JP5058217B2 - Electric deionized water production apparatus and deionized water production method - Google Patents

Description

  The present invention relates to an electric deionized water production apparatus and a deionized water production method used in various industries or research facilities such as semiconductor manufacturing field, pharmaceutical manufacturing field, power generation field such as nuclear power and thermal power, food industry and the like.

2. Description of the Related Art Conventionally, as a method for producing deionized water, a method for performing deionization by passing water to be treated through an ion exchange resin is known. However, in this method, when the ion exchange resin is saturated with ions, it is necessary to perform a regeneration treatment with a chemical. In recent years, in order to eliminate such disadvantages in processing operation, an electric deionized water production apparatus (hereinafter referred to as EDI) which does not require regeneration of an ion exchanger by a drug has been put into practical use. This EDI is a deionized water (pure water) production apparatus that combines electrophoresis and electrodialysis. In general EDI, a demineralization chamber filled with an ion exchanger is provided between an anion exchange membrane arranged on the anode side and a cation exchange membrane arranged on the cathode side, and both sides of the demineralization chamber are provided. A concentration chamber is provided. In such EDI, by passing water to be treated into the desalting chamber with a DC voltage applied between the cathode and the anode, ion components in the water to be treated are adsorbed by the ion exchanger. Then, ions are adsorbed to the membrane surface by electrophoresis through the adsorbed ion component, and electrodialyzed through an ion exchange membrane to be removed into concentrated water to produce deionized water.
Conventional typical EDI has a structure in which a plurality of desalting chambers are stacked through a concentration chamber, and a cathode and an anode are arranged at both ends thereof.

Until now, various attempts have been made for the purpose of improving the quality of deionized water obtained by EDI and removing impurity ions with power saving. In the desalting chamber, the filling method and the filling amount of the ion exchanger to be used are determined by the required water quality of the deionized water, so there is a limit in reducing the electrical resistance of the desalting chamber. Therefore, measures are often taken to reduce the electrical resistance of the concentrating chamber. For example, Patent Document 1 discloses a method of reducing the electrical resistance in the concentration chamber by adding and supplying an electrolyte to the concentration chamber.
On the other hand, Patent Document 2 discloses a desalination chamber 2-cell structure in which a desalination chamber is partitioned by an intermediate ion exchange membrane disposed between an anion exchange membrane and a cation exchange membrane. EDI is disclosed. In the production of deionized water in the EDI, water to be treated is introduced into one small demineralization chamber (first small demineralization chamber) while voltage is applied, and then the effluent from the small demineralization chamber is fed to the other. In addition to flowing into the small desalting chamber (second small desalting chamber) (series water flow), the concentrated water is flowed into the concentrating chamber to remove impurity ions in the water to be treated to obtain deionized water. According to the EDI having such a structure, the ion exchanger filled in at least one of the two small desalting chambers is, for example, an anion exchanger alone or a single bed form such as only a cation exchanger. Or, it can be a mixed bed form of anion exchanger and cation exchanger, and it can be set to an optimum thickness for reducing the electric resistance and obtaining high deionization performance for each type of ion exchanger. it can.

Japanese Patent Laid-Open No. 9-24374 Japanese Patent No. 3385553

However, with the conventional techniques, although the electrical resistance in the desalting chamber or the concentration chamber can be reduced, removal of ion components and prevention of scale generation have been insufficient. In addition, there has been a problem that the quality of the deionized water obtained is not stable due to fluctuations in the raw water quality of the treated water. In order to obtain deionized water with high water quality by EDI having a conventional two-cell desalination chamber structure, if the above series water flow is repeated, the differential pressure in the desalination chamber increases and the amount of treated water decreases significantly. Is not practical.
The present invention provides EDI and deionized water that can prevent the generation of scale while ensuring the amount of treated water, and can obtain high quality deionized water (raw water resistance) without being affected by fluctuations in the raw water quality. It aims at the manufacturing method of.

As a result of intensive studies on the reduction of ion removal ability and the generation of scale in the conventional EDI, the present inventor has obtained the following knowledge.
In the conventional two-cell structure of the desalination chamber, depending on the arrangement of the ion exchanger and the intermediate ion exchange membrane, the silica is interposed between the first small desalination chamber and the second small desalination chamber via the intermediate ion exchange membrane. In addition, ions such as carbonic acid and sodium circulate, and there is a problem that it is difficult to discharge to the concentration chamber. For example, when silica circulates, the amount of silica brought in from the water to be treated and the amount of silica brought in from the adjacent desalting chamber are added together, and actually more than silica brought from the water to be treated. The amount of silica is to be treated. As a result, silica cannot be completely removed, leading to problems such as leakage into deionized water and extremely increasing electrical resistance.

Also, the cathode side is the first small desalting chamber, the anode side is the second small desalting chamber, the first small desalting chamber is filled with a cation exchanger, and the second small desalting chamber is filled with an anion exchanger. In the case of the structure, as the cation component is removed in the first small desalting chamber, the pH of the water to be treated is inclined to the acidic side, and the H ⁺ concentration is increased. For this reason, the current efficiency to the cation component to be removed, such as Na ⁺ , Ca ²⁺ , Mg ²⁺ , is reduced, and the cation component cannot be reduced below a certain concentration. And since the 2nd small desalination chamber was not filled with the cation exchanger, there existed a problem that it would leak to deionized water as it is. Furthermore, since the cation component removal ability of the anion exchange membrane constituting the second small desalting chamber is not 100%, the cation component once moved to the concentration chamber is very small, but the second component passes through the anion exchange membrane. It moves back to the small desalination chamber. And since the 2nd small desalination chamber is not filled with the cation exchanger, there exists a phenomenon that a cation component leaks in deionized water as a result.

Also, the anode side is the first small desalting chamber, the cathode side is the second small desalting chamber, the first small desalting chamber is filled with an anion exchanger, and the second small desalting chamber is filled with a cation exchanger. In the case of the structure, as the anion component is removed in the first small desalting chamber, the pH of the water to be treated is inclined toward the alkali side and the OH ⁻ concentration is increased. For this reason, to anion components to be removed such as Cl ⁻ , HCO ₃ ⁻ , CO ₃ ²⁻ , SiO ₂ (silica often takes a special form and is therefore displayed differently from general ions). Current efficiency decreases, and the anion component cannot be reduced below a certain concentration. And since the 2nd small desalination chamber was not filled with the anion exchanger, there existed a problem that it would leak to deionized water as it is. Further, since the anion component removal ability of the cation exchange membrane constituting the second small desalting chamber is not 100%, the anion component once moved to the concentration chamber is very small, but the second component passes through the cation exchange membrane. It moves backward to the two small desalting chambers. And since the anion exchanger is not filled in the second small desalting chamber, there is a phenomenon that an anion component leaks into the deionized water as a result.

Further, in the EDI having a one-cell structure in which the desalting chamber is not divided by the intermediate ion exchange membrane, there are the following problems when a plurality of types of ion exchangers are stacked and filled in the desalting chamber. The stacked cation exchanger single-bed ion exchange layer, anion exchanger single-bed ion exchange layer, and cation exchanger and anion-exchange mixed-bed ion exchange layer have different electrical resistances. . For this reason, there is a phenomenon that electricity flows only to the ion exchange layer having a lower electric resistance, and the ion removal rate in the ion exchange layer having a higher electric resistance is extremely reduced.
In addition, H ⁺ generated at the contact point between the anion exchange membrane and the cation exchanger contributes to regeneration of the cation exchanger, but OH ⁻ moves to the concentration chamber and does not perform any function. is there. This phenomenon will be described with reference to FIG. FIG. 4 is a schematic diagram of an EDI deionization module 220 having a one-cell structure. As shown in FIG. 4, in the deionization module 220, a desalination chamber 224 is formed between the cation exchange membrane 222 on the cathode side and the anion exchange membrane 230 on the anode side, and concentration chambers 234 are formed on both sides of the desalination chamber 224. It is formed and disposed between a cathode chamber and an anode chamber (not shown). In the desalting chamber 224, a desalting layer 224a filled with an anion exchanger and a desalting layer 224b filled with a cation exchanger are formed. When the water to be treated is passed through the desalting chamber 224, H ⁺ is generated on the desalting chamber 224 side and OH ⁻ is generated on the concentrating chamber 234 side at the interface between the anion exchange membrane 230 and the cation exchanger of the desalting layer 224b. To do. H ⁺ generated on the desalting chamber 224 side contributes to the regeneration of the cation exchanger in the desalting layer 224 b, while OH ⁻ generated on the concentration chamber 234 side is not any ion exchanger in the desalting chamber 224. Does not contribute to regeneration. Similarly, OH ⁻ generated at the interface between the cation exchange membrane 222 and the anion exchanger filled in the desalting layer 224a contributes to the regeneration of the anion exchanger of the desalting layer 224a, but is generated on the concentration chamber 234 side. H ⁺ does not contribute to the regeneration of any ion exchanger in the desalting chamber 224.
The present invention has been made based on the above findings.

That is, the EDI of the present invention is partitioned by a cation exchange membrane on the cathode side and an anion exchange membrane on the anode side, and is provided with a plurality of desalting chambers for circulating the water to be treated, and the cation exchange membrane or the anion exchange membrane Concentration chambers through which concentrated water flows are provided on both sides of the desalting chamber through the intermediate, and the desalting chamber is provided with an intermediate ion exchange membrane disposed between the cation exchange membrane and the anion exchange membrane. The first small desalting chamber and the second small desalting chamber partitioned in the thickness direction are formed, and the treated water distributed through any of the first small desalting chambers is distributed, and the treated water is distributed. The first small water desalination chamber is provided with a first water passage means, and the water to be treated which has circulated through the arbitrary second small desalination chamber is supplied to the other first small desalination chamber. It is characterized by the 2nd water flow means to distribute | circulate to a chamber.
Preferably, the second water flow means joins the water to be treated that has circulated through the plurality of second small desalination chambers and causes the merged water to be circulated to the other first small desalination chambers. The concentrated water is circulated through the optional first small desalting chamber and the adjacent concentrating chamber via the anion exchange membrane or the cation exchange membrane, and then the other first small desalting chamber and the anion exchange membrane or the cation. It is more preferable that a means for flowing through the adjacent concentrating chamber through the exchange membrane is provided. The volume ratio between the volume V1 of the arbitrary first small desalting chamber and the volume V2 of the other first small desalting chamber is preferably V1: V2 = 2: 8 to 8: 2. The volume ratio of the volume v1 of the concentrating chamber adjacent to the arbitrary first small desalting chamber to the volume v2 of the concentrating chamber adjacent to the other first small desalting chamber is v1: v2 = 2. Preferably, the first small desalting chamber is formed by filling an anion exchanger in a single bed between the anion exchange membrane and the intermediate ion exchange membrane, More preferably, the second small desalting chamber is formed by filling a cation exchanger in a single-bed form between the cation exchange membrane and the intermediate ion exchange membrane. Exchange membranes, anion exchange membranes, duplex membranes or biofilms with both cation exchange membranes and anion exchange membranes It is preferable that the over La film.

  The method for producing deionized water according to the present invention is a method for producing deionized water using the electric deionized water production apparatus described above, and the treated water circulated through any of the first small demineralization chambers. It distributes and distributes the to-be-processed water distribute | circulates to arbitrary said some said 2nd small desalination chamber, Furthermore, it distribute | circulates to another said 1st small desalination chamber, It is characterized by the above-mentioned.

  ADVANTAGE OF THE INVENTION According to this invention, scale generation | occurrence | production can be prevented, ensuring the processing amount of to-be-processed water, and high-quality deionized water can be obtained (raw water tolerance) without being influenced by the fluctuation | variation of raw | natural water quality.

It is a perspective view of the deionization module group concerning the embodiment of the present invention. It is a schematic diagram of EDI concerning the embodiment of the present invention. It is a schematic diagram of the deionization module concerning embodiment of this invention. It is a schematic diagram of a conventional one-cell EDI deionization module.

  Hereinafter, an example of the EDI of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view of a deionization module group 2 for explaining an embodiment of the present invention. FIG. 2 is a schematic diagram showing an EDI 1 for explaining an embodiment of the present invention. For convenience of explanation, the constituent members of the deionization module group 2 are illustrated with a certain interval, and in the actual deionization module group 2, the constituent members are in close contact.

In EDI 1, the deionization module group 2, the first concentration chamber 20, and the third concentration chamber 140 are provided between the anode chamber 12 and the cathode chamber 142.
The deionization module group 2 includes a first deionization module 4, a second deionization module 6, and a second deionization module 4 provided between the first deionization module 4 and the second deionization module 6. A concentrating chamber 80 is schematically configured. A treated water inflow line 42 and a deionized water outflow line 102 are connected to the deionized module group 2.

  The first deionization module 4 is roughly configured by an anion exchange membrane 30, a frame body 41, an intermediate ion exchange membrane 50, a frame body 61, and a cation exchange membrane 70 that are arranged in order from the anode 10 side. In the first deionization module 4, an opening of the frame body 41 is filled with an anion exchanger in a single-bed form to form a first small desalting chamber 40, and a cation exchanger is simply formed in the opening of the frame body 61. Filled in a floor form, a second small desalting chamber 60 is formed. A first desalting chamber 39 is formed by the first small desalting chamber 40 and the second small desalting chamber 60 adjacent via the intermediate ion exchange membrane 50.

  The second deionization module 6 is schematically configured by an anion exchange membrane 90, a frame body 101, an intermediate ion exchange membrane 110, a frame body 121, and a cation exchange membrane 130 arranged in this order from the anode 10 side. In the second deionization module 6, the opening of the frame body 101 is filled with an anion exchanger in a single bed form to form a first small desalting chamber 100, and the opening of the frame body 121 has a single cation exchanger. Filled in a floor form, a second small desalting chamber 120 is formed. A second desalting chamber 99 is formed by the first small desalting chamber 100 and the second small desalting chamber 120 adjacent via the intermediate ion exchange membrane 110.

  Water passage holes 32, 33, and 34 are formed in the anion exchange membrane 30. A treated water inflow line 42 is connected to the water passage 32. A pipe 35 is connected to the water holes 33 and 34. In the frame body 41, water holes 44, 45, 46 are formed. The frame body 41 is formed with a water passage 47 communicating the water passage hole 44 and the first small desalination chamber 40 and a water passage 48 communicating the water passage hole 45 and the first small desalination chamber 40. Yes. Water passage holes 51 are formed in the intermediate ion exchange membrane 50. Water passage holes 62 and 63 are formed in the frame body 61. The frame body 61 is formed with a water passage 64 communicating the water passage 62 and the second small desalination chamber 60 and a water passage 65 communicating the water passage 63 and the second small desalination chamber 60. ing. Water passage holes 71 and 72 are formed in the cation exchange membrane 70 (the first deionization module 4). Water flow holes 84 and 85 are formed in the frame 81.

  Water passage holes 91 and 92 are formed in the anion exchange membrane 90. Water passage holes 103, 104, 105, and 106 are formed in the frame body 101. The frame body 101 is formed with a water passage 107 that communicates the water passage 104 and the first small desalination chamber 100, and a water passage 108 that communicates the water passage 105 and the first small desalination chamber 100. ing. Water passage holes 111, 112, 113, and 114 are formed in the intermediate ion exchange membrane 110. Water passage holes 123, 124, 125, and 126 are formed in the frame body 121. The frame body 121 is formed with a water passage 127 that connects the water passage hole 123 and the second small desalination chamber 120, and a water passage 128 that communicates the water passage 126 and the second small desalination chamber 120. ing. Water passage holes 132, 133, and 134 are formed in the cation exchange membrane 130. A pipe 135 is connected to the water passage holes 132 and 133. The deionized water outflow line 102 is connected to the water passage hole 134 (the second deionization module 6).

  The “first water passage means” includes water passage holes 33, 34, 45, 46, 51, 62, 71, 84, 91, 103, 111, 123, water passages 48, 64, 127, and piping 35. ing. The “second water passage means” includes water passage holes 63, 72, 85, 92, 104, 106, 112, 114, 124, 126, 132, 133, water passages 65, 107, 128, and piping 135. ing.

The anode 10 and the cathode 150 are connected to a power source (not shown).
In the anode chamber 12, the anode 10, the frame body 11, and the partition film 14 are arranged in order, and the opening of the frame body 11 is filled with an ion exchanger. An electrode water inflow line 16 and an electrode water outflow line 18 are connected to the anode chamber 12.
In the cathode chamber 152, a partition film 154, a frame body 151, and a cathode 150 are arranged in this order from the anode 10 side, and an opening of the frame body 151 is filled with an ion exchanger. An electrode water inflow line 156 and an electrode water outflow line 158 are connected to the cathode chamber 152.

In the first concentration chamber 20, a frame body 21 is disposed between the partition membrane 14 and the anion exchange membrane 30, and the anion exchanger is filled and formed in a single bed form in the opening of the frame body 21. . A concentrated water inflow line 22 and a concentrated water outflow line 23 are connected to the first concentration chamber 20.
In the second concentrating chamber 80, a frame body 81 is disposed between the cation exchange membrane 70 and the anion exchange membrane 90, that is, between the first deionization module 4 and the second deionization module 6. An opening of the body 81 is filled with an anion exchanger in the form of a single bed. A concentrated water inflow line 82 and a concentrated water outflow line 83 are connected to the second concentration chamber 80.
In the third concentrating chamber 140, a frame body 141 is disposed between the partition membrane 154 and the cation exchange membrane 130, and an opening of the frame body 141 is filled with an anion exchanger in a single bed form. . A concentrated water inflow line 142 and a concentrated water outflow line 143 are connected to the third concentration chamber 140.
The concentrated water outflow line 23 and the concentrated water inflow line 82 are connected by a pipe (not shown).

  “Concentrated water is allowed to flow through the optional first small desalting chamber and the adjacent concentrating chamber via the anion exchange membrane or cation exchange membrane, and then the other first small desalting chamber and the anion exchange membrane or cation. The “means for circulating to the adjacent concentrating chamber through the exchange membrane” includes the concentrated water outflow line 23, the concentrated water inflow line 82, and a pipe (not shown) connecting them.

  The ion exchange membrane can be roughly classified into a homogeneous membrane formed by impregnating a raw material monomer solution into a reinforcing body and then polymerized, and a homogenous membrane formed by pulverization and molding together with a polyolefin resin capable of dissolving and molding the ion exchange resin. There are two types of homogeneous membranes. The anion exchange membrane 30, the cation exchange membrane 70, the anion exchange membrane 90, and the cation exchange membrane 130 in the present embodiment are not particularly limited. EDI manufacturing simplicity, quality of water to be treated, and water quality required for deionized water , And can be selected according to the amount of processing.

  The intermediate ion exchange membrane 50 in this embodiment is an anion exchange membrane. The intermediate ion exchange membrane is not particularly limited, and the same ion exchange membrane as that of the anion exchange membrane 30 can be used. The intermediate ion exchange membrane 110 is the same as the intermediate ion exchange membrane 50.

Examples of the anion exchanger filled in the first small desalting chamber 40 include ion exchange resins, ion exchange fibers, monolithic porous ion exchangers, etc. Among them, the most general-purpose ion exchange resins are preferably used. The kind of anion exchange resin is not particularly limited, and examples thereof include strong basic anion exchange resins and weak basic anion exchange resins. For example, as a commercial product, Amberlite (trade name, manufactured by Rohm and Haas) and the like can be mentioned.
The anion exchanger filled in the first small desalting chamber 100 is the same as the anion exchanger filled in the first small desalting chamber 40.

Examples of the cation exchanger filled in the second small desalting chamber 60 include ion exchange resins, ion exchange fibers, monolithic porous ion exchangers, etc. Among them, the most general-purpose ion exchange resins are preferably used. The kind of cation exchange resin is not particularly limited, and examples include strong acid cation exchange resins and weak acid cation exchange resins. For example, as a commercial product, Amberlite (trade name, manufactured by Rohm and Haas) and the like can be mentioned.
The cation exchanger filled in the second small desalting chamber 120 is the same as the cation exchanger filled in the second small desalting chamber 60.

The frame 41 is not particularly limited as long as it has an insulating property and does not leak water to be treated. For example, a frame made of resin such as polyethylene, polypropylene, polyvinyl chloride, ABS, polycarbonate, noryl and the like can be given. be able to.
The thickness of the frame 41 is not particularly limited, and can be set according to the desired thickness of the first small desalting chamber 40. For example, the thickness of the first small desalting chamber 40 is preferably 4 to 16 mm, and more preferably 6 to 12 mm. If it is less than 4 mm, the residence time of the water to be treated cannot be sufficiently secured and the quality of the deionized water may be deteriorated. If it exceeds 16 mm, the first deionization module 4 tends to be difficult to mold.

  The material of the frames 61, 101, 121 is the same as that of the frame 41. The thickness of the frames 61, 101, 121 is the same as the thickness of the frame 41.

The thickness of the first small desalting chamber 40 and the thickness of the second small desalting chamber 60 may be the same or different. The thickness of the first small desalting chamber 100 and the thickness of the second small desalting chamber 120 may be the same or different.
Further, the thickness of the first small desalting chamber 40 and the thickness of the first small desalting chamber 100 may be the same or different. The thickness of the first small desalting chamber 40 and the thickness of the first small desalting chamber 100 can be determined according to the volume required for each small desalting chamber. For example, the thickness of each small desalting chamber is the volume V1 of the first small desalting chamber 40, which is the preceding small desalting chamber, and the volume V2 of the first small desalting chamber 100, which is the subsequent small desalting chamber. Is preferably set so that V1: V2 = 2: 8 to 8: 2. Within the above range, it is possible to suppress the passing jug pressure of the water to be treated in the first small depletion chamber 100, an anionic component in the for-treatment water _{^{(Cl -, HCO 3 -,}} CO 3 2-, SiO 2 , etc. ) Can be removed satisfactorily.

The anode 10 is not particularly limited as long as it functions as an anode. However, when Cl ⁻ is present in the electrode water, chlorine generation occurs in the anode, and therefore, an anode 10 having chlorine resistance is preferable. For example, a noble metal such as platinum, palladium, iridium, or a net-like or plate-like electrode obtained by coating the noble metal on titanium or the like can be given.
The cathode 150 is not particularly limited as long as it functions as a cathode. For example, a plate-like stainless steel, a mesh-like stainless steel, or a noble metal such as platinum, palladium, iridium, or the noble metal is covered with titanium or the like. And a net-like or plate-like electrode.

The material of the frame 11 is the same as that of the frame 41. The thickness of the frame 11 can be determined according to the thickness required for the anode chamber 12. The thickness of the anode chamber 12 is, for example, 0.3 to 10 mm.
Examples of the ion exchanger filled in the anode chamber 12 include ion exchange resins, ion exchange fibers, and monolithic porous ion exchangers, and the most general-purpose ion exchange resin is preferably used. The packing form of the ion exchanger can be determined in consideration of the quality of the water to be treated, for example, a single bed form of an anion exchanger, a single bed form of a cation exchanger, or a mixed bed of an anion exchanger and a cation exchanger. A form or a double bed form is mentioned.

  The material of the frame 151 is the same as that of the frame 41. The thickness of the frame 151 can be determined according to the thickness required for the cathode chamber 152. The thickness of the cathode chamber 152 is the same as the thickness of the anode chamber 12. The ion exchanger filled in the cathode chamber 152 is the same as the ion exchanger filled in the anode chamber 12.

  The partition membrane 14 is not particularly limited as long as it is an ion exchange membrane, and can be selected in consideration of the quality of the water to be treated, the operating conditions of the EDI 1, and the like. For example, a cation exchange membrane or an anion exchange membrane can be selected. The partition film 154 is the same as the partition film 14.

The anion exchanger filled in the first concentration chamber 20 is the same as the anion exchanger filled in the first small desalting chamber 40. By using the single bed form of the anion exchanger, an anion exchanger layer in contact with the anion exchange membrane 30 is formed, and the movement of the anion component from the first small desalting chamber 40 to the first concentration chamber 20 is promoted. Because.
The material of the frame body 21 is the same as that of the frame body 41. The thickness of the frame body 21 can be determined according to the thickness required for the first concentration chamber 20. The thickness of the first concentration chamber 20 is, for example, 3 to 10 mm.

The anion exchanger filled in the second concentration chamber 80 is the same as the anion exchanger filled in the first small desalting chamber 40. By making a single bed form of the anion exchanger, an anion exchanger layer in contact with the anion exchange membrane 90 is formed, promoting the movement of the anion component from the first small desalting chamber 100 to the second concentration chamber 80, It is possible to prevent the anion component from being present at a high concentration on the surface of the anion exchange membrane 90. As a result, the hardness components (Ca ²⁺ , Mg ^2+, etc.) that have moved from the second small desalting chamber 60 to the second concentration chamber 80 do not come into contact with the high-concentration anion components on the anion exchange membrane 90 surface. Occurrence can be prevented.
The material of the frame 81 is the same as that of the frame 41. The thickness of the frame 81 can be determined according to the thickness required for the second concentration chamber 80. The thickness of the second concentration chamber 80 is, for example, 3 to 10 mm.

The anion exchanger filled in the third concentration chamber 140 is the same as the anion exchanger filled in the first small desalting chamber 40.
The material of the frame body 141 is the same as that of the frame body 41. The thickness of the frame 141 can be determined according to the thickness required for the third concentration chamber 140. The thickness of the third concentration chamber 140 is, for example, 3 to 10 mm.

  The thickness of the first concentration chamber 20, the thickness of the second concentration chamber 80, and the thickness of the third concentration chamber 140 may be the same or different from each other. The thickness of each concentration chamber can be determined according to the volume required for each concentration chamber. For example, the thicknesses of the first concentration chamber 20 and the second concentration chamber 80 are the same as the volume v1 of the first concentration chamber 20 that is the preceding concentration chamber and the second concentration chamber 80 that is the subsequent concentration chamber. The volume ratio with the volume v2 is preferably set to be 2: 8 to 8: 2. If it is in the said range, the water flow differential pressure | voltage in the 2nd concentration chamber 80 can be suppressed, and sufficient amount of concentrated water can be flowed. As a result, the movement of the anion component from the first small desalting chamber 100 to the second concentration chamber 80 can be promoted.

  Next, a method for producing deionized water using EDI1 will be described. In the method for producing deionized water of the present invention, the turbid components of industrial water and well water are removed by a turbidity membrane, and the water treated with a reverse osmosis (RO) membrane is treated as deionized water. Thus, deionized water is obtained.

First, electrode water is caused to flow from the electrode water inflow line 16 to the anode chamber 12, electrode water is caused to flow from the electrode water inflow line 156 to the cathode chamber 152, and a DC voltage is applied between the anode 10 and the cathode 150. The electrode water flowing into the anode chamber 12 flows in an upward flow while diffusing through the ion exchanger in the anode chamber 12. During this time, the electrode water takes in Cl ₂ , O _{2 and the} like generated from the anode 10 and flows out from the electrode water outflow line 18. The electrode water flowing into the cathode chamber 150 flows in an upward flow while diffusing through the ion exchanger in the cathode chamber 150. During this time, the electrode water takes in H ₂ or the like generated from the cathode 150 and flows out from the electrode water outflow line 158.

Examples of the electrode water include water from the same water source as the water to be treated, deionized water, and pure water. The amount of electrode water supplied to the anode chamber 10 is preferably determined according to the applied voltage or the like. For example, it is determined in the range of 5 to 200 L / h, preferably 30 to 100 L / h. If the supply amount of the electrode water is too small, it will be difficult to sufficiently discharge the generated O ₂ and Cl ₂ gas, and if the supply amount of the electrode water is too large, the recovery rate is lowered, which is not preferable. The supply amount of the electrode water to the cathode chamber 150 is the same as the supply amount of the electrode chamber to the anode chamber 10.
The current to be applied is determined in consideration of the quality of the water to be treated and the scale of EDI1.

  Next, the concentrated water is circulated from the concentrated water inflow line 22 to the first concentrating chamber 20, and the concentrated water is circulated from the concentrated water inflow line 142 to the third concentrating chamber 140. Examples of the concentrated water include water from the same water source as the water to be treated, deionized water, and pure water.

  The amount of concentrated water supplied to EDI 1 can be determined in consideration of the ability of EDI 1, the quality of the water to be treated and the amount of treatment. If the supply amount of concentrated water is too small, uneven concentration diffusion of ions moved to each concentration chamber occurs, and for example, the concentration polarization layer on the surface of the anion exchange membrane 90 becomes thick, and scale may be generated. On the other hand, when the supply amount of concentrated water is too large, the recovery rate of deionized water is not preferable.

  From such a viewpoint, for example, the amount of concentrated water supplied to EDI 1 is preferably set so that the concentration ratio represented by the following formula (1) is 3 to 20. In the following formula (1), “the amount of concentrated water supplied to EDI” is the sum of the amount of concentrated water supplied to the first concentrating chamber 20 and the amount of concentrated water supplied to the third concentrating chamber 140. In addition, the concentration ratio according to the following equation (1) is defined on the assumption that the same raw water is used for the treated water and the concentrated water, and that all the ionic components in the treated water are transferred to the concentration chamber.

  Concentration rate = (Amount of treated water supplied to EDI + Amount of concentrated water supplied to EDI) ÷ Amount of concentrated water supplied to EDI (1)

The treated water is supplied to the deionized module group 2 from the treated water inflow line 42. The supply amount of the water to be treated to the deionization module group 2 can be determined in consideration of the ability of the EDI 1 and the quality of the water to be treated. The supply amount of the water to be treated is preferably adjusted so that the space velocity (SV) in the first small desalting chamber 40 is SV = 30 to 300 L / L · h ⁻¹ . If the SV is too high, the ion removal performance decreases, or the water flow differential pressure increases due to an increase in the liquid flow rate (LV) generated with the increase in the SV, so that the first deionization module 4 and the second deionization are performed. This is not preferable because the module 6 may be damaged or operation may be difficult. On the other hand, if the SV is too low, the flow distribution to the second small demineralization chamber 60 and the second small demineralization chamber 100 is not properly performed, and the deionization module with sufficient deionization treatment and the deionization treatment are insufficient. May cause adverse effects on the performance of the EDI 1 as a whole.

Note that SV is a flow rate (L) circulated in one hour with respect to the unit volume (L) of the ion exchanger, and is represented by L / L · h ⁻¹ (the same applies hereinafter). Moreover, LV is a flow rate per unit area, and is a linear velocity expressed in m / h.

The supplied treated water flows through the water passage holes 32 and 44 and the water passage 47 in order, and flows into the first small desalting chamber 40. The treated water that has flowed into the first small desalting chamber 40 flows while diffusing through the anion exchanger in the first small desalting chamber 40. During this time, anion components such as Cl ⁻ and HCO ₃ ^{— in the} water to be treated are adsorbed by the anion exchanger. The adsorbed anion component is attracted to the anode 10, passes through the anion exchange membrane 30, and moves to the first concentration chamber 20. Here, in the first small desalting chamber 40, when the removal of the anion component proceeds, the pH of the water to be treated shifts to the alkaline side, and the concentration of OH ⁻ that is a competing ion of the anion component increases. For this reason, the current efficiency with respect to an anion component falls, and it becomes difficult for the density | concentration of the anion component in to-be-processed water to reach below a fixed concentration. As a result, the to-be-processed water which circulated through the first small desalting chamber 40 is in a state where a certain amount of anion component remains.

The treated water that has circulated through the first small desalination chamber 40 circulates through the water passage 48, the water passage holes 45 and 33, the pipe 35, and the water passage holes 34, 46, and 51 in this order, and reaches the water passage hole 62. Part of the water to be treated that has reached the water passage hole 62 flows through the water passage 64 and flows into the second small desalting chamber 60. The treated water that has flowed into the second small desalting chamber 60 flows while diffusing through the cation exchanger in the second small desalting chamber 60. During this time, cation components such as Na ⁺ and Ca ^{2+ in the} water to be treated are adsorbed by the cation exchanger. The adsorbed cation component is attracted to the cathode 150, passes through the cation exchange membrane 70, and moves to the second concentration chamber 80. Here, since the pH of the water to be treated that has flowed into the second small desalting chamber 60 has shifted to the alkaline side, the H ⁺ concentration, which is a competitive ion of the cation component, is low. For this reason, the removal of a cation component is performed favorably. The treated water that has circulated through the second small desalination chamber 60 circulates through the water passage 65 and the water passage holes 63, 72, 85, 92, 106, 114 in order, and reaches the water passage hole 126. In addition, in the stage which distribute | circulated the 2nd small desalination chamber 60, pH of to-be-processed water is a neutral area | region.

Further, OH ⁻ and H ⁺ are generated by water decomposition at the contact point between the intermediate ion exchange membrane 50 and the cation exchanger. OH ⁻ generated by water splitting passes through the intermediate ion exchange membrane 50 and moves to the first small desalting chamber 40, and is used for regeneration of the anion exchanger in the first small desalting chamber 40. H ⁺ generated by water splitting is used for regeneration of the cation exchanger in the second small desalting chamber 60.

  Other part of the water to be treated that has reached the water passage 62 further flows through the water passages 71, 84, 91, 103, 111, 123, and the water passage 127 in order, and flows into the second small desalination chamber 120. To do. The treated water that has flowed into the second small desalting chamber 120 flows while diffusing through the cation exchanger in the second small desalting chamber 120. During this time, the cation component in the water to be treated is adsorbed by the cation exchanger. The adsorbed cation component is attracted to the cathode 150, passes through the cation exchange membrane 130, and moves to the third concentration chamber 140. The to-be-processed water which flowed into the 2nd small desalination chamber 120 has transferred to the alkalinity similarly to the to-be-processed water which flowed into the 2nd small desalination chamber 60. For this reason, the to-be-processed water which distribute | circulated the 2nd small desalination chamber 120 becomes a neutral area | region while a cationic component is removed favorably. The treated water that has circulated through the second small desalination chamber 120 circulates through the water passage 128 and reaches the water passage hole 126. In this way, the water to be treated flowing through the second small desalting chamber 60 and the water to be treated flowing through the second small desalting chamber 120 merge at the water passage hole 126.

Further, at the contact point between the intermediate ion exchange membrane 110 and the cation exchanger, OH ⁻ and H ⁺ are generated by water decomposition. OH ⁻ generated by water splitting passes through the intermediate ion exchange membrane 110 and moves to the first small desalting chamber 100, and is used for regeneration of the anion exchanger in the first small desalting chamber 100. H ⁺ generated by water splitting is used for regeneration of the cation exchanger in the second small desalting chamber 120.

  The treated water that has joined at the water passage hole 126 flows in order through the water passage hole 133, the pipe 135, the water passage holes 132, 124, 112, 104, and the water passage 107, and flows into the first small desalination chamber 100. The treated water that has flowed into the first small desalting chamber 100 flows while diffusing through the anion exchanger in the first small desalting chamber 100. During this time, the anion component in the water to be treated is adsorbed by the anion exchanger. The adsorbed anion component is attracted to the anode 10, passes through the anion exchange membrane 90, and moves to the second concentration chamber 80. Here, since most of the anion component of the water to be treated that has flowed into the first small desalination chamber 100 has been removed in advance in the first small desalination chamber 40, even if the removal of the anion component proceeds, The pH is maintained. For this reason, the remaining anion component can be removed satisfactorily. The treated water flows through the first small desalting chamber 100 and becomes deionized water. The deionized water flows through the water passage 108 and the water passage holes 105, 113, 125, 134 in order, and flows out from the deionized water outflow line 102.

The concentrated water that has flowed into the first concentration chamber 20 flows while diffusing in the ion exchanger of the first concentration chamber 20 in an upward flow. During this time, the concentrated water takes in the anion component moved from the first small desalting chamber 40 to the first concentration chamber 20 and flows out from the concentrated water outflow line 23.
In addition, it is assumed that the to-be-processed water which flows into the 1st small desalination chamber 40 contains many types of anion components. When such treated water flows through the first small desalting chamber 40, HCO ₃ ⁻ , CO ₃ ⁻ , Cl ^{− and the} like are preferentially adsorbed on the anion exchanger and move to the first concentration chamber 20. On the other hand, there is little movement of OH ⁻ to the first concentration chamber 20. For this reason, the concentrated water flowing through the first concentration chamber 20 includes the concentrated water outflow line 23 and the concentrated water inflow line 82 in a state containing more HCO ₃ ⁻ , CO ₃ ⁻ , Cl ^{− and the} like than OH ^−. It flows and flows into the second concentration chamber 80.

The concentrated water that has flowed into the second concentration chamber 80 flows in an upward flow while diffusing through the ion exchanger in the second concentration chamber 80. During this time, the concentrated water takes in the cation component moved from the second small desalting chamber 60 to the second concentration chamber 80 and the anion component moved from the first small desalting chamber 100 to the second concentration chamber 80. Then, it flows out from the concentrated water outflow line 83.
The concentrated water flowing through the second concentration chamber 80 contains the anion component removed in the first small desalting chamber 40 or the second small desalting chamber 80. Of these anion components, HCO ₃ ⁻ and CO ₃ ⁻ may be gasified, permeate the cation exchange membrane 70, and move to the second small desalting chamber 60. As described above, the HCO ₃ ⁻ and CO ₃ ⁻ moved from the second concentrating chamber 80 to the second small desalting chamber 60 and mixed into the water to be treated further pass the water to be treated through the first small desalting chamber 100. Can be removed.

  The concentrated water flowing into the third concentrating chamber 140 flows in an upward flow while diffusing through the ion exchanger in the third concentrating chamber 140. During this time, the concentrated water takes in the cation component moved from the second small desalting chamber 120 to the third concentration chamber 140 and flows out from the concentrated water outflow line 143.

As described above, in EDI 1, the treated water is circulated through the first small desalting chamber 40 to remove the anion component, and then the treated water is distributed to the second small desalting chamber 60 or the second small desalting chamber 120. Then, the cation component is removed by circulation, and the water to be treated that has circulated through each second small desalination chamber is circulated through the first small desalination chamber 100 to remove the anion component again. For this reason, the deionized water from which the anion component and cation component in the to-be-processed water were removed highly can be manufactured.
In addition, in order to distribute the treated water flowing through the first small desalting chamber 40 to the second small desalting chamber 60 and the second small desalting chamber 120, the second small desalting chamber 60 or the second small desalting chamber 60 is used. An increase in water flow differential pressure in the salt chamber 120 can be suppressed. By suppressing the increase in the water flow differential pressure, the residence time of the water to be treated in each second small desalting chamber can be made sufficient, and the cation component can be favorably removed. Furthermore, deionized water having high water quality can be stably produced without reducing the amount of water to be treated in EDI 1 by suppressing the increase in water flow differential pressure.

OH ⁻ and H ⁺ generated at the contact point between the intermediate ion exchange membrane 50 and the cation exchanger in the second small desalting chamber 60 are the anion exchanger and the second small desalting chamber in the first small desalting chamber 40, respectively. Since it contributes to the regeneration of the 60 cation exchanger, there is little waste in terms of current efficiency. Further, OH ⁻ and H ⁺ generated by setting the intermediate ion exchange membrane 110 and the cation exchanger in the second small desalting chamber 120 are the anion exchanger and the second small desalting in the first small desalting chamber 100, respectively. Since it contributes to the regeneration of the cation exchanger in the salt chamber 120, there is little waste in terms of current efficiency. This point will be described with reference to FIG. FIG. 3 is a schematic diagram for explaining the flow of ions in the deionization module 4. As shown in FIG. 3, when the water to be treated is circulated through the second small desalting chamber 60, the contact (interface) between the intermediate ion exchange membrane 50 and the cation exchanger in the second small desalting chamber 60 is the first. OH ⁻ is generated on the small desalting chamber 40 side, and H ⁺ is generated on the second small desalting chamber 60 side. The OH ⁻ generated on the first small desalting chamber 40 side contributes to the regeneration of the anion exchanger in the first small desalting chamber 40. The excess OH ^{− in} the regeneration of the anion exchanger moves to the first concentration chamber 20. H ⁺ generated on the second small desalting chamber 60 side contributes to the regeneration of the cation exchanger in the second small desalting chamber 60. The excess H ^{+ in} the regeneration of the cation exchanger moves to the second concentration chamber 80.

In general, when a high concentration of OH ⁻ and hardness components such as Ca ²⁺ and Mg ²⁺ are present, a scale is likely to be generated. Most of the water to be treated that has flowed into the first small desalting chamber 100, such as HCO ₃ ⁻ , CO ₃ ⁻ , and Cl ⁻ , is removed when it flows through the first small desalting chamber 40. For this reason, most of the anion component moving from the first small desalting chamber 100 to the second concentration chamber 80 is OH ⁻ . For this reason, in EDI 1, the concentrated component containing a large amount of HCO ₃ ⁻ , CO ₃ ⁻ , Cl ^{− and the} like is circulated through the first concentration chamber 20 to the second concentration chamber 80. The frequency of encountering OH ⁻ can be reduced, and scale generation on the anion exchange membrane 90 surface can be prevented.

  The first small desalting chambers 40 and 100 are filled with an anion exchanger in a single bed form, and the second small desalting chambers 60 and 120 are filled with a cation exchanger in a single bed form. For this reason, in each 1st small desalination chamber and each 2nd small desalination chamber, the bias | inclination of an electric current is prevented and current efficiency can be improved.

  As described above, according to the present invention, the conventional EDI having a two-cell structure for the desalination chamber is used, while ensuring the treatment amount of the water to be treated and preventing the occurrence of scale, it is not affected by the fluctuation of the raw water quality. In addition, deionized water with a high water quality can be obtained.

The present invention is not limited to the embodiment described above.
In the above-described embodiment, one deionization module group 2 is provided in the EDI 1, but, for example, two or more deionization module groups 2 may be provided. When two or more deionization module groups 2 are provided, each of the deionization module groups 2 may produce deionized water individually, or the two or more deionization module groups 2 are connected in series to remove water. Ionic water may be produced.

  In the above-described embodiment, the deionization module group 2 includes two deionization modules, the first deionization module 4 and the second deionization module 6. However, the deionization module group may be configured by three or more deionization modules.

When the deionization module group is configured by three or more deionization modules, the number of the first small demineralization chambers through which the water to be treated is first circulated may be one or two or more. . In addition, the number of first small desalination chambers in the front stage through which the water to be treated is first circulated and the number of first small desalination chambers in the rear stage are the total volume V1 of the first small desalination chamber in the front stage and the subsequent stage. It is preferable that the volume ratio with the total volume V2 of the first small desalting chamber is V1: V2 = 2: 8 to 8: 2.
In addition, the number of pre-concentration chambers and the number of post-concentration chambers through which concentrated water is first circulated is the total volume v1 of the pre-concentration chamber and the total volume v2 of the post-concentration chamber. It is preferable to set so that v1: v2 = 2: 8 to 8: 2.

In the above-described embodiment, the intermediate ion exchange membranes 50 and 110 are anion exchange membranes. The present invention is not limited to this, and the type of the intermediate ion exchange membranes 50 and 110 can be selected in consideration of the quality of water to be treated, the quality of water required for deionized water, and the like. Examples of the intermediate ion exchange membranes 50 and 110 include an anion exchange membrane, a single cation exchange membrane, a composite membrane in which both an anion exchange membrane and a cation exchange membrane are arranged, or a bipolar membrane. However, when the water to be treated contains a lot of anion components, the intermediate ion exchange membranes 50 and 110 are preferably single membranes of anion exchange membranes. For example, by making the intermediate ion exchange membrane 50 a single membrane of an anion exchange membrane, anion components (Cl ⁻ , HCO ₃ ⁻ , CO ₃ ²⁻ , SiO ²⁾ in the water to be treated flowing through the second small desalting chamber 60. _This is because the anion component can be removed to a high degree by moving ₂ ) to the first small desalting chamber 40.
Different types of ion exchange membranes may be used for the intermediate ion exchange membrane 50 and the intermediate ion exchange membrane 110.

  In the above-described embodiment, the first small desalting chambers 40 and 100 are all in the single bed form of the anion exchanger. For example, the single bed form of the cation exchanger, or the mixed bed of the anion exchanger and the cation exchange. It may be in the form or a multiple floor form. However, when the first small desalting chambers 40 and 100 are formed on the anode 10 side as in the above-described embodiment, a single bed form of an anion exchanger or a mixed bed form of an anion exchanger and cation exchange Or a double bed form is preferable and the single bed form of an anion exchanger is more preferable.

  In the above-described embodiment, each of the second small desalting chambers 60 and 120 is a single bed form of the cation exchanger, but for example, a single bed form of the anion exchanger, a mixture of the anion exchanger and the cation exchanger. A floor form or a double floor form may be sufficient. However, when the second small desalting chambers 60 and 120 are formed on the cathode side as in the above-described embodiment, a single bed form of the cation exchanger or a mixed bed form of anion exchanger and cation exchange or A multiple bed form is preferred, and a single bed form of the cation exchanger is more preferred.

In the above embodiment, the small desalination chamber formed between the anion exchange membrane and the intermediate ion exchange membrane is the first small desalination chamber, and the small desalination chamber formed between the cation exchange membrane and the intermediate exchange membrane is used. The salt chamber is the second small desalination chamber. However, the present invention is not limited to this, for example, a small desalting chamber formed between the anion exchange membrane and the intermediate ion exchange membrane is used as the second small desalting chamber, and the cation exchange membrane and the intermediate exchange membrane are The small desalting chamber formed between the two may be used as the first small desalting chamber. The position where the first small desalting chamber and the second small desalting chamber are formed can be determined in consideration of the quality of the water to be treated.
When water to be treated contains a large amount of anion components as impurities compared to the cation component, the small desalting chamber formed between the anion exchange membrane and the intermediate ion exchange membrane is the first small size. It is preferable that the desalting chamber is a small desalting chamber formed between the cation exchange membrane and the intermediate exchange membrane.

  In the above-described embodiment, the flow directions of the water to be treated in the first small desalting chambers 40 and 100 and the second small desalting chambers 60 and 120 are all downward. However, the present invention is not limited to this, and the flow direction of the water to be treated in the small desalting chamber may be all ascending flow or may be different for each small desalting chamber.

  In the above-described embodiment, the first water passage means is constituted by the water passage holes and water passages formed in the deionization module group 2 and the piping provided in the deionization module group 2. However, the 1st water flow means may be comprised by piping provided in the exterior of the deionization module group 2, for example. Moreover, the 2nd water flow means may be comprised by the piping provided in the exterior of the deionization module group 2 similarly to the 1st water flow means.

  In the above-described embodiment, the first concentration chamber 20, the second concentration chamber 80, and the third concentration chamber 140 are all in a single-bed form of an anion exchanger. However, the ion exchanger filled in each concentrating chamber is not limited to a single bed form of an anion exchanger, for example, a single bed form of a cation exchanger, a mixed bed form of an anion exchanger and a cation exchanger, or multiple beds. Form may be sufficient. In addition, each concentration chamber may be provided with a spacer or the like without being filled with an ion exchanger. However, from the viewpoint of preventing the occurrence of scale in each concentration chamber, it is preferable to fill the anion exchanger in a single bed form.

  In the above-described embodiment, the flow direction of the concentrated water in each concentration chamber is an upward flow. However, the present invention is not limited to this. For example, the flow direction of the concentrated water in all the concentration chambers may be a downward flow or may be different in each concentration chamber.

  In the above-described embodiment, the concentrated water flowing through the first concentration chamber 20 is circulated to the second concentration chamber 80, and the concentrated water is circulated independently to the third concentration chamber 120. However, the present invention is not limited to this, and for example, the concentrated water may be circulated independently in the first concentration chamber 20 and the second concentration chamber 80, or the concentration that is circulated through the second concentration chamber 80. Water may be circulated through the third concentration chamber 140. Further, for example, the concentrated water flowing through the first concentration chamber 20 may be distributed and distributed to the second concentration chamber 80 and the third concentration chamber 140, or the first concentration chamber 20 and the second concentration chamber 20 may be distributed. The concentrated water circulated independently from the concentration chamber 80 may be merged, and the merged concentrated water may be circulated to the third concentration chamber 140. However, from the viewpoint of preventing the generation of scale, as in the above-described embodiment, the concentration that circulates through the first concentration chamber 20 adjacent to the first small desalination chamber and the anion exchange membrane or the cation exchange membrane through the previous stage. It is preferable to circulate water to the second concentration chamber 80 adjacent to the first small desalting chamber in the subsequent stage via the anion exchange membrane or the cation exchange membrane.

  In the embodiment described above, the anode chamber 12 is filled with the ion exchanger. However, for example, a spacer or the like may be disposed without filling the ion exchanger. Similarly, the cathode chamber 152 may be provided with a spacer or the like without being filled with the ion exchanger.

  In the embodiment described above, the flow direction of the electrode water in the anode chamber 12 and the cathode chamber 152 is an upward flow. However, the present invention is not limited to this. For example, the flow direction of the electrode water in the anode chamber 12 and the cathode chamber 152 may be a downward flow, or the flow of electrode water between the anode chamber 12 and the cathode chamber 152. The directions may be different.

  In the above-described embodiment, the three-stage treatment in which the water to be treated flows from the first small desalting chamber 40 to the second small desalting chamber 60 or the second small desalting chamber 120 and then the first small desalting chamber 100 in this order. It is said that. However, the present invention is not limited to this. For example, when two or more deionization module groups 2 are provided, or when a deionization module group is configured by three or more deionization modules, a three-stage process is performed. Further, the water to be treated may be circulated to another desalting chamber at the former stage or the latter stage. However, from the viewpoint of suppressing the increase in the water flow differential pressure in EDI and efficiently producing deionized water, it is preferable to use a three-stage treatment as in the above-described embodiment.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, it is not limited to an Example.
<Conductivity / specific resistance>
For water quality evaluation, conductivity and specific resistance were used. In the case of water containing no impurities, the theoretical value of conductivity in water at 25 ° C. is 0.055 μS / cm, and the theoretical value of specific resistance is 18.2 MΩ · cm. As for the water quality of deionized water, the specific resistance approaches 18.2 MΩ · cm, and the higher, the higher the water quality. Deionized water quality was evaluated with specific resistance.
The conductivity was measured using a conductivity meter (873CC, manufactured by FOXBORO). The specific resistance was measured using a specific resistance meter (873RS, manufactured by FOXBORO).

<Silica concentration>
Water quality was evaluated by measuring the silica concentration, which is an index of EDI processing performance. The silica concentration was measured by molybdenum blue absorptiometry using a spectrophotometer (U-3010, manufactured by Hitachi High-Technology Corporation).

<Desalination chamber differential pressure>
The demineralization chamber differential pressure was measured as the EDI water flow differential pressure in each example. The demineralization chamber differential pressure is measured using a pressure gauge (GS50, manufactured by Nagano Keiki Co., Ltd.). (P2) was measured and calculated according to (2) below.

  Desalination chamber differential pressure = P1-P2 (2)

Example 1
EDI-A similar to EDI1 shown in FIG. EDI-A is provided with one deion module group consisting of four deion modules.
EDI-A distributes the water to be treated to the two first small desalination chambers (downstream first small desalination chamber) and then distributes them to the four second small desalination chambers. Circulate, and then the treated water that has circulated through the four second small desalination chambers is merged and distributed again to the remaining two first small desalination chambers (the first small desalination chamber in the subsequent stage) A structure that circulates in a stream. In addition, EDI-A allows the concentrated water to flow in an upward flow to the two adjacent concentration chambers through the first small desalination chamber and the anion exchange membrane, and then to the first small desalination chamber in the subsequent stage. The structure was distributed to two adjacent concentrating chambers and the remaining concentrating chambers via an anion exchange membrane and circulated in an upward flow. The electrode water was circulated in the cathode chamber in an upward flow and then circulated in the anode chamber in an upward flow.
Using the obtained EDI-A, deionized water was continuously produced for 2000 hours under the following operating conditions. 2000 hours after the start of operation, the specific resistance of the obtained deionized water, the silica concentration, the pressure difference in the desalting chamber, and the average applied voltage of EDI-A were measured, and the results are shown in Table 1.
The hardness of the water to be treated is a value measured with an atomic absorption spectrophotometer (SpectrAA, manufactured by Varian), and the total carbonic acid concentration is a value measured with a wet ultraviolet oxidation TOC analyzer (model 900, manufactured by SIEVERS). It is.

<EDI-A specifications>
(1) Cation exchange membrane: Astom Co., Ltd. (2) Intermediate ion exchange membrane: Astom Co., Ltd. anion exchange membrane (3) Anion exchange membrane: Astom Co., Ltd. (4) First small desalting chamber thickness: 9 mm
(5) Second small desalination chamber thickness: 9 mm
(6) Desalination chamber dimensions: 280mm wide x 400mm high
(7) First small desalination chamber filled ion exchanger: anion exchange resin (Rohm and Haas Co., Ltd.) single bed form (8) Second small desalination chamber filled ion exchanger: Cation exchange resin (Rohm and Haas) (Made by Haas) Single bed form (9) Concentrated chamber filled ion exchanger: Anion exchange resin (made by Rohm and Haas) Single bed form (10) Number of first small desalination chambers in the previous stage: 2 (11 ) Number of first small desalination chambers: 2

<Operating conditions>
(1) Water to be treated: Water obtained by treating industrial water with a reverse osmosis membrane device (2) Conductivity of water to be treated: 7.7 μS / cm
(3) Specific resistance of water to be treated: 0.13 MΩ · cm
(4) Silica concentration in treated water: 889 μg / L
(5) Hardness to be treated: 0.27 mg CaCO ₃ / L
(6) Total carbonic acid concentration in treated water: 8.2 mg CO ₂ / L
(7) Amount of treated water supplied: 0.4 m ³ / h
(8) Concentrated water supply: 0.1 m ³ / h
(9) Amount of electrode water supplied: 10 L / h
(10) Operating current value: 2.5A

(Example 2)
EDI-B was produced with the same specifications as in Example 1, except that the number of first small desalination chambers in the front stage was three and the number of first small desalination chambers in the rear stage was one. Deionized water was produced under the same conditions as in Example 1 using EDI-B. After 2000 hours from the start of operation, the specific resistance of the obtained deionized water, the silica concentration, the pressure difference in the desalting chamber, and the average applied voltage of EDI-B were measured, and the results are shown in Table 1.

(Comparative Example 1)
After deionized water is distributed to the four first small desalting chambers and circulated in the downward flow, the treated water that has circulated through the four first small desalting chambers is merged and again the four second small desalting chambers. The structure was distributed to the chamber and distributed in a downward flow. In addition, the concentrated water is circulated in an upward flow independently in all the concentration chambers. Except for these changes, EDI-C was obtained with the same specifications as in Example 1. Deionized water was produced under the same conditions as in Example 1 using EDI-C. 2000 hours after the start of operation, the specific resistance of the obtained deionized water, the silica concentration, the pressure difference in the desalting chamber, and the average applied voltage of EDI-C were measured, and the results are shown in Table 1.

(Comparative Example 2)
For each deionization module, the water to be treated is circulated in the first small desalination chamber in a downward flow, and the water to be treated that has circulated in the first small desalination chamber is circulated in the downward flow to the second small desalination chamber. It was. Furthermore, it was set as the structure which passes deionized water in series through four deionization modules. Except for these changes, EDI-D was manufactured with the same specifications as in Example 1. Deionized water was produced under the same conditions as in Example 1 using EDI-D. In EDI-D, the demineralization chamber differential pressure became 0.6 MPa or more immediately after the start of operation, and deionized water could not be produced. In this comparative example, the specific resistance of deionized water obtained immediately after the start of operation, the silica concentration, the desalting chamber differential pressure, and the average applied voltage of EDI-D were measured, and the results are shown in Table 1 as reference values.

As shown in Examples 1 and 2 and Comparative Examples 1 and 2 in Table 1, the difference in average applied voltage in each example was small.
Example 1 in which two first small desalination chambers in the front stage and two first small desalination chambers in the rear stage and the water to be treated was circulated had a specific resistance of 16.6 MΩ · cm, a silica concentration of 21 μg / An extremely high quality deionized water of L was obtained. Example 2 in which three first small desalination chambers in the front stage and one first small desalination chamber in the rear stage and the water to be treated was circulated had a specific resistance of 17.1 MΩ · cm, a silica concentration of 13 μg / Deionized water with a higher quality than that of Example 1 was obtained.
On the other hand, in Comparative Example 2 in which the water to be treated was circulated independently through the four deionization modules, deionized water having a low water quality with a specific resistance of 2.2 and a silica concentration of 750 μg / L was obtained. In Comparative Example 4 in which water was passed through four deionization modules in series, a high water quality with a specific resistance of 17.8 MΩ · cm and a silica concentration of 7 μg / L was obtained.
In addition, in Examples 1 and 2 and Comparative Example 1, the desalting chamber differential pressure was less than 0.2 MPa, which was practical. On the other hand, in Comparative Example 2, the demineralization chamber differential pressure became 0.6 MPa or more immediately after the start of production of deionized water, and could not be operated.
When EDI-A and EDI-B 2000 hours after the start of operation were disassembled and visually observed, no generation of scale was observed.

  Based on the above results, the water to be treated that circulated through the first small desalination chamber in the previous stage is distributed and circulated to a plurality of second small desalination chambers, and the water to be treated that has circulated through the second small desalination chamber is further separated. It was found that the EDI of the present invention circulated in the first small desalting chamber can obtain deionized water with high water quality while maintaining the treatment amount, and can well prevent scale generation.

DESCRIPTION OF SYMBOLS 1 Electric deionized water production apparatus 10 Anode 20, 80, 140, 234 Concentration chamber 30, 90, 230 Anion exchange membrane 39, 99, 224 Desalination chamber 40, 100 First small demineralization chamber 50, 110 Intermediate ion exchange Membrane 60, 120 Second small desalting chamber 70, 130, 222 Cation exchange membrane 150 Cathode

Claims (8)

Partitioned by a cation exchange membrane on the cathode side and an anion exchange membrane on the anode side, and provided with a plurality of desalting chambers for circulating the water to be treated,
A concentration chamber for circulating concentrated water is provided on both sides of the desalting chamber via the cation exchange membrane or the anion exchange membrane,
In the desalting chamber, a first small desalting chamber and a second small desalting chamber which are partitioned in the thickness direction by an intermediate ion exchange membrane disposed between the cation exchange membrane and the anion exchange membrane. Formed,
Distributing the treated water that has circulated through any of the first small desalting chambers, and provided with a first water flow means for distributing the distributed treated water to any of the plurality of second small desalting chambers,
Electric deionization characterized in that second dewatering means is provided for circulating the water to be treated that has circulated through the optional second small demineralization chamber to the other first small demineralization chamber. Water production equipment.   Said 2nd water flow means joins the to-be-processed water which distribute | circulated several said 2nd small desalination chamber, and distribute | circulates the to-be-processed water to the said other 1st small desalination chamber. The electric deionized water production apparatus according to claim 1.   Concentrated water is circulated to an adjacent first concentrating chamber via any one of the first small desalting chambers and the anion exchange membrane or cation exchange membrane, and then the other first small desalting chamber and the anion exchange membrane or cation exchange. The apparatus for producing electric deionized water according to claim 1 or 2, further comprising means for circulating through an adjacent concentrating chamber through a membrane.   The volume ratio of the volume V1 of the arbitrary first small desalting chamber to the volume V2 of the other first small desalting chamber is V1: V2 = 2: 8 to 8: 2. The electric deionized water production apparatus according to any one of claims 1 to 3.   The volume ratio between the volume v1 of the concentrating chamber adjacent to the arbitrary first small desalting chamber and the volume v2 of the concentrating chamber adjacent to the other first small desalting chamber is v1: v2 = 2: It is 8-8: 2, The electrical deionized water manufacturing apparatus of Claim 3 or 4 characterized by the above-mentioned.   The first small desalting chamber is formed by filling an anion exchanger in a single bed between the anion exchange membrane and the intermediate ion exchange membrane, and the second small desalting chamber is formed of the cation exchange membrane. 6. The electric deionized water production apparatus according to claim 1, wherein a cation exchanger is filled in a single bed form between the intermediate ion exchange membrane and the intermediate ion exchange membrane. .   7. The intermediate ion exchange membrane is a cation exchange membrane, an anion exchange membrane, a duplex membrane or a bipolar membrane in which both a cation exchange membrane and an anion exchange membrane are arranged. The electrical deionized water production apparatus according to 1. It is a manufacturing method of the deionized water using the electric deionized water manufacturing apparatus of any one of Claims 1-7, Comprising: The to-be-processed water distribute | circulated to arbitrary said 1st small demineralization chambers A method for producing deionized water, characterized in that the treated water thus distributed is circulated to any of the plurality of second small desalting chambers and further to the other first small desalting chambers.

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