JP2013013830A - Electric deionized water production apparatus and deionized water production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric deionized water production apparatus and a deionized water production method which solve problems occurring when water to be treated is used as electrode water with saving cost.SOLUTION: The apparatus includes electrode chambers E1 and E2 which are composed of an anode chamber E1 and a cathode chamber E2, cation desalination chambers D1 and S1 which are adjacent with cation exchange films c1 and c2 on the side of the cathode chamber E2 and filled with at least a cation exchange body, and anion desalination chambers D2 and S2 which are adjacent with anion exchange films a1 and a2 on the side of the anode chamber E1 and filled with at least an anion exchange body. The cation desalination chambers D1 and S1, and the anion desalination chambers D2 and S2 are communicated with each other so that a part of intermediate treated water in which at least a cation component is removed, flowing out from the cation desalination chambers D1 and S1, flows into the anion desalination chambers D2 and S2. The cation desalination chambers D1 and S1 and the electrode chambers E1 and E2 are communicated with each other so the other part of the intermediate treated water flowing out from the cation desalination chambers D1 and S1 flows into the electrode chambers E1 and E2.

Description

  The present invention relates to an electrical deionized water production apparatus and a deionized water production method.

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

  The electric deionized water production apparatus is an apparatus that combines electrophoresis and electrodialysis. The electric deionized water production apparatus is filled with an ion exchanger between an anion exchange membrane and a cation exchange membrane to form a main desalting chamber, and a concentration chamber is provided outside the anion exchange membrane and the cation exchange membrane. This is an apparatus in which an anode chamber having an anode on the outside and a cathode chamber having a cathode are arranged.

In order to produce deionized water (treated water) using an electrical deionized water production apparatus, water to be treated is passed through the main demineralization chamber with a DC voltage applied to the electrodes. The ionic component in the water to be treated is adsorbed by the ion exchanger in the demineralization chamber and subjected to deionization (demineralization) treatment. In the desalting chamber, a dissociation reaction of water occurs at the interface of the different ion exchanger, that is, the interface between the anion exchanger and the cation exchanger in the desalting chamber due to the applied voltage, and hydrogen ions and hydroxide ions are generated ( H ₂ O → H ⁺ + OH ⁻ ). The ionic component adsorbed on the ion exchanger is exchanged with the hydrogen ions and hydroxide ions, and is released from the ion exchanger. The liberated ion component is electrophoresed to the ion exchange membrane, electrodialyzed on the ion exchange membrane, and discharged into the concentrated water flowing through the concentration chamber. Thus, in the electric deionized water production apparatus, hydrogen ions and hydroxide ions continuously act as acid and alkali regenerators for regenerating the ion exchanger. For this reason, the regeneration by the medicine is basically unnecessary, and the continuous operation can be performed without the regeneration of the ion exchanger by the medicine.

By the way, electrolysis (electrode reaction) of water occurs in the anode chamber and the cathode chamber of the above-described electric deionized water production apparatus, and this reaction causes oxygen (2H ₂ O → O ₂ + 4H ⁺ + 4e ⁻ ) in the anode chamber. In the cathode chamber, hydrogen (2H ₂ O + 2e ⁻ → H ₂ + 2OH ⁻ ) is generated. In order to discharge these gas components to the outside, electrode water is supplied to the electrode chambers (anode chamber and cathode chamber). In many cases, water to be treated is used as the electrode water, which causes the following problems.

  In the cathode chamber, hydroxide ions are generated together with hydrogen by the electrode reaction described above. Therefore, the liquidity of the electrode water flowing through the cathode chamber (cathode surface) tends to be alkaline. Therefore, when treated water containing a large amount of hardness component is used as electrode water, magnesium hydroxide is mainly used in the vicinity of the cathode surface due to the hardness component attracted to the cathode surface and hydroxide ions generated by the electrode reaction. A scale may be generated as a component. When the scale is generated, the electric resistance at that portion increases, and the operating voltage increases, thereby increasing the power consumption.

  As a method for coping with such a problem, for example, Patent Documents 1 and 2 disclose a method of using treated water that has flowed out of a desalting chamber and deionized as electrode water. Since the treated water contains almost no cation component, particularly a hardness component, scale generation in the cathode chamber can be suppressed.

Japanese Patent No. 3801621 Japanese Patent No. 3788318

  In order to supply the treated water that has flowed out of the desalting chamber to the electrode chamber, it is necessary to increase the supply pressure of the treated water to the electrode chamber, that is, the back pressure at the outlet of the desalting chamber, in consideration of pressure loss due to the electrode chamber. is there. For this purpose, it is necessary to install a pump with a large output at the front stage of the electric deionized water production apparatus to increase the supply pressure of the water to be treated. However, use of a large pump is not preferable because it leads to an increase in cost.

  Therefore, the present invention provides an electrical deionized water production apparatus and a deionized water production method that eliminates problems that occur when treated water is used as electrode water, such as scale generation in the cathode chamber, while suppressing an increase in cost. The purpose is to provide.

  In order to achieve the above-described object, an electric deionized water production apparatus of the present invention is an electric deionized water production apparatus for producing deionized water by treating water to be treated, and an anode provided with an anode. An electrode chamber comprising a chamber and a cathode chamber provided with a cathode; and a cation desalting chamber located between the anode chamber and the cathode chamber, adjacent to the cation exchange membrane on the cathode chamber side and filled with at least a cation exchanger And an anion exchange membrane and an anion deionization chamber which are adjacent to the anode chamber side and are filled with at least an anion exchanger. The salt chamber is communicated so that the water to be treated flows into the cation demineralization chamber and a part of the intermediate treated water from which at least the cation component has been removed through the cation demineralization chamber flows into the anion demineralization chamber. The cation desalination chamber and the electrode chamber Another part of the intermediate processing water flowing out of the desalting compartment is communicated to flow into the electrode chamber.

  The deionized water production method of the present invention includes an electrode chamber composed of an anode chamber having an anode and a cathode chamber having a cathode, and a cation exchange membrane and a cathode chamber, which are located between the anode chamber and the cathode chamber. A cation desalination chamber that is adjacent on the side and filled with at least a cation exchanger, and located between the anode and cathode chambers, adjacent to the anion exchange membrane and the anode chamber side, and at least filled with an anion exchanger A deionized water production method for producing deionized water by treating water to be treated using an electric deionized water production apparatus having an anion demineralization chamber, wherein the treated water is converted into a cation demineralization chamber. Flowing, generating intermediate treated water from which at least the cation component has been removed, flowing a portion of the intermediate treated water that has flowed out of the cation desalting chamber into the anion desalting chamber, and intermediate that has flowed out of the cation desalting chamber The other part of the treated water, the electrode chamber And includes a step of flowing, the.

  In such an electrical deionized water production apparatus and deionized water production method, the cation component of the water to be treated that has flowed into the cation demineralization chamber is adsorbed to the cation exchanger, and the cation component, particularly The intermediate treated water from which the hardness component has been removed flows out. Since the intermediate treated water partially flows into the anion desalting chamber, the water pressure of the intermediate treated water at the outlet of the cation desalting chamber is higher than the water pressure of the treated water at the outlet of the anion desalting chamber. Inevitably higher. It is possible to easily cause a part of such intermediate treated water to flow into the electrode chamber by changing the piping, etc., which is greater than when installing a pump with a large output in the front stage of the device. There is no cost increase. In addition, since the intermediate treated water from which the hardness component has been removed is used as the electrode water, the inflow of the hardness component into the cathode chamber can be suppressed. As a result, similarly to the case where treated water is used as the electrode water, it is possible to suppress the generation of scale in the cathode chamber and suppress the increase in operating voltage and the accompanying increase in power consumption.

  As described above, according to the present invention, an electric deionized water production apparatus that eliminates problems that occur when treated water is used as electrode water, such as scale generation in the cathode chamber, while suppressing an increase in cost, and A method for producing deionized water can be provided.

It is a schematic block diagram of the electric deionized water manufacturing apparatus which concerns on one Embodiment of this invention. It is a schematic block diagram which shows the other structural example of the electrical deionized water manufacturing apparatus which concerns on one Embodiment of this invention.

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

  FIG. 1 is a schematic configuration diagram of an electric deionized water production apparatus according to an embodiment of the present invention. The electric deionized water production apparatus 1 includes a main demineralization chamber D and a pair of concentrators located on both sides of the main demineralization chamber D between an anode chamber E1 having an anode 4 and a cathode chamber E2 having a cathode 5. Chambers C1 and C2, a secondary cation desalting chamber S1 located between the concentrating chamber C1 and the anode chamber E1, and a secondary anion desalting chamber S2 located between the concentrating chamber C2 and the cathode chamber E2, are provided. Are partitioned by ion exchange membranes a1 to a3 and c1 to c3. In the following description, the enrichment chamber adjacent to the main desalting chamber D on the anode side is referred to as the anode concentration chamber C1, and the enrichment chamber adjacent to the main desalination chamber D on the cathode side is referred to as the cathode concentration chamber C2.

  The anode side concentrating chamber C1 is adjacent to the main desalting chamber D via the first anion exchange membrane a1, and the cathode side concentrating chamber C2 is adjacent to the main desalting chamber D via the first cation exchange membrane c1. Yes. The secondary cation desalting chamber S1 is adjacent to the anode-side concentration chamber C1 via the second cation exchange membrane c2, and is adjacent to the anode chamber E1 via the third cation exchange membrane c3. The secondary anion demineralization chamber S2 is adjacent to the cathode-side concentration chamber C2 via the second anion exchange membrane a2, and is adjacent to the cathode chamber E2 via the third anion exchange membrane a3.

  The main desalting chamber D has a main cation desalting chamber D1 adjacent to the first cation exchange membrane c1, and a main anion desalting chamber D2 adjacent to the first anion exchange membrane a1. The main cation desalting chamber D1 and the main anion desalting chamber D2 are adjacent to each other through the intermediate ion exchange membrane 3.

The main cation desalting chamber D1 is filled with at least a cation exchanger, and mainly cation components (Na ⁺ , Ca ²⁺ , Mg ^2+, etc.) in the water to be treated are removed. Examples of the cation exchanger include a cation exchange resin, a cation exchange fiber, and a monolithic porous cation exchanger, and the most versatile cation exchange resin is preferably used. Examples of the cation exchanger include weakly acidic cation exchangers and strongly acidic cation exchangers. As a filling form of the ion exchanger filled in the main cation desalting chamber D1, a single bed form of the cation exchanger can be mentioned. In addition, as long as the cation exchanger that can sufficiently remove the cation component (hardness component) in the water to be treated is packed, the mixed bed form with the anion exchanger or the multiple bed form may be used.

The main anion demineralization chamber D2 is filled with at least an anion exchanger and mainly contains anion components (Cl ⁻ , CO ₃ ²⁻ , HCO ₃ ⁻ , SiO ₂ (silica can take a special form) in the water to be treated. Therefore, the display is different from that of general ions). Examples of the anion exchanger include anion exchange resins, anion exchange fibers, and monolithic porous anion exchangers, and the most general anion exchange resin is preferably used. Examples of the anion exchanger include weakly basic anion exchangers and strong basic anion exchangers. The main anion desalting chamber D2 may be further filled with a cation exchanger. Examples of the filling form of the anion exchanger filled in the main anion desalting chamber D2 include a single bed form of the anion exchanger, a mixed bed form of an anion exchanger and a cation exchanger, or a multiple bed form.

  The intermediate ion exchange membrane 3 is selected in consideration of the quality of the water to be treated, the water quality required for the deionized water, the type of ion exchanger filled in the main cation demineralization chamber D1 or the main anion demineralization chamber D2, and the like. Can do. The intermediate ion exchange membrane 3 may be either an anion exchange membrane or a single membrane of a cation exchange membrane, or a composite membrane having both an anion exchange membrane and a cation exchange membrane.

  Thus, the main desalting chamber D is divided into two small desalting chambers, a main cation desalting chamber D1 and a main anion desalting chamber D2, and a concentration chamber is adjacent to the outside of each of the small desalting chambers D1 and D2. The configuration (two main demineralization chamber configurations) enables multi-stage treatment of water to be treated, and is effective in improving deionization performance. Moreover, since it is not necessary to provide a concentrating chamber between the main cation desalting chamber D1 and the main anion desalting chamber D2, the applied voltage between the anode and the cathode can be suppressed, the power consumption is reduced, and the operating cost is reduced. Is possible.

  The anode side concentrating chamber C1 is provided to take in the anion component discharged from the main anion demineralization chamber D2 and the cation component discharged from the sub-cation demineralization chamber S1, and to release them out of the system. The cathode concentration chamber C2 is provided to take in the cation component discharged from the main cation demineralization chamber D1 and the anion component discharged from the secondary anion demineralization chamber S2, and to release them out of the system. Concentration chamber supply water flows into each of the concentration chambers C1 and C2, and the concentration chamber supply water becomes concentrated water containing a cation component and an anion component and is discharged from each of the concentration chambers C1 and C2. As the concentrating chamber supply water, a part of the water to be treated is used in this embodiment, but it can also be supplied by a separate concentrating chamber supply water supply line. In order to suppress the electric resistance of the electric deionized water production apparatus 1, the concentration chambers C1 and C2 may be filled with an ion exchanger.

  The sub cation demineralization chamber S1 has the same configuration as the main cation demineralization chamber D1, but only the cation exchanger is filled with a single bed.

  The secondary anion desalting chamber S2 has the same configuration as the main anion desalting chamber D2, but only the anion exchanger is filled with a single bed.

  In the electrode chambers (anode chamber and cathode chamber) E1 and E2, decationized water (intermediate treated water) from which the cation component has been removed in the main cation demineralization chamber D1 and the auxiliary cation demineralization chamber S1, as described later in detail. ) Flows in as electrode water. As described above, these electrode waters generate hydrogen ions and hydroxide ions by electrolysis near the electrodes. Therefore, in order to suppress the electrical resistance of the electrical deionized water production apparatus 1, it is preferable that the anode chamber E1 and the cathode chamber E2 are filled with an ion exchanger. Thereby, the movement of hydrogen ions to the secondary cation desalting chamber S1 and the movement of hydroxide ions to the secondary anion desalting chamber S2 described later are smoothly performed.

  Examples of the ion exchanger filled in the anode chamber E1 and the cathode chamber E2 include ion exchange resins, ion exchange fibers, and monolithic porous ion exchangers, and the most general-purpose ion exchange resins are preferably used. In the case of the anode chamber E1, as a kind of cation exchanger with which it fills, a weak acidic cation exchanger, a strong acidic cation exchanger, etc. are mentioned, As the filling form, single bed filling is mentioned. In the case of the cathode chamber E2, the types of anion exchangers to be filled include weakly basic anion exchangers, strong basic anion exchangers, and the like, and the packing form includes single bed filling.

The anode chamber E1 accommodates the anode 4. The anode 4 is made of a metal net or plate. If Cl ⁻ is contained in the flowing electrode water, chlorine is generated at the anode 4. For this reason, it is desirable to use a material having chlorine resistance for the anode 4, and examples thereof include a metal such as platinum, palladium, iridium, or a material obtained by coating titanium with these metals.

  The cathode chamber E2 accommodates the cathode 5. The cathode 5 is made of a metal net or plate, and for example, a stainless steel net or plate can be used.

  Each electrode chamber E1, E2, main cation demineralization chamber D1, main anion demineralization chamber D2, each concentration chamber C1, C2, sub cation demineralization chamber S1, and sub anion demineralization chamber S2 each have an opening. It is provided inside the frame 2 that is a plate-like member. In FIG. 1, the frame body 2 is shown integrally, but actually, a separate frame body is provided for each room, and the frame bodies are provided in close contact with each other. The frame body 2 is not particularly limited as long as it has an insulating property and does not leak in water to be treated. For example, polyethylene, polypropylene, polyvinyl chloride, ABS, polycarbonate, m-PPE (modified polyphenylene ether), etc. Can be mentioned.

  Several flow paths U1 to U4 and L1 to L5 are provided for communication between rooms, supply and discharge of water to be treated, electrode water, and the like.

  One end of the flow path U1 located in the upper part of the electrical deionized water production apparatus 1 is connected to the supply side of the water to be treated, and the other end side branches into some parts along the main cation demineralization chamber D1. The secondary cation desalting chamber S1 is connected to each of the concentration chambers C1 and C2. The flow path L1 located in the lower part of the electric deionized water production apparatus 1 is connected to the main cation demineralization chamber D1 and the sub cation demineralization chamber S1, and merges in the middle and is connected to one end of the transition pipe Y1. Yes. The other end of the transition pipe Y1 is connected to a flow path U2 located in the upper part of the electric deionized water production apparatus 1, and the flow path U2 branches in the middle to decouple the main anion demineralization chamber D2 and the secondary anion deionization. It is connected to the salt chamber S2. The flow path L2 located in the lower part of the electric deionized water production apparatus 1 is connected to the main anion demineralization chamber D2 and the subanion demineralization chamber S2, and merges in the middle and is connected to the outflow side of the treated water. Yes. The flow path L5 located in the lower part of the electric deionized water production apparatus 1 is connected to each of the concentrating chambers C1 and C2, joins in the middle, and is connected to the concentrated water outflow side.

  The flow path L3 located in the lower part of the electric deionized water production apparatus 1 is connected to the crossover pipe Y1 on one end side and to the cathode chamber E2 on the other end side. That is, a part of the decationized water that has flowed out of the main cation demineralization chamber D1 and the subcation demineralization chamber S1 is allowed to flow into the main anion demineralization chamber D2 and the subanion demineralization chamber S2. Is allowed to flow into the cathode chamber E2. The flow path U3 located in the upper part of the electric deionized water production apparatus 1 is connected to the cathode chamber E2 on one end side and to the crossover pipe Y2 on the other end side. The other end of the transition pipe Y2 is connected to a flow path L4 located at the lower part of the electric deionized water production apparatus 1, and the flow path L4 is connected to the anode chamber E1. A flow path U4 is connected to the upper part of the anode chamber E1, so that the electrode water (decationized water) flowing into the cathode chamber E2 passes through the flow path U3, the crossover pipe Y2, and the flow path L4. It flows into E1 and is discharged from the anode chamber E1 through the flow path U4.

  In FIG. 1, the flow paths U <b> 1 to U <b> 3, L <b> 1 to L <b> 5 are positioned outside the frame body 2 for convenience of illustration, but these flow paths U <b> 1 to U <b> 4, L <b> 1 to L <b> 5 are built in the frame body 2. It is advantageous.

  Next, the flow of water to be treated and the principle of deionization will be described with reference to FIG.

  In advance, a part of the water to be treated is supplied from the flow path U1 to the concentration chambers C1 and C2 as the supply water for the concentration chamber and discharged from the flow path L5. Electrode water (currently treated water that has just passed through the main cation demineralization chamber D1 and the sub cation demineralization chamber S1) is supplied to the electrode chambers E1 and E2 from the flow path L3 and discharged from the flow path U4. Keep it. A predetermined voltage is applied between the anode 4 and the cathode 5. In this state, the water to be treated is caused to flow in parallel from the flow path U1 into the main cation desalting chamber D1 and the sub cation desalting chamber S1. The cation component is removed from the water to be treated in the main cation demineralization chamber D1 and the sub cation demineralization chamber S1.

Specifically, a cation component such as Mg ²⁺ is adsorbed on the cation exchanger filled in the main cation demineralization chamber D1 in the main cation demineralization chamber D1. In the main desalting chamber D, a reaction (water dissociation reaction) in which water dissociates into hydrogen ions (hereinafter referred to as “H ⁺ ”) and hydroxide ions (hereinafter referred to as “OH ⁻ ”) continuously proceeds. doing. H ⁺ is exchanged with a cation component such as Mg ²⁺ adsorbed on the cation exchanger, and the cation exchanger filled in the main cation desalting chamber D1 is regenerated. The removed cation component such as Mg ²⁺ is attracted to the cathode 5 side by the potential difference between the anode 4 and the cathode 5, passes through the first cation exchange membrane c 1, and flows into the cathode side concentration chamber C 2.

In the secondary cation desalting chamber S1, cation components such as Mg ²⁺ are adsorbed by the cation exchanger filled in the secondary cation desalting chamber S1. In the anode chamber E1, a reaction in which oxygen gas and H ⁺ are generated from water by an electrode reaction (2H ₂ O → O ₂ + 4H ⁺ + 4e ⁻ ) proceeds continuously. The oxygen gas rises in the anode chamber E1 and is discharged out of the electric deionized water production apparatus 1 together with the electrode water. H ⁺ flows into the secondary cation desalting chamber S1 through the third cation exchange membrane c3. H ⁺ flowing into the secondary cation desalting chamber S1 is exchanged with the cation component adsorbed on the cation exchanger, and the cation exchanger is regenerated. The removed cation component such as Mg ²⁺ is attracted to the cathode 5 side by the potential between the anode 4 and the cathode 5, passes through the second cation exchange membrane c2, and flows into the anode side concentrating chamber C1.

The water from which the cation component such as Mg ²⁺ has been removed in this way (decationized water) is merged in the flow path L1, and a part thereof flows into the flow path U2 through the transition pipe Y1, and the other one. Part flows into the flow path L3 from the crossover pipe Y1.

  The decationized water flowing into the flow path U2 flows in parallel into the main anion demineralization chamber D2 and the subanion demineralization chamber S2, and the anion component is removed in the main anion demineralization chamber D2 and the subanion demineralization chamber S2. The

Specifically, an anion component such as Cl 2 ⁻ is adsorbed to the anion exchanger filled in the main anion desalting chamber D2 in the main anion desalting chamber D2. In the main desalting chamber D, as described above, OH ⁻ is continuously generated by the water dissociation reaction. OH ⁻ is exchanged with an anion component such as Cl 2 ⁻ adsorbed on the anion exchange resin to regenerate the anion exchanger. Cl has been removed ^- anionic components such as the anode 4, are attracted to the anode 4 side by the potential difference between the cathode 5 passes through the first anion exchange membrane a1 flows into the anode side concentrating compartment C1.

In sub anion depletion chamber S2, Cl ^- anion components, etc., are adsorbed to the anion exchanger filled in the sub anion depletion chamber S2. In the cathode chamber E2, the reaction of generating hydrogen gas and OH ⁻ from water by the electrode reaction (2H ₂ O + 2e ⁻ → H ₂ + 2OH ⁻ ) proceeds continuously. The hydrogen gas rises in the cathode chamber E2 and is discharged out of the deionized water production apparatus 1 together with the electrode water. OH ⁻ flows into the secondary anion desalting chamber S2 through the third anion exchange membrane a3 and is exchanged with the anion component adsorbed on the anion exchanger, thereby regenerating the anion exchanger. The removed anion component such as Cl ⁻ is attracted to the anode 4 side by the potential between the anode 4 and the cathode 5, passes through the second anion exchange membrane a 2, and flows into the cathode side concentration chamber C 2. The treated water from which the anion component has been removed in the main anion demineralization chamber D2 and the subanion demineralization chamber S2 joins in the flow path L2 and is discharged out of the electric deionized water production apparatus 1.

  On the other hand, the decationized water that has flowed into the flow path L3 is supplied to the cathode chamber E2 as electrode water. The electrode water flowing out from the cathode chamber E2 flows into the anode chamber E1 through the flow path U3, the crossover pipe Y2, and the flow path L4, and passes through the flow path U4 located at the upper part of the electric deionized water production apparatus 1. And discharged to the outside of the electric deionized water production apparatus 1.

  Concentration chamber supply water (treated water) supplied to the concentration chambers C1 and C2 through the flow path U1 is a main cation demineralization chamber D1, a sub cation demineralization chamber S1, a main anion demineralization chamber D2, and a sub anion. The cation component and the anion component respectively discharged from the demineralization chamber S2 are taken in and discharged to the outside of the electric deionized water production apparatus 1 through the flow path L5 located at the lower part of the electric deionized water production apparatus 1. .

In this way, the water to be treated becomes decation water by removing the cation component in the main cation demineralization chamber D1 and the sub cation demineralization chamber S1, and the cation exchanger in the main cation demineralization chamber D1 is subjected to water dissociation reaction. Regenerated by the generated H ^+, the cation exchanger in the secondary cation desalting chamber S1 is regenerated by the H ⁺ generated in the anode chamber E1. Similarly, deionized water is deionized water by removing anion components in the main anion demineralization chamber D2 and the secondary anion demineralization chamber S2, and the anion exchanger in the main anion demineralization chamber D2 is generated by a water dissociation reaction. been OH ^- reproduced by an anion exchanger of the auxiliary anion depletion chamber S2, OH generated in the cathode chamber E2 ^- it is played by.

  In the configuration in which the decationized water that has flowed out of the cation demineralization chambers D1 and S1 flows into the anion demineralization chambers D2 and S2 as in this embodiment, the back of the outlet of the cation demineralization chambers D1 and S1. The pressure is higher than the back pressure at the outlet of the anion desalting chambers D2 and S2 by the pressure loss due to the anion desalting chambers D2 and S2. That is, the water pressure of the decationized water that has flowed out of the cation desalting chambers D1 and S1 is inevitably higher than the water pressure of the treated water that has flowed out of the anion desalting chambers D2 and S2. Therefore, such decationized water can be partly placed in the electrode chambers E1 and E2 only by changing the piping or by installing a very small auxiliary pump in front of the electric deionized water production apparatus. It becomes possible to make it flow. This means that when treated water is used as the electrode water, that is, by installing a pump with a large output at the front stage of the electric deionized water production apparatus and increasing the supply pressure of the treated water, Compared to the case where the water pressure is increased, there is no significant increase in cost.

In the decationized water, the cation component, particularly the hardness component, is removed by the main cation demineralization chamber D1 and the sub cation demineralization chamber S1. In addition to this, the decationized water takes in a large amount of H ⁺ instead of removing the cation component in the main cation demineralization chamber D1 and the sub cation demineralization chamber S1, and therefore its pH value is low. . By flowing such decationized water into the electrode chambers E1 and E2 as electrode water, it is possible to suppress the supply of hardness components to the cathode chamber E2 and the increase in pH value of the electrode water, particularly on the surface of the cathode E2. Can do. As a result, similarly to the case where treated water is used for the electrode water, it is possible to suppress the generation of scale in the cathode chamber E2, and to suppress the increase in operating voltage and the accompanying increase in power consumption.

  Scale generation is further suppressed by lowering the pH value of the decationized water flowing into the cathode chamber E2. Therefore, it is most preferable that the main cation desalting chamber D1 and the secondary cation desalting chamber S1 are filled with a cation exchanger in a single bed form.

  In the electric deionized water production apparatus 1 described above, hydrogen ions generated in the anode chamber E1 and hydroxide ions generated in the cathode chamber E2 are converted into ion exchangers in the secondary cation demineralization chamber S1 and the secondary anion demineralization chamber S2. It is effectively used for playback. As a result, the applied voltage between the anode and the cathode can be reduced, and the amount of power used can be reduced. In such a configuration, when water to be treated is used as electrode water, particularly in the anode chamber E1, not only hydrogen ions but also cation components contained in the electrode water move to the sub-cation demineralization chamber S1. Become. Therefore, the water to be treated flowing in the sub cation demineralization chamber S1 may be contaminated again by the cation component that has moved from the anode chamber E1 even though the cation component is removed there. Therefore, water that contains the cation component may flow out of the sub-cation demineralization chamber S1 where it should originally flow out of the sub-cation demineralization chamber S1 as decation water.

  In this embodiment, such a problem can be dealt with by using decationized water as electrode water. That is, since the decationized water supplied to the electrode chambers E1 and E2 contains almost no cation component, leakage of the cation component from the anode chamber E1 to the secondary cation demineralization chamber S1 can be suppressed. Thereby, it becomes possible to maintain the quality of decationized water satisfactorily by suppressing the cation component from being contained in the water (decationized water) flowing out of the secondary cation desalting chamber S1.

  When decationized water is used as the electrode water, the anion component is still contained in the electrode water flowing into the electrode chambers E1 and E2. Therefore, as in this embodiment, in the apparatus in which the cathode chamber E2 is adjacent to the secondary anion demineralization chamber S2 via the anion exchange membrane a3, the electrode water (decationized water) is combined with the hydroxide ions generated by the electrode reaction. The anion component contained in is also moved from the cathode chamber E2 to the secondary anion desalting chamber S2. Therefore, this anion component may not be removed in the secondary anion demineralization chamber S2 and may flow into the treated water and contaminate the treated water. In order to suppress this, an anion exchanger cartridge can be provided on the flow path L3 for supplying the electrode water to the cathode chamber E2. Thereby, the anion component in the electrode water supplied to the cathode chamber E2 can be reduced or removed, and leakage of the anion component from the cathode chamber E2 to the secondary anion demineralization chamber S2 can be suppressed.

  In addition, it is preferable to install a constant flow valve on the flow path L3 in order to secure a certain amount of electrode water. When the pressure loss in the electrode chambers E1 and E2 is large, a further auxiliary is provided on the flow path L3. A typical pump may be provided.

  Furthermore, since decationized water is acidic in liquidity as described above, it is effective to allow a part of the decationized water to flow not only into the electrode chamber but also into the concentration chamber. This suppresses the increase in the pH value of the concentrated water in the vicinity of the anion exchange membrane, and is mainly composed of calcium carbonate that can be generated in the concentration chamber (in the vicinity of the anion exchange membrane) when treated water having a high hardness component is treated. This is because the generation of scale as a component can be suppressed.

  In the present embodiment, the anode chamber E1 and the cathode chamber E2 are connected in series so that the electrode water flowing out from the cathode chamber E2 flows into the anode chamber E1, but the opposite may be possible. That is, in the anode chamber E1 and the cathode chamber E2, in order to suppress the above-described scale generation in the cathode chamber E2 and leakage of the cation component from the anode chamber E1 to the secondary cation desalting chamber S1, It is sufficient that the decationized water from which water is removed flows as electrode water. Therefore, for example, the decationized water may flow independently (for example, in parallel) into the anode chamber E1 and the cathode chamber E2.

  The present invention is greatly characterized in that a part of the decationized water that has flowed out of the cation desalting chambers D1 and S1 flows into the electrode chambers E1 and E2. Therefore, the present invention can be applied to various existing electric deionized water production apparatuses regardless of the arrangement pattern of the desalting chamber and the concentration chamber. FIG. 2 shows a configuration example of such an electrical deionized water production apparatus. In FIG. 2, the reference numerals of the respective chambers correspond to the reference numerals of the respective chambers in FIG. 1, and the reference sign X in the drawing means that the ends of the flow paths indicated by the reference sign X are connected to each other.

  In the embodiment shown in FIG. 1, the electric deionized water production apparatus of the present invention has been described by taking an example in which only one main demineralization chamber is provided. In order to respond, two or more main desalting chambers may be provided. In that case, the main desalting chamber and the concentrating chamber are alternately provided with the anion exchange membrane on the anode side and the cation exchange membrane on the cathode side sandwiched, and the concentrating chamber located on the most anode side is interposed via the cation exchange membrane. The concentrating chamber located adjacent to the secondary cation desalting chamber and closest to the cathode side is adjacent to the secondary anion desalting chamber via the anion exchange membrane. Further, the main desalting chamber is not necessarily provided, and only the sub-desalting chamber may be provided. That is, as shown in FIG. 2A, the cation desalting chamber D1 adjacent to the anode chamber E1 through the third cation exchange membrane c3 and the cathode chamber E2 through the third anion exchange membrane a3. Only one set with the anion desalting chamber D2 may be provided. In that case, the concentration chamber C is provided only between the cation desalting chamber D1 and the anion desalting chamber D2, and is adjacent to the second cation exchange membrane c2 on the cathode 5 side of the cation desalting chamber D1. It is adjacent to the second anion exchange membrane a2 on the anode 4 side of the anion desalting chamber D2.

  Further, when one or more main desalting chambers are provided, only one of the secondary cation desalting chamber and the secondary anion desalting chamber needs to be provided. Therefore, when the secondary cation desalting chamber is not provided, the most concentrated anode chamber is adjacent to the anode chamber through the cation exchange membrane, and when the secondary anion desalting chamber is not provided, the cathode is most The concentration chamber located on the side is adjacent to the cathode chamber through the anion exchange membrane. Alternatively, as shown in FIG. 2B, both the secondary cation desalting chamber and the secondary anion desalting chamber can be omitted. FIG. 2B shows a case where two main desalting chambers D are provided. In this case, the enrichment chamber C1 located closest to the anode 4 is adjacent to the anode chamber E1 via the ion exchange membrane m, which is either a cation exchange membrane or an anion exchange membrane, and is located closest to the cathode 5 side. Is adjacent to the cathode chamber E2 through the ion exchange membrane m. The main desalting chamber D and the concentrating chambers C1 to C3 are adjacent to each other with the anion exchange membrane a1 on the anode 4 side and the cation exchange membrane c1 on the cathode 5 side interposed therebetween, as described above.

  Further, from the embodiment shown in FIG. 1 in which one main desalting chamber is provided, the secondary cation desalting chamber S1, the secondary anion desalting chamber S2, and the pair of concentrating chambers C1, C2 are removed, and the anode chamber E1. A configuration in which the main anion desalting chamber D1 is adjacent to each other via the first cation exchange membrane a1, and the cathode chamber E2 and the main anion desalting chamber D2 are adjacent to each other via the second anion exchange membrane a2 is also possible. is there. In such a configuration shown in FIG. 2 (c), the anode chamber E1 and the cathode chamber E2 also serve as a concentration chamber, that is, the ionic components in the water to be treated removed in the main desalting chamber D are converted into the electrode chamber. It flows into E1 and E2 and is discharged outside by electrode water. Such a configuration can also be applied when two or more main desalting chambers are provided. That is, for example, in the embodiment shown in FIG. 2B, the concentration chambers C1 and C2 adjacent to the electrode chambers E1 and E2 are removed, the anode chamber E1 also serves as the concentration chamber C1, and the cathode chamber E2 serves as the concentration chamber C3. May be adopted.

(Example)
An electric deionized water production apparatus (Example) having the configuration shown in FIG. 1 and an electric deionized water production apparatus (Comparative Example) having the same configuration in each chamber as the embodiment shown in FIG. 1, 2) was used to confirm the effect of the present invention. Comparative Example 1 is different from the example shown in FIG. 1 in that the electrode chamber supply water is treated water that has circulated through the cation demineralization chamber and the anion desalination chamber. It is different in that it is treated water before flowing into the cation desalting chamber, that is, raw water. The flow rate of the electrode chamber supply water and the flow rate of the treated water obtained are the same in both the example and the comparative examples 1 and 2, but the example in which the decationized water that has flowed out of the cation demineralization chamber flows into the electrode chamber Then, compared with the comparative example 2, the flow volume of the to-be-processed water in a cation desalination chamber entrance is large only by the amount which flows into an electrode chamber. Similarly, in Comparative Example 1 in which the treated water that has flowed out of the anion desalting chamber flows into the electrode chamber, the flow rate of the water to be treated at the cation desalting chamber inlet is larger than that in Comparative Example 2 by the amount that flows into the electrode chamber. It has become. An anion exchange membrane is used as the intermediate ion exchange membrane.

  Actually, both the examples and comparative examples 1 and 2 were verified using an electric deionized water production apparatus provided with two main demineralization chambers.

The specifications of the electrical deionized water production apparatus, the water flow rate, the specifications of the feed water, etc. in the examples and comparative examples 1 and 2 are as follows. CER is an abbreviation for cation exchange resin, and AER is an anion exchange resin.
・ Anode chamber E1: dimension 300 × 80 × 4 mm CER filling ・ cathode chamber E2: dimension 300 × 80 × 4 mm AER filling ・ cation desalination chamber: dimension 300 × 80 × 8 mm (all three chambers) CER filling ・ anion desalination chamber : Dimensions 300 x 80 x 8 mm (both 3 chambers) AER filling / concentration chamber: 300 x 80 x 5 mm (both 3 chambers) AER filling / treated water flow rate: 150 L / h
・ Concentrated water flow: 30 L / h
-Electrode water flow rate: 10L / h
・ Cation desalination chamber supply water (treated water): One-stage RO permeated water 11 ± 1 μS / cm
・ Cation desalination chamber water hardness (CaCO ₃ content): 1 ± 0.1 mg / L
・ Concentration chamber supply water: 1 stage RO permeate 11 ± 1 μS / cm
-Electrode chamber supply water (Example): Cation demineralization chamber treated water (decation water)
(Comparative Example 1): Anion desalination chamber treated water (treated water)
(Comparative example 2): Cation demineralization chamber feed water (treated water)
-Applied current value: 1.4A
Applied current density: 0.58 A / dm ²

  About the apparatus of the Example and the comparative example 1, operation | movement for 2000 hours was performed and the pressure in each desalination chamber inlet and outlet was compared. The results are shown in Table 1.

  In the example, compared with Comparative Example 1, the total pressure is kept low, and the decationized water that has flowed out of the cation demineralization chamber is supplied to the electrode chamber at the minimum water pressure at which the treated water flows out of the anion demineralization chamber. It was confirmed that it was possible. On the other hand, the increase in pressure in Comparative Example 1 means that the pressure at the outlet of the anion desalting chamber must be increased in order to allow the treated water flowing out of the anion desalting chamber to flow into the electrode chamber. That is, in order to increase the pressure at the inlet of the cation desalting chamber (supply pressure of water to be treated), it means that an additional means that leads to an increase in cost is required.

  Similarly, Comparative Example 2 was also operated for 2000 hours, and the changes over time in the quality of treated water (treated water specific resistance) and operating voltage were compared with those of the Examples. The results are shown in Table 2.

  As shown in Table 2, it was confirmed that in the example, the operating voltage was suppressed lower than that in Comparative Example 2. This is considered to be an effect that scale generation at the cathode is suppressed by supplying decationized water from which the hardness component has been removed by flowing out from the cation desalting chamber to the electrode chamber. In fact, after about 2000 hours of operation, each device was disassembled, and it was confirmed that scale was generated at the cathode in the device of Comparative Example 2, but scale generation was confirmed in the device of the example. could not.

  Similarly, in the examples, it was confirmed that better treated water quality was obtained as compared with Comparative Example 2. This is considered to be an effect that the cationic component moves to the secondary cation demineralization chamber and contaminates decationized water flowing out of the secondary cation demineralization chamber.

DESCRIPTION OF SYMBOLS 1 Electric deionized water production apparatus 2 Frame 3 Intermediate ion exchange membrane 4 Anode 5 Cathode D Main demineralization chamber D1 Main cation demineralization chamber D2 Main anion demineralization chamber S1 Subcation demineralization chamber S2 Subanion demineralization chamber C , C1 to C3 Concentrating chamber C1 Cathode side concentrating chamber C2 Anode side concentrating chamber E1 Anode chamber E2 Cathode chamber a1 to a3 Anion exchange membrane c1 to c3 Cation exchange membrane

Claims (10)

An electrical deionized water production apparatus for producing deionized water by treating water to be treated,
An electrode chamber comprising an anode chamber with an anode and a cathode chamber with a cathode;
A cation desalting chamber located between the anode chamber and the cathode chamber, adjacent to the cation exchange membrane on the cathode chamber side, and filled with at least a cation exchanger;
An anion exchange membrane located between the anode chamber and the cathode chamber, adjacent to the anion exchange membrane on the anode chamber side, and having an anion exchanger filled with at least an anion exchanger;
The cation demineralization chamber and the anion demineralization chamber are a portion of intermediate treated water in which treated water flows into the cation demineralization chamber and flows out of the cation demineralization chamber to remove at least the cation component. Communicated to flow into the anion desalination chamber,
The cation desalting chamber and the electrode chamber are communicated so that another part of the intermediate treated water that has flowed out of the cation desalting chamber flows into the electrode chamber.
Electric deionized water production equipment.   Located between the anode chamber and the cathode chamber, on the cathode chamber side of the cation desalting chamber, adjacent to the cation desalting chamber via a cation exchange membrane, and the anode chamber of the anion desalting chamber The apparatus for producing electric deionized water according to claim 1, further comprising a concentration chamber adjacent to the cation demineralization chamber via an anion exchange membrane. The anion desalting chamber has a main anion desalting chamber, the cation desalting chamber has a main cation desalting chamber;
On the anode chamber side of the main anion demineralization chamber, an anode side concentration chamber located adjacent to the main anion demineralization chamber via a first anion exchange membrane, and the cathode side of the main cation demineralization chamber A cathode-side enrichment chamber located adjacent to the main cation desalting chamber via a first cation exchange membrane,
The electric deionized water production according to claim 1, wherein the main anion demineralization chamber is adjacent to the main cation demineralization chamber via an intermediate ion exchange membrane on the anode chamber side of the main cation demineralization chamber. apparatus.   The cation desalination chamber is located between the anode chamber and the anode side enrichment chamber, is adjacent to the anode side enrichment chamber via a second cation exchange membrane, and is disposed via a third cation exchange membrane. The electric deionized water production apparatus according to claim 3, further comprising a secondary cation demineralization chamber adjacent to the anode chamber and forming a parallel flow path with the main cation demineralization chamber.   The anion desalination chamber is located between the cathode chamber and the cathode side enrichment chamber, is adjacent to the cathode side enrichment chamber via a second anion exchange membrane, and is disposed via the third anion exchange membrane. The electric deionized water production apparatus according to claim 3, further comprising a secondary anion demineralization chamber adjacent to the cathode chamber and forming a parallel flow path with the main anion demineralization chamber.   The cation desalting chamber and the cathode chamber are adjacent to each other via a cation exchange membrane, the anion desalting chamber and the anode chamber are adjacent to each other via an anion exchange membrane, and the anion desalting chamber is The electric deionized water production apparatus according to claim 1, which is adjacent to the cation demineralization chamber via an intermediate ion exchange membrane on the anode chamber side of the cation demineralization chamber.   The electric deionized water production apparatus according to any one of claims 1 to 6, wherein the cation demineralization chamber is filled with the cation exchanger in a single-bed form.   The anode chamber and the cathode chamber are in communication with each other so that the other part of the intermediate treated water flows in series between the anode chamber and the cathode chamber. The electrical deionized water production apparatus according to the item.   The anode chamber and the cathode chamber are in communication with each other so that the other part of the intermediate treated water flows in parallel between the anode chamber and the cathode chamber. The electrical deionized water production apparatus according to the item. An electrode chamber comprising an anode chamber with an anode and a cathode chamber with a cathode;
A cation desalting chamber located between the anode chamber and the cathode chamber, adjacent to the cation exchange membrane on the cathode chamber side, and filled with at least a cation exchanger;
An anion desalination chamber located between the anode chamber and the cathode chamber, adjacent to the anion exchange membrane on the anode chamber side and filled with at least an anion exchanger;
A deionized water production method for producing deionized water by treating water to be treated using an electrical deionized water production apparatus having:
Flowing the water to be treated into the cation desalting chamber to produce intermediate treated water from which at least the cation component has been removed;
Flowing a portion of the intermediate treated water that has flowed out of the cation desalting chamber into the anion desalting chamber;
Flowing another part of the intermediate treated water that has flowed out of the cation desalting chamber to the electrode chamber;
A method for producing deionized water.

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