Softening water device

Abstract

To provide a water softening device that can suppress a deterioration of a water softening performance caused by pH of water flowing through a water softening tank during a water softening treatment.SOLUTION: A water softening device 1 includes a water softening tank 3 and a neutralization tank 4. The water softening tank 3 softens raw water containing a hardness component with a weakly acidic cation exchange resin 7. Further, the water softening tank 3 has a first softening tank 3a and a second softening tank 3b. The neutralization tank 4 neutralizes pH of the soft water that has passed through the water softening tank 3 with a weakly basic anion exchange resin 8. Further, the neutralization tank 4 has a first neutralization tank 4a and a second neutralization tank 4b. The water softening device 1 is configured to distribute raw water containing a hardness component in an order of the first softening tank 3a, the first neutralization tank 4a, the second softening tank 3b, and the second neutralization tank 4b.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a water softening device for obtaining water for daily life. [Background technology]

[0002] In a conventional water softener using a weakly acidic cation exchange resin, a method of regenerating the cation exchange resin using acidic electrolyzed water produced by electrolysis is known as a method of regenerating the cation exchange resin without using salt (see, for example, Patent Document 1). A weakly acidic cation exchange resin has a proton at the end of the functional group, and softens the raw water by exchanging hardness components (e.g., calcium ions, magnesium ions) in the raw water for hydrogen ions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-30973 A Summary of the Invention [Problem to be solved by the invention]

[0004] In such conventional water softening devices, when softening hard water containing a large amount of hardness components or water containing a large proportion of permanent hardness among the hardness components, the water becomes strongly acidic before all of the hardness components are removed, so even if the water is softened using a large amount of weakly acidic cation exchange resin, the water softening performance decreases as it flows through the weakly acidic cation exchange resin.

[0005] The present invention is devised to solve the above-mentioned problems of the conventional art, and aims to provide a water softening device that can suppress a decrease in water softening performance caused by the pH of the water flowing through the water softening tank. [Means for solving the problem]

[0006] In order to achieve this object, the water softening device according to the present invention comprises a water softening tank, a neutralization tank, and 、 An electrolytic cell and a treatment cell; 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 that has passed through the water softening tank with a weakly basic anion exchange resin. The water softening tank has a first water softening tank and a second water softening tank. The neutralization tank also has a first neutralization tank and a second neutralization tank. The electrolytic tank produces 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 neutralizing tank. The treatment tank mixes the acidic electrolyzed water that has passed through the softening tank and the alkaline electrolyzed water that has passed through the neutralizing tank, and supplies the resulting mixture to the electrolytic tank. The water softening device is constructed so that raw water flows through the first water softening tank, the first neutralization tank, the second water softening tank, and the second neutralization tank in this order, thereby achieving the intended purpose. Effect of the Invention

[0007] According to the present invention, it is possible to provide a water softening device capable of suppressing a decrease in water softening performance caused by the pH of water flowing through a water softening tank. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a conceptual diagram showing the configuration of a water softening device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a configuration diagram showing a circulation flow path of the water softening device. [Diagram 3] FIG. 3 is a diagram showing a state of the water softening device during operation. [Figure 4] FIG. 4 is a diagram for explaining the water softening performance of the water softening devices according to the example and the comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The water softening apparatus according to the present invention includes a water softening tank and a neutralization tank. 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 that has passed through the water softening tank with a weakly basic anion exchange resin. The water softening tank includes a first water softening tank and a second water softening tank. The neutralization tank includes a first neutralization tank and a second neutralization tank. The water softening apparatus is configured such that raw water flows through the first water softening tank, the first neutralization tank, the second water softening tank, and the second neutralization tank in this order.

[0010] According to this configuration, raw water containing hardness components flows out of the first water softening tank before the pH of the raw water decreases due to the softening treatment in the first water softening tank, is neutralized in the first neutralization tank, and is softened in the second water softening tank. Therefore, compared to conventional water softening devices in which the softening tank and the neutralization tank are each configured separately, the decrease in pH of the water flowing through the water softening tank, i.e., acidification, can be suppressed, and hardness components are more likely to be exchanged with hydrogen ions held by the weakly acidic cation exchange resin in the water softening tank (particularly the second water softening tank). Therefore, compared to conventional water softening devices, it is possible to improve the water softening performance.

[0011] The water softening device according to the present invention may further include an electrolytic cell that 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, and a treatment tank that mixes the acidic electrolyzed water that has flowed through the water softening tank and the alkaline electrolyzed water that has flowed through the neutralization tank and supplies the resulting mixture to the electrolytic cell. With this configuration, the weakly acidic cation exchange resin can be regenerated by the acidic electrolyzed water generated in the electrolytic cell, and the weakly basic anion exchange resin can be regenerated by the alkaline electrolyzed water. This reduces the frequency of maintenance of the water softening device, making it possible to provide a water softening device that can be used for a long period of time.

[0012] In addition, in the water softening device according to the present invention, it is preferable that the acidic electrolyzed water discharged from the electrolytic cell is configured to flow through the second water softening cell and then through the first water softening cell during the regeneration process for regenerating the weakly acidic cation exchange resin. In this way, during the regeneration process, the acidic electrolyzed water discharged from the electrolytic cell flows into the second water softening cell, which has a smaller amount of adsorption of hardness components than the first water softening cell, and the acidic electrolyzed water containing hardness components is discharged from the second water softening cell to the first water softening cell. In the regeneration of the weakly acidic cation exchange resin in the second water softening cell, the consumption of hydrogen ions in the acidic electrolyzed water is small, that is, the reduction in hydrogen ion concentration can be suppressed compared to the regeneration of the first water softening cell, so that the acidic electrolyzed water containing a large amount of hydrogen ions flows into the first water softening cell, and the re-adsorption of hardness components in the first water softening cell can be suppressed. Therefore, the decrease in the efficiency of the regeneration process can be suppressed, and the regeneration time can be shortened.

[0013] In addition, the water softening device according to the present invention is preferably configured such that, during regeneration, the acidic electrolyzed water is introduced into the first and second softening tanks from the downstream side of the first and second softening tanks. In this way, during regeneration, the acidic electrolyzed water sent from the electrolytic tank flows in from the downstream side, where the amount of hardness components adsorbed is smaller, to regenerate each softening tank. In the regeneration of the weakly acidic cation exchange resin on the downstream side, the hydrogen ions in the acidic electrolyzed water are consumed less, that is, the reduction in the hydrogen ion concentration of the acidic electrolyzed water can be suppressed, so that the hardness components contained in the acidic electrolyzed water from the downstream side can be suppressed from being re-adsorbed on the upstream side. Therefore, the decrease in the efficiency of the regeneration process of each softening tank can be suppressed, and the regeneration time can be shortened.

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the following embodiment is an example of the present invention, and does not limit the technical scope of the present invention. Also, each figure described in the embodiment is a schematic diagram, and the size and thickness ratios of each component in each figure do not necessarily reflect the actual dimensional ratios.

[0015] (Embodiment 1) A water softening device 1 according to a first embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a conceptual diagram showing the configuration of the water softening device 1 according to the first embodiment of the present invention. Note that Fig. 1 conceptually shows each element of the water softening device 1.

[0016] (Overall composition) The water softening device 1 is a device that converts city water (raw water containing hardness components) supplied from the outside into neutral soft water that can be used as water for daily life.

[0017] Specifically, as shown in Fig. 1, the water softening apparatus 1 includes an inlet 2 for raw water from the outside, a water softening tank 3, a neutralization tank 4, an intake port 5 for treated soft water, and a regeneration device 6. The water softening tank 3 includes a first water softening tank 3a and a second water softening tank 3b. The neutralization tank 4 includes a first neutralization tank 4a and a second neutralization tank 4b. The regeneration device 6 includes an electrolytic tank 9, a treatment tank 11, and a water pump 12. The water softening apparatus 1 includes a plurality of on-off valves (on-off valves 41 to 45, on-off valves 51 to 56, on-off valves 61, and on-off valve 62) and a control unit 15.

[0018] The inlet 2 is connected to city water. The water softening device 1 is capable of taking out softened water from the water intake 5 using the pressure of the city water.

[0019] The inlet 2 is connected to the water intake 5 by flow paths 20, 21, 22, 23, and 24. Flow path 20 is a flow path that connects the inlet 2 to the first water softening tank 3a. Flow path 21 is a flow path that connects the first water softening tank 3a to the first neutralization tank 4a. Flow path 22 is a flow path that connects the first neutralization tank 4a to the second water softening tank 3b. Flow path 23 is a flow path that connects the second water softening tank 3b to the second neutralization tank 4b. Flow path 24 is a flow path that connects the second neutralization tank 4b to the water intake 5.

[0020] In other words, the flow path 20 is a flow path that guides raw water containing hardness components from the inlet 2 to the first water softening tank 3a. The flow path 21 is a flow path that guides water that has been softened in the first water softening tank 3a to the first neutralization tank 4a. The flow path 22 is a flow path that guides 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 raw water softened in the second water softening tank 3b to the second neutralization tank 4b. The flow path 24 is a flow path that guides softened water neutralized in the second neutralization tank 4b to the water intake 5.

[0021] In other words, in the water softening device 1, during the water softening process, city water supplied from outside flows in the following order: inlet 2, flow path 20, first water softening tank 3a, flow path 21, first neutralization tank 4a, flow path 22, second water softening tank 3b, flow path 23, second neutralization tank 4b, flow path 24, and water intake 5, and is discharged as neutral soft water.

[0022] (Water softening tank and neutralization tank) The water softening tank 3 is, for example, a cylindrical container filled with a weakly acidic cation exchange resin 7. The neutralization tank 4 is, for example, a cylindrical container filled with a weakly basic anion exchange resin 8.

[0023] 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 filled with a first weakly acidic cation exchange resin 7a. The second water softening tank 3b is filled with a second weakly acidic cation exchange resin 7b. 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 volume of the weakly acidic cation exchange resin 7. In the following description, the first weakly acidic cation exchange resin 7a and the second weakly acidic cation exchange resin 7b will be described as the weakly acidic cation exchange resin 7 when there is no need to distinguish between them.

[0024] The neutralization tank 4 includes a first neutralization tank 4a and a second neutralization tank 4b. The first neutralization tank 4a is configured by, for example, filling a first weakly basic anion exchange resin 8a in a cylindrical container. The second neutralization tank 4b is configured by filling a second weakly basic anion exchange resin 8b. The first neutralization tank 4a and the second neutralization tank 4b have the same flow path length, flow path cross-sectional area, and volume of the weakly basic anion exchange resin 8. In the following, the first weakly basic anion exchange resin 8a and the second weakly basic anion exchange resin 8b will be described as the weakly basic anion exchange resin 8 when there is no need to distinguish between them.

[0025] Here, the weakly acidic cation exchange resin 7 is not particularly limited, and any general-purpose resin can be used, for example, one having a carboxyl group (-COOH) as an exchange group. In addition, the hydrogen ion ( H + ) is a metal ion, an ammonium ion ( NH 4 + ) may be a cation.

[0026] The weakly basic anion exchange resin 8 is not particularly limited, and any general-purpose resin may be used, for example, a free base type resin.

[0027] 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 the weakly acidic cation exchange resin 7 having hydrogen ions at the ends of its functional groups. The water softening tank 3 exchanges cations (calcium ions, magnesium ions) that are hardness components contained in the flowing water (raw water) with hydrogen ions, thereby reducing the hardness of the raw water and softening the raw water. In addition, since the ends of the functional groups of the weakly acidic cation exchange resin 7 are hydrogen ions, the weakly acidic cation exchange resin 7 can be regenerated using acidic electrolyzed water in the regeneration process described below. At this time, the weakly acidic cation exchange resin 7 releases cations that are hardness components that were taken in during the water softening process.

[0028] More specifically, in the first water softening tank 3a, raw water containing hardness components is passed through a flow path 20, and the raw water containing hardness components is softened by passing through the first weakly acidic cation exchange resin 7a filled inside, and the softened water is passed through a flow path 21 to the first neutralization tank 4a. However, the water softened by the first weakly acidic cation exchange resin 7a contains many hydrogen ions that are exchanged with hardness components and flow out, and is acidic water with a low pH. Here, when softening water is performed, the pH of water containing many permanent hardness components (for example, sulfates such as calcium sulfate or chlorides such as magnesium chloride) as hardness components is more likely to decrease than that of water containing many temporary hardness components (for example, carbonates such as calcium carbonate). As will be described in detail later, when the pH is decreased, softening is difficult to proceed, so the water that has flowed through the first water softening tank 3a is passed through the first neutralization tank 4a to be neutralized.

[0029] Meanwhile, in the second water softening tank 3b, neutralized water is passed through the flow path 22 and passes through the second weakly acidic cation exchange resin 7b filled inside. As a result, hardness components that could not be removed in the first water softening tank 3a are exchanged with hydrogen ions possessed by the second weakly acidic cation exchange resin 7b. Therefore, the water that flows into the second water softening tank 3b is softened. However, the water softened by the second weakly acidic cation exchange resin 7b is acidic water because it contains hydrogen ions that have been exchanged with hardness components and flowed out.

[0030] The neutralization tank 4 neutralizes the pH of the soft water (acidified soft water) containing hydrogen ions coming out of the softening tank 3 by the action of the weakly basic anion exchange resin 8, converting it into neutral soft water. More specifically, the neutralization tank 4 is equipped with the weakly basic anion exchange resin 8, which adsorbs the hydrogen ions contained in the soft water from the softening tank 3 together with anions (negative ions), thereby increasing the pH of the soft water and making it neutral soft water. The weakly basic anion exchange resin 8 can be regenerated using alkaline electrolyzed water in the regeneration process described below.

[0031] More specifically, in the first neutralization tank 4a, softened water containing hydrogen ions is passed through a flow path 21 and flows through the first weakly basic anion exchange resin 8a filled inside, thereby neutralizing the acidified water flowing out from the first water softening tank 3a, and the neutral water is allowed to flow into the second water softening tank 3b through a flow path 22. In other words, the first neutralization tank 4a neutralizes the acidic water flowing out from the first water softening tank 3a and containing hydrogen ions released from the first weakly acidic cation exchange resin 7a, and sends the water that has flowed through the first neutralization tank 4a to the second water softening tank 3b as water that is easy to soften.

[0032] Meanwhile, in the second neutralization tank 4b, soft water containing hydrogen ions is passed from flow path 23 and flows through the second weakly basic anion exchange resin 8b filled inside, thereby neutralizing the acidified soft water discharged from the second water softening tank 3b and passing the neutral soft water to the outside through flow path 24. In other words, the second neutralization tank 4b neutralizes the acidic water discharged from the second water softening tank 3b and containing hydrogen ions released from the second weakly acidic cation exchange resin 7b, thereby discharging soft water that can be used as water for daily use.

[0033] (playback device) The regenerator 6 is a device that regenerates the weakly acidic cation exchange resin 7 in the water softening tank 3 and regenerates the weakly basic anion exchange resin 8 in the neutralization tank 4. Specifically, the regenerator 6 includes the electrolytic tank 9, the treatment tank 11, and the water pump 12, as described above. In the regenerator 6, a first supply flow path 31, a first recovery flow path 35, a second supply flow path 32, and a second recovery flow path 36 are connected to the flow path 23, the flow path 20, the flow path 21, and the flow path 24 from the inlet 2 to the water intake 5, respectively. In addition, the flow path 21 and the flow path 22 are connected by a first bypass flow path 33. In addition, the flow path 22 and the flow path 23 are connected by a second bypass flow path 34. Each flow path constitutes a circulation flow path 30 (first circulation flow path 30a, second circulation flow path 30b) described later.

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

[0035] (electrolytic cell) The electrolytic cell 9 generates and discharges acidic electrolyzed water and alkaline electrolyzed water by electrolyzing the water (water supplied from the treatment cell 11) using the electrodes 10 provided therein. More specifically, hydrogen ions are generated by electrolysis at the electrode that becomes the anode during electrolysis, and acidic electrolyzed water is generated. Meanwhile, hydroxide ions are generated by electrolysis at the electrode that becomes the cathode during electrolysis, and alkaline electrolyzed water is generated. The electrolytic cell 9 supplies the acidic electrolyzed water to the second water softening cell 3b through the first supply flow path 31. Meanwhile, the electrolytic cell 9 supplies the alkaline electrolyzed water to the first neutralization cell 4a through the second supply flow path 32. Although the details will be described later, the acidic electrolyzed water generated by the electrolytic cell 9 is used to regenerate the first weakly acidic cation exchange resin 7a of the first water softening cell 3a and the second weakly acidic cation exchange resin 7b of the second water softening cell 3b. The alkaline electrolyzed water generated by the electrolytic bath 9 is used to regenerate the first weakly basic anion exchange resin 8a in the first neutralization bath 4a and the second weakly basic anion exchange resin 8b in the second neutralization bath 4b. The electrolytic bath 9 is configured so that the current supply state to the electrode 10 can be controlled by the 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 water to be circulated through the circulation flow path 30 (see FIG. 2) when regenerating the weakly acidic cation exchange resin 7 and the weakly basic anion exchange resin 8. The treatment tank 11 also mixes the acidic electrolyzed water containing hardness components that has been circulated through the water softening tank 3 with the alkaline electrolyzed water containing anions that has been circulated through the neutralization tank 4, and supplies the resulting mixture to the electrolysis tank 9.

[0037] In the treatment tank 11, the mixed hardness components react with the alkaline electrolyzed water to generate reaction products (reaction products due to the hardness components contained in the raw water). More specifically, the 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 to the treatment tank 11. In addition, the 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 to the treatment tank 11. Then, in the 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 components in the acidic electrolyzed water are calcium ions, a reaction occurs in which calcium carbonate or calcium hydroxide is generated by mixing with the alkaline electrolyzed water. The reacted hardness components can be separated as reaction products by the filtration unit 13 described later, and treated water can be obtained.

[0038] In addition, "hardness components react" does not only mean that all of the hardness components react, but also includes a state in which the treatment tank 11 contains components that do not react or components that do not exceed the solubility product.

[0039] The treated water obtained by the reaction of the hardness components in the treatment tank 11 is passed through the electrolytic tank 9, where it is electrolyzed into acidic electrolyzed water and alkaline electrolyzed water, which are then supplied to the water softener tank 3 and neutralizer tank 4, respectively. The acidic electrolyzed water and alkaline electrolyzed water are reused in the water softener tank 3 and neutralizer tank 4, respectively, and then passed through the treatment tank 11 again. This allows the acidic electrolyzed water and alkaline electrolyzed water used for regenerating the weakly acidic cation exchange resin 7 and the weakly basic anion exchange resin 8 to be reused. Moreover, because the water with which the hardness components have reacted is reused, it is possible to suppress a decrease in regeneration efficiency when regenerating the weakly acidic cation exchange resin 7.

[0040] (Water pump) The water pump 12 is a device that circulates water through the circulation flow path 30 (see FIG. 2) during regeneration treatment by the regeneration device 6. The water pump 12 is provided in a water supply flow path 40 that communicates between the treatment tank 11 and the electrolytic tank 9. The water pump 12 is preferably disposed upstream of the electrolytic tank 9 and downstream of the treatment tank 11. The reason for such an arrangement is that the single water pump 12 can easily circulate water through a first circulation flow path 30a and a second circulation flow path 30b, which will be described later. The water pump 12 is also connected to a control unit 15, which will be described later, wirelessly or by wire so as to be able to communicate with each other.

[0041] (Filtration section) The filtration unit 13 is provided at the front stage of the water supply flow path 40 that connects the treatment tank 11 to the electrolytic tank 9. The filtration unit 13 separates precipitates contained in the water that has passed through the treatment tank 11. The precipitates are reaction products generated by the reaction between the acidic electrolyzed water containing hardness components that has passed through the water softening tank 3 and the alkaline electrolyzed water containing anions that has passed through the neutralization tank 4.

[0042] By separating the precipitates in the filtration unit 13, the treated water flowing through the water supply flow path 40 contains fewer hardness components than city water or water not provided with the filtration unit 13. In other words, by separating the precipitates in the filtration unit 13, the hardness of the treated water is reduced, and the hardness of the acidic electrolyzed water generated in the electrolytic cell 9 is also reduced. Therefore, the hardness components flowing into the water softening cell 3 can be reduced, and the reduction in the regeneration efficiency of the weakly acidic cation exchange resin 7 can be suppressed.

[0043] The filtration section 13 may have any form as long as it can separate the reaction products with the hardness components in the treatment tank 11. For example, it may be a cartridge type filter, a filtration layer using a granular filter medium, a cyclone type solid-liquid separator, a hollow fiber membrane, or the like.

[0044] (Shut-off valve) A plurality of on-off valves (on-off valves 41 to 45, on-off valves 51 to 56, on-off valves 61, and on-off valves 62) are provided in each flow path, and are switched between an "open" state and a "closed" state in each flow path. In addition, each of the plurality of on-off valves (on-off valves 41 to 45, on-off valves 51 to 56, on-off valves 61, and on-off valves 62) is connected to a control unit 15 described later wirelessly or by wire so as to be able to communicate with each other.

[0045] (Control unit) The control unit 15 controls the water softening treatment for softening raw water containing hardness components. The control unit 15 also controls the regeneration treatment of the weakly acidic cation exchange resin 7 in the water softening tank 3 and the weakly basic anion exchange resin 8 in the neutralization tank 4. The control unit 15 also controls the switching of the water softening treatment, regeneration treatment, and wastewater treatment of the water softening device 1. In this case, the control unit 15 controls the operation of the electrode 10, the water pump 12, the on-off valves 41 to 45, the on-off valves 51 to 56, the on-off valve 61, and the on-off valve 62, switches between the water softening treatment, the regeneration treatment, and the wastewater treatment, and causes each treatment to be performed.

[0046] (Flow path) Next, a description will be given of the circulation flow path 30 formed during the regeneration treatment of the water softening device 1 with reference to Fig. 2. Fig. 2 is a configuration diagram showing the circulation flow path 30 of the water softening device 1.

[0047] Although the explanation will be repeated, as shown in FIG. 2, in the water softening device 1, the electrolytic cell 9 and the treatment cell 11 constituting the regenerating device 6 are connected in communication with each other via a water supply flow path 40. The electrolytic cell 9 and the treatment cell 11 are connected to the flow paths 23, 20, 21, and 24 from the inlet 2 to the water intake 5 via a first supply flow path 31, a first recovery flow path 35, a second supply flow path 32, and a second recovery flow path 36, respectively. The flow paths 21 and 22 are bypass-connected via a first bypass flow path 33. The flow paths 22 and 23 are bypass-connected via a second bypass flow path 34. The respective flow paths constitute a circulation flow path 30 (first circulation flow path 30a, second circulation flow path 30b) described later.

[0048] The first supply flow path 31 is a flow path that supplies acidic electrolyzed water from the electrolytic cell 9 to the second water softening cell 3b, and an on-off valve 53 is provided in the flow path. That is, the water softening device 1 is provided with the first supply flow path 31 that allows acidic electrolyzed water to be drawn from the electrolytic cell 9 and sent to the downstream side of the second water softening cell 3b.

[0049] The first bypass flow path 33 is a flow path that supplies acidic electrolyzed water from the second water softening tank 3b to the first water softening tank 3a, and an on-off valve 55 is provided in the flow path. That is, the water softening device 1 is provided with the first bypass flow path 33 that allows the acidic electrolyzed water that has flowed through the second water softening tank 3b to be sent downstream of the first water softening tank 3a. By providing the first bypass flow path 33, the regeneration process can be carried out without flowing acidic electrolyzed water through the first neutralization tank 4a that is located between the first water softening tank 3a and the second water softening tank 3b.

[0050] The first recovery flow path 35 is a flow path that recovers the acidic electrolyzed water containing hardness components that has passed through the first water-softening tank 3a to the treatment tank 11, and is provided with an on-off valve 51. That is, the water softening device 1 is provided with the first recovery flow path 35 that enables the upstream side of the treatment tank 11 to be connected to the upstream side of the first water-softening tank 3a.

[0051] The second supply flow path 32 is a flow path that supplies alkaline electrolyzed water from the electrolytic cell 9 to the first neutralization cell 4a, and is provided with an on-off valve 52. That is, the water softener 1 is provided with the second supply flow path 32 that allows alkaline electrolyzed water to be drawn from the electrolytic cell 9 and sent to the upstream side of the first neutralization cell 4a.

[0052] The second bypass flow path 34 is a flow path that supplies alkaline electrolyzed water from the first neutralization tank 4a to the second neutralization tank 4b, and is provided with an on-off valve 56. That is, the water softener 1 is provided with the second bypass flow path 34 that allows the alkaline electrolyzed water that has flowed through the first neutralization tank 4a to be sent to the upstream side of the second neutralization tank 4b.

[0053] The second recovery flow path 36 is a flow path that recovers the alkaline electrolyzed water that has passed through the second neutralization tank 4b to the treatment tank 11, and is provided with an on-off valve 54. That is, the water softening device 1 is provided with the second recovery flow path 36 that enables the upstream side of the treatment tank 11 to be connected to the downstream side of the second neutralization tank 4b.

[0054] The circulation flow path 30 includes a first circulation flow path 30a through which water pumped out of 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 water pumped out of the treatment tank 11 by the water supply pump 12 flows through the first neutralization tank 4a and the second neutralization tank 4b.

[0055] 2 (white arrow), the first circulation flow path 30a is a flow path through which water sent from the treatment tank 11 by the water supply pump 12 flows through the electrolytic tank 9, the second water softening tank 3b, and the first water softening tank 3a, and circulates back to the treatment tank 11. More specifically, the first circulation flow path 30a is a flow path through which the water sent from the treatment tank 11 by the water supply pump 12 circulates through the water supply flow path 40, the electrolytic tank 9, the first supply flow path 31, the on-off valve 53, the second water softening tank 3b, the first bypass flow path 33, the on-off valve 55, the first water softening tank 3a, the first recovery flow path 35, the on-off valve 51, and the treatment tank 11 in this order.

[0056] 2 (black arrow), the second circulation flow path 30b is a flow path through which water sent out from the treatment tank 11 by the water supply pump 12 flows through the electrolytic tank 9, the first neutralization tank 4a, and the second neutralization tank 4b, and circulates back to the treatment tank 11. 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 flows and circulates through the water supply flow path 40, the electrolytic tank 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 56, the second neutralization tank 4b, the second recovery flow path 36, the on-off valve 54, and the treatment tank 11 in this order.

[0057] Here, the state of each flow path for circulating water in the circulation flow path 30 will be described.

[0058] An on-off valve 44 is provided in the flow path 23 downstream of the first supply flow path 31 and upstream of the second bypass flow path 34. By closing the on-off valve 44 and opening the on-off valve 53, the first supply flow path 31 is connected in communication with the downstream side of the second water-softening tank 3b. This allows acidic electrolyzed water from the electrolytic tank 9 to be supplied to the second water-softening tank 3b.

[0059] An on-off valve 42 is provided in the flow path 21 downstream of the first bypass flow path 33 and upstream of the second supply flow path 32. An on-off valve 43 is provided in the flow path 22 downstream of the second bypass flow path 34 and upstream of the first bypass flow path 33. By closing the on-off valves 42 and 43 and opening the on-off valve 55, the first bypass flow path 33 is connected in communication with the upstream side of the second water softening tank 3b and the downstream side of the first water softening tank 3a. This makes it possible to supply the acidic electrolyzed water that has flowed through the second water softening tank 3b to the first water softening tank 3a.

[0060] Further, an on-off valve 41 is provided in the flow path 20 downstream of the inlet 2 and upstream of the first recovery flow path 35. By closing the on-off valves 41 and 42 and opening the on-off valve 51, the first recovery flow path 35 is connected in communication with the upstream side of the first water-softening tank 3a. This makes it possible for the water softening device 1 to recover, in the treatment tank 11, 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.

[0061] Furthermore, by closing the on-off valve 42 and opening the on-off valve 52, the second supply flow path 32 is connected to the upstream side of the first neutralization tank 4a, so that alkaline electrolyzed water from the electrolytic tank 9 can be supplied to the first neutralization tank 4a.

[0062] Furthermore, by closing the on-off valves 42, 43 and 44 and opening the on-off valve 56, the second bypass flow path 34 is connected to the downstream side of the first neutralization tank 4a and the upstream side of the second neutralization tank 4b. This allows the alkaline electrolyzed water that has flowed through the first neutralization tank 4a to be supplied to the second neutralization tank 4b.

[0063] Furthermore, by closing the on-off valves 44 and 45 and opening the on-off valve 54, the second recovery passage 36 is connected downstream of the second neutralization tank 4b. This makes it possible for the water softening device 1 to recover, in the treatment tank 11, the water (alkaline electrolyzed water containing anions) that has flowed through the first neutralization tank 4a and the second neutralization tank 4b.

[0064] In addition, an on-off valve 61 is provided in the water supply flow path 40 downstream of the treatment tank 11 (at a position between the treatment tank 11 and the water supply pump 12). By closing the on-off valve 61, water can be stored in the treatment tank 11. On the other hand, by opening the on-off valve 61, water can be supplied to the water supply flow path 40.

[0065] In addition, the circulation of water to the circulation flow path 30 can be started by closing the on-off valve 41 and the on-off valve 45, while the circulation of water to the circulation flow path 30 can be stopped by opening the on-off valve 41 and the on-off valve 45.

[0066] (Water softening, regeneration, and wastewater treatment) Next, the water softening process, regeneration process, and drainage process of the water softening device 1 starting from the regeneration process will be described with reference to Fig. 3. Fig. 3 is a diagram showing the state of the water softening device 1 during operation.

[0067] In the water softening treatment, regeneration treatment, and wastewater treatment, the control unit 15 controls the on-off valves 41 to 45, the on-off valves 51 to 56, the on-off valves 61 and 62, the electrodes 10 of the electrolytic cell 9, and the water pump 12 to switch to the respective flow states, as shown in Fig. 3. The control unit 15 has a computer system having a processor and a memory. The processor executes a program stored in the memory, so that the computer system functions as the control unit. The program executed by the processor is pre-recorded in the memory of the computer system here, but may be recorded in a non-transitory recording medium such as a memory card and provided, or may be provided via an electric communication line such as the Internet.

[0068] 3 indicates that the corresponding on-off valve is "open", that the electrode 10 is energized, and that the water pump 12 is operating. Blank spaces indicate that the corresponding on-off valve is "closed", that the electrode 10 is not energized, and that the water pump 12 is stopped.

[0069] (Recycling) First, the operation of the regeneration device 6 of the water softening device 1 during regeneration treatment will be described in order with reference to the columns "Water injection" and "Regeneration" in FIG.

[0070] In the water softening apparatus 1, the water softening tank 3 filled with the weakly acidic cation exchange resin 7 loses or loses its cation exchange capacity with continued use. In other words, after all of 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 is no longer possible. In this state, hardness components become contained in the treated water. For this reason, in the water softening apparatus 1, it becomes necessary to carry out a regeneration process of the water softening tank 3 and the neutralization tank 4 using the regeneration device 6.

[0071] Therefore, in the water softening device 1, once per predetermined period (for example, once per day (24 hours)), the control unit 15 identifies a time period during which the regeneration process is possible, and executes the regeneration process.

[0072] First, as shown in Fig. 3, when water is injected, the on-off valve 41 and the on-off valve 51 are opened. As a result, the water softening device 1 introduces raw water into the treatment tank 11 from the inlet 2 via the first recovery passage 35 by the pressure of city water. At this time, the on-off valves 42 to 45, the on-off valves 52 to 56, the on-off valves 61 and 62 are closed. By storing a predetermined amount of water according to the capacity of the water softening device 1 in the treatment tank 11, the regeneration device 6 can ensure the amount of water during regeneration.

[0073] Next, during regeneration, when the on-off valves 41 to 45 and the on-off valve 62 are closed and the on-off valves 51 to 56 and the on-off valve 61 are opened, the first circulation flow path 30a and the second circulation flow path 30b are formed, as shown in FIG. 2.

[0074] When the electrodes 10 and the water pump 12 of the electrolytic bath 9 are operated, the water stored in the treatment bath 11 circulates through both the first circulation flow path 30a and the second circulation flow path 30b.

[0075] At this time, the acidic electrolyzed water generated in the electrolytic cell 9 flows through the first supply flow path 31 and is sent to the second water softening cell 3b, and flows through the second weakly acidic cation exchange resin 7b therein. Then, the acidic electrolyzed water that has flowed through the second water softening cell 3b flows through the first bypass flow path 33 and is sent to the first water softening cell 3a, and flows through the first weakly acidic cation exchange resin 7a therein. 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. This regenerates the first weakly acidic cation exchange resin 7a and the second weakly acidic cation exchange resin 7b. After that, the acidic electrolyzed water that has flowed through the first weakly acidic cation exchange resin 7a flows into the first recovery flow path 35, containing the cations. 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 flow path 33 and the first recovery flow path 35.

[0076] In this way, the first circulation flow path 30a is configured to allow the acidic electrolyzed water to flow from the downstream side of the second water softening tank 3b, which is located at the most downstream from the inlet of the raw water and has the second weakly acidic cation exchange resin 7b that has a small amount of hardness components adsorbed thereon, to flow into the downstream side of the first water softening tank 3a, which is located at the upstream and has the first weakly acidic cation exchange resin 7a that has a larger amount of hardness components adsorbed thereon than the second weakly acidic cation exchange resin 7b. In other words, the first circulation flow path 30a is a flow path that allows the acidic electrolyzed water discharged from the electrolytic tank 9 to flow through the second water softening tank 3b, then to be sent to the first water softening tank 3a by the first bypass flow path 33, to flow through the first water softening tank 3a, to be collected in the treatment tank 11, and then to flow into the electrolytic tank 9. In addition, the first circulation flow path 30a has a path for introducing the acidic electrolyzed water discharged from the electrolytic tank 9 into the first water softening tank 3a and the second water softening tank 3b from the downstream side of the first water softening tank 3a and the second water softening tank 3b, and discharging the acidic electrolyzed water from the upstream side where a greater amount of hardness components are adsorbed than on the downstream side of each water softening tank.

[0077] On the other hand, the alkaline electrolyzed water generated in the electrolytic bath 9 is fed through the second supply flow path 32 into the first neutralization bath 4a and flows through the first weakly basic anion exchange resin 8a therein. The alkaline electrolyzed water that has flowed through the first neutralization bath 4a flows through the second bypass flow path 34, is fed into the second neutralization bath 4b, and flows through the second weakly basic anion exchange resin 8b therein. 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. This regenerates the first weakly basic anion exchange resin 8a and the second weakly basic anion exchange resin 8b. After that, the alkaline electrolyzed water that has flowed through the second weakly basic anion exchange resin 8b contains anions and flows into the second recovery flow path 36. 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 collected in the treatment tank 11 via the second bypass flow path 34 and the second recovery flow path 36. The water softener 1 may be configured so that the alkaline electrolyzed water produced in the electrolytic tank 9 flows through the second neutralization tank 4b, then through the first neutralization tank 4a, and then flows into the treatment tank 11. In that case, for example, the second supply flow path 32 may be connected to the downstream side of the second neutralization tank 4b and the upstream side of the on-off valve 45, and the second recovery flow path 36 may be connected to the downstream side of the on-off valve 42 and the upstream side of the first neutralization tank 4a.

[0078] 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 and the alkaline electrolyzed water containing anions recovered from the first neutralization tank 4a and the second neutralization tank 4b are mixed and neutralized.

[0079] In this case, by mixing acidic electrolyzed water containing cations (hardness components) with alkaline electrolyzed water containing anions, the hardness components react with hydroxide ions contained in the alkaline electrolyzed water to produce precipitates. For example, if the hardness components in the acidic electrolyzed water are calcium ions, calcium hydroxide will be produced by the alkaline electrolyzed water, or calcium carbonate will be produced by combining with carbonate ions normally present in the water.

[0080] Thereafter, reaction products are removed from the treated water that has been treated in the treatment tank 11 as it flows through the filtration section 13, and the treated water is again passed through the water supply flow path 40 to the electrolytic tank 9. The passed water is then electrolyzed again in the electrolytic tank 9.

[0081] Here, the electrolyzed water (acidic electrolyzed water, alkaline electrolyzed water) electrolyzed again in the electrolytic bath 9 is used for regenerating the weakly acidic cation exchange resin 7 and the weakly basic anion exchange resin 8, respectively. That is, the acidic electrolyzed water used for regenerating the weakly acidic cation exchange resin 7 is reused as electrolyzed water again in the treatment bath 11 after the hardness components are converted into reaction products and filtered. Moreover, the reused electrolyzed acidic water contains less hardness components than city water (raw water containing hardness components) supplied from the outside or when the treatment bath 11 is not provided. In addition, when electrolyzed in the electrolytic bath 9, the hardness components, which are cations, move to the alkaline electrolyzed water, so that the hardness of the acidic electrolyzed water decreases, and the decrease in the regeneration efficiency of the weakly acidic cation exchange resin 7 can be suppressed. Furthermore, the adhesion of solidified matters caused by hardness components can be suppressed inside the electrolytic bath 9 and the water softening bath 3.

[0082] When the regeneration process is completed, the water softening device 1 stops the operation of the electrode 10 and the water pump 12. Also, the on-off valve 62 is opened to transition to the drainage process. The regeneration process may be completed after a certain time (e.g., 7 hours) from the start of the regeneration process (when the electrode 10 starts operating).

[0083] (Wastewater treatment) In the water softener 1, when the regeneration process is completed, the process proceeds to the discharge process. Here, the discharge process is a process for discharging the acidic electrolyzed water and the alkaline electrolyzed water remaining in the circulation flow path 30.

[0084] Next, the operation of the water softening device 1 during wastewater treatment will be described with reference to the section "During wastewater treatment" in FIG.

[0085] In the water softening device 1, as shown in FIG. 3, during wastewater treatment (during wastewater discharge), the on-off valves 41 to 45 are closed, and the on-off valves 51 to 56, the on-off valve 61, and the on-off valve 62 are opened.

[0086] This allows the acidic electrolyzed water remaining in the first circulation flow path 30a and the alkaline electrolyzed water remaining in the second circulation flow path 30b to flow into the treatment tank 11.

[0087] Next, when the on-off valve 62 is opened, the air vent valve 14 operates to discharge the electrolytic water in the treatment tank 11 to the outside of the apparatus.

[0088] By performing the wastewater treatment, it is possible to prevent the acidic electrolyzed water and alkaline electrolyzed water remaining in the circulation flow path 30 from being mixed with the raw water flowing in from the inlet 2 and being discharged from the water intake 5 when the water softening treatment is restarted.

[0089] Then, in the water softening device 1, when the wastewater treatment is completed, the on-off valves 51 to 56, 61, and 62 are closed, and the on-off valves 41 to 45 are opened, thereby transitioning to the water softening treatment. The wastewater treatment may be completed when a certain time (for example, one minute) has elapsed since the start of the wastewater treatment.

[0090] (Water softening treatment) When the wastewater treatment is completed, the water softening device 1 starts water softening treatment.

[0091] Next, the operation of the water softening device 1 during water softening treatment will be described with reference to the section "water softening" in FIG.

[0092] In the water softening device 1, as shown in Fig. 3, in the water softening process (softening water), the on-off valve 45 provided at the water intake 5 is opened while the on-off valves 41 to 44 are open. This allows city water (raw water containing hardness components) from the outside to flow through the water softening tank 3 and the neutralization tank 4, so that the water softening device 1 can take out softened water (neutral soft water) from the water intake 5. At this time, the on-off valves 51 to 56, the on-off valves 61, and the on-off valves 62 are all closed. In addition, the operation of the electrode 10 of the electrolytic tank 9 and the water pump 12 is also stopped.

[0093] Specifically, as shown in FIG. 1, in the water softening process, raw water is supplied from the inlet 2 through the flow path 20 by the pressure of city water to the first water softening tank 3a. 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, 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 is performed). The raw water is softened by removing the cations from the raw water. The softened water contains many hydrogen ions that have been exchanged with hardness components and discharged, and is acidified to become 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, hydrogen ions are removed from the water softened by the first water softening tank 3a, and the lowered pH rises and is neutralized. Therefore, the softening process in the second water softening tank 3b proceeds more easily than when the water softened in the first water softening tank 3a is directly softened in the second water softening tank 3b. The water neutralized in the first neutralization tank 4a flows further 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 that flows 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 soft water that flows in are adsorbed by the action of the second weakly basic anion exchange resin 8b. In other words, hydrogen ions are removed from the soft water, causing the lowered pH to rise, turning the water into softened neutral water that can be used for daily life. The softened neutral water flows through flow path 24 and can be taken out from water intake port 5.

[0094] Then, in the water softening device 1, when a time period specified by the control unit 15 is reached or when the water softening process exceeds a certain period of time, the regeneration process is carried out.

[0095] In this manner, in the water softening device 1, the water softening process, the regeneration process, and the drainage process are repeatedly performed.

[0096] Next, the reason why the water softening tank 3 is made up of the first water softening tank 3a and the second water softening tank 3b, and the neutralization tank 4 is made up of the first neutralization tank 4a and the second neutralization tank 4b, and their configuration will be described with reference to FIG.

[0097] FIG. 4 is a diagram for explaining the water softening performance of the water softeners according to the examples and the comparative example. More specifically, FIG. 4(a) is a conceptual diagram showing the water softening tank and neutralization tank constituting the water softeners according to the examples and the comparative example. FIG. 4(b) is a diagram showing the water softening performance of the water softeners according to the examples and the comparative example, plotting the hardness of water after softening treatment against the amount of raw water containing hardness components passing through. Here, the examples correspond to the water softener 1 according to the first embodiment, and the comparative example corresponds to a conventional water softener 1c.

[0098] As shown in FIG. 4(a), the water softener 1c according to the comparative example is composed of a single water softening tank 3c and a single neutralization tank 4c. The water softening tank 3c is filled with a weakly acidic cation exchange resin 7c. The neutralization tank 4c is filled with a weakly basic anion exchange resin 8c. During the water softening process, the water softener 1c passes raw water containing hardness components from the upstream of the water softening tank 3c, and the hardness components are adsorbed by the weakly acidic cation exchange resin 7c. The resulting acidified soft water is then passed through the neutralization tank 4c, where the weakly basic anion exchange resin 8c adsorbs and neutralizes hydrogen ions, thereby obtaining softened neutral water.

[0099] On the other hand, the water softening device 1 according to the embodiment is composed of a water softening tank 3 and a neutralization tank 4. The water softening tank 3 is composed of a first water softening tank 3a and a second water softening tank 3b. The first water softening tank 3a is filled with a first weakly acidic cation exchange resin 7a. The second water softening tank 3b is filled with a second weakly acidic cation exchange resin 7b. The flow path cross-sectional area of ​​the first water softening tank 3a and the second water softening tank 3b is configured to be equal to the cross-sectional area of ​​the water softening tank 3c. The flow path cross-sectional area refers to the cross-sectional area when the water softening tank 3 and the neutralization tank 4 are cut perpendicularly to the flow direction. The total flow path length of the first water softening tank 3a and the second water softening tank 3b is configured to be equal to the flow path length of the water softening tank 3c. Furthermore, the sum of the volumes of the first weakly acidic cation exchange resin 7a and the second weakly acidic cation exchange resin 7b is configured to be equal to the volume of the weakly acidic cation exchange resin 7c.

[0100] The neutralization tank 4 is composed of a first neutralization tank 4a and a second neutralization tank 4b. The first neutralization tank 4a is filled with a first weakly basic anion exchange resin 8a. The second neutralization tank 4b is filled with a second weakly basic anion exchange resin 8b. The flow path cross-sectional area of ​​the first neutralization tank 4a and the second neutralization tank 4b is configured to be equal to the flow path area of ​​the neutralization tank 4c. The total flow path length of the first neutralization tank 4a and the second neutralization tank 4b is configured to be equal to the flow path length of the neutralization tank 4c. The total volume of the first weakly basic anion exchange resin 8a and the second weakly basic anion exchange resin 8b is configured to be equal to the volume of the weakly basic anion exchange resin 8c.

[0101] Furthermore, the water softening device 1 is configured so that during the water softening process, raw water containing hardness components flowing in from the inlet 2 flows through the first water softening tank 3a, the first neutralization tank 4a, the second water softening tank 3b, and the second neutralization tank 4b in that order.

[0102] As shown in FIG. 4(b), in the comparative example, when 200-300 L of raw water was passed through, the hardness of the water after the softening treatment exceeded 50 ppm, and the hardness increased as the amount of water passed through increased. In the comparative example, when the softening treatment was performed, the hardness components contained in the raw water were exchanged with the hydrogen ions adsorbed on the weakly acidic cation exchange resin 7c in the softening tank 3c, and the hydrogen ions were released. Then, as the water flows through the softening tank 3c, the pH of the water passing through the tank decreases (the water becomes acidic), and the adsorption of the hardness components becomes difficult. After that, the water that passed through the softening tank 3c flows into the neutralization tank 4c, where the hydrogen ions are removed by the action of the weakly basic anion exchange resin 8c. Therefore, the decreased pH increases and the water becomes neutral, but in order to obtain soft water, it is necessary to perform a regeneration treatment when the amount of raw water passing through the tank reaches 200-300 L.

[0103] On the other hand, in the embodiment, even when 1500 L of raw water is passed through, the hardness of the water after softening is only a few ppm, and soft water can be obtained continuously even if the amount of water passed through increases. Comparing the embodiment and the comparative example, it can be seen that the embodiment can maintain the softening performance for a longer period of time. In the embodiment, when performing the softening treatment, in the first softening tank 3a, exchange occurs between the hardness components contained in the raw water and the hydrogen ions adsorbed on the first weakly acidic cation exchange resin 7a, and the hydrogen ions are released. Since the flow path length of the first softening tank 3a is shorter than the flow path length of the softening tank 3c, the water flows out of the first softening tank 3a before the acidification of the water progresses and flows into the first neutralization tank 4a. The hydrogen ions are removed from the acidic water that flows in by the first weakly basic anion exchange resin 8a, and the water becomes neutral. Thereafter, the water is softened again by passing through the second softening tank 3b, and acidified soft water can be obtained. By passing the acidified soft water through the second neutralization tank 4b, neutral soft water that can be used as water for daily use can be obtained.

[0104] That is, in the embodiment, the pH of the water flowing through the water softening tank 3 can be suppressed from decreasing compared to the comparative example, and the exchange between the hardness components and the hydrogen ions held by the weakly acidic cation exchange resin 7 can be easily performed. Therefore, in the embodiment, the water softening performance can be improved compared to the comparative example when the weakly acidic cation exchange resin 7 and the weakly basic anion exchange resin 8 of the same volume as in the comparative example are used by alternately providing the water softening tank 3 and the neutralization tank 4. In addition, when it is desired to obtain the same water softening performance as in the comparative example, the necessary volumes of the weakly acidic cation exchange resin 7 and the weakly basic anion exchange resin 8 can be reduced, so that the water softening device 1 can be made smaller and less expensive. Furthermore, when water containing a large amount of permanent hardness components (for example, sulfates such as calcium sulfate or chlorides such as magnesium chloride) is softened, the pH is more likely to decrease than water containing a large amount of temporary hardness components (for example, carbonates such as calcium carbonate) during softening. Therefore, in the comparative example in which softening and neutralization are performed once each, water containing a large amount of permanent hardness components causes a decrease in the softening performance of the water softening device 1. On the other hand, in the embodiment, the pH of the water, which has been lowered by the softening in the first water softening tank 3a, is neutralized in the first neutralization tank 4a, and then the water can be softened again in the second water softening tank 3b. Therefore, the water softening device 1 is less susceptible to the effects of the raw water quality (the proportion of permanent hardness in the hardness components) compared to the comparative example, and can obtain high water softening performance regardless of the raw water quality.

[0105] As described above, according to the water softening device 1 according to the first embodiment, the following effects can be obtained.

[0106] (1) The water softening device 1 includes a water softening tank 3 and a neutralization tank 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. The water softening tank 3 includes a first water softening tank 3a and a second water softening tank 3b. The neutralization tank 4 includes a first neutralization tank 4a and a second neutralization tank 4b. The water softening device 1 is configured so that the raw water flows through the first water softening tank 3a, the first neutralization tank 4a, the second water softening tank 3b, and the second neutralization tank 4b in this order.

[0107] According to this configuration, 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 softening treatment in the first water softening tank 3a, is neutralized in the first neutralization tank 4a, and is softened in the second water softening tank 3b. Therefore, compared to the conventional water softening device 1c in which the softening tank 3c and the neutralization tank 4c are each configured separately, the pH of the water flowing through the water softening tank 3 can be suppressed from decreasing and becoming acidic, so that the hardness components are more likely to be exchanged with the hydrogen ions held by the second weakly acidic cation exchange resin 7b of the second water softening tank 3b. Therefore, the water softening device 1 can improve the water softening performance compared to the conventional water softening device 1c. It is to be noted that the water softening performance can be improved when the weakly acidic cation exchange resin 7 and the weakly basic anion exchange resin 8 are used in the same volume as those of the conventional water softening device 1c.

[0108] (2) The water softener 1 further includes an electrolytic cell 9 that generates acidic electrolyzed water for regenerating the weakly acidic cation exchange resin 7 in the water softening cell 3 and alkaline electrolyzed water for regenerating the weakly basic anion exchange resin 8 in the neutralization cell 4, and a treatment cell 11 that mixes the acidic electrolyzed water that has flowed through the water softening cell 3 with the alkaline electrolyzed water that has flowed through the neutralization cell 4 and supplies the mixed water to the electrolytic cell 9. With this configuration, the weakly acidic cation exchange resin 7 can be regenerated by the acidic electrolyzed water generated in the electrolytic cell 9, and the weakly basic anion exchange resin 8 can be regenerated by the alkaline electrolyzed water. This reduces the frequency of maintenance of the water softener 1, and allows the water softener 1 to be used for a long period of time.

[0109] (3) In the water softening device 1, during the regeneration process for regenerating the weakly acidic cation exchange resin 7, the acidic electrolyzed water discharged from the electrolytic cell 9 flows through the second water softening cell 3b and then through the first water softening cell 3a. In this way, during the regeneration process, the acidic electrolyzed water discharged from the electrolytic cell 9 flows into the second water softening cell 3b, which has a smaller amount of adsorbed hardness components than the first water softening cell 3a, and the acidic electrolyzed water containing the hardness components is discharged to the first water softening cell 3a. In the regeneration of the second weakly acidic cation exchange resin 7b in the second water softening cell 3b, the consumption of hydrogen ions in the acidic electrolyzed water is small, that is, the reduction in hydrogen ion concentration can be suppressed compared to the regeneration of the first water softening cell 3a. Therefore, the acidic electrolyzed water containing a large amount of hydrogen ions flows into the first water softening cell 3a, and the re-adsorption of the hardness components in the first water softening cell 3a can be suppressed. Therefore, the decrease in the efficiency of the regeneration process can be suppressed, and the regeneration time can be shortened.

[0110] In addition, since the acidic electrolyzed water discharged from the electrolytic cell 9 flows into the second water softening cell 3b, which has a smaller amount of adsorbed hardness components than the first water softening cell 3a, and the acidic electrolyzed water containing hardness components is discharged to the first water softening cell 3a, it can be said that the amount of hardness components discharged by regeneration from the second water softening cell 3b is smaller than that of the first water softening cell 3a. Therefore, since the acidic electrolyzed water contains fewer hardness components when introduced from the second water softening cell 3b compared to when introduced from the first water softening cell 3a, it can be said that the re-adsorption of the hardness components in the first water softening cell 3a can be suppressed, and the decrease in the efficiency of the regeneration process can be suppressed, and the regeneration time can be shortened.

[0111] (4) The water softener 1 is configured such that, during regeneration, acidic electrolyzed water is introduced into the first water softener tank 3a and the second water softener tank 3b from the downstream side of the first water softener tank 3a and the second water softener tank 3b. Thus, during regeneration, the acidic electrolyzed water sent from the electrolytic tank 9 flows into the water softener tank 3 from the downstream side where less hardness components are adsorbed, and the water softener tank 3 is regenerated. During regeneration of the weakly acidic cation exchange resin 7 on the downstream side, the hydrogen ions in the acidic electrolyzed water are consumed less, that is, the reduction in the hydrogen ion concentration of the acidic electrolyzed water can be suppressed, and the hardness components contained in the acidic electrolyzed water from the downstream side can be suppressed from being re-adsorbed on the upstream side. Therefore, the decrease in the efficiency of regeneration of the water softener tank 3 can be suppressed, and the regeneration time can be shortened.

[0112] In addition, since the acidic electrolyzed water discharged from the electrolytic cell 9 flows in from the downstream side, where the amount of adsorbed hardness components is smaller, and regenerates the water softening cell 3, it can be said that the amount of hardness components discharged due to regeneration of the weakly acidic cation exchange resin 7 on the downstream side is smaller than that on the upstream side. Therefore, compared to the case where the acidic electrolyzed water is introduced from the upstream side, it can be said that the hardness components can be prevented from being re-adsorbed on the weakly acidic cation exchange resin 7 on the upstream side when the acidic electrolyzed water is introduced from the downstream side, and therefore the decrease in the efficiency of the regeneration process can be prevented, and the regeneration time can be shortened.

[0113] (5) In the water softening device 1, the first neutralization tank 4a is configured so that the acidic water flowing out of the first water softening tank 3a flows into it during the water softening process. This allows the first neutralization tank 4a to neutralize the hydrogen ions generated from the first water softening tank 3a. This makes it possible to suppress the inflow of acidic water into the second water softening tank 3b, into which the water flowing out of the first neutralization tank 4a flows. This makes it possible to soften water in the second water softening tank 3b without deteriorating the water softening performance of the second water softening tank 3b, improving the water softening performance.

[0114] (6) In the water softening device 1, the first water softening tank 3a and the second water softening tank 3b are configured to have the same flow path length, flow path cross-sectional area, volume of resin filled in the water softening tank 3, and type of resin filled in the water softening tank 3. This allows the first water softening tank 3a and the second water softening tank 3b to be configured using the same materials, thereby reducing the cost of the water softening device 1.

[0115] (7) In the water softening device 1, the first neutralization tank 4a and the second neutralization tank 4b are configured to have the same flow path length, flow path cross-sectional area, volume of resin filled in the neutralization tank 4, and type of resin filled in the neutralization tank 4. With this configuration, the first neutralization tank 4a and the second neutralization tank 4b can be configured from the same materials, thereby reducing the cost of the water softening device 1.

[0116] The present invention has been described above based on the embodiments. These embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of each component or each treatment process, and that such modifications are also within the scope of the present invention.

[0117] In the water softening device 1 according to the first embodiment, there are two water softening tanks 3 and two neutralization tanks 4, but this is not limited to the above. For example, there may be three of each, or more. This increases the number of times that water softening and neutralization are alternately performed during the water softening process, thereby further improving the water softening performance.

[0118] In the water softening device 1 according to the first embodiment, the first water softening tank 3a and the second water softening tank 3b have the same flow path length and flow path cross-sectional area, but this is not limited to the above. For example, the flow path length or the flow path cross-sectional area may be different, or both the flow path length and the flow path cross-sectional area may be different. Even in this case, the same effect as in the first embodiment can be obtained.

[0119] In the water softener 1 according to the first embodiment, the first weakly acidic cation exchange resin 7a filled in the first water softening tank 3a and the second weakly acidic cation exchange resin 7b filled in the second water softening tank 3b are equal in volume, but this is not limited thereto. For example, the first weakly acidic cation exchange resin 7a and the second weakly acidic cation exchange resin 7b may have different volumes, or different types of weakly acidic cation exchange resins 7 may be used. This allows the water softening performance to be adjusted, and a water softener 1 having water softening performance suited to the purpose can be obtained.

[0120] In the water softening device 1 according to the first embodiment, the first neutralization tank 4a and the second neutralization tank 4b have the same flow path length and flow path cross-sectional area, but this is not limited to this. For example, the flow path length or the flow path cross-sectional area may be different, or both the flow path length and the flow path cross-sectional area may be different. Even in this case, the same effect as in the first embodiment can be obtained.

[0121] In the water softener 1 according to the first embodiment, the first weakly basic anion exchange resin 8a filled in the first neutralization tank 4a and the second weakly basic anion exchange resin 8b filled in the second neutralization tank 4b are equal in volume, but this is not limited thereto. For example, the first weakly basic anion exchange resin 8a and the second weakly basic anion exchange resin 8b may have different volumes, or different types of weakly basic anion exchange resins 8 may be used. However, the volume of the second weakly basic anion exchange resin 8b filled in the second neutralization tank 4b may be sufficient to adsorb the hydrogen ions released from the second water softening tank 3b and turn the acidic soft water flowing from the second water softening tank 3b into neutral soft water. This allows the softening performance to be adjusted, and the water softener 1 having the softening performance according to the purpose can be obtained.

[0122] In the water softening device 1 according to the first embodiment, the acidic electrolyzed water is passed through the second water softening tank 3b and then through the first water softening tank 3a, but this is not a limitation. For example, the acidic electrolyzed water may be passed through the first water softening tank 3a and then through the second water softening tank 3b. Furthermore, in the water softening device 1 according to the first embodiment, the acidic electrolyzed water is passed through the water softening tank 3 from the downstream side, but it may be passed through the water softening tank 3 from the upstream side. This also allows the regeneration process of the water softening tank 3 to be performed.

[0123] In the water softening device 1 according to the first embodiment, the acidic electrolyzed water is passed through the second water softening tank 3b and then through the first water softening tank 3a in this order, but this is not a limitation. For example, a first regenerator and a second regenerator having the same function as the regenerator 6 may be used to perform the regeneration process in separate flow paths. This allows the first water softening tank 3a and the second water softening tank 3b to be regenerated independently, thereby shortening the time required for the regeneration process.

[0124] In the water softener 1 according to the first embodiment, the regeneration process is performed when the time period specified by the control unit 15 is reached or the water softening process has exceeded a certain time, but the present invention is not limited to this. For example, an ion concentration detector may be provided downstream of the second neutralization tank 4b and upstream of the on-off valve 45, and the ion concentration detector may constantly detect the ion concentration (e.g., hardness component concentration) of the soft water flowing through the flow path 24, and the regeneration process may be performed not only when the time period specified by the control unit 15 is reached or the water softening process has exceeded a certain time, but also when the ion concentration exceeds a preset reference value. This makes it possible to determine whether or not to perform the regeneration process based on the ion concentration of the water after it has flowed through the second neutralization tank 4b. Therefore, the state of the weakly acidic cation exchange resin 7 in the water softening tank 3 can be determined more accurately, and the weakly acidic cation exchange resin 7 and the weakly basic anion exchange resin 8 can be regenerated at an appropriate timing.

[0125] In the water softening device 1 according to the first embodiment, in the cleaning process (during cleaning), the raw water is introduced from the inlet 2 through the water softening tank 3, the neutralization tank 4, the second recovery passage 36, and the treatment tank 11 into the electrolytic tank 9, but this is not limited thereto. For example, the raw water may be circulated through the first recovery passage 35 instead of the second recovery passage 36. This makes it possible to collect the acidic electrolyzed water containing hardness components remaining in the first recovery passage 35. [Industrial Applicability]

[0126] The water softening device according to the present invention can be applied to a point-of-use (POU) water purification device or a point-of-entry (POE) water purification device. [Explanation of symbols]

[0127] 1 Water softener 1c water softener 2 Inlet 3 Water softening tank 3a First water softening tank 3b Second water softening tank 3c water softening tank 4 Neutralization tank 4a First neutralization tank 4b Second neutralization tank 4c Neutralization tank 5. Water Intake 6 Playback device 7. Weakly acidic cation exchange resin 7a First weakly acidic cation exchange resin 7b Second weakly acidic cation exchange resin 7c 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 8c Weakly basic anion exchange resin 9 Electrolytic cell 10 electrodes 11 Treatment tank 12 Water Pump 13 Filtration section 14 Air vent valve 15 Control section 20 Flow Path 21 Flow Path 22 Flow Path 23 Flow Path 24 Flow Path 30 Circulation flow path 30a First circulation flow path 30b Second circulation flow path 31 First supply channel 32 Second supply channel 33 First bypass channel 34 Second bypass flow path 35 First recovery channel 36 Second recovery channel 40 Water 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 61 On-off valve 62 On-off valve

Claims

1. a water softening tank for softening raw water containing hardness components using a weakly acidic cation exchange resin; a neutralization tank for neutralizing the softened water that has passed through the softening tank with a weakly basic anion exchange resin; A water softening device comprising: an electrolytic cell for producing acidic electrolyzed water for regenerating the weakly acidic cation exchange resin in the water softening cell, and alkaline electrolyzed water for regenerating the weakly basic anion exchange resin in the neutralization cell; a treatment tank for mixing the acidic electrolyzed water that has passed through the softening tank and the alkaline electrolyzed water that has passed through the neutralization tank and supplying the resulting mixture to the electrolysis tank; The water softening tank includes a first water softening tank and a second water softening tank, The neutralization tank includes a first neutralization tank and a second neutralization tank, A water softening apparatus characterized in that the raw water is configured to flow through the first water softening tank, the first neutralization tank, the second water softening tank, and the second neutralization tank in this order.

2. 2. The water softening device according to claim 1, characterized in that, during a regeneration process for regenerating the weakly acidic cation exchange resin, the acidic electrolyzed water discharged from the electrolytic cell is configured to flow through the second water softening cell and then through the first water softening cell.

3. 3. The water softening device according to claim 2, characterized in that, during the regeneration treatment, the acidic electrolyzed water is introduced into the first water softening tank and the second water softening tank from downstream of the first water softening tank and the second water softening tank.

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