JP6994351B2 - Electric deionized water production equipment - Google Patents

Description

The present invention relates to an electric deionized water production apparatus.

Conventionally, as an apparatus for producing deionized water, an apparatus for deionizing by passing water to be treated through an ion exchanger is known. In such a device, when the ion exchange group of the ion exchanger is saturated and the desalting performance is deteriorated, it is necessary to regenerate the ion exchanger with a chemical such as an acid or an alkali. Specifically, it is necessary to replace the anions and cations adsorbed on the ion exchange group with H ⁺ derived from an acid and OH ⁻ derived from an alkali, respectively. In recent years, an electric deionized water production device that does not require regeneration with a chemical has been put into practical use for the purpose of eliminating such disadvantages in operation.

The electric deionized water production device is a device that combines electrophoresis and electrodialysis. A general electric deionized water production device includes a desalting chamber, a pair of concentrating chambers arranged on both sides of the desalting chamber, an anode chamber arranged outside one of the concentrating chambers, and the other concentrating chamber. It has a cathode chamber arranged outside the chamber. The desalting chamber is adjacent to the concentration chambers on both sides via the anion exchange membrane and the cation exchange membrane, respectively, and the ion exchanger (at least one of the anion exchange membrane and the cation exchange membrane) filled between these ion exchange membranes. have.

In order to produce deionized water (treated water) with the electric deionized water production device configured as described above, deionization is performed with a DC voltage applied between the electrodes provided in the anode chamber and the cathode chamber, respectively. Pass the water to be treated through the salt chamber. In the desalting chamber, the anion components (Cl ⁻ , CO ^3-2- , HCO ₃ ⁻ , SiO ₂ etc.) in the water to be treated are adsorbed _on the anion exchanger, and the cationic components (Na ⁺ , Ca ²⁺ , Mg) in the water to be treated are adsorbed. ²⁺ etc.) is adsorbed on the cation exchanger, and the water to be treated is deionized (desalted). Further, in the desalting chamber, a dissociation reaction of water occurs at the interface between the anion exchanger and the cation exchanger, and hydrogen ions and hydroxide ions are generated (H ₂ O → H ⁺ + OH ⁻ ). The anion component adsorbed on the anion exchanger is exchanged with the hydroxide ion and released from the anion exchanger, and the cation component adsorbed on the cation exchanger is exchanged with the hydrogen ion and released from the cation exchanger. do. The released anion component is electrophoresed to the anion exchange membrane through the anion exchanger, electrodialyzed by the cation exchange membrane, and transferred to the concentration chamber. On the other hand, the liberated cation component is electrophoresed to the cation exchange membrane through the cation exchanger, electrodialyzed by the cation exchange membrane, and moved to the concentration chamber. The ionic components thus moved to the concentration chamber are discharged by the concentrated water flowing through the concentration chamber.

As described above, in the electric deionized water production apparatus, hydrogen ions and hydroxide ions continuously act as a regenerating agent (acid or alkali) for regenerating the ion exchanger, so that the ion exchanger using a drug can be used. Reproduction is basically unnecessary, and as a result, continuous operation becomes possible.

By the way, in order to obtain treated water having a high resistivity value and good water quality, a multi-stage treatment is performed in which at least one of the removal of the cation component by the cation exchanger and the removal of the anion component by the anion exchanger are performed twice or more. Is effective. For example, when the anion component is removed and the cation component is removed once in this order, the anion component in the water to be treated is first removed, but the electrical neutrality is maintained in the water. The removed anion component and the equivalent amount of hydroxide ion are released into the water to be treated. Therefore, hydroxide ions become excessive in the water to be treated from which the anion component has been removed to some extent, and it becomes difficult for the anion component (Cl ⁻ , CO ^3-2- , HCO ₃ ⁻ , etc.) to be adsorbed _on the anion exchanger. As a result, the anion exchanger cannot sufficiently remove the anion component, and the unremoved anion component leaks into the treated water. In such a case, by removing the cation component with the cation exchanger and then removing the anion component with the anion exchanger again, it is possible to suppress the leakage of the anion component into the treated water.

In Patent Document 1, the water to be treated is passed through the first anion removing desalting chamber, the cation removing desalting chamber, and the second anion removing desalting chamber in this order, and the above-mentioned multi-stage treatment is executed. The electric deionized water production apparatus to be used is disclosed.

Japanese Unexamined Patent Publication No. 2013-39510

However, the electric deionized water production apparatus described in Patent Document 1 is mainly intended to suppress scale generation in a concentration chamber. Therefore, in order to reduce the amount of silica discharged from the first anion removing desalting chamber to the concentration chamber, silica (SiO ₂ ) is not removed as much as possible in the first anion removing desalting chamber. .. In such a configuration, anion components (Cl ⁻ , CO ₃ ^2- , HCO _3- ^, etc.), which are more selective than silica, inevitably leak from the first anion removal desalting chamber, and as a result, As shown below, it becomes difficult to obtain treated water in which the concentration of weakly acidic anionic components (for example, silica and boron) is sufficiently reduced.

When the water to be treated containing an anionic component flows into the desalination chamber for removing cations, hydrogen ions equivalent to the anionic component are generated by electrolysis of the water in the desalting chamber for removing cations. If this hydrogen ion becomes excessive, it will be adsorbed on the cation exchanger and its cation removal performance will be deteriorated, and the cation component in the water to be treated cannot be sufficiently removed. Then, when the cation component leaks from the cation removal desalting chamber and flows into the second anion removing desalting chamber, the second anion removing desalting chamber uses the same principle as the above-mentioned generation of hydrogen ions. When hydroxide ions are generated and become excessive, the anion removal performance of the anion exchanger is deteriorated. As a result, when the water to be treated contains a large amount of weakly acidic anion components, it becomes impossible to sufficiently remove them, and it becomes difficult to obtain treated water having a sufficiently reduced silica concentration and boron concentration, for example.

Therefore, an object of the present invention is to provide an electric deionized water producing apparatus for producing deionized water having good water quality.

In order to achieve the above-mentioned object, the electric deionized water producing apparatus of the present invention is an electric deionized water producing apparatus that treats water to be treated to produce deionized water, and has an anode and a cathode. At least located between the plurality of first desalting units adjacent to each other and between the plurality of first desalting units and the cathode, or between the anode and the plurality of first desalting units. It has one second desalting unit, and each of the plurality of first desalting units has a first concentrating chamber and a first concentrating chamber on the cathode side of the first concentrating chamber via an anion exchange membrane. Adjacent to the first enrichment chamber, at least adjacent to the first anion removal chamber filled with the anion exchanger and the first enrichment chamber via the cathode exchange membrane on the anode side of the first enrichment chamber, at least the cation exchange. It has a body-filled cation removal chamber, and each of at least one second desalting unit has a second concentration chamber and a second concentration chamber on the cathode side of the second concentration chamber via an anion exchange membrane. Adjacent to the two concentration chambers, there is a second anion removal chamber filled with at least an anion exchanger, and the plurality of first desalting units and at least one second desalting unit are plural. A parallel flow path consisting of a first anion removal chamber , a parallel flow path consisting of a plurality of cation removal chambers , and a parallel flow path consisting of at least one second anion removal chamber are connected in series in this order. The number of the first desalting units is larger than the number of the second desalting units.

According to such an electric deionized water production apparatus, since the number of the first anion removing chambers is relatively large, the anion components in the water to be treated are sufficiently removed in the first anion removing chambers. can do. As a result, the leakage of the anion component from the first anion removal chamber can be minimized, and the leakage of the cation component from the cation removal chamber can be minimized. As a result, the anion removal performance of the second anion removal chamber can be maximized, and the desired treated water quality can be obtained.

As described above, according to the present invention, deionized water having good water quality can be produced.

It is a schematic diagram which shows the structure of the electric deionized water production apparatus which concerns on 1st Embodiment of this invention. It is a schematic diagram which shows the structure of the electric deionized water production apparatus which concerns on 2nd Embodiment of this invention. It is a schematic diagram which shows the structure of the electric deionized water production apparatus which concerns on 3rd Embodiment of this invention. It is a schematic diagram which shows the structure of the electric deionized water production apparatus which concerns on 4th Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First Embodiment)
FIG. 1 is a schematic view showing the configuration of an electric deionized water producing apparatus according to the first embodiment of the present invention.

The electric deionized water production apparatus 10 is an apparatus that combines electrophoresis and electrodialysis, and simultaneously performs deionization (demineralization) treatment of the water to be treated by an ion exchanger and regeneration treatment of the ion exchanger. It is a device. The electric deionized water producing apparatus 10 includes an anode chamber E1 provided with an anode 11, a cathode chamber E2 provided with a cathode 12, and two first deionizations provided between the anode chamber E1 and the cathode chamber E2. It has a salt unit A and a second desalting unit B provided between the two first desalting units A and the cathode chamber E2. The two first desalting units A are adjacent to each other via the first intermediate ion exchange membrane _iAA , and the first desalting unit A and the second desalting unit B exchange second intermediate ions. Adjacent to each other via membrane _iAB . Further, the anode chamber E1 is adjacent to the first desalting unit A via the anode side ion exchange membrane i _E1 , and the cathode chamber 12 is adjacent to the second desalting unit B via the cathode side ion exchange membrane i _E2 . Adjacent to.

Each of the first desalting units A has a first concentration chamber C1 and a first concentration chamber C1 adjacent to the _first concentration chamber C1 via an anion exchange membrane a1 on the cathode 12 side of the first concentration chamber C1. It has an anion removal chamber D11 and a cation removal chamber D12 adjacent to the _first concentration chamber C1 via a cation exchange membrane k1 on the anode 11 side of the first concentration chamber C1. Further, the second desalting unit has a _second anion adjacent to the second anion chamber C2 via the anion exchange membrane a2 on the cathode 12 side of the second enrichment chamber C2 and the second enrichment chamber C2. It has a removal chamber D2 and.

The first and second anion removing chambers D11 and D2 are each filled with at least anion exchangers, preferably anion exchangers in a single bed form. Examples of the anion exchange body include an anion exchange resin, anion exchange fiber, and a monolithic porous anion exchange body, and the most general-purpose anion exchange resin is preferably used. Examples of the type of anion exchanger include a weakly basic anion exchanger, a strongly basic anion exchanger and the like.

The cation removal chamber D12 is filled with at least a cation exchanger, preferably a cation exchanger in a single bed form. Examples of the cation exchanger include a cation exchange resin, a cation exchange fiber, a monolithic porous cation exchanger, and the like, and the most general-purpose cation exchange resin is preferably used. Examples of the type of the cation exchanger include a weakly acidic cation exchanger, a strongly acidic cation exchanger and the like.

In the first and second anion removal chambers D11 and D2 and the cation removal chamber D12, the water to be treated passes through the first anion removal chamber D11, the cation removal chamber D12, and the second anion removal chamber D2 in this order. It is connected. More specifically, a parallel flow path consisting of two first anion removal chambers D11, a parallel flow path consisting of two cation removal chambers D12, and a second anion removal chamber D2 are connected in series. .. The flow path configuration including the two first anion removal chambers D11 and the two cation removal chambers D12 is not limited to this, and for example, one first anion removal chamber D11 and one cation removal chamber D11. A series flow path including the chamber D12 and a series flow path including the other first anion removal chamber D11 and the other cation removal chamber D12 may be connected in parallel.

The first concentration chamber C1 is provided to take in the anion component and the cation component discharged from the first anion removal chamber D11 and the cation removal chamber D12, respectively, and discharge them to the outside by concentrated water. Further, the second concentration chamber C2 is provided to take in the anion components discharged from the second anion removal chamber D2 and discharge them to the outside by the concentrated water. As concentrated water, for example, a part of the water to be treated or a part of the treated water (deionized water) flows into the concentration chambers C1 and C2 at the same time. In order to suppress the electric resistance of the electric deionized water producing apparatus 10, it is preferable that the concentration chambers C1 and C2 are filled with an ion exchanger.

The anode chamber E1 houses the anode 11 made of a metal mesh or plate. The cathode chamber E2 houses the cathode 12 made of a metal mesh or plate. For example, a part of the water to be treated or a part of the treated water flows into the anode chamber E1 and the cathode chamber E2 as the electrode water. In order to suppress the electric resistance of the electric deionized water producing apparatus 1, it is preferable that the anode chamber E1 and the cathode chamber E2 are filled with an ion exchanger.

The first intermediate ion exchange membrane _iAA is an ion exchange membrane arranged between the first anion removal chamber D11 on the anode 11 side and the cation removal chamber D12 on the cathode 12 side. The type can be selected in consideration of the water quality of the water to be treated, the water quality required for the treated water (deionized water), the type of the ion exchanger filled in each of the removal chambers D11 and D12, and the like. The first intermediate ion exchange membrane _iAA is, for example, a single membrane of an anion exchange membrane or a cation exchange membrane, or a bipolar membrane.

The second intermediate ion exchange membrane _iAB has a function of supplying hydroxide ions to the first anion removing chamber D11 adjacent to the anode 11 side to regenerate the anion exchanger in the first anion removing chamber D11. It is preferable to have. Examples of such an ion exchange membrane include a bipolar membrane that promotes the dissociation reaction of water.

The anode-side ion exchange membrane _iE1 is preferably an ion exchange membrane containing at least a cation exchange membrane in order to supply hydrogen ions used for regeneration of the cation exchanger to the adjacent cation removal chamber D12. It is preferable that the cation exchange membrane is a single membrane or a bipolar membrane. When the anode side ion exchange membrane i _E1 is a single membrane of the cation exchange membrane, the cation is removed by passing hydrogen ions generated by the electrode reaction (2H ₂ O → O ₂ + 4H ⁺ + 4e ⁻ ) in the anode chamber E1. It can be supplied to the chamber D12. When the anode-side ion exchange membrane _iE1 is a bipolar membrane, hydrogen ions can be generated by the dissociation reaction of water and supplied to the cation removal chamber D12.

The cathode side ion exchange membrane _iE2 is an ion exchange membrane including at least an anion exchange membrane in order to supply hydroxide ions used for regeneration of the anion exchanger to the adjacent second anion removal chamber D2. Is preferable, and specifically, a single anion exchange membrane or a bipolar membrane is preferable. When the cathode side ion exchange membrane i _E2 is a single film of an anion exchange membrane, the hydroxide ion generated by the electrode reaction (2H ₂ O + ^2e- → H ₂ + ^2OH- ) in the cathode chamber E2 is passed through the first membrane. It can be supplied to the anion removal chamber D2 of 2. When the cathode side ion exchange membrane _iE2 is a bipolar membrane, hydroxide ions can be generated by the dissociation reaction of water and supplied to the second anion removal chamber D2.

Subsequently, with reference to FIG. 1, the operation of the electric deionized water production apparatus of the present embodiment will be described.

With a DC voltage applied between the anode 11 and the cathode 12, the water to be treated is passed through the first anion removal chamber D11, the cation removal chamber D12, and the second anion removal chamber D2. At this time, for example, a part of the water to be treated is supplied to the first and second concentration chambers C1 and C2 as concentrated water, and similarly, the anode chamber E1 and the cathode chamber E2 are supplied with, for example, one of the water to be treated. The part is supplied as electrode water.

First, in the _first anion removing chamber D11, most of the anion components (Cl ⁻ , CO ^3-2- , HCO ₃ ⁻ , SiO ₂ and the like) in the water to be treated are adsorbed by the anion exchanger and removed. Hydroxide ions are continuously supplied to the first anion removal chamber D11 through the adjacent first intermediate ion exchange membrane _iAA or the second intermediate ion exchange membrane _iAB . By exchanging the hydroxide ion with the anion component adsorbed on the anion exchanger, the anion exchanger in the first anion removing chamber D11 is regenerated. The anion component released from the anion exchanger exchanged with the hydroxide ion is attracted to the anode 11 side by the potential difference between the anode 11 and the cathode 12, passes through the anion exchange film a1 and enters the _first concentration chamber C1. Moving. The anion component that has moved to the first concentration chamber C1 is taken into the concentrated water and discharged to the outside together with the concentrated water.

Next, in the cation removal chamber D12, the cation component (Na ⁺ , Ca ²⁺ , Mg ²⁺ , etc.) in the water to be treated is adsorbed by the cation exchanger and removed. Hydrogen ions are continuously supplied to the cation removal chamber D12 through the adjacent first intermediate ion exchange membrane _iAA or the anode side ion exchange membrane _iE1 . By exchanging this hydrogen ion with the cation component adsorbed on the cation exchanger, the cation exchanger in the cation removal chamber D12 is regenerated. The cation component released from the cation exchanger exchanged with hydrogen ions is attracted to the cathode 12 side by the potential difference between the anode 11 and the cathode 12, passes through the cation exchange film k1 and moves to the _first concentration chamber C1. .. The anion component that has moved to the first concentration chamber C1 is taken into the concentrated water and discharged to the outside together with the concentrated water.

Then, in the second anion removing chamber D2, the anion component that could not be completely removed by the first anion removing chamber D11 in the water to be treated is adsorbed by the anion exchanger and removed. Hydroxide ions are continuously supplied to the second anion removal chamber D2 through the adjacent cathode side ion exchange membrane _iE2 . By exchanging the hydroxide ion with the anion component adsorbed on the anion exchanger, the anion exchanger in the second anion removing chamber D2 is regenerated. The anion component released from the anion exchanger exchanged with the hydroxide ion is attracted to the anode 11 side by the potential difference between the anode 11 and the cathode 12, passes through the anion exchange film _a2 , and enters the second concentration chamber C2. Moving. The anion component transferred to the second concentration chamber C2 is taken into the concentrated water and discharged to the outside together with the concentrated water.

In this way, by passing the water to be treated through the first anion removal chamber D11, the cation removal chamber D12, and the second anion removal chamber D2, the cation component and the anion component in the water to be treated can be removed. , Treated water (deionized water) can be produced.

In this embodiment, the number of first desalting units A (2) is larger than the number of second desalting units B (1), and therefore the number of first anion removal chambers D11 is second. It is larger than the number of anion removal chambers D2 in. Therefore, in the first anion removing chamber D11, the anion component in the water to be treated can be sufficiently removed. As a result, the leakage of the anion component from the first anion removal chamber D11 can be minimized, and by extension, the leakage of the cation component from the cation removal chamber D12 can be minimized. This makes it possible to maximize the anion removal performance of the second anion removal chamber D2, and even when the water to be treated contains a large amount of weakly acidic anion components such as silica, they are sufficiently removed. This makes it possible to obtain the desired treated water quality.

Since the number of the first desalting units A is larger than the number of the second desalting units B, the differential pressure of water flow increases in the second anion removing chamber D2 into which the water to be treated finally flows. I am concerned. Therefore, the volume of the second anion removal chamber D2 is preferably larger than the volume of each of the first anion removal chamber D11 and the cation removal chamber D12.

(Second embodiment)
FIG. 2 is a schematic view showing the configuration of an electric deionized water producing apparatus according to a second embodiment of the present invention.

This embodiment is the same as the first embodiment in terms of the configuration of each desalting unit A and B and the flow path configuration, but the arrangement of the first desalting unit A and the second desalting unit B is second. It is different from the embodiment of 1. Specifically, in the first embodiment, the second desalting unit B is arranged between the two first desalting units A and the cathode chamber E2, but in the present embodiment, the anode chamber is arranged. A second desalting unit B is arranged between E1 and the two first desalting units A. Accordingly, the configurations and functions of the second intermediate ion exchange membrane _iAB and the anode side ion exchange membrane _iE1 are also different from those of the first embodiment. Specifically, the second intermediate ion exchange membrane _iAB is similar to the first intermediate ion exchange membrane _iAA in that it is located between the anion exchanger on the anode 11 side and the cation exchanger on the cathode 12 side. It is an ion exchange membrane of, for example, a single membrane of an anion exchange membrane or a cation exchange membrane, or a bipolar membrane. Further, the anode-side ion exchange membrane i _E1 preferably has a function of suppressing the movement of the anion component in the second concentration chamber C2 to the anode chamber E1, and is preferably a cation exchange membrane. .. The cathode side ion exchange membrane _iE2 has the same configuration and function as that of the first embodiment in that the anion exchanger is adjacent to the anode 11 side.

(Third embodiment)
FIG. 3 is a schematic view showing the configuration of an electric deionized water producing apparatus according to a third embodiment of the present invention.

This embodiment is a modification of the first embodiment, and is a modification in which a first desalting unit A and a second desalting unit B are further added to the configuration of the first embodiment. .. That is, in the present embodiment, n first desalting units A (n is an integer of 1 or more) are added between the anode chamber E1 and the two first desalting units A, and the second desalting unit A is added. M (m is an integer of 1 or more) second desalting units B are added between the salt unit B and the cathode chamber E2. Therefore, the electric deionized water producing apparatus 10 of the present embodiment has n + 2 first desalting units A and m + 1 second desalting units B, but also in this case as well. , The number of the first desalting units A is larger than the number of the second desalting units B ((n + 2)> (m + 1)). Thereby, as in the first embodiment, it is possible to minimize the leakage of the anion component from the first anion removing chamber D11, and as a result, the anion removing performance of the second anion removing chamber D2 is improved. It can be maximized.

The added first desalting unit A is adjacent to each other via the first intermediate ion exchange membrane _iAA similar to the above-described embodiment, and the added second desalting unit B is a third. They are adjacent to each other via the intermediate ion exchange membrane _iBB . The third intermediate ion exchange membrane _iBB has a function of supplying hydroxide ions to the second anion removing chamber D2 adjacent to the anode 11 side to regenerate the anion exchanger in the second anion removing chamber D2. It is preferable to have. Examples of such an ion exchange membrane include a bipolar membrane that promotes the dissociation reaction of water.
The flow path configuration of the present embodiment is limited to a specific configuration as long as the water to be treated passes through the first anion removal chamber D11, the cation removal chamber D12, and the second anion removal chamber D2 in this order. It is not something that will be done. However, from the viewpoint of easy production, a parallel flow path consisting of n + 2 first anion removal chambers D11, a parallel flow path consisting of n + 2 cation removal chambers D12, and m + 1 second anion removal chamber. It is preferable that the parallel flow path composed of the chamber D2 is connected in series.

(Fourth Embodiment)
FIG. 4 is a schematic view showing the configuration of an electric deionized water producing apparatus according to a fourth embodiment of the present invention.

This embodiment is the same as the third embodiment in terms of the configuration of each desalting unit A and B and the flow path configuration, but the arrangement of the first desalting unit A and the second desalting unit B is the second. It is different from the third embodiment. Specifically, in the third embodiment, m + 1 second desalting units B are arranged between n + 2 first desalting units A and the cathode chamber E2, but this embodiment Then, m + 1 second desalting units B are arranged between the anode chamber E1 and n + 2 first desalting units A. That is, in the present embodiment, with respect to the second embodiment, n first desalting units (n is an integer of 1 or more) between the anode chamber E1 and the two first desalting units A are present. It is also a modified example in which A is added and m (m is an integer of 1 or more) second desalting units B are added between the second desalting unit B and the cathode chamber E2. Therefore, the second intermediate ion exchange membrane i _AB and the anode side ion exchange membrane i _E1 have the same configurations and functions as those of the second embodiment, respectively. Further, the cathode side ion exchange membrane _iE2 has the same configuration and function as that of the first embodiment (that is, the third embodiment).

(Example)
Next, the effect of the present invention will be described with reference to specific examples.

In this embodiment, in the electric deionized water production apparatus shown in FIG. 4, the number of the first desalting unit is four and the number of the second desalting unit is two, and the operation is performed for 3000 hours. The treatment water quality (specific resistance of treated water, silica concentration in treated water, boron concentration in treated water) was measured. RO permeable water having a conductivity of 4 ± 1 μS / cm (permeated water separated by a reverse osmosis membrane) was used as the water to be treated, and similar RO permeable water was used as the concentrated water and the electrode water. During operation, the treatment flow rate (flow rate of water to be treated), the concentrated water flow rate, and the electrode water flow rate are 100 L / h, 10 L / h, and 5 L / h, respectively, and the operating current (current value flowing between the electrodes) is. It is 0.5A.

Further, for comparison, the same as in the examples, using the same total number of desalting units (6) as in the examples but different ratios of the first desalting unit and the second desalting unit. The measurement was performed under the conditions of. Specifically, as Comparative Example 1, the number of the first desalting unit and the number of the second desalting unit are both three, and as Comparative Example 2, the number of the first desalting unit is 2. Then, the number of the second desalting units was four.

The specifications of each room common to Examples 1 and 2 are as follows. CER is an abbreviation for cation exchange resin and AER is an abbreviation for anion exchange resin.
・ Anode chamber: Dimension 100 × 100 × 10 mm CER filling ・ Cathode chamber: Dimension 100 × 100 × 10 mm AER filling ・ First anion removal chamber: Dimension 100 × 100 × 10 mm AER filling ・ Cathode removal chamber: Dimension 100 × 100 × 10 mm CER filling ・ Second anion removal chamber: Dimension 100 × 100 × 20 mm AER filling ・ First concentration chamber: Dimension 100 × 100 × 10 mm AER filling ・ Second concentration chamber: Dimension 100 × 100 × 10 mm AER filling

Table 1 shows the measurement results in Example, Comparative Example 1, and Comparative Example 2. For reference, Table 1 also shows the number of each of the first and second desalting units, as well as the total volume of the anion removal chamber. Here, the total volume of the anion removing chambers is the total volume of all the anion removing chambers of the first and second desalting units. For example, in the embodiment, since there are four first anion removing chambers having a volume of 0.1 L and two second anion removing chambers having a volume of 0.2 L, the total volume of the anion removing chamber is 0.8 L. Become.

As shown in Table 1, it was confirmed that in the examples, the treated water resistivity was higher and the silica concentration and the boron concentration in the treated water were suppressed to be lower than those of Comparative Examples 1 and 2. Regarding the anion removal performance, according to the conventional common general knowledge, it is considered advantageous that the volume of the anion removal chamber is large because the contact time with the anion exchanger becomes long. However, in the examples, better treated water quality is obtained even though the total volume of the anion removal chamber is smaller (that is, the amount of the anion exchange resin is smaller) than in Comparative Examples 1 and 2. It is considered that this is because, in the embodiment, the number of the first desalting units is larger than the number of the second desalting units. That is, in order to reduce the silica concentration and the boron concentration in the treated water, it is considered effective to relatively increase the number of the first desalting units into which the water to be treated first flows.

10 Electric deionized water production equipment 11 Anode 12 cathode A 1st desalting unit B 2nd desalting unit C1 1st concentrating chamber C2 2nd concentrating chamber D11 1st anion removal chamber D12 cation removal chamber D2 2nd anion removal chamber E1 anode chamber E2 cathode chamber a ₁ , a ₂ anion exchange membrane k ₁ cation exchange membrane i _AA first intermediate ion exchange membrane i _AB second intermediate ion exchange membrane i _BB third intermediate ion Exchange membrane i _E1 Anode side ion exchange membrane i _E2 Cathode side ion exchange membrane

Claims (8)

An electric deionized water production device that treats water to be treated to produce deionized water.
A plurality of first desalting units located between an anode and a cathode and adjacent to each other, and between the plurality of first desalting units and the cathode, or between the anode and the plurality of first desalting units. It has at least one second desalting unit, which is located between the salt units and
Each of the plurality of first desalting units
The first concentration chamber and
A first anion removal chamber adjacent to the first concentration chamber on the cathode side of the first concentration chamber via an anion exchange membrane and filled with at least an anion exchanger.
It has a cation removal chamber adjacent to the first concentration chamber on the anode side of the first concentration chamber via a cation exchange membrane and filled with at least a cation exchanger.
Each of the at least one second desalting unit
The second concentration room and
It has a second anion removal chamber, which is adjacent to the second concentration chamber on the cathode side of the second concentration chamber via an anion exchange membrane and is filled with at least an anion exchanger.
The plurality of first desalting units and the at least one second desalting unit are a parallel flow path composed of a plurality of the first anion removal chambers and a parallel flow path composed of a plurality of the cation removal chambers. And a parallel flow path consisting of at least one second anion removal chamber are connected in series in this order.
An electric deionized water producing apparatus in which the number of the first desalting units is larger than the number of the second desalting units. The electric deionized water producing apparatus according to claim 1, which has a plurality of the second desalting units adjacent to each other. The plurality of first desalting units are adjacent to each other via a first intermediate ion exchange membrane and adjacent to the plurality of second desalting units via a second intermediate ion exchange membrane. The electric deionized water production apparatus according to claim 2, wherein the plurality of second desalting units are adjacent to each other via a third intermediate ion exchange membrane. The plurality of second desalting units are located between the plurality of first desalting units and the cathode.
The second intermediate ion exchange membrane supplies hydroxide ions to the first anion removal chamber adjacent to the anode side of the second intermediate ion exchange membrane, and anions in the first anion removal chamber. The electric deionized water production apparatus according to claim 3, which has a function of regenerating an exchange. The electric deionized water producing apparatus according to claim 3, wherein the plurality of second desalting units are located between the anode and the plurality of first desalting units. The third intermediate ion exchange membrane supplies hydroxide ions to the second anion removal chamber adjacent to the anode side of the third intermediate ion exchange membrane, and anions in the second anion removal chamber. The electric deionized water production apparatus according to any one of claims 3 to 5, which has a function of regenerating an exchange. The electric deionized water production apparatus according to any one of claims 1 to 6, wherein the water to be treated containing a weak acid is supplied as the water to be treated. The electric deionized water production apparatus according to any one of claims 1 to 6, wherein the permeated water separated by the reverse osmosis membrane is supplied as the water to be treated.

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