Water 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 technology]

[0002] In hard water regions, problems caused by hardness components such as scale and limescale arise, creating a demand for water softeners. Water softeners use ion exchange resins (see, for example, Patent Document 1), but this method has the drawback of generating waste salt solution because it uses salt for regeneration. Other water softening methods use EDI or RO membranes (see, for example, Patent Document 2), but these methods have the drawback of disposing of large amounts of water. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3145240 [Patent Document 2] International Publication No. 2007 / 132685 Summary of the Invention [Problem to be solved by the invention]

[0004] A water softening device that uses electrolysis to soften water is considered. In a water softening device that uses electrolysis, it is desirable to reduce the hardness of the soft water that is finally produced.

[0005] SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above problems and to provide a water softening device that can further reduce the hardness of softened water. [Means for solving the problem]

[0006] In order to achieve the above object, the water softening device of the present invention comprises an electrolyzer that produces alkaline water and acidic water by electrolysis, a circulation flow path connected to the electrolyzer, which includes a first circulation flow path and a second circulation flow path through which the alkaline water and acidic water produced by the electrolyzer can alternately flow, a first sensor that detects parameters of water flowing through the first circulation flow path, a second sensor that detects parameters of water flowing through the second circulation flow path, and a control unit, wherein the control unit controls 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, and controls the electrolyzer to stop electrolysis based on the detection value of the first sensor or the second sensor in the first mode and the second mode. [Effects of the Invention]

[0007] According to the water softening device of the present invention, the hardness of softened water can be further reduced. [Brief explanation of the drawings]

[0008] [Figure 1] Schematic diagram of a water softening device according to an embodiment. [Figure 2] 1. A flowchart showing the first mode of the water softening device shown in FIG. [Figure 3] A diagram showing the water flow in the first raw water injection mode in the first mode. [Figure 4] FIG. 10 is a diagram showing the water flow in the first crystallization treatment mode in the first mode. [Figure 5] FIG. 10 is a diagram showing the water flow in the first acidic water supply mode in the first mode. [Figure 6] FIG. 10 is a diagram showing the water flow in the first alkaline water supply mode in the first mode. [Figure 7] A diagram showing the water flow in the first pipe cleaning mode in the first mode [Figure 8] FIG. 10 shows the water flow in the first electrolytic bath cleaning mode in the first mode. [Figure 9]A flowchart showing a method for determining whether to continue or stop electrolysis in the first crystallization treatment mode. [Figure 10] Graph showing the time course of "alkaline pH" and "ion separation rate" in the first crystallization treatment mode [Figure 11] 1. A flowchart showing the second mode of the water softening device shown in FIG. [Figure 12] A diagram showing the water flow in the second raw water injection mode in the second mode [Figure 13] FIG. 2 shows the water flow in the second crystallization treatment mode in the second mode. [Figure 14] FIG. 2 shows the water flow in the second acidic water supply mode in the second mode. [Figure 15] FIG. 2 shows the water flow in the second alkaline water supply mode in the second mode. [Figure 16] A diagram showing the water flow in the second pipe cleaning mode in the second mode [Figure 17] FIG. 2 shows the water flow in the second electrolytic bath cleaning mode in the second mode. [Figure 18A] Schematic diagram showing the time evolution of parameters when using a conductivity sensor or TDS sensor [Figure 18B] Schematic diagram showing the time transition of parameters when using a turbidity sensor or a color sensor [Figure 18C] Schematic diagram showing the time transition of parameters when using a hardness sensor DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. However, the present invention is not limited to these embodiments.

[0010] (Embodiment) FIG. 1 is a schematic diagram of a water softening device 2 according to an embodiment.

[0011] The water softener 2 is a device that uses electrolysis to remove metal ions, which act as hardness components, from water. The metal ions referred to here are calcium ions (Ca 2+ ) and magnesium ions (Mg 2+ ) The water softening device 2 in this embodiment is a water softening device that removes and separates metal ions from hard water, thereby reducing the concentration (hardness) of metal ions in hard water to a predetermined concentration or less, thereby producing soft water. For the definitions of hard water and soft water, for example, the WHO definitions may be used. That is, soft water may be defined as water with a hardness of less than 120 mg / L, and hard water may be defined as water with a hardness of 120 mg / L or more.

[0012] 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 electrolyzer 12, pH sensors 14A and 14B, a separator 16, an intermediate tank 18, a water storage tank 20, and a control unit 21. The water softening device 2 further includes various valves, such as valves 22A and 22B, a valve 24, a valve 26, valves 28A and 28B, a valve 30, and a valve 32.

[0013] The raw water flow paths 4A and 4B are flow paths for supplying raw water to the batch processing 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 processing tanks 6A and 6B. Valves 22A and 22B are provided in the raw water flow paths 4A and 4B, respectively. Opening and closing the valves 22A and 22B controls whether water is allowed to flow from the raw water flow paths 4A and 4B to the batch processing tanks 6A and 6B, respectively.

[0014] The batch processing tanks 6A and 6B are tanks for storing water for batch processing. Each of the batch processing tanks 6A and 6B is provided with a float sensor (not shown) that can detect the amount of water stored in each tank. Circulation flow paths 8A and 8B are connected to the batch processing 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 extend downstream from the batch processing tanks 6A and 6B, respectively, and merge to form a single channel at a point connected to a valve 24. The combined circulation channels 8A and 8B are then connected to an electrical separation device 12 via a pump 10 and a valve 26.

[0016] The flow / stop of water from the batch treatment tanks 6A, 6B to the electrolyzer 12 is controlled by opening and closing valves 24 and 26. Water is passed downstream from the batch treatment tanks 6A, 6B by driving pump 10 provided between valves 24 and 26.

[0017] The electrolyzer 12 is a device that produces alkaline water and acidic water by electrolyzing water supplied through the circulation flow paths 8A and 8B. The electrolyzer 12 includes a positive electrode (anode) and a negative electrode (cathode) with a diaphragm disposed between the electrodes, and produces alkaline water and acidic water by applying a voltage between the positive and negative electrodes to electrolyze water.

[0018] The electrolyzer 12 is connected downstream thereof with circulation flow paths 8A and 8B as two flow paths.

[0019] The circulation flow paths 8A and 8B connected downstream from the electrolyzer 12 are capable of alternately passing alkaline water and acidic water produced by the electrolyzer 12. When alkaline water passes through the circulation flow path 8A, acidic water passes through the circulation flow path 8B, and when acidic water passes through the circulation flow path 8A, alkaline water passes through the circulation flow path 8B.

[0020] Circulation flow path 8A, which is connected downstream from electrolyzer 12, is provided with valve 28A and pH sensor 14A along the way and is also connected to batch processing tank 6A. Similarly, circulation flow path 8B, which is connected downstream from electrolyzer 12, is provided with valve 28B and pH sensor 14B along the way and is also connected to batch processing tank 6B. Opening and closing valves 28A and 28B control whether water is allowed to flow from electrolyzer 12 to batch processing tanks 6A and 6B, respectively.

[0021] The circulation flow paths 8A, 8B having the above-described configuration constitute circulation flow paths that run from the batch treatment tanks 6A, 6B via the electrolyzer 12 and return to the batch treatment tanks 6A, 6B, respectively. In this embodiment, the circulation flow paths 8A, 8B merge to form a single flow path at a point from the valve 24 to the electrolyzer 12. Compared to when the circulation flow paths 8A, 8B are independent flow paths that do not merge, the configuration of the water softening device 2 can be simplified, for example, by requiring only one pump 10.

[0022] The pH sensors 14A and 14B are sensors for detecting the pH value as a parameter of the water flowing through the circulation flow paths 8A and 8B, respectively. As will be described later, the pH values ​​detected by the pH sensors 14A and 14B are used as parameters for determining whether to continue or stop electrolysis by the electrolyzer 12. Details will be described later.

[0023] A valve 26 is provided at the point where the circulation channels 8A and 8B join together to form a single channel, and is connected to a channel 34 in addition to the circulation channels 8A and 8B. The channel 34 is connected to a separation device 16.

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

[0025] Two flow paths, a flow path 36 and a flow path 38, are connected to the separation device 16. The flow path 36 is a flow path for passing water from which crystals have been separated by the separation device 16. The flow path 38 is a wastewater flow path for passing wastewater containing crystals separated by the separation device 16, and extends outside the water softening device 2 system.

[0026] A flow path 36 for passing the water from which the crystals have been separated 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 passed through the flow path 40. By opening and closing the valve 30, the flow / stop of water from the separation device 16 to the intermediate tank 18 via the flow paths 36, 40 is controlled.

[0028] Flow path 41 is a bypass flow path that connects batch processing tanks 6A, 6B with intermediate tank 18 without passing through electrolyzer 12 and separator 16. Two flow paths 41A, 41B are connected to flow path 41, and flow paths 41A, 41B are connected to the above-mentioned valves 28A, 28B, respectively.

[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 midway along the CO2 supply line 42, and the supply / stop of CO2 gas is controlled by opening and closing the valve 32.

[0030] A flow path 44 is further 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 after the softening treatment. The treated water stored in the water storage tank 20, i.e., the soft water, can be supplied to a faucet or the like and used by end users.

[0032] A pressure sensor (not shown) is provided in the water storage tank 20. The amount of water stored in the water storage tank 20 can be detected by detecting a drop in pressure due to consumption of treated water with the pressure sensor.

[0033] The control unit 21 is a member that controls each of the components of the above-mentioned water softening device 2. The control unit 21 is electrically connected to each of the components of the water softening device 2, and performs control of opening and closing each valve, ON / OFF control of the pump 10, ON / OFF control of the electrolyzer 12, ON / OFF control of the separation device 16, etc. The control unit 21 is configured, for example, by a microcomputer that includes a processor and a memory that stores a computer program executed by the processor.

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

[0035] First, the first mode will be described with reference to Fig. 2 and Fig. 3 to Fig. 8. Fig. 2 is a flowchart for executing the first mode using the water softening device 2. Fig. 3 to Fig. 8 are schematic diagrams showing the flow of water when the first mode is executed according to 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 the operation of the water softening device 2 is started. Specifically, the control unit 21 controls the flow to occur as shown in FIG. 3. In FIG. 3 and subsequent figures, the water flow is represented by arrows, and no water flow occurs in flow paths without arrows. In addition, the open state of the valve is represented by hatching, and the closed state of the valve is represented by filling in black.

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

[0038] When a predetermined amount (for example, 10 L) of raw water is passed 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 processing mode) 4 shows the first crystallization treatment mode. The control unit 21 controls the supply of raw water stored in the batch treatment tank 6A to the electrolyzer 12. Specifically, while driving the pump 10, the control unit 21 opens the valve 24 to pass water from the batch treatment tank 6A to the circulation flow path 8A, and opens the valve 26 to pass water to the electrolyzer 12. At this time, the control unit 21 controls the opening and closing of the valve 24 so as to stop water from passing downstream from the batch treatment tank 6B.

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

[0041] In the first crystallization treatment mode, the electrolyzer 12 is controlled so that, of the alkaline water and acidic water produced by the electrolyzer 12, the alkaline water is passed through the circulation flow path 8A and the acidic water is passed 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 passed through the circulation flow path 8A is returned to the batch treatment tank 6A, and controls the opening and closing of the valve 28B so that the acidic water passed through the circulation flow path 8B is returned to the batch treatment tank 6B, thereby generating the flows indicated by the arrows in FIG.

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

[0044] In the circulation flow path 8A including the batch treatment tank 6A, the mixed water of raw water and alkaline water is circulated while electrolysis is continuously carried out by the electrolyzer 12, and the pH value also continuously increases.

[0045] Here, the Ca contained in the raw water 2+ and Mg 2+ Metal ions such as OH migrate electrophoretically from the anode (acidic water) to the cathode (alkaline water) through a membrane, reducing the hardness of acidic water. - Even in alkaline water containing a large amount of HCl, the reactions of the following formulas 1 to 3 occur, reducing the hardness of the water.

[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 shown in Equation 1, the OH contained in alkaline water - is HCO3 in water - (bicarbonate ion) to produce water and CO3 2- (carbonate ion). The CO3 produced in the reaction of Equation 1 2- is expressed as Ca as in Eq. 2+ It reacts with Mg to produce insoluble CaCO3 (calcium carbonate).2+ is the OH contained in alkaline water - This reaction produces insoluble Mg(OH)2 (magnesium hydroxide). As CaCO3 and Mg(OH)2 crystallize and precipitate, the concentration of metal ions in the alkaline water decreases, and the hardness of the alkaline water also decreases. As a result, the hardness of both acidic and alkaline water decreases.

[0048] By continuously supplying alkaline water to the circulation flow path 8A and circulating it, the reactions of the above formulas 1 to 3 are continuously caused to occur, causing the metal ions in the alkaline water to crystallize and precipitate, thereby reducing the hardness of the raw water.

[0049] The control unit 21 ends the first crystallization treatment mode at a predetermined timing and then executes the next first acidic water supply mode (step S3-1). The timing to end 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) 5 shows the first acidic water supply mode. The control unit 21 controls the supply of acidic water stored in the batch processing tank 6B to the intermediate tank 18 via the separator 16. Specifically, while driving the pump 10, the valve 24 is opened to allow water to flow from the batch processing tank 6B to the circulation flow path 8B, and the valve 26 is opened to allow water to flow from the circulation flow path 8B to the flow path 34.

[0051] The control unit 21 does not operate the separation device 16, but instead passes the acidic water that reaches the separation device 16 directly through the flow path 36. The control unit 21 then opens the valve 30 so that the acidic water that has been passed through the flow path 36 passes through the flow path 40. This causes the acidic water to pass through the flow path 40 into the intermediate tank 18.

[0052] According to the above operation, the amount of acidic water stored in the intermediate tank 18 increases, while the amount of acidic water stored in the batch processing tank 6B decreases. In this embodiment, the control unit 21 continues the first acidic water delivery mode until the amount of acidic water stored in the batch processing tank 6B decreases to a predetermined amount (e.g., 2 L). When the amount of water stored in the batch processing tank 6B decreases to the predetermined amount, the control unit 21 stops the first acidic water delivery mode and executes the next first alkaline water delivery mode (S4-1).

[0053] (First alkaline water supply mode) 6 shows the first alkaline water supply mode. The control unit 21 controls the supply of alkaline water stored in the batch processing tank 6A to the intermediate tank 18 via the separator 16. While the operation of the separator 16 was stopped in the first acidic water supply mode, in the first alkaline water supply mode, the separator 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 to allow water to flow from the batch processing tank 6A to the circulation flow path 8A, and the valve 26 is opened to allow water to flow from the circulation flow path 8A to the flow path .

[0055] The control unit 21 separates the crystals contained in the alkaline water by centrifugal separation by operating the separator 16. The separator 16 passes the alkaline water from which the crystals have been separated through a flow path 36, and passes the wastewater containing the crystals through a flow path 38 to discharge the wastewater.

[0056] The alkaline water after crystal separation that has passed through flow path 36 is passed through flow path 40 to intermediate tank 18. Because acidic water is already stored in intermediate tank 18, the alkaline water and acidic water are mixed in intermediate tank 18. The mixed water of alkaline water and acidic water is neutralized, and the pH value becomes close to neutral. As mentioned above, both alkaline water and acidic water have low hardness, so the hardness of the mixed water also becomes low. As a result, the mixed water stored in intermediate tank 18 is soft water with a pH value close to neutral and low hardness.

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

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

[0059] The crystalline CaCO3 reacts with CO2 and H2O to produce soluble Ca(HCO3)2. This reaction allows the crystals to dissolve in water, reducing the turbidity of the treated water. 2+ The reaction equation is omitted for the following.

[0060] According to the above operation, the amount of mixed water stored in the intermediate tank 18 increases, while the amount of alkaline water stored in the batch processing tank 6A decreases. In this embodiment, the control unit 21 continues the first alkaline water delivery mode until the amount of water stored in the batch processing tank 6A is depleted. When the amount of water stored in the batch processing tank 6A is depleted, the control unit 21 stops the first alkaline water delivery mode and executes the next first pipe cleaning mode (S5-1).

[0061] (1st pipe cleaning mode) 7 shows the first pipe cleaning mode. The control unit 21 controls the acidic water remaining in the batch processing tank 6B to be returned to the batch processing tanks 6A and 6B via the separation device 16 and the bypass flow paths 41, 41A, and 41B.

[0062] Specifically, while driving the pump 10, the valve 24 is opened to allow water to flow from the batch processing tank 6B to the circulation flow path 8B, and the valve 26 is opened to allow water to flow from the circulation flow path 8B to the flow path 34. The control unit 21 does not operate the separation device 16, but instead allows the acidic water that reaches the separation device 16 to pass directly through the flow path 36.

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

[0064] This creates a flow of acidic water as shown in Figure 7. As the acidic water flows through each pipe, it dissolves the scale (CaCO3) that has adhered to the inner wall surface of each pipe, cleaning each pipe.

[0065] According to the above operation, the amount of acidic water stored in the batch treatment tank 6A increases, while the amount of acidic water stored in the batch treatment tank 6B decreases. When a predetermined amount (e.g., 1 L) of acidic water has passed through the batch treatment tank 6B, the control unit 21 ends the first pipe cleaning mode and executes the next first electrolytic bath cleaning mode (S6-1).

[0066] (First electrolytic bath cleaning mode) 8 shows the first electrolytic bath cleaning mode. The control unit 21 controls the acidic water remaining in the batch treatment tank 6B to be returned to the batch treatment tanks 6A and 6B via the electrolyzer 12.

[0067] Specifically, while driving pump 10, valve 24 is opened to allow water to flow from batch processing tank 6B to circulation flow path 8B, and valve 26 is opened to allow water to flow from circulation flow path 8B to electrolyzer 12. Control unit 21 does not operate electrolyzer 12, and allows acidic water that reaches electrolyzer 12 to pass through circulation flow paths 8A and 8B without being electrolyzed. Control unit 21 also controls the opening and closing of valves 28A and 28B to allow acidic water coming out of electrolyzer 12 to flow through circulation flow paths 8A and 8B to batch processing tanks 6A and 6B.

[0068] This produces a flow of acidic water as shown in Fig. 8. As the acidic water flows through the electrolyzer 12 and each pipe, the scale adhering to the inner wall surfaces of the electrolyzer 12 and each pipe is dissolved in the acidic water, thereby cleaning the electrolyzer 12 and each pipe.

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

[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 whether to continue or stop the electrolysis in the electrolyzer 12 in the first crystallization treatment mode (S2-1) will be described with reference to Figures 4 and 9. Figure 9 is a flowchart showing an example of a method for determining whether to continue or stop the electrolysis in the electrolyzer 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 detected value periodically transmitted from the pH sensor 14A. The control unit 21 determines whether the fluctuation value of the pH value of the alkaline water over a predetermined period of time is within a predetermined range, as shown in Fig. 9 (S7: first determination). The predetermined period is, for example, one minute, and the predetermined range is, for example, -0.02 to 0.02.

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

[0074] If the second determination determines that the increase in the concentration over the predetermined period is not equal to or greater than the predetermined value (NO in S8), the control unit 21 executes step S8 again. If the second determination determines that the increase in the concentration over the predetermined period is equal to or greater than the predetermined value (YES in S8), the control unit 21 stops the electrolysis by the electrolyzer 12 (S9). By stopping the electrolysis, the first crystallization treatment mode (S2-1) is terminated and the system transitions to the first acidic water delivery mode (S3-1).

[0075] An example of experimental data related to the method of determining whether to continue or stop electrolysis described in Figure 9 is shown in Figure 10. Figure 10 is a graph showing the time progression of "alkaline pH" and "ion separation rate" when the first crystallization treatment mode is carried out under specified conditions. The horizontal axis represents time, and the vertical axis represents "alkaline pH" and "ion separation rate."

[0076] "Alkaline pH" is the detection value of pH sensor 14A and indicates the pH value of alkaline water (unitless). "Ion separation rate" is the ratio (unit: %) of the hardness of the acidic water after electrolysis divided by the hardness of the raw water before electrolysis. The ion separation rate is an index that indicates the degree to which the hardness of the raw water has been reduced by electrolysis. The higher the ion separation rate, the more the hardness of the acidic water has been reduced. The ion separation rate is calculated by detecting the hardness of the raw water and acidic water using a hardness sensor (not shown).

[0077] As shown in Figure 10, when electrolysis is started by the electrolyzer 12, the "alkaline pH" value increases as alkaline water is produced. On the other hand, the "ion separation rate" also increases because metal ions are attracted to the alkaline water by electrophoresis, reducing the hardness of the acidic water.

[0078] After that, the increase in alkaline pH and the increase in ion separation rate stop, and a steady state is reached (approximately 2 minutes after the start). In the steady state, the reactions of Equations 1 to 3 described above are progressing, and the crystallization of the metal components is progressing.

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

[0080] The alkaline pH rises again as the reactions of Equations 1 to 3 proceed, and the substances required for the reactions of Equations 1 to 3 (HCO3 - etc.) in water, the reactions of Equations 1 to 3 slow down, and OH - The reason for the decrease in ion separation rate is that the crystallization proceeds due to the reactions of Equations 1 to 3, and the crystal mass becomes larger. As shown in Equation 5 below, the CaCO3 crystals react with the acid (H + ) and dissolved in Ca 2+ This is because the reaction of Mg(OH)2 is omitted.

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

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

[0083] The first determination (S7) determines whether the alkaline pH fluctuation value over a predetermined period is within a predetermined range, thereby making it possible to determine whether the steady state shown in the graph of FIG. 10 (the period from about 2 minutes to about 8 minutes later) is reached.

[0084] Furthermore, after the first determination (S7) determines that the steady state is reached, the second determination (S8) determines whether the increase in alkaline pH over a predetermined period of time is equal to or greater than a predetermined value, thereby making it possible to determine whether a re-increase in alkaline pH (after about 8 minutes) has occurred, as shown in the graph of FIG.

[0085] When the second determination (S8) detects a re-increase in alkaline pH, the electrolysis of the electrolyzer 12 is stopped (S9), which stops the electrolysis before the ion separation rate begins to drop sharply (after about 8 minutes). This allows the hardness of the acidic water produced by electrolysis to be maintained at a low value, and the hardness of the soft water ultimately produced by mixing acidic water and alkaline water can also be reduced. In this way, the hardness of the soft water can be reduced in the water softener 2, which uses electrolysis to soften water.

[0086] After executing the first mode including steps S1-1 to S6-1 described above, the water softening device 2 of this embodiment switches the batch processing tanks 6A, 6B and circulation flow paths 8A, 8B used in the first mode and executes a second mode as a similar water softening process. Specifically, after executing the first mode, the control unit 21 executes the second mode in accordance with the flowchart shown in FIG.

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

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

[0089] 12 to 17, as in Figures 3 to 8, the flow of water is represented by arrows, and no water flow occurs in flow paths without arrows. Also, the open state of the valve is represented by hatching, and the closed state of the valve is represented by filling in black.

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

[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), raw water stored in the batch treatment tank 6B is supplied to the electrolyzer 12 for electrolysis. The resulting alkaline water is passed through the circulation flow path 8B and circulated through the circulation flow path 8B, which includes the batch treatment tank 6B, while the acidic water is passed through the circulation flow path 8A and stored in the batch treatment tank 6A. As shown in FIG. 14, in the second acidic water delivery mode (S3-2), the acidic water stored in the batch treatment tank 6A is supplied to the intermediate tank 18 via the separator 16. As shown in FIG. 15, in the second alkaline water delivery mode (S4-2), the alkaline water stored in the batch treatment tank 6B is supplied to the separator 16 to separate the crystals, and the alkaline water after the 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 caused to flow into the bypass flow paths 41, 41A, and 41B via the separator 16, thereby cleaning the pipes. 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 caused to flow into the electrolyzer 12, thereby cleaning the electrolyzer 12 and the pipes.

[0092] 13, alkaline water is circulated through the circulation flow path 8B while electrolysis is being performed by the electrolyzer 12. This increases the pH value of the water flowing through the circulation flow path 8B, crystallizes metal components contained in the water, and reduces the hardness of the raw water.

[0093] Furthermore, in the second crystallization treatment mode (S2-2), the control unit 21 determines whether to continue or stop the electrolysis in the electrolyzer 12 by executing the first determination (S7) and the second determination (S8) shown in FIG. 9. Specifically, the control unit 21 determines whether to continue or stop the electrolysis in the electrolyzer 12 by executing the first determination (S7) and the second determination (S8) while monitoring the pH value of the alkaline water based on the detection value of the pH sensor 14B provided in the circulation flow path 8B. This makes it possible to stop the electrolysis before the ion separation rate drops sharply (after about 8 minutes) as shown in the graph of FIG. 10, thereby maintaining the hardness of the acidic water at a low value and ultimately reducing the hardness of the soft water produced.

[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 softened water.

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

[0096] With this configuration, by controlling the operation of the electrolyzer 12 based on the values ​​detected by the pH sensors 14A and 14B, it is possible to stop electrolysis when the "ion separation rate" begins to drop sharply, i.e., when the hardness of the acidic water begins to increase, thereby reducing the hardness of the soft water that is ultimately produced.

[0097] In the first mode, electrolysis in the electrolyzer 12 is stopped based on the detection value of the pH sensor 14A, and in the second mode, electrolysis in the electrolyzer 12 is stopped based on the detection value of the pH sensor 14B. That is, the determination of whether to continue or stop electrolysis in the first and second modes is made based on the parameters of the alkaline water.

[0098] By using alkaline water as the target of judgment in this way, there is an advantage that it is possible to use the general-purpose and inexpensive configuration of pH sensors 14A and 14B compared to when acidic water is the target of judgment (for example, when the hardness of acidic water is directly detected with a hardness sensor to determine whether to continue or stop electrolysis).

[0099] In the water softening device 2 of this embodiment, the pH sensor 14A is provided in the circulation flow path 8A downstream of the electrolyzer 12 and upstream of the batch treatment tank 6A. The pH sensor 14B is provided in the circulation flow path 8B downstream of the electrolyzer 12 and upstream of the batch treatment tank 6B.

[0100] With this arrangement, the pH sensors 14A and 14B can detect the pH values ​​of both alkaline water and acidic water, which can be used as feedback when determining the mixing ratio when mixing alkaline water and acidic water, the amount of CO2 to be supplied through the CO2 supply line 42, etc.

[0101] In the water softener 2 of this embodiment, the control unit 21 determines whether the fluctuation value of the detection value (alkaline water) of the pH sensors 14A, 14B over a predetermined period of time is within a predetermined range (S7). If it is determined that the fluctuation value is within the predetermined range (YES in S7), the control unit 21 then determines whether the increase value of the detection value of the pH sensors 14A, 14B over the predetermined period of time is equal to or greater than a predetermined value (S8). If it is determined that the increase value is equal to or greater than the predetermined value (YES in S8), the control unit 21 controls the electrolyzer 12 to stop electrolysis (S9).

[0102] This configuration makes it possible to stop electrolysis when the "ion separation rate" begins to drop sharply, i.e., when the hardness of the acidic water begins to increase, thereby making it possible to produce soft water with a lower hardness.

[0103] The water softening apparatus 2 of this embodiment further includes a batch processing tank 6A (first batch processing tank) provided midway through the circulation flow path 8A, a batch processing tank 6B (second batch processing tank) provided midway through the circulation flow path 8B, and a valve 24. The valve 24 controls whether water is allowed to flow downstream from the batch processing tank 6A, and whether water is allowed to flow downstream from the batch processing tank 6B. In this configuration, the control unit 21 controls the valve 24 in a first mode to allow water to flow downstream from the batch processing tank 6A and to stop water from flowing in the batch processing tank 6B, and in a second mode to allow water to flow downstream from the batch processing tank 6B and to stop water from flowing in the batch processing tank 6A.

[0104] With this configuration, it becomes possible to store acidic water produced by electrolysis in the batch treatment tanks 6A and 6B, while circulating alkaline water through the circulation flow paths 8A and 8B.

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

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

[0107] The present invention is not limited to the above-described embodiment and can be embodied in various other aspects. For example, in the embodiment, the pH sensors 14A and 14B are used to determine whether to continue or stop electrolysis based on the pH value of the alkaline water flowing through the circulation flow paths 8A and 8B. However, the present invention is not limited to this. A sensor other than the pH sensor may be used to detect a parameter other than the pH value, and the determination of whether to continue or stop electrolysis may be made based on the detected value. Specific examples of other sensors include a conductivity sensor, a TDS sensor, a turbidity sensor, a chromaticity sensor, and a hardness sensor.

[0108] The conductivity sensor detects the water parameter "conductivity," the TDS sensor detects "total dissolved solids," the turbidity sensor detects "turbidity," the colorimeter sensor detects "color," and the hardness sensor detects "hardness." Figures 18A to 18C show the time progression of each parameter during electrolysis when these sensors are used.

[0109] FIG. 18A is a schematic diagram showing the time transition of the detected values ​​of each parameter 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 parameter values ​​show the same time transition as when pH sensors 14A and 14B are used (see FIG. 10). Specifically, the parameter increases with the start of electrolysis, then reaches a steady state, and then increases again. The timing of this increase corresponds to the timing when the hardness of the acidic water begins to increase, so it is sufficient to perform the first determination (S7) and the second determination (S8) similar to those in FIG. 9 to determine whether to continue or stop electrolysis. This allows for the same functions and effects as those of the embodiment to be achieved.

[0111] FIG. 18B is a schematic diagram showing the time transition of the detected values ​​of each parameter 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 parameter values ​​behave differently from those when pH sensors 14A and 14B, a conductivity sensor, or a TDS sensor is used. Specifically, the parameter increases as electrolysis begins, but the rate of increase gradually decreases, and at a certain point, it reaches saturation and the increase in the parameter essentially stops. The saturation point at which the increase in the parameter stops corresponds to the timing when the hardness of the acidic water begins to increase. Therefore, whether to continue or stop electrolysis can be determined by determining whether the saturation point has been reached. Specifically, based on the detected value of the turbidity sensor or the chromaticity sensor, electrolysis by the electrolyzer 12 may be controlled to stop when the rate of increase (rate of change) of the parameter per unit time falls below a predetermined value.

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

[0114] As shown in FIG. 18C, when a hardness sensor is used, the detected parameter values ​​behave differently from those in FIGS. 18A and 18B. Specifically, the parameter decreases as electrolysis begins, but the rate of decrease gradually decreases, and at a certain point, it reaches saturation and the decrease in the parameter essentially stops. The saturation point at which the decrease in the parameter stops corresponds to the timing at which the hardness of the acidic water begins to increase. Therefore, whether to continue or stop electrolysis can be determined by determining whether the saturation point has been reached. Specifically, based on the detected value from the hardness sensor, electrolysis by the electrolyzer 12 may be controlled to stop when the rate of decrease (rate of change) of the parameter per unit time falls below a predetermined value.

[0115] When using the above-mentioned sensors, acidic water may be used as the determination target instead of alkaline water, depending on the characteristics of the sensor. That is, the continuation / stop of electrolysis may be determined based on the detected value of the parameter of the acidic water. For example, when a pH sensor, a conductivity sensor, or a hardness sensor is used, acidic water may be used as the determination target instead of alkaline water. In particular, by using a hardness sensor to detect the hardness of the acidic water as a determination parameter, changes in the hardness of the acidic water can be monitored more directly.

[0116] Any sensor may be used, not limited to the above-mentioned sensor, as long as it can detect a parameter related to the timing when the ion separation rate begins to rapidly decrease, i.e., the timing when the hardness of the acidic water begins to increase. Such sensors may be collectively referred to as "crystallinity sensor" or "acidic water hardness sensor."

[0117] In the above embodiment, the batch processing tanks 6A and 6B are provided midway along the circulation flow paths 8A and 8B, respectively. However, this is not a limitation. The batch processing tanks 6A and 6B may not be provided. Even in this case, by adjusting the shape and length of the circulation flow paths 8A and 8B or by providing valves appropriately, alkaline water can be circulated in the same manner as in the first crystallization treatment mode (S2-1) and the second crystallization treatment mode (S2-2) described above.

[0118] In the above embodiment, the first alkaline water delivery mode is executed after the first acidic water delivery mode in the first mode shown in Fig. 2, and the second alkaline water delivery mode is executed after the second acidic water delivery mode in the second mode shown in Fig. 11. However, this is not a limitation. The acidic water delivery mode may be executed after the alkaline water delivery mode.

[0119] The various modes described above can be combined as appropriate to achieve the effects of each mode.

[0120] Although the present invention has been fully described in connection with the preferred embodiment with reference to the accompanying drawings, various changes and modifications will be apparent to those skilled in the art. Such changes and modifications are to be understood as being included within the scope of the present invention as defined by the appended claims, unless they depart therefrom. Furthermore, changes in the combination and order of elements in the embodiments may be made without departing from the scope and spirit of the present invention. [Industrial Applicability]

[0121] The present invention is useful in both domestic and commercial water softening systems. [Explanation of symbols]

[0122] 2 Water softener 4A Raw water flow path 4B Raw water flow path 6A Batch processing tank (first batch processing tank) 6B Batch processing tank (second batch processing tank) 8A Circulation flow path (first circulation flow path) 8B Circulation flow path (second circulation flow path) 10 Pump 12 Electrolyzer 14A pH sensor (first sensor, first pH sensor) 14B pH sensor (second sensor, second pH sensor) 16 Separation device 18 Intermediate Tank 20 Water 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 path (bypass flow path) 42 CO2 supply line 44 Flow path

Claims

1. an electrolysis device that generates alkaline water and acidic water by electrolysis; a first circulation flow path and a second circulation flow path connected to the electrolyzer, through which alkaline water and acidic water produced by the electrolyzer can alternately flow; 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; a first batch processing tank provided midway along the first circulation flow path; a second batch processing tank provided midway along 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 first sensor and the second sensor are any one of a pH sensor, a conductivity sensor, and a TDS sensor; The control unit 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; 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 a first pipe cleaning mode in which pipes constituting the first circulation flow path and the second circulation flow path are cleaned; In the first mode, it is determined whether a fluctuation value of the detection value of the first sensor over a predetermined period of time is within a predetermined range; If it is determined that the fluctuation value is within a predetermined range, it is then determined whether or not the increase in the detected value of the first sensor over a predetermined period of time is equal to or greater than a predetermined value; When it is determined that the increase is equal to or greater than the predetermined value, the electrolysis of the electrolyzer is stopped. In the second mode, it is determined whether a fluctuation value of the detection value of the second sensor over a predetermined period of time is within a predetermined range; If it is determined that the fluctuation value is within a predetermined range, it is then determined whether or not the increase in the detected value of the second sensor over a predetermined period of time is equal to or greater than a predetermined value; When it is determined that the increase is equal to or greater than the predetermined value, the electrolysis of the electrolyzer is stopped. In the first pipe cleaning mode, the water softening device controls the valve to return the acidic water remaining in the second batch treatment tank to the first batch treatment tank and the second batch treatment tank.

2. an electrolysis device that generates alkaline water and acidic water by electrolysis; a first circulation flow path and a second circulation flow path connected to the electrolyzer, through which alkaline water and acidic water produced by the electrolyzer can alternately flow; 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; a first batch processing tank provided midway along the first circulation flow path; a second batch processing tank provided midway along 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; Equipped with the first sensor and the second sensor are hardness sensors; The control unit 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; 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 a first pipe cleaning mode in which pipes constituting the first circulation flow path and the second circulation flow path are cleaned; In the first mode, it is determined whether or not a rate of decrease per unit time of the detected value of the first sensor is equal to or less than a predetermined value; When it is determined that the rate of decrease is equal to or less than the predetermined value, the electrolysis of the electrolyzer is stopped. In the second mode, it is determined whether or not a rate of decrease per unit time of the detected value of the second sensor is equal to or less than a predetermined value; When it is determined that the rate of decrease is equal to or less than the predetermined value, the electrolysis of the electrolyzer is stopped. In the first pipe cleaning mode, the water softening device controls the valve to return the acidic water remaining in the second batch treatment tank to the first batch treatment tank and the second batch treatment tank.

3. 3. The water softening apparatus according to claim 1, wherein the first sensor is provided in the first circulation flow path downstream of the electrolyzer and upstream of the first batch treatment tank, and the second sensor is provided in the second circulation flow path downstream of the electrolyzer and upstream of the second batch treatment tank.

4. 3. The water softening apparatus according to claim 1, 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.

5. 3. The water softening apparatus according to claim 1, further comprising a flow path connected to the first circulation flow path and the second circulation flow path, and a separation device connected to the flow path, wherein the separation device separates crystals of metal components from the water supplied from the flow path.

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