JP2010125353A - Water softening method and water softener - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for softening water by which the consumption of an electrode material is suppressed, so that maintenance cost for a water softener can be reduced, and to provide the water softener. <P>SOLUTION: In the water softening method where the water to be treated is made to flow between confronted electrodes, and D.C. voltage is applied between the electrodes so as to electrolytically deposit metal ions in the water to be treated on the electrode on the cathode side, a titanium based alloy electrode containing 0.1 to 5 mass% nickel is used at least as the electrode on the anode side. Further, the water softener includes: an electrolytic cell receiving and exhausting the water to be treated; a first electrode installed in the electrolytic cell; a second electrode installed at prescribed intervals with the first electrode in the electrolytic cell; and a D.C. power source applying D.C. voltage to the space between the first electrode and the second electrode, and in which at least the electrode to form into the electrode on the anode side between the first electrode and the second electrode is made of a titanium based alloy electrode containing 0.1 to 5 mass% nickel. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method and an apparatus for softening water to be treated by electrolysis. More specifically, the present invention relates to a water softening method and an apparatus therefor, which include depositing ions in water to be treated on the surface of an electrode or in the vicinity thereof by electrolysis.

  Water to be treated is supplied into an electrolytic cell equipped with opposing electrode plates, and a DC voltage is applied between the electrode plates to remove cations and anions in the water to be treated by oxidation or reduction on the surface of the electrode plates. There are known methods for softening water to be treated and such devices.

  When such an apparatus is operated for a long period of time, components such as alkali metal ions, alkaline earth metal ions and ionic silica contained in the water to be treated are deposited on the surface of the cathode side electrode plate as a scale, and gradually become current. May not flow, making it difficult to soften the water to be treated.

  For this reason, conventionally, when the scale attached to the surface of the electrode plate on the cathode side exceeds a certain amount and it becomes difficult for current to flow, the electrode plate is removed from the electrolytic cell and the scale is physically removed from the surface of the electrode plate. The electrode plate was again attached to the electrolytic cell. However, there is a problem that these series of operations are time-consuming and require considerable cost for maintenance of the apparatus.

  In order to deal with such problems, a pure titanium plate is used as the electrode plate, and the scale attached to the electrode plate surface is automatically reversed by periodically reversing the polarity of the voltage applied between the electrode plates. A water softening device that can be peeled off is proposed (Patent Document 1).

When water to be treated is treated by electrolysis using a pure titanium electrode plate, an anodic oxide coating (TiO ₂ ) is gradually formed on the electrode surface on the anode side. This anodic oxide film is more easily generated as the overvoltage of the anode-side electrode is higher. In general, when a voltage of about 15 to 18 V is applied between the electrode plates, the generated anodic oxide film breaks down and peels off from the electrode surface. As described above, since the pure titanium electrode plate is consumed as the apparatus is operated, it is necessary to periodically replace it with a new electrode. In addition, when an expensive noble metal material such as Pt or a material that is quickly consumed such as Al, SUS, or Fe is used as the electrode plate, as in the case of using a pure titanium plate, the cost of the electrode plate itself It was difficult to reduce the costs associated with the maintenance of the equipment.

International Publication WO2008 / 018316 Pamphlet

  The present invention relates to a water softening method capable of reducing the costs associated with the maintenance of electrode materials and apparatuses by suppressing the consumption of the electrode materials and efficiently performing the water softening treatment of the water to be treated. An object is to provide such a device.

  According to one embodiment of the present invention, the water to be treated is disposed between the opposing electrodes, a DC voltage is applied between the electrodes, and the metal ions in the water to be treated are electrolytically deposited on the cathode side electrode. A method for softening water to be treated, comprising using a titanium-based alloy electrode containing 0.1 to 5% by mass of nickel as an electrode on at least the anode side Is provided.

  In another embodiment of the present invention, a titanium-based alloy electrode containing 0.1 to 5% by mass of nickel is used for both the cathode side and anode side electrodes, and the polarity of the voltage applied between the electrodes is changed every predetermined time. May be reversed.

In another embodiment of the present invention, the current flowing between the electrodes may be 0.1 to 30 A per 1 m ² of the anode-side electrode area.

  In another embodiment of the present invention, the current flowing between the electrodes may be a constant current.

  In another embodiment of the present invention, when the electrical conductivity of the treated water is higher than the predetermined value A, the current flowing between the electrodes is increased, and when the electrical conductivity of the treated water is lower than the predetermined value B, The current flowing between the electrodes may be reduced so that the predetermined value A and the predetermined value B have a relationship of A ≧ B. At this time, it is preferable that the predetermined value A of the electric conductivity of the water to be treated is 30 to 150 mS / m and the predetermined value B is 30 to 150 mS / m.

  Further, according to one embodiment of the present invention, an electrolytic cell that receives and discharges water to be treated, one or more first electrodes installed in the electrolytic cell, and the first electrode and a predetermined value in the electrolytic cell A water softening device comprising one or a plurality of second electrodes arranged at intervals, and a DC power source for applying a DC voltage between the first electrode and the second electrode, wherein the first electrode and the second electrode Provided is a water softening device in which at least an electrode serving as an anode side electrode is a titanium alloy electrode containing 0.1 to 5% by mass of nickel.

  In another embodiment of the present invention, both the first electrode and the second electrode are titanium-based alloy electrodes containing 0.1 to 5% by mass of nickel, and the water softening device includes the first electrode and the second electrode. You may further provide the polarity switching apparatus which reverses the polarity of the voltage applied between the electrodes for every predetermined time.

In another embodiment of the present invention, the direct current power source may be a direct current stabilized power source capable of flowing a constant current of 0.1 to 30 A per 1 m ² of the electrode area on the anode side.

  In another embodiment of the present invention, when the water softener is an electrical conductivity meter that measures the electrical conductivity of the water to be treated, and the electrical conductivity obtained by the electrical conductivity meter is higher than a predetermined value A, When the output voltage of the DC power supply is increased to increase the current flowing between the electrodes, and the electrical conductivity obtained by the electric conductivity meter is lower than the predetermined value B, the output voltage of the DC power supply is lowered to reduce the gap between the electrodes. You may provide the electric current control apparatus which reduces the electric current which flows and makes the predetermined value A and the predetermined value B the relationship of A> = B. At this time, it is preferable that the predetermined value A of the electric conductivity of the water to be treated is 30 to 150 mS / m and the predetermined value B is 30 to 150 mS / m.

  According to the present invention, by using a titanium-based alloy containing nickel as an electrode, the amount of electrode material lost due to dielectric breakdown while maintaining the ability to remove scale components in the water to be treated equivalent to that of a pure titanium electrode Can be greatly reduced as compared with a pure titanium electrode. Therefore, according to this invention, the lifetime of an electrode can be extended significantly and the cost regarding the maintenance of a water softening apparatus (for example, electrode replacement | exchange operation | work) can be reduced significantly.

  In particular, under conditions where the current density is large, the conventional pure titanium electrode is lost in large quantities due to dielectric breakdown, whereas the nickel-containing titanium-based alloy electrode hardly decreases. Therefore, according to the present invention, it is possible to increase the speed of the water softening process using operating conditions that have been difficult to achieve with conventional water softeners, that is, operating conditions with a large current density.

  In addition, according to the present invention, the nickel-containing titanium-based alloy electrode has a lower voltage required for electrolysis than the pure titanium electrode, so that it is possible to reduce the power consumption required for the water softening treatment.

  Further, if necessary, the scale attached to the electrode surface on the cathode side can be removed maintenance-free by inverting the polarity of the voltage applied between the electrodes. In this way, it is possible to further reduce the maintenance cost of the water softening device, particularly the cost related to the scale removal work by the operator.

  In addition, when the polarity of the voltage applied between the electrodes is reversed every predetermined time, the electrode consumption due to the dielectric breakdown of the anodic oxide coating can be made the same for both opposing electrodes. It can be used more effectively.

  Further, if necessary, by performing the water softening process while monitoring the electrical conductivity of the water to be treated, it is possible to further suppress the electrode consumption while performing the water softening process efficiently. For example, when the electrical conductivity of the treated water becomes higher than a predetermined value A, it is ensured that the current necessary for promoting the water softening treatment flows in the treated water, while the electrical conductivity of the treated water. When the rate is lower than the predetermined value B, the current flowing between the electrodes can be reduced to suppress the consumption of the electrodes and reduce the power consumption.

  The above description should not be construed as disclosing all embodiments of the present invention and all advantages related to the present invention.

  Hereinafter, the present invention will be described in more detail with reference to the drawings for the purpose of illustrating representative embodiments of the present invention. However, the present invention is not limited to these embodiments.

  FIG. 1 is a schematic view of a water softening device 10 according to an embodiment of the present invention. The water softening device 10 includes an electrolytic cell 12, an electrode unit 14 accommodated in the electrolytic cell 12, a DC power supply 16 that supplies a DC current to the electrode unit 14, and a control panel 17.

  The electrolytic cell 12 is a box-shaped container, and the raw water (treated water) is indicated as “IN” via a water supply pump 20 at a position near the side of the electrolytic cell 12 at the bottom 18 of the electrolytic cell 12. A water supply port 22 is provided. The size (capacity) of the electrolytic cell 12 and the feed water pump 20 is designed according to the amount of raw water supplied.

  The electrode unit 14 includes one or more first electrodes and one or more second electrodes that are alternately arranged at a predetermined interval. The first electrode and the second electrode of the electrode unit 14 can each have any shape such as a plate shape, a round bar shape, and a square bar shape. It is preferable to use a plate-like electrode because it can be easily accommodated in a rectangular electrolytic cell that is generally used and the effective treatment area per unit mass is large. The size of the electrode unit 14 is designed according to the required water softening capacity.

  FIG. 2 shows a schematic diagram of an electrode unit 14 composed of a plurality of plate-like electrodes 24, 26 according to one embodiment of the present invention. The electrode unit 14 includes a plurality of plate-like first electrodes 24 and a plurality of plate-like second electrodes 26, and the first electrodes 24 and the second electrodes 26 are alternately arranged in parallel at predetermined intervals. ing.

  In FIG. 2, the first electrode 24 of the electrode unit 14 is connected to the positive output terminal of the DC power supply 16, and the second electrode 26 is connected to the negative output terminal of the DC power supply 16. A DC voltage is applied between the first electrode and the second electrode.

  According to the present invention, at least about 0.1 to about 5 wt.%, Preferably about 0.2 to about 3 wt.%, More preferably about 0.3 to about 3 wt. A titanium-based alloy containing 2% by mass is used. When the nickel content exceeds about 5% by mass, depending on the temperature at the time of alloying, the phase of the nickel-containing titanium alloy changes from βTi, which shows electrolysis activity, to αTi, which is suitable for water softening treatment. On the other hand, when the content of nickel is less than about 0.1% by mass, the formation of the anodized film cannot be sufficiently suppressed. The nickel-containing titanium-based alloy is preferably a titanium-nickel binary alloy containing only nickel based on titanium. When the nickel-containing titanium-based alloy electrode is used, the generation of an anodized film on the electrode surface on the anode side is suppressed, so that electrode consumption due to dielectric breakdown and peeling off of the anodized film can be reduced. Further, since the voltage drop due to the resistance of the anodic oxide coating is reduced, the voltage applied between the electrodes can be lowered, and as a result, the power consumption can be reduced.

  Titanium-nickel alloy properties (eg, phase diagrams) and methods of manufacture are described in, for example, Max Hansen and Kurt Anderko, “Constitution of Binary Alloys”, McGraw-Hill Book Co., New York (1958), with numerous references and It is also described.

  The water softening device according to another embodiment of the present invention may further include a polarity switching device (not shown) that reverses the voltage applied between the first electrode and the second electrode. The polarity switching device may include an operation mechanism that performs polarity inversion every predetermined time. In this case, since both the first electrode and the second electrode alternately function as an anode-side electrode and a cathode-side electrode, both electrodes contain about 0.1 to about 5% by mass of nickel, preferably about A titanium-based alloy electrode containing 0.2 to about 3 mass%, more preferably about 0.3 to about 2 mass% is preferable.

The direct current power source 16 can be a direct current stabilized power source capable of flowing a constant current of about 0.1 to about 30 A per 1 m ^{2 of the} electrode area on the anode side. In this case, the electrodes may be plate-shaped, and the current density distribution between the electrodes can be made more uniform by making their surfaces face each other as shown in FIG.

  Between the side portion 28 of the electrolytic cell 12 and the electrode unit 14, at a place opposite to the water supply port 22, two parallel overflow partitions 30 are slightly perpendicularly spaced apart at a predetermined interval. is set up. On the side portion 28 of the electrolytic cell 12, an outlet 32 is provided above the side where the overflow partition 30 is provided to allow the water subjected to softening treatment to flow out.

  Between the side portion 28 of the electrolytic cell 12 and the overflow partition 30, an electric conductivity meter 34 for measuring the electric conductivity of the water to be treated is installed near the outlet 32. For example, the electrical conductivity of the water to be treated measured by the electrical conductivity meter 34 may be sent as data to the control panel 17 and used to control the current supplied from the DC power supply 16. For example, according to one embodiment of the present invention, when the electrical conductivity of the water to be treated is higher than the predetermined value A, the output voltage of the DC power supply is increased to increase the current flowing between the electrodes, When the electrical conductivity is lower than a predetermined value B (A ≧ B), it is possible to control the output of the DC power supply 16 so as to reduce the current flowing between the electrodes by lowering the output voltage of the DC power supply. A current control device (not shown) can be further provided.

  A float switch 36 is installed in the upper part of the electrolytic cell 12. When the scale 70 accumulates in the filtration unit 60 of the receiving tank 44 and the resistance of water flowing out from the electrolytic cell 12 through the outlet 32 increases, the float switch 36 is activated and a signal is sent to the control panel 17. .

  A receiving tank 44 for temporarily storing water softened in the electrolytic cell 12 is provided below the electrolytic cell 12, and the outlet 32 is connected to the receiving tank 44 through an outflow pipe 46. A discharge pump 48 for discharging treated water (soft water) stored in the receiving tank 44 is installed in the vicinity of the receiving tank 44. A float switch 50 is provided in the receiving tank 44 for operating the discharge pump 48 to discharge the treated water in the receiving tank 44 when the surface of the treated water (soft water) reaches a predetermined height. Yes.

  Near the center of the bottom 18 of the electrolytic cell 12, a discharge port 52 for discharging the accumulated scale is provided. The bottom portion 18 of the electrolytic cell 12 is inclined so as to become lower toward the discharge port 52, and the inclination angle α can be generally about 25 degrees to about 35 degrees.

  A discharge device 54 is provided below the discharge port 52. The discharge device 54 includes a discharge valve and a discharge timer which are open / close devices, and the discharge timer controls the timing of discharging the accumulated scale and the open time of the discharge valve.

  The outlet side of the discharge device 54 is open without being connected to another pipe, and the scale 70 discharged together with the water in the electrolytic cell 12 is separated directly below the discharge device 54 and above the receiving tank 44. A filtering unit 60 is provided.

  The discharge capacity of the discharge device 54 is set according to the size of the electrolytic cell 12. For example, the discharge device 54 is set so that the maximum flow rate of water discharged when the water is put in the electrolytic cell 12 to a predetermined height and the discharge valve 56 is fully opened is about 30 liters / minute or more. May be.

  Next, a water softening method according to an embodiment of the present invention will be described with reference to FIG. FIG. 3 is an explanatory diagram of the control mechanism of the water softening device according to one embodiment of the present invention.

  First, the flow of water to be treated will be described. When the water supply pump 20 is operated, raw water (treated water) is supplied from the water supply port 22 of the electrolytic cell 12 to the inside of the electrolytic cell 12 through a pipe indicated as “IN” in the drawing. The supplied water to be treated immerses the electrode unit 14. The treated water (soft water) overflowing from the upper end of the lower overflow partition 30 flows between the two overflow partitions 30, flows out of the electrolytic cell 12 from the outlet 32, and is received through the outlet pipe 46. Enter tank 44.

  The float switch 50 of the receiving tank 44 is set to be switched on when the surface of the treated water (soft water) reaches a predetermined height. When the water level of the treated water (soft water) in the receiving tank 44 reaches the set height, the float switch 50 is turned on and the discharge pump 48 is activated, and the treated water (soft water) in the receiving tank 44 is “OUT” by the discharge pump 48. It is discharged through a pipe indicated as “.

  When the DC power supply 16 is turned on while the electrolytic cell 12 is filled with the water to be treated, a positive voltage is applied to the anode side electrode and a negative voltage is applied to the cathode side electrode. As a result, for example, metal ions such as calcium ions and magnesium ions and ionic silica contained in the water to be treated arranged between the electrodes are attracted to the electrode on the cathode side and reduced on the surface thereof. It deposits as a scale on or near the surface of the cathode side electrode by various mechanisms such as reaching a saturation concentration due to the high pH in the vicinity of the cathode side electrode. As a result, these ions contained in the water to be treated are gradually reduced.

  When a current is passed between the anode-side electrode and the cathode-side electrode, an anodic oxide film is formed on the anode-side electrode surface, and the resistance value on the electrode surface increases. When a certain voltage is applied, the anodized film breaks down due to dielectric breakdown, and as a result, the electrode on the anode side is consumed. Moreover, since a voltage drop occurs due to the resistance of the anodic oxide coating, it may be necessary to increase the voltage applied between the electrodes. In the present invention, at least about 0.1 to about 5% by weight of nickel based on titanium, preferably about 0.2 to about 3% by weight, more preferably about 0.3 to about 2% by weight, at least on the anode side electrode. By using a titanium-based alloy electrode containing 1%, the generation of such an anodized film can be minimized. As described above, according to the present invention, it is possible to reduce the consumption of the electrodes due to the dielectric breakdown and peeling off of the anodic oxide coating, and it is possible to reduce the voltage applied between the electrodes and reduce the power consumption.

  Nickel-containing titanium-based alloy electrodes may be used for both the cathode and anode electrodes, and the polarity of the voltage applied between the electrodes may be reversed every predetermined time. The polarity inversion of the voltage can be performed using the polarity switching device as described above. When the polarity of the applied voltage is reversed, the electrode on the cathode side, which was the cathode side electrode before the inversion, becomes the anode side electrode, and the scale is removed simultaneously with the dielectric breakdown and peeling of the anodic oxide coating as described above. It is removed from the electrode surface. Therefore, scale removal from the electrode surface can be performed while operating the water softening device, and maintenance work relating to scale removal becomes unnecessary. In addition, since electrode wear is mainly due to dielectric breakdown and peeling of the anodized film, if the polarity of the applied voltage is reversed, the wear of both opposing electrodes can be adjusted to the same level, making the electrode material more effective. Can be used.

A current of about 0.1 to about 30 A, preferably about 0.5 to about 25 A, may be passed between the electrodes per 1 m ^{2 of the} electrode area on the anode side. If the current per unit area (1 m ² ) of the electrode on the anode side, that is, the current density on the surface of the electrode on the anode side is less than about 0.1 A / m ² , the water to be treated cannot be sufficiently softened. If it exceeds m ² , the electrode corrodes and is excessively consumed. In this case, the electrode may be plate-shaped. When the electrodes are plate-shaped, the current density distribution between the electrodes becomes more uniform, and the water softening treatment can be performed uniformly throughout the electrode unit.

  The current flowing between the electrodes may be a constant current. The constant current can be supplied using a DC stabilized power supply as described above. In this way, the water softening treatment can be performed at a constant rate regardless of the amount of anodic oxide film formed on the anode-side electrode surface.

  When the water-softening treatment of the water to be treated by electrolysis is continued, scale deposits on the surface of the electrode on the cathode side or in the vicinity of the surface, and a part thereof gradually accumulates as a muddy substance on the bottom 18 of the electrolytic cell 12. In addition, as described above, when the polarity of the voltage applied between the electrodes is reversed every predetermined time, and the anodic oxide film on the surface of the electrode to which the scale is attached breaks down, the peeled scale is also the bottom 18 is deposited. The discharge valve 58 is opened at the set operation timing by the discharge timer 58 whose operation timing and release time are set in advance according to the supply speed of the water to be treated, the deposition speed of the scale, etc. Water (soft water) is discharged together with the scale deposited on the bottom 18.

  The scale in the discharged treated water (soft water) is filtered and removed by the filtration unit 60, and the treated water enters the receiving tank 44. When the opening time set in the discharge timer 58 has elapsed, the discharge valve is closed, and the electrolytic cell 12 is again filled with the water to be treated. The scale remaining in the filtration unit 60 is sequentially carried out and removed when it accumulates to some extent.

  An electrical conductivity meter 34 installed near the outlet of the electrolytic cell 12 constantly measures the electrical conductivity of the water to be treated. When the electrical conductivity of the water to be treated becomes a predetermined value or more, the alarm device 38 is activated, the alarm lamp 40 is turned on, and the alarm buzzer 42 is sounded.

  The electrical conductivity meter 34 is used to measure the electrical conductivity of the water to be treated. When the electrical conductivity of the water to be treated is higher than the predetermined value A, the current flowing between the electrodes is increased to When the conductivity is higher than the predetermined value B, the current flowing between the electrodes may be reduced. Such control can be performed by the current control device as described above. The predetermined value A and the predetermined value B have a relationship of A ≧ B. Each of the predetermined value A and the predetermined value B may be about 30 to about 150 mS / m, preferably about 50 to about 100 mS / m, while satisfying the above-described relationship (A ≧ B). If it does in this way, excessive consumption of an electrode can be controlled, performing water softening processing efficiently.

  The float switch 36 in the upper part of the electrolytic cell 12 monitors the amount of scale accumulated in the filtration unit 60 using the resistance of the water flowing out from the outflow port 32. When the water outflow resistance exceeds a predetermined value, the float switch 36 senses the rise of the water surface of the electrolytic cell 12 and sends a signal to the alarm device 38. The alarm device 38 turns on the alarm lamp 40 and sounds the alarm buzzer 42.

Example 1: Comparison of electrode materials Two pure Ti electrodes (JIS 2 types) or two Ti-Ni electrodes (Ti 99.5% -Ni 0.5%) having a size of 20 mm x 40 mm and a thickness of 2 mm were used. The electrode unit 14 was configured, and the galvanostat was used as the DC power source 16 to electrolyze the water to be treated at a constant current (current density 5 A / m ² ). The distance between the electrodes was 30 mm. As the water to be treated, 200 mL of 50 mM Na ₂ SO ₄ +10 mM NaCl aqueous solution was used. The polarity of the applied voltage was reversed every hour, and the cell voltage and the electrode potentials on both sides were measured. The results are shown in Table 1.

From the results of Table 1, the cell voltage and resistance overvoltage of the pure Ti electrode were about 10 V and about 0.2 V, respectively, and the cell voltage and resistance overvoltage of the Ti—Ni electrode were about 4 V and about 0.03 V, respectively. The resistance overvoltage derived from the anodic oxide coating (TiO ₂ ) is an order of magnitude smaller for the Ti—Ni electrode than for the pure Ti—Ni electrode. Also, the overvoltage of the anode-side electrode is significantly lower for the Ti—Ni electrode than for the Ti electrode. Therefore, when a Ti—Ni electrode is used, the overvoltage of the electrode on the anode side can be reduced at the same time, and the generation of the anodic oxide film on the electrode surface can be effectively suppressed. Moreover, since the cell voltage was about 37% of a pure Ti electrode, the power consumption can be reduced by using a Ti-Ni electrode.

Example 2: Electrolysis of circulating water in the cooling tower Two sheets of pure Ti electrodes (JIS type 2) or two Ti-Ni electrodes (Ti 99.5% -Ni 0.5%) with a size of 100 mm x 115 mm and a thickness of 2 mm The electrode unit 14 was configured using a DC stabilized power source as the DC power source 16, and electrolysis of the water to be treated was performed for 24 hours at a constant current (current density 3 A / m ² ). The distance between the electrodes was 30 mm. As treated water, 2 L of circulating water whose electric conductivity was increased to 68 mS / m in a cooling tower of 20 refrigeration tons was used. The electrical conductivity of the water to be treated and the change with time of the applied voltage between the electrodes were measured, and the water quality analysis after the water softening treatment, the measurement of the electrode consumption, and the fluorescent X-ray analysis of the precipitation components were performed. The results are shown in FIGS. 4 to 6 and Tables 2 to 3.

  As shown in FIG. 4, the amount of decrease in electrical conductivity after 24 hours of electrolysis using a Ti—Ni electrode was almost the same as that using a pure Ti electrode. However, the Ti—Ni electrode reached a constant value (about 50 mS / m) in 16 to 17 hours after the start of electrolysis, whereas the pure Ti electrode reached 23 to 24 hours to reach the same value. Is needed. From this, it can be seen that the Ti—Ni electrode is superior in the rate of electrolytic deposition of ionic components in the water to be treated. In addition, the electrical conductivity in the case of using the Ti—Ni electrode has changed slightly up and down around 50 mS / m after 16 hours from the start of electrolysis. Regarding this phenomenon, it is assumed as one of the causes that the electrolysis is inhibited by the scale deposited and adhered to the electrode surface on the cathode side. Therefore, if the scale is peeled off by reversing the polarity of the applied voltage and breaking down the anodic oxide film on the electrode surface, it is expected that the electrolysis can be continued further.

  As shown in Table 2, the removal amount of the ionic component is almost the same as the whole, although there is a difference that the pure Ti electrode is more for anions and the Ti-Ni electrode is more for cations. It was. Here, the total hardness means the total of hardness components in water, the total component amount means the sum of cations and anions, and the removal amount means the total component amount after treatment from the total component amount before treatment. It means the value obtained by subtracting the amount of ingredients.

  As shown in Table 3, the electrode consumption when using a Ti-Ni electrode was about 1/5 of that of a pure Ti electrode. From this, it can be seen that the Ti—Ni electrode has a life of at least about 5 times that of the pure Ti electrode, and the cost for the electrode material can be reduced. As shown in FIG. 5, it can be seen from the fluorescent X-ray analysis results of the components precipitated in the reaction vessel that the Ti component is hardly contained in the precipitated components when the Ti—Ni electrode is used. In addition, in FIG. 5, the mass of each ionic species in a precipitation component is shown by the percentage (mass%).

  In this example, since a constant current is supplied from the direct current stabilized power supply, the anodic oxide film produced on the electrode surface on the anode side at least partially affects the voltage between the electrodes. As shown in FIG. 6, the voltage when using a pure Ti electrode gradually increases from about 6V to about 18V, while the voltage when using a Ti-Ni electrode is about 5V to about 13.5V. It changed in. Therefore, in this example, the power consumption of the Ti—Ni electrode can be estimated to be about 75% of that of the pure Ti electrode, and the power consumption can be reduced by using the Ti—Ni electrode.

Example 3: Electrolysis under a large current density condition The electrolyzed water was electrolyzed in the same manner as in Example 2 except that a constant current having a current density of 20 A / m ² was supplied from a DC stabilized power source. Table 4 shows the results of measurement of electrode consumption.

As shown in Table 4, the Ti-Ni electrode is hardly consumed even when the current density is increased to 20 A / m ² , whereas the pure Ti electrode repeatedly causes dielectric breakdown of the anodic oxide film formed on the electrode surface on the anode side. And wear out remarkably. For this reason, the Ti—Ni electrode is particularly superior to the pure Ti electrode in terms of the life of the electrode under operating conditions with a large current density.

  The present invention includes drinking water, water for steam generators such as boilers, water for cooling molds such as injection molding devices, water used in electric heating systems such as electric water heaters, humidifiers, induction heating furnaces, Water (raw water) supplied to pure water production equipment, circulating water for cooling towers, circulating water for chillers, circulating water for cold and hot water heaters, supplementary water for heat pump water heaters, supplementary water for gas / oil water heaters, 24-hour bath Applicable to softening water, pool water, artificial pond water, etc.

It is the schematic of the water softening apparatus by one embodiment of this invention. It is the schematic of the electrode unit comprised from the some plate-shaped electrode by one embodiment of this invention. It is explanatory drawing of the control mechanism of the water softening apparatus by one embodiment of this invention. It is a graph which shows transition of the electrical conductivity at the time of using a pure titanium electrode and a titanium-nickel alloy electrode. It is a bar graph which shows the analysis result of the precipitation component at the time of using a pure titanium electrode and a titanium-nickel alloy electrode. It is a graph which shows transition of the applied voltage between electrodes at the time of using a pure titanium electrode and a titanium-nickel alloy electrode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Water softening device 12 Electrolytic tank 14 Electrode unit 16 DC power supply 17 Control panel 18 Bottom part 20 Water supply pump 22 Water supply port 24 1st electrode 26 2nd electrode 28 Side part 30 Overflow partition 32 Outlet 34 Electric conductivity meter 36 Float switch 38 Alarm device 40 Alarm lamp 42 Alarm buzzer 44 Receiving tank 46 Outflow piping 48 Discharge pump 50 Float switch 52 Discharge port 54 Discharge device 56 Discharge valve 58 Opening / closing timer 60 Filtration unit 70 Scale

Claims (11)

  Softening water to be treated, including disposing treated water between opposing electrodes, applying a DC voltage between the electrodes, and electrolytically depositing metal ions in the treated water on the cathode side electrode A method for softening water to be treated, characterized in that a titanium-based alloy electrode containing 0.1 to 5% by mass of nickel is used at least as an electrode on the anode side.   A titanium alloy electrode containing 0.1 to 5% by mass of nickel is used for both the cathode side and anode side electrodes, and the polarity of the voltage applied between the electrodes is reversed every predetermined time. The method of claim 1. 3. The method according to claim 1, wherein a current flowing between the electrodes is 0.1 to 30 A per 1 m ^{2 of} an electrode area on the anode side.   The method according to claim 1, wherein the current flowing between the electrodes is a constant current.   When the electrical conductivity of the water to be treated is higher than a predetermined value A, the current passed between the electrodes is increased. When the electrical conductivity of the water to be treated is lower than a predetermined value B, the current passed between the electrodes The method according to claim 1, wherein the predetermined value A and the predetermined value B have a relationship of A ≧ B.   The method according to claim 5, wherein the predetermined value A of the electric conductivity of the water to be treated is 30 to 150 mS / m, and the predetermined value B is 30 to 150 mS / m.   An electrolytic cell that receives and discharges water to be treated, one or more first electrodes installed in the electrolytic cell, and 1 installed in the electrolytic cell at a predetermined interval from the first electrode Or a water softening device comprising a plurality of second electrodes and a DC power source for applying a DC voltage between the first electrodes and the second electrodes, wherein at least the anode of the first electrodes and the second electrodes The water softening device, wherein the electrode serving as the side electrode is a titanium-based alloy electrode containing 0.1 to 5% by mass of nickel.   Both the first electrode and the second electrode are titanium-based alloy electrodes containing 0.1 to 5% by mass of nickel, and the polarity of the voltage applied between the first electrode and the second electrode The water softening device according to claim 7, further comprising a polarity switching device that reverses the frequency at a predetermined time. The DC power supply according to any one of claims 7 and 8, wherein the DC power supply is a DC stabilized power supply capable of supplying a constant current of 0.1 to 30 A per 1 m ² of an anode-side electrode area. The water softening device described.   An electrical conductivity meter for measuring the electrical conductivity of the water to be treated; and when the electrical conductivity obtained by the electrical conductivity meter is higher than a predetermined value A, the output voltage of the DC power supply is increased to increase the electrode If the electrical conductivity obtained by the electrical conductivity meter is lower than a predetermined value B, the output voltage of the DC power supply is lowered to reduce the current flowing between the electrodes, The water softening device according to any one of claims 7 and 8, further comprising: a current control device that sets the predetermined value A and the predetermined value B to have a relationship of A ≧ B.   The water softening device according to claim 10, wherein the predetermined value A of the electrical conductivity of the water to be treated is 30 to 150 mS / m, and the predetermined value B is 30 to 150 mS / m.

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