JP2011139980A - Electric deionized water producing apparatus and method of producing deionized water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric deionized water producing apparatus which can suppress an increase in operating voltage and deterioration of treated water quality by inhibiting generation of scales in concentrating chambers. <P>SOLUTION: The electric deionized water producing apparatus includes an anode 4 and a cathode 5, cation desalting chambers D1, D1' filled with at least a cation exchanger, anion desalting chambers D2, D2' filled with at least an anion exchanger, and concentrating chambers C1, C2 located between the anode 4 and the cathode 5 to be adjacent to the anion desalting chambers D2, D2' through first anion exchange membranes (a), a' respectively. The cation desalting chambers D1, D1' communicate with the anion desalting chambers D2, D2' so that a part of intermediate treated water, which flows out from the cation desalting chambers D1, D1' and from which at least cation components are removed, flows into the anion desalting chambers D2, D2'. The cation desalting chambers D1, D1' communicate with the concentrating chambers C1, C2 so that the other part of the intermediate treated water having flowed through the cation desalting chambers D1, D1'flows into the concentrating chambers C1, C2. <P>COPYRIGHT: (C)2011,JPO&INPIT

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.

  In the electric deionized water production apparatus described above, not only the anion component in the water to be treated, but also hydroxide ions generated by the water dissociation reaction are permeated through the anion exchange membrane from the desalting chamber and discharged into the concentration chamber. The For this reason, the liquidity of the concentrated water in the vicinity of the anion exchange membrane tends to be alkaline. On the other hand, when the water to be treated having a high hardness component is treated with the above-described electric deionized water production apparatus, the hardness component and the carbonic acid component in the water to be treated (general name for free carbonic acid, hydrogen carbonate ion, carbonate ion) in the concentration chamber. Are discharged and concentrated. As a result, in the vicinity of the anion exchange membrane in which the concentrated water is inclined to be alkaline (pH value is increased), a scale mainly composed of calcium carbonate may be generated. When the scale is generated, the electric resistance at that portion increases, and the operating voltage increases, thereby increasing the power consumption. Moreover, when the produced | generated scale adheres to the membrane surface of an ion exchange membrane, the ion component which should be discharged | emitted by a concentration chamber will not be discharged | emitted, and the water quality of treated water will fall.

  As one of the measures for suppressing the scale generation, Patent Document 1 discloses a method of filling an ion exchanger in a concentration chamber of an electric deionized water production apparatus and supplying water containing free carbonic acid to the concentration chamber. Has been. In this method, since the diffusion dilution of hydroxide ions into the concentration chamber is promoted, the increase in pH value in the vicinity of the anion exchange membrane is mitigated, thereby suppressing the generation of scale.

JP 2004-358440 A

  However, if the water to be treated contains a higher-concentration hardness component or if processing at a higher space velocity is performed, the concentration chamber is filled with an ion exchanger and water containing free carbonic acid is added. Supplying to the concentrating chamber is not sufficient and scale may still be generated. In such a case, the concentration of calcium carbonate in the concentrated water can be kept at a level that does not precipitate by increasing the flow rate of the concentration chamber supply water supplied to the concentration chamber and lowering the concentration rate of the concentrated water. It is done. However, this measure is also not preferable when the water to be treated is used as the concentration chamber supply water because more water is discharged as the concentrated water and the water recovery rate is reduced. Furthermore, it is possible to add an acidic solution such as hydrochloric acid to the concentration chamber supply water to suppress the increase in the pH value of the concentration water in the vicinity of the anion exchange membrane, but this leads to an increase in cost. This is contrary to the original advantage of the electric deionized water production apparatus that does not use chemicals.

  From the above, a measure based on a different idea from the past is desired for scale generation in the concentration chamber.

  Then, this invention provides the electrical deionized water manufacturing apparatus and the deionized water manufacturing method which can suppress the raise of an operating voltage and the fall of treated water quality by suppressing the production | generation of the scale in a concentration chamber. With the goal.

  In order to achieve the above-described object, an electrical deionized water production apparatus of the present invention is an electrical deionized water production apparatus for producing deionized water by treating water to be treated, comprising an anode and a cathode, A cation desalting chamber filled with at least a cation exchanger, an anion desalting chamber filled with at least an anion exchanger, and an anion desalting chamber located between an anode and a cathode via a first anion exchange membrane A cation demineralization chamber and an anion demineralization chamber in which water to be treated flows into the cation demineralization chamber and flows out of the cation demineralization chamber to remove at least the cation component. A part of the intermediate treated water is communicated so as to flow into the anion desalination chamber, and the cation desalting chamber and the concentrating chamber are the other part of the intermediate treated water that has flowed out of the cation desalting chamber into the concentrating chamber. It is connected so that it may flow in.

  The deionized water production method of the present invention includes an anode and a cathode, a cation demineralization chamber filled with at least a cation exchanger, an anion demineralization chamber filled with at least an anion exchanger, and an anode and a cathode. A deionized water is produced by treating the water to be treated using an electrical deionized water production apparatus located between and having an anion demineralization chamber and a concentrating chamber adjacent to each other via a first anion exchange membrane. A method for producing deionized water, the step of flowing treated water into a cation demineralization chamber to generate intermediate treated water from which at least a cation component has been removed, and a part of the intermediate treated water that has flowed out of the cation demineralization chamber And flowing the other part of the intermediate treated water that has flowed out of the cation desalting chamber into the concentrating chamber.

  In such an electric 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 is removed from the cation demineralization chamber. The treated intermediate water flows out. Since the intermediate treated water takes in hydrogen ions generated by the dissociation reaction of water in the cation desalting chamber, its liquidity becomes acidic. By causing a portion of this intermediate treated water to flow into the concentration chamber, it is possible to suppress an increase in the pH value of the concentrated water, particularly in the vicinity of the anion exchange membrane. Thereby, generation of scale in the concentration chamber can be suppressed, and an increase in operating voltage and a decrease in the quality of treated water can be suppressed.

  As described above, according to the present invention, an electric deionized water production apparatus and deionized water that can suppress an increase in operating voltage and a decrease in the quality of treated water by suppressing the generation of scale in the concentration chamber. A manufacturing method can be provided.

It is a schematic block diagram of the electrical deionized water manufacturing apparatus which concerns on the 1st Embodiment of this invention. It is a schematic block diagram of the electrical deionized water manufacturing apparatus which concerns on the 2nd Embodiment of this invention. It is a schematic block diagram which shows another structural example of the electric deionized water manufacturing apparatus which concerns on the 2nd Embodiment of this invention. It is a schematic block diagram of the electrical deionized water manufacturing apparatus which concerns on a comparative example.

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

(First embodiment)
FIG. 1 is a schematic configuration diagram of an electric deionized water production apparatus according to the first embodiment of the present invention. The electric deionized water production apparatus 1 includes three concentrating chambers C1 to C3 and first and second concentrating chambers C1 and C2 between an anode chamber E1 having an anode 4 and a cathode chamber E2 having a cathode 5. A first main desalting chamber D positioned between the second and third concentrating chambers C2 and C3, and a second main desalting chamber D ′ positioned between the second and third concentrating chambers C2 and C3. It is partitioned by ion exchange membranes a, a′c, c ′, m.

  The first main desalination chamber D includes a first cation desalination chamber D1 adjacent to the cation exchange membrane c on the cathode side, a first anion desalination chamber D2 adjacent to the anion exchange membrane a on the anode side, have. The second main desalting chamber D ′ includes a second cation desalting chamber D1 ′ adjacent to the cation exchange membrane c ′ on the cathode side and a second anion desalting adjacent to the anion exchange membrane a ′ on the anode side. And a chamber D2 ′. In each main desalting chamber D, D ', the cation desalting chambers D1, D1' and the anion desalting chambers D2, D2 'are adjacent to each other through the intermediate ion exchange membrane 3.

  The first and second main desalting chambers D and D ′ are on the anode side, through the anion exchange membranes (first anion exchange membranes) a and a ′, and the concentration chambers (anode side concentration chambers) C1, Adjacent to C2 and adjacent to the concentrating chambers (cathode-side concentrating chambers) C2 and C3 via cation exchange membranes (first cation exchange membranes) c and c ′ on the respective cathode sides. Therefore, the second concentration chamber C2 is a cathode-side concentration chamber for the first main desalting chamber D1, and an anode-side concentration chamber for the second main desalting chamber D '. In the electric deionized water production apparatus 1, the first concentration chamber C1 located closest to the anode side is adjacent to the anode chamber E1 through an ion exchange membrane m which is either a cation exchange membrane or an anion exchange membrane. In the electric deionized water production apparatus 1, the third concentrating chamber C3 located closest to the cathode side is adjacent to the cathode chamber E2 through the ion exchange membrane m.

The first cation desalting chamber D1 is filled with at least a cation exchanger to mainly remove cation components (Na ⁺ , Ca ²⁺ , Mg ^2+, etc.) in the water to be treated. 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 first cation desalting chamber D1, a single bed form of the cation exchanger can be mentioned. The second cation desalting chamber D1 ′ has the same configuration as that of the first cation desalting chamber D1.

The first anion desalination chamber D2 is filled with at least an anion exchanger and mainly contains anion components (Cl ⁻ , CO ₃ ²⁻ , HCO ₃ ⁻ , SiO _{2 in} silica to be treated (silica takes a special form). In many cases, 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 first anion desalting chamber D2 may be further filled with a cation exchanger. Examples of the filling form of the anion exchanger filled in the first 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 double bed form. The second anion desalting chamber D2 ′ has the same configuration as the first anion desalting chamber D2.

  The intermediate ion exchange membrane 3 takes into consideration the quality of water to be treated, the quality required for deionized water, the type of ion exchanger filled in the cation demineralization chambers D1, D1 ′ or the anion demineralization chambers D2, D2 ′, and the like. Can be selected. 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, each main desalting chamber D, D ′ is divided into two small desalting chambers, a cation desalting chamber D1, D1 ′ and an anion desalting chamber D2, D2 ′. , D ′ (concentration chamber 2 chamber configuration) adjacent to the concentration chamber is capable of multi-stage treatment of water to be treated, and is effective in improving deionization performance. Moreover, since there is no need to provide a concentration chamber between the cation desalting chambers D1, D1 ′ and the anion desalting chambers D2, D2 ′ of the main desalting chambers D, D ′, the applied voltage between the anode and the cathode is Therefore, the power consumption is reduced and the operation cost can be reduced.

  The first concentrating chamber C1 is provided for taking in the anion component discharged from the first anion desalting chamber D2 and the cation component discharged from the anode chamber E1, and releasing them out of the system. The second concentrating chamber C2 takes in the cation component discharged from the first cation desalting chamber D1 and the anion component discharged from the second anion desalting chamber D2 ′ and releases them out of the system. Is provided. The third concentrating chamber C3 is provided for taking in the cation component discharged from the second cation desalting chamber D1 'and the anion component discharged from the cathode chamber E2 and releasing them out of the system. A part of the decationized water (intermediate treated water) from which the cation component has been removed in the first and second cation demineralization chambers D1 and D1 'flows into the concentration chambers C1 to C3 as the concentration chamber supply water. Concentrated chamber supply water becomes concentrated water containing a cation component and an anion component, and is discharged from each of the concentration chambers C1 to C3. In order to suppress the electric resistance of the electric deionized water production apparatus 1, each of the concentrating chambers C1 to C3 may be filled with an ion exchanger.

The anode chamber E1 accommodates the anode 4. The anode 4 is made of a metal net or plate. When the water to be treated contains Cl ⁻ , 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.

  Electrode water flows into the electrode chambers (anode chamber and cathode chamber) E1, E2. In order to suppress the electric resistance of the electric deionized water production apparatus 1, it is preferable that the anode chamber E1 and the cathode chamber E2 are filled with an ion exchanger. 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.

  Each of the electrode chambers E1, E2, the first and second cation desalting chambers D1, D1 ′, the first and second anion desalting chambers D2, D2 ′, and the concentration chambers C1 to C3 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 U5 and L1 to L5 are provided for communication between rooms, supply and discharge of treated water, electrode water, and the like.

  One end of the flow path U1 located in the upper part of the electric deionized water production apparatus 1 is connected to the supply side of the water to be treated, and the other end side branches in the middle to form the first cation demineralization chamber D1 and the first cation demineralization chamber D1. 2 cation demineralization chamber D1 '. The flow path L1 located in the lower part of the electric deionized water production apparatus 1 is connected to the first cation demineralization chamber D1 and the second cation demineralization chamber D1 ′, and merges in the middle of the transition pipe Y. Connected to one end. The other end of the transition pipe Y 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 is branched in the middle to form the first anion demineralization chamber D2 and the second one. 2 anion desalination chamber D2 '. The flow path L2 located in the lower part of the electric deionized water production apparatus 1 is connected to the first anion demineralization chamber D2 and the second anion demineralization chamber D2 ′, and merges in the middle to discharge the treated water. Connected to the side.

  The flow path L3 located in the lower part of the electric deionized water production apparatus 1 is connected to the crossover pipe Y on one end side, and is branched in the middle on the other end side to be connected to the concentration chambers C1 to C3. That is, a part of the decationized water that has flowed out of the first and second cation demineralization chambers D1, D1 ′ is allowed to flow into the first and second anion demineralization chambers D2, D2 ′. A part is made to flow into each concentration chamber C1-C3. The flow path U3 located in the upper part of the electric deionized water production apparatus 1 is connected to each of the concentrating chambers C1 to C3, merges on the way, and is connected to the concentrated water outflow side.

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

  Flow paths L4 and U4 are connected to the anode chamber E1, and electrode water flows into the anode chamber E1 from the flow path L4 connected to the lower portion of the anode chamber E1, and is connected to the upper portion of the anode chamber E1. It is discharged from the anode chamber E1 through U4. Channels L5 and U5 are connected to the cathode chamber E2, and electrode water flows into the cathode chamber E2 from the channel L5 connected to the lower portion of the cathode chamber E2, and is connected to the upper portion of the cathode chamber E2. It is discharged from the cathode chamber E2 through U5.

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

  In advance, electrode water is supplied to the anode chamber E1 from the flow path L4 and discharged from the flow path U4. Similarly, electrode water is supplied to the cathode chamber E2 from the flow path L5 and discharged from the flow path U5. 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 to the first cation desalting chamber D1 and the second cation desalting chamber D1 '. The cation component is removed from the water to be treated in the first cation desalting chamber D1 and the second cation desalting chamber D1 '.

Specifically, the cation component such as Ca ²⁺ is exchanged between the first and second cation desalting chambers D1 and D1 ′ in the first and second cation desalting chambers D1 and D1 ′. Adsorbed to the body. In the main desalting chambers D and D ′, a reaction (water dissociation reaction) in which water is dissociated into hydrogen ions (hereinafter referred to as “H ⁺ ”) and hydroxide ions (hereinafter referred to as “OH ⁻ ”) continues. Is progressing. H ⁺ is exchanged with a cation component such as Ca ²⁺ adsorbed on the cation exchanger to regenerate the cation exchanger filled in the first and second cation desalting chambers D1 and D1 ′. The removed cation component such as Ca ²⁺ is attracted to the cathode 5 side by the potential difference between the anode 4 and the cathode 5, passes through the cation exchange membranes c and c ′, and enters the second and third concentration chambers C2 and C3. Inflow. In the first concentration chamber C1, the cation component contained in the electrode water flowing through the anode chamber E1 is drawn toward the cathode 5 due to the potential difference between the anode 4 and the cathode 5, and flows in through the ion exchange membrane m.

The water from which cation components such as Ca ²⁺ have been removed in this way (decationized water) merges in the flow path L1, and a part of the water flows into the flow path U2 through the transition pipe Y. Part flows into the flow path L3 from the crossover pipe Y.

  The decationized water that has flowed into the flow path U2 flows in parallel into the first anion desalination chamber D2 and the second anion desalination chamber D2 ′, and the first anion desalination chamber D2 and the second anion desalination chamber D2 ′. In chamber D2 ′, the anion component is removed.

Specifically, the anion component such as HCO ₃ ⁻ is anion exchange in the first and second anion desalting chambers D2 and D2 ′ and filled in the first and second anion desalting chambers D2 and D2 ′. Adsorbed to the body. In the main desalting chambers D and D ′, as described above, OH ⁻ is continuously generated by the water dissociation reaction. OH ⁻ is exchanged with an anion component such as HCO ₃ ⁻ adsorbed on the anion exchanger to regenerate the anion exchanger. The removed anion component such as HCO ₃ ⁻ is attracted to the anode 4 side by the potential difference between the anode 4 and the cathode 5, passes through the anion exchange membranes a and a ′, and enters the first and second concentration chambers C 1 and C 2. Inflow. In the third concentrating chamber C3, the anion component contained in the electrode water flowing through the cathode chamber E2 is attracted to the anode 4 side by the potential difference between the anode 4 and the cathode 5, and flows in through the ion exchange membrane m. The treated water from which the anion component has been removed in the first and second anion demineralization chambers D2 and D2 ′ 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 concentration chambers C1 to C3 as the concentration chamber supply water. In each of the concentration chambers C1 to C3, decationized water is discharged from the first and second cation demineralization chambers D1, D1 ′, the first and second anion demineralization chambers D2, D2 ′, and the electrode chambers. The cation component and the anion component are taken in, become concentrated water, and are discharged out of the electric deionized water production apparatus 1 through the flow path U3 located in the upper part of the electric deionized water production apparatus 1.

In this way, the water to be treated becomes decationized water by removing the cation component in the first and second cation demineralization chambers D1, D1 ′, and the first and second cation demineralization chambers D1, D1 ′. The cation exchanger is regenerated by H ⁺ produced by the water dissociation reaction. Similarly, the decationized water is deionized water by removing the anion component in the first and second anion demineralization chambers D2 and D2 ′, and the deionized water in the first and second anion demineralization chambers D2 and D2 ′. anion exchanger OH produced by the water dissociation reaction ^- are played by.

  In the present embodiment, as described above, a part of the decationized water that has flowed out of the first and second cation demineralization chambers D1 and D1 ′ flows into each of the concentration chambers C1 to C3. . The effects of this configuration will be described below by taking the second concentration chamber C2 as an example.

In the second concentrating chamber C2, it is generated from the second anion desalting chamber D2 ′ located on the cathode side through the anion exchange membrane a ′ together with the anion component removed from the water to be treated by a water dissociation reaction. OH ^-is also discharged. As a result, a large amount of OH ⁻ is present in the second concentration chamber C2, particularly in the vicinity of the anion exchange membrane a ′, and the pH value of the concentrated water increases. On the other hand, when the water to be treated having a high hardness component such as Ca ²⁺ is treated, the hardness component and the carbonic acid component in the water to be treated are discharged and concentrated in the second concentration chamber C2. Therefore, in the vicinity of the anion exchange membrane a ′ in which the concentrated water is inclined to be alkaline as described above, the discharged carbonic acid component exists mainly as carbonate ions (CO ₃ ²⁻ ). Is more likely to be generated. However, the intermediate treated water (decationized water) supplied to the second concentration chamber C2 contains a large amount of H ⁺ instead of removing the cation component in the first and second cation demineralization chambers D1 and D1 ′. Since it has taken in, the pH value is low. Therefore, by supplying the intermediate treated water that has passed through the cation desalting chamber and has become acidic to the second concentrating chamber C2, the pH value increases due to OH ⁻ discharged from the second anion desalting chamber D2 ′. And the generation of scale can be suppressed. In this way, it is possible to reduce an increase in the operating voltage of the electric deionized water production apparatus due to the generation of scale and a decrease in the quality of deionized water.

  Therefore, for example, even when a high-concentration hardness component is contained in the water to be treated, the pH is reliably lowered as compared with the method of supplying the permeated water of the reverse osmosis membrane directly to the concentration chamber as in Patent Document 1. Water can be supplied to the concentration chamber. As a result, an acidic solution such as hydrochloric acid is added to the concentration chamber supply water to suppress the pH increase in the concentration chamber, or the calcium carbonate concentration is kept below a certain concentration by increasing the flow rate of the concentration chamber supply water. This is unnecessary, and scale generation can be reliably suppressed.

  Scale generation is further suppressed by lowering the pH value of the decationized water flowing into the concentration chambers C1 to C3. Therefore, it is most preferable that the first and second cation desalting chambers D1 and D1 'are filled with a cation exchanger in a single bed form.

As can be seen from FIG. 1, in this embodiment, the inflow direction of the decationized water flowing into each of the concentration chambers C1 to C3 and the deionization flowing into the first and second anion demineralization chambers D2 and D2 ′. The inflow direction of the cationic water is opposite. This means that the inflow position of the decationized water in each of the concentration chambers C1 to C3 is adjacent to the discharge position of the decationized water in the first and second anion demineralization chambers D2 and D2 ′. To do. In each anion desalting chamber D2, D2 ′, the anion component contained in the decationized water is removed by the anion exchanger in each anion desalting chamber D2, D2 ′. , Less than the content in the vicinity of the inflow position. Therefore, conversely, OH ⁻ generated by the dissociation reaction of water and used for the regeneration of the anion exchanger is excessive in the vicinity of the discharge position of each anion desalting chamber D2, D2 ′ compared to the vicinity of the inflow position. Become. Therefore, an inflow position of each of the concentration chambers C1 to C3 into which acidic decationized water flows is provided adjacent to the discharge position of each of the anion desalination chambers D2 and D2 ′ where OH ⁻ is excessive. Thus, an increase in the pH value in each of the concentration chambers C1 to C3 can be suppressed more effectively. Thus, the inflow direction of the decation water flowing into each of the concentration chambers C1 to C3 is opposite to the inflow direction of the decation water flowing into the first and second anion demineralization chambers D2 and D2 ′. As a result, the effect of suppressing the scale generation described above becomes more prominent.

  In addition, the decationized water which flows into each concentration chamber C1-C3 is enough if the raise of the pH value of each concentration chamber C1-C3 can be suppressed to such an extent that the production | generation of a scale can be suppressed. Therefore, if the flow rate of the decationized water flowing into each of the concentration chambers C1 to C3 is in the range of 0.05 to 1 times the flow rate of the decationized water flowing into each of the anion demineralization chambers D2 and D2 ′. It is enough. Moreover, it is also possible to adjust the pH value by additionally supplying deionized water or the like as the concentration chamber supply water.

  In the present embodiment, the electric deionization production apparatus of the present invention is provided with two main demineralization chambers that are adjacent to each other via an intermediate ion exchange membrane and are composed of a cation demineralization chamber and an anion demineralization chamber. Although the case has been described as an example, only one main desalting chamber may be provided, or three or more main desalting chambers may be provided. Regardless of the number of main desalting chambers, the main desalting chambers and concentrating chambers are provided alternately, the concentrating chamber located closest to the anode side is adjacent to the anode chamber, and the concentrating chamber located closest to the cathode side Will be adjacent to the cathode chamber.

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

  In the electric deionized water production apparatus 1 shown in FIG. 2, the cation demineralization chamber D11 is located between the anode chamber E1 and the concentration chamber C and is adjacent to the concentration chamber C via the first cation exchange membrane c1. And located adjacent to the anode chamber via the second cation exchange membrane c2. An anion desalination chamber D12 is located between the cathode chamber E2 and the concentration chamber C, is adjacent to the concentration chamber via the first anion exchange membrane a1, and is connected to the cathode via the second anion exchange membrane a2. Located adjacent to chamber E2.

  In other words, the electric deionized water production apparatus 1 of the present embodiment removes the first concentration chamber C1 and the first anion demineralization chamber D2 from the first embodiment shown in FIG. The cation desalting chamber D1 and the anode chamber E1 are adjacent to each other through a cation exchange membrane, the third concentrating chamber C3 and the second cation desalting chamber D1 ′ are removed, and the second anion desalting chamber D2 ′ The cathode chamber E2 is adjacent to the cathode chamber E2 via the second anion exchange membrane a2. Therefore, the configuration of each chamber in this embodiment is the same as the configuration of each corresponding chamber in the first embodiment, and the flow of water to be treated (flow channel configuration) and the principle of deionization are also the first. This is the same as the embodiment. Further, the effect of suppressing the scale generation is the same as that of the first embodiment.

  On the other hand, in the present embodiment, hydrogen ions and hydroxide ions generated by the electrolysis reaction of water in the electrode chambers E1 and E2 are converted into the cation desalting chamber D11 and the anion desalting chamber adjacent to the electrode chambers E1 and E2, respectively. This is different from the first embodiment in that it is used for regeneration of the ion exchanger of D12. This will be briefly described below.

Hydrogen ions generated by the electrolysis reaction (2H ₂ O → O ₂ + 4H ⁺ + 4e ⁻ ) in the anode chamber E1 flow into the cation desalting chamber D11 through the second cation exchange membrane c2. In the cation desalting chamber D11, the cation component of the treated water that has flowed in is adsorbed by the cation exchanger, and the cation exchanger that has adsorbed the cation component is regenerated by the hydrogen ions that have moved from the anode chamber E1. On the other hand, hydroxide ions generated in the cathode chamber E2 by the same electrolysis reaction as in the anode chamber E1 move to the anion desalination chamber D12 through the second anion exchange membrane a2. In the anion desalting chamber D12, the anion component of the treated water that has flowed in is adsorbed by the anion exchanger, and the anion exchanger that has adsorbed the anion component is regenerated by the hydroxide ions that have moved from the cathode chamber E2.

  Thus, in the electric deionized water production apparatus 1 of the present embodiment, the hydrogen ions generated in the anode chamber E1 and the hydroxide ions generated in the cathode chamber E2 are ion exchangers in the demineralization chambers D11 and D12. 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.

  FIG. 3 is a schematic configuration diagram showing another configuration example of the electric deionized water production apparatus of the present embodiment. In FIG. 3, the reference numerals of the respective rooms correspond to the reference numerals of the respective rooms in FIG. The symbol X in the figure means that the ends of the flow path indicated by the symbol X are connected to each other.

  In the configuration example shown in FIG. 2, one unit configuration including three chambers of the anion demineralization chamber D12, the concentration chamber C, and the cation demineralization chamber D11 is provided. This unit configuration includes, for example, a large amount of water to be treated. For example, as shown in FIG. 3, it is possible to provide a plurality. In that case, each unit structure is adjacent to each other via an intermediate ion exchange membrane 3 having the same structure as that of the first embodiment. The cation desalting chamber D11 located on the most anode side is adjacent to the anode chamber E1 via the second cation exchange membrane c2, and the anion desalting chamber D12 located on the most cathode side is located on the second anion exchange membrane a2. Is adjacent to the cathode chamber E2. Moreover, all the cation demineralization chambers D11 form parallel flow paths so that the water to be treated flows in parallel, and the parallel flow paths so that the decationized water flows in parallel to all the anion demineralization chambers D12. Form. With such a configuration, it is possible to cope with an increase in the amount of water to be treated.

(Example)
The effect of the present invention was confirmed using the electric deionized water production apparatus (Example) having the configuration shown in FIG. 1 and the electric deionized water production apparatus (Comparative Example) shown in FIG. The comparative example is different from the embodiment shown in FIG. 1 in the configuration of each chamber, and is different in that the concentrated chamber supply water is treated water before flowing into the cation demineralization chamber, that is, raw water. The flow rate of the supply water of the concentrating chamber and the flow rate of the treated water obtained are the same in both the example and the comparative example, but in the example in which the decationized water that has flowed out of the cation demineralization chamber is flowed to the concentration chamber, the cation Compared with the comparative example, the flow rate of the water to be treated at the inlet of the desalination chamber is increased by the amount that flows into the concentration chamber. An anion exchange membrane is used as the intermediate ion exchange membrane, a cation exchange membrane is used as the ion exchange membrane between the anode chamber and the concentration chamber, and an anion exchange membrane is used as the ion exchange membrane between the cathode chamber and the concentration chamber. Each is used.

  In practice, both the examples and the comparative examples were verified using an electric deionized water production apparatus provided with three main demineralization chambers.

The specifications of the electric deionized water production apparatus, the water flow rate, the specifications of the feed water, etc. in the examples and comparative examples are as follows. CER is an abbreviation for cation exchange resin, and AER is an anion exchange resin.
・ Anode chamber E1: Dimensions 300 × 80 × 4 mm CER filling ・ Cathode chamber E2: Dimensions 300 × 80 × 4 mm AER filling ・ Cation desalting chamber: Dimensions 300 × 80 × 5 mm (all three chambers) CER filling : Dimensions 300 x 80 x 5 mm (both 3 chambers) AER filling / concentration chamber: 300 x 80 x 5 mm (both 4 chambers) AER filling and treated water flow rate: 100 L / h
・ Concentrated water flow: 10 L / h
-Electrode water flow rate: 15 L / 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 (Example): Cation demineralization chamber treated water (decation water)
(Comparative example): Cation demineralization chamber supply water (treated water)
・ Electrode chamber supply water: One-stage RO permeated water 11 ± 1 μS / cm
-Applied current value: 2.0A
Applied current density: 0.83 A / dm ²

  About the apparatus of the Example and the comparative example, the driving | running for 1000 hours was performed and the temporal change of the treated water quality (treated water specific resistance) and the operating voltage was compared. The results are shown in Table 1.

  In the examples, it was confirmed that a good treated water quality was obtained and the operating voltage was kept low compared to the comparative example. As shown in Table 1, this is considered to be the effect of suppressing the generation of scale by supplying decationized water having a low pH value after flowing out of the cation demineralization chamber to the concentration chamber. In fact, after about 1000 hours of operation, each device was disassembled, and it was confirmed that scale was generated in the concentration chamber in the device of Comparative Example 1, but in the device of Example 1, scale was generated. Could not be confirmed.

DESCRIPTION OF SYMBOLS 1 Electric deionized water manufacturing apparatus 2 Frame 3 Intermediate ion exchange membrane 4 Anode 5 Cathode D, D 'Main desalination chamber D1 1st cation desalination chamber D1' 2nd cation desalination chamber D11 Cation desalination chamber D2 First anion desalination chamber D2 ′ Second anion desalination chamber D12 Anion desalination chamber C Concentration chamber C1 to C3 First to third concentration chamber E1 Anode chamber E2 Cathode chamber a, a ′ Anion exchange membrane a1 1st anion exchange membrane a2 2nd anion exchange membrane c, c 'cation exchange membrane c1 1st cation exchange membrane c2 2nd cation exchange membrane

Claims (11)

An electrical deionized water production apparatus for producing deionized water by treating water to be treated,
An anode and a cathode;
A cation desalting chamber filled with at least a cation exchanger;
An anion desalting chamber filled with at least an anion exchanger;
A concentration chamber located between the anode and the cathode and adjacent to the anion desalting chamber via a first anion exchange membrane;
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 concentrating chamber are communicated so that another part of the intermediate treated water that has flowed out of the cation desalting chamber flows into the concentrating chamber.
Electric deionized water production equipment. The concentration chamber is located on the anode side of the anion demineralization chamber, adjacent to the anion demineralization chamber via the first anion exchange membrane, and the cation demineralization chamber A cathode side concentrating chamber located adjacent to the cation desalting chamber via a first cation exchange membrane on the cathode side;
The electric deionized water production apparatus according to claim 1, wherein the anion demineralization chamber is adjacent to the cation demineralization chamber via an intermediate ion exchange membrane on the anode side of the cation demineralization chamber.   The electric deionized water production apparatus according to claim 1, wherein the concentration chamber is adjacent to the cation demineralization chamber via a first cation exchange membrane on the cathode side of the cation demineralization chamber. An anode chamber provided with the anode, and a cathode chamber provided with the cathode,
The cation desalting chamber is adjacent to the anode chamber via a second cation exchange membrane, and the anion desalting chamber is adjacent to the cathode chamber via a second anion exchange membrane. The electric deionized water production apparatus as described. An anode chamber provided with the anode, and a cathode chamber provided with the cathode,
Two or more of the anion desalting chamber, the concentration chamber, and the cation desalting chamber are provided so as to be adjacent to each other via an intermediate ion exchange membrane,
Two or more anion desalination chambers form parallel flow paths, two or more of the cation desalination chambers form parallel flow paths,
The cation demineralization chamber located closest to the anode side is adjacent to the anode chamber via a second cation exchange membrane, and the anion desalination chamber located closest to the cathode side is the second anion exchange membrane. The electric deionized water production apparatus according to claim 3, wherein the apparatus is adjacent to the cathode chamber via a gap.   The electric deionized water production apparatus according to any one of claims 1 to 5, wherein the cation demineralization chamber is filled with the cation exchanger in a single-bed form.   The inflow direction of the other part of the intermediate treated water flowing into the concentrating chamber and the inflow direction of the part of the intermediate treated water flowing into the anion desalination chamber are opposite to each other. The electric deionized water production apparatus according to any one of 1 to 6.   The flow rate ratio of the other part of the intermediate treated water flowing into the concentrating chamber to the part of the intermediate treated water flowing into the anion desalting chamber is in a range of 0.05 to 1 times. Item 8. The electric deionized water production apparatus according to any one of Items 1 to 7. An anode and a cathode;
A cation desalting chamber filled with at least a cation exchanger;
An anion desalting chamber filled with at least an anion exchanger;
A concentration chamber located between the anode and the cathode and adjacent to the anion desalting chamber via a first anion exchange membrane;
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 concentrating chamber;
A method for producing deionized water.   The step of flowing into the concentrating chamber includes flowing the other part of the intermediate treated water into the concentrating chamber in a direction opposite to the direction of flowing the part of the intermediate treated water into the anion desalting chamber. The method for producing deionized water according to claim 9.   The step of flowing into the concentrating chamber has a flow rate in the range of 0.05 to 1 times the flow rate of the part of the intermediate treated water flowing into the anion desalting chamber, and the other part of the intermediate treated water. The electric deionized water production apparatus according to claim 9 or 10, comprising flowing water into the concentration chamber.

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