Water softening unit

Abstract

To provide a water softening device capable of removing precipitates on a cathode while suppressing electrode deterioration.SOLUTION: A water softening device 1 includes a water softening tank 3, a neutralization tank 4, an electrolytic tank 7, and a chemical input part. The water softening tank 3 softens raw water containing hardness components by means of a weakly acidic cation exchange resin in a water softening process. The neutralization tank 4 neutralizes the softened water that has passed through the water softening tank with a weakly basic anion exchange resin in a neutralization process. The electrolytic tank 7 generates alkaline electrolytic water for regeneration of the weakly basic anion exchange resin in the regeneration process. The chemical input part feeds chemicals used in the electrolytic tank cleaning process to dissolve precipitates that precipitate in the electrolytic tank into the electrolytic tank.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Conventionally, by utilizing the characteristics of a weakly acidic cation exchange resin having a hydrogen ion at the end of a functional group, hardness components (for example, calcium ions, magnesium ions) in raw water are adsorbed and hydrogen ions are desorbed, that is, a method of softening raw water by exchanging them is known. Since the adsorption amount of hardness components is not infinite, it is necessary to exchange and regenerate the cation exchange resin. As a method for regenerating a cation exchange resin without using salt, a method of regenerating a cation exchange resin with acidic electrolyzed water generated by electrolysis is known (for example, see Patent Document 1).

[0003] In addition, the water softened by the weakly acidic cation exchange resin becomes acidic because hydrogen ions are released instead of the hardness components by the above-described component exchange. In order to neutralize this, a weakly basic anion exchange resin may be combined with the weakly acidic cation exchange resin for use. As a method for regenerating a weakly basic anion exchange resin, a method using alkaline electrolyzed water generated by electrolysis is known (for example, see Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] When conventional ion exchange resin regeneration methods are applied to water softeners, the water softener generates acidic and alkaline electrolyzed water for use in the ion exchange resin regeneration process. During the generation of this acidic and alkaline electrolyzed water, some of the calcium carbonate or magnesium hydroxide deposited in the cathode chamber of the electrolytic cell where water is electrolyzed accumulates on the cathode. The accumulation of deposits on the cathode increases the power consumption of the electrolytic cell and causes electrode deterioration. Therefore, a polarity reversal operation was performed, in which the voltage applied to the electrodes of the electrolytic cell was reversed from the aforementioned operation state, to remove the deposits. However, polarity reversal operation itself has the problem of accelerating electrode deterioration.

[0006] The present invention aims to solve the above-mentioned conventional problems and to provide a water softening device that enables the removal of precipitates on the cathode while suppressing electrode deterioration. [Means for solving the problem]

[0007] To achieve this objective, the water softening apparatus according to the present invention comprises a water softening tank, a neutralization tank, an electrolytic cell, and a chemical input unit. The water softening tank softens raw water containing hardness components using a weakly acidic cation exchange resin in a water softening treatment. The neutralization tank neutralizes the softened water that has passed through the water softening tank using a weakly basic anion exchange resin in a neutralization treatment. The electrolytic cell generates alkaline electrolyzed water used for regenerating the weakly basic anion exchange resin in a regeneration treatment. The chemical input unit adds chemicals to the electrolytic cell to be used in an electrolytic cell cleaning treatment that dissolves precipitates that have accumulated in the electrolytic cell. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a water softening device that enables the removal of precipitates on the cathode while suppressing electrode deterioration. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a conceptual diagram showing the configuration of a water softening device according to Embodiment 1. [Figure 2]Figure 2 is a configuration diagram showing the water softening channel of the water softening apparatus according to Embodiment 1. [Figure 3] Figure 3 is a diagram showing the regeneration circulation channel for the water softening tank and the regeneration circulation channel for the neutralization tank of the water softening apparatus according to Embodiment 1. [Figure 4] Figure 4 is a configuration diagram showing the first and second washing channels of the water softening apparatus according to Embodiment 1. [Figure 5] Figure 5 is a configuration diagram showing the third washing channel of the water softening device according to Embodiment 1. [Figure 6] Figure 6 is a configuration diagram showing the fourth washing channel of the water softening device according to Embodiment 1. [Figure 7] Figure 7 is a functional block diagram of the water softening device according to Embodiment 1. [Figure 8] Figure 8 is a configuration diagram showing the control method of the water softening device according to Embodiment 1. [Figure 9] Figure 9 is a flowchart showing the control of the water softening device according to Embodiment 1. [Figure 10] Figure 10 is a flowchart showing the control of the water softening device according to Embodiment 1. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described below with reference to the drawings. Note that the following embodiments are merely examples of the present invention and do not limit the technical scope of the present invention. Furthermore, the figures described in the embodiments are schematic diagrams, and the ratios of the size and thickness of each component in each figure do not necessarily reflect the actual dimensional ratios.

[0011] (Embodiment 1) Referring to Figure 1, the water softening device 1 according to Embodiment 1 of the present invention will be described. Figure 1 is a conceptual diagram showing the configuration of the water softening device 1 according to Embodiment 1 of the present invention. Note that Figure 1 conceptually shows each element of the water softening device 1.

[0012] <Overall Structure> The water softening device 1 is a device that generates neutral softened water from raw water containing hardness components supplied from the outside. The raw water is the water (water to be treated) introduced into the device through the inlet 2, and is, for example, tap water or well water. The raw water contains hardness components (for example, calcium ions or magnesium ions). By performing a water softening process using the water softening device 1, neutral softened water with a reduced hardness compared to the raw water can be obtained, and softened water can be used even in areas where the hardness of the raw water is high. The water softening in the water softening device 1 refers to a state where the amount of hardness components in the water after water softening is less than the amount of hardness components in the raw water.

[0013] Specifically, as shown in FIG. 1, the water softening device 1 includes an inlet 2, a hardness measurement unit 51, a soft water tank 3, a neutralization tank 4, a water intake 5, a regeneration device 6, a flow rate measurement unit 52, and a control unit 13.

[0014] Further, the water softening device 1 includes a drain port 11, a plurality of on-off valves (on-off valve 14, on-off valve 15, on-off valve 16, on-off valve 17, on-off valve 18, and on-off valve 19), a three-way valve 20, and a plurality of flow path switching valves (flow path switching valves 21 to 24). Details thereof will be described later.

[0015] <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.

[0016] The water intake 5 is an opening for supplying the water that has flowed through the water softening device 1 and has been subjected to the water softening process to the outside of the device. The water softening device 1 can take out the water after the water softening process from the water intake 5 by the pressure of the raw water flowing in from the inlet 2.

[0017] In the water softening device 1, in the water softening process for performing the water softening process, the raw water supplied from the outside flows in the order of the inlet 2, the hardness measurement unit 51, the flow path 25, the first soft water tank 3a, the flow path 26, the first neutralization tank 4a, the flow path 27, the second soft water tank 3b, the flow path 28, the second neutralization tank 4b, the flow path 29, the flow path 30, the flow rate measurement unit 52, and the water intake 5, and is discharged as neutral softened water.

[0018] <Soft water tank> The water softening tanks 3 (first water softening tank 3a and second water softening tank 3b) soften raw water containing hardness components through the action of a weakly acidic cation exchange resin 31. Specifically, the water softening tanks 3 exchange cations (calcium ions and magnesium ions), which are hardness components contained in the circulating water (raw water), with hydrogen ions, thereby lowering the hardness of the raw water and softening it. In the water softening device 1 of this embodiment 1, the water softening tanks 3 are provided as the first water softening tank 3a and the second water softening tank 3b, and unless otherwise distinguished, both are referred to collectively as the water softening tank 3.

[0019] The first water softening tank 3a softens the raw water flowing in from the inlet 2. The first water softening tank 3a is equipped with a flow path switching valve 21. Details about the flow path switching valve will be described later.

[0020] The second water softening tank 3b softens the water that has passed through the first neutralization tank 4a, which will be described later. The second water softening tank 3b is equipped with a flow path switching valve 23.

[0021] The first water softening tank 3a and the second water softening tank 3b are filled with weakly acidic cation exchange resin 31 (first weakly acidic cation exchange resin 31a and second weakly acidic cation exchange resin 31b).

[0022] The weakly acidic cation exchange resin 31 is an ion exchange resin having hydrogen ions at the ends of its functional groups. The weakly acidic cation exchange resin 31 adsorbs cations (calcium ions, magnesium ions), which are hardness components contained in the raw water being passed through, and releases hydrogen ions. Softened water treated with the weakly acidic cation exchange resin 31 contains a large amount of hydrogen ions that have been released through the exchange with the hardness components. In other words, the softened water flowing out of the first softened water tank 3a and the second softened water tank 3b is acidic softened water (acidic softened water) that contains a large amount of hydrogen ions.

[0023] Since the terminal ends of the functional groups of the weakly acidic cation exchange resin 31 are hydrogen ions, the weakly acidic cation exchange resin 31 can be regenerated using acidic electrolyzed water in the regeneration process described later. At this time, the weakly acidic cation exchange resin 31 releases cations, which are hardness components that were taken in during the water softening process.

[0024] There are no particular restrictions on the weakly acidic cation exchange resin 31, and a general-purpose resin can be used. For example, one that uses a carboxyl group (-COOH) as the exchange group. Also, the hydrogen ion (H), which is the counterion of the carboxyl group, can be used. + ) are metal ions, ammonium ions (NH4 + It is also acceptable if it is a positive ion such as )

[0025] <Neutralization tank> The neutralization tanks 4 (first neutralization tank 4a and second neutralization tank 4b) neutralize the pH of the softened water containing hydrogen ions (acidified softened water) coming out of the softened water tank through the action of the weakly basic anion exchange resin 32, thereby producing neutral softened water. Specifically, the neutralization tanks 4 adsorb hydrogen ions contained in the softened water from the softened water tank 3 along with anions, thereby raising the pH of the softened water and producing neutral softened water. In the water softening device 1 of this embodiment 1, the neutralization tanks 4 are provided as the first neutralization tank 4a and the second neutralization tank 4b, and unless otherwise distinguished, both are referred to collectively as the neutralization tank 4.

[0026] The first neutralization tank 4a neutralizes the acidic softened water that has flowed through the first softening tank 3a. The first neutralization tank 4a is equipped with a flow path switching valve 22.

[0027] The second neutralization tank 4b neutralizes the acidic softened water that has flowed through the second softening tank 3b. The second neutralization tank 4b is equipped with a flow path switching valve 24.

[0028] The first neutralization tank 4a and the second neutralization tank 4b are filled with weakly basic anion exchange resins 32 (first weakly basic anion exchange resin 32a and second weakly basic anion exchange resin 32b).

[0029] The weakly basic anion exchange resin 32 adsorbs hydrogen ions contained in the water being passed through it, producing neutral water. The weakly basic anion exchange resin 32 is regenerated using alkaline electrolyzed water in the regeneration process described later.

[0030] There are no particular restrictions on the weakly basic anion exchange resin 32; a general-purpose resin can be used, for example, one that is a free basic form of a tertiary amine.

[0031] <Hardness measurement part> The hardness measuring unit 51 is located downstream of the inlet 2 and upstream of the first water softening tank 3a, and measures the concentration of hardness components in the raw water flowing into the water softening device 1. Methods for measuring the hardness component concentration of the raw water include, for example, measuring the TDS value using a Total Dissolved Solids (TDS) meter and multiplying the measured TDS value by a specific percentage to obtain the hardness component concentration. Here, the specific percentage can be the expected proportion of hardness components in the raw water. Alternatively, the hardness component concentration of the raw water, previously measured by chelation titration or ion analysis, may be input as the measured value. The hardness measuring unit 51 is wirelessly or wiredly connected to the adsorption hardness calculation unit 61 and the control unit 13, which will be described later.

[0032] <Flow rate measuring section> The flow rate measuring unit 52 measures the flow rate of neutral soft water that flows out of the second neutralization tank 4b.

[0033] The flow rate measuring unit 52 is located downstream of the neutralization tank 4, and in this embodiment 1, it is located in the flow path 30. When multiple neutralization tanks 4 are provided, it is preferable that the flow rate measuring unit 52 be located downstream of the last neutralization tank 4. Furthermore, "downstream" refers to the downstream side in the water softening process.

[0034] The flow rate measuring unit 52 is wirelessly or wiredly connected to the adsorption hardness calculation unit 61 and the control unit 13, which will be described later. Information regarding the measured flow rate of softened water is used as an input signal for the adsorption hardness calculation unit 61 and the control unit 13.

[0035] As the flow rate measuring unit 52, any detector that measures the flow rate of water can be used, such as a general-purpose impeller type or ultrasonic type.

[0036] <Playback device> The regeneration device 6 is a device that regenerates the weakly acidic cation exchange resin 31 filled in the first water softening tank 3a and the second water softening tank 3b, and also regenerates the weakly basic anion exchange resin 32 filled in the first neutralization tank 4a and the second neutralization tank 4b.

[0037] The regeneration device 6 comprises an electrolytic cell 7, a capture unit 8, a first water supply pump 9, and a second water supply pump 10. The regeneration device 6 is connected to the second water softening tank 3b, the second neutralization tank 4b, the flow path 25, and the flow path 26 by the first supply flow path 33, the second supply flow path 34, the first recovery flow path 35, and the second recovery flow path 36, respectively. Details of each flow path will be described later. The first supply flow path 33, the second supply flow path 34, the first recovery flow path 35, the second recovery flow path 36, the neutralization tank bypass flow path 41, and the water softening tank bypass flow path 42 form the water softening tank regeneration circulation flow path 37 and the neutralization tank regeneration circulation flow path 38, which will be described later.

[0038] <<Electrolytic cell>> The electrolytic cell 7 generates acidic electrolyzed water and alkaline electrolyzed water by electrolyzing the incoming water using a pair of electrodes 39 (electrodes 39a and 39b) installed inside. More specifically, at electrode 39a, which becomes the anode during electrolysis in the regeneration process, hydrogen ions are generated by electrolysis, producing acidic electrolyzed water. At electrode 39b, which becomes the cathode during electrolysis in the regeneration process, hydroxide ions are generated by electrolysis, producing alkaline electrolyzed water. The electrolytic cell 7 then supplies the generated acidic electrolyzed water to the first water softening tank 3a and the second water softening tank 3b via the first supply channel 33 and the neutralization tank bypass channel 41. The electrolytic cell 7 also supplies the generated alkaline electrolyzed water to the first neutralization tank 4a and the second neutralization tank 4b via the second supply channel 34 and the water softening tank bypass channel 42. As will be described in detail later, the acidic electrolyzed water produced by the electrolytic cell 7 is used to regenerate the weakly acidic cation exchange resin 31 in the first water softening tank 3a and the second water softening tank 3b, and the alkaline electrolyzed water produced by the electrolytic cell 7 is used to regenerate the weakly basic anion exchange resin 32 in the first neutralization tank 4a and the second neutralization tank 4b. The electrolytic cell 7 is configured so that the energization state to the pair of electrodes 39 can be controlled by the control unit 13, which will be described later.

[0039] The electrolytic cell 7 is equipped with a diaphragm, which is a porous membrane that separates the liquids inside the cell. The diaphragm suppresses the mixing of acidic electrolyzed water and alkaline electrolyzed water by convection while allowing ion movement by electrophoresis. As a result, the consumption of hydrogen ions in the acidic electrolyzed water and hydroxide ions in the alkaline electrolyzed water by neutralization reactions is suppressed, thereby suppressing a decrease in the regeneration efficiency of the weakly acidic cation exchange resin 31 and the weakly basic anion exchange resin 32.

[0040] <<Water pump>> The first water supply pump 9 is a device that circulates acidic electrolyzed water to the first water softening tank 3a and the second water softening tank 3b during the regeneration process by the regeneration device 6. The first water supply pump 9 is installed in the first recovery channel 35 that connects the first water softening tank 3a and the electrolytic cell 7. This arrangement makes it easier to circulate the acidic electrolyzed water using only the first water supply pump 9.

[0041] The second water supply pump 10 is a device that circulates alkaline electrolyzed water to the first neutralization tank 4a and the second neutralization tank 4b during the regeneration process by the regeneration device 6. The second water supply pump 10 is installed in the second recovery channel 36 that connects the first neutralization tank 4a and the electrolytic cell 7. This arrangement makes it easier to circulate the alkaline electrolyzed water using only the second water supply pump 10.

[0042] Furthermore, the first water supply pump 9 and the second water supply pump 10 are connected to the control unit 13, which will be described later, via wireless or wired communication.

[0043] <<Supplementary Information>> The capture unit 8 is located in the second supply channel 34, which connects the electrolytic cell 7 and the second neutralization tank 4b. In other words, the capture unit 8 is located downstream of the electrolytic cell 7 and upstream of the neutralization tank 4 during the regeneration process.

[0044] The capture unit 8 captures precipitates contained in the alkaline electrolyzed water discharged from the electrolytic cell 7. Precipitates are reaction products formed in the electrolytic cell 7 when hardness components, which are cations released from the first softening tank 3a and the second softening tank 3b during the regeneration process, react with alkaline electrolyzed water. More specifically, while the electrolysis of water is being performed in the electrolytic cell 7, hardness components (e.g., calcium ions, magnesium ions) released from the first softening tank 3a and the second softening tank 3b during the regeneration process move from the anode (electrode 39a) side to the cathode (electrode 39b) side via the diaphragm. Since alkaline electrolyzed water is generated on the cathode side, the hardness components react with the alkaline electrolyzed water to form precipitates. For example, if the hardness component is calcium ions, mixing with alkaline electrolyzed water can cause reactions that produce calcium carbonate or calcium hydroxide. The precipitates derived from the hardness components either accumulate on the cathode side of the electrolytic cell 7 or flow out from the cathode side of the electrolytic cell 7 into the second supply channel 34.

[0045] By providing a capture unit 8 on the second supply channel 34, which is the downstream channel of the electrolytic cell 7 and the upstream channel of the neutralization tank 4, precipitates derived from hardness components can be captured by the capture unit 8, preventing the precipitates from flowing into the neutralization tank 4 and accumulating within it. If a capture unit 8 is not provided on the downstream side of the electrolytic cell 7 and the upstream side of the neutralization tank 4, when the water softening process is restarted after the regeneration process is completed, the precipitates accumulated in the neutralization tank 4 will react with hydrogen ions in the acidic softened water released from the softened water tank 3 and become ionized. As a result, the softened water sent from the neutralization tank 4 will again contain hardness components, causing its hardness to increase compared to the hardness when it was released from the softened water tank 3 immediately before. In contrast, by providing a capture unit 8 on the second supply channel 34, the accumulation and dissolution of precipitates in the neutralization tank 4 and the resulting increase in hardness can be suppressed.

[0046] Furthermore, during the regeneration process, the alkaline electrolyzed water, from which precipitates derived from hardness components have been captured by the capture unit 8, flows through the second neutralization tank 4b and the first neutralization tank 4a, and is then electrolyzed again in the electrolytic cell 7 to be used again as alkaline electrolyzed water for the regeneration of the weakly basic anion exchange resin 32. At this time, the acidic electrolyzed water contains fewer hardness components compared to the case without the capture unit 8. In other words, by capturing precipitates in the capture unit 8, the hardness of the acidic electrolyzed water is reduced, which reduces the amount of hardness components flowing into the first softening tank 3a and the second softening tank 3b, thereby suppressing a decrease in the regeneration efficiency of the weakly acidic cation exchange resin 31.

[0047] Furthermore, "the hardness components react" means not only that all hardness components react, but also that some components do not react or do not exceed the solubility product of the hardness components.

[0048] The capture unit 8 can take any form as long as it is capable of separating precipitates produced by the reaction between hardness components and alkaline electrolyzed water. Examples include cartridge-type filters, filtration layers using granular filter media, cyclone-type solid-liquid separators, and hollow fiber membranes.

[0049] A commonly used method for the capture unit 8 is a cartridge-type filter. Cartridge-type filters can include deep filtration types such as wound filters, surface filtration types such as pleated filters and membrane filters, or a combination of these.

[0050] The capture unit 8 includes an on / off valve 18 and a capture unit drain port 12.

[0051] The on-off valve 18 is a valve located at the bottom of the capture unit 8 and controls the drainage of water from within the capture unit 8. By opening the on-off valve 18, water from within the capture unit 8 can be discharged outside the device through the capture unit drain port 12. Furthermore, water from the neutralization tank regeneration circulation channel 38 (shown in Figure 3) can be discharged outside the device during and after the electrolytic cell cleaning process, which will be described later.

[0052] The capture section drain port 12 is an opening for discharging water from the capture section 8 to the outside of the device. By opening the on / off valve 18 located upstream of the capture section drain port 12, water from the capture section can be discharged from the capture section drain port 12 to the outside of the device.

[0053] <Medication Dispensing Section> The chemical supply unit adds chemicals to the electrolytic cell to dissolve the precipitates that form in the electrolytic cell. In this embodiment, the chemical supply unit is provided as a chemical tank 53.

[0054] The chemical tank 53 is located upstream of the second water supply pump 10 and is connected to the second recovery channel 36 via a washing water channel 54. The chemical tank 53 stores chemicals for removing precipitates accumulated on the electrode 39b, which is the cathode side of the electrolytic cell 7. It dissolves the required amount of chemicals in water to produce electrode washing water, and in the electrolytic cell cleaning process, the electrode washing water is passed to the cathode side of the electrolytic cell 7 through the second recovery channel 36. The precipitates are reaction products that occur in the electrolytic cell 7 when hardness components, which are cations released from the first water softening tank 3a and the second water softening tank 3b during the regeneration process, react with alkaline electrolyzed water. The electrode washing water passed to the cathode side of the electrolytic cell 7 is drained through the second supply channel 34, the capture unit 8, and the capture unit drain port 12. The chemical tank 53 includes a chemical storage unit 53a, a chemical supply channel 53b, and a chemical dissolution unit 53c.

[0055] The chemical storage unit 53a stores chemicals supplied from outside the water softening device 1. The chemical storage unit 53a is connected to the chemical dissolving unit 53c by a chemical supply passage 53b. The chemicals stored in the chemical storage unit 53a are capable of removing precipitates accumulated on the electrode 39b, and examples include citric acid, which is an acidic substance. The state of the chemical, whether liquid or solid, is not a concern, but a solid is preferable considering the ease of supplying the chemical from an external source, the ease of producing high-concentration chemical-containing water, and the danger of leakage inside or outside the device. Furthermore, in order to suppress corrosion of the chemical storage unit 53a and the chemical dissolving unit 53c during storage, organic acids are preferable to inorganic acids, as they have a higher pH and lower corrosiveness even in high-concentration chemical-containing water.

[0056] The drug supply channel 53b is a channel that connects the drug storage unit 53a and the drug dissolving unit 53c, supplying the drug stored in the drug storage unit 53a to the drug dissolving unit 53c. The drug supply channel 53b is equipped with a drug input mechanism, which is a mechanism for introducing the drug into the drug dissolving unit 53c. As the drug input mechanism, for example, if the drug is liquid, a pump can be used, and if the drug is solid, an opening that allows the drug to be introduced one tablet at a time from the drug storage unit 53a can be used. The drug input mechanism is connected to the control unit 13, which will be described later, via wireless or wired communication, and the drug is supplied from the drug storage unit 53a to the drug dissolving unit 53c by a signal from the control unit 13.

[0057] The drug dissolving unit 53c dissolves the drug supplied from the drug supply passage 53b in water to produce drug-containing water.

[0058] The washing water channel 54 is a channel that connects the chemical tank 53 and the second recovery channel 36. It is a channel for introducing water for dissolving the chemical into the chemical dissolving section 53c and for releasing the chemical-containing water produced in the chemical dissolving section 53c into the second recovery channel 36. The water for dissolving the chemical flows in from the second recovery channel 36 through the washing water channel 54 during the electrolytic cell cleaning process. The produced chemical-containing water then flows out into the second recovery channel 36 through the washing water channel 54 and into the electrolytic cell 7 via the second water supply pump 10.

[0059] <On / off valves, three-way valves, and flow path switching valves> Multiple on-off valves (on-off valves 14 to 19) are provided in each flow path, and each flow path switches between an "open" state and a "closed" state.

[0060] Multiple on-off valves (on-off valves 14, 15, 17, and 19) start or stop the flow of water to each channel by opening and closing the valves.

[0061] The on-off valves 16 and 18 are opened when the regeneration process described later is completed, during the electrolytic cell cleaning process, or when switching to the water softening process after the electrolytic cell cleaning process is completed, and the regenerated circulating water is discharged outside the device.

[0062] The three-way valve 20 is installed in the second recovery channel 36 and is connected to the wash water channel 54. The direction of flow in each channel is switched by the rotation of the valve.

[0063] Multiple flow path switching valves (flow path switching valves 21 to 24) are provided in the first water softening tank 3a, the first neutralization tank 4a, the second water softening tank 3b, and the second neutralization tank 4b, respectively. Each of the multiple flow path switching valves has three openings. The first opening is an inlet / outlet that allows water to flow in and out, the second opening is an inlet that does not function as an outlet for water to flow out but functions as an inlet for water to flow in, and the third opening is an outlet that does not function as an inlet for water to flow in but functions as an outlet for water to flow out. In each of the multiple flow path switching valves, the inlet / outlet is always "open," and depending on the direction of water flow, when either the inlet or the outlet is "open," the other is "closed." By providing flow path switching valves 21 to 24, the number of on / off valves required for each flow path in the water softening device 1 can be reduced, thereby reducing the cost of the water softening device 1.

[0064] Furthermore, multiple on-off valves (on-off valves 14 to 19), a three-way valve 20, and multiple flow path switching valves (flow path switching valves 21 to 24) are each connected to the control unit 13, which will be described later, via wireless or wired communication.

[0065] <Drain port> The drain port 11 is an opening provided at the end of the drain channel 44, and is an opening for discharging water from the regeneration circulation channel to the outside of the device. An on-off valve 16 is provided upstream of the drain port 11, and by opening the on-off valve 16, drainage can be performed from the drain port 11. The drain port 11 discharges water from the water softening tank regeneration circulation channel 37 to the outside of the device, for example, during and after the electrolytic cell cleaning process described later. Drainage from the drain port 11 may also be performed when switching to the water softening process after the completion of the regeneration process.

[0066] <Flow path> The bypass channel 43 is a channel that connects the inlet 2 and the channel 30, and an on / off valve 14 is provided on the channel. The bypass channel 43 makes it possible to bypass the water softening tank 3 and the neutralization tank 4 and send untreated water to the downstream side of the neutralization tank 4 without passing raw water through the water softening tank 3 and the neutralization tank 4. Furthermore, even when the regeneration process is being carried out, the user of the water softening device 1 can obtain raw water from the intake 5 via the bypass channel 43.

[0067] <<Water softening channel>> Referring to Figure 2, the water softening channel 40 formed during the water softening process of the water softening device 1 will be described. Figure 2 is a configuration diagram showing the water softening channel 40 of the water softening device 1.

[0068] The water softening channel 40 (indicated by the diagonal arrow in Figure 2) is a channel that softens the raw water. The raw water that flows through the water softening channel 40 becomes neutral soft water and is discharged outside the device from the water intake 5.

[0069] The water softening channel 40 is a channel through which water flows from the water intake 5, passing through the inlet 2, hardness measuring unit 51, channel 25, first water softening tank 3a, channel 26, first neutralizing tank 4a, channel 27, second water softening tank 3b, channel 28, second neutralizing tank 4b, channel 29, flow rate measuring unit 52, and channel 30, respectively, which are the routes through which water flows to the water softening tank 3 and the neutralizing tank 4.

[0070] The channel 25 is a channel that connects the inlet 2 to the first water softening tank 3a. In other words, the channel 25 is a channel that guides raw water containing hardness components from the inlet 2 to the first water softening tank 3a.

[0071] Flow path 26 is a flow path connecting the first water softening tank 3a to the first neutralization tank 4a. In other words, flow path 26 is a flow path that guides the water softened in the first water softening tank 3a to the first neutralization tank 4a.

[0072] Flow path 27 is a flow path connecting the first neutralization tank 4a to the second water softening tank 3b. In other words, flow path 27 is a flow path that guides the water neutralized in the first neutralization tank 4a to the second water softening tank 3b.

[0073] Flow path 28 is a flow path connecting the second water softening tank 3b to the second neutralization tank 4b. In other words, flow path 28 is a flow path that guides the water softened in the second water softening tank 3b to the second neutralization tank 4b.

[0074] Flow channel 29 is a flow channel connecting the second neutralization tank 4b to flow channel 30. In other words, flow channel 29 is a flow channel that guides softened raw water from the second neutralization tank 4b to flow channel 30.

[0075] The flow path 30 is a flow path that connects the flow path 29 to the water intake 5, and the bypass flow path 43 to the water intake 5. In other words, the flow path 30 is a flow path that guides softened raw water from the flow path 29 to the water intake 5, and a flow path that guides raw water from the bypass flow path 43 to the water intake 5.

[0076] As shown in Figure 2, an on-off valve 15 is installed on the flow path 25 downstream of the inlet 2 and upstream of the first softened water tank 3a. By closing the on-off valve 14 and opening the on-off valve 15, the first softened water tank 3a and the inlet 2 are connected. Additionally, the flow path switching valve 21 is switched to connect the first softened water tank 3a and the first neutralization tank 4a, the flow path switching valve 22 is switched to connect the first neutralization tank 4a and the second softened water tank 3b, the flow path switching valve 23 is switched to connect the second softened water tank 3b and the second neutralization tank 4b, and the flow path switching valve 24 is switched to connect the second neutralization tank 4b and the intake port 5. This creates a water softening channel 40 that connects the inlet 2 to the channel 25, the first water softening tank 3a, the channel 26, the first neutralization tank 4a, the channel 27, the second water softening tank 3b, the channel 28, the second neutralization tank 4b, the channel 29, the channel 30, and the intake 5.

[0077] <<Recycling channel>> Next, with reference to Figure 3, the regeneration circulation channel 37 of the water softening tank and the regeneration circulation channel 38 of the neutralization tank, which are formed during the regeneration process of the water softening device 1, will be described. Figure 3 is a configuration diagram showing the regeneration circulation channel 37 of the water softening tank and the regeneration circulation channel 38 of the water softening device 1. In this embodiment, the regeneration circulation channel 37 of the water softening tank and the regeneration circulation channel 38 of the neutralization tank are collectively referred to as the regeneration channel.

[0078] First, let me explain the water softening tank regeneration circulation channel 37.

[0079] The water softening tank regeneration circulation channel 37 is a channel through which acidic electrolyzed water flows during the regeneration process to regenerate the first water softening tank 3a and the second water softening tank 3b. As shown in Figure 3 (white arrow), the water sent out by the first water supply pump 9 flows through the electrolytic cell 7, the second water softening tank 3b, and the first water softening tank 3a, and returns to the electrolytic cell 7 for circulation.

[0080] Specifically, the water softening tank regeneration circulation channel 37 is composed of the first supply channel 33, the neutralization tank bypass channel 41, and the first recovery channel 35. An electrolytic cell 7, a second water softening tank 3b, a first water softening tank 3a, and a first water supply pump 9 are installed on the water softening tank regeneration circulation channel 37.

[0081] The first supply channel 33 is a channel that connects the downstream side of the electrolytic cell 7 during the regeneration process to the downstream side of the second water softening tank 3b during the water softening process, and is a channel that supplies acidic electrolyzed water from the electrolytic cell 7 to the second water softening tank 3b.

[0082] The neutralization tank bypass channel 41 is a channel that bypasses the first neutralization tank 4a and connects the upstream side of the second water softening tank 3b to the downstream side of the first water softening tank 3a during the water softening process, and is a channel that supplies acidic electrolyzed water from the second water softening tank 3b to the first water softening tank 3a.

[0083] The first recovery channel 35 is a channel that connects the upstream side of the first water softening tank 3a to the electrolytic cell 7 during the water softening process, and is a channel that recovers acidic electrolyzed water containing hardness components that has passed through the first water softening tank 3a and the second water softening tank 3b to the electrolytic cell 7. The first water supply pump 9 is provided in the first recovery channel 35.

[0084] Furthermore, the water softening tank regeneration circulation channel 37 is a channel that introduces the acidic electrolyzed water sent from the electrolytic cell 7 into the first water softening tank 3a and the second water softening tank 3b from the downstream side of the first water softening tank 3a and the second water softening tank 3b during the water softening process, and discharges it from the upstream side, where the amount of hardness components adsorbed is greater than on the downstream side of the water softening tank 3.

[0085] Next, we will explain the neutralization tank regeneration circulation channel 38.

[0086] The neutralization tank regeneration circulation channel 38 is a channel through which alkaline electrolyzed water flows during the regeneration process to regenerate the first neutralization tank 4a and the second neutralization tank 4b. As shown in Figure 3 (black arrow), the water sent by the second water supply pump 10 flows through the electrolytic cell 7, the second neutralization tank 4b, and the first neutralization tank 4a, and then returns to the electrolytic cell 7 for circulation.

[0087] Specifically, the neutralization tank regeneration circulation channel 38 is composed of the second supply channel 34, the soft water tank bypass channel 42, and the second recovery channel 36. An electrolytic cell 7, a second neutralization tank 4b, a first neutralization tank 4a, and a second water supply pump 10 are provided on the neutralization tank regeneration circulation channel 38.

[0088] The second supply channel 34 is a channel that connects the downstream side of the electrolytic cell 7 during the regeneration process to the downstream side of the second neutralization tank 4b during the water softening process, and is a channel that supplies alkaline electrolyzed water from the electrolytic cell 7 to the second neutralization tank 4b. The second supply channel 34 is equipped with an on / off valve 17, a capture unit 8, and an on / off valve 19.

[0089] The water softening tank bypass channel 42 is a channel that bypasses the second water softening tank 3b and connects the upstream side of the second neutralization tank 4b to the downstream side of the first neutralization tank 4a during the water softening process, and is a channel that supplies alkaline electrolyzed water from the second neutralization tank 4b to the first neutralization tank 4a.

[0090] The second recovery channel 36 is a channel that connects the upstream side of the first neutralization tank 4a to the electrolytic cell 7 during the water softening process, and is a channel that recovers the alkaline electrolyzed water that has passed through the first neutralization tank 4a and the second neutralization tank 4b to the electrolytic cell 7. The second recovery channel 36 is equipped with a second water supply pump 10.

[0091] <<Electrolytic cell cleaning channel>> Next, with reference to Figures 4 to 6, the electrolytic cell cleaning channels formed during the electrolytic cell cleaning process of the water softening apparatus 1 will be described. Figure 4 is a configuration diagram showing the first and second cleaning channels of the water softening apparatus according to Embodiment 1. Figure 5 is a configuration diagram showing the third cleaning channel of the water softening apparatus according to Embodiment 1. Figure 6 is a configuration diagram showing the fourth cleaning channel of the water softening apparatus according to Embodiment 1.

[0092] During the electrolytic cell cleaning process, valves 14-18 are opened and valve 19 is closed. In addition, flow path switching valve 21 is connected to allow water to be supplied from flow path 25 to flow path 26, and flow path switching valve 22 is connected to allow water to be supplied from flow path 26 to flow path 27. In addition, flow path switching valve 23 is connected to allow water to be supplied from flow path 27 to flow path 28, and flow path switching valve 24 is connected to allow water to be supplied from flow path 28 to the second supply flow path 34.

[0093] At this time, the first neutralization tank 4a and the second softening tank 3b are connected in communication. However, because the on-off valve 19 is closed, even if water flows out of the first softening tank 3a into the flow path 26, it does not flow into the first neutralization tank 4a but flows into the second recovery flow path 36. As a result, the first washing flow path 55 is formed, as shown in Figure 4. Furthermore, by setting the three-way valve 20 to a state in which water can be sent from the second recovery flow path 36 to the washing water flow path 54, a state in which water can be sent from the washing water flow path 54 to the second recovery flow path 36, and a state in which water flows over the second recovery flow path 36 without flowing into the washing water flow path 54, the second washing flow path 56, the third washing flow path 57, and the fourth washing flow path 58 are formed, as shown in Figures 4, 5, and 6, respectively.

[0094] The first washing channel 55 is a channel through which raw water is introduced into the electrolytic cell 7 and the acidic electrolyzed water remaining in the channel is drained outside the water softening device 1. As shown in Figure 4 (white arrow), the first washing channel 55 is a channel through which raw water flowing in from the inlet 2 flows through the first recovery channel 35, the first water supply pump 9, the electrolytic cell 7, the first supply channel 33, and the drainage channel 44 before being discharged from the drain outlet 11.

[0095] The second washing channel 56 is a channel through which raw water flows into the softened water tank 3 and then into the chemical dissolution section 53c. As shown in Figure 4 (black arrow), the second washing channel 56 is a channel through which raw water flowing in from the inlet 2 flows through the first softened water tank 3a, the second recovery channel 36, and the washing water channel 54 before flowing into the chemical tank 53.

[0096] The third washing channel 57 is a channel that sends the chemical-containing water from the chemical tank 53 to the cathode chamber and capture unit 8 of the electrolytic cell 7, and drains it through the capture unit drain port 12. As shown in Figure 5 (black arrow), the third washing channel 57 is a channel through which the chemical-containing water from the chemical tank 53 flows through the washing water channel 54, the second recovery channel 36, the second water supply pump 10, the electrolytic cell 7, the second supply channel 34, and the capture unit 8, and is drained from the capture unit drain port 12.

[0097] The fourth washing channel 58 is a channel through which raw water is drained via the water softening tank 3, the electrolytic cell 7, the capture unit 8, and the capture unit drain port 12. In other words, the fourth washing channel 58 is a channel for replacing the chemical-containing water in the third washing channel 57 with raw water that has flowed through the water softening tank 3. As shown in Figure 6 (white arrow), the fourth washing channel 58 is a channel through which raw water flowing in from the inlet 2 flows through the first water softening tank 3a, the second recovery channel 36, the second water supply pump 10, the electrolytic cell 7, the second supply channel 34, and the capture unit 8, and is drained from the capture unit drain port 12.

[0098] <Department Head> Referring to Figure 7, the functions of the control unit 13 according to this embodiment will be described. Figure 7 is a functional block diagram of the water softening device according to Embodiment 1.

[0099] The control unit 13 controls the execution of the water softening process, the regeneration process, the electrolytic cell cleaning process, and the switching between processes. The timing of the switching may be, for example, set to switch when the time reaches a predetermined reference time. As a method for identifying the reference time, which is a predetermined time period, for example, a predetermined reference time may be set in advance, or the predetermined reference time may be determined by identifying time periods when the likelihood of performing the water softening process is low based on actual usage. The predetermined reference time is a continuous time period within the time when the water softening process is performed infrequently.

[0100] For example, a period of time during which the water softening process is not performed is predetermined and designated as a standard time for the regeneration process. Specifically, if the period during which the water softening process is not performed is set from 11 PM to 6 AM, it is decided to perform the regeneration process during this period (7 hours). Another method of determination is to monitor the usage status of the water softening device 1 and record the time periods during which the water softening process is performed. Based on this time period information, a period during which the water softening process is performed less frequently is identified, and it is decided to perform the regeneration process during this period. Specifically, the usage status over the past month is monitored, and the average time period during which the amount of softened water used is low is calculated compared to the time period during which the water softening process is performed, and this is designated as a standard time.

[0101] Furthermore, the control unit 13 controls the on-off valves 16 and 18, and controls the drainage during the electrolytic cell cleaning process and the drainage process.

[0102] Furthermore, the control unit 13 controls the flow path switching valves 21-24, on-off valves 14, 15, 17, and 19, and the three-way valve 20 to perform flow path switching.

[0103] The control unit 13 includes an adsorption hardness calculation unit 61, a flow path hardness calculation unit 62, an electrolytic cell deposition amount calculation unit 63, a drug amount calculation unit 64, an input amount control unit 65, a cumulative amount calculation unit 66, a storage unit 67, and a comparison unit 68.

[0104] <<Adsorption hardness calculation section>> The adsorbed hardness calculation unit 61 calculates the amount of cations adsorbed onto the weakly acidic cation exchange resin 31 by the water softening process as the adsorbed hardness. The adsorbed hardness is calculated by multiplying the amount of raw water by the concentration of hardness components in the raw water. Specifically, the adsorbed hardness is calculated by multiplying the amount of raw water that has undergone the water softening process (the amount of softened water taken out from the water intake 5), as measured by the flow rate measurement unit 52, by the concentration of hardness components in the raw water, as measured by the hardness measurement unit 51. More precisely, it is calculated by multiplying the amount of softened water taken out from the water intake 5 by the concentration of hardness components removed by the water softening process (the difference between the hardness component concentration of the raw water and the hardness component concentration of the softened water).

[0105] Furthermore, when raw water exhibiting a typical concentration of hardness components in domestic water (for example, a hardness component concentration of 250 mg / L or less) is softened, the hardness component concentration of the softened water taken out from the intake 5 will be approximately 1% or less compared to the hardness component concentration of the raw water, and can therefore be considered practically zero. Thus, the hardness component concentration of the raw water can be used directly to calculate the amount of adsorption. In cases where the raw water exhibits a high hardness component concentration (for example, 300 mg / L or more), even after water softening treatment, the hardness components of the raw water may not be completely removed, and hardness components may begin to remain in the softened water taken out from the intake 5. In such cases, by installing a component that can measure the hardness component concentration of the incoming raw water, such as the hardness measuring unit 51, near the intake 5, the hardness component concentration of the softened water can be measured, and the difference between this and the hardness component concentration of the raw water can be calculated to determine the concentration of hardness components removed by the water softening process.

[0106] <<In-flow channel hardness calculation unit>> The flow path hardness calculation unit 62 calculates the amount of hardness components in the acidic electrolyzed water and alkaline electrolyzed water present in the softened water tank regeneration circulation flow path 37 and the neutralization tank regeneration circulation flow path 38 at the end of the regeneration process. The amount of hardness components can be calculated by multiplying the concentration of hardness components in the regenerated water in the regeneration circulation flow path by the amount of water.

[0107] <<Electrolytic tank precipitation amount calculation section>> The electrolytic cell precipitate amount calculation unit 63 calculates the amount of precipitate deposited in the electrolytic cell 7, particularly on the electrode 39b, which is the cathode side. It is assumed that almost the entire amount of hardness components adsorbed on the weakly acidic cation exchange resin 31 in the water softening process is released by the regeneration process. In this case, the amount of precipitate is calculated by subtracting the amount of hardness components in the regeneration circulation channel calculated by the channel hardness amount calculation unit 62 from the adsorbed hardness amount calculated by the adsorbed hardness amount calculation unit 61. In reality, the value calculated by the above method is the hardness equivalent of the precipitate generated in the neutralization tank regeneration circulation channel 38, and corresponds to the sum of the amount of precipitate deposited on the electrode 39b and the amount of precipitate captured by the capture unit 8. Therefore, if the amount of chemical agent described later is calculated based on the precipitate amount calculated by this method, it is calculated that an excess amount of chemical agent is required compared to the amount of chemical agent required to remove the precipitate from the electrolytic cell 7. However, as will be described later, in order to remove almost the entire amount of precipitate deposited on electrode 39b, it is desirable to use an excess amount of chemical agent, so it is desirable to calculate a value that includes the amount of precipitate in the capture unit 8.

[0108] <<Drug Dosage Calculation Unit>> The drug quantity calculation unit 64 calculates the amount of drug to be used in the electrolytic cell cleaning process to remove the precipitates accumulated on the electrodes, based on the precipitate amount calculated by the electrolytic cell precipitate amount calculation unit 63.

[0109] Regarding the amount of drug to be used, the drug is an acid (H + Let's consider the case where a substance containing H(II, AAA, AAA) is used. In such a water softening device, the precipitates that are likely to form are calcium carbonate or magnesium hydroxide. Calcium carbonate and magnesium hydroxide each contain 2 moles of H(II, AAA, AAA) per mole. + The reaction (dissolution of precipitates) occurs through this process. Therefore, theoretically, the precipitates can be removed by using twice the amount of the agent as the precipitates. However, in practice, the reaction becomes less likely to proceed as the concentrations of the precipitates and the agent decrease in the later stages of the reaction. Therefore, to remove precipitates accumulated on the electrodes, it is desirable to use 3 to 4 times the amount of the agent as the precipitates.

[0110] <<Input Amount Control Unit>> The input amount control unit 65 controls the drug input mechanism of the drug supply passage 53b so that the amount of drug calculated by the drug amount calculation unit 64 is supplied to the drug dissolution unit 53c during the electrolytic cell cleaning process. The control method depends on the form of the drug, but for example, if it is a solid of a specific shape, the supply amount can be controlled by the number of drugs, and if it is a liquid, it can be controlled by the volume. It is desirable that the actual amount of drug added has an error of within 5% of the amount of drug calculated by the drug amount calculation unit 64. By reducing the error, it is possible to remove precipitates from the electrolytic cell 7 while suppressing the wasteful use of drug.

[0111] <<Cumulative amount calculation section>> The cumulative amount calculation unit 66 calculates the cumulative amount of adsorbed hardness since the end of the previous electrolytic cell cleaning process. In other words, it calculates the cumulative amount of cations adsorbed onto the weakly acidic cation exchange resin 31 by the water softening process since the end of the previous electrolytic cell cleaning process. For the calculation, the amount of adsorption calculated for the water softening process performed since the end of the previous electrolytic cell cleaning process may be used, or the amount of raw water that underwent the water softening process may be multiplied by the concentration of hardness components in the raw water.

[0112] <<Storage section>> The memory unit 67 stores a predetermined value as the cleaning reference value. This cleaning reference value is compared with the cumulative value calculated by the cumulative amount calculation unit 66 in the comparison unit 68, which will be described later. If the cumulative value is equal to or greater than the cleaning reference value, the electrolytic cell cleaning process is performed. In other words, the cleaning reference value is a reference value that determines what value the cumulative value should be to perform the electrolytic cell cleaning process.

[0113] Setting a low cleaning standard value allows for more frequent electrolytic cell cleaning, preventing electrode deterioration due to deposit buildup. However, this increases the amount of wastewater generated and the time during which water softening treatment cannot be performed. Conversely, setting a high value reduces the amount of wastewater generated and the time during which water softening treatment cannot be performed. However, it prolongs the period during which deposits accumulate on the electrodes, reducing the effectiveness of preventing electrode deterioration.

[0114] <<Comparison Section>> The comparison unit 68 compares the cumulative value calculated by the cumulative amount calculation unit 66 with the cleaning reference value stored in the storage unit 67, and determines whether the cumulative value is equal to or greater than the cleaning reference value. As will be described in detail later, if the cumulative value is equal to or greater than the cleaning reference value, the control unit 13 controls the system to perform an electrolytic cell cleaning process after the regeneration process is completed in order to prevent electrode deterioration due to the accumulation of precipitates on the electrodes.

[0115] Each component of the control unit 13 can be implemented as hardware, such as a computer's CPU (Central Processing Unit), or as mechanical devices, and as software, such as a computer program. However, in this case, it is implemented through the coordination of these components. Therefore, these functional blocks can be implemented in various ways through combinations of hardware and software.

[0116] The above describes the configuration of the water softening device 1.

[0117] Next, we will explain the operation of the water softening device 1.

[0118] <Water softening process, regeneration process, electrolytic cell cleaning process, and wastewater treatment process> Next, referring to Figure 8, the water softening process, regeneration process, electrolytic cell cleaning process, and wastewater discharge process of the water softening device 1 will be described. Figure 8 is a diagram showing the state of the water softening device 1 during operation.

[0119] In the water softening process, regeneration process, electrolytic cell cleaning process, and wastewater discharge process, the control unit 13 controls the on / off valves 14 to 19, the three-way valve 20, the flow path switching valves 21 to 24, the electrodes 39 of the electrolytic cell 7, the first water supply pump 9, and the second water supply pump 10 to switch between them, as shown in Figure 8, to achieve the respective flow states.

[0120] In Figure 8, "ON" indicates the state in which the on-off valve is "open," the electrode 39 is energized, the water supply pump is operating, and the hardness measuring unit 51 and flow rate measuring unit 52 are energized. A blank space indicates the state in which the on-off valve is "closed," the electrode 39 is not energized, the water supply pump is stopped, and the hardness measuring unit 51 and flow rate measuring unit 52 are not energized.

[0121] Furthermore, in Figure 8, "(component number) to (component number)" indicates that the three-way valve and flow path switching valve in question are connected to flow paths in the direction of water being supplied from one component to the other. For example, the flow path switching valve 21 in the water softening process connects each flow path so that water can be supplied from flow path 25 to flow path 26.

[0122] <Water softening process> First, the operation of the water softening device 1 during the water softening process will be explained by referring to the "Water Softening Process" section in Figures 2 and 8.

[0123] In the water softening device 1, as shown in Figure 8, during the water softening process, the on-off valve 15 installed in the flow path 25 is opened while the on-off valve 14 is closed. This allows raw water containing hardness components to flow in from the outside. The incoming raw water flows in the order of the first softening tank 3a, the first neutralization tank 4a, the second softening tank 3b, and the second neutralization tank 4b, so the water softening device 1 can take out softened water (neutral soft water) from the water intake 5. At this time, the flow path switching valve 21 is connected to allow water to be sent from flow path 25 to flow path 26, the flow path switching valve 22 is connected to allow water to be sent from flow path 26 to flow path 27, the flow path switching valve 23 is connected to allow water to be sent from flow path 27 to flow path 28, and the flow path switching valve 24 is connected to allow water to be sent from flow path 28 to flow path 29. On-off valves 16 to 19 are all in a closed state. Furthermore, the electrodes 39 of the electrolytic cell 7, the first water supply pump 9, and the second water supply pump 10 are also stopped.

[0124] Specifically, as shown in Figure 2, in the water softening process, the raw water flowing in from the outside is supplied to the first water softening tank 3a by the pressure of the raw water, passing through the inlet 2, the hardness measuring unit 51, and the flow path 25. The raw water supplied to the first water softening tank 3a then flows through the weakly acidic cation exchange resin 31 provided inside the first water softening tank 3a. 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 31, and hydrogen ions are released (ion exchange takes place). As a result, the raw water is softened by the removal of cations. The softened water contains a large amount of hydrogen ions that have been exchanged for hardness components and released, so it becomes acidic water (first soft water) with a low pH (hydrogen ion concentration index). Here, water containing a large amount of permanent hardness components (for example, sulfates such as calcium sulfate or chlorides such as magnesium chloride) tends to have its pH lowered more easily when softened than water containing a large amount of temporary hardness components (for example, carbonates such as calcium carbonate). Since water softening is less likely to proceed when the pH is low, the water that has flowed through the first water softening tank 3a is passed through the first neutralization tank 4a to be neutralized.

[0125] The first softened water flows through the flow path 26 via the flow path switching valve 21 installed in the first softened water tank 3a and flows into the first neutralization tank 4a. In the first neutralization tank 4a, hydrogen ions contained in the softened water are adsorbed by the action of the weakly basic anion exchange resin 32. In other words, hydrogen ions are removed from the water softened in the first softened water tank 3a, so the lowered pH rises and neutralization occurs. Therefore, compared to the case where the water softened in the first softened water tank 3a is softened directly in the second softened water tank 3b, the softening process in the second softened water tank 3b proceeds more easily.

[0126] The water neutralized in the first neutralization tank 4a (first-stage neutralized soft water) flows through the flow path 27 via the flow path switching valve 22 provided in the first neutralization tank 4a and flows into the second soft water tank 3b. In the second soft water tank 3b, the cations that are hardness components are adsorbed and hydrogen ions are released by the action of the weakly acidic cation exchange resin 31. The second soft water tank 3b exchanges the hydrogen ions contained in the weakly acidic cation exchange resin 31 for the hardness components that could not be removed in the first soft water tank 3a. In other words, the water that flows into the second soft water tank 3b is further softened and becomes soft water (second-stage soft water).

[0127] The second softened water flows through channel 28 via a flow path switching valve 23 located in the second softened water tank 3b and flows into the second neutralization tank 4b. In the second neutralization tank 4b, hydrogen ions contained in the incoming second softened water are adsorbed by the action of a weakly basic anion exchange resin 32. In other words, hydrogen ions are removed from the second softened water, causing the lowered pH to rise and resulting in neutral softened water (neutralized second softened water) that can be used as drinking water. The neutralized second softened water flows through channel 29, the flow rate measuring unit 52, and channel 30 via a flow path switching valve 24 located in the second neutralization tank 4b and can be taken out from the water intake 5.

[0128] In other words, in the water softening process, the raw water flows through the first softening tank 3a, the first neutralization tank 4a, the second softening tank 3b, and the second neutralization tank 4b in that order. As a result, the raw water containing hardness components flows out of the first softening tank 3a before the pH of the raw water decreases due to the softening process in the first softening tank 3a, is neutralized in the first neutralization tank 4a, softened in the second softening tank 3b, and neutralized again in the second neutralization tank 4b. Therefore, compared to when the softening tank and neutralization tank are configured individually, the decrease in pH, i.e., acidification, of the water flowing through the softening tank can be suppressed, making it easier for the exchange between hardness components and hydrogen ions held by the weakly acidic cation exchange resin 31 in the softening tank (especially the second softening tank 3b) to occur. Consequently, it is possible to improve the water softening performance.

[0129] In the water softening device 1, the water softening process is terminated and the regeneration process is executed when the time period specified by the control unit 13 is reached, or when the water softening treatment exceeds a certain period of time.

[0130] <Regeneration process> Next, the operation of the regeneration device 6 of the water softening device 1 during the regeneration process will be explained in order, referring to the "Regeneration" column in Figures 3 and 8.

[0131] In the water softening device 1, the first water softening tank 3a and the second water softening tank 3b, which are filled with weakly acidic cation exchange resin 31, will experience a decrease or complete loss of cation exchange capacity with continued use. That is, once all the hydrogen ions, which are functional groups of the cation exchange resin, have been exchanged for calcium ions or magnesium ions, which are hardness components, ion exchange will no longer be possible. When this happens, hardness components will be contained in the treated water. Similarly, the first neutralization tank 4a and the second neutralization tank 4b, which are filled with weakly basic anion exchange resin 32, will experience a decrease or complete loss of anion exchange capacity and neutralization performance with continued use. When this happens, the acidic softened water flowing in from the water softening tanks will no longer be able to be neutralized. Therefore, in the water softening device 1, it becomes necessary to perform a regeneration process of the first water softening tank 3a, the second water softening tank 3b, the first neutralization tank 4a, and the second neutralization tank 4b using the regeneration device 6. In this embodiment 1, the control unit 13 determines the timing for performing the regeneration process, and executes the regeneration process when the time period specified by the control unit 13 arrives, or when the water softening treatment exceeds a certain period of time.

[0132] During the regeneration process, valves 15, 16, and 18 are closed, valves 14, 17, and 19 are opened, the flow path switching valve 21 is connected to allow water to be supplied from the neutralization tank bypass flow path 41 to the first recovery flow path 35, the flow path switching valve 22 is connected to allow water to be supplied from the soft water tank bypass flow path 42 to the second recovery flow path 36, the flow path switching valve 23 is connected to allow water to be supplied from the first supply flow path 33 to the neutralization tank bypass flow path 41, and the flow path switching valve 24 is connected to allow water to be supplied from the second supply flow path 34 to the soft water tank bypass flow path 42. In other words, the first soft water tank 3a and the second soft water tank 3b are connected in communication, the first neutralization tank 4a and the second neutralization tank 4b are connected in communication, and drainage from the drain port 11 and the capture unit drain port 12 is stopped. As a result, the soft water tank regeneration circulation flow path 37 and the neutralization tank regeneration circulation flow path 38 are formed, as shown in Figure 3.

[0133] When the first water supply pump 9 and the second water supply pump 10 are operated, the acidic electrolyzed water and alkaline electrolyzed water in the electrolytic cell 7 circulate through the water softening tank regeneration circulation channel 37 and the neutralization tank regeneration circulation channel 38, respectively.

[0134] Furthermore, the electrolytic cell 7 is energized such that the anode is at 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 produced near the anode. On the other hand, hydroxide ions are generated at the cathode, and alkaline electrolyzed water is produced near the cathode.

[0135] The acidic electrolyzed water produced in the electrolytic cell 7 flows through the first supply channel 33 and is sent to the second water softening tank 3b via the channel switching valve 23, where it flows through the weakly acidic cation exchange resin 31 inside. The acidic electrolyzed water that has flowed through the second water softening tank 3b then flows through the neutralization tank bypass channel 41 and is sent to the first water softening tank 3a via the channel switching valve 21, where it flows through the weakly acidic cation exchange resin 31 inside. In other words, by passing the acidic electrolyzed water through the weakly acidic cation exchange resin 31, the cations (hardness components) adsorbed on the weakly acidic cation exchange resin 31 undergo an ion exchange reaction with the hydrogen ions contained in the acidic electrolyzed water. This regenerates the weakly acidic cation exchange resin 31.

[0136] Subsequently, the acidic electrolyzed water that has flowed through the first water softening tank 3a contains cations and flows into the first recovery channel 35. In other words, the acidic electrolyzed water containing cations that has flowed through the weakly acidic cation exchange resin 31 is recovered in the electrolytic cell 7 via the first recovery channel 35.

[0137] Thus, the water softening tank regeneration circulation channel 37 is configured to circulate acidic electrolyzed water from the downstream side of the second water softening tank 3b, which is the water softening tank located furthest downstream from the raw water inlet and has a weakly acidic cation exchange resin 31 that adsorbs less hardness components than the upstream water softening tank, to the downstream side of the first water softening tank 3a, which is located upstream and has a weakly acidic cation exchange resin 31 that adsorbs more hardness components than the second water softening tank 3b. In other words, the water softening tank regeneration circulation channel 37 is a channel that circulates the acidic electrolyzed water sent from the electrolytic cell 7 to the second water softening tank 3b, then to the first water softening tank 3a via the neutralization tank bypass channel 41, circulates through the first water softening tank 3a, and flows back into the electrolytic cell 7 via the first recovery channel 35.

[0138] As a result, during the regeneration process, the acidic electrolyzed water discharged from the electrolytic cell 7 flows into the second softening tank 3b, which has less adsorption of hardness components compared to the first softening tank 3a, and the acidic electrolyzed water containing hardness components is discharged from the second softening tank 3b to the first softening tank 3a. In the regeneration of the weakly acidic cation exchange resin 31 in the second softening tank 3b, the consumption of hydrogen ions in the acidic electrolyzed water is less compared to the first softening tank 3a, so the reduction in hydrogen ion concentration can be suppressed compared to the regeneration of the first softening tank 3a. Therefore, acidic electrolyzed water containing a large amount of hydrogen ions flows into the first softening tank 3a, and the re-adsorption of hardness components in the first softening tank 3a can be suppressed. Consequently, the decrease in the efficiency of the regeneration process can be suppressed, and the regeneration time can be shortened. Note that the downstream side refers to the downstream side of the flow path during the water softening process.

[0139] Meanwhile, the alkaline electrolyzed water generated near the cathode of the electrolytic cell 7 flows through the second supply channel 34 and the capture unit 8, and is sent to the second neutralization tank 4b via the channel switching valve 24, where it flows through the internal weakly basic anion exchange resin 32. The alkaline electrolyzed water that has flowed through the second neutralization tank 4b then flows through the water softening tank bypass channel 42, and is sent to the first neutralization tank 4a via the channel switching valve 22, where it flows through the internal weakly basic anion exchange resin 32. In other words, by passing the alkaline electrolyzed water through the weakly basic anion exchange resin 32, the anions adsorbed on the weakly basic anion exchange resin 32 undergo an ion exchange reaction with hydroxide ions contained in the alkaline electrolyzed water. This regenerates the weakly basic anion exchange resin 32.

[0140] Subsequently, the alkaline electrolyzed water that has flowed through the first neutralization tank 4a contains anions and flows into the second recovery channel 36. In other words, the alkaline electrolyzed water containing anions that has flowed through the weakly basic anion exchange resin 32 is recovered in the electrolytic cell 7 via the second recovery channel 36.

[0141] Thus, the neutralization tank regeneration circulation channel 38 is configured to circulate alkaline electrolyzed water from the downstream side of the second neutralization tank 4b, which is the neutralization tank located furthest downstream from the raw water inlet and has a weakly basic anion exchange resin 32 that adsorbs fewer anions compared to the upstream neutralization tank, to the downstream side of the first neutralization tank 4a, which is located upstream and has a weakly basic anion exchange resin 32 that adsorbs more anions than the second neutralization tank 4b. In other words, the neutralization tank regeneration circulation channel 38 is a channel that circulates the alkaline electrolyzed water sent from the electrolytic cell 7 to the second neutralization tank 4b, then to the first neutralization tank 4a via the water softening tank bypass channel 42, circulates through the first neutralization tank 4a, and then flows back into the electrolytic cell 7 via the second recovery channel 36.

[0142] As a result, during the regeneration process, alkaline electrolyzed water flows into the second neutralization tank 4b, which has a lower anion adsorption capacity compared to the first neutralization tank 4a, and alkaline electrolyzed water containing anions is discharged from the second neutralization tank 4b to the first neutralization tank 4a. In the regeneration of the weakly basic anion exchange resin 32 in the second neutralization tank 4b, less hydroxide ions are consumed in the alkaline electrolyzed water compared to the first neutralization tank 4a, thus suppressing the reduction in hydroxide ion concentration compared to the regeneration of the first neutralization tank 4a. Therefore, alkaline electrolyzed water containing a large amount of hydroxide ions flows into the first neutralization tank 4a, and the re-adsorption of anions in the first neutralization tank 4a is suppressed. Consequently, a decrease in the efficiency of the regeneration process can be suppressed, and the regeneration time can be shortened.

[0143] Furthermore, within the electrolytic cell 7, precipitates are formed when hardness components, which are cations released from the first water softening tank 3a and the second water softening tank 3b during the regeneration process, react with the alkaline electrolyzed water. These precipitates contained in the alkaline electrolyzed water discharged from the electrolytic cell 7 are captured by the capture unit 8. This prevents the precipitates from flowing into and accumulating in the second neutralization tank 4b. By suppressing the accumulation of precipitates in this way, when the water softening process is restarted after the completion of the regeneration process, it is possible to suppress the increase in hardness of the softened water discharged from the second neutralization tank 4b, which is caused by the precipitates accumulated in the second neutralization tank 4b reacting with hydrogen ions contained in the water discharged from the second water softening tank 3b and becoming ionized.

[0144] The concentration of hardness components in the regenerated water in the regeneration circulation channel at the end of the regeneration process varies greatly depending on the pH of the regenerated water (more fundamentally, the current value flowing through the electrolytic cell) and the type of diaphragm separating the electrodes 39 in the electrolytic cell. This behavior changes significantly depending on the type of diaphragm separating the electrodes 39 in the electrolytic cell. For example, if an anion exchange membrane is used as the diaphragm of the electrolytic cell 7, hardness components cannot move from the anode side to the cathode side of the electrolytic cell 7. As a result, there is no inflow of hardness components into the cathode side, i.e., the neutralization tank regeneration circulation channel 38, and no precipitates are generated. However, in this case, the hardness components desorbed from the weakly acidic cation exchange resin 31 during the regeneration process do not flow into the neutralization tank regeneration circulation channel 38, but are all concentrated in the soft water tank regeneration circulation channel 37. As a result, the equilibrium of the ion exchange reaction between hydrogen ions in the weakly acidic cation exchange resin 31 and hardness components shifts toward the adsorption of hardness components onto the weakly acidic cation exchange resin 31. This makes it difficult to regenerate the weakly acidic cation exchange resin 31. Therefore, in the water softening device 1, a porous membrane is used as the diaphragm of the electrolytic cell 7.

[0145] In the water softening device 1, the regeneration process is terminated when a time period specified by the control unit 13 is reached, or when the regeneration process exceeds a certain time (for example, 4 hours) or a regeneration time based on instructions from the device user, and the electrolytic cell cleaning process or drainage process is executed.

[0146] Furthermore, if a user wishes to obtain water during the regeneration process, they can open a faucet (not shown) connected to the water softener 1, allowing raw water to flow from the inlet 2 through the bypass channel 43 and out of the intake 5. This enables the use of raw water without waiting for the regeneration process to complete.

[0147] <Electrolytic cell cleaning process> In the water softening device 1, once the regeneration process is complete, the process moves on to the electrolytic cell cleaning process. Here, the electrolytic cell cleaning process is a process of removing precipitates accumulated on the electrode 39b, which is the cathode side of the electrolytic cell 7.

[0148] Next, the operation of the water softening device 1 during the electrolytic cell cleaning process will be explained by referring to the "Electrolytic Cell Cleaning" section in Figure 8.

[0149] During the electrolytic cell cleaning process, valves 14-18 are opened and valve 19 is closed. In addition, flow path switching valve 21 is connected to allow water to be supplied from flow path 25 to flow path 26, and flow path switching valve 22 is connected to allow water to be supplied from flow path 26 to flow path 27. In addition, flow path switching valve 23 is connected to allow water to be supplied from flow path 27 to flow path 28, and flow path switching valve 24 is connected to allow water to be supplied from flow path 28 to the second supply flow path 34.

[0150] At this time, the first neutralization tank 4a and the second water softening tank 3b are connected in communication. However, because the on-off valve 19 is closed, even if water flows out of the first water softening tank 3a into the flow path 26, it does not flow into the first neutralization tank 4a but flows into the second recovery flow path 36. As a result, the first washing flow path 55 is formed, as shown in Figure 4. Furthermore, by setting the three-way valve 20 to a state in which water can be sent from the second recovery flow path 36 to the washing water flow path 54, a state in which water can be sent from the washing water flow path 54 to the second recovery flow path 36, and a state in which water flows over the second recovery flow path 36 without flowing into the washing water flow path 54, the second washing flow path 56, the third washing flow path 57, and the fourth washing flow path 58 are formed, as shown in Figures 4, 5, and 6, respectively. In addition, by opening the on-off valves 16 and 18, it is possible to drain raw water and chemical-containing water from the drain port 11 and the capture drain port 12.

[0151] Then, as shown in Figure 4, when the first water supply pump 9 is operated with the first washing channel 55 and the second washing channel 56 formed, the raw water flowing in from the inlet 2 flows through the anode chamber of the electrolytic cell 7 and is drained from the drain port 11. In addition, a portion of the raw water flowing in from the inlet 2 flows into the first water softening tank 3a, flows through the channel 26, the second recovery channel 36 and the washing water channel 54, and flows into the chemical dissolution section 53c.

[0152] Subsequently, when a certain amount of raw water that has passed through the first water softening tank 3a flows into the chemical dissolving section 53c, the three-way valve 20 is switched to prevent water from flowing into the washing water channel 54. Furthermore, the chemical for removing precipitates stored in the chemical storage section 53a is introduced into the chemical dissolving section 53c through the chemical supply channel 53b. This makes it possible to create chemical-containing water for removing precipitates within the chemical dissolving section 53c.

[0153] Next, the three-way valve 20 is switched to a state where water can be supplied from the washing water channel 54 to the second recovery channel 36, thereby forming the first washing channel 55 and the third washing channel 57 as shown in Figure 5. When the second water supply pump 10 is operated, the drug-containing water produced in the drug dissolution section 53c flows into the cathode chamber of the electrolytic cell 7 through the washing water channel 54 and the second recovery channel 36, and the precipitates accumulated on the electrode 39b can be removed by the drug-containing water. The drug-containing water from which the precipitates have been removed then flows out of the cathode chamber of the electrolytic cell 7 and is drained through the second supply channel 34, the capture section 8 and the capture section drain port 12. At this time, if the drug-containing water that has flowed into the capture section 8 has not been completely consumed, the incoming drug-containing water can also remove the precipitates captured in the capture section 8, thereby maintaining the performance of the capture section 8 or extending its lifespan.

[0154] Subsequently, the three-way valve 20 is switched to prevent water from flowing into the washing water channel 54, thereby forming the first washing channel 55 and the fourth washing channel 58 as shown in Figure 6. Then, by keeping the first water supply pump 9 and the second water supply pump 10 running, the raw water that has passed through the first water softening tank 3a is drained through the electrolytic cell 7, the capture unit 8, and the capture unit drain port 12. This cleans the channels through which the chemical-containing water has flowed, preventing the chemicals contained in the chemical-containing water from mixing with the alkaline regenerated water flowing through the neutralization tank regeneration circulation channel 38 in the next regeneration process. Depending on the type of chemical used, if an acidic chemical is used, a neutralization reaction will occur when it is mixed with alkaline regenerated water, reducing the regeneration efficiency of the weakly basic anion exchange resin 32 by the alkaline regenerated water.

[0155] In the water softening device 1, the electrolytic cell cleaning process is performed, and when a time specified by the control unit 13 has elapsed, the electrolytic cell cleaning process is terminated and the wastewater drainage process is performed.

[0156] <Drainage process> In the water softening device 1, once the regeneration process is complete, or if the electrolytic cell cleaning process is performed, the device proceeds to the wastewater discharge process. The wastewater discharge process involves discharging the acidic and alkaline electrolyzed water remaining in the water softening tank regeneration circulation channel 37 and the neutralization tank regeneration circulation channel 38.

[0157] Next, the operation of the water softening device 1 during the wastewater treatment process will be explained by referring to the "During Wastewater Treatment" column in Figure 8.

[0158] In the water softening device 1, as shown in Figure 8, during the drainage process (during drainage), the on-off valve 15 is closed, and on-off valves 14 and 16-19 are opened. The flow path switching valve 21 is connected to allow water to be sent from the neutralization tank bypass flow path 41 to the first recovery flow path 35, the flow path switching valve 22 is connected to allow water to be sent from the water softening tank bypass flow path 42 to the second recovery flow path 36, the flow path switching valve 23 is connected to allow water to be sent from the first supply flow path 33 to the neutralization tank bypass flow path 41, and the flow path switching valve 24 is connected to allow water to be sent from the second supply flow path 34 to the water softening tank bypass flow path 42. In other words, the water softening tank regeneration circulation flow path 37 and the neutralization tank regeneration circulation flow path 38 are formed, and by further opening the on-off valves 16 and 18, it is possible to drain acidic electrolyzed water and alkaline electrolyzed water from the drain port 11 and the capture unit drain port 12.

[0159] By performing a drainage process, when the water softening process is restarted, it is possible to prevent the acidic electrolyzed water and alkaline electrolyzed water remaining in the water softening tank regeneration circulation channel 37 and the neutralization tank regeneration circulation channel 38 from mixing with the raw water flowing in from the inlet 2 and being discharged from the intake port 5.

[0160] Then, in the water softening device 1, when the wastewater treatment process is completed, the on-off valves 14 and 16-19 are closed, on-off valve 15 is opened, the flow path switching valve 21 is connected to allow water to be supplied from flow path 25 to flow path 26, the flow path switching valve 22 is connected to allow water to be supplied from flow path 26 to flow path 27, the flow path switching valve 23 is connected to allow water to be supplied from flow path 27 to flow path 28, and the flow path switching valve 24 is connected to allow water to be supplied from flow path 28 to flow path 29, and the process proceeds to the water softening process. The wastewater treatment process can be considered complete when a certain amount of time has elapsed since the start of wastewater treatment.

[0161] As described above, the water softening device 1 repeatedly performs the water softening process, the regeneration process, the electrolytic cell cleaning process, and the wastewater discharge process.

[0162] Next, the control performed by the control unit 13 in the above configuration will be explained using Figures 9 and 10. Figures 9 and 10 are flowcharts showing the control of the water softening device according to Embodiment 1. Here, in the flowchart, numbers are assigned starting with the letter S. For example, S1 indicates a processing step. However, the magnitude of the numerical value indicating the processing step is not related to the processing order.

[0163] <Control details of the control unit 13> The following describes the control performed by the control unit 13 at the end of the regeneration process in the water softener 1. The water softener 1 can be configured to perform the electrolytic cell cleaning process every time the regeneration process is completed, or it can be configured to decide whether or not to perform the electrolytic cell cleaning process based on a cumulative value at the end of the regeneration process. The user of the water softener 1 can choose which method to use.

[0164] First, we will explain the case where the electrolytic cell cleaning process is performed each time the regeneration process is completed, using Figure 9.

[0165] At the end of the regeneration process, the hardness measuring unit 51 determines the hardness of the raw water flowing in from the inlet 2 (S001). One method for determining hardness is to measure the TDS value using a TDS meter and multiply the measured TDS value by a specific ratio to obtain the hardness component concentration. Here, the specific ratio can be the expected ratio of hardness components in the raw water. Furthermore, by adjusting the above specific ratio in consideration of the water quality of the area where the water softening device 1 is used, a more accurate measurement of the hardness component concentration can be obtained.

[0166] The flow rate measuring unit 52 determines the flow rate of softened water taken out from the water intake 5 (S002).

[0167] The adsorbed hardness calculation unit 61 calculates the adsorbed hardness amount based on the raw water hardness information identified by the hardness measurement unit 51 and the flow rate of softened water identified by the flow rate measurement unit 52 (S003).

[0168] The flow path hardness calculation unit 62 calculates the amount of hardness components in the acidic electrolyzed water and alkaline electrolyzed water present in the softened water tank regeneration circulation flow path 37 and the neutralization tank regeneration circulation flow path 38 at the end of the regeneration process, based on the concentration and volume of hardness components of the regenerated water in the regeneration circulation flow path (S004).

[0169] The concentration of hardness components in the regenerated water in the regeneration circulation channel at the end of the regeneration process varies greatly depending on the pH of the regenerated water (more fundamentally, the current value flowing through the electrolytic cell) and the type of membrane separating the electrodes 39 in the electrolytic cell. For example, consider the case where the pH of the acidic electrolyzed water is 2.5, the pH of the alkaline electrolyzed water is 11.5, and the membrane is a MicroFiltration (MF) membrane. In this case, the concentration of hardness components in the acidic electrolyzed water flowing through the softened water tank regeneration circulation channel 37 at the end of the regeneration process is approximately 10 mmol / L. Also, the concentration of hardness components in the alkaline regenerated water flowing through the neutralization tank regeneration circulation channel 38 is 0.5 mmol / L or less, and can be considered almost zero. The upper limit of the concentration of hardness components in the acidic electrolyzed water flowing through the softened water tank regeneration circulation channel 37 is largely determined by the equilibrium of the ion exchange reaction between hydrogen ions in the weakly acidic cation exchange resin 31 and the hardness components. Therefore, when the pH of the acidic electrolyzed water is lower, that is, when it is more acidic, the concentration of hardness components tends to be higher. Furthermore, since most of the hardness components in the alkaline regenerated water flowing through the neutralization tank regeneration circulation channel 38 precipitate as calcium carbonate and magnesium hydroxide, the concentration of hardness components becomes almost zero.

[0170] The electrolytic cell deposition amount calculation unit 63 calculates the amount of precipitate deposited in the electrolytic cell 7, particularly on the electrode 39b on the cathode side, based on the amount of adsorption hardness calculated by the adsorption hardness amount calculation unit 61 and the amount of hardness component in the regenerated circulation channel calculated by the channel hardness amount calculation unit 62 (S005).

[0171] The drug quantity calculation unit 64 calculates the amount of drug to be used in the electrolytic cell cleaning process to remove the precipitates accumulated on the electrodes, based on the precipitate amount calculated by the electrolytic cell precipitate amount calculation unit 63 (S006).

[0172] The input amount control unit 65 controls the drug input mechanism so that the amount of drug calculated by the drug amount calculation unit 64 is supplied to the drug dissolution unit 53c during the electrolytic cell cleaning process (S007).

[0173] After the drug-containing water is prepared by the input amount control unit 65, the control unit 13 performs the electrolytic cell cleaning process (S008).

[0174] Next, we will explain, using Figure 10, the case in which it is decided whether or not to perform the electrolytic cell cleaning process based on the cumulative value at the end of the regeneration process.

[0175] At the end of the regeneration process, the hardness measuring unit 51 determines the hardness of the raw water flowing in from the inlet 2 (S101). One method for determining hardness is to measure the TDS value using a TDS meter and multiply the measured TDS value by a specific ratio to obtain the hardness component concentration. Here, the specific ratio can be the expected ratio of hardness components in the raw water. Furthermore, by adjusting the above specific ratio in consideration of the water quality of the area where the water softening device 1 is used, a more accurate measurement of the hardness component concentration can be obtained. Alternatively, the hardness component concentration of the raw water measured in advance by chelation titration or ion analysis may be input as the measured value.

[0176] The flow rate measuring unit 52 determines the flow rate of softened water taken out from the water intake 5 (S102).

[0177] The adsorbed hardness calculation unit 61 calculates the adsorbed hardness amount based on the raw water hardness information identified by the hardness measurement unit 51 and the flow rate of softened water identified by the flow rate measurement unit 52 (S103).

[0178] The cumulative amount calculation unit 66 calculates the cumulative value of the adsorbed hardness since the end of the previous electrolytic cell cleaning process (S104).

[0179] The comparison unit 68 compares the cumulative value calculated by the cumulative amount calculation unit 66 with the cleaning reference value stored in the storage unit 67 (S105).

[0180] If the cumulative value is less than the cleaning standard value, the control unit 13 determines that the electrolytic cell cleaning process is unnecessary and proceeds to execute the drainage process.

[0181] If the cumulative value is equal to or greater than the cleaning standard value, the control unit 13 executes the electrolytic cell cleaning process (S105 → S201).

[0182] Next, we will explain the case where the electrolytic cell cleaning process is performed (S105→S201).

[0183] The drug quantity calculation unit 64 calculates the amount of drug to be used in the electrolytic cell cleaning process to remove precipitates accumulated on the electrodes, based on the cumulative amount calculated by the cumulative amount calculation unit 66 (S201).

[0184] The input amount control unit 65 controls the drug input mechanism so that the amount of drug calculated by the drug amount calculation unit 64 is supplied to the drug dissolution unit 53c during the electrolytic cell cleaning process (S202).

[0185] After the drug-containing water is prepared by the input amount control unit 65, the control unit 13 executes the electrolytic cell cleaning process (S203).

[0186] As described above, the amount of chemicals to be used in the electrolytic cell cleaning process, or whether or not to perform the electrolytic cell cleaning process at all, is determined based on the usage of softened water. By calculating the amount of adsorbed hardness, the amount of hardness in the flow path, and the amount of precipitate in the electrolytic cell, it is possible to appropriately adjust the amount of chemicals. Furthermore, if the electrolytic cell cleaning process is performed periodically, the decision to perform the electrolytic cell cleaning process is made by comparing the cumulative amount with the cleaning standard value. This makes it possible to perform an electrolytic cell cleaning process that can appropriately remove precipitates accumulated on the electrodes 39b in the electrolytic cell 7 while minimizing the number of times the electrolytic cell cleaning process is performed. Therefore, it is possible to suppress electrode deterioration due to precipitates. As described above, the water softening device 1 according to this embodiment 1 can be enjoyed with the following effects.

[0187] (1) The water softening device 1 comprises a water softening tank 3, a neutralization tank 4, an electrolytic cell 7, a control unit 13, a hardness measuring unit 51, a flow rate measuring unit 52, an adsorbed hardness amount calculation unit 61, a flow path hardness amount calculation unit 62, an electrolytic cell deposition amount calculation unit 63, a drug amount calculation unit 64, and an input amount control unit 65. The water softening tank 3 softens raw water containing hardness components using a weakly acidic cation exchange resin 31. The neutralization tank 4 neutralizes the pH of the softened water that has passed through the water softening tank 3 using a weakly basic anion exchange resin 32. The electrolytic cell 7 generates acidic electrolyzed water to regenerate the weakly acidic cation exchange resin 31 in the water softening tank 3 and alkaline electrolyzed water to regenerate the weakly basic anion exchange resin 32 in the neutralization tank 4. The hardness measuring unit 51 measures the concentration of hardness components in the raw water flowing into the water softening device 1. The flow rate measuring unit 52 measures the amount of softened water taken out from the water intake 5. The adsorption hardness amount calculation unit 61 calculates the amount of cations adsorbed on the weakly acidic cation exchange resin 31 by the water softening process as the adsorption hardness amount. The flow path hardness amount calculation unit 62 calculates the amount of hardness components in the acidic electrolyzed water and alkaline electrolyzed water present in the water softening tank regeneration circulation flow path 37 and the neutralization tank regeneration circulation flow path 38 at the end of the regeneration process. The electrolytic cell deposition amount calculation unit 63 calculates the amount of precipitate deposited in the electrolytic cell 7, especially on the electrode 39b on the cathode side. The drug amount calculation unit 64 calculates the amount of drug to be used to remove the precipitate deposited on the electrode 39b in the electrolytic cell cleaning process. The input amount control unit 65 controls the supply of the amount of drug calculated by the drug amount calculation unit 64 to the drug dissolution unit 53c in the electrolytic cell cleaning process.

[0188] With this configuration, the hardness component concentration of the raw water flowing from the hardness measurement unit 51 to the water softener 1 is measured, and the amount of softened water extracted is measured by the flow rate measurement unit 52. This allows the adsorption hardness amount calculation unit 61 to calculate the amount of cations adsorbed on the weakly acidic cation exchange resin 31 as the adsorption amount. Furthermore, the flow path hardness amount calculation unit 62 calculates the amount of hardness components in the acidic electrolyzed water and alkaline electrolyzed water present in the water softener tank regeneration circulation flow path 37 and the neutralization tank regeneration circulation flow path 38 at the end of the regeneration process, i.e., the amount of hardness components that have not precipitated. This allows the electrolytic cell precipitate amount calculation unit 63 to calculate the amount of precipitate deposited on the electrode 39b. In addition, the chemical amount calculation unit 64 can calculate the amount of chemical used to remove the precipitate deposited on the electrode during the electrolytic cell cleaning process. Therefore, by adjusting the amount of chemical used according to the amount of precipitate generated, it is possible to remove precipitates that precipitate on the cathode and cause increased power consumption and electrode deterioration during operation of the electrolytic cell 7 without excess or deficiency. Therefore, it becomes possible to remove deposits on the cathode while suppressing electrode degradation. In addition, since only the amount of chemical necessary for deposit removal is used, the wasteful use of chemicals can be suppressed.

[0189] (2) The water softening device 1 includes a cumulative amount calculation unit 66, a storage unit 67, and a comparison unit 68. The cumulative amount calculation unit 66 calculates the cumulative value of the adsorbed hardness since the end of the previous electrolytic cell cleaning process. The storage unit 67 stores a predetermined value as the cleaning standard value. The comparison unit 68 compares the cumulative value calculated by the cumulative amount calculation unit 66 with the cleaning standard value stored in the storage unit 67 and determines whether the cumulative value is equal to or greater than the cleaning standard value. If the cumulative value is equal to or greater than the cleaning standard value, the electrolytic cell cleaning process is executed.

[0190] With this configuration, when the total amount of hardness adsorbed by multiple water softening treatments reaches the cleaning standard value, an electrolytic cell cleaning process is performed after the regeneration process, and precipitates on the cathode can be removed with chemicals. When the amount of hardness components in the raw water or the amount of water softening treatment per treatment is small, the amount of precipitates that accumulate on the electrode 39b by one water softening and regeneration treatment is less than the amount that accelerates the deterioration of the electrode 39b. Therefore, by performing an electrolytic cell cleaning treatment after multiple water softening and regeneration treatments, it is possible to suppress electrode deterioration while further reducing the amount of chemicals used.

[0191] (3) The water softening device 1 is configured to allow the chemical-containing water that flows out of the electrolytic cell 7 during the electrolytic cell cleaning process to be drained through the capture unit 8 and the capture unit drain port 12.

[0192] With this configuration, the chemical-containing water used to remove precipitates accumulated on the electrodes 39b of the electrolytic cell 7 can be introduced into the capture unit 8, thereby removing the precipitates captured in the capture unit 8 by the incoming chemical-containing water. Therefore, it becomes possible to maintain the performance of the capture unit 8 or extend its lifespan.

[0193] The present invention has been described above based on embodiments. These embodiments are illustrative, and it will be understood by those skilled in the art that various modifications are possible for each component or combination of processing steps, and that such modifications also fall within the scope of the present invention.

[0194] In Embodiment 1, the chemical tank 53 is used to store the chemicals, produce chemical-containing water, and allow the chemical-containing water to flow into the electrolytic cell. However, instead of a chemical tank, the chemical input section may be provided with a chemical input port that allows the chemicals to be introduced into the device from outside, and piping connecting the chemical input port and the electrolytic cell. When performing the electrolytic cell cleaning process, the chemicals may be introduced directly from the outside through the chemical input port, allowing the chemicals to flow into the electrolytic cell. [Industrial applicability]

[0195] The water softening device according to the present invention can be applied to point-of-use (POU) water purification devices or point-of-entry (POE) water purification devices installed at building entrances, etc. [Explanation of symbols]

[0196] 1 Water softener 2 Inlet 3 Soft water tank 3a First soft water tank 3b Second soft water tank 4 Neutralization tank 4a First neutralization tank 4b Second neutralization tank 5. Water intake 6 Playback device 7 Electrolytic cell 8. Capture section 9. First water supply pump 10. Second water supply pump 11 Drain 12 Trap drainage port 13 Control Unit 14, 15, 16, 17, 18, 19 Shut-off valves 20 Three-way valve 21, 22, 23, 24 Flow path switching valve 25, 26, 27, 28, 29, 30 Channels 31 Weakly acidic cation exchange resin 31a First weakly acidic cation exchange resin 31b Second weakly acidic cation exchange resin 32 Weakly basic anion exchange resin 32a First weakly basic anion exchange resin 32b Second weakly basic anion exchange resin 33 First supply channel 34 Second supply channel 35 First recovery channel 36 Second recovery channel 37. Water softening tank regeneration circulation channel 38 Neutralization tank regeneration circulation channel 39 electrode 39a electrode 39b electrode 40 Water softening channel 41 Neutralization tank bypass channel 42. Softened water tank bypass channel 43 Bypass channel 44 Drainage channel 51 Hardness measurement section 52 Flow measurement section 53 Chemical tank 53a Drug Storage Department 53b Drug supply route 53c Drug dissolving section 54 Wash water channel 61 Adsorption hardness calculation section 62. Calculation unit for hardness amount in the flow path 63 Electrolytic tank precipitation amount calculation section 64 Drug Dosage Calculation Unit 65 Input Amount Control Unit 66 Cumulative amount calculation section 67 Memory section 68 Comparison Section

Claims

1. A water softening tank that softens raw water containing hardness components using a weakly acidic cation exchange resin, A neutralization tank in which the softened water that has passed through the aforementioned water softening tank is neutralized by a weakly basic anion exchange resin, An electrolytic cell that generates alkaline electrolyzed water used for regenerating the weakly basic anion exchange resin in a regeneration process, A chemical input unit for introducing chemicals used in an electrolytic cell cleaning process to dissolve precipitates deposited in the electrolytic cell into the electrolytic cell, A hardness measuring unit that determines the hardness of the raw water before it is softened in the water softening tank, A flow rate measuring unit for measuring the amount of raw water that has passed through the water softening tank, A control unit that controls the delivery of the aforementioned drug to the electrolytic cell, Equipped with, The control unit, A drug quantity calculation unit calculates the required amount of the drug necessary to dissolve the precipitate based on the hardness information identified by the hardness measuring unit and the amount of raw water measured by the flow rate measuring unit. A water softening apparatus comprising: an input amount control unit that controls the amount of the aforementioned chemical to be input to the electrolytic cell to the required amount calculated by the chemical amount calculation unit.

2. The control unit, An adsorbed hardness amount calculation unit calculates the amount of adsorbed hardness, which is the amount of hardness component adsorbed in the water softening tank, based on the hardness information and the amount of raw water. A channel hardness amount calculation unit calculates the amount of hardness components remaining in the regeneration channel through which water flows during the aforementioned regeneration process, and The electrolytic cell precipitate amount calculation unit calculates the amount of precipitate precipitate based on the adsorption hardness amount and the flow path hardness amount, The water softening apparatus according to claim 1, wherein the agent amount calculation unit calculates the required amount of the agent based on the amount of precipitate.

3. The control unit, A storage unit that stores predetermined cleaning standard values, An adsorbed hardness amount calculation unit calculates the amount of adsorbed hardness, which is the amount of hardness component adsorbed in the water softening tank, based on the hardness information and the amount of raw water. The cumulative amount calculation unit calculates the cumulative hardness amount calculated by the adsorption hardness amount calculation unit, and accumulates the adsorption hardness amount calculated by the adsorption hardness amount calculation unit, A comparison unit compares the cumulative hardness amount calculated by the cumulative amount calculation unit with the predetermined cleaning standard value stored in the storage unit. Equipped with, The water softening apparatus according to claim 1, wherein the cumulative hardness amount calculated by the cumulative amount calculation unit determines that the electrolytic cell cleaning treatment is necessary when the cumulative hardness amount calculated by the cumulative amount calculation unit is equal to or greater than the cleaning standard value, and terminates the regeneration treatment, and performs the electrolytic cell cleaning treatment using the required amount of the chemical calculated by the chemical amount calculation unit.

4. The predetermined cleaning standard value is, The water softening apparatus according to claim 3, wherein the value is predetermined based on the amount of hardness components adsorbed in the water softening tank, which generates a precipitate in an amount that necessitates the electrolytic cell cleaning treatment.

5. The chemical tank comprises a chemical storage section for storing the solid or liquid chemical, and a chemical dissolving section for dissolving the chemical in water to obtain chemical-containing water. The water softening apparatus according to claim 1, wherein the control unit puts the drug-containing water generated by the drug dissolving unit into the electrolytic cell.

6. The system includes a drug storage unit for storing the liquid drug as drug-containing water, The water softening apparatus according to claim 1, wherein the control unit puts the drug-containing water into the electrolytic cell.

7. A capture unit is provided downstream of the electrolytic cell and captures precipitates in the alkaline electrolyzed water, The water softening apparatus according to claim 1, wherein the precipitate is dissolved by passing the drug-containing water discharged from the electrolytic cell through the capture unit.

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