Softening device

Abstract

To provide a water softening device capable of regeneration of a weakly acidic cation-exchange resin with good efficiency by using an acidic electrolytic water produced in electrolysis.SOLUTION: A water softening device 1 is assembled with a water softening tank 3, a neutralization tank 4, an electrolytic tank 12, and a control part 30. The water softening tank 3 softens water by treating raw water containing hard components by using a weakly acidic cation-exchange resin 10. The neutralization tank 4 neutralizes pH of the soft water distributed from the water softening tank 3 by using a weakly basic anion-exchange resin 11. The electrolytic tank 12 produces an acidic electrolytic water for regenerating the weakly acidic cation-exchange resin 10 of the water softening tank 3 and an alkaline electrolytic water for regenerating the weakly basic anion-exchange resin 11 of the neutralization tank 4. The control part 30 determines termination of the regeneration of the weakly acidic cation-exchange resin 10 of the water softening tank 3 and the weakly basic anion-exchange resin 11 of the neutralization tank 4 based on an ion concentration information of a first ion concentration of the acidic electrolytic water before introducing to the water softening tank 3 and a second ion concentration of the acidic electrolytic water after distributed from the water softening tank 3.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a water softening device for obtaining domestic water.

Background Art

[0002] In a conventional water softening device using a weakly acidic cation exchange resin, as a method for regenerating the cation exchange resin without using salt, a method of regenerating the cation exchange resin with acidic electrolyzed water generated by electrolysis is known (for example, see Patent Document 1). The weakly acidic cation exchange resin has a proton at the end of the functional group, and since it softens raw water by exchanging calcium ions or magnesium ions contained in the raw water with hydrogen ions, automatic regeneration of the weakly acidic cation exchange resin with acidic electrolyzed water becomes possible.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The required amount of acidic electrolyzed water used for regenerating the weakly acidic cation exchange resin basically is proportional to the amount of soft water used and the hardness of the raw water. However, the hardness of the raw water varies greatly depending on the region, and it is difficult to accurately detect the hardness of the raw water by electronic devices. For this reason, by uniformly setting the required amount of acidic electrolyzed water according to high-hardness regions, it is possible to handle any region, but in some regions where the water softening device is used, regeneration with acidic electrolyzed water is performed more than necessary, and there is a problem that the electrodes for electrolysis for generating acidic electrolyzed water are excessively consumed.

[0005] Therefore, the present invention aims to solve the above-mentioned conventional problems and provide a water softening device capable of efficiently regenerating a weakly acidic cation exchange resin with acidic electrolyzed water generated by electrolysis.

Means for Solving the Problems

[0006] To achieve this object, the water softening device according to the present invention includes a water softening tank, a neutralization tank, an electrolysis tank, a treatment tank, and a control unit. The water softening tank softens raw water containing hardness components with a weakly acidic cation exchange resin. The neutralization tank neutralizes the pH of the softened water flowing through the water softening tank with a weakly basic anion exchange resin. The electrolysis tank generates acidic electrolyzed water for regenerating the weakly acidic cation exchange resin in the water softening tank and alkaline electrolyzed water for regenerating the weakly basic anion exchange resin in the neutralization tank. The treatment tank mixes the acidic electrolyzed water flowing through the water softening tank and the alkaline electrolyzed water flowing through the neutralization tank and supplies the mixture to the electrolysis tank. The filtration unit removes reaction products generated by mixing acidic electrolyzed water and alkaline electrolyzed water. The control unit acquires ion concentration information regarding the first ion concentration of the acidic electrolyzed water before being introduced from the electrolysis tank into the water softening tank and the second ion concentration of the acidic electrolyzed water after flowing through the water softening tank, and controls the regeneration treatment of the weakly acidic cation exchange resin in the water softening tank and the weakly basic anion exchange resin in the neutralization tank. Then, the control unit determines the end of the regeneration treatment based on the ion concentration information, thereby achieving the intended purpose.

Effects of the Invention

[0007] According to the present invention, it is possible to provide a water softening device capable of efficiently regenerating a weakly acidic cation exchange resin with acidic electrolyzed water generated by electrolysis.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Best Mode for Carrying Out the Invention

[0009] The water softening device according to the present invention includes a water softening tank, a neutralization tank, an electrolysis tank, a treatment tank, and a control unit. The water softening tank softens raw water containing hardness components with a weakly acidic cation exchange resin. The neutralization tank neutralizes the pH of the softened water flowing through the water softening tank with a weakly basic anion exchange resin. The electrolysis tank generates acidic electrolyzed water for regenerating the weakly acidic cation exchange resin in the water softening tank and alkaline electrolyzed water for regenerating the weakly basic anion exchange resin in the neutralization tank. The treatment tank mixes the acidic electrolyzed water flowing through the water softening tank and the alkaline electrolyzed water flowing through the neutralization tank and supplies the mixture to the electrolysis tank. The control unit acquires ion concentration information regarding the first ion concentration of the acidic electrolyzed water before being introduced from the electrolysis tank into the water softening tank and the second ion concentration of the acidic electrolyzed water after flowing through the water softening tank, and controls the regeneration treatment of the weakly acidic cation exchange resin in the water softening tank and the weakly basic anion exchange resin in the neutralization tank. Then, the control unit determines the end of the regeneration treatment based on the ion concentration information.

[0010] According to such a configuration, the regeneration treatment can be terminated at the timing when the regeneration of the weakly acidic cation exchange resin in the water softening tank is completed. Thereby, since the regeneration treatment can be performed with an appropriate amount of acidic electrolyzed water, it is possible to suppress excessive consumption of the electrodes for electrolysis for generating acidic electrolyzed water, and the performance of the regeneration treatment can be maintained over a long period. That is, it is possible to provide a water softening device capable of efficiently regenerating the weakly acidic cation exchange resin with the acidic electrolyzed water generated by electrolysis.

[0011] Further, in the water softening device according to the present invention, the control unit may determine the end of the regeneration treatment when the difference between the first ion concentration and the second ion concentration is equal to or less than a reference value, and determine the continuation of the regeneration treatment when the difference between the first ion concentration and the second ion concentration exceeds the reference value. Thereby, it becomes possible to accurately control the end of the regeneration treatment of the weakly acidic cation exchange resin with acidic electrolyzed water.

[0012] Further, in the water softening device according to the present invention, the first ion concentration may be the first pH value of the acidic electrolyzed water before being introduced from the electrolytic cell into the water softening tank, and the second ion concentration may be the second pH value of the acidic electrolyzed water after flowing through the water softening tank. Thereby, based on the hydrogen ion concentration (pH value) before and after water softening, the completion of the regeneration of the weakly acidic cation exchange resin is determined, so that the timing of the completion of the regeneration can be detected more accurately. Then, since the regeneration treatment can be performed with a more appropriate amount of acidic electrolyzed water, it is possible to suppress excessive consumption of the electrodes for electrolysis for generating acidic electrolyzed water, and the performance of the regeneration treatment can be maintained over a long period. That is, it is possible to provide a water softening device capable of more efficiently regenerating the weakly acidic cation exchange resin with the acidic electrolyzed water generated by electrolysis.

[0013] Further, in the water softening device according to the present invention, there are provided a first supply passage for drawing out acidic electrolyzed water from the electrolytic cell and supplying it to the upstream side of the water softening tank, a second supply passage for drawing out alkaline electrolyzed water from the electrolytic cell and supplying it to the upstream side of the neutralization tank, a first recovery passage capable of connecting the upstream side of the treatment tank to the downstream side of the water softening tank, a second recovery passage capable of connecting the upstream side of the treatment tank to the downstream side of the neutralization tank, a first pH detection unit provided in the first supply passage for detecting the first pH value of the acidic electrolyzed water flowing through the first supply passage, and a second pH detection unit provided in the first recovery passage for detecting the second pH value of the acidic electrolyzed water flowing through the first recovery passage. Further, during the water softening treatment, by switching the on-off valve, the raw water supplied from the outside is made to flow through the water softening tank and the neutralization tank in this order and discharged. Further, during the regeneration treatment, by switching the on-off valve, the water in the treatment tank is supplied from the electrolytic cell to the water softening tank through the first supply passage, the water that has flowed through the water softening tank is recovered from the water softening tank to the treatment tank through the first recovery passage, the water in the treatment tank is supplied from the electrolytic cell to the neutralization tank through the second supply passage, and the water that has flowed through the neutralization tank is recovered from the neutralization tank to the treatment tank through the second recovery passage. Then, the control unit terminates the regeneration treatment and resumes the water softening treatment by switching the on-off valve based on the pH information from the first pH detection unit and the second pH detection unit. Thereby, by switching the on-off valve based on the pH information, the switching from the regeneration treatment to the water softening treatment becomes easy.

[0014] Further, in the water softening device according to the present invention, the first ion concentration may be the first TDS value of the acidic electrolyzed water before being introduced from the electrolytic cell into the water softening tank, and the second ion concentration may be the second TDS value of the acidic electrolyzed water after flowing through the water softening tank. Thereby, based on the TDS values before and after water softening, the completion of the regeneration of the weakly acidic cation exchange resin can be determined, and the timing of the completion of the regeneration can be detected more accurately. Then, since the regeneration treatment can be performed with an appropriate amount of acidic electrolyzed water, it is possible to suppress excessive consumption of the electrodes for electrolysis for generating acidic electrolyzed water, and the performance of the regeneration treatment can be maintained over a long period. That is, it is possible to provide a water softening device capable of more efficiently regenerating the weakly acidic cation exchange resin with the acidic electrolyzed water generated by electrolysis.

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the following embodiments are examples of embodying the present invention and do not limit the technical scope of the present invention. Also, each drawing described in the embodiments is a schematic diagram, and the ratio of the size and thickness of each component in each drawing does not necessarily reflect the actual dimensional ratio.

[0016] (Embodiment 1) With reference to FIG. 1, the water softening device 1 according to Embodiment 1 of the present invention will be described. FIG. 1 is a conceptual diagram showing the water softening device 1 according to Embodiment 1 of the present invention. Note that in FIG. 1, each element of the water softening device 1 is conceptually shown.

[0017] The water softening device 1 is a device that generates the municipally supplied water (raw water containing hardness components) supplied from the outside as neutral softened water that can be used as domestic water.

[0018] Specifically, as shown in FIG. 1, the softening device 1 includes an inlet 2 for raw water from the outside, a softening tank 3, a neutralization tank 4, a water intake 5 for the treated soft water, and a regeneration device 6. Further, the regeneration device 6 includes an electrolytic cell 12, a treatment tank 14, a water supply pump 15, and a filtration unit 32 as a separation tank. Also, the softening device 1 includes a plurality of on-off valves (on-off valves 21 to 27, on-off valve 33, on-off valve 34), a first pH detection unit 28, a second pH detection unit 29, and a control unit 30.

[0019] The inlet 2 is connected to the municipal water. The softening device 1 can take out the water after softening treatment from the water intake 5 by the pressure of the municipal water.

[0020] From the inlet 2 to the water intake 5, they are connected by a flow path 7, a flow path 8, and a flow path 9. The flow path 7 is a flow path connecting the inlet 2 to the softening tank 3. The flow path 8 is a flow path connecting the softening tank 3 and the neutralization tank 4. The flow path 9 is a flow path connecting from the neutralization tank 4 to the water intake 5.

[0021] In other words, the flow path 7 is a flow path for guiding the raw water containing hardness components from the inlet 2 to the softening tank 3. Also, the flow path 8 is a flow path for guiding the raw water softened in the softening tank 3 to the neutralization tank 4. The flow path 9 is a flow path for guiding the neutralized soft water to the water intake 5.

[0022] That is, in the softening device 1, in the softening treatment, the municipal water supplied from the outside flows in the order of the inlet 2, the flow path 7, the softening tank 3, the flow path 8, the neutralization tank 4, the flow path 9, and the water intake 5, and is discharged as neutral soft water.

[0023] The softening tank 3 is filled with a weakly acidic cation exchange resin 10, and the neutralization tank 4 is filled with a weakly basic anion exchange resin 11.

[0024] Here, there are no particular restrictions on the weakly acidic cation exchange resin 10, and general-purpose ones can be used. For example, those having a carboxyl group (-COOH) as an exchange group can be mentioned. Also, those in which the hydrogen ion (H+), which is the counter ion of the carboxyl group, is a cation such as a metal ion or an ammonium ion (NH4+) may be used.

[0025] Also, there are no particular restrictions on the weakly basic anion exchange resin 11, and general-purpose ones can be used. For example, those in the free base form can be mentioned.

[0026] The water softening tank 3 softens the raw water containing hardness components by the action of the weakly acidic cation exchange resin 10. More specifically, the water softening tank 3 is provided with a weakly acidic cation exchange resin 10 having a hydrogen ion at the terminal of the functional group, and exchanges the cations (calcium ions, magnesium ions), which are the hardness components contained in the flowing water (raw water), with hydrogen ions, so that the hardness of the raw water is reduced and the raw water can be softened. Also, since the terminal of the functional group of the weakly acidic cation exchange resin 10 is a hydrogen ion, in the regeneration treatment described later, the weakly acidic cation exchange resin 10 can be regenerated using acidic electrolyzed water.

[0027] Raw water containing hardness components is passed through the water softening tank 3 from the flow path 7, and is passed through the weakly acidic cation exchange resin 10 filled inside, and then passed as softened water from the flow path 8 to the neutralization tank 4. However, the softened water treated with the weakly acidic cation exchange resin 10 contains a large amount of hydrogen ions that have come out after being exchanged with the hardness components.

[0028] The neutralization tank 4 converts the softened water (acidified softened water) containing hydrogen ions coming out of the softening tank 3 into neutral water (neutral softened water) by the action of the weakly basic anion exchange resin 11. More specifically, the neutralization tank 4 is equipped with the weakly basic anion exchange resin 11, and adsorbs the hydrogen ions contained in the softened water from the softening tank 3 together with anions (negative ions), so that the pH of the softened water rises and neutral softened water can be obtained. Also, the weakly basic anion exchange resin 11 can be regenerated using alkaline electrolyzed water in the regeneration process described later.

[0029] In the neutralization tank 4, the softened water containing hydrogen ions is passed through the flow path 8 and passes through the weakly basic anion exchange resin 11 filled inside, so that the acidified softened water coming out of the softening tank 3 is neutralized and passed out to the outside through the flow path 9 as neutral softened water.

[0030] The regeneration device 6 is a device that regenerates the weakly acidic cation exchange resin 10 of the softening tank 3 and the weakly basic anion exchange resin 11 of the neutralization tank 4. Specifically, as described above, the regeneration device 6 includes an electrolytic cell 12, a treatment tank 14, a water supply pump 15, and a filtration unit 32. And the regeneration device 6 is connected to the flow paths 7, 8, and 9 from the inlet 2 to the water intake 5 by a first supply flow path 17, a first recovery flow path 18, a second supply flow path 19, and a second recovery flow path 20 respectively, and constitutes a circulation flow path 16 (a first circulation flow path 16a and a second circulation flow path 16b) described later.

[0031] Here, the first supply flow path 17 is a flow path for supplying acidic electrolyzed water from the electrolytic cell 12 to the softening tank 3, and the first recovery flow path 18 is a flow path for recovering the acidic electrolyzed water containing hardness components that has passed through the softening tank 3 to the treatment tank 14. Also, the second supply flow path 19 is a flow path for supplying alkaline electrolyzed water from the electrolytic cell 12 to the neutralization tank 4, and the second recovery flow path 20 is a flow path for recovering the alkaline electrolyzed water that has passed through the neutralization tank 4 to the treatment tank 14.

[0032] The electrolytic cell 12 uses the electrodes 13 provided inside to electrolyze the incoming water (the water supplied from the treatment tank 14), thereby generating and discharging acidic electrolyzed water and alkaline electrolyzed water. Then, the electrolytic cell 12 supplies the acidic electrolyzed water to the softening tank 3 and the alkaline electrolyzed water to the neutralization tank 4. Although details will be described later, the acidic electrolyzed water generated by the electrolytic cell 12 is used for the regeneration of the weakly acidic cation exchange resin 10 in the softening tank 3, and the alkaline electrolyzed water generated by the electrolytic cell 12 is used for the regeneration of the weakly basic anion exchange resin 11 in the neutralization tank 4. Note that the electrolytic cell 12 is configured to be able to control the energization state of the electrodes 13 by a control unit 30 described later.

[0033] The treatment tank 14 is a tank or container equipped with an air vent valve 35. The treatment tank 14 can secure and store the water that circulates in the circulation channel 16 (see Figure 2) when regenerating the weakly acidic cation exchange resin 10 and the weakly basic anion exchange resin 11. Further, the treatment tank 14 mixes the acidic electrolyzed water containing hardness components that has flowed through the softening tank 3 and the alkaline electrolyzed water containing anions that has flowed through the neutralization tank 4. In the treatment tank 14, a reaction product (a reaction product resulting from the hardness components contained in the raw water) is generated by the reaction between the mixed hardness components and the alkaline electrolyzed water.

[0034] More specifically, in the treatment tank 14, the acidic electrolyzed water containing hardness components after regenerating the weakly acidic cation exchange resin 10 in the softening tank 3 is passed through the first recovery channel 18. Also, in the treatment tank 14, the alkaline electrolyzed water containing anions after regenerating the weakly basic anion exchange resin 11 in the neutralization tank 4 is passed through the second supply channel 19. Then, in the treatment tank 14, the acidic electrolyzed water containing hardness components and the alkaline electrolyzed water containing anions are mixed, and the hardness components react with the alkaline electrolyzed water. For example, when the hardness component in the acidic electrolyzed water is calcium ion, reactions such as the formation of calcium carbonate or calcium hydroxide occur by mixing with the alkaline electrolyzed water. And the reacted hardness components can be separated as reaction products.

[0035] Note that "the hardness components react" includes not only the case where all of the hardness components react, but also the state where components that do not react in the treatment tank 14 or components that do not exceed the solubility product are included.

[0036] Then, the treated water obtained by the reaction of the hardness components in the treatment tank 14 is passed through the electrolytic cell 12, electrolyzed in the electrolytic cell 12, and becomes acidic electrolyzed water and alkaline electrolyzed water, which are respectively supplied to the water softening tank 3 and the neutralization tank 4. Then, after the acidic electrolyzed water and the alkaline electrolyzed water are respectively reused in the water softening tank 3 and the neutralization tank 4, they are passed (recovered) to the treatment tank 14. Therefore, in the present embodiment, the acidic electrolyzed water and the alkaline electrolyzed water used for the regeneration of the weakly acidic cation exchange resin 10 and the regeneration of the weakly basic anion exchange resin 11, which were conventionally discarded, can be reused. Moreover, since the water in which the hardness components have reacted is reused, it is possible to suppress a reduction in the regeneration efficiency when regenerating the weakly acidic cation exchange resin 10.

[0037] The water supply pump 15 is a device that circulates water in the circulation flow path 16 (see FIG. 2) during the regeneration process by the regeneration device 6. The water supply pump 15 is provided in the water supply flow path 31 that communicatively connects between the treatment tank 14 and the electrolytic cell 12. Note that the water supply pump 15 is preferably arranged on the upstream side of the electrolytic cell 12 and the downstream side of the treatment tank 14. This is because it becomes easier to circulate water in the first circulation flow path 16a and the second circulation flow path 16b, which will be described later, with one water supply pump. Further, the water supply pump 15 is communicatively connected to a control unit 30, which will be described later, by wireless or wired means.

[0038] The filtration unit 32 is provided in the front stage of the water supply flow path 31 that connects the treatment tank 14 to the electrolytic cell 12. Then, the filtration unit 32 separates the reaction products (reaction products generated by the reaction of the acidic electrolyzed water containing the hardness components that have passed through the water softening tank 3 and the alkaline electrolyzed water containing the anions that have passed through the neutralization tank 4) contained in the water that has passed through the treatment tank 14.

[0039] The filtration unit 32 may have any form as long as it can separate the reaction product with the hardness component in the treatment tank 14. For example, forms using a filtration layer with granular filter media, a cyclone type solid-liquid separator, a hollow fiber membrane, etc. can be mentioned.

[0040] A plurality of on-off valves (on-off valves 21 to 27, on-off valve 33, on-off valve 34) are respectively provided in each flow path, and switch between the "open" state and the "closed" state in each flow path. Each of the plurality of on-off valves is communicably connected to a control unit 30 described later by wireless or wired means.

[0041] The first pH detection unit 28 is provided in the first supply flow path 17 and detects the pH value of the acidic electrolyzed water flowing through the first supply flow path 17 (hereinafter, the first pH value). The first pH detection unit 28 is communicably connected to a control unit 30 described later by wireless or wired means, and information regarding the detected first pH value is used as an input signal to the control unit 30. Note that the first pH value is included in the "first ion concentration" described in the claims.

[0042] The second pH detection unit 29 is provided in the first recovery flow path 18 and detects the pH value of the acidic electrolyzed water flowing through the first recovery flow path 18 (hereinafter, the second pH value). Similar to the first pH detection unit 28, the second pH detection unit 29 is communicably connected to the control unit 30 by wireless or wired means, and information regarding the detected second pH value is used as an input signal to the control unit 30. Note that the second pH value is included in the "second ion concentration" described in the claims.

[0043] Note that the pH of the acidic electrolyzed water flowing through the water softening tank 3 increases because the hydrogen ions in the acidic electrolyzed water are exchanged with the hardness components in the weakly acidic cation exchange resin 10, but the increase range becomes smaller as the regeneration process progresses. Therefore, by detecting the pH values of the acidic electrolyzed water flowing through the first supply flow path 17 and the first recovery flow path 18, the progress of the regeneration process can be estimated from the difference between these two pH values.

[0044] The control unit 30 controls the switching between the reproduction process and the softening process. Further, the control unit 30 controls the reproduction process of the weakly acidic cation exchange resin 10 in the softening tank 3 and the weakly basic anion exchange resin 11 in the neutralization tank 4. More specifically, the control unit 30 controls the operations of the electrode 13, the water supply pump 15, the on-off valves 21, 22, 23, 24, 25, 26, 27, 33, and 34 to switch between the softening process and the reproduction process and execute each process. In particular, the control unit 30 determines the end of the reproduction process based on the information on the pH values (the first pH value and the second pH value) from the first pH detection unit 28 and the second pH detection unit 29. The detailed operations will be described later.

[0045] Next, with reference to FIGS. 2 and 3, the circulation flow path 16 of the water softening device 1 will be described. FIG. 2 is a diagram showing the circulation flow path 16 of the water softening device 1. FIG. 3 is a diagram showing the state during the operation of the water softening device 1.

[0046] Although the description is repetitive, as shown in FIG. 2, in the water softening device 1, the electrolytic cell 12 and the treatment tank 14 constituting the reproduction device 6 are connected in communication by the water supply flow path 31, while the flow paths 7, 8, and 9 from the inlet 2 to the water intake 5 are respectively connected in communication by the first supply flow path 17, the first recovery flow path 18, the second supply flow path 19, and the second recovery flow path 20. And in the reproduction device 6, the circulation flow path 16 is configured.

[0047] The first supply flow path 17 is a flow path for supplying acidic electrolyzed water from the electrolytic cell 12 to the softening tank 3, and the on-off valve 21 and the first pH detection unit 28 are installed in the flow path. The first recovery flow path 18 is a flow path for recovering the acidic electrolyzed water containing the hardness components that have passed through the softening tank 3 to the treatment tank 14, and the on-off valve 22 and the second pH detection unit 29 are installed in the flow path.

[0048] The second supply channel 19 is a channel for supplying alkaline electrolyzed water from the electrolytic cell 12 to the neutralization tank 4, and an on-off valve 23 is installed in this channel. Further, the second recovery channel 20 is a channel for recovering the alkaline electrolyzed water that has passed through the neutralization tank 4 to the treatment tank 14, and an on-off valve 24 is installed in this channel.

[0049] The circulation channel 16 includes a first circulation channel 16a through which the water sent out from the treatment tank 14 by the water pump 15 flows through the water softening tank 3, and a second circulation channel 16b through which the water sent out from the treatment tank 14 by the water pump 15 flows through the neutralization tank 4.

[0050] As shown in FIG. 2 (white arrow), the first circulation channel 16a is a channel through which the water sent out from the treatment tank 14 by the water pump 15 circulates through the electrolytic cell 12 and the water softening tank 3 and then returns to the treatment tank 14. More specifically, the first circulation channel 16a is a channel through which the water sent out from the treatment tank 14 by the water pump 15 circulates in the order of the water supply channel 31, the electrolytic cell 12, the first supply channel 17 (the first pH detection unit 28, the on-off valve 21), the water softening tank 3, the first recovery channel 18 (the on-off valve 22, the second pH detection unit 29), and the treatment tank 14.

[0051] As shown in FIG. 2 (black arrow), the second circulation channel 16b is a channel through which the water sent out from the treatment tank 14 by the water pump 15 circulates through the electrolytic cell 12 and the neutralization tank 4 and then returns to the treatment tank 14. More specifically, the second circulation channel 16b is a channel through which the water sent out from the treatment tank 14 by the water pump 15 circulates in the order of the water supply channel 31, the electrolytic cell 12, the second supply channel 19 (the on-off valve 23), the neutralization tank 4, the second recovery channel 20 (the on-off valve 24), and the treatment tank 14.

[0052] Here, in order to circulate water (treated water) in the circulation channel 16, an on-off valve 25 is installed on the downstream side of the inlet 2 in the channel 7. By closing the on-off valve 25 and opening the on-off valve 21, the first supply channel 17 is communicatively connected to the upstream side of the water softening tank 3. As a result, the acidic electrolyzed water from the electrolytic cell 12 can be supplied to the water softening tank 3.

[0053] Also, a switching valve 26 is installed in the flow path 8 on the downstream side of the first recovery flow path 18 and on the upstream side of the second supply flow path 19. By closing the switching valve 26 and opening the switching valve 22, the first recovery flow path 18 is communicatively connected to the downstream side of the water softening tank 3. As a result, the water (acidic electrolyzed water containing a hardening component) that has passed through the water softening tank 3 can be recovered to the treatment tank 14.

[0054] Also, by closing the switching valve 26 and opening the switching valve 23, the second supply flow path 19 is communicatively connected to the upstream side of the neutralization tank 4. As a result, the alkaline electrolyzed water from the electrolysis tank 12 can be supplied to the neutralization tank 4.

[0055] Also, a switching valve 27 is installed in the flow path 9 on the downstream side of the neutralization tank 4. By closing the switching valve 27 and opening the switching valve 24, the second recovery flow path 20 is communicatively connected to the downstream side of the neutralization tank 4. As a result, the water (alkaline electrolyzed water containing anions) that has passed through the second recovery flow path 20 can be recovered to the treatment tank 14.

[0056] Also, a switching valve 33 is installed in the water supply flow path 31 on the downstream side of the treatment tank 14 (at a position between the treatment tank 14 and the water supply pump 15). By closing the switching valve 27, the circulation of water to the circulation flow path 16 can be started, while by opening the switching valve 27, the circulation of water to the circulation flow path 16 can be stopped.

[0057] Next, the water softening treatment and the regeneration treatment in the water softening apparatus 1 will be described.

[0058] In the softening treatment and the regeneration treatment, as shown in FIG. 3, the control unit 30 controls the on-off valves 21, 22, 23, 24, 25, 26, 27, 33, 34, the electrodes 13 of the electrolytic cell 12, and the water supply pump 15 to switch them to their respective flow states. Here, "ON" in FIG. 3 indicates a state where the on-off valve is "open", a state where the electrode 13 is energized, and a state where the water supply pump 15 is operating. The blank spaces indicate a state where the on-off valve is "closed", a state where the electrode 13 is not energized, and a state where the water supply pump 15 is stopped.

[0059] [Softening treatment] In the water softening device 1, as shown in FIG. 3, in the water softening treatment (during water softening), by opening the on-off valve 27 provided at the water intake 5 with the on-off valves 25 and 26 open, municipal water (raw water containing hardness components) from the outside flows through the water softening tank 3 and the neutralization tank 4, so that the softened water (neutral soft water) can be taken out from the water intake 5. At this time, the on-off valves 21, 22, 23, 24, and 33 are all in the closed state. Also, the electrodes 13 of the electrolytic cell 12 and the water supply pump 15 are also in the stopped state.

[0060] Specifically, in the water softening treatment, due to the pressure of the municipal water, the supplied raw water is supplied from the inlet 2 through the flow path 7 to the water softening tank 3. Then, it flows through the weakly acidic cation exchange resin 10 provided in the water softening tank 3. At this time, the cations, which are the hardness components in the raw water, are adsorbed by the action of the weakly acidic cation exchange resin 10, and hydrogen ions are released (ion exchange occurs). Then, the raw water is softened by removing the cations from the raw water. The softened water further proceeds to the neutralization tank 4 through the flow path 8. In the neutralization tank 4, the hydrogen ions contained in the softened water are adsorbed by the action of the weakly basic anion exchange resin 11. That is, since the hydrogen ions are removed from the treated soft water, the decreased pH rises, and the neutral water softened as domestic water can be taken out from the water intake 5.

[0061] [Regeneration treatment] The water softening tank 3 filled with the weakly acidic cation exchange resin 10 will have its cation exchange capacity decreased or lost if it continues to be used. That is, after all the hydrogen ions, which are the functional groups of the cation exchange resin, are exchanged with calcium ions or magnesium ions, which are hardness components, ion exchange can no longer occur. For this reason, in the water softening apparatus 1, the water softening tank 3 and the neutralization tank 4 are regenerated by the regeneration apparatus 6 at predetermined time intervals.

[0062] First, as shown in FIG. 3, at the time of water injection, that is, at the initial stage of the regeneration of the water softening tank 3 and the neutralization tank 4 by the regeneration apparatus 6, by opening the on-off valve 25 and the on-off valve 22, raw water is introduced from the inlet 2 through the water softening tank 3 to the treatment tank 14 by the pressure of the service water. At this time, the on-off valve 21, the on-off valve 26, the on-off valve 33, and the on-off valve 34 are closed. By storing a predetermined amount of water in the treatment tank 14, the amount of water during regeneration can be ensured.

[0063] Next, during regeneration, when the on-off valve 25, the on-off valve 26, and the on-off valve 27 are closed and the on-off valve 21, the on-off valve 22, the on-off valve 23, the on-off valve 24, and the on-off valve 33 are opened, as shown in FIG. 2, the first circulation flow path 16a and the second circulation flow path 16b are respectively formed.

[0064] Then, when the electrode 13 of the electrolytic cell 12 and the water supply pump 15 are operated, the water stored in the treatment tank 14 will circulate through each of the first circulation flow path 16a and the second circulation flow path 16b.

[0065] At this time, the acidic electrolyzed water generated in the electrolytic cell 12 is sent into the softening tank 3 through the first supply channel 17 and flows through the weakly acidic cation exchange resin 10 inside. That is, by flowing through the weakly acidic cation exchange resin 10, the cations (hardness components) adsorbed on the weakly acidic cation exchange resin 10 undergo an ion exchange reaction with the hydrogen ions contained in the acidic electrolyzed water. As a result, the weakly acidic cation exchange resin 10 is regenerated. Thereafter, the acidic electrolyzed water that has flowed through the weakly acidic cation exchange resin 10 contains cations and flows into the first recovery channel 18. That is, the acidic electrolyzed water containing cations that has flowed through the weakly acidic cation exchange resin 10 is recovered into the treatment tank 14 through the first recovery channel 18.

[0066] On the other hand, the alkaline electrolyzed water generated in the electrolytic cell 12 is sent into the neutralization tank 4 through the second supply channel 19 and flows through the weakly basic anion exchange resin 11 inside. That is, by flowing through the weakly basic anion exchange resin 11, the anions adsorbed on the weakly basic anion exchange resin 11 undergo an ion exchange reaction with the hydroxide ions contained in the alkaline electrolyzed water. As a result, the weakly basic anion exchange resin 11 is regenerated. Thereafter, the alkaline electrolyzed water that has flowed through the weakly basic anion exchange resin 11 contains anions and flows into the second recovery channel 20. That is, the alkaline electrolyzed water containing anions that has flowed through the weakly basic anion exchange resin 11 is recovered into the treatment tank 14 through the second recovery channel 20.

[0067] And in the treatment tank 14, the acidic electrolyzed water containing cations recovered from the softening tank 3 and the alkaline electrolyzed water containing anions recovered from the neutralization tank 4 are mixed. At this time, inside the treatment tank 14, the hardness components, which are cations in the acidic electrolyzed water, react with the alkaline electrolyzed water. For example, when the hardness component in the acidic electrolyzed water is calcium ion, calcium hydroxide is generated by the alkaline electrolyzed water, or calcium carbonate is generated by combining with carbonate ions that always exist in water.

[0068] Thereafter, when the water treated in the treatment tank 14 flows through the filtration unit 32, the reaction products are removed, and the water is passed through the water supply channel 31 again to the electrolytic cell 12. Then, the passed water is electrolyzed again in the electrolytic cell 12.

[0069] Here, the electrolyzed water (acidic electrolyzed water, alkaline electrolyzed water) electrolyzed again in the electrolytic cell 12 is used for the regeneration of the weakly acidic cation exchange resin 10 and the weakly basic anion exchange resin 11, respectively. That is, the acidic electrolyzed water used for the regeneration of the weakly acidic cation exchange resin 10 is reused as electrolyzed water again after the hardness components are changed into reaction products and filtered in the treatment tank 14. Moreover, the hardness components contained in the water are reduced compared with the case of municipal water (raw water containing hardness components) supplied from the outside or the case without the treatment tank 14. Also, when electrolyzed in the electrolytic cell 12, the hardness components, which are cations, move to the alkaline electrolyzed water side, so the hardness of the acidic electrolyzed water decreases, and the decrease in the regeneration efficiency of the weakly acidic cation exchange resin 10 can be suppressed. Furthermore, the adhesion of deposits caused by the hardness components can be suppressed inside the electrolytic cell 12 and the water softening tank 3.

[0070] On the other hand, during the regeneration process of the water softening tank 3, the first pH detection unit 28 and the second pH detection unit 29 detect the pH values of the acidic electrolyzed water, respectively, and the control unit 30 acquires information regarding the pH values (first pH value, second pH value) of the acidic electrolyzed water output from the first pH detection unit 28 and the second pH detection unit 29.

[0071] Then, when the difference between the first pH value and the second pH value is equal to or less than a preset reference value (pH reference value), the control unit 30 determines the end of the regeneration process, and when the difference between the first pH value and the second pH value exceeds the reference value, the control unit 30 determines the continuation of the regeneration process. In this embodiment, the end determination of the weakly acidic cation exchange resin 10 in the water softening tank 3 is regarded as the end of the regeneration process of the weakly basic anion exchange resin 11 in the neutralization tank 4.

[0072] Here, the acidic electrolyzed water flowing through the water softening tank 3 has its pH increased because hydrogen ions in the acidic electrolyzed water are exchanged with hardness components in the weakly acidic cation exchange resin 10. However, as the regeneration process progresses, the increase amplitude becomes smaller. Therefore, the reference value is set based on the difference in pH values when the regeneration of the weakly acidic cation exchange resin 10 experimentally verified is completed.

[0073] When the end of the regeneration process is determined, the control unit 30 stops the energization of the electrodes 13 of the electrolytic cell 12 and stops the operation of the water supply pump 15. Then, when the on-off valve 34 is opened, due to the action of the air vent valve 35, the water in the treatment tank 14 is drained to the outside. After that, the on-off valve 34 is closed, and the on-off valves 21, 22, 23, 24, 25, 26, 27 are switched to shift to the water softening treatment.

[0074] As described above, in the water softening device 1, the water softening treatment and the regeneration treatment are repeatedly executed.

[0075] As described above, according to the water softening device 1 according to the first embodiment, the following effects can be enjoyed.

[0076] (1) The water softening device 1 includes a water softening tank 3, a neutralization tank 4, an electrolysis tank 12, a treatment tank 14, and a control unit 30. The water softening tank 3 softens raw water containing hardness components with a weakly acidic cation exchange resin 10. The neutralization tank 4 neutralizes the pH of the softened water flowing through the water softening tank 3 with a weakly basic anion exchange resin 11. The electrolysis tank 12 generates acidic electrolyzed water for regenerating the weakly acidic cation exchange resin 10 in the water softening tank 3 and alkaline electrolyzed water for regenerating the weakly basic anion exchange resin 11 in the neutralization tank 4. The treatment tank 14 mixes the acidic electrolyzed water flowing through the water softening tank 3 and the alkaline electrolyzed water flowing through the neutralization tank 4 and supplies them to the electrolysis tank 12. The control unit 30 acquires ion concentration information regarding the first ion concentration of the acidic electrolyzed water before being introduced from the electrolysis tank 12 into the water softening tank 3 and the second ion concentration of the acidic electrolyzed water after flowing through the water softening tank 3, and controls the regeneration processes of the weakly acidic cation exchange resin 10 in the water softening tank 3 and the weakly basic anion exchange resin 11 in the neutralization tank 4. And the control unit 30 is configured to determine the end of the regeneration process based on the ion concentration information.

[0077] According to such a configuration, the regeneration process can be terminated at the timing when the regeneration of the weakly acidic cation exchange resin 10 in the water softening tank 3 is completed. Thereby, since the regeneration process can be performed with an appropriate amount of acidic electrolyzed water, it is possible to suppress excessive consumption of the electrodes for performing electrolysis for generating acidic electrolyzed water, and the performance of the regeneration process can be maintained over a long period. That is, it is possible to provide the water softening device 1 capable of efficiently regenerating the weakly acidic cation exchange resin 10 with the acidic electrolyzed water generated by electrolysis.

[0078] (2) In the water softening device 1, the control unit 30 determines the end of the regeneration process when the difference between the first ion concentration and the second ion concentration is less than or equal to a reference value (pH reference value), and determines the continuation of the regeneration process when the difference between the first ion concentration and the second ion concentration exceeds the reference value. Thereby, it becomes possible to highly accurately control the end of the regeneration process of the weakly acidic cation exchange resin 10 with acidic electrolyzed water.

[0079] (3) In the softening device 1, the first ion concentration is the first pH value of the acidic electrolyzed water before being introduced from the electrolytic cell 12 into the softening tank 3, and the second ion concentration is the second pH value of the acidic electrolyzed water after flowing through the softening tank 3. Thereby, based on the hydrogen ion concentration (pH value) before and after softening, the completion of the regeneration of the weakly acidic cation exchange resin 10 is determined, so that the timing of the completion of the regeneration can be detected more accurately. As a result, the regeneration treatment can be performed with a more appropriate amount of acidic electrolyzed water, so that the electrode 13 for electrolysis for generating the acidic electrolyzed water can be prevented from being excessively consumed, and the performance of the regeneration treatment can be maintained over a long period. That is, it becomes possible to more efficiently perform the regeneration of the weakly acidic cation exchange resin 10 with the acidic electrolyzed water generated by electrolysis.

[0080] (4) The softening water treatment device 1 further includes a first supply passage 17 that can draw out acidic electrolyzed water from the electrolytic cell 12 and supply it to the upstream side of the softening tank 3, a second supply passage 19 that can draw out alkaline electrolyzed water from the electrolytic cell 12 and supply it to the upstream side of the neutralization tank 4, a first recovery passage 18 that can connect the upstream side of the treatment tank 14 to the downstream side of the softening tank 3, a second recovery passage 20 that can connect the upstream side of the treatment tank 14 to the downstream side of the neutralization tank 4, a first pH detection unit 28 provided in the first supply passage 17 for detecting the first pH value of the acidic electrolyzed water flowing through the first supply passage 17, and a second pH detection unit 29 provided in the first recovery passage 18 for detecting the second pH value of the acidic electrolyzed water flowing through the first recovery passage 18. Also, during the softening water treatment, the softening water treatment device 1 circulates and discharges the raw water supplied from the outside in the order of the softening tank 3 and the neutralization tank 4 by switching each on-off valve. Further, during the regeneration treatment, the softening water treatment device 1 supplies the water in the treatment tank 14 from the electrolytic cell 12 to the softening tank 3 through the first supply passage 17, and recovers the water that has passed through the softening tank 3 to the treatment tank 14 through the first recovery passage 18. At the same time, the softening water treatment device 1 supplies the water in the treatment tank 14 from the electrolytic cell 12 to the neutralization tank 4 through the second supply passage 19, and recovers the water that has passed through the neutralization tank 4 to the treatment tank 14 through the second recovery passage 20. Then, based on the pH information from the first pH detection unit 28 and the second pH detection unit 29, the control unit 30 ends the regeneration treatment and resumes the softening water treatment by switching each on-off valve. Thereby, by switching each on-off valve based on the pH information, it is possible to easily switch from the regeneration treatment to the softening water treatment and execute it.

[0081] (5) In the water softening device 1, a filtration unit 32 is provided in the treatment tank 14 for separating reaction products (reaction products resulting from the hardness components contained in the raw water) by the reaction of the acidic electrolyzed water that has flowed through the water softening tank 3 and the alkaline electrolyzed water that has flowed through the neutralization tank 4. As a result, in the regeneration process, the reaction products can be reliably separated from the water supplied from the treatment tank 14 to the electrolytic cell 12. Therefore, compared with the case of supplying raw water containing hardness components from the outside to the electrolytic cell 12, the hardness components contained in the water supplied from the treatment tank 14 to the electrolytic cell 12 will decrease. For this reason, inside the electrolytic cell 12 or the water softening tank 3, the adhesion of deposits caused by the hardness components can be suppressed.

[0082] (6) The water softening device 1 is provided with a treatment tank 14 for mixing the acidic electrolyzed water containing hardness components that has flowed through the water softening tank 3 and the alkaline electrolyzed water containing anions that has flowed through the neutralization tank 4. In the treatment tank 14, reaction products (reaction products resulting from the hardness components contained in the raw water) are generated by the reaction of the mixed hardness components and the alkaline electrolyzed water and can be separated. The treated water obtained by the reaction of the hardness components in the treatment tank 14 is passed through and electrolyzed in the electrolytic cell 12, and becomes acidic electrolyzed water and alkaline electrolyzed water and is supplied to the water softening tank 3 and the neutralization tank 4 respectively. Then, the acidic electrolyzed water and the alkaline electrolyzed water are reused in the water softening tank 3 and the neutralization tank 4 respectively, and then passed through (recovered) to the treatment tank 14. As a result, the acidic electrolyzed water and the alkaline electrolyzed water used for the regeneration of the weakly acidic cation exchange resin 10 and the regeneration of the weakly basic anion exchange resin 11 can be reused. Moreover, since the water in which the hardness components have reacted is reused, a reduction in the regeneration efficiency when regenerating the weakly acidic cation exchange resin 10 can be suppressed.

[0083] (Embodiment 2) The water softening device 1a according to Embodiment 2 of the present invention will be described.

[0084] The water softening device 1a according to Embodiment 2 of the present invention is different from Embodiment 1 in that the first TDS detector 28a and the second TDS detector 29a are used to detect the ion concentrations (such as hardness components and hydrogen ions) of acidic electrolyzed water before and after the flow through the water softening tank 3. The configuration of the water softening device 1a other than this is the same as that of the water softening device 1 according to Embodiment 1. Hereinafter, the content already described in Embodiment 1 will be appropriately omitted from the repeated description, and the points different from Embodiment 1 will be mainly described.

[0085] Referring to FIG. 1, the water softening device 1a according to Embodiment 2 of the present invention will be described.

[0086] The water softening device 1a is a device that generates municipally supplied water (raw water containing hardness components) supplied from the outside into neutral soft water that can be used as domestic water.

[0087] Specifically, as shown in FIG. 1, the water softening device 1a includes an inlet 2 for raw water from the outside, a water softening tank 3, a neutralization tank 4, a water intake 5 for the treated soft water, and a regeneration device 6. Further, the regeneration device 6 includes an electrolytic cell 12, a treatment tank 14, a water pump 15, and a filtration unit 32 as a separation tank. The water softening device 1 includes a plurality of on-off valves (on-off valves 21 to 27, on-off valve 33, on-off valve 34), a first TDS detector 28a, a second TDS detector 29a, and a control unit 30.

[0088] For the first TDS detector 28a and the second TDS detector 29a, a detector for measuring the amount of TDS (Total Dissolved Solid) contained in water is used. The detector for measuring the amount of TDS has high durability and a low required frequency of equipment calibration, so it can be used over a long period of time.

[0089] Water (pure water) is an insulator that hardly conducts electricity by itself, but it conducts electricity when various substances dissolve (ionize). That is, the electrical conductivity of a liquid is an indicator of the amount of ionized substances contained in the liquid. In general tap water, it is proportional to the contents of calcium ions, magnesium ions, sodium ions, chloride ions, etc. that are abundantly contained in river water or groundwater that is the source of the tap water. In the present embodiment, TDS represents the total concentration of ions (such as calcium ions, magnesium ions, chloride ions, hydrogen ions, etc.) contained in the water flowing through each TDS detection unit during the regeneration process. In water of the same water system, the electrical conductivity and TDS are approximately in a proportional relationship.

[0090] The first TDS detection unit 28a is provided in the first supply flow path 17 and detects the TDS value (hereinafter, the first TDS value) of the acidic electrolyzed water flowing through the first supply flow path 17. The first TDS detection unit 28a is communicably connected to the control unit 30 wirelessly or by wire, and the information regarding the detected first TDS value is used as an input signal to the control unit 30. Note that the first TDS value is included in the "first ion concentration" described in the claims.

[0091] The second TDS detection unit 29a is provided in the first recovery flow path 18 and detects the TDS value (hereinafter, the second TDS value) of the acidic electrolyzed water flowing through the first recovery flow path 18. The second TDS detection unit 29a is communicably connected to the control unit 30 wirelessly or by wire in the same manner as the first TDS detection unit 28a, and the information regarding the detected second TDS value is used as an input signal to the control unit 30. Note that the second TDS value is included in the "second ion concentration" described in the claims.

[0092] Note that the pH of the acidic electrolyzed water flowing through the water softening tank 3 increases and the TDS value changes because the hydrogen ions in the acidic electrolyzed water are exchanged with the hardness components in the weakly acidic cation exchange resin 10. Since the change width becomes smaller as the regeneration process progresses, the progress of the regeneration process can be estimated from the difference between these two TDS values by detecting the TDS values of the acidic electrolyzed water flowing through the first supply flow path 17 and the first recovery flow path 18.

[0093] The control unit 30 controls the switching between the reproduction process and the softening process. Further, the control unit 30 controls the regeneration process of the weakly acidic cation exchange resin 10 in the softening tank 3 and the weakly basic anion exchange resin 11 in the neutralization tank 4. More specifically, the control unit 30 controls the operations of the electrode 13, the water supply pump 15, the on-off valves 21, 22, 23, 24, 25, 26, 27, 33, and 34, and switches between the softening process and the regeneration process and executes each process. In particular, the control unit 30 determines the end of the regeneration process based on the information on the TDS values (the first TDS value and the second TDS value) from the first TDS detection unit 28a and the second TDS detection unit 29a.

[0094] Specifically, during the regeneration process of the softening tank 3, the first TDS detection unit 28a and the second TDS detection unit 29a respectively detect the TDS value of the acidic electrolyzed water, and the control unit 30 acquires the information on the TDS values (the first TDS value and the second TDS value) of the acidic electrolyzed water output from the first TDS detection unit 28a and the second TDS detection unit 29a.

[0095] Then, when the difference between the first TDS value and the second TDS value is equal to or less than a preset reference value (TDS reference value), the control unit 30 determines the end of the regeneration process, and when the difference between the first TDS value and the second TDS value exceeds the reference value, the control unit 30 determines the continuation of the regeneration process. In this embodiment, the end determination of the weakly acidic cation exchange resin 10 in the softening tank 3 also serves as the end of the regeneration process of the weakly basic anion exchange resin 11 in the neutralization tank 4.

[0096] Here, since the hydrogen ions in the acidic electrolyzed water flowing through the softening tank 3 are exchanged with the hardness components in the weakly acidic cation exchange resin 10, the pH increases and the TDS value changes. As the regeneration process progresses, the change range becomes smaller, so the reference value is set based on the difference in the TDS value when the regeneration of the weakly acidic cation exchange resin 10 experimentally verified is completed.

[0097] As described above, according to the water softening device 1a according to the second embodiment, in addition to the effects (1), (2), and (5) described above, the following effects can be enjoyed.

[0098] (6) In the softening water treatment device 1a, the first ion concentration is set as the first TDS value of the acidic electrolyzed water before being introduced from the electrolytic cell 12 into the softening water tank 3, and the second ion concentration is set as the second TDS value of the acidic electrolyzed water after flowing through the softening water tank 3. Thereby, based on the TDS values before and after softening water treatment, the completion of the regeneration of the weakly acidic cation exchange resin 10 is determined, so that the timing when the regeneration is completed can be detected more accurately. Then, since the regeneration treatment can be performed with a more appropriate amount of acidic electrolyzed water, it is possible to suppress excessive consumption of the electrode 13 for performing electrolysis for generating acidic electrolyzed water, and the performance of the regeneration treatment can be maintained over a long period. That is, it is possible to obtain the softening water treatment device 1a capable of more efficiently performing the regeneration of the weakly acidic cation exchange resin 10 with the acidic electrolyzed water generated by electrolysis.

[0099] (7) In the softening water treatment device 1a, detectors for measuring the amount of TDS contained in water are used for the first TDS detection unit 28a and the second TDS detection unit 29a. The detectors for measuring the amount of TDS have high durability and a low required frequency of equipment calibration. Thereby, the softening water treatment device 1a can be made into a device that can be used over a long period.

[0100] (8) The softening water treatment device 1a further includes a first supply channel 17 that can draw acidic electrolyzed water from the electrolytic cell 12 and supply it to the upstream side of the softening water tank 3, a second supply channel 19 that can draw alkaline electrolyzed water from the electrolytic cell 12 and supply it to the upstream side of the neutralization tank 4, a first recovery channel 18 that can connect the upstream side of the treatment tank 14 to the downstream side of the softening water tank 3, a second recovery channel 20 that can connect the upstream side of the treatment tank 14 to the downstream side of the neutralization tank 4, a first TDS detection unit 28a provided in the first supply channel 17 for detecting the first TDS value of the acidic electrolyzed water flowing through the first supply channel 17, and a second TDS detection unit 29a provided in the first recovery channel 18 for detecting the second TDS value of the acidic electrolyzed water flowing through the first recovery channel 18. Further, when performing the softening water treatment, the softening water treatment device 1 circulates and discharges the raw water supplied from the outside in the order of the softening water tank 3 and the neutralization tank 4 by switching each on-off valve. Also, when performing the regeneration treatment, the softening water treatment device 1 supplies the water in the treatment tank 14 to the softening water tank 3 through the first supply channel 17 from the electrolytic cell 12, recovers the water that has flowed through the softening water tank 3 to the treatment tank 14 through the first recovery channel 18, supplies the water in the treatment tank 14 to the neutralization tank 4 through the second supply channel 19 from the electrolytic cell 12, and recovers the water that has flowed through the neutralization tank 4 to the treatment tank 14 through the second recovery channel 20. Then, based on the TDS information from the first TDS detection unit 28a and the second TDS detection unit 29a, the control unit 30 ends the regeneration treatment and resumes the softening water treatment by switching each on-off valve. Thereby, by switching each on-off valve based on the TDS information, it is possible to easily switch from the regeneration treatment to the softening water treatment and execute it.

[0101] As described above, the embodiments of the present invention have been described based on the embodiments. These embodiments are examples, and it is understood by those skilled in the art that various modifications are possible for each of these constituent elements or combinations of each processing process, and such modifications are also within the scope of the present invention.

[0102] In the softening device 1 according to the first embodiment, the first pH detection unit 28 and the second pH detection unit 29 are provided inside the device, but it is not limited thereto. For example, each pH detection unit may be provided outside the device to detect the pH value of the acidic electrolyzed water. Even with such a configuration, the same effects can be enjoyed.

[0103] Similarly, in the softening device 1a according to the second embodiment, the first TDS detection unit 28a and the second TDS detection unit 29a are provided inside the device, but it is not limited thereto. For example, each TDS detection unit may be provided outside the device to detect the TDS value of the acidic electrolyzed water. Even with such a configuration, the same effects can be enjoyed.

Industrial Applicability

[0104] The softening device according to the present invention can be applied to a point-of-use water purification device (POU) or a point-of-entry water purification device (POE) installed at the place of use.

Explanation of Signs

[0105] 1 Softening device 1a Softening device 2 Inlet 3 Softening tank 4 Neutralization tank 5 Water intake 6 Regeneration device 7 Flow path 8 Flow path 9 Flow path 10 Weak acidic cation exchange resin 11 Weak basic anion exchange resin 12 Electrolysis tank 13 Electrode 14 Treatment tank 15 Water supply pump 16 Circulation flow path 16a First circulation flow path 16b Second circulation flow path 17 First supply flow path 18 First recovery flow path 19 Second supply flow path 20 Second Recovery Flow Path 21 On - Off Valve 22 On - Off Valve 23 On - Off Valve 24 On - Off Valve 25 On - Off Valve 26 On - Off Valve 27 On - Off Valve 28 First pH Detection Unit 28a First TDS Detection Unit 29 Second pH Detection Unit 29a Second TDS Detection Unit 30 Control Unit 31 Water Supply Flow Path 32 Filtration Unit 33 On - Off Valve 34 On - Off Valve 35 Air Vent Valve

Claims

1. A softening tank that softens raw water containing a hardness component using a weakly acidic cation exchange resin; A neutralization tank that neutralizes the pH of the softened water flowing through the softening tank using a weakly basic anion exchange resin; An electrolytic cell that generates acidic electrolyzed water for regenerating the weakly acidic cation exchange resin in the softening tank and alkaline electrolyzed water for regenerating the weakly basic anion exchange resin in the neutralization tank; A treatment tank that mixes the acidic electrolyzed water flowing through the softening tank and the alkaline electrolyzed water flowing through the neutralization tank and supplies the mixture to the electrolytic cell; A filtration unit that removes reaction products generated by mixing the acidic electrolyzed water and the alkaline electrolyzed water; An ion concentration information acquisition unit that acquires ion concentration information regarding a first ion concentration of the acidic electrolyzed water before being introduced from the electrolytic cell into the softening tank and a second ion concentration of the acidic electrolyzed water after flowing through the softening tank, and a control unit that controls the regeneration treatment of the weakly acidic cation exchange resin in the softening tank and the weakly basic anion exchange resin in the neutralization tank; Comprising: The softening device, wherein the control unit determines the end of the regeneration treatment based on the ion concentration information.

2. The softening device according to claim 1, wherein the control unit determines the end of the regeneration treatment when the difference between the first ion concentration and the second ion concentration is less than or equal to a reference value, and determines the continuation of the regeneration treatment when the difference between the first ion concentration and the second ion concentration exceeds the reference value.

3. The first ion concentration is a first pH value of the acidic electrolyzed water before being introduced from the electrolytic cell into the softening tank, The softening device according to claim 1 or 2, wherein the second ion concentration is a second pH value of the acidic electrolyzed water after flowing through the softening tank.

4. A first supply channel that can draw out the acidic electrolyzed water from the electrolytic cell and supply it to the upstream side of the softening tank; A second supply channel that can draw out the alkaline electrolyzed water from the electrolytic cell and supply it to the upstream side of the neutralization tank; A first recovery channel that can connect the upstream side of the treatment tank to the downstream side of the softening tank; A second recovery channel that can connect the upstream side of the treatment tank to the downstream side of the neutralization tank; A first pH detection unit provided in the first supply channel for detecting the first pH value of the acidic electrolyzed water flowing through the first supply channel; A second pH detection unit provided in the first recovery channel for detecting the second pH value of the acidic electrolyzed water flowing through the first recovery channel; further comprising; During the softening treatment, by switching the on-off valve, the raw water supplied from the outside is circulated and discharged in the order of the softening tank and the neutralization tank; During the regeneration treatment, by switching the on-off valve, the water in the treatment tank is supplied from the electrolytic cell to the softening tank through the first supply channel, and the water that has flowed through the softening tank is recovered from the first recovery channel to the treatment tank. At the same time, the water in the treatment tank is supplied from the electrolytic cell to the neutralization tank through the second supply channel, and the water that has flowed through the neutralization tank is recovered from the second recovery channel to the treatment tank; The control unit is characterized in that, based on the pH information from the first pH detection unit and the second pH detection unit, by switching the on-off valve, the regeneration treatment is terminated and the softening treatment is restarted. The softening device according to claim 3.

5. The first ion concentration is the first TDS value of the acidic electrolyzed water before being introduced from the electrolytic cell into the softening tank; The softening device according to claim 1 or 2, wherein the second ion concentration is the second TDS value of the acidic electrolyzed water after flowing through the softening tank.

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