Spiral membrane element and membrane separation device

Abstract

Provided is a novel spiral membrane element suitable for efficiently recovering a permeated fluid. This spiral membrane element (10) is provided with: a central tube (21); a separation membrane (12) that is wound around the central tube (21) and separates a supplied fluid (S) into a permeated fluid (S1) and a non-permeated fluid (S2); and a supply space and a permeated space that are separated by the separation membrane (12). The permeable space communicates with the external space 30 of the spiral membrane element 10 via the outer peripheral surface 10s of the spiral membrane element 10.

Description

Technical Field

[0001] The invention relates to a spiral membrane element and a membrane separation device. Background Art

[0002] As a method for separating acidic gases from mixed gases containing acidic gases such as carbon dioxide, membrane separation has been developed. Compared with absorption methods in which acidic gases contained in mixed gases are absorbed by absorbents to separate them, membrane separation methods can efficiently separate acidic gases while suppressing operating costs.

[0003] For example, a spiral membrane element is used in the membrane separation method. The spiral membrane element has a central tube and a separation membrane wound on the central tube. In the conventional spiral membrane element, the permeated fluid that has passed through the separation membrane is introduced into the interior of the central tube through an opening formed in the central tube. The permeated fluid collected through the opening of the central tube moves inside the central tube and is sent to the outside of the spiral membrane element. Patent document 1 discloses an example of a conventional spiral membrane element.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2015-024372 Summary of the invention

[0007] Problems to be solved by the invention

[0008] There is a need for new spiral membrane elements suitable for efficiently recovering permeated fluid.

[0009] Means for solving problems

[0010] The present invention provides a spiral membrane element, which comprises:

[0011] Central tube;

[0012] a separation membrane wound around the central tube and separating a feed fluid into a permeated fluid and a non-permeated fluid; and

[0013] The supply space and the permeate space separated by the separation membrane,

[0014] The permeation space is communicated with the external space of the spiral membrane element via the outer peripheral surface of the spiral membrane element.

[0015] In addition, the present invention provides a spiral membrane element, which comprises:

[0016] Central tube;

[0017] a separation membrane wound around the central tube and separating a feed fluid into a permeated fluid and a non-permeated fluid; and

[0018] The supply space and the permeate space separated by the separation membrane,

[0019] The permeated fluid is transported from the permeation space to the external space of the spiral membrane element through the outer peripheral surface of the spiral membrane element.

[0020] In addition, the present invention also provides a membrane separation device, which comprises:

[0021] The above spiral membrane element; and

[0022] A housing for housing the spiral membrane element.

[0023] Effects of the Invention

[0024] According to the present invention, a novel spiral membrane element suitable for efficiently recovering a permeated fluid can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] [ Figure 1 ] is a perspective view schematically showing an expanded spiral membrane element according to one embodiment of the present invention.

[0026] [ Figure 2 ] is a schematic cross-sectional view of a spiral membrane element.

[0027] [ Figure 3 ] is a schematic cross-sectional view of a separation membrane included in a spiral membrane element.

[0028] [ Figure 4A ] is a diagram for illustrating a method for manufacturing a spiral membrane element.

[0029] [ Figure 4B ] is a diagram for illustrating a method for manufacturing a spiral membrane element.

[0030] [ Figure 5 ] is a schematic cross-sectional view showing an example of a membrane separation device.

[0031] [ Figure 6 ] is a schematic cross-sectional view showing another example of a membrane separation device. DETAILED DESCRIPTION

[0032] A spiral membrane element according to a first aspect of the present invention comprises:

[0033] Central tube;

[0034] A separation membrane wound around the central tube and separating a feed fluid into a permeated fluid and a non-permeated fluid; and

[0035] The supply space and the permeate space separated by the separation membrane,

[0036] The permeation space is communicated with the external space of the spiral membrane element via the outer peripheral surface of the spiral membrane element.

[0037] A spiral membrane element according to a second aspect of the present invention comprises:

[0038] Central tube;

[0039] A separation membrane wound around the central tube for separating a feed fluid into a permeated fluid and a non-permeated fluid; and

[0040] The supply space and the permeate space separated by the separation membrane,

[0041] The permeated fluid is transported from the permeation space to the external space of the spiral membrane element through the outer peripheral surface of the spiral membrane element.

[0042] In a third aspect of the present invention, for example, the spiral membrane element of the first or second aspect further includes a first flow path material constituting the outer peripheral surface and through which the permeated fluid can pass.

[0043] In a fourth aspect of the present invention, for example, the spiral membrane element according to the third aspect further includes a permeation spacer disposed in the permeation space, and the permeation spacer is connected to the first flow path material.

[0044] In a fifth aspect of the present invention, for example, the spiral membrane element of the fourth aspect further includes a second flow path material connected to the permeate spacer and wound around the center tube on the center tube side relative to the separation membrane.

[0045] In a sixth aspect of the present invention, for example, the spiral membrane element according to any one of the first to fifth aspects further includes a supply spacer disposed in the supply space, wherein the supply spacer is surrounded by the separation membrane folded in two.

[0046] In the seventh aspect of the present invention, for example, in the spiral membrane element of any one of the first to sixth aspects, the center tube has an opening that connects the inside and outside of the center tube, and the permeable space communicates with the inside of the center tube through the opening.

[0047] In the 8th aspect of the present invention, for example, the spiral membrane element of the 7th aspect transports a portion of the permeated fluid from the permeation space to the external space through the outer peripheral surface, and transports the remaining permeated fluid from the permeation space to the interior of the central tube through the opening.

[0048] In a ninth aspect of the present invention, for example, the spiral membrane element according to any one of the first to eighth aspects is used to separate carbon dioxide from a mixed gas containing carbon dioxide and nitrogen.

[0049] A membrane separation device according to a tenth aspect of the present invention comprises:

[0050] The spiral membrane element according to any one of the first to ninth aspects; and

[0051] A housing for housing the spiral membrane element.

[0052] In the 11th aspect of the present invention, for example, in the membrane separation device of the 10th aspect, the housing has a permeated fluid outlet for discharging the permeated fluid transported from the permeation space through the outer peripheral surface of the spiral membrane element to the outside.

[0053] In the twelfth aspect of the present invention, for example, the membrane separation device of the tenth or eleventh aspect further comprises a first sealing portion arranged around the spiral membrane element, which prevents the supply fluid from flowing into the space between the outer peripheral surface of the spiral membrane element and the inner peripheral surface of the shell.

[0054] In the 13th embodiment of the present invention, for example, the membrane separation device of any one of the 10th to 12th embodiments further comprises a second sealing portion arranged around the above-mentioned spiral membrane element, and the second sealing portion prevents the above-mentioned non-permeable fluid from flowing into the space between the above-mentioned outer peripheral surface of the above-mentioned spiral membrane element and the inner peripheral surface of the above-mentioned shell.

[0055] Hereinafter, the present invention will be described in detail, but the following description is not intended to limit the present invention to specific embodiments.

[0056] <Embodiment of spiral membrane element>

[0057] Figure 1 and Figure 2 The spiral membrane element 10 (hereinafter referred to as "separation membrane element 10") of the present embodiment is shown. The separation membrane element 10 includes a central tube 21 and a stacked body 22 having a separation membrane 12. The stacked body 22 is wound around the central tube 21 and arranged around the central tube 21. In other words, the separation membrane 12 is wound around the central tube 21. The separation membrane 12 can separate the supply fluid S into a permeated fluid S1 and a non-permeated fluid S2.

[0058] The separation membrane element 10 further includes a supply space (supply fluid flow path) and a permeate space (permeate fluid flow path) separated by the separation membrane 12. The supply space and the permeate space are formed inside the stack 22. In the separation membrane element 10 of the present embodiment, the permeate space is connected to the external space 30 of the separation membrane element 10 via the outer peripheral surface 10s of the separation membrane element 10. The separation membrane element 10 can transport the permeate fluid S1 from the permeate space to the external space 30 via the outer peripheral surface 10s.

[0059] In detail, during the operation of the separation membrane element 10, the supply fluid S is supplied to the interior of the separation membrane element 10 from one end surface of the stack 22, and flows in the supply space in parallel with the length direction of the central tube 21. The supply fluid S is separated by the separation membrane 12 to generate a permeable fluid S1 and a non-permeable fluid S2. The permeable fluid S1 is discharged from the permeable space to the external space 30 through the outer peripheral surface 10s of the separation membrane element 10. However, a part of the permeable fluid S1 can also be guided to the outside through the central tube 21. The non-permeable fluid S2 is discharged from the other end surface of the stack 22 to the outside of the separation membrane element 10. It should be noted that in this specification, the outer peripheral surface 10s refers to the outer peripheral surface of the separation membrane element 10 in a cross section perpendicular to the length direction of the central tube 21.

[0060] The feed fluid S to be treated by the separation membrane element 10 may be either a gas or a liquid. As an example, the feed fluid S is a mixed gas containing an acidic gas, particularly a mixed gas containing carbon dioxide and nitrogen.

[0061] like Figure 2 As shown, the stacked body 22 includes a plurality of separation membrane units U. Each separation membrane unit U is wound around a central tube 21. The number of separation membrane units U in the stacked body 22 is not particularly limited, and is, for example, 2 to 40.

[0062] Each separation membrane unit U includes a structure 11 composed of a separation membrane 12 and a supply spacer 13, and a permeate spacer 14. Figure 2 , the supply spacer 13 and the permeate spacer 14 are indicated by dotted lines. In the separation membrane unit U, the separation membrane 12 is folded into two parts, and the ends thereof are joined in such a manner that the separation membrane 12 has a cylindrical structure. In the stack 22, the inside of the cylindrical structure corresponds to the supply space, and the outside of the cylindrical structure corresponds to the permeate space. For example, thermal fusion (heat sealing, ultrasonic welding, etc.) can be used to join the ends of the separation membrane 12. However, as Figure 2 As shown, the end portions of the separation membrane 12 may be bonded using an adhesive layer 26 containing an adhesive.

[0063] The supply spacer 13 is disposed in the supply space. Specifically, the supply spacer 13 is surrounded by the separation membrane 12 folded in two, and ensures a space serving as a flow path for the supply fluid.

[0064] The permeable spacer 14 is disposed in the permeable space and is stacked on the separation membrane 12 (specifically, the structure 11 composed of the separation membrane 12 and the supply spacer 13). In the stack 22, a plurality of structures 11 and a plurality of permeable spacers 14 are alternately stacked. The permeable spacer 14 ensures a space as a permeable fluid flow path between two structures 11. Two adjacent structures 11 separated by the permeable spacer 14 are located near one end surface of the stack 22 to which the supply fluid S is supplied (for example, Figure 2 The vicinity of the end face of the stack 22 on the inner side of the paper surface) and the vicinity of the other end face of the stack 22 from which the non-permeable fluid S2 is discharged (for example, Figure 2 The laminate 22 is bonded to each other near the end surface of the laminate 22 near the front side of the paper. Figure 2 In the example of FIG. 1 , one transmissive spacer 14 is disposed between two structures 11. However, a plurality of transmissive spacers 14 (particularly two transmissive spacers 14) may be disposed between two structures 11 in a stacked state.

[0065] like Figure 2 As shown, the shape of the center tube 21 is typically cylindrical, particularly cylindrical. The center tube 21 can, for example, collect a portion of the permeated fluid S1 that has passed through each separation membrane 12 and guide it to the outside of the separation membrane element 10. An opening 21h that connects the inside of the center tube 21 with the outside is provided in the center tube 21. Thus, the permeate space is connected to the inside of the center tube 21 through the opening 21h. The opening 21h is, for example, a through hole formed on the wall of the center tube 21. In detail, in the center tube 21, a plurality of openings 21h are provided at prescribed intervals along the direction in which the center tube 21 extends. The number of columns of the plurality of openings 21h provided along the direction in which the center tube 21 extends is not particularly limited, and is, for example, 1 or 2. In the center tube 21, two columns of the plurality of openings 21h can also be provided in a mutually opposing manner. The outer diameter of the center tube 21 is, for example, 10 to 100 mm, preferably 12 to 50 mm.

[0066] The separation membrane element 10 further includes a first flow path material 15 constituting the outer peripheral surface 10s thereof. Specifically, the first flow path material 15 is wound around the central tube 21 on the outer side of the stack 22 so as to surround the stack 22. The permeate spacer 14 included in the stack 22 is connected to the first flow path material 15. On the other hand, in the separation membrane element 10, the supply spacer 13 and the first flow path material 15 are not connected to each other.

[0067] The first flow path material 15 is configured to allow the permeate fluid S1 to pass therethrough. For example, the first flow path material 15 has an opening (gap) through which the permeate fluid S1 can be transported from the permeate space to the external space 30. In this manner, the separation membrane element 10 of the present embodiment can, for example, transport the permeate fluid S1 from the permeate space to the external space 30 through the first flow path material 15 constituting the outer peripheral surface 10s. In the separation membrane element 10, the permeate space is connected to the external space 30 through the first flow path material 15 constituting the outer peripheral surface 10s.

[0068] The separation membrane element 10 further includes a second flow path material 16. The second flow path material 16 is located between the central tube 21 and the stack 22, and is wound around the central tube 21 on the central tube 21 side relative to the stack 22 (and the separation membrane 12). The second flow path material 16 ensures a space as a permeate fluid flow path between the stack 22 and the central tube 21. The second flow path material 16 is connected to the permeate spacer 14 included in the stack 22. The second flow path material 16 is in contact with the opening 21h of the central tube 21. As a result, a portion of the permeate fluid S1 can flow from the second flow path material 16 into the interior of the central tube 21 through the opening 21h.

[0069] Examples of the supply spacer 13, the permeable spacer 14, the first flow path material 15, and the second flow path material 16 include a net, a screen, a wire fabric, a fiber fabric, a nonwoven fabric, a grooved sheet, a corrugated sheet, etc. Examples of the materials of these spacers 13 and 14, and the flow path materials 15 and 16 include resin materials such as polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polyamide, polyphenylene sulfide (PPS), ethylene-chlorotrifluoroethylene copolymer (ECTFE), epoxy resin, and urethane resin; natural polymers; rubber; metal; and the like.

[0070] The thickness of the spacers 13 and 14, and the flow path materials 15 and 16 is not particularly limited, and is, for example, 100 μm to 2000 μm. The opening ratio of the spacers 13 and 14, and the flow path materials 15 and 16 is not particularly limited, and is, for example, 10% to 80%. The opening ratio of the spacer (or flow path material) can be determined by the following method. First, the spacer (or flow path material) to be measured is arranged on the membrane, and the surface of the spacer is observed with a scanning electron microscope (SEM). Based on the obtained electron microscope image, the area C1 of the surface of the spacer and the area C2 (the area of ​​the gap formed on the spacer) through which the membrane can be confirmed are calculated by image processing. The ratio of area C2 to area C1 can be determined as the opening ratio.

[0071] It should be noted that the structure and material of the permeable spacer 14 are typically the same as those of the first flow path material 15 and the second flow path material 16. However, their structures and materials may be different from each other.

[0072] In the separation membrane element 10 , in order to protect the end faces of the stacked body 22 and prevent the stacked body 22 from expanding in a sleeve-like manner, end face members may be disposed on both sides of the stacked body 22 .

[0073] [Separation membrane]

[0074] like Figure 3 As shown, the separation membrane 12 includes, for example, a separation functional layer 1, a porous support 3 supporting the separation functional layer 1, and an intermediate layer 2 disposed between the separation functional layer 1 and the porous support 3. The intermediate layer 2 is, for example, directly in contact with each of the separation functional layer 1 and the porous support 3. However, the separation membrane 12 may not include the intermediate layer 2.

[0075] (Separation Functional Layer)

[0076] The separation functional layer 1 is, for example, a layer that allows the acidic gas contained in the mixed gas to pass preferentially. The separation functional layer 1 preferably contains a resin. Examples of the resin contained in the separation functional layer 1 include: polyether block amide resins, polyamide resins, polyether resins, polyimide resins, polyetherimide resins, cellulose acetate resins, silicone resins, fluororesins, and polyurethane resins. The separation functional layer 1 preferably contains a polyimide resin or a cellulose acetate resin, and more preferably contains a cellulose acetate resin. The separation functional layer 1 is preferably substantially formed of a resin. In this specification, "substantially formed of" means excluding other components that will change the essential characteristics of the material mentioned, for example, it means that more than 95wt%, and further more than 99wt% is composed of the material.

[0077] The thickness of the separation functional layer 1 is, for example, 50 μm or less, preferably 25 μm or less, and more preferably 15 μm or less. The thickness of the separation functional layer 1 may be 0.05 μm or more, or 0.1 μm or more.

[0078] (Middle layer)

[0079] The intermediate layer 2 may include, for example, a resin, and may also include nanoparticles dispersed in the resin (matrix). The nanoparticles may be separated from each other in 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 includes a silicone resin.

[0080] Nanoparticles may contain inorganic materials or organic materials. Examples of inorganic materials contained in nanoparticles include silicon dioxide, titanium dioxide, and aluminum oxide. Preferably, the nanoparticles contain silicon dioxide.

[0081] The thickness of the intermediate layer 2 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 2 is not particularly limited, and is, for example, 1 μm. The intermediate layer 2 is, for example, a layer having a thickness of less than 50 μm.

[0082] (Porous Support)

[0083] The porous support 3 supports the separation functional layer 1 via the intermediate layer 2. Examples of the porous support 3 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; a permeable (porous) polymer containing at least one selected from the group consisting of polyvinyl fluoride, polyvinylidene fluoride, polyurethane, polypropylene, polyethylene, polystyrene, polycarbonate, polysulfone, polyetheretherketone, polyacrylonitrile, polyimide, and polyphenylene ether; a metal foam having open or closed cells; a polymer foam having open or closed cells; silicon dioxide; porous glass; a mesh, and the like. The porous support 3 may be a combination of two or more of these.

[0084] The porous support 3 has an average pore size of, for example, 0.01 to 0.4 μm. The thickness of the porous support 3 is not particularly limited, and is, for example, 10 μm or more, preferably 20 μm or more, and more preferably 50 μm or more. The thickness of the porous support 3 is, for example, 300 μm or less, preferably 200 μm or less, and more preferably 150 μm or less.

[0085] [Method for manufacturing spiral membrane element]

[0086] Reference Figure 4A and 4B An example of a method for manufacturing the separation membrane element 10 is described. Figure 4A As shown, the separation membrane 12 is folded into two parts in such a manner that the separation functional layer 1 of the separation membrane 12 is located on the inner side. A supply spacer 13 is arranged between the separation membrane 12 folded into two parts. The ends of the separation membrane 12 are joined in such a manner that the separation membrane 12 has a cylindrical structure. Thus, a structure 11 consisting of the separation membrane 12 and the supply spacer 13 is obtained. As described above, the ends of the separation membrane 12 are joined, for example, by heat welding. However, as Figure 4AAs shown, for the purpose of joining the end portions, an adhesive 26a may also be applied. At this point, the adhesive 26a may be in an uncured state or may be cured.

[0087] Next, a permeable spacer 14 is arranged on the separation membrane 12. Furthermore, an adhesive 27a is applied to two mutually opposing sides of the outer periphery of the permeable spacer 14. Thus, a separation membrane unit U is obtained. The adhesive 27a is in an uncured state at this moment. It should be noted that a plurality of permeable spacers 14 (particularly two permeable spacers 14) may be stacked on the separation membrane 12. That is, the separation membrane unit U may also have a plurality of permeable spacers 14.

[0088] Then, if Figure 4B As shown, a central tube 21, a flow path material 17, and a plurality of separation membrane units U are prepared. The flow path material 17, for example, includes a first portion 17a directly wound around the central tube 21, a second portion 17b stacked with the separation membrane unit U, and a third portion 17c connected to the second portion 17b and extending from the second portion 17b to the opposite side of the central tube 21. The first portion 17a of the flow path material 17 corresponds to the second flow path material 16 described above, the second portion 17b corresponds to the permeable spacer 14, and the third portion 17c corresponds to the first flow path material 15. The plurality of separation membrane units U are arranged in a stepped manner on the second portion 17b of the flow path material 17. The number of the plurality of separation membrane units U is not particularly limited, and is, for example, 2 to 40. It should be noted that the separation membrane unit U located at the top may not have the permeable spacer 14.

[0089] Next, the first portion 17a of the flow path material 17 is wound around the central tube 21, and then a plurality of separation membrane units U are wound. At this time, the separation membrane unit U located at the top is stacked with the second portion 17b of the flow path material 17. Next, the third portion 17c of the flow path material 17 is wound around the central tube 21 in a manner that surrounds the plurality of separation membrane units U. The number of turns of the first portion 17a and the third portion 17c is not particularly limited, and is, for example, 1 to 15, preferably 2 to 10.

[0090] After the separation membrane unit U is wound around the central tube 21, the adhesive 27a is cured to bond two adjacent structures 11 to each other via the permeable spacer 14. Thus, an assembly including the central tube 21 and the stacked body 22 is obtained.

[0091] [Characteristics of spiral membrane elements]

[0092] In a spiral membrane element, the difference between the pressure of the supply fluid and the pressure of the permeated fluid (pressure difference) is used as a driving force to perform membrane separation of the supply fluid using a separation membrane. Therefore, if pressure loss occurs in the spiral membrane element, the pressure difference decreases, and the permeation rate of the permeated fluid from the separation membrane decreases. In particular, according to the research of the inventors, in the conventional spiral membrane element that only transports the permeated fluid to the outside through the central tube, there is a tendency that the movement distance of the permeated fluid in the permeation space is long and the pressure loss is large.

[0093] In the separation membrane element 10 of the present embodiment, during operation, the permeated fluid S1 is sent from the permeation space to the external space 30 through the outer peripheral surface 10s of the separation membrane element 10. Specifically, the separation membrane element 10 can send a portion of the permeated fluid S1 from the permeation space to the external space 30 through the outer peripheral surface 10s, and send the remaining permeated fluid S1 from the permeation space to the inside of the central tube 21 through the opening 21h of the central tube 21. That is, in the separation membrane element 10 of the present embodiment, both the outer peripheral surface 10s and the central tube 21 function as the outlet of the permeated fluid S1. The permeated fluid S1 in the permeation space can flow out from the outlet with a short moving distance in the outer peripheral surface 10s and the central tube 21. As described above, in the separation membrane element 10 of the present embodiment, the moving distance of the permeated fluid S1 in the permeation space is short compared to the conventional spiral membrane element, which is suitable for suppressing pressure loss. That is, the separation membrane element 10 of the present embodiment is suitable for efficiently recovering the permeated fluid S1.

[0094] As the operation method of the separation membrane element 10 of the present embodiment, for example, the following methods can be adopted: a method of operating by reducing the pressure of the external space 30 adjacent to the outer peripheral surface 10s and the interior of the central tube 21 (decompression method); a method of supplying the pressurized supply fluid S to the supply space (pressurization method). In the separation membrane element 10 of the present embodiment, a method of supplying a sweep fluid to the permeation space from either the outer peripheral surface 10s or the central tube 21, and taking out the sweep fluid and the permeated fluid S1 from the other side (sweep method) can also be used. As the sweep fluid, there can be cited sweep gases such as air and argon. In particular, compared with the pressurization method, the decompression method and the sweep method can adjust the pressure difference between the supply fluid S and the permeated fluid S1 to be smaller, and are suitable for the operation method of the separation membrane element 10 of the present embodiment.

[0095] As an example, using carbon dioxide as the supply fluid, the ratio R of the carbon dioxide permeation rate T2 (GPU) from the separation membrane element 10 when the separation membrane element 10 is operated by the reduced pressure method to the carbon dioxide permeation rate T1 (GPU) from the flat membrane separation membrane 12 when the flat membrane separation membrane 12 is operated by the reduced pressure method is, for example, 85% or more, preferably 90% or more, 95% or more, 97% or more, and more preferably 99% or more.

[0096] In the decompression method for determining the permeation rates T1 and T2, the temperature of the supply fluid supplied to the flat membrane 12 or the separation membrane element 10 is 23°C and the pressure is 0.1 MPa. In the decompression method, a vacuum pump is used to reduce the pressure of the space where the permeation fluid is obtained to about 10 kPa or less. It should be noted that GPU refers to 10 -6 cm 3 (STP) / (secc·m 2 cmHg). 3 (STP) refers to the volume of carbon dioxide at 1 atmosphere and 0°C.

[0097] [Application of spiral membrane elements]

[0098] As the use of the separation membrane element 10 of the present embodiment, there can be cited the use of treating gases, in particular, the use of separating acidic gases from a mixed gas containing acidic gases. As acidic gases in the mixed gas, there can be cited carbon dioxide, hydrogen sulfide, carbonyl sulfide, sulfur oxides (SOx), hydrogen cyanide, nitrogen oxides (NOx), etc., preferably carbon dioxide. The mixed gas contains other gases other than acidic gases. As other gases, for example, non-polar gases such as hydrogen and nitrogen and inert gases such as helium can be cited, preferably nitrogen. In particular, the separation membrane element 10 of the present embodiment is suitable for the use of separating carbon dioxide from a mixed gas containing carbon dioxide and nitrogen. However, the use of the separation membrane element 10 is not limited to the above-mentioned use of separating acidic gases from a mixed gas.

[0099] <Embodiment of membrane separation device>

[0100] like Figure 5 As shown, the membrane separation device 100 of this embodiment includes the above-mentioned separation membrane element 10 and a housing 40 that accommodates the separation membrane element 10. The separation membrane element 10 is configured to be attachable to and detachable from the housing 40. As the housing 40, for example, a known high-pressure container can be used.

[0101] The housing 40 includes a housing body 41, a first end plate 42, and a second end plate 43. The housing body 41 has, for example, a cylindrical shape or a square cylindrical shape, and is made of a material having sufficient pressure resistance. The first end plate 42 is mounted on one end of the housing body 41 to close the end. The second end plate 43 is mounted on the other end of the housing body 41 to close the end.

[0102] The housing 40 has ports 41a, 42a, 43a, and 43b. These ports are used to connect the inside and outside of the housing 40. The port 41a is provided in the housing body 41, and functions as a permeate fluid outlet for discharging the permeate fluid S1 transported from the permeate space through the outer peripheral surface 10s of the separation membrane element 10 to the outside of the housing 40. The number of ports 41a may be one, or may be two or more.

[0103] The port 42a is provided on the first end plate 42, and functions as a supply fluid inlet for supplying the supply fluid S into the interior of the housing 40. The number of the port 42a may be one, or may be two or more.

[0104] The port 43a is provided on the second end plate 43, and functions as an impermeable fluid outlet for discharging the impermeable fluid S2 to the outside of the housing 40. The number of the port 43a may be one, or may be two or more.

[0105] The port 43b is provided on the second end plate 43 and connected to the central tube 21. The port 43b functions as a permeated fluid outlet for discharging the permeated fluid S1 sent from the permeation space to the inside of the central tube 21 to the outside of the housing 40.

[0106] Each of the ports 41a, 42a, 43a and 43b may be a simple opening or a Figure 5 The nozzle-shaped opening shown.

[0107] The membrane separation device 100 also includes a first sealing portion 45 and a second sealing portion 46 disposed around the separation membrane element 10. The first sealing portion 45 is disposed at the end portion on the upstream side of the separation membrane element 10, and can prevent the supply fluid S from flowing into the space 50 between the outer peripheral surface 10s of the separation membrane element 10 and the inner peripheral surface 40s of the shell 40. The second sealing portion 46 is disposed at the end portion on the downstream side of the separation membrane element 10, and can prevent the non-permeable fluid S2 from flowing into the above-mentioned space 50. In the membrane separation device 100, the inlet and outlet of the space 50 are blocked by the first sealing portion 45 and the second sealing portion 46. In other words, the space 50 is sealed by the first sealing portion 45 and the second sealing portion 46. It should be noted that the space 50 is equivalent to the above-mentioned external space 30.

[0108] As the first sealing portion 45 and the second sealing portion 46 , a seal having a U-shaped cross section (U-shaped gasket), an O-ring seal, or the like can be used.

[0109] The membrane separation device 100 can be operated, for example, by the following method. First, a supply fluid S is supplied to the interior of the housing 40 through the port 42a. The supply fluid S is supplied to the supply space of the separation membrane element 10 and moves in the supply space in the length direction of the central tube 21. At this time, the supply fluid S contacts one surface of the separation membrane 12. Next, in a state where the supply fluid S contacts one surface of the separation membrane 12, the permeation space adjacent to the other surface of the separation membrane 12 is depressurized. In detail, the space 50 is depressurized through the port 41a, and the interior of the central tube 21 is depressurized through the port 43b, thereby enabling the permeation space to be depressurized.

[0110] By depressurizing the permeation space, the supply fluid S permeates the separation membrane 12, and the permeated fluid S1 is supplied to the permeation space. A portion of the permeated fluid S1 (the permeated fluid S1 supplied to a position relatively close to the outer peripheral surface 10s) is transported from the permeation space to the space 50 through the outer peripheral surface 10s. The permeated fluid S1 is discharged to the outside of the membrane separation device 100 through the port 41a. The remaining permeated fluid S1 (the permeated fluid S1 supplied to a position relatively close to the central tube 21) is transported from the permeation space to the inside of the central tube 21 through the opening 21h of the central tube 21. The permeated fluid S1 is discharged to the outside of the membrane separation device 100 through the port 43b.

[0111] The feed fluid S (non-permeated fluid S2 ) treated by the separation membrane element 10 is discharged from the feed space of the separation membrane element 10 and discharged to the outside of the membrane separation device 100 through the port 43 a .

[0112] It should be noted that the operating method of the membrane separation device 100 is not limited to the above-mentioned decompression method, and a pressurization method in which the pressurized supply fluid S is supplied to the interior of the shell 40 or a purging method using a purging fluid may also be used. In the purging method, the purging fluid may be supplied from either the port 41a or the port 43b, and the permeated fluid S1 may be taken out from the other side together with the purging fluid. As an example, when the purging fluid is supplied from the port 43b, the purging fluid passes through the interior of the central tube 21 and is transported to the permeation space of the separation membrane element 10. The purging fluid and the permeated fluid S1 are mixed in the permeation space to obtain a mixed fluid. The mixed fluid is transported from the permeation space to the space 50 through the outer peripheral surface 10s of the separation membrane element 10, and then discharged to the outside of the membrane separation device 100 through the port 41a.

[0113] As described above, the pressure reduction method and the purge method can adjust the pressure difference between the supply fluid S and the permeate fluid S1 to be smaller than the pressurization method. Therefore, according to the pressure reduction method and the purge method, for example, there is a tendency that the supply fluid S can be sufficiently suppressed from leaking into the space 50 from the gap between the first sealing portion 45 and the separation membrane element 10, etc.

[0114] [Modification of membrane separation device]

[0115] In the membrane separation device 100 , the combination of the ports provided in the housing 40 is not limited to the above combination. Figure 6 The membrane separation device 110 shown has the same structure as the membrane separation device 100 except that the port 42b is provided on the first end plate 42 instead of the above-mentioned port 43b. Therefore, sometimes the same reference numerals are marked on the common elements in the above-mentioned membrane separation device 100 and the membrane separation device 110 of the modified example, and their description is omitted. That is, the description of each embodiment can be applied to each other as long as it is not technically contradictory. Moreover, the various embodiments can also be combined with each other as long as it is not technically contradictory.

[0116] As described above, the port 42b is provided on the first end plate 42 and connected to the central tube 21. The port 42b functions as a permeated fluid outlet for discharging the permeated fluid S1 sent from the permeation space to the inside of the central tube 21 to the outside of the housing 40.

[0117] In the membrane separation device 110, during operation, the permeated fluid S1 transported to the inside of the central tube 21 moves in the direction opposite to the direction in which the supply fluid S moves inside the separation membrane element 10. The membrane separation device 110 is a countercurrent flow type membrane separation device. During operation of the membrane separation device 110, the flow rate of the permeated fluid S1 transported to the inside of the central tube 21 is generally larger on the upstream side of the separation membrane element 10 (the inlet side of the supply fluid S) than on the downstream side of the separation membrane element 10 (the outlet side of the supply fluid S). In the membrane separation device 110, the permeated fluid S1 transported to the inside of the central tube 21 near the upstream of the separation membrane element 10 is immediately discharged from the port 42b. That is, in the membrane separation device 110, the permeated fluid S1 with a large flow rate moves a short distance inside the central tube 21. Therefore, it can be said that the membrane separation device 110 is suitable for reducing the pressure loss caused by the movement of the permeated fluid S1 inside the central tube 21.

[0118] <Embodiment of membrane separation system>

[0119] The membrane separation system of the present embodiment, for example, includes the above-mentioned membrane separation device 100 and a pressure reducing device. The membrane separation system may also include a membrane separation device 110 instead of the membrane separation device 100. The membrane separation system, for example, includes two pressure reducing devices. One of the two pressure reducing devices can reduce the pressure on the space 50 through the port 41a of the membrane separation device 100, and the other of the two pressure reducing devices can reduce the pressure on the inside of the central tube 21 through the port 43b. However, in the membrane separation system, it is also possible to configure one pressure reducing device to reduce the pressure on both the space 50 and the inside of the central tube 21. A specific example of the pressure reducing device is a vacuum device such as a vacuum pump.

[0120] The membrane separation system may include a plurality of membrane separation devices 100, and the plurality of membrane separation devices 100 may be connected in series or in parallel. In the present specification, "a plurality of membrane separation devices 100 are connected in series" means a configuration in which a plurality of membrane separation devices 100 are connected in series in such a manner that the supply fluid S (non-permeable fluid S2) discharged from the port 43a of the membrane separation device 100 at the front stage is transported to the port 42a of the membrane separation device 100 at the rear stage. "A plurality of membrane separation devices 100 are connected in parallel in such a manner that a plurality of membrane separation devices 100 are connected in parallel in such a manner that the supply fluid S is transported to the respective ports 42a of the plurality of membrane separation devices 100. The number of membrane separation devices 100 in the membrane separation system is not particularly limited, and is, for example, 2 to 5.

[0121] The membrane separation system may include an additional membrane separation device for further treating the permeated fluid S1 discharged from the membrane separation device 100. As the additional membrane separation device, a device having the same configuration as the membrane separation device 100 can be used.

[0122] Example

[0123] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[0124] (Example 1)

[0125] [Production of separation membrane]

[0126] First, a coating solution containing a silicone resin and a polyurethane resin in a weight ratio of 9:1 is prepared. The coating solution contains water as a solvent. Next, the coating solution is applied to a porous support by a gravure coating method, thereby obtaining a coating film. As a porous support, a UF membrane (ultrafiltration membrane) RS-50 (a laminate of a PVDF porous layer and a PET nonwoven fabric) manufactured by Nitto Denko Corporation is used. By drying the obtained coating film, a separation functional layer is formed. Thus, a separation membrane is obtained.

[0127] [Manufacturing of spiral membrane elements]

[0128] Using the central tube and the above separation membrane, by referring to Figure 4A and 4B The spiral membrane element of Example 1 was prepared by the method described in the description. It should be noted that #1000E manufactured by KB SEIREN was used as the permeation spacer, the first flow path material, and the second flow path material. As the supply spacer, 34mil manufactured by Tokyo Ink Co., Ltd. was used. In Example 1, the separation membrane unit was prepared by stacking two permeation spacers on the separation membrane. In the spiral membrane element of Example 1, the permeation space is connected to the external space through the outer peripheral surface of the element.

[0129] (Comparative Example 1)

[0130] The spiral membrane element of Comparative Example 1 was manufactured by the same method as Example 1, except that the permeate fluid was transported to the outside only through the central tube. In the spiral membrane element of Comparative Example 1, the permeate space was not connected to the external space through the outer peripheral surface of the element, which is the same as the structure of the conventional spiral membrane element.

[0131] [Evaluation of Flat Separation Membranes]

[0132] For the separation membrane used in the spiral membrane element, the permeation rate T1 (GPU) of carbon dioxide in the flat membrane state was measured. The permeation rate T1 was measured using a differential pressure gas permeability measuring device (GTR-31AHND manufactured by GTR TEC) by the following method. First, the separation membrane was placed in a metal chamber in a flat membrane state and sealed with an O-ring to prevent leakage. The membrane area of ​​the separation membrane was 3.14 cm 2 . Next, a supply fluid (carbon dioxide) is injected into the metal cell in such a way that the supply fluid contacts the main surface of the separation functional layer side of the separation membrane. The temperature of the supply fluid injected into the metal cell is 23°C and the pressure is 0.1 MPa. Next, a vacuum pump is used to reduce the pressure of the space adjacent to the main surface of the porous support side of the separation membrane to less than about 10 kPa. Thus, a permeable fluid is obtained from the main surface of the porous support side of the separation membrane. Based on the composition of the obtained permeable fluid, the weight of the permeable fluid, etc., the permeation rate T1 of carbon dioxide is calculated. It should be noted that the composition of the permeable fluid, etc. is measured using a gas chromatograph (G2700T manufactured by Yanako Technical Science).

[0133] [Evaluation of spiral membrane elements]

[0134] Next, the carbon dioxide permeation rate T2 (GPU) was measured when the spiral membrane element was operated by the reduced pressure method.

[0135] The permeation rate T2 is measured by the following method. First, supply fluid (carbon dioxide) is supplied to the supply fluid flow path of the spiral membrane element. The temperature of the supply fluid is 23°C and the pressure is 0.1 MPa. Next, use a vacuum pump to reduce the pressure in the center tube and the external space adjacent to the outer peripheral surface of the spiral membrane element to about 10 kPa or less. Thus, a permeable fluid is obtained. Based on the flow rate of the obtained permeable fluid, etc., the permeation rate T2 of carbon dioxide is calculated. It should be noted that the flow rate of the permeable fluid is measured using a soap film flowmeter (manufactured by HORIBA).

[0136] The ratio R of the transmission rate T2 to the transmission rate T1 was calculated. The results are shown in Table 1.

[0137] [Table 1]

[0138]

[0139] As can be seen from Table 1, the ratio R of the separation membrane element of Example 1 in which the permeation space is connected to the external space via the outer peripheral surface is higher than that of the comparative example. From this result, it can be seen that in the spiral membrane element of this embodiment, the decrease in the permeation rate of the permeated fluid from the separation membrane is suppressed, and it is suitable for efficiently recovering the permeated fluid.

[0140] Industrial Applicability

[0141] The spiral membrane element of this embodiment is suitable for separating acidic gas from a mixed gas containing acidic gas. In particular, the spiral membrane element of this embodiment is suitable for separating carbon dioxide from exhaust gas of chemical facilities and thermal power generation.

Claims

1. Spiral membrane element, which has: Central tube; a separation membrane wound around the central tube and separating a feed fluid into a permeated fluid and a non-permeated fluid; and The supply space and the permeate space separated by the separation membrane, in, The permeation space communicates with an external space of the spiral membrane element via an outer peripheral surface of the spiral membrane element.

2. Spiral membrane element, which has: Central tube; a separation membrane wound around the central tube and separating a feed fluid into a permeated fluid and a non-permeated fluid; and The supply space and the permeate space separated by the separation membrane, in, The permeated fluid is transported from the permeation space to an external space of the spiral membrane element through the outer peripheral surface of the spiral membrane element. 3 . The spiral membrane element according to claim 1 , further comprising a first flow path material constituting the outer peripheral surface and through which the permeated fluid can pass.

4. The spiral membrane element according to claim 3, further comprising a permeation spacer disposed in the permeation space, The permeable spacer is connected to the first flow path material. 5 . The spiral membrane element according to claim 4 , further comprising a second flow path material connected to the permeate spacer and wound around the center tube on the center tube side relative to the separation membrane.

6. The spiral membrane element according to claim 1 or 2, further comprising a supply spacer disposed in the supply space, The supply spacer is surrounded by the separation membrane folded into two parts.

7. The spiral membrane element according to claim 1 or 2, wherein: The central tube has an opening that allows the interior of the central tube to communicate with the exterior. The permeable space communicates with the interior of the central tube through the opening.

8. The spiral membrane element according to claim 7, wherein: A portion of the permeated fluid is transported from the permeation space to the external space through the outer peripheral surface, and the remaining permeated fluid is transported from the permeation space to the inside of the central tube through the opening. 9 . The spiral membrane element according to claim 1 , which is used for separating carbon dioxide from a mixed gas containing carbon dioxide and nitrogen.

10. A membrane separation device comprising: The spiral membrane element according to claim 1 or 2; and A housing for housing the spiral membrane element.

11. The membrane separation device according to claim 10, wherein: The housing has a permeated fluid outlet for discharging the permeated fluid transported from the permeation space through the outer peripheral surface of the spiral membrane element to the outside. 12 . The membrane separation device according to claim 10 , further comprising a first sealing portion disposed around the spiral membrane element, the first sealing portion preventing the feed fluid from flowing into a space between the outer peripheral surface of the spiral membrane element and the inner peripheral surface of the housing. 13 . The membrane separation device according to claim 10 , further comprising a second sealing portion disposed around the spiral membrane element, the second sealing portion preventing the non-permeated fluid from flowing into a space between the outer peripheral surface of the spiral membrane element and the inner peripheral surface of the housing.

Images