Softening device

Abstract

To provide a water softening device capable of lowering a hardness of softened water.SOLUTION: A water softening device includes: an electrolysis device that generates alkaline water and acidic water by electrolysis; a first circulation channel and a second circulation channel connected to the electrolysis device and capable of alternately passing alkaline water and acidic water generated by the electrolysis device; a first sensor detecting a parameter of water flowing in the first circulation channel; a second sensor detecting a parameter of water flowing in the second circulation channel; and a control unit. The control unit controls the electrolysis device to execute a first mode in which alkaline water flows in the first circulation channel and acid water flows in the second circulation channel, and a second mode in which acid water flows in the first circulation channel and alkaline water flows in the second circulation channel. The electrolysis device is controlled to stop electrolysis of the electrolysis device based on a detection value of the first sensor or the second sensor in the first mode and the second mode.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] In hard water areas, there are problems caused by hardness components such as scale and water scale, and a water softening device is required. As a water softening device, there is a water softening method using ion exchange resin (see, for example, Patent Document 1), but there is a problem that salt waste liquid is generated because regeneration is performed with salt. In addition, there are water softening methods using EDI, RO membranes, etc. (see, for example, Patent Document 2), but there is a problem that the amount of waste water is large.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] A water softening device that softens water using electrolysis can be considered. In a water softening device using electrolysis, it is desirable to make the hardness of the finally produced soft water lower.

[0005] Therefore, an object of the present invention is to solve the above problems and provide a water softening device capable of making the hardness of soft water lower.

Means for Solving the Problems

[0006] To achieve the above object, the water softening device of the present invention includes an electrolysis device that generates alkaline water and acidic water by electrolysis, a circulation flow path connected to the electrolysis device, the first circulation flow path and the second circulation flow path through which the alkaline water and acidic water generated by the electrolysis device can alternately flow, a first sensor that detects parameters of the water flowing through the first circulation flow path, a second sensor that detects parameters of the water flowing through the second circulation flow path, and a control unit. The control unit controls the electrolysis device to execute a first mode in which alkaline water is passed through the first circulation flow path and acidic water is passed through the second circulation flow path, and a second mode in which acidic water is passed through the first circulation flow path and alkaline water is passed through the second circulation flow path, and controls the electrolysis of the electrolysis device to stop based on the detection value of the first sensor or the second sensor in the first mode and the second mode.

Effect of the Invention

[0007] According to the water softening device of the present invention, the hardness of the softened water can be made lower.

Brief Description of the Drawings

[0008]

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Figure 18A

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Figure 18C

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described in detail based on the drawings. Note that the present invention is not limited by these embodiments.

[0010] (Embodiment) Fig. 1 is a schematic diagram of the water softening device 2 in the embodiment.

[0011] The water softening device 2 is a device for removing metal ions as hardness components from water using electrolysis. The metal ions here refer to calcium ions (Ca 2+ ) and magnesium ions (Mg 2+ ). The water softening device 2 in the embodiment is a water softening device that produces soft water by removing and separating metal ions from hard water to reduce the concentration (hardness) of metal ions in hard water to a predetermined concentration or less. As the definitions of hard water and soft water, for example, the definitions of the WHO may be used. That is, water with a hardness of less than 120 mg / L may be defined as soft water, and water with a hardness of 120 mg / L or more may be defined as hard water.

[0012] The water softening device 2 shown in FIG. 1 includes raw water flow paths 4A and 4B, batch treatment tanks 6A and 6B, circulation flow paths 8A and 8B, a pump 10, an electrolysis device 12, pH sensors 14A and 14B, a separation device 16, an intermediate tank 18, a water storage tank 20, and a control unit 21. The water softening device 2 further includes, as various valves, valves 22A and 22B, valve 24, valve 26, valves 28A and 28B, valve 30, and valve 32.

[0013] The raw water flow paths 4A and 4B are flow paths for supplying raw water to the batch treatment tanks 6A and 6B, respectively. The raw water is, for example, hard water. The upstream sides of the raw water flow paths 4A and 4B are connected to a water source (not shown), and the downstream sides are connected to the batch treatment tanks 6A and 6B. Valves 22A and 22B are provided in the raw water flow paths 4A and 4B, respectively. By opening and closing the valves 22A and 22B, the flow of water / stopping of water from the raw water flow paths 4A and 4B to the batch treatment tanks 6A and 6B is controlled, respectively.

[0014] The batch treatment tanks 6A and 6B are water storage tanks for performing batch treatment, respectively. Float sensors (not shown) are provided in the batch treatment tanks 6A and 6B, respectively, and the water storage amounts can be detected respectively. Circulation flow paths 8A and 8B are connected to the batch treatment tanks 6A and 6B, respectively.

[0015] The circulation channels 8A and 8B are two circulation channels connected to the batch processing tanks 6A and 6B. The circulation channels 8A and 8B each extend downstream from the batch processing tanks 6A and 6B and merge at a location connected to the valve 24 to form one channel. The circulation channels 8A and 8B that have become one channel are connected to the electrolysis device 12 via the pump 10 and the valve 26.

[0016] The water flow / stop from the batch processing tanks 6A and 6B to the electrolysis device 12 is controlled by the opening and closing of the valve 24 and the valve 26. By driving the pump 10 provided between the valve 24 and the valve 26, water is passed downstream from the batch processing tanks 6A and 6B.

[0017] The electrolysis device 12 is a device that generates alkaline water and acidic water by electrolyzing the water supplied through the circulation channels 8A and 8B. The electrolysis device 12 includes a + electrode (anode) and a - electrode (cathode), and a diaphragm provided between both electrodes. By applying a voltage between the + electrode and the - electrode, water is electrolyzed to generate alkaline water and acidic water.

[0018] The circulation channels 8A and 8B are connected to the downstream side of the electrolysis device 12 as two channels.

[0019] The circulation channels 8A and 8B connected to the downstream side from the electrolysis device 12 can each alternately pass the alkaline water and acidic water generated by the electrolysis device 12. When the circulation channel 8A passes alkaline water, the circulation channel 8B passes acidic water, and when the circulation channel 8A passes acidic water, the circulation channel 8B passes alkaline water.

[0020] The circulation channel 8A connected to the downstream side of the electrolysis device 12 is provided with a valve 28A and a pH sensor 14A in the middle thereof, and is connected to the batch treatment tank 6A. Similarly, the circulation channel 8B connected to the downstream side of the electrolysis device 12 is provided with a valve 28B and a pH sensor 14B in the middle thereof, and is connected to the batch treatment tank 6B. By opening and closing the valves 28A and 28B, the water flow / stop from the electrolysis device 12 to the batch treatment tanks 6A and 6B is controlled respectively.

[0021] The circulation channels 8A and 8B having the above-described configuration respectively constitute a circulation channel that returns from the batch treatment tanks 6A and 6B to the batch treatment tanks 6A and 6B via the electrolysis device 12. The circulation channels 8A and 8B of the present embodiment merge at a location from the valve 24 to the electrolysis device 12 to form a single channel. Compared with the case where the circulation channels 8A and 8B are independent channels without merging, the device configuration of the water softening device 2 can be simplified, such as only one pump 10 being required.

[0022] The pH sensors 14A and 14B are sensors for detecting the pH value as a parameter of the water flowing through the circulation channels 8A and 8B respectively. The pH values detected by the pH sensors 14A and 14B are used as parameters for determining the continuation / stop of electrolysis by the electrolysis device 12, as will be described later. Details will be described later.

[0023] A valve 26 provided at a location where the circulation channels 8A and 8B merge into a single channel is connected to a flow path 34 in addition to the circulation channels 8A and 8B. The flow path 34 is connected to the separation device 16.

[0024] The separation device 16 is a device that separates metal component crystals from the water supplied from the flow path 34. The separation device 16 of the embodiment is a cyclone type separation device that separates solids such as crystals contained in water by centrifugal separation.

[0025] The separation device 16 is connected with a flow path 36 and a flow path 38 as two flow paths. The flow path 36 is a flow path through which water from which crystals have been separated by the separation device 16 passes. The flow path 38 is a drainage flow path through which drainage containing crystals separated by the separation device 16 passes, and extends outside the system of the water softening device 2.

[0026] The flow path 36 through which water from which crystals have been separated passes is connected to a valve 30. A flow path 40 and a flow path 41 are connected to the valve 30.

[0027] The flow path 40 is a flow path connected to the intermediate tank 18. The intermediate tank 18 is a tank for temporarily storing water passing through the flow path 40. By opening and closing the valve 30, the flow of water from the separation device 16 to the intermediate tank 18 through the flow paths 36 and 40 is controlled.

[0028] The flow path 41 is a bypass flow path for connecting between the batch processing tanks 6A and 6B and the intermediate tank 18 without passing through the electrolysis device 12 and the separation device 16. Two flow paths 41A and 41B are connected to the flow path 41, and the flow paths 41A and 41B are respectively connected to the aforementioned valves 28A and 28B.

[0029] A CO2 supply line 42 is connected to the intermediate tank 18. The CO2 supply line 42 is a pipe for supplying CO2 gas to the water stored in the intermediate tank 18. By supplying CO2 gas through the CO2 supply line 42, the turbidity of the water stored in the intermediate tank 18 can be reduced. A valve 32 is provided in the middle of the CO2 supply line 42, and the supply / stop of CO2 gas is controlled by opening and closing the valve 32.

[0030] A further flow path 44 is connected to the intermediate tank 18. The flow path 44 is connected to the water storage tank 20.

[0031] The water storage tank 20 is a tank for storing treated water for which the water softening treatment has been completed. The treated water stored in the water storage tank 20, that is, the soft water, can be supplied to a faucet or the like for use by the end user.

[0032] The water storage tank 20 is provided with a pressure sensor (not shown). By detecting the pressure drop associated with the consumption of the treated water with the pressure sensor, the water storage volume of the water storage tank 20 can be detected.

[0033] The control unit 21 is a member that controls each component of the water softening device 2 described above. The control unit 21 is electrically connected to each component of the water softening device 2, and executes opening / closing control of each valve, ON / OFF control of the pump 10, ON / OFF control of the electrolysis device 12, ON / OFF control of the separation device 16, etc. The control unit 21 is composed of, for example, a microcomputer including a processor and a memory storing a computer program executed by the processor.

[0034] The control unit 21 of the present embodiment operates the water softening device 2 in each of a first mode and a second mode as two operation modes.

[0035] First, the first mode will be described with reference to FIGS. 2 and 3 to 8. FIG. 2 is a flowchart when the first mode is executed using the water softening device 2. FIGS. 3 to 8 are schematic diagrams showing the flow of water and the like when the first mode is executed along the flowchart shown in FIG. 2.

[0036] (First raw water injection mode) As shown in FIG. 2, the control unit 21 first executes the first raw water injection mode (S1-1). The first raw water injection mode is a mode in which hard water, which is raw water, is injected into the water softening device 2 when starting the operation of the water softening device 2. Specifically, the control unit 21 controls to cause a flow as shown in FIG. 3. In the drawings after FIG. 3, the flow of water is represented by an arrow, and it is assumed that no water flow occurs in the flow path without an arrow. Also, the open state of the valve is represented by hatching, and the closed state of the valve is represented by being painted black.

[0037] The control unit 21 opens the valve 22A so that raw water flows through the raw water flow path 4A. By flowing the raw water through the raw water flow path 4A, the raw water is passed through the raw water flow path 4A into the batch treatment tank 6A and stored in the batch treatment tank 6A. At this time, the control unit 21 controls to close the valve 22B.

[0038] When a predetermined amount (for example, 10 L) of raw water has flowed through the batch treatment tank 6A, the control unit 21 closes the valve 22A and executes the first crystallization treatment mode (step S2-1).

[0039] (First crystallization treatment mode) FIG. 4 shows the first crystallization treatment mode. The control unit 21 controls to supply the raw water stored in the batch treatment tank 6A to the electrolysis device 12. Specifically, while driving the pump 10, the valve 24 is opened to allow water to flow from the batch treatment tank 6A into the circulation flow path 8A, and the valve 26 is opened to allow water to flow into the electrolysis device 12. At this time, the control unit 21 controls the opening and closing of the valve 24 to stop the water flow from the batch treatment tank 6B to the downstream side.

[0040] The control unit 21 further drives the electrolysis device 12 to electrolyze the raw water supplied from the batch treatment tank 6A, thereby generating alkaline water and acidic water.

[0041] In the first crystallization treatment mode, the electrolysis device 12 is controlled so that, among the alkaline water and acidic water generated by the electrolysis device 12, the alkaline water flows through the circulation flow path 8A and the acidic water flows through the circulation flow path 8B.

[0042] The control unit 21 controls the opening and closing of the valve 28A so that the alkaline water flowing through the circulation flow path 8A returns to the batch treatment tank 6A, and controls the opening and closing of the valve 28B so that the acidic water flowing through the circulation flow path 8B returns to the batch treatment tank 6B. As a result, the flow indicated by the arrow as shown in FIG. 4 occurs.

[0043] According to the above operation, while consuming the raw water in the batch treatment tank 6A, alkaline water approximately half the amount of the consumption is newly stored in the batch treatment tank 6A. As a result, the water storage volume decreases, and the pH value detected by the pH sensor 14A increases. On the other hand, in the batch treatment tank 6B, acidic water is stored, so the water storage volume increases, and the pH value detected by the pH sensor 14B is maintained at a low value.

[0044] In the circulation channel 8A including the batch treatment tank 6A, while the mixed water of raw water and alkaline water circulates, electrolysis by the electrolysis device 12 is continuously performed, and the pH value also continuously increases.

[0045] Here, metal ions such as Ca 2+ and Mg 2+ in the raw water electrophorese from the anode (acidic water) to the cathode (alkaline water) through the diaphragm by electrolysis, so the hardness of the acidic water decreases. On the other hand, even in alkaline water containing a large amount of OH - , the hardness of the water decreases due to the occurrence of the reactions of the following formulas 1 to 3.

[0046] (Formula 1) OH - +HCO3 - →H2O+CO3 2- (Formula 2) Ca 2+ +CO3 2- →CaCO3 (Formula 3) Mg 2+ +2OH - →Mg(OH)2

[0047] As in Formula 1, OH - contained in the alkaline water reacts with HCO3 - (bicarbonate ion) in the water to generate water and produce CO3 2- (carbonate ion). The CO3 2- generated by the reaction of Formula 1 reacts with Ca 2+ as in Formula 2 to produce insoluble CaCO3 (calcium carbonate). As in Formula 3, Mg2+ reacts with OH contained in the alkaline water - to produce insoluble Mg(OH)2 (magnesium hydroxide). As CaCO3 and Mg(OH)2 crystallize and precipitate, the concentration of metal ions in the alkaline water also decreases, so the hardness of the alkaline water decreases. As a result, the hardness of both acidic water and alkaline water decreases.

[0048] By continuously supplying and circulating alkaline water in the circulation channel 8A, the reactions of the above formulas 1 to 3 can be continuously caused to crystallize and precipitate metal ions in the alkaline water, thereby reducing the hardness of the raw water.

[0049] The control unit 21 ends the first crystallization treatment mode at a predetermined timing and executes the next first acidic water supply mode (step S3-1). The timing for ending the first crystallization treatment mode is determined based on the pH value of the alkaline water detected by the pH sensor 14A. Details will be described later.

[0050] (First acidic water supply mode) FIG. 5 shows the first acidic water supply mode. The control unit 21 controls to supply the acidic water stored in the batch treatment tank 6B to the intermediate tank 18 via the separation device 16. Specifically, while driving the pump 10, the valve 24 is opened to allow water to flow from the batch treatment tank 6B into the circulation channel 8B, and the valve 26 is opened to allow water to flow from the circulation channel 8B into the channel 34.

[0051] The control unit 21 does not operate the separation device 16 and allows the acidic water reaching the separation device 16 to pass through as it is and flow into the channel 36. The control unit 21 further opens the valve 30 to allow the acidic water flowing through the channel 36 to flow into the channel 40. Thereby, the acidic water is passed through the channel 40 into the intermediate tank 18.

[0052] According to the above operation, while the storage volume of acidic water in the intermediate tank 18 increases, the storage volume of acidic water in the batch treatment tank 6B decreases. The control unit 21 of the present embodiment continues the first acidic water supply mode until the acidic water in the batch treatment tank 6B decreases to a predetermined amount (for example, 2L). When the storage volume of the batch treatment tank 6B decreases to the predetermined amount, the control unit 21 stops the first acidic water supply mode and executes the next first alkaline water supply mode (S4-1).

[0053] (First alkaline water supply mode) FIG. 6 shows the first alkaline water supply mode. The control unit 21 controls to supply the alkaline water stored in the batch treatment tank 6A to the intermediate tank 18 via the separation device 16. In the first acidic water supply mode described above, the operation of the separation device 16 was stopped, whereas in the first alkaline water supply mode, the separation device 16 is operated to separate crystals from the alkaline water.

[0054] As shown in FIG. 6, while driving the pump 10, the valve 24 is opened so that water flows from the batch treatment tank 6A into the circulation channel 8A, and the valve 26 is opened so that water flows from the circulation channel 8A into the channel 34.

[0055] The control unit 21 separates the crystals contained in the alkaline water by centrifugation by operating the separation device 16. The separation device 16 allows the alkaline water from which the crystals have been separated to flow through the channel 36, and discharges the drainage containing the crystals through the channel 38.

[0056] The alkaline water after crystal separation that has flowed through the channel 36 flows through the channel 40 into the intermediate tank 18. Since acidic water is already stored in the intermediate tank 18, the alkaline water and the acidic water are mixed in the intermediate tank 18. The mixed water of the alkaline water and the acidic water is neutralized, and the pH value becomes a value near neutral. Since both the alkaline water and the acidic water have a low hardness as described above, the hardness of the mixed water also becomes low. As a result, the mixed water stored in the intermediate tank 18 is generated as soft water with a pH value near neutral and a low hardness.

[0057] The alkaline water supplied to the intermediate tank 18 may contain crystals of CaCO3 that could not be separated by the separation device 16. The control unit 21 controls the opening and closing of the valve 32 to supply CO2 from the CO2 supply line 42 to the intermediate tank 18 as necessary, thereby supplying CO2 to the intermediate tank 18. This promotes the reaction of Equation 4 below.

[0058] (Equation 4) CaCO3 + CO2 + H2O → Ca(HCO3)2

[0059] The crystalline CaCO3 reacts with CO2 and H2O to produce soluble Ca(HCO3)2. By this reaction, the crystals can be dissolved in water, and the turbidity of the treated water can be reduced. Note that the reaction formula for Mg 2+ is omitted.

[0060] According to the above operation, while the water storage volume of the mixed water in the intermediate tank 18 increases, the water storage volume of the alkaline water in the batch treatment tank 6A decreases. The control unit 21 of the present embodiment continues the first alkaline water supply mode until the water storage volume of the batch treatment tank 6A runs out. When the water storage volume of the batch treatment tank 6A runs out, the control unit 21 stops the first alkaline water supply mode and executes the next first pipe cleaning mode (S5-1).

[0061] (First Pipe Cleaning Mode) FIG. 7 shows the first pipe cleaning mode. The control unit 21 controls the acidic water remaining in the batch treatment tank 6B to return to the batch treatment tanks 6A and 6B via the separation device 16 and the bypass channels 41, 41A, and 41B.

[0062] Specifically, while driving the pump 10, the valve 24 is opened to allow water to flow from the batch treatment tank 6B to the circulation channel 8B, and the valve 26 is opened to allow water to flow from the circulation channel 8B to the channel 34. The control unit 21 does not operate the separation device 16 and allows the acidic water reaching the separation device 16 to pass through as it is and flow into the channel 36.

[0063] The control unit 21 further controls the opening and closing of the valve 30 so that the acidic water flowing through the flow path 36 flows into the flow paths 41 and 41A, 41B. The control unit 21 further controls the opening and closing of the valves 28A, 28B so that the acidic water flowing through the flow paths 41A, 41B flows into the batch processing tanks 6A, 6B through the circulation flow paths 8A, 8B.

[0064] As a result, a flow of acidic water as shown in FIG. 7 occurs. As the acidic water flows through each pipe, the scale (CaCO3) adhering to the inner wall surface of each pipe is dissolved in the acidic water, and each pipe can be cleaned.

[0065] According to the above operation, the water storage amount of the acidic water in the batch processing tank 6A increases, and the water storage amount of the acidic water in the batch processing tank 6B decreases. When the control unit 21 passes a predetermined amount (for example, 1 L) of acidic water through the batch processing tank 6B, it ends the first pipe cleaning mode and executes the next first electrolytic cell cleaning mode (S6-1).

[0066] (First electrolytic cell cleaning mode) FIG. 8 shows the first electrolytic cell cleaning mode. The control unit 21 controls so that the acidic water remaining in the batch processing tank 6B returns to the batch processing tanks 6A, 6B via the electrolysis device 12.

[0067] Specifically, while driving the pump 10, the valve 24 is opened so that water flows from the batch processing tank 6B into the circulation flow path 8B, and the valve 26 is opened so that water flows from the circulation flow path 8B into the electrolysis device 12. The control unit 21 does not operate the electrolysis device 12, and allows the acidic water reaching the electrolysis device 12 to pass through without electrolysis and flow into the circulation flow paths 8A, 8B. The control unit 21 further controls the opening and closing of the valves 28A, 28B so that the acidic water coming out of the electrolysis device 12 flows into the batch processing tanks 6A, 6B through the circulation flow paths 8A, 8B.

[0068] As a result, a flow of acidic water as shown in FIG. 8 occurs. As the acidic water flows through the electrolysis device 12 and each pipe, the scale adhering to the inner wall surfaces of the electrolysis device 12 and each pipe is dissolved in the acidic water, and the electrolysis device 12 and each pipe can be cleaned.

[0069] According to the above operation, the water storage amount of the acidic water in the batch treatment tank 6A increases, while the water storage amount of the acidic water in the batch treatment tank 6B decreases. When the control unit 21 passes a predetermined amount (for example, 1 L) of acidic water through the batch treatment tank 6B, the first electrolytic bath cleaning mode ends. The acidic water remaining in the batch treatment tanks 6A and 6B may be discarded thereafter.

[0070] By executing the above-described steps S1-1 to S6-1, the execution of the first mode is completed.

[0071] Here, a method for determining the continuation / stop of electrolysis of the electrolysis device 12 in the first crystallization treatment mode (S2-1) will be described with reference to FIGS. 4 and 9. FIG. 9 is a flowchart showing an example of a method for determining the continuation / stop of electrolysis of the electrolysis device 12.

[0072] In the water flow of the water softening device 2 shown in FIG. 4, the control unit 21 monitors the pH value of the alkaline water based on the detection value periodically transmitted from the pH sensor 14A. As shown in FIG. 9, the control unit 21 determines whether or not the fluctuation value within a predetermined period is within a predetermined range with respect to the pH value of the alkaline water (S7: first determination). The predetermined period is, for example, 1 minute, and the predetermined range is, for example, -0.02 to 0.02.

[0073] In the first determination, when it is determined that the fluctuation value within the predetermined period is not within the predetermined range (NO in S7), the control unit 21 executes step S7 again. In the first determination, when it is determined that the fluctuation value within the predetermined period is within the predetermined range (YES in S7), the control unit 21 then determines whether or not the increase value within the predetermined period is equal to or greater than a predetermined value with respect to the pH value of the alkaline water (S8: second determination). The predetermined period is, for example, 1 minute, and the predetermined value is, for example, 0.05.

[0074] In the second determination, when it is determined that the increase value during a predetermined period is not greater than a predetermined value (NO in S8), the control unit 21 executes step S8 again. In the second determination, when it is determined that the increase value during a predetermined period is greater than or equal to the predetermined value (YES in S8), the control unit 21 stops the electrolysis by the electrolysis device 12 (S9). By stopping the electrolysis, the first crystallization treatment mode (S2-1) is terminated, and the process proceeds to the first acidic water supply mode (S3-1).

[0075] An example of experimental data related to the method for determining continuation / stop of electrolysis described with reference to FIG. 9 is shown in FIG. 10. FIG. 10 is a graph showing the time change of "alkaline pH" and "ion separation rate" when the first crystallization treatment mode is carried out under predetermined conditions. The horizontal axis represents time, and the vertical axis represents "alkaline pH" and "ion separation rate".

[0076] "Alkaline pH" is the detected value of the pH sensor 14A and indicates the pH value of the alkaline water (unitless). "Ion separation rate" is the ratio obtained by dividing the hardness of the acidic water after electrolysis by the hardness of the raw water before electrolysis (unit: %). The ion separation rate is an index indicating the degree to which the hardness of the raw water has decreased due to electrolysis. The higher the ion separation rate, the lower the hardness of the acidic water. The ion separation rate is calculated by detecting the hardness of the raw water and the acidic water using a hardness sensor (not shown).

[0077] As shown in FIG. 10, when the electrolysis by the electrolysis device 12 is started, the value of "alkaline pH" increases with the generation of alkaline water. On the other hand, since metal ions are attracted to the alkaline water by electrophoresis and the hardness of the acidic water decreases, the "ion separation rate" also increases.

[0078] Thereafter, the increase in alkaline pH and the increase in ion separation rate stop, and a steady state is reached (about 2 minutes after the start). In the steady state, the reactions of the above-described formulas 1 to 3 proceed, and the crystallization of the metal components progresses.

[0079] After the steady state continues for several minutes (from about 2 minutes to about 8 minutes after the start), the alkaline pH begins to rise again, and the ion separation rate begins to decrease rapidly.

[0080] The reason for the alkaline pH to rise again is that as the reactions of Formulas 1 to 3 proceed, substances (such as HCO3 - ) required for the reactions of Formulas 1 to 3 decrease in water, the reactions of Formulas 1 to 3 become sluggish, and the consumption of OH - decreases. Also, the reason for the decrease in the ion separation rate is that as crystallization proceeds due to the reactions of Formulas 1 to 3 and the crystal mass increases, as shown in Formula 5 below, the CaCO3 crystals dissolve in acid (H + ) to produce Ca 2+ , and the hardness of the acidic water increases. Note that the reaction formula for Mg(OH)2 is omitted.

[0081] (Formula 5) CaCO3 + H + →Ca 2+ + HCO3 -

[0082] In view of the fact that "alkaline pH" and "ion separation rate" show the behavior as shown in FIG. 10, the control unit 21 of the present embodiment executes the above-described first determination (S7) and second determination (S8).

[0083] By determining whether the fluctuation value of the alkaline pH within a predetermined period is within a predetermined range by the first determination (S7), it is possible to determine whether it is the steady state (the period from about 2 minutes to about 8 minutes) shown in the graph of FIG. 10.

[0084] Furthermore, after determining that it is the steady state by the first determination (S7), by the second determination (S8), it is determined whether the increase value of the alkaline pH within a predetermined period is equal to or greater than a predetermined value. Thereby, it is possible to determine whether the alkaline pH has risen again (after about 8 minutes) as shown in the graph of FIG. 10.

[0085] When an increase in the alkaline pH is detected by the second determination (S8), by controlling to stop the electrolysis of the electrolysis device 12 (S9), the electrolysis can be stopped at a point in time (about 8 minutes later) before the ion separation rate starts to rapidly decrease. Thereby, the hardness of the acidic water generated by electrolysis can be maintained at a low value, and the hardness of the soft water finally produced by mixing the acidic water and the alkaline water can also be reduced. In this way, in the water softening device 2 that softens water using electrolysis, the hardness of the soft water can be reduced.

[0086] When the water softening device 2 of the present embodiment executes the first mode including the above-described steps S1-1 to S6-1, it switches the batch processing tanks 6A and 6B and the circulation channels 8A and 8B used in the first mode, and executes the second mode as the same water softening process. Specifically, after executing the first mode, the control unit 21 executes the second mode according to the flowchart shown in FIG. 11.

[0087] As shown in FIG. 11, in the second mode, the control unit 21 sequentially executes the second raw water injection mode (S1-2), the second crystallization treatment mode (S2-2), the second acidic water water supply mode (S3-2), the second alkaline water water supply mode (S4-2), the second pipe cleaning mode (S5-2), and the second electrolysis tank cleaning mode (S6-2).

[0088] The flow of water in each mode of steps S1-2 to S6-2 is shown in FIGS. 12 to 17. FIG. 12 shows the second raw water injection mode, FIG. 13 shows the second crystallization treatment mode, FIG. 14 shows the second acidic water water supply mode, FIG. 15 shows the second alkaline water water supply mode, FIG. 16 shows the second pipe cleaning mode, and FIG. 17 shows the second electrolysis tank cleaning mode.

[0089] In FIGS. 12 to 17, similar to FIGS. 3 to 8, the flow of water is represented by arrows, and it is assumed that no water flow occurs in the channels without arrows. Also, the open state of the valve is represented by hatching, and the closed state of the valve is represented by being painted black.

[0090] As shown in FIGS. 12 to 17, in the second mode, the only difference from the first mode is that the batch treatment tanks 6A and 6B and the circulation channels 8A and 8B are switched.

[0091] As shown in FIG. 12, in the second raw water injection mode (S1-2), raw water is injected into the batch treatment tank 6B. As shown in FIG. 13, in the second crystallization treatment mode (S2-2), the raw water stored in the batch treatment tank 6B is supplied to the electrolysis device 12 for electrolysis. The generated alkaline water is passed through the circulation channel 8B, and while circulating in the circulation channel 8B including the batch treatment tank 6B, the acidic water is passed through the circulation channel 8A and stored in the batch treatment tank 6A. As shown in FIG. 14, in the second acidic water supply mode (S3-2), the acidic water stored in the batch treatment tank 6A is supplied to the intermediate tank 18 via the separation device 16. As shown in FIG. 15, in the second alkaline water supply mode (S4-2), the alkaline water stored in the batch treatment tank 6B is supplied to the separation device 16 to separate crystals, and the alkaline water after crystal separation is supplied to the intermediate tank 18 and mixed with the acidic water. As shown in FIG. 16, in the second pipe cleaning mode (S5-2), the acidic water remaining in the batch treatment tank 6A is passed through the bypass channels 41, 41A, and 41B via the separation device 16 to clean each pipe. As shown in FIG. 17, in the second electrolysis tank cleaning mode (S6-2), the acidic water remaining in the batch treatment tank 6A is passed through the electrolysis device 12 to clean the electrolysis device 12 and each pipe.

[0092] Similar to the first mode, in the second crystallization treatment mode (S2-2) shown in FIG. 13, while electrolysis is performed by the electrolysis device 12, alkaline water is circulated through the circulation channel 8B. Thereby, while increasing the pH value of the water flowing through the circulation channel 8B, crystallization of the metal components contained in the water can be performed, and the hardness of the raw water can be reduced.

[0093] Furthermore, in the second crystallization treatment mode (S2-2), the control unit 21 determines whether to continue or stop the electrolysis of the electrolysis device 12 by executing the first determination (S7) and the second determination (S8) shown in FIG. 9. Specifically, while monitoring the pH value of the alkaline water based on the detection value of the pH sensor 14B provided in the circulation channel 8B, the first determination (S7) and the second determination (S8) are executed to determine whether to continue or stop the electrolysis of the electrolysis device 12. Thereby, electrolysis can be stopped at a point in time (about 8 minutes later) before the ion separation rate rapidly decreases as shown in the graph of FIG. 10, the hardness of the acidic water can be maintained at a low value, and finally the hardness of the produced soft water can be reduced.

[0094] The control unit 21 alternately executes the first mode (S1-1 to S6-1) shown in FIG. 2 and the second mode (S1-2 to S6-2) shown in FIG. 11 to continuously produce soft water.

[0095] The above-described softening device 2 includes a circulation channel 8A, 8B, an electrolysis device 12, a pH sensor 14A, a pH sensor 14B, and a control unit 21. The pH sensor 14A is a first sensor that detects the pH value as a parameter of the water flowing through the circulation channel 8A (first circulation channel). The pH sensor 14B is a second sensor that detects the pH value as a parameter of the water flowing through the circulation channel 8B (second circulation channel). In such a configuration, the control unit 21 controls the electrolysis device 12 to execute a first mode in which alkaline water is passed through the circulation channel 8A and acidic water is passed through the circulation channel 8B, and a second mode in which acidic water is passed through the circulation channel 8A and alkaline water is passed through the circulation channel 8B. The control unit 21 further controls to stop the electrolysis of the electrolysis device 12 based on the detection value of the pH sensor 14A in the first mode, and controls to stop the electrolysis of the electrolysis device 12 based on the detection value of the pH sensor 14B in the second mode.

[0096] According to such a configuration, by controlling the operation of the electrolysis device 12 based on the detection values of the pH sensors 14A and 14B, it becomes possible to stop the electrolysis when the "ion separation rate" starts to rapidly decrease, that is, when the hardness of the acidic water starts to increase. As a result, the hardness of the finally produced soft water can be reduced.

[0097] Also, in the first mode, the electrolysis of the electrolysis device 12 is controlled to stop based on the detection value of the pH sensor 14A, and in the second mode, the electrolysis of the electrolysis device 12 is stopped based on the detection value of the pH sensor 14B. That is, the determination of the continuation / stop of electrolysis in the first mode and the second mode is performed based on the parameters of the alkaline water.

[0098] By making the alkaline water the object of determination in this way, there are advantages such as being able to utilize the general-purpose and inexpensive configurations of the pH sensors 14A and 14B compared to the case where the acidic water is the object of determination (for example, when directly detecting the hardness of the acidic water with a hardness sensor and determining the continuation / stop of electrolysis, etc.).

[0099] Also, in the softening device 2 of the embodiment, the pH sensor 14A is provided on the downstream side of the electrolysis device 12 and on the upstream side of the batch treatment tank 6A in the circulation flow path 8A. Further, the pH sensor 14B is provided on the downstream side of the electrolysis device 12 and on the upstream side of the batch treatment tank 6B in the circulation flow path 8B.

[0100] According to such an arrangement, since the pH sensors 14A and 14B can detect both the pH values of the alkaline water and the acidic water, they can be used for feedback when determining the mixing ratio when mixing the alkaline water and the acidic water, the supply amount of CO2 by the CO2 supply line 42, etc.

[0101] In the water softening device 2 of the embodiment, the control unit 21 determines whether or not the variation value of the detected values (alkaline water) of the pH sensors 14A and 14B within a predetermined period is within a predetermined range (S7). When it is determined that the variation value is within the predetermined range (YES in S7), the control unit 21 then determines whether or not the increase value of the detected values of the pH sensors 14A and 14B within a predetermined period is equal to or greater than a predetermined value (S8). When it is determined that the increase value is equal to or greater than the predetermined value (YES in S8), the control unit 21 controls to stop the electrolysis of the electrolysis device 12 (S9).

[0102] According to such a configuration, it is possible to perform an operation of stopping electrolysis at the point in time when the "ion separation rate" begins to rapidly decrease, that is, when the hardness of the acidic water begins to increase, and it is possible to make the hardness of the finally produced soft water lower.

[0103] The water softening device 2 of the embodiment further includes a batch treatment tank 6A (first batch treatment tank) provided in the middle of the circulation flow path 8A, a batch treatment tank 6B (second batch treatment tank) provided in the middle of the circulation flow path 8B, and a valve 24. The valve 24 controls the flow of water / stopping of water from the batch treatment tank 6A to the downstream side and the flow of water / stopping of water from the batch treatment tank 6B to the downstream side. In such a configuration, in the first mode, the control unit 21 controls the valve 24 so that water flows from the batch treatment tank 6A to the downstream side and the batch treatment tank 6B is stopped, and in the second mode, the control unit 21 controls the valve 24 so that water flows from the batch treatment tank 6B to the downstream side and the batch treatment tank 6A is stopped.

[0104] According to such a configuration, it is possible to perform an operation of circulating the alkaline water in the respective circulation flow paths 8A and 8B while storing the acidic water generated by electrolysis in the batch treatment tanks 6A and 6B.

[0105] In the water softening device 2 of the embodiment, the circulation flow paths 8A and 8B merge at positions extending downstream from the batch treatment tanks 6A and 6B, respectively, and are connected to the electrolysis device 12.

[0106] According to such a configuration, the device configuration of the water softening device 2 can be simplified.

[0107] Note that the present invention is not limited to the above-described embodiment and can be implemented in various other modes. For example, in the embodiment, the case where the pH sensors 14A and 14B are used to determine the continuation / stop of electrolysis based on the pH values of the alkaline water flowing through the circulation channels 8A and 8B has been described. However, the present invention is not limited to such a case. A sensor different from the pH sensor may be used to detect a parameter different from the pH value, and the continuation / stop of electrolysis may be determined based on the detected value. Specific examples of other sensors include, for example, a conductivity sensor, a TDS sensor, a turbidity sensor, a chromaticity sensor, and a hardness sensor.

[0108] The conductivity sensor detects "conductivity" as a parameter of water, the TDS sensor detects "total dissolved solids amount", the turbidity sensor detects "turbidity", the chromaticity sensor detects "chromaticity", and the hardness sensor detects "hardness". The time transitions of the respective parameters during electrolysis when these sensors are used are shown in FIGS. 18A to 18C.

[0109] FIG. 18A is a schematic diagram showing the time transition of the detected values of the respective parameters when a conductivity sensor or a TDS sensor is used.

[0110] As shown in FIG. 18A, when a conductivity sensor or a TDS sensor is used, the detected values of the parameters show the same time transition as in the case where the pH sensors 14A and 14B are used (see FIG. 10). Specifically, the parameters increase after the start of electrolysis, then reach a steady state, and then increase again. Since the timing of this re-increase corresponds to the timing when the hardness of the acidic water starts to increase, the same first determination (S7) and second determination (S8) as in FIG. 9 may be performed to determine the continuation / stop of electrolysis. Thereby, the same operations and effects as in the embodiment can be achieved.

[0111] FIG. 18B is a schematic diagram showing the time transition of the detected values of the respective parameters when a turbidity sensor or a chromaticity sensor is used.

[0112] As shown in FIG. 18B, when a turbidity sensor or a chromaticity sensor is used, the detected value of the parameter shows a different behavior from the parameters when pH sensors 14A and 14B, a conductivity sensor, and a TDS sensor are used. Specifically, as electrolysis starts, the parameter increases, but the rate of increase gradually decreases and reaches a saturation state at a certain point, where the increase in the parameter substantially stops. Since the saturation point at which the increase in this parameter stops corresponds to the timing when the hardness of the acidic water starts to increase, it is sufficient to determine whether to continue / stop electrolysis by determining whether the saturation point has been reached. Specifically, based on the detected value of the turbidity sensor or the chromaticity sensor, control may be performed to stop the electrolysis by the electrolysis device 12 when the rate of increase (change rate) of the parameter per unit time becomes equal to or less than a predetermined value.

[0113] FIG. 18C is a schematic diagram showing the time transition of the detected value of the parameter when a hardness sensor is used.

[0114] As shown in FIG. 18C, when a hardness sensor is used, the detected value of the parameter shows a different behavior from FIGS. 18A and 18B. Specifically, as electrolysis starts, the parameter decreases, but the rate of decrease gradually decreases and reaches a saturation state at a certain point, where the decrease in the parameter substantially stops. Since the saturation point at which the decrease in this parameter stops corresponds to the timing when the hardness of the acidic water starts to increase, it is sufficient to determine whether to continue / stop electrolysis by determining whether the saturation point has been reached. Specifically, based on the detected value of the hardness sensor, control may be performed to stop the electrolysis by the electrolysis device 12 when the rate of decrease (change rate) of the parameter per unit time becomes equal to or less than a predetermined value.

[0115] When using each of the above sensors, depending on the characteristics of the sensors, etc., acidic water instead of alkaline water may be the object of determination. That is, based on the detected values of the parameters of acidic water, the continuation / stop of electrolysis may be determined. For example, when using a pH sensor, a conductivity sensor, or a hardness sensor, acidic water may be the object of determination instead of alkaline water. In particular, by detecting the hardness of acidic water as a parameter for determination using a hardness sensor, the change in the hardness of acidic water can be monitored more directly.

[0116] Note that not limited to the above-mentioned sensors, any sensor may be used as long as it can detect a parameter related to the timing when the ion separation rate starts to rapidly decrease, that is, the timing when the hardness of acidic water starts to increase. Such sensors may be collectively referred to as "crystallinity sensing sensors", "acidic water hardness sensing sensors", etc.

[0117] Also, in the above embodiment, the case where batch processing tanks 6A and 6B are respectively provided in the middle of the circulation channels 8A and 8B has been described, but it is not limited to such a case. The batch processing tanks 6A and 6B may not be provided. Even in such a case, by devising the shape and length of the circulation channels 8A and 8B or appropriately providing valves, an operation of circulating alkaline water can be executed in the same manner as the above-described first crystallization processing mode (S2-1) and second crystallization processing mode (S2-2).

[0118] Also, in the above embodiment, the case where the first alkaline water feeding mode is executed after the first acidic water feeding mode in the first mode shown in FIG. 2 and the second alkaline water feeding mode is executed after the second acidic water feeding mode in the second mode shown in FIG. 11 has been described, but it is not limited to such a case. The acidic water feeding mode may be executed after the alkaline water feeding mode.

[0119] Note that by appropriately combining the above various forms, the respective effects can be achieved.

[0120] The present invention is fully described in relation to preferred embodiments with reference to the accompanying drawings, but various modifications and alterations will be apparent to those skilled in the art. Such modifications and alterations are to be understood as being included therein as long as they do not depart from the scope of the present invention as defined by the appended claims. Also, changes in the combination and order of elements in the embodiments can be realized without departing from the scope and spirit of the present invention.

Industrial Applicability

[0121] The present invention is useful for both household water softening devices and industrial water softening devices.

Explanation of Reference Numerals

[0122] 2 Water softening device 4A Raw water flow path 4B Raw water flow path 6A Batch treatment tank (First batch treatment tank) 6B Batch treatment tank (Second batch treatment tank) 8A Circulation flow path (First circulation flow path) 8B Circulation flow path (Second circulation flow path) 10 Pump 12 Electrolysis device 14A pH sensor (First sensor, First pH sensor) 14B pH sensor (Second sensor, Second pH sensor) 16 Separation device 18 Intermediate tank 20 Water storage tank 21 Control unit 22A, 22B, 24, 26, 28A, 28B, 30, 32 Valves 34 Flow path 36 Flow path 38 Flow path (Drainage flow path) 40 Flow path 41, 41A, 41B Flow paths (Bypass flow paths) 42 CO2 supply line 44 Flow path

Claims

1. an electrolysis device for producing alkaline water and acidic water by electrolysis; a first circulation flow path and a second circulation flow path connected to the electrolyzer, the first circulation flow path and the second circulation flow path allowing the alkaline water and the acidic water produced by the electrolyzer to flow alternately; a first sensor for detecting a parameter of water flowing through the first circulation flow path; a second sensor for detecting a parameter of the water flowing through the second circulation flow path; A control unit, The first sensor and the second sensor are either a turbidity sensor or a chromaticity sensor, The control unit is controlling the electrolyzer to execute a first mode in which alkaline water is passed through the first circulation flow path and acidic water is passed through the second circulation flow path, and a second mode in which acidic water is passed through the first circulation flow path and alkaline water is passed through the second circulation flow path; In the first mode, it is determined whether or not a rate of increase per unit time of the detection value of the first sensor is equal to or less than a predetermined value; When it is determined that the rate of increase is equal to or less than the predetermined value, the electrolysis of the electrolysis device is stopped. In the second mode, it is determined whether or not a rate of increase per unit time of the detection value of the second sensor is equal to or less than a predetermined value; When it is determined that the rate of increase is equal to or less than the predetermined value, the water softening device controls the electrolysis device to stop electrolysis.

2. a first batch processing tank provided in the first circulation flow path; a second batch processing tank provided in the middle of the second circulation flow path; a valve for controlling water flow / stop from the first batch processing tank to the downstream side and water flow / stop from the second batch processing tank to the downstream side, The control unit is In the first mode, the valve is controlled so that water is passed from the first batch processing tank to a downstream side and water is stopped in the second batch processing tank; The water softening apparatus according to claim 1 , wherein in the second mode, the valve is controlled so that water is passed from the second batch processing tank downstream and water is stopped in the first batch processing tank.

3. 3. The water softening apparatus according to claim 2, wherein the first sensor is provided in the first circulation flow path downstream of the electrolysis device and upstream of the first batch processing tank, and the second sensor is provided in the second circulation flow path downstream of the electrolysis device and upstream of the second batch processing tank.

4. The water softening apparatus according to claim 2 or 3, wherein the first circulation flow path and the second circulation flow path join at a position extending downstream from the first batch treatment tank and the second batch treatment tank, respectively, and are connected to the electrolysis device.

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