Laminated body of ion exchange membrane and gasket, ion dialysis tank, and gasket

Abstract

The utility model provides a laminated body of an ion exchange membrane and a gasket, an ion dialysis tank and the gasket. The laminated body can eliminate the problem that the efficiency of the laminated body as an ion dialysis tank is reduced. The gasket is provided with: a processing unit in which a space for ion exchange is formed in an ion exchange dialysis tank and a space for diffusion or dialysis is formed in a diffusion dialysis tank; and a gasket frame that surrounds the treatment unit, in which a flow distribution unit that connects the treatment unit and a communication hole formed in the ion exchange membrane is formed in the gasket frame, a spacer having a mesh structure is disposed in the treatment unit, and a flow distribution plate having a mesh structure is disposed in the flow distribution unit. The opening of the mesh structure constituting the flow distribution plate is formed smaller than the opening of the mesh structure constituting the spacer. The pitch of the openings constituting the mesh structure of the flow distribution plate in the liquid flow direction at the flow distribution part is formed to be longer than the pitch in the width direction orthogonal to the liquid flow direction at the flow distribution part.

Description

Technical Field

[0001] The utility model relates to a laminate of an ion exchange membrane and a gasket used in an ion dialysis cell as an ion exchange dialysis cell or a diffusion dialysis cell, an ion dialysis cell having the laminate of the ion exchange membrane and the gasket, and a gasket used in the laminate. Background Art

[0002] Ion dialysis cells are known that are composed of stacked sections of a laminated body comprising ion exchange membranes and gaskets. These ion dialysis cells include at least an ion exchange dialysis cell, in which ionic substances in a solution are desalinated, concentrated, purified, or recovered by electrodialysis through electrical interaction with the ion exchange membranes; and a diffusion dialysis cell, in which acid or alkali is recovered from waste liquid by utilizing the concentration difference between the liquids on both sides of the ion exchange membranes, rather than relying on electrical interaction.

[0003] Electrolyte solution desalination technology using ion exchange dialysis cells and electrodialysis was first developed in the 1950s for the desalination of brine. Since then, it has been used in a variety of fields, including seawater concentration for salt production, desalination of soy sauce and whey, streamlining various chemical manufacturing processes, wastewater treatment, and separation of impurities from wine.

[0004] A typical electrodialysis device using an ion exchange dialysis cell such as the one described above is known to utilize a stacked portion in which a plurality of ion exchange membranes (anion exchange membranes and cation exchange membranes) are stacked between a pair of electrodes, with the anion exchange membranes and cation exchange membranes alternately positioned between adjacent gaskets. Each gasket is formed with a processing portion sandwiched between the anion exchange membranes and the cation exchange membranes to function as an ion exchange chamber for ion exchange, and a gasket frame surrounding the processing portion. The gasket frame is formed with a flow distribution portion connecting the processing portion to a communication hole formed in the ion exchange membrane (see, for example, Patent Document 1).

[0005] As ion exchange dialysis cells capable of performing electrodialysis, in addition to the above-mentioned structure in which a plurality of anion exchange membranes, cation exchange membranes and gaskets are stacked to form a stacking portion for ion exchange, there are also known structures: a structure in which an ion exchange membrane (bipolar membrane) having a structure in which an anion exchange layer and a cation exchange layer are laminated together with the anion exchange membrane, cation exchange membrane and gasket to form a stacking portion for ion exchange; a structure in which the bipolar membrane is stacked together with an anion exchange membrane and a gasket to form a stacking portion for ion exchange; and a structure in which the bipolar membrane is stacked together with a cation exchange membrane and a gasket to form a stacking portion for ion exchange.

[0006] In addition, when using a diffusion dialysis cell to recover acid from waste liquid, an anion exchange membrane and a gasket are stacked to form a stacked portion, and when recovering alkali from waste liquid, a cation exchange membrane and a gasket are stacked to form a stacked portion. In a treatment unit having the same structure as the gasket of the ion exchange dialysis cell, a chamber for supplying waste liquid and water containing the acid or alkali is formed, and the waste liquid or water is supplied to the treatment unit. As a result, the acid or alkali contained in the waste liquid passes through the anion exchange membrane or cation exchange membrane toward the water side due to the concentration difference, thereby recovering the acid or alkali (for example, see Patent Document 2). Similar to the gasket used in the ion exchange dialysis cell, the gasket used in the diffusion dialysis cell also has a treatment unit that is sandwiched between the anion exchange membrane or cation exchange membrane and functions as a chamber for performing diffusion, etc., and a gasket frame surrounding the treatment unit. The gasket frame has a distribution unit that connects the treatment unit to the connecting hole formed in the ion exchange membrane (anion exchange membrane or cation exchange membrane).

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2014-14776

[0010] Patent Document 2: Japanese Patent Application Laid-Open No. 2016-221507 Utility Model Content

[0011] Problems to be solved by utility models

[0012] In any of the above-mentioned ion dialysis cells, there is provided one or more stacking sections formed by a stack of ion exchange membranes and gaskets, and a press machine is used to press the stacking section from the side to apply pressing force to maintain the stacking section, and a space of a processing section and a distribution section based on the gasket is formed to allow the liquid to be processed to flow and implement ion exchange, diffusion or dialysis.

[0013] In the treatment section and distribution section of the gasket clamped by the ion exchange membrane, a sheet-like component is provided to ensure space for the liquid to be treated to flow and be treated. The sheet-like component is composed of a resin sheet with a mesh structure, so that the raw liquid, acid, alkaline waste liquid, etc. to be the object of desalination treatment supplied to the treatment section can flow in the treatment section and distribution section.

[0014] Here, the thickness of the ion exchange membrane is typically thinner than that of the gasket. When a plurality of ion exchange membranes and gaskets are stacked to form a stacked portion, and a raw liquid, acid waste liquid, alkaline waste liquid, or the like to be subjected to desalination treatment is supplied to the above-mentioned treatment portion while maintaining the shape of the stacked portion by applying pressure using a press, the ion exchange membrane stacked on the gasket may sometimes be recessed toward the flow distribution portion formed on the gasket frame, creating a gap between the adjacent gaskets sandwiching the ion exchange membrane in the flow distribution portion. As a result, the flow distribution portion cannot be formed, and liquid flowing in the treatment portion of the adjacent gasket may leak between the gasket frame and the ion exchange membrane of the adjacent gasket, where liquid should not normally flow (hereinafter referred to as "internal leakage"). In the ion exchange dialysis cell, liquids from independent circulation systems (e.g., concentrate and desalted liquid) that would not otherwise mix mix, resulting in a problem of reduced efficiency of the ion dialysis cell.

[0015] Here, in order to avoid the above-mentioned ion exchange membrane from sinking, it is conceivable to provide a plate-like component (a sheet with a mesh structure) having sufficient thickness and strength in the distribution portion formed on the gasket frame. However, in this case, even if the internal leakage can be suppressed, the pressure loss of the liquid flowing in the distribution portion equipped with the plate-like component will also increase, thereby causing the problem of reduced efficiency as an ion dialysis cell. In addition, since the pressure loss of the distribution portion increases, liquid leakage will occur next to the distribution portion (the mating surface between the ion exchange membrane and the gasket frame). In the case of an electrodialysis cell, the following problem also arises: under the action of electricity (stray current) flowing in the portion where the liquid leakage occurs, the ion exchange membrane will burn out and deteriorate, resulting in irreversible damage.

[0016] The present invention is made in view of the above facts, and its main technical problem is to provide a stack of ion exchange membrane and gasket for use in an ion dialysis cell as an ion exchange dialysis cell or a diffusion dialysis cell. Specifically, it provides a stack of ion exchange membrane and gasket for use in an ion dialysis cell that can eliminate the problem that liquids in independent paths that would not originally mix (such as concentrated liquid and desalted liquid) are mixed due to the depression of the ion exchange membrane at the distribution part of the gasket frame, thereby reducing the efficiency of the ion dialysis cell, an ion dialysis cell having the stack of ion exchange membrane and gasket, and a gasket used in the stack.

[0017] Solutions for solving problems

[0018] In order to solve the above-mentioned main technical problems, according to the utility model, a stack of an ion exchange membrane and a gasket is provided, which is used in an ion dialysis cell as an ion exchange dialysis cell or a diffusion dialysis cell, wherein the gasket comprises: a processing part, which forms a space for ion exchange in the ion exchange dialysis cell and a space for diffusion or dialysis in the diffusion dialysis cell; and a gasket frame, which surrounds the processing part, and a distribution part connecting the processing part and the connecting hole formed in the ion exchange membrane is formed in the gasket frame, a spacer with a mesh structure is provided in the processing part, and a distribution plate with a mesh structure is provided in the distribution part, the opening of the mesh structure constituting the distribution plate is formed to be smaller than the opening of the mesh structure constituting the spacer, and the spacing of the openings of the mesh structure constituting the distribution plate in the liquid flow direction at the distribution part is formed to be longer than the spacing in the width direction orthogonal to the liquid flow direction at the distribution part.

[0019] Preferably, the boundary line between the processing section and the distribution section is set as an adjacent side, one end of the adjacent side is used as a starting point, and the angle of the strands constituting the mesh structure of the distribution plate relative to the adjacent side forms a hypotenuse. The end point of the hypotenuse when reaching the side of the distribution plate and the other end of the adjacent side form an opposite side. The distribution plate is formed to have a size that internally contains a right triangle formed by the adjacent side, the hypotenuse, and the opposite side, and the angle formed by the adjacent side and the strands is set so that the right triangle does not overlap with the connecting holes of the ion exchange membrane. In addition, the distribution plate is preferably a mesh cloth structure.

[0020] Furthermore, according to the present invention, there is provided an ion dialysis cell including a laminate of the ion exchange membrane and a gasket.

[0021] Furthermore, according to the present invention, a gasket is provided, which is stacked together with an ion exchange membrane in an ion dialysis cell serving as an ion exchange dialysis cell or a diffusion dialysis cell, wherein the gasket comprises: a processing portion, which forms a space for ion exchange in the ion exchange dialysis cell and a space for diffusion or dialysis in the diffusion dialysis cell; and a gasket frame, which surrounds the processing portion, and a distribution portion is formed in the gasket frame to connect the processing portion and a connecting hole formed in the ion exchange membrane stacked on the gasket, a spacer with a mesh structure is provided in the processing portion, and a distribution plate with a mesh structure is provided in the distribution portion, the opening of the mesh structure constituting the distribution plate is formed to be smaller than the opening of the mesh structure constituting the spacer, and the spacing of the openings of the mesh structure constituting the distribution plate in the liquid flow direction at the distribution portion is formed to be longer than the spacing in the width direction orthogonal to the liquid flow direction at the distribution portion.

[0022] Effect of utility model

[0023] The stack of ion exchange membrane and gasket of the present invention is used in an ion dialysis cell as an ion exchange dialysis cell or a diffusion dialysis cell, wherein the gasket comprises: a processing portion, which forms a space for ion exchange in the ion exchange dialysis cell and a space for diffusion or dialysis in the diffusion dialysis cell; and a gasket frame, which surrounds the processing portion, and a distribution portion is formed in the gasket frame to connect the processing portion and the connecting hole formed in the ion exchange membrane, a spacer with a mesh structure is provided in the processing portion, and a distribution plate with a mesh structure is provided in the distribution portion, and the opening of the mesh structure constituting the distribution plate is formed to be larger than the opening of the mesh structure constituting the spacer. The openings of the mesh structure of the component are small, and the spacing of the openings of the mesh structure constituting the distribution plate in the liquid flow direction at the distribution portion is formed to be longer than the spacing in the width direction orthogonal to the liquid flow direction at the distribution portion. Therefore, the wavy depressions formed along the distribution plate can be reduced, and the above-mentioned internal leakage can be reduced or eliminated. Moreover, by making the spacing of the openings of the mesh structure constituting the distribution plate in the liquid flow direction at the distribution portion longer than the spacing in the width direction orthogonal to the liquid flow direction at the distribution portion, the pressure loss at the distribution portion can be reduced, and the above-mentioned problems of internal leakage and increased pressure loss can be solved at the same time.

[0024] In addition, the ion dialysis cell of the present invention has a stack of the above-mentioned ion exchange membrane and gasket, thereby reducing the wavy depressions formed along the distribution plate, reducing or eliminating the above-mentioned internal leakage, and by making the spacing of the openings of the mesh structure constituting the distribution plate in the liquid flow direction at the distribution part longer than the spacing in the width direction orthogonal to the liquid flow direction at the distribution part, the pressure loss at the distribution part can be reduced, and the above-mentioned problems of internal leakage and increased pressure loss can be solved at the same time.

[0025] Furthermore, the gasket of the present invention is stacked together with an ion exchange membrane in an ion dialysis cell which is an ion exchange dialysis cell or a diffusion dialysis cell, wherein the gasket comprises: a processing portion which forms a space for ion exchange in the ion exchange dialysis cell and a space for diffusion or dialysis in the diffusion dialysis cell; and a gasket frame which surrounds the processing portion, wherein a distribution portion is formed in the gasket frame to connect the processing portion and a connecting hole formed in the ion exchange membrane stacked on the gasket, a spacer with a mesh structure is provided in the processing portion, and a distribution plate with a mesh structure is provided in the distribution portion, wherein the opening of the mesh structure constituting the distribution plate is formed to be smaller than the structure The openings of the mesh structure constituting the spacer are small, and the spacing of the openings of the mesh structure constituting the distribution plate in the direction of liquid flow at the distribution portion is formed to be longer than the spacing in the width direction perpendicular to the liquid flow direction at the distribution portion. Therefore, the wavy depressions formed along the distribution plate can be reduced, and the above-mentioned internal leakage can be reduced or eliminated. Moreover, by making the spacing of the openings of the mesh structure constituting the distribution plate in the direction of liquid flow at the distribution portion longer than the spacing in the width direction perpendicular to the liquid flow direction at the distribution portion, the pressure loss at the distribution portion can be reduced, and the above-mentioned problems of internal leakage and increased pressure loss can be solved at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic side view of an ion exchange dialysis cell constituting the electrodialysis device of this embodiment.

[0027] Figure 2 It contains the components Figure 1 An exploded perspective view of a unit of an ion exchange dialysis cell is shown, showing a gasket, an anion exchange membrane, a gasket and a cation exchange membrane, and a gasket stacked on the cation exchange membrane.

[0028] Figure 3(a) shows the Figure 2 FIG3(b) is a front view showing an enlarged portion of a region of the gasket where the flow distribution portion is formed, and FIG3(a) is a front view showing a further enlarged portion of the front view shown in FIG3(a).

[0029] Figure 4(a) shows that Figure 1 4( b ) is a cross-sectional view taken along line AA of FIG. 4( a ), and FIG. 4( c ) is a cross-sectional view taken along line BB of FIG. 4( a ).

[0030] Description of Reference Numerals

[0031] 1: ion exchange dialysis cell; 10a: anode chamber; 10b: cathode chamber; 12, 14: fastening plate; 20: spacer; 30: distribution plate; 31, 32: strands; A: anion exchange membrane; K: cation exchange membrane; G1, G2, G3~Gn: gaskets; G1a: processing unit; G1b: gasket frame; G1c: distribution unit; G1d: connecting hole; G2a: processing unit; G2b: gasket frame; G2c: distribution unit; G2d: connecting hole; N1, N2: electrode diaphragms. DETAILED DESCRIPTION

[0032] Hereinafter, embodiments of a stack of ion exchange membranes and gaskets used in an ion dialysis cell constructed according to the present invention, an ion dialysis cell comprising the stack of ion exchange membranes and gaskets, and a gasket used in the stack will be described in detail with reference to the accompanying drawings. Furthermore, the ion dialysis cell described below is an example of an ion exchange dialysis cell that desalinates and concentrates ionic substances in a solution through electrical interaction with the ion exchange membrane. However, the present invention is not limited to this embodiment and can also be applied to diffusion dialysis cells that recover acids or alkalis from wastewater by utilizing a concentration difference between liquids on both sides of an ion exchange membrane, rather than relying on electrical interaction.

[0033] Figure 1 This is a schematic side view of an ion exchange dialysis cell 1 constituting the electrodialysis device of this embodiment. For ease of explanation, the ion exchange dialysis cell 1 is shown in exploded form. The illustrated ion exchange dialysis cell 1 constitutes a so-called filter press type electrodialysis device. The ion exchange dialysis cell 1 is formed by stacking a plurality of ion exchange membranes and gaskets between an anode chamber 10a containing an anode plate and a cathode chamber 10b containing a cathode plate. More specifically, as shown in the figure, gaskets G1 and G2 are arranged in a stacked manner, with cation exchange membranes K and anion exchange membranes A as ion exchange membranes alternately arranged between these gaskets. As such cation exchange membranes K and anion exchange membranes A, known exchange membranes can be used. As shown in the figure, the gasket G1, anion exchange membrane A, gasket G2, and cation exchange membrane K, which are surrounded by dotted lines, are formed into a unit U, and a stack portion S is formed by stacking a plurality of these units U (e.g., 60 units). At both ends of the stack S and between the anode chamber 10a and the cathode chamber 10b, electrode separators N1 and N2 composed of ion exchange membranes are provided. Figure 1 The stacking portion S is held by a pair of fastening plates 12 and 14, and a pressing force is applied from a horizontal direction by a pressing device (not shown). Figure 1 This is a schematic side view of the ion exchange dialysis cell 1 , not showing all the components, and including flow paths for the raw solution, concentrate, and desalted solution, pumps, and other components not shown.

[0034] exist Figure 2 , a perspective view of the gasket G1, anion exchange membrane A, gasket G2, and cation exchange membrane K, which constitute the unit U of the ion exchange dialysis cell 1, and the gasket G1 stacked on the cation exchange membrane K, is shown. The gasket G1, which is sandwiched between the electrode diaphragm N1 composed of the ion exchange membrane and the anion exchange membrane A, includes a processing portion G1a for performing ion exchange and a gasket frame G1b surrounding the processing portion G1a. The gasket frame G1b has flow distribution portions G1c formed in four locations, one above and one below, connecting the processing portion G1a to the connecting holes of the ion exchange membrane stacked on the gasket G1, more specifically, the connecting holes Ab of the anion exchange membrane A. Furthermore, the gasket frame G1b also has connecting holes G1d, which are independent of the processing portion G1a and communicate with the connecting holes Aa of the anion exchange membrane A stacked on the gasket G1, formed in four locations, one above and one below.

[0035] The gasket G2, which is stacked on the gasket G1 with an anion exchange membrane A interposed therebetween and is sandwiched between the anion exchange membrane A and the cation exchange membrane K, comprises: a processing section G2a, which forms a space (desalination chamber) for generating a desalted solution from a raw solution through ion exchange; and a gasket frame G2b, which surrounds the processing section G2a. The gasket frame G2b has flow distribution sections G2c formed at a total of four locations, connecting the processing section G2a to the connecting holes Aa and Ka formed in the anion exchange membrane A and the cation exchange membrane K sandwiching the gasket G2. Furthermore, the gasket frame G2b has connecting holes G2d, which are independent of the processing section G2a and connect the connecting holes Ab and Kb formed in the anion exchange membrane A and the cation exchange membrane K sandwiching the gasket G2, also formed at a total of four locations, interposed therebetween. A gasket G1 identical to the gasket G1 is stacked on the gasket G2 with the cation exchange membrane K interposed therebetween. An anion exchange membrane A (not shown) similar to the anion exchange membrane A described above is also laminated on the gasket G1. Thus, the ion exchange dialysis cell 1 of this embodiment is formed by laminating a plurality of units U each comprising the gasket G1, the anion exchange membrane A, the gasket G2, and the cation exchange membrane K. Furthermore, the processing portion G1a of the gasket G1, sandwiched between the cation exchange membrane K and the anion exchange membrane A, forms a space (concentration chamber) for generating a concentrated solution through ion exchange.

[0036] like Figure 2 As shown, a mesh-structured spacer 20 is provided in the processing portion G1a of the gasket G1 and the processing portion G2a of the gasket G2, and a mesh-structured distribution plate 30 is provided in the distribution portion G1c of the gasket G1 and the distribution portion G2c of the gasket G2.

[0037] FIG3(a) shows an enlarged view of the gasket G2 in which the flow distribution portion G2c is formed. Figure 2As can be understood from Figure 3(a), the spacer 20 is formed throughout the entire area of the treatment section G2a. Rather than weaving strands of molten plastic resin, such as polyethylene or polyolefin, into filaments, the spacer 20 is formed using a single mesh sheet with a biaxial mesh structure. The provision of this spacer 20 allows the desalination chamber to be formed in the treatment section G2a without contact with the opposing anion exchange membrane A and cation exchange membrane K.

[0038] As can be understood from FIG3(a), the distribution plate 30 is sized to correspond to the widthwise dimension of the distribution section G2c indicated by arrows X1-X2, and is sized to extend from the boundary between the processing section G2a and the distribution section G2c to the communication holes Aa and Ka (indicated by dashed lines) of the anion exchange membrane A and cation exchange membrane K sandwiching the gasket G2. This plate is inserted to ensure a space between the anion exchange membrane A and cation exchange membrane K of the distribution section G2c sandwiching the gasket G2 for liquid flow in the direction indicated by arrows Y1-Y2. Similar to the spacer 20, the distribution plate 30 is formed from a single sheet of mesh structure, not from strands of woven molten plastic of a resin, such as a polyolefin such as polyethylene or polypropylene, but rather from a biaxial mesh structure formed from these strands.

[0039] Here, the electrodialysis device has a commercially practical size, that is, the area of the treatment section G2a (effective current-carrying area) is 50 to 14,000 cm 2 , more preferably 55 to 6000 cm 2 In this case, the width of the flow distribution section G2c indicated by the arrows X1-X2 is generally 0.5 to 10 cm, preferably 0.8 to 5 cm. The length of the flow distribution section G2c (the length from the boundary between the processing section G2a and the flow distribution section G2c to the communication hole Ka indicated by the dot-dash line) is generally 1.5 to 5.5 cm, preferably 1.7 to 5.0 cm.

[0040] Furthermore, the thickness of the spacers 20 and manifold 30 is set to correspond to the thickness of the gasket. Since the thickness of the spacers 20 and manifold 30 is determined by the thickness of the two strands used to form the mesh structure of the spacers 20 and manifold 30, the strands forming the mesh structure of the spacers 20 and manifold 30, provided in the gaskets G1 and G2 of this embodiment, are typically of the same thickness. The diameter of the strands forming the mesh structure of the spacers 20 and manifold 30 is typically 0.25 to 0.50 mm, more preferably 0.28 to 0.45 mm.

[0041] As shown in Figure 3(a), the openings of the mesh structure constituting the distribution plate 30 of this embodiment are smaller than the openings of the mesh structure constituting the spacer 20. Furthermore, the openings of the mesh structure constituting the distribution plate 30 are formed so that the spacing between them in the liquid flow direction of the distribution portion G2c, indicated by arrows Y1-Y2, is longer than the spacing between them in the width direction, indicated by arrows X1-X2, which is perpendicular to the liquid flow direction. This point will be described in more detail with reference to Figure 3(b) in addition to Figure 3(a).

[0042] Figure 3(b) shows an enlarged view of the area indicated by the dashed line R in the distribution plate 30 shown in Figure 3(a). In Figure 3(b), the direction indicated by arrows Y1-Y2 represents the flow direction of the liquid in the distribution section G2c, and the direction indicated by arrows X1-X2 represents the width direction of the distribution section G2c. As shown in Figure 3(b), the distribution plate 30 is a sheet having a mesh structure, formed by welding so that strands 31, 31 tilted to the left and strands 32, 32 tilted to the right intersect. Openings P1', P2', P3', and P4' are formed by points P1', P2', P3', and P4' inside the quadrilateral P1P2P3P4 formed by the intersection points P1, P2, P3, and P4 between strands 31 and 32. In this embodiment, in the illustrated openings P1', P2', P3', P4', the pitch P1', P3' (=a) in the liquid flow direction indicated by arrows Y1-Y2 is formed to be longer than the pitch P2', P4' (=b) in the width direction indicated by arrows X1-X2, which is perpendicular to the liquid flow direction. The effects of this formation will be described below.

[0043] The size of the opening formed by the manifold 30 can generally be described using the ratio of the area of the openings P1', P2', P3', P4' to the area of the quadrilateral P1, P2, P3, P4 formed by the intersection of the strands 31, 31 and the strands 32, 32 (opening ratio). In this embodiment, the spacer 20 is also formed of a mesh structure, and the opening ratio of the spacer 20 is calculated using the same method as described above. The preferred value of this opening ratio will be described later.

[0044] Regarding the flow of liquid when desalting or concentrating ionic substances in a solution using the ion exchange dialysis cell 1, see also Figure 4(a) to Figure 4(c) Provide explanation.

[0045] FIG4(a) is a diagram showing a region corresponding to the flow distribution portion G2c of the gasket G2 described based on FIG3(a). The gasket G2 is sandwiched and stacked between the anion exchange membrane A and the cation exchange membrane K. As shown in FIG4(b) and FIG4(c), the gasket G2 is stacked with the gasket G1 on the anion exchange membrane A side and with the gasket G1 on the cation exchange membrane K side. FIG4(b) is a cross-sectional view taken along line AA of FIG4(a), and FIG4(c) is a cross-sectional view taken along line BB of FIG4(a).

[0046] Arrow F1 shown in Figure 4(a) indicates the flow of desalted liquid from the processing portion G2a of gasket G2 via the flow distribution portion G2c toward the area where the connecting holes Aa of the anion exchange membrane A and the connecting holes Ka of the cation exchange membrane K are formed during electrodialysis in the ion exchange dialysis cell 1. The flow F1 of the desalted liquid represents the flow through the flow distribution portion G2c shown in Figures 4(b) and 4(c). In this embodiment, as can be understood from Figures 4(b) and 4(c), in the area of the anion exchange membrane A stacked on gasket G2 corresponding to the flow distribution portion G2c, the anion exchange membrane A is wavy and concave along the strands 31 of the flow distribution plate 30. This creates a gap M between the gasket G1 and the anion exchange membrane A, which are in contact with the anion exchange membrane A. Furthermore, for ease of explanation, the anion exchange membrane A shown in Figures 4(b) and 4(c) is depicted as being more concave than it actually is.

[0047] No flow distribution portion is formed in the region of the gasket frame G1b of the gasket G1 corresponding to the flow distribution portion G2c of the gasket G2. Without the aforementioned recess, liquid would not flow from the processing portion G1a of the gasket G1 to the communicating holes Aa of the anion exchange membrane A and the communicating holes Ka of the cation exchange membrane K. However, as described above, if a recess in the anion exchange membrane A is present in the region corresponding to the flow distribution portion G2c, creating a gap M, as indicated by arrow F2 in FIG4(a), liquid in the processing portion G1a (not shown) of the gasket G1 flows into the gap M, causing internal leakage W. If this internal leakage W reaches the region corresponding to the communicating holes Aa of the anion exchange membrane A and the communicating holes Ka of the cation exchange membrane K, it would mix with the desalted liquid flowing from the processing portion G2a of the gasket G2 via the flow distribution portion G2c, resulting in a reduction in the processing efficiency of the ion exchange dialysis cell 1.

[0048] In this embodiment, as described above, the openings P1', P2', P3', P4' of the mesh structure of the distribution plate 30 disposed in the distribution portion G2c are smaller than the openings of the mesh structure of the spacer 20. This reduces the wavy depressions formed along the strands 31 of the distribution plate 30, compared to a case where the openings P1', P2', P3', P4' of the mesh structure of the distribution plate 30 are the same size as the openings of the mesh structure of the spacer 20, and thus reduces or eliminates the internal leakage W.

[0049] Here, if the openings P1', P2', P3', P4' that constitute the mesh structure of the distribution plate 30 are reduced, the strands 31 and 32 of the distribution plate 30 will become obstructions, increasing pressure loss in the distribution section G2c and potentially causing liquid to leak outward from the distribution section G2c. Therefore, in this embodiment, the spacing a of the openings P1', P2', P3', P4' that constitute the mesh structure of the distribution plate 30 as described above is made longer in the direction of liquid flow in the distribution section G2c (the direction of arrows Y1-Y2) than in the width direction X1-X2, which is perpendicular to the direction Y1-Y2 of liquid flow in the distribution section G2c. Because flow F1 in the distribution section G2c flows along the strands 31 and 32, by making the spacing a between the openings P1', P2', P3', and P4' in the liquid flow direction (the direction of arrows Y1-Y2) in the distribution section G2c longer than the spacing b in the width direction X1-X2 perpendicular to the liquid flow direction Y1-Y2 in the distribution section G2c, flow F1 in the distribution section G2c can be smoothed, and pressure loss in the distribution section G2c can be reduced, compared to a case where the spacing a is shorter than the spacing b. Therefore, by using the stack of ion exchange membranes and gaskets disclosed in this embodiment, the ion dialysis cell including the stack of ion exchange membranes and gaskets, and the gasket, the aforementioned problems of internal leakage W and increased pressure loss can be simultaneously solved.

[0050] Furthermore, in the distribution plate 30, the boundary line between the processing portion G2a of the gasket G2 and the distribution portion G2c (the line connecting point Q1 and point Q2 in FIG4(a)) is set as the adjacent side Q1Q2, and one end Q2 of the adjacent side Q1Q2 is used as the starting point. The angle θ of the wire material 31 constituting the mesh structure of the distribution plate 30 relative to the adjacent side Q1Q2 forms a hypotenuse Q2Q3, and the end point Q3 when the hypotenuse Q2Q3 reaches the side on the opposite side of the distribution plate 30 and the other end Q1 of the adjacent side Q1Q2 form an opposite side Q3Q1. The distribution plate 30 is formed to have a size that internally includes a right triangle Q1Q2Q3 formed by the adjacent side Q1Q2, the hypotenuse Q2Q3 and the opposite side Q3Q1, and the angle θ formed by the adjacent side Q1Q2 and the strand is set so that the right triangle Q1Q2Q3 does not overlap with the connecting holes Aa and connecting holes ka of the anion exchange membrane A and the cation exchange membrane K stacked on the gasket G2.

[0051] Here, assuming that the anion exchange membrane A between gasket G1 and anion exchange membrane A is recessed toward the flow distribution portion G2c in the region corresponding to the flow distribution portion G2c, creating a gap M, internal leakage W could potentially occur from the processing portion G1a of gasket G1 in the region near the boundary line (the line connecting points Q1 and Q2 in FIG4(a) ), as shown in FIG4(b) , which shows the AA section of FIG4(a) . However, in this embodiment, the right triangle Q1Q2Q3 formed in the flow distribution plate 30 is designed not to overlap with the communication holes Aa and Ka. Therefore, even if such internal leakage W occurs, the internal leakage W flowing through the gap M at the angle θ along the strand 31 forming the flow distribution plate 30 can be confined within the right triangle Q1Q2Q3. As shown in FIG4(c) , which shows the BB section of FIG4(a) , internal leakage W does not occur in the gap M and does not reach the communication holes Aa and Ka.

[0052] That is, in addition to the effects obtained as described above by making the openings P1'P2'P3'P4' of the mesh structure constituting the distribution plate 30 smaller than the openings of the mesh structure constituting the spacer 20, and making the spacing a of the openings of the mesh structure constituting the distribution plate 30 in the liquid flow direction Y1-Y2 at the distribution portion G2c longer than the spacing b in the width direction X1-X2 orthogonal to the liquid flow direction Y1-Y2 at the distribution portion G2c, internal leakage W can be more reliably prevented.

[0053] Furthermore, as mentioned above, to prevent ion exchange membrane concavity, the openings P1', P2', P3', P4' in the mesh structure of the distribution plate 30 are preferably small. However, if the opening ratio of the distribution plate 30 is too small, the pressure loss in the distribution section tends to increase. In particular, if the ratio of the opening ratio of the distribution plate 30 to the opening ratio of the spacer 20 is less than 0.50, while ion exchange membrane concavity can be prevented, the pressure loss increases excessively, which is not preferred. Therefore, the ratio of the opening ratio of the distribution plate 30 to the opening ratio of the spacer 20 is preferably 0.50 to 0.99, more preferably 0.65 to 0.99, even more preferably 0.65 to 0.90, and most preferably 0.70 to 0.80. This prevents the ion exchange membrane from concaving toward the distribution plate 30 and prevents excessive pressure loss in the distribution section.

[0054] The opening ratio of the distribution plate 30 is usually 40 to 80%, more preferably 50 to 60%. As the value in this range, it is preferred to satisfy the technical characteristics of the ratio of the opening ratio of the distribution plate 30 to the opening ratio of the spacer 20.

[0055] Furthermore, as described above, the spacing a of the openings P1', P2', P3', and P4' in the direction of liquid flow at the distribution section G2c (the direction of the arrow Y1-Y2) is preferably formed longer than the spacing b in the width direction X1-X2, which is orthogonal to the liquid flow direction Y1-Y2 at the distribution section G2c. If the spacing a is shorter than the spacing b, the smoothness of the flow F1 in the distribution section G2c will be impaired, increasing the pressure loss at the distribution section G2c, which is not preferred. Therefore, the spacing a is preferably longer than the spacing b by at least 1.1 times, more preferably 1.1 to 2.2 times, more preferably 1.3 to 2.2 times, and particularly preferably 1.5 to 2.2 times. In addition, when the wire diameter of the strands forming the mesh structure is the general wire diameter, the spacing a is generally 0.25 to 0.50 mm, and more preferably 0.28 to 0.45 mm.

[0056] Furthermore, the distribution plate 30 is more preferably formed to have a size of a right triangle Q1Q2Q3 formed internally by the adjacent side Q1Q2, the hypotenuse Q2Q3 and the opposite side Q3Q1 as described above. If this size is achieved in a manner that satisfies the technical characteristics of the appropriate opening ratio and the length of the spacing a relative to the spacing b, the hypotenuse Q2Q3 is generally selected within the range of 45° to 70° for the angle θ of the strand 31 relative to the adjacent side Q1Q2, and more preferably within the range of 50° to 65° for the angle θ of the strand 31 relative to the adjacent side Q1Q2.

[0057] The present invention is not limited to the above-mentioned embodiments and can include various modified examples. In the above-mentioned embodiments, an example of applying a stack of an ion exchange membrane and a gasket constructed based on the present invention to an ion exchange dialysis cell capable of performing electrodialysis is shown. However, for example, the present invention can also be applied to a structure in which an ion exchange membrane (bipolar membrane) having a structure formed by laminating an anion exchange layer and a cation exchange layer is stacked together with the above-mentioned anion exchange membrane, cation exchange membrane and gasket to form a stacked portion for ion exchange; a structure in which the bipolar membrane is stacked together with an anion exchange membrane and a gasket to form a stacked portion for ion exchange; a structure in which the bipolar membrane is stacked together with a cation exchange membrane and a gasket to form a stacked portion for ion exchange; or an ion dialysis cell in which an ion exchange membrane and a gasket are stacked together to perform diffusion dialysis.

[0058] In addition, the communicating holes (Aa, Ab, Ka, Kb) of the ion exchange membrane (anion exchange membrane A, cation exchange membrane K) in the above-mentioned embodiment are respectively formed with 4 in total on the upper and lower sides, but the utility model is not limited to this, and can also be other numbers, and its size can also be set as needed. In addition, in the above-mentioned embodiment, the communicating holes Aa, Ab, Ka, Kb of the anion exchange membrane A and the cation exchange membrane K are roughly quadrilateral, but the utility model is not limited to this, and can also be circular. Even if the communicating holes Aa and Ka are circular, according to the utility model, the same effect as the above-mentioned embodiment can be achieved.

Claims

1. A laminate of an ion exchange membrane and a gasket, used in an ion dialysis cell as an ion exchange dialysis cell or a diffusion dialysis cell, characterized in that: The gasket includes: a processing portion forming a space for ion exchange in the ion exchange dialysis cell and a space for diffusion or dialysis in the diffusion dialysis cell; and a gasket frame surrounding the processing portion. The gasket frame is formed with a flow distribution portion that connects the processing portion and the communication hole formed in the ion exchange membrane. The processing part is provided with a spacer with a mesh structure, and the distribution part is provided with a distribution plate with a mesh structure. The openings of the mesh structure constituting the distribution plate are formed to be smaller than the openings of the mesh structure constituting the spacer, and the spacing of the openings of the mesh structure constituting the distribution plate in the liquid flow direction at the distribution part is formed to be longer than the spacing in the width direction orthogonal to the liquid flow direction at the distribution part.

2. The laminate of the ion exchange membrane and the gasket according to claim 1, wherein The boundary line between the processing part and the distribution part is set as an adjacent side, and one end of the adjacent side is used as a starting point. The angle of the strands constituting the mesh structure of the distribution plate relative to the adjacent side forms a hypotenuse, and the end point when the hypotenuse reaches the side of the distribution plate and the other end of the adjacent side form an opposite side. The distribution plate is formed to have a size that internally includes a right triangle formed by the adjacent side, the hypotenuse and the opposite side, and the angle formed by the adjacent side and the strands is set so that the right triangle does not overlap with the connecting hole of the ion exchange membrane.

3. The laminate of the ion exchange membrane and the gasket according to claim 1, wherein The distribution plate is a mesh cloth structure.

4. An ion dialysis cell, characterized in that: This ion dialysis cell comprises a laminate of the ion exchange membrane according to claim 1 and a gasket.

5. A gasket stacked together with an ion exchange membrane in an ion dialysis cell which is an ion exchange dialysis cell or a diffusion dialysis cell, characterized in that: The gasket includes: a processing portion forming a space for ion exchange in the ion exchange dialysis cell and a space for diffusion or dialysis in the diffusion dialysis cell; and a gasket frame surrounding the processing portion. The gasket frame is provided with a flow distribution portion that connects the processing portion and a communication hole formed in the ion exchange membrane stacked on the gasket. The processing part is provided with a spacer with a mesh structure, and the distribution part is provided with a distribution plate with a mesh structure. The openings of the mesh structure constituting the distribution plate are formed to be smaller than the openings of the mesh structure constituting the spacer, and the spacing of the openings of the mesh structure constituting the distribution plate in the liquid flow direction at the distribution part is formed to be longer than the spacing in the width direction orthogonal to the liquid flow direction at the distribution part.

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