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

Abstract

The invention provides a laminate of an ion exchange membrane and a gasket, an ion dialysis tank, and a 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 present invention relates to a laminate of an ion exchange membrane and a gasket used in an ion dialysis cell which is 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] An ion dialysis cell composed of a stacked portion of a laminated body having an ion exchange membrane and a gasket is known. The ion dialysis cell includes at least: an ion exchange dialysis cell in which ionic substances in a solution are desalted, concentrated, refined, recovered, etc. by electrical action with the ion exchange membrane and electrodialysis; and a diffusion dialysis cell in which acid or alkali is recovered from waste liquid by utilizing the concentration difference of liquid on both sides of the ion exchange membrane instead of electrical action.

[0003] The desalination technology of electrolyte solutions based on electrodialysis using ion exchange dialysis cells was first developed in the 1950s for the purpose of desalting salt water. Since then, it has been used in a variety of fields, such as seawater concentration for the purpose of salt production, desalination of soy sauce and whey, rationalization of various chemical manufacturing processes, wastewater treatment, and separation of impurities in wine.

[0004] As a typical electrodialysis device using an ion exchange dialysis cell as described above, it is known that the following stacking unit is used: a plurality of ion exchange membranes (anion exchange membranes, cation exchange membranes) and gaskets are stacked between a pair of electrodes, and the anion exchange membranes and cation exchange membranes are stacked in a manner that they are alternately located between gaskets adjacent to each other. A processing unit that functions as an ion exchange chamber for ion exchange and is sandwiched between the anion exchange membranes and the cation exchange membranes and a gasket frame surrounding the processing unit are formed on each gasket, and a distribution unit that connects the processing unit to a connecting hole formed on the ion exchange membrane is formed on the gasket frame (for example, refer to 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 stacked 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 bonded together and stacked in combination with the 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 in combination with an anion exchange membrane and a gasket to form a stacked portion for ion exchange; and a structure in which the bipolar membrane is stacked in combination with a cation exchange membrane and a gasket to form a stacked portion for ion exchange.

[0006] In addition, when using a diffusion dialysis tank to recover acid from waste liquid, an anion exchange membrane and a gasket are stacked to form a stacking portion, and when recovering alkali from waste liquid, a cation exchange membrane and a gasket are stacked to form a stacking portion. In a treatment portion having the same structure as the gasket of the above-mentioned ion exchange dialysis tank, a chamber for supplying waste liquid and water of acid or alkali is formed and the waste liquid or water is supplied to the treatment portion, so that the acid or alkali contained in the waste liquid moves to the water side through the anion exchange membrane or the cation exchange membrane under the action of the concentration difference, and the acid or alkali is recovered (for example, refer to patent document 2.). Similar to the gasket used in the above-mentioned ion exchange dialysis tank, the gasket used in the diffusion dialysis tank is also formed with a treatment portion that is clamped by the anion exchange membrane or the cation exchange membrane and functions as a chamber for diffusion, etc., and a gasket frame surrounding the treatment portion, and a distribution portion that connects the treatment portion and the connecting hole formed in the ion exchange membrane (anion exchange membrane or cation exchange membrane) is formed in the gasket frame.

[0007] Prior art literature

[0008] Patent Literature

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

[0010] Patent Document 2: Japanese Patent Application Publication No. 2016-221507 Summary of the invention

[0011] Problem that the invention aims to solve

[0012] In any of the above-mentioned ion dialysis cells, there is provided one or more stacking sections which are formed by a stack of ion exchange membranes and gaskets. A press machine is used to press the stacking section from the side to apply a 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 a liquid to be processed to flow, thereby implementing ion exchange, diffusion or dialysis.

[0013] In order to ensure space for the liquid to be treated to flow and be treated, a sheet-like component is provided in the treatment section and distribution section of the gasket clamped by the ion exchange membrane. 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, usually, the thickness of the ion exchange membrane is thinner than that of the gasket. When a plurality of ion exchange membranes and gaskets are stacked to form a stacking section, and the raw liquid, acid waste liquid, alkaline waste liquid, etc. to be the object of desalination treatment are supplied to the above-mentioned treatment section in a state where the stacking section is maintained by applying a pressing force using a press machine, sometimes the ion exchange membrane stacked on the gasket is recessed toward the distribution section formed on the gasket frame, and a gap is generated in the distribution section between the adjacent gasket sides relative to the ion exchange membrane. As a result, the distribution section cannot be formed, and the liquid flowing in the treatment section of the adjacent gasket will leak between the gasket frame and the ion exchange membrane of the adjacent gasket where the liquid should not flow (hereinafter referred to as "internal leakage"), and in the ion exchange dialysis tank, the liquids of the independent circulation systems (such as the concentrate and the desalted liquid) that would not be mixed originally are mixed, resulting in the problem of reduced efficiency as an ion dialysis tank.

[0015] Here, in order to avoid the above-mentioned depression of the ion exchange membrane, it is conceivable to provide a plate-like component (a sheet with a mesh structure) with sufficient thickness and firmness in the distribution part 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 part 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 part increases, liquid leakage will occur next to the distribution part (the mating surface of the ion exchange membrane and the gasket frame). In the case of an electrodialysis cell, the following problem also occurs: under the action of electricity (stray current) flowing in the part where the liquid leakage occurs, the ion exchange membrane burns out and deteriorates, causing irreversible damage.

[0016] The present invention is made in view of the above facts, and its main technical problem is to relate to a stack of ion exchange membranes and gaskets used in an ion dialysis cell as an ion exchange dialysis cell or a diffusion dialysis cell. Specifically, there are provided a stack of ion exchange membranes and gaskets used in an ion dialysis cell that can eliminate the problem of mixing of liquids in independent paths that would not originally mix (for example, concentrated liquid and desalted liquid) 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 membranes and gaskets, 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 present invention, 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 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 connecting the processing portion and a 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 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.

[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, 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, and the distribution plate is formed to contain the size of 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. 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 comprising a laminate of the above-mentioned 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 in which a distribution portion is formed that connects 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] Effects of the Invention

[0023] The stack of the ion exchange membrane and the 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 arranged in the processing portion, and a distribution plate with a mesh structure is arranged in the distribution portion, and the opening of the mesh structure constituting the distribution plate is formed larger than the opening of the mesh structure constituting the spacer. The openings of the mesh structure 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 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 direction of liquid flow 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 comprises a stack of the above-mentioned ion exchange membrane and a gasket, thereby being able to reduce the wavy depressions formed along the distribution plate, being able to reduce or eliminate 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 portion longer than the spacing in the width direction orthogonal to the liquid flow direction at the distribution portion, being able to reduce the pressure loss at the distribution portion, and being able to solve the above-mentioned problems of internal leakage and increased pressure loss 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 larger than the opening of the mesh structure constituting the distribution plate. The opening of the mesh structure of the spacer is 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 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 direction of liquid flow 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. 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 the present embodiment.

[0027] Figure 2 It contains components Figure 1 The ion exchange dialysis cell shown is an exploded perspective view of a unit 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 Figure 2 FIG3( b ) is a front view showing a part of the front view shown in FIG3( a ) in a further enlarged manner. FIG3( a ) is a front view showing a region of the gasket where the flow distribution portion is formed. FIG3( b ) is a front view showing a part of the front view shown in FIG3( a ) in a further enlarged manner.

[0029] Figure 4(a) shows that Figure 1 4( b ) is a schematic diagram of the flow of liquid and the state of internal leakage when electrodialysis is performed in the ion exchange dialysis cell shown in FIG. 4( a ), FIG. 4( c ) is a sectional view taken along line BB in 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: gasket; G1a: processing part; G1b: gasket frame; G1c: distribution part; G1d: connecting hole; G2a: processing part; G2b: gasket frame; G2c: distribution part; G2d: connecting hole; N1, N2: electrode diaphragm. DETAILED DESCRIPTION

[0032] Hereinafter, embodiments of a laminate of an ion exchange membrane and a gasket used in an ion dialysis cell constructed based on the present invention, an ion dialysis cell having the laminate of the ion exchange membrane and the gasket, and a gasket used in the laminate will be described in detail with reference to the accompanying drawings. In addition, the ion dialysis cell described below is an example of an ion exchange dialysis cell that desalinates and concentrates ionic substances in a solution by electrical action with an ion exchange membrane, but the present invention is not limited thereto and can also be applied to a diffusion dialysis cell that recovers acid or alkali from a waste liquid by utilizing the concentration difference of liquids on both sides of the ion exchange membrane without relying on electrical action.

[0033] Figure 1 It is a schematic side view of the ion exchange dialysis cell 1 constituting the electrodialysis device of the present embodiment, and for the convenience of explanation, it is a figure that decomposes and represents the ion exchange dialysis cell 1. The ion exchange dialysis cell 1 shown in the figure constitutes a so-called electrodialysis device of a filter press type. The ion exchange dialysis cell 1 is formed by stacking a plurality of ion exchange membranes and a stack of gaskets between the anode chamber 10a containing an anode plate and the cathode chamber 10b containing a cathode plate. More specifically, as shown in the figure, gaskets G1 and G2 are configured in a plurality of overlapping ways, and between these gaskets, cation exchange membranes K and anion exchange membranes A as ion exchange membranes are alternately provided. As such cation exchange membranes K and anion exchange membranes A, known exchange membranes can be used. As shown in the figure, gaskets G1, anion exchange membranes A, gaskets G2, and cation exchange membranes K surrounded by dotted lines are formed into a unit U, and a stacking portion S is formed by stacking a plurality of the units U (e.g., 60 units). At both ends of the stacked portion S and between the anode chamber 10a and the cathode chamber 10b, electrode separators N1 and N2 composed of ion exchange membranes are arranged. Figure 1 The stacked 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 pressure device (not shown) to hold the stacked portion S. Figure 1 This is a schematic side view of the ion exchange dialysis cell 1 , and not all structures are shown, and flow paths for the flow of the raw solution, the concentrated solution, and the desalted solution, pumps, and other structures not shown are appropriately omitted.

[0034] exist Figure 2 In the figure, a three-dimensional view of the gasket G1, anion exchange membrane A, gasket G2 and cation exchange membrane K constituting the unit U of the above-mentioned ion exchange dialysis cell 1, and the gasket G1 stacked on the cation exchange membrane K is shown. The gasket G1 clamped by the electrode diaphragm N1 composed of the above-mentioned ion exchange membrane and the anion exchange membrane A has a processing part G1a for ion exchange and a gasket frame G1b surrounding the processing part G1a. In the gasket frame G1b, the distribution part G1c connecting the processing part G1a and the connecting hole of the ion exchange membrane stacked on the gasket G1, more specifically, the connecting hole Ab of the anion exchange membrane A is formed at a total of 4 positions in the upper and lower parts. In addition, in the gasket frame G1b, the connecting hole G1d that is independent of the processing part G1a and connected to the connecting hole Aa of the anion exchange membrane A stacked on the gasket G1 is also formed at a total of 4 positions in the upper and lower parts.

[0035] The gasket G2, which is stacked on the above-mentioned gasket G1 through the anion exchange membrane A and is sandwiched by the anion exchange membrane A and the cation exchange membrane K, has: a processing part 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 part G2a. In the gasket frame G2b, a distribution part G2c connecting the processing part G2a with the connecting hole Aa and the connecting hole Ka formed in the anion exchange membrane A and the cation exchange membrane K sandwiching the gasket G2 is formed in a total of 4 places up and down. In addition, in the gasket frame G2b, a connecting hole G2d that is independent of the processing part G2a and connects the connecting hole Ab and the connecting hole Kb formed in the anion exchange membrane A and the cation exchange membrane K sandwiching the gasket G2 is also formed in a total of 4 places up and down. In the gasket G2, a gasket G1 identical to the gasket G1 is stacked through the cation exchange membrane K. The gasket G1 is also stacked with an anion exchange membrane A (not shown) that is the same as the anion exchange membrane A. In this way, the ion exchange dialysis cell 1 of the present embodiment is formed by stacking a plurality of units U including the gasket G1, the anion exchange membrane A, the gasket G2, and the cation exchange membrane K. In addition, 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 by ion exchange.

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

[0037] FIG3(a) shows an enlarged front view of the gasket G2 showing a region where the flow distribution portion G2c is formed. Figure 2As can be understood from FIG. 3( a ), the spacer 20 is formed in the entire region of the processing section G2a, and the spacer 20 is formed by not weaving a strand formed by forming a molten plastic of a resin, such as polyethylene, polyolefin, or the like, into a filament, but by using a sheet of a mesh structure having a biaxial mesh cloth structure. By providing the spacer 20, a desalination chamber can be formed in the processing section G2a without contacting the opposing anion exchange membrane A and cation exchange membrane K.

[0038] As can be understood from FIG. 3( a ), the flow distribution plate 30 is of a size corresponding to the dimension in the width direction of the flow distribution section G2c indicated by the arrows X1-X2, and is formed to be of a size from the boundary between the processing section G2a and the flow distribution section G2c to the communicating hole Aa and communicating hole Ka (indicated by a single dot-dash line) of the anion exchange membrane A and the cation exchange membrane K sandwiching the gasket G2, and is inserted to ensure a space for the liquid to flow in the flow direction indicated by the arrows Y1-Y2 between the anion exchange membrane A and the cation exchange membrane K of the flow distribution section G2c sandwiching the gasket G2. Similar to the spacer 20, the flow distribution plate 30 is also formed by a sheet of a mesh structure in which the strands are formed into a filamentary strand made of a molten plastic of a resin, such as polyethylene, polypropylene, etc., but are set as a two-axis mesh cloth structure.

[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 the case of, the width dimension of the distribution part G2c indicated by the arrow X1-X2 is generally 0.5 to 10 cm, preferably 0.8 to 5 cm. The length dimension of the distribution part G2c (the length from the boundary between the processing part G2a and the distribution part G2c to the connecting hole Ka indicated by the single-dot chain line) is generally 1.5 to 5.5 cm, preferably 1.7 to 5.0 cm.

[0040] In addition, the thickness of the spacer 20 and the manifold 30 is set corresponding to the thickness of the gasket. Since the thickness of the spacer 20 and the manifold 30 is determined by the thickness of the two strands when the spacer 20 and the manifold 30 are formed in a mesh structure, typically, the strands forming the spacer 20 arranged in the gaskets G1 and G2 of this embodiment and the strands forming the manifold 30 in a mesh structure have the same thickness. Here, the wire diameter of the strands forming the mesh structure of the spacer 20 and the manifold 30 is generally 0.25 to 0.50 mm, and more preferably 0.28 to 0.45 mm.

[0041] As shown in FIG3(a), the openings of the mesh structure constituting the flow distribution plate 30 of the present embodiment are formed to be smaller than the openings of the mesh structure constituting the spacer 20. In addition, the openings of the mesh structure constituting the flow distribution plate 30 are formed so that the spacing in the liquid flow direction of the flow distribution portion G2c indicated by the arrow Y1-Y2 is longer than the spacing in the width direction indicated by the arrow X1-X2 orthogonal to the liquid flow direction. Regarding this point, in addition to FIG3(a), FIG3(b) is also referred to for a more specific description.

[0042] In FIG3(b), the area of ​​the dotted line R in the distribution plate 30 shown in FIG3(a) is enlarged. In FIG3(b), the direction indicated by the arrow Y1-Y2 is the flow direction of the liquid in the distribution section G2c, and the direction indicated by the arrow X1-X2 is the width direction of the distribution section G2c. As shown in FIG3(b), the distribution plate 30 is a sheet having a mesh structure, which is formed by welding in such a way that the strands 31, 31 inclined to the left and the strands 32, 32 inclined to the right in the figure intersect. The openings P1', P2', P3', P4' are formed by the points P1', P2', P3', P4' inside the quadrilateral P1P2P3P4 formed by the intersection points P1, P2, P3, P4 between the strands 31 and the strands 32. In this embodiment, in the openings P1'P2'P3'P4' shown in the figure, the pitch P1'P3'(=a) in the liquid flow direction indicated by the arrow Y1-Y2 is formed to be longer than the pitch P2'P4'(=b) in the width direction indicated by the arrow X1-X2 orthogonal to the liquid flow direction. The effects achieved by such formation will be described later.

[0043] In addition, the size of the opening formed by the distribution plate 30 can usually be described by the ratio (opening ratio) of the area of ​​the opening P1'P2'P3'P4' to the area of ​​the quadrilateral P1P2P3P4 formed by the intersection of the strands 31, 31 and the strands 32, 32 shown in FIG3(b). In the present embodiment, the spacer 20 is also formed by a mesh structure, and the opening ratio of the spacer 20 is also calculated by the same method as described above. The preferred value of the opening ratio is also described later.

[0044] For the flow of liquid when desalting, concentrating, etc., ionic substances in a solution are carried out using the above-mentioned ion exchange dialysis cell 1, see also Figure 4(a) to Figure 4(c) Provide explanation.

[0045] Fig. 4(a) is a diagram showing a region corresponding to the flow distribution portion G2c of the gasket G2 described based on Fig. 3(a), the gasket G2 is sandwiched and stacked by the anion exchange membrane A and the cation exchange membrane K, and as shown in Fig. 4(b) and Fig. 4(c), the gasket G2 is stacked with the gasket G1 on the anion exchange membrane A side and the gasket G1 on the cation exchange membrane K side. In addition, Fig. 4(b) is a cross-sectional view taken along AA of Fig. 4(a), and Fig. 4(c) is a cross-sectional view taken along BB of Fig. 4(a).

[0046] Arrow F1 shown in FIG4 (a) indicates that when electrodialysis is implemented in the ion exchange dialysis tank 1, the desalted liquid flows from the processing part G2a of the gasket G2 via the distribution part G2c toward the area where the connecting hole Aa of the anion exchange membrane A and the connecting hole Ka of the cation exchange membrane K are formed, and the flow F1 of the desalted liquid indicates the flow through the distribution part G2c shown in FIG4 (b) and FIG4 (c). In this embodiment, it can be understood from FIG4 (b) and FIG4 (c) that in the area corresponding to the distribution part G2c of the anion exchange membrane A stacked on the gasket G2, the anion exchange membrane A is wavy and concave along the strand 31 of the distribution plate 30. Thus, a gap M is generated between the gasket G1 in contact with the anion exchange membrane A and the anion exchange membrane A. In addition, for the convenience of explanation, the anion exchange membrane A shown in FIG4 (b) and FIG4 (c) is recorded as being more concave than the actual one.

[0047] No flow distribution part is formed in the area of ​​the gasket frame G1b of the gasket G1 corresponding to the flow distribution part G2c of the gasket G2. If there is no such depression, the liquid will not flow from the processing part G1a of the gasket G1 to the connecting hole Aa of the anion exchange membrane A and the connecting hole Ka of the cation exchange membrane K. However, as described above, when there is a depression of the anion exchange membrane A in the area corresponding to the flow distribution part G2c and a gap M is generated, as shown by the arrow F2 of Figure 4 (a), the liquid in the processing part G1a (not shown) of the gasket G1 flows to the above gap M, resulting in internal leakage W. Assuming that the internal leakage W reaches the area corresponding to the connecting hole Aa of the anion exchange membrane A and the connecting hole Ka of the cation exchange membrane K, it will mix with the desalted liquid flowing from the processing part G2a of the gasket G2 via the flow distribution part G2c, resulting in a problem of reduced processing efficiency as the ion exchange dialysis cell 1.

[0048] Here, in the present embodiment, as described above, the openings P1'P2'P3'P4' of the mesh structure constituting the flow distribution plate 30 disposed in the flow distribution portion G2c are formed to be smaller than the openings of the mesh structure constituting the spacer 20. Thus, compared with the case where the openings P1'P2'P3'P4' of the mesh structure of the flow distribution plate 30 are set to be a mesh structure of the same size as the openings of the mesh structure of the spacer 20, the wavy depressions formed along the strands 31 of the flow distribution plate 30 can be reduced, and the internal leakage W can be reduced or eliminated.

[0049] Here, if the openings P1'P2'P3'P4' constituting the mesh structure of the distribution plate 30 are reduced, the strands 31 and 32 of the distribution plate 30 will become obstacles, the pressure loss at the distribution part G2c will increase, and there is a concern that the liquid will leak to the side of the distribution part G2c. Therefore, in this embodiment, the spacing a of the openings P1'P2'P3'P4' constituting the mesh structure of the distribution plate 30 as described above in the liquid flow direction (the direction of the arrow Y1-Y2) at the distribution part G2c is formed to be longer than the spacing b in the width direction X1-X2 orthogonal to the liquid flow direction Y1-Y2 at the distribution part G2c. Since the flow F1 at the distribution part G2c flows along the strands 31 and 32, by making the spacing a of the openings P1'P2'P3'P4' in the liquid flow direction (the direction of the arrow Y1-Y2) at the distribution part G2c longer than the spacing b in the width direction X1-X2 orthogonal to the liquid flow direction Y1-Y2 at the distribution part G2c, the flow F1 at the distribution part G2c can be smoother and the pressure loss at the distribution part G2c can be reduced, compared with the case where the spacing a is shorter than the spacing b. Therefore, by adopting the stack of ion exchange membranes and gaskets disclosed in this embodiment, the ion dialysis cell having the stack of ion exchange membranes and gaskets, and the gasket, the above-mentioned problems of internal leakage W and increased pressure loss can be solved at the same time.

[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 Figure 4(a)) is set as the adjacent side Q1Q2, and one end Q2 of the adjacent side Q1Q2 is used as the starting point. The wire material 31 constituting the mesh structure of the distribution plate 30 forms a hypotenuse Q2Q3 at an angle θ relative to the adjacent side Q1Q2, 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 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 is recessed toward the flow distribution portion G2c between the gasket G1 and the anion exchange membrane A in the region corresponding to the flow distribution portion G2c to generate a gap M, as shown in FIG4(b) showing the AA section of FIG4(a), an internal leakage W may be generated from the processing portion G1a of the gasket G1 in the vicinity of the boundary line (a line connecting the point Q1 and the point Q2 in FIG4(a)). However, since the right triangle Q1Q2Q3 formed in the flow distribution plate 30 in the present embodiment is set not to overlap with the communicating holes Aa and Ka, even if such an internal leakage W occurs, the internal leakage W flowing in the gap M of the angle θ along the strand 31 forming the flow distribution plate 30 can be retained in the right triangle Q1Q2Q3, and as shown in FIG4(c) showing the BB section of FIG4(a), no internal leakage W is generated in the gap M, and the internal leakage W does not reach the communicating holes Aa and Ka.

[0052] That is, in addition to the effect 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 part G2c longer than the spacing b in the width direction X1-X2 orthogonal to the liquid flow direction Y1-Y2 at the distribution part G2c, internal leakage W can be more reliably prevented.

[0053] In addition, as described above, in order to suppress the depression of the ion exchange membrane, the openings P1'P2'P3'P4' in the mesh structure of the distribution plate 30 are preferably smaller. However, if the opening ratio of the distribution plate 30 is too small, the pressure loss at the distribution portion will tend 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 lower than 0.50, although the depression of the ion exchange membrane can be suppressed, 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, further preferably 0.65 to 0.90, and most preferably 0.70 to 0.80. As a result, the ion exchange membrane can be suppressed from being depressed toward the distribution plate 30 side and the pressure loss at the distribution portion can be suppressed from being excessively increased.

[0054] The opening ratio of the distribution plate 30 is usually 40 to 80%, and more preferably selected within the range of 50 to 60%. As a value in this range, it is preferred to satisfy the technical feature 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'P4' in the direction of liquid flow at the distribution section G2c (the direction of the arrow Y1-Y2) is preferably formed to be longer than the spacing b in the width direction X1-X2 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 of the distribution section G2c will be impaired, and the pressure loss at the distribution section G2c will increase, which is not preferred. Therefore, the spacing a is preferably longer than the spacing b by more than 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 formed into a 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 the stack of ion exchange membranes and gaskets constructed based on the present invention to an ion exchange dialysis cell capable of performing electrodialysis is shown, but for example, it 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 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; 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; an ion dialysis cell in which an ion exchange membrane and a gasket are stacked 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 formed with 4 in total on the upper and lower sides, but the present invention is not limited to this, and can be other numbers, and its size can also be set as required. 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 present invention is not limited to this, and can be circular. Even if the communicating holes Aa and Ka are circular, according to the present invention, the same effect as the above-mentioned embodiment can be achieved.

Claims

1. A laminate of an ion exchange membrane and a gasket, which is used in an ion dialysis cell as an ion exchange dialysis cell or a diffusion dialysis cell, wherein: The gasket includes: a processing portion that 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 that surrounds 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 flow distribution part is provided with a flow 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 section and the distribution section is set as an adjacent side, and one end of the adjacent side is set as a starting point, so that 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, and 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, wherein: The ion dialysis cell comprises a laminate of the ion exchange membrane according to claim 1 and a gasket.

5. A gasket which 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 includes: a processing portion that 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 that surrounds the processing portion. The gasket frame includes 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 flow distribution part is provided with a flow 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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