Water softening unit

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] This invention relates to a water softening device. [Background technology]

[0002] In hard water areas, problems caused by hardness components such as scale and limescale are common, and water softening devices are needed. One method of water softening is using ion exchange resin (see, for example, Patent Document 1), but this method involves regeneration with salt, which results in the generation of salt wastewater. Other methods of water softening include using EDI and RO membranes (see, for example, Patent Document 2), but these methods have the problem of producing a large amount of wastewater. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 3145240 [Patent Document 2] International Publication No. 2007 / 132685 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] A water softening device that uses electrolysis to soften water is a possibility. In a water softening device that uses electrolysis, it is desirable to make the hardness of the softened water produced in the end as low as possible.

[0005] Therefore, the object of the present invention is to solve the above problems by providing a water softening device that can further reduce the hardness of softened water. [Means for solving the problem]

[0006] To achieve the above objective, the water softening apparatus of the present invention comprises an electrolysis apparatus that generates alkaline water and acidic water by electrolysis; a circulation channel connected to the electrolysis apparatus, comprising a first circulation channel and a second circulation channel through which the alkaline water and acidic water generated by the electrolysis apparatus can be alternately passed; a first sensor for detecting the parameters of the water flowing through the first circulation channel; a second sensor for detecting the parameters of the water flowing through the second circulation channel; and a control unit. The control unit controls the electrolysis apparatus to execute a first mode in which alkaline water is passed through the first circulation channel and acidic water is passed through the second circulation channel, and a second mode in which acidic water is passed through the first circulation channel and alkaline water is passed through the second circulation channel. In the first and second modes, the control unit controls the electrolysis apparatus to stop electrolysis based on the detected value of the first sensor or the second sensor. [Effects of the Invention]

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

[0008] [Figure 1] Schematic diagram of a water softening device in an embodiment [Figure 2] Flowchart showing the water softening device in its first mode, as shown in Figure 1. [Figure 3] Diagram showing the water flow in the first raw water injection mode in the first mode. [Figure 4] Diagram showing the water flow in the first crystallization treatment mode in the first mode. [Figure 5] Diagram showing the water flow in the first acidic water delivery mode in the first mode. [Figure 6] Diagram showing the water flow in the first alkaline water supply mode in the first mode. [Figure 7] Diagram showing the water flow in the first pipe cleaning mode in the first mode. [Figure 8] Diagram showing the water flow in the first electrolytic tank cleaning mode in the first mode. [Figure 9]Flowchart showing a method for determining continuation / stop of electrolysis in the first crystallization treatment mode [Figure 10] Graph showing the time evolution of "alkaline pH" and "ion separation rate" in the first crystallization treatment mode [Figure 11] Flowchart when the water softening device shown in FIG. 1 executes the second mode [Figure 12] Diagram showing the water flow in the second raw water injection mode in the second mode [Figure 13] Diagram showing the water flow in the second crystallization treatment mode in the second mode [Figure 14] Diagram showing the water flow in the second acidic water supply mode in the second mode [Figure 15] Diagram showing the water flow in the second alkaline water supply mode in the second mode [Figure 16] Diagram showing the water flow in the second pipe cleaning mode in the second mode [Figure 17] Diagram showing the water flow in the second electrolysis tank cleaning mode in the second mode [Figure 18A] Schematic diagram showing the time evolution of parameters when using a conductivity sensor or a TDS sensor [Figure 18B] Schematic diagram showing the time evolution of parameters when using a turbidity sensor or a chromaticity sensor [Figure 18C] Schematic diagram showing the time evolution of parameters when using a hardness sensor

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 this embodiment.

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

[0011] Water softening device 2 is a device that uses electrolysis to remove metal ions, which are hardness components, from water. Here, metal ions 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, thereby reducing the concentration (hardness) of metal ions in hard water to a predetermined concentration or less. For the definitions of hard water and soft water, for example, the WHO definition 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 Figure 1 comprises raw water channels 4A and 4B, batch processing tanks 6A and 6B, circulation channels 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 comprises various valves, including valves 22A and 22B, valve 24, valve 26, valves 28A and 28B, valve 30, and valve 32.

[0013] The raw water channels 4A and 4B are channels for supplying raw water to batch processing tanks 6A and 6B, respectively. The raw water is, for example, hard water. The upstream side of the raw water channels 4A and 4B is connected to a water source (not shown), and the downstream side is connected to batch processing tanks 6A and 6B. Valves 22A and 22B are provided in the raw water channels 4A and 4B, respectively. The opening and closing of valves 22A and 22B controls the flow of water from the raw water channels 4A and 4B to the batch processing tanks 6A and 6B, respectively.

[0014] Batch processing tanks 6A and 6B are water storage tanks for batch processing. Each batch processing tank 6A and 6B is equipped with a float sensor (not shown) that can detect the amount of water stored in each tank. Circulation channels 8A and 8B are connected to batch processing tanks 6A and 6B, respectively.

[0015] The circulation channels 8A and 8B are two circulation channels connected to batch processing tanks 6A and 6B. Each of the circulation channels 8A and 8B extends downstream from the batch processing tanks 6A and 6B, and merges at the point where it connects to valve 24 to form a single circulation channel. The combined circulation channels 8A and 8B are then connected to the electro-separator 12 via pump 10 and valve 26.

[0016] The flow of water from batch processing tanks 6A and 6B to the electrolysis apparatus 12 is controlled by opening and closing valves 24 and 26. Water flows downstream from batch processing tanks 6A and 6B by driving a pump 10 located between valves 24 and 26.

[0017] The electrolysis apparatus 12 is a device that produces alkaline water and acidic water by electrolyzing water supplied through circulation channels 8A and 8B. The electrolysis apparatus 12 comprises a positive electrode (anode) and a negative electrode (cathode), and a diaphragm provided between the two electrodes. By applying a voltage between the positive and negative electrodes, it electrolyzes water to produce alkaline water and acidic water.

[0018] Two circulation channels, 8A and 8B, are connected to the downstream side of the electrolysis apparatus 12.

[0019] The circulation channels 8A and 8B connected downstream from the electrolysis device 12 are capable of alternately passing alkaline water and acidic water produced by the electrolysis device 12. When alkaline water flows through circulation channel 8A, acidic water flows through circulation channel 8B, and when acidic water flows through circulation channel 8A, alkaline water flows through circulation channel 8B.

[0020] The circulation channel 8A, connected downstream from the electrolysis apparatus 12, has a valve 28A and a pH sensor 14A along its length and is connected to the batch processing tank 6A. Similarly, the circulation channel 8B, also connected downstream from the electrolysis apparatus 12, has a valve 28B and a pH sensor 14B along its length and is connected to the batch processing tank 6B. The opening and closing of valves 28A and 28B controls the flow of water from the electrolysis apparatus 12 to the batch processing tanks 6A and 6B, respectively.

[0021] The circulation channels 8A and 8B, having the configuration described above, each constitute a circulation channel that returns water from batch processing tanks 6A and 6B to batch processing tanks 6A and 6B via the electrolysis device 12. In this embodiment, the circulation channels 8A and 8B merge at the point from valve 24 to the electrolysis device 12 to form a single channel. Compared to the case where the circulation channels 8A and 8B are independent channels without merging, the configuration of the water softening device 2 can be simplified, for example, by requiring only one pump 10.

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

[0023] At the point where circulation channels 8A and 8B merge to form a single channel, a valve 26 is provided, to which a channel 34 is connected in addition to circulation channels 8A and 8B. Channel 34 is connected to a separation device 16.

[0024] The separation device 16 is a device that separates metal component crystals from water supplied from the flow path 34. The separation device 16 in this 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 to two channels, channel 36 and channel 38. Channel 36 is a channel through which water from which crystals have been separated by the separation device 16 passes. Channel 38 is a drainage channel through which wastewater containing the crystals separated by the separation device 16 passes, and it extends outside the system of the water softener 2.

[0026] A channel 36 through which the water containing the separated crystals passes is connected to a valve 30. Channels 40 and 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 that flows through the flow path 40. The opening and closing of the valve 30 controls the flow of water from the separation device 16 through the flow paths 36 and 40 to the intermediate tank 18.

[0028] Flow path 41 is a bypass flow path that connects batch processing tanks 6A and 6B and the intermediate tank 18 without passing through the electrolysis apparatus 12 and the separation apparatus 16. Two flow paths 41A and 41B are connected to flow path 41, and flow paths 41A and 41B are connected to the aforementioned valves 28A and 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 in the middle of the CO2 supply line 42, and the supply / stopping of CO2 gas is controlled by opening and closing the valve 32.

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

[0031] The water storage tank 20 is a tank for storing treated water after the water softening treatment has been completed. The treated water, i.e., softened water, stored in the water storage tank 20 can be supplied to faucets and other devices for use by end users.

[0032] The water storage tank 20 is equipped with a pressure sensor (not shown). By detecting the decrease in pressure due to the consumption of treated water using the pressure sensor, the amount of water stored in the water storage tank 20 can be detected.

[0033] The control unit 21 is a component that controls each of the components 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 performs functions such as opening and closing control of each valve, ON / OFF control of the pump 10, ON / OFF control of the electrolysis device 12, and ON / OFF control of the separation device 16. The control unit 21 is composed of a microcomputer that includes a processor and a memory that stores a computer program executed by the processor.

[0034] In this embodiment, the control unit 21 operates the water softener 2 in two operating modes: a first mode and a second mode.

[0035] First, the first mode will be explained using Figures 2 and 3 to 8. Figure 2 is a flowchart showing the execution of the first mode using the water softening device 2. Figures 3 to 8 are schematic diagrams showing the water flow, etc., when the first mode is executed according to the flowchart shown in Figure 2.

[0036] (First raw water injection mode) As shown in Figure 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 the raw water, is injected into the water softener 2 when the operation of the water softener 2 is started. Specifically, the control unit 21 controls the flow to create the flow shown in Figure 3. In the drawings from Figure 3 onward, the flow of water is represented by arrows, and it is assumed that there is no water flow in the flow path without an arrow. In addition, the state of an open valve is represented by hatching, and the state of a closed valve is represented by filling it in black.

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

[0038] When a predetermined amount (e.g., 10 L) of raw water is passed through the batch processing tank 6A, the control unit 21 closes the valve 22A and executes the first crystallization processing mode (step S2-1).

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

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

[0041] In the first crystallization treatment mode, the electrolysis device 12 is controlled so that, of the alkaline water and acidic water produced by the electrolysis device 12, the alkaline water is passed through the circulation channel 8A and the acidic water is passed through the circulation channel 8B.

[0042] The control unit 21 controls the opening and closing of valve 28A to return the alkaline water that has passed through the circulation channel 8A back to the batch processing tank 6A, and controls the opening and closing of valve 28B to return the acidic water that has passed through the circulation channel 8B back to the batch processing tank 6B. This results in the flow shown by the arrows in Figure 4.

[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 consumed water is newly stored in the batch treatment tank 6A. As a result, the water storage amount 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 amount 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 acid water decreases. On the other hand, even in alkaline water containing a large amount of OH - , the hardness in the water decreases due to 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 shown 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 shown in Formula 2 to produce insoluble CaCO3 (calcium carbonate). As shown in Formula 3, Mg2+ OH is 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, thus reducing the hardness of the alkaline water. As a result, the hardness of both acidic and alkaline water decreases.

[0048] By continuously supplying and circulating alkaline water through the circulation channel 8A, the reactions shown in equations 1 to 3 above are continuously generated, causing metal ions in the alkaline water to crystallize and precipitate, thereby reducing the hardness of the raw water.

[0049] The control unit 21 terminates the first crystallization processing mode at a predetermined timing and executes the next first acidic water supply mode (step S3-1). The timing for terminating the first crystallization processing 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) Figure 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 separation device 16. Specifically, while driving the pump 10, it opens valve 24 to allow water to flow from the batch processing tank 6B to the circulation channel 8B, and opens valve 26 to allow water to flow from the circulation channel 8B to the channel 34.

[0051] The control unit 21 does not operate the separation device 16 and allows the acidic water that would reach the separation device 16 to pass through directly into the flow path 36. The control unit 21 then opens the valve 30 to allow the acidic water that has passed through the flow path 36 to pass into the flow path 40. As a result, the acidic water is passed 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. The control unit 21 in this embodiment continues the first acidic water supply mode until the amount of acidic water in the batch processing tank 6B decreases to a predetermined amount (for example, 2L). 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 supply mode and executes the next first alkaline water supply mode (S4-1).

[0053] (First alkaline water supply mode) Figure 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 separation device 16. In the first acidic water supply mode described above, 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 Figure 6, while driving the pump 10, valve 24 is opened to allow water to flow from the batch processing tank 6A to the circulation channel 8A, and valve 26 is opened to allow water to flow from the circulation channel 8A to the channel 34.

[0055] The control unit 21 operates the separation device 16 to separate the crystals contained in the alkaline water by centrifugal force. The separation device 16 passes the alkaline water from which the crystals have been separated through the channel 36 and the wastewater containing the crystals through the channel 38 for discharge.

[0056] The alkaline water, after crystal separation, which has passed through channel 36, is then passed through channel 40 to the intermediate tank 18. Since acidic water is already stored in the intermediate tank 18, the alkaline water and acidic water are mixed in the intermediate tank 18. The mixture of alkaline and acidic water is neutralized, and its pH value becomes close to neutral. As mentioned above, both alkaline and acidic water have low hardness, so the hardness of the mixed water also becomes low. As a result, the mixed water stored in the intermediate tank 18 is produced as 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 separation device 16. The control unit 21 supplies CO2 to the intermediate tank 18 by controlling the opening and closing of valve 32 to supply CO2 from CO2 supply line 42 as needed. This promotes the reaction shown in Equation 4 below.

[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, thereby reducing the turbidity of the treated water. 2+ The reaction equation will be omitted for this part.

[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. The control unit 21 in this embodiment continues the first alkaline water supply 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 supply mode and executes the next first pipe cleaning mode (S5-1).

[0061] (First pipe cleaning mode) Figure 7 shows the first piping 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 channels 41, 41A, and 41B.

[0062] Specifically, while driving the pump 10, valve 24 is opened to allow water to flow from the batch processing tank 6B to the circulation channel 8B, and 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 instead allows the acidic water that would reach the separation device 16 to pass through directly to the channel 36.

[0063] The control unit 21 further controls the opening and closing of valve 30 so that the acidic water that has passed through flow path 36 passes through flow path 41 and flow paths 41A and 41B. The control unit 21 further controls the opening and closing of valves 28A and 28B so that the acidic water that has passed through flow paths 41A and 41B passes through circulation flow paths 8A and 8B to 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) attached to the inner wall surface of each pipe, thereby cleaning the pipes.

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

[0066] (First electrolytic tank cleaning mode) Figure 8 shows the first electrolytic tank 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 electrolysis device 12.

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

[0068] This creates a flow of acidic water as shown in Figure 8. As the acidic water flows through the electrolysis apparatus 12 and each pipe, the scale adhering to the inner walls of the electrolysis apparatus 12 and each pipe is dissolved in the acidic water, thereby cleaning the electrolysis apparatus 12 and each pipe.

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

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

[0071] Here, the method for determining whether to continue or stop the electrolysis of the electrolysis apparatus 12 in the first crystallization processing mode (S2-1) will be explained using Figures 4 and 9. Figure 9 is a flowchart showing an example of the method for determining whether to continue or stop the electrolysis of the electrolysis apparatus 12.

[0072] In the water flow of the water softener 2 shown in Figure 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 is within a predetermined range, as shown in Figure 9 (S7: First determination). The predetermined period is, for example, 1 minute, and the predetermined range is, for example, -0.02 to 0.02.

[0073] If the first determination determines that the fluctuation value over a predetermined period is not within the predetermined range (NO in S7), the control unit 21 repeats step S7. If the first determination determines that the fluctuation value over a 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 over the predetermined period is greater than or equal to a predetermined value (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, if it is determined that the increase during the predetermined period is not equal to or greater than the predetermined value (NO in S8), the control unit 21 executes step S8 again. In the second determination, if it is determined that the increase during the predetermined period is equal to or greater than 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 system transitions to the first acidic water supply mode (S3-1).

[0075] Figure 10 shows an example of experimental data related to the method for determining whether to continue or stop electrolysis, as explained in Figure 9. Figure 10 is a graph showing the time changes 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 value detected by pH sensor 14A and indicates the pH value of 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 indicator of the degree to which the hardness of the raw water has decreased due to electrolysis. The higher the ion separation rate, the greater the decrease in the hardness of the acidic water. 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 by the electrolysis apparatus 12 is started, the "alkaline pH" value increases as alkaline water is produced. On the other hand, the hardness of the acidic water decreases as metal ions are attracted to the alkaline water by electrophoresis, so the "ion separation rate" also increases.

[0078] Subsequently, the increase in alkaline pH and ion separation rate stops, and a steady state is reached (approximately 2 minutes after the start). In the steady state, the reactions shown in equations 1 to 3 above proceed, and the crystallization of the metal component progresses.

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

[0080] The alkaline pH rises again because the reactions in equations 1-3 proceed, and the substances required for the reactions in equations 1-3 (HCO3) are produced. - As the amount of (etc.) decreases in the water, the reactions in equations 1 to 3 become slower, - This is because the consumption of [the substance] decreases. Also, the ion separation rate decreases because crystallization progresses through the reactions in Equations 1 to 3, and the crystal clumps become larger, so as shown in Equation 5 below, the CaCO3 crystals become acid (H + ) dissolve in Ca 2+ This is because it produces a reaction that increases the hardness of acidic water. The reaction equation for Mg(OH)2 is omitted.

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

[0082] In light of the behavior of "alkaline pH" and "ion separation rate" as shown in Figure 10, the control unit 21 of this embodiment performs the first determination (S7) and the second determination (S8) described above.

[0083] The first determination (S7) determines whether the fluctuation value of the alkaline pH over a predetermined period is within a predetermined range, thereby determining whether or not a steady state (the period from approximately 2 minutes to approximately 8 minutes) is in place, as shown in the graph of Figure 10.

[0084] Furthermore, after determining that a steady state has been reached by the first determination (S7), the second determination (S8) determines whether the increase in alkaline pH over a predetermined period is greater than or equal to a predetermined value. This makes it possible to determine whether or not a further increase in alkaline pH (after approximately 8 minutes), as shown in the graph of Figure 10, has occurred.

[0085] If a rise in alkaline pH is detected again by the second judgment (S8), the electrolysis of the electrolysis device 12 is controlled to stop (S9), allowing the electrolysis to be stopped before the ion separation rate begins to decrease rapidly (approximately 8 minutes later). This makes it possible to maintain a low hardness in the acidic water produced by electrolysis, and ultimately lower the hardness of the soft water produced by mixing the acidic water and alkaline water. In this way, the hardness of the soft water can be reduced in the water softening device 2 that softens water using electrolysis.

[0086] In this embodiment, after executing the first mode, which includes steps S1-1 to S6-1 described above, the water softening device 2 replaces the batch processing tanks 6A and 6B and circulation channels 8A and 8B used in the first mode and executes a second mode, which is a similar water softening treatment. Specifically, after executing the first mode, the control unit 21 executes the second mode according to the flowchart shown in Figure 11.

[0087] As shown in Figure 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 supply mode (S3-2), the second alkaline water supply mode (S4-2), the second pipe cleaning mode (S5-2), and the second electrolytic tank cleaning mode (S6-2).

[0088] Figures 12 to 17 show the water flow in each mode of steps S1-2 to S6-2. 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 tank cleaning mode.

[0089] In Figures 12 to 17, water flow is represented by arrows, similar to Figures 3 to 8, and it is assumed that there is no water flow in the channels without arrows. Additionally, an open valve is represented by hatching, and a closed valve is represented by a solid black color.

[0090] As shown in Figures 12 to 17, the only difference between the second mode and the first mode is that the batch processing tanks 6A and 6B and the circulation channels 8A and 8B are swapped.

[0091] As shown in Figure 12, in the second raw water injection mode (S1-2), raw water is injected into the batch processing tank 6B. As shown in Figure 13, in the second crystallization processing mode (S2-2), the raw water stored in the batch processing tank 6B is supplied to the electrolysis device 12 for electrolysis, and the generated alkaline water is passed through the circulation channel 8B and circulated in the circulation channel 8B including the batch processing tank 6B, while the acidic water is passed through the circulation channel 8A and stored in the batch processing tank 6A. As shown in Figure 14, in the second acidic water supply mode (S3-2), the acidic water stored in the batch processing tank 6A is supplied to the intermediate tank 18 via the separation device 16. As shown in Figure 15, in the second alkaline water supply mode (S4-2), the alkaline water stored in the batch processing tank 6B is supplied to the separation device 16 to separate the crystals, and the alkaline water after crystal separation is supplied to the intermediate tank 18 and mixed with the acidic water. As shown in Figure 16, in the second piping cleaning mode (S5-2), the acidic water remaining in the batch processing tank 6A is flowed through the separation device 16 to the bypass channels 41, 41A, and 41B to clean each pipe. As shown in Figure 17, in the second electrolytic cell cleaning mode (S6-2), the acidic water remaining in the batch processing tank 6A is flowed to 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 Figure 13, alkaline water is circulated through the circulation channel 8B while electrolysis is performed by the electrolysis device 12. This increases the pH value of the water flowing through the circulation channel 8B, causing the metal components contained in the water to crystallize and reducing the hardness of the raw water.

[0093] Furthermore, in the second crystallization processing mode (S2-2), the control unit 21 determines whether to continue or stop the electrolysis of the electrolysis apparatus 12 by performing the first determination (S7) and the second determination (S8) shown in Figure 9. Specifically, the control unit 21 determines whether to continue or stop the electrolysis of the electrolysis apparatus 12 by performing 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 installed in the circulation channel 8B. This makes it possible to stop the electrolysis before the ion separation rate drops sharply as shown in the graph of Figure 10 (approximately 8 minutes later), thereby maintaining the hardness of the acidic water at a low value and ultimately lowering the hardness of the soft water produced.

[0094] The control unit 21 continuously produces softened water by alternately executing the first mode (S1-1 to S6-1) shown in Figure 2 and the second mode (S1-2 to S6-2) shown in Figure 11.

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

[0096] With this configuration, by controlling the operation of the electrolysis apparatus 12 based on the detection values ​​of pH sensors 14A and 14B, it becomes possible to stop electrolysis at the point when the "ion separation rate" begins to decrease rapidly, that is, when the hardness of the acidic water begins to increase. This makes it possible to reduce the hardness of the soft water that is ultimately produced.

[0097] 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. In other words, the decision 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 for evaluation, there are advantages compared to using acidic water as the target (for example, directly detecting the hardness of acidic water with a hardness sensor to determine whether to continue or stop electrolysis), such as being able to use a general-purpose and inexpensive configuration of pH sensors 14A and 14B.

[0099] In the water softening device 2 of this embodiment, the pH sensor 14A is located downstream of the electrolysis device 12 and upstream of the batch processing tank 6A in the circulation channel 8A. The pH sensor 14B is located downstream of the electrolysis device 12 and upstream of the batch processing tank 6B in the circulation channel 8B.

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

[0101] In the water softening device 2 of this embodiment, the control unit 21 determines whether the fluctuation value of the pH sensor 14A and 14B's detected values ​​(alkaline water) over a predetermined period 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 in the pH sensor 14A and 14B's detected values ​​over a predetermined period is greater than or equal to a predetermined value (S8). If it is determined that the increase is greater than or equal to a predetermined value (YES in S8), the control unit 21 controls the electrolysis device 12 to stop electrolysis (S9).

[0102] With this configuration, it becomes possible to stop the electrolysis operation at the point when the "ion separation rate" begins to decrease rapidly, that is, when the hardness of the acidic water begins to increase, thereby making it possible to lower the hardness of the soft water that is ultimately produced.

[0103] The water softening device 2 of the embodiment further includes a batch processing tank 6A (first batch processing tank) located in the middle of the circulation channel 8A, a batch processing tank 6B (second batch processing tank) located in the middle of the circulation channel 8B, and a valve 24. The valve 24 controls the flow / stopping of water from batch processing tank 6A downstream and from batch processing tank 6B downstream. In this configuration, the control unit 21 controls the valve 24 in the first mode to allow water to flow from batch processing tank 6A downstream and stop the flow in batch processing tank 6B, and in the second mode to allow water to flow from batch processing tank 6B downstream and stop the flow in batch processing tank 6A.

[0104] With this configuration, it becomes possible to operate the system by storing the acidic water produced by electrolysis in batch processing tanks 6A and 6B, while circulating the alkaline water through circulation channels 8A and 8B, respectively.

[0105] In the water softening device 2 of this embodiment, the circulation channels 8A and 8B merge at a point downstream from the batch processing tanks 6A and 6B, respectively, and are connected to the electrolysis device 12.

[0106] This configuration allows for a simplified setup of the water softening device 2.

[0107] It should be noted that the present invention is not limited to the embodiments described above and can be implemented in various other forms. For example, in the embodiments, a case was described in which the continuation / stopping of electrolysis is determined based on the pH value of the alkaline water flowing through the circulation channels 8A and 8B using pH sensors 14A and 14B, but the invention is not limited to this case. A sensor other than the pH sensor may be used to detect a parameter other than the pH value, and the continuation / stopping of electrolysis may be determined based on the detected value. Specific examples of other sensors include, for example, conductivity sensors, TDS sensors, turbidity sensors, chromaticity sensors, and hardness sensors.

[0108] The conductivity sensor detects "conductivity" as a parameter of water, the TDS sensor detects "total dissolved solids", the turbidity sensor detects "turbidity", the chromaticity sensor detects "chromaticity", and the hardness sensor detects "hardness". The time evolution of each parameter during electrolysis when using these sensors is shown in Figures 18A to 18C.

[0109] Figure 18A is a schematic diagram showing the time evolution of the detected values ​​of each parameter when using a conductivity sensor or a TDS sensor.

[0110] As shown in Figure 18A, when a conductivity sensor or TDS sensor is used, the detected parameter values ​​show the same time progression as when pH sensors 14A and 14B are used (see Figure 10). Specifically, the parameter rises upon the start of electrolysis, reaches a steady state, and then rises again. Since the timing of this re-rise corresponds to the timing when the hardness of the acidic water begins to increase, the first determination (S7) and second determination (S8) as in Figure 9 can be performed to decide whether to continue or stop the electrolysis. This makes it possible to achieve the same effects and advantages as in the embodiment.

[0111] Figure 18B is a schematic diagram showing the time evolution of the detected values ​​of each parameter when using a turbidity sensor or a chromaticity sensor.

[0112] As shown in Figure 18B, when a turbidity sensor or chromaticity sensor is used, the detected parameter values ​​behave differently from those when using pH sensors 14A, 14B, conductivity sensors, or TDS sensors. Specifically, the parameter increases as electrolysis begins, but the rate of increase gradually decreases until it reaches a saturation point where the parameter increase effectively stops. Since this saturation point where the parameter increase stops corresponds to the timing when the hardness of the acidic water begins to increase, the continuation or cessation of electrolysis can be determined by determining whether or not the saturation point has been reached. Specifically, based on the detected values ​​of the turbidity sensor or chromaticity sensor, the electrolysis device 12 may be controlled to stop electrolysis when the rate of increase (rate of change) of the parameter per unit time falls below a predetermined value.

[0113] Figure 18C is a schematic diagram showing the time evolution of the detected parameter values ​​when using a hardness sensor.

[0114] As shown in Figure 18C, when a hardness sensor is used, the detected parameter values ​​behave differently from those in Figures 18A and 18B. Specifically, the parameter decreases as electrolysis begins, but the rate of decrease gradually declines until it reaches a saturation point where the decrease in the parameter effectively stops. Since this saturation point where the decrease in the parameter stops corresponds to the timing when the hardness of the acidic water begins to increase, the continuation or cessation of electrolysis can be determined by determining whether or not the saturation point has been reached. Specifically, based on the detected value of the hardness sensor, the electrolysis device 12 may be controlled to stop electrolysis when the rate of decrease (rate of change) of the parameter per unit time falls below a predetermined value.

[0115] When using the sensors described above, acidic water may be used as the target for evaluation instead of alkaline water, depending on the characteristics of the sensor. In other words, the decision to continue or stop electrolysis may be made based on the detected values ​​of the parameters of the acidic water. For example, when using a pH sensor, conductivity sensor, or hardness sensor, acidic water may be used as the target for evaluation instead of alkaline water. In particular, by using a hardness sensor to detect the hardness of acidic water as a parameter for evaluation, changes in the hardness of the acidic water can be monitored more directly.

[0116] Furthermore, any sensor capable of detecting parameters related to the timing at which the ion separation rate begins to decrease rapidly, i.e., the timing at which the hardness of acidic water begins to increase, may be used, not limited to the sensors described above. Such sensors may be collectively referred to as "crystallinity sensing sensors," "acidic water hardness sensing sensors," etc.

[0117] Furthermore, although the above embodiment describes the case in which batch processing tanks 6A and 6B are provided in the middle of the circulation channels 8A and 8B, respectively, the invention is not limited to this case. Batch processing tanks 6A and 6B may not be provided. Even in such cases, by devising the shape and length of the circulation channels 8A and 8B, or by appropriately providing valves, it is possible to perform operation in which alkaline water is circulated in the same manner as the first crystallization processing mode (S2-1) and the second crystallization processing mode (S2-2) described above.

[0118] Furthermore, in the above embodiment, we have described the case in which, in the first mode shown in Figure 2, the first alkaline water supply mode is performed after the first acidic water supply mode, and in the second mode shown in Figure 11, the second alkaline water supply mode is performed after the second acidic water supply mode. However, the embodiment is not limited to this case. The acidic water supply mode may be performed after the alkaline water supply mode.

[0119] Furthermore, by appropriately combining the various forms described above, it is possible to achieve the effects that each form possesses.

[0120] Although the present invention has been fully described in relation to preferred embodiments with reference to the accompanying drawings, various modifications and alterations will be obvious to those skilled in the art. Such modifications and alterations should be understood to be included within the scope of the invention as defined in the appended claims. Furthermore, changes in the combination and order of elements in the embodiments can be realized without departing from the scope and spirit of the invention. [Industrial applicability]

[0121] This invention is useful for both household 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 channel (First circulation channel) 8B Circulation channel (Second circulation channel) 10 pumps 12 Electrolysis apparatus 14A pH sensor (1st sensor, 1st pH sensor) 14B pH sensor (second sensor, second pH sensor) 16 Separation device 18 Intermediate Tank 20 Water storage tanks 21 Control Unit 22A, 22B, 24, 26, 28A, 28B, 30, 32 valves 34 Flow channels 36 channels 38. Flow channels (drainage channels) 40 flow channels 41, 41A, 41B channels (bypass channels) 42 CO2 supply lines 44 channels

Claims

1. An electrolysis apparatus that produces alkaline water and acidic water by electrolysis, A circulation channel connected to the electrolysis apparatus, comprising a first circulation channel and a second circulation channel capable of alternately passing alkaline water and acidic water produced by the electrolysis apparatus, A first sensor for detecting parameters of the water flowing through the first circulation channel, A second sensor for detecting the parameters of the water flowing through the second circulation channel, Control unit and A first batch processing tank is provided in the middle of the first circulation channel, A second batch processing tank is provided in the middle of the second circulation channel, The system includes a valve that controls the flow / stopping of water from the first batch processing tank downstream and the flow / stopping of water from the second batch processing tank downstream, The first sensor and the second sensor are one of a pH sensor, a conductivity sensor, and a TDS sensor. The control unit, The electrolysis apparatus is controlled to perform a first mode in which alkaline water is passed through the first circulation channel and acidic water is passed through the second circulation channel, a second mode in which acidic water is passed through the first circulation channel and alkaline water is passed through the second circulation channel, and a first pipe cleaning mode in which the pipes constituting the first and second circulation channels are cleaned. In the first mode, it is determined whether the fluctuation value of the detected value of the first sensor over a predetermined period is within a predetermined range. If it is determined that the fluctuation value is within a predetermined range, it is then determined whether the increase in the detected value of the first sensor over a predetermined period is greater than or equal to a predetermined value. If it is determined that the aforementioned increase is equal to or greater than the predetermined value, the electrolysis apparatus is controlled to stop the electrolysis. In the second mode, it is determined whether the fluctuation value of the detected value of the second sensor over a predetermined period is within a predetermined range. If it is determined that the fluctuation value is within a predetermined range, it is then determined whether the increase in the detected value of the second sensor over a predetermined period is greater than or equal to a predetermined value. If it is determined that the aforementioned increase is equal to or greater than the predetermined value, the electrolysis apparatus is controlled to stop the electrolysis. A water softening device that, in the first piping cleaning mode, controls the valve to return the acidic water remaining in the second batch processing tank to the first batch processing tank and the second batch processing tank.

2. An electrolysis apparatus that produces alkaline water and acidic water by electrolysis, A circulation channel connected to the electrolysis apparatus, comprising a first circulation channel and a second circulation channel capable of alternately passing alkaline water and acidic water produced by the electrolysis apparatus, A first sensor for detecting parameters of the water flowing through the first circulation channel, A second sensor for detecting the parameters of the water flowing through the second circulation channel, Control unit and A first batch processing tank is provided in the middle of the first circulation channel, A second batch processing tank is provided in the middle of the second circulation channel, A valve that controls the flow / stopping of water from the first batch processing tank downstream, and the flow / stopping of water from the second batch processing tank downstream, Equipped with, The first sensor and the second sensor are hardness sensors, The control unit, The electrolysis apparatus is controlled to perform a first mode in which alkaline water is passed through the first circulation channel and acidic water is passed through the second circulation channel, a second mode in which acidic water is passed through the first circulation channel and alkaline water is passed through the second circulation channel, and a first pipe cleaning mode in which the pipes constituting the first and second circulation channels are cleaned. In the first mode, it is determined whether the rate of decrease per unit time of the detected value of the first sensor is less than or equal to a predetermined value. If it is determined that the rate of decrease is less than or equal to the predetermined value, the electrolysis apparatus is controlled to stop the electrolysis. In the second mode, it is determined whether the rate of decrease per unit time of the detected value of the second sensor is less than or equal to a predetermined value. If it is determined that the rate of decrease is less than or equal to the predetermined value, the electrolysis apparatus is controlled to stop the electrolysis. A water softening device that, in the first piping cleaning mode, controls the valve to return the acidic water remaining in the second batch processing tank to the first batch processing tank and the second batch processing tank.

3. The water softening apparatus according to claim 1 or 2, wherein the first sensor is provided downstream of the electrolysis apparatus and upstream of the first batch processing tank in the first circulation channel, and the second sensor is provided downstream of the electrolysis apparatus and upstream of the second batch processing tank in the second circulation channel.

4. The water softening apparatus according to claim 1 or 2, wherein the first circulation channel and the second circulation channel each merge at a position extending downstream from the first batch processing tank and the second batch processing tank and are connected to the electrolysis apparatus.

5. The water softening apparatus according to claim 1 or 2, further comprising a channel connected to the first circulation channel and the second circulation channel, and a separation device connected to the channel, wherein the separation device separates metal component crystals from water supplied from the channel.

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