JP5114307B2 - Electric deionized water production equipment - Google Patents

Description

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

  As a method for producing deionized water, a method for deionizing by passing water to be treated through an ion exchange resin is conventionally known. However, in this method, when the ion exchange resin is saturated, it is necessary to regenerate with a drug. In recent years, in order to eliminate such disadvantages in processing operation, an electric deionization apparatus (hereinafter referred to as EDI) that does not require regeneration with a drug has been put into practical use.

  EDI is a pure water production apparatus that combines electrophoresis and electrodialysis. EDI is filled with an ion exchanger between an anion exchange membrane and a cation exchange membrane, an anode chamber having an anode outside the ion exchange membrane, and a cathode chamber having a cathode (hereinafter collectively referred to as an anode chamber and a cathode chamber, This is a device in which an electrode chamber is sometimes provided. In the method of producing deionized water by EDI, by passing water to be treated through the ion exchanger layer with a DC voltage applied to the electrodes, ion components in the water to be treated are adsorbed by the ion exchanger, and electrophoresis is performed. The ions are migrated to the membrane surface with, and electrodialyzed with an ion exchange membrane to be removed into concentrated water.

In conventional EDI, regeneration of the ion exchanger in the desalting chamber occurs at the interface between different types of ion exchangers in the desalting chamber, mainly using H ⁺ and OH ⁻ generated by the water dissociation reaction. It was broken. For this reason, it is necessary to apply a voltage sufficient to advance the water dissociation reaction to the desalting chamber, and the voltage is added according to the number of desalting chambers. In addition, the conventional EDI has a concentrating chamber between the electrode chamber and the desalting chamber, or even if the electrode chamber and the desalting chamber are adjacent to each other, the electrode chamber is used as a concentrating chamber. H ⁺ and OH ⁻ ions generated by the electrode reaction in the electrode chamber were not effectively used and were discharged out of the apparatus.

To solve such a problem, for example, the electrode chamber is used as a desalting chamber, and H ⁺ and OH ⁻ generated by the electrolytic reaction (electrode reaction) of water proceeding at the electrode in the electrode chamber are converted into the electrode chamber (desalting chamber). EDI used for the regeneration of the ion exchanger inside is disclosed (for example, Patent Document 1). However, in the invention described in Patent Document 1, there is a concern that gas components generated by the electrode reaction, oxidizing substances, and the like are also included in the deionized water.

  An EDI is disclosed in which a demineralization chamber adjacent to the electrode chamber is provided and the water to be treated is circulated through the demineralization chamber as a structure in which gas components generated by the electrode reaction do not directly affect the deionized water. (For example, patent document 2). However, the EDI of Patent Document 2 has a problem that the number of electrodes per desalting chamber is large, and the apparatus becomes large in order to increase the amount of treated water.

EDI has been disclosed in which deionized water treated in a desalting chamber is circulated in an electrode chamber filled with an ion exchanger to prevent electrode deterioration, reduce operating voltage, and improve desalting efficiency ( For example, Patent Document 3). However, in the EDI of Patent Document 3, although it is possible to prolong the life of the electrode by preventing salt precipitation on the electrode, H ⁺ and OH ⁻ generated in the electrode chamber are not effectively used. It was discharged outside the EDI device.
Japanese Patent No. 3793229 Japanese Patent Publication No. 5-79397 Japanese Patent No. 3801621

  An object of the present invention is to provide an EDI that realizes energy saving during operation and has a high specific resistance and good water quality.

  The EDI of the present invention is filled with an ion exchanger in a space defined by a cation exchange membrane on one side and an anion exchange membrane on the other side, and is provided with one or more main desalting chambers, Alternatively, a concentration chamber is provided on both sides of the main desalting chamber via the anion exchange membrane, and the anode chamber in which the main desalting chamber and the concentration chamber are partitioned by an anode and an anode-side partition membrane; A cathode chamber partitioned by a cathode and a cathode-side partition membrane, the anode-side partition membrane as a cation exchange membrane, the anode chamber filled with an ion exchanger, the anode-side partition membrane and the A sub-desalting chamber formed by filling a space partitioned by the cation exchange membrane disposed opposite to the anode side partition membrane with an ion exchanger, and / or the cathode side partition membrane as an anion exchange membrane The cathode chamber is filled with an ion exchanger, A sub-demineralization chamber formed by filling an ion exchanger is provided in a space defined by the pole-side partition membrane and the anion-exchange membrane disposed opposite to the cathode-side partition membrane, Means for circulating the treated water flowing through the chamber to the main desalting chamber, and / or means for circulating the treated water flowing through the main desalting chamber to the sub-desalting chamber. Features.

  Between the anode chamber and the cathode chamber, two or more main demineralization chambers are arranged via the concentration chamber, and the water to be treated that has circulated through the sub-demineralization chamber is used as an arbitrary main demineralization chamber. The treated water that has been circulated and circulated through the optional main desalting chamber may be circulated to another main desalting chamber, and the treated water that is circulated through the optional main desalting chamber may be circulated to other main desalting chambers. The treated water that has been circulated through the chamber and then circulated through the main desalting chamber may be circulated through the sub-desalting chamber.

  Two or more main desalting chambers are arranged between the anode chamber and the cathode chamber via the concentration chamber, and the treated water distributed through the sub-desalting chamber is distributed and distributed. Water may be circulated to the plurality of main desalting chambers, the treated water that has been circulated through the plurality of main desalting chambers may be merged, and the combined treated water may be circulated to the sub-desalting chambers good.

  In the main desalination chamber, an intermediate ion exchange membrane is disposed between the cation exchange membrane on one side and the anion exchange membrane on the other side, and the small desalination is divided into multiple stages in the thickness direction of the main desalination chamber. A salt chamber may be formed. The anode chamber and / or the cathode chamber is preferably passed with water treated in the main desalting chamber or the sub-desalting chamber, and has a resistivity of 0.2 to 18. It is preferable that 2 MΩ · cm of water is passed.

  According to the EDI of the present invention, it is possible to achieve energy saving during operation and to obtain a good water quality with high specific resistance.

  In the EDI of the present invention, a main desalting chamber is provided between an anode chamber and a cathode chamber (hereinafter sometimes referred to as an electrode chamber), and at least one of the electrode chambers is connected to a sub-channel adjacent via a partition film. Means for providing a desalting chamber and circulating the treated water flowing through the sub-desalting chamber to the main desalting chamber, and / or treating the treated water flowing through the main desalting chamber to the sub-desalting chamber There is provided a means for distribution.

  The principle of energy saving and water quality improvement during operation in the EDI of the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram for explaining the flow of ion components in the EDI 8 of the present invention. As shown in FIG. 1, the EDI 8 includes a main desalting chamber 50 and concentration chambers 60 and 62 provided on both sides of the main desalting chamber 50 between the cathode chamber 10 and the anode chamber 20. Sub-demineralization chambers 30 and 40 are provided on the chamber 10 side and the anode chamber 20 side, respectively.

  The cathode chamber 10 is formed by filling an ion exchanger into a space defined by a cathode 12 and a cathode-side partition membrane 14 that is an anion exchange membrane. The anode chamber 20 is formed by filling an ion exchanger into a space defined by an anode 22 and an anode-side partition membrane 24 that is a cation exchange membrane.

  The sub-desalting chamber 30 is formed by filling an ion exchanger into a space defined by the cathode-side partition membrane 14 forming the cathode chamber 10 and the anion exchange membrane 32. The sub-desalting chamber 40 is formed by filling an ion exchanger in a space defined by the anode-side partition membrane 24 that forms the anode chamber 20 and the cation exchange membrane 42. The main desalting chamber 50 is formed by filling an ion exchanger in a space defined by a cation exchange membrane 52 disposed on the cathode chamber 10 side and an anion exchange membrane 54 disposed on the anode chamber 20 side. Yes.

  The concentration chamber 60 is formed by being partitioned by an anion exchange membrane 32 that forms the secondary desalting chamber 30 and a cation exchange membrane 52 that forms the main desalting chamber 50. The concentration chamber 62 is formed by being partitioned by a cation exchange membrane 42 that forms the secondary desalting chamber 40 and an anion exchange membrane 54 that forms the main desalting chamber 50.

  Here, the cathode chamber 10 and the sub-desalting chamber 30 are filled with an anion exchanger in a single bed form, and the anode chamber 20 and the sub-desalting chamber 40 are filled with a cation exchanger in a single bed form. As an example, the flow of ion components will be described.

  In the production of deionized water, first, electrode water is circulated through the cathode chamber 10 and the anode chamber 20, and a DC voltage is applied between the cathode 12 and the anode 22. Further, the concentrated water is circulated through the concentration chambers 60 and 62. And the to-be-processed water is distribute | circulated and processed to the sub-demineralization chamber 30 or the sub-demineralization chamber 40, the processed to-be-processed water is distribute | circulated to the main desalination chamber 50, and deionized water is manufactured. Alternatively, the water to be treated is circulated through the main desalting chamber 50 and the treated water is circulated through the sub-desalting chamber 30 or the sub-desalting chamber 40 to produce deionized water.

During the production of deionized water, in the cathode chamber 10, H ₂ , OH ^{− and the} like are generated by an electrode reaction at the cathode 12. Among these, H ₂ is taken into the electrode water and discharged from the cathode chamber 10. OH ⁻ is attracted to the anode 22 that is the counter electrode, passes through the cathode side partition membrane 14 that is the anion exchange membrane, and moves to the sub-desalting chamber 30.

In the sub-desalting chamber 30, the water to be treated flows while diffusing in the anion exchanger of the sub-desalting chamber 30, and mainly contains anion components (Cl ⁻ , HCO ₃ ⁻ , CO ₃ ²⁻ , SiO ₂ (silica is In many cases, it takes a special form, so that it is displayed differently from general ions)) is adsorbed on the anion exchanger. Here, the anion exchanger is regenerated by exchanging OH ⁻ moved from the cathode chamber 10 and adsorbed anion components such as Cl ⁻ and HCO ₃ ⁻ . The anion component desorbed from the anion exchanger passes through the anion exchange membrane 32 and moves to the concentration chamber 60. The anion component moved to the concentration chamber 60 is taken into the concentrated water and discharged.

In the anode chamber 20, O ₂ , H ^{+ and the} like are generated by the electrode reaction in the anode 22. Among these, O ₂ is taken into the electrode water and discharged from the anode chamber 20. H ⁺ is attracted to the cathode 12 that is the counter electrode, passes through the anode-side partition membrane 24 that is a cation exchange membrane, and moves to the sub-desalting chamber 40.

In the sub-desalting chamber 40, the water to be treated flows while diffusing in the cation exchanger of the sub-desalting chamber 40, and mainly cation components (Na ⁺ , Ca ²⁺ , Mg ^2+, etc.) are converted into the cation exchanger. Adsorbed. Here, the cation exchanger is regenerated by exchanging H ⁺ moved from the anode chamber 20 with adsorbed cation components such as Na ⁺ and Ca ²⁺ . The cation component desorbed from the cation exchanger passes through the cation exchange membrane 42 and moves to the concentration chamber 62. The cation component moved to the concentration chamber 62 is taken into the concentrated water and discharged.

In the deionized water production described above, in the secondary demineralization chamber 30, the anion exchanger is efficiently regenerated due to the presence of OH ⁻ moving from the cathode chamber 10. In the secondary desalting chamber 40, the cation exchanger is efficiently regenerated due to the presence of H ⁺ , which moves from the anode chamber 20. Therefore, the ion components in the secondary desalting chambers 30 and 40 are smoothly moved. It is possible to carry out operation at a reduced voltage.

Furthermore, since the secondary desalting chambers 30 and 40 have a high regeneration efficiency of the ion exchanger, the space velocity (SV), which is the flow rate of the water to be treated, can be increased as compared with the main desalting chamber 50. That is, even if the auxiliary desalting chambers 30 and 40 are made thinner than the main desalting chamber 50, they have the same or higher capacity for desalting. For this reason, the distance between the cathode 12 and the anode 22 can be shortened, whereby the operating voltage can be further lowered. In addition, SV is the flow rate (L) which distribute | circulates for 1 hour with respect to the unit volume (L) of an ion exchanger, Comprising: A unit is represented by L / L * h ^<-1 > (hereinafter the same). .

In addition, OH ⁻ moves abundantly from the adjacent cathode chamber 10 to the sub-desalting chamber 30. For this reason, even if it is a to-be-processed water of low pH, the to-be-processed water can be adjusted to pH suitable for the process in the main desalting chamber 50 by pre-processing in the sub-desalination chamber 30. FIG.
On the other hand, H ⁺ moves abundantly from the adjacent anode chamber 20 into the sub-desalting chamber 40. For this reason, even if it is a to-be-processed water of high pH, the to-be-processed water can be adjusted to pH suitable for the process in the main desalting chamber 50 by pre-processing in the sub-desalination chamber 40.

The EDI of the present invention will be described with an example, but is not limited to this embodiment.
(First embodiment)
A first embodiment of EDI of the present invention will be described with reference to FIG. FIG. 2 is a cross-sectional view of the EDI 100 of this embodiment. As shown in FIG. 2, the EDI 100 is arranged such that a main desalting chamber 150 and a main desalting chamber 155 are sandwiched by a concentration chamber 160 between a cathode chamber 110 and an anode chamber 120. An adjacent sub-desalting chamber 130 is provided via a partition membrane 114. And EDI100 distribute | circulates the to-be-processed water which distribute | circulated the auxiliary | assistant desalination chamber 130 to arbitrary main desalination chambers, and also distribute | circulates it to another main desalination chamber.

The cathode 112 and the anode 122 are connected to a power source (not shown).
The cathode chamber 110 is formed by sequentially arranging a cathode 112, a frame body 111, and a cathode side partition film 114, and an opening of the frame body 111 is filled with an ion exchanger. An electrode water inflow line 116 and an electrode water outflow line 118 are connected to the cathode chamber 110.

  In the anode chamber 120, an anode 122, a frame body 121, and an anode side partition film 124 are arranged in order, and an opening of the frame body 121 is filled with an ion exchanger. An electrode water inflow line 126 and an electrode water outflow line 128 are connected to the anode chamber 120.

  The sub-desalting chamber 130 is formed by arranging a cathode-side partition membrane 114, a frame body 131, and an anion exchange membrane 132 in this order from the cathode 112 side, and filling the opening of the frame body 131 with an ion exchanger. ing. A treated water inflow line 134 and a treated water outflow line 136 are connected to the sub-desalting chamber 130. The treated water outflow line 136 is connected to the treated water inflow line 156 by a pipe (not shown). And the to-be-processed water outflow line 136, the piping which is not shown in figure, and the to-be-processed water inflow line 156 comprise "the means to distribute | circulate the to-be-processed water which distribute | circulated the sub-demineralization chamber to the main desalination chamber."

  The main desalting chamber 150 is formed by sequentially arranging a cation exchange membrane 152, a frame 151, and an anion exchange membrane 154 from the cathode 112 side, and filling the opening of the frame 151 with the ion exchanger. Yes. A treated water inflow line 156 and a treated water outflow line 157 are connected to the main desalting chamber 150, and the treated water outflow line 157 is connected to the treated water inflow line 158 by a pipe (not shown). Yes.

  The main desalting chamber 155 is formed by arranging a cation exchange membrane 152, a frame 151, and an anion exchange membrane 154 in this order from the cathode 112 side, and filling the opening of the frame 151 with the ion exchanger. Yes. A treated water inflow line 158 and a deionized water outflow line 159 are connected to the main desalting chamber 155.

  The concentrating chamber 160 is formed by disposing a frame 161 on both sides of the main desalting chambers 150 and 155. A concentrated water inflow line 162 and a concentrated water outflow line 164 are connected to the concentration chamber 160.

The cathode 112 is not particularly limited as long as it functions as a cathode, and examples thereof include plate-like stainless steel and mesh-like stainless steel.
The anode 122 is not particularly limited as long as it functions as an anode. However, when Cl ⁻ is present in the water to be treated, chlorine generation occurs in the anode, and thus the anode 122 preferably has chlorine resistance. 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 side partition membrane 114 is an anion exchange membrane. 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 of the cathode side partition membrane 114 in the present embodiment is not particularly limited, and any anion exchange membrane may be selected depending on the ease of production of EDI, the quality of water to be treated, the quality of water required for deionized water, the amount of treatment, and the like. Can be selected.

  The ion exchanger filled in the cathode chamber 110 is not particularly limited as long as it has an ion exchange function. For example, an ion exchange resin, an ion exchange fiber, a monolithic porous ion exchanger, etc. can be mentioned. Of these, ion exchange resins, which are the most versatile, are preferred. Examples of the ion exchange resin include an anion exchange resin and a cation exchange resin. Examples of the anion exchange resin include strongly basic anion exchange resins and weakly basic anion exchange resins. For example, commercially available products include Amberlite (trade name) manufactured by Rohm and Haas. Examples of the cation exchange resin include a strong acid cation exchange resin and a weak acid cation exchange resin, and examples thereof include amberlite (trade name) manufactured by Rohm & Haas. These may be used alone or in combination of two or more.

In addition, the ion exchanger packing form is not particularly limited, but an anion exchanger single bed form, a cation exchanger single bed form, a mixed bed form of an anion exchanger and a cation exchanger, or a double bed form, etc. Either can be used. Among these, it is preferable to use an anion exchanger single bed form, a mixed bed form of an anion exchanger and a cation exchanger, or a double bed form. When the mixed bed form of the anion exchanger and the cation exchanger or the double bed form is used, the anion exchanger is preferably 50% by volume or more and less than 100% by volume. This is because in the cathode chamber 110, OH ⁻ generated by the electrode reaction of the cathode 112 is smoothly transferred to the sub-desalting chamber 130.

  The anode side partition membrane 124 is not particularly limited, and either a cation exchange membrane or an anion exchange membrane may be used. The anode-side partition film 124 can be either a homogeneous film or a heterogeneous film.

The ion exchanger filled in the anode chamber 120 is not particularly limited, and the same ion exchanger as that filled in the cathode chamber 110 described above can be used.
In addition, the form of filling the ion exchanger in the anode chamber 120 is not particularly limited, as is the case with the filling form of the cathode chamber 110 described above, and an anion exchanger single bed form, a cation exchanger single bed form, or an anion exchanger Either a mixed bed form with a cation exchanger or a double bed form can be used.

The frames 111 and 121 are not particularly limited as long as they have insulating properties and do not leak electrode water. For example, a frame made of resin such as polyethylene, polypropylene, polyvinyl chloride, ABS, polycarbonate, noryl or the like is used. Can be mentioned.
The thickness of the frames 111 and 121 is not particularly limited, and can be set according to the desired thickness of the cathode chamber 110 and the anode chamber 120.
Moreover, when the area of the opening part of the frame bodies 111 and 121 is large, you may provide a support body in the space where the frame bodies 111 and 121 were hollowed out. This is because by providing the support, it is possible to prevent the cathode side partition film 114 and the anode side partition film 124 from being curved and the filling amount of the ion exchanger from becoming uneven. The support is not particularly limited as long as it is a material that has insulating properties and does not hinder the flow of water to be treated. For example, polyethylene, polypropylene, polyvinyl chloride, ABS, polycarbonate, noryl, etc., provided with slits. The resin-made support body can be mentioned.

  The thickness of the cathode chamber 110 is not particularly limited, and can be determined in consideration of the voltage applied between the two electrodes. For example, the thickness is preferably selected in the range of 0.3 to 10 mm. The thickness of the anode chamber 121 is the same as the thickness of the cathode chamber 110.

  The anion exchange membrane 132 in the sub-desalting chamber 130 is not particularly limited, and either a homogeneous membrane or a heterogeneous membrane can be used.

The ion exchanger filled in the sub-desalting chamber 130 is not particularly limited, and the same ion exchanger as that filled in the cathode chamber 110 can be used.
The filling form of the ion exchanger in the sub-desalting chamber 130 is not particularly limited, but preferably contains an anion exchanger, more preferably an anion exchanger single bed form, or a mixed bed of an anion exchanger and a cation exchanger. It is preferable to use a form or a double bed form. When the mixed bed form of the anion exchanger and the cation exchanger or the double bed form is used, the anion exchanger is preferably 50% by volume or more and less than 100% by volume. In the sub-desalting chamber 130 on the cathode chamber 110 side, mainly anion components such as Cl ⁻ and HCO ₃ ^{− in the} water to be treated are removed, and abundant OH ⁻ moving from the cathode chamber 110 is regenerated as an anion exchanger. This is because it can be used.

  The frame 131 can be the same as the frame 111. The thickness of the frame 131 is not particularly limited, and can be set according to the desired thickness of the sub-desalting chamber 130.

  The thickness of the sub-demineralization chamber 130 is not particularly limited, and can be determined in consideration of the quality of water to be treated and deionized water, the amount of treatment, and the like, and is preferably in the range of 4 to 50 mm, for example. If the thickness of the sub-desalting chamber 130 is too thin, the water flow differential pressure increases, which may cause damage to the sub-desalting chamber 130 and the like. This is because if the thickness of the sub-desalting chamber 130 is too thick, the flow may be uneven and current efficiency may be reduced.

  The cation exchange membrane 152 and the anion exchange membrane 154 that form the main desalting chambers 150 and 155 are not particularly limited, and either a homogeneous membrane or a heterogeneous membrane can be used.

The ion exchanger filled in the main desalting chambers 150 and 155 is not particularly limited, and the same ion exchanger as that filled in the cathode chamber 110 can be used.
The form of packing of the ion exchanger in the main desalting chamber 150 is not particularly limited, and a single bed form of an anion exchanger or a cation exchanger, a mixed bed form of an anion exchanger and a cation exchanger, or a double bed form. Either form can be used. The filling form of the ion exchanger in the main desalting chamber 155 is the same as that of the main desalting chamber 150. Note that the types and packing forms of the ion exchangers in the main desalting chambers 150 and 155 may be the same or different.

  The frame 151 can be the same as the frame 111. The thickness of the frame 151 is not particularly limited, and can be determined according to the desired thickness of the main desalting chambers 150 and 155.

  The thicknesses of the main desalting chambers 150 and 155 are not particularly limited, and it is preferable to determine an appropriate thickness depending on the type and packing form of the ion exchanger. For example, the thickness of the main desalting chambers 150 and 155 is preferably determined in the range of 4 to 100 mm, and is suitably determined in the range of 8 to 60 mm. The thicknesses of the main desalting chambers 150 and 155 may be the same or different.

  The frame 161 of the concentrating chamber 160 can be the same as the frame 111. The thickness of the frame 161 is not particularly limited, and can be determined according to a desired thickness of the concentration chamber.

  The concentration chamber 160 is not particularly limited as long as the concentrated water can circulate, and a mesh may be arranged or an ion exchanger may be filled. From the viewpoint of reducing the electrical resistance, it is preferable that the ion exchanger is filled.

When the concentration chamber 160 is filled with an ion exchanger, the ion exchanger to be filled is not particularly limited, and the same ion exchanger as the cathode chamber 110 can be used.
The filling form of the ion exchanger in the concentrating chamber 160 is not particularly limited, and can be determined in consideration of the quality of the water to be treated. The anion exchanger single bed form, the cation exchanger single bed form, or the anion exchange Any of the mixed bed form of the body and the cation exchanger, or the multiple bed form can be used. For example, from the viewpoint of preventing scale formation on the surface of the anion exchange membrane 154 in the concentration chamber 160, the anion exchanger may be filled in a single bed form. By having the anion exchanger layer in contact with the anion exchange membrane 154, the movement of the anion component from the main desalting chambers 150, 155 to the concentration chamber 160 is promoted, and the anion component is present on the surface of the anion exchange membrane 154 on the concentration chamber 160 side. This is because the presence of a high concentration can suppress the occurrence of concentration polarization.

  Regarding the method for producing deionized water in the present embodiment, the cathode chamber 110, the sub-desalting chamber 130, and the main desalting chamber 155 are filled with an anion exchanger in a single bed form, and the anode chamber 120 and the main desalting chamber 150 are filled. In the following, a case where the cation exchanger is packed in a single bed form will be described as an example.

First, electrode water is caused to flow into the cathode chamber 110 from the electrode water inflow line 116, and electrode water is caused to flow into the anode chamber 120 from the electrode water inflow line 126. The concentrated water is caused to flow into the concentration chamber 160 from the concentrated water inflow line 162. Then, a DC voltage is applied between the cathode 112 and the anode 122. When a DC voltage is applied, in the cathode chamber 110, an electrolytic reaction of water in the vicinity of the electrode shown in the following formula (1) occurs due to an electrode reaction of the cathode 112, and H ₂ and OH ⁻ are generated. The generated H ₂ is taken into the electrode water and discharged to the electrode water outflow line 118. On the other hand, the produced OH ⁻ is attracted to the side of the anode 122 that is the counter electrode, moves through the anion exchanger filled in the cathode chamber 110, passes through the cathode side partition membrane 114 that is an anion exchange membrane, and is sub-desalted. Move to chamber 130.

2H ₂ O + 2e ⁻ → H ₂ + 2OH ⁻ (1)

Next, the water to be treated is caused to flow into the sub-desalination chamber 130 from the water to be treated inflow line 134. The treated water that has flowed in flows through the anion exchanger in the sub-desalting chamber 130 while diffusing, and flows out from the treated water outflow line 136. During this time, mainly anion components such as Cl ⁻ and HCO ₃ ^{— in the} water to be treated are adsorbed on the anion exchanger and removed from the water to be treated.

Here, the anion exchanger that adsorbs anion components such as Cl ⁻ and HCO ₃ ^— is regenerated with OH ⁻ that has moved from the cathode chamber 110. The desorbed anion component is attracted to the anode 122 side, passes through the anion exchange membrane 132, and moves to the concentration chamber 160. The anion component moved to the concentration chamber 160 is taken into the concentrated water and discharged from the concentrated water outflow line 164. In general, carbon dioxide gas is dissolved in raw water used for EDI treated water to form a weak acid (pH of about 5.5 to 6.0). Due to the moved OH ⁻ , the pH of the water to be treated in the sub-desalting chamber 130 is adjusted to near neutrality.

The treated water treated in the sub-desalination chamber 130 flows from the treated water outflow line 136 through the unshown piping through the treated water inflow line 156 and flows into the main desalting chamber 150. The treated water that has flowed into the main desalting chamber 150 flows while diffusing through the cation exchanger in the main desalting chamber 150, and flows out from the treated water outflow line 157. During this time, mainly cation components such as Na ⁺ and Ca ^{2+ in the} water to be treated are adsorbed by the cation exchanger. Here, the pH of the water to be treated is maintained in the vicinity of neutrality, and the H ⁺ concentration, which is a competing ion, is lower than the water to be treated before flowing into the sub-desalting chamber 130. For this reason, current efficiency becomes high and the removal of the cation component in to-be-processed water is performed favorably.

At this stage, ionic components contained in the water to be treated are generally removed. However, among the anion components removed in the sub-desalting chamber 130, carbonate ions are concentrated at a high concentration in the concentration chamber 160, so that they pass through the cation exchange membrane 152 and return to the main desalting chamber 150. May move. For this reason, the anion component is removed again in the main desalting chamber 155. The treated water treated in the main desalting chamber 150 flows from the treated water outflow line 157 through the untreated water inflow line 158 and flows into the main desalting chamber 155 via a pipe (not shown). The treated water that has flowed into the main desalting chamber 155 flows while diffusing in the anion exchanger. Thus, the water to be treated becomes deionized water in which both ionic components such as a cation component such as Na ⁺ and Ca ²⁺ and an anion component such as Cl ⁻ and HCO ₃ ⁻ are highly removed, and the deionized water flows out. Out of line 159.

  Although the to-be-processed water is not specifically limited, The water etc. which processed the water which removed the turbid component of industrial water and well water with the turbidity membrane with the reverse osmosis (RO) membrane, etc. are mentioned.

The amount of water to be treated in the sub-desalination chamber 130 is not particularly limited, and can be determined in consideration of the ability of the EDI 100, the quality of the water to be treated, and the like. Here, the water flow rate can be expressed by space velocity (SV). If the SV is too large, the ion removal performance decreases, or the differential pressure increases due to the increase in the water flow rate (LV) that occurs with the increase in SV. This is not preferable because it causes damage to the sub-desalting chamber 130 and causes operational difficulties. Here, LV is a flow rate per unit area and is a linear velocity expressed in m / h (the same applies hereinafter). On the other hand, if the SV is too small, the amount of deionized water produced is low, which is not preferable.
In addition, SV of the to-be-processed water in the sub desalination chamber 130 can be made higher than SV of the main desalination chambers 150 and 155. This is because, in the secondary desalting chamber 130, the anion exchanger is regenerated well, so that the anion component can be removed satisfactorily even when the SV is higher than the water to be treated in the main desalting chambers 150, 155.

The amount of water to be treated in the main desalting chamber 150 is not particularly limited and can be determined in consideration of the ability of the EDI 100, the quality of the water to be treated, and the like. In the main desalting chamber 150, if the SV of the water to be treated is too large, the ion removal performance decreases, or the differential pressure increases due to the increase in LV that occurs as the SV increases, leading to damage to the main desalting chamber 150. Or undesirably driving problems. On the other hand, if the SV is too small, the amount of deionized water produced is low, which is not preferable.
The amount of water to be treated in the main desalting chamber 155 is the same as the amount of water flowing in the main desalting chamber 150.

  The flow rate of the concentrated water in the concentration chamber 160 is not particularly limited, and can be determined in consideration of the ability of the EDI 100, the quality of the water to be treated, and the amount to be treated. The concentrated water has the purpose of diffusing ions that have moved to the concentration chamber 160 into the concentrated water and flowing out of the EDI 100. Therefore, the flow rate of the concentrated water is preferably determined by the relationship between the flow rate of the water to be treated, the ion concentration of the water to be treated, and the production amount of deionized water. It is preferable to determine the flow rate of the concentrated water so that the concentration ratio is 3 to 20. In addition, the concentration rate by the following formula (2) is defined on the assumption that the same raw water is used for the water to be treated and the concentrated water, and all the ions in the main desalting chamber 150 are transferred to the concentration chamber 160.

If the flow rate of the concentrated water is too small, uneven concentration diffusion of ions transferred to the concentration chamber 160 occurs, the concentration polarization layer on the surface of the ion exchange membrane becomes thick, and scale may be generated. On the other hand, if the flow rate of the concentrated water is too large, the recovery rate of deionized water decreases, which is not preferable.
The concentrated water is not particularly limited, and water from the same water source as the water to be treated may be used as the concentrated water, or deionized water or pure water may be used.

  The electrode water in the cathode chamber 110 is not particularly limited, and water from the same water source as the water to be treated may be used as the electrode water, the sub-desalting chamber 130, the main desalting chamber 150, or the main desalting chamber. Water treated in the chamber 155 or water having a specific resistance value of 0.2 to 18.2 MΩ · cm may be used as electrode water. Among them, water processed through the secondary desalting chamber 130, the main desalting chamber 150, or the main desalting chamber 155, or water having a specific resistance value of 0.2 to 18.2 MΩ · cm. It is preferable. By using water with few impurities such as a cation component and an anion component, the electrolysis of water is preferentially advanced, and precipitates are prevented from being generated on the surface of the cathode 112, thereby maintaining the current efficiency. Can be planned. The electrode water in the anode chamber 120 is the same as the electrode water in the cathode chamber 110.

The current to be applied is not particularly limited, and is preferably determined in consideration of the quality of water to be treated, the scale of EDI 100, and the like.
The flow rate of the electrode water in the cathode chamber 110 and the anode chamber 120 is not particularly limited, and is preferably determined according to the applied voltage or the like. If the flow rate of the electrode water is too small, it will be difficult to sufficiently discharge the generated H ₂ , O ₂ , and Cl ₂ gases, and if the flow rate of the electrode water is too large, the recovery rate is lowered, which is not preferable.

In the EDI 100 of the present embodiment, OH ⁻ necessary for regeneration of the ion exchanger filled in the sub-desalting chamber 130 is supplied from the cathode chamber 110, so that the ion exchanger charged in the sub-desalting chamber 130 is simply used. Even in the floor form, the ion exchanger is regenerated well. And by making it a single bed form, the movement of ion becomes smoother and the operating voltage of EDI100 can further be reduced.

  Moreover, the anion component in to-be-processed water can be favorably removed by processing to-be-processed water in the sub-desalination chamber 130 with high regeneration efficiency. In addition, when the water to be treated is acidic, the water to be treated whose pH has been adjusted in the secondary desalting chamber 130 is treated in the main desalting chamber 150, so that the main desalting chamber 150 can remove cation components well. can do. Furthermore, by performing treatment in the main desalting chamber 155, deionized water having a high specific resistance and high water quality from which both anionic and cationic components are highly removed can be produced.

(Second Embodiment)
A second embodiment of EDI of the present invention will be described with reference to FIG. FIG. 3 is a cross-sectional view of the EDI 200 of the present embodiment. As shown in FIG. 3, the EDI 200 is disposed between the cathode chamber 110 and the anode chamber 120 with the main desalting chamber 250 sandwiched between the concentration chambers 160 and adjacent to the cathode chamber 110 via the cathode-side partition membrane 114. A secondary desalting chamber 230 is provided. And EDI200 distributes the to-be-processed water processed in the sub-desalination chamber 230, and distribute | circulates it to the some main desalination chamber 250. FIG.

  The sub-desalting chamber 230 is the same as the sub-desalting chamber 130 in the first embodiment. A treated water inflow line 234 and a treated water outflow line 236 are connected to the sub-desalting chamber 230. The treated water outflow line 236 is connected to the treated water inflow line 252 by a pipe (not shown). And the to-be-processed water outflow line 236, the piping which is not shown in figure, and the to-be-processed water inflow line 252 comprise the "means which distribute | circulate the to-be-processed water which distribute | circulated the sub-desalination chamber to the main desalination chamber."

  The main desalting chamber 250 is the same as the main desalting chambers 150 and 155 in the first embodiment. A deionized water outflow line 258 is connected to the main desalting chamber 250. The treated water inflow line 252 has a plurality of branch lines 254, and each of the branch lines 254 is connected to the main desalting chamber 250.

  Regarding the method for producing deionized water in this embodiment, the cathode chamber 110 and the secondary demineralization chamber 230 are filled with an anion exchanger in a single-bed form, and the anode chamber 120 and the main demineralization chamber 250 are filled with a cation exchanger. The case where it is filled in a single floor form will be described as an example.

The treated water is caused to flow into the sub-desalting chamber 230 from the treated water inflow line 234. The treated water that has flowed in flows through the anion exchanger in the secondary desalting chamber 230 while diffusing, and flows out from the treated water outflow line 236. During this time, mainly anion components such as Cl ⁻ and HCO ₃ ^{— in the} water to be treated are adsorbed on the anion exchanger and removed from the water to be treated. Then, anion components such as Cl ⁻ and HCO ₃ ⁻ adsorbed on the anion exchanger are exchanged by OH ⁻ moving from the cathode chamber 110 and desorbed from the anion exchanger. The desorbed anion component repeats adsorption to the anion exchanger and regeneration by OH ⁻ , is attracted to the anode 122 side, passes through the anion exchange membrane 132, and moves to the concentration chamber 160. The anion component moved to the concentration chamber 160 is taken into the concentrated water and discharged from the concentrated water outflow line 164.

The treated water that has been treated in the secondary desalting chamber 230 and adjusted in pH passes through the treated water inflow line 252 from the treated water outflow line 236 via a pipe (not shown), and is distributed to the branch line 254. , Flows into the main desalting chamber 250. The treated water that has flowed into the main demineralization chamber 250 flows while diffusing in the cation exchanger, and becomes deionized water and flows out from the deionized water outflow line 258. During this time, mainly cation components such as Na ⁺ and Ca ^{2+ in the} water to be treated are adsorbed by the cation exchanger. Here, even if the removal of the cation component in the water to be treated progresses, the H ⁺ concentration that becomes a competing ion is lower than the water to be treated before flowing into the sub-desalting chamber 230. For this reason, current efficiency becomes high and the removal of the cation component in to-be-processed water is performed favorably.

  When the SV is too large, the amount of water to be treated in the secondary desalting chamber 230 is not preferable because the ion removal performance is deteriorated, the secondary desalting chamber 230 is damaged, and operational difficulties are caused. . On the other hand, if the SV is too small, flow distribution to the main desalting chamber 250 is not performed properly, and there are a main desalting chamber 250 that is sufficiently desalted and a main desalting chamber 250 that is insufficiently desalted. As a result, the flow between the main desalting chambers 250 becomes uneven, which may adversely affect the performance of the EDI 200 as a whole.

  The amount of water to be treated in the main desalting chamber 250 is the same as the amount of water to be treated in the main desalting chambers 150 and 155 of the first embodiment.

  According to this embodiment, when performing the multistage process which distribute | circulates to-be-processed water to a some desalination chamber in series, it distribute | circulates to the some main desalination chamber 250 only by the sub-desalination chamber 230 with high regeneration efficiency. To be treated. Compared to conventional EDI, for example, multi-stage treatment in which water is sequentially passed through two main desalination chambers, the first stage desalination treatment can be concentrated in the sub-desalination chamber 230. The number of salt rooms can be reduced. For this reason, the distance between the cathode 112 and the anode 122 can be reduced, the operating voltage can be lowered, and deionized water can be produced with energy saving.

(Third embodiment)
A third embodiment of EDI of the present invention will be described with reference to FIG. FIG. 4 is a cross-sectional view of the EDI 300 of this embodiment. As shown in FIG. 4, the EDI 300 is disposed between the cathode chamber 110 and the anode chamber 120 with the main desalting chamber 350 sandwiched between the concentration chambers 160 and adjacent to the cathode chamber 110 via the cathode-side partition membrane 114. A secondary desalting chamber 330 is provided.

  The sub-desalting chamber 330 is the same as the sub-desalting chamber 130 in the first embodiment. A treated water inflow line 334 and a treated water outflow line 336 are connected to the sub-desalting chamber 330. The treated water outflow line 336 is connected to the treated water inflow line 360 by a pipe (not shown). And the to-be-processed water outflow line 336, the piping which is not shown in figure, and the to-be-processed water inflow line 360 comprise "the means to distribute | circulate the to-be-processed water which distribute | circulated the sub-desalination chamber to the main desalination chamber."

  The main desalting chamber 350 includes a small desalting chamber 352 and a small desalting chamber 354. The small desalting chamber 352 is formed by arranging a cation exchange membrane 152, a frame body 353, and an intermediate ion exchange membrane 356 in this order from the cathode 112 side, and filling the ion exchanger in the opening of the frame body 353. Has been. The small desalting chamber 354 is formed in such a manner that an intermediate ion exchange membrane 356, a frame body 355, and an anion exchange membrane 154 are disposed in this order from the cathode 112 side, and an opening of the frame body 355 is filled with an ion exchanger. ing. The small desalting chamber 352 and the small desalting chamber 354 are adjacent to each other through the intermediate ion exchange membrane 356.

  The treated water inflow line 360 has a plurality of branch lines 362, and each of the branch lines 362 is connected to the small desalting chamber 352. A treated water outflow line 364 is connected to the small desalting chamber 352, and the treated water outflow line 364 is connected to the treated water inflow line 365 by a pipe (not shown). A treated water inflow line 365 and a deionized water outflow line 368 are connected to the small desalting chamber 354.

  The intermediate ion exchange membrane 356 is not limited and is preferably selected according to the quality of the water to be treated and the quality of water required for deionized water. The intermediate ion exchange membrane 356 may be either an anion exchange membrane, a single cation exchange membrane, or a composite membrane in which both an anion exchange membrane and a cation exchange membrane are arranged. A composite membrane refers to a membrane in which the ion exchange membrane has regions with different polarities. For example, a mosaic film or a bipolar film can be used. The ratio of the anion exchange membrane to the cation exchange membrane in the composite membrane can be appropriately determined depending on the quality of the water to be treated, the purpose of treatment, and the like.

As the ion exchanger filled in the small desalting chambers 352 and 354, the same ion exchanger as that filled in the cathode chamber 110 can be used.
The filling form of the ion exchanger filled in the small desalting chamber 352 is not particularly limited, but it should be a single bed form of a cation exchanger, a mixed bed form of an anion exchanger and a cation exchanger, or a double bed form. Is preferred. In the case of a mixed bed form of an anion exchanger and a cation exchanger or a double bed form, the cation exchanger is preferably 50% by volume or more and less than 100% by volume. This is mainly for removing the cation component in the small desalting chamber 352 on the cathode 112 side.

The form of the ion exchanger filled in the small desalting chamber 354 is not particularly limited, but it should be an anion exchanger single bed form, a mixed bed form of an anion exchanger and a cation exchanger, or a double bed form. Is preferred. When the mixed bed form of the anion exchanger and the cation exchanger or the double bed form is used, the anion exchanger is preferably 50% by volume or more and less than 100% by volume. This is mainly for removing anion components in the small desalting chamber 354 on the anode 122 side.
In addition, the kind and filling form of the ion exchanger with which the small desalting chambers 352 and 354 are filled may be the same or different.

  As the frame bodies 353 and 355, the same ones as the frame body 111 can be used. The thickness of the frames 353 and 355 is not particularly limited, and can be determined according to the desired thickness of the small desalting chambers 352 and 354.

  The thickness of the small desalting chamber 352 is preferably determined in consideration of the quality of the water to be treated and deionized water, and the treatment amount, and is preferably determined in the range of 3 to 50 mm, for example. The thickness of the small desalting chamber 354 is the same as the thickness of the small desalting chamber 352. Note that the thicknesses of the small desalting chambers 352 and 354 may be the same or different.

  Regarding the method for producing deionized water in the present embodiment, the cathode chamber 110, the secondary desalting chamber 330, and the small desalting chamber 354 are in a single-bed form of an anion exchanger, and the small desalting chamber 352 and the anode chamber 120 are cations. A case where the exchanger is in a single-floor form will be described as an example.

From the treated water inflow line 334, the treated water flows into the sub-desalting chamber 330. The treated water that has flowed in flows through the anion exchanger in the sub-desalination chamber 330 while diffusing, and flows out from the treated water outflow line 336. During this time, mainly anion components such as Cl ⁻ and HCO ₃ ^{— in the} water to be treated are adsorbed on the anion exchanger and removed from the water to be treated. On the other hand, anion components such as Cl ⁻ and HCO ₃ ⁻ adsorbed on the anion exchanger in the secondary desalting chamber 330 are exchanged by OH ⁻ that has moved from the cathode chamber 110 and desorbed from the anion exchanger. The desorbed anion component is attracted to the anode 122 side, passes through the anion exchange membrane 132, and moves to the concentration chamber 160. The anion component moved to the concentration chamber 160 is taken into the concentrated water and discharged from the concentrated water outflow line 164. In addition, due to the abundant OH ⁻ that moves from the cathode chamber 110 to the sub-desalting chamber 330, the pH of the water to be treated in the sub-desalting chamber 330 becomes near neutral.

The treated water that has been treated in the secondary desalination chamber 330 and adjusted in pH passes through the treated water inflow line 360 from the treated water outflow line 336 via a pipe (not shown), and is distributed to the branch line 362. , Flows into the small desalting chamber 352. The treated water that has flowed into the small desalting chamber 352 circulates through the cation exchanger and flows out from the treated water outflow line 364. During this time, mainly cation components such as Na ⁺ and Ca ^{2+ in the} water to be treated are adsorbed by the cation exchanger. Here, since the pH of the water to be treated that has flowed into the small desalting chamber 352 is near neutral, the H ⁺ concentration, which is a competitive ion of cation components such as Na ⁺ and Ca ²⁺ , is low. For this reason, the current efficiency with respect to the cation component in to-be-processed water becomes high, and the removal of a cation component is performed favorably. In addition, as the cation component is removed while the water to be treated flows through the small desalting chamber 352, H ⁺ that is a competitive ion is released, and the pH is inclined to the acidic side.

The treated water that has flowed through the small desalting chamber 352 flows from the treated water outflow line 364 through the unshown piping through the untreated water inflow line 365 and flows into the small desalting chamber 354. The treated water that has flowed into the small desalting chamber 354 circulates in the anion exchanger while diffusing, becomes deionized water, and flows out from the deionized water outflow line 368. During this time, mainly anion components such as Cl ⁻ and HCO ₃ ^{— in the} water to be treated are adsorbed on the anion exchanger. Here, the water to be treated flows into the small desalting chamber 354 in a state where the pH is inclined to the acidic side, that is, in a state where the OH ⁻ concentration which is a competitive ion of an anionic component such as Cl ⁻ and HCO ₃ ^— is low. For this reason, the current efficiency with respect to an anion component is high, and the anion component is removed favorably. Thus, deionized water from which both anion components such as Cl ⁻ and HCO ₃ ⁻ and cation components such as Na ⁺ and Ca ²⁺ have been removed can be obtained.

The amount of water to be treated in the sub-desalination chamber 330 is the same as the amount of water to be treated in the sub-desalination chamber 230 of the second embodiment.
The amount of water to be treated in the small desalting chambers 352 and 354 is the same as the amount of water to be treated in the main desalting chambers 150 and 155 of the first embodiment.

  According to this embodiment, the main desalting chamber 350 includes small desalting chambers 352 and 354 that are partitioned by an intermediate ion exchange membrane 356. For this reason, it is possible to perform multistage treatment of the water to be treated without increasing the concentration chamber 160. As a result, when performing multistage processing, the distance between the cathode 112 and the anode 122 can be shortened, and the operating voltage can be lowered. For example, as described above, when the small desalting chamber 352 is a single bed form of a cation exchanger and the small desalting chamber 354 is a single bed form of an anion exchanger, the ions in each small desalting chamber are Since there is no heterogeneous ion interface between the exchangers, the electrical resistance can be kept low, and the operating voltage can be further reduced.

(Fourth embodiment)
A fourth embodiment of EDI of the present invention will be described with reference to FIG. FIG. 5 is a cross-sectional view of the EDI 400 of this embodiment. As shown in FIG. 5, the EDI 400 is disposed between the cathode chamber 410 and the anode chamber 420 with the main desalting chamber 450 sandwiched between the concentration chamber 160 and adjacent to the anode chamber 420 via the anode-side partition membrane 424. A secondary desalting chamber 440 is provided. And the to-be-processed water which distribute | circulated the main desalination chamber 450 is made to merge, and it distribute | circulates to the sub-desalination chamber 440. FIG.

  The cathode chamber 410 is formed by sequentially arranging the cathode 112, the frame body 111, and the cathode side partition film 414, and filling the opening of the frame body 111 with an ion exchanger. An electrode water inflow line 116 and an electrode water outflow line 118 are connected to the cathode chamber 410.

  In the anode chamber 420, the anode 122, the frame body 121, and the anode side partition film 424 are arranged in this order, and the opening of the frame body 121 is filled with an ion exchanger. An electrode water inflow line 126 and an electrode water outflow line 128 are connected to the anode chamber 420.

  The main desalting chamber 450 is formed by sequentially arranging a cation exchange membrane 152, a frame 151, and an anion exchange membrane 154 from the cathode 112 side, and an ion exchanger is filled in the opening of the frame 151. . A treated water inflow line 452 and a treated water outflow line 456 are connected to the main desalting chamber 450. The treated water outflow line 456 is connected to the treated water inflow line 444 by a pipe (not shown). And the means to distribute the to-be-processed water which distribute | circulated the main desalination chamber to the sub-desalination chamber is comprised by the to-be-processed water outflow line 456, the piping which is not shown in figure, and the to-be-processed water inflow line 444.

  In the sub-desalting chamber 440, a cation exchange membrane 442, a frame body 441, and an anode side partition membrane 424 that is a cation exchange membrane are arranged in this order from the cathode 112 side, and an ion exchanger is placed in the opening of the frame body 441. Filled and formed. A treated water inflow line 444 and a deionized water outflow line 446 are connected to the sub-desalting chamber 440.

  The cathode side partition membrane 414 is not particularly limited as long as it is an ion exchange membrane, and either a cation exchange membrane or an anion exchange membrane may be used. The cathode side partition film 414 can be either a homogeneous film or a heterogeneous film.

The ion exchanger filled in the cathode chamber 410 is not particularly limited, and the same ion exchanger filled in the cathode chamber 110 described above can be used.
In addition, the ion exchanger packing form is not particularly limited, but an anion exchanger single bed form, a cation exchanger single bed form, a mixed bed form of an anion exchanger and a cation exchanger, or a double bed form, etc. Either can be used.

  The anode-side partition membrane 424 is not particularly limited as long as it is a cation exchange membrane, and either a homogeneous membrane or a heterogeneous membrane can be selected.

The ion exchanger filled in the anode chamber 420 is not particularly limited, and the same ion exchanger filled in the cathode chamber 110 described above can be used.
Further, the filling form of the ion exchanger in the anode chamber 420 is not particularly limited, but it is preferably a cation exchanger single bed form, a mixed bed form of an anion exchanger and a cation exchanger, or a double bed form. . In the case of a mixed bed form of an anion exchanger and a cation exchanger or a double bed form, the cation exchanger is preferably 50% by volume or more and less than 100% by volume. This is because in the anode chamber 420, H ⁺ generated by the electrode reaction of the anode 122 is smoothly transferred to the sub-desalting chamber 440.

  As the cation exchange membrane 442 forming the sub-desalting chamber 440, either a homogeneous membrane or a heterogeneous membrane can be used.

As the ion exchanger filled in the sub-desalting chamber 440, the same ion exchanger as that filled in the cathode chamber 110 can be used.
The filling form of the ion exchanger in the sub-desalting chamber 440 is not particularly limited, but preferably contains a cation exchanger, more preferably a single cation exchanger or a combination of an anion exchanger and a cation exchanger. It is preferable to use a mixed bed form or a double bed form. In the case of a mixed bed form of an anion exchanger and a cation exchanger or a double bed form, the cation exchanger is preferably 50% by volume or more and less than 100% by volume. In the secondary desalting chamber 440 on the anode chamber 420 side, cation components such as Na ⁺ and Ca ^{2+ in the} water to be treated are mainly removed, and abundant H ⁺ moving from the anode chamber 420 is used to regenerate the cation exchanger. This is because it can be used.

  The frame body 441 can be the same as the frame body 111. The thickness of the frame 441 is not particularly limited, and can be determined according to the thickness of the sub-desalting chamber 440.

  The thickness of the sub-desalting chamber 440 is not particularly limited, and can be determined in consideration of the quality of water to be treated and deionized water, the amount of treatment, and the like, and is preferably in the range of 4 to 50 mm, for example. If the thickness of the sub-desalting chamber 440 is too thin, the water flow differential pressure is increased, which may cause damage to the sub-desalting chamber 440 and the like. This is because if the thickness of the sub-desalting chamber 40 is too thick, the flow may be uneven and current efficiency may be reduced.

  Regarding the method for producing deionized water in the present embodiment, the cathode chamber 410 and the main desalting chamber 450 are filled with an anion exchanger in a single bed form, and the anode chamber 420 and the sub-desalting chamber 440 are filled with a cation exchanger. This will be described by taking the case of filling in a single bed form as an example.

First, electrode water is caused to flow into the cathode chamber 410 from the electrode water inflow line 116, and electrode water is caused to flow into the anode chamber 420 from the electrode water inflow line 126. The concentrated water is caused to flow into the concentration chamber 160 from the concentrated water inflow line 162. Then, a DC voltage is applied between the cathode 112 and the anode 122. When a DC voltage is applied, the electrode reaction of the anode 122 causes an electrolytic reaction of water in the vicinity of the electrode shown in the following formula (3) in the anode chamber 420 to generate O ₂ and H ⁺ . The generated O ₂ is taken into the electrode water and discharged to the electrode water outflow line 128. On the other hand, the generated H ⁺ is attracted to the cathode 112 side which is the counter electrode, moves through the cation exchanger filled in the anode chamber 420, permeates the anode side partition membrane 424 which is the cation exchange membrane, and is sub-desalted. Move to chamber 440.

2H ₂ O → O ₂ + 4H ⁺ + 4e ⁻ (3)

Next, the water to be treated is caused to flow into the main desalting chamber 450 from the water to be treated inflow line 452. The treated water that has flowed in flows through the anion exchanger in the main desalting chamber 450 while diffusing, and flows out from the treated water outflow line 456. During this time, mainly anion components such as Cl ⁻ and HCO ₃ ^{— in the} water to be treated are adsorbed on the anion exchanger and removed from the water to be treated. Then, anion components such as Cl ⁻ and HCO ₃ ⁻ adsorbed on the anion exchanger are attracted to the anode 122 side, pass through the anion exchange membrane 154, and move to the concentration chamber 160. The anion component moved to the concentration chamber 160 is taken into the concentrated water and discharged from the concentrated water outflow line 164.

The treated water that has been circulated through the main desalting chambers 450 and merged in the treated water outflow line 456 is circulated through the treated water inflow line 444 via a pipe (not shown), and the auxiliary desalting chamber 440. Flow into. The treated water that has flowed in flows through the cation exchanger in the sub-demineralization chamber 440 while diffusing, becomes deionized water, and flows out from the deionized water outflow line 446. During this time, mainly cation components such as Na ⁺ and Ca ^{2+ in the} water to be treated are adsorbed by the cation exchanger and removed from the water to be treated. Then, cation components such as Na ⁺ and Ca ²⁺ adsorbed on the cation exchanger are exchanged by H ⁺ moved from the anode chamber 420 and desorbed from the cation exchanger. The desorbed cation component is attracted to the cathode 112 side, passes through the cation exchange membrane 442, and moves to the concentration chamber 160. The cation component moved to the concentration chamber 160 is taken into the concentrated water and discharged from the concentrated water outflow line 164. Thus, deionized water from which both anion components such as Cl ⁻ and HCO ₃ ⁻ and cation components such as Na ⁺ and Ca ²⁺ have been removed can be obtained.

  Although the to-be-processed water is not specifically limited, The water etc. which processed the water which removed the turbid component of industrial water and well water with the turbidity membrane with the reverse osmosis (RO) membrane, etc. are mentioned.

The amount of water to be treated in the sub-desalination chamber 440 is not particularly limited, and the ability of EDI 400, the quality of the water to be treated, the strength of the sub-desalination chamber 440, the treatment capacity of the main desalination chamber 450, etc. It can be decided in consideration. In the main desalination chamber 450, if the SV is too high, if the SV is too high, the ion removal performance decreases, or the differential pressure increases due to the increase in LV generated along with the increase in SV. This is not preferable because it causes damage to 440 and causes operational difficulties.
In addition, SV of the to-be-processed water in the sub desalination chamber 440 can be made higher than SV of the main desalination chamber 450. This is because, in the secondary desalting chamber 440, regeneration of the cation exchanger is performed satisfactorily, so that the cation component can be removed even when the treatment water is higher than SV in the main desalting chamber 450.

  The amount of water to be treated in main demineralization chamber 450 is not particularly limited, and can be determined in consideration of the quality of water to be treated and deionized water and the amount of treatment, and the main desalination chamber of the first embodiment. This is the same as the water flow amount at 150.

  The electrode water in the anode chamber 420 is not particularly limited, and water from the same water source as the water to be treated may be used as the electrode water, or the water treated in the main desalting chamber 450 or the sub-desalting chamber 440. The water treated in step 1 or water having a specific resistance of 0.2 to 18.2 MΩ · cm may be used as the electrode water. Especially, it is preferable that it is the water which distribute | circulated and processed through the main desalination chamber 450 or the sub-desalination chamber 440, or the water whose specific resistance value is 0.2-18.2 Mohm * cm. By using such water having few impurities such as a cation component and an anion component, it is possible to prevent a precipitate from being generated on the surface of the anode 122 and maintain current efficiency. The electrode water in the cathode chamber 410 is the same as the electrode water in the anode chamber 420.

  According to the present embodiment, the secondary desalting chamber 440 has high regeneration efficiency of the cation exchanger. Therefore, when performing the multi-stage processing, the sub-desalting chamber 440 has one post-stage treatment for the plurality of main desalting chambers 450 performing the pre-stage processing. This can be covered by the secondary desalination chamber 440. As a result, it is not necessary to provide the number of subsequent main desalting chambers corresponding to the number of main desalting chambers that perform the previous stage treatment, and the cathode is only provided by the amount of the subsequent main desalting chamber and the corresponding concentration chamber not installed. The distance between 112 and the anode 122 is shortened, and the operating voltage can be lowered.

(Fifth embodiment)
A fifth embodiment of EDI of the present invention will be described with reference to FIG. FIG. 6 is a cross-sectional view of the EDI 500 of the present embodiment. As shown in FIG. 6, the EDI 500 is arranged such that the main desalting chamber 550 is sandwiched between the concentration chamber 160 between the cathode chamber 110 and the anode chamber 420. A sub-desalting chamber 530 adjacent to the cathode chamber 110 via the cathode-side partition membrane 114 is provided, and a sub-desalting chamber 540 adjacent to the anode chamber 420 via the anode-side partition membrane 424 is provided. Then, the EDI 500 distributes the water to be treated that has been circulated through the sub-desalting chamber 530, distributes it to the plurality of main desalting chambers 550, joins the water to be treated that has circulated through the main desalting chamber 550, and It is made to distribute | circulate to the salt chamber 540.

  In the sub-desalting chamber 530, a cathode-side partition membrane 114, which is an anion exchange membrane, a frame 131, and an anion exchange membrane 132 are arranged in this order from the cathode 112 side, and the opening of the frame 131 is filled with an ion exchanger. Has been formed. A treated water inflow line 532 and a treated water outflow line 534 are connected to the sub-desalting chamber 530, and the treated water outflow line 534 is connected to the treated water inflow line 560 through a pipe (not shown). . And the to-be-processed water outflow line 534, the piping which is not shown in figure, and the to-be-processed water inflow line 560 comprise "the means to distribute | circulate the to-be-processed water which distribute | circulated the sub-desalination chamber to the main desalination chamber." .

  The main desalting chamber 550 includes a small desalting chamber 552 and a small desalting chamber 554. The small desalting chamber 552 is formed by arranging a cation exchange membrane 152, a frame body 353, and an intermediate ion exchange membrane 356 in this order from the cathode 112 side, and filling the ion exchanger in the opening of the frame body 353. Has been. The small desalting chamber 554 is formed by arranging an intermediate ion exchange membrane 356, a frame body 355, and an anion exchange membrane 154 in this order from the cathode 112 side, and an opening of the frame body 355 is filled with an ion exchanger. ing. The small desalting chamber 552 and the small desalting chamber 554 are adjacent to each other through an intermediate ion exchange membrane 356.

  The treated water inflow line 560 has a plurality of branch lines 562, and each of the branch lines 562 is connected to the small desalting chamber 552. A treated water outflow line 564 is connected to the small desalting chamber 552, and the treated water outflow line 564 is connected to the treated water inflow line 565 by a pipe (not shown). A treated water inflow line 565 and a treated water outflow line 568 are connected to the small desalting chamber 554. The treated water outflow line 568 is connected to the treated water inflow line 544 by a pipe (not shown). And the means to distribute the to-be-processed water which distribute | circulated the main desalination chamber to the sub-desalination chamber is comprised by the to-be-processed water outflow line 568, the piping which is not shown in figure, and the to-be-processed water inflow line 544. .

  In the sub-desalting chamber 540, a cation exchange membrane 442, a frame body 441, and an anode-side partition membrane 424 that is a cation exchange membrane are arranged in this order from the cathode 112 side, and the opening of the frame body 441 is filled with an ion exchanger. Has been formed. A treated water inflow line 544 and a deionized water outflow line 546 are connected to the sub-desalting chamber 540.

As the ion exchanger filled in the sub-desalting chamber 530, the same ion exchanger as that filled in the cathode chamber 110 can be used.
The filling form of the ion exchanger in the secondary desalting chamber 530 is not particularly limited, but preferably contains an anion exchanger, more preferably an anion exchanger single bed form, or a mixed bed of an anion exchanger and a cation exchanger. It is preferable to use a form or a double bed form. When the mixed bed form of the anion exchanger and the cation exchanger or the double bed form is used, the anion exchanger is preferably 50% by volume or more and less than 100% by volume. In the sub-desalting chamber 530 on the cathode chamber 110 side, anion components such as Cl ⁻ and HCO ₃ ⁻ are mainly removed from the water to be treated, and abundant OH ⁻ moving from the cathode chamber 110 is regenerated as an anion exchanger. This is because it can be used.

As the ion exchanger filled in the sub-desalting chamber 540, the same ion exchanger as that filled in the cathode chamber 110 can be used.
The filling form of the ion exchanger in the secondary desalting chamber 540 is not particularly limited, but preferably contains a cation exchanger, more preferably a single cation exchanger or a mixed bed of an anion exchanger and a cation exchanger. It is preferable to use a form or a double bed form. In the case of a mixed bed form of an anion exchanger and a cation exchanger or a double bed form, the cation exchanger is preferably 50% by volume or more and less than 100% by volume. In the secondary desalting chamber 540 on the anode chamber 420 side, cation components such as Na ⁺ and Ca ^{2+ in the} water to be treated are mainly removed, and abundant H ⁺ moving from the anode chamber 420 is used to regenerate the cation exchanger. This is because it can be used.

  The thicknesses of the sub-desalting chambers 530 and 540 are not particularly limited, and are preferably determined in consideration of the quality of the water to be treated and deionized water, the processing amount, the processing capacity of the main desalting chamber 550, and the like.

  The thickness of the small desalting chamber 552 is preferably determined in consideration of the quality of the water to be treated and deionized water, and the treatment amount, and is preferably determined in the range of 3 to 50 mm, for example. The thickness of the small desalting chamber 554 is the same as the thickness of the small desalting chamber 552. Note that the thicknesses of the small desalting chambers 552 and 554 may be the same or different.

  Regarding the method for producing deionized water in the present embodiment, the cathode chamber 110, the sub-desalting chamber 530, and the small desalting chamber 554 are filled with an anion exchanger in a single bed form, and the anode chamber 420 and the sub-desalting chamber 540 are filled. The case where the small desalting chamber 552 is filled with a cation exchanger in the form of a single bed will be described as an example.

From the treated water inflow line 532, the treated water flows into the sub-desalting chamber 530. The treated water that has flowed in flows through the anion exchanger in the sub-desalination chamber 530 while diffusing, and flows out from the treated water outflow line 534. During this time, anion components such as Cl ⁻ and HCO ₃ ^{— in the} water to be treated are adsorbed and removed by the anion exchanger. The anion exchanger is regenerated using OH ⁻ that has moved from the cathode chamber 110 to the sub-desalting chamber 530. Further, the pH of the water to be treated is adjusted to be inclined toward the alkaline side by OH ⁻ that has moved from the cathode chamber 110.

The treated water treated in the sub-desalination chamber 530 reaches the treated water inflow line 560 from the treated water outflow line 534 via a pipe (not shown), and is distributed to a plurality of branch lines 562 for small desalting. It flows into the salt chamber 552. The treated water that has flowed in flows through the cation exchanger in the small desalting chamber 552 while diffusing, and cation components such as Na ⁺ and Ca ²⁺ are removed. Here, even if the removal of the cation component in the water to be treated proceeds, the H ⁺ concentration is converted to H ₂ O due to the presence of OH ⁻ as a counter ion, and the water to be treated before flowing into the sub-desalting chamber 530. Lower than. For this reason, current efficiency becomes high and removal of cation components, such as Na ^<+> , Ca ^{< 2+ >} , in a to-be-processed water is performed favorably.

The treated water treated in the small desalting chamber 552 flows from the treated water outflow line 564 to the treated water inflow line 565 via a pipe (not shown) and flows into the small desalting chamber 554. The treated water that has flowed in flows through the anion exchanger in the small desalting chamber 554 while diffusing, and anion components such as Cl ⁻ and HCO ₃ ⁻ are removed.

The treated water treated in the small desalting chamber 554 flows through the treated water inflow line 544 from the treated water outflow line 568 through a pipe (not shown) and flows into the sub-desalting chamber 540. The treated water that has flowed in flows through the cation exchanger in the secondary demineralization chamber 540 while diffusing, becomes deionized water, and flows out from the deionized water outflow line 546. During this time, cation components such as Na ⁺ and Ca ^{2+ in the} water to be treated are adsorbed and removed by the cation exchanger. The cation exchanger is regenerated using H ⁺ that has moved from the anode chamber 420 to the sub-desalting chamber 540. Thus, deionized water from which both anion components such as Cl ⁻ and HCO ₃ ⁻ and cation components such as Na ⁺ and Ca ²⁺ have been removed can be obtained.

The amount of water to be treated in the sub-demineralization chamber 530 is not particularly limited. The capacity of the EDI 500, the quality of the water to be treated, the strength of the sub-desalination chamber 530, the treatment capacity of the main desalination chamber 550, etc. It can be decided in consideration. If the SV is too high in the sub-desalting chamber 530, the ion removal performance decreases, or the differential pressure increases due to the increase in LV that occurs with the increase in SV. This is not preferable because it may cause damage to the vehicle or cause operational difficulties. On the other hand, if the SV is too small, the flow distribution to the main desalting chamber 550 is not appropriately performed, the flow between the main desalting chambers 550 becomes uneven, and the performance of the EDI 500 as a whole may be adversely affected.
In addition, SV of to-be-processed water in the sub desalination chamber 530 can be made higher than SV of the main desalination chamber 550. This is because, in the secondary desalting chamber 530, the anion exchanger is regenerated well, so that the anion component can be removed even if it is higher than the SV to be treated in the main desalting chamber 550.

  The amount of water to be treated in the sub-desalination chamber 540 is the same as the amount of water to be treated in the sub-desalination chamber 530. Further, the SV of the water to be treated in the sub-desalting chamber 540 can be higher than the SV of the main desalting chamber 550. This is because, in the secondary desalting chamber 540, the cation exchanger is regenerated satisfactorily, so that the cation component can be removed even if it is higher than the SV of the water to be treated in the main desalting chamber 550.

  The amount of water to be treated in the small desalting chambers 552 and 554 of the main desalting chamber 550 is not particularly limited, and can be determined in consideration of the quality and amount of treated water and deionized water. This is the same as the water flow rate in the main desalting chamber 150 of the embodiment.

According to the present embodiment, the water to be treated is circulated in the order of the sub-desalination chamber 530, the small desalination chamber 552, the small desalination chamber 554, and the sub-desalination chamber 540, and the multi-stage treatment is performed. High and good quality deionized water can be obtained.
Here, in the conventional EDI, the water to be treated treated in an arbitrary main desalting chamber 550 is circulated to the other main desalting chamber 550, whereby multistage treatment equivalent to this embodiment can be performed. However, in this embodiment, the first stage processing is performed only in the sub-desalting chamber 530, and the fourth stage (final stage) processing is performed only in the sub-desalting chamber 540. The number of main desalting chambers 550 to perform can be greatly reduced. Accordingly, the number of concentration chambers 160 can be significantly reduced. As a result, the distance between the cathode 112 and the anode 122 can be shortened, and the EDI can be operated at a low voltage. Further, since the number of main desalting chambers 550 and concentration chambers 160 can be reduced, EDI can be made compact.

  Furthermore, according to the present embodiment, by providing a single-bed type small desalting chamber and performing multi-stage treatment, the movement of ionic components in each small desalting chamber is unidirectional, and the anion component and cation component are good. Can be removed.

  The present invention is not limited to the above-described embodiment. In the first to third embodiments, the water to be treated is circulated through the sub-desalting chamber provided on the cathode side and then circulated through the main desalting chamber. However, the distribution order of the water to be treated is not limited to this, and the water to be treated that has circulated through the main desalting chamber may be circulated to the sub-desalting chamber as in the fourth embodiment.

  In 4th Embodiment, the to-be-processed water processed by the main desalting chamber is distribute | circulated to the sub desalting chamber provided in the anode side. However, the flow order of the water to be treated is not limited to this, and the water to be treated that has circulated through the sub-desalting chamber may be circulated to the main desalting chamber as in the first to third embodiments.

  In the third and fifth embodiments, the main desalting chamber is partitioned into two small desalting chambers by an intermediate ion exchange membrane, but the main desalting chamber is partitioned into three or more small desalting chambers. May be. In the fifth embodiment, the main desalting chamber is divided into two small desalting chambers by an intermediate ion exchange membrane. However, as in the first and second embodiments, the main desalting chamber. May not be partitioned by the intermediate ion exchange membrane.

  In the fourth embodiment, the main desalting chamber may be an intermediate ion exchange membrane having a small desalting chamber divided into two or more.

  In the first to fourth embodiments, the cathode chamber and the anode chamber are filled with the ion exchanger, but the electrode chamber filled with the ion exchanger may be only the electrode chamber adjacent to the sub-desalting chamber. good.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, it is not limited to an Example.
(Water quality evaluation)
<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).

Example 1
A main desalination chamber is provided, which is divided into two small desalination chambers by an intermediate ion exchange membrane, similar to the EDI 300 shown in FIG. 4 except that one main desalination chamber is used. An EDI having a concentration chamber on both sides and a sub-desalting chamber on the cathode chamber side was produced according to the following specifications to obtain EDI-A. The obtained EDI-A was continuously operated under the following operating conditions. The water to be treated is circulated in a downward flow to a sub-desalination chamber provided on the cathode chamber side, and then circulated in a downward flow to a small desalination chamber on the cation exchange membrane side, and then small desalination on the anion exchange membrane side. It was circulated in the chamber in a downward flow.
Concentrated water was circulated and drained in a downward flow to each concentrating chamber, and electrode water was circulated and drained to the cathode chamber and the anode chamber, respectively.
The operating voltage and the specific resistance of deionized water at 1000 hours after the start of operation were measured, and the results are shown in Table 1.

<EDI 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) Small desalting chamber on the anion exchange membrane side: Width 100mm, height 300mm, thickness 6mm
(5) Small desalination chamber on the cation exchange membrane side: width 100 mm, height 300 mm, thickness 6 mm
(6) Filling ion exchanger in the small desalting chamber on the anion exchange membrane side: Single bed form of anion exchange resin (Rohm and Haas) (7) Filling ion exchange in the small desalting chamber on the cation exchange membrane side Body: Single-floor form of cation exchange resin (Rohm and Haas) (8) Concentration chamber: width 100 mm, height 300 mm, thickness 4 mm
(9) Packing ion exchanger in concentration chamber: single-bed form of anion exchange resin (10) Cathode chamber: width 100 mm, height 300 mm, thickness 4 mm
(11) Anode chamber: width 100 mm, height 300 mm, thickness 4 mm
(12) Filling ion exchanger in the cathode chamber: single bed form of anion exchange resin (13) Filling ion exchanger in the anode chamber: single bed form of cation exchange resin (14) Sub-desalting chamber: width 100 mm, height 300 mm , Thickness 4mm
(15) Filling ion exchanger in sub-demineralization chamber: single bed form of anion exchange resin

<Operating conditions>
(1) Conductivity of water to be treated: 17 to 23 μS / cm (NaCl / ultra pure water)
(2) Specific resistance of water to be treated: 0.043 to 0.059 MΩ · cm
(3) Processed water flow rate: 40L / h
(4) Conductivity of concentrated water: 17 to 23 μS / cm (NaCl / ultra pure water)
(5) Concentrated water flow rate: 20 L / h
(6) Specific resistance of electrode water: Ultrapure water with specific resistance exceeding 15 MΩ · cm (7) Flow rate of electrode water: 10 L / h
(9) Operating current value: 0.25A

(Comparative Example 1)
The conventional EDI used in Comparative Example 1 will be described with reference to FIG.
FIG. 7 is a cross-sectional view of a conventional EDI 900. As shown in FIG. In the EDI 900, one main desalting chamber 950 and a concentrating chamber 960 provided on both sides of the main desalting chamber 950 are disposed between the cathode chamber 910 and the anode chamber 920.
The cathode chamber 910 is formed by sequentially arranging a cathode 912, a frame body 911, and a cathode-side partition film 914 that is an anion exchange membrane, and an opening of the frame body 911 is filled with an anion exchange resin. The anode chamber 920 is formed by sequentially arranging an anode 922, a frame body 921, and an anode side partition film 924 that is a cation exchange membrane, and an opening portion of the frame body 921 is filled with a cation exchanger.
An electrode water inflow line 916 and an electrode water outflow line 918 are connected to the cathode chamber 910, and an electrode water inflow line 926 and an electrode water outflow line 928 are connected to the anode chamber 920.

The main desalting chamber 950 includes a small desalting chamber 951 and a small desalting chamber 952 that is adjacent to the small desalting chamber 951 with an intermediate ion exchange membrane 955 interposed therebetween. The small desalting chamber 951 is formed by sequentially arranging a cation exchange membrane 953, a frame body 954, and an intermediate ion exchange membrane from the cathode 912 side, and filling an opening of the frame body 954 with a cation exchange resin. Yes. The small desalting chamber 952 is formed by arranging an intermediate ion exchange membrane 955, a frame body 956, and an anion exchange membrane 957 in this order from the cathode 912 side, and filling an opening of the frame body 956 with an anion exchange resin. Yes.
A treated water inflow line 970 and a treated water outflow line 972 are connected to the small desalting chamber 951. A treated water inflow line 974 and a deionized water outflow line 976 are connected to the small desalting chamber 952. And the to-be-processed water outflow line 972 and the to-be-processed water inflow line 974 are connected by piping which is not shown in figure.

  The concentration chamber 960 is formed by disposing a frame 961 on both sides of the main desalting chamber 950 and filling an opening of the frame 961 with an anion exchanger. A concentrated water inflow line 962 and a concentrated water outflow line 964 are connected to the concentration chamber 960.

As with EDI900, one main desalting chamber 950 was placed and manufactured according to the following specifications to obtain EDI-B. Using EDI-B, continuous operation was performed under the same operation conditions as in Example 1. In operation, after the treated water is circulated through the small desalting chamber 951 from the treated water inflow line 970 in a downward flow, the small desalination chamber 952 is passed through the treated water outflow line 972 and the treated water inflow line 974. Was allowed to flow in a downward flow, and deionized water was caused to flow out from the deionized water outflow line 976 to obtain deionized water. Concentrated water was circulated and drained to each concentrating chamber in a downward flow, and electrode water was circulated and drained to the cathode chamber 910 and the anode chamber 920, respectively.
The operating voltage and the specific resistance of deionized water at 1000 hours after the start of operation were measured, and the results are shown in Table 1.

<EDI 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) Small desalting chamber on the anion exchange membrane side: Width 100mm, height 300mm, thickness 6mm
(5) Small desalination chamber on the cation exchange membrane side: width 100 mm, height 300 mm, thickness 6 mm
(6) Filling ion exchanger in the small desalting chamber on the anion exchange membrane side: Single bed form of anion exchange resin (Rohm and Haas) (7) Filling ion exchange in the small desalting chamber on the cation exchange membrane side Body: Single-floor form of cation exchange resin (Rohm and Haas) (8) Concentration chamber: width 100 mm, height 300 mm, thickness 4 mm
(9) Packing ion exchanger in concentration chamber: single-bed form of anion exchange resin (10) Cathode chamber: width 100 mm, height 300 mm, thickness 4 mm
(11) Anode chamber: width 100 mm, height 300 mm, thickness 4 mm
(12) Filling ion exchanger in the cathode chamber: single bed form of anion exchange resin (13) Filling ion exchanger in the anode chamber: single bed form of cation exchange resin

As shown in Table 1, the deionized water obtained in Example 1 had a higher specific resistance than the deionized water obtained in Comparative Example 1. From this, it was found that the quality of the deionized water obtained can be improved by circulating the treated water treated in the auxiliary desalting chamber to the main desalting chamber.
In Example 1, the operation voltage 1000 hours after the start of operation was 7V, while in Comparative Example 1, it was 26V, which was about 3.7 times that of Example 1. From this, it can be seen that the provision of the sub-desalting chamber as in Example 1 makes it possible to effectively use the current even when the distance between the electrodes is increased, so that deionized water can be produced with energy saving. It was.

It is a schematic diagram explaining the flow of the ion component in EDI8 of this invention. It is sectional drawing which shows EDI concerning the 1st Embodiment of this invention. It is sectional drawing which shows EDI concerning the 2nd Embodiment of this invention. It is sectional drawing which shows EDI concerning the 3rd Embodiment of this invention. It is sectional drawing which shows EDI concerning the 4th Embodiment of this invention. It is sectional drawing which shows EDI concerning the 5th Embodiment of this invention. 6 is a schematic diagram showing a conventional EDI used in Comparative Example 1. FIG.

Explanation of symbols

8, 100, 200, 300, 400, 500, 900 Electric deionized water production apparatus 10, 110, 410, 910 Cathode chamber 12, 112, 912 Cathode 14, 114, 414, 914 Cathode side partition membrane 24, 124, 424, 924 Anode-side partition membrane 20, 120, 420, 920 Anode chamber 22, 122, 922 Anode 30, 40, 130, 230, 330, 440, 530, 540 Sub-desalting chamber 50, 150, 155, 250, 350 450, 550, 950 Main desalination chamber 32, 54, 132, 154, 957 Anion exchange membrane 42, 52, 152, 442, 953 Cation exchange membrane 60, 62, 160, 960 Concentration chamber 136, 157, 236, 336 364, 456, 534, 564, 568, 972 To-be-treated water outflow lines 156, 158, 52, 360, 365, 444, 452, 544, 560, 565, 970, 974 Untreated water inflow line 254, 362, 562 Branch line 352, 354, 552, 554, 951, 952 Small desalination chamber 356, 955 Intermediate Ion exchange membrane

Claims (8)

The space partitioned by the cation exchange membrane on one side and the anion exchange membrane on the other side is filled with an ion exchanger, and one or more main desalting chambers are provided,
A concentration chamber is provided on both sides of the main desalting chamber via the cation exchange membrane or the anion exchange membrane,
The main desalting chamber and the concentration chamber are disposed between an anode chamber partitioned by an anode and an anode side partition membrane, and a cathode chamber partitioned by a cathode and a cathode side partition membrane,
The anode-side partition membrane is a cation exchange membrane, the ion chamber is filled with an ion exchanger, and a space defined by the anode-side partition membrane and the cation-exchange membrane disposed opposite to the anode-side partition membrane. A sub-desalting chamber formed by filling an ion exchanger and / or the cathode side partition membrane as an anion exchange membrane, the cathode chamber filled with an ion exchanger, the cathode side partition membrane and the cathode side A sub-demineralization chamber formed by filling an ion exchanger is provided in a space defined by an anion exchange membrane disposed opposite to the partition membrane,
Means for circulating the treated water flowing through the sub-desalting chamber to the main desalting chamber and / or means for circulating the treated water flowing through the main desalting chamber to the sub-desalting chamber are provided. Electric deionized water production equipment.   Between the anode chamber and the cathode chamber, two or more main demineralization chambers are arranged via the concentration chamber, and the water to be treated that has circulated through the sub-demineralization chamber is used as an arbitrary main demineralization chamber. The electric deionized water production apparatus according to claim 1, wherein the water to be treated which is circulated and circulated through the arbitrary main demineralization chamber is circulated to another main demineralization chamber.   Between the anode chamber and the cathode chamber, two or more main desalting chambers are arranged via the concentration chamber, and the water to be treated which circulates through any main desalting chamber is used as another main desalting chamber. The electric deionized water production apparatus according to claim 1, wherein the water to be treated that has been circulated through the main demineralization chamber is circulated through the sub-demineralization chamber.   Two or more main desalting chambers are arranged between the anode chamber and the cathode chamber via the concentration chamber, and the treated water distributed through the sub-desalting chamber is distributed and distributed. The electric deionized water production apparatus according to claim 1, wherein water is circulated through the main demineralization chamber.   Between the anode chamber and the cathode chamber, two or more main desalting chambers are arranged via the concentration chamber, and the water to be treated that has circulated through the main desalting chambers is merged and merged. The electric deionized water production apparatus according to claim 1, wherein the water to be treated is circulated through the sub-demineralization chamber.   In the main desalination chamber, an intermediate ion exchange membrane is disposed between the cation exchange membrane on one side and the anion exchange membrane on the other side, and the small desalination is divided into multiple stages in the thickness direction of the main desalination chamber. The electric deionized water production apparatus according to any one of claims 1 to 5, wherein a salt chamber is formed.   The water treated in the main desalting chamber or the sub-desalting chamber is passed through the anode chamber and / or the cathode chamber, according to any one of claims 1 to 6. The electric deionized water production apparatus according to claim 1.   8. The water according to claim 1, wherein water having a specific resistance value of 0.2 to 18.2 MΩ · cm is passed through the anode chamber and / or the cathode chamber. The electrical deionized water production apparatus according to 1.

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