JP4960288B2 - Electric deionized water production apparatus and deionized water production method - Google Patents

Description

  The present invention relates to a technique for an electric deionized water production apparatus and a method for producing deionized water using the electric deionized water production apparatus.

  As a method for producing deionized water, a method of performing deionization by passing water to be treated through an ion exchange resin has been known. However, in this method, when the ion exchange resin is saturated with ions, regeneration is usually performed with a drug. Such regeneration treatment is disadvantageous in processing operation, and in order to eliminate such a point, a deionized water production method by an electric deionization method that does not require regeneration by a chemical agent has been established and has been put into practical use. .

  As an electric deionized water production apparatus (EDI) for performing such desalting treatment, for example, a cation exchange membrane and an anion exchange membrane are alternately arranged between an anode and a cathode, and between the two membranes. An example is one in which a desalting chamber filled with an anion exchanger and a concentration chamber are alternately formed (see, for example, Patent Document 1). In the electric deionized water production apparatus, the water to be treated is allowed to flow into the demineralization chamber filled with the ion exchanger and the concentrated water is allowed to flow into the concentration chamber while a direct current is passed between the anode and the cathode. As a result, ions in the water to be treated move into the concentrated water, and deionized water is obtained.

  For example, Patent Document 2 discloses a desalination chamber partitioned by an anion exchange membrane and a cation exchange membrane, and a concentration chamber partitioned by a cation exchange membrane and an anion exchange membrane and filled with an anion exchanger on the anion exchange membrane side. There is disclosed an electric deionized water production apparatus having: Here, when the hardness of the water to be treated flowing into the desalination chamber is high, for example, when tap water or water obtained by subjecting tap water to RO membrane treatment is used as the water to be treated, a hardness scale is formed on the anion exchange membrane surface of the concentration chamber. It tends to occur. However, as in the apparatus of Patent Document 2, when the concentration chamber is filled with an anion exchanger, the anion exchanger plays a role of mitigating the pH shift that occurs in the vicinity of the anion exchange membrane in the concentration chamber, and the anion in the concentration chamber It is possible to prevent the hardness scale from being generated on the exchange membrane surface.

JP 2001-170646 A JP 2004-358440 A JP 2007-283228 A

  On the other hand, various developments of an electrical deionized water production apparatus capable of reducing the electrical resistance of the electrical deionized water production apparatus and removing impurity ions in the water to be treated with power saving have been performed.

  Then, the objective of this invention provides the manufacturing method of the deionized water which uses the electrical deionized water manufacturing apparatus which can remove the impurity in to-be-processed water by power saving, and the said electrical deionized water manufacturing apparatus. It is in.

  The electric deionized water production apparatus of the present invention includes a cation exchange demineralization chamber that is partitioned by a pair of cation exchange membranes and is filled with a cation exchanger between an anode chamber having an anode and a cathode chamber having a cathode. An anion exchange demineralization chamber partitioned by a pair of anion exchange membranes and filled with an anion exchanger, and a cation of the cation exchange demineralization chamber between the cation exchange demineralization chamber and the anion exchange demineralization chamber A concentration chamber partitioned by an exchange membrane and an anion exchange membrane of the anion exchange desalting chamber and filled with an ion exchanger.

  Further, the electric deionized water production apparatus of the present invention comprises an anode / anode chamber / cation exchange membrane / cation exchange demineralization chamber filled with cation exchanger / cation exchange membrane / concentration chamber filled with ion exchanger / An anion exchange membrane / anion exchange desalting chamber filled with an anion exchanger / anion exchange membrane / cathode chamber / cathode are arranged in this order.

  In the electric deionized water production apparatus, the ion exchanger is preferably an anion exchanger, a cation exchanger, or a mixture of a cation exchanger and an anion exchanger.

  Further, in the electric deionized water production apparatus, water to be treated is passed through the cation exchange demineralization chamber in the order of the anion exchange demineralization chamber or the anion exchange demineralization chamber in the order of the cation exchange demineralization chamber. It is preferable to provide a desalting treatment line.

  The electric deionized water production apparatus preferably includes a desalting treatment line for passing water to be treated having an acidic pH from the anion exchange desalting chamber in the order of the cation exchange desalting chamber.

  The electric deionized water production apparatus preferably includes a desalting treatment line for passing water to be treated having an alkaline pH in the order of the cation exchange demineralization chamber to the anion exchange demineralization chamber.

  Moreover, in the said electrical deionized water manufacturing apparatus, it is preferable to have the concentrated water line which lets a to-be-processed water flow into the said concentration chamber separately from the said desalination processing line.

  In the electric deionized water production apparatus, a part of treated water obtained by subjecting treated water to desalination treatment in the cation exchange demineralization chamber and the anion exchange demineralization chamber is used as electrode water. It is preferable to have an electrode water line for passing water in the order of the anode chamber from the cathode chamber.

  In the electric deionized water production apparatus, a part of treated water obtained by subjecting treated water to desalination treatment in the cation exchange demineralization chamber and the anion exchange demineralization chamber is used as electrode water. It is preferable to have an electrode water line for passing water from the cathode chamber in the order of the anode chamber, and a concentrated water line for passing a part of the treated water to the concentration chamber.

  Further, in the electric deionized water production apparatus, a tank for storing treated water to be passed through the cation exchange demineralization chamber and the anion exchange demineralization chamber, and electrode water that has passed through the electrode water line are stored in the tank. It is preferable to have a circulation line to be supplied to.

  In the electric deionized water production apparatus, a part of treated water obtained by subjecting treated water to desalination treatment in the cation exchange demineralization chamber and the anion exchange demineralization chamber is used as electrode water. It is preferable to have an electrode water line for passing water from the cathode chamber in the order of the anode chamber, and a concentrated water line for passing electrode water that has passed through the electrode water line to the concentration chamber.

  Moreover, it is preferable that the said electrical deionized water manufacturing apparatus is a water treatment apparatus for fuel cells which desalinates the condensed water discharged | emitted from a fuel cell.

  Moreover, the manufacturing method of the deionized water of this invention uses the said electrical deionized water manufacturing apparatus, demineralizes the to-be-processed water, and manufactures deionized water.

  Moreover, it is a manufacturing method of the said deionized water, Comprising: It is preferable that the said to-be-processed water is the condensed water discharged | emitted from a fuel cell.

  According to the present invention, impurities in the for-treatment water can be removed with power saving.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

  FIG. 1 is a schematic configuration diagram of an electric deionized water production apparatus according to this embodiment. The electric deionized water production apparatus 1 shown in FIG. 1 includes an anode 10 / anode chamber 12 / cation exchange membrane 18 / cation exchange demineralization chamber 22 / cation exchange membrane 18 / ion exchanger 30 filled with a cation exchanger 20. Are arranged in the order of the concentration chamber 32 filled with the anion exchange membrane 24 / anion exchange desalting chamber 28 filled with the anion exchanger 26 / anion exchange membrane 24 / cathode chamber 16 / cathode 14.

  However, the electric deionized water production apparatus according to the present embodiment is partitioned by a pair of cation exchange membranes 18 between an anode chamber 12 having an anode 10 and a cathode chamber 16 having a cathode 14. An anion exchange demineralization chamber 28 which is partitioned by a filled cation exchange desalting chamber 22 and a pair of anion exchange membranes 24 and is filled with an anion exchanger 26, a cation exchange demineralization chamber 22 and an anion exchange desalination chamber 28. Between the cation exchange membrane 18 and the anion exchange membrane 24, and a concentrating chamber 32 filled with the ion exchanger 30, the configuration of the desalting chamber and the concentrating chamber is simply A cell may be a stack of a plurality of cells. In addition, when laminating | stacking, it is preferable that the ion exchange membrane which divides the adjacent cation exchange demineralization chamber 22 and the anion exchange demineralization chamber 28 is either one of the cation exchange membrane 18 or the anion exchange membrane 24.

  The electric deionized water production apparatus 1 in the present embodiment can sufficiently demineralize the water to be treated even with one single cell, rather than stacking a plurality of the single cells and using it as a water treatment apparatus for a large flow rate. It is preferable to use it as a water treatment device for a small flow rate. Examples of the water treatment device for small flow rate include a water treatment device for a fuel cell used for a household power source, a vehicle power source, and the like. A water treatment device for a fuel cell is used to remove impurities such as carbonic acid components and alkali metals contained in condensed water discharged from the fuel cell. The treated water from which impurities have been removed is used as humidifying water for the electrolyte membrane constituting the fuel cell. Hereinafter, in this embodiment, an electric deionized water production apparatus having one single cell as shown in FIG. 1 will be described as an example.

  In the electric deionized water production apparatus 1, the cation exchange demineralization chamber 22 partitioned by the pair of cation exchange membranes 18 is filled with the cation exchanger 20 and the anion exchange deionization partitioned by the pair of anion exchange membranes 24. The salt chamber 28 is filled with an anion exchanger 26.

  A concentration chamber 32 provided between the cation exchange desalting chamber 22 and the anion exchange desalting chamber 28 and partitioned by the cation exchange membrane 18 and the anion exchange membrane 24 is filled with an ion exchanger 30. The ion exchanger 30 filled in the concentration chamber 32 is an anion exchanger, a cation exchanger, a mixture of an anion exchanger and a cation exchanger, or the like, depending on the quality of the water to be treated. It is preferable to select as appropriate. For example, in the case of water to be treated containing almost no hardness component, it is not necessary to consider the generation of a hardness scale, so that a cation exchanger can be used for the ion exchanger 30 filled in the concentration chamber 32. Examples of water to be treated that contains almost no hardness component include condensed water discharged from a fuel cell. In general, a cation exchanger has higher conductivity than an anion exchanger. Therefore, it is possible to reduce the electric resistance of the concentration chamber 32 and to save power in the electric deionized water production apparatus 1 when the concentration chamber 32 is filled with the cation exchanger rather than the anion exchanger. Become. In general, since the cation exchanger has higher thermal stability than the anion exchanger, the heat resistance of the concentrating chamber 32 can be improved. On the other hand, when the water to be treated is, for example, tap water or water obtained by treating tap water with an RO membrane or the like, since the hardness component is usually included, the occurrence of a hardness scale can be suppressed. In view of the possibility, an anion exchanger is preferably used as the ion exchanger 30 filled in the concentration chamber 32. When the concentration chamber 32 is filled with an anion exchanger, the anion exchanger plays a role of mitigating the pH shift that occurs in the vicinity of the anion exchange membrane 24 in the concentration chamber 32, and the hardness of the anion exchange membrane 24 surface of the concentration chamber 32 is increased. Scale can be prevented from occurring.

  In addition, as an ion exchanger 30 filled in the concentration chamber 32, anion can be suppressed by suppressing the movement of free carbonic acid from the concentration chamber 32 to the cation exchange desalting chamber 22 and improving the quality of the treated water. It is preferable to use a mixture of an exchanger and a cation exchanger. By filling the concentration chamber 32 with the mixture, before the carbonate ions that have moved from the anion exchange desalting chamber 28 to the concentration chamber 32 move through the anion exchanger in the mixture and reach the cation exchange membrane 18, Free carbonic acid is released into concentrated water (treated water) by the action of hydrogen ions supplied from the cation exchanger in the mixture. For this reason, it is prevented that the free carbonic acid concentration in the vicinity of the cation exchange membrane 18 becomes high, and the influence on the treated water quality is mitigated.

  In the electric deionized water production apparatus 1, the anode chamber 12 formed between the anode 10 and the cation exchange demineralization chamber 22 is filled with a cation exchanger 20 as necessary. The cathode chamber 16 formed between the anion exchange desalting chamber 28 is filled with an anion exchanger 26 as necessary.

  It has also been found that the electrical resistance is high at the contact point between the cation exchanger and the anion exchanger. In the case of the electric deionized water production apparatus 1 of the present embodiment, the number of contact points between the cation exchanger and the anion exchanger is small even if the concentration chamber 32 is filled with either the cation exchanger or the anion exchanger. Therefore, an increase in electrical resistance can be suppressed and power saving of the device can be achieved.

  The electric deionized water production apparatus 1 has a demineralization treatment line for passing water to be treated in the order of the anion exchange demineralization chamber 28 to the cation exchange demineralization chamber 22. The desalination treatment line includes a first line 34, a second line 36, and a third line 38. The first line 34 is connected to the inlet of the anion exchange desalting chamber 28. The second line 36 is connected to the outlet of the anion exchange desalting chamber 28 and the inlet of the cation exchange desalting chamber 22. The third line 38 is connected to the outlet of the cation exchange desalting chamber 22.

  Moreover, the electric deionized water production apparatus 1 has a concentrated water line that allows the water to be treated to flow through the concentration chamber 32. The concentrated water line includes a concentrated water inflow line 40 and a concentrated water outflow line 42. The concentrated water inflow line 40 is connected to the inlet of the concentrating chamber 32, and the concentrated water outflow line 42 is connected to the outlet of the concentrating chamber 32. Moreover, the electric deionized water production apparatus 1 uses a part of treated water desalted in the anion exchange desalting chamber 28 and the cation exchange desalting chamber 22 as electrode water in the order of the cathode chamber 16 to the anode chamber 12. It has an electrode water line for water flow. The electrode water line includes an electrode water first line 44, an electrode water second line 46, and an electrode water third line 48. The electrode water first line 44 branches from the third line 38 of the desalination treatment line and is connected to the inlet of the cathode chamber 16, and the electrode water second line 46 is connected to the outlet of the cathode chamber 16 and the inlet of the anode chamber 12. The electrode water third line 48 is connected to the outlet of the anode chamber 12.

Similarly to the concentrated water line, the electrode water line may have a configuration in which the water to be treated is passed through the anode chamber 12 and the cathode chamber 16, but impurities such as anions and cations contained in the water to be treated are anodes. The cation exchange membrane 18 in the chamber 12 or the anion exchange membrane 24 in the cathode chamber 16 may permeate and move to the cation exchange desalting chamber 22 or the anion exchange desalting chamber 28 to deteriorate the quality of the treated water. Therefore, a part of the treated water from which impurities are removed flows as electrode water to the electrode water line and is passed through the anode chamber 12 and the cathode chamber 16 to move to the respective desalting chambers (22, 28). The amount of impurities can be reduced and the quality of treated water can be improved. In addition, the electrode water line may be configured such that a part of the treated water is passed as electrode water in the order of the anode chamber 12 to the cathode chamber 16, but H ₂ O ₂ is generated in the anode chamber 12. The H ₂ O ₂ generated in the anode chamber 12 may flow into the cathode chamber 16, and the anion exchanger 26 and the anion exchange membrane 24 filled in the cathode chamber 16 may be deteriorated. Therefore, the electrode water line is configured to pass a part of the treated water as electrode water in the order of the cathode chamber 16 to the anode chamber 12 so that H ₂ O ₂ generated in the anode chamber 12 does not flow to the cathode chamber 16. It is preferable that

  An example of an operation method in the case of producing deionized water by the electric deionized water production apparatus 1 according to this embodiment will be described below. First, water to be treated is caused to flow from the first line 34 and the concentrated water inflow line 40 of the desalination treatment line in a state where a direct current is passed between the anode 10 and the cathode 14. The water to be treated which has flowed from the first line 34 is supplied to the anion exchange desalting chamber 28, and when passing through the packed bed of the anion exchanger 26, the anions in the water to be treated are removed. Further, the water to be treated is discharged from the anion exchange desalting chamber 28, flows through the second line 36 of the desalting treatment line, and is supplied to the cation exchange desalting chamber 22. And when passing through the packed bed of the cation exchanger 20, cations in the water to be treated are removed, and treated water (deionized water) is obtained from the third line 38 of the desalting treatment line. Further, part of the treated water obtained flows as electrode water through the electrode water first line 44 and is supplied to the cathode chamber 16. The electrode water that has passed through the cathode chamber 16 flows through the electrode water second line 46 and is supplied to the anode chamber 12. Then, the electrode water that has passed through the anode chamber 12 is discharged from the electrode water third line 48. In addition, the water to be treated supplied from the concentrated water inflow line 40 to the concentration chamber 32 is a cation that moves from the cation exchange desalting chamber 22 through the cation exchange membrane 18, and an anion exchange membrane from the anion exchange desalting chamber 28. The anion moving through 24 is received and discharged from the concentrated water outflow line 42 as concentrated water in which impurities such as cations and anions are concentrated. By the above operation, treated water (deionized water) from which impurities in the for-treatment water are removed is obtained.

  The electric deionized water production apparatus 1 of the present embodiment is an apparatus that can efficiently perform a desalting treatment, particularly in water to be treated whose pH is acidic. That is, first, the water to be treated that exhibits acidity is passed through the anion exchange desalting chamber 28 filled with the anion exchanger 26 to remove the anion that is to be removed from the water to be treated. As a result, cations remain in the water to be treated, and hydroxide ions generated by water dissociation as these counter ions increase, and the pH of the water to be treated after the removal of anions becomes close to alkalinity. Accordingly, since the water to be treated supplied to the cation exchange desalting chamber 22 filled with the cation exchanger 20 is close to alkalinity, the number of hydrogen ions removed in the water to be treated is reduced. This makes it easier to remove the cation and improves the removal efficiency of impurities in the water to be treated.

  However, when the water to be treated exhibiting alkalinity is supplied to the anion exchange desalting chamber 28 filled with the anion exchanger 26, a large amount of hydroxide ions present in the water to be treated is captured by the anion exchanger 26, and the concentration chamber. Since it moves to 32, the anion which is a removal object cannot be removed efficiently. Then, even if the to-be-treated water in which the anion to be removed remains flows into the cation exchange desalting chamber 22 filled with the cation exchanger 20, the anion remaining in the to-be-treated water is not removed, and impurities in the treated water. The removal efficiency is reduced.

  For example, since the condensed water discharged from the fuel cell contains a large amount of carbonic acid components, the pH is acidic. Therefore, as described above, the fuel cell water treatment device that demineralizes the condensed water of the fuel cell to produce deionized water exchanges the water to be treated (condensed water) from the anion exchange demineralization chamber 28 with cation exchange. It is preferable that the apparatus is an electric deionized water production apparatus having a desalting treatment line for passing water in the order of the desalting chamber 22.

  In this embodiment, the flow of the water to be treated flowing into the anion exchange desalting chamber 28 is in the upward direction, and the flow of the water to be treated flowing into the cation exchange desalting chamber 22 is in the downward direction. It is not limited. Further, the flow of the water to be treated and the electrode water flowing in the electrode chamber (the anode chamber 12 and the cathode chamber 16) and the concentration chamber 32 is not particularly limited, but is preferably in the upward direction.

  Next, as another embodiment of the present invention, electric deionized water that allows the water to be treated to flow in the order from the cation exchange desalting chamber filled with the cation exchanger to the anion exchange desalting chamber filled with the anion exchanger. A manufacturing apparatus will be described.

  FIG. 2 is a schematic configuration diagram of an electric deionized water production apparatus according to another embodiment of the present invention. In the electric deionized water production apparatus 2 shown in FIG. 2, the same components as those in the electric deionized water production apparatus 1 shown in FIG.

  The electric deionized water production apparatus 2 has a demineralization treatment line for passing water to be treated in order from the cation exchange demineralization chamber 22 to the anion exchange demineralization chamber 28. The desalting treatment line includes a first line 50, a second line 52, and a third line 54. The first line 50 is connected to the inlet of the cation exchange desalting chamber 22. The second line 52 is connected to the outlet of the cation exchange desalting chamber 22 and the inlet of the anion exchange desalting chamber 28. The third line 54 is connected to the outlet of the anion exchange desalting chamber 28. Further, the desalination treatment in the concentrated water line (concentrated water inflow line 40, concentrated water outflow line 42) for passing the water to be treated to the concentrating chamber 32, the cation exchange desalting chamber 22 and the anion exchange desalting chamber 28. The configuration of the electrode water line (electrode water first line 44, electrode water second line 46, electrode water third line 48) through which a part of water is passed in the order of cathode chamber 16 to anode chamber 12 as electrode water is as follows: Since it is the same structure as the electric deionized water manufacturing apparatus 1 shown in FIG. 1, the description is omitted.

  An example of an operation method in the case of producing deionized water by the electric deionized water production apparatus 2 according to this embodiment will be described below. First, water to be treated is caused to flow from the first line 50 of the desalting treatment line and the concentrated water inflow line 40 in a state where a direct current is passed between the anode 10 and the cathode 14. The water to be treated that has flowed from the first line 50 is supplied to the cation exchange desalting chamber 22, and cations in the water to be treated are removed when passing through the packed bed of the cation exchanger 20. Further, the water to be treated is discharged from the cation exchange desalting chamber 22, flows through the second line 52 of the desalting treatment line, and is supplied to the anion exchange desalting chamber 28. And when passing through the packed bed of the anion exchanger 26, the anion in the water to be treated is removed, and treated water (deionized water) is obtained from the third line 54 of the desalting treatment line. Further, part of the treated water obtained flows as electrode water through the electrode water first line 44 and is supplied to the cathode chamber 16. The electrode water that has passed through the cathode chamber 16 flows through the electrode water second line 46 and is supplied to the anode chamber 12. Then, the electrode water that has passed through the anode chamber 12 is discharged from the electrode water third line 48. In addition, the water to be treated supplied from the concentrated water inflow line 40 to the concentration chamber 32 is a cation that moves from the cation exchange desalting chamber 22 through the cation exchange membrane 18, and an anion exchange membrane from the anion exchange desalting chamber 28. The anion which moves through 24 is received, and it flows out from the concentrated water outflow line 42 as concentrated water in which impurities such as cations and anions are concentrated. By the above operation, treated water (deionized water) from which impurities in the for-treatment water are removed is obtained.

  The electric deionized water production apparatus 2 of the present embodiment is an apparatus that can efficiently perform a desalting treatment particularly in water to be treated whose pH is alkaline. That is, first, the water to be treated that exhibits alkalinity is passed through the cation exchange desalting chamber 22 filled with the cation exchanger 20, and the cations to be removed from the water to be treated are removed. As a result, anions remain in the water to be treated, hydrogen ions generated by water dissociation as these counter ions increase, and the pH of the water to be treated after cation removal becomes acidic. Accordingly, since the water to be treated flowing into the anion exchange desalting chamber 28 filled with the anion exchanger 26 becomes closer to acidity, the amount of hydroxide ions removed in the water to be treated is reduced, and as a result, the object to be removed in the treated water. As a result, the removal efficiency of impurities in the water to be treated is improved.

  However, when the water to be treated that shows acidity is supplied to the cation exchange desalting chamber 22 filled with the cation exchanger 20, hydrogen ions present in a large amount in the water to be treated are captured by the cation exchanger 20 and are supplied to the concentration chamber 32. Since it moves, the cation which is a removal object cannot be removed efficiently. Then, even if the water to be treated in which cations to be removed remain flows into the anion exchange desalting chamber 28 filled with the anion exchanger 26, the cations remaining in the water to be treated are not removed, and impurities in the treated water. The removal efficiency is reduced.

  Moreover, the electric deionized water production apparatus of the present embodiment includes a demineralization treatment line shown in FIG. 1, a demineralization treatment line shown in FIG. 2, and a pH sensor, and depending on the pH of the water to be treated, You may select the desalination processing line which allows water to be treated to flow through.

FIG. 3 is a schematic configuration diagram of an electrical deionized water production apparatus according to a reference example . In the electrical deionized water production apparatus 3 shown in FIG. 3, the same components as those of the electrical deionized water production apparatus 1 shown in FIG.

  The electric deionized water production apparatus 3 includes a concentrated water line for passing a part of the treated water desalted in the cation exchange desalting chamber 22 and the anion exchange desalting chamber 28 to the concentrating chamber 32, and treated water. An electrode water line through which a part of the water is passed in the order from the cathode chamber 16 to the anode chamber 12 as electrode water. The concentrated water line includes a concentrated water inflow line 56 and a concentrated water outflow line 58. The concentrated water inflow line 56 branches from the third line 38 of the desalting treatment line and is connected to the inlet of the concentrating chamber 32, and the concentrated water outflow line 58 is connected to the outlet of the concentrating chamber 32. The electrode water line (electrode water first line 44, electrode water second line 46, and electrode water third line 48) has the same configuration as that of the electrical deionized water production apparatus 1 shown in FIG. Moreover, the structure of the said concentrated water line and an electrode water line is applicable also to the electrical deionized water manufacturing apparatus 2 shown in FIG. That is, the concentrated water inflow line 56 branches from the third line 54 of the desalting treatment line shown in FIG. 2 and is connected to the inlet of the concentrating chamber 32, and the concentrated water outflow line 58 is connected to the outlet of the concentrating chamber 32. .

  With the above configuration, part of the desalted treated water flows through the concentrated water inflow line 56, is supplied to the concentrating chamber 32, and is discharged from the concentrated water outflow line 58. A part of the desalted treated water is passed as electrode water in the order from the cathode chamber 16 to the anode chamber 12 as described above. When the water to be treated is supplied to the concentration chamber 32, cations and anions in the water to be treated are blocked by the cation exchange membrane 18 and the anion exchange membrane 24 in the concentration chamber 32 and move to the respective desalting chambers (22, 24). Never do. However, the free carbonic acid in the for-treatment water may pass through the cation exchange membrane 18 and move to the cation exchange desalting chamber 22 to deteriorate the quality of the treated water. Therefore, in this embodiment, a part of the treated water from which impurities such as free carbonic acid are removed is passed through the concentration chamber, thereby reducing the amount of free carbonic acid moving to the cation exchange desalting chamber 22, Water quality can be improved. Further, by passing the treated water through the electrode chambers (the anode chamber 12 and the cathode chamber 16), the amount of impurities such as cations and anions moving to the respective desalting chambers (22, 28) is reduced, and the treated water is reduced. Water quality can be improved.

FIG. 4 is a schematic configuration diagram of an electric deionized water production apparatus according to a reference example . In the electric deionized water production apparatus 4 shown in FIG. 4, the same components as those of the electric deionized water production apparatus 3 shown in FIG.

  The electric deionized water production apparatus 4 includes a tank 60 that stores water to be treated that passes through the cation exchange demineralization chamber 22 and the anion exchange demineralization chamber 28. The first line 34 of the desalination treatment line is connected to the outlet of the tank 60. The electric deionized water production apparatus 4 includes a circulation line 62 that supplies the electrode water that has passed through the electrode water line to the tank 60. The circulation line 62 is connected to the electrode water third line 48 and the electrode water inlet of the tank 60. The tank 60 also includes a supply port that can replenish water to be treated from outside the electric deionized water production apparatus 4. Moreover, the tank 60 and the circulation line 62 are applicable also to the electrical deionized water manufacturing apparatus shown in FIGS.

  With the above configuration, the water to be treated stored in the tank 60 passes through the desalting treatment lines (34, 36, 38) and is desalted by the desalting chambers (22, 28) to become treated water. A part of the treated water passes through the electrode water lines (44, 46, 48) and the electrode chambers (12, 16) as electrode water, flows into the circulation line 62, and is supplied to the tank 60. Since the impurity does not move from the desalting chambers (22, 28) to the electrode chambers (12, 16) unlike the concentration chamber 32, the electrode water contains almost no impurities. Therefore, even if the electrode water is returned to the tank 60 and subjected to desalting treatment as treated water again, the quality of the treated water obtained is not deteriorated. Furthermore, since the electrode water is circulated through the circulation line 62, the recovery rate of the finally obtained treated water can be improved.

FIG. 5 is a schematic configuration diagram of an electric deionized water production apparatus according to a reference example . In the electric deionized water production apparatus 5 shown in FIG. 5, the same components as those in the electric deionized water production apparatus 1 shown in FIG.

  The electric deionized water production apparatus 5 uses a part of the treated water demineralized in the cation exchange demineralization chamber 22 and the anion exchange demineralization chamber 28 as electrode water in order from the cathode chamber 16 to the anode chamber 12. And a concentrated water line for passing the electrode water that has passed through the electrode water line to the concentration chamber 32. The electrode water line includes an electrode water first line 44, an electrode water second line 46, and an electrode water third line 48, similarly to the electric deionized water production apparatus 1 shown in FIG. 1. The concentrated water line includes a concentrated water inflow line 64 and a concentrated water outflow line 66. The concentrated water inflow line 64 is connected to the third electrode water line 48 and the inlet of the concentrating chamber 32, and the concentrated water outflow line 66 is connected to the outlet of the concentrating chamber 32. Moreover, the structure of the said concentrated water line is applicable also to the electrical deionized water manufacturing apparatus 2 shown in FIG.

  With the above configuration, a part of the treated water desalted by each desalting chamber (22, 28) is first supplied as electrode water to the electrode water line (44, 46, 48) and the electrode chamber (12, 16). After passing, it flows into the concentrated water inflow line 64 as concentrated water. The concentrated water is supplied to the concentration chamber 32 through the concentrated water inflow line 64, passes through the concentration chamber 32, and is discharged from the concentrated water outflow line 66. When passing through the concentrating chamber 32, the impurities moved from the respective desalting chambers (22, 28) are received. In the electrode chamber (12, 16), since impurities do not move from the respective desalting chambers (22, 28) unlike the concentration chamber 32, the electrode water contains almost no impurities. That is, since the electrode water contains almost no free carbonic acid unlike the water to be treated, even if the electrode water is supplied to the concentration chamber 32, the amount of free carbonic acid that moves to the cation exchange desalting chamber 22 is small, Deterioration of the quality of treated water can be suppressed. Further, a part of the treated water desalted in each desalting chamber (22, 28) was supplied to the electrode chamber (12, 16) rather than to the concentrating chamber 32 and the electrode chamber (12, 16), respectively. Supplying the electrode water to the concentration chamber 32 is preferable from the viewpoint of effective use of the treated water, and can improve the recovery rate of the treated water and reduce the production cost.

  In an electrical desalting apparatus that performs a desalting process by passing a direct current between the anode 10 and the cathode 14, bubbles (oxygen gas, hydrogen gas) are generated from the anode 10 and the cathode 14. As described above, in the configuration in which the electrode water is passed from the electrode chamber (12, 16) to the concentration chamber 32, the bubbles in the electrode chamber (12, 16) are supplied to the concentration chamber 32 together with the electrode water. When bubbles are present in the concentration chamber 32 and adversely affect the desalting treatment of the water to be treated, it is preferable to install air vents or the like in the electrode water line, the concentrated water line or the like to remove the bubbles.

  In the present embodiment, the volumes of the cation exchange desalting chamber 22 and the anion exchange desalting chamber 28 are not particularly limited, but are designed in a range in which the water flow rate is 50 to 300 with respect to the flow rate of the water to be treated. Is preferred. If the double water flow rate is 300 or more, the removal efficiency of impurities in the water to be treated may decrease, and the quality of the treated water may deteriorate.

  In the present embodiment, the thickness of the concentrating chamber 32 is not particularly limited. However, if the linear flow rate in the concentrating chamber 32 is high, the water flow differential pressure increases, so the linear flow rate is designed to be 10 m / hr or less. It is preferable.

  Examples of ion exchangers used as the cation exchanger 20 and the anion exchanger 26 include ion exchange resins, ion exchange fibers, and monolithic organic porous anion exchangers (for example, those described in JP-A-2002-306976). And any substance having an ion exchange function, such as a mixture thereof, or a combination thereof.

  In the electric deionized water production apparatus, the flow rate, energization amount, and other operating conditions can be appropriately set according to the properties of the water to be treated. However, the flow rate of the concentrated water (treated water or treated water) flowing through the concentration chamber 32 is preferably set so that the concentration ratio with respect to the treated water is 20 times or less.

  The electric deionized water production apparatus of this embodiment is preferably used as a water treatment apparatus for small flow rates such as a water treatment apparatus for household fuel cells (flow rate: 5 L / h to 10 L / h). However, it is not necessarily limited to this.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

Example 1
Anode / anode chamber filled with cation exchange resin / cation exchange membrane / cation exchange desalting chamber filled with cation exchange resin / cation exchange membrane / concentration chamber filled with cation exchange resin / anion exchange membrane / anion exchange resin An anion-exchange demineralization chamber / anion exchange membrane / cathode chamber / cathode chamber filled with an anion-exchange resin were used, and the water to be treated was passed under the following conditions. The treated water specific resistance (MΩ · cm) and the operating voltage (V) were measured.
<Ion exchange resin used>
Cation exchange resin: IR120B-HG
Anion exchange resin: IRA402BL-HG
<Desalination room, concentration room size>
Size: length 40 mm x width 50 mm x thickness 15 mm (anion exchange desalting chamber, cation exchange desalting chamber and concentrating chamber have the above sizes)
<Anode plate and cathode plate>
Anode plate: A platinum plate formed on a titanium substrate was used as an anode plate.
Cathode plate: SUS316 was used as a cathode plate.
<Water flow order>
The water to be treated was passed in the order shown in FIG. That is, part of the water to be treated was passed in the order of anion exchange desalting chamber → cation exchange desalting chamber. A part of the water to be treated was also passed through the concentration chamber. A part of the treated water obtained from the desalting chamber was passed in the order of the cathode chamber → the anode chamber.
<Water flow conditions>
Processed water flow rate: 60mL / min
Concentrated water flow: 10 mL / min
Water conductivity to be treated: 6 μS / cm
Total carbonate concentration in water to be treated: 20 mg / L
Untreated water Na concentration: 600 μg / L
Water to be treated pH: 4.9
Operating time: 1000hr
<Current conditions>
Using a DC constant voltage constant current power supply, operation was carried out with a constant current of 0.25 A flowing.

(Reference example)
The treatment was performed under the same conditions as in Example 1 except that the water to be treated was passed in the order shown in FIG. That is, it was carried out under the same conditions as in Example 1 except that a part of the treated water obtained from the desalting chamber was passed through the concentration chamber and the electrode chamber (in order of the cathode chamber → the anode chamber).

(Example 3)
The treatment was performed under the same conditions as in Example 1 except that the water to be treated was passed in the order shown in FIG. That is, it was carried out under the same conditions as in Example 1 except that the flow of water to be treated was passed in the order of cation exchange demineralization chamber → anion exchange demineralization chamber.

(Comparative example)
The reaction was performed under the same conditions as in Example 1 except that the ion exchange resin filled in the cation exchange desalting chamber and the anion exchange desalting chamber was a mixture of IR120B-HG and IRA402BL-HG.

  The treated water specific resistivity (MΩ · cm) and the operating voltage (V) obtained from Examples 1 to 3 and Comparative Example after 1000 hours of operation were measured. The results are summarized in Table 1. Examples 1 to 3 were able to be operated at an operating voltage of 1/3 of the comparative example. This is because Examples 1 to 3 have a configuration in which there are few contacts between the cation exchanger and the anion exchanger, and thus an increase in electrical resistance could be suppressed. In Examples 1 and 2, the treated water specific resistance value equivalent to that of the comparative example was obtained. From this, it can be said that Examples 1 and 2 can be operated with low power consumption while maintaining the treatment efficiency of the water to be treated.

  In particular, the treated water specific resistivity of Example 2 was higher than that of Example 1. In the case of Example 2, the amount of free carbonic acid transferred from the concentration chamber to the desalting chamber through the cation exchange membrane can be suppressed by passing the treated water treated in the desalting chamber through the concentration chamber. This is because. In addition, the treated water specific resistivity of Examples 1 and 2 showed a higher value than that of Example 3 because acidic treated water was passed in the order of anion exchange demineralization chamber → cation exchange demineralization chamber. This is because the impurity removal efficiency is improved.

It is a schematic block diagram of the electrical deionized water manufacturing apparatus which concerns on this embodiment. It is a schematic block diagram of the electrical deionized water manufacturing apparatus which concerns on other embodiment of this invention. It is a schematic block diagram of the electrical deionized water manufacturing apparatus which concerns on a reference example . It is a schematic block diagram of the electrical deionized water manufacturing apparatus which concerns on a reference example . It is a schematic block diagram of the electrical deionized water manufacturing apparatus which concerns on a reference example .

Explanation of symbols

  1-5 Electric deionized water production apparatus, 10 anode, 12 anode chamber, 14 cathode, 16 cathode chamber, 18 cation exchange membrane, 20 cation exchanger, 22 cation exchange demineralization chamber, 24 anion exchange membrane, 26 anion exchange Body, 28 anion exchange desalting chamber, 30 ion exchanger, 32 concentration chamber, 34,50 first line, 36,52 second line, 38,54 third line, 40,56,64 concentrated water inflow line, 42 58, 66 Concentrated water outflow line, 44 electrode water first line, 46 electrode water second line, 48 electrode water third line, 48 electrode water third line, 60 tanks, 62 circulation line.

Claims (6)

Between an anode chamber with an anode and a cathode chamber with a cathode,
A cation exchange desalting chamber partitioned by a pair of cation exchange membranes and filled with a cation exchanger;
An anion exchange desalination chamber partitioned by a pair of anion exchange membranes and filled with an anion exchanger;
Between the cation exchange desalting chamber and the anion exchange desalting chamber, a cation exchange membrane in the cation exchange desalting chamber and an anion exchange membrane in the anion exchange desalting chamber are partitioned and filled with an ion exchanger. A demineralization treatment line for passing water to be treated in the order of the anion exchange demineralization chamber from the cation exchange demineralization chamber or the order of the cation exchange demineralization chamber from the anion exchange demineralization chamber; the separately from the desalination process lines, it possesses a concentrated water line that passed through the treated water into the concentrating compartment, a,
The ion exchanger is an anion exchanger, a cation exchanger, or a mixture of a cation exchanger and an anion exchanger,
The anode, the anode chamber, the cation exchange membrane, the cation exchange desalting chamber, the cation exchange membrane, the concentration chamber, the anion exchange membrane, the anion exchange desalting chamber, the anion exchange membrane, the cathode chamber, the electrodeionization water producing apparatus according to claim that you have been arranged in the order of the cathode. A claim 1 Symbol placement of the electrodeionization water producing apparatus, a part of the treated water obtained by the treatment water is desalted by the cation exchange desalting chamber and the anion exchange desalting compartment An electrode-type deionized water production apparatus having an electrode water line for passing water as electrode water in the order from the cathode chamber to the anode chamber. A second aspect Symbol placing the electrodeionization water producing apparatus, a tank for storing water to be treated is passed through the cation exchange desalting chamber and the anion exchange desalting compartment, passing through the electrode water line An electric deionized water production apparatus comprising a circulation line for supplying electrode water to the tank. The electric deionized water production apparatus according to any one of claims 1 to 3 is a water treatment apparatus for a fuel cell that demineralizes condensed water discharged from the fuel cell. Type deionized water production equipment. A method for producing deionized water, comprising using the electric deionized water production apparatus according to any one of claims 1 to 3 to demineralize the water to be treated to produce deionized water. . 6. The method for producing deionized water according to claim 5 , wherein the water to be treated is condensed water discharged from a fuel cell.

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