKY (registered trademark) manufactured by Union Showa Corporation, and Zeoal (registered trademark) manufactured by Nakamura Choukou Co., Ltd.

[0070] The filler may include a metal-organic framework (MOF). The metal-organic framework is also called a porous coordination polymer (PCP). The metal-organic framework is preferably hydrophobic. The metal-organic framework includes, for example, a metal ion and an organic ligand. Examples of the metal ion include Zn ions. Examples of the organic ligand include an aromatic ring. Examples of the aromatic ring included in the organic ligand include an imidazole ring. Examples of the organic ligand include 2-methylimidazole. Specific examples of the metal-organic framework include ZIF-8.

[0071] The shape of the filler is, for example, particulate. In this specification, "particulate" includes spherical, ellipsoidal, scaly, and fibrous shapes. The average particle size of the filler is not particularly limited and is, for example, 50 μm or less, preferably 20 μm or less, and more preferably 10 μm or less. The lower limit of the average particle size of the filler is, for example, 0.01 μm. The average particle size of the filler can be determined, for example, by the following method. First, the cross section of the separation functional layer 1 is observed with a transmission electron microscope. In the obtained electron microscope image, the area of ​​a specific filler is calculated by image processing. The diameter of a circle having the same area as the calculated area is considered to be the particle size (particle diameter) of that specific filler. The particle sizes of an arbitrary number (at least 50) of fillers are calculated, and the average of the calculated values ​​is considered to be the average particle size of the filler.

[0072] The filler content in the separation functional layer 1 is, for example, 10 wt % or more, preferably 30 wt % or more, and more preferably 40 wt % or more. The upper limit of the filler content in the separation functional layer 1 is not particularly limited and is, for example, 70 wt %. The matrix content in the separation functional layer 1 is not particularly limited and is, for example, 30 wt % to 90 wt %.

[0073] The thickness of the separation functional layer 1 is, for example, 200 μm or less, preferably 100 μm or less, and more preferably 80 μm or less. The thickness of the separation functional layer 1 may be 1.0 μm or more, 10 μm or more, or 30 μm or more.

[0074] The separation functional layer 1 may have a microporous structure with an average pore size of less than 0.01 μm, but may also be a dense layer with no pores on the surface.

[0075] (Porous support) Examples of the porous support 2 include nonwoven fabrics, porous polytetrafluoroethylene, aromatic polyamide fibers, porous metals, sintered metals, porous ceramics, porous polyesters, porous nylons, activated carbon fibers, latex, silicone, silicone rubber, polyvinyl fluoride, polyvinylidene fluoride, polyurethane, polypropylene, polyethylene, polystyrene, polycarbonate, polysulfone, polyether ether ketone, polyacrylonitrile, polyimide, and polyphenylene oxide. Permeable (porous) polymers containing at least one selected from the group consisting of open-cell or closed-cell metal foams, open-cell or closed-cell polymer foams, silica, porous glass, and mesh screens. The porous support 2 may be a combination of two or more of these.

[0076] The porous support 2 has an average pore size of, for example, 0.01 to 0.4 μm. The thickness of the porous support 2 is not particularly limited and is, for example, 10 μm or more, preferably 50 μm or more, and more preferably 100 μm or more. The thickness of the porous support 2 is, for example, 300 μm or less, and preferably 200 μm or less.

[0077] (Protective Layer) The protective layer, for example, covers the surface of the separation functional layer 1. The material of the protective layer is not particularly limited, and examples thereof include silicone resin. The material of the protective layer may be the same as or different from the material of the matrix of the separation functional layer 1. The thickness of the protective layer is not particularly limited, and is, for example, 0.5 μm or more, preferably 1 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more. The thickness of the protective layer is, for example, 100 μm or less, preferably 50 μm or less, and more preferably 30 μm or less.

[0078] (Method for producing pervaporation membrane) The pervaporation membrane 11 can be produced, for example, by forming a separation function layer 1 on a porous support 2. In detail, first, a coating liquid containing the material of the separation function layer 1 is prepared. The coating liquid may contain a filler as well as a dispersant for dispersing the filler in the coating liquid. For example, if the coating liquid contains a compound having a siloxane bond, the coating liquid may further contain a catalyst for curing the compound. Next, a coating membrane is obtained by applying the coating liquid onto the porous support 2. The coating membrane is dried to form the separation function layer 1. In this manner, the pervaporation membrane 11 is obtained.

[0079] <Embodiment of operating method of membrane separation device> The operating method of the membrane separation device of this embodiment includes supplying a fermentation liquor S containing volatile organic compounds to the membrane separation device, separating the fermentation liquor S into a permeate fluid S1 and a non-permeate fluid S2 by the pervaporation membrane 11, and discharging the non-permeate fluid S2 from the membrane separation device while preventing the non-permeate fluid S2 from flowing into the space 25 adjacent to the outer peripheral surface 15s of the membrane element 15.

[0080] The operating method of the membrane separation apparatus of this embodiment for the membrane separation apparatus 100 of embodiment 1 is carried out, for example, as follows. As shown in FIG. 1 , first, the fermentation liquor S is supplied into the interior of the membrane separation apparatus 100 through the port 21a (fermentation liquor inlet 13a). The fermentation liquor S is then supplied into the interior of the membrane element 15 through the upstream space 25a, and flows through the supply space parallel to the longitudinal direction of the central tube 16, coming into contact with one surface of the pervaporation membrane 11. With the fermentation liquor S in contact with one surface of the pervaporation membrane 11, the permeation space adjacent to the other surface of the pervaporation membrane 11 is depressurized. Specifically, the pressure inside the permeation space is reduced through the permeation fluid outlet 14b. By reducing the pressure inside the permeation space, a permeation fluid S1 having a high organic compound content can be obtained on the other surface of the pervaporation membrane 11. In other words, the permeation fluid S1 that has permeated the pervaporation membrane 11 is supplied to the permeation space. The permeate fluid S1 moves into the central tube 16 and is discharged to the outside of the membrane separation apparatus 100 through port 22b (permeate fluid outlet 14b). The gaseous permeate fluid S1 is cooled, for example, in a condensation section. As a result, the permeate fluid S1 is liquefied, and a liquid permeate fluid S1 is obtained. Meanwhile, the fermentation broth S (non-permeate fluid S2) that did not permeate the pervaporation membrane 11 is discharged to the outside of the membrane element 15. The non-permeate fluid S2 is then discharged to the outside of the membrane separation apparatus 100 through port 21b (non-permeate fluid outlet 13b). The non-permeate fluid S2 is typically a liquid. At this time, as shown in FIG. 1 , effluent S3 generated by the fermentation broth S flowing out from the outer peripheral surface 15s of the membrane element 15 flows into the space 25. The effluent S3 that has flowed into the space 25 flows along the space 25. The effluent S3 flowing through the space 25 prevents the non-permeated fluid S2 from flowing into the space 25 and stagnating inside the space 25. The effluent S3 that has flowed through the space 25 passes through the downstream space 25b and is discharged together with the non-permeated fluid S2 to the outside of the membrane separation device 100 through the port 21b (non-permeated fluid outlet 13b).

[0081] Figure 14 is a schematic cross-sectional view showing a membrane separation apparatus 200 equipped with a conventional spiral-type membrane element 35. In the conventional membrane separation apparatus 200, the outer peripheral surface 35s of the membrane element 35 is configured with a shell (not shown) made of a material that is impermeable to the aqueous solution s, and one end of the space 45 between the membrane element 35 and the casing 32 is sealed by a seal member 44 disposed in the space 45. The seal member 44 has a ring shape and surrounds the membrane element 35 in the circumferential direction. The seal member 44 is generally disposed at the downstream end (left side in Figure 14) of the membrane element 35.

[0082] 14 has a problem that, during operation, the non-permeated fluid s2 discharged from the downstream end face of the membrane element 35 flows back into the space 45 and remains inside the space 45. When the non-permeated fluid s2 remains in the space 45, unwanted microorganisms grow, which can deteriorate the sanitary condition inside the membrane separation apparatus 200. The deterioration of the sanitary condition inside the membrane separation apparatus 200 becomes a particular problem when a fermentation liquid containing volatile organic compounds is used as the aqueous solution s supplied to the membrane separation apparatus 200.

[0083] In contrast, in the operating method of the membrane separation apparatus of this embodiment, the non-permeated fluid S2 is discharged from the membrane separation apparatus so as not to flow into the space 25 adjacent to the outer peripheral surface 15s of the spiral membrane element 15. As shown in FIG. 1 , in the membrane separation apparatus 100 of Embodiment 1, during operation, the effluent S3 flows into the space 25 and along the space 25. That is, the space 25 forms the flow path of the effluent S3. This prevents the non-permeated fluid S2 from flowing into the space 25 and remaining inside the space 25 in the membrane separation apparatus 100. Therefore, the growth of unwanted microorganisms inside the membrane separation apparatus 100 is suppressed, and a deterioration in the sanitary condition inside the membrane separation apparatus 100 is suppressed.

[0084] Furthermore, in the membrane separation apparatus 100 of embodiment 1, during operation, the effluent S3 flows through the space 25, which facilitates heat transfer from the outside of the casing 12 to the membrane element 15, making it difficult for the temperature of the membrane element 15 to decrease. As a result, during operation, a decrease in the temperature of the membrane element 15 and a decrease in the performance of the pervaporation membrane 11 can be suppressed. The temperature of the effluent S3 is approximately the same as the temperature of the fermentation liquor S supplied to the supply space. As an example, the temperature of the fermentation liquor S supplied to the supply space is 15°C to 75°C.

[0085] The fermentation liquor S contains, for example, an organic compound as a fermented product and water. The organic compound contained in the fermentation liquor S is not particularly limited as long as it is volatile. In this specification, a "volatile organic compound" refers to an organic compound having a boiling point of 20°C to 260°C, preferably 50°C to 260°C, under atmospheric pressure (101.325 kPa). Note that, when the organic compound has a high concentration in an aqueous solution, for example, it generates an aqueous phase containing water as a main component and an organic phase having a higher organic compound content than the aqueous phase.

[0086] The number of carbon atoms in the organic compound is not particularly limited, and may be, for example, 10 or less, 8 or less, 6 or less, or even 4 or less. The lower limit of the number of carbon atoms in the organic compound may be 1 or 2. The organic compound has a functional group containing an oxygen atom, such as a hydroxyl group, a carbonyl group, an ether group, or an ester group. In the organic compound, the number of functional groups containing an oxygen atom is typically one.

[0087] Examples of organic compounds include alcohols, ketones, and esters. When the organic compound is an alcohol, it is highly compatible with water and is less likely to cause imbalances in the system environment. The alcohol may be an alkyl alcohol composed only of alkyl groups and hydroxyl groups, or an aryl alcohol containing aryl groups and hydroxyl groups. The alkyl alcohol may be linear, branched, or cyclic. Examples of alkyl alcohols in organic compounds include methanol, ethanol, n-propanol, isopropanol, n-butanol (BuOH), 2-butanol, isobutanol, t-butanol, and n-pentanol, with n-butanol being preferred. n-butanol is a compound that generates two phases (aqueous and organic) from an aqueous solution when its content in the aqueous solution is about 8 wt% or higher. Therefore, when the organic compound is n-butanol, for example, by adjusting the content of the organic compound in the permeating fluid to about 8 wt% or higher, an aqueous phase and an organic phase can be generated in the permeating fluid after liquefaction. In this case, the permeate can be easily purified by separating the aqueous and organic phases. Examples of aryl alcohols include phenol.

[0088] The ketone may be a dialkyl ketone composed only of an alkyl group and a carbonyl group. Examples of dialkyl ketones in organic compounds include methyl ethyl ketone (MEK) and acetone.

[0089] The ester may be a fatty acid alkyl ester composed only of an alkyl group and an ester group, such as ethyl acetate.

[0090] The organic compound is not limited to those mentioned above, and may be an aromatic hydrocarbon such as benzene, toluene, or xylene.

[0091] The fermentation liquor S may contain one type of organic compound or two or more types of organic compounds. The content of the organic compounds in the fermentation liquor S may be, for example, 50 wt % or less, 30 wt % or less, 10 wt % or less, 5 wt % or less, 2 wt % or less, or even 1 wt % or less. The lower limit of the content of the organic compounds is not particularly limited and may be, for example, 0.01 wt %.

[0092] In this embodiment, the organic compound is a fermentation product produced by fermenting a carbon source with a microorganism. That is, in this embodiment, the fermentation liquor S is a fermentation liquor containing the organic compound as a fermentation product.

[0093] In addition to water and organic compounds, the fermentation liquor S may further contain other components such as microorganisms involved in the production of the fermented product, a carbon source, a nitrogen source, inorganic ions, etc. The microorganisms involved in the production of the fermented product are typically bacteria. Examples of carbon sources include polysaccharides such as starch and monosaccharides such as glucose.

[0094] The amount of the fermentation liquor S supplied to the membrane separation device of this embodiment is not particularly limited and is determined depending on the processing capacity of the membrane separation device. The fermentation liquor S supplied to the supply space may be preheated. As described above, the temperature of the fermentation liquor S supplied to the supply space is 15°C to 75°C.

[0095] The pressure in the permeation space can be reduced by a pressure reducing device such as a vacuum pump. The pressure in the permeation space is, for example, 50 kPa or less, and may be 20 kPa or less, 10 kPa or less, 5 kPa or less, 3 kPa or less, or even 2 kPa or less. In this specification, unless otherwise specified, "pressure" means absolute pressure.

[0096] As described above, the pervaporation membrane included in the membrane separation apparatus of this embodiment allows preferential permeation of organic compounds contained in the fermentation liquor S. Therefore, the permeated fluid S1 obtained by operation of the membrane separation apparatus has a higher content of organic compounds than the fermentation liquor S supplied to the membrane separation apparatus.

[0097] After performing membrane separation operation for a certain period of time according to the above-described method for operating a membrane separation apparatus, a cleaning operation of the membrane separation apparatus may be performed. The cleaning operation of the membrane separation apparatus may be performed periodically.

[0098] According to the method for operating a membrane separation apparatus of this embodiment, for example, a permeated fluid S1 having a high content of organic compounds can be produced. In other words, according to the method for operating a membrane separation apparatus of this embodiment, organic compounds can be produced as the permeated fluid S1.

[0099] <Embodiment of Method for Producing Organic Compounds> The method for producing an organic compound of this embodiment includes supplying a fermentation liquor S to a membrane separation device, separating the fermentation liquor S into a permeate fluid S1 and a non-permeate fluid S2 using the pervaporation membrane 11 of a spiral membrane element 15, discharging the non-permeate fluid S2 from the membrane separation device while preventing the non-permeate fluid S2 from flowing into a space 25 adjacent to the outer surface 15s of the membrane element 15, and recovering the permeate fluid S1. In the method for producing an organic compound of this embodiment, the content of organic compounds in the permeate fluid S1 is higher than the content of organic compounds in the fermentation liquor S.

[0100] In the method for producing an organic compound of this embodiment, the organic compound may be an alcohol. According to the method for producing an organic compound of this embodiment, the alcohol can be efficiently separated from the fermentation liquor S containing a volatile alcohol.

[0101] [Embodiment 2] Figure 5 is a schematic cross-sectional view showing a membrane separation apparatus 101 of Embodiment 2. In the membrane separation apparatus 101 of Embodiment 2, the space 25 between the outer peripheral surface 15s of the membrane element 15 and the inner peripheral surface 12s of the casing 12 is sealed. That is, the above condition (1) is met in the membrane separation apparatus 101. Therefore, in the membrane separation apparatus 101, the non-permeated fluid S2 is prevented from flowing into the space 25. Therefore, the non-permeated fluid S2 is prevented from flowing into the space 25 and remaining inside the space 25. This suppresses the growth of unwanted microorganisms inside the membrane separation apparatus 101, thereby suppressing a deterioration in the sanitary condition inside the membrane separation apparatus 101.

[0102] In this specification, "the space 25 is sealed" means that the space 25 is filled or that the entrance and exit of the space 25 is blocked.

[0103] In the membrane separation apparatus 101 of the second embodiment, the outer peripheral surface 15s of the membrane element 15 is configured with a shell (not shown) made of a material that does not allow the fermentation liquor S to pass through. The shell may be made of fiber reinforced plastic (FRP). Therefore, in the membrane separation apparatus 101, unlike the membrane separation apparatus 100 of the first embodiment described above, the effluent S3 does not flow out from the outer peripheral surface 15s of the membrane element 15 during operation.

[0104] The membrane separation device 101 of the second embodiment includes a seal portion 24 disposed around the membrane element 15. The seal portion 24 seals a space 25.

[0105] In the membrane separation apparatus 101 of the second embodiment, the seal units 24 are arranged in two locations. That is, the membrane separation apparatus 101 uses two seal units 24 as the seal unit 24. The two seal units 24 seal one end and the other end of the space 25, in other words, the entrance and exit of the space 25. That is, the space 25 is separated from the upstream space 25a and the downstream space 25b by the two seal units 24.

[0106] As shown in Fig. 5, the two seal portions 24 are preferably disposed at the upstream end 15a and downstream end 15b of the membrane element 15, respectively. With such a configuration, it is easier to prevent the non-permeated fluid S2 from flowing into the space 25 and stagnating inside the space 25. The two seal portions 24 may also be disposed slightly downstream of the upstream end 15a of the membrane element 15 and slightly upstream of the downstream end 15b of the membrane element 15. Even with such a structure, the same effect is expected.

[0107] The seal portion 24 has a ring shape and circumferentially surrounds the membrane element 15. The seal portion 24 may be the same as the seal member 44 used in the conventional membrane separation device 200 shown in FIG.

[0108] Although not shown in the drawings, in the membrane separation device 101, end members may be attached to one or both axial ends of the membrane element 15. In this case, the two seal members 24 seal one end of the space 25 via the end member arranged at the upstream end 15a of the membrane element 15 and the end member arranged at the downstream end 15b of the membrane element 15.

[0109] Although not shown, in the membrane separation device 101, the space 25 may be filled with a highly thermally conductive material. With this structure, heat from outside the casing 12 is easily transferred to the membrane element 15, making it less likely for the temperature of the membrane element 15 to decrease. As a result, a decrease in the temperature of the membrane element 15 during operation, which would otherwise cause a decrease in the performance of the pervaporation membrane 11, can be prevented. Examples of highly thermally conductive materials include water, ethylene glycol, ethanol, and thermal pastes such as CPU grease. The thermal paste may include, for example, a matrix and thermally conductive particles dispersed in the matrix. The matrix may include, for example, silicone. The conductive particles may include, for example, a metal such as aluminum. The highly thermally conductive material may be water. The thermal conductivity of the highly thermally conductive material is preferably 0.1 W / m·K or greater. The upper limit of the thermal conductivity of the highly thermally conductive material is not particularly limited. For example, the upper limit is 20.0 W / m·K.

[0110] The operating method of the membrane separation apparatus of this embodiment is carried out, for example, as follows for the membrane separation apparatus 101 of embodiment 2. As shown in FIG. 5 , first, the fermentation liquor S is supplied into the interior of the membrane separation apparatus 101 through port 21a (fermentation liquor inlet 13a). The fermentation liquor S is then supplied into the interior of the membrane element 15 through the upstream space 25a and comes into contact with one side of the pervaporation membrane 11. With the fermentation liquor S in contact with one side of the pervaporation membrane 11, the permeation space adjacent to the other side of the pervaporation membrane 11 is depressurized. This results in a permeated fluid S1. The permeated fluid S1 moves into the interior of the central tube 16 and is discharged to the outside of the membrane separation apparatus 101 through port 22b (permeated fluid outlet 14b). At this time, as shown in FIG. 5 , in the membrane separation apparatus 101, the space 25 is sealed by the seal portion 24, so that the non-permeated fluid S2 is prevented from flowing into the space 25 and remaining within the space 25. On the other hand, the fermentation liquor S (non-permeated fluid S2) that did not permeate the pervaporation membrane 11 is discharged to the outside of the membrane element 15. Thereafter, the non-permeated fluid S2 passes through the downstream space 25b and is discharged to the outside of the membrane separation device 101 through the port 21b (non-permeated fluid outlet 13b).

[0111] [Embodiment 3] Figure 6 is a schematic cross-sectional view showing a membrane separation apparatus 102 of embodiment 3. In the membrane separation apparatus 102 of embodiment 3, the space 25 is sealed by being filled with a filler 27. That is, in the membrane separation apparatus 102, the above condition (1) is met. In other words, the space 25 is filled with the filler 27. That is, the space 25 is separated from the upstream space 25a and the downstream space 25b by the filler 27. Therefore, in the membrane separation apparatus 102, the non-permeated fluid S2 is prevented from flowing into the space 25.

[0112] As shown in Fig. 6, the filler 27 is preferably filled between the upstream end 15a and the downstream end 15b of the membrane element 15. With such a configuration, it is easier to prevent the non-permeated fluid S2 from flowing into the space 25 and stagnating inside the space 25. The filler 27 may also be filled between slightly downstream of the upstream end 15a of the membrane element 15 and slightly upstream of the downstream end 15b of the membrane element 15. Even with such a structure, the same effect is expected.

[0113] The filler 27 has a ring shape and surrounds the membrane element 15 in the circumferential direction. The membrane element 15 is fixed to the inner peripheral surface 12s of the casing 12 by the filler 27. The materials listed as having high thermal conductivity in embodiment 2 may be used as the filler 27. With this structure, heat from outside the casing 12 is easily transferred to the membrane element 15, so the temperature of the membrane element 15 is less likely to drop. As a result, a drop in the temperature of the membrane element 15 during operation, which would otherwise cause a decrease in the performance of the pervaporation membrane 11, can be suppressed. Commercially available fillers may be used as the filler 27.

[0114] Although not shown, in the membrane separation device 102, end members may be attached to one or both axial ends of the membrane element 15. In this case, the space 25 adjacent to the outer peripheral surface 15s of the membrane element 15, including the outer peripheral surface of the end member, may be filled with a filler 27.

[0115] The operation method of the membrane separation apparatus 102 of the third embodiment is carried out in the same manner as the operation method of the membrane separation apparatus 101 of the second embodiment described above.

[0116] [Embodiment 4] Figure 7 is a schematic cross-sectional view showing a membrane separation apparatus 103 of embodiment 4. In the membrane separation apparatus 103 of embodiment 4, the seal portion 24 is a casting agent 24a. The membrane separation apparatus 103 has the same structure as the membrane separation apparatus 101, except that the casting agent 24a is used as the seal portion 24. That is, the membrane separation apparatus 103 satisfies the above condition (1). In other words, the space 25 is separated from the upstream space 25a and the downstream space 25b by the casting agent 24a. Therefore, in the membrane separation apparatus 103, the non-permeated fluid S2 is prevented from flowing into the space 25.

[0117] In the membrane separation device 103, the casing 12 and the membrane element 15 are integrated with each other by the casting agent 24a. In this specification, "integrated" means that the components cannot be separated from each other without destruction.

[0118] 7, the casting agent 24a is preferably disposed at the upstream end 15a and the downstream end 15b of the membrane element 15. With such a configuration, it is easier to prevent the non-permeated fluid S2 from flowing into the space 25 and remaining inside the space 25. For example, urethane resin, epoxy resin, etc. can be used as the casting agent 24a.

[0119] Although not shown in the drawings, in the membrane separation apparatus 103, end members may be attached to one or both axial ends of the membrane element 15. In this case, the upstream and downstream casting agents 24a seal one end of the space 25 via the end member arranged at the upstream end 15a of the membrane element 15 and the end member arranged at the downstream end 15b of the membrane element 15.

[0120] The operation method of the membrane separation apparatus 103 of the fourth embodiment is carried out in the same manner as the operation method of the membrane separation apparatus 101 of the second embodiment described above.

[0121] 8 is a schematic cross-sectional view showing a membrane separation apparatus 104 of embodiment 5. In the membrane separation apparatus 104 of embodiment 5, the seal part 24 has a through-hole 24h through which the fermentation liquor S flows into the space 35. That is, the membrane separation apparatus 104 has a structure in which the space 25 is not sealed by the seal part 24.

[0122] As shown in Figure 8, in the membrane separation apparatus 104 of embodiment 5, a portion of the fermentation liquor S to be supplied to the membrane element 15 flows into the space 25 through the through-hole 24h of the seal portion 24. The fermentation liquor S that flows into the space 25 flows along the space 25. That is, in the membrane separation apparatus 104, the above-mentioned condition (2) is met. More specifically, in the membrane separation apparatus 104, the space 25 forms a flow path for the fermentation liquor S. The fermentation liquor S that flows through the space 25 is discharged from the non-permeated fluid outlet 13b together with the fermentation liquor S that did not permeate the pervaporation membrane 11 of the membrane element 15 (non-permeated fluid S2). Therefore, in the membrane separation apparatus 104, the non-permeated fluid S2 flows into the space 25 and is prevented from stagnation within the space 25.

[0123] 8, in the membrane separation device 104 of the fifth embodiment, the fermentation liquor S flows through the space 25 during operation, which facilitates heat transfer from the outside of the casing 12 to the membrane element 15, making it difficult for the temperature of the membrane element 15 to decrease. As a result, a decrease in the temperature of the membrane element 15 during operation, which would otherwise cause a decrease in the performance of the pervaporation membrane 11, can be suppressed. The temperature of the fermentation liquor S is 15°C to 75°C, as described above.

[0124] The through holes 24h are provided so as to penetrate the seal portion 24 in the thickness direction. The number of through holes 24h is not particularly limited and may be one or two or more. A plurality of through holes 24h may be provided in the seal portion 24 at predetermined intervals along the circumferential direction of the seal portion 24. The number of rows of the plurality of through holes 24h provided along the circumferential direction of the seal portion 24 is not particularly limited and may be one or two or more. When a plurality of through holes 24h are provided, the sum of the cross-sectional areas of the plurality of through holes 24h is preferably 50% or less of the cross-sectional area of ​​the seal portion 24. With this configuration, loss of the fermentation liquid S due to excessive flow of the fermentation liquid S into the space 25 can be suppressed.

[0125] In the membrane separation apparatus 104 of embodiment 5, the seal part 24 having the through hole 24h is arranged at the upstream end 15a of the membrane element 15. The position where the seal part 24 having the through hole 24h is arranged is not particularly limited. The seal part 24 having the through hole 24h may be arranged at the upstream end 15a or the downstream end 15b of the membrane element 15. The seal part 24 having the through hole 24h may be arranged at any position between the upstream end 15a and the flow-side end 15b of the membrane element 15.

[0126] The seal portion 24 having the through hole 24h may be arranged in two locations. Two seal portions 24 having the through hole 24h may be used as the seal portion 24. The two seal portions 24 having the through hole 24h may be arranged at the upstream end 15a and the downstream end 15b of the membrane element 15, respectively.

[0127] Although not shown in the drawings, in the membrane separation device 104, an end member may be attached to one or both axial ends of the membrane element 15. In this case, the seal part 24 having the through-hole 24h forms a flow path via the end member arranged at the upstream end 15a of the membrane element 15 without sealing one end of the space 25.

[0128] The operating method of the membrane separation apparatus of this embodiment is carried out, for example, as follows for the membrane separation apparatus 104 of embodiment 5. First, as shown in FIG. 8 , the fermentation liquor S is supplied into the interior of the membrane separation apparatus 104 through port 21a (fermentation liquor inlet 13a). The fermentation liquor S is then supplied into the interior of the membrane element 15 through the upstream space 25a and comes into contact with one surface of the pervaporation membrane 11. With the fermentation liquor S in contact with one surface of the pervaporation membrane 11, the permeation space adjacent to the other surface of the pervaporation membrane 11 is depressurized. This results in a permeated fluid S1. The permeated fluid S1 moves into the interior of the central tube 16 and is discharged to the outside of the membrane separation apparatus 104 through port 22b (permeated fluid outlet 14b). Meanwhile, the fermentation liquor S that does not permeate the pervaporation membrane 11 (non-permeated fluid S2) is discharged to the outside of the membrane element 15. Thereafter, the non-permeated fluid S2 is discharged to the outside of the membrane separation device 104 through the port 21b (non-permeated fluid outlet 13b). At this time, as shown in FIG. 8 , a portion of the fermentation liquor S to be supplied to the membrane element 15 flows into the space 25 through the through-hole 24h of the seal portion 24 and flows along the space 25. That is, the space 25 forms a flow path for the fermentation liquor S. The fermentation liquor S flowing through the space 25 prevents the non-permeated fluid S2 from flowing into the space 25 and stagnating inside the space 25. The fermentation liquor S that has flowed through the space 25 passes through the downstream space 25b together with the non-permeated fluid S2 and is discharged to the outside of the membrane separation device 104 through the port 21b (non-permeated fluid outlet 13b).

[0129] 9 is a schematic cross-sectional view showing a membrane separation apparatus 105 of embodiment 6. In the membrane separation apparatus 105 of embodiment 6, the casing 12 has an opening 12i and an opening 12o that communicate between the space 25 and the outside of the membrane separation apparatus 105. The membrane separation apparatus 105 has the same structure as the membrane separation apparatus 101, except that the casing 12 has the opening 12i and the opening 12o.

[0130] The openings 12 i and 12 o are formed in the casing 12 at positions facing the space 25 .

[0131] The opening 12i functions as an inlet for the heat medium M. That is, in the membrane separation device 105, the above condition (2) is satisfied. More specifically, in the membrane separation device 105, the space 25 forms a flow path for the heat medium M. Therefore, in the membrane separation device 105, the non-permeating fluid S2 is prevented from flowing into the space 25. The opening 12i may be connected to a heat medium supply path (not shown) for supplying the heat medium M to the space 25. The opening 12o functions as an outlet for the heat medium M. The opening 12o may be connected to a heat medium discharge path (not shown) for discharging the heat medium M from the space 25. With this structure, the heat medium M flows through the space 25, allowing the membrane element 15 to be easily heated. This prevents a decrease in the temperature of the membrane element 15 and a decrease in the performance of the pervaporation membrane 11 during operation.

[0132] 9 , the heat medium M is introduced into the space 25 through the opening 12i. The heat medium M introduced into the space 25 exchanges heat with the membrane elements 15 via the outer peripheral surfaces 15s of the membrane elements 15, heating the membrane elements 15. The heat medium M that has exchanged heat with the membrane elements 15 is discharged from the space 25 through the opening 12o. The heat medium discharge path may be connected to the heat medium supply path, and the heat medium M may be configured to circulate through the heat medium supply path, the space 25, and the heat medium discharge path.

[0133] The heat medium M is typically hot water. However, the heat medium M may also be steam (e.g., water vapor). The steam may be used under a pressure equal to or higher than the atmospheric pressure of the surrounding environment, or may be used under a pressure lower than the atmospheric pressure of the surrounding environment. In this specification, steam used under a pressure lower than the atmospheric pressure of the surrounding environment may be referred to as vacuum steam. The temperature of the heat medium M may be approximately the same as the temperature of the fermentation liquor S supplied to the membrane separation device 105.

[0134] [Embodiment 7] Figure 10 is a schematic cross-sectional view showing a membrane separation apparatus 106 of embodiment 7. In the membrane separation apparatus 106 of embodiment 7, the casing 12 has a plurality of openings 12i and a plurality of openings 12o. The membrane separation apparatus 106 has the same structure as the membrane separation apparatus 105, except that the casing 12 has a plurality of openings 12i and a plurality of openings 12o. That is, the membrane separation apparatus 106 satisfies the above condition (2). More specifically, in the membrane separation apparatus 106, the space 25 forms a flow path for the heat transfer medium M. Therefore, in the membrane separation apparatus 106, the non-permeated fluid S2 is prevented from flowing into the space 25.

[0135] According to the membrane separation device 106 of the seventh embodiment, the heat medium M can be introduced more evenly into the space 25 and can also be discharged more evenly from the space 25. Therefore, the membrane elements 15 can be heated evenly.

[0136] The arrangement of the plurality of openings 12i and the plurality of openings 12o is not particularly limited. As shown in Fig. 10, the plurality of openings 12i and the plurality of openings 12o may be evenly formed in the casing 12 at a position facing the space 25. The number of openings 12i and the number of openings 12o are not particularly limited. For example, the casing 12 may be configured so that the position facing the space 25 has a mesh structure, thereby providing the plurality of openings 12i and the plurality of openings 12o.

[0137] [Embodiment 8] Figure 11 is a schematic cross-sectional view showing a membrane separation apparatus 107 of embodiment 8. The membrane separation apparatus 107 of embodiment 8 has an end member 18 attached to at least 15a of the membrane element 15, and the end member 18 has a through-hole 18h through which the fermentation liquor S flows into the space 35. As described above, the membrane separation apparatus 107 has the same structure as the membrane separation apparatus 104, except that the end member 18 has the through-hole 18h instead of the seal portion 24. That is, the membrane separation apparatus 107 satisfies the above condition (2). More specifically, in the membrane separation apparatus 107, the space 25 forms a flow path for the fermentation liquor S.

[0138] 11 , in the membrane separation apparatus 107 of embodiment 8, a portion of the fermentation liquor S to be supplied to the membrane element 15 flows into the space 25 through the through-holes 18h of the end member 18. The fermentation liquor S that flows into the space 25 flows along the space 25. That is, the space 25 forms a flow path for the fermentation liquor S. The fermentation liquor S that flows through the space 25 is discharged from the non-permeated fluid outlet 13b together with the fermentation liquor S that did not permeate the pervaporation membrane 11 of the membrane element 15 (non-permeated fluid S2). Therefore, in the membrane separation apparatus 107, the non-permeated fluid S2 flows into the space 25 and is prevented from stagnation within the space 25.

[0139] 11 , in the membrane separation device 107 of the eighth embodiment, the fermentation liquid S flows through the space 25 during operation, which facilitates heat transfer from the outside of the casing 12 to the membrane element 15, and therefore the temperature of the membrane element 15 is less likely to decrease. As described above, the temperature of the fermentation liquid S is 15° C. to 75° C.

[0140] 1 and 5 to 11, in the membrane separation devices of Embodiments 1 to 8, the fermentation liquid inlet 13a, the non-permeated fluid outlet 13b, and the permeated fluid outlet 14b are provided in a direction parallel to the axis of the central tube 16. Therefore, the membrane separation devices of Embodiments 1 to 8 can be easily used by connecting them in series, either individually or in combination with each other.

[0141] <Embodiment of Membrane Separation System> Fig. 12 is a schematic configuration diagram showing an example of a membrane separation system 1000 of this embodiment. As shown in Fig. 12, the membrane separation system 1000 of this embodiment includes the membrane separation device of this embodiment described above as a membrane separation device. For convenience, the membrane separation device of this embodiment will be referred to as membrane separation device 100 below and in Fig. 12. The membrane separation system 1000 can perform the above-described operating method on the membrane separation device 100.

[0142] The membrane separation system 1000 further includes a tank 30 in addition to the membrane separation apparatus 100. The tank 30 stores a fermentation liquid S to be supplied to the membrane separation apparatus 100. The tank 30 is typically a fermenter for producing organic compounds by fermenting a carbon source with microorganisms.

[0143] The membrane separation system 1000 may further include a pressure reducing device 40. The pressure reducing device 40 can reduce the pressure inside the permeate space 14 of the membrane separation device 100. The pressure reducing device 40 is preferably a vacuum device such as a vacuum pump. The vacuum pump is typically a gas transport type vacuum pump, and examples thereof include a reciprocating vacuum pump and a rotary vacuum pump. Examples of reciprocating vacuum pumps include diaphragm type and swing piston type vacuum pumps. Examples of rotary vacuum pumps include liquid ring pumps; oil rotary pumps (rotary pumps); mechanical booster pumps; and various dry pumps such as roots type, claw type, screw type, turbo type, and scroll type. The pump serving as the pressure reducing device 40 may be equipped with a variable speed mechanism for changing the rotation speed, etc. An example of the variable speed mechanism is an inverter that drives the pump motor. By controlling the rotation speed, etc. of the pump using the variable speed mechanism, the pressure in the supply space 13 of the membrane separation device 100 can be appropriately adjusted.

[0144] The membrane separation system 1000 may further include a recovery unit 50 for recovering the permeated fluid S1. The recovery unit 50 recovers the permeated fluid S1 sent from the membrane separation device 100 and can store the permeated fluid S1, for example. The recovery unit 50 is, for example, a tank for storing the permeated fluid S1.

[0145] The membrane separation system 1000 further includes a fermentation liquid supply path 71 , a permeate fluid discharge path 72 , and a non-permeate fluid discharge path 73 .

[0146] The fermentation liquid supply path 71 is connected to the fermentation liquid outlet (outlet 31) of the tank 30 and the fermentation liquid inlet (inlet 13a) of the membrane separation device 100, and is a path for supplying the fermentation liquid S from the tank 30 to the membrane separation device 100. A pump for controlling the flow rate of the fermentation liquid S may be disposed in the fermentation liquid supply path 71, and a sensor for measuring the content of organic compounds in the fermentation liquid S may be disposed in the fermentation liquid supply path 71.

[0147] The permeate discharge path 72 is connected to the permeate outlet (outlet 14b) of the membrane separation device 100 and the permeate inlet (inlet 51) of the recovery section 50, and is a path for sending the permeate fluid S1 from the membrane separation device 100 to the recovery section 50. A sensor for measuring the content of organic compounds in the permeate fluid S1 may be disposed in the permeate discharge path 72.

[0148] The non-permeated fluid discharge path 73 is connected to the non-permeated fluid outlet (outlet 13b) of the membrane separation device 100, and is a path for discharging the non-permeated fluid S2 from the membrane separation device 100. A sensor for measuring the content of organic compounds in the non-permeated fluid S2 may be disposed in the non-permeated fluid discharge path 73.

[0149] The non-permeated fluid discharge path 73 may be connected to the non-permeated fluid inlet (inlet 32) of the tank 30 and configured to send the non-permeated fluid S2 to the tank 30. That is, in the membrane separation system 1000, the non-permeated fluid S2 may be mixed with the fermentation liquor S in the tank 30 and circulated through the fermentation liquor supply path 71 and the non-permeated fluid discharge path 73. When the non-permeated fluid S2 is sent to the tank 30, the fermentation liquor S and the non-permeated fluid S2 are mixed in the tank 30, and the organic compound content of the fermentation liquor S decreases. When the tank 30 is a fermenter, the decrease in the organic compound content of the fermentation liquor S can prevent microbial fermentation from stopping, thereby enabling continuous production of a fermented product. Furthermore, since retention of the non-permeated fluid S2 is suppressed in the membrane separation device 100, the incorporation of impurities into the tank 30 due to retention can be suppressed. Furthermore, air is prevented from accumulating in the space 25 of the membrane separation device 100, so that air entrapment in the membrane separation device 100 can be suppressed.

[0150] The permeated fluid discharge path 72 may further be provided with a condensation section for condensing the permeated fluid S1. The condensation section is, for example, a heat exchanger for cooling the permeated fluid S1. The heat exchanger can cool and condense the gaseous permeated fluid S1. The heat exchanger is, for example, a gas-liquid heat exchanger that causes heat exchange between a cooling medium such as antifreeze and the gaseous permeated fluid S1. The condensation section may be located between the membrane separation device 10 and the pressure reduction device 40 (upstream of the pressure reduction device 40), or may be located between the pressure reduction device 40 and the recovery section 50 (downstream of the pressure reduction device 40).

[0151] The membrane separation system 1000 may further include a controller 60 that controls each component of the membrane separation system 1000. The controller 60 is, for example, a DSP (Digital Signal Processor) including an A / D conversion circuit, an input / output circuit, an arithmetic circuit, a storage device, etc. The controller 60 stores a program for appropriately operating the membrane separation system 1000. For example, the controller 60 can control the operation of the pressure reducing device 40, etc., to switch between membrane separation operation and cleaning operation.

[0152] Unless otherwise specified, each of the paths of the membrane separation system 1000 is made up of, for example, metal or resin piping.

[0153] <Modification of Membrane Separation Apparatus in Membrane Separation System> The membrane separation system 1000 of this embodiment may include a plurality of membrane separation apparatuses 100, and the plurality of membrane separation apparatuses 100 may be connected to each other in series or in parallel. In this specification, "a plurality of membrane separation apparatuses 10 connected to each other in series" refers to a configuration in which the plurality of membrane separation apparatuses 100 are connected to each other so that the fermentation liquor S (non-permeated fluid S2) discharged from the supply space 13 of the membrane element 15 of the membrane separation apparatus 100 in the upstream stage is supplied to the supply space 13 of the membrane element 15 of the membrane separation apparatus 100 in the downstream stage. "A plurality of membrane separation apparatuses 100 connected to each other in parallel" refers to a configuration in which the plurality of membrane separation apparatuses 100 are connected to each other so that the fermentation liquor S sent from the tank 30 is supplied to the supply space 13 of the membrane element 15 of each of the plurality of membrane separation apparatuses 100. The number of membrane separation apparatuses 100 in the membrane separation system 100 is not particularly limited and may be, for example, 2 to 5. A modified example of the membrane separation system 1000 will now be described in detail with reference to FIGS. 13A and 13B.

[0154] (Variation 1) FIG. 13A is a schematic diagram showing a variation 1 of the membrane separation system 1000 of this embodiment. The membrane separation system 1001 of Variation 1 includes two membrane separation devices 100A and 100B connected in series. The membrane separation devices 100A and 100B are connected by piping. The membrane separation system 1001 has the same configuration as the membrane separation system 1000, except for the inclusion of two membrane separation devices 100A and 100B. Therefore, elements common to the above-described membrane separation system 1000 and the membrane separation system 1001 of Variation 1 are given the same reference numerals, and their description may be omitted. In other words, the descriptions of each embodiment can be mutually applied unless there is a technical contradiction. Furthermore, each embodiment may be mutually combined unless there is a technical contradiction.

[0155] As described above, in the membrane separation system 1001, the membrane separation apparatuses 100A and 100B are connected in series. Specifically, the membrane separation system 1001 further includes a connection path 74 that connects the membrane separation apparatuses 100A and 100B to each other. The connection path 74 is connected to the non-permeated fluid outlet 13b of the membrane separation apparatus 100A and the fermented fluid inlet 13a of the membrane separation apparatus 100B. The fermented fluid inlet 13a of the membrane separation apparatus 100A is connected to a fermented fluid supply path 71, and the non-permeated fluid outlet 13b of the membrane separation apparatus 100B is connected to a non-permeated fluid discharge path 73.

[0156] The permeate discharge path 72 has a first portion 72A and a second portion 72B. The first portion 72A is connected to the permeate outlet 14b of the membrane separation device 100A, and the second portion 72B is connected to the permeate outlet 14b of the membrane separation device 100B. The first portion 72A and the second portion 72B are joined at a joining position 75.

[0157] For example, two pressure reducing devices 40A and 40B are disposed in the permeate discharge path 72. The pressure reducing device 40A is located between the membrane separation apparatus 100A and the confluence position 70 and can reduce the pressure in the permeate space 14 of the membrane element 15 included in the membrane separation apparatus 100A. The pressure reducing device 40B is located between the membrane separation apparatus 100B and the confluence position 70 and can reduce the pressure in the permeate space 14 of the membrane element 15 included in the membrane separation apparatus 100B. However, a single pressure reducing device may be disposed in the permeate discharge path 72, and this pressure reducing device may be located between the confluence position 70 and the recovery section 50. In other words, a single pressure reducing device may be shared by the membrane separation apparatuses 100A and 100B.

[0158] In the membrane separation system 1001, the pervaporation membrane 11A of the membrane element 15 included in the membrane separation apparatus 100A may be the same as or different from the pervaporation membrane 11B of the membrane element 15 included in the membrane separation apparatus 100B, except for the membrane area. 2 ) relative to the membrane area (m 2 The ratio of

[0159] As an example, the membrane separation system 1001 can be operated by the following method: First, a pump (not shown) is operated to supply the fermented liquid S from the tank 30 to the membrane separation apparatus 100A, and then the fermented liquid S is supplied from the membrane separation apparatus 100A to the membrane separation apparatus 100B. This allows the fermented liquid S to come into contact with the pervaporation membrane 11A of the membrane element 15 provided in the membrane separation apparatus 100A and the pervaporation membrane 11B of the membrane element 15 provided in the membrane separation apparatus 100B.

[0160] Next, the permeate space 14 of the membrane element 15 in the membrane separation apparatus 100A is depressurized through the permeate fluid outlet 14b, and the permeate space 14 of the membrane element 15 in the membrane separation apparatus 100B is depressurized through the permeate fluid outlet 14b. This allows membrane separation operation to be performed in both the membrane separation apparatuses 100A and 100B, and permeate fluid S1 can be obtained from each of the membrane separation apparatuses 100A and 100B. The fermentation liquor S (non-permeate fluid S2) treated in the membrane separation apparatus 100A is sent to the membrane separation apparatus 100B through the connecting path 74, and is further treated in the membrane separation apparatus 100B.

[0161] Next, the pressure in the permeate space 14 of at least one of the membrane elements 15 of the membrane separation apparatus 100A and the membrane elements 15 of the membrane separation apparatus 100B is increased, and the membrane separation operation is terminated.

[0162] (Variation 2) Figure 13B is a schematic diagram showing a variation 2 of the membrane separation system 1000 of this embodiment. The membrane separation system 1002 of variation 2 includes two membrane separation devices 100A and 100B connected in parallel to each other. The membrane separation devices 100A and 100B are connected by piping. The membrane separation system 1002 has the same configuration as the membrane separation system 100, except that it includes two membrane separation devices 100A and 100B.

[0163] As described above, in the membrane separation system 1002, the membrane separation apparatuses 100A and 100B are connected in parallel to each other. Specifically, the fermentation liquid supply path 71 has a first portion 71A and a second portion 71B. The first portion 71A of the fermentation liquid supply path 71 is connected to the fermentation liquid inlet 13a of the membrane separation apparatus 100A, and the second portion 71B is connected to the fermentation liquid inlet 13a of the membrane separation apparatus 100B. The second portion 71B branches off from the first portion 71A at a branching position 76. The branching position 76 is located between the tank 30 and the membrane separation apparatus 100A.

[0164] Furthermore, the non-permeated fluid discharge path 73 has a first portion 73A and a second portion 73B. The first portion 73A of the non-permeated fluid discharge path 73 is connected to the non-permeated fluid outlet 13b of the membrane separation device 100A, and the second portion 73B is connected to the non-permeated fluid outlet 13b of the membrane separation device 100B. The first portion 73A and the second portion 73B are joined at a joining position 77. The joining position 77 is located, for example, between the tank 30 and the membrane separation device 100A.

[0165] Similar to the membrane separation system 1001 of Modification 1, the permeate discharge path 72 has a first portion 72A and a second portion 72B. The first portion 72A is connected to the permeate outlet 14b of the membrane separation device 100A, and the second portion 72B is connected to the permeate outlet 14b of the membrane separation device 100B. The first portion 72A and the second portion 72B are joined at a joining position 75.

[0166] For example, two pressure reducing devices 40A and 40B are disposed in the permeate discharge path 72. The pressure reducing device 40A is located between the membrane separation apparatus 100A and the confluence position 75 and can reduce the pressure in the permeate space 14 of the membrane element 15 included in the membrane separation apparatus 100A. The pressure reducing device 40B is located between the membrane separation apparatus 100B and the confluence position 75 and can reduce the pressure in the permeate space 14 of the membrane element 15 included in the membrane separation apparatus 100B. However, a single pressure reducing device may be disposed in the permeate discharge path 72, and this pressure reducing device may be located between the confluence position 75 and the recovery section 50. In other words, a single pressure reducing device may be shared by the membrane separation apparatuses 100A and 100B.

[0167] In the membrane separation system 1002, the pervaporation membrane 11A of the membrane element 15 included in the membrane separation apparatus 100A may be the same as or different from the pervaporation membrane 11B of the membrane element 15 included in the membrane separation apparatus 100B. 2 ) relative to the membrane area (m 2 The ratio of

[0168] As an example, the membrane separation system 1002 can be operated by the following method: First, a pump (not shown) is operated to supply the fermentation liquor S from the tank 30 to each of the membrane separation apparatuses 100A and 100B. This allows the fermentation liquor S to come into contact with the pervaporation membrane 11A of the membrane element 15 included in the membrane separation apparatus 100A and the pervaporation membrane 11B of the membrane element 15 included in the membrane separation apparatus 100B.

[0169] Next, the permeate space 14 of the membrane element 15 provided in the membrane separation apparatus 100A is depressurized through the permeate fluid outlet 14b, and the permeate space 14 of the membrane element 15 provided in the membrane separation apparatus 100B is depressurized through the permeate fluid outlet 14b. This allows membrane separation operation to be performed in both the membrane separation apparatuses 100A and 100B, and permeate fluid S1 can be obtained from each of the membrane separation apparatuses 100A and 100B.

[0170] Next, the pressure in the permeate space 14 of at least one of the membrane elements 15 of the membrane separation apparatus 10A and the membrane elements 15 of the membrane separation apparatus 10B is increased, and the membrane separation operation is terminated.

[0171] The membrane separation system of this embodiment is suitable for efficiently separating volatile organic compounds from a fermentation broth containing the organic compounds.

Claims

1. A membrane separation apparatus equipped with a spiral-type membrane element, wherein the membrane element comprises a central tube having through-holes, and a membrane leaf having a pervaporation membrane that separates a fermentation liquid containing volatile organic compounds into a permeate fluid and a non-permeate fluid, the membrane leaf being wound around the central tube, and wherein, during operation, the non-permeate fluid is prevented from flowing into a space adjacent to the outer peripheral surface of the membrane element.

2. A membrane separation device equipped with a spiral-type membrane element, wherein the membrane element includes a central tube having through-holes and a membrane leaf wound around the central tube, the membrane leaf having a pervaporation membrane that separates a fermentation liquid containing volatile organic compounds into a permeate fluid and a non-permeate fluid, and wherein the following condition (1) or (2) is met: (1) The space adjacent to the outer peripheral surface of the membrane element is sealed. (2) The space adjacent to the outer peripheral surface of the membrane element forms a flow path for a fluid other than the non-permeate fluid.

3. A membrane separation device according to claim 1 or 2, wherein the outer peripheral surface of the membrane element is made of a flow path material.

4. The membrane separation device according to claim 1 or 2, further comprising a seal portion disposed around the periphery of the membrane element.

5. The membrane separation device according to claim 4, wherein the sealing portion has a through-hole for allowing the fermentation liquid to flow into the space.

6. The membrane separation device according to claim 4, wherein the space is sealed by two of the sealing portions.

7. The membrane separation device according to claim 6, wherein the sealing portion contains a casting agent.

8. The membrane separation device according to claim 1 or 2, wherein the space is sealed by filling the space with a filler.

9. A membrane separation device according to claim 1 or 2, wherein the space is filled with a material having a thermal conductivity of 0.1 W / m·K or more.

10. A membrane separation device according to claim 1 or 2, wherein the membrane element is configured to be detachable from the casing.

11. A membrane separation system comprising the membrane separation device according to claim 1 or 2.

12. The membrane separation system according to claim 11, further comprising a tank for storing the fermentation liquid to be supplied to the membrane separation device.

13. The membrane separation system according to claim 11, wherein the membrane separation system includes a plurality of the membrane separation devices, and the plurality of membrane separation devices are connected to each other in series or in parallel.

14. A method for operating a membrane separation apparatus equipped with a spiral-type membrane element, wherein the membrane element includes a central tube having through holes and a membrane leaf having a pervaporation membrane and wound around the central tube, the method comprising: supplying a fermentation liquid containing volatile organic compounds to the membrane separation apparatus; separating the fermentation liquid into a permeate fluid and a non-permeate fluid by the pervaporation membrane; and discharging the non-permeate fluid from the membrane separation apparatus while preventing the non-permeate fluid from flowing into a space adjacent to the outer peripheral surface of the membrane element.