Membrane separation device, membrane separation system, end member for spiral membrane element, and method for operating membrane separation system

Abstract

A membrane separation device 100 comprises: a filter member 10 having a filtration part 11 that separates a feed fluid F1 containing solids into a filtered fluid F2 and a non-filtered fluid F3; and a spiral membrane element 20 to which the filtered fluid F2 is fed. The membrane element 20 includes: a central tube 23 having through holes 23h; and a membrane leaf 24 that includes a separation membrane 24a and is wrapped around the central tube 23.

Description

Membrane separation device, membrane separation system, end member for spiral membrane element, and method for operating membrane separation system

[0001] The present invention relates to a membrane separation apparatus, a membrane separation system, an end member for a spiral-wound membrane element, and a method for operating a membrane separation system.

[0002] Membrane separation methods using separation membranes have been developed as methods for separating a solvent or a volatile organic compound from a solution containing the solvent or the organic compound, or for separating an acidic gas such as carbon dioxide from a mixed gas containing the acidic gas.

[0003] For example, a membrane separation device equipped with a spiral membrane element is used in membrane separation methods (see, for example, Patent Document 1). The spiral membrane element includes an element body including a central tube and membrane leaves wound around the central tube. The membrane leaves include a separation membrane. A feed fluid supplied to the membrane separation device typically passes through an upstream end member and is then separated into a permeate fluid and a non-permeate fluid by the separation membrane. The permeate fluid is discharged through the central tube, and the non-permeate fluid is discharged through a downstream end member.

[0004] Japanese Patent Application Laid-Open No. 2002-095931

[0005] The feed fluid supplied to the above-described membrane separation apparatus may contain solids such as suspended solids. When a feed fluid containing solids is supplied to a spiral membrane element, the feed-side inlet of the membrane element may be blocked or the separation membrane may become clogged, causing the fluid to stagnate inside the membrane separation apparatus. Since fluid stagnation inside the membrane separation apparatus hinders efficient membrane separation, it is desirable to minimize this stagnation.

[0006] An object of the present invention is to provide a membrane separation device suitable for suppressing fluid retention inside the membrane separation device.

[0007] The present invention provides a membrane separation device comprising: a filtration member having a filtration section that separates a feed fluid containing solids into a filtrate fluid and a non-filtrate fluid; and a spiral membrane element to which the filtrate fluid is supplied.

[0008] In another aspect, the present invention provides a membrane separation system including the membrane separation device of the present invention.

[0009] In yet another aspect, the present invention provides an end member for a spiral-wound membrane element, the end member being disposed at the end of the spiral-wound membrane element on the feed side in the axial direction, and comprising a filtration section that separates a feed fluid containing solids into a filtrate fluid and a non-filtrate fluid.

[0010] In yet another aspect, the present invention provides a method for operating a membrane separation system equipped with a membrane separation device including a filtration element having a filtration section that separates a feed fluid containing solids into a filtrate fluid and a non-filtrate fluid, and a spiral membrane element to which the filtrate fluid is supplied, the method comprising: separating the feed fluid into the filtrate fluid and the non-filtrate fluid by the filtration section of the filtration element; and separating the filtrate into a permeate fluid and a non-permeate fluid by the membrane element.

[0011] According to the present invention, it is possible to provide a membrane separation device suitable for suppressing retention of fluid inside the membrane separation device.

[0012] FIG. 1 is a schematic cross-sectional view showing an example of a membrane separation apparatus of embodiment 1. FIG. 2 is a schematic cross-sectional view showing another example of a membrane separation apparatus of embodiment 1. FIG. 3 is an exploded perspective view showing a spiral membrane element. FIG. 4 is a schematic cross-sectional view of the spiral membrane element of FIG. 3. FIG. 5 is a schematic cross-sectional view of a separation membrane. FIG. 6 is a partially enlarged view of the membrane separation apparatus of FIG. 1 or FIG. 2. FIG. 7 is a schematic perspective view of a filtration member. FIG. 8 is a schematic perspective view of an end member. FIG. 9 is a schematic configuration diagram showing an example of a membrane separation system of embodiment 2. FIG. 10 is a schematic configuration diagram showing a membrane separation system of modified example 1. FIG. 11 is a diagram explaining an example of a flow rate adjustment process in the membrane separation system of modified example 1. FIG. 12 is a schematic configuration diagram showing a membrane separation system of modified example 2. FIG. 13 is a schematic configuration diagram showing a membrane separation system of modified example 3. FIG. 14 is a schematic cross-sectional view showing an example of a membrane separation apparatus equipped with a conventional spiral membrane element.

[0013] A membrane separation apparatus according to a first aspect of the present invention comprises: a filtration member having a filtration section that separates a feed fluid containing solids into a filtrate and a non-filtrate; and a spiral membrane element to which the filtrate is supplied.

[0014] In a second aspect of the present invention, for example, the membrane separation device according to the first aspect further includes a casing that houses the filtering member and the membrane element.

[0015] In a third aspect of the present invention, for example, in the membrane separation device according to the first or second aspect, a space adjacent to the outer peripheral surface of the membrane element forms a flow path for the non-filtrate fluid.

[0016] In a fourth aspect of the present invention, for example, in the membrane separation device according to any one of the first to third aspects, the filtration member has a filtration flow path through which the filtrate fluid flows and a non-filtration flow path through which the non-filtration fluid flows, the filtration flow path communicates with a supply space located inside the membrane element, and the non-filtration flow path communicates with a space adjacent to the outer peripheral surface of the membrane element.

[0017] In a fifth aspect of the present invention, for example, in the membrane separation device according to any one of the first to fourth aspects, the filtration member has a convex portion that protrudes in the axial direction of the membrane element, and the filtration portion is disposed on at least a part of a side surface of the convex portion.

[0018] In a sixth aspect of the present invention, for example, in the membrane separation device according to any one of the first to fifth aspects, the filtration section includes a porous member.

[0019] In a seventh aspect of the present invention, for example, the membrane separation device according to any one of the first to sixth aspects further comprises an end member arranged at a supply-side end in the axial direction of the membrane element, and the end member includes the filtration member.

[0020] In an eighth aspect of the present invention, for example, in the membrane separation device according to any one of the first to seventh aspects, the membrane element includes a central tube having through holes, and a membrane leaf having a separation membrane and wound around the central tube.

[0021] In a ninth aspect of the present invention, for example, in the membrane separation device according to the eighth aspect, the feed fluid is a solution containing at least one selected from the group consisting of a solvent and a volatile organic compound, and the separation membrane is a pervaporation membrane.

[0022] A membrane separation system according to a tenth aspect of the present invention includes the membrane separation device according to any one of the first to ninth aspects.

[0023] In an eleventh aspect of the present invention, for example, the membrane separation system according to the tenth aspect further includes an adjusting mechanism that adjusts the flow rate of the filtrate supplied to the membrane element.

[0024] An end member for a spiral-wound membrane element according to a twelfth aspect of the present invention is an end member that is disposed at the end of the spiral-wound membrane element on the feed side in the axial direction, and is provided with a filtration section that separates a feed fluid containing solids into a filtrate and a non-filtrate.

[0025] In a thirteenth aspect of the present invention, for example, in the end member according to the twelfth aspect, the space adjacent to the outer peripheral surface of the membrane element forms a flow path for the non-filtrate fluid.

[0026] In a fourteenth aspect of the present invention, for example, the end member according to the twelfth or thirteenth aspect has a filtration flow path through which the filtrate fluid flows and a non-filtration flow path through which the non-filtration fluid flows, the filtration flow path communicates with a supply space located inside the membrane element, and the non-filtration flow path communicates with a space adjacent to the outer peripheral surface of the membrane element.

[0027] In a fifteenth aspect of the present invention, for example, the end member according to any one of the twelfth to fourteenth aspects has a convex portion that protrudes in the axial direction of the membrane element, and the filtration portion is disposed on at least a part of the side surface of the convex portion.

[0028] In a sixteenth aspect of the present invention, for example, in the end member according to any one of the twelfth to fifteenth aspects, the filtration section includes a porous member.

[0029] A seventeenth aspect of the present invention relates to a method for operating a membrane separation system equipped with a membrane separation device including a filtration member having a filtration section that separates a feed fluid containing solids into a filtrate fluid and a non-filtrate fluid, and a spiral membrane element to which the filtrate fluid is supplied, the method comprising: separating the feed fluid into the filtrate fluid and the non-filtrate fluid by the filtration section of the filtration member; and separating the filtrate fluid into a permeate fluid and a non-permeate fluid by the membrane element.

[0030] In an eighteenth aspect of the present invention, for example, the method for operating a membrane separation system according to the seventeenth aspect further comprises gradually increasing the flow rate of the filtrate supplied to the membrane element.

[0031] In a nineteenth aspect of the present invention, for example, in the method of operating a membrane separation system according to the eighteenth aspect, gradually increasing the flow rate of the filtrate fluid includes at least one selected from the group consisting of (i) gradually increasing the pressure difference between the feed fluid and the non-permeated fluid, and (ii) gradually increasing the flow rate of the non-permeated fluid.

[0032] In a twentieth aspect of the present invention, for example, in the method of operating a membrane separation system according to the nineteenth aspect, the membrane separation system further comprises an adjustment mechanism for adjusting the flow rate of the filtrate fluid supplied to the membrane element, and in (i) above, the adjustment mechanism is controlled based on the monitoring results of the pressure of the supply fluid and the pressure of the non-permeated fluid, thereby gradually increasing the pressure difference between the supply fluid and the non-permeated fluid, and in (ii) above, the adjustment mechanism is controlled based on the monitoring results of the flow rate of the non-permeated fluid, thereby gradually increasing the flow rate of the non-permeated fluid.

[0033] In a 21st aspect of the present invention, for example, in the method of operating a membrane separation system according to any one of the 17th to 20th aspects, the membrane separation device further has a casing in which the filtration member and the membrane element are housed.

[0034] In a 22nd aspect of the present invention, for example, in the method of operating a membrane separation system according to any one of the 17th to 21st aspects, the membrane separation device further has an end member arranged at a supply-side end in the axial direction of the membrane element, and the end member includes the filtration member.

[0035] In a 23rd aspect of the present invention, for example, in a method for operating a membrane separation system according to any one of the 17th to 22nd aspects, the membrane element includes a central tube having through holes and a membrane leaf having a separation membrane and wound around the central tube.

[0036] In a 24th aspect of the present invention, for example, in the method of operating a membrane separation system according to the 23rd aspect, the feed fluid is a solution containing at least one selected from the group consisting of a solvent and a volatile organic compound, and the separation membrane is a pervaporation membrane.

[0037] 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.

[0038] [Embodiment 1] <Membrane Separation Apparatus> Fig. 1 is a schematic cross-sectional view showing an example of a membrane separation apparatus 100 of Embodiment 1. As shown in Fig. 1, the membrane separation apparatus 100 includes a filtration member 10 and a spiral membrane element 20. The filtration member 10 has a filtration section 11 that separates a feed fluid F1 containing solids into a filtrate fluid F2 and a non-filtrate fluid F3. The filtrate fluid F2 has a lower solids content than the non-filtrate fluid F3. The filtrate fluid F2 from which solids have been separated by the filtration section 11 is supplied to the membrane element 20. The membrane element 20 has a separation membrane that separates the filtrate fluid F2 into a permeate fluid F4 and a non-permeate fluid F5.

[0039] As described above, the feed fluid supplied to a membrane separation apparatus equipped with spiral membrane elements may contain solids such as suspended matter. If the feed fluid containing solids is directly supplied to the membrane elements, the feed-side inlet of the membrane elements may be blocked or the separation membranes may become clogged, causing the fluid to stagnate inside the membrane separation apparatus.

[0040] However, according to the membrane separation apparatus 100 of the first embodiment, even if the feed fluid F1 contains solids, the filtered fluid F2 from which the solids have been separated by the filtration section 11 of the filtration member 10 can be supplied to the membrane element 20. This makes it possible to suppress the accumulation of fluids such as the feed fluid F1 inside the membrane separation apparatus 100. As a result, efficient membrane separation can be performed.

[0041] In this embodiment, the supply fluid F1 may be a gas or a liquid. An example of the gas supply fluid F1 is a mixed gas containing an acidic gas, particularly a mixed gas containing carbon dioxide and nitrogen. An example of the liquid supply fluid F1 is a solution containing at least one selected from the group consisting of a solvent and a volatile organic compound. The supply fluid F1 may also be a solution containing at least one selected from the group consisting of a solvent and a volatile organic compound. Examples of solutions containing a solvent include waste liquids generated in various chemical processes. Examples of solutions containing volatile organic compounds include fermentation liquids.

[0042] The waste liquid may be, for example, a cleaning liquid used to clean an object to be cleaned, such as a separation membrane (e.g., an RO membrane), in a manufacturing process of the separation membrane, etc. The cleaning liquid contains, for example, a solvent (cleaning agent), impurities, and water.

[0043] The solvent is typically a lower alcohol. The lower alcohol is, for example, an alcohol having 5 or less carbon atoms. The lower alcohol may be a monohydric alcohol or a polyhydric alcohol. The lower alcohol may be linear or branched. Examples of lower alcohols include methanol, ethanol, n-propanol, isopropanol (IPA), n-butanol, 2-butanol, isobutanol, t-butanol, and n-pentanol, with IPA being preferred. The solvent content in the cleaning liquid is, for example, 50 wt % or less, preferably 30 wt % or less, and more preferably 10 wt % or less. The lower limit of the solvent content is not particularly limited and is, for example, 1 wt %.

[0044] The impurities are not particularly limited and may include, for example, organic compounds, and are preferably composed of organic compounds. However, the impurities may also include inorganic compounds. The impurities may be dissolved in the cleaning solution or may not be dissolved in the cleaning solution. The content of the impurities in the cleaning solution is, for example, 300 ppm or more, and may be 500 ppm or more. In this specification, "ppm" means parts per million by mass. The upper limit of the content of the impurities is not particularly limited and is, for example, 1 wt%.

[0045] The fermentation broth contains, for example, a fermented product as an organic compound and water. The organic compound contained in the fermentation broth is not particularly limited as long as it is volatile. In this specification, "volatile organic compound" means 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 content of organic compounds than the aqueous phase.

[0046] 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.

[0047] 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 permeated fluid F4 to about 8 wt% or higher, an aqueous phase and an organic phase can be generated in the permeated fluid F4 after liquefaction. In this case, the permeated fluid F4 can be easily purified by separating the aqueous and organic phases. Examples of the aryl alcohol include phenol.

[0048] 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.

[0049] The ester may be a fatty acid alkyl ester composed only of an alkyl group and an ester group, such as ethyl acetate.

[0050] The organic compound is not limited to those mentioned above, and may be an aromatic hydrocarbon such as benzene, toluene, or xylene.

[0051] The fermentation liquor 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 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%.

[0052] The organic compound may be a fermentation product produced by fermenting a carbon source with a microorganism, i.e., the fermentation liquid may be a fermentation liquid containing the organic compound as a fermentation product.

[0053] In addition to water and organic compounds, the fermentation broth 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.

[0054] Solids that may be contained in the liquid supply fluid F1 include, for example, suspended matter such as coarse residues. The presence of suspended matter may be significant when the liquid supply fluid F1 is a solution containing at least one selected from the group consisting of solvents and volatile organic compounds. For example, when such a solution is a cleaning solution used to clean an object to be cleaned, such as a separation membrane, suspended matter containing a large amount of impurities may be contained as solid matter. For example, when such a solution is a fermentation liquid using biomass as a raw material, the solution may contain biomass residues generated in the saccharification process as solid matter. Solid matter may accumulate, for example, at the inlet on the supply side of the membrane element 20, as scale, biofilm, etc. Solid matter that may be contained in the gas supply fluid F1 includes, for example, foreign matter such as dust.

[0055] The membrane separation device 100 further includes a casing 30 that houses the filtration member 10 and the membrane element 20. In this embodiment, the filtration member 10 and the membrane element 20 are housed in a single common casing 30.

[0056] Conventionally, as a countermeasure for a feed fluid containing solids, the solids have been removed from the feed fluid before membrane separation. However, this conventional method requires the installation of a pretreatment device upstream of the membrane separation device to remove the solids from the feed fluid, which can lead to a large system. In contrast, according to the membrane separation device 100 of the first embodiment, the filter member 10 and the membrane element 20 are housed in a single common casing 30, eliminating the need for a separate pretreatment device and allowing for a more compact system. The membrane separation device 100 has a simple configuration and can suppress the retention of fluids, such as the feed fluid F1, inside the membrane separation device 100.

[0057] FIG. 14 is a schematic cross-sectional view showing an example of a membrane separation apparatus equipped with a conventional spiral-type membrane element, as disclosed in Patent Document 1. In the conventional membrane separation apparatus 110 shown in FIG. 14, the outer peripheral surface 80s of the membrane element 80 is composed of an exterior material 84 made of a material that does not allow the feed fluid f1 to pass through, and one end of the space 85 between the membrane element 80 and the casing 90 is sealed by a seal member 83 disposed in the space 85. The space 85 is formed between the outer peripheral surface 80s of the membrane element 80 and the inner peripheral surface 90s of the casing 90. The seal member 83 has a ring shape and surrounds the membrane element 80 in the circumferential direction. The seal member 83 is generally disposed at the upstream end (left side in FIG. 14) of the membrane element 80.

[0058] 14 , in a conventional membrane separation apparatus 110, during operation, non-permeated fluid f5 discharged from the downstream end of the membrane element 80 may flow back into the space 85 and become stagnant inside the space 85. If non-permeated fluid f5 remains in the space 85, unwanted microorganisms may grow, which may deteriorate the sanitary condition inside the membrane separation apparatus 110. The deterioration of the sanitary condition inside the membrane separation apparatus 110 becomes a particular problem when a fermentation liquid containing volatile organic compounds is used as the feed fluid f1.

[0059] In contrast, in the membrane separation apparatus 100 of Embodiment 1, during operation, the non-permeated fluid F5 is prevented from flowing into the space 35 adjacent to the outer peripheral surface 20s of the membrane element 20. Specifically, as shown in FIG. 1 , the space 35 forms a flow path for the non-filtrate fluid F3. The space 35 is a space formed between the outer peripheral surface 20s of the membrane element 20 and the inner peripheral surface 30s of the casing 30. With this configuration, the non-permeated fluid F5 can be discharged from the membrane separation apparatus 100 so as not to flow into the space 35.

[0060] As shown in FIG. 1 , during operation of the membrane separation apparatus 100, a non-filtrate fluid F3 flows into the space 35 and along the space 35. That is, the space 35 constitutes a flow path for the non-filtrate fluid F3. The non-filtrate fluid F3 that flows through the space 35 merges with the non-permeated fluid F5 discharged from the membrane element 20 downstream of the membrane element 20. The merged fluid (non-treated fluid F6) is discharged from the membrane separation apparatus 100. As a result, in the membrane separation apparatus 100, the non-permeated fluid F5 is prevented from flowing back into the space 35 and remaining inside the space 35. 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.

[0061] 1, in the membrane separation apparatus 100, the non-filtered fluid F3 flows through the space 35 during operation, which facilitates heat transfer from the outside of the casing 30 to the membrane elements 20, making it difficult for the temperature of the membrane elements 20 to decrease. Therefore, for example, when the separation membrane is a pervaporation membrane, a decrease in the temperature of the membrane elements 20 during operation, which would otherwise cause a decrease in the performance of the pervaporation membrane, can be suppressed. As an example, when the feed fluid F1 is a fermentation broth, the temperature of the fermentation broth supplied to the filtration section 11 of the filtration member 10 is 15°C to 75°C.

[0062] The amount of the feed fluid F1 supplied to the membrane separation device 100 is not particularly limited and is determined depending on the processing capacity of the membrane separation device 100. The feed fluid F1 supplied to the membrane separation device 100 may be heated in advance.

[0063] 1 , the membrane separation apparatus 100 may further include a seal member 26 arranged around the membrane element 20. The membrane element 20 may be fixed to the casing 30 by the seal member 26. The seal member 26 has a ring shape and surrounds the membrane element 20 in the circumferential direction. For example, the seal member 26 may be a seal with a U-shaped cross section, an O-ring seal, or the like.

[0064] In the membrane separation apparatus 100 of the first embodiment, the seal member 26 has a through-hole 26h through which the non-filtrate fluid F3 flows into the space 35. That is, in the membrane separation apparatus 100, the space 35 is not sealed by the seal member 26.

[0065] The through holes 26h are provided so as to penetrate the seal member 26 in the thickness direction. The number of through holes 26h is not particularly limited and may be one or two or more. A plurality of through holes 26h may be provided at predetermined intervals along the circumferential direction of the seal member 26. The number of rows of the plurality of through holes 26h provided along the circumferential direction of the seal member 26 is not particularly limited and may be one or two or more. When a plurality of through holes 26h are provided, the sum of the cross-sectional areas of the plurality of through holes 26h is preferably 50% or less of the cross-sectional area of ​​the seal member 26. With this configuration, for example, loss of the supply fluid F1 due to excessive flow of the non-filtered fluid F3 into the space 35 can be suppressed.

[0066] 1 , the seal member 26 having the through hole 26h is disposed at the upstream end of the membrane element 20. However, the position where the seal member 26 having the through hole 26h is disposed is not particularly limited. The seal member 26 having the through hole 26h may be disposed at the upstream end or the downstream end of the membrane element 20. The seal member 26 having the through hole 26h may be disposed at any position between the upstream end and the downstream end of the membrane element 20.

[0067] The seal member 26 having the through hole 26h may be disposed in two locations. Two seal members 26 having the through hole 26h may be used as the seal member 26. The two seal members 26 having the through hole 26h may be disposed at the upstream end and the downstream end of the membrane element 20, respectively.

[0068] The shape of the casing 30 is not particularly limited as long as it can accommodate the membrane elements 20. The shape of the casing 30 may be, for example, cylindrical or rectangular tubular. Fig. 1 illustrates an example in which the casing 30 has a cylindrical shape.

[0069] As shown in FIG. 1 , in this embodiment, the casing 30 includes a casing body 31, a first end plate 321, and a second end plate 322. The casing body 31 has a cylindrical shape and is made of a material with sufficient pressure resistance. The casing 30 may be a high-pressure vessel such as that used in reverse osmosis membranes. The first end plate 321 is attached to the upstream end 301 of the casing 30. The end 301 of the casing 30 is closed by the first end plate 321. The second end plate 322 is attached to the downstream end 302 of the casing 30. The end 302 of the casing 30 is closed by the second end plate 322.

[0070] The casing 30 has ports 33a, 33b, and 33c. These ports are used to communicate between the inside and outside of the casing 30. The port 33a is provided at an upstream end 301 of the casing 30. The ports 33b and 33c are provided at a downstream end 302 of the casing 30.

[0071] 1, the port 33a may be provided in the first end plate 321. The port 33b and the port 33c may be provided in the second end plate 322.

[0072] 1 , in this embodiment, an upstream space 35a is formed between the inner surface 321s of the first end plate 321 and the upstream end face 201s of the membrane element 20. A downstream space 35b is formed between the inner surface 322s of the second end plate 322 and the downstream end face 202s of the membrane element 20. A filtration member 10 is disposed in the upstream space 35a. The upstream space 35a communicates with the space 35 via the filtration member 10. The space 35 communicates with the downstream space 35b.

[0073] The membrane separation device 100 has a feed fluid inlet 50a, a permeate fluid outlet 50b, and a non-treated fluid outlet 50c. The feed fluid inlet 50a is an opening for supplying the feed fluid F1 to the membrane separation device 100. The permeate fluid outlet 50b is an opening for discharging the permeate fluid F4 from the membrane separation device 100. The non-treated fluid outlet 50c is an opening for discharging the combined fluid (non-treated fluid F6) of the non-filtrate fluid F3 that has flowed through the space 35 and the filtered fluid F2 (non-permeate fluid F5) that has not permeated the separation membrane from the membrane separation device 100. The feed fluid inlet 50a and port 33a are connected to each other, and port 33a is used as an inlet for the feed fluid F1. The central tube 23 is connected to port 33b at the permeate fluid outlet 50b. That is, port 33b is used as an outlet for the permeate fluid F4. The non-processing fluid outlet 50c and the port 33c are in communication with each other, and the port 33c is used as an outlet for the non-processing fluid F6. Each port may be a simple opening, or may be a nozzle-shaped opening as shown in FIG.

[0074] 2 is a schematic cross-sectional view showing another example of the membrane separation apparatus 100 of Embodiment 1. In the membrane separation apparatus 101 shown in Fig. 2, the casing 30 further has a port 33d. The port 33d is provided on the downstream side of the casing 30. The port 33d may also be provided on the downstream side of the casing main body 31.

[0075] The membrane separation apparatus 101 further has a non-filtrate fluid outlet 50d. The non-filtrate fluid outlet 50d is an opening for discharging the non-filtrate fluid F3 from the membrane separation apparatus 100. The non-filtrate fluid outlet 50d and the port 33d are in communication with each other, and the port 33d is used as an outlet for the non-filtrate fluid F3.

[0076] 2, in the membrane separation apparatus 101, the space 35 and the downstream space 35b are separated by a sealing member 28, which will be described later. That is, in the membrane separation apparatus 101, the space 35 does not communicate with the downstream space 35b. In the membrane separation apparatus 101, the filtered fluid F2 (non-permeated fluid F5) that did not permeate the separation membrane is discharged from the non-treated fluid outlet 50c, and the non-filtrate fluid F3 is discharged from the non-filtrate fluid outlet 50d.

[0077] 1 and 2, the membrane element 20 is placed horizontally so that the axial direction is along the horizontal direction. However, the membrane element 20 may be placed vertically so that the axial direction is along the vertical direction, or may be placed obliquely so that the axial direction forms an angle greater than 0° and less than 90° with respect to the horizontal direction.

[0078] The membrane element 20 may be configured to be detachable from the casing 30. In other words, the membrane element 20 may be configured as a cartridge, and the membrane element 20 may be configured to be replaceable with respect to the casing 30. With such a configuration, maintenance work on the membrane element 20 can be performed smoothly, improving maintainability.

[0079] The diameter of the membrane element 20 may be 8 inches (approximately 201 mm) or less. A membrane separation apparatus 100 equipped with a membrane element 20 of this size is highly portable.

[0080] The membrane separation devices 100 and 101 may separate the filtrate F2 into a permeate fluid F4 and a non-permeate fluid F5 while the supply space of the membrane element 20 is filled with the filtrate F2.

[0081] The membrane separation apparatuses 100 and 101 of the first embodiment are suitable for a continuous membrane separation method. However, the membrane separation apparatuses 100 and 101 may also be used for a batch membrane separation method.

[0082] <Spiral-type membrane element> Fig. 3 is an exploded perspective view schematically showing a spiral-type membrane element 20 provided in the membrane separation devices 100, 101 of Embodiment 1. Fig. 4 is a schematic cross-sectional view of the membrane element 20 of Fig. 3. The membrane element 20 includes an element body 21 and an exterior material 22. The exterior material 22 is omitted in Figs. 3 and 4.

[0083] The element body 21 includes a central tube 23 having a through-hole 23h and a membrane leaf 24 wound around the central tube 23. The membrane leaf 24 has a separation membrane 24a. The separation membrane 24a separates the filtrate fluid F2 into a permeated fluid F4 and a non-permeated fluid F5.

[0084] 3 and 4, the membrane element 20 includes a laminate 25. The laminate 25 is wound around the central tube 23 and disposed around the central tube 23. A feed space and a permeate space are formed inside the laminate 25.

[0085] The filtrate fluid F2 is supplied into the membrane element 20 from one end face of the stack 25 and flows through the supply space parallel to the longitudinal direction of the central tube 23. That is, the filtrate fluid F2 is supplied from the upstream end face of the stack 25 included in the membrane element 20. In the membrane element 20, the filtrate fluid F2 is separated to produce a permeated fluid F4 and a non-permeated fluid F5. The permeated fluid F4 is led to the outside through the central tube 23. The non-permeated fluid F5 is discharged to the outside of the membrane element 20 from the other end face of the stack 25. That is, the non-permeated fluid F5 is discharged from the downstream end face of the stack 25 included in the membrane element 20.

[0086] As shown in FIG. 4 , the laminate 25 has a plurality of membrane leaves 24. Each membrane leaf 24 has a separation membrane 24a and a permeate-side channel material 24b. In FIG. 4 , the permeate-side channel material 24b is indicated by a dashed line. Specifically, the membrane leaf 24 has two separation membranes 24a. The two separation membranes 24a are stacked on top of each other and sealed at three sides to form a bag-like structure. For example, an adhesive layer 25a containing an adhesive is used to seal the two separation membranes 24a. The permeate-side channel material 24b is disposed between the two separation membranes 24a so as to be located inside the bag-like structure. The permeate-side channel material 24b secures a space (permeation space) between the two separation membranes 24a as a channel for the permeating fluid F4. In this way, the permeate-side channel material 24b is used in combination with the separation membrane 24a. The number of membrane leaves 24 is not particularly limited and may be, for example, 2 to 30.

[0087] The laminate 25 further includes a feed-side channel material 25b. In Fig. 4, the feed-side channel material 25b is indicated by a dashed line. The feed-side channel material 25b is located outside the above-mentioned bag-like structure and is laminated on the membrane leaves 24. In detail, the laminate 25 includes a plurality of feed-side channel materials 25b, and the plurality of feed-side channel materials 25b and the plurality of membrane leaves 24 are laminated alternately. The feed-side channel material 25b ensures a space (supply space) between the membrane leaves 24 as a channel for the filtrate fluid F2.

[0088] As shown in Figures 3 and 4, the central tube 23 is typically tubular, particularly cylindrical. The central tube 23 serves to collect the permeated fluid F4 that has permeated each separation membrane 24a and guide it to the outside of the membrane element 20. The central tube 23 is provided with through holes 23h that communicate the internal space of the central tube 23 with the external space. The through holes 23h are formed, for example, in the wall surface of the central tube 23. The number of through holes 23h is not particularly limited and may be one or two or more. The central tube 23 may be provided with a plurality of through holes 23h at predetermined intervals along the direction in which the central tube 23 extends. The number of rows of the plurality of through holes 23h provided along the direction in which the central tube 23 extends is not particularly limited and may be one or two or more. The central tube 23 may be provided with two rows of the plurality of through holes 23h that face each other in a cross-sectional view. The outer diameter of the central tube 23 is, for example, 10 to 100 mm, and preferably 12 to 50 mm.

[0089] As shown in FIGS. 1 and 2, an end cap 23c is attached to the supply end of the central tube 23.

[0090] Examples of materials for the central tube 23 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.

[0091] The membrane element 20 may further include a flow path material 25c. The flow path material 25c is indicated by a dashed line in FIG. 4 . The flow path material 25c is located between the central tube 23 and the stack 25 and is wound around the central tube 23 on the central tube 23 side of the stack 25. The flow path material 25c ensures a space for a flow path of the permeate fluid F4 between the stack 25 and the central tube 23. The flow path material 25c is connected to the open end of the membrane leaf 24 described above. This connects the permeate-side flow path material 24b of the membrane leaf 24 to the flow path material 25c. The flow path material 25c is in contact with the through-hole 23h of the central tube 23. This allows the permeate fluid F4 to flow from the flow path material 25c into the interior of the central tube 23 through the through-hole 23h.

[0092] As the permeate-side flow path material 24b, the feed-side flow path material 25b, and the flow path material 25c, 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.

[0093] [Sheathing Material] As described above, the membrane element 20 includes the sheathing material 22. The sheathing material 22 covers at least the outer peripheral surface 21s of the element body 21.

[0094] The exterior material 22 constitutes the outer peripheral surface 20s of the membrane element 20. The exterior material 22 is wound around the outer peripheral surface 21s of the element body 21, thereby covering the outer peripheral surface 21s of the element body 21. The exterior material 22 is made of a material that does not allow fluid to pass through. The exterior material 22 contains, for example, glass fiber and resin. The resin is typically epoxy resin. The exterior material 22 may be made of fiber reinforced plastic (FRP). The exterior material 22 may be made by winding glass roving (a bundle of glass fibers) impregnated with epoxy resin around the outer peripheral surface 21s of the element body 21 and curing it.

[0095] [Separation Membrane] The configuration of the separation membrane 24a is not particularly limited. When the supply fluid F1 is a solution containing at least one selected from the group consisting of a solvent and a volatile organic compound, the separation membrane 24a may be a pervaporation membrane that separates the solution (filtered fluid F2) from which solids have been separated by the filtration section 11 of the filtration member 10 into a permeated fluid F4 and a non-permeated fluid F5.

[0096] When the supply fluid F1 is a mixed gas containing an acidic gas, the separation membrane 24a may be a gas separation membrane that separates the mixed gas (filtered fluid F2) from which solids have been separated by the filtration section 11 of the filtration member 10 into a permeated fluid F4 and a non-permeated fluid F5.

[0097] Figure 5 is a schematic cross-sectional view showing an example of a separation membrane 24a included in the membrane element 20. As shown in Figure 5, the separation membrane 24a includes, for example, a separation function layer 241 and a porous support 242 that supports the separation function layer 241. The separation function layer 241 is in direct contact with, for example, the porous support 242. For example, the separation membrane 24a has a main surface 241s on the separation function layer side exposed to the supply space, and a main surface 242s on the porous support side exposed to the permeation space.

[0098] When the separation membrane 24 a is a pervaporation membrane, the separation membrane 24 a may further include a protective layer (not shown) that protects the separation functional layer 241 .

[0099] When the separation membrane 24a is a gas separation membrane, the separation membrane 24a may further include an intermediate layer (not shown) disposed between the separation functional layer 241 and the porous support 242. The intermediate layer is in direct contact with each of the separation functional layer 241 and the porous support 242, for example.

[0100] (Separation Functional Layer) The separation functional layer 241 is a layer that allows specific components contained in the filtrate fluid F2 to pass preferentially. When the supply fluid F1 is a cleaning liquid containing a solvent, the separation functional layer 241 is, for example, a layer that allows the solvent contained in the cleaning liquid to pass preferentially. When the supply fluid F1 is a fermentation liquid containing volatile organic compounds, the separation functional layer 241 is, for example, a layer that allows the organic compounds contained in the fermentation liquid to pass preferentially. When the supply fluid F1 is a mixed gas containing an acidic gas, the separation functional layer 241 is, for example, a layer that allows the acidic gas contained in the mixed gas to pass preferentially.

[0101] When the separation functional layer 241 is a layer that allows preferential permeation of a solvent contained in a cleaning solution or an organic compound contained in a fermentation solution, the separation functional layer 241 preferably contains a hydrophobic material. In this specification, the term "hydrophobic material" refers to a material that has a static contact angle of water greater than 90° when, for example, 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 of water can be measured using a commercially available contact angle meter.

[0102] 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 241 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 copolymer (PFA). The hydrophobic materials can be used alone or in combination of two or more.

[0103] The separation functional layer 241 may contain a hydrophobic material as a main component, or may be composed substantially of only a hydrophobic material. The "main component" refers to the component that is contained in the separation functional layer 241 in the largest amount by weight.

[0104] The separation functional layer 241 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.

[0105] The filler includes 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 filtrate fluid F2. Examples of high-silica zeolites that can be used include HSZ (registered trademark) manufactured by Tosoh Corporation, HiSiv (registered trademark) manufactured by Resonac Universal Co., Ltd., USKY (registered trademark) manufactured by Resonac Universal Co., Ltd., and Zeoal (registered trademark) manufactured by Nakamura Choukou Co., Ltd.

[0106] 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.

[0107] 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 241 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.

[0108] The filler content in the separation functional layer 241 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 241 is not particularly limited and is, for example, 70 wt %. The matrix content in the separation functional layer 241 is not particularly limited and is, for example, 30 wt % to 90 wt %.

[0109] When the separation functional layer 241 is a layer that allows preferential permeation of a solvent contained in a cleaning solution or an organic compound contained in a fermentation solution, the thickness of the separation functional layer 241 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 241 may be 1.0 μm or more, 10 μm or more, or 30 μm or more.

[0110] When the separation functional layer 241 is a layer that allows preferential permeation of the solvent contained in the cleaning liquid or the organic compounds contained in the fermentation liquid, the separation functional layer 241 may have a microporous structure with an average pore diameter of less than 0.01 μm, or may be a dense layer with no pores on the surface.

[0111] (Porous Support) Examples of the porous support 242 include nonwoven fabric, porous polytetrafluoroethylene, aromatic polyamide fiber, porous metal, sintered metal, porous ceramic, porous polyester, porous nylon, activated carbon fiber, latex, silicone, silicone rubber, permeable (porous) polymers containing at least one selected from the group consisting of polyvinyl fluoride, polyvinylidene fluoride, polyurethane, polypropylene, polyethylene, polystyrene, polycarbonate, polysulfone, polyether ether ketone, polyacrylonitrile, polyimide, and polyphenylene oxide, metal foams having open or closed cells, polymer foams having open or closed cells, silica, porous glass, and mesh screens. The porous support 242 may be a combination of two or more of these.

[0112] The porous support 242 has an average pore size of, for example, 0.01 to 0.4 μm. The thickness of the porous support 242 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 242 is, for example, 300 μm or less, and preferably 200 μm or less.

[0113] (Protective Layer) The protective layer, for example, covers the surface of the separation functional layer 241. 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 241.

[0114] 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.

[0115] (Intermediate Layer) The intermediate layer may contain, for example, a resin and may further contain nanoparticles dispersed in the resin (matrix). The nanoparticles may be spaced apart within the matrix or may be partially aggregated. The material of the matrix is ​​not particularly limited, and examples thereof include silicone resins such as polydimethylsiloxane; fluororesins such as polytetrafluoroethylene; epoxy resins such as polyethylene oxide; polyimide resins; polysulfone resins; polyacetylene resins such as polytrimethylsilylpropyne and polydiphenylacetylene; and polyolefin resins such as polymethylpentene. The matrix preferably contains a silicone resin.

[0116] The nanoparticles may contain an inorganic material or an organic material. Examples of inorganic materials contained in the nanoparticles include silica, titania, and alumina. The nanoparticles preferably contain silica.

[0117] The thickness of the intermediate layer is not particularly limited and is, for example, less than 50 μm, preferably 40 μm or less, and more preferably 30 μm or less. The lower limit of the thickness of the intermediate layer is not particularly limited and is, for example, 1 μm. The intermediate layer is, for example, a layer having a thickness of less than 50 μm.

[0118] <Filtering Member> As described above, the filtering member 10 is disposed in the upstream space 35a. The filtering member 10 is disposed between the first end plate 321 of the casing 30 and the upstream end of the element body 21. The filtering member 10 is disposed so that the filtering portion 11 faces the supply fluid inlet 50a. The filtering member 10 may also be disposed so that the filtering portion 11 faces the supply fluid inlet 50a.

[0119] 1 and 2 , the filtration member 10 may be directly connected to the membrane elements 20. In other words, there may be no space or other members between the filtration member 10 and the membrane elements 20. With this configuration, the filtered fluid F2 from which solids have been separated by the filtration section 11 can be easily supplied to the membrane elements 20. However, as long as the filtered fluid F2 from which solids have been separated by the filtration section 11 can be supplied to the membrane elements 20, there may be a space or other members between the filtration member 10 and the membrane elements 20.

[0120] FIG. 6 is a partially enlarged view of the membrane separation devices 100, 101. As shown in FIG. 6, the filtration member 10 has a filtration flow path P2 through which the filtrate fluid F2 flows and a non-filtration flow path P3 through which the non-filtrate fluid F3 flows. The filtration flow path P2 is a flow path that guides the filtrate fluid F2 that has passed through the filtration section 11 to the membrane element 20. The filtration flow path P2 is connected to a supply space located inside the membrane element 20. The non-filtration flow path P3 is a flow path that guides the non-filtrate fluid F3 that has not passed through the filtration section 11 to a space 35 adjacent to the outer peripheral surface 20s of the membrane element 20. The non-filtration flow path P3 is connected to the space 35. With this configuration, the filtration flow path P2 can guide the filtrate fluid F2 to the supply space of the membrane element 20. The non-filtration flow path P3 can guide the non-filtrate fluid F3 to the space 35.

[0121] In a cross section of the membrane separation apparatus 100 taken along the axis X of the membrane element 20, the surface 11s of the filtration section 11 may be perpendicular to the axis X, i.e., parallel to the upstream end face 201s of the membrane element 20, or may have an inclination angle with respect to the axis X. In the example of Fig. 6, the surface 11s of the filtration section 11 has an inclination angle with respect to the axis X. As shown in Fig. 6, when the surface 11s has an inclination angle in the above cross section, the filtration section 11 may have a surface 11s that is line-symmetrical with respect to the axis X.

[0122] In the above cross section, the inclination angle of the surface 11s with respect to the axis X is, for example, in the range of 0° to ±90°. When the inclination angle is 0°, the surface 11s is parallel to the axis X. When the inclination angle is ±90°, the surface 11s is parallel to the end face 201s.

[0123] The lower limit of the inclination angle of the surface 11s with respect to the axis X may be 5° or more, 10° or more, 15° or more, 20° or more, 25° or more, or even 30° or more. The upper limit of the inclination angle of the surface 11s with respect to the axis X may be ±85° or less, ±80° or less, or even ±75° or less.

[0124] Fig. 7 is a schematic perspective view of the filtering member 10. As shown in Fig. 7, the filtering member 10 may have a protrusion 12 protruding in the direction of the axis X. In this case, the filtering portion 11 may be disposed on at least a part of a side surface 12s of the protrusion 12. By disposing the filtering portion 11 on at least a part of the side surface 12s of the protrusion 12, the surface 11s of the filtering portion 11 may have an inclination angle with respect to the axis X in the cross section.

[0125] With this configuration, as shown in Fig. 6, the incident angle θi of the supply fluid F1 with respect to the surface 11s of the filtration section 11 can be made smaller than 90°. Therefore, solid matter is less likely to accumulate on the surface 11s of the filtration section 11. Even if solid matter does accumulate on the surface 11s of the filtration section 11, the flowing force of the supply fluid F1 can wash away the solid matter accumulated on the surface 11s. This makes it possible to prevent clogging of the filtration section 11.

[0126] When the filtering member 10 has the convex portion 12, the filtering member 10 is disposed so that the convex portion 12 protrudes toward the upstream side, specifically, toward the supply fluid inlet 50a side.

[0127] The convex portion 12 may have, for example, a truncated cone shape, a conical shape, or a cylindrical shape. In the example of Figures 6 and 7, the convex portion 12 has a truncated cone shape.

[0128] 6 , the truncated cone-shaped convex portion 12 is defined as an upstream portion 12a located on the upstream side and a downstream portion 12b located on the downstream side. In this case, the filtration section 11 may be disposed on a side surface 12s of the truncated cone-shaped convex portion 12 that corresponds to the upstream portion 12a. However, the filtration section 11 may also be disposed on the entire side surface of the truncated cone-shaped convex portion 12.

[0129] 6, the upstream portion 12a of the truncated cone-shaped convex portion 12 may have a holding portion 12h for holding the filtration portion 11. The sheet-like or film-like filtration portion 11 may be configured to be detachable from the holding portion 12h. The configuration of the holding portion 12h is not particularly limited as long as it is capable of holding the sheet-like or film-like filtration portion 11.

[0130] As shown in Fig. 7, at least a portion of the side surface 12s of the truncated cone-shaped convex portion 12 may have a frame structure. Of the side surfaces 12s of the truncated cone-shaped convex portion 12, the side surface corresponding to the upstream portion 12a may have the frame structure. The filtration section 11 may be arranged so as to cover the side surface having the frame structure. With this configuration, the strength of the convex portion 12 can be improved.

[0131] In the example of Fig. 7, the side surface 12s of the truncated cone-shaped protrusion 12 that corresponds to the upstream portion 12a has a frame structure. The side surface that corresponds to the upstream portion 12a has a lattice-like frame structure made up of vertical lattices 121 and horizontal lattices 122. However, the frame structure is not limited to the one exemplified in Fig. 7. For example, the frame structure may be a lattice-like structure made up of only vertical lattices.

[0132] Although not shown in the drawings, the side surface 12s of the truncated cone-shaped convex portion 12 may be formed only by the filtering portion 11. In other words, the side surface 12s does not need to have a frame structure. In this case, the filtering area provided by the filtering portion 11 becomes larger, thereby improving filtering efficiency.

[0133] 7, when the convex portion 12 has a truncated cone shape, the convex portion 12 may further have a top surface 12t connected to the side surface 12s. The top surface 12t is a surface perpendicular to the axis X. In this case, it is preferable that the filtration section 11 is not disposed on the top surface 12t. With this configuration, solid matter is prevented from accumulating on the surface 11s of the filtration section 11.

[0134] In the present embodiment, the filtration unit 11 includes a porous member. With this configuration, the supply fluid F1 containing solids can be reliably separated into a filtered fluid F2 and an unfiltered fluid F3 by the filtration unit 11. The porous member may be, for example, in the form of a plate, a sheet, or a film.

[0135] The porous member is not particularly limited as long as it can separate the solid-containing feed fluid F1 into the filtered fluid F2 and the unfiltered fluid F3. Examples of the porous member that can be used include 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); a metal net, woven fabric, or knitted fabric; punched metal; nonwoven fabric; wedge wire screen; and sintered wire mesh.

[0136] The average pore size of the porous member is, for example, in the range of 10 μm to 2000 μm. The lower limit of the average pore size may be 20 μm or more, 30 μm or more, 40 μm or more, or even 50 μm or more. The upper limit of the average pore size may be 1750 μm or less, 1500 μm or less, 1250 μm or less, 1000 μm or less, 750 μm or less, or even 500 μm or less.

[0137] The thickness of the porous member is, for example, in the range of 0.05 mm to 10 mm. The lower limit of the thickness may be 0.06 mm or more, 0.07 mm or more, 0.08 mm or more, 0.09 mm or more, or even 0.1 mm or more. The upper limit of the thickness may be 9 mm or less, 8 mm or less, 7 mm or less, 6 mm or less, 5 mm or less, 4 mm or less, 3 mm or less, or even 2 mm or less.

[0138] The filtration member 10 may further have an annular skirt portion 14 extending toward the membrane element 20 side.

[0139] 6, the skirt portion 14 can be disposed between the element body 21 and the exterior material 22. The skirt portion 14 and a part of the exterior material 22 may be bonded together. With this configuration, the membrane element 20 and the filtration member 10 can be firmly fixed together.

[0140] The inner diameter of the skirt portion 14 is approximately the same as the outer diameter of the element body 21. Therefore, by disposing the filtering member 10 at the upstream end of the element body 21, the inner circumferential surface of the skirt portion 14 can be brought into contact with the outer circumferential surface 21s of the element body 21. In this state, by attaching the exterior material 22 so as to straddle the outer circumferential surfaces of the skirt portion 14 and the outer circumferential surface 21s of the element body 21, the element body 21 is covered by the skirt portion 14 and the exterior material 22.

[0141] The filtration member 10 may further have a shoulder portion 13 that protrudes inward from the skirt portion 14 in the radial direction of the membrane element 20. The shoulder portion 13 can suppress the telescope phenomenon during operation. In this way, the filtration member 10 may also serve as a member for suppressing the telescope phenomenon during operation (telescope prevention member).

[0142] As shown in FIG. 6 , when the filter element 10 has a convex portion 12 , the shoulder portion 13 is located between the convex portion 12 and the skirt portion 14 .

[0143] The filtering member 10 may have an internal space 12i. The internal space 12i may constitute a part of the filtering flow path P2 through which the fluid F2 to be filtered flows. The internal space 12i is a space defined by, for example, the inner surfaces of the protrusion 12 and the shoulder portion 13 connected to the protrusion 12.

[0144] The filtering member 10 may further have an annular portion 15 provided in the circumferential direction near the downstream portion 12b of the convex portion 12. In this case, as shown in Fig. 5, the space between the side surface 12s of the convex portion 12 and the inner surface 15s of the annular portion 15 may form part of the non-filtration flow path P3.

[0145] The annular portion 15 may have a groove 15g formed in the circumferential direction. As shown in Fig. 6 , the groove 15g may be located near a boundary line 12c between the upstream portion 12a and the downstream portion 12b in the direction of the axis X.

[0146] The membrane separation devices 100, 101 may further include a seal member 27 disposed in the groove portion 15g of the annular portion 15. As shown in Fig. 6, the filtration member 10 may be fixed to the casing 30 by the seal member 27. The seal member 27 has a ring shape and is disposed so as to surround the annular portion 15 of the filtration member 10 in the circumferential direction. For example, the seal member 27 may be a seal with a U-shaped cross section, an O-ring seal, or the like.

[0147] There are no particular limitations on the material that constitutes the filter member 10. The filter member 10 may be made of, for example, metal or resin. When the filter member 10 is made of metal, the filter portion 11 may be made of, for example, punched metal, so that the filter member 10 and the filter portion 11 can be integrally molded.

[0148] The filtration member 10 may contain polyamide resin, phenolic resin, fluororesin, polyphenylene oxide resin, or austenitic stainless steel as its primary component. "Main component" refers to the component that is present in the largest amount by weight. These materials are highly resistant to heavy hydrocarbons such as benzene, toluene, ethylbenzene, xylene (BTEX components), and unsaturated hydrocarbons. Therefore, a filtration member 10 containing these materials as its primary component is suitable for applications such as separating acidic gases. The filtration member 10 may contain polyamide resin as its primary component. Thermoplastic polyamide resin is preferred as the polyamide resin because it can be injection molded. Polyamide resin is also preferred from a cost perspective.

[0149] Like the membrane element 20, the filtration member 10 may be configured to be detachable from the casing 30. In other words, the filtration member 10 may be configured to be replaceable with respect to the casing 30. With such a configuration, maintenance work on the membrane separation device 100 can be performed smoothly, improving maintainability.

[0150] In the filtering member 10, the filtering section 11 may be configured to be detachable from the convex portion 12. Alternatively, in the filtering member 10, the upstream portion 12a of the convex portion 12 may be configured to be detachable from the downstream portion 12b. With such a configuration, maintenance work on the filtering member 10 can be performed smoothly, improving maintainability.

[0151] <End Member> The membrane separation device 100 may further include an end member 40 attached to one or both ends of the membrane element 20 in the axial X direction. The end member 40 is a member for suppressing the telescope phenomenon during operation, and is also called an anti-telescope member or an anti-telescope material. The end member 40 may be attached to both ends of the membrane element 20 in the axial X direction. Two end members 40 may be attached to both ends of the membrane element 20 in the axial X direction so as to face each other.

[0152] 1 and 2, the end member 40 is disposed in the downstream space 35b. The end member 40 is disposed between the downstream end of the element body 21 and the second end plate 322 of the casing 30. By disposing the end member 40 at the downstream end of the element body 21, the telescoping phenomenon during operation is likely to be suppressed.

[0153] 8 is a schematic perspective view of the end member 40. The end member 40 includes a main body 41 having a circular outline in a cross section perpendicular to the direction of the axis X, and an annular skirt portion 44 extending from the main body 41 toward the membrane element 20.

[0154] The skirt portion 44 corresponds to the skirt portion 14 of the filtering member 10 described above. The skirt portion 44 may have the same configuration as the skirt portion 14. That is, the skirt portion 44 may be disposed between the element body 21 and the exterior material 22. The skirt portion 44 and a part of the exterior material 22 may be bonded to each other.

[0155] The main body 41 may further have a groove 41g formed in the circumferential direction.

[0156] 1 may further include a sealing member disposed in the groove 41g of the main body 41 and having a through hole through which the non-filtered fluid F3 flows into the downstream space 35b. The sealing member having a through hole allows the end member 40 to be fixed to the casing 30 without impeding communication between the space 35 and the downstream space 35b. As the sealing member having a through hole, for example, the same sealing member as the sealing member 26 having the through hole 26h described above can be used.

[0157] 2 further includes a seal member 28 disposed in the groove 41g of the main body 41. The seal member 28 can secure the end member 40 to the casing 30 while separating the space 35 from the downstream space 35b. The seal member 28 can be the same as the seal member 27 described above, for example.

[0158] 8, the main body 41 has an opening 41a through which the non-permeated fluid F5 passes and an annular opening 41b through which the permeated fluid F4 passes. The opening 41a and the annular opening 41b extend in the direction of the axis X. The central tube 23 is inserted into the upstream side (the skirt portion 14 side) of the annular opening 41b. The opening 41a may be divided into multiple sections by multiple connecting portions 41c provided in the shape of spokes.

[0159] As the material for the end member 40, the materials listed above for the filter member 10 can be used.

[0160] In this embodiment, the end member 40 may include the filtering member 10. That is, the end member 40 may include a filtering section 11 that separates the supply fluid F1 containing solids into a filtered fluid F2 and an unfiltered fluid F3. In other words, the filtering member 10 may also serve as the end member 40. The filtering member 10 and the end member 40 may be integrated.

[0161] As described above, the filtration member 10 may further have a shoulder portion 13 that protrudes inward from the skirt portion 14 in the radial direction of the membrane element 20. The filtration member 10 having the shoulder portion 13 can also be used as an end member 40 because the shoulder portion 13 can suppress the telescope phenomenon during operation.

[0162] In the examples of Figures 1 and 2, the filtration member 10 has a shoulder portion 13. Therefore, it can be said that the membrane separation apparatus 100, 101 includes an end member 40 arranged at the upstream end of the membrane element 20 in addition to an end member 40 arranged at the downstream end of the membrane element 20. Because the end member 40 arranged at the upstream end of the membrane element 20 includes the filtration member 10, there is no need to prepare the filtration member 10 separately from the end member 40. Therefore, for example, the size of the upstream space 35a of the membrane separation apparatus 100, 101 can be reduced, making the membrane separation apparatus 100, 101 more compact. Furthermore, the costs required for the membrane separation apparatus 100, 101 can be reduced.

[0163] Although not shown, the membrane separation devices 100, 101 may include a filtration member 10 in addition to the end member 40 arranged at the upstream end of the membrane element 20. In this case, the filtration member 10 is arranged upstream of the end member 40 in the direction of the axis X. A space or another member may exist between the filtration member 10 and the end member 40.

[0164] In the membrane separation devices 100 and 101 of the first embodiment, the feed fluid inlet 50a, the permeated fluid outlet 50b, and the untreated fluid outlet 50c are provided in a direction parallel to the axis X of the membrane element 20. Therefore, the membrane separation devices 100 and 101 are suitable for use by connecting a plurality of them in series.

[0165] <Operating Method of Membrane Separation Apparatus> Next, an operating method of the membrane separation apparatus 100, 101 of the first embodiment will be described with reference to Figures 1 and 2. In the following, an example will be described in which the supply fluid F1 is a solution containing at least one selected from the group consisting of a solvent and a volatile organic compound, and the separation membrane 24a is a pervaporation membrane.

[0166] The operating method of the membrane separation devices 100, 101 includes, for example, separating a feed fluid F1 into a filtered fluid F2 and a non-filtered fluid F3 by the filtration section 11 of the filtration member 10 (filtration separation process), and separating the filtered fluid F2 into a permeated fluid F4 and a non-permeated fluid F5 by the membrane element 20 (membrane separation process).

[0167] Specifically, the membrane separation apparatus 100, 101 is operated as follows. First, a solution containing solids (feed fluid F1) is supplied to the interior of the membrane separation apparatus 100, 101 through the port 33a (feed fluid inlet 50a). The feed fluid F1 is separated into a filtered fluid F2 and a non-filtrate fluid F3 by the filtration section 11 of the filtration member 10 (filtration separation process). Next, the filtered fluid F2 is supplied to the interior of the membrane element 20 through the filtration flow path P2. At this time, the non-filtrate fluid F3 flows into the space 35 through the non-filtration flow path P3 and the through-hole 26h of the seal member 26 and flows along the space 35.

[0168] The filtrate F2 supplied to the interior of the membrane element 20 comes into contact with one side of the pervaporation membrane. With the filtrate F2 in contact with one side of the pervaporation membrane, the permeation space adjacent to the other side of the pervaporation membrane is depressurized. This results in a permeated fluid F4 (membrane separation process). The permeated fluid F4 moves into the interior of the central tube 23 and is discharged to the outside of the membrane separation apparatus 100, 101 through port 33b (permeated fluid outlet 50b). Meanwhile, the solution that has not permeated the pervaporation membrane (non-permeated fluid F5) is discharged to the outside of the membrane element 20. At this time, in the membrane separation apparatus 100, the non-filtrate F3 flowing through the space 35 prevents the non-permeated fluid F5 from flowing into the space 35 and accumulating therein. In the membrane separation apparatus 101, the space 35 is not connected to the downstream space 35b, so the non-permeated fluid F5 is prevented from flowing into the space 35 and accumulating therein.

[0169] In the operating method of the membrane separation device 100, the non-permeated fluid F5 merges with the non-filtered fluid F3 that has flowed through the space 35, and the combined fluid (non-treated fluid F6) is discharged to the outside of the membrane separation device 100 through the port 33c (non-treated fluid outlet 50c).

[0170] In the operation method of the membrane separation apparatus 101, the non-permeated fluid F5 is discharged to the outside of the membrane separation apparatus 101 through the port 33c (non-treated fluid outlet 50c). The non-filtrate fluid F3 that has flowed through the space 35 is discharged to the outside of the membrane separation apparatus 101 through the port 33d (non-filtrate outlet 50d).

[0171] [Embodiment 2] <Membrane Separation System> Fig. 9 is a schematic configuration diagram showing an example of a membrane separation system 1000 of Embodiment 2. The membrane separation system 1000 shown in Fig. 9 includes the membrane separation device 100 of Embodiment 1 described above as a membrane separation device. The membrane separation system 1000 can perform the above-described operating method on the membrane separation device 100.

[0172] The membrane separation system 1000 may further include an adjustment mechanism (not shown) that adjusts the flow rate of the filtrate fluid F2 supplied to the membrane elements 20 of the membrane separation device 100. With this configuration, the flow rate of the filtrate fluid F2 supplied to the membrane elements 20 can be appropriately adjusted, thereby further suppressing fluid retention inside the membrane separation device 100.

[0173] The configuration of the adjustment mechanism is not particularly limited as long as it can adjust the flow rate of the filtrate fluid F2 supplied to the membrane element 20. The adjustment mechanism may be, for example, a valve or a pump connected to port 33b. In this case, the flow rate of the filtrate fluid F2 supplied to the membrane element 20 can be adjusted by adjusting the flow rate of the permeated fluid F4. The adjustment mechanism may be a valve or a pump connected to port 33c. In this case, the flow rate of the filtrate fluid F2 supplied to the membrane element 20 can be adjusted by adjusting the flow rate of the non-treated fluid F6.

[0174] The membrane separation system 1000 may further include a tank 200 in addition to the membrane separation apparatus 100. The tank 200 stores a feed fluid F1 to be supplied to the membrane separation apparatus 100. When the feed fluid F1 is a fermentation liquid containing volatile organic compounds, the tank 200 may be a fermenter for producing the organic compounds by fermenting a carbon source with microorganisms.

[0175] The membrane separation system 1000 may further include a pressure reducing device 300. The pressure reducing device 300 can reduce the pressure in the permeate space 100b of the membrane separation device 100. The pressure reducing device 300 is preferably a vacuum device such as a vacuum pump. The vacuum pump is typically a gas transport 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 300 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 100a of the membrane separation device 100 can be appropriately adjusted.

[0176] The pressure in the permeate space 100b of the membrane separation device 100 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.

[0177] The membrane separation system 1000 may further include a recovery unit 400 for recovering the permeated fluid F4. The recovery unit 400 recovers the permeated fluid F4 sent from the membrane separation device 100 and can store the permeated fluid F4, for example. The recovery unit 400 is, for example, a tank for storing the permeated fluid F4.

[0178] The membrane separation system 1000 further includes a feed fluid supply path 91 , a permeate fluid discharge path 92 , and an untreated fluid discharge path 93 .

[0179] The feed fluid supply path 91 is connected to the feed fluid outlet (outlet 200a) of the tank 200 and the feed fluid inlet 50a (port 33a) of the membrane separation device 100, and is a path for supplying the feed fluid F1 from the tank 200 to the membrane separation device 100. A pump for controlling the flow rate of the feed fluid F1 may be disposed in the feed fluid supply path 91. When the feed fluid F1 is a solution containing at least one selected from the group consisting of solvents and volatile organic compounds, a sensor for measuring the content of the solvent or organic compounds in the feed fluid F1 may be disposed in the feed fluid supply path 91.

[0180] The permeate fluid discharge path 92 is connected to the permeate fluid outlet 50b (port 33b) of the membrane separation device 100 and the permeate fluid inlet (inlet 400a) of the recovery section 400, and is a path for sending the permeate fluid F4 from the membrane separation device 100 to the recovery section 400. When the supply fluid F1 is a solution containing at least one selected from the group consisting of solvents and volatile organic compounds, the permeate fluid discharge path 92 may be provided with a sensor for measuring the content of the solvent or organic compound in the permeate fluid F4.

[0181] The untreated fluid discharge path 93 is connected to the untreated fluid outlet 50c (port 33c) of the membrane separation device 100, and is a path for discharging the untreated fluid F6 from the membrane separation device 100. When the supply fluid F1 is a solution containing at least one selected from the group consisting of a solvent and a volatile organic compound, a sensor for measuring the content of the solvent or organic compound in the untreated fluid F6 may be disposed in the untreated fluid discharge path 93.

[0182] The non-treated fluid discharge path 93 may be connected to the non-permeated fluid inlet (inlet 200b) of the tank 200 and configured to send the non-treated fluid F6 to the tank 200. That is, in the membrane separation system 1000, the non-treated fluid F6 may be mixed with the supply fluid F1 in the tank 200 and circulated through the supply fluid supply path 91 and the non-treated fluid discharge path 93. For example, if the supply fluid F1 is a fermentation liquid containing volatile organic compounds, sending the non-treated fluid F6 to the tank 200 causes the fermentation liquid and the non-treated fluid F6 to mix in the tank 200, reducing the organic compound content in the fermentation liquid. If the tank 200 is a fermenter, the reduction in the organic compound content in the fermentation liquid can prevent microbial fermentation from stopping, thereby enabling continuous production of a fermented product. Furthermore, since retention of the non-permeated fluid F5 in the membrane separation device 100 is suppressed, the incorporation of impurities into the tank 200 due to retention can be suppressed. Furthermore, air is prevented from accumulating in the space 35 of the membrane separation device 100, so that air entrapment in the membrane separation device 100 can be suppressed.

[0183] When the permeated fluid F4 is a gas, a condensation section (not shown) for condensing the permeated fluid F4 may be further disposed in the permeated fluid discharge path 92. The condensation section is, for example, a heat exchanger for cooling the permeated fluid F4. The heat exchanger can cool and condense the gaseous permeated fluid F4. 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 F4. The condensation section may be located between the membrane separation device 100 and the pressure reduction device 300 (upstream of the pressure reduction device 300), or may be located between the pressure reduction device 300 and the recovery section 400 (downstream of the pressure reduction device 300).

[0184] The membrane separation system 1000 may further include a controller 500 that controls each component of the membrane separation system 1000. The controller 500 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 500 stores a program for appropriately operating the membrane separation system 1000. For example, the controller 500 controls an adjustment mechanism that adjusts the flow rate of the filtrate fluid F2 supplied to the membrane elements 20 of the membrane separation device 100. For example, the controller 500 can control the operation of the pressure reducing device 300 and the like to switch between membrane separation operation and cleaning operation.

[0185] Unless otherwise specified, each of the paths of the membrane separation system 1000 is made up of, for example, metal or resin piping.

[0186] The operating method of the membrane separation system 1000 includes the filtration separation step and membrane separation step in the operating method of the membrane separation apparatus 100 described above. The operating method of the membrane separation system 1000 may further include adjusting the flow rate of the filtrate F2 supplied to the membrane element 20 (flow rate adjusting step). The flow rate adjusting step may be performed by an adjusting mechanism (not shown) that adjusts the flow rate of the filtrate F2 supplied to the membrane element 20.

[0187] Modified examples of the membrane separation system 1000 will be described in detail below with reference to Figures 10 to 13. In the following, elements common to the above-described membrane separation system 1000 will be denoted by the same reference numerals, and their description may be omitted. That is, the descriptions of the second embodiment and the following modified examples can be mutually applied unless technically inconsistent. Furthermore, the second embodiment and the following modified examples may be combined with each other unless technically inconsistent.

[0188] (Variation 1) Fig. 10 is a schematic configuration diagram showing Variation 1 of the membrane separation system 1000 of the present embodiment. The membrane separation system 1001 of Variation 1 shown in Fig. 10 includes the membrane separation device 101 of the above-described embodiment 1 as a membrane separation device. The membrane separation system 1001 can implement the above-described operating method for the membrane separation device 101.

[0189] In the membrane separation system 1001, the adjusting mechanism for adjusting the flow rate of the filtrate fluid F2 supplied to the membrane element 20 may be a valve or pump connected to port 33b and a valve or pump connected to port 33d. In this case, the flow rate of the permeate fluid F4 and the flow rate of the non-filtrate fluid F3 can be adjusted, respectively, to adjust the flow rate of the filtrate fluid F2 supplied to the membrane element 20. The adjusting mechanism may be a valve or pump connected to port 33c and a valve or pump connected to port 33d. In this case, the flow rate of the filtrate fluid F2 supplied to the membrane element 20 can be adjusted by adjusting the flow rate of the non-permeate fluid F5 and the flow rate of the non-filtrate fluid F3.

[0190] In the example of FIG. 10, the membrane separation system 1001 includes, as the adjusting mechanism, a valve 61 connected to the port 33d and a valve 62 connected to the port 33c.

[0191] As shown in FIG. 10, the membrane separation system 1001 may further include a pressure sensor 71 that measures the pressure of the feed fluid F1 and a pressure sensor 72 that measures the pressure of the non-permeated fluid F5.

[0192] As shown in FIG. 10, the membrane separation system 1001 may further include a flow sensor 73 that measures the flow rate of the non-permeate fluid F5.

[0193] 10, the pressure sensor 71 is disposed in the supply fluid supply path 91. The pressure sensor 72 and the flow rate sensor 73 are disposed in the non-processing fluid discharge path 93, upstream of the valve 62.

[0194] The operating method of the membrane separation system 1001 includes the filtration separation step and the membrane separation step in the operating method of the membrane separation device 101 described above. The operating method of the membrane separation system 1001 may further include adjusting the flow rate of the filtrate F2 supplied to the membrane element 20 (flow rate adjusting step).

[0195] The flow rate adjusting step may include at least one selected from the group consisting of: (I) adjusting the pressure difference between the feed fluid F1 and the non-permeated fluid F5, and (II) adjusting the flow rate of the non-permeated fluid F5. That is, the flow rate of the filtrate fluid F2 supplied to the membrane element 20 may be adjusted by performing (I) and / or (II). (I) and / or (II) may be performed at the start of operation of the membrane separation system 1001.

[0196] In the operation method of the membrane separation system 1001, it is preferable to gradually increase the flow rate of the filtrate fluid F2 supplied to the membrane element 20 in the flow rate adjustment step. When the flow rate of the filtrate fluid F2 supplied to the membrane element 20 is gradually increased in the flow rate adjustment step, the feed fluid F1 containing solids is prevented from being rapidly supplied to the filtration section 11, making it difficult for solids to accumulate on the surface of the filtration section 11. As a result, fluid retention inside the membrane separation device 101 is further suppressed. The membrane separation system 1001 is more suitable for continuous operation.

[0197] The "gradual increase in the flow rate of the filtrate fluid F2 supplied to the membrane element 20 in the flow rate adjustment step" in this embodiment will be described with reference to FIG. 11 . As shown in FIG. 11 , the flow rate of the filtrate fluid F2 at the start of the flow rate adjustment step is defined as 0%, and the flow rate of the filtrate fluid F2 at the end of the adjustment is defined as 100%. The start point of the adjustment time is normalized to 0% and the end point of the adjustment time is normalized to 100%. In a graph with the adjustment time (%) on the horizontal axis and the flow rate (%) of the filtrate fluid F2 on the vertical axis, the straight line connecting the start time and the end time of the adjustment is defined as the reference line Lr. In this case, "gradually increasing the flow rate of the filtrate fluid F2 supplied to the membrane element 20 in the flow rate adjustment step" means increasing the flow rate of the filtrate fluid F2 supplied to the membrane element 20 within a range that does not exceed the slope of the reference line Lr. The line Lex shown in FIG. 11 is an example of a case where the flow rate of the filtrate fluid F2 supplied to the membrane element 20 is increased within a range that does not exceed the slope of the reference line Lr.

[0198] A flow rate adjustment step may be performed at the start of operation of the membrane separation system 1001, and the flow rate of the filtrate fluid F2 supplied to the membrane element 20 may be gradually increased from zero to a predetermined value. The predetermined value is set appropriately depending on the operating conditions of the membrane separation device 101, etc.

[0199] Gradually increasing the flow rate of the filtrate fluid F2 supplied to the membrane element 20 may include at least one selected from the group consisting of: (i) gradually increasing the pressure difference between the feed fluid F1 and the non-permeated fluid F5, and (ii) gradually increasing the flow rate of the non-permeated fluid F5. According to (i) and / or (ii) above, it is easy to gradually increase the flow rate of the filtrate fluid F2 supplied to the membrane element 20. Therefore, rapid supply of the feed fluid F1 containing solids to the filtration section 11 is further suppressed, and solids are less likely to accumulate on the surface of the filtration section 11. As a result, fluid stagnation inside the membrane separation device 101 is further suppressed.

[0200] The meaning of "(i) gradually increasing the pressure difference between the feed fluid F1 and the non-permeated fluid F5" in this embodiment can be understood by replacing "the flow rate (%) of the filtered fluid F2" with "the pressure difference (%) between the feed fluid F1 and the non-permeated fluid F5" in the above description regarding "gradually increasing the flow rate of the filtered fluid F2 supplied to the membrane element 20 in the flow rate adjustment step." That is, "(i) gradually increasing the pressure difference between the feed fluid F1 and the non-permeated fluid F5" means increasing the pressure difference between the feed fluid F1 and the non-permeated fluid F5 within a range that does not exceed the slope of the reference line Lr connecting the start and end of adjustment in a graph with the adjustment time (%) on the horizontal axis and the pressure difference (%) between the feed fluid F1 and the non-permeated fluid F5 on the vertical axis. In this case, the line Lex shown in FIG. 11 is an example of a case where the pressure difference between the feed fluid F1 and the non-permeated fluid F5 is increased within a range that does not exceed the slope of the reference line Lr.

[0201] The meaning of "(ii) gradually increasing the flow rate of the non-permeated fluid F5" in this embodiment can be understood by replacing "the flow rate (%) of the filtrate fluid F2" with "the flow rate (%) of the non-permeated fluid F5" in the above description regarding "gradually increasing the flow rate of the filtrate fluid F2 supplied to the membrane element 20 in the flow rate adjustment step." That is, "(ii) gradually increasing the flow rate of the non-permeated fluid F5" means increasing the flow rate of the non-permeated fluid F5 within a range that does not exceed the slope of the reference line Lr connecting the start and end of adjustment in a graph with the adjustment time (%) on the horizontal axis and the flow rate (%) of the non-permeated fluid F5 on the vertical axis. In this case, the line Lex shown in FIG. 11 is an example of a case where the flow rate of the non-permeated fluid F5 is increased within a range that does not exceed the slope of the reference line Lr.

[0202] At the start of operation of the membrane separation system 1001, in the above step (i), the pressure difference between the feed fluid F1 and the non-permeated fluid F5 may be gradually increased from zero to a predetermined value. The predetermined value is set appropriately depending on the operating conditions of the membrane separation device 101, etc.

[0203] At the start of operation of the membrane separation system 1001, in the above (ii), the flow rate of the non-permeated fluid F5 may be gradually increased from zero to a predetermined value. The predetermined value is set appropriately depending on the operating conditions of the membrane separation device 101, etc.

[0204] In the above (i), the pressure difference between the supply fluid F1 and the non-permeating fluid F5 may be gradually increased by controlling the adjusting mechanism based on the monitoring results of the pressure of the supply fluid F1 and the pressure of the non-permeating fluid F5. In the above (ii), the flow rate of the non-permeating fluid F5 may be gradually increased by controlling the adjusting mechanism based on the monitoring results of the flow rate of the non-permeating fluid F5.

[0205] 10 , in the above (i), the pressure difference between the supply fluid F1 and the non-permeating fluid F5 can be gradually increased by controlling the valve 61 and / or the valve 62. In the above (ii), the flow rate of the non-permeating fluid F5 can be gradually increased by controlling the valve 61 and / or the valve 62.

[0206] In the above (i), the pressure of the supply fluid F1 may be monitored by a pressure sensor 71, and the pressure of the non-permeating fluid F5 may be monitored by a pressure sensor 72. In the above (ii), the flow rate of the non-permeating fluid F5 may be monitored by a flow rate sensor 73.

[0207] In the above (i), the pressure difference between the feed fluid F1 and the non-permeated fluid F5 may be calculated while monitoring the pressures of the feed fluid F1 and the non-permeated fluid F5 with the pressure sensors 71 and 72, and the adjustment mechanism (valve 61 and / or valve 62) may be controlled so as to reduce the amount of change in the pressure difference per unit time. In the above (ii), the adjustment mechanism (valve 61 and / or valve 62) may be controlled so as to reduce the amount of change in the flow rate of the non-permeated fluid F5 per unit time while monitoring the flow rate of the non-permeated fluid F5 with the flow sensor 73. By controlling the adjustment mechanism in this manner, the flow rate of the filtrate fluid F2 supplied to the membrane element 20 may be gradually increased.

[0208] In the above (i) and / or (ii), the time from the start to the end of the adjustment of the flow rate of the filtered fluid F2 by the adjustment mechanism is, for example, in the range of 5 seconds to 20 minutes. The time from the start to the end of the adjustment of the flow rate of the filtered fluid F2 by the adjustment mechanism may be in the range of 15 seconds to 10 minutes, or in the range of 1 minute to 5 minutes.

[0209] The membrane separation system 1000 of this embodiment may include multiple membrane separation devices 100, 101, and the multiple membrane separation devices 100, 101 may be connected to each other in series or in parallel. In this specification, "multiple membrane separation devices connected to each other in series" means a configuration in which multiple membrane separation devices are connected to each other so that the untreated fluid F6 discharged from the supply space of the membrane element of the upstream membrane separation device is supplied to the filtration member of the downstream membrane separation device. "multiple membrane separation devices connected to each other in parallel" means a configuration in which multiple membrane separation devices are connected to each other so that the feed fluid F1 sent from a tank is supplied to the filtration member of each of the multiple membrane separation devices. The number of membrane separation devices 100, 101 in the membrane separation system 1000 is not particularly limited and may be, for example, 2 to 5.

[0210] (Variation 2) Figure 12 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 to each other 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 that it includes two membrane separation devices 100A and 100B.

[0211] As described above, in the membrane separation system 1002, the membrane separation apparatuses 100A and 100B are connected in series. Specifically, the membrane separation system 1002 further includes a connection path 94 that connects the membrane separation apparatuses 100A and 100B to each other. The connection path 94 is connected to the untreated fluid outlet 50c of the membrane separation apparatus 100A and the feed fluid inlet 50a of the membrane separation apparatus 100B. The feed fluid inlet 50a of the membrane separation apparatus 100A is connected to a feed fluid supply path 91, and the untreated fluid outlet 50c of the membrane separation apparatus 100B is connected to a untreated fluid discharge path 93.

[0212] The permeate discharge path 92 has a first portion 92A and a second portion 92B. The first portion 92A is connected to the permeate outlet 50b of the membrane separation device 100A, and the second portion 92B is connected to the permeate outlet 50b of the membrane separation device 100B. The first portion 92A and the second portion 92B are joined at a joining position 95.

[0213] For example, two pressure reducing devices 300A and 300B are disposed in the permeate discharge path 92. The pressure reducing device 300A is located between the membrane separation device 100A and the confluence position 95 and can reduce the pressure in the permeate space 100b of the membrane element 20 included in the membrane separation device 100A. The pressure reducing device 300B is located between the membrane separation device 100B and the confluence position 95 and can reduce the pressure in the permeate space 100b of the membrane element 20 included in the membrane separation device 100B. However, a single pressure reducing device may be disposed in the permeate discharge path 92, and this pressure reducing device may be located between the confluence position 95 and the recovery section 400. In other words, a single pressure reducing device may be shared by the membrane separation devices 100A and 100B.

[0214] In the membrane separation system 1002, the separation membrane 24a of the membrane element 20 included in the membrane separation apparatus 100A may be the same as or different from the separation membrane 24a of the membrane element 20 included in the membrane separation apparatus 100B, except for the membrane area. 2 ) relative to the membrane area (m 2 The ratio of

[0215] As an example, the membrane separation system 1002 can be operated by the following method. First, a pump (not shown) is operated to supply a feed fluid F1 from the tank 200 to the membrane separation apparatus 100A, and then the feed fluid F1 is supplied from the membrane separation apparatus 100A to the membrane separation apparatus 100B. This allows the feed fluid F1 to be supplied to the filtration member 10 of the membrane separation apparatus 100A and the filtration member 10 of the membrane separation apparatus 100B. In each of the membrane separation apparatuses 100A and 100B, the filtrate F2 that has passed through the filtration section 11 of the filtration member is supplied to the membrane element 20 and comes into contact with the separation membrane 24a.

[0216] Next, the permeate space 100b of the membrane separation apparatus 100A is depressurized through the permeate fluid outlet 50b, and the permeate space 100b of the membrane separation apparatus 100B is depressurized through the permeate fluid outlet 50b. This allows membrane separation operation to be performed in both the membrane separation apparatuses 100A and 100B, and permeate fluid F4 can be obtained from each of the membrane separation apparatuses 100A and 100B. Note that the untreated fluid F6 that was not treated in the membrane separation apparatus 100A is sent to the membrane separation apparatus 100B through the connecting path 94 and is further treated therein.

[0217] Next, the pressure in the permeate space 100b of at least one of the membrane separation devices 100A and 100B is increased, and the membrane separation operation is terminated.

[0218] (Variation 3) Figure 13 is a schematic diagram showing a variation 3 of the membrane separation system 1000 of this embodiment. The membrane separation system 1003 of variation 3 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 1003 has the same configuration as the membrane separation system 1000, except that it includes two membrane separation devices 100A and 100B.

[0219] As described above, in the membrane separation system 1003, the membrane separation apparatuses 100A and 100B are connected in parallel to each other. Specifically, the feed fluid supply path 91 has a first portion 91A and a second portion 91B. The first portion 91A of the feed fluid supply path 91 is connected to the feed fluid inlet 50a of the membrane separation apparatus 100A, and the second portion 91B is connected to the feed fluid inlet 50a of the membrane separation apparatus 100B. The second portion 91B branches off from the first portion 91A at a branching position 96. The branching position 96 is located between the tank 200 and the membrane separation apparatus 100A.

[0220] Furthermore, the untreated fluid discharge path 93 has a first portion 93A and a second portion 93B. The first portion 93A of the untreated fluid discharge path 93 is connected to the untreated fluid outlet 50c of the membrane separation device 100A, and the second portion 93B is connected to the untreated fluid outlet 50c of the membrane separation device 100B. The first portion 93A and the second portion 93B are joined at a joining position 97. The joining position 97 is located, for example, between the tank 200 and the membrane separation device 100A.

[0221] Similar to the membrane separation system 1002 of Modification 2, the permeate discharge path 92 has a first portion 92A and a second portion 92B. The first portion 92A is connected to the permeate outlet 50b of the membrane separation apparatus 100A, and the second portion 92B is connected to the permeate outlet 50b of the membrane separation apparatus 100B. The first portion 92A and the second portion 92B are joined at a joining position 95.

[0222] For example, two pressure reducing devices 300A and 300B are disposed in the permeate discharge path 92. The pressure reducing device 300A is located between the membrane separation device 100A and the confluence position 95 and can reduce the pressure in the permeate space 100b of the membrane element 20 included in the membrane separation device 100A. The pressure reducing device 300B is located between the membrane separation device 100B and the confluence position 95 and can reduce the pressure in the permeate space 100b of the membrane element 20 included in the membrane separation device 100B. However, a single pressure reducing device may be disposed in the permeate discharge path 92, and this pressure reducing device may be located between the confluence position 95 and the recovery section 400. In other words, a single pressure reducing device may be shared by the membrane separation devices 100A and 100B.

[0223] In the membrane separation system 1003, the separation membrane 24a of the membrane element 20 included in the membrane separation apparatus 100A may be the same as or different from the separation membrane 24a of the membrane element 20 included in the membrane separation apparatus 100B. 2 ) relative to the membrane area (m 2 The ratio of

[0224] As an example, the membrane separation system 1003 can be operated by the following method. First, a pump (not shown) is operated to supply a feed fluid F1 from the tank 200 to each of the membrane separation apparatuses 100A and 100B. This allows the feed fluid F1 to be supplied to each of the filtration members 10 of the membrane separation apparatus 100A and 100B. In each of the membrane separation apparatuses 100A and 100B, a filtrate F2 that has passed through the filtration section 11 of the filtration member is supplied to the membrane element 20 and comes into contact with the separation membrane 24a.

[0225] Next, the permeate space 100b of the membrane separation device 100A is depressurized through the permeate fluid outlet 50b, and the permeate space 100b of the membrane separation device 100B is depressurized through the permeate fluid outlet 50b. This allows membrane separation operation to be performed in both the membrane separation devices 100A and 100B, and permeate fluid F4 can be obtained from each of the membrane separation devices 100A and 100B.

[0226] Next, the pressure in the permeate space 100b of at least one of the membrane separation devices 100A and 100B is increased, and the membrane separation operation is terminated.

[0227] The present invention will be explained in more detail below with reference to examples and reference examples, but the present invention is not limited thereto.

[0228] The membrane separation devices of Examples 1 and 2 and Comparative Example 1 were evaluated to see whether or not fluid remained inside the membrane separation device.

[0229] <Membrane Separation Apparatus> A membrane separation apparatus having the configuration shown in Figure 1 was used as the membrane separation apparatus in Examples 1 and 2. A conventional membrane separation apparatus having the configuration shown in Figure 14 was used as the membrane separation apparatus in Comparative Example 1. A spiral membrane element having an outer diameter including the exterior material of 56 mm and an axial length of the element body of 240 mm was used. In the membrane separation apparatuses of Examples 1 and 2, a filtration member equipped with a 100-mesh SUS wire mesh (95% separation particle size: 185 µm) was used as the filtration section.

[0230] [Separation membrane] A pervaporation membrane prepared by the following method was used as the separation membrane. 1.650 kg (solids concentration 30 wt%) of silicone resin (YSR3022 manufactured by Momentive Performance Materials Japan), 2.805 kg of toluene, 0.495 kg of high-silica zeolite (HiSiv3000 manufactured by Resonac Universal Co., Ltd.), 0.0495 kg of silicone curing catalyst (YC6831 manufactured by Momentive Performance Materials Japan Co., Ltd.), and 0.0495 kg of acetylacetone as a curing retarder were mixed to prepare a coating solution. Next, the coating solution was applied onto a 150 μm thick porous support (RS-50 manufactured by Nitto Denko Corporation) to obtain a coating membrane (thickness 500 μm). The coating membrane was heated at 90 ° C. for 4 minutes and dried to produce a 50 μm thick separation functional layer. In the separating functional layer, the weight ratio of the silicone resin to the high-silica zeolite was 50: 50. This resulted in a pervaporation membrane.

[0231] (Solid-Containing Feed Fluid) A pulp dispersion prepared by the following method was used as the solid-containing feed fluid. The pulp dispersion is a simulated fermentation broth containing volatile organic compounds. The pulp dispersion was prepared by adding reverse osmosis membrane (RO membrane) water to a pulp sheet (hardwood bleached pulp (LBKP)) and stirring with a magnetic stirrer for 30 minutes. The amount of pulp sheet added was adjusted so that the pulp content as solid matter in the pulp dispersion was approximately 0.1 wt %.

[0232] (Method for measuring the solid content in a liquid) Approximately 30 g (weight w1) of liquid was collected in an aluminum cup, and the water was evaporated on a hot plate heated to 140°C. After visually confirming that the water had completely evaporated, the liquid was heated for an additional 10 minutes, and the weight after heating, w2, was measured. The weight w3 of the solid matter was calculated from the difference between w2 and w1. The content (wt%) of the solid matter in the liquid was calculated based on the weight w3 of the solid matter.

[0233] (Continuous Operation Test) A continuous operation test was conducted on the membrane separation devices of Examples 1 and 2 and Comparative Example 1, in which a pulp dispersion was continuously supplied at a flow rate of 380 g / min for 30 minutes. After 30 minutes of operation, the supply of the pulp dispersion was stopped, and for the membrane separation devices of Examples 1 and 2, the solid content (wt%) of the filtrate and non-filtrate was measured. For the membrane separation device of Comparative Example 1, the solid content (wt%) of the non-permeate and the liquid retained in the upstream space was measured. Furthermore, for the membrane separation devices of Examples 1 and 2, the flow rates (g / min) of the filtrate and non-filtrate were measured, and the sum of these flow rates was calculated. The proportion (%) of the filtrate was calculated by dividing the flow rate of the filtrate by the total flow rate. For the membrane separation device of Comparative Example 1, the flow rate (g / min) of the non-permeate was measured. Furthermore, throughout the continuous operation test, the membrane separation devices of Examples 1 and 2 and Comparative Example 1 were visually inspected for the presence or absence of liquid retention in the upstream space. Furthermore, the solid content (flow rate) (g / min) for each liquid was calculated based on the solid content (wt%) and flow rate (g / min). The results are shown in Tables 1 to 3. Note that the filtrate, non-filtrate, and non-permeated liquid in Tables 1 to 3 correspond to the filtrate fluid, non-filtrate fluid, and non-permeated fluid described in the above embodiment, respectively.

[0234]

[0235]

[0236]

[0237] As shown in Table 2, in Comparative Example 1, liquid retention occurred in the upstream space from the beginning of continuous operation, making it immediately unusable. In contrast, in Examples 1 and 2, liquid retention in the upstream space was almost nonexistent throughout continuous operation. In particular, in Example 1, liquid retention did not occur at all throughout continuous operation. Furthermore, as shown in Table 3, in Example 1, there was no significant change in the solids content (g / min) of the pulp dispersion and the total solids content (g / min) of the filtrate and non-filtrate. From these results, it can be determined that in Example 1, liquid retention in the upstream space was almost nonexistent throughout continuous operation. In Example 2, the total solids content (g / min) of the filtrate and non-filtrate decreased to about half the solids content (g / min) of the pulp dispersion. From these results, it can be determined that liquid retention occurred over time in Example 2. On the other hand, in Comparative Example 1, the solids content (g / min) of the non-permeated liquid decreased to nearly zero. From this result, it is judged that in Comparative Example 1, liquid accumulation occurred from the early stage of operation.

[0238] In Examples 1 and 2, the same membrane separation device was used, but continuous operation was performed with different filtrate percentages. The results in Table 2 show that when the filtrate percentage is about 30%, liquid retention in the upstream space is less likely to occur during continuous operation. From these results, it is inferred that by appropriately adjusting the flow rate of the filtrate supplied to the membrane element, fluid retention inside the membrane separation device can be further suppressed.

[0239] The membrane separation system of this embodiment is suitable for efficiently separating, for example, a solvent or a volatile organic compound from a solution containing the solvent or the organic compound.

Claims

1. A membrane separation device comprising: a filtration member having a filtration section that separates a feed fluid containing solids into a filtrate fluid and a non-filtrate fluid; and a spiral membrane element to which the filtrate fluid is supplied.

2. The membrane separation apparatus according to claim 1, further comprising a casing in which the filtering member and the membrane element are housed.

3. The membrane separation device according to claim 1, wherein the space adjacent to the outer peripheral surface of said membrane element forms a flow path for said non-filtrate fluid.

4. The membrane separation device according to claim 1, wherein the filtration member has a filtration flow path through which the filtrate fluid flows and a non-filtration flow path through which the non-filtration fluid flows, the filtration flow path communicating with a supply space located inside the membrane element, and the non-filtration flow path communicating with a space adjacent to the outer peripheral surface of the membrane element.

5. The membrane separation device according to claim 1, wherein the filtering member has a protrusion that protrudes in the axial direction of the membrane element, and the filtering portion is disposed on at least a part of the side surface of the protrusion.

6. The membrane separation device according to claim 1, wherein the filtration section includes a porous member.

7. The membrane separation apparatus according to claim 1, further comprising an end member disposed at the feed side end in the axial direction of the membrane element, the end member including the filtration member.

8. The membrane separation device according to claim 1, wherein the membrane element comprises a central tube having through holes, and a membrane leaf having a separation membrane and wound around the central tube.

9. The membrane separation apparatus according to claim 8, wherein the feed fluid is a solution containing at least one selected from the group consisting of solvents and volatile organic compounds, and the separation membrane is a pervaporation membrane.

10. A membrane separation system comprising the membrane separation device according to any one of claims 1 to 9.

11. The membrane separation system according to claim 10, further comprising an adjusting mechanism for adjusting the flow rate of the filtrate fluid supplied to the membrane element.

12. An end member for a spiral-wound membrane element, which is disposed at the end of the spiral-wound membrane element on the feed side in the axial direction, and which is equipped with a filtration section that separates a feed fluid containing solids into a filtrate fluid and a non-filtrate fluid.

13. A method for operating a membrane separation system equipped with a membrane separation device having a filtration element having a filtration section that separates a supply fluid containing solids into a filtrate fluid and a non-filtrate fluid, and a spiral membrane element to which the filtrate fluid is supplied, the method comprising: separating the supply fluid into the filtrate fluid and the non-filtrate fluid by the filtration section of the filtration element; and separating the filtrate fluid into a permeate fluid and a non-permeate fluid by the membrane element.

14. The method of operating a membrane separation system according to claim 13, further comprising gradually increasing the flow rate of the filtrate fluid supplied to the membrane element.

15. The method for operating a membrane separation system according to claim 14, wherein gradually increasing the flow rate of the filtrate fluid includes at least one selected from the group consisting of: (i) gradually increasing the pressure difference between the feed fluid and the non-permeate fluid, and (ii) gradually increasing the flow rate of the non-permeate fluid.

16. The method for operating a membrane separation system according to claim 15, further comprising: an adjusting mechanism for adjusting the flow rate of the filtrate fluid supplied to the membrane element; wherein in (i), the adjusting mechanism is controlled based on the monitoring results of the pressure of the supply fluid and the pressure of the non-permeated fluid, thereby gradually increasing the pressure difference between the supply fluid and the non-permeated fluid; and in (ii), the adjusting mechanism is controlled based on the monitoring results of the flow rate of the non-permeated fluid, thereby gradually increasing the flow rate of the non-permeated fluid.

17. The method for operating a membrane separation system according to claim 13, wherein the membrane separation device further comprises a casing in which the filtration member and the membrane element are housed.

18. The method for operating a membrane separation system according to claim 13, wherein the membrane separation device further has an end member disposed at the feed side end in the axial direction of the membrane element, and the end member includes the filtration member.

19. The method for operating a membrane separation system according to claim 13, wherein the membrane element comprises a central tube having a through hole, and a membrane leaf having a separation membrane and wound around the central tube.

20. The method for operating a membrane separation system according to claim 19, wherein the feed fluid is a solution containing at least one selected from the group consisting of solvents and volatile organic compounds, and the separation membrane is a pervaporation membrane.

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