Softening device

Abstract

To provide a water softener which enables quick shift to water softening treatment from regeneration treatment, and efficient water softening.SOLUTION: A water softener 1 includes: a plurality of water softening tanks 3 for softening raw water containing a hardness component by a weakly acidic cation-exchange resin 7; a plurality of neutralization tanks 4 for neutralizing a pH of soft water circulating in the water softening tanks 3 by a weakly basic anion-exchange resin 8; and an electric cell 9 for generating acidic electrolytic water for regenerating the weakly acidic cation-exchange resin 7 of the water softening tanks 3, and alkaline electrolytic water for regenerating the weakly basic anion-exchange resin 8 of the neutralization tanks 4. The water softening treatment makes the water softening tanks 3 and the neutralization tanks 4 alternately communicate and connect with each other, and softens the raw water. The regeneration treatment regenerates the water softening tanks 3 and the neutralization tanks 4 by first regeneration treatment of regenerating the water softening tanks 3, and the neutralization tanks 4 excluding the neutralization tank 4 in the last stage, and second regeneration treatment of regenerating the water softening tanks 3, and the neutralization tanks 4 including the neutralization tank 4 in the last stage.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 exchanges hardness components (for example, calcium ions, magnesium ions) in raw water with hydrogen ions to soften the raw water. Then, the hydrogen ions in the water softened by the weakly acidic cation exchange resin are neutralized by being adsorbed by a weakly basic anion exchange resin provided downstream of the weakly acidic cation exchange resin. In a conventional water softening device, as a method for regenerating the weakly basic anion exchange resin, a method of regenerating the weakly basic anion exchange resin with alkaline electrolyzed water generated by electrolysis is known (for example, see Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In such a conventional water softening device, when switching from the regeneration treatment to the water softening treatment, the electrolyzed water used in the regeneration treatment remains in the ion exchange resin and the piping, which affects the water quality such as the pH or hardness of the obtained softened water. Therefore, it was necessary to wash the ion exchange resin and the piping by passing city water through the water softening device after the regeneration treatment. However, when city water is passed through after the regeneration treatment, there is a problem that the transition from the regeneration treatment to the water softening treatment is not rapid.

[0005] The present invention solves the above-described conventional problems, and an object thereof is to provide a water softening device that can rapidly shift from a regeneration treatment to a water softening treatment and efficiently perform water softening.

Means for Solving the Problems

[0006] And, in order to achieve this object, the water softening device according to the present invention includes a plurality of water softening tanks that soften raw water containing hardness components with a weakly acidic cation exchange resin, and a plurality of neutralization tanks that neutralize the pH of the softened water flowing through the water softening tanks with a weakly basic anion exchange resin, acidic electrolyzed water for regenerating the weakly acidic cation exchange resin in the water softening tanks, and alkaline electrolyzed water for regenerating the weakly basic anion exchange resin in the neutralization tanks. And an electrolytic cell that generates And in the water softening treatment, the water softening tank and the neutralization tank are alternately connected in communication to perform softening of the raw water. In the regeneration treatment, the regeneration of the water softening tank and the neutralization tank is executed by a first regeneration treatment for regenerating the neutralization tanks excluding the water softening tank and the last-stage neutralization tank, and a second regeneration treatment for regenerating the neutralization tanks including the water softening tank and the last-stage neutralization tank. Thereby, the intended object is achieved.

Effects of the Invention

[0007] According to the present invention, it is possible to provide a water softening device that can rapidly shift from a regeneration treatment to a water softening treatment and efficiently perform water softening.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0009] The water softening device according to the present invention includes a plurality of water softening tanks that soften raw water containing hardness components with a weakly acidic cation exchange resin, a plurality of neutralization tanks that neutralize the pH of the softened water flowing through the water softening tanks with a weakly basic anion exchange resin, acidic electrolyzed water for regenerating the weakly acidic cation exchange resin in the water softening tanks, and an electrolytic cell that generates alkaline electrolyzed water for regenerating the weakly basic anion exchange resin in the neutralization tanks. In the water softening process, the water softening tanks and the neutralization tanks are alternately connected in communication to perform the softening of the raw water. In the regeneration process, the regeneration of the water softening tanks and the neutralization tanks is performed by a first regeneration process for regenerating the neutralization tanks except for the water softening tanks and the last-stage neutralization tank, and a second regeneration process for regenerating the neutralization tanks including the water softening tanks and the last-stage neutralization tank.

[0010] According to such a configuration, by switching from the second regeneration process to the first regeneration process, the regeneration process is performed with the last-stage neutralization tank excluded. And in the first regeneration process, since alkaline electrolyzed water is not circulated to the last-stage neutralization tank, even when immediately shifting to the water softening process after the end of the first regeneration process, it is possible to obtain neutral softened water instead of softened water containing alkaline electrolyzed water from the water intake. That is, the water softening device can quickly shift from the regeneration process to the water softening process and perform water softening efficiently.

[0011] Further, in the water softening device according to the present invention, the second regeneration process may be executed when the set period set based on the usage status of the device is reached, and the first regeneration process may be executed when the water softening process has not been executed outside the set period. By doing so, since the first regeneration process is executed in a state where the water softening process has not been executed outside the set period, it becomes possible to shorten the processing time of the second regeneration process executed during the set period. That is, the water softening device can quickly shift from the regeneration process to the water softening process and perform water softening efficiently.

[0012] Further, in the water softening device according to the present invention, when the second regeneration process ends, after performing a drainage process of discharging the acidic electrolyzed water used for the regeneration of the water softening tank and the alkaline electrolyzed water used for the regeneration of the neutralization tank to the outside, the water softening process is executed. When the first regeneration process ends, it is preferable that the water softening process is executed without performing the drainage process. By doing so, in the second regeneration process, the influence of the alkaline electrolyzed water remaining in the last-stage neutralization tank can be surely suppressed, and in the first regeneration process, the influence of the alkaline electrolyzed water remaining in the last-stage neutralization tank can be suppressed while quickly shifting to the water softening process.

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the following embodiments are an example of embodying the present invention and do not limit the technical scope of the present invention. Also, each figure described in the embodiments is a schematic figure, and the ratio of the size and thickness of each component in each figure does not necessarily reflect the actual dimensional ratio.

[0014] (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 configuration of 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.

[0015] (Overall Configuration) The water softening device 1 is a device that generates the municipally supplied water (raw water containing hardness components) supplied from the outside into neutral soft water that can be used as domestic water.

[0016] Specifically, as shown in FIG. 1, the water softening device 1 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. The water softening tank 3 is composed of a first water softening tank 3a and a second water softening tank 3b. The neutralization tank 4 is composed of a first neutralization tank 4a and a second neutralization tank 4b. Further, the regeneration device 6 includes an electrolytic cell 9, a treatment tank 11, and a water supply pump 12. Also, the water softening device 1 includes a plurality of on-off valves (on-off valves 41 to 45, on-off valves 51 to 57, on-off valve 61, and on-off valve 62) and a control unit 15.

[0017] The inlet 2 is connected to the municipally supplied water. The water softening device 1 can take out the water after the water softening treatment from the water intake 5 by the pressure of the municipally supplied water.

[0018] From the inlet 2 to the water intake 5, they are connected by a flow path 20, a flow path 21, a flow path 22, a flow path 23, and a flow path 24. The flow path 20 is a flow path connecting the inlet 2 to the first water softening tank 3a. The flow path 21 is a flow path connecting the first water softening tank 3a to the first neutralization tank 4a. The flow path 22 is a flow path connecting the first neutralization tank 4a to the second water softening tank 3b. The flow path 23 is a flow path connecting the second water softening tank 3b to the second neutralization tank 4b. The flow path 24 is a flow path connecting the second neutralization tank 4b to the water intake 5.

[0019] In other words, the flow path 20 is a flow path that guides the raw water containing hardness components from the inlet 2 to the first water softening tank 3a. Also, the flow path 21 is a flow path that guides the water that has undergone the water softening treatment in the first water softening tank 3a to the first neutralization tank 4a. The flow path 22 is a flow path that guides the water that has been neutralized in the first neutralization tank 4a to the second water softening tank 3b. The flow path 23 is a flow path that guides the raw water softened by the second water softening tank 3b to the second neutralization tank 4b. The flow path 24 is a flow path that guides the soft water neutralized by the second neutralization tank 4b to the water intake 5.

[0020] That is, in the water softening device 1, in the water softening treatment, the tap water supplied from the outside flows in the order of the inlet 2, the flow path 20, the first water softening tank 3a, the flow path 21, the first neutralization tank 4a, the flow path 22, the second water softening tank 3b, the flow path 23, the second neutralization tank 4b, the flow path 24, and the water intake 5, and is discharged as neutral soft water.

[0021] (Water softening tank and neutralization tank) The water softening tank 3 is configured by filling, for example, a cylindrical container with a weakly acidic cation exchange resin 7. Further, the neutralization tank 4 is configured by filling, for example, a cylindrical container with a weakly basic anion exchange resin 8.

[0022] The water softening tank 3 includes a first water softening tank 3a and a second water softening tank 3b. The first water softening tank 3a is configured by filling with a first weakly acidic cation exchange resin 7a. The second water softening tank 3b is configured by filling with a second weakly acidic cation exchange resin 7b. Further, the first water softening tank 3a and the second water softening tank 3b have the same flow path length, flow path cross-sectional area, and the same volume of weakly acidic cation exchange resin 7. Hereinafter, regarding the first weakly acidic cation exchange resin 7a and the second weakly acidic cation exchange resin 7b, when there is no particular need to distinguish between the two, they will be described as the weakly acidic cation exchange resin 7.

[0023] The neutralization tank 4 includes a first neutralization tank 4a and a second neutralization tank 4b. The first neutralization tank 4a is configured by filling, for example, a cylindrical container with a first weakly basic anion exchange resin 8a. Further, the second neutralization tank 4b is configured by filling with a second weakly basic anion exchange resin 8b. Further, the first neutralization tank 4a and the second neutralization tank 4b have the same flow path length, flow path cross-sectional area, and the same volume of weakly basic anion exchange resin 8. Hereinafter, regarding the first weakly basic anion exchange resin 8a and the second weakly basic anion exchange resin 8b, when there is no particular need to distinguish between the two, they will be described as the weakly basic anion exchange resin 8.

[0024] Here, there are no particular restrictions on the weakly acidic cation exchange resin 7, and general-purpose ones can be used. For example, those having a carboxyl group (-COOH) as an exchange group can be mentioned. Also, the hydrogen ion (H + ), which is the counter ion of the carboxyl group, may be a cation such as a metal ion or an ammonium ion (NH4 + ).

[0025] Also, there are no particular restrictions on the weakly basic anion exchange resin 8, 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 raw water containing hardness components by the action of the weakly acidic cation exchange resin 7. More specifically, the water softening tank 3 is equipped with a weakly acidic cation exchange resin 7 having a hydrogen ion at the end of the functional group. The water softening tank 3 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 end of the functional group of the weakly acidic cation exchange resin 7 is a hydrogen ion, the weakly acidic cation exchange resin 7 can be regenerated using acidic electrolyzed water in the regeneration treatment described later. At this time, the cations, which are the hardness components taken in during the water softening treatment, are released from the weakly acidic cation exchange resin 7.

[0027] More specifically, in the first water softening tank 3a, raw water containing hardness components is passed through the flow path 20 and passes through the first weakly acidic cation exchange resin 7a filled inside, thereby softening the raw water containing hardness components, and the softened water is passed through the flow path 21 to the first neutralization tank 4a. However, the water softened by the first weakly acidic cation exchange resin 7a contains a large amount of hydrogen ions that have been exchanged with the hardness components and has become acidic water with a low pH.

[0028] On the other hand, in the second water softening tank 3b, neutral water neutralized in the flow path 22 passes through the second weakly acidic cation exchange resin 7b filled inside. As a result, the hardness components that could not be removed in the first water softening tank 3a are exchanged with the hydrogen ions possessed by the second weakly acidic cation exchange resin 7b. Therefore, the water flowing into the second water softening tank 3b is softened. However, the water softened by the second weakly acidic cation exchange resin 7b contains hydrogen ions that have been exchanged with the hardness components and thus is acidic water.

[0029] The neutralization tank 4 neutralizes the pH of the soft water (acidified soft water) containing hydrogen ions coming out of the water softening tank 3 by the action of the weakly basic anion exchange resin 8 and converts it into neutral soft water. More specifically, the neutralization tank 4 is provided with the weakly basic anion exchange resin 8 and adsorbs the hydrogen ions contained in the soft water from the water softening tank 3 together with anions (negative ions), so that the pH of the soft water rises and neutral soft water can be obtained. Also, the weakly basic anion exchange resin 8 can be regenerated using alkaline electrolyzed water in the regeneration process described later.

[0030] More specifically, in the first neutralization tank 4a, the softened water containing hydrogen ions passes through the flow path 21 and flows through the first weakly basic anion exchange resin 8a filled inside, thereby neutralizing the acidified water flowing out of the first water softening tank 3a and making it flow into the second water softening tank 3b as neutral water via the flow path 22. That is, the first neutralization tank 4a neutralizes the acidic water flowing out of the first water softening tank 3a, which is acidic water containing hydrogen ions released from the first weakly acidic cation exchange resin 7a, and sends the water flowing through the first neutralization tank 4a to the second water softening tank 3b as water that is easy to soften.

[0031] On the other hand, in the second neutralization tank 4b, soft water containing hydrogen ions is passed through the flow path 23 and circulated through the second weakly basic anion exchange resin 8b filled inside, thereby neutralizing the acidified soft water that has emerged from the second softening tank 3b and discharging it to the outside through the flow path 24 as neutral soft water. That is, the second neutralization tank 4b neutralizes the acidic water that has flowed out from the second softening tank 3b and contains hydrogen ions released from the second weakly acidic cation exchange resin 7b, and discharges soft water that can be used as domestic water.

[0032] Here, as shown in FIG. 1, by alternately providing the softening tank 3 and the neutralization tank 4, it is possible to improve the softening performance compared to the case where one weakly acidic cation exchange resin 7 and one weakly basic anion exchange resin 8 of the same volume are used. In addition, water containing a large amount of permanent hardness components (for example, sulfates such as calcium sulfate or chlorides such as magnesium chloride) is more likely to have a lower pH than water containing a large amount of temporary hardness components (for example, carbonates such as calcium carbonate) when softening. Therefore, when water containing a large amount of permanent hardness components is softened and neutralized once each, it causes a decrease in the softening performance of the water softening device 1. On the other hand, if the pH of the water decreased by softening in the first softening tank 3a is neutralized in the first neutralization tank 4a and then softened again by the second softening tank 3b, it is less affected by the quality of the raw water (the ratio of permanent hardness in the hardness components), and high softening performance can be obtained regardless of the quality of the raw water.

[0033] (Regeneration device) The regeneration device 6 is a device that regenerates the weakly acidic cation exchange resin 7 in the softening tank 3 and the weakly basic anion exchange resin 8 in the neutralization tank 4. Specifically, as described above, the regeneration device 6 includes an electrolytic cell 9, a treatment tank 11, and a water supply pump 12. And the regeneration device 6 has a first supply channel 31, a first recovery channel 35, a second supply channel 32, a second recovery channel 36, and a third recovery channel 37 respectively connected to the channels 23, 20, 21, 22, and 24 from the inlet 2 to the water intake 5. Also, the first bypass channel 33 connects the channels 21 and 22. Further, the second bypass channel 34 connects the channels 22 and 23. And each channel constitutes a circulation channel 30 (first circulation channel 30a, second circulation channel 30b, third circulation channel 30c) described later.

[0034] Here, the first supply channel 31 is a channel that supplies acidic electrolyzed water from the electrolytic cell 9 to the second softening tank 3b. The first bypass channel 33 is a channel that supplies the acidic electrolyzed water that has passed through the second softening tank 3b to the first softening tank 3a by bypassing the first neutralization tank 4a. The first recovery channel 35 is a channel that recovers the water containing hardness components that has passed through the first softening tank 3a to the treatment tank 11. The second supply channel 32 is a channel that supplies alkaline electrolyzed water from the electrolytic cell 9 to the first neutralization tank 4a. The second bypass channel 34 is a channel that supplies the alkaline electrolyzed water that has passed through the first neutralization tank 4a to the second neutralization tank 4b by bypassing the second softening tank 3b. The second recovery channel 36 is a channel that recovers the water that has passed through the first neutralization tank 4a to the treatment tank 11. The third recovery channel 37 is a channel that recovers the water that has passed through the second neutralization tank 4b to the treatment tank 11.

[0035] (Electrolytic cell) The electrolytic cell 9 uses the electrodes 10 provided inside to electrolyze the inflowing water (the water supplied from the treatment tank 11), thereby generating and discharging acidic electrolyzed water and alkaline electrolyzed water. More specifically, at the electrode that becomes the anode during electrolysis, hydrogen ions are generated by electrolysis, and acidic electrolyzed water is produced. Also, at the electrode that becomes the cathode during electrolysis, hydroxide ions are generated by electrolysis, and alkaline electrolyzed water is produced. Then, the electrolytic cell 9 supplies the acidic electrolyzed water to the second softening tank 3b via the first supply channel 31. Further, the electrolytic cell 9 supplies the alkaline electrolyzed water to the first neutralization tank 4a via the second supply channel 32. Although details will be described later, the acidic electrolyzed water generated by the electrolytic cell 9 is used for the regeneration of the first weakly acidic cation exchange resin 7a in the first softening tank 3a and the second weakly acidic cation exchange resin 7b in the second softening tank 3b. Also, the alkaline electrolyzed water generated by the electrolytic cell 9 is used for the regeneration of the first weakly basic anion exchange resin 8a in the first neutralization tank 4a and the second weakly basic anion exchange resin 8b in the second neutralization tank 4b. Note that the electrolytic cell 9 is configured to be able to control the energization state to the electrodes 10 by a control unit 15 described later.

[0036] (Treatment tank) The treatment tank 11 is a tank or container equipped with an air vent valve 14. The treatment tank 11 secures and stores the water that circulates in the circulation channel 30 (see FIGS. 2 and 3) when regenerating the weakly acidic cation exchange resin 7 and the weakly basic anion exchange resin 8. Also, the treatment tank 11 mixes the acidic electrolyzed water containing the hardness components that have flowed through the softening tank 3 and the alkaline electrolyzed water containing the anions that have flowed through the neutralization tank 4, and supplies the mixture to the electrolytic cell 9.

[0037] In treatment tank 11, the mixed hardness components and alkaline electrolyzed water react to generate reaction products (reaction products resulting from the hardness components contained in the raw water). More specifically, acidic electrolyzed water containing hardness components after regenerating the weakly acidic cation exchange resin 7 in the water softening tank 3 is passed through the first recovery flow path 35 into treatment tank 11. Also, alkaline electrolyzed water containing anions (e.g., chloride ions and hydroxide ions) after regenerating the weakly basic anion exchange resin 8 in the neutralization tank 4 is passed through the second recovery flow path 36 or the third recovery flow path 37 into treatment tank 11. Then, in treatment tank 11, 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 ions, reactions such as the formation of calcium carbonate or the formation of calcium hydroxide occur upon mixing with the alkaline electrolyzed water. And the reacted hardness components can be separated as reaction products by the filtration unit 13 described later, and treated water can be obtained.

[0038] Note that "the hardness components react" includes not only the case where all hardness components react, but also the state where components that do not react in treatment tank 11 or components that do not exceed the solubility product are included.

[0039] Then, the treated water obtained by the reaction of the hardness components in treatment tank 11 is passed into electrolysis tank 9, electrolyzed in electrolysis tank 9, and becomes acidic electrolyzed water and alkaline electrolyzed water, which are respectively supplied to water softening tank 3 and neutralization tank 4. And the acidic electrolyzed water and the alkaline electrolyzed water are reused in water softening tank 3 and neutralization tank 4 respectively, and then passed into treatment tank 11 again. Therefore, the acidic electrolyzed water and the alkaline electrolyzed water used for the regeneration of the weakly acidic cation exchange resin 7 and the regeneration of the weakly basic anion exchange resin 8 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 7 can be suppressed.

[0040] (Water supply pump) The water supply pump 12 is a device that circulates water in the circulation channel 30 (see FIGS. 2 and 3) during the regeneration process by the regeneration device 6. The water supply pump 12 is provided in the water supply channel 40 that communicatively connects between the treatment tank 11 and the electrolysis tank 9. Note that the water supply pump 12 is preferably arranged on the upstream side of the electrolysis tank 9 and on the downstream side of the treatment tank 11. Such an arrangement makes it easier to circulate water in the first circulation channel 30a, the second circulation channel 30b, and the third circulation channel 30c, which will be described later, with a single water supply pump 12. Further, the water supply pump 12 is communicatively connected to a control unit 15, which will be described later, by wireless or wired means.

[0041] (Filter section) The filter section 13 is provided in the front stage of the water supply channel 40 that connects from the treatment tank 11 to the electrolysis tank 9. And the filter section 13 separates the precipitate contained in the water that has flowed through the treatment tank 11. The precipitate is a reaction product generated by the reaction between the acidic electrolyzed water containing the hardness component that has flowed through the water softening tank 3 and the alkaline electrolyzed water containing the anion that has flowed through the neutralization tank 4.

[0042] By separating the precipitate in the filter section 13, the treated water flowing through the water supply channel 40 has a reduced hardness component compared to the case of tap water or when the filter section 13 is not provided. That is, by separating the precipitate in the filter section 13, the hardness of the treated water decreases, so the hardness of the acidic electrolyzed water generated in the electrolysis tank 9 also decreases. Therefore, the hardness component flowing into the water softening tank 3 can be reduced, and the decrease in the regeneration efficiency of the weakly acidic cation exchange resin 7 can be suppressed.

[0043] The form of the filter section 13 is not limited as long as it can separate the reaction product with the hardness component in the treatment tank 11. For example, forms using a cartridge type filter, a filter layer using granular filter media, a cyclone type solid-liquid separator, a hollow fiber membrane, etc. can be mentioned. Further, the filter section 13 may be additionally provided in the second supply channel 32 that is the subsequent stage of the electrolysis tank 9 as necessary.

[0044] (On-off valve) A plurality of on-off valves (on-off valves 41 to 45, on-off valves 51 to 57, on-off valve 61, and on-off valve 62) are respectively provided in each flow path and can be switched between an "open" state and a "closed" state in each flow path. Also, each of the plurality of on-off valves (on-off valves 41 to 45, on-off valves 51 to 57, on-off valve 61, and on-off valve 62) is communicably connected to a control unit 15 described later by wireless or wired means.

[0045] (Control Unit) The control unit 15 controls a softening treatment for softening raw water containing hardness components. Also, the control unit 15 controls the regeneration treatment of the weakly acidic cation exchange resin 7 in the softening tank 3 and the weakly basic anion exchange resin 8 in the neutralization tank 4. Further, the control unit 15 controls the switching of the softening treatment, regeneration treatment, and drainage treatment of the softening device 1. At this time, the control unit 15 controls the operations of the electrodes 10, water supply pump 12, on-off valves 41 to 45, on-off valves 51 to 57, on-off valve 61, and on-off valve 62, switches the softening treatment, regeneration treatment, and drainage treatment, and causes each treatment to be executed.

[0046] (Flow Path) Next, with reference to FIGS. 2 and 3, the circulation flow path 30 formed during the regeneration treatment of the softening device 1 will be described. FIG. 2 is a configuration diagram showing the circulation flow path 30A during the first regeneration treatment of the softening device 1. FIG. 3 is a configuration diagram showing the circulation flow path 30B during the second regeneration treatment of the softening device 1. Although details will be described later, the first regeneration treatment is a treatment for regenerating the first softening tank 3a, the first neutralization tank 4a, and the second softening tank 3b, excluding the second neutralization tank 4b, which is located at the last stage in the flow path of the softening treatment. Also, the second regeneration treatment is a treatment for regenerating the first softening tank 3a, the first neutralization tank 4a, the second softening tank 3b, and the second neutralization tank 4b.

[0047] Although the description is repetitive, as shown in FIG. 2, in the water softening device 1, the electrolytic cell 9 and the treatment tank 11 that constitute the regeneration device 6 are communicatively connected by a water supply channel 40. Further, the electrolytic cell 9 and the treatment tank 11 are connected to the channels 23, 20, 21, 22, and 24 from the inlet 2 to the water intake 5 by a first supply channel 31, a first recovery channel 35, a second supply channel 32, a second recovery channel 36, and a third recovery channel 37, respectively. Further, the channels 21 and 22 are bypass-connected by a first bypass channel 33. Also, the channels 22 and 23 are bypass-connected by a second bypass channel 34. And each channel constitutes a circulation channel 30 (a first circulation channel 30a, a second circulation channel 30b, and a third circulation channel 37) described later.

[0048] The first supply channel 31 is a channel for supplying acidic electrolyzed water from the electrolytic cell 9 to the second water softening tank 3b, and an on-off valve 54 is installed in the channel. That is, the water softening device 1 includes a first supply channel 31 that can draw acidic electrolyzed water from the electrolytic cell 9 and supply it to the downstream side of the second water softening tank 3b.

[0049] The first bypass channel 33 is a channel for supplying acidic electrolyzed water from the second water softening tank 3b to the first water softening tank 3a, and an on-off valve 56 is installed in the channel. That is, the water softening device 1 includes a first bypass channel 33 that can supply the acidic electrolyzed water that has flowed through the second water softening tank 3b to the downstream side of the first water softening tank 3a. By providing the first bypass channel 33, the regeneration process can proceed without flowing the acidic electrolyzed water through the first neutralization tank 4a existing between the first water softening tank 3a and the second water softening tank 3b.

[0050] The first recovery channel 35 is a channel for recovering the acidic electrolyzed water containing the hardness component that has passed through the first water softening tank 3a to the treatment tank 11, and an on-off valve 51 is installed in the channel. That is, the water softening device 1 includes a first recovery channel 35 that can connect the upstream side of the treatment tank 11 to the upstream side of the first water softening tank 3a.

[0051] The second supply channel 32 is a channel for supplying alkaline electrolyzed water from the electrolytic cell 9 to the first neutralization tank 4a, and an on-off valve 52 is installed in the channel. That is, the water softening device 1 includes a second supply channel 32 that can draw out alkaline electrolyzed water from the electrolytic cell 9 and supply it to the upstream side of the first neutralization tank 4a.

[0052] The second recovery channel 36 is a channel for recovering the alkaline electrolyzed water that has passed through the first neutralization tank 4a to the treatment tank 11, and an on-off valve 53 is installed in the channel. That is, the water softening device 1 includes a second recovery channel 36 that can connect the upstream side of the treatment tank 11 to the downstream side of the first neutralization tank 4a.

[0053] The second bypass channel 34 is a channel for supplying alkaline electrolyzed water from the first neutralization tank 4a to the second neutralization tank 4b, and an on-off valve 57 is installed in the channel. That is, the water softening device 1 includes a second bypass channel 34 that can supply the alkaline electrolyzed water that has flowed through the first neutralization tank 4a to the upstream side of the second neutralization tank 4b. By providing the second bypass channel 34, the regeneration process can proceed without flowing the alkaline electrolyzed water through the second water softening tank 3b existing between the first neutralization tank 4a and the second neutralization tank 4b.

[0054] The third recovery channel 37 is a channel for recovering the alkaline electrolyzed water that has passed through the second neutralization tank 4b to the treatment tank 11, and an on-off valve 55 is installed in the channel. That is, the water softening device 1 includes a third recovery channel 37 that can connect the upstream side of the treatment tank 11 to the downstream side of the second neutralization tank 4b.

[0055] The circulation channel 30 includes a circulation channel 30A (see Figure 2) formed during the first regeneration process and a circulation channel 30B (see Figure 3) formed during the second regeneration process. In the following, regarding the circulation channel 30A and the circulation channel 30B, when there is no need to particularly distinguish between the two, they will be described as the circulation channel 30.

[0056] As shown in FIG. 2, the circulation flow path 30A includes a first circulation flow path 30a through which the water sent out from the treatment tank 11 by the water supply pump 12 flows through the second water softening tank 3b and the first water softening tank 3a, and a second circulation flow path 30b through which the water sent out from the treatment tank 11 by the water supply pump 12 flows through the first neutralization tank 4a without flowing through the second neutralization tank 4b.

[0057] As shown by the white arrow in FIG. 2, the first circulation flow path 30a is a flow path through which the water sent out from the treatment tank 11 by the water supply pump 12 flows through the electrolytic cell 9, the second water softening tank 3b, and the first water softening tank 3a and then returns to the treatment tank 11 for circulation. More specifically, the first circulation flow path 30a is a flow path through which the water sent out from the treatment tank 11 by the water supply pump 12 circulates in the order of the water supply flow path 40, the electrolytic cell 9, the first supply flow path 31, the on-off valve 54, the second water softening tank 3b, the first bypass flow path 33, the on-off valve 56, the first water softening tank 3a, the first recovery flow path 35, the on-off valve 51, and the treatment tank 11.

[0058] As shown by the black arrow in FIG. 2, the second circulation flow path 30b is a flow path through which the water sent out from the treatment tank 11 by the water supply pump 12 flows through the electrolytic cell 9 and the first neutralization tank 4a and then returns to the treatment tank 11 for circulation. More specifically, the second circulation flow path 30b is a flow path through which the water sent out from the treatment tank 11 by the water supply pump 12 circulates in the order of the water supply flow path 40, the electrolytic cell 9, the second supply flow path 32, the on-off valve 52, the first neutralization tank 4a, the second recovery flow path 36, the on-off valve 53, and the treatment tank 11.

[0059] Next, as shown in FIG. 3, the circulation flow path 30B includes a first circulation flow path 30a through which the water sent out from the treatment tank 11 by the water supply pump 12 flows through the second water softening tank 3b and the first water softening tank 3a, and a third circulation flow path 30c through which the water sent out from the treatment tank 11 by the water supply pump 12 flows through the first neutralization tank 4a and the second neutralization tank 4b.

[0060] As shown by the white arrows in Fig. 3, the first circulation flow path 30a is a flow path through which the water sent out from the treatment tank 11 by the water supply pump 12 circulates through the electrolytic cell 9, the second softening tank 3b, and the first softening tank 3a and then returns to the treatment tank 11. Since the first circulation flow path 30a of the circulation flow path 30B is the same as the first circulation flow path 30a of the circulation flow path 30A, the details are omitted.

[0061] As shown by the shaded arrows in Fig. 3, the third circulation flow path 30c is a flow path through which the water sent out from the treatment tank 11 by the water supply pump 12 circulates through the electrolytic cell 9, the first neutralization tank 4a, and the second neutralization tank 4b and then returns to the treatment tank 11. More specifically, the third circulation flow path 30c is a flow path through which the water sent out from the treatment tank 11 by the water supply pump 12 circulates in the order of the water supply flow path 40, the electrolytic cell 9, the second supply flow path 32, the on-off valve 52, the first neutralization tank 4a, the second bypass flow path 34, the on-off valve 57, the second neutralization tank 4b, the third recovery flow path 37, the on-off valve 55, and the treatment tank 11.

[0062] Here, the states of the respective flow paths for circulating water in the circulation flow path 30 will be described.

[0063] An on-off valve 44 is installed in the flow path 23 on the downstream side of the first supply flow path 31 and on the upstream side of the second bypass flow path 34. By closing the on-off valve 44 and opening the on-off valve 54, the first supply flow path 31 is communicatively connected to the downstream side of the second softening tank 3b. Thereby, the acidic electrolyzed water from the electrolytic cell 9 can be supplied to the second softening tank 3b.

[0064] An on-off valve 42 is installed in the flow path 21 on the downstream side of the first bypass flow path 33 and on the upstream side of the second supply flow path 32. Also, an on-off valve 43 is installed in the flow path 22 on the downstream side of the second bypass flow path 34 and the second recovery flow path 36 and on the upstream side of the first bypass flow path 33. By closing the on-off valve 42 and the on-off valve 43 and opening the on-off valve 56, the first bypass flow path 33 is communicatively connected to the upstream side of the second softening tank 3b and the downstream side of the first softening tank 3a. Thereby, the acidic electrolyzed water that has passed through the second softening tank 3b can be supplied to the first softening tank 3a.

[0065] An on-off valve 41 is installed in the flow path 20 on the downstream side of the inlet 2 and on the upstream side of the first recovery flow path 35. By closing the on-off valve 41 and the on-off valve 42 and opening the on-off valve 51, the first recovery flow path 35 is communicatively connected to the upstream side of the first water softening tank 3a. As a result, in the water softening device 1, the water (acidic electrolyzed water containing hardness components) that has flowed through the first water softening tank 3a and the second water softening tank 3b can be recovered to the treatment tank 11.

[0066] Also, by closing the on-off valve 42 and opening the on-off valve 52, the second supply flow path 32 is communicatively connected to the upstream side of the first neutralization tank 4a. As a result, the alkaline electrolyzed water from the electrolytic cell 9 can be supplied to the first neutralization tank 4a.

[0067] Also, by closing the on-off valve 43 and the on-off valve 57 and opening the on-off valve 53, the second recovery flow path 36 is communicatively connected to the downstream side of the first neutralization tank 4a. As a result, in the water softening device 1, the water (alkaline electrolyzed water containing anions) that has flowed through the first neutralization tank 4a can be recovered to the treatment tank 11.

[0068] Also, by closing the on-off valve 42, the on-off valve 43, and the on-off valve 44 and opening the on-off valve 57, the second bypass flow path 34 is communicatively connected to the downstream side of the first neutralization tank 4a and on the upstream side of the second neutralization tank 4b. As a result, the alkaline electrolyzed water that has flowed through the first neutralization tank 4a can be supplied to the second neutralization tank 4b.

[0069] Also, by closing the on-off valve 44 and the on-off valve 45 and opening the on-off valve 55, the third recovery flow path 37 is communicatively connected to the downstream side of the second neutralization tank 4b. As a result, in the water softening device 1, the water (alkaline electrolyzed water containing anions) that has flowed through the first neutralization tank 4a and the second neutralization tank 4b can be recovered to the treatment tank 11.

[0070] In addition, a shut-off valve 61 is installed in the water supply passage 40 at the downstream side of the treatment tank 11 (at the position between the treatment tank 11 and the water supply pump 12). By closing the shut-off valve 61, water can be stored in the treatment tank 11. On the other hand, by opening the shut-off valve 61, water can be supplied to the water supply passage 40.

[0071] Also, by closing the shut-off valve 41 and the shut-off valve 45, the circulation of water through the circulation passage 30 can be started. On the other hand, by opening the shut-off valve 41 and the shut-off valve 45, the circulation of water through the circulation passage 30 can be stopped.

[0072] (Softening treatment, regeneration treatment, and drainage treatment) Next, with reference to FIG. 4, the softening treatment, regeneration treatment, and drainage treatment of the water softening apparatus 1 starting from the regeneration treatment will be described. FIG. 4 is a diagram showing the state of the water softening apparatus 1 during operation.

[0073] In the softening treatment, regeneration treatment, and drainage treatment, as shown in FIG. 4, the control unit 15 controls the shut-off valves 41 to 45, shut-off valves 51 to 57, shut-off valve 61, shut-off valve 62, the electrodes 10 of the electrolytic cell 9, and the water supply pump 12 to switch to their respective flow states. The control unit 15 has a computer system having a processor and a memory. Then, by the processor executing the program stored in the memory, the computer system functions as the control unit. The program executed by the processor is assumed to be pre-recorded in the memory of the computer system here, but it may be recorded and provided on a non-temporary recording medium such as a memory card, or may be provided through an electrical communication line such as the Internet.

[0074] Here, "ON" in FIG. 4 indicates the state where the corresponding shut-off valve is "open", the state where the electrode 10 is energized, and the state where the water supply pump 12 is operating, respectively. The blank spaces indicate the state where the corresponding shut-off valve is "closed", the state where the electrode 10 is not energized, and the state where the water supply pump 12 is stopped, respectively.

[0075] (Regeneration treatment) In the water softening device 1, in the water softening tank 3 filled with the weakly acidic cation exchange resin 7, if the use continues, the cation exchange capacity decreases or disappears. 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 be carried out. When it reaches such a state, the hardness components will be contained in the treated water. Therefore, in the water softening device 1, it is necessary to perform the regeneration treatment of the water softening tank 3 and the neutralization tank 4 by the regeneration device 6.

[0076] In the present embodiment, the regeneration treatment includes a second regeneration treatment executed during a predetermined set period and a first regeneration treatment executed when predetermined conditions are satisfied outside the set period.

[0077] The second regeneration treatment is a treatment for regenerating the first water softening tank 3a, the first neutralization tank 4a, the second water softening tank 3b, and the second neutralization tank 4b. The second regeneration treatment is executed when it reaches the set period which is a predetermined time zone. And the second regeneration treatment is executed until the regeneration treatment of the water softening tank 3 and the neutralization tank 4 by the regeneration device 6 is completed. And after the end of the second regeneration treatment, after performing the drainage treatment of draining the water in the circulation channel 30B, it shifts to the water softening treatment. Note that the second regeneration treatment corresponds to the treatment of "regenerating the water softening tank and the neutralization tank including the last-stage neutralization tank" in the claims.

[0078] Here, the set period is specified and set, for example, once a day (24 hours), to identify the time zone when the regeneration treatment is possible. More specifically, the control unit 15 may set the time zone with a low frequency of water softening treatment within a day by referring to the usage history of the water softening device 1, or the user may set an appropriate time zone (for example, at night) in advance.

[0079] The first regeneration process is a process of regenerating the first water softening tank 3a, the first neutralization tank 4a, and the second water softening tank 3b, excluding the second neutralization tank 4b located at the last stage in the flow path of the water softening process. The first regeneration process is executed when, outside the set period described above (the time period during which the second regeneration process is not being executed), the water softening process is not being performed, that is, when the inflow of municipal water from the inlet 2 is not occurring. And the first regeneration process is executed until the user uses soft water, that is, until the inflow of municipal water from the inlet 2 occurs. And when the user starts using soft water, the first regeneration process immediately ends and the process shifts to the water softening process. In other words, in the first regeneration process, unlike the second regeneration process, without performing a drainage process of draining the water in the circulation flow path 30B, it immediately shifts to the water softening process.

[0080] In the first regeneration process, since alkaline electrolyzed water is not circulated to the last-stage second neutralization tank 4b, even when immediately shifting to the water softening process after the end of the first regeneration process, it is possible to obtain the same neutral soft water as in the normal water softening process, rather than water (soft water) containing alkaline electrolyzed water from the water intake 5. On the other hand, the water (soft water) containing acidic electrolyzed water remaining in the second water softening tank 3b flows through the second neutralization tank 4b located downstream, and thus is treated by the second neutralization tank 4b to become the same neutral soft water as in the normal water softening process. The same applies to the respective electrolyzed waters remaining in the first water softening tank 3a and the first neutralization tank 4a.

[0081] In the first regeneration process, when the regeneration process of the water softening tank 3 and the neutralization tank 4 (excluding the second neutralization tank 4b) by the regeneration device 6 is completed, after performing a drainage process of draining the water in the circulation flow path 30B, the process shifts to the water softening process.

[0082] Below, each operation of the regeneration process (the first regeneration process and the second regeneration process), the drainage process, and the water softening process in the water softening device 1 will be described in detail.

[0083] (Operation of the First Regeneration Process) Regarding the operation during the first regeneration process by the regeneration device 6 of the water softening device 1, it will be described in order with reference to the columns of "During water injection" and "During regeneration (first)" in Fig. 4.

[0084] First, as shown in Fig. 4, during water injection, the on-off valve 41 and the on-off valve 51 are opened. Thereby, the water softening device 1 introduces raw water from the inlet 2 to the treatment tank 11 through the first recovery flow path 35 by the pressure of the city water. At this time, the on-off valves 42 to 45, the on-off valves 52 to 57, the on-off valve 61, and the on-off valve 62 are closed. By storing a predetermined amount of water in the treatment tank 11 according to the capacity of the water softening device 1, the regeneration device 6 can secure the amount of water during regeneration.

[0085] Next, during regeneration (first), when the on-off valves 41 to 45, the on-off valve 55, the on-off valve 57, and the on-off valve 62 are closed and the on-off valves 51 to 54, the on-off valve 56, and the on-off valve 61 are opened, as shown in Fig. 2, the circulation flow path 30A (the first circulation flow path 30a and the second circulation flow path 30b) is formed.

[0086] Then, when the electrode 10 of the electrolytic cell 9 and the water pump 12 are operated, the water stored in the treatment tank 11 circulates through each of the first circulation flow path 30a and the second circulation flow path 30b.

[0087] The acidic electrolyzed water generated in the electrolytic cell 9 flows through the first circulation channel 30a to regenerate the softening tank 3. More specifically, the acidic electrolyzed water generated in the electrolytic cell 9 flows through the first supply channel 31 and is sent into the second softening tank 3b, where it flows through the internal second weakly acidic cation exchange resin 7b. Then, the acidic electrolyzed water that has flowed through the second softening tank 3b flows through the first bypass channel 33 and is sent into the first softening tank 3a, where it flows through the internal first weakly acidic cation exchange resin 7a. That is, by passing the acidic electrolyzed water through the first weakly acidic cation exchange resin 7a and the second weakly acidic cation exchange resin 7b, the cations (hardness components) adsorbed on the first weakly acidic cation exchange resin 7a and the second weakly acidic cation exchange resin 7b undergo an ion exchange reaction with the hydrogen ions contained in the acidic electrolyzed water. As a result, the first weakly acidic cation exchange resin 7a and the second weakly acidic cation exchange resin 7b are regenerated. Thereafter, the acidic electrolyzed water that has flowed through the first weakly acidic cation exchange resin 7a contains cations and flows into the first recovery channel 35. That is, the acidic electrolyzed water containing cations that has flowed through the first weakly acidic cation exchange resin 7a and the second weakly acidic cation exchange resin 7b is recovered into the treatment tank 11 via the first bypass channel 33 and the first recovery channel 35.

[0088] In this way, the first circulation channel 30a is configured to allow the acidic electrolyzed water to flow from the downstream side of the second softening tank 3b, which is located most downstream from the raw water inlet 2 and has the second weakly acidic cation exchange resin 7b with a small adsorption amount of hardness components, and to flow into the downstream side of the first softening tank 3a, which is located upstream and has the first weakly acidic cation exchange resin 7a with a larger adsorption amount of hardness components than the second weakly acidic cation exchange resin 7b.

[0089] On the one hand, the alkaline electrolyzed water generated in the electrolytic cell 9 flows through the second circulation channel 30b to regenerate the neutralization tank 4. More specifically, the alkaline electrolyzed water generated in the electrolytic cell 9 is sent into the first neutralization tank 4a through the second supply channel 32 and flows through the internal first weakly basic anion exchange resin 8a. That is, by passing the alkaline electrolyzed water through the first weakly basic anion exchange resin 8a, the anions adsorbed on the first weakly basic anion exchange resin 8a undergo an ion exchange reaction with the hydroxide ions contained in the alkaline electrolyzed water. As a result, the first weakly basic anion exchange resin 8a is regenerated. Thereafter, the alkaline electrolyzed water that has flowed through the first weakly basic anion exchange resin 8a contains anions and flows into the second recovery channel 36. That is, the alkaline electrolyzed water containing anions that has flowed through the first weakly basic anion exchange resin 8a is recovered into the treatment tank 11 through the second recovery channel 36.

[0090] And in the treatment tank 11, the acidic electrolyzed water containing cations recovered from the first water softening tank 3a and the second water softening tank 3b is mixed and neutralized with the alkaline electrolyzed water containing anions recovered from the first neutralization tank 4a.

[0091] At this time, by mixing the acidic electrolyzed water containing cations (hardness components) and the alkaline electrolyzed water containing anions, the hardness components react with the hydroxide ions contained in the alkaline electrolyzed water to form precipitates. For example, when the hardness component in the acidic electrolyzed water is calcium ion, calcium hydroxide is generated by the alkaline electrolyzed water, or it combines with carbonate ions existing in the water to form calcium carbonate.

[0092] Thereafter, when the treated water treated in the treatment tank 11 flows through the filtration unit 13, the reaction products are removed, and the water is passed through the water supply channel 40 and sent back to the electrolytic cell 9 again. And the passed water is electrolyzed again in the electrolytic cell 9.

[0093] Here, the electrolyzed water (acidic electrolyzed water, alkaline electrolyzed water) electrolyzed again in the electrolytic cell 9 is used for the regeneration of the weakly acidic cation exchange resin 7 and the regeneration of the weakly basic anion exchange resin 8, respectively. That is, the acidic electrolyzed water used for the regeneration of the weakly acidic cation exchange resin 7 is reused as electrolyzed water again from the state where the hardness components have changed into reaction products and been filtered in the treatment tank 11. Moreover, the hardness components contained in the water are reduced compared with the case of city water (raw water containing hardness components) supplied from the outside or the case without the treatment tank 11. Also, when electrolyzed in the electrolytic cell 9, the hardness components, which are cations, move to the alkaline electrolyzed water side, so the hardness of the acidic electrolyzed water decreases, and a decrease in the regeneration efficiency of the weakly acidic cation exchange resin 7 can be suppressed. Furthermore, inside the electrolytic cell 9 and the water softening tank 3, adhesion of deposits caused by hardness components can be suppressed.

[0094] After that, in the water softening device 1, when the user starts using soft water, the operations of the electrode 10 and the water supply pump 12 are stopped to end the first regeneration process. Then, by closing the on-off valves 51 to 57 and the on-off valves 61 to 62 and opening the on-off valves 41 to 45, the process immediately shifts to the water softening process. In addition, in the first regeneration process, when the regeneration process of the water softening tank 3 and the neutralization tank 4 (excluding the second neutralization tank 4b) by the regeneration device 6 is completed, after performing the drainage process of draining the water in the circulation flow path 30B, the process may shift to the water softening process.

[0095] (Operation of the second regeneration process) The operation during the second regeneration process by the regeneration device 6 of the water softening device 1 will be described in order with reference to the columns of "When water is injected" and "During regeneration (second)" in FIG. 4.

[0096] First, as shown in FIG. 4, when water is injected, the on-off valves 41 and 51 are opened. Thereby, the water softening device 1 introduces raw water from the inlet 2 to the treatment tank 11 through the first recovery flow path 35 by the pressure of the city water. At this time, the on-off valves 42 to 45, the on-off valves 52 to 57, the on-off valve 61, and the on-off valve 62 are closed. By storing a predetermined amount of water in the treatment tank 11 according to the capacity of the water softening device 1, the regeneration device 6 can ensure the amount of water during regeneration.

[0097] Next, during regeneration (second), when the on-off valves 41 to 45, the on-off valve 53, and the on-off valve 62 are closed and the on-off valves 51, 52, 54 to 57, and the on-off valve 61 are opened, as shown in FIG. 3, the circulation flow path 30B (the first circulation flow path 30a and the third circulation flow path 30c) is formed.

[0098] Then, when the electrode 10 of the electrolytic cell 9 and the water pump 12 are operated, the water stored in the treatment tank 11 circulates through each of the first circulation flow path 30a and the third circulation flow path 30c.

[0099] The acidic electrolyzed water generated in the electrolytic cell 9 flows through the first circulation flow path 30a to regenerate the water softening tank 3. The details of the first circulation flow path 30a are the same as those described in the operation of the first regeneration process, so they are omitted.

[0100] On the one hand, the alkaline electrolyzed water generated in the electrolytic cell 9 flows through the third circulation channel 30c to regenerate the neutralization tank 4. More specifically, the alkaline electrolyzed water generated in the electrolytic cell 9 is sent into the first neutralization tank 4a through the second supply channel 32 and flows through the internal first weakly basic anion exchange resin 8a. Then, the alkaline electrolyzed water that has flowed through the first neutralization tank 4a flows through the second bypass channel 34, is sent into the second neutralization tank 4b, and flows through the internal second weakly basic anion exchange resin 8b. That is, by passing the alkaline electrolyzed water through the first weakly basic anion exchange resin 8a and the second weakly basic anion exchange resin 8b, the anions adsorbed on the first weakly basic anion exchange resin 8a and the second weakly basic anion exchange resin 8b undergo an ion exchange reaction with the hydroxide ions contained in the alkaline electrolyzed water. Thereby, the first weakly basic anion exchange resin 8a and the second weakly basic anion exchange resin 8b are regenerated. After that, the alkaline electrolyzed water that has flowed through the second weakly basic anion exchange resin 8b contains anions and flows into the third recovery channel 37. That is, the alkaline electrolyzed water containing anions that has flowed through the first weakly basic anion exchange resin 8a and the second weakly basic anion exchange resin 8b is recovered into the treatment tank 11 through the second bypass channel 34 and the third recovery channel 37.

[0101] And in the treatment tank 11, the acidic electrolyzed water containing cations recovered from the first water softening tank 3a and the second water softening tank 3b is mixed and neutralized with the alkaline electrolyzed water containing anions recovered from the first neutralization tank 4a and the second neutralization tank 4b.

[0102] After that, in the water softening device 1, when the regeneration treatment of the water softening tank 3 and the neutralization tank 4 by the regeneration device 6 is completed, the operations of the electrode 10 and the water supply pump 12 are stopped to end the second regeneration treatment. Then, by opening the on-off valve 53 and the on-off valve 62, the process shifts to the drainage treatment. Note that the completion of the regeneration treatment may be, for example, after a certain time (e.g., 6 hours) from the start of the regeneration treatment (when the operation of the electrode 10 starts), or it may be determined by detecting the pH of the acidic electrolyzed water flowing through the first circulation channel 30a.

[0103] (Operation of drainage treatment) In the water softening device 1, when the second regeneration treatment is completed, the process shifts to the drainage treatment. Here, the drainage treatment is a process of draining the acidic electrolyzed water and alkaline electrolyzed water remaining in the circulation channel 30A. Note that the same treatment may be performed when draining the acidic electrolyzed water and alkaline electrolyzed water remaining in the circulation channel 30B.

[0104] Next, the operation during the drainage treatment by the water softening device 1 will be described with reference to the "During Drainage" column in FIG. 4.

[0105] In the water softening device 1, as shown in FIG. 4, during the drainage treatment (during drainage), the on-off valves 41 to 45 are closed, and the on-off valves 51 to 57 and the on-off valve 61 are opened.

[0106] Thereby, the acidic electrolyzed water remaining in the first circulation channel 30a and the alkaline electrolyzed water remaining in the second circulation channel 30b can flow into the treatment tank 11.

[0107] When the on-off valve 62 is opened, due to the action of the air vent valve 14, the electrolyzed water in the treatment tank 11 can be discharged outside the device.

[0108] By performing the drainage treatment, when the water softening treatment is restarted after the second regeneration treatment, it is possible to suppress the acidic electrolyzed water and alkaline electrolyzed water remaining in the circulation channel 30A from mixing with the raw water flowing in from the inlet 2 and being discharged from the water intake 5. That is, even after the start of the water softening treatment, it is possible to suppress the discharge of water containing alkaline electrolyzed water from the water intake 5.

[0109] Then, in the water softening device 1, when the drainage treatment is completed, the on-off valves 51 to 57, the on-off valve 61, and the on-off valve 62 are closed, and the on-off valves 41 to 45 are opened to shift to the water softening treatment. Note that the end of the drainage treatment may be set when a certain time (for example, 1 minute) has elapsed since the start of the drainage treatment.

[0110] (Operation of water softening treatment) When the wastewater treatment after the second regeneration treatment is completed, the water softening device 1 shifts to the water softening treatment. Also, when the user starts using softened water during the first regeneration treatment, the water softening device 1 shifts to the water softening treatment.

[0111] Next, the operation during the water softening treatment by the water softening device 1 will be described with reference to the "During Water Softening" column in FIG. 4.

[0112] In the water softening device 1, as shown in FIG. 4, during the water softening treatment (during water softening), with the on-off valves 41 to 44 open, the on-off valve 45 provided at the water intake 5 is opened. As a result, city water (raw water containing hardness components) from the outside flows through the water softening tank 3 and the neutralization tank 4, so that the water softening device 1 can take out the softened water (neutral softened water) from the water intake 5. At this time, all of the on-off valves 51 to 57, the on-off valve 61, and the on-off valve 62 are in a closed state. Also, the operation of the electrodes 10 of the electrolytic cell 9 and the water pump 12 is stopped.

[0113] Specifically, as shown in FIG. 1, in the water softening treatment, due to the pressure of the municipal water, the raw water to be supplied flows from the inlet 2 through the flow path 20 and is supplied to the first water softening tank 3a. Then, the raw water supplied to the first water softening tank 3a flows through the first weakly acidic cation exchange resin 7a provided in the first water softening tank 3a. At this time, the cations, which are hardness components in the raw water, are adsorbed by the action of the first weakly acidic cation exchange resin 7a, and hydrogen ions are released (ion exchange occurs). And since the cations are removed from the raw water, the raw water is softened. The softened water contains a large amount of hydrogen ions that have been exchanged with the hardness components and thus becomes acidic water with a low pH. The softened water further flows through the flow path 21 and flows into the first neutralization tank 4a. In the first neutralization tank 4a, the hydrogen ions contained in the softened water are adsorbed by the action of the first weakly basic anion exchange resin 8a. That is, since the hydrogen ions are removed from the water softened by the first water softening tank 3a, the decreased pH rises and is neutralized. Therefore, compared with the case where the water softened in the first water softening tank 3a is directly softened in the second water softening tank 3b, the water softening treatment in the second water softening tank 3b proceeds more easily. The water neutralized by the first neutralization tank 4a further flows through the flow path 22 and flows into the second water softening tank 3b. In the second water softening tank 3b, the cations, which are hardness components, are adsorbed by the action of the second weakly acidic cation exchange resin 7b, and hydrogen ions are released. That is, the water flowing into the second water softening tank 3b is softened and becomes soft water. The soft water containing hydrogen ions flows through the flow path 23 and flows into the second neutralization tank 4b. In the second neutralization tank 4b, the hydrogen ions contained in the flowing-in soft water are adsorbed by the action of the second weakly basic anion exchange resin 8b. That is, since the hydrogen ions are removed from the soft water, the decreased pH rises, and the softened neutral water that can be used as domestic water is obtained. The softened neutral water can be taken out from the water intake 5 through the flow path 24.

[0114] And in the water softening device 1, the regeneration treatment is executed when the time zone specified by the control unit 15 is reached or when the water softening treatment exceeds a certain time.

[0115] In this way, in the water softening device 1, the operations of water softening treatment, regeneration treatment, and wastewater treatment are repeatedly executed.

[0116] As described above, according to the water softening device 1 according to the first embodiment, the following effects can be enjoyed.

[0117] (1) The water softening device 1 includes a plurality of water softening tanks 3 (first water softening tank 3a, second water softening tank 3b) that soften raw water containing hardness components with a weakly acidic cation exchange resin 7, a plurality of neutralization tanks 4 (first neutralization tank 4a, second neutralization tank 4b) that neutralize the pH of the softened water flowing through the water softening tank 3 with a weakly basic anion exchange resin 8, acidic electrolyzed water for regenerating the weakly acidic cation exchange resin 7 in the water softening tank 3, and an electrolytic cell 9 that generates alkaline electrolyzed water for regenerating the weakly basic anion exchange resin 8 in the neutralization tank 4. In the water softening treatment, the water softening tank 3 and the neutralization tank 4 are alternately connected in communication to perform the softening of the raw water. In the regeneration treatment, a first regeneration treatment for regenerating the neutralization tank 4 (first neutralization tank 4a) excluding the water softening tank 3 (first water softening tank 3a and second water softening tank 3b) and the last-stage neutralization tank 4 (second neutralization tank 4b), and a second regeneration treatment for regenerating the neutralization tank 4 (first neutralization tank 4a and second neutralization tank 4b) including the water softening tank 3 (first water softening tank 3a and second water softening tank 3b) and the last-stage neutralization tank 4 (first neutralization tank 4a) are performed to regenerate the water softening tank 3 and the neutralization tank 4.

[0118] According to such a configuration, by switching from the second regeneration treatment to the first regeneration treatment, the regeneration treatment is performed with the last-stage neutralization tank 4 (second neutralization tank 4b) excluded. And in the first regeneration treatment, since alkaline electrolyzed water is not circulated to the last-stage neutralization tank 4 (second neutralization tank 4b), even when immediately shifting to the water softening treatment after the end of the first regeneration treatment, it is possible to obtain neutral softened water instead of softened water containing alkaline electrolyzed water from the water intake 5. That is, the water softening device 1 can quickly shift from the regeneration treatment to the water softening treatment and perform water softening efficiently.

[0119] (2) In the water softening device 1, the second regeneration process is executed when the set period set based on the usage status of the device is reached, and the first regeneration process is executed when the water softening process is not being executed outside the set period. As a result, outside the set period, the first regeneration process is executed in a state where the water softening process is not being executed, so it is possible to shorten the processing time of the second regeneration process executed during the set period. That is, the water softening device 1 can quickly shift from the regeneration process to the water softening process and perform water softening efficiently.

[0120] (3) In the water softening device, when the second regeneration process ends, after executing the drainage process of discharging the acidic electrolyzed water used for the regeneration of the water softening tank 3 and the alkaline electrolyzed water used for the regeneration of the neutralization tank 4 to the outside, the water softening process is executed. Also, when the first regeneration process ends, the water softening process is executed without performing the drainage process. As a result, in the second regeneration process, the influence of the alkaline electrolyzed water remaining in the last-stage neutralization tank 4 (second neutralization tank 4b) can be reliably suppressed, and in the first regeneration process, the influence of the alkaline electrolyzed water remaining in the last-stage neutralization tank 4 (second neutralization tank 4b) can be suppressed while quickly shifting to the water softening process.

[0121] (4) The water softening device 1 includes a plurality of water softening tanks 3 and a plurality of neutralization tanks 4. The water softening tank 3 softens raw water containing hardness components with a weakly acidic cation exchange resin 7. The neutralization tank 4 neutralizes the pH of the softened water that has passed through the water softening tank 3 with a weakly basic anion exchange resin 8. Also, the water softening tank 3 has a first water softening tank 3a and a second water softening tank 3b. The neutralization tank 4 has a first neutralization tank 4a and a second neutralization tank 4b. The water softening device 1 is configured such that the raw water flows in the order of the first water softening tank 3a, the first neutralization tank 4a, the second water softening tank 3b, and the second neutralization tank 4b.

[0122] As a result, the raw water containing hardness components flows out of the first water softening tank 3a before the pH of the raw water decreases due to the water softening treatment in the first water softening tank 3a, is neutralized in the first neutralization tank 4a, and is then water-softened in the second water softening tank 3b. Therefore, compared with the case where the water softening tank 3 and the neutralization tank 4 are each configured independently, it is possible to suppress the decrease and acidification of the pH of the water flowing through the water softening tank 3. This makes it easier for the hardness components to exchange with the hydrogen ions held by the second weakly acidic cation exchange resin 7b in the second water softening tank 3b. Thus, the water softening device 1 can improve its water softening performance.

[0123] (5) In the water softening device 1, an electrolytic cell 9 that generates acidic electrolyzed water for regenerating the weakly acidic cation exchange resin 7 in the water softening tank 3 and alkaline electrolyzed water for regenerating the weakly basic anion exchange resin 8 in the neutralization tank 4, and a treatment tank 11 that mixes 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 and supplies the mixture to the electrolytic cell 9 are provided. As a result, it becomes possible to regenerate the weakly acidic cation exchange resin 7 with the acidic electrolyzed water generated in the electrolytic cell 9, and it becomes possible to regenerate the weakly basic anion exchange resin 8 with the alkaline electrolyzed water. Therefore, the maintenance frequency of the water softening device 1 can be reduced, and the water softening device 1 can be made usable over a long period.

[0124] (6) In the softening device 1, during the regeneration process of the weakly acidic cation exchange resin 7, the acidic electrolyzed water sent out from the electrolytic cell 9 flows through the second softening tank 3b and then through the first softening tank 3a. Thereby, during the regeneration process, the acidic electrolyzed water sent out from the electrolytic cell 9 flows into the second softening tank 3b where the adsorption amount of the hardness component is less than that in the first softening tank 3a, and the acidic electrolyzed water containing the hardness component is sent to the first softening tank 3a. In the regeneration of the second weakly acidic cation exchange resin 7b in the second softening tank 3b, since the consumption of hydrogen ions in the acidic electrolyzed water is small, that is, compared with the regeneration of the first softening tank 3a, the reduction of the hydrogen ion concentration can be suppressed. Therefore, the acidic electrolyzed water containing a large amount of hydrogen ions flows into the first softening tank 3a, and the re-adsorption of the hardness component in the first softening tank 3a can be suppressed. Therefore, the decrease in the regeneration efficiency can be suppressed and the regeneration time can be shortened.

[0125] In addition, since the acidic electrolyzed water sent out from the electrolytic cell 9 flows into the second softening tank 3b where the adsorption amount of the hardness component is less than that in the first softening tank 3a, and the acidic electrolyzed water containing the hardness component is sent to the first softening tank 3a, it can be said that the hardness component flowing out due to the regeneration of the second softening tank 3b is less than that in the first softening tank 3a. Therefore, compared with the case where the acidic electrolyzed water is introduced from the first softening tank 3a, when the acidic electrolyzed water is introduced from the second softening tank 3b, since the hardness component contained in the acidic electrolyzed water is less, the re-adsorption of the hardness component in the first softening tank 3a can be suppressed, the decrease in the regeneration efficiency can be suppressed, and it can also be said that the regeneration time can be shortened.

[0126] (7) The softening water treatment device 1 is configured such that during the regeneration process, acidic electrolyzed water is introduced from the downstream side of the first softening water tank 3a and the second softening water tank 3b into the first softening water tank 3a and the second softening water tank 3b. Thereby, during the regeneration process, in the softening water tank 3, the acidic electrolyzed water sent out from the electrolytic cell 9 flows in from the downstream side where the adsorption amount of hardness components is smaller, and the softening water tank 3 is regenerated. In the regeneration of the weakly acidic cation exchange resin 7 on the downstream side, since the consumption of hydrogen ions in the acidic electrolyzed water is small, that is, the reduction of the hydrogen ion concentration of the acidic electrolyzed water can be suppressed, it is possible to suppress the re-adsorption of the hardness components contained in the acidic electrolyzed water from the downstream side on the upstream side. Therefore, it is possible to suppress a decrease in the regeneration treatment efficiency of the softening water tank 3 and shorten the regeneration time.

[0127] In addition, since the acidic electrolyzed water sent out from the electrolytic cell 9 flows in from the downstream side in the softening water tank 3 where the adsorption amount of hardness components is smaller, and the softening water tank 3 is regenerated, it can also be said that the hardness components flowing out due to the regeneration of the weakly acidic cation exchange resin 7 on the downstream side are less than those on the upstream side. Therefore, compared with the case where the acidic electrolyzed water is introduced from the upstream side, when it is introduced from the downstream side, it is possible to suppress the re-adsorption of the hardness components to the weakly acidic cation exchange resin 7 on the upstream side, it is possible to suppress a decrease in the regeneration treatment efficiency, and it can also be said that the regeneration time can be shortened.

[0128] (8) In the softening water treatment device 1, during the softening water treatment, the first neutralization tank 4a is configured such that the acidic water flowing out of the first softening water tank 3a flows in. Thereby, the first neutralization tank 4a can neutralize the hydrogen ions generated from the first softening water tank 3a. Therefore, it is possible to suppress the inflow of acidic water into the second softening water tank 3b into which the water flowing out of the first neutralization tank 4a flows. Therefore, it is possible to perform softening with the second softening water tank 3b without degrading the softening performance of the second softening water tank 3b, and the softening performance is improved.

[0129] The above has been described based on the embodiments of the present invention. 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.

[0130] In the water softening device 1 according to the first embodiment, it is assumed that there are two water softening tanks 3 and two neutralization tanks 4 each, but it is not limited to this. For example, there may be three each, or more. As a result, during the water softening process, the number of times of alternately performing water softening and neutralization increases, so the water softening performance can be further improved. In such a case, the first regeneration treatment may be executed with the last-stage neutralization tank excluded.

[0131] Also, in the water softening device 1 according to the first embodiment, the acidic electrolyzed water is circulated in the order of the second water softening tank 3b and the first water softening tank 3a, but this is not the only case. For example, the acidic electrolyzed water may be circulated in the order of the first water softening tank 3a and the second water softening tank 3b. Furthermore, in the water softening device 1 according to the first embodiment, the acidic electrolyzed water is circulated from the downstream side of the water softening tank 3, but it may be circulated from the upstream side. Even in this way, the regeneration treatment of the water softening tank 3 can be performed.

[0132] In addition, in the water softening device 1 according to the first embodiment, in the wastewater treatment after the second regeneration treatment, the acidic electrolyzed water and the alkaline electrolyzed water remaining in the circulation channel 30A are caused to flow into the treatment tank 11 and discharged outside the device. However, this is not the limit. For example, as the wastewater treatment, after causing the acidic electrolyzed water and the alkaline electrolyzed water remaining in the circulation channel 30A to flow into the treatment tank 11 and discharged outside the device, the raw water may be circulated in the order of the inlet 2, the first water softening tank 3a, the first neutralization tank 4a, the second water softening tank 3b, the second neutralization tank 4b, the third recovery channel 37, and the treatment tank 11 and a cleaning treatment for discharging it outside the device may be performed. Thereby, the acidic electrolyzed water remaining in the weakly acidic cation exchange resin 7 in the water softening tank 3 is washed by the raw water, and the alkaline electrolyzed water remaining in the weakly basic anion exchange resin 8 in the neutralization tank 4 is washed by the raw water. As a result, the influence of the alkaline electrolyzed water remaining in the last-stage neutralization tank 4 (second neutralization tank 4b) after the second regeneration treatment (the influence that the water containing alkaline electrolyzed water is temporarily discharged from the water intake 5) can be further suppressed.

Industrial Applicability

[0133] The water softening device according to the present invention can be applied to a point-of-use (POU) water purification device installed at the place of use or a point-of-entry (POE) water purification device installed at the building entrance.

Explanation of Signs

[0134] 1 Water softening device 2 Inlet 3 Water softening tank 3a First water softening tank 3b Second water softening tank 4 Neutralization tank 4a First neutralization tank 4b Second neutralization tank 5 Water intake 6 Regeneration device 7 Weakly acidic cation exchange resin 7a First weakly acidic cation exchange resin 7b Second weakly acidic cation exchange resin 8 Weakly basic anion exchange resin 8a First weakly basic anion exchange resin 8b Second weakly basic anion exchange resin 9 Electrolytic cell 10 Electrode 11 Treatment tank 12 Water supply pump 13 Filtration section 14 Air vent valve 15 Control unit 20 Flow path 21 Flow path 22 Flow path 23 Flow path 24 Flow path 30 Circulation flow path 30A Circulation flow path 30B Circulation flow path 30a First circulation flow path 30b Second circulation flow path 30c Third circulation flow path 31 First supply flow path 32 Second supply flow path 33 First bypass flow path 34 Second bypass flow path 35 First recovery flow path 36 Second recovery flow path 37 Third recovery flow path 40 Water supply flow path 41 On-off valve 42 On-off valve 43 On-off valve 44 On-off valve 45 On-off valve 51 On-off valve 52 On-off valve 53 On-off valve 54 On-off valve 55 On-off valve 56 On-off valve 57 On-off valve 61 On-off valve 62 On-off valve

Claims

1. A plurality of water softening tanks for softening raw water containing a hardness component with a weakly acidic cation exchange resin; A plurality of neutralization tanks for neutralizing the pH of the softened water flowing through the water softening tanks with a weakly basic anion exchange resin; An electrolytic cell for generating 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; Comprising: In the water softening treatment, the water softening tanks and the neutralization tanks are alternately connected in communication to perform the softening of the raw water; In the regeneration treatment, the regeneration of the water softening tanks and the neutralization tanks is performed by a first regeneration treatment for regenerating the neutralization tanks except for the water softening tanks and the last-stage neutralization tank, and a second regeneration treatment for regenerating the neutralization tanks including the water softening tanks and the last-stage neutralization tank. A water softening device characterized by this.

2. The second regeneration treatment is executed when it reaches a set period set based on the usage status of the device, The water softening device according to claim 1, wherein the first regeneration treatment is executed when the water softening treatment is not being executed outside the set period.

3. When the second regeneration treatment ends, after performing a drainage treatment for discharging the acidic electrolyzed water used for regenerating the water softening tank and the alkaline electrolyzed water used for regenerating the neutralization tank to the outside, the water softening treatment is executed, The water softening device according to claim 1 or 2, wherein when the first regeneration treatment ends, the water softening treatment is executed without performing the drainage treatment.

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