Electrodeionized water production apparatus and frame for electrodeionized water production apparatus

Abstract

To provide an electric type deionized water production device (EDI device) that can stably process water to be treated at a large flow rate, while preventing an imbalance of an ion exchanger filled in a desalting chamber and a deformation of an ion exchange membrane that partitions the desalting chamber.SOLUTION: There is provided an EDI device 1 including: a frame 43 having a penetrating opening; an ion exchanger filled in the opening; and a desalting chamber 23 partitioned by a pair of ion exchange membranes 32 and 33 arranged so as to close both ends of the opening, respectively, wherein an opening of the frame 43 consists of a plurality of mutually separated openings 63, each of which has a width W of more than 100 mm and less than 240 mm.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to an electric deionized water production device and a frame used for the electric deionized water production device.

Background Art

[0002] As one of the devices for generating deionized water from treated water, there is an electric deionized water production device (also referred to as an EDI (Electrodeionization) device. Hereinafter, the electric deionized water production device will also be referred to as an EDI device). The EDI device is a device that combines electrophoresis and electrodialysis, and has a configuration in which one or more desalination chambers are arranged via a concentration chamber between an anode chamber provided with an anode and a cathode chamber provided with a cathode. And these chambers adjacent to each other (that is, the anode chamber, the concentration chamber, the desalination chamber, and the cathode chamber) are partitioned by ion exchange membranes. The desalination chamber is filled with an ion exchanger such as an ion exchange resin and the treated water is supplied. It is preferable that the anode chamber, the concentration chamber, and the cathode chamber are also filled with an ion exchanger. In the EDI device, by applying a DC voltage between the anode and the cathode, the desalination treatment of the treated water and the regeneration treatment of the ion exchanger proceed simultaneously. The EDI device has the advantage of not requiring chemicals for the regeneration of the ion exchanger.

[0003] An EDI apparatus can have a structure in which at least a concentration chamber and a desalination chamber are repeatedly arranged separated by an ion exchange membrane. Therefore, the concentration chamber and desalination chamber can be constructed by using multiple frames (also called spacers, etc.) with through-openings, and stacking the frames with the ion exchange membrane in between. Such a frame can be considered as a plate-like member with openings formed through both surfaces, and assuming that the plate-like member is made into a frame by providing openings, the thickness of the plate-like member can be said to be the thickness of the frame. Each time a frame constituting the desalination chamber is stacked, the opening of that frame is filled with an ion exchange material for the desalination chamber. An EDI apparatus configured in this way is used in a position where the direction from the anode to the cathode is horizontal, and the openings of multiple frames stacked in the thickness direction of the frames form a single cylindrical space, with the anode and cathode positioned at both ends of this space. In this position, the cylindrical space formed by the openings of the multiple frames is partitioned by the ion exchange membrane interposed between the frames, and the small spaces formed by this partitioning become the concentration chamber and the desalination chamber, respectively. In an EDI device constructed by stacking frames, water to be treated is supplied in parallel to multiple desalination chambers. In the following description, when referring to the frame, the openings in the frame, or the vertical direction of the openings, it refers to the vertical direction in the operating state of the EDI device equipped with that frame. The direction perpendicular to both the vertical direction and the thickness direction of the frame will be called the horizontal direction.

[0004] Furthermore, in EDI devices, when an ion exchange resin is filled into the opening of the frame to form a desalination chamber, a method has been proposed to prevent the ion exchange resin from moving or being compressed within the desalination chamber, and to further prevent deformation of the ion exchange material, by dividing such a large opening in the frame so that multiple elongated openings extending in the vertical direction are arranged in the horizontal direction, rather than having one large opening in the frame (see, for example, Patent Documents 1 and 2). Patent Document 3 discloses arranging honeycomb-shaped partition members within a large opening in the frame and filling the small chambers formed by the partition members with an ion exchange material, and Patent Document 4 discloses dividing a large opening in the frame into a grid and filling the inside of the small chambers formed by each grid with an ion exchange material.

[0005] Some EDI devices further divide the desalination chamber into a first small desalination chamber on the anode side and a second small desalination chamber on the cathode side by an intermediate ion exchange membrane, and the water to be treated is configured to pass through these small desalination chambers sequentially. Such EDI devices can also be assembled by alternately stacking frames and ion exchange membranes, in which case each small desalination chamber is composed of a frame for the small desalination chamber, ion exchange membranes arranged on both sides of the frame so as to cover the opening of the frame, and an ion exchange material filled in the opening. Patent Document 5 discloses dividing the opening of the frame constituting each small desalination chamber into multiple openings, and Patent Document 6 discloses dividing the opening of the frame constituting the first small desalination chamber on the anode side into multiple openings.

[0006] In recent years, there has been a growing need for large quantities of high-purity water in fields such as semiconductor equipment manufacturing. Due to its characteristic of not requiring chemicals for the regeneration of ion exchangers, there is a growing demand for large-scale EDI equipment capable of processing large volumes of water in a single unit, i.e., high-flow EDI equipment, for applications involving the mass production of high-purity water. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 107906 / 1983 [Patent Document 2] Special Publication No. 7-16587 [Patent Document 3] Japanese Patent Publication No. 2002-136971 [Patent Document 4] Japanese Patent Publication No. 2006-218382 [Patent Document 5] Japanese Patent Publication No. 2001-239270 [Patent Document 6] Japanese Patent Publication No. 2011-576 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] In an EDI system, there is an upper limit to the appropriate space velocity (SV) when water to be treated is passed through a desalination chamber filled with ion exchange material. To increase the flow rate of water to be treated in an EDI system, it is necessary to increase the total amount of ion exchange material filled in the EDI system. Here, a desalination chamber having a frame with a through-opening and ion exchange material filled in the opening, and partitioned by a pair of ion exchange membranes positioned to close both ends of the opening, will be called a cell. Methods for constructing a high-flow EDI system include increasing the number of desalination chambers, i.e., increasing the number of stacked cells, and increasing the size of the cells to enlarge their openings. At least one of these methods is adopted. However, increasing the number of stacked cells increases the operating voltage of the EDI system, so there is a practical upper limit to the number of stacked cells. On the other hand, when aiming to enlarge the cell, if the opening of the cell is divided into multiple openings as described in Patent Documents 1-5, these patent documents state that the width of the openings is preferably about 40-50 mm or less, so the number of openings provided in the cell increases. In this case, since it is necessary to fill each of the numerous openings with the appropriate amount of ion exchange material, such as ion exchange resin, the workability when assembling the EDI device decreases. Also, as the number of openings in the frame increases, the proportion of the beam-like parts separating the openings to the overall dimensions of the frame becomes significant, necessitating an even larger frame. When enlarging the cell, increasing it vertically can lead to excessively large water pressure differences or affect desalination performance, so the cell needs to be enlarged horizontally, based on the operating orientation of the EDI device.

[0009] The object of the present invention is to provide an EDI device that can stably treat water to be treated at a high flow rate while preventing uneven distribution of the packed ion exchanger and deformation of the ion exchange membrane, and a frame used in such an EDI device. [Means for solving the problem]

[0010] The EDI apparatus (electrodeionized water production apparatus) according to the present invention comprises a frame having a through-opening, an ion exchanger filled in the opening, and a desalination chamber partitioned by a pair of ion exchange membranes arranged to close both ends of the opening, wherein the opening consists of a plurality of mutually separated openings, and each opening has a width greater than 100 mm and less than 240 mm.

[0011] The frame according to the present invention is used in an EDI device and is a frame having a through-hole used for filling an ion exchanger, characterized in that the opening consists of a plurality of mutually separated openings, and each opening has a width greater than 100 mm and less than 240 mm.

[0012] In the present invention, the width of each opening formed in the frame is preferably 105 mm or more and 200 mm or less, more preferably 110 mm or more and 180 mm or less, and even more preferably 120 mm or more and 160 mm or less. In the present invention, "width of the opening" refers, for example, to the length of the shorter side when each opening is formed in a substantially rectangular shape. An EDI device based on the present invention can be configured such that a desalination chamber and a concentration chamber are alternately arranged by stacking a large number of frames in the thickness direction with an ion exchange membrane in between. In this case, the direction of water flow in the desalination chamber is usually the vertical direction when the EDI device is in use. If water flows along the vertical direction in the desalination chamber, the length of the opening in the direction perpendicular to the direction of water flow, that is, the length of the opening in the horizontal direction as described above, may be defined as the "width of the opening" in the present invention. When the length in the horizontal direction is defined as the width of the opening, the multiple openings formed in the frame can be arranged so as to be aligned with each other in the horizontal direction, and furthermore, the length of the opening in the vertical direction can be made longer than the width of the opening.

[0013] In order to reduce the water flow differential pressure in the desalination chamber used in a high-flow EDI device, it is effective to form a frame that is long in the lateral direction. Considering mechanical strength and the like, if the length of the frame along the lateral direction is a, for example, a can be 500 mm or more and 1000 mm or less. Alternatively, if the length of the frame in the vertical direction is b, it is preferable that a > b, that is, a / b > 1. More preferably, a / b > 1.2, and even more preferably, a / b > 1.5.

Advantages of the Invention

[0014] According to the present invention, it is possible to obtain an EDI device that can stably treat the water to be treated at a high flow rate while preventing the bias of the filled ion exchanger and the deformation of the ion exchange membrane.

Brief Description of the Drawings

[0015] [Figure 1] It is a schematic cross-sectional view showing an EDI device according to an embodiment of the present invention. [Figure 2] It is an assembled perspective view of the EDI device shown in FIG. 1. [Figure 3] It is a schematic cross-sectional view showing the configuration of an EDI device according to another embodiment. [Figure 4] It is a front view showing a general frame according to the prior art. [Figure 5] It is a front view showing an example of the configuration of the frame used in the present invention. [Figure 6] It is a schematic front view showing an example of the flow of the water to be treated. [Figure 7] It is a front view showing another example of the configuration of the frame. [Figure 8] It is a view showing the main part of the EDI devices of Examples 1 to 3 and Comparative Example 1. [Figure 9] It is a view showing the main part of the EDI device of Example 4.

Modes for Carrying Out the Invention

[0016] Next, embodiments for carrying out the present invention will be described with reference to the drawings. Figure 1 shows an EDI device according to one embodiment of the present invention. The illustrated EDI device 10 has a concentration chamber 22, a desalination chamber 23, and a concentration chamber 24 arranged between an anode chamber 21 provided with an anode 11 and a cathode chamber 25 provided with a cathode 12, with an ion exchange membrane in between from the anode 11 side, and the desalination chamber 23 and concentration chamber 24 may be arranged in this order repeatedly. This repeating unit, that is, one desalination chamber 23 and one concentration chamber 24 adjacent to it, is called a cell pair. Therefore, the EDI device 10 has the configuration of anode chamber 21, concentration chamber 22, desalination chamber 23, concentration chamber 24, desalination chamber 23, concentration chamber 24, ..., concentration chamber 24, cathode chamber 25. A cation exchange membrane 31 is interposed between the anode chamber 21 and the concentration chamber 22, an anion exchange membrane 32 is interposed between the concentration chamber 22 and the desalination chamber 23, and an anion exchange membrane 34 is interposed between the concentration chamber 24 and the cathode chamber 25. Furthermore, an anion exchange membrane 32 is interposed between the concentration chamber 24 adjacent to the desalination chamber 23 on the anode 11 side and the desalination chamber 23, and a cation exchange membrane 33 is interposed between the concentration chamber 24 adjacent to the desalination chamber 23 on the cathode 12 side and the desalination chamber 23. As a result, the desalination chamber 23 is partitioned by the anion exchange membrane 32 on the anode 11 side and the cation exchange membrane 33 on the cathode 12 side.

[0017] The desalination chamber 23 is filled with ion exchange resin as an ion exchange material. In order to lower the DC voltage to be applied between the anode 11 and the cathode 12 when the EDI device 10 is in operation, it is preferable that the anode chamber 21, concentration chambers 22, 24 and cathode chamber 25 are also filled with ion exchange material such as ion exchange resin. The desalination chamber 23 is supplied with water to be treated and discharges deionized water as treated water. The anode chamber 21 and cathode chamber 25 are supplied with electrode chamber supply water and discharge electrode water. The concentration chambers 22 and 24 are supplied with concentration chamber supply water and discharge concentrated water.

[0018] When filling the concentration chambers 22 and 24 with ion exchange resin, including cation exchange resin in the ion exchange resin allows for a lower operating voltage of the EDI device 10, stabilizes the operating voltage, and improves the boron removal rate. On the other hand, if only cation exchange resin is filled into the concentration chambers 22 and 24, there is a risk of an increase in operating voltage when the water to be treated or the water supplied to the concentration chambers 22 and 24 contains hardness components such as calcium and magnesium. For these reasons, it is preferable to fill the concentration chambers 22 and 24 with anion exchange resin and cation exchange resin in a mixed state. When filling the concentration chambers 22 and 24 with a mixture of anion exchange resin and cation exchange resin, let A be the apparent volume of the anion exchange resin and C be the apparent volume of the cation exchange resin, the mixing ratio A:C of these ion exchange resins is preferably between 20:80 and 60:40, and more preferably between 20:80 and 50:50. Furthermore, the ratio of A to C can be determined even after filling the concentration chambers 22 and 24 with ion exchange resin. This can be done by removing the filled ion exchange resin from the concentration chambers 22 and 24, separating it into anion exchange resin and cation exchange resin, and measuring the apparent volume of the separated anion exchange resin and the apparent volume of the separated cation exchange resin, respectively.

[0019] The EDI device 10 has a configuration in which multiple frames 41-45, each having an opening, are stacked with an ion exchange membrane in between them. The anode 11 and cathode 12 are located at both ends of the stacking direction of the frames 41-45 and face each other through the openings of the frames 41-45. The anode chamber 21, concentration chamber 22, desalination chamber 23, concentration chamber 24, and cathode chamber 25 are each composed of frames 41, 42, 43, 44, and 45. The anode 11 is fixed to frame 41 via a retaining plate 48, and the cathode 12 is fixed to frame 45 via a retaining plate 49. The frame 41 that constitutes the anode chamber 21 and the frame 42 that constitutes the concentration chamber 22 are adjacent to each other, but the openings of these frames 41 and 42 are separated by the cation exchange membrane 31, thereby partitioning the anode chamber 21 and the concentration chamber 22 from each other. Similarly, an anion exchange membrane 32 is placed between adjacent frame 42 and frame 43, a cation exchange membrane 33 is placed between adjacent frame 43 and frame 44, and an anion exchange membrane 34 is placed between adjacent frame 44 and frame 45.

[0020] In Figure 1, the channels 51 for supplying treated water to multiple desalination chambers 23, the channels 52 for supplying concentrate supply water to multiple concentrate chambers 22, 24, the channels 53 for recovering deionized water from the multiple desalination chambers 23, and the channels 54 for recovering concentrate water from the multiple concentrate chambers 22, 24 are depicted outside the frames 41-45. However, since each of the channels 51-54 extends parallel to the direction from the anode 11 to the cathode 12, in reality they are provided to penetrate at least the frames 42-44 so as to communicate between adjacent frames 42-44. Figure 2 is an exploded perspective view of the EDI device 10 shown in Figure 1, but the channels 51-54 are not depicted in Figure 2.

[0021] By sequentially stacking the frames with an ion exchange membrane in between to form the concentration chambers 22, 24 and the desalination chamber 23, the EDI device 10 can be easily manufactured. When stacking the frames, the frames are stacked with the openings facing upwards. When filling each chamber (anode chamber 21, concentration chamber 22, desalination chamber 23, concentration chamber 24, and cathode chamber 25) with ion exchange resin, the frames constituting that chamber are stacked, the ion exchange resin is filled into the openings of the frames, and then the next frame is placed on top with an ion exchange membrane in between.

[0022] When operating the EDI apparatus 10 shown in Figure 1 to produce deionized water, the orientation of the EDI apparatus 10 is set such that the direction from the anode 11 to the cathode 12 is horizontal, and the direction of water flow inside the anode chamber 21, concentration chambers 22, 24, desalination chamber 23, and cathode chamber 25 is vertical. In this orientation, each frame 41-45 is upright and their openings face horizontal. Then, by supplying concentration chamber water to the concentration chambers 22 and 24, supplying electrode chamber water to the anode chamber 21 and cathode chamber 25, and supplying the water to be treated to the desalination chamber 23 while applying a DC voltage between the anode 11 and cathode 12, the desalination treatment of the water to be treated and the regeneration treatment of the ion exchange resin proceed simultaneously in the desalination chamber 23, and deionized water can be obtained from the desalination chamber 23.

[0023] Figure 3 shows an EDI device 10 of another embodiment. This EDI device 10 divides the desalination chamber 23 of the EDI device 10 shown in Figure 1 into a first small desalination chamber 26 on the anode 11 side and a second small desalination chamber 27 on the cathode 12 side, with an intermediate ion exchange membrane 35 separating the first small desalination chamber 26 and the second small desalination chamber 27. Ion exchange resin is filled into both the first small desalination chamber 26 and the second small desalination chamber 27. The water to be treated is supplied to the first small desalination chamber 26, and the water to be treated discharged from the first small desalination chamber is then supplied to the second small desalination chamber 27, from which deionized water is discharged as treated water. Flow paths 55 and 56 are provided to supply the water to be treated discharged from the first small desalination chamber to the second small desalination chamber 27. In the EDI device 10 shown in Figure 3, the first small desalination chamber 26 and the second small desalination chamber 27 are each composed of frames 46 and 47. Frames 46 and 47 are the same as frame 43 in the EDI device 10 shown in Figure 1. In Figure 3, the flow paths 55 and 56 are depicted outside the frames 42, 44, 46, and 47, but in reality, the flow paths 55 and 56 are provided to penetrate at least the frames 42, 44, 46, and 47 so as to communicate between adjacent frames 42, 44, 46, and 47, similar to the flow paths 51 to 54. In the EDI device 10 where the first small desalination chamber 26 and the second small desalination chamber 27 are adjacent to each other via an intermediate ion exchange membrane 35, a cell pair is formed by the first small desalination chamber 26, the second small desalination chamber 27, and the concentration chamber 24.

[0024] Next, the frames 43, 46, and 47 that constitute the desalination chamber 23 or the small desalination chambers 26, 27 in the EDI apparatus 10 according to the present invention will be described. Frame 43 and frames 46, 47 differ in whether or not through holes corresponding to the flow paths 55, 56 are provided. Here, frame 43 will be described, but before describing frame 43, a general frame that has been used conventionally will be described. Figure 4 shows a frame 90 that is commonly used in conventional EDI apparatuses, which are constructed by stacking frames with an ion exchange membrane in between, similar to the EDI apparatus 10 shown in Figure 1. Frame 90 is a plate-shaped member with an opening 60. The outer shape of frame 90 is a rectangle with rounded vertices, and the opening 60 is provided in the approximate center of frame 90 so as to penetrate both surfaces of the plate-shaped members that constitute frame 90. The thickness direction of the plate-shaped member is called the thickness direction of the frame. In the frame 90, through holes 71 to 74 are provided between the outer circumference of the frame 90 and the opening 60, respectively, which constitute the aforementioned flow paths 51 to 54.

[0025] When used as a desalination chamber 23, the water to be treated flows vertically, perpendicular to the thickness direction of the frame 90, through a space partitioned by the opening 60 of the frame 90 and ion exchange membranes positioned to close both ends of the opening 60. To ensure a uniform flow of the water to be treated within the desalination chamber filled with ion exchange resin and to reduce the differential pressure, the opening 60 has a roughly rectangular shape, with its width being longer than its height. An internal flow path 61 is provided, connecting a through-hole 71 corresponding to the flow path 51 through which the water to be treated flows to one side of the opening 60, either the upper or lower edge. The internal flow path 61 guides the water to be treated from the flow path 51 to the opening 60 and is formed to spread out in a fan shape so that, as viewed from the through-hole 71, the water to be treated can be supplied along the entire length of one side of the opening 60, either the upper or lower edge. At the point where the internal flow path 61 connects to the opening 60, the internal flow path 61 is formed as a slit in the wall surface of the opening 60, communicating with the opening 60. Similarly, in order to recover deionized water from the desalination chamber, an internal channel 62 is provided that connects a through-hole 73 corresponding to the channel 53 through which the deionized water flows to the other side of the upper or lower edge of the opening 60.

[0026] If L is the length of the opening 60 along the flow direction of the water to be treated in the desalination chamber 23 (i.e., vertical direction), and W is the width of the opening in the horizontal direction, then since the opening 60 is longer in the horizontal direction, W > L holds true for the general frame 90 shown in Figure 4. Therefore, if a is the length in the horizontal direction and b is the length in the vertical direction of the outer shape of the frame 90, then generally a > b holds true. In an EDI device that flows water to be treated in the desalination chamber 23 at a large flow rate, the width W becomes large, for example, to about 300 mm to 800 mm, and the width a of the frame 90 itself also becomes large, for example, to about 500 mm to 1000 mm. In such a general frame 90, because the opening 60 is large, when used in the EDI device 10, the deformation of the ion exchange membrane that partitions the desalination chamber 23 becomes large, which can lead to an increase in the differential pressure of the water flow and an increase in the operating voltage. To solve these problems, as mentioned in the background technology section, it is known to divide the opening 60 into numerous compartments, typically multiple elongated sections. However, when divided in this way, the efficiency of filling the desalination chamber with ion exchange material decreases.

[0027] Therefore, in the EDI device 10 based on the present invention, assuming that the EDI device 10 is configured as shown in Figure 1, a frame 43 is used that can suppress deformation of the ion exchange membrane, uneven distribution of the ion exchange material, and increase in the differential pressure of the water flow without significantly impairing the workability of filling the ion exchange material into the desalination chamber 23. The frame 43 is obtained by dividing the opening 60 of a general frame 90 shown in Figure 4 into a plurality of mutually separated openings 63. Figure 5 shows an example of the configuration of the frame 43. In Figure 5, (a) shows a frame 43 obtained by dividing the opening 60 of the frame 90 in Figure 4 into two openings 63, (b) shows a frame 43 obtained by dividing the opening 60 into three openings 63, (c) shows a frame 43 obtained by dividing the opening 60 into four openings 63, and (d) shows a frame 43 obtained by dividing the opening 60 into five openings 63. In all cases, the shape of the openings 63 in the frame 43 is approximately rectangular, and the plurality of openings 63 are arranged in the width direction. The internal flow channels 61 and 62 that were present in the general frame 90 shown in Figure 4 remain in the frame 43 as well. Therefore, the water to be treated is supplied evenly to each opening 63 of the frame 43, and the deionized water produced by the desalination treatment is recovered evenly from each opening 63. In all of the frame 43s shown in Figures 5(a) to (d), the length L of the opening 63 along the flow direction of the water to be treated is the same as the length L of the opening 60 in the general frame 90 shown in Figure 4.

[0028] When the length of each opening 63 in the direction orthogonal to the flow direction of the treated water is defined as the width W, W exceeds 100 mm and is less than 240 mm. The width W is preferably 105 mm or more and 200 mm or less, more preferably 110 mm or more and 180 mm or less, and even more preferably 120 mm or more and 160 mm or less. The width W of the opening 60 before being divided into a plurality of openings 63 (the width W of the opening 60 in the frame body 90 shown in FIG. 4) satisfied W>L, but in each opening 63, it may be W<L, and rather, it is preferable that W<L. In any of the frame bodies 43 shown in (a) to (e) in FIG. 5, W<L. The outer peripheral dimensions of the frame body 43 are substantially the same as those of the frame body 90 shown in FIG. 4. Therefore, the length a in the lateral width direction of the frame body 43 is, for example, 500 mm or more and 1000 mm or less, preferably 650 or more and 800 mm or less. Also, it is preferable that the length b in the vertical direction of the frame body is smaller than the length a in the lateral width direction, that is, a / b>1. More preferably, a / b>1.2, and even more preferably, a / b>1.5.

[0029] Next, the water flow in the frame body 43 will be described. In each frame body 43 shown in FIG. 5, for the plurality of provided openings 63, the treated water is supplied in parallel from the through hole 71 through the internal flow path 61, and the deionized water obtained by performing desalination treatment in each opening 63 is also collected in parallel from the plurality of openings 63 through the internal flow path 62 to the through hole 72. If the number of openings 63 in the frame body 43 is three, then in the frame body 43, water will flow as shown in FIG. 6(a). However, when the increase in the water passing differential pressure can be ignored, as shown in FIG. 6(b), it is also possible to make water flow in series through the plurality of openings 63 formed in one frame body 43.

[0030] The EDI device 10 according to the present invention is designed to prevent an increase in water flow differential pressure and deformation of the ion exchange membrane when the opening 60 (see Figure 4) formed in the frame 43 constituting the desalination chamber 23 becomes large when attempting to desalinate the water to be treated at a large flow rate in the desalination chamber 23. To achieve this, the opening 60 is divided into multiple openings 63 (see Figure 5), and the lower and upper limits of the width of each opening 63 are defined. In the cases shown in Figures 5(a) to (d), the width W of the opening 63 is the length of the opening 63 in the lateral direction. However, if it is possible to prevent an increase in water flow differential pressure and deformation of the ion exchange membrane, the length of the opening 63 along the water flow can be defined as the width of the opening 63, and this width can be greater than 100 mm and less than 240 mm. The frame 43 shown in Figure 7 is formed by dividing the opening 60 of the frame 90 shown in Figure 4 into two in the vertical direction, with each becoming an opening 63. In the case shown in Figure 7, since water passing through the upper opening 63 needs to be supplied to the lower opening 63, multiple slits 64 communicating with both openings 63 are provided between the two openings 63. In the frame 43 shown in Figure 7, the length of the shorter side of the roughly rectangular opening 63, that is, the length in the vertical direction of the opening 63, is defined as the width D of the opening 63. The width D is greater than 100 mm and less than 240 mm. If the length of the opening 63 in the horizontal direction is C, then C > D.

[0031] Considering both the case shown in Figure 5 and the case shown in Figure 7, in the EDI device according to the present invention, the width of the opening may be the length of the opening along the direction perpendicular to the water flow direction in the desalination chamber, or, if the opening is substantially rectangular, it may be the length of its shorter side. In any case, the width of the opening is greater than 100 mm and less than 240 mm. [Examples]

[0032] Next, the present invention will be described in more detail with reference to examples.

[0033] [Examples 1-3, Comparative Example 1] Four EDI devices 10, each having the structure shown in Figure 3 and differing in opening width W, were assembled and designated as the EDI devices for Examples 1-3 and Comparative Example 1, respectively. The number of cell pairs in each EDI device 10 was set to 7. The desalination chamber consists of a first small desalination chamber 26 on the anode 11 side and a second small desalination chamber 27 on the cathode 12 side, separated by an intermediate ion exchange membrane 35. However, unlike that shown in Figure 3, in the EDI devices 30 of Examples 1-3 and Comparative Example 1, the water flow direction in the first small desalination chamber 26 and the water flow direction in the second small desalination chamber 27, which are adjacent to each other across the intermediate ion exchange membrane 35, are in a countercurrent relationship. The water to be treated is first supplied to the first small desalination chamber 26, and the water to be treated that has passed through the first small desalination chamber 26 is supplied to the second small desalination chamber 27. The frames 46 and 47 used to construct these small desalination chambers 26 and 27 each have a length a in the lateral direction of 655 mm, and the opening to which the ion exchange resin is to be filled is divided into multiple openings 63 in the lateral direction. In addition, each EDI device 10 is provided with seven sets of first small desalination chambers 26 and second small desalination chambers 27 via a concentration chamber 24. By changing the number of divisions when dividing the opening into openings 63, the opening width W in the frames 46 and 47 was set to 240 mm in the EDI device 10 of Comparative Example 1, to 160 mm in the EDI device 10 of Example 1, to 120 mm in the EDI device 10 of Example 2, and to 96 mm in the EDI device 10 of Example 3.

[0034] Figure 8 shows the main components of the EDI apparatus 10 used in Examples 1-3 and Comparative Example 1, illustrating how ion exchange resin was packed into the two adjacent small desalination chambers 26 and 27 and the adjacent concentration chambers 22 and 24. An anion exchange membrane (AEM) is used in the intermediate ion exchange membrane 35 that separates the first small desalination chamber 26 on the anode 11 side from the second small desalination chamber 27 on the cathode 12 side. The first small desalination chamber 26 is packed with anion exchange resin (AER) in a single bed, and the concentration chamber 22 adjacent to the first small desalination chamber 26 is also packed with anion exchange resin in a single bed via the anion exchange membrane (AEM) 32. The second small desalination chamber 27 is divided into two regions with respect to the flow of the treated water: an inlet side and an outlet side. The inlet side region is packed with cation exchange resin (CER), and the outlet side region is packed with anion exchange resin. In other words, the second small desalination chamber 27 is filled with cation exchange resin and anion exchange resin in a double bed configuration. Furthermore, an anion exchange membrane 37 is provided at the interface where the cation exchange membrane (CEM) 33 and the anion exchange resin in the second small desalination chamber 27 come into contact. The concentration chamber 24 adjacent to the second small desalination chamber 27 is also filled with anion exchange resin in a single bed configuration via the cation exchange membrane 33.

[0035] Concentration chambers 22 and 24 were supplied with concentrate chamber water, and the water to be treated was supplied to the first small desalination chamber 26. A water flow test was conducted by operating a total of four EDI devices 10 (Examples 1-3 and Comparative Example 1) in parallel, ensuring that the operating conditions (space velocity (SV) of water flow in each chamber, applied current, and water quality of the supplied water) were the same. The applied DC voltage (applied voltage) and water flow differential pressure were measured after 1500 hours of operation. Immediately afterward, the operation was stopped, the EDI device 10 was dismantled, and the deformation of the ion exchange membrane was visually observed.

[0036] Regarding the applied voltage, a value suitable for operation was classified as "A," a value that does not hinder operation was classified as "B," and a value that is too high and unsuitable for operation was classified as "C." Regarding the differential pressure of the water flow, a value that is suitable for the differential pressure of the water flow during operation was classified as "A," a value that does not hinder operation was classified as "B," and a value that is too high and unsuitable for operation was classified as "C." Regarding the deformation of the ion exchange membrane, those in which no significant deformation was observed and it was considered that good operation could be continued were classified as "A," those in which deformation was observed but it was considered that it did not hinder the continuation of operation was classified as "B," and those in which there was significant deformation and it was considered unsuitable for the continuation of operation was classified as "C." The results are shown in Table 1.

[0037] [Table 1]

[0038] In the EDI device 10 of Comparative Example 1, where the width W of the opening 63 is 240 mm, significant deformation of the ion exchange membrane was observed, as well as increases in the applied voltage and water flow differential pressure. In particular, the applied voltage tended to increase consistently from the start of operation. In the EDI devices 10 of Examples 1 to 3, where the width W of the opening 63 is not 240 mm, the applied voltage was stable after 1500 hours from the start of operation. Regarding the water flow differential pressure, the width W of the opening 63 is 96 mm. Example 3 EDI device 10 showed higher values ​​compared to EDI devices 10 in Examples 1 and 2, which had widths W of 160 mm and 120 mm, respectively. The amount of deformation of the ion exchange membrane was particularly small when the width W of the opening 63 was 120 mm or less. From the results of Examples 1 to 3 and Comparative Example 1, it was found that the width W of the opening 63 should be greater than 100 mm and less than 240 mm, from the viewpoint of applied voltage, water flow differential pressure, and the amount of deformation of the ion exchange membrane. Furthermore, when no significant deformation was observed in the ion exchange membrane, no unevenness was observed in the filled ion exchange resin.

[0039] [Example 4] In the EDI apparatus 10 of Example 2, a mixture of anion exchange resin and cation exchange resin was packed into the concentration chambers 22 and 24; that is, a mixed bed of anion exchange resin and cation exchange resin was prepared. When packing the mixed bed, the ratio A:K of the apparent volume A of the anion exchange resin to the apparent volume K of the cation exchange resin was set to 1:1. Figure 9 shows the main parts of the EDI apparatus 10 of Example 4. The EDI apparatus 10 of Example 2 and the EDI apparatus 10 of Example 4 have the same configuration and size, except that in Example 2, the concentration chambers 22 and 24 are packed with a single bed of anion exchange resin, while in Example 4, the anion exchange resin and cation exchange resin are packed in a mixed bed. In particular, both of these EDI apparatuses 10 have 7 cell pairs, a width W of the opening 63 is 120 mm, and a cell width a is 655 mm.

[0040] The same water to be treated, with a boron concentration of 10 ppb, was supplied, and the EDI devices 10 of Examples 2 and 4 were operated under identical operating conditions such as space velocity and current density. The boron removal performance and operating voltage were then compared and evaluated. The water to be treated did not contain hardness components such as calcium or magnesium, and the current density was 1.1 A / dm². 2 Table 2 shows the operating voltage and boron removal rate 200 hours after the start of operation, and Table 3 shows the operating voltage and boron removal rate 2000 hours after the start of operation. The number of cell pairs in the EDI device 10 in Examples 2 and 4 is 7, but when treating water to be treated at a large flow rate in the EDI device, the number of cell pairs will be increased within the range that the operating voltage can tolerate. Therefore, the operating voltage expected when the number of cell pairs is set to 50 for high flow rate treatment is shown in the table as the "converted voltage assuming large scale". Note that the upper limit of the operating voltage is generally 600V depending on the specifications of the DC power supply used to drive the EDI device.

[0041] [Table 2]

[0042] [Table 3]

[0043] As shown in Tables 2 and 3, in Example 2, where only anion exchange resin was filled into the concentration chambers 22 and 24, the operating voltage tended to increase and the boron removal rate to decrease as time progressed from the start of operation. In contrast, in Example 4, where anion exchange resin and cation exchange resin were mixed and filled into the concentration chambers 22 and 24, the operating voltage remained stable and the boron removal rate was maintained. In particular, the boron removal performance was better in Example 4 than in Example 2. Assuming that the concentration chamber is partitioned by a cation exchange membrane located on the anode side and an anion exchange membrane located on the cathode side, in the EDI device during operation, hydrogen ions (H) are transmitted to the concentration chamber via the cation exchange membrane. + ) moves in. When cation exchange resin is present in the concentration chamber, the moved hydrogen ions move within the concentration chamber. However, when only anion exchange resin is present in the concentration chamber, hydrogen ions remain in the region near the cation exchange membrane, and the pH in that region decreases. On the other hand, the boron component that moves from the desalting chamber to the concentration chamber is captured by the anion exchange resin in the concentration chamber in the form of anions containing boric acid, moves towards the anode within the concentration chamber, and concentrates in the region near the cation exchange membrane. When the boron-containing anions concentrate in the region near the cation exchange membrane, if the pH in this region is low, the boron-containing anions become neutral molecules containing boron, and because they are neutral molecules, they can move across the cation exchange membrane and leak into the desalting chamber. This leakage of the boron component into the desalting chamber is caused by the fact that boron-containing anions can move within the concentration chamber, but hydrogen ions do not move easily. Therefore, this can be suppressed by mixing cation exchange resin with anion exchange resin in the concentration chamber. This is thought to be the reason why the presence of cation exchange resin in concentration chambers 22 and 24 results in higher boron removal performance.

[0044] The results shown in Tables 2 and 3 indicate that, in order to operate the EDI device stably over a long period and maintain its boron removal performance (desalination performance), it is preferable to fill the concentration chambers 22 and 24 with a mixture of anion exchange resin and cation exchange resin. It was also found that by filling the concentration chambers 22 and 24 with a mixture of anion exchange resin and cation exchange resin, the operating voltage can be lowered, thereby reducing power consumption. [Explanation of Symbols]

[0045] 10. Electrical deionized water production system (EDI system) 11 Anode 12 Cathode 21 Anode chamber 22,24 Concentration chamber 23 Desalination room 25 Cathode Chamber 26, 27 Small desalination chamber 31, 33, 37 Cation exchange membrane (CEM) 32,34 Anion exchange membrane (AEM) 35 Intermediate ion exchange membrane 41~47,90 Frame 51-56 Channel 60 aperture 61,62 Internal flow path 63 Opening 71-74 Through holes

Claims

1. An electro-deionized water production apparatus comprising a frame having a through-opening, an ion exchanger filled in the opening, and a desalination chamber partitioned by a pair of ion exchange membranes arranged to close both ends of the opening, The width direction is defined as the direction perpendicular to the direction of water flow in the desalination chamber and the thickness direction of the frame, and the opening consists of a plurality of mutually separated openings arranged along the width direction, each of which has a width of 120 mm or more and 160 mm or less. The width of the opening is the length of the opening along the width direction, The sum of the widths of the plurality of openings is longer than the length of the openings along the direction of the water flow. An electric deionized water production apparatus in which water flows vertically in the desalination chamber when in use.

2. The electro-deionized water production apparatus according to claim 1, wherein the length of the opening in the direction of water flow in the desalination chamber is longer than the width of the opening.

3. The desalination chamber is further comprising a concentration chamber located adjacent to the desalination chamber via an ion exchange membrane that partitions the desalination chamber, The electrolytic deionized water production apparatus according to claim 1 or 2, wherein the concentration chamber is filled with a mixture of anion exchange resin and cation exchange resin.

4. The electro-deionized water production apparatus according to claim 1 or 2, wherein each of the openings is substantially rectangular and the width of the opening is the length of the shorter side of the opening.

5. The electro-deionized water production apparatus according to claim 1 or 2, wherein the length of the frame along the width direction is 500 mm or more and 1000 mm or less.

6. The electric deionized water production apparatus according to claim 1 or 2, wherein the length of the frame in the width direction is longer than the length of the frame in the vertical direction when the electric deionized water production apparatus is in use.

7. In an electro-deionized water production apparatus, a frame having a roughly rectangular opening that goes through is used for filling ion exchangers, The frame is characterized in that the opening consists of a plurality of openings separated from each other along the long side of the opening, each of the openings has a width of 120 mm or more and 160 mm or less, and the width of the opening is the length of the opening along the direction in which the long side of the opening extends.

8. The opening is a substantially rectangular shape with a short side aligned with the long side of the opening. The frame is provided with a first through-hole that constitutes a channel through which water supplied to the plurality of openings flows, and a second through-hole that constitutes a channel through which water discharged from the plurality of openings flows. A first internal flow path communicating with the first through hole is formed as a slit in the inner wall of each of the multiple openings, on one of the short sides of the opening. The frame according to claim 7, wherein a second internal flow path communicating with the second through hole is formed as a slit in the inner wall of each of the plurality of openings on the other of the short side of the opening.

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