Water softening device

Abstract

To provide a water softening device capable of suppressing a decline in water softening performance.SOLUTION: A water softening device 1 includes a water softening tank for softening raw water containing hardness component by a weakly acidic cation exchange resin, a neutralization tank for neutralizing softened water that has passed through the water softening tank by a weakly basic anion exchange resin, an electrolysis tank 9 for generating alkaline electrolyzed water used for regeneration of the weakly basic anion exchange resin, a capture part 10 for capturing precipitates contained in the alkaline electrolyzed water, a hydroxide ion concentration measuring part 55 for obtaining the hydroxide ion concentration of the alkaline electrolytic water, a flow rate adjustment part 56 for adjusting the flow rate of the alkaline electrolyzed water. The flow rate adjustment part 56 reduces the flow rate of the alkaline electrolytic water to a lower flow rate value when the hydroxide ion concentration exceeds a hydroxide ion concentration standard value.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] In a conventional water softening device, as a method for regenerating a cation exchange resin that does not use salt, a method of regenerating the cation exchange resin with acidic electrolyzed water generated by electrolysis is known (see, for example, 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. And the raw water softened by the weakly acidic cation exchange resin contains hydrogen ions and is acidic. The hydrogen ions in this soft water are adsorbed by the weakly basic anion exchange resin, whereby the raw water softened thereby is neutralized. In a conventional water softening device, as a method for regenerating a weakly basic anion exchange resin, a method of regenerating the weakly basic anion exchange resin with alkaline electrolyzed water generated by electrolysis is known (see, for example, 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, as the regeneration of the weakly acidic cation exchange resin and the weakly basic anion exchange resin progresses, hardness components (for example, calcium ions, magnesium ions) are released from the water softening tank. Due to the released hardness components, the concentration of hardness components in the acidic electrolyzed water and the alkaline electrolyzed water increases. When the water with an increased hardness component concentration flows into the electrolysis cell, calcium carbonate or magnesium hydroxide is likely to precipitate in the cathode chamber of the electrolysis cell where electrolysis is performed when generating acidic electrolyzed water and alkaline electrolyzed water. When the generated precipitate flows into the ion exchange resin, the water softening performance deteriorates. Therefore, it is conceivable to provide a trapping section for trapping the precipitate between the electrolysis cell and the ion exchange resin.

[0005] However, when the precipitate cannot be completely trapped by the trapping section, there is a problem that the untrapped precipitate flows into the ion exchange resin and the water softening performance deteriorates.

[0006] The present invention solves the above conventional problems and aims to provide a water softening device capable of suppressing a decrease in water softening performance.

Means for Solving the Problems

[0007] To achieve this object, the water softening device according to the present invention includes a water softening tank that softens raw water containing hardness components with a weakly acidic cation exchange resin, a neutralization tank that neutralizes the softened water that has passed through the water softening tank with a weakly basic anion exchange resin, an electrolysis cell that generates alkaline electrolyzed water used for regenerating the weakly basic anion exchange resin, a trapping section that traps the precipitate contained in the alkaline electrolyzed water, a hydroxide ion concentration measurement section that acquires the hydroxide ion concentration of the alkaline electrolyzed water, and a flow rate adjustment section that adjusts the flow rate of the alkaline electrolyzed water. The flow rate adjustment section reduces the flow rate of the alkaline electrolyzed water to a reduced flow rate value when the hydroxide ion concentration exceeds a hydroxide ion concentration reference value. Thereby, the intended object is achieved.

Effects of the Invention

[0008] According to the present invention, it is possible to provide a water softening device capable of suppressing a decrease in water softening performance.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

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Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. 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.

[0011] (Embodiment 1) Referring 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. In FIG. 1, each element of the water softening device 1 is conceptually shown.

[0012] (Overall Configuration) The water softening device 1 is a device that generates neutral softened water from raw water containing hardness components supplied from the outside. Here, neutral includes not only the case where the pH (hydrogen ion concentration index) is 7, but also the case where the pH is about 6 to 8. The raw water is water (water to be treated) introduced into the device from the inlet 2, for example, tap water or well water. The raw water contains hardness components (calcium ions or magnesium ions). By performing water softening treatment using the water softening device 1, neutral softened water with reduced hardness can be obtained, and softened water can be used even in areas where the hardness of the raw water is high.

[0013] Specifically, as shown in FIG. 1, the water softening device 1 includes an inlet 2, water softening tanks (first water softening tank 3 and second water softening tank 5), neutralization tanks (first neutralization tank 4 and second neutralization tank 6), a water intake 7, a regeneration device 8, and a control unit 15.

[0014] Also, the water softening device 1 includes a drain port 13, a plurality of on-off valves (on-off valve 18, on-off valve 19, on-off valve 20, on-off valve 21, on-off valve 22, and on-off valve 23), and a plurality of flow path switching valves (flow path switching valves 24 to 27). Details of these will be described later.

[0015] In the water softening device 1, in the water softening process for performing water softening treatment, the raw water supplied from the outside flows in the order of the inlet 2, the flow path 28, the first water softening tank 3, the flow path 29, the first neutralization tank 4, the flow path 30, the second water softening tank 5, the flow path 31, the second neutralization tank 6, the flow path 32, and the water intake 7, and is discharged as neutral soft water.

[0016] (Inlet and water intake) The inlet 2 is connected to the source of the raw water. The inlet 2 is an opening for introducing the raw water into the water softening device 1.

[0017] The water intake 7 is an opening that circulates inside the water softening device 1 and supplies the softened water that has undergone water softening treatment outside the water softening device 1. The water softening device 1 can take out the water after the water softening treatment from the water intake 7 by the pressure of the raw water flowing in from the inlet 2.

[0018] (Water softening tank) The water softening tanks (the first water softening tank 3 and the second water softening tank 5) soften the raw water containing hardness components by the action of the weakly acidic cation exchange resin 33. Specifically, the water softening tanks exchange the cations (calcium ions, magnesium ions), which are the hardness components contained in the flowing water (raw water), with hydrogen ions. As a result, the hardness of the raw water decreases and the raw water is softened.

[0019] The first water softening tank 3 softens the raw water flowing in from the inlet 2. The first water softening tank 3 is provided with a flow path switching valve 24. Details about the flow path switching valve will be described later in summary.

[0020] The second water softening tank 5 softens the water that has flowed through the first neutralization tank 4 described later. The second water softening tank 5 is provided with a flow path switching valve 26.

[0021] The first water softening tank 3 and the second water softening tank 5 are filled with the weakly acidic cation exchange resin 33.

[0022] The weakly acidic cation exchange resin 33 is an ion exchange resin having hydrogen ions at the ends of its functional groups. The weakly acidic cation exchange resin 33 adsorbs cations (calcium ions, magnesium ions), which are hardness components contained in the raw water passed through it, and releases hydrogen ions. The soft water treated with the weakly acidic cation exchange resin 33 contains a large amount of hydrogen ions that have been exchanged with the hardness components. That is, the soft water flowing out from the first soft water tank 3 and the second soft water tank 5 is soft water (acidic soft water) containing a large amount of hydrogen ions and acidified.

[0023] Since the ends of the functional groups of the weakly acidic cation exchange resin 33 are hydrogen ions, in the regeneration process described later, the weakly acidic cation exchange resin 33 can be regenerated using acidic electrolyzed water. At this time, cations, which are hardness components taken in during the softening treatment, are released from the weakly acidic cation exchange resin 33.

[0024] There are no particular restrictions on the weakly acidic cation exchange resin 33, and general-purpose ones can be used. For example, those having a carboxyl group (-COOH) as an exchange group can be mentioned. Also, those in which the counter ion of the carboxyl group, hydrogen ion (H+), is a cation such as a metal ion or an ammonium ion (NH4+) may be used.

[0025] (Neutralization tank) The neutralization tanks (the first neutralization tank 4 and the second neutralization tank 6) neutralize the pH of the acidic soft water containing hydrogen ions coming out of the soft water tank by the action of the weakly basic anion exchange resin 34 to obtain neutral soft water. Specifically, in the neutralization tank, the hydrogen ions contained in the soft water from the soft water tank are adsorbed by the weakly basic anion exchange resin 34 together with anions (negative ions), so that the pH of the soft water increases and neutral soft water can be obtained.

[0026] The first neutralization tank 4 neutralizes the acidic soft water that has flowed through the first soft water tank 3. The first neutralization tank 4 is provided with a flow path switching valve 25.

[0027] The second neutralization tank 6 neutralizes the acidic soft water that has flowed through the second soft water tank 5. The second neutralization tank 6 is provided with a flow path switching valve 27.

[0028] The first neutralization tank 4 and the second neutralization tank 6 are filled with weakly basic anion exchange resin 34.

[0029] The weakly basic anion exchange resin 34 neutralizes the hydrogen ions contained in the water flowing through it to produce neutral water. The weakly basic anion exchange resin 34 can be regenerated using alkaline electrolyzed water in the regeneration process described later.

[0030] There are no particular restrictions on the weakly basic anion exchange resin 34, and general-purpose ones can be used. For example, those in the free base form can be mentioned.

[0031] (Regeneration device) The regeneration device 8 is a device that regenerates the weakly acidic cation exchange resin 33 filled in the first soft water tank 3 and the second soft water tank 5, and also regenerates the weakly basic anion exchange resin 34 filled in the first neutralization tank 4 and the second neutralization tank 6.

[0032] The regeneration device 8 includes an electrolytic cell 9, a capture unit 10, a first water supply pump 11, a second water supply pump 12, a hydroxide ion concentration measurement unit 55, and a flow rate adjustment unit 56. And the regeneration device 8 is connected to the second soft water tank 5, the second neutralization tank 6, the flow path 28, and the flow path 29 by a first supply flow path 35, a second supply flow path 36, a first recovery flow path 37, and a second recovery flow path 38, respectively. Details of each flow path will be described later. Note that the first supply flow path 35, the second supply flow path 36, the first recovery flow path 37, the second recovery flow path 38, the neutralization tank bypass flow path 42, and the soft water tank bypass flow path 44 form a soft water tank regeneration circulation flow path 39 and a neutralization tank regeneration circulation flow path 40 described later.

[0033] ((Electrolytic cell)) The electrolytic cell 9 electrolyzes the incoming water (the water supplied from the inlet 2) using a pair of electrodes 41 (electrode 41a and electrode 41b) provided inside, to generate and discharge acidic electrolyzed water and alkaline electrolyzed water. More specifically, at the electrode 41a that becomes the anode during the electrolysis in the regeneration process, hydrogen ions are generated by electrolysis, and acidic electrolyzed water is produced. Also, at the electrode 41b that becomes the cathode during the electrolysis in the regeneration process, hydroxide ions are generated by electrolysis, and alkaline electrolyzed water is produced. Then, the electrolytic cell 9 supplies the acidic electrolyzed water to the first soft water tank 3 and the second soft water tank 5 via the first supply flow path 35 and the neutralization tank bypass flow path 42, and supplies the alkaline electrolyzed water to the first neutralization tank 4 and the second neutralization tank 6 via the second supply flow path 36 and the soft water tank bypass flow path 44. Although details will be described later, the acidic electrolyzed water generated by the electrolytic cell 9 is used for the regeneration of the weakly acidic cation exchange resin 33 in the first soft water tank 3 and the second soft water tank 5, and the alkaline electrolyzed water generated by the electrolytic cell 9 is used for the regeneration of the weakly basic anion exchange resin 34 in the first neutralization tank 4 and the second neutralization tank 6. Note that the electrolytic cell 9 is configured to be able to control the energization state to the pair of electrodes 41 by a control unit 15 described later.

[0034] ((Water supply pump)) The first water supply pump 11 is a device that circulates acidic electrolyzed water through the soft water tank regeneration circulation flow path 39 (see FIG. 3) during the regeneration process by the regeneration device 8. The first water supply pump 11 is provided in the first recovery flow path 37 that communicatively connects between the first soft water tank 3 and the electrolytic cell 9. Such an arrangement is for the first water supply pump 11 alone to easily circulate the acidic electrolyzed water through the soft water tank regeneration circulation flow path 39.

[0035] The second water supply pump 12 is a device that circulates alkaline electrolyzed water through the neutralization tank regeneration circulation flow path 40 (see FIG. 3). The second water supply pump 12 is provided in the second recovery flow path 38 that communicatively connects between the first neutralization tank 4 and the electrolytic cell 9. Such an arrangement is because the second water supply pump 12 alone can easily circulate the alkaline electrolyzed water through the neutralization tank regeneration circulation flow path 40.

[0036] Further, the first water supply pump 11 and the second water supply pump 12 are communicably connected to a control unit 15, which will be described later, either wirelessly or by wire. As the water supply pumps (the first water supply pump 11 and the second water supply pump 12), for example, a centrifugal pump or the like that can supply the required flow rates of a soft water tank regeneration circulation flow path 39 and a neutralization tank regeneration circulation flow path 40, which will be described later, during the regeneration process can be used.

[0037] ((Capture unit)) The capture unit 10 is provided in a second supply flow path 36 that communicably connects the electrolytic cell 9 and the second neutralization tank 6.

[0038] The capture unit 10 captures the precipitates contained in the alkaline electrolyzed water sent out from the electrolytic cell 9. The precipitate is a reaction product generated by the reaction of the hardness components, which are cationic ions released from the first soft water tank 3 and the second soft water tank 5 during the regeneration process, with the alkaline electrolyzed water in the electrolytic cell 9. More specifically, while water electrolysis is being performed in the electrolytic cell 9, the hardness components (for example, calcium ions, magnesium ions) released from the first soft water tank 3 and the second soft water tank 5 during the regeneration process move to the cathode (electrode 41b) side. Since alkaline electrolyzed water is being generated on the cathode side, the hardness components react with the alkaline electrolyzed water to form precipitates. For example, when the hardness component is calcium ions, reactions occur such as the formation of calcium carbonate or the formation of calcium hydroxide by mixing with the alkaline electrolyzed water. Then, the precipitates derived from the hardness components are captured as precipitates by the capture unit 10 provided in the second supply flow path 36. By capturing the precipitates derived from the hardness components with the capture unit 10, it is possible to suppress the inflow and deposition of the precipitates into the second neutralization tank 6. Therefore, when restarting the softening treatment after the completion of the regeneration process, it is possible to suppress an increase in the hardness of the soft water sent out from the second neutralization tank 6, which is caused by the reaction of the precipitates deposited in the second neutralization tank 6 with the hydrogen ions released from the first soft water tank 3 and the second soft water tank 5 and their ionization.

[0039] Also, during the regeneration process, the alkaline electrolyzed water that has passed through the trapping unit 10 with precipitates derived from the hardness components circulates through the second neutralization tank 6 and the first neutralization tank 4, and then is electrolyzed again in the electrolytic cell 9 and used as alkaline electrolyzed water again for the regeneration of the weakly basic anion exchange resin 34. At this time, the hardness components contained in the acidic electrolyzed water are reduced compared to the case where the trapping unit 10 is not provided. That is, by trapping the precipitates in the trapping unit 10, the hardness of the acidic electrolyzed water is reduced, so that the hardness components flowing into the first soft water tank 3 and the second soft water tank 5 can be reduced, and the reduction in the regeneration efficiency of the weakly acidic cation exchange resin 33 can be suppressed.

[0040] Note that "the hardness components react" includes not only the case where all the hardness components react, but also the state in which components that do not react or components that do not exceed the solubility product are included.

[0041] The form of the trapping unit 10 is not limited as long as it can separate the precipitates generated by the reaction between the hardness components and the alkaline electrolyzed water. For example, forms using a cartridge-type filter, a filtration layer using granular filter media, a cyclone-type solid-liquid separator, a hollow fiber membrane, etc. can be mentioned.

[0042] As a commonly used means for the form of the trapping unit 10, a cartridge-type filter can be mentioned. As the cartridge-type filter, a deep filtration type such as a wound filter, a surface filtration type such as a pleat filter and a membrane filter, or a combination thereof can be used.

[0043] The coil filter corresponds to particle diameters of 1 to 150 micrometers and is mainly used as a pre-filter. There are pleated filters and membrane filters that correspond to a wide range of particle diameters of about 0.03 to 100 micrometers. However, particularly in the implementation of the present invention, it is preferable to use those with an accuracy of 0.5 micrometers or more in order to reduce the possibility of filter clogging. Also, in order to ensure the capture performance of precipitates, it is preferable to use those with an accuracy of 1.5 micrometers or less. Since alkaline electrolyzed water flows through the capture part 10 in the regeneration process described later and acidic electrolyzed water flows through it in the cleaning process, the material of the cartridge-type filter is preferably a material highly resistant to acids and alkalis (for example, polypropylene).

[0044] The granular filter medium used in the filtration layer aims to capture and remove hardness components. However, depending on the state of existence of particles having a surface potential that adsorbs to the granular filter medium, ions in the raw water, etc., particles with a particle diameter of about 1 to 10 micrometers or colority can also be removed. As the granular filter medium, filter sand, pellet-shaped fiber filter media, etc., filter media suitable for the object to be removed can be used. The material of the granular filter medium may be, for example, sand, anthracite, garnet, ceramics, granular activated carbon, iron oxyhydroxide, manganese sand, etc., as long as it has a hardness that does not easily deform under pressure and settles in water. For the particle diameter, for example, those with a particle diameter of 0.3 to 5.0 millimeters and a uniformity coefficient of 1.2 to 2.0 can be used.

[0045] In addition, the multi-layer filtration method of mixing and using multiple types of filter media with different specific gravities is a method of laminating particles of different sizes in order from small to large as the filtration layer. In the multi-layer filtration method, it is common to mix particles with a large specific gravity and a small size and particles with a small specific gravity and a large size to form a multi-layer structure. The multi-layer filtration method is preferable because it has advantages such as higher filtration efficiency per unit volume and lower head loss compared to using a single type of filter media. As the granular filter media, for example, garnet with a size of 0.3 millimeters, sand with a size of 0.6 millimeters, and anthracite with a size of 1.0 millimeters are mixed and used in a ratio of 2:1:1, but it is preferable to adjust the mixing ratio or particle diameter according to the particle characteristics of the turbidity.

[0046] The capture unit 10 includes an on-off valve 22 and a capture unit drain port 14.

[0047] The on-off valve 22 is a valve provided at the lower part of the capture unit 10 and is a valve that controls the drainage in the capture unit 10. By opening the on-off valve 22, the water in the capture unit 10 can be discharged outside the device from the capture unit drain port 14.

[0048] The capture unit drain port 14 is an opening for discharging the water in the capture unit 10 outside the device. By opening the on-off valve 22 provided upstream of the capture unit drain port 14, the water in the capture unit can be discharged outside the device from the capture unit drain port 14.

[0049] (On-off valve and flow path switching valve) A plurality of on-off valves (on-off valves 18 to 23) are respectively provided in each flow path and switch between an "open" state and a "closed" state in each flow path.

[0050] A plurality of on-off valves (on-off valves 18, 19, 21, and 23) start or stop the flow of water to each flow path by opening and closing the valves.

[0051] The on-off valves 20 and 22 are in an open state during the regeneration flow path cleaning process, electrolytic cell cleaning process, and capture unit cleaning process described later, and discharge the regenerated circulating water outside the device.

[0052] The plurality of flow path switching valves (flow path switching valves 24 to 27) are respectively provided in the first soft water tank 3, the second soft water tank 5, the first neutralization tank 4, and the second neutralization tank 6. Each of the plurality of flow path switching valves has three openings. The first opening is an inflow / outflow port through which water can flow in and out. The second opening functions as an inlet but does not function as an outlet. The third opening functions as an outlet but does not function as an inlet. In each of the plurality of flow path switching valves, the inflow / outflow port is always "open". Depending on the water flow direction, when one of the inlet or the outlet is "open", the other outlet is "closed". By providing the flow path switching valves 24 to 27, the number of on-off valves required for each flow path in the water softening device 1 can be reduced, and the cost of the water softening device 1 can be reduced.

[0053] Also, the plurality of on-off valves (on-off valves 18 to 23) and the plurality of flow path switching valves (flow path switching valves 24 to 27) are respectively connected to a control unit 15 described later so as to be communicable wirelessly or by wire.

[0054] ((Hydroxide ion concentration measurement unit)) The hydroxide ion concentration measurement unit 55 is provided in the second recovery flow path 38 that communicatively connects the first neutralization tank 4 and the electrolysis tank 9. Specifically, it is provided near the inlet on the cathode side of the electrolysis tank 9 in the neutralization tank regeneration circulation flow path 40. The hydroxide ion concentration measurement unit 55 measures the hydroxide ion concentration of the alkaline electrolyzed water after it has been used for regeneration during the regeneration process by the regeneration device 8. Specifically, it measures the hydroxide ion concentration of the alkaline electrolyzed water after the alkaline electrolyzed water sent out from the electrolysis tank 9 has passed through the second neutralization tank 6 and the first neutralization tank 4. There are no particular restrictions on the hydroxide ion concentration measurement unit 55, and general-purpose ones can be used. For example, a pH meter and a thermometer using the glass electrode method can be used. In this case, the hydrogen ion concentration corresponding to the measured pH value of the alkaline electrolyzed water is calculated from the pH value measured by the pH meter. Also, since the ion product of water, which is the product of the hydrogen ion concentration and the hydroxide ion concentration, is a constant value when the temperature is constant, the hydroxide ion concentration can be calculated from the ion product of water at that temperature.

[0055] Also, the hydroxide ion concentration measurement unit 55 is communicatively connected to a control unit 15, which will be described later, by wireless or wired means.

[0056] ((Flow rate adjustment unit)) The flow rate adjustment unit 56 controls the flow rate of the alkaline electrolyzed water passed through from the second water supply pump 12 during the regeneration process by the regeneration device 8. There are no particular restrictions on the flow rate adjustment method of the flow rate adjustment unit 56, and it can be changed according to the type of water supply pump and the actual configuration of the regeneration device 8. For example, a method of adjusting the flow rate by controlling the current value of the water supply pump can be mentioned. Also, the flow rate adjustment unit 56 is communicatively connected to a control unit 15, which will be described later, by wireless or wired means.

[0057] ((Pressure measurement unit)) The pressure measurement unit 57 is connected to the capture unit 10 and measures the upstream pressure of the alkaline electrolyzed water flowing into the capture unit 10 and the downstream pressure of the alkaline electrolyzed water flowing out of the capture unit 10 during the reproduction process by the reproduction device 8. Then, the pressure measurement unit 57 calculates the capture unit pressure loss, which is the difference between the upstream pressure and the downstream pressure. Note that the calculation of the capture unit pressure loss may also be performed by the control unit 15. There is no particular limitation on the method of measuring the pressure, and it can be changed according to the type of the capture unit 10 and the actual configuration of the reproduction device 8. For example, a method of measuring with an upstream pressure gauge that measures the pressure of the alkaline electrolyzed water flowing into the capture unit 10 and a downstream pressure gauge that measures the pressure of the alkaline electrolyzed water flowing out of the capture unit 10 can be mentioned. Further, the pressure measurement unit 57 is communicably connected to the control unit 15 described later by wireless or wired means.

[0058] ((Pump current value detection unit)) The pump current value detection unit 58 is a device that detects the current value of the second water supply pump 12. There is no particular limitation on the method of detecting the current value. For example, a method of connecting the current detection circuit and the second water supply pump 12 by wire and converting the potential difference across the shunt resistor into a current value using a shunt resistor can be mentioned. Further, the pump current value detection unit 58 is communicably connected to the control unit 15 described later by wireless or wired means.

[0059] ((Drain outlet)) The drain outlet 13 is an opening provided at the end of the drain channel 54 and is an opening for discharging the water inside the device to the outside of the device during the reproduction path cleaning process and the electrolytic cell cleaning process. A switching valve 20 is provided upstream of the drain outlet 13, and by opening the switching valve 20, drainage can be performed from the drain outlet 13.

[0060] ((Control unit)) The control unit 15 controls the execution of each process of the softening process, the reproduction process, the reproduction path cleaning process, the electrolytic cell cleaning process, and the capture unit cleaning process and the switching between the processes.

[0061] The control of the switching between processes specifically means that the control unit 15 controls the switching from the water softening process to the regeneration process, the switching from the regeneration process to the regeneration flow path cleaning process, the switching from the regeneration flow path cleaning process to the electrolytic cell cleaning process, the switching from the electrolytic cell cleaning process to the capture unit cleaning process, and the switching from the capture unit cleaning process to the water softening process.

[0062] In addition, the control unit 15 controls the on-off valves 20 and 22 and controls the drainage during the regeneration flow path cleaning process, the electrolytic cell cleaning process, and the capture unit cleaning process.

[0063] In addition, the control unit 15 controls the flow path switching valves 24 to 27, the on-off valves 18, 19, 21, and 23 and executes the switching of the flow path.

[0064] In addition, the control unit 15 is connected to the hydroxide ion concentration measurement unit 55, the pressure measurement unit 57, the pump current value detection unit 58, and the flow rate adjustment unit 56. Based on the hydroxide ion concentration of the alkaline electrolyzed water measured by the hydroxide ion concentration measurement unit 55, the upstream pressure of the alkaline electrolyzed water flowing into the capture unit and the capture unit pressure loss value which is the difference between the upstream pressure and the downstream pressure of the alkaline electrolyzed water flowing out of the capture unit measured by the pressure measurement unit 57, and the current value of the water supply pump measured by the pump current value detection unit 58, the control unit 15 controls the flow rate adjustment unit 56 to control the flow rate of the alkaline electrolyzed water flowing through the second water supply pump 12.

[0065] Referring to FIG. 8, the structure of the control unit 15 will be described. FIG. 8 is a conceptual diagram showing the configuration of the control unit 15 of the water softening device according to Embodiment 1.

[0066] The control unit 15 includes a hydroxide ion concentration storage unit 59, a hydroxide ion concentration comparison unit 60, a loss pressure storage unit 61, a discharge pressure calculation unit 62, and a pressure comparison unit 63.

[0067] (((Hydroxide Ion Concentration Storage Unit))) The hydroxide ion concentration memory unit 59 stores, as a hydroxide ion concentration reference value, the hydroxide ion concentration (for example, 10 -4 mol / L) at which magnesium hydroxide begins to be generated in the electrolytic cell 9 due to the reaction between the hardness component and the ions in the alkaline electrolyzed water generated in the electrolytic cell 9. The stored hydroxide ion concentration reference value is output to the hydroxide ion concentration comparison unit 60 described later and is used to determine whether the hydroxide ion concentration measured by the hydroxide ion concentration measurement unit 55 has reached the hydroxide ion concentration reference value.

[0068] Regarding the setting of the hydroxide ion concentration reference value, the adsorption amount of the hardness component with respect to the total amount of raw water passed through, particularly the adsorption amount of magnesium ions, is considered. The total amount of raw water passed through is the total amount of raw water passed through the soft water tanks (the first soft water tank 3 and the second soft water tank 5) during the softening treatment performed during the period from the end of the regeneration process to the start of the next regeneration process. The upper limit value of the magnesium ions released during the regeneration process is determined by the total amount of raw water passed through. Note that the upper limit value of the magnesium ions released during the regeneration process is equal to the total amount of magnesium ions adsorbed on the weakly acidic cation exchange resin. That is, the upper limit value of the magnesium ions released during the regeneration process is the total amount of magnesium ions adsorbed on the weakly acidic cation exchange resin during the softening treatment. In the regeneration process, not necessarily all of the magnesium ions adsorbed on the weakly acidic cation exchange resin are released. Therefore, it is preferable that the hydroxide ion concentration reference value be set to a value smaller than the hydroxide ion concentration that reacts with the total amount of magnesium ions adsorbed on the weakly acidic cation exchange resin. The hydroxide ion concentration memory unit 59 may be provided inside or outside the control unit 15.

[0069] (((Hydroxide Ion Concentration Comparison Unit))) The hydroxide ion concentration comparison unit 60 compares the hydroxide ion concentration reference value stored in the hydroxide ion concentration storage unit 59 with the hydroxide ion concentration measurement value measured by the hydroxide ion concentration measurement unit 55, and outputs the comparison result to the control unit 15. The comparison result indicates whether the hydroxide ion concentration measurement value is equal to or greater than the hydroxide ion concentration reference value or less than the hydroxide ion concentration reference value. The hydroxide ion concentration comparison unit 60 may be provided inside or outside the control unit 15.

[0070] (((Loss pressure storage unit))) The loss pressure storage unit 61 stores the loss pressure caused by the flow path other than the capture unit 10 (excluding the capture unit 10) in the flow path through which the alkaline electrolyzed water is supplied as the alkaline flow path loss pressure. In other words, the loss pressure storage unit 61 stores the loss pressure caused by the first neutralization tank 4, the second neutralization tank 6, the electrolysis tank 9, the second supply flow path 36, the second recovery flow path 38, the soft water tank bypass flow path 44, the flow path communicating with the hydroxide ion concentration measurement unit 55, and each component as the alkaline flow path loss pressure. The stored alkaline flow path loss pressure is output to the pressure comparison unit 63 described later, and is used to determine whether the discharge pressure of the second water supply pump 12 calculated by the discharge pressure calculation unit 62 described later is greater than the sum of the alkaline flow path loss pressure and the capture unit loss pressure measured by the pressure measurement unit 57. Note that the value of the alkaline flow path loss pressure is set to a value measured in advance. The loss pressure storage unit 61 may be provided inside or outside the control unit 15.

[0071] (((Discharge pressure calculation unit))) The discharge pressure calculation unit 62 calculates the discharge pressure of the second water supply pump 12 based on the current value of the second water supply pump 12 detected by the pump current value detection unit 58. The discharge pressure calculation unit 62 may be provided inside or outside the control unit 15.

[0072] (((Pressure comparison unit))) The pressure comparison unit 63 compares the sum of the alkaline flow path loss pressure and the capture unit loss pressure measured by the pressure measurement unit 57 with the discharge pressure of the second water pump 12 calculated by the discharge pressure calculation unit 62, and outputs the comparison result to the control unit 15. The comparison result indicates whether the discharge pressure of the second water pump 12 calculated by the discharge pressure calculation unit 62 is greater than or less than or equal to the sum of the loss pressure and the capture unit loss pressure measured by the pressure measurement unit 57. The pressure comparison unit 63 may be provided inside the control unit 15 or may be provided outside.

[0073] (Flow path) The flow path 53 is a flow path that communicatively connects the inlet 2 and the water intake 7, and an on-off valve 18 is provided on the flow path 53. Even when any of the regeneration process, the regeneration flow path cleaning process, the electrolytic cell cleaning process, and the capture unit cleaning process is being performed by the flow path 53, the user of the water softening device 1 can obtain raw water from the water intake 7.

[0074] (Water softening flow path) Referring to FIG. 2, the water softening flow path 43 formed during the water softening process of the water softening device 1 will be described. FIG. 2 is a configuration diagram showing the water softening flow path 43 of the water softening device 1.

[0075] The water softening flow path 43 (the diagonal arrow in FIG. 2) is a flow path for softening raw water. The raw water flowing through the water softening flow path 43 becomes neutral soft water and is discharged from the water intake 7 to the outside of the device.

[0076] The water softening flow path 43 is formed by the inlet 2, the flow path 28, the first water softening tank 3, the flow path 29, the first neutralization tank 4, the flow path 30, the second water softening tank 5, the flow path 31, the second water softening tank 5, the flow path 32, and the water intake 7.

[0077] The flow path 28 is a flow path that connects from the inlet 2 to the first water softening tank 3. That is, the flow path 28 is a flow path that guides raw water containing hardness components from the inlet 2 to the first water softening tank 3.

[0078] The flow path 29 is a flow path connecting the first soft water tank 3 to the first neutralization tank 4. That is, the flow path 29 is a flow path for guiding the water softened in the first soft water tank 3 to the first neutralization tank 4.

[0079] The flow path 30 is a flow path connecting the first neutralization tank 4 to the second soft water tank 5. That is, the flow path 30 is a flow path for guiding the water neutralized in the first neutralization tank 4 to the second soft water tank 5.

[0080] The flow path 31 is a flow path connecting the second soft water tank 5 to the second neutralization tank 6. That is, the flow path 31 is a flow path for guiding the water softened in the second soft water tank 5 to the second neutralization tank 6.

[0081] The flow path 32 is a flow path connecting the second neutralization tank to the water intake 7. That is, the flow path 32 is a flow path for guiding the softened raw water from the second neutralization tank 6 to the water intake 7.

[0082] As shown in FIG. 2, an on-off valve 19 is installed on the flow path 28 on the downstream side of the inlet 2 and the upstream side of the first soft water tank 3. Also, an on-off valve 18 is installed in the flow path 53 described later. By closing the on-off valve 18 and opening the on-off valve 19, the first soft water tank 3 and the inlet 2 are connected in communication. Also, the flow path switching valve 24 is switched so that the first soft water tank 3 and the first neutralization tank 4 are connected in communication, the flow path switching valve 25 is switched so that the second soft water tank 5 and the second neutralization tank 6 are connected in communication, the flow path switching valve 26 is switched so that the first neutralization tank 4 and the second soft water tank 5 are connected in communication, and the flow path switching valve 27 is switched so that the second soft water tank 5 and the second neutralization tank 6 are connected in communication. Thereby, a water softening flow path 43 is formed that connects the inlet 2, the flow path 28, the first soft water tank 3, the flow path 29, the first neutralization tank 4, the flow path 30, the second soft water tank 5, the flow path 31, the second neutralization tank 6, the flow path 32, and the water intake 7 in communication. At this time, the on-off valves 20, 21, and 23 are closed.

[0083] (Regeneration circulation flow path) Next, referring to FIG. 3, the soft water tank regeneration circulation passage 39 and the neutralization tank regeneration circulation passage 40 formed during the regeneration process of the softening water device 1 will be described. FIG. 3 is a configuration diagram showing the soft water tank regeneration circulation passage 39 and the neutralization tank regeneration circulation passage 40 of the softening water device 1.

[0084] First, the soft water tank regeneration circulation passage 39 will be described.

[0085] The soft water tank regeneration circulation passage 39 is a passage for regenerating the first soft water tank 3 and the second soft water tank 5 by allowing acidic electrolyzed water to flow during the regeneration process. As shown in FIG. 3 (white arrow), the water sent out by the first water pump 11 flows through the electrolytic cell 9, the second soft water tank 5, and the first soft water tank 3, and then returns to the electrolytic cell 9 for circulation.

[0086] Specifically, the soft water tank regeneration circulation passage 39 is composed of passages including an electrolytic cell 9, a second soft water tank 5, a first soft water tank 3, a first supply passage 35 connecting the first water pump 11, a neutralization tank bypass passage 42, and a first recovery passage 37.

[0087] The first supply passage 35 is a passage connecting the downstream side of the electrolytic cell 9 to the downstream side of the second soft water tank 5, and is a passage for supplying acidic electrolyzed water from the electrolytic cell 9 to the second soft water tank 5.

[0088] The neutralization tank bypass passage 42 is a passage that bypasses the first neutralization tank 4 and connects the upstream side of the second soft water tank 5 to the downstream side of the first soft water tank 3, and is a passage for supplying acidic electrolyzed water from the second soft water tank 5 to the first soft water tank 3.

[0089] The first recovery passage 37 is a passage connecting the upstream side of the first soft water tank 3 to the electrolytic cell 9, and is a passage for recovering the acidic electrolyzed water containing hardness components that has passed through the first soft water tank 3 and the second soft water tank 5 to the electrolytic cell 9. A first water pump 11 is provided in the first recovery passage 37.

[0090] Further, the soft water tank regeneration circulation passage 39 is a passage that introduces the acidic electrolyzed water sent from the electrolytic cell 9 into the first soft water tank 3 and the second soft water tank 5 from the downstream side of the first soft water tank 3 and the second soft water tank 5, and discharges it from the upstream side where the adsorption amount of the hardness component is larger than that on the downstream side of the softening tank. Here, the downstream side refers to the downstream side in the passage during the softening treatment.

[0091] Next, the neutralization tank regeneration circulation passage 40 will be described.

[0092] The neutralization tank regeneration circulation passage 40 is a passage for regenerating the first neutralization tank 4 and the second neutralization tank 6 by allowing the alkaline electrolyzed water to flow during the regeneration process. As shown in FIG. 3 (black arrow), the water sent by the second water pump 12 flows through the electrolytic cell 9, the second neutralization tank 6, and the first neutralization tank 4, and returns to the electrolytic cell 9 for circulation.

[0093] Specifically, the neutralization tank regeneration circulation passage 40 is composed of passages including the second supply passage 36 connecting the electrolytic cell 9, the second neutralization tank 6, the first neutralization tank 4, and the second water pump 12, the soft water tank bypass passage 44, and the second recovery passage 38.

[0094] The second supply passage 36 is a passage that communicatively connects from the downstream side of the electrolytic cell 9 to the downstream side of the second neutralization tank 6, and is a passage for supplying alkaline electrolyzed water from the electrolytic cell 9 to the second neutralization tank 6. The second supply passage 36 is provided with a capture portion 10, an on-off valve 21, and an on-off valve 23.

[0095] The soft water tank bypass passage 44 is a passage that bypasses the second soft water tank 5 and communicatively connects from the upstream side of the second neutralization tank 6 to the downstream side of the first neutralization tank 4, and is a passage for supplying alkaline electrolyzed water from the second neutralization tank 6 to the first neutralization tank 4.

[0096] The second recovery passage 38 is a passage that communicatively connects from the upstream side of the first neutralization tank 4 to the electrolytic cell 9, and is a passage for recovering the alkaline electrolyzed water that has passed through the first neutralization tank 4 and the second neutralization tank 6 to the electrolytic cell 9. The second recovery passage 38 is provided with the second water pump 12.

[0097] (Regeneration flow path cleaning flow path) Next, with reference to FIG. 4, the regeneration flow path cleaning flow path 45 formed during the regeneration flow path cleaning process of the water softening device 1 will be described. FIG. 4 is a configuration diagram showing the regeneration flow path cleaning flow path 45 of the water softening device 1.

[0098] The regeneration flow path cleaning flow path 45 is a flow path that discharges the highly hard water remaining in the flow path to the outside of the device without flowing into the first neutralization tank 4 and the second neutralization tank 6 during the regeneration flow path cleaning process described later. The regeneration flow path cleaning flow path 45 includes a first drainage flow path 46 and a second drainage flow path 47.

[0099] As shown in FIG. 4 (white arrow), the first drainage flow path 46 is composed of flow paths connecting the inlet 2 to the first water supply pump 11, the electrolytic cell 9, the on-off valve 20, and the drain port 13. Specifically, the first drainage flow path 46 is a flow path that allows the raw water flowing in from the inlet 2 to flow through the flow path 28, the first recovery flow path 37, the first water supply pump 11, the electrolytic cell 9, the drainage flow path 54, the on-off valve 20, and the drain port 13 in this order.

[0100] The drainage flow path 54 is a flow path connected to the first supply flow path 35 at one end and to the drain port 13 at the other end. An on-off valve 20 is provided in the drainage flow path 54. By opening the on-off valve 20, the water in the flow path can be drained to the outside of the device, and by closing the on-off valve 20, the drainage from the drain port 13 can be stopped.

[0101] As shown in FIG. 4 (black arrow), the second drainage flow path 47 is composed of flow paths connecting the inlet 2 to the first water softening tank 3, the second water softening tank 5, the on-off valve 20, and the drain port 13. Specifically, the second drainage flow path 47 is a flow path that allows the raw water flowing in from the inlet 2 to flow through the flow path 28, the first water softening tank 3, the neutralization tank bypass flow path 42, the second water softening tank 5, the first supply flow path 35, the on-off valve 20, and the drain port 13 in this order.

[0102] Note that the flow rate of the water flowing through the second drainage channel 47 is preferably controlled to be larger than the flow rate of the water flowing through the first drainage channel. Thereby, the high-hardness water in the second drainage channel, which is a channel including the water softening tank used during the water softening process, can be preferentially replaced with raw water. Therefore, the influence of the high-hardness water when starting the water softening process can be suppressed.

[0103] (Electrolytic cell cleaning channel) Next, with reference to FIG. 5, the electrolytic cell cleaning channel 49 formed during the electrolytic cell cleaning process of the water softening device 1 will be described. FIG. 5 is a configuration diagram showing the electrolytic cell cleaning channel 49 of the water softening device 1.

[0104] The electrolytic cell cleaning channel 49 is a channel for removing deposits caused by hardness components in the electrolytic cell 9 and the neutralization tank regeneration circulation channel 40 during the electrolytic cell cleaning process described later. The electrolytic cell cleaning channel 49 is configured to include a first drainage channel 46 and a third drainage channel 50.

[0105] As shown in FIG. 5 (black arrow), the third drainage channel 50 is constituted by channels that communicatively connect from the inlet 2 to the first water softening tank 3, the second water pump 12, the electrolytic cell 9, the on-off valve 21, the capture unit 10, the on-off valve 22, and the capture unit drain port 14. Specifically, the third drainage channel 50 allows the raw water flowing in from the inlet 2 to flow through the channels in the order of the channel 28, the first water softening tank 3, the second recovery channel 38, the second water pump 12, the electrolytic cell 9, the second supply channel 36, the on-off valve 21, the capture unit 10, and the on-off valve 22, and discharges it outside the device from the capture unit drain port 14. More specifically, in the third drainage channel 50, the raw water flowing in from the inlet 2 flows into the first water softening tank 3 through the channel 28 to become acidic soft water. The generated acidic soft water flows into the electrolytic cell 9 through the second recovery channel 38 via the second water pump 12. Thereafter, the acidic soft water flows through the second supply channel 36, the on-off valve 21, the capture unit 10, and the on-off valve 22 in this order, dissolves the deposits in the capture unit 10, and discharges it outside the device from the capture unit drain port 14.

[0106] (Capture unit cleaning channel) Next, referring to FIG. 6, the capture unit cleaning channel 51 formed during the capture unit cleaning process of the water softening device 1 will be described. FIG. 6 is a configuration diagram showing the capture unit cleaning channel 51 of the water softening device 1.

[0107] The capture unit cleaning channel 51 is a channel for removing deposits derived from hardness components deposited on the capture unit 10 during the capture unit cleaning process described later. The capture unit cleaning channel 51 is configured to include a fourth drainage channel 52.

[0108] As shown in FIG. 6, the capture unit cleaning channel 51 is composed of channels that communicatively connect from the inlet 2 to the first water softening tank 3, the first neutralization tank 4, the second water softening tank 5, the second neutralization tank 6, the capture unit 10, and the capture unit drainage port 14. Specifically, the capture unit cleaning channel 51 allows the raw water flowing in from the inlet 2 to flow through the channels 28, the first water softening tank 3, the channel 29, the first neutralization tank 4, the channel 30, the second water softening tank 5, the channel 31, the second neutralization tank 6, the second supply channel 36, the on-off valve 23, the capture unit 10, and the on-off valve 22 in this order, and is a channel for discharging to the outside of the device from the capture unit drainage port.

[0109] The above is the configuration of the water softening device 1.

[0110] Next, the operation of the water softening device 1 will be described.

[0111] (Water softening process, regeneration process, regeneration channel cleaning process, electrolytic cell cleaning process, and capture unit cleaning process) Next, referring to FIG. 7, the water softening process, regeneration process, regeneration channel cleaning process, electrolytic cell cleaning process, and capture unit cleaning process of the water softening device 1 will be described. FIG. 7 is a diagram showing the state during the operation of the water softening device 1.

[0112] In the water softening process, regeneration process, regeneration channel cleaning process, electrolytic cell cleaning process, and capture unit cleaning process, as shown in FIG. 7, the control unit 15 controls the on-off valves 18 to 23, the channel switching valves 24 to 27, the electrodes 41 of the electrolytic cell 9, the first water pump 11, and the second water pump 12 to switch to their respective flow states.

[0113] Here, "ON" in FIG. 7 indicates the state where the corresponding on-off valve is "open", the electrode 41 is energized, and the corresponding water supply pump is operating. The blank spaces indicate the state where the corresponding on-off valve is "closed", the electrode 41 is not energized, and the corresponding water supply pump is stopped.

[0114] Also, "(from component number) to (component number)" in FIG. 7 indicates the state where the corresponding flow path switching valve connects the flow path in the direction of water supply from the corresponding component to the corresponding component. For example, the flow path switching valve 24 in the water softening process connects each flow path so that water can be supplied from the flow path 28 to the flow path 29.

[0115] Also, "(to component number)" in FIG. 7 indicates the state where the corresponding flow path switching valve connects the flow path in the direction in which water may be supplied to the corresponding component. At this time, although the flow paths are connected, since it is an environment where it is difficult for water to flow in and out of the water softening tank or the neutralization tank provided with the corresponding flow path switching valve, water supply from the corresponding flow path switching valve is extremely unlikely to occur.

[0116] (Water softening process) First, the operation during the water softening process by the water softening device 1 will be described with reference to the "During water softening" column in FIGS. 2 and 7.

[0117] In the water softening device 1, as shown in FIG. 7, in the water softening process, with the on-off valve 18 closed, the on-off valve 19 provided in the flow path 28 is opened. As a result, raw water containing hardness components flows in from the outside. Since the inflowing raw water circulates in the order of the first water softening tank 3, the first neutralization tank 4, the second water softening tank 5, and the second neutralization tank 6, the water softening device 1 can take out softened water (neutral soft water) from the water intake 7. At this time, the flow path switching valve 24 is in a connection state where water can be sent from the flow path 28 to the flow path 29, the flow path switching valve 25 is in a connection state where water can be sent from the flow path 29 to the flow path 30, the flow path switching valve 26 is in a connection state where water can be sent from the flow path 30 to the flow path 31, and the flow path switching valve 27 is in a connection state where water can be sent from the flow path 31 to the flow path 32. The on-off valves 20 to 23 are all in a closed state. Also, the operations of the electrodes 41 of the electrolytic cell 9, the first water pump 11, and the second water pump 12 are stopped.

[0118] Specifically, as shown in FIG. 1, in the water softening process, due to the pressure of the raw water flowing in from the outside, the raw water is supplied from the inlet 2 through the flow path 28 to the first water softening tank 3. Then, the raw water supplied to the first water softening tank 3 circulates through the weakly acidic cation exchange resin 33 provided in the first water softening tank 3. At this time, the cations, which are the hardness components in the raw water, are adsorbed by the action of the weakly acidic cation exchange resin 33, and hydrogen ions are released (ion exchange occurs). Then, 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 flowed out, so it is acidified and becomes acidic water (first soft water) with a low pH. Here, water containing a large amount of permanent hardness components (for example, sulfates such as calcium sulfate or chlorides such as magnesium chloride) as hardness components 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 is performed. Since softening is difficult to proceed in a state where the pH has decreased, the water that has passed through the first water softening tank 3 is passed through the first neutralization tank 4 for neutralization.

[0119] The softened water flows through the flow path 29 via the flow path switching valve 24 provided in the first soft water tank 3 and flows into the first neutralization tank 4. In the first neutralization tank 4, hydrogen ions contained in the softened water are adsorbed by the action of the weakly basic anion exchange resin 34. That is, since hydrogen ions are removed from the water softened by the first soft water tank 3, the decreased pH rises and is neutralized. Therefore, compared with the case where the water softened in the first soft water tank 3 is directly softened in the second soft water tank 5, the softening treatment in the second soft water tank 5 proceeds more easily.

[0120] The water (neutralized first soft water) neutralized by the first neutralization tank 4 flows through the flow path 30 via the flow path switching valve 25 provided in the first neutralization tank 4 and flows into the second soft water tank 5. In the second soft water tank 5, cations as hardness components are adsorbed and hydrogen ions are released by the action of the weakly acidic cation exchange resin 33. The second soft water tank 5 exchanges the hardness components that could not be removed in the first soft water tank 3 with the hydrogen ions possessed by the weakly acidic cation exchange resin 33. That is, the water flowing into the second soft water tank 5 is further softened and becomes soft water (second soft water).

[0121] The second soft water flows through the flow path 31 via the flow path switching valve 26 provided in the second soft water tank 5 and flows into the second neutralization tank 6. In the second neutralization tank 6, hydrogen ions contained in the flowing-in second soft water are adsorbed by the action of the weakly basic anion exchange resin 34. That is, since hydrogen ions are removed from the second soft water, the decreased pH rises and becomes neutral soft water (neutralized second soft water) that can be used as domestic water. The neutralized second soft water can be taken out from the water intake 7 by flowing through the flow path 32 via the flow path switching valve 27 provided in the second neutralization tank 6.

[0122] That is, in the softening treatment, the raw water flows through the first soft water tank 3, the first neutralization tank 4, the second soft water tank 5, and the second neutralization tank 6 in this order. Thereby, the raw water containing hardness components is softened in the first soft water tank 3 Before the pH of the raw water decreases due to the hydration treatment, it flows out of the first soft water tank 3, is neutralized in the first neutralization tank 4, softened in the second soft water tank 5, and then neutralized in the second neutralization tank 6. Therefore, compared with the case where the softening tank and the neutralization tank are each configured as a single unit, it is possible to suppress the decrease in pH, that is, the acidification of the water flowing through the soft water tank. As a result, the exchange between the hardness components and the hydrogen ions held by the weakly acidic cation exchange resin 33 in the softening tank (especially the second soft water tank 5) becomes easier. Therefore, it becomes possible to improve the softening performance.

[0123] Then, in the water softening apparatus 1, when the time zone specified by the control unit 15 is reached or when the water softening process exceeds a certain amount of water, the water softening process is terminated and the regeneration process is executed.

[0124] (Regeneration process) Next, the operation during the regeneration process by the regeneration device 8 of the water softening apparatus 1 will be described in order with reference to the "During regeneration" columns in FIGS. 3 and 7.

[0125] In the water softening apparatus 1, the first soft water tank 3 and the second soft water tank 5 filled with the weakly acidic cation exchange resin 33 will have a reduced or lost cation exchange capacity if use continues. That is, after all the hydrogen ions, which are the functional groups of the cation exchange resin, are exchanged with calcium ions or magnesium ions, which are hardness components, ion exchange can no longer occur. Even before all the hydrogen ions are exchanged with the hardness components, as the hydrogen ions decrease, the ion exchange reaction becomes less likely to occur, so the water softening performance decreases. When such a state occurs, hardness components will be contained in the treated water. For this reason, in the water softening apparatus 1, it becomes necessary to perform a regeneration process of the first soft water tank 3, the second soft water tank 5, the first neutralization tank 4, and the second neutralization tank 6 by the regeneration device 8.

[0126] During the regeneration process, the on-off valves 19, 20, and 22 are closed, the on-off valves 18, 21, and 23 are opened, the flow path switching valve 24 is in a connection state that allows water to be sent from the neutralization tank bypass flow path 42 to the first recovery flow path 37, the flow path switching valve 25 is in a connection state that allows water to be sent from the soft water tank bypass flow path 44 to the second recovery flow path 38, the flow path switching valve 26 is in a connection state that allows water to be sent from the first supply flow path 35 to the neutralization tank bypass flow path 42, and the flow path switching valve 27 is in a connection state that allows water to be sent from the second supply flow path 36 to the soft water tank bypass flow path 44. That is, the first soft water tank 3 and the second soft water tank 5 are in a communicating connection state, the first neutralization tank 4 and the second neutralization tank 6 are in a communicating connection state, and the drainage of the drain port 13 and the capture part drain port 14 is stopped. As a result, as shown in FIG. 3, a soft water tank regeneration circulation flow path 39 and a neutralization tank regeneration circulation flow path 40 are respectively formed.

[0127] Then, when the first water supply pump 11 and the second water supply pump 12 are operated, the acidic electrolyzed water and the alkaline electrolyzed water in the electrolytic cell 9 circulate through the soft water tank regeneration circulation flow path 39 and the neutralization tank regeneration circulation flow path 40 respectively.

[0128] Further, the electrolytic cell 9 is energized so that the anode has a higher potential than the cathode (positive electrolysis). As a result, during electrolysis, hydrogen ions are generated at the anode, and acidic electrolyzed water is generated near the anode. On the other hand, hydroxide ions are generated at the cathode, and alkaline electrolyzed water is generated near the cathode.

[0129] The acidic electrolyzed water generated in the electrolytic cell 9 flows through the first supply flow path 35 and is sent into the second soft water tank 5 through the flow path switching valve 26, and flows through the weakly acidic cation exchange resin 33 inside. Then, the acidic electrolyzed water that has flowed through the second soft water tank 5 flows through the neutralization tank bypass flow path 42 and is sent into the first soft water tank 3 through the flow path switching valve 24, and flows through the weakly acidic cation exchange resin 33 inside. That is, by passing the acidic electrolyzed water through the weakly acidic cation exchange resin 33, the cations (hardness components) adsorbed on the weakly acidic cation exchange resin 33 undergo an ion exchange reaction with the hydrogen ions contained in the acidic electrolyzed water. As a result, the weakly acidic cation exchange resin 33 is regenerated.

[0130] Subsequently, the acidic electrolyzed water that has flowed through the first soft water tank 3 contains cations and flows into the first recovery channel 37. That is, the acidic electrolyzed water containing cations that has flowed through the weakly acidic cation exchange resin 33 is recovered into the electrolytic cell 9 via the first recovery channel 37.

[0131] In this way, the soft water tank regeneration circulation channel 39 circulates the acidic electrolyzed water from the downstream side of the second soft water tank 5, which is the soft water tank located most downstream from the raw water inlet and has a weakly acidic cation exchange resin 33 with a smaller adsorption amount of hardness components than the upstream soft water tank, to the downstream side of the first soft water tank 3, which is located upstream and has a weakly acidic cation exchange resin 33 with a larger adsorption amount of hardness components than the second soft water tank 5. That is, the soft water tank regeneration circulation channel 39 is a channel that sends the acidic electrolyzed water sent out from the electrolytic cell 9 to the second soft water tank 5, then sends it to the first soft water tank 3 through the neutralization tank bypass channel 42, circulates it through the first soft water tank 3, and allows it to flow into the electrolytic cell 9 via the first recovery channel 37. Thereby, during the regeneration process, the acidic electrolyzed water discharged from the electrolytic cell 9 flows into the second soft water tank 5, which has a smaller adsorption amount of hardness components than the first soft water tank 3, and the acidic electrolyzed water containing hardness components is discharged from the second soft water tank 5 to the first soft water tank 3. In the regeneration of the weakly acidic cation exchange resin 33 in the second soft water tank 5, since less hydrogen ions in the acidic electrolyzed water are consumed compared to the first soft water tank 3, a reduction in the hydrogen ion concentration can be suppressed compared to the regeneration of the first soft water tank 3. Therefore, it is possible to suppress the inflow of acidic electrolyzed water containing a large amount of hydrogen ions into the first soft water tank 3 and suppress the re-adsorption of hardness components in the first soft water tank 3. Therefore, a decrease in the efficiency of the regeneration process can be suppressed and the regeneration time can be shortened.

[0132] On one hand, the alkaline electrolyzed water generated near the cathode of the electrolytic cell 9 flows through the second supply channel 36 and the capture unit 10, and is sent into the second neutralization tank 6 through the flow path switching valve 27, and flows through the weakly basic anion exchange resin 34 inside. Then, the alkaline electrolyzed water that has flowed through the second neutralization tank 6 flows through the soft water tank bypass channel 44, and is sent into the first neutralization tank 4 through the flow path switching valve 25, and flows through the weakly basic anion exchange resin 34 inside. That is, by passing the alkaline electrolyzed water through the weakly basic anion exchange resin 34, the anions adsorbed on the weakly basic anion exchange resin 34 undergo an ion exchange reaction with the hydroxide ions contained in the alkaline electrolyzed water. As a result, the weakly basic anion exchange resin 34 is regenerated.

[0133] After that, the alkaline electrolyzed water that has flowed through the first neutralization tank 4 contains anions and flows into the second recovery channel 38. That is, the alkaline electrolyzed water containing anions that has flowed through the weakly basic anion exchange resin 34 is recovered into the electrolytic cell 9 through the second recovery channel.

[0134] Thus, the neutralization tank regeneration circulation passage 40 circulates the alkaline electrolyzed water from the downstream side of the second neutralization tank 6 having the weakly basic anion exchange resin 34 with a smaller amount of adsorbed anions compared to the upstream neutralization tank to the downstream side of the first neutralization tank 4 having the weakly basic anion exchange resin 34 with more adsorbed anions than the second neutralization tank 6 located upstream. That is, the neutralization tank regeneration circulation passage 40 is a passage that circulates the alkaline electrolyzed water sent from the electrolysis tank 9 to the second neutralization tank 6, then sends it to the first neutralization tank 4 through the soft water tank bypass passage 44, circulates the first neutralization tank 4, and flows it into the electrolysis tank 9 through the second recovery passage 38. Thereby, during the regeneration process, the alkaline electrolyzed water flows into the second neutralization tank 6 with a smaller amount of adsorbed anions compared to the first neutralization tank 4, and the alkaline electrolyzed water containing anions is discharged from the second neutralization tank 6 to the first neutralization tank 4. In the regeneration of the weakly basic anion exchange resin 34 in the second neutralization tank 6, since the consumption of hydroxide ions in the alkaline electrolyzed water is smaller compared to the first neutralization tank 4, a reduction in the hydroxide ion concentration can be suppressed compared to the regeneration of the first neutralization tank 4. Therefore, it is possible to suppress the alkaline electrolyzed water containing a large amount of hydroxide ions from flowing into the first neutralization tank 4 and the re-adsorption of anions in the first neutralization tank 4. Therefore, a decrease in the regeneration process efficiency can be suppressed, and the regeneration time is shortened.

[0135] Further, the neutralization tank regeneration circulation passage 40 introduces the alkaline electrolyzed water sent from the electrolytic cell 9 into the first neutralization tank 4 and the second neutralization tank 6 from the downstream side of the first neutralization tank 4 and the second neutralization tank 6, and allows it to flow out from the upstream side where the adsorption amount of anions is larger than that on the downstream side of each neutralization tank. Thereby, the alkaline electrolyzed water flows in from the downstream side where the adsorption amount of the anion component is smaller, and the regeneration of the neutralization tank is performed. In the regeneration of the weakly basic anion exchange resin 34 on the downstream side, the consumption of hydroxide ions in the alkaline electrolyzed water is less compared to the upstream side, so that the reduction in the hydroxide ion concentration of the alkaline electrolyzed water can be suppressed. Therefore, the re-adsorption of anions contained in the alkaline electrolyzed water from the downstream side on the upstream side can be suppressed. Accordingly, a decrease in the efficiency of the regeneration process of the neutralization tank can be suppressed, and the regeneration time can be shortened. Note that the downstream side refers to the downstream side in the flow path during the water softening treatment.

[0136] Note that as the regeneration process progresses, in the water softening tank regeneration circulation passage 39, the concentrations of calcium ions and magnesium ions, which are hardness components released from the first water softening tank 3 and the second water softening tank 5, increase. Also, in the neutralization tank regeneration circulation passage 40, the concentration of carbonate ions released from the first neutralization tank 4 and the second neutralization tank 6 or the concentration of hydroxide ions generated on the cathode side of the electrolytic cell 9 increases. Therefore, in the electrolytic cell 9, the hardness components move to the cathode side during electrolysis and react with anions on the cathode side to form precipitates. For example, calcium ions react with carbonate ions to form calcium carbonate. Also, magnesium reacts with hydroxide ions to form magnesium hydroxide.

[0137] Part of the precipitate is contained in the alkaline electrolyzed water discharged from the electrolytic cell 9, flows through the second supply channel 36, and is captured by the capture unit 10. Therefore, during the regeneration process, the precipitate gradually accumulates in the capture unit 10, and the pressure loss caused by the capture unit 10 gradually increases. Along with this increase in pressure loss, the flow rate of the alkaline electrolyzed water flowing through the neutralization tank regeneration circulation channel 40 gradually decreases. Therefore, if the precipitate is left unattended, the time required for the regeneration of the weakly basic anion exchange resin 34 provided in the first neutralization tank 4 and the second neutralization tank 6 will be prolonged, and ultimately, the filling of hydroxide ions into the weakly basic anion exchange resin 34 may not be completed. Therefore, the water softening device 1 is provided with a capture unit cleaning step, which will be described later, and switches from the regeneration step to the capture unit cleaning step as necessary. In the capture unit cleaning step, the precipitate captured or deposited on the capture unit 10 is removed.

[0138] Depending on the amount of precipitate generated, it is necessary to frequently switch between the regeneration step and the capture unit cleaning step and clean the capture unit 10. During the regeneration process, due to the electrolysis performed in the electrolytic cell 9, the concentration of hydroxide ions gradually increases, and as the regeneration process progresses, the concentration of hydroxide ions in the alkaline electrolyzed water increases. Also, as the regeneration process progresses, the concentration of magnesium ions in the electrolytic cell 9 also increases, and when the solubility product of magnesium hydroxide is exceeded, a large amount of magnesium hydroxide precipitates instantaneously. The precipitated magnesium hydroxide exists in the alkaline electrolyzed water in a colloidal state and may not be completely captured by the capture unit 10. The magnesium hydroxide that could not be captured flows into the weakly basic anion exchange resin 34 in the second neutralization tank 6 and is included in the soft water as a hardness component during water softening, resulting in a decrease in water softening performance. Therefore, in order to suppress the decrease in regeneration efficiency, it is necessary to improve the capture performance of magnesium hydroxide in the capture unit 10.

[0139] In order to improve the capture rate in the capture unit 10, a large amount of magnesium hydroxide is generated and aggregated in the electrolytic cell 9 to increase the particle size of magnesium hydroxide. In the water softening device 1, during the period from when magnesium hydroxide starts to be generated in the electrolytic cell 9 until the capture unit pressure loss reaches the pressure set value, flow rate adjustment control is performed to reduce the flow rate of the alkaline electrolyzed water flowing through the neutralization tank regeneration circulation passage 40.

[0140] ((Flow rate adjustment control)) Next, the above-mentioned flow rate adjustment control will be described.

[0141] During the regeneration process, the water softening device 1 aggregates magnesium hydroxide by adjusting the flow rate of the second water supply pump 12, thereby improving the capture rate in the capture unit 10 of magnesium hydroxide.

[0142] First, the hydroxide ion concentration measurement unit 55 measures the hydroxide ion concentration of the alkaline electrolyzed water flowing through the second recovery passage 38, and transmits the measured hydroxide ion concentration measurement value to the hydroxide ion concentration comparison unit 60.

[0143] The hydroxide ion concentration comparison unit 60 receives the hydroxide ion concentration measurement value transmitted from the hydroxide ion concentration measurement unit 55 and the hydroxide ion concentration reference value transmitted from the hydroxide ion concentration storage unit 59. When the hydroxide ion concentration measurement value exceeds the hydroxide ion concentration reference value, magnesium hydroxide is generated and there is a possibility that it cannot be completely captured by the capture unit 10. Therefore, the hydroxide ion concentration comparison unit 60 determines whether the received hydroxide ion concentration measurement value reaches the hydroxide ion concentration reference value, and transmits the comparison result to the control unit 15.

[0144] The control unit 15 receives the comparison result from the hydroxide ion concentration comparison unit 60 and controls the flow rate adjustment unit 56 according to the comparison result. When the measured value of the hydroxide ion concentration is smaller than the reference value of the hydroxide ion concentration, the flow rate adjustment unit 56 maintains the current flow rate. Here, as the regeneration process progresses, the hydroxide ion concentration of the alkaline electrolyzed water gradually increases. When the hydroxide ion concentration gradually increases and the measured value of the hydroxide ion concentration measured by the hydroxide ion concentration measurement unit 55 exceeds the reference value of the hydroxide ion concentration, the control unit 15 controls the flow rate adjustment unit 56 to reduce the flow rate of the alkaline electrolyzed water to the reduced flow rate value. At this time, the control unit 15 receives the current value of the second water supply pump 12 from the pump current value detection unit 58, and the discharge pressure calculation unit 62 calculates the discharge pressure of the second water supply pump 12. Using the calculated value, the pressure comparison unit 63 compares the discharge pressure of the second water supply pump 12 with the sum of the alkaline flow path loss pressure stored in the loss pressure storage unit 61 and the capture unit loss pressure received from the pressure measurement unit 57. In response to the result, the control unit 15 calculates the reduced flow rate value as the flow rate corresponding to the discharge pressure of the second water supply pump 12 such that the discharge pressure of the second water supply pump 12 becomes a value larger than the sum of the alkaline flow path loss pressure and the capture unit loss pressure. Then, the flow rate adjustment unit 56 reduces the flow rate of the second water supply pump 12 to the calculated reduced flow rate value. As the regeneration process progresses at the reduced flow rate, the capture unit pressure loss measured by the pressure measurement unit 57 increases. Then, after a certain time has elapsed since the flow rate was reduced, the regeneration process is terminated and the capture unit cleaning process is executed. The certain time can be determined based on, for example, the capture unit pressure loss. After that, the flow rate of the second water supply pump 12 is returned to the flow rate before the reduction, and the regeneration process is restarted.

[0145] In addition, when the user wants to obtain soft water during the regeneration process, by opening a faucet or the like connected to the water softening device 1, the raw water flows from the inlet 2 through the flow path 53 and flows out from the water intake 7, so that the raw water can be used without waiting for the end of the regeneration process.

[0146] (Regeneration Flow Path Cleaning Process) Next, the operation of the water softening device 1 during the regeneration flow path cleaning process will be described in order with reference to the "During Regeneration Flow Path Cleaning" column in FIGS. 4 and 7.

[0147] In the water softening device 1, during the regeneration process, hardness components are released from the first soft water tank 3 and the second soft water tank 5 into the acidic electrolyzed water, and the acidic electrolyzed water circulates in the flow path without being discharged from the soft water tank regeneration circulation flow path 39 shown in FIG. 3. Therefore, after the completion of the regeneration process, the soft water tank regeneration circulation flow path 3 9 is filled with high-hardness water containing hardness components released from the first soft water tank 3 and the second soft water tank 5. The hardness of this high-hardness water is significantly higher than the hardness of the raw water (for example, 450 ppm), and may increase to about 2000 ppm, for example. When the water softening process is started in a state where this high-hardness water remains in the water softening device 1, high-hardness water or a mixed water of raw water and high-hardness water is discharged from the water intake 7. Therefore, when the user of the water softening device 1 executes the water softening process after the completion of the regeneration process, there is a problem that not only can soft water not be obtained immediately after the start of the water softening process, but water with a higher hardness than the raw water is obtained. In addition, the high-hardness water flows through the weakly acidic cation exchange resin 33 in the first soft water tank 3 and the second soft water tank 5. Although the hardness components adsorbed in the regeneration process are replaced with hydrogen ions for regeneration, water containing hardness components flows through again, so the hydrogen ions and hardness components filled by the regeneration process performed with great effort cause an exchange reaction, and the hardness components are adsorbed on the weakly acidic cation exchange resin 33 again. Therefore, the hydrogen ions available for softening the raw water decrease, and the water softening performance deteriorates. In order to solve these problems, a regeneration flow path cleaning process for draining the high-hardness water in the soft water tank regeneration circulation flow path 39 is performed.

[0148] During the regeneration flow path cleaning process, the on-off valves 21 to 23 are closed, the on-off valves 18 to 20 are opened, the flow path switching valve 24 is set to a connection state where water can be sent from the flow path 28 to the neutralization tank bypass flow path 42, the flow path switching valve 25 is set to a connection state where water can be sent to the soft water tank bypass flow path 44, the flow path switching valve 26 is set to a connection state where water can be sent from the neutralization tank bypass flow path 42 to the first supply flow path 35, and the flow path switching valve 27 is set to a connection state where water can be sent to the second supply flow path 36. That is, the first soft water tank 3 and the second soft water tank 5 are in a communicating connection state, the second soft water tank 5 and the drain port 13 are in a communicating connection state, the electrolytic cell 9 and the drain port 13 are in a communicating connection state, and the drainage from the capture part drain port 14 is stopped. As a result, as shown in FIG. 4, the first drainage flow path 46 and the second drainage flow path 47 are respectively formed. At this time, the operations of the electrode 41, the first water supply pump 11, and the second water supply pump 12 are stopped.

[0149] In the regeneration flow path cleaning process, specifically, by opening the on-off valve 19, raw water flows into the first drainage flow path 46 and the second drainage flow path 47 from the outside.

[0150] In the first drainage flow path 46, due to the pressure of the inflowing raw water, the high-hardness water in the flow path 28, the first recovery flow path 37, the first water supply pump 11, the electrolytic cell 9, and the first supply flow path 35 is flushed away and flows into the drainage flow path 54. The high-hardness water that has flowed into the drainage flow path 54 is discharged outside the apparatus from the drain port 13.

[0151] In the second drainage flow path 47, due to the pressure of the inflowing raw water, the high-hardness water in the flow path 28, the first soft water tank 3, the neutralization tank bypass flow path 42, the second soft water tank 5, and the first supply flow path 35 is flushed away and flows into the drainage flow path 54. The high-hardness water that has flowed into the drainage flow path 54 is discharged outside the apparatus from the drain port 13.

[0152] In this way, through the regeneration channel cleaning process, the high-hardness water in the first drainage channel 46 and the second drainage channel 47, which are the main residual locations of high-hardness water after the regeneration process, can be replaced with raw water while suppressing the flow to the neutralization tank. Therefore, in the regeneration channel cleaning process, since it is possible to suppress the adsorption of hydrogen ions to the weakly basic anion exchange resin 34 in the neutralization tank, the consumption of the filled hydroxide ions can be suppressed, and the neutralization performance can be maintained. Therefore, it is possible to suppress the deterioration of the water softening performance caused by high-hardness water.

[0153] Note that the control unit 15 supplies raw water to each channel such that the flow rate of the raw water flowing through the second drainage channel 47 is greater than the flow rate of the raw water flowing through the first drainage channel 46.

[0154] As a result, it is possible to preferentially replace the high-hardness water in the second drainage channel 47, which is a channel including the water softening tank used during the water softening process and is a channel where drainage of the high-hardness water in the channel is essential, with raw water. Therefore, it is possible to suppress the deterioration of the water softening performance caused by high-hardness water at the start of the water softening process. In addition, since it is a channel not used during the water softening process and the amount of drainage from the first drainage channel 46, where even if high-hardness water remains, the impact on the water softening process is small, can be reduced, unnecessary drainage can be prevented, and the amount of water required for the regeneration channel cleaning process can be suppressed. Moreover, as a result, the high-hardness water is drained outside the apparatus through a channel that does not include the neutralization tank. That is, since it is possible to suppress the adsorption of the hardness components in the high-hardness water stored in the water softening tank regeneration channel to the weakly basic anion exchange resin 34 in the neutralization tank and drain it, it is possible to prevent the deterioration of the water softening performance caused by the high-hardness water generated during the regeneration process and maintain the water softening performance.

[0155] And in the water softening apparatus 1, when the time zone specified by the control unit 15 arrives, or when the regeneration channel cleaning process exceeds a certain time (for example, 1 minute), or when the water flow rate in the regeneration channel cleaning process exceeds a certain value, the regeneration channel cleaning process is terminated and the electrolytic cell cleaning process is executed.

[0156]

[0157] ​In addition, when the user wants to obtain soft water during the regeneration flow path cleaning process, by opening a faucet (not shown) connected to the water softening device 1, raw water flows from the inlet 2 through the flow path 53 and out from the water intake 7. Therefore, the raw water can be used without waiting for the end of the regeneration flow path cleaning process.

[0158] (Electrolytic cell cleaning process) Next, the operation of the water softening device 1 during the electrolytic cell cleaning process will be described in order with reference to the "During electrolytic cell cleaning" columns in FIGS. 5 and 7.

[0159] In the regeneration process, when the electrolytic cell 9 is operating, hardness components (calcium ions or magnesium ions) in water are deposited as solids (scale) on the cathode. Since the deposit on the cathode is a non-conductor, it will increase the operating voltage of the electrolytic cell 9 and the power consumption during the regeneration process. Therefore, it is necessary to perform an electrolytic cell cleaning process to remove the deposit on the cathode.

[0160] In the electrolytic cell cleaning process, open the on-off valves 18 to 22 and close the on-off valve 23. Also, set the flow path switching valve 24 to a connection state where water can be supplied from the flow path 28 to the flow path 29, set the flow path switching valve 25 to a connection state where water can be supplied to the soft water tank bypass flow path 44, set the flow path switching valve 26 to a connection state where water can be supplied to the first supply flow path 35, and set the flow path switching valve 27 to a connection state where water can be supplied to the second supply flow path 36. That is, set the state where the first soft water tank 3 and the electrolytic cell 9 are in communication connection, the state where the electrolytic cell 9 and the drain port 13 are in communication connection, and the state where the electrolytic cell 9 and the capture unit drain port 14 are in communication connection. As a result, as shown in FIG. 5, the first drain flow path 46 and the third drain flow path 50 are respectively formed.

[0161] In the electrolytic cell cleaning process, specifically, by opening the on-off valve 19, raw water flows into the first drain flow path 46 and the third drain flow path 50 from the outside.

[0162] In the first drain flow path 46, the inflowing raw water flows through the flow path 28, the first recovery flow path 37, and the first water pump 11 and then flows into the electrolytic cell 9.

[0163] On the other hand, in the third drainage channel 50, the inflowing raw water flows through the channel 28, the first soft water tank 3, the second recovery channel 38, and the second water supply pump 12, and flows into the electrolytic cell 9.

[0164] In the electrolytic cell cleaning process, the control unit 15 energizes the cathode to be at a high potential with respect to the anode (reverse electrolysis). Therefore, the electrolytic cell 9 electrolyzes the raw water flowing into the electrolytic cell, and alkaline electrolyzed water is generated near the anode, and acidic electrolyzed water is generated near the cathode.

[0165] At this time, the acidic electrolyzed water generated at the cathode can dissolve the deposits deposited on the cathode. Therefore, it is possible to suppress the deterioration of the electrolysis performance caused by the adhesion of deposits on the surface of the electrode 41.

[0166] The alkaline electrolyzed water generated at the anode flows through the first supply channel 35, flows into the drainage channel 54, and is discharged outside the apparatus from the drainage port 13.

[0167] On the other hand, the acidic electrolyzed water generated at the cathode dissolves the deposits deposited on the cathode, flows through the second supply channel 36, and flows into the trapping unit 10. The acidic electrolyzed water flowing into the trapping unit 10 can dissolve the deposits trapped in the trapping unit 10 and can preliminarily clean the trapping unit 10. Therefore, the time required for the next trapping unit cleaning process can be shortened. Then, the acidic electrolyzed water is discharged outside the apparatus from the trapping unit drainage port 14 provided at the lower part of the trapping unit 10.

[0168] That is, in the electrolytic cell cleaning process, it is possible to simultaneously remove the deposits in the electrolytic cell 9 and the deposits in the trapping unit 10, and the time required from the end of the regeneration process to the start of the softening process can be shortened.

[0169] Then, in the softening apparatus 1, when the time zone specified by the control unit 15 is reached or when the electrolytic cell cleaning process exceeds a certain time (for example, 5 minutes), the electrolytic cell cleaning process is terminated and the trapping unit cleaning process is executed.

[0170] In the third drainage channel 50, since the raw water passes through the first soft water tank 3, the acidic water passes through the capture section 10. Therefore, the capture section 10 becomes acidic, and the precipitate captured by the capture section 10 is dissolved by the acidic water. Accordingly, since the capture section 10 can be preliminarily cleaned, the time required for the capture section cleaning step, which is the next step, can be shortened. That is, the removal of the precipitate in the electrolytic cell 9 and the removal of the precipitate in the capture section 10 can be performed simultaneously, and the time required from the end of the regeneration step to the start of the softening step can be shortened.

[0171] In addition, when the user wants to obtain soft water during the electrolytic cell cleaning step, by opening a faucet (not shown) or the like connected to the softening device 1, the raw water flows from the inlet 2 through the flow path 53 and flows out from the water intake 7, so that the raw water can be used without waiting for the end of the electrolytic cell cleaning step.

[0172] (Capture section cleaning step) Next, the operation of the softening device 1 during the capture section cleaning step will be described in order with reference to the "During capture section cleaning" columns in FIGS. 6 and 7.

[0173] The capture section cleaning step is a step of removing the precipitate captured by the capture section 10 after the electrolytic cell cleaning step. In the capture section cleaning step, the on-off valves 18, 19, 22, and 23 are opened, and the on-off valves 20 and 21 are closed. Also, the flow path switching valve 24 is set to a connection state capable of sending water from the flow path 28 to the flow path 29, the flow path switching valve 25 is set to a connection state capable of sending water from the flow path 29 to the flow path 30, the flow path switching valve 26 is set to a connection state capable of sending water from the flow path 30 to the flow path 31, and the flow path switching valve 27 is set to a connection state capable of sending water from the flow path 31 to the second supply flow path 36. That is, the first soft water tank 3 and the first neutralization tank 4 are in a communicating connection state, the first neutralization tank 4 and the second soft water tank 5 are in a communicating connection state, the second soft water tank 5 and the second neutralization tank 6 are in a communicating connection state, and the second neutralization tank 6 and the capture section drain port 14 are in a communicating connection state. As a result, as shown in FIG. 6, the fourth drainage channel 52 is formed.

[0174] In the capture unit cleaning process, specifically, by opening the on-off valve 19, raw water flows into the flow path 28 from the outside. The inflowing raw water circulates through the flow path 28, the first soft water tank 3, the flow path 29, the first neutralization tank 4, the flow path 30, the second soft water tank 5, the flow path 31, the second neutralization tank 6, and the second supply flow path 36, and flows into the capture unit 10.

[0175] In the capture unit 10, neutral soft water flows in from the side opposite to the water flow direction in the regeneration process. That is, the capture unit 10 is backwashed by the inflowing neutral soft water. At this time, since a part of the precipitate captured or deposited in the capture unit 10 by the electrolytic cell cleaning process is pre-dissolved, the cleaning of the capture unit 10 with neutral soft water can be easily performed. The neutral soft water containing the precipitate is discharged outside the apparatus from the capture unit drain port 14 provided at the lower part of the capture unit 10.

[0176] In this way, since the capture unit 10 can be backwashed, the precipitate remaining in the capture unit 10 can be removed. Therefore, clogging of the capture unit 10 can be suppressed, and when the regeneration process is performed again, the pressure loss caused by the capture unit 10 can be reduced. As a result, a reduction in the flow rate of the neutralization tank regeneration circulation flow path 40, which is a regeneration flow path including the capture unit 10, can be suppressed, and the flow rate of the alkaline electrolyzed water can be ensured, so that the regeneration performance can be ensured.

[0177] Then, in the water softening apparatus 1, when the time zone specified by the control unit 15 is reached or when the capture unit cleaning process exceeds a certain time (for example, 5 minutes), the capture unit cleaning process is terminated and the water softening process is executed.

[0178] Note that the flow path from the inlet 2 to the second neutralization tank 6 is the same as the flow path during the water softening process. That is, by using the fourth drain flow path 52, the second neutralization tank 6, which is the last-stage neutralization tank in the water softening process, is filled with the softened water. Therefore, by performing the water softening process after performing the capture unit cleaning process using the fourth drain flow path 52, the user of the water softening apparatus 1 can obtain softened water with reduced hardness from the water intake 7 immediately after the start of the water softening process.

[0179] In addition, when the user wants to obtain soft water during the capture unit cleaning process, by opening a faucet (not shown) connected to the water softening device 1, raw water flows from the inlet 2 through the flow path 53 and out from the water intake 7. Therefore, the raw water can be used without waiting for the end of the capture unit cleaning process.

[0180] As described above, in the water softening device 1, the water softening process, the regeneration process, the regeneration flow path cleaning process, the electrolytic cell cleaning process, and the capture unit cleaning process are repeatedly executed in this order. By performing the capture unit cleaning process immediately before the water softening process, the final neutralization tank in the water softening process is filled with the softened water. Therefore, when the user of the water softening device 1 opens the faucet, the discharge of high-hardness water from the water intake 7 can be suppressed, and soft water with stable hardness can be provided immediately after the start of the water softening process.

[0181] Also, by performing the electrolytic cell cleaning process after the regeneration flow path cleaning process, at the time of electrode polarization in the electrolytic cell cleaning process, the high-hardness water has already been drained outside the device, and the possibility of electrolyzing the high-hardness water can be suppressed. Therefore, the electrolysis of water with high hardness can be suppressed, and the generation of a large amount of scale in the flow path where alkaline electrolyzed water is supplied at the time of electrode polarization can be suppressed.

[0182] As described above, according to the water softening device 1 according to the first embodiment, the following effects can be enjoyed.

[0183] (1) The water softening device 1 includes a water softening tank (the first water softening tank 3 and the second water softening tank 5), a neutralization tank (the first neutralization tank 4 and the second neutralization tank 5), an electrolytic cell 9, a hydroxide ion concentration measurement unit 55, and a flow rate adjustment unit 56. In the water softening process, the water softening tank softens the raw water containing hardness components with the weakly acidic cation exchange resin 33. Also, the neutralization tank adjusts the pH of the softened water that has passed through the water softening tank to a weak salt It is neutralized by the basic anion exchange resin 34. In the regeneration process, the electrolytic cell 9 generates acidic electrolyzed water used for regenerating the weakly acidic cation exchange resin 33 and alkaline electrolyzed water used for regenerating the weakly basic anion exchange resin 34. The hydroxide ion concentration measurement unit 55 measures the hydroxide ion concentration of the alkaline electrolyzed water. When the measured value of the hydroxide ion concentration exceeds the hydroxide ion concentration reference value, the flow rate adjustment unit 56 decreases the flow rate of the water flowing through the cathode side of the electrolytic cell 9. The hydroxide ion concentration reference value is the hydroxide ion concentration at which magnesium hydroxide begins to be generated by the reaction between the hardness components released during the regeneration of the weakly acidic cation exchange resin 33 and the ions in the alkaline electrolyzed water. According to such a configuration, magnesium hydroxide precipitated during the regeneration process can be aggregated, and the capture rate in the capture unit of magnesium hydroxide can be improved. Therefore, it is possible to suppress a decrease in the softening performance due to the inflow of precipitates that could not be completely captured by the capture unit 10 into the ion exchange resin. In addition, since the number of times of the capture unit cleaning process can be reduced, the required time other than the softening process can be reduced, and the executable time of the softening process can be increased.

[0184] In the water softening device 1 according to the first embodiment, after the regeneration process is completed, the regeneration flow path cleaning process, the electrolytic cell cleaning process, and the capture unit cleaning process are executed in this order, but it is not limited to this. For example, the electrolytic cell cleaning process may be performed first and then the regeneration flow path cleaning process, and the capture unit cleaning process may be executed in the process before the water softening process. Even if the device is cleaned in such an order, the precipitates in the electrolytic cell 9 and the capture unit can be removed, and the second neutralization tank 6 immediately before the water softening process can be filled with soft water.

[0185] (Embodiment 2) The softening device 1a according to this embodiment is different from the first embodiment in that it does not include a pump current value detection unit 58, includes a flow rate measurement unit 64 for measuring the flow rate of alkaline electrolyzed water, does not include a loss pressure storage unit 61, a discharge pressure calculation unit 62, and a pressure comparison unit 63 in the configuration of the control unit 15a, includes a flow rate value storage unit 65 for storing a decreased flow rate value, compares the hydroxide ion concentration measured by the hydroxide ion concentration measurement unit 55 with the hydroxide ion concentration reference value stored in the hydroxide ion concentration storage unit 59, and when the hydroxide ion concentration exceeds the hydroxide ion concentration reference value, decreases the flow rate of the alkaline electrolyzed water to the decreased flow rate value stored in the flow rate value storage unit 65. The configuration of the softening device 1a other than this is the same as that of the softening device 1 according to the first embodiment. Hereinafter, the content already described in the first embodiment will be appropriately omitted from repeated explanation, and the points different from the first embodiment will be mainly described.

[0186] The softening device 1a according to this embodiment will be described with reference to FIGS. 9 and 10. FIG. 9 is a configuration diagram showing a soft water tank regeneration circulation path and a neutralization tank regeneration circulation path of the softening device according to the second embodiment. FIG. 10 is a conceptual diagram showing the configuration of the control unit of the softening device according to the second embodiment.

[0187] (Overall configuration) As shown in FIG. 9, the softening device 1a includes a flow rate measurement unit 64 for measuring the flow rate of alkaline electrolyzed water.

[0188] (Flow rate measurement unit) The flow rate measurement unit 64 is a device for measuring the flow rate of alkaline electrolyzed water. There is no particular limitation on the flow rate measurement method. The flow rate measurement unit 64 is communicably connected to a control unit 15a, which will be described later, by wireless or wired means.

[0189] (Control unit) The control unit 15a is connected to a hydroxide ion concentration measurement unit 55, a pressure measurement unit 57, a flow rate measurement unit 64, and a flow rate adjustment unit 56. The control unit 15a is based on the hydroxide ion concentration of the alkaline electrolyzed water measured by the hydroxide ion concentration measurement unit 55 and the flow rate measured by the flow rate measurement unit 64 Then, the flow rate adjustment unit 56 is controlled to control the flow rate of the alkaline electrolyzed water passed through from the second water supply pump 12.

[0190] (Flow rate value storage unit) The flow rate value storage unit 65 stores a reduced flow rate value which is the flow rate value after the flow rate is reduced. The reduced flow rate value is a predetermined value set in advance, for example, the flow rate necessary to discharge the scale generated in the electrolytic cell outside the electrolytic cell 9. The flow rate value storage unit 65 may be provided inside the control unit 15a or may be provided outside.

[0191] (Regeneration process) ((Flow rate adjustment control)) During the regeneration process, the water softening device 1a adjusts the flow rate of the second water supply pump 12 to aggregate magnesium hydroxide and improve the capture rate at the capture unit 10 of magnesium hydroxide.

[0192] First, the hydroxide ion concentration measurement unit 55 measures the hydroxide ion concentration of the alkaline electrolyzed water flowing through the second recovery channel 38, and transmits the measured hydroxide ion concentration measurement value to the hydroxide ion concentration comparison unit 60.

[0193] The hydroxide ion concentration comparison unit 60 receives the hydroxide ion concentration measurement value transmitted from the hydroxide ion concentration measurement unit 55 and the hydroxide ion concentration reference value transmitted from the hydroxide ion concentration storage unit 59. When the hydroxide ion concentration measurement value exceeds the hydroxide ion concentration reference value, magnesium hydroxide is generated and there is a possibility that it cannot be completely captured by the capture unit 10. Therefore, the hydroxide ion concentration comparison unit 60 determines whether the received hydroxide ion concentration measurement value reaches the hydroxide ion concentration reference value, and transmits the comparison result to the control unit 15a.

[0194] The control unit 15a receives the comparison result from the hydroxide ion concentration comparison unit 60 and controls the flow rate adjustment unit 56 based on the comparison result. When the measured value of the hydroxide ion concentration is smaller than the reference value of the hydroxide ion concentration, the flow rate adjustment unit 56 maintains the current flow rate. Here, as the regeneration process progresses, the hydroxide ion concentration of the alkaline electrolyzed water gradually increases. When the hydroxide ion concentration gradually increases and the measured value of the hydroxide ion concentration measured by the hydroxide ion concentration measurement unit 55 exceeds the reference value of the hydroxide ion concentration, the control unit 15a controls the flow rate adjustment unit 56 to decrease the flow rate of the alkaline electrolyzed water to the decreased flow rate value stored in the flow rate value storage unit 65. At this time, the control unit 15a receives the flow rate of the alkaline electrolyzed water from the flow rate measurement unit 64 and controls the flow rate adjustment unit 56 so that the measured flow rate matches the decreased flow rate value stored in the flow rate value storage unit 65. As the regeneration process progresses at the decreased flow rate, the capture unit pressure loss measured by the pressure measurement unit 57 increases. Then, after a certain time has elapsed since the flow rate was decreased, the regeneration process is terminated and the capture unit cleaning process is executed. The certain time can be determined based on, for example, the capture unit pressure loss. Specifically, the certain time is set to the time until the capture unit pressure loss reaches the capture unit pressure loss when the second water supply pump 12 reaches its upper limit output. After that, the flow rate of the second water supply pump 12 is returned to the flow rate before the decrease, and the regeneration process is restarted.

[0195] In addition, when the user wants to obtain soft water during the regeneration process, by opening a faucet or the like connected to the water softening device 1, raw water flows from the inlet 2 through the flow path 53 and out from the water intake 7, so that the raw water can be used without waiting for the end of the regeneration process.

[0196] As described above, according to the water softening device 1a according to the present embodiment, the following effects can be achieved.

[0197] (2) The water softening device 1a includes a second water supply pump 12 that supplies alkaline electrolyzed water to the neutralization tank and , it includes a flow rate measurement unit 64 for measuring the flow rate of the alkaline electrolyzed water, a control unit 15a, a hydroxide ion concentration measurement unit 55, a pressure measurement unit 57, and a flow rate adjustment unit 56. The control unit 15a is connected to the hydroxide ion concentration measurement unit 55, the pressure measurement unit 57, the flow rate measurement unit 64, and the flow rate adjustment unit 56. Based on the hydroxide ion concentration of the alkaline electrolyzed water measured by the hydroxide ion concentration measurement unit 55 and the flow rate of the alkaline electrolyzed water measured by the flow rate measurement unit 64, it controls the flow rate adjustment unit 56 to control the flow rate of the alkaline electrolyzed water flowing through the second water supply pump 12. Also, the control unit 15a includes a hydroxide ion concentration storage unit 59, a hydroxide ion concentration comparison unit 60, and a flow rate value storage unit 65. When the hydroxide ion concentration measurement value measured by the hydroxide ion concentration measurement unit 55 exceeds the hydroxide ion concentration reference value, the control unit 15a controls the flow rate adjustment unit 56 to reduce the flow rate of the alkaline electrolyzed water to the reduced flow rate value stored in the flow rate value storage unit 65. After a certain time has elapsed since the flow rate was reduced, the regeneration process is terminated, and the capture unit cleaning process is executed. After that, the flow rate of the second water supply pump 12 is returned to the flow rate before the reduction, and the regeneration process is restarted. With such a configuration, similar to Embodiment 1, the capture rate of magnesium hydroxide by the capture unit 10 can be improved for the regeneration process.

[0198] (Embodiment 3) The softening water device 1b according to this embodiment does not include a pump current value detection unit 58, includes a flow rate measurement unit 64 for measuring the flow rate of alkaline electrolyzed water, and does not include a loss pressure storage unit 61, a discharge pressure calculation unit 62, and a pressure comparison unit 63 in the configuration of the control unit 15b. A hydroxide ion concentration calculation unit 66 that calculates the hydroxide ion concentration in the electrolytic cell from the hydroxide ion concentration measured by the hydroxide ion concentration measurement unit 55 and the flow rate of the alkaline electrolyzed water measured by the flow rate measurement unit 64, a hydroxide ion concentration target value storage unit 67 that stores a predetermined hydroxide ion concentration, the hydroxide ion concentration reference value stored in the hydroxide ion concentration storage unit 59, the pre-drop flow rate value measured by the flow rate measurement unit 64, the hydroxide ion concentration in the electrolytic cell calculated by the hydroxide ion concentration calculation unit 66, and a flow rate calculation unit 68 that calculates a decreased flow rate value from the hydroxide ion concentration target value stored in the hydroxide ion concentration target value storage unit 67. The hydroxide ion concentration measured by the hydroxide ion concentration measurement unit 55 is compared with the hydroxide ion concentration reference value stored in the hydroxide ion concentration storage unit 59. When the hydroxide ion concentration exceeds the hydroxide ion concentration reference value, the flow rate of the alkaline electrolyzed water is decreased to the decreased flow rate value calculated based on the hydroxide ion concentration in the electrolytic cell and a preset hydroxide ion concentration target value. After a certain period of time has elapsed since the flow rate was decreased, the regeneration process is terminated, the capture unit cleaning process is executed, and then the regeneration process is restarted without returning the flow rate of the second water supply pump 12 to the pre-drop flow rate, which is different from Embodiment 1. The configuration of the softening water device 1b other than this is the same as that of the softening water device 1 according to Embodiment 1. Hereinafter, the contents already described in Embodiment 1 will be appropriately omitted, and the points different from Embodiment 1 will be mainly described.

[0199] The softening water device 1b according to this embodiment will be described with reference to FIGS. 11 and 12. FIG. 11 is a configuration diagram showing a soft water tank regeneration circulation flow path and a neutralization tank regeneration circulation flow path of the softening water device according to Embodiment 3. FIG. 12 is a conceptual diagram showing the configuration of the control unit of the softening water device according to Embodiment 3.

[0200] (Overall Configuration) As shown in FIG. 11, the softening water device 1b includes a flow rate measurement unit 64 for measuring the flow rate of alkaline electrolyzed water.

[0201] (Flow rate measurement unit) The flow rate measurement unit 64 is a device for measuring the flow rate of alkaline electrolyzed water. There is no particular limitation on the flow rate measurement method. Further, the flow rate measurement unit 64 is communicably connected to a control unit 15b described later by wireless or wired means.

[0202] (Control unit) The control unit 15b is connected to the hydroxide ion concentration measurement unit 55, the pressure measurement unit 57, the flow rate measurement unit 64, and the flow rate adjustment unit 56. Based on the hydroxide ion concentration of the alkaline electrolyzed water measured by the hydroxide ion concentration measurement unit 55 and the flow rate measured by the flow rate measurement unit 64, the control unit 15b controls the flow rate adjustment unit 56 to control the flow rate of the alkaline electrolyzed water passed through from the second water supply pump 12.

[0203] (Hydroxide ion concentration calculation unit) The hydroxide ion concentration calculation unit 66 calculates the hydroxide ion concentration in the electrolytic cell 9 from the hydroxide ion concentration measured by the hydroxide ion concentration measurement unit 55 and the flow rate of the alkaline electrolyzed water measured by the flow rate measurement unit 64. The hydroxide ion concentration calculation unit 66 may be provided inside or outside the control unit 15b.

[0204] (Hydroxide ion concentration target value storage unit) The hydroxide ion concentration target value storage unit 67 stores a predetermined hydroxide ion concentration that is greater than the hydroxide ion concentration reference value. The predetermined hydroxide ion concentration is, for example, the hydroxide ion concentration at which magnesium hydroxide begins to frequently appear (for example, 3×10 -4 mol / L). The hydroxide ion concentration target value storage unit 67 may be provided inside or outside the control unit 15b.

[0205] (Flow rate calculation unit) The flow rate calculation unit 68 calculates a reduced flow rate value for making the hydroxide ion concentration in the electrolytic cell equal to the hydroxide ion concentration target value, from the hydroxide ion concentration reference value stored in the hydroxide ion concentration storage unit 59, the flow rate value before reduction measured by the flow rate measurement unit 64, the hydroxide ion concentration in the electrolytic cell calculated by the hydroxide ion concentration calculation unit 66, and the hydroxide ion concentration target value stored in the hydroxide ion concentration target value storage unit 67. There is no particular limitation on the calculation method, but as an example, (reduced flow rate value) = (flow rate before reduction) × (hydroxide ion concentration target value - hydroxide ion concentration reference value) / (hydroxide ion concentration in the electrolytic cell), etc. The flow rate calculation unit 68 may be provided inside the control unit 15b or outside it.

[0206] (Regeneration process) ((Flow rate adjustment control)) During the regeneration process, the softening device 1b adjusts the flow rate of the second water supply pump 12 to aggregate magnesium hydroxide and improve the capture rate at the magnesium hydroxide capture unit 10.

[0207] First, the hydroxide ion concentration measurement unit 55 measures the hydroxide ion concentration of the alkaline electrolyzed water flowing through the second recovery channel 38, and transmits the measured hydroxide ion concentration measurement value to the hydroxide ion concentration comparison unit 60.

[0208] The hydroxide ion concentration comparison unit 60 receives the hydroxide ion concentration measurement value transmitted from the hydroxide ion concentration measurement unit 55 and the hydroxide ion concentration reference value transmitted from the hydroxide ion concentration storage unit 59. When the hydroxide ion concentration measurement value exceeds the hydroxide ion concentration reference value, magnesium hydroxide is generated and there is a possibility that it cannot be completely captured by the capture unit 10. Therefore, the hydroxide ion concentration comparison unit 60 determines whether the received hydroxide ion concentration measurement value reaches the hydroxide ion concentration reference value, and transmits the comparison result to the control unit 15b.

[0209] The control unit 15b receives the comparison result from the hydroxide ion concentration comparison unit 60 and controls the flow rate adjustment unit 56 according to the comparison result. When the measured value of the hydroxide ion concentration is smaller than the hydroxide ion concentration reference value, the flow rate adjustment unit 56 maintains the current flow rate. As the regeneration process progresses the hydroxide ion concentration of the alkaline electrolyzed water gradually increases. When the hydroxide ion concentration gradually increases and the measured value of the hydroxide ion concentration measured by the hydroxide ion concentration measurement unit 55 exceeds the hydroxide ion concentration reference value, the control unit 15b controls the flow rate adjustment unit 56, and decreases the flow rate of the alkaline electrolyzed water to the decreased flow rate value calculated by the flow rate calculation unit 68, so as to rapidly increase the hydroxide ion concentration in the electrolytic cell to the hydroxide ion concentration target value, and magnesium hydroxide can frequently appear and aggregate. At this time, the control unit 15b receives the flow rate of the alkaline electrolyzed water from the flow rate measurement unit 64, and controls the flow rate adjustment unit 56 so that the measured flow rate matches the decreased flow rate value calculated by the flow rate calculation unit 68. The decreased flow rate value is calculated by the flow rate calculation unit 68 based on the hydroxide ion concentration reference value stored in the hydroxide ion concentration storage unit 59, the flow rate before decrease measured by the flow rate measurement unit 64, the hydroxide ion concentration in the electrolytic cell calculated by the hydroxide ion concentration calculation unit 66, and the hydroxide ion concentration target value stored in the hydroxide ion concentration target value storage unit 67. As the regeneration process progresses at the flow rate after decrease, the capture unit pressure loss measured by the pressure measurement unit 57 increases. Then, after a certain period of time has elapsed since the flow rate was decreased, the regeneration process is terminated, and the capture unit cleaning process is executed. The certain period of time can be determined based on, for example, the capture unit pressure loss. After that, the flow rate of the second water supply pump 12 remains at the decreased flow rate value, and the regeneration process is restarted.

[0210] In addition, when the user wants to obtain soft water during the regeneration process, by opening a faucet or the like connected to the water softening device 1, the raw water flows from the inlet 2 through the flow path 53 and flows out from the water intake 7, so that the raw water can be used without waiting for the end of the regeneration process.

[0211] As described above, according to the water softening device 1b according to the present embodiment, the following effects can be enjoyed.

[0212] (3) The softening device 1b includes a second water supply pump 12 that supplies alkaline electrolyzed water to the neutralization tank, a flow rate measurement unit 64 that measures the flow rate of the alkaline electrolyzed water, a control unit 15b, a hydroxide ion concentration measurement unit 55, a pressure measurement unit 57, and a flow rate adjustment unit 56. The control unit 15a is connected to the hydroxide ion concentration measurement unit 55, the pressure measurement unit 57, the flow rate measurement unit 64, and the flow rate adjustment unit 56, and based on the hydroxide ion concentration of the alkaline electrolyzed water measured by the hydroxide ion concentration measurement unit 55 and the flow rate of the alkaline electrolyzed water measured by the flow rate measurement unit 64, controls the flow rate adjustment unit 56 to control the flow rate of the alkaline electrolyzed water flowing through from the second water supply pump 12. Further, the control unit 15a includes a hydroxide ion concentration storage unit 59, a hydroxide ion concentration comparison unit 60, a hydroxide ion concentration calculation unit 66, a hydroxide ion concentration target value storage unit 67, and a flow rate calculation unit 68. When the measured value of the hydroxide ion concentration measured by the hydroxide ion concentration measurement unit 55 exceeds the hydroxide ion concentration reference value, the control unit 15b controls the flow rate adjustment unit 56, and based on the hydroxide ion concentration reference value stored in the hydroxide ion concentration storage unit 59, the pre-drop flow rate value measured by the flow rate measurement unit 64, the hydroxide ion concentration in the electrolytic cell calculated by the hydroxide ion concentration calculation unit 66, and the hydroxide ion concentration target value stored in the hydroxide ion concentration target value storage unit 67, reduces the flow rate of the alkaline electrolyzed water to the reduced flow rate value calculated by the flow rate calculation unit 68. And after a certain time has elapsed since the flow rate was reduced, the regeneration process is terminated and the capture unit cleaning process is executed. After that, the flow rate of the second water supply pump 12 remains at the reduced flow rate value and the regeneration process is restarted. According to such a configuration, similar to Embodiment 1, for the regeneration process, the capture rate of magnesium hydroxide by the capture unit can be improved.

[0213] As described above, the embodiments of the present invention have been described based on the embodiments. These embodiments are examples, and it is understood by those skilled in the art that various modifications are possible for each of these constituent elements or combinations of each processing process, and such modifications are also within the scope of the present invention.

Industrial Applicability

[0214] The water softening device according to the present invention can be applied to a point-of-use water purification device (POU) or a point-of-entry water purification device (POE) installed at the place of use.

Explanation of symbols

[0215] 1, 1a, 1b Water softening device 2 Inlet 3 First soft water tank 4 First neutralization tank 5 Second soft water tank 6 Second neutralization tank 7 Water intake 8 Regeneration device 9 Electrolytic cell 10 Capture part 11 First water pump 12 Second water pump 13 Drain outlet 14 Capture part drain outlet 15, 15a, 15b Control part 18, 19, 20, 21, 22, 23 On-off valve 24, 25, 26, 27 Flow path switching valve 28, 29, 30, 31, 32 Flow path 33 Weak acid cation exchange resin 34 Weak base anion exchange resin 35 First supply flow path 36 Second supply flow path 37 First recovery flow path 38 Second recovery flow path 39 Soft water tank regeneration circulation flow path 40 Neutralization tank regeneration circulation flow path 41 Electrode 41a Electrode 41b Electrode 42 Neutralization tank bypass flow path 43 Water softening flow path 44 Soft water tank bypass flow path 45 Regeneration flow path washing flow path 46 First drain flow path 47 Second drain flow path 49 Electrolytic cell washing flow path 50 Third drain flow path 51 Capture unit cleaning flow path 52 Fourth drainage flow path 53 Flow path 54 Drainage flow path 55 Hydroxide ion concentration measurement unit 56 Flow rate adjustment unit 57 Pressure measurement unit 58 Pump current value detection unit 59 Hydroxide ion concentration memory unit 60 Hydroxide ion concentration comparison unit 61 Loss pressure memory unit 62 Discharge pressure calculation unit 63 Pressure comparison unit 64 Flow rate measurement unit 65 Flow rate value memory unit 66 Hydroxide ion concentration calculation unit 67 Hydroxide ion concentration target value memory unit 68 Flow rate calculation unit

Claims

1. A soft water tank that softens raw water containing a hardness component with a weakly acidic cation exchange resin; A neutralization tank that neutralizes the soft water that has passed through the soft water tank with a weakly basic anion exchange resin; An electrolytic cell that generates alkaline electrolyzed water for regenerating the weakly basic anion exchange resin; A trapping unit that traps precipitates contained in the alkaline electrolyzed water; A hydroxide ion concentration measurement unit that acquires the hydroxide ion concentration of the alkaline electrolyzed water; A flow rate adjustment unit that adjusts the flow rate of the alkaline electrolyzed water; Comprising; The flow rate adjustment unit, A water softening device that reduces the flow rate of the alkaline electrolyzed water to a reduced flow rate value when the hydroxide ion concentration exceeds a hydroxide ion concentration reference value.

2. Equipped with a water supply pump that sends the alkaline electrolyzed water to the neutralization tank, The reduced flow rate value, The water softening device according to claim 1, wherein the value is determined such that the discharge pressure of the water supply pump is greater than the loss pressure of the flow path through which the alkaline electrolyzed water is supplied.

3. A pressure measurement unit that measures the inflow pressure, which is the pressure of the alkaline electrolyzed water flowing into the trapping unit, and the outflow pressure, which is the pressure of the alkaline electrolyzed water flowing out of the trapping unit; A loss pressure storage unit that stores the loss pressure caused by a specific path in the flow path through which the alkaline electrolyzed water is supplied, comprising; The flow rate adjustment unit, A current value detection unit that detects the current value of the water supply pump; A current value adjustment unit that adjusts the current value of the water supply pump; The water softening device according to claim 2, wherein the current value adjustment unit adjusts the current value of the water supply pump to a current value corresponding to the reduced flow rate value.

4. The water softening device according to claim 3, wherein the specific path is a path that does not include the trapping unit.

5. A water supply pump that sends the alkaline electrolyzed water to the neutralization tank; A flow rate measurement unit that measures the flow rate of the alkaline electrolyzed water; The flow rate adjustment unit, A current value detection unit that detects the current value of the water supply pump; A current value adjustment unit that adjusts the current value of the water supply pump; The reduced flow rate value is set to a predetermined value, The water softening device according to claim 1, wherein the current value adjustment unit adjusts the current value of the water supply pump to a current value based on the reduced flow rate value.

6. A water supply pump that sends the alkaline electrolyzed water to the neutralization tank; A flow rate measurement unit that measures the flow rate of the alkaline electrolyzed water; A control unit that controls the regeneration process of the weakly basic anion exchange resin. The control unit A hydroxide ion concentration calculation unit that calculates the hydroxide ion generation concentration of the alkaline electrolyzed water generated in the electrolytic cell based on the hydroxide ion concentration acquired by the hydroxide ion concentration measurement unit and the flow rate measured by the flow rate measurement unit. A hydroxide ion concentration storage unit that stores a predetermined hydroxide ion concentration target value. The flow rate adjustment unit Is provided with a current value detection unit that detects the current value of the water supply pump. The upper limit value of the reduced current value, which is the current value when the flow rate of the alkaline electrolyzed water is reduced to the reduced flow rate value is The water softening device according to claim 1, wherein the value is determined based on the hydroxide ion reference value, the hydroxide ion generation concentration, and the hydroxide ion concentration target value.

7. After reducing the flow rate of the alkaline electrolyzed water to the reduced flow rate value, The water softening device according to claim 1, which performs a capture unit cleaning step of removing the precipitate captured by the capture unit after a certain period of time has elapsed.

8. A pressure measurement unit that measures the upstream pressure of the alkaline electrolyzed water flowing into the capture unit and the downstream pressure of the alkaline electrolyzed water flowing out of the capture unit. The certain period of time Is the time until the capture unit pressure loss value, which is the difference between the upstream pressure measured by the pressure measurement unit and the downstream pressure measured by the pressure measurement unit, exceeds the set pressure value. The water softening device according to claim 6.

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