JP2014200698A - Electric deionized water manufacturing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit an operation voltage gain of an electric deionized water manufacturing apparatus.SOLUTION: The provided electric deionized water manufacturing apparatus comprises: a first minor desalinating chamber 12 filled with an anion exchanger; and a second minor desalinating chamber 14 filled with a cation exchanger and an anion exchanger and adjacent to the first minor desalinating chamber 12 via an intermediate ion exchange membrane 13. The first minor desalinating chamber 12 is partitioned by an anion exchange membrane 30 and the intermediate ion exchange membrane 13. The second minor desalinating chamber 14 is partitioned not only by an ion exchange membrane 32 including a cation exchange membrane but also by the intermediate ion exchange membrane 13. Of the anion exchangers filled respectively into the first minor desalinating chamber 12 and second minor desalinating chamber 14, the anion exchanger having the least basicity is included within at least either of the first minor desalinating chamber 12 and second minor desalinating chamber 14. Treatment target water is permeated through the minor desalinating chamber not including the anion exchanger having the least basicity and then through the other minor desalinating chamber.

Description

  The present invention relates to an electrical deionized water production apparatus, and more particularly to a configuration of a desalting treatment unit.

There is known a deionized water production apparatus that removes an ionic component of water to be treated by passing the water to be treated through an ion exchanger. When the ion exchange group of the ion exchanger is saturated and the deionization performance of the ion exchange group is reduced, it is necessary to regenerate the ion exchange group with a chemical such as acid or alkali. That is, the anion and cation adsorbed on ion exchange groups, acid or alkali from the H ⁺ and OH ^- process of replacing a is required. In recent years, in order to eliminate such disadvantages in operation, an electric deionized water production apparatus that does not require regeneration by a drug has been put into practical use.

  The electric deionized water production apparatus executes a process that combines electrophoresis and electrodialysis. A general electric deionized water production apparatus includes a demineralization chamber, a pair of concentration chambers disposed on both sides of the demineralization chamber, an anode chamber disposed outside one of the concentration chambers, and a concentration of the other. And a cathode chamber disposed outside the chamber. The desalination chamber has an anion exchange membrane and a cation exchange membrane facing each other, and a chamber partitioned by the anion exchange membrane and the cation exchange membrane is filled with an ion exchanger (anion exchanger or / and cation exchanger). ing. Hereinafter, the electric deionized water production apparatus may be abbreviated as “deionized water production apparatus”.

In order to produce deionized water (treated water) using a deionized water production apparatus, water to be treated is passed through the demineralization chamber while a DC voltage is applied to the electrodes provided in the anode chamber and the cathode chamber, respectively. Let In the desalting chamber, anion components (Cl ⁻ , CO ₃ ²⁻ , HCO ₃ ⁻ , SiO _2, etc.) in the water to be treated are captured by the anion exchanger. In addition, cation components (Na ⁺ , Ca ²⁺ , Mg ^2+, etc.) in the water to be treated are captured by the cation exchanger. At this time, a dissociation reaction of water occurs on the surfaces of the anion exchanger and cation exchanger, and hydrogen ions and hydroxide ions are generated (H ₂ O → H ⁺ + OH ⁻ ). The ion component captured by the ion exchanger is replaced with the hydrogen ions and hydroxide ions, and is released from the ion exchanger.

  The ion component is electrophoresed to the ion exchange membrane (anion exchange membrane or cation exchange membrane) disposed at the end of the desalting chamber by the action of voltage while being repeatedly captured and released from the ion exchanger. This ionic component is electrodialyzed by an ion exchange membrane and moves to a concentration chamber adjacent to the desalting chamber. The ion component that has moved to the concentration chamber is discharged together with the concentrated water flowing through the concentration chamber. In this way, the water to be treated that has passed through the desalting chamber is deionized.

  In the electric deionized water production apparatus, hydrogen ions and hydroxide ions generated by the water dissociation reaction act as a regenerant for regenerating the ion exchanger. For this reason, a separate drug for regenerating the ion exchanger is basically unnecessary.

  Patent Document 1 and Patent Document 2 disclose an electrodeionized water production apparatus including two small demineralization chambers adjacent to each other through an intermediate ion exchange membrane. The first small desalting chamber is partitioned by a cation exchange membrane and an intermediate ion exchange membrane. The second small desalting chamber is partitioned by the intermediate ion exchange membrane and the anion exchange membrane. The water to be treated is passed through the second small desalting chamber and then through the first small desalting chamber.

  For example, Patent Document 1 describes that a mixture of a cation exchanger and an anion exchanger is filled in a first small desalting chamber, and an anion exchanger is filled in a second small desalting chamber. In Patent Document 2, the second small desalting chamber is filled with an anion exchanger, and the first small desalting chamber is filled with a cation exchanger or an anion exchanger, or a cation exchanger and an anion exchanger stacked on each other. It is described that it is done.

  In such a deionized water production apparatus, anion exchange treatment and / or cation exchange treatment can be performed in a plurality of stages by passing water to be treated through a plurality of small demineralization chambers.

Japanese Patent No. 3385553 Japanese Patent No. 4497388

The inventors of the present application have found that in a deionized water production apparatus that includes at least two small desalting chambers and performs cation exchange treatment or anion exchange treatment in at least two stages, the operating voltage of the apparatus may increase. It was. In particular, when anion treatment is performed in at least two stages, that is, when both the first small desalting chamber and the second small desalting chamber are filled with an anion exchanger, the electrical resistance of the anion exchanger increases. May increase the operating voltage. This increase in the operating voltage is prominent when the water to be treated contains a large amount of an anionic component, particularly silica (SiO ₂ ).

It was found that the increase in operating voltage mainly depends on the following causes. When an anion component is trapped in the anion exchanger in the small desalting chamber, the electrical resistance value of the anion exchanger increases. Many anion components are electrophoresed toward the anode chamber by the action of voltage while being repeatedly captured and released into the ion exchanger, and discharged to the concentration chamber. For this reason, many anion components are not deposited on the anion exchanger, and thus do not contribute much to an increase in electrical resistance. However, anion components that are not ionized in water, such as silica (SiO ₂ ), are not easily affected by voltage and are easily deposited on the ion exchanger. Thereby, the electrical resistance value between an anode chamber and a cathode chamber increases with the operating time of a deionized water manufacturing apparatus. As a result, the operating voltage of the deionized water production apparatus increases.

  In view of this, it is desirable to suppress an increase in operating voltage in the electrical deionized water production apparatus.

  The electric deionized water production apparatus of the present invention includes a first small demineralization chamber filled with an anion exchanger, a first small demineralization chamber and an intermediate ion exchange membrane adjacent to each other, a cation exchanger, And a second small desalting chamber filled with an anion exchanger. The first small desalting chamber is partitioned by an anion exchange membrane and an intermediate ion exchange membrane. The second small desalting chamber is partitioned by an ion exchange membrane including a cation exchange membrane and an intermediate ion exchange membrane. Among the anion exchangers filled in the first small desalting chamber and the second small desalting chamber, the anion exchanger having the lowest basicity is the first small desalting chamber and the second small desalting chamber. It is included in either one. The water to be treated is passed through the small demineralization chamber that does not contain the anion exchanger having the smallest basicity, and then the other small desalting chamber, that is, the anion exchanger having the smallest basicity. Water is passed through the small desalination chamber.

According to the present invention, the anionic component, in particular SiO ₂ can be prevented from increasing driving voltage of the electrodeionization water producing apparatus according to depositing the anion exchanger.

It is a schematic block diagram of the electrical deionized water manufacturing apparatus which concerns on the 1st Embodiment of this invention. It is the schematic which shows the alternative example of a structure of a desalination process part. It is a schematic block diagram of the electrical deionized water manufacturing apparatus which concerns on the 2nd Embodiment of this invention.

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

  FIG. 1 shows a schematic configuration of an electric deionized water production apparatus according to the first embodiment. The electric deionized water production apparatus includes a cathode chamber 24 having a cathode and an anode chamber 26 having an anode. Between the cathode chamber 24 and the anode chamber 26, a desalting treatment unit 10 and concentration chambers 20 and 22 are provided. The concentration chambers 20 and 22 are provided on both sides of the desalting unit 10.

  The cathode of the cathode chamber 24 may be a metal net or plate, for example, a stainless steel net or plate. The anode of the anode chamber 26 may be a metal net or plate. Examples of the material constituting the anode include platinum, palladium, iridium and the like.

  Electrode water is supplied to the cathode chamber 24 and the anode chamber 26 through pipes 54 and 56, respectively. In order to suppress the electrical resistance of the deionized water production apparatus, the cathode chamber 24 and the anode chamber 26 are preferably filled with an ion exchanger. The cathode chamber 24 may be filled with an anion exchanger in a single bed form, and the anode chamber 26 may be filled with a cation exchanger in a single bed form. The cathode chamber 24 and the anode chamber 26 are not limited to this, and may have any configuration.

  The desalination processing unit 10 includes a first small desalting chamber 12, an intermediate ion exchange membrane 13, and a second small desalting chamber 14. The second small desalting chamber 14 is adjacent to the first small desalting chamber 12 through the intermediate ion exchange membrane 13. An anion exchange membrane 30 is provided between the first small desalting chamber 12 and the first concentration chamber 22. Therefore, the first small desalting chamber 12 is partitioned by the anion exchange membrane 30 and the intermediate ion exchange membrane 13.

  A cation exchange membrane 32 is provided between the second small desalting chamber 14 and the second concentration chamber 20. The portion between the second compartment 14b of the second small desalting chamber 14 and the second concentrating chamber 20 may be a bipolar membrane. The bipolar membrane is an ion exchange membrane in which an anion exchange membrane and a cation exchange membrane are bonded and integrated. In this case, the bipolar membrane is preferably arranged so that the anion exchange membrane faces the second small desalting chamber. Further, a portion between the second compartment 14b of the second small desalting chamber 14 and the second concentrating chamber 20 may be installed by overlapping a cation exchange membrane 32 with a bipolar membrane. Also in this case, it is preferable that the anion exchange membrane of the bipolar membrane is disposed so as to face the second small desalting chamber. The second small desalting chamber 14 is partitioned by the ion exchange membrane including the cation exchange membrane 32 and the intermediate ion exchange membrane 13.

  The first small desalting chamber 12 is filled with an anion exchanger. The second small desalting chamber 14 is filled with a cation exchanger and an anion exchanger. In the example shown in FIG. 1, the second small desalting chamber 14 is divided into two compartments 14a and 14b. The lower compartment of FIG. 1 is filled with a cation exchanger. The upper compartment of FIG. 1 is filled with an anion exchanger. The second small desalting chamber 14 may be divided into three or more sections. In this case, it is preferable to arrange the compartment filled with the anion exchanger and the compartment filled with the cation exchanger in order.

  In the electrical deionized water production apparatus according to the present invention, for example, water that has been subjected to a reverse osmosis (RO (Rverse Osmosis)) membrane is supplied to the desalination treatment unit 10 through the pipe 40 as treated water. It is discharged as treated water. In the present embodiment, the water to be treated is supplied to the first small desalination chamber 12, passes through the first small desalination chamber 12, and then passes through the first small desalination chamber 14 through the connecting pipe 41. To the compartment 14a. The treated water that has flowed into the first compartment 14a passes through the second compartment 14b, and is then discharged out of the system as treated water through the discharge pipe 42.

  In the first small desalting chamber 12 and the second small desalting chamber 14, the anion component in the water to be treated is captured by the anion exchanger. The anion component trapped in the anion exchanger is electrophoresed toward the anode chamber 26 by the action of voltage while being repeatedly released and captured, and flows into the first concentration chamber 22.

  In the second small desalting chamber 14, the cation component in the for-treatment water is captured by the cation exchanger. The cation component trapped in the cation exchanger is electrophoresed toward the cathode chamber 24 by the action of voltage while being repeatedly released and captured, and flows into the second concentration chamber 20.

  Concentrated water (a part of the water to be treated in FIG. 1) is passed through the pipes 50 to the respective concentration chambers 20 and 22. The first concentration chamber 22 adjacent to the first small desalting chamber 12 takes in the anion component discharged from the first small desalting chamber 12. The second concentration chamber 20 adjacent to the second small desalting chamber 14 takes in a cation component discharged from the second small desalting chamber 14. The ion components taken into the concentration chambers 20 and 22 are discharged out of the system through the discharge pipe 52 together with the concentrated water.

  Each of the concentrating chambers 20 and 22 may be filled with an anion exchanger in a single bed form in order to suppress the generation of scale. A cation exchange membrane 36 may be provided between the first concentration chamber 22 and the anode chamber 26. An anion exchange membrane 34 may be provided between the second concentration chamber 20 and the cathode chamber 24.

  As the ion exchanger filled in the concentration chambers 20 and 22, the electrode chambers 24 and 26, and the desalting unit 10, a porous body that exhibits an ion exchange function is used in addition to an ion exchange resin.

  Various materials such as an anion exchange membrane, a cation exchange membrane, a bipolar membrane, or a mosaic membrane can be used as the intermediate ion exchange membrane 13. The mosaic membrane is an ion exchange membrane having a structure in which cation exchange group domains and anion exchange group domains are alternately arranged in parallel, and each domain penetrates from the membrane surface to the back surface.

  The intermediate ion exchange membrane 13 may be composed of an anion exchange membrane. The intermediate ion exchange membrane 13 may be an anion exchange membrane in the second small desalting chamber 14 where the portion filled with the anion exchanger and the first small desalting chamber 12 are adjacent. That is, in the example shown in FIG. 1, at least a portion of the intermediate ion exchange membrane 13 adjacent to the second compartment 14b of the second small desalting chamber 14 may be an anion exchange membrane. The other part of the intermediate ion exchange membrane 13 may be an arbitrary ion exchange membrane. The intermediate ion exchange membrane 13 may have any configuration as much as possible.

  The portion of the intermediate ion exchange membrane between the first small desalination chamber 12 and the first compartment 14a of the second small desalination chamber 14 may be a bipolar membrane, or a cation exchange membrane or an anion. A bipolar membrane may be stacked on the exchange membrane. When a bipolar membrane is installed in the cation exchange membrane, the bipolar membrane is arranged on the first small desalination chamber 12 side of the cation exchange membrane so that the anion exchange membrane of the bipolar membrane faces the first small desalination chamber 12. It is preferable that When a bipolar membrane is installed in the anion exchange membrane, the bipolar membrane is arranged such that the cation exchange membrane of the bipolar membrane faces the second small desalination chamber 14 on the second small desalination chamber 14 side of the anion exchange membrane. It is preferable to arrange | position.

  In the example illustrated in FIG. 1, the water to be deionized passes through the first small desalting chamber 12 and then passes through the second small desalting chamber 14. Of the anion exchangers filled in the first small desalting chamber 12 and the second small desalting chamber 14, the anion exchanger having the lowest basicity is the second anion exchanger in the second small desalting chamber. It is contained in the compartment 14b and is not substantially contained in the first small desalting chamber 12. Therefore, the water to be treated is passed through the small desalting chamber (first small desalting chamber 12) that does not contain the anion exchanger having the smallest basicity, and then the other small desalting chamber. Water is passed through (second small desalination chamber 14). Note that the first small desalting chamber 12 is allowed to contain an anion exchanger having the smallest basicity in such a small amount that it hardly contributes to anion exchange.

  In the small desalting chamber (second small desalting chamber 14) containing the anion exchanger having the lowest basicity, the other small desalting chamber (first small desalting chamber 12) is mainly used. It is preferred that the anion exchanger having a basicity smaller than that of the packed anion exchanger preferably occupies a majority, more preferably substantially all.

Anion exchangers are, in descending order of basicity, type I strongly basic anion exchange resin (styrene), type I strongly basic anion exchange resin (acrylic), type II strongly basic anion exchange resin (styrene). Type), medium basic anion exchange resin (acrylic), weak basic anion exchange resin (acrylic), weak basic anion exchange resin (styrene), and the like. That is, the basicity of type I strongly basic anion exchange resin (styrene) is the largest.

Therefore, when the first small desalting chamber 12 is filled with the type I strong basic anion exchange resin, the second small desalting chamber 14 has the type II strong basic anion exchange resin, the medium basic anion. At least one of an exchange resin and a weakly basic anion exchange resin may be filled. In addition, when the first small desalting chamber 12 is filled with a type I strong basic anion exchange resin and a type II strong basic anion exchange resin, the second small desalting chamber 14 has a weak basic anion exchange. What is necessary is just to fill with resin. At this time, a part of the anion exchanger in the second small desalting chamber 14 may be an I-type strongly basic anion exchange resin or an II-type strongly basic anion exchange resin.

Next, the desalination process of the to-be-processed water in the desalination process part 10 is demonstrated. In the first small desalting chamber 12, components (Cl ⁻ , CO ₃ ²⁻ , HCO ₃ ^−, etc.) that are mainly easily ionized among the anionic components in the water to be treated are captured by the anion exchanger, and the concentration chamber 22. Is discharged. Since electrical neutrality is maintained in water, hydroxide ions equivalent to the removed anion component are released into the water to be treated. Since ion exchange is an equilibrium reaction, when the concentration of hydroxide ions increases, the desalting property of the anion exchanger, that is, the ability to capture anion components in the water to be treated decreases.

  As a result, all the anion components in the for-treatment water cannot be removed, and the anion components remain in the for-treatment water. Most of the anion components remaining in the for-treatment water that has passed through the first small desalting chamber 12 are considered to be components that are difficult to ionize or components that are not ionized.

  The treated water that has passed through the first small desalting chamber 12 is passed through the first compartment 14 a of the second small desalting chamber 14. In the first compartment 14a, the cation component in the water to be treated is captured by the cation exchanger and discharged to the concentration chamber 20. At this time, an equivalent amount of hydrogen ions to the discharged cation component is released into the water to be treated. Most of these hydrogen ions are combined with hydroxide ions released into the water to be treated in the first small desalting chamber 12 to form electrically neutral water molecules.

  The treated water that has passed through the first compartment 14 a of the second small desalting chamber 14 is passed through the second compartment 14 b of the second small desalting chamber 14. In the second compartment 14b, the anion component remaining in the for-treatment water is captured by the anion exchanger. The anion component trapped in the anion exchanger undergoes an action of voltage, electrophoreses toward the anode chamber 26, and is discharged to the concentration chamber 22 through the first small desalting chamber 12.

  Here, the anion exchanger having the smallest basicity is included in the second compartment 14b of the second small desalting chamber 14, but is substantially included in the first small desalting chamber 12. Not. That is, the anion trapping capacity of the anion exchanger in the second compartment 14b of the second small desalting chamber 14 is lower than the anion trapping capacity of the anion exchanger in the first small desalting chamber 12. Therefore, the anion exchanger in the second compartment 14b mainly captures anion components ionized in the water to be treated, and does not trap anion components that are not ionized in the water to be treated. As a result, the anion component ionized in the treated water is discharged to the concentration chamber 22 through the first and second small desalting chambers 12 and 14, and the anion component not ionized in the treated water passes through the discharge pipe 42. It remains in the discharged treated water.

  Thus, in the small desalination chamber downstream in the direction of water flow of the water to be treated, anion components that are not ionized in the water to be treated are reduced by reducing the desalting ability of the anion exchanger, that is, the ion exchange capacity. It can suppress that it is trapped by. Therefore, the anion component that is not ionized in the water to be treated, particularly silica, is suppressed from being deposited on the anion exchanger in the small desalting chambers 12 and 14. As a result, an increase in operating voltage accompanying an increase in the electrical resistance value of the anion exchanger can be suppressed.

  In the treated water that has passed through the second small desalting chamber 14, an anion component that is not ionized remains. However, anion components that do not ionize have little effect on the conductivity of water. Therefore, depending on the use of the treated water, an anion component that is not ionized may remain.

  In the configuration shown in FIG. 1, the water to be treated is passed through the first small desalting chamber 12 and then through the second small desalting chamber 14. Instead of this configuration, the water to be treated may be passed to the first small desalting chamber 12 after being passed to the second small desalting chamber 14. In this case, the anion exchanger having the smallest basicity is not filled in the second small desalting chamber 14 (second compartment 14a), but is filled in the first small desalting chamber 12. Thus, after the treated water is passed through the small desalting chamber (second small desalting chamber 14) that does not contain the anion exchanger having the smallest basicity, the other small desalting is performed. Water is passed through the chamber (first small desalination chamber 12). Even in this case, an increase in the operating voltage accompanying an increase in the electrical resistance value of the anion exchanger can be suppressed by reducing the anion exchange capacity in the small desalting chamber on the downstream side.

  In this way, the direction of water to be treated may be either direction. However, considering the advantage of easily removing the cation component, it is better that the water to be treated is passed through the first small desalting chamber 12 and then the second small desalting chamber 14. If a large amount of anion components ionized when supplementing the cation component to the cation exchanger remain, an amount of hydrogen ions corresponding to the amount of the remaining anion components is generated in the water to be treated, and the concentration of hydrogen ions increases. become. Therefore, the desalting property of the cation exchanger, that is, the ability to capture cation components in the water to be treated is lowered. In the apparatus of the present invention, the second small desalting chamber 14 is filled with a cation exchanger, whereas the first small desalting chamber is not filled with a cation exchanger. The anion component can be efficiently removed by passing the water to be treated through the small desalting chamber 12. Thus, as many anion components as possible can be removed in the first small desalting chamber 12, so that the cation components can be efficiently removed by the cation exchanger in the second small desalting chamber 14.

  FIG. 2 shows an alternative example of the configuration of the desalting unit 10. The desalination processing unit 10 includes a first small desalting chamber 12, an intermediate ion exchanger 13, and a second small desalting chamber 14. The second small desalting chamber 14 is adjacent to the first small desalting chamber 12 via the intermediate ion exchanger 13. The first small desalting chamber 12 is filled with an anion exchanger. The second small desalting chamber 14 is filled with a cation exchanger and an anion exchanger. However, the second small desalting chamber 14 is not divided, and the cation exchanger and the anion exchanger are mixed (mixed bed). In addition, as above-mentioned, the water flow direction of to-be-processed water may be any direction.

  Of the anion exchangers filled in the first small desalting chamber 12 and the second small desalting chamber 14, the anion exchanger having the lowest basicity is the first small desalting chamber 12 and the second small desalting chamber 12. It is contained in either one of the small desalting chambers 14. The treated water is passed through the small desalting chamber (the first small desalting chamber 12 in the direction of water flow shown in FIG. 2) that does not contain the anion exchanger having the smallest basicity, Are passed through a small desalting chamber (second small desalting chamber 14 in the direction of water flow shown in FIG. 2).

  When the second small desalting chamber 14 is filled with an anion exchanger and a cation exchanger, the intermediate ion exchange membrane 14 is preferably an anion exchange membrane.

  FIG. 3 shows a schematic configuration of an electric deionized water production apparatus according to the second embodiment. The deionized water production apparatus includes a cathode chamber 24, an anode chamber 26, concentration chambers 20, 22, 60 and 62, and a plurality of demineralization processing units 10. In FIG. 3, three demineralization treatment units 10 are shown, but the deionized water production apparatus may include two or more demineralization treatment units 10. Concentration chambers 60 and 62 are provided between the desalting units 10.

  The cathode chamber 24, the anode chamber 26, and the concentration chambers 20, 22, 60, and 62 may have the same configuration as that described in the first embodiment. Moreover, the desalination processing unit 10 has the same configuration as that described in the first embodiment, and includes a pair of small desalting chambers 12 and 14 that are adjacent to each other through the intermediate ion exchange membrane 13. Yes.

  The water to be treated is passed through the first small desalting chamber 12 of each desalting treatment unit 10. In each desalting treatment unit 10, the water to be treated that has passed through the first small desalting chamber 12 is passed to the second small desalting chamber 14. However, as described in the first embodiment, the water to be treated may be passed through the first small desalting chamber 12 after passing through the second small desalting chamber 14. The flow direction of the water to be treated may be the same for all the desalting treatment units 10 or may be different for each desalting treatment unit 10.

In each desalting unit 10, the anion exchanger having the lowest basicity is included in either the first small desalting chamber 12 or the second small desalting chamber 14. Then, the water to be treated is passed through the other small desalting chamber after passing through the smaller desalting chamber that does not contain the anion exchanger having the smallest basicity. As a result, as in the first embodiment, it is possible to suppress an increase in operating voltage caused by deposition of an anion component that is not ionized, particularly SiO _2, on the anion exchanger.

  Moreover, the structure of all the desalination process parts 10 may mutually be the same, and may mutually differ. For example, any of the plurality of desalting treatment units 10 may have the configuration shown in FIG.

  Next, the results of measuring the operating voltage of the deionized water production apparatus and the specific resistance value of the treated water using the deionized water production apparatus having the configuration shown in FIG. 3 will be described.

  The dimensions of the cathode chamber 24 and the anode chamber 26 were 300 mm × 80 mm × 4 mm. The cathode chamber 24 was filled with an anion exchange resin. The anode chamber 26 was filled with a cation exchange resin. The dimensions of the concentrating chambers 20, 22, 60, 62 were 300 mm × 80 mm × 5 mm. The concentration chambers 20, 22, 60, 62 were filled with an anion exchange resin.

  The dimensions of the first small desalting chamber 12 and the second small desalting chamber 14 of each desalting treatment unit 10 were 300 mm × 80 mm × 10 mm. Here, in the second small desalting chamber 14, the volume ratio of the first compartment 14a and the second compartment 14b was 1: 1. The intermediate ion exchange membrane 13 was an anion exchange membrane.

  The treated water was softened and passed through the RO membrane, and then passed from the first small desalting chamber 12 to the second small desalting chamber 14. The flow rate of the water to be treated was 180 [L / h]. The flow rate of concentrated water is 30 [L / h], and the flow rate of electrode water is 10 [L / h]. The conductivity of the water to be treated before the desalting treatment was 10 ± 1 [μS / cm]. The carbonate concentration of the water to be treated before the desalting treatment was about 15 [mg / L], and the silica concentration of the water to be treated before the desalting treatment was about 1 [mg / L]. The current value applied between the cathode chamber 24 and the anode chamber 26 was 1.1 [A].

As an example, the first small desalting chamber 12 of each desalting unit 10 was filled with a single bed of type I strongly basic anion exchange resin. In the second small desalting chamber 14 of each desalting unit 10, the first compartment 14a was filled with a cation exchange resin, and the second compartment 14b was filled with a type II strong basic anion exchange resin.

As a comparative example, the second compartment 14b of the second small desalting chamber 14 was filled with the same type I strongly basic anion exchange resin as the anion exchanger filled in the first small desalting chamber 12. Conditions other than the type of anion exchanger filled in the second compartment 14b of the second small desalting chamber 14 are the same in the examples and the comparative examples.

  About both the Example and the comparative example, the deionized water manufacturing apparatus was operated for 1000 hours, and the operating voltage and the quality of the treated water, here, the specific resistance value of the treated water were measured. The results of this measurement are shown in Table 1 below.

  There is almost no difference in the specific resistance value of the treated water between the examples and the comparative examples. This means that the quality of the water to be treated is hardly changed.

On the other hand, the operation voltage of the comparative example is significantly larger than the operation voltage of the example. This is because the type II strong basic anion exchange resin used in the second small desalting chamber 14 of the example is lower than the basicity of the type I strong basic anion exchange resin. Conceivable.

  Although the preferred embodiments of the present invention have been presented and described in detail above, the present invention is not limited to the above-described embodiments, and it is understood that various changes and modifications can be made without departing from the gist. I want to be.

DESCRIPTION OF SYMBOLS 10 Desalination process part 12 1st small desalting chamber 13 Intermediate | middle ion exchange membrane 14 2nd small desalting chamber 14a 1st division 14b 2nd division 20, 22, 60, 62 Concentration chamber 24 Cathode chamber 26 Anode Chamber 30 Anion exchange membrane 32 Cation exchange membrane 41 Connecting tube

Claims (4)

A first small desalting chamber partitioned by an anion exchange membrane and an intermediate ion exchange membrane and filled with an anion exchanger;
Adjacent to the first small desalting chamber through an intermediate ion exchange membrane, partitioned by an ion exchange membrane including a cation exchange membrane and the intermediate ion exchange membrane, and filled with a cation exchanger and an anion exchanger 2 small desalting chambers,
Among the anion exchangers filled in the first small desalting chamber and the second small desalting chamber, the anion exchanger having the lowest basicity is the first small desalting chamber and the second small desalting chamber. Included in one of the small desalination chambers of
Electrically deionized water in which the water to be treated is passed through the other small desalting chamber after passing through the small desalting chamber that does not contain the anion exchanger having the smallest basicity. manufacturing device. The anion exchanger having the smallest basicity is filled in the second small desalting chamber,
The electric deionized water production apparatus according to claim 1, wherein the water to be treated is passed through the first small desalting chamber and then passed through the second small desalting chamber. Of the first small desalting chamber and the second small desalting chamber, the anion exchanger filled in the small desalting chamber to be previously passed is an I-type strongly basic anion exchange resin. ,
Among the first small desalting chamber and the second small desalting chamber, the anion exchanger filled in the small desalting chamber to be passed later is a type II strongly basic anion exchange resin, a medium base The electric deionized water production apparatus according to claim 1 or 2, which is at least one of a basic anion exchange resin and a weakly basic anion exchange resin. A first concentrating chamber provided on the opposite side of the second small desalting chamber via the first small desalting chamber;
A second concentrating chamber provided on the opposite side to the first small desalting chamber via the second small desalting chamber;
An anode provided on the opposite side of the first small desalination chamber via the first concentration chamber;
The electric deionization according to any one of claims 1 to 3, further comprising a cathode provided on the opposite side of the second small desalting chamber through the second concentration chamber. Water production equipment.

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