JP2003024947A - Electrodialytic cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrodialytic cell capable of keeping the independence of a deionizing chamber and a concentration chamber by a simple method and capable of achieving efficient deionization. SOLUTION: Anion exchange membranes 5 and cation exchange membranes 4 are alternately arranged and spacers 7 forming spacer space parts 16a and 16b are arranged between the anion exchange membranes 5 and the cation exchange membranes 4 to form the deionizing chambers and the concentration chambers. Comb tooth-like ribs 18 are alternately arranged to the spacer space parts 16a and 16b of the spacers 7 so that the comb tooth-like ribs 18 of the spacer space parts 16a and 16b adjacent to each other through the anion exchange membranes 5 and the cation exchange membranes 4 cross each other almost at a right angle. By this constitution, the distances between the ion exchange membranes opposed to each other through the spacer space parts 16a and 16b can be kept constant and, therefore, stable deionizing capacity can be held.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electrochemical method for removing cations such as sodium ions and calcium ions, and anions such as chloride ions and sulfate ions, which are mainly contained in water such as tap water. The present invention relates to an electrodialysis tank of a water treatment device.

[0002]

2. Description of the Related Art An electrodialysis method comprising an ion exchange membrane and an electric field applying means is used for desalination of seawater and production of salt from seawater. In addition, the electrodialysis method, which does not require a regeneration operation, is widely used for the production of ion-exchanged water and ultrapure water used in semiconductor manufacturing and the like.

In the electrodialysis method, a cation exchange membrane and an anion exchange membrane are alternately arranged in an electrodialysis tank in which a deionization chamber and a concentration chamber are formed, and a voltage is applied while flowing water to be treated into the deionization chamber. Deionized water is produced by applying electric electrodialysis, and the ion exchange membrane is self-regenerated by using acid and alkali by water dissociation in the deionization chamber. In these devices, many contrivances have been made in materials and configurations in order to improve deionization efficiency and reliability.

FIG. 6 shows a diagram of a spacer of a conventional electrodialysis tank. Spaces are formed in the deionization chamber and the concentration chamber by the gaskets 101 and 102 sandwiched between the cation exchange membrane and the anion exchange membrane, and the mesh spacers 103 and 104 are arranged in this space portion. It is common. Regarding the integration of the spacers 103 and 104 and the gaskets 101 and 102, various proposals have been made, for example, in JP-A-2-290227 and JP-A-58-112006.

[0005]

In order to increase the efficiency of the electrodialysis cell, it is necessary to reduce the distance between the cation exchange membrane and the anion exchange membrane, that is, to reduce the deionization chamber and the concentration chamber, and stack them in multiple layers. desirable. Therefore, the structure of the above-mentioned gasket and spacer becomes important. The gaskets and spacers of conventional electrodialysis tanks are mainly composed of a combination of a polymer elastomer and a polymer network, and various patents have been applied for the connection method. A structure that replaces the mesh-like body by forming protrusions from a part of the gasket, which is a polymer elastomer, is generally known. Since this projection directly reduces the electrode area, it is desirable that the total area is small. It is possible to reduce the total area by reducing the number of protrusions, but in this case, the ion exchange membrane facing the gasket is deformed and partially contacts, and the current is concentrated and burned at this part. An accident occurs. In order to prevent this, it is effective to arrange the protrusions densely in the deionization chamber and reduce the width of the protrusions. However, in this case, there is a possibility that the projecting portion will shift during assembly and will not be fixed properly.

Further, there is a problem in the arrangement of spacers in the water guiding portion that connects the space portion of the deionization chamber to the water inlet pipe and the water discharge pipe. Although this part is a narrow passage, when the pressure in the concentration chambers (or deionization chambers) on both sides of the passage of the deionization chamber (or concentration chamber) becomes high, the ion exchange membrane deforms, and A phenomenon in which concentrated water (or diluted water) flows back from the membrane water passage to the deionization chamber (or concentration chamber) is likely to occur.

Therefore, it is an object of the present invention to provide an electrodialysis tank capable of maintaining the independence of the deionization chamber and the concentration chamber by a simple method and achieving efficient deionization.

[0008]

In order to solve the above-mentioned problems, the present invention has an anion exchange membrane and a cation exchange membrane alternately arranged, and a space portion is provided between the anion exchange membrane and the cation exchange membrane. In a stacked electrodialysis tank with deionization chamber and concentration chamber with spacers formed, the comb-teeth ribs are alternately arranged in the space of the spacers, and anion exchange membrane or cation exchange membrane is used. It is characterized in that comb-shaped ribs of spacers adjacent to each other via the film are arranged so as to be substantially orthogonal to each other.

According to the present invention, it is possible to obtain an electrodialysis tank which can secure the space of the deionization chamber and the concentration chamber by a simple method, maintain their independence, and achieve efficient deionization.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the invention described in claim 1, an anion exchange membrane and a cation exchange membrane are alternately arranged, and a space is formed between the anion exchange membrane and the cation exchange membrane. In a stacked electrodialysis tank in which a spacer is arranged to form a deionization chamber and a concentration chamber, comb-shaped ribs are alternately arranged in the space of the spacer and an anion exchange membrane or a cation exchange membrane is interposed. It is an electrodialysis tank characterized in that comb-shaped ribs of adjacent spacers are arranged so as to be substantially orthogonal to each other, and the distance between the ion-exchange membranes facing each other through the spacers can be kept constant, which is stable. Deionization performance can be maintained.

According to a second aspect of the present invention, there is provided a water channel formed by penetrating the outer frame portion of the anion exchange membrane, the cation exchange membrane and the spacer in the stacking direction, and the spacer connects the water channel and the space portion. The electrodialysis tank according to claim 1, wherein a comb-teeth-shaped rib parallel to the water passage is provided in the water passage for adjoining, and adjacent to each other via an ion exchange membrane, which is likely to occur near the water passage. Flow of concentrated water from the concentration chamber, or
Since the dilution water can be prevented from flowing out of the deionization chamber, stable deionization performance can be maintained.

The invention according to claim 3 is the electrodialysis tank according to claim 1 or 2, characterized in that the material of the spacer is a polymer elastomer, and the invention corresponds to a conventional gasket and spacer. Since the spacer can be formed of a single sheet-shaped member, the configuration can be simplified and the assemblability is improved. In addition, even when laminated in multiple layers, it is possible to eliminate the risk of water leakage.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic view showing the structure of an electrodialysis tank according to an embodiment of the present invention, showing a state in which an ion exchange membrane, spacers, electrodes and an outer frame are all laminated.

In FIG. 1, the electrodialysis tank 1 includes an electrode plate 2
A cation exchange membrane 4 (for example, K501 (trade name) manufactured by Asahi Kasei Co., Ltd.) and a spacer 6 (for example, thermoplastic resin polyurethane manufactured by Nippon Bulker Co., Ltd.) between the two polar chamber cells 14 and 15 in which the electrode plate 3 and the electrode plate 3 are arranged. Elastomer, trade name; tough tan, anion exchange membrane 5 (for example, Asahi Kasei Corp., A50)
1 (commercial name)) and a spacer 7 (for example, Nippon Bulker Co., Ltd., thermoplastic polyurethane elastomer, trade name; Tuffletan) are repeatedly laminated as a set and are fixed by tightening from the outside. The thinner the spacers 6 and 7, the more efficiently electrodialysis can be performed. However, if the spacers 6 and 7 are too thin, the pressure at the time of water flow increases and a large flow rate cannot be flowed, so a thickness of about 0.5 mm to 2 mm is appropriate. Is.

Water is passed through the electrodialysis tank 1 by introducing water to be treated such as brine or hard water from the deionization chamber water inlet 8 provided in the outer frame portion of the laminated portion, and the spacers 7 are alternately arranged. It is performed by uniformly distributing the deionized water to the formed deionization chambers, collecting the treated water discharged from each water discharge port, and discharging the deionized water from the water discharge port 11. On the other hand, the same treated water as the deionization chamber is introduced into the concentration chambers which are alternately arranged and formed by the spacers 6 through the concentration chamber inlet 9 and similarly distributed to the concentration chambers to concentrate the ionic components. The concentrated water discharged from each water outlet is collected and discharged from the concentrated water outlet 12. Also, the polar chamber cell 1
The same water to be treated as in the deionization chamber is supplied to 4 and 15 as well
Water is introduced from 0, electrolyzed, and then discharged from the polar water discharge port 13. This discharged water may be mixed with concentrated water to be discharged, but it is separated separately and the discharged water from the polar chamber cell 14 is used as cathode water (alkaline water), and the discharged water from the polar chamber cell 15 is used as anode water (acidic water). It can also be used as water).

Next, the water passage will be described with reference to FIGS. 2A is a plan view of the spacer 6 of the electrodialysis tank according to the embodiment of the present invention, and FIG.
FIG. 3 is a detailed view of a portion A of FIG. 3, FIG. 3 is a plan view of the spacer 7 of the electrodialysis tank according to the embodiment of the present invention, and FIG. 4 is a spacer 6 of the electrodialysis tank according to the embodiment of the present invention, and cation exchange. 3 is a perspective view showing a laminated state of a membrane 4 and an anion exchange membrane 5. FIG.

The spacer 6 shown in FIG. 2 is hollow and
In order to avoid contact between the ion-exchange membranes, a spacer space portion 16a having a shape in which a comb-shaped rib 18 partially protrudes from the outer frame portion toward the hollow portion is provided. Spacer space 16a
Is a spacer water passage 1 for use as a water inlet and a water outlet.
7a are provided at opposing positions, and the comb-shaped ribs 18 are alternately arranged so as to cross a straight line connecting the water inlet and the water outlet.

The spacer 7 shown in FIG. 3 is hollow and
In order to avoid contact between the ion-exchange membranes, a spacer space portion 16b having a shape in which the comb-shaped ribs 19 are partially projected from the outer frame portion toward the hollow portion is provided. Spacer space 16b
Is a spacer water passage 1 for use as a water inlet and a water outlet.
7b are provided at opposing positions, and the comb-shaped ribs 19 are alternately arranged so as to cross a straight line connecting the water inlet and the water outlet. At this time, the protrusion of the comb-teeth rib 19 of the spacer 7 is formed at a position substantially perpendicular to the comb-teeth rib 18 of the spacer 6.

As shown in FIG. 4, the spacer 7 has a spacer water passage 17b opened from the spacer space 16b toward the outer frame portion, and the right-angled communication hole 20 is connected to the tip of the spacer water passage 17b. Structure. The right-angled communication hole 20 penetrates the laminated body of the anion exchange membrane 5, the spacer 6, and the cation exchange membrane 4 and is arranged in the outer frame portion, and the spacer space portion of the spacer 7 passes through the spacer water passage 17b. It is open toward 16b and closed toward the spacer space 16a of the spacer 6. With such a structure in which the right-angled communication holes 20 alternately have the opening portions and the closed portions repeatedly, an inflow water channel that allows water to pass through the spacer space portion 16b that performs all deionization is formed. The water discharge channel is configured such that the spacer water channel 17b, which is arranged at a position substantially facing the water channel and the spacer space portion 16b, is connected to the right-angled communication hole 20 similarly to the water channel.

On the other hand, the spacer 6 has a spacer space 16
Spacer water passage 17a opened from a toward the outer frame
This spacer water passage 17a is connected to the right-angled communication hole 21 arranged at a position different from the water inlet passage on the deionization side. The right-angled communication hole 21 is not connected to the spacer space portion 16b of the spacer 7. In the water discharge channel of the concentrating portion, the spacer water channel 17a arranged at a position substantially facing the water channel and the spacer space 16a has a right-angled communication hole 21.
It is configured to be connected to. On the other hand, the electrode water is the electrode plate 2,
The spacer 6, the anion exchange membrane 5 or the cation exchange membrane 4, the spacer 7, and the electrode plate 3 are arranged so as to enter the water and discharge from the other end. Anode water and cathode water are obtained depending on the polarity of the electrodes, but if this is not used, they may be collectively drained.

The water to be treated, which has been passed through the spacer space 16b, which serves as a deionization portion between the pair of electrode plates 2 and 3, is deionized by applying a DC voltage to the electrode plates 2 and 3, and is collected. It is used for water discharge. On the other hand, regarding the concentrated water, the water to be treated that has been passed through the spacer space 16a, which is a concentrating portion that is also alternately arranged with the deionization portion, applies a DC voltage to the electrode plates 2 and 3, On the contrary, it is concentrated, collected, discharged, and treated as wastewater.

Here, the role of the spacers 6 and 7 will be described in detail.

FIG. 5 is a perspective view showing a state in which the spacer 6 and the spacer 7 are superposed on each other.

As shown in FIG. 5, the spacer space portion 16
Comb-shaped ribs 18 arranged toward the spaces a and 16b
Since the spacers 6 and 7 are arranged substantially at right angles, they surely overlap each other at their intersections, and the anion exchange membrane 5 and the cation exchange membrane 4 arranged between the spacers 6 and 7 are surely suppressed. , Can be fixed.

Further, as shown in FIG. 1B, a comb-teeth-shaped rib 19 parallel to the spacer water passage 17a is arranged in the spacer water passage 17a of the hole connected to the right-angled communication hole 21. The spacer water passage 17a is fixed in a state where the spacer 7, the anion exchange membrane 5 and the cation exchange membrane 4 are laminated and pressed from both sides. However, since the spacer water passage 17a is hollow, it cannot be pressed on one side. If the pressure in the concentrating chamber (or deionizing chamber) adjacent to each other through the anion exchange membrane 5 and the cation exchange membrane 4 increases as it is, the concentrated water (or the concentrating chamber) can be easily concentrated in the deionization chamber (or the concentrating chamber). Deionized water) will leak. In the conventional electrodialysis tank, gaskets 101 and 102 are used.
Reticulated spacer 10 arranged in the space formed by
Although the device for stretching 3, 104 to this area is prevented so as to prevent the membrane from being deformed, the present invention can achieve this object without using a different material such as a mesh spacer. By providing the comb-teeth-shaped ribs in parallel along the spacer water passage, it is possible to overcome the leakage problem with the same material.

[0027]

In the electrodialysis tank of the present invention, the conventional spacer and the spacer corresponding to the gasket are made of the same material, and the comb-teeth ribs formed in the spacer space are substantially orthogonal to each other in the adjacent chambers. Since they are arranged in such a manner, stable electrodialysis can be realized without deformation or movement of the ion exchange membrane. In addition, by placing comb-shaped ribs made of the same material as the spacer in parallel with the water passage on the water passage that connects the right-angled communication hole of the spacer and the space, it is possible to completely mix the concentrated water and deionized water. It has the excellent feature that stable deionized water can be obtained because it can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of an electrodialysis tank according to an embodiment of the present invention.

FIG. 2A is a plan view of a spacer of an electrodialysis tank according to an embodiment of the present invention, and FIG. 2B is a detailed view of part A of FIG.

FIG. 3 is a plan view of a spacer of the electrodialysis tank according to the embodiment of the present invention.

FIG. 4 is a perspective view showing a laminated state of a spacer, a cation exchange membrane and an anion exchange membrane of an electrodialysis tank according to an embodiment of the present invention.

5 is a perspective view showing a state in which the spacers of FIGS. 2 and 3 are overlapped with each other.

FIG. 6 is a diagram of a spacer of a conventional electrodialysis tank.

[Explanation of symbols]

1 electrodialysis tank 2,3 electrode plate 4 Cation exchange membrane 5 Anion exchange membrane 6,7 spacer 8 Deionization room water inlet 9 Concentration room water inlet 10 Polar room water inlet 11 Deionized water spout 12 Concentrated water spout 13 Polar water spout 14 Polar cell 15 polar cell 16a, 16b Spacer space portion 17a, 17b spacer water passage 18,19 Comb-shaped rib 20, 21 Right angle communication hole

Claims (3)

[Claims] 1. Anion-exchange membrane and cation-exchange membrane are alternately arranged, and a spacer having a space is formed between the anion-exchange membrane and the cation-exchange membrane, and a deionization chamber and In a laminated electrodialysis tank having a concentrating chamber, alternating comb-shaped ribs are arranged in the space of the spacer,
An electrodialysis tank characterized in that comb-shaped ribs of the spacers adjacent to each other via the anion exchange membrane or the cation exchange membrane are arranged so as to be substantially orthogonal to each other. 2. A water channel formed by penetrating an outer frame portion of the anion exchange membrane, the cation exchange membrane, and a spacer in a stacking direction, wherein the spacer is a passage for connecting the water channel and the space portion. The electrodialysis tank according to claim 1, wherein a comb tooth-shaped rib parallel to the water passage is provided in the water passage. 3. The electrodialysis tank according to claim 1, wherein the spacer material is a polymer elastomer.