JP6496146B2 - Electric deionized water production equipment - Google Patents

Description

  The present invention relates to an electric deionized water production apparatus for producing demineralized water (treated water) in which ions are electrically excluded from water to be treated, and particularly to an aspect of an ion exchanger filled in the apparatus.

In semiconductor and liquid crystal manufacturing processes, semiconductor wafers and glass substrates are cleaned using ultrapure water from which impurities are highly removed. As an apparatus for producing ultrapure water used for such cleaning, an electric deionized water production apparatus (hereinafter referred to as EDI) has begun to be used.
EDI, which has been put into practical use, is basically desalted by filling the gap formed by the cation exchange membrane and the anion exchange membrane with an ion exchange resin such as anion exchange resin or cation exchange resin as an ion exchanger. It is set as a chamber and water to be treated is passed through the ion exchange resin layer. In the EDI, a direct current is applied in a direction perpendicular to the flow of water to be treated through both a cation exchange membrane and an anion exchange membrane, thereby flowing through a concentration chamber formed outside the desalting chamber. Desalinated water (treated water) is produced while electrically removing ions in the water to be treated in the concentrated water.

Patent Document 1 describes that in EDI, in order to reduce the electrical resistance during water flow operation, the adhesion between ion exchangers housed in a desalting chamber and an ion exchange membrane is increased. Further, this document describes that an ion exchanger in an amount in which the regenerated volume of the ion exchanger in a free state (without being bound by the desalting chamber) is 103 to 170% of the volume of the desalting chamber is removed. The filling of the salt chamber is described.
In the invention described in Patent Document 1, the volume of the ion exchanger during EDI water-flowing operation (during use) has not been sufficiently studied, and thus good water quality cannot always be obtained. If the ion exchanger is overfilled with respect to the desalting chamber volume, the pressure loss in the desalting chamber increases and the amount of treated water decreases, and the sealing performance between the desalting chamber and the adjacent concentrating chamber also decreases. There is a case.
Therefore, in Patent Document 2, the ion exchanger is placed in the desalting chamber so that the ratio of the volume of the ion exchanger filled in the desalting chamber to the desalting chamber volume is 101 to 120%. It has been proposed to be housed in.

JP-A-10-216729 JP 2001-104960 A

  In the inventions described in Patent Documents 1 and 2 described above, the ion exchanger is dried before filling into the desalting chamber, or an ion form other than a regenerated form (for example, a salt form such as Na form or Cl form). By using the method of converting to an ion exchanger, the volume of the ion exchanger is expanded during the water passing operation of the desalting chamber, thereby improving the adhesion between the ion exchangers in the desalting chamber and the ion exchange membrane. .

However, when the EDI filled with the ion exchanger in the desalting chamber is operated by the above-described methods, the time from the start of the EDI operation until the desalinated water having a desired water quality (for example, specific resistance value) can be produced, so-called rise It turns out that the time is long.
Specifically, when the ion exchanger is dried, the deterioration of the ion exchanger proceeds. It was confirmed that when the desalting chamber was filled with such an ion exchanger and the production of desalted water was started, the organic component (TOC) derived from the ion exchanger leaked into the desalted water. In addition, when an ion exchanger that has been converted to a salt form such as Na form or Cl form is charged into a desalting chamber and production of demineralized water is started, the salt form ion exchanger is removed from the salt form in the initial stage of production. It was confirmed that salt components (Na, Cl, etc.) leaked into the salt water, and it took time to improve the water quality.
On the other hand, when the deionization chamber is simply filled with the ion exchanger in a wet state, the adhesion between the ion exchangers in the demineralization chamber and the ion exchange membrane becomes insufficient, and the water flow operation is not performed. Electrical resistance and voltage may also increase.

  In view of the problems of the background art described above, the present invention can obtain demineralized water with good water quality in a short time from the start of production of demineralized water, and has an electric resistance at the time of water flow operation (during the production of demineralized water). An object of the present invention is to provide an electric deionized water production apparatus that can be reduced.

One aspect of the present invention includes a cathode and an anode facing each other, a desalting chamber defined by an ion exchange membrane between the cathode and the anode and containing the first ion exchanger, and ion exchange on both sides of the desalting chamber The present invention relates to an electric deionized water production apparatus for producing demineralized water having a pair of concentration chambers adjacent to a membrane. In this apparatus, the first ion exchanger is filled in the desalting chamber in a regenerated form in a wet state with a moisture content exceeding 45% . The concentration chamber is filled with a second ion exchanger. Further, in the second ion exchanger, the volume of the second ion exchanger taken out from the concentration chamber after the demineralized water production in the electric deionized water production apparatus is 103% to 125 % of the concentration chamber volume. It is characterized by.

In the said aspect, the 1st ion exchanger with which the desalination chamber was filled is made into the reproduction | regeneration form of a wet state. In this way, if the demineralization chamber is filled with a regenerated ion exchanger instead of the salt form, it becomes possible to produce demineralized water without leaking salt components into the demineralized water from the start of production of the demineralized water. The time from the start of production of desalted water to obtaining the desired treated water quality is shortened. In addition, since the ion exchanger is filled in the desalting chamber in a wet state, leakage of the organic substance component (TOC) derived from the ion exchanger can also be reduced.
In addition, the ion exchangers in the concentration chambers are filled with an ion exchanger whose volume is 103% to 125% of the volume of the concentration chambers, and the amount of ion exchangers in the concentration chambers is increased. In addition, the adhesion with the ion exchange membrane is improved, and the ion exchanger in the desalting chamber adjacent to the concentration chamber is also compressed. This facilitates the movement of ions in the concentration chamber and the desalting chamber, and the desalting proceeds smoothly. Therefore, it is possible to achieve a reduction in electrical resistance and voltage during the production of desalted water and an improvement in the quality of treated water.

  Therefore, according to the present invention, demineralized water with good water quality can be obtained in a short time from the start of the production of desalted water, and the electrical resistance during the water-passing operation (during the production of desalted water) can also be reduced. .

It is typical sectional drawing which shows one structural example of EDI which can apply this invention. It is typical sectional drawing which shows the other structural example of EDI which can apply this invention. It is a graph which shows TOC of this desalted water at the time of manufacturing desalted water by changing the filling aspect of an ion exchanger. It is a graph which shows the specific resistance of this desalted water when changing the filling aspect of an ion exchanger, and manufacturing desalted water.

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

The EDI according to the present invention can be configured as shown in FIG.
(Configuration example 1 of EDI)
In the configuration example of FIG. 1, the EDI 1 is disposed on the outside of the desalination chamber D and the desalination chamber having a pair of concentration chambers C1 and C2 disposed on both sides of the desalination chamber D, and one of the concentration chambers C1. And an anode chamber E2 disposed outside the other enrichment chamber C2.
The desalting chamber D includes an anion exchange membrane AEM and a cation exchange membrane CEM that are arranged opposite to each other, and a mixed bed type ion exchanger (anion exchange resin and cation exchange) filled between the anion exchange membrane AEM and the cation exchange membrane CEM. A mixture of resin). The concentration chambers C1 and C2 are also filled with a mixed bed type ion exchanger. In this example, the ion exchanger filled in the desalination chamber or concentration chamber is a mixed bed type, but any type can be used in the desalination chamber or concentration chamber, whether it is a mixed bed, a multi-layer bed or a single bed. is there.

A cathode is accommodated in the cathode chamber E1. The cathode is made of a metal net or plate, and for example, a stainless steel net or plate can be used. An anode is accommodated in the anode chamber E2. The anode is made of a metal net or plate. When the water to be treated contains Cl ⁻ , chlorine is generated at the anode. For this reason, it is desirable to use a material having chlorine resistance for the anode, and examples thereof include metals such as platinum, palladium and iridium, or materials obtained by coating titanium with these metals.

In order to produce demineralized water (treated water) using the EDI 1 shown in FIG. 1, the desalination chamber D is supplied from the water supply line 2 with a DC voltage applied between the electrodes provided in the anode chamber E1 and the cathode chamber E2. Allow the treated water to pass through. In the desalting chamber D, anion components (Cl ⁻ , CO ₃ ²⁻ , HCO ₃ ⁻ , SiO ₂ , etc.) are captured by the anion exchange resin, and cation components (Na ⁺ , Ca ²⁺ , Mg ^2+, etc.) are captured by the cation exchange resin. Is done. At the same time, a water dissociation reaction occurs at the interface between the anion exchange resin and the cation exchange resin in the desalting chamber D, and hydrogen ions (H ⁺ ) and hydroxide ions (OH ⁻ ) are generated. Ion components captured by ion exchangers such as cation exchange resin and anion exchange resin are exchanged with hydrogen ions and hydroxide ions to be released from the ion exchanger. The liberated ionic component travels through the ion exchanger, migrates to the ion exchange membrane (anion exchange membrane AEM or cation exchange membrane CEM), is electrodialyzed by the ion exchange membrane, and moves into the concentration chambers C1 and C2. The ionic components that have moved into the concentration chambers C1 and C2 are discharged by the concentrated water flowing through the concentration chambers C1 and C2.
As described above, the water to be treated that has passed through the desalting chamber D to which a DC voltage is applied becomes desalted water (treated water), and is sent to a use point (not shown) by the treated water line 3.

  In the configuration example of FIG. 1, EDI 1 has a single desalination chamber D, but EDI 1 includes a plurality of units composed of demineralization chamber D and concentration chamber C 1 stacked in the arrangement shown in FIG. It may be laminated between the concentration chamber C2 and the anode chamber E1 in the direction in which the current voltage is applied.

  Moreover, as an ion exchanger with which the desalination chamber D of this embodiment is filled, both the anion exchange resin and the cation exchange resin are regenerated (OH form or H form) and are in a wet state. . If the desalination chamber D is filled with a regenerative ion exchanger instead of the salt form in this way, it is possible to produce the desalted water without leaking salt components into the desalted water from the start of the production of the desalted water. The time from the start of production of desalted water to the desired quality of treated water is shortened. In addition, since the desalting chamber is filled with the wet ion exchanger, leakage of the organic component (TOC) derived from the ion exchanger can also be reduced.

  However, the present invention only has to produce the above two effects in the entire ion exchanger filled in the desalting chamber D. Therefore, both the anion exchange resin and the cation exchange resin constituting the ion exchanger are regenerated. It may not be in the wet state (OH form or H form). That is, either the anion exchange resin or the cation exchange resin is filled in the desalting chamber D in a regenerated form (OH form or H form), or either the anion exchange resin or the cation exchange resin is removed in a wet state. The salt chamber D may be filled.

In particular, it is sufficient that the ion exchanger in the desalting chamber is in a regenerated form in a wet state before the desalted water is produced with EDI 1, and this state can be realized in the following four cases.
(Case 1)
“Dehydrated ion exchanger” itself is filled in a desalting chamber.
(Case 2)
Fill the desalting chamber with a “wet and salt-type ion exchanger”, and then perform a water flow operation (trial operation) with voltage applied, or use regenerative chemicals (hydrochloric acid or sodium hydroxide). Converting the ion exchanger in the desalting chamber into a “wet and regenerative ion exchanger” by passing the solution.
(Case 3)
By filling the desalting chamber with a “dry and regenerative ion exchanger” and then performing a water flow operation (trial operation), the ion exchanger in the desalting chamber is “wet, Converted to a regenerative ion exchanger.
(Case 4)
Fill the desalting chamber with a “dry, salt-type ion exchanger”, and then perform a water flow operation (trial operation) with voltage applied, or use regenerative chemicals (hydrochloric acid or sodium hydroxide). Converting the ion exchanger in the desalting chamber into a “wet and regenerative ion exchanger” by passing the solution.

  In the ion exchanger filled in the desalting chamber D, the filling volume may be a volume that does not cause the following problems. If the ion exchanger is overfilled with respect to the desalting chamber volume, the pressure loss in the desalting chamber D increases and the amount of treated water decreases, and between the desalting chamber D and the concentrating chambers C1, C2 adjacent thereto. There may be a problem that the sealing performance of the resin deteriorates. On the other hand, when the filling amount of the ion exchanger in the desalting chamber D is too small, ions are difficult to move in the desalting chamber D, and the quality of the treated water is deteriorated. Therefore, the volume of the ion exchanger that does not cause such a problem may be used. For example, an ion exchanger having a volume of about 80 to 130% of the volume of the desalting chamber D is accommodated in the desalting chamber D. do it.

  The concentration chambers C1 and C2 are also filled with an ion exchanger. By filling not only the desalting chamber D but also the concentration chambers C1 and C2 with ion exchangers, ions that have permeated through the ion exchange membrane adjacent to the desalting chamber D move quickly into the concentration chambers C1 and C2, Ion migration within the desalting chamber D is also extremely fast, and the production efficiency of desalted water can be greatly improved.

Furthermore, as the ion exchanger filled in the concentrating chambers C1 and C2, at least one of the anion exchange resin and the cation exchange resin is an ion exchange resin other than the regenerated form, that is, a salt form, or a dry ion exchange resin. Filled with. This is because the volume of the ion exchanger filled in the concentrating chambers C1 and C2 expands during water flow operation, and the expansion improves the adhesion between the ion exchangers in the concentrating chamber and the ion exchange membrane. The ion exchanger in the desalting chamber D is also compressed. This facilitates the movement of ions in the concentration chamber and the desalting chamber, and the desalting proceeds smoothly. Therefore, when the ion exchange resin in a salt form or in a dry state is filled in the concentration chamber, the electric resistance and voltage during EDI operation can be reduced.
The “wet state” refers to a state where the moisture content (weight) of the ion exchanger exceeds 45%, and the “dry state” refers to a state where the moisture content (weight) of the ion exchanger is 45% or less. Say.

In the case of a cation exchange resin, examples of the salt form include Na form, Ca form, and Mg form. In the case of an anion exchange resin, examples of the salt form include Cl form and HCO ₃ form. Specifically, as the anion exchange resin filled in the concentrating chambers C1 and C2, styrenic gel type, styrenic MR type, acrylic gel type, acrylic MR type strongly basic and weakly basic anion exchange resins are available. used. This is in the wet state of Cl form or HCO ₃ form. When the volume corresponding to the volume of the concentrating chamber (volume at the time of filling) is 100%, the anion exchange resin is converted into Cl form, HCO ₃ form to OH form in EDI1 water flow operation (regeneration to regenerated form). Conversion) causes volume expansion of about 110 to 120%. On the other hand, as the cation exchange resin, styrene gel type, styrene MR type, acrylic gel type, acrylic MR type strong acid or weak acid cation exchange resin is used. This is a wet form of Na form. When the volume corresponding to the volume of the concentrating chamber (volume at the time of filling) is 100%, the cation exchange resin is 110 in the process of changing from Na form to H form (conversion to regenerated form) in EDI1 water flow operation. A volume expansion of ~ 120% occurs.
In addition, it can replace with the anion exchange resin expanded at the time of conversion to the above regeneration types, and can use the anion exchange resin dried until the moisture content became about 40%. Similarly, a cation exchange resin dried to a water content of about 40% can be used in place of the cation exchange resin that expands upon conversion to a regenerated form. Assuming that the volume corresponding to the volume of the concentrating chamber (the volume at the time of filling) is 100%, volume expansion of about 110 to 120% occurs in a wet state during the water passing operation of EDI1.

  As described above, the concentration chambers C1 and C2 are filled with a salt ion exchange resin or a dry ion exchange resin. The concentrated water passing through the concentration chambers C1 and C2 is discharged out of the system through a flow path L different from the desalted water (treated water). For this reason, even if salt-type or dry ion-exchange resin is filled into the concentrating chamber and salt components or TOC leak from the ion-exchange resin to the concentrated water when water passes through the concentrating chamber, the quality of the demineralized water is affected. Not give. Rather, the salt-form or dry ion-exchange resin expands in volume when water is passed through, improving the adhesion between the ion exchangers in the concentration chamber and the ion-exchange membrane, and further compressing the ion exchanger in the desalting chamber. Thus, ions can easily move in the concentration chamber and the desalination chamber, and the effect of reducing the electrical resistance and voltage during EDI operation can be obtained.

(Configuration example 2 of EDI)
In the configuration example of FIG. 2, the desalting chamber D is divided into two small desalting chambers. Specifically, the desalination chamber D includes a first small desalination chamber D1 adjacent to the first concentration chamber C1, and a second small desalination chamber D2 adjacent to the second concentration chamber C2. It is divided into. Specifically, the cathode chamber E2 is adjacent to the second concentration chamber C2 via the anion exchange membrane AEM, and the second concentration chamber C2 is connected to the second small desalination chamber D2 via the cation exchange membrane CEM. Adjacent. The second small desalting chamber D2 is adjacent to the first small desalting chamber D1 via the anion exchange membrane AEM, and the first concentration chamber C1 is connected to the first small desalting chamber D1 via the anion exchange membrane AEM. Adjacent, the anode chamber E1 is adjacent to the first concentration chamber C1 via the cation exchange membrane CEM.
In the present specification, among the plurality of ion exchange membranes, the anion exchange membrane AEM that partitions the desalination chamber D into the first small desalination chamber D1 and the second desalination chamber D2 is referred to as “intermediate ion exchange membrane”. Called to distinguish from other ion exchange membranes. The intermediate ion exchange membrane may be changed to a cation exchange membrane or a bipolar membrane according to the desired performance.

  Further, in FIG. 2, the first small desalting chamber D1 is filled with an anion exchanger in a single bed form. The second small desalting chamber D2 is filled with a mixed bed type ion exchanger (a mixture of anion exchange resin and cation exchange resin). In this example, the ion exchanger filled in the desalting chamber D1 is a single bed of anion exchanger and the ion exchanger filled in the desalting chamber D2 is a mixed bed type. Any type of floor can be used.

  Here, the main flows of treated water and concentrated water in EDI 1 shown in FIG. 2 will be outlined in advance. The water to be treated is supplied to the first small desalination chamber D1 through the water supply line 2 and passes through the small desalination chamber D1. The treated water that has passed through the first small desalting chamber D1 is supplied to the second small desalting chamber D2 through the flow path L1, and is discharged to the treated water line 3 after passing through the second small desalting chamber D2. On the other hand, the concentrated water is supplied in parallel to the first concentration chamber C1 and the second concentration chamber C2, respectively, passes through the concentration chambers C1 and C2, and is discharged to the flow path L2. In addition, although illustration is abbreviate | omitted, the flow path for supplying the electrode water and the flow path for discharging | emitting the supplied electrode water are each connected to the cathode chamber E2 and the anode chamber E1. In this example, the treated water that has passed through the first small desalting chamber D1 is supplied to the second small desalting chamber D2, but the treated water that has passed through the second small desalting chamber D2 is supplied to the first small desalting chamber D2. You may supply to the desalination chamber D1.

Next, the operation of the EDI 1 in the configuration example shown in FIG. 2 will be described.
A predetermined DC voltage is applied between the anode in the anode chamber E1 and the cathode in the cathode chamber E2. Under this energized state, water to be treated is supplied from the water supply line 2 to the first small desalination chamber D1. Anion components (Cl ⁻ , CO ₃ ²⁻ , HCO ₃ ⁻ , SiO _2, etc.) in the supplied water to be treated are captured in a process in which the water to be treated passes through the first small desalting chamber D1. Then, the anion component captured in the first small desalting chamber D1 moves to the first concentration chamber C1 via the first small desalting chamber D1 and the anion exchange membrane AEM adjacent thereto, and the first concentration It is discharged to the flow path L2 together with the concentrated water passing through the chamber C1.
Next, the water to be treated that has passed through the first small desalting chamber D1 is supplied to the second small desalting chamber D2 via the flow path L1. Here, the second small desalting chamber D2 is filled with a mixed bed or multi-bed type ion exchanger. In this case, for the treatment water supplied to the second small depletion chamber D2, water cationic components cation exchange resin ^{(Na +, Ca 2+, Mg} 2+ , etc.) are captured. The cation component captured by the cation exchange resin moves to the second second concentration chamber C2 via the second small desalting chamber D2 and the cation exchange membrane CEM, and is concentrated through the second concentration chamber C2. It is discharged together with water into the flow path L2.
Furthermore, anion components (Cl ⁻ , CO ₃ ²⁻ , HCO ₃ ⁻ , SiO _2, etc.) remaining in the for-treatment water passing through the second small desalting chamber D2 are captured by the anion exchange resin. The anion component captured by the anion exchange resin in the second small desalting chamber D2 moves to the adjacent first small desalting chamber D1 via the second small desalting chamber D2 and the intermediate ion exchange membrane AEM. The anion component moved to the first small desalting chamber D1 moves to the first concentrating chamber C1 adjacent to the first small desalting chamber D1 via the anion exchange membrane AEM, and the first concentrating chamber C1 is passed through. Together with the concentrated water to be discharged to the flow path L2.
As described above, the configuration example of FIG. 2 has a higher desalting performance compared to the configuration example of FIG.

In the present invention, the ion exchanger filled in the first small desalting chamber D1 and the second small desalting chamber D2 is regenerated (OH type or H type) and wet. The reason for this is that, as in the configuration example of FIG. 1, the desalinated water can be produced without the salt component leaking into the desalted water from the start of the production of the desalted water, and the desired treated water quality is obtained from the start of the production of the desalted water. This is for shortening the time until the time is reduced and for reducing leakage of the organic component (TOC) derived from the ion exchanger. As described above, the ion exchanger in the desalting chamber only needs to be in a regenerated form in a wet state before the desalted water is produced with EDI1.
On the other hand, the ion exchanger filled in the concentrating chambers C1 and C2 is filled with a salt ion exchange resin or a dry ion exchange resin. This is because, as in the configuration example of FIG. 1, the adhesion between the ion exchangers in the concentration chambers C1 and C2 and the ion exchange membrane is increased to reduce the electrical resistance during EDI operation.

(Other embodiments)
In the present invention, only the above-described EDI 1 may be operated alone, or a pretreatment device such as an RO membrane separation device may be installed in front of EDI 1. More preferably, a two-stage RO membrane separation apparatus is installed in front of EDI1. By passing the water to be treated through both the EDI 1 and the RO membrane separator, the quality of the treated water (demineralized water) can be further improved.

Hereafter, the test result verified about the effect of this invention is shown.
In the following tests 1 to 3, EDI having the configuration example of FIG. 1 was used. In each test, the volume of the desalting chamber D and the concentration chambers C1 and C2 is all 150 mm × 300 mm × 10 mm, the flow rate of the treated water during the desalted water production operation is 100 L / h, and the flow rate of the concentrated water is 10 L. / H, the current value to be energized was 2.5A. The treated water was RO permeated water of 3.0 ± 0.5 μS / cm.
[Test 1]
In Test 1, the effect of filling the desalting chamber D with an ion exchanger in a regenerated or wet state was verified. For this reason, EDI1 (configuration example in FIG. 1) was passed through, and the TOC [μg / L] and specific resistance [MΩ · cm] of the treated water (demineralized water) were measured as the operating time passed. This measurement was performed in four combinations (Examples 1 and 2 below, Comparative Example 1 below) in which the modes of the ion exchanger filled in the desalting chamber D and the ion exchangers filled in the concentration chambers C1 and C2 were changed. Comparative Example 2) was conducted.

Example 1
In Example 1, the desalting chamber D is filled with a mixed bed type ion exchanger in a wet regeneration form (mixed bed / regeneration / wet), and the concentration chambers C1 and C2 are mixed bed type ion exchange. Fill body with wet salt form (mixed bed / salt form / wet).
Specifically, the ion exchanger filled in the desalting chamber D and the concentration chambers C1 and C2 includes an anion exchange resin (styrene gel type strongly basic anion exchange resin) and a cation exchange resin (styrene gel type strong acidity). A mixed bed type with a cation exchange resin) is used, and such a mixed bed type ion exchanger is filled in a wet state with a moisture content of about 50%. In the desalting chamber D, the anion exchange resin is used in a regenerated form (OH form) and the cation exchange resin is used in a regenerated form (H form). On the other hand, in the concentration chambers C1 and C2, the anion exchange resin is used in a salt form (Cl form) and the cation exchange resin is used in a salt form (Na form).
Furthermore, the volume when each ion exchanger is filled in the desalting chamber D and the concentration chambers C1 and C2 is 100% of the volume of the desalting chamber D and the concentration chambers C1 and C2. Further, the volume of the ion exchanger taken out from the desalting chamber D after the water passing operation of EDI1 is 94% with respect to the volume of the desalting chamber D1, and is taken out from the concentrating chambers C1 and C2 after the water passing operation. Further, the volume of each ion exchanger is 112% with respect to the volume of the concentration chambers C1 and C2.

  Thus, when each chamber was filled with an ion exchanger and a water flow operation was performed, the TOC [μg / L] of the treated water was 157 after 10 minutes from the start of operation, 16, after 60 minutes, 13, after 120 minutes, A measured value of 6 was shown after 180 minutes. Further, the specific resistance [MΩ · cm] of the treated water showed a measured value of 18.2 after 10 minutes from the start of operation, and was 18.2 after 60 minutes, 120 minutes and 180 minutes.

Example 2
In Example 2, the desalination chamber D is filled with a mixed bed type ion exchanger in a wet regeneration form (mixed bed / regeneration / wet), and the concentration chambers C1 and C2 are mixed bed type ion exchange. Fill the body in dry regenerated form (mixed bed / regenerated form / dry).
Specifically, the ion exchanger filled in the desalting chamber D and the concentration chambers C1 and C2 includes an anion exchange resin (styrene gel type strongly basic anion exchange resin) and a cation exchange resin (styrene gel type strong acidity). Use a mixed bed type with cation exchange resin. In the desalting chamber D, the anion exchange resin is used in a regenerated form (OH form), and the cation exchange resin is used in a regenerated form (H form). Such a mixed bed type ion exchanger has a water content of 50%. Fill in the wet state. On the other hand, in the concentrating chambers C1 and C2, an anion exchange resin is used in a regenerated form (OH form) and a cation exchange resin is used in a regenerated form (H form), and such a mixed bed type ion exchanger has a water content of 40%. Fill in the dry state.
Furthermore, the volume when each ion exchanger is filled in the desalting chamber D and the concentration chambers C1 and C2 is 100% of the volume of the desalting chamber D and the concentration chambers C1 and C2. Further, the volume of the ion exchanger taken out from the desalting chamber D after the water passing operation of EDI1 is 95% with respect to the volume of the desalting chamber D1, and is taken out from the concentration chambers C1 and C2 after the water passing operation. Further, the volume of each ion exchanger is 117% with respect to the volume of the concentration chambers C1 and C2.

  Thus, when each chamber was filled with the ion exchanger and the water flow operation was performed, the TOC [μg / L] of the treated water was 180 minutes after the start of operation, 13 minutes after the start of operation, 13, 12 minutes after 120 minutes, A measured value of 5 was shown after 180 minutes. Further, the specific resistance [MΩ · cm] of the treated water showed a measured value of 18.2 after 10 minutes from the start of operation, and was 18.2 after 60 minutes, 120 minutes and 180 minutes.

Comparative Example 1
In Comparative Example 1, the desalting chamber D is filled with a mixed bed type ion exchanger in a dry regeneration form (mixed bed / regeneration / drying), and the concentration chambers C1 and C2 are not filled with an ion exchanger.
Specifically, the ion exchanger filled in the desalting chamber D is composed of an anion exchange resin (styrene gel type strongly basic anion exchange resin) and a cation exchange resin (styrene gel type strongly acidic cation exchange resin). Use a mixed floor type. Further, in the desalination chamber D, the anion exchange resin is used in a regenerated form (OH form) and the cation exchange resin is used in a regenerated form (H form), and such a mixed bed type ion exchanger has a water content of about 40%. Fill in the dry state.
Furthermore, the volume when each ion exchanger is filled in the desalting chamber D is 80% of the volume of the desalting chamber D. Further, the volume of the ion exchanger taken out from the desalting chamber D after the EDI1 water-flowing operation is 95% of the volume of the desalting chamber D1.

  Thus, when each chamber was filled with an ion exchanger and the water flow operation was performed, the TOC [μg / L] of the treated water was 1225 after 10 minutes from the start of operation, 210 after 60 minutes, 140 after 120 minutes, A measured value of 89 was indicated after 180 minutes. Further, the specific resistance [MΩ · cm] of the treated water showed measured values of 16.5 after 10 minutes from the start of operation, 17.8 after 60 minutes, 17.9 after 120 minutes, and 18.2 after 180 minutes. .

Comparative Example 2
In Comparative Example 2, the desalting chamber D is filled with a mixed bed type ion exchanger in a wet salt form (mixed bed / salt shape / wet), and the concentration chambers C1 and C2 are not filled with an ion exchanger.
Specifically, the ion exchanger filled in the desalting chamber D is composed of an anion exchange resin (styrene gel type strongly basic anion exchange resin) and a cation exchange resin (styrene gel type strongly acidic cation exchange resin). Use a mixed floor type. In the desalting chamber D, the anion exchange resin is used in a salt form (Cl form) and the cation exchange resin is used in a salt form (Na form), and such a mixed bed type ion exchanger has a water content of about 50%. In a wet state.
Furthermore, the volume when each ion exchanger is filled in the desalting chamber D is 85% of the volume of the desalting chamber D. Further, the volume of the ion exchanger taken out from the desalting chamber D after the EDI1 water-flowing operation is 96% with respect to the volume of the desalting chamber D1.

  Thus, when each chamber was filled with the ion exchanger and the water flow operation was performed, the TOC [μg / L] of the treated water was 254 after 10 minutes from the start of operation, 25 after 60 minutes, 18, after 120 minutes, A measured value of 14 was shown after 180 minutes. Further, the specific resistance [MΩ · cm] of the treated water showed a measured value of 2.1 after 10 minutes from start of operation, 5.5 after 60 minutes, 7.5 after 120 minutes, and 9.8 after 180 minutes. .

  FIGS. 3 and 4 are graphs in which the measured TOC and specific resistance of the treated water are plotted for each of the ion exchanger filling modes described above. As can be seen from these figures, in Examples 1 and 2 in which the desalting chamber D is filled with the ion exchanger in the wet state, there is little TOC leakage, and good treatment can be achieved in a short time from the start of the desalting chamber production. Water quality is obtained. However, Comparative Example 1 in which the ion exchanger is filled in the desalting chamber D in a dry state has a lot of TOC leakage, and Comparative Example 2 in which the desalting chamber is filled with salt is from the start of production of the desalting chamber until a good treated water quality is obtained. The time is long. That is, it can be confirmed that the treated water quality (specific resistance) does not decrease in Comparative Example 1, but the TOC of treated water is large, and in Comparative Example 2, the treated water quality (specific resistance) is low, but the TOC of treated water does not increase. Can be confirmed.

[Test 2]
In Test 2, the effect when the concentration chambers C1 and C2 were filled with a dry or salt ion exchanger was verified. For this reason, the filling rate of the ion exchanger in the concentrating chamber is changed, EDI1 (configuration example in FIG. 1) is passed through, and after 500 hours from the start of operation, the quality of the treated water (specific resistance), the cathode And the voltage required for energization between the anodes were measured. In this measurement, the desalting chamber D is filled with a mixed bed type ion exchanger in a wet state (mixed bed / regenerated type / wet), and the concentrating chambers C1 and C2 are mixed bed type ion exchangers. Was filled in a dry regenerated form (mixed bed / regenerated form / dry).
In particular, in this measurement, the mode of the resin of each ion exchanger filled in the desalting chamber D and the concentration chambers C1 and C2 is the same as that in the above-described second embodiment.

  Moreover, the filling rate of the ion exchanger in the concentration chamber was set as follows. After the EDI 1 is operated for 500 hours, the EDI 1 is disassembled, the ion exchangers in the concentration chambers C1 and C2 are taken out, and the volume of the ion exchanger in a state where the volume is freely expanded is measured. The ratio [%] of this measured value to the concentration chamber volume (volume of the concentration chamber before filling with the ion exchanger) was taken as the filling rate of the ion exchanger in the concentration chamber.

The filling rate [%] of the ion exchanger in the concentration chamber was changed to 98, 103, 125, and 129, and the voltage and treated water quality during EDI operation with respect to each filling rate were measured. The results shown in Table 1 were obtained. It became. In Table 1, each measured voltage is shown as a relative ratio based on the voltage when the concentration rate of the ion exchanger in the concentrating chamber is 98%.

  As can be seen from Table 1, the ion exchanger filling rate in the desalting chamber at the end of the operation was similar in all systems. The voltage at the ion exchanger filling rate of 98% in the concentrating chamber is significantly higher, 1.5 times the voltage at the ion exchanger filling rate of 103%. On the other hand, when the ion exchanger filling rates are 129% and 125%, almost the same voltage is shown and there is no significant difference. Regarding water quality, the filling rate tends to decrease between 125% and 129%. Therefore, it became clear that the optimal ion exchanger filling rate of the concentrating chamber is 103 to 125%. In other words, when the filling rate is within this range, the electric resistance is reduced, the voltage during EDI operation can be kept low, and good treatment water quality can be obtained without overfilling the ion exchanger. Therefore, in the present invention, the ion exchanger is filled in the concentrating chamber such that the free volume of the ion exchanger taken out of the concentrating chamber after the EDI water-flowing operation is 103 to 125% of the concentrating chamber volume. Here, the “free state” means a state in which the ion exchanger is freely volume-expanded without being constrained.

  In addition, it is assumed that even if the concentration chambers C1 and C2 are filled with a mixed bed type ion exchanger in a wet salt form (mixed bed / salt form / wet), the result is similar to the above measurement result. .

[Test 3]
In Test 3, the effect when the thicknesses of the desalting chamber D and the concentration chambers C1 and C2 were changed was verified. For this reason, the ratio of the thickness of the concentrating chamber to the thickness of the desalting chamber is changed, and EDI 1 (configuration example in FIG. 1) is passed through. After 500 hours from the start of the operation, between the cathode and the anode The voltage required for energization was measured. In this measurement, the concentration chambers C1 and C2 are changed to the same thickness. The “thickness” of the desalting chamber or concentration chamber here refers to the width in the direction corresponding to the energization direction between the cathode and the anode. In this measurement, the desalting chamber D is filled with a mixed bed type ion exchanger in a wet regeneration form (mixed bed / regeneration / wet), and the concentration chambers C1 and C2 are mixed bed type ions. The exchanger was filled with wet salt form (mixed bed / salt form / wet).
In particular, in this measurement, the mode of the resin of each ion exchanger filled in the desalting chamber D and the concentration chambers C1 and C2 is the same as that in the first embodiment.

The ratio of the thickness of the concentration chamber to the thickness of the desalting chamber was changed to 1/4, 1/3, 1/1, 2/1, and the voltage during operation of each EDI produced at each ratio was measured. However, the results shown in Table 2 were obtained. In Table 2, each measured voltage is shown as a relative ratio based on the voltage when the ratio of the thickness of the concentration chamber to the thickness of the desalting chamber is 1/4.

As can be seen from Table 2, if the concentration chamber is too thin relative to the desalination chamber, the effect of increasing the filling rate of the ion exchanger in the concentration chamber, that is, the voltage reduction during EDI operation can be obtained. Hateful. From the above results, it is clear that the concentration chamber thickness is preferably 1/3 or more of the desalting chamber thickness, and 1/1 or more shows almost the same voltage and no significant difference.
Since the thickening of the concentrating chamber means that the dimension of EDI1 becomes large, the concentrating chamber thickness is optimally in the range of 1/3 to 1/1 of the desalting chamber thickness.

In addition, it explains supplementarily about the measuring method of the moisture content of an ion exchanger.
The water content of the ion exchange resin was measured by a heat drying method. The heat drying method is a method in which a sample is heated to 100 ° C. or higher, which is the boiling point of water, to remove moisture and to obtain moisture from a mass difference before and after heating. Results with the same accuracy as the Karl Fischer method, which has been established as a moisture measurement method, can be easily obtained.
In the present invention, the moisture content was measured using a heat drying moisture meter MX-50 manufactured by A & D Corporation. The specific measurement conditions and moisture content calculation method are as follows.
When 5 g of ion exchange resin as a sample is heated at 110 ° C. and the mass change per minute becomes 0.05% or less, the difference in mass before and after heating is defined as the amount of water contained in the ion exchange resin. The water content was calculated by the following formula.
W = M0 − M1
X = W / M0 x 100
Where M0 (g): ion exchange resin mass,
M1 (g): mass of ion exchange resin after heat drying,
W (g): amount of water contained in the ion exchange resin,
X (%): water content of ion exchange resin,
And

1 EDI
2 Water to be treated water supply line 2a Concentrated water supply line 3 Treated water supply line D Desalination chamber D1, D2 Small desalination chamber C1, C2 Concentration chamber E1, E2 Electrode chamber AEM Anion exchange membrane CEM Cation exchange membrane

Claims (5)

An opposing cathode and anode, an ion exchange membrane defined between the cathode and anode, and a desalting chamber containing the first ion exchanger, and the ion exchange membrane on both sides of the desalting chamber, respectively In an electric deionized water production apparatus for producing demineralized water having a pair of adjacent concentrating chambers,
The first ion exchanger is filled in the desalting chamber in a regenerated form in a wet state with a moisture content exceeding 45% ,
The concentration chamber is filled with a second ion exchanger;
The second ion exchanger is
The electrical deionization is characterized in that the volume of the second ion exchanger taken out from the concentration chamber after the production of demineralized water in the electric deionized water production apparatus is 103% to 125 % of the volume of the concentration chamber. Ionized water production equipment. In the electric deionized water production apparatus according to claim 1,
An electric deionized water production apparatus, wherein the concentration chamber is filled with at least one of an anion exchange resin and a cation exchange resin in the form of a salt as the second ion exchanger. In the electric deionized water production apparatus according to claim 1,
An electric deionized water production apparatus, wherein the concentration chamber is filled with at least one of an anion exchange resin and a cation exchange resin as the second ion exchanger in a dry state. In the electric deionized water production apparatus according to any one of claims 1 to 3,
The length of the concentrating chamber in the energizing direction between the cathode and the anode is 1/3 to 1/1 of the length of the desalting chamber in the energizing direction. Ionized water production equipment. In the electric deionized water production apparatus according to any one of claims 1 to 4,
The demineralization chamber is divided into two chambers by an ion exchange membrane, and at least one of the two chambers is filled with the first ion exchanger, The apparatus for producing electrical deionized water.

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