Water supply system

Abstract

A water supply system (1) includes a soft water generation device for generating acidic water and alkaline water by removing metal ions from water to be treated by electrolysis. The water supply system (1) also includes a water storage tank (200) for storing the acidic water or alkaline water generated by soft water generation device. The water supply system (1) further includes a device (300) which is connected to the water storage tank (200) and uses the acidic water or alkaline water stored in the water storage tank (200).

Description

water supply system

[0001] This disclosure relates to a water supply system.

[0002] Conventionally, technologies relating to water supply systems for supplying alkaline water to heat equipment such as boilers and water treatment equipment have been proposed. Patent Document 1 discloses a water supply system for supplying alkaline water to heat equipment, water treatment equipment, etc. In the water supply system disclosed in Patent Document 1, treated water softened by a water softening treatment device made of ion exchange resin is electrolyzed by an electrolysis device, and the resulting alkaline water is injected into a water supply tank that supplies water to the boiler.

[0003] Japanese Patent Publication No. 2005-319352

[0004] The water supply system disclosed in Patent Document 1 generates treated water for supplying equipment such as boilers using a water softening treatment device made of ion exchange resin and an electrolysis device. Therefore, in the water supply system disclosed in Patent Document 1, it is necessary to use both a water softening treatment device made of ion exchange resin and an electrolysis device, which makes the configuration of the water supply system complex and increases the scale of the system.

[0005] This disclosure has been made in view of the problems of the prior art. The purpose of this disclosure is to provide a water supply system that can realize a water supply system for equipment such as boilers with a simple configuration.

[0006] To solve the above problems, a water supply system according to an embodiment of the present disclosure comprises: a water softener that removes metal ions from water to be treated by electrolysis to produce acidic water and alkaline water; a water storage tank for storing the acidic water or alkaline water produced by the water softener; and equipment connected to the water storage tank for utilizing the acidic water or alkaline water stored in the water storage tank.

[0007] Figure 1 is a schematic diagram showing an example of the configuration of the water supply system according to this embodiment. Figure 2 is a schematic diagram showing an example of the configuration of the water treatment apparatus according to this embodiment. Figure 3 is a schematic diagram showing the state of metal ion movement and insolubilization in the electrolytic cell of the water treatment apparatus according to this embodiment. Figure 4 is a schematic diagram showing the state of hydrogen ion movement and neutralization in the electrolytic cell of the water treatment apparatus according to this embodiment. Figure 5 shows the state of carbonic acid (H) when carbonate ions are dissolved in water. ２ CO ３ ), bicarbonate ions (HCO3) ３ － ) and carbonate ions (CO ３ ２－ Figure 6 is a graph showing the relationship between the relative abundance of ) and pH. Figure 7 is a table for explaining the electrolytic control in the water treatment apparatus according to this embodiment. Figure 7 is a graph schematically showing the relationship between the conductivity of the treated water, the ion transfer rate and insolubilization rate of metal ions, and the water softening rate when only constant current control is performed, when only constant voltage control is performed, and when electrolytic control is performed. Figure 8 is a schematic diagram showing an example of the configuration of a water supply system according to another embodiment. Figure 9 is a schematic diagram showing an example of the configuration of a water supply system according to another embodiment.

[0008] The water supply system 1 according to this embodiment will be described in detail below with reference to the drawings. Note that the dimensional ratios in the drawings are exaggerated for illustrative purposes and may differ from the actual ratios.

[0009] (Water supply system 1) Figure 1 is a schematic diagram showing an example of the configuration of the water supply system 1 according to this embodiment. The water supply system 1 is composed of a water treatment device 100, a water storage tank 200, and equipment 300. The water supply system 1 may further include a water storage tank 400, a neutralization device 500, and a chemical treatment device 601.

[0010] Furthermore, the water supply system 1 includes first valves 701 to fifth valves 705 for adjusting the flow rate of water in each path. The water supply system 1 also includes first water quality sensors 801 to fifth water quality sensors 805 for detecting the water quality of the water flowing in each path.

[0011] The water treatment device 100 is a water softening device that uses electrolysis to produce softened water, which is then supplied to the equipment 300. In the example shown in Figure 1, raw water (water to be treated) is introduced through the first valve 701 and the first water quality sensor 801, and metal ions are removed by electrolysis to produce acidic water and alkaline water, which are then supplied to the downstream water storage tanks 200 and 400. In other words, in this embodiment, the treated water is softened water. The water treatment device 100 corresponds to a water softening device.

[0012] In the example shown in Figure 1, the acidic water generated by the water treatment device 100 is supplied to the water storage tank 400 via the third valve 703. The alkaline water generated by the water treatment device 100 is supplied to the water storage tank 200 via the second water quality sensor 802, the second valve 702, and the chemical treatment device 601. Details of the water softening process in the water treatment device 100 will be described later.

[0013] The water storage tank 200 stores alkaline water supplied from the water treatment device 100 and supplies it to the downstream equipment 300. The water storage tank 400 stores acidic water supplied from the water treatment device 100 and supplies it to the downstream neutralization device 500.

[0014] The device 300 is a device that utilizes softened water, and is a device that heats or cools the softened water for use. For example, the device 300 corresponds to a boiler or a cooling tower. In this embodiment, the device 300 does not include a faucet or the like that simply controls the flow of softened water.

[0015] The neutralization device 500 neutralizes the alkaline water wastewater generated by the equipment 300 with acidic water supplied from the water storage tank 400, and then discharges it. In other words, the neutralization device 500 mixes the wastewater from the equipment 300 with the acidic water produced by the water treatment device 100, which is a water softener, to produce neutral water.

[0016] Further, the neutralization device 500 detects the pH (hydrogen ion concentration) of the drained water by the fifth water quality sensor 805, and adjusts the flow rate of the acidic water in the fourth valve 704 so that the drained water becomes neutral. The fifth water quality sensor 805 corresponds to a pH sensor. Thereby, the water supply system 1 according to the present embodiment can prevent environmental pollution caused by draining alkaline water or acidic water by draining neutral treated water.

[0017] In the present embodiment, the chemical treatment device 601 corresponds to a free chlorine removal device that is a device for injecting a free chlorine remover. In the generation of soft water by electrolysis, free chlorine is generated by electrolysis. Therefore, the free chlorine removal device provided downstream of the water treatment device 100 can appropriately remove free chlorine and prevent deterioration of the downstream devices 300 and equipment. In the soft water generation device using ion exchange resin, chlorine deteriorates the resin, so it is different from the soft water generation device by electrolysis in that chlorine needs to be removed upstream of the device.

[0018] As described above, the water supply system 1 includes a soft water generation device that removes metal ions by electrolysis to generate acidic water and alkaline water from the water to be treated. The water supply system 1 also includes a water storage tank 200 that stores the acidic water or alkaline water generated by the soft water generation device. Further, the water supply system 1 includes a device 300 that is connected to the water storage tank 200 and uses the acidic water or alkaline water stored in the water storage tank 200. Thereby, the water supply system 1 according to the present embodiment does not need to use both a soft water treatment device using ion exchange resin and an electrolysis device, and can realize a system that supplies water to a device 300 such as a boiler with a simple configuration. The soft water generation device corresponds to the water treatment device 100.

[0019] Further, the water supply system 1 according to the present embodiment may include a chemical treatment device 601 downstream of the soft water generation device and upstream of the water storage tank 200. Thereby, the water supply system 1 can supply more appropriate alkaline water to the device 300.

[0020] Furthermore, the chemical treatment device 601 of the water supply system 1 according to this embodiment may be a device for introducing a free chlorine removal agent. This makes it possible for the water supply system 1 to remove free chlorine generated by the electrolysis of the water treatment device 100 and prevent deterioration of the downstream equipment 300.

[0021] Furthermore, the equipment 300 of the water supply system 1 according to this embodiment may be equipment that heats or cools treated water, which is acidic water or alkaline water, for use. This makes it possible for the water supply system 1 to supply appropriate acidic water or alkaline water with a simple configuration using equipment that heats or cools treated water for use.

[0022] Furthermore, the water storage tank 200 of the water supply system 1 according to this embodiment stores alkaline water, and the equipment 300 may be a boiler. This makes it possible for the water supply system 1 to supply appropriate alkaline water with a simple configuration in equipment that includes a boiler.

[0023] Furthermore, the water supply system 1 according to this embodiment may include a neutralization device 500 that mixes wastewater from the equipment 300 with acidic water produced by a water softener to produce neutral water. This allows the water supply system 1 to discharge neutral treated water, thereby preventing environmental pollution caused by the discharge of alkaline or acidic water.

[0024] Furthermore, the water supply system 1 according to this embodiment may be equipped with a pH sensor downstream of the neutralization device 500. The fifth water quality sensor 805 corresponds to the pH sensor. This enables the water supply system 1 to accurately produce neutral water in the neutralization device 500.

[0025] (Water Treatment Device 100) Next, the details of the water treatment device 100 will be described. As shown in Figure 2, the water treatment device 100 of this embodiment includes an electrolytic cell 10 that generates acidic water and alkaline water from water to be treated by electrolysis, a first flow path 20 through which acidic water circulates, and a second flow path 30 through which alkaline water circulates. The water treatment device 100 further includes a water to be treated flow path 40 for supplying water to be treated, a first discharge flow path 50 for discharging treated acidic water from the first flow path 20, and a second discharge flow path 60 for discharging treated alkaline water from the second flow path 30.

[0026] As shown in Figures 2 and 3, the electrolytic cell 10 comprises a solution tank 11, an anode 12, a cathode 13, and an ion-permeable membrane (ion-permeable membrane 14). The solution tank 11 is a container that holds the water to be treated, which contains metal ions, and electrolyzes the water held inside, as will be described later.

[0027] The anode 12 and cathode 13 are an electrode pair for electrolyzing the water to be treated in the solution tank 11. The anode 12 is located in the anode chamber 15, and the cathode 13 is located in the cathode chamber 16. The anode 12 and cathode 13 are arranged inside the solution tank 11, facing each other with an ion-permeable membrane 14 in between. The anode 12 is electrically connected to the positive electrode of the electrolysis power supply 90, and the cathode 13 is electrically connected to the negative electrode of the electrolysis power supply 90.

[0028] The ion-permeable membrane 14 is placed inside the solution tank 11 and divides the solution tank 11 into an anode chamber 15 and a cathode chamber 16. In other words, the anode chamber 15 is partitioned from a part of the solution tank 11 by the ion-permeable membrane 14, and the cathode chamber 16 is partitioned from the other part of the solution tank 11 by the ion-permeable membrane 14. The ion-permeable membrane 14 is a component that allows metal ions in the water to be treated to pass through. Therefore, the ion-permeable membrane 14 is not particularly limited as long as it is capable of allowing metal ions to pass through, and for example, a porous membrane or a cation exchange membrane can be used. Furthermore, the material of the porous membrane can be, for example, a ceramic material, a resin material, or a metal material, but is not particularly limited.

[0029] A first flow path 20 is connected to the anode chamber 15 of the electrolytic cell 10. In other words, the first flow path 20 is connected to the inlet 15a and outlet 15b of the anode chamber 15, respectively. In the first flow path 20, an acidic water tank 21 for temporarily storing acidic water and a first circulation pump 22 for pumping acidic water are located downstream of the anode chamber 15. Therefore, acidic water flowing out from the outlet 15b of the anode chamber 15 can pass through the acidic water tank 21 and the first circulation pump 22 and flow into the interior of the anode chamber 15 from the inlet 15a.

[0030] Similarly, a second flow path 30 is connected to the cathode chamber 16 of the electrolytic cell 10. In other words, the second flow path 30 is connected to the inlet 16a and outlet 16b of the cathode chamber 16, respectively. In the second flow path 30, an alkaline water tank 31 for temporarily storing alkaline water and a second circulation pump 32 for pumping alkaline water are located downstream of the cathode chamber 16. Therefore, alkaline water flowing out from the outlet 16b of the cathode chamber 16 can pass through the alkaline water tank 31 and the second circulation pump 32 and flow into the interior of the cathode chamber 16 from the inlet 16a.

[0031] The treated water channel 40 is a channel that supplies treated water to the electrolytic cell 10. Specifically, the treated water channel 40 branches into two channels and is connected to a first channel 20 and a second channel 30. Therefore, the treated water is supplied to both the first channel 20 and the second channel 30 through the treated water channel 40. The treated water channel 40 is also equipped with an electric valve 41 that switches between allowing and stopping the flow of treated water.

[0032] The first outflow channel 50 is connected to the downstream side of the first circulation pump 22 via a first electric valve 51. As will be described later, the first outflow channel 50 is a channel for discharging acidic water that has been treated to soften water in the electrolytic cell 10. A faucet 52 is provided at the end of the first outflow channel 50 to switch between allowing and stopping the flow of the treated acidic water. The treated water discharged from the first outflow channel 50 is treated water from which metal ions have been removed or reduced, and can be suitably utilized.

[0033] In the water treatment apparatus 100 according to this embodiment, the electric valve 41, the first electric valve 51, the second electric valve 61, and the faucet 52 are all general electric valves driven by actuators using a motor (electric motor). However, the valves used in the water treatment apparatus 100 are not limited to electric valves, and may be composed of, for example, electromagnetic valves driven by actuators (solenoids).

[0034] The second outflow channel 60 is connected to the downstream side of the second circulation pump 32 via a second electric valve 61. As will be described later, the second outflow channel 60 is a channel for discharging alkaline water that has been insolubilized in the electrolytic cell 10. The end of the second outflow channel 60 is connected to a faucet 52. The faucet 52 allows switching between the flow and shutoff of alkaline water that has been treated to remove insolubilized substances and softened by the filter 62. The treated water discharged from the second outflow channel 60 is water from which metal ions have been removed or reduced and can be suitably utilized.

[0035] The second outflow channel 60 is provided with a filter 62 for separating and removing insoluble substances consisting of metal ions that have been insoluble in the electrolytic cell 10. The filter 62 is not particularly limited as long as it can remove the insoluble substances, but a cartridge-type filter, a filtration layer using granular filter media, a cyclone-type solid-liquid separator, a hollow fiber membrane, etc., can be used.

[0036] As shown in Figure 2, a bypass channel 53 may be connected to the first electric valve 51 for supplying the softened acidic water to the filter 62. The acidic water that has been softened in the electrolytic cell 10 and is circulating in the first channel 20 has had its insoluble matter sufficiently reduced, but if necessary, the acidic water may be filtered by the filter 62 before being supplied to the faucet 52. In addition, a bypass channel 63 may be connected to the second electric valve 61 for supplying the alkaline water that has been insolublely treated in the electrolytic cell 10 directly to the faucet 52 without supplying it to the filter 62.

[0037] As shown in Figure 2, the water treatment apparatus 100 of this embodiment includes a first conductivity measuring unit 70 for measuring the conductivity of water flowing through the anode chamber and a second conductivity measuring unit 80 for measuring the conductivity of water flowing through the cathode chamber. In this specification, water flowing through the anode chamber is also referred to as anode water, and water flowing through the cathode chamber is also referred to as cathode water. The first conductivity measuring unit 70 is provided on the inlet 15a side of the anode chamber 15 in the first flow path 20, and the second conductivity measuring unit 80 is provided on the inlet 16a side of the cathode chamber 16 in the second flow path 30. However, the location of the first conductivity measuring unit 70 is not particularly limited as long as it can measure the conductivity of the anode water, and it may be provided, for example, inside the anode chamber 15 or inside the acidic water tank 21. Similarly, the location where the second conductivity measuring unit 80 is installed is not particularly limited as long as it can measure the conductivity of the cathode water. For example, it may be installed inside the cathode chamber 16 or inside the alkaline water tank 31.

[0038] The first conductivity measuring unit 70 and the second conductivity measuring unit 80 are connected to a control unit 101, which will be described later, and transmit the numerical values ​​of the conductivity of the anode water and cathode water measured by the first conductivity measuring unit 70 and the second conductivity measuring unit 80 to the control unit 101.

[0039] The water treatment apparatus 100 further includes an electrolytic power supply 90 and a control unit 101. The electrolytic power supply 90 is electrically connected to the anode 12 and the cathode 13. The electrolytic power supply 90 then flows current and applies voltage between the anode 12 and the cathode 13.

[0040] The control unit 101 is connected to the electrolytic power supply 90 and adjusts the voltage between the anode and cathode by controlling the electrolytic power supply 90. The control unit 101 is also connected to the electric valve 41, the first electric valve 51, the second electric valve 61, and the faucet 52 of the water to be treated flow path 40 and controls their opening and closing. Furthermore, the control unit 101 is connected to the first circulation pump 22 and the second circulation pump 32 and controls their operation.

[0041] Incidentally, when the control unit 101 executes operations based on a control program, it may include a storage device such as a ROM (Read Only Memory) or a RAM (Random Access Memory) that stores the control program. Further, the control unit 101 may include a microcomputer that executes the control program. Also, when the control unit 101 executes predetermined operations, it may include a dedicated electronic circuit or the like in which the control program is realized in hardware. Furthermore, the control unit 101 may include a timing unit such as an RTC (Real Time Clock) for measuring time. Additionally, the control unit 101 may include a measurement unit 120 that measures the conductivity based on the values measured by the conductivity sensors provided in the first conductivity measurement unit 70 and the second conductivity measurement unit 80.

[0042] When the water treatment apparatus 100 configured as described above operates, the following events are assumed. First, the conductivity of acidic water is in a proportional relationship with the ion concentration in the acidic water. Therefore, the conductivity of acidic water is in a proportional relationship with the concentration (hardness) of metal ions contained in the acidic water. Similarly, the conductivity of alkaline water is in a proportional relationship with the ion concentration in the alkaline water. Therefore, the conductivity of alkaline water is in a proportional relationship with the concentration (hardness) of metal ions contained in the alkaline water.

[0043] Next, when voltage is applied to the anode 12 and the cathode 13 with the water to be treated in the anode chamber 15 and the cathode chamber 16 of the electrolytic cell 10, as shown in FIG. 3, metal ions in the anode chamber 15 permeate through the ion permeable membrane 14 and move to the cathode chamber 16. That is, as shown by the electrophoresis velocity formula of Equation 1, the velocity ν (m / s) of ion electrophoresis is represented by the product of the ion mobility μ (m ２ / Vs) and the electric field E (V / m). Therefore, the movement of metal ions depends on the magnitude of the voltage (electric field). As shown in FIG. 4, when voltage is applied to the anode 12 and the cathode 13, hydrogen ions (H ＋ ) existing in the anode chamber 15 also move to the cathode chamber 16 and react with hydroxide ions (OH － ) to be neutralized. [Equation 1] ν = μE

[0044] Next, when the water to be treated is placed in the anode chamber 15 and cathode chamber 16 of the electrolytic cell 10 and electrolyzed, as shown in Figure 4 and Chemical Formula 1, hydrogen ions (H) are produced at the anode 12 by oxidation reaction. ＋ ) is generated, and at cathode 13, hydroxide ions (OH) are produced by a reduction reaction. － ) is produced. Note that this type of water electrolysis depends on the magnitude of the current. [Chemical Formula 1] Anode 12:2H ２ O → 4H ＋ +4e － +O ２ ↑ Cathode 13:4H ２ O+4e － → 4OH － +2H ２ ↑

[0045] And, magnesium ions (Mg) contained in the water to be treated ２＋ ) reacts with the generated hydroxide ions to form magnesium hydroxide (Mg(OH) ２ ) and becomes insoluble. Here, the solubility product K of magnesium hydroxide in water at 25°C. ｓｐ is 1.80 x 10 －１１ (mol / L) ３ And, as shown in equation 2, Mg ２＋ and OH － The ion product with the solubility product K ｓｐ If it becomes larger than that, Mg(OH) ２ The dissolution equilibrium shifts in the direction that Mg(OH) is produced, ２ An insoluble compound consisting of the above is formed. Therefore, in order to efficiently insolubilize magnesium ions, it is necessary to increase the pH, that is, to increase the hydroxide ions. [Equation 2] K ｓｐ <[Mg ２＋ ] [OH － ] ２

[0046] Furthermore, carbonate ions (CO2) are produced in the treated water due to the dissolution of carbonates from minerals and carbon dioxide from the air. ３ ２－ ) is included. And, calcium ions (Ca) contained in the water to be treated ２＋) reacts with carbonate ions to form calcium carbonate (CaCO3). ３ ) and becomes insoluble. Here, the solubility product K of calcium carbonate in water at 25°C. ｓｐ is 4.96 x 10 －９ (mol / L) ２ And, as shown in equation 3, Ca ２ + and CO ３ － The ion product with the solubility product K ｓｐ If it becomes larger than that, CaCO2 ３ Because the dissolution equilibrium shifts in the direction of CaCO2 formation, ３ An insoluble compound consisting of the above is formed. [Mathematics 3] K ｓｐ <[Ca ２＋ ] [CO ３ － ]

[0047] Here, in Figure 5, the carbonic acid (H) is shown when carbonate ions are dissolved in water. ２ CO ３ ), bicarbonate ions (HCO3) ３ － ) and carbonate ions (CO ３ ２－ This shows the relationship between the relative abundance of ions and pH. From Figure 5, it can be seen that the more alkaline the pH of water, the less carbonic acid and bicarbonate ions there are, and the more carbonate ions there are. Therefore, in order to efficiently insolubilize calcium ions, it is necessary to increase the pH and thus increase the carbonate ions.

[0048] Thus, the insolubilization of magnesium and calcium ions increases as the concentration of hydroxide ions increases. Furthermore, the electrolysis of water depends on the magnitude of the electric current. Therefore, the insolubilization of magnesium and calcium ions also depends on the magnitude of the electric current.

[0049] Next, based on the above-mentioned events, the operation of the water treatment apparatus 100 of this embodiment will be described. First, the control unit 101 opens the electric valve 41 and injects the raw water to be treated into the water to be treated flow path 40, the first flow path 20, and the second flow path 30. Furthermore, it injects the water to be treated into the anode chamber 15 and the cathode chamber 16 of the electrolytic cell 10, as well as the acidic water tank 21 and the alkaline water tank 31.

[0050] Next, the control unit 101 measures the conductivity of the anode water and cathode water using the first conductivity measuring unit 70 and the second conductivity measuring unit 80. Furthermore, the control unit 101 controls the electrolytic power supply 90 to flow current between the anode 12 and the cathode 13 to electrolyze the water to be treated. The control unit 101 also operates the first circulation pump 22 and the second circulation pump 32 to circulate the water to be treated in the first flow path 20 and the second flow path 30. By performing electrolysis and circulation of the water to be treated for a predetermined time, the water to be treated in the anode chamber 15, the first flow path 20 and the acidic water tank 21 becomes acidic water, and the water to be treated in the cathode chamber 16, the second flow path 30 and the alkaline water tank 31 becomes alkaline water.

[0051] The control unit 101 then measures the conductivity of the anode water (acidic water) and cathode water (alkaline water) at predetermined intervals. If the metal ions in the acidic and alkaline water have not been removed, both the acidic and alkaline water will have high conductivity, as shown in "(1) Insoluble Substance Formation" in Figure 6. Therefore, the control unit 101 controls the electrolytic power supply 90 to supply a constant current between the anode 12 and the cathode 13. This constant current control can be achieved by adjusting the current or voltage applied between the anode 12 and the cathode 13.

[0052] As mentioned above, the insolubilization of metal ions is current-dependent; therefore, constant current control promotes the insolubilization of metal ions in alkaline water. As a result, the concentration of metal ions decreases, and the conductivity of alkaline water declines. However, in acidic water, the insolubilization of metal ions is less likely to occur, so the conductivity remains high.

[0053] Next, if the conductivity measurement shows that the conductivity of alkaline water has decreased but the conductivity of acidic water remains high, the control unit 101 controls the electrolytic power supply 90 to apply a constant voltage between the anode 12 and the cathode 13, as shown in "(2) Ion Transfer" in Figure 6. This constant voltage control can be achieved by adjusting the voltage applied between the anode 12 and the cathode 13.

[0054] As described above, electrophoresis, in which metal ions move from the anode chamber 15 to the cathode chamber 16, is voltage-dependent. Therefore, when constant voltage control is performed, metal ions in the acidic water of the anode chamber 15 permeate the ion-permeable membrane 14 and move to the cathode chamber 16. As a result, the concentration of metal ions in the alkaline water of the cathode chamber 16 increases, and the conductivity of the alkaline water increases. Conversely, the concentration of metal ions in the acidic water decreases, and the conductivity of the acidic water decreases.

[0055] Here, as described above, when a constant voltage is applied to the anode 12 and cathode 13, hydrogen ions (H) present in the anode chamber 15 ＋ As the ions move to the cathode chamber 16, a neutralization reaction occurs and the pH decreases. If the pH of the alkaline water in the cathode chamber 16 decreases, the insolubilization of metal ions is suppressed. Therefore, if the control unit 101 measures the conductivity after constant current control and finds that the conductivity of the alkaline water has decreased but the conductivity of the acidic water has remained high, it calculates a voltage value that can maintain a high pH for the alkaline water. For example, the control unit 101 calculates and applies a voltage value that can maintain the pH of the alkaline water at 11 or higher.

[0056] Next, if the conductivity of alkaline water increases but the conductivity of acidic water decreases as a result of the conductivity measurement, the control unit 101 controls the electrolytic power supply 90 to flow a constant current between the anode 12 and the cathode 13, as shown in "(3) Insoluble matter formation" in Figure 6. This constant current control can be performed by adjusting the current or voltage applied between the anode 12 and the cathode 13.

[0057] As mentioned above, the insolubilization of metal ions is current-dependent; therefore, constant current control promotes the insolubilization of metal ions in alkaline water. As a result, the concentration of metal ions decreases, and the conductivity of alkaline water decreases.

[0058] Next, if the conductivity of both the acidic water and the alkaline water decreases as a result of measuring the conductivity, the control unit 101 determines that the water softening process has progressed for both the acidic water and the alkaline water, as shown in "(4) Water softening" in Figure 6.

[0059] In this manner, the control unit 101 measures the conductivity of the anode water and cathode water, then adjusts the voltage applied between the anode 12 and cathode 13 to perform electrolytic control by repeatedly switching between constant current control and constant voltage control. As a result, metal ions in the acidic water side undergo electrophoresis to the alkaline water side, and metal ions become insoluble in the alkaline water side, thus reducing the amount of metal ions in the water being treated. In this embodiment, the time taken for the electrolytic control is measured by the timing unit of the control unit 101, so the electrolytic control is performed until a predetermined time has elapsed.

[0060] Subsequently, the control unit 101 adjusts the first electric valve 51 to allow the acidic water in the first flow path 20 to flow into the first outlet flow path 50. The control unit 101 also adjusts the second electric valve 61 to allow the alkaline water in the second flow path 30 to flow into the second outlet flow path 60. The alkaline water then passes through the filter 62 provided in the second outlet flow path 60. Since the alkaline water flowing into the second outlet flow path 60 contains insoluble metal ions, these insoluble ions are removed as the alkaline water passes through the filter 62. By opening the faucet 52, the user can then use the softened acidic water and alkaline water. At this time, by arbitrarily mixing the acidic water and alkaline water, neutral treated water (neutral water) can be used.

[0061] Here, Figure 7 shows the relationship between the conductivity of the treated water, the ion transfer rate and insolubilization rate of metal ions, and the water softening rate when the control unit 101 performs only constant voltage control, which applies a constant voltage to the anode 12 and cathode 13 of the electrolytic cell 10 regardless of conductivity. Also, Figure 7 shows the relationship between the conductivity of the treated water, the ion transfer rate and insolubilization rate of metal ions, and the water softening rate when the control unit 101 performs only constant current control, which applies a constant current to the anode 12 and cathode 13 of the electrolytic cell 10 regardless of conductivity. Note that "ion transfer rate of metal ions" indicates the efficiency of metal ions moving from the anode chamber 15 to the cathode chamber 16. "Insolubilization rate of metal ions" indicates the efficiency of metal ions binding with hydroxide ions and carbonate ions and becoming insoluble. "Water softening rate" indicates the efficiency of metal ions being removed from the treated water.

[0062] As described above, the movement of metal ions depends on voltage (electric field). Therefore, when the control unit 101 performs constant voltage control, metal ions move from the anode chamber 15 to the cathode chamber 16 regardless of the conductivity of the water being treated, meaning that a high ion transfer rate can be maintained. However, since the insolubilization of metal ions depends on current, when constant voltage control is performed, the insolubilization rate improves when the conductivity of the water being treated is high, but decreases when the conductivity is low. Therefore, if the control unit 101 performs only constant voltage control and not constant current control, the water can be efficiently softened and the softening rate increased when the conductivity of the water being treated is high, i.e., when the concentration of metal ions is high. However, when the conductivity of the water being treated is low, i.e., when the concentration of metal ions is low, the insolubilization rate decreases, and therefore the softening rate also decreases. Thus, when the control unit 101 performs only constant voltage control, the softening rate is good when the concentration of metal ions is high, but the softening rate deteriorates when the concentration of metal ions is low.

[0063] In contrast, since the insolubilization of metal ions depends on the current, when the control unit 101 performs constant current control, metal ions are insolubilized regardless of the conductivity of the water being treated, meaning that a high insolubilization rate can be maintained. However, as mentioned above, since the movement of metal ions depends on the voltage, when constant current control is performed, the ion movement rate improves when the conductivity of the water being treated is low, but decreases when the conductivity is high. Therefore, if the control unit 101 performs only constant current control and not constant voltage control, it can efficiently soften the water and increase the water softening rate when the conductivity of the water being treated is low, i.e., when the concentration of metal ions is low. However, when the conductivity of the water being treated is high, i.e., when the concentration of metal ions is high, the ion movement rate decreases, and the water softening rate also decreases. Thus, when the control unit 101 performs only constant current control, the water softening rate is good when the concentration of metal ions is low, but the water softening rate deteriorates when the concentration of metal ions is high.

[0064] In the water treatment apparatus 100 of this embodiment, electrolytic control is performed by repeatedly switching between constant current control and constant voltage control by adjusting the voltage applied between the anode 12 and the cathode 13 according to the conductivity (hardness) of the anodic water and cathode water. As a result, the ion transfer rate and insolubilization rate are always kept high, and as a result, it is possible to obtain the desired water softening rate regardless of conductivity.

[0065] Furthermore, in the water treatment apparatus 100 of this embodiment, the first flow path 20 and the second flow path 30 are circulating flow paths. However, the water treatment apparatus is not limited to this configuration, and one-pass flow paths that do not circulate water may be used as the first and second flow paths. Moreover, a combination of a circulating flow path and a one-pass flow path may be used as the first and second flow paths. For this reason, in this specification, the circulating flow path and the one-pass flow path are collectively referred to as the "first flow path." Similarly, the circulating flow path and the one-pass flow path are collectively referred to as the "second flow path."

[0066] (Other Embodiments) Although these embodiments have been described above, the embodiments are not limited to these, and various modifications are possible within the scope of the gist of the embodiments. Furthermore, it is possible to combine some or all of the various embodiments to create new embodiments.

[0067] Figure 8 is a schematic diagram showing an example of the configuration of a water supply system 2 according to another embodiment. The example shown in Figure 8 differs from the water supply system 1 described above in that a downstream chemical treatment device 602 is provided downstream of the chemical treatment device 601. That is, the water supply system 2 is provided downstream of the chemical treatment device 601 and upstream of the water storage tank 200, with the downstream chemical treatment device 602 located therein.

[0068] The downstream chemical treatment device 602 may be a scale prevention device that adds polyacrylic acid or the like, or an active ion removal device that adsorbs or inactivates ions. For example, to prevent free chlorine from degrading the scale prevention agent, the downstream chemical treatment device 602 is installed downstream of the chemical treatment device 601, which is a free chlorine removal device. The chemical treatment device 601 and the downstream chemical treatment device 602 are composed of devices that add chemicals to softened water and perform filtration to remove unwanted substances. As a result, the water supply system 2 shown in Figure 8 can supply more appropriate alkaline water to equipment 300 such as a boiler.

[0069] Figure 9 is a schematic diagram showing an example of the configuration of a water supply system 3 according to another embodiment. In the example shown in Figure 9, the water softener 900 is provided downstream of the chemical treatment device 601 and upstream of the downstream chemical treatment device 602, which is different from the water supply systems 1 and 2 described above. The water softener 900 corresponds to the downstream water softener. The water supply system 3 shown in Figure 9 makes it possible to further reduce the hardness of the treated water, and scale can be better prevented in the equipment 300 that uses softened water. The water softener 900 may be provided downstream of the downstream chemical treatment device 602. The water softener 900 may also be a water softener that uses ion exchange resin or electrolysis.

[0070] (Note) The above description of embodiments discloses the following technology.

[0071] (Technology 1) A water supply system comprising: a water softener that removes metal ions from water to be treated by electrolysis to produce acidic water and alkaline water; a water storage tank for storing the acidic water or alkaline water produced by the water softener; and equipment connected to the water storage tank for using the acidic water or alkaline water stored in the water storage tank.

[0072] This configuration eliminates the need for both an ion exchange resin water softening device and an electrolysis device in the water supply systems 1, 2, and 3, making it possible to realize a system that supplies water to equipment 300 such as a boiler with a simple configuration.

[0073] (Technology 2) The water supply system according to Technology 1, wherein a chemical treatment device is provided downstream of the water softening device and upstream of the water storage tank.

[0074] This configuration allows the water supply systems 1, 2, and 3 to supply more appropriate acidic or alkaline water to the device 300.

[0075] (Technical 3) The water supply system according to Technical 2, wherein the chemical treatment device is a device for introducing a free chlorine removal agent.

[0076] This configuration allows the water supply systems 1, 2, and 3 to remove free chlorine generated by the electrolysis of the water treatment device 100, thereby preventing deterioration of the downstream equipment 300.

[0077] (Technical 4) The water supply system according to Technical 2 or 3, further comprising a downstream chemical treatment device located downstream of the chemical treatment device and upstream of the water storage tank.

[0078] This configuration allows the water supply system 2 to supply more appropriate acidic or alkaline water to equipment 300 such as a boiler.

[0079] (Technology 5) A water supply system according to any one of Technologies 1 to 4, comprising a downstream water softening device located downstream of the chemical treatment device and upstream of the water storage tank.

[0080] This configuration allows the water supply system 3 to further reduce the hardness of the treated water, thereby better preventing scaling in the equipment 300 that uses softened water.

[0081] (Technical 6) The water supply system according to any one of Technical 1 to 5, wherein the equipment is equipment that heats or cools the acidic water or the alkaline water for use.

[0082] This configuration allows the water supply systems 1, 2, and 3 to supply appropriate acidic or alkaline water to equipment that heats or cools the treated water, with a simple configuration.

[0083] (Technical 7) A water supply system according to any one of Technical 1 to 6, wherein the water storage tank stores the alkaline water, and the equipment is a boiler.

[0084] This configuration allows water supply systems 1, 2, and 3 to supply appropriate alkaline water to equipment equipped with a boiler with a simple configuration.

[0085] (Technology 8) A water supply system according to any one of Technologies 1 to 7, comprising a neutralization device that mixes the wastewater from the equipment with the acidic water produced by the water softener to produce neutral water.

[0086] This configuration allows water supply systems 1, 2, and 3 to discharge neutral treated water, thereby preventing environmental pollution caused by the discharge of alkaline or acidic water.

[0087] (Technical 9) The water supply system according to Technical 8, further comprising a pH sensor downstream of the neutralization device.

[0088] This configuration enables the water supply systems 1, 2, and 3 to accurately generate neutral water in the neutralization device 500.

[0089] Although this embodiment has been described above, this embodiment is not limited to these, and various modifications are possible within the scope of the gist of this embodiment.

[0090] The entire contents of Japanese Patent Application No. 2024-230923 (Filing Date: December 26, 2024) are incorporated herein by reference.

[0091] According to this disclosure, it is possible to provide a water supply system that realizes a system for supplying water to equipment such as boilers with a simple configuration.

[0092] 1, 2, 3 Water supply system 10 Electrolytic cell 100 Water treatment device 101 Control unit 200, 400 Water storage tank 300 Equipment 500 Neutralization device 601 Chemical treatment device 602 Downstream chemical treatment device 701 First valve 702 Second valve 703 Third valve 704 Fourth valve 705 Fifth valve 801 First water quality sensor 802 Second water quality sensor 803 Third water quality sensor 804 Fourth water quality sensor 805 Fifth water quality sensor 900 Water softening device

Claims

1. A water supply system comprising: a water softener that removes metal ions from water to be treated by electrolysis to produce acidic water and alkaline water; a water storage tank for storing the acidic water or alkaline water produced by the water softener; and equipment connected to the water storage tank for utilizing the acidic water or alkaline water stored in the water storage tank.

2. The water supply system according to claim 1, further comprising a chemical treatment device downstream of the water softening device and upstream of the water storage tank.

3. The water supply system according to claim 2, wherein the chemical treatment device is a device for introducing a free chlorine removal agent.

4. The water supply system according to claim 2 or 3, further comprising a downstream chemical treatment device downstream of the chemical treatment device and upstream of the water storage tank.

5. The water supply system according to any one of claims 2 to 4, comprising a downstream water softening device downstream of the chemical treatment device and upstream of the water storage tank.

6. The water supply system according to any one of claims 1 to 5, wherein the equipment is equipment for heating or cooling the acidic water or the alkaline water for use.

7. The water supply system according to any one of claims 1 to 6, wherein the water storage tank stores the alkaline water, and the equipment is a boiler.

8. A water supply system according to any one of claims 1 to 7, comprising a neutralization device that mixes the wastewater from the equipment with the acidic water produced by the water softener to produce neutral water.

9. The water supply system according to claim 8, further comprising a pH sensor downstream of the neutralization device.

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