Gasket and ion dialysis tank formed by laminating ion exchange membrane and gasket

Abstract

The utility model provides a gasket and an ion dialysis tank, wherein the gasket can restrain internal leakage and liquid leakage generated beside a flow distribution part and is laminated with an ion exchange membrane, and the ion dialysis tank comprises a laminated body formed by laminating the ion exchange membrane and the gasket. The gasket is provided with: a processing unit that forms a space for ion exchange in a fastening-type ion exchange dialysis tank and forms a space for diffusion or dialysis in a fastening-type diffusion dialysis tank; and a gasket frame surrounding the treatment unit, in which a flow distribution unit for connecting the treatment unit and a communication hole formed in the ion exchange membrane laminated on the gasket is formed in the gasket frame, a flow distribution plate having a mesh structure is disposed in the flow distribution unit, and the aperture ratio of the mesh structure constituting the flow distribution plate is 26-90%. The thickness of the flow distribution plate is made to be 103%-128% of the thickness of the gasket frame.

Description

TECHNICAL FIELD

[0001] The utility model relates to the gasket that is laminated with ion exchange membrane in the ion dialysis tank as the fastening type ion exchange dialysis tank or fastening type diffusion dialysis tank, and the ion dialysis tank formed by laminating ion exchange membrane and the gasket. BACKGROUND

[0002] There is known an ion dialysis tank composed of a stack portion provided with a laminate including an ion exchange membrane and a gasket. In the ion dialysis tank, at least: an ion exchange dialysis tank in which desalination, concentration, purification, recovery, etc. of ionic substances in a solution are performed by electrochemical action with an ion exchange membrane and by electrodialysis; and a diffusion dialysis tank in which acid or alkali is recovered from a waste liquid without relying on electrochemical action, but by utilizing a concentration difference of liquids sandwiching both sides of the ion exchange membrane.

[0003] Desalination technology of an electrolyte solution based on electrodialysis using an ion exchange dialysis tank is a technology originally developed in the 1950s for the purpose of desalination of salt water, and thereafter, is used in various fields such as seawater concentration for the purpose of manufacturing of table salt, desalination of soy sauce, whey, rationalization of various chemical manufacturing processes, wastewater treatment, separation of impurities in wine, etc.

[0004] As a typical electrodialysis device using the above-described ion exchange dialysis tank, there is known a fastening type ion exchange dialysis tank in which a stack portion is used, which stacks a plurality of ion exchange membranes (anion exchange membranes, cation exchange membranes) and gaskets between a pair of electrodes, stacks the anion exchange membranes and the cation exchange membranes alternately between the gaskets adjacent to each other, and forms by pressing these laminates from both ends in the stacking direction. Each gasket is formed with a treatment portion which is sandwiched by the anion exchange membrane and the cation exchange membrane to function as an ion exchange chamber in which ion exchange is performed, and a gasket frame which surrounds the treatment portion, and a flow distribution portion which connects the treatment portion and a communication hole formed in the ion exchange membrane is formed in the gasket frame (for example, refer to Patent Literature 1).

[0005] As a fastening-type ion exchange dialysis cell capable of performing electrodialysis, in addition to the above-described structure in which a plurality of anion exchange membranes, cation exchange membranes, and gaskets are stacked to form a stack portion to perform ion exchange, there are known structures in which an ion exchange membrane (bipolar membrane) having a structure in which an anion exchange layer and a cation exchange layer are bonded is combined with the anion exchange membrane, the cation exchange membrane, and the gasket to form a stack portion to perform ion exchange; a structure in which the bipolar membrane is combined with the anion exchange membrane and the gasket to form a stack portion to perform ion exchange; and a structure in which the bipolar membrane is combined with the cation exchange membrane and the gasket to form a stack portion to perform ion exchange.

[0006] In addition, in a case where an acid is recovered from a waste liquid using a fastening-type diffusion dialysis cell in which a stack portion is formed by pressing a stack from both ends thereof in the stacking direction, a stack portion is formed by stacking an anion exchange membrane and a gasket, in a case where an alkali is recovered from a waste liquid, a stack portion is formed by stacking a cation exchange membrane and a gasket, and in a treatment portion having the same structure as the gasket of the above-described fastening-type ion exchange dialysis cell, a chamber for supplying a waste liquid and water of an acid or an alkali is constituted, and the waste liquid or water is supplied to the treatment portion, whereby the acid or the 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 a concentration difference, and the acid or the alkali is recovered (for example, see Patent Literature 2). As with the gasket used in the above-described fastening-type ion exchange dialysis cell, in the gasket used in the fastening-type diffusion dialysis cell, a treatment portion in which an anion exchange membrane or a cation exchange membrane is sandwiched to function as a chamber in which diffusion or the like is performed, and a gasket frame surrounding the treatment portion are formed, and a flow distribution portion connecting the treatment portion and a communication hole formed in the ion exchange membrane (anion exchange membrane or cation exchange membrane) is formed in the gasket frame.

[0007] Prior Art Documents

[0008] Patent Literature

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

[0010] Patent Literature 2: Japanese Patent Application Laid-Open No. 2016-221507 Summary of Invention

[0011] Problem to be Solved by the Invention

[0012] In any of the above-described fastening-type ion exchange dialysis cells, one or more stack portions in which a stack of an ion exchange membrane and a gasket is formed are provided, a pressing force is applied to the stack portion by a press machine that presses the stack portion from the side, the stack portion is held, and a space of a treatment portion and a flow distribution portion based on the gasket is formed, a liquid that is a treatment target is caused to flow, and ion exchange, diffusion, or dialysis is performed.

[0013] In the treatment section and the flow distribution section of the gasket sandwiched by the ion exchange membrane, a sheet-shaped member is provided in order to secure a space in which a liquid to be treated flows and is treated. The sheet-shaped member is composed of a mesh structure sheet so that a raw liquid, an acid, an alkali waste liquid, and the like, which are supplied to the treatment section to be subjected to desalination treatment, flow in the treatment section and the flow distribution section.

[0014] Here, generally, the thickness of the ion exchange membrane is thinner than that of the gasket, and in a case where a raw liquid, an acid waste liquid, an alkali waste liquid, and the like, which are to be subjected to desalination treatment, are supplied to the above treatment section in a state in which a stack section is formed by stacking a plurality of ion exchange membranes and gaskets and in which the shape of the stack section is maintained by applying a pressing force using a press, the ion exchange membrane stacked on the gasket is sometimes recessed toward the flow distribution section formed in the gasket frame, and a gap is generated between the opposite gaskets sandwiching the ion exchange membrane in the flow distribution section. As a result, the flow distribution section is not formed, and a liquid flowing in the treatment section of the adjacent gasket leaks out between the gasket frame and the ion exchange membrane, which are normally not supposed to flow with a liquid (hereinafter referred to as "internal leakage"). In a fastening-type ion exchange dialysis cell, liquids of independent circulation systems (for example, a concentrated liquid and a desalinated liquid) that are not supposed to be mixed are mixed, and a problem of a decrease in efficiency as an ion dialysis cell occurs.

[0015] In addition, in order to avoid the recess of the ion exchange membrane that causes the above internal leakage, it is conceivable to provide a mesh structure sheet having a small opening ratio and a sufficient thickness with respect to the gasket in the flow distribution section formed in the gasket frame. However, in this case, even though the internal leakage can be suppressed, insufficient sealing between the ion exchange membrane and the gasket in the vicinity of the flow distribution section occurs, and liquid leakage occurs in the vicinity of the flow distribution section (a mating surface of the ion exchange membrane and the gasket). In the case of an electrodialysis cell, the ion exchange membrane is deteriorated and irreversibly damaged due to the effect of electricity (stray current) flowing in the portion where the liquid leaks, and the like.

[0016] To prevent the above-mentioned internal leakage, liquid leakage generated beside the flow distribution portion, the thickness of a sheet (hereinafter referred to as "flow distribution plate") of mesh structure provided in the flow distribution portion needs to be properly managed. In this regard, for the flow distribution plate, a scrim structure or a woven fabric structure of strands formed by forming molten plastic of resin, such as polyethylene, polypropylene, or the like, into a filament is adopted, and the thickness of the flow distribution plate is defined by the thickness of the intersection portion of two strands, i.e., the diameter x 2 of the two strands. In the case where such a flow distribution plate is provided in the flow distribution portion of the gasket and the ion exchange membrane and the gasket are stacked, although the flow distribution plate formed at the overlapping position in the stacking direction is stacked together with the gasket frame and the ion exchange membrane when viewed in the stacking direction, the intersection portion of the strands defining the thickness of the above-mentioned flow distribution plate does not necessarily coincide with each other in the adjacent two flow distribution plates, in which case, the effect of preventing the above-mentioned internal leakage, liquid leakage generated beside the flow distribution portion cannot be sufficiently exerted. That is, since the gasket frame is also formed of a soft resin material as will be described later, if the gasket frame and the ion exchange membrane located between the above-mentioned adjacent two flow distribution plates are not sandwiched from both sides at the intersection portion of each flow distribution plate, the support thereof becomes uneven, and in the gap portion of the mesh structure constituting the flow distribution plate on one side, the pressing from the intersection portion of the flow distribution plate on the other side is applied to the ion exchange membrane via the elastic force of the gasket frame, and local depression thereof is generated. Furthermore, when the number of layers of the stack is increased, the depression is significantly increased, thereby causing the above-mentioned internal leakage and the like. In this background, how to set the thickness of the flow distribution plate provided in the flow distribution portion and the opening ratio of the mesh structure constituting the same to eliminate the above-mentioned internal leakage, liquid leakage generated beside the flow distribution portion has not been sufficiently studied.

[0017] The present utility model is made in view of the above fact, and the main technical problem thereof is to provide a gasket capable of suppressing the above-mentioned internal leakage, liquid leakage generated beside the flow distribution portion, which is stacked together with an ion exchange membrane, and an ion dialysis tank comprising a stack of the ion exchange membrane and the gasket.

[0018] Solution to the problem

[0019] To solve the above-mentioned main technical problems, according to the utility model, provide a gasket, it is together with ion exchange membrane in the ion dialysis cell of fastening type ion exchange dialysis cell or fastening type diffusion dialysis cell as laminated, its characterized in being, the gasket has: processing portion, it forms the space of ion exchange in fastening type ion exchange dialysis cell, and it forms the space of diffusion or dialysis in fastening type diffusion dialysis cell, and gasket frame, it surrounds the processing portion, the flow distribution portion that the processing portion and the communication hole formed in the ion exchange membrane laminated in the gasket are connected is formed in the gasket frame, the flow distribution plate of mesh structure is equipped in the flow distribution portion, the opening rate of mesh structure that constitutes the flow distribution plate is formed 26%~90%, and the thickness of the flow distribution plate is formed the thickness of 103%~128% of the thickness of gasket frame.

[0020] To solve the above-mentioned main technical problems, provide a kind of ion dialysis cell, it is characterized in that, the ion dialysis cell includes the laminated body of more than one ion exchange membrane and above-mentioned gasket, the laminated number of the gasket of the flow distribution plate is laminated at the same position in the laminated direction of ion exchange membrane and gasket 30 or more.

[0021] Effect of the utility model

[0022] The gasket of the utility model is together with ion exchange membrane laminated in the ion dialysis cell of fastening type ion exchange dialysis cell or fastening type diffusion dialysis cell, wherein, the gasket has: processing portion, it forms the space of ion exchange in fastening type ion exchange dialysis cell, and it forms the space of diffusion or dialysis in fastening type diffusion dialysis cell, and gasket frame, it surrounds the processing portion, the flow distribution portion that the processing portion and the communication hole formed in the ion exchange membrane laminated in the gasket are connected is formed in the gasket frame, the flow distribution plate of mesh structure is equipped in the flow distribution portion, the opening rate of mesh structure that constitutes the flow distribution plate is formed 26%~90%, and the thickness of the flow distribution plate is formed the thickness of 103%~128% of the thickness of gasket frame, therefore, can prevent the liquid flowing in the processing portion of adjacent gasket and the like from leaking out between the gasket frame and ion exchange membrane of the gasket that liquid should not normally flow to adjacent gasket, can eliminate the problem that the liquid (for example, concentrated liquid and desalination liquid) of independent circulation system that should not be mixed mixes, thereby causing the efficiency reduction of ion dialysis cell, and can eliminate the following problems: in the case that liquid leakage occurs at the side of flow distribution portion (the matching surface of ion exchange membrane and gasket), the ion exchange membrane is deteriorated by burning under the action of electricity (stray current) flowing at the part where liquid leakage occurs, and irreversible damage occurs.

[0023] Furthermore, the ion dialysis tank of this invention comprises a laminate formed by stacking one or more ion exchange membranes and the aforementioned gaskets. The number of gaskets stacked at the same position in the stacking direction of the ion exchange membranes and gaskets is 30 or more. Therefore, in the ion dialysis tank, internal leakage can be prevented, such as liquid flowing in the processing section of adjacent gaskets leaking into the space between the gasket frame and the ion exchange membrane where liquid should not normally flow. This eliminates the problem of liquids (e.g., concentrate and desalination solution) from independent circulation systems that would not normally mix, thus reducing the efficiency of the ion dialysis tank. It also eliminates the following problem: when liquid leakage occurs next to the distribution section (at the mating surface of the ion exchange membrane and the gasket) in the case of an electrodialysis tank, the ion exchange membrane burns and deteriorates under the action of electricity (stray current) flowing at the part where liquid leakage occurs, resulting in irreversible damage. Attached Figure Description

[0024] Figure 1 This is a schematic side view of the compacted ion exchange dialysis cell that constitutes the electrodialysis apparatus of this embodiment.

[0025] Figure 2 It includes the constituent parts Figure 1 An exploded perspective view of the unit of the solidified ion exchange dialysis cell shown, including the gasket, anion exchange membrane, gasket and cation exchange membrane, and the gasket stacked on the cation exchange membrane.

[0026] Figure 3(a) shows the... Figure 2 The front view shown is an enlarged view of the area where the gasket with the distribution section is formed. Figure 3(b) is a further enlarged front view of a portion of the front view shown in Figure 3(a).

[0027] Explanation of reference numerals in the attached figures

[0028] 1. Fastened ion exchange dialysis cell; 10a. Anode chamber; 10b. Cathode chamber; 12, 14. Fastening plates; 20. Spacer; 30. Flow distribution plate; 31, 32. Wires; A. Anion exchange membrane; K. Cation exchange membrane; G1, G2. Gaskets; G1a. Treatment section; G1b. Gasket frame; G1c. Flow distribution section; G1d. Connecting hole; G2a. Treatment section; G2b. Gasket frame; G2c. Flow distribution section; G2d. Connecting hole; N1, N2. Electrode diaphragms. Detailed Implementation

[0029] Hereinafter, with reference to the accompanying drawings, embodiments of the gasket constructed based on the present invention, which is stacked together with the ion exchange membrane, and the ion dialysis cell comprising the stacked body formed by stacking the ion exchange membrane and the gasket are described in detail.

[0030] Hereinafter, referring to the drawings and explaining in detail the embodiments of the gasket laminated with the ion exchange membrane in the ion dialysis cell constituted as a fastening type ion exchange dialysis cell or a fastening type diffusion dialysis cell based on the present application, the ion dialysis cell including the laminated body of one or more ion exchange membranes and the gasket described above. Further, the ion dialysis cell described below is an example of the fastening type ion exchange dialysis cell that performs desalination, concentration, or the like of ionic substances in a solution by electrochemical action with the ion exchange membrane, but the present application is not limited thereto and can also be applied to the fastening type diffusion dialysis cell that recovers an acid or a base from a waste liquid without relying on electrochemical action but by utilizing a concentration difference of the liquid sandwiched between both sides of the ion exchange membrane.

[0031] Figure 1 is a schematic side view of the fastening type ion exchange dialysis cell 1 of the present embodiment, and is a view that shows the fastening type ion exchange dialysis cell 1 in an exploded manner for convenience of explanation. The illustrated fastening type ion exchange dialysis cell 1 constitutes a so-called filter-press type electrodialysis device. This fastening type ion exchange dialysis cell 1 is formed by laminating a plurality of laminated bodies of ion exchange membranes and gaskets between an anode chamber 10a including an anode plate and a cathode chamber 10b including a cathode plate. More specifically, as illustrated, gaskets G1, G2 are arranged in a manner of overlapping a plurality of times, and between these gaskets, a cation exchange membrane K and an anion exchange membrane A as ion exchange membranes are alternately arranged. As such a cation exchange membrane K and an anion exchange membrane A, a publicly known exchange membrane can be used. As illustrated, the gasket G1, the anion exchange membrane A, the gasket G2, and the cation exchange membrane K surrounded by a broken line are formed as one unit U, and by laminating a plurality of the units U (not illustrated) in a manner of stacking them, one stack S is formed. At both ends of the stack S and between the anode chamber 10a and the cathode chamber 10b, electrode separators N1, N2 composed of ion exchange membranes are arranged. The stack S is sandwiched by a pair of fastening plates 12, 14 as illustrated, and by a pressurizing device (not illustrated) that applies a pressing force from the horizontal direction, the stack S is held. Further, the fastening type ion exchange dialysis cell 1 is provided with a pair of electrodes 20, 30 that are arranged to face each other via the stack S, and a power supply 40 that applies a voltage between the electrodes 20, 30. Figure 1 is omitted) to form one stack S. At both ends of the stack S and between the anode chamber 10a and the cathode chamber 10b, electrode separators N1, N2 composed of ion exchange membranes are arranged. The stack S is sandwiched by a pair of fastening plates 12, 14 as illustrated, and by a pressurizing device (not illustrated) that applies a pressing force from the horizontal direction, the stack S is held. Further, the fastening type ion exchange dialysis cell 1 is provided with a pair of electrodes 20, 30 that are arranged to face each other via the stack S, and a power supply 40 that applies a voltage between the electrodes 20, 30. Figure 1 is omitted) to form one stack S. At both ends of the stack S and between the anode chamber 10a and the cathode chamber 10b, electrode separators N1, N2 composed of ion exchange membranes are arranged. The stack S is sandwiched by a pair of fastening plates 12, 14 as illustrated, and by a pressurizing device (not illustrated) that applies a pressing force from the horizontal direction, the stack S is held. Further, the fastening type ion exchange dialysis cell 1 is provided with a pair of electrodes 20, 30 that are arranged to face each other via the stack S, and a power supply 40 that applies a voltage between the electrodes 20, 30. Figure 1 is a schematic side view of the fastening type ion exchange dialysis cell 1, and does not show the entire structure, and the structure including flow paths through which raw liquid, concentrated liquid, and desalinated liquid flow, pumps, and other structures not illustrated are appropriately omitted.

[0032] In Figure 2 , a perspective view of the gasket G1, the anion exchange membrane A, the gasket G2, and the cation exchange membrane K that constitute one unit U of the fastening type ion exchange dialysis cell 1 is shown. The same unit U is also laminated in front and behind the illustrated unit U, and Figure 2The diagram also shows a gasket G1 of an adjacent unit U, stacked with the cation exchange membrane K of unit U. The gasket G1, held between the cation exchange membrane K (or an electrode diaphragm N1 composed of an ion exchange membrane) and the anion exchange membrane A, has a processing section G1a for ion exchange and a gasket frame G1b surrounding the processing section G1a. In the gasket frame G1b, a distribution section G1c is formed at four locations in total, connecting the processing section G1a to the communication holes of the ion exchange membrane stacked on the gasket G1, and more specifically, the communication holes Ab of the anion exchange membrane A stacked on the gasket G1. Additionally, in the gasket frame G1b, a communication hole G1d is also formed at four locations in total, independent of the processing section G1a and communicating with the communication holes Aa of the anion exchange membrane A stacked on the gasket G1.

[0033] The gasket G2, which is stacked on top of the gasket G1 and sandwiched between the anion exchange membrane A and the cation exchange membrane K, includes: a processing section G2a, which forms a space (desalination chamber) for generating a desalinated solution from the feed solution through ion exchange; and a gasket frame G2b surrounding the processing section G2a. In the gasket frame G2b, a distribution section G2c is formed at a total of four locations, vertically and horizontally, 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. Additionally, in the gasket frame G2b, a connecting hole G2d, independent of the processing section G2a and connecting to the connecting holes Ab and Kb formed in the anion exchange membrane A and the cation exchange membrane K sandwiching the gasket G2, is also formed at a total of four locations, vertically and horizontally. In the gasket G2, a gasket G1, with the same adjacent unit U as the gasket G1, is stacked on top of the cation exchange membrane K. Thus, the compact ion exchange dialysis tank 1 of this embodiment is formed by stacking multiple units U, each containing a gasket G1, an anion exchange membrane A, a gasket G2, and a cation exchange membrane K. Furthermore, the processing section G1a of the gasket G1, which is held between the cation exchange membrane K and the anion exchange membrane A, forms a space (concentration chamber) for generating a concentrate through ion exchange.

[0034] like Figure 2 As shown, mesh-structured spacers 20 are provided in the processing section G1a of gasket G1 and the processing section G2a of gasket G2, and mesh-structured distribution plates 30 are provided in the distribution section G1c of gasket G1 and the distribution section G2c of gasket G2. That is, the mesh-structured distribution plates 30 provided in the distribution section G1c of gasket G1 and the distribution section G2c of gasket G2 are stacked at the same position in the stacking direction of unit U, with the number of units U.

[0035] In Figure 3(a), an enlarged view shows the area in the front view of the gasket G1 where the flow distribution section G1c is formed. According to... Figure 2As can be understood from Figure 3(a), the spacer 20 is formed throughout the entire area of ​​the processing section G1a. It is a sheet with a mesh structure, where the strands are formed from molten resin (e.g., polyethylene, polypropylene, etc.) into filaments, rather than woven into threads. This spacer 20 allows for the formation of a concentration chamber in the processing section G1a without contact between opposing ion exchange membranes.

[0036] As can be understood from Figure 3(a), the distribution plate 30 is sized to correspond to the width of the distribution section G1c indicated by arrows X1-X2, and is formed such that the size from the junction of the processing section G1a and the distribution section G1c to the connecting holes Kb and Ab (indicated by single-dotted lines) of the cation exchange membrane K and anion exchange membrane A sandwiching the gasket G1 is inserted to ensure space between the cation exchange membrane K and anion exchange membrane A of the distribution section G1c sandwiching the gasket G1, allowing the liquid to flow in the flow direction indicated by arrows Y1-Y2. Similar to the spacer 20, the distribution plate 30 is also formed from a sheet with a mesh structure, not by weaving strands of molten resin, such as polyethylene or polypropylene, into filaments, but by setting these strands as a biaxial mesh fabric structure.

[0037] Here, the commercially viable size of the electrodialysis apparatus, i.e., the area (effective energized area) of the treatment section G1a, is 50–14000 cm². 2 More preferably 55-6000cm 2 In this case, the width dimension of the distribution section G1c indicated by arrows X1-X2 is generally 0.5 to 10 cm, preferably 0.8 to 5 cm. The length dimension of the distribution section G1c (the length from the junction between the processing section G1a and the distribution section G1c to the connecting holes Ab and Kb indicated by the single-dot dashed lines) is generally 1.5 to 5.5 cm, preferably 1.7 to 5.0 cm. Furthermore, the material of the gasket frame is not particularly limited, but soft resin materials can generally be used, and in particular, soft resins with a hardness (JIS A) of about 60 to 90 degrees are preferred. Specifically, thermoplastic resins such as polyolefins and polyvinyl chloride, or rubbers such as styrene-butadiene rubber and ethylene-propylene rubber, as well as thermoplastic elastomers made from a mixture of thermoplastic resins and rubbers can be used. Moreover, the thickness of the gasket frame is generally 0.4 to 1.0 mm, and 0.5 to 1.0 mm is preferred when used in an electrodialysis device.

[0038] Here, the applicant arranges the aforementioned distribution plate 30 in the distribution sections G1c and G2c to form gaskets G1 and G2, so that gasket G1, the aforementioned anion exchange membrane A, gasket G2, and the aforementioned cation exchange membrane K form a unit U. Next, as...Figure 1 As shown, a stack S is formed by stacking a plurality of the units U, electrode separators N1, N2 composed of ion exchange membranes are provided at both ends of the stack S and between the anode chamber 10a and the cathode chamber 10b, and the stack S is held by a pair of fastening plates 12, 14 shown in Fig. 2, and is kept by a pressing force applied from the horizontal direction by a pressing device not shown, thereby constituting a fastening type ion exchange dialysis cell 1. The pressing force is applied only to the gasket frame surface of the stack, and the appropriate fastening pressure is generally 0.6 N / mm Figure 1 ±0.1 N / mm 2 ±0.1 N / mm 2 .

[0039] The structure of the flow distribution plate 30 will be described more specifically with reference to Fig. 3(b) in addition to Fig. 3(a). In Fig. 3(b), the area of the broken line R in the flow distribution plate 30 shown in Fig. 3(a) is enlarged. In Fig. 3(b), the direction indicated by the arrows Y1-Y2 is the flow direction of the liquid in the flow distribution portion G1c, and the direction indicated by the arrows X1-X2 is the width direction of the flow distribution portion G1c. As shown in Fig. 3(b), the flow distribution plate 30 is a sheet in a lattice structure formed by welding so that the strands 31, 31 inclined to the left and the strands 32, 32 inclined to the right cross each other. An opening P1'P2'P3'P4' is formed by the points P1', P2', P3', P4' inside the quadrangle P1P2P3P4 formed by the intersections P1, P2, P3, P4 between the strands 31 and 32. In the illustrated opening P1'P2'P3'P4' in the present embodiment, the pitch a (= opening P1'P3') in the liquid flow direction indicated by the arrows Y1-Y2 is formed longer than the pitch b (= opening P2'P4') in the width direction indicated by the arrows X1-X2 orthogonal to the liquid flow direction, but the present application is not limited thereto.

[0040] With respect to the opening ratio of the opening formed by the flow distribution plate 30, generally, it can be explained using the proportion of the area of the opening P1 'P2 'P3 'P4'with respect to the area of the quadrangle P1P2P3P4 formed by the intersection of the strands 31, 31 and the strands 32, 32 shown in Fig. 3(b). Therefore, in the case where the positions of the intersections P1, P2, P3, P4 between the strands 31 and the strands 32 are constant, if the line diameter of the strands 31 and the strands 32 is made large (thick), the opening ratio decreases, and if the line diameter is made small (thin), the opening ratio increases. In addition, even if the line diameter of the strands 31 and the strands 32 is not changed, but the intersections P1, P2, P3, P4 between the strands 31 and the strands 32 are made close or far, the opening ratio can be changed. The line diameter of the strands 31, 32 of which each of the spacers 20 and the flow distribution plate 30 is formed in a mesh structure is generally 0.25 to 0.55 mm, and more preferably 0.28 to 0.45 mm. In addition, the thickness of the flow distribution plate 30 is set in correspondence with the thickness of the gaskets, and the thickness of the flow distribution plate 30 is defined by the thickness of the intersections P1, P2, P3, P4 of the two strands at the time of forming the flow distribution plate 30.

[0041] Here, the present applicant has made various changes in the combination of the opening ratio of the flow distribution plate 30, the thickness of the flow distribution plate 30, the thickness of the gaskets, and the number of the units U constituting the stacking portion S while constituting the above-described fastening-type ion exchange dialysis cell 1, and has verified whether or not internal leakage such as leakage of the liquid flowing in the processing portion of the gasket disposed adjacent to each other in the vicinity of the distribution portions G1c, G2c to the gasket frame G1b, G2b and the ion exchange membrane (anion exchange membrane A, cation exchange membrane K) to which the liquid should not normally flow, and whether or not liquid leakage occurs in the vicinity of the distribution portions G1c, G2c (the mating surface of the ion exchange membrane and the gasket frame). Hereinafter, the verification results will be described.

[0042] It was confirmed that, in a case where the opening ratio of the mesh structure constituting the flow distribution plate 30 is formed to be 26% to 90% and the thickness of the flow distribution plate is formed to be a thickness of 103% to 128% of the thickness of the gasket frame, the above-mentioned internal leakage and liquid leakage leading to generation of a stray current do not occur. In a case where the opening ratio is less than 26%, although the depression of the ion exchange membrane can be suppressed, the pressure loss excessively increases, the flow of liquid in the flow distribution portions G1c, G2c is hindered, and thus it is not preferable. In addition, it was found that, in a case where the opening ratio is greater than 90%, although the pressure loss in the flow distribution portions G1c, G2c becomes small, in a case where a plurality of flow distribution plates 30 are stacked, the probability that each of the intersection points P1, P2, P3, P4 does not overlap in the stacking direction in the adjacent flow distribution plates 30 necessarily increases, and the ion exchange membrane constituting the clearance portion of the mesh structure of the flow distribution plate on one side is pressed by the elastic force of the intersection portion of the flow distribution plate on the other side via the gasket frame, and thus the above-mentioned internal leakage is easily generated.

[0043] In addition, it was found that, even if the opening ratio is set as described above, in a case where the thickness of the flow distribution plate 30 is less than 103% of the thickness of the gasket frame G1b, G2b, the above-mentioned internal leakage is easily generated because the intersection points P1, P2, P3, P4 are not completely coincident in the adjacent flow distribution plates 30 as described above, and thus the local depression of the ion exchange membrane occurs in the clearance portion of the mesh structure constituting the flow distribution plate 30. The greater the opening ratio, the more obvious this problem becomes. In addition, in a case where the thickness of the flow distribution plate 30 is a thickness of more than 128% of the thickness of the gasket frame G1b, G2b, the thickness of the flow distribution plate 30 is excessive, and thus the sealing between the ion exchange membrane (anion exchange membrane A, cation exchange membrane K) and the gasket frame G1b, G2b is insufficient, and liquid leakage occurs on the side of the flow distribution plate 30, and thus such a problem that the efficiency of the ion dialysis cell decreases occurs. The smaller the opening ratio, the more obvious this problem becomes. In addition, the above-mentioned effects are not limited by the number of cells U stacked, but it was confirmed that, in a case where the number of cells U is 30 or more, and more preferably 35 to 400, better effects can be obtained.

[0044] Further, in the case where the number of the cells U stacked is 30 or more, the opening ratio of the mesh structure constituting the flow distribution plate 30 is preferably 30 to 85%, and the thickness of the flow distribution plate 30 is preferably 108 to 119% of the thickness of the gasket frame G1b, G2b. Further, in the case where the number of the cells U stacked is 35 or more and 400 or less, the opening ratio of the mesh structure constituting the flow distribution plate 30 is preferably 40 to 80%, and the thickness of the flow distribution plate 30 is preferably 109 to 115% of the thickness of the gasket frame G1b, G2b. Further, in the case where the number of the cells U stacked is 40 or more and 350 or less, the opening ratio of the mesh structure constituting the flow distribution plate 30 is preferably 50 to 80%, and the thickness of the flow distribution plate 30 is preferably 109 to 113% of the thickness of the gasket frame G1b, G2b. Further, in the present embodiment, the number of the cells U corresponds to the number of the gaskets stacked at the same position in the stacking direction of the ion exchange membrane and the gasket, and the number of the cells U is the same meaning as the number of the gaskets stacked at the same position in the stacking direction of the ion exchange membrane and the gasket.

[0045] By having the above structure, internal leakage in which liquid flowing in the treatment section of the adjacent gasket leaks to the gasket frame and the ion exchange membrane where liquid is not normally supposed to flow in the adjacent gasket can be suppressed, the problem in which the liquids of the independent circulation systems which are not supposed to be mixed in the fastening-type ion exchange dialysis cell, such as the concentrated liquid and the desalinated liquid, are mixed to cause a decrease in the efficiency of the ion dialysis cell, can be eliminated, and the problem in which the ion exchange membrane is deteriorated and damaged irreversibly due to the action of electricity (stray current) flowing in the portion where liquid leaks in the case of the ion dialysis cell in which liquid leaks beside the flow distribution section (the mating surface of the ion exchange membrane and the gasket), can be eliminated.

[0046] Further, as described above, the pitch a of the openings P1'P2'P3'P4' in the liquid flow direction (the direction of the arrows Y1-Y2) at the flow distribution section G1c is preferably longer than the pitch b in the width direction X1-X2 orthogonal to the liquid flow direction Y1-Y2 at the flow distribution section G1c. If the pitch a is shorter than the pitch b, the flowability of the flow distribution section G1c is impaired, and the pressure loss at the flow distribution section G1c increases, which is not preferable. Therefore, the pitch a is preferably 1.1 times or more longer than the pitch b, 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. Further, in the case where the wire diameter of the strand forming the mesh structure is the general wire diameter, the pitch a is generally 0.25 to 0.55 mm, and more preferably 0.28 to 0.45 mm.

[0047] The utility model is not limited to the above-mentioned embodiment, and various variants are included. In the above-mentioned embodiment, an example of applying the laminate of the ion exchange membrane and the gasket formed based on the utility model to the fastening type 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 in which a cation exchange layer and an anion exchange layer are bonded is combined with the above-mentioned anion exchange membrane, cation exchange membrane, and gasket to form a stack to perform ion exchange; a structure in which the bipolar membrane is combined with the anion exchange membrane and the gasket to form a stack to perform ion exchange; a structure in which the bipolar membrane is combined with the cation exchange membrane and the gasket to form a stack to perform ion exchange; and an ion dialysis cell in which the ion exchange membrane and the gasket are laminated to perform diffusion dialysis. That is, the utility model exerts an effect in an ion dialysis cell including a laminate of one or more ion exchange membranes and the above-mentioned gasket, and more preferably, in a case where the number of laminated gaskets of the flow distribution plate laminated at the same position in the laminating direction of the ion exchange membrane and the gasket is 30 or more (the number of units U is 30 or more) in the ion dialysis cell, a better effect can be exerted.

[0048] In addition, the communication holes (Aa, Ab, Ka, Kb) of the ion exchange membranes (anion exchange membrane A, cation exchange membrane K) in the above-mentioned embodiment are each formed in four in total, but the utility model is not limited thereto, and the number thereof can be other numbers, and the size thereof can be set as needed. In addition, in the above-mentioned embodiment, the communication holes Aa, Ab, Ka, Kb of the anion exchange membrane A and the cation exchange membrane K are substantially quadrangular, but the utility model is not limited thereto, and can be circular. Even if the communication holes Aa, Ka are circular, according to the utility model, the same effects as in the above-mentioned embodiment can be exerted.

Claims

1. A gasket, laminated together with an ion exchange membrane in an ion dialysis cell serving as a fixed-type ion exchange dialysis cell or a fixed-type diffusion dialysis cell, characterized in that, The gasket comprises: The processing unit forms a space for ion exchange in a fixed-type ion exchange dialysis cell and a space for diffusion or dialysis in a fixed-type diffusion dialysis cell. as well as Gasket frame, which surrounds the processing unit, A flow distribution section is formed in the gasket frame, connecting the processing section and the ion exchange membrane formed on the stacked gasket. The distribution section is equipped with a distribution plate with a mesh structure. The opening ratio of the mesh structure constituting the distributor plate is formed to be 26% to 90%, and the thickness of the distributor plate is formed to be 103% to 128% of the thickness of the gasket frame.

2. An ion dialysis cell, characterized in that, The ion dialysis cell comprises a laminate formed by stacking one or more ion exchange membranes and the gaskets as described in claim 1, wherein the number of gaskets stacked at the same position in the stacking direction of the ion exchange membranes and the gaskets is 30 or more.

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