Water softening device

Abstract

A water softening device (100) comprises: a water softening chamber (201) that has a weakly acidic cation exchange resin (101) and generates soft water from raw water containing a hardness component; a neutralization chamber (202) that has a weakly basic anion exchange resin (102) and neutralizes soft water; a diaphragm that separates between the water softening chamber (201) and the neutralization chamber (202) so that soft water can flow therethrough; a first electrode (103) that acts as an anode during regeneration of the weakly acidic cation exchange resin (101); and a second electrode (104) that acts as a cathode during regeneration of the weakly basic anion exchange resin (102). The first electrode (103) is provided so as to be surrounded by the weakly acidic cation exchange resin (101) in the water softening chamber (201), and the second electrode (104) is provided so as to be surrounded by the weakly basic anion exchange resin (102) in the neutralization chamber (202).

Description

water softener

[0001] The present disclosure relates to a water softening device that utilizes ion exchange resins.

[0002] Currently, water softeners are widely used in areas with hard water to remove hardness components from tap water. These water softeners require periodic salt replenishment.

[0003] Furthermore, in order to solve the issues of the workload involved in salt replenishment and the performance issue of not being able to obtain soft water if salt replenishment is not carried out appropriately, a water softening technology has been developed that allows maintenance to be performed without using salt (see Patent Document 1).

[0004] The water softening system disclosed in Patent Document 1 has a basic configuration in which two types of resins, a weakly acidic cation exchange resin and a weakly basic anion exchange resin, are mixed together, and neutral soft water can be obtained by using a bipolar membrane (a membrane in which a cation exchange resin membrane and an anion exchange resin membrane are joined: hereinafter referred to as a BP membrane) on the anode side of a pair of electrodes and a cation exchange resin membrane on the cathode side.

[0005] In this conventional technology, when a certain amount of hardness ions is adsorbed onto the resin, the resin needs to be regenerated. For example, in the regeneration process described in Patent Document 1, a voltage is applied to the BP membrane and the resin chamber between the electrodes using electrodes. The BP membrane or the ion exchange resin chamber has an interface between the cation exchange resin and the anion exchange resin. When a voltage is applied to this interface, water molecules are split and H ＋ and OH － is generated. The generated H ＋ The weakly acidic cation exchange resin was － The weakly basic anion exchange resin can be regenerated by

[0006] Patent No. 6444939

[0007] However, in the technology described in Patent Document 1, the hardness ions released from the ion exchange resin are re-adsorbed onto the ion exchange resin, which tends to inhibit the reaction during resin regeneration. Therefore, in order to discharge the released hardness ions, regeneration must be performed while passing water through the resin. This water passing operation has the problem of increasing the amount of wastewater discharged during resin regeneration.

[0008] The present disclosure has been made in view of the problems inherent in the prior art, and aims to provide a water softening device that can suppress wastewater generation during regeneration and efficiently regenerate resin.

[0009] The water softening device according to the present disclosure includes a water softening chamber containing a weakly acidic cation exchange resin for producing soft water from raw water containing hardness components, a neutralization chamber containing a weakly basic anion exchange resin for neutralizing the soft water, a diaphragm for separating the water softening chamber from the neutralization chamber to allow soft water to pass through, a first electrode acting as an anode during regeneration of the weakly acidic cation exchange resin, and a second electrode acting as a cathode during regeneration of the weakly basic anion exchange resin. The first electrode is disposed in the water softening chamber and surrounded by the weakly acidic cation exchange resin, and the second electrode is disposed in the neutralization chamber and surrounded by the weakly basic anion exchange resin.

[0010] According to the present disclosure, it is possible to provide a water softening device that can suppress wastewater during regeneration and efficiently regenerate resin.

[0011] FIG. 1 is a perspective view of a water softener according to a first embodiment of the present disclosure. FIG. 2 is a cross-sectional view of the same water softener. FIG. 3 is a diagram including a formula illustrating the principle of the same water softener. FIG. 4 is a diagram illustrating the hardness of softened water in the water softening process before and after regeneration in Example 1. FIG. 5 is a diagram illustrating the change in pH over time in the water softening chamber and the neutralization chamber during regeneration in Example 1. FIG. 6 is a diagram illustrating the change in the number of moles of each ion over time during regeneration in Example 1. FIG. 7 is a schematic diagram of a water softener according to a second embodiment of the present disclosure. FIG. 8 is a perspective view of a water softener according to the second embodiment. FIG. 9 is a cross-sectional view of a water softener according to the second embodiment. FIG. 10 is a diagram including a formula illustrating the principle of the water softener according to the second embodiment. FIG. 11 is a diagram illustrating the change over time in the rate of hydrogen ion consumption by a weakly acidic cation exchange resin during the regeneration process. FIG. 12 is a schematic diagram of a water softener according to a fourth embodiment. FIG. 13 is a schematic diagram of a water softener according to a fifth embodiment. FIG. 14 is a schematic diagram of a water softener according to a sixth embodiment. FIG. 15 is a schematic diagram of a water softener according to a seventh embodiment of the present disclosure. FIG. 16 is a schematic diagram of a water softener according to an eighth embodiment of the present disclosure. FIG. 17 is a perspective view of a water softener according to the eighth embodiment. FIG. 18 is a cross-sectional view of a water softener according to the eighth embodiment. FIG. 19 is a diagram including an equation illustrating the principle of the water softener according to the eighth embodiment. FIG. 20 is a diagram illustrating the time change in the rate of hydrogen ion consumption by a weakly acidic cation exchange resin during a regeneration process. FIG. 21 is a perspective view of an example of a water softener according to the eighth embodiment. FIG. 22 is a diagram illustrating the relationship between the amount of wastewater and hardness one hour after the start of regeneration in an example of the eighth embodiment. FIG. 23 is a schematic diagram of a water softener according to a ninth embodiment of the present disclosure. FIG. 24 is a perspective view of a water softener according to the ninth embodiment. FIG. 25 is a cross-sectional view of a water softener according to the ninth embodiment. FIG. 26 is a cross-sectional view of the water softener according to the ninth embodiment, taken along the line A-A' in FIG. 25. FIG. 27 is a diagram including an equation illustrating the principle of the water softener according to the ninth embodiment. FIG. 28 is a graph showing the change over time in the rate of hydrogen ion consumption by the weakly acidic cation exchange resin during the regeneration process.

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that each of the following embodiments is an example of the present disclosure and does not limit the technical scope of the present disclosure. Furthermore, each drawing used in each embodiment is a schematic drawing, and the ratios of the sizes and thicknesses of the components in each drawing do not necessarily reflect the actual dimensional ratios.

[0013] First Embodiment A water softening device 100 according to a first embodiment of the present disclosure will be described with reference to FIGS. 1 and 2 .

[0014] Fig. 1 is a perspective view showing the configuration of a water softening device 100 according to a first embodiment of the present disclosure. Fig. 2 is a cross-sectional view showing the configuration of the water softening device 100 according to the first embodiment of the present disclosure. Note that Figs. 1 and 2 conceptually show each element of the water softening device 100. Also, Fig. 1 omits the weakly acidic cation exchange resin 101 and the weakly basic anion exchange resin 102.

[0015] The water softening device 100 is a device that produces neutral soft water from raw water that contains hardness components and is supplied from the outside. The raw water is water (water to be treated) that is introduced into the water softening device 100 from a water conveying section 107 (described later), and is, for example, well water or tap water. The raw water contains hardness components (calcium ions or magnesium ions).

[0016] By performing a water softening process to soften raw water using the water softening device 100, neutral soft water with reduced hardness can be obtained from raw water with high hardness, and soft water can be used even in areas where the raw water has high hardness.

[0017] After performing the water softening process for a certain period of time, the water softening device 100 also performs a regeneration process to regenerate the weakly acidic cation exchange resin 101 and the weakly basic anion exchange resin 102. Details of the water softening process and the regeneration process will be described later.

[0018] Specifically, as shown in FIG. 1 , the water softening device 100 includes a casing 203, a water conveying section inlet 111, a water conveying section 107, a water softening chamber 201, a neutralization chamber 202, a water conveying section 108, and a water conveying section outlet 110.

[0019] The casing 203 is a hollow cylindrical member, and in its hollow space, in order from the side closer to the central axis I connecting the top and bottom surfaces of the casing 203 toward the outer periphery, there are a water conveying section 107, a water softening chamber 201, a neutralization chamber 202, and a water supply section 108.

[0020] A water conveying section inlet 111 is provided at the center of the lower surface of the casing 203, i.e., on the central axis I. A water conveying section outlet 110 is provided at the center of the upper surface of the casing 203, i.e., on the central axis I. The central axis I of the casing 203 coincides with the central axes of the water conveying section 107, the water softening chamber 201, the neutralization chamber 202, and the water conveying section 108.

[0021] Inside the casing 203, the raw water is softened and the ion exchange resin is regenerated.

[0022] The water conveying section inlet 111 is provided on the bottom surface of the casing 203 and supplies raw water to the water conveying section 107. The central axis of the water conveying section inlet 111 coincides with the central axis I of the casing 203.

[0023] The water conveying section 107 is a cylindrical member, and its lower end is connected to the water conveying section inlet 111. The water conveying section 107 conveys raw water into the water softening device 100 and supplies it to the water softening chamber 201. The water conveying section 107 can be a tube such as a pipe having an internal space.

[0024] The water conveying section 107 is configured to allow raw water introduced into the water softening device 100 to flow uniformly through the water softening chamber 201 and the neutralization chamber 202. Specifically, the water conveying section 107 is provided in the center of the casing 203, and the outer periphery of the water conveying section 107 is in contact with the water softening chamber 201; in other words, the water conveying section 107 is located on the central axis I.

[0025] Furthermore, the water conveying section 107 is provided from the bottom to the top of the water softening chamber 201 and the neutralization chamber 202, more precisely from the bottom end to the top end. The length of the part of the water conveying section 107 that can supply raw water to the water softening chamber 201 and the neutralization chamber 202 is equal to the height of the water softening chamber 201 and the neutralization chamber 202.

[0026] The water conveying section 107 has a plurality of holes on its side surface, through which raw water is delivered from the central axis I of the casing 203 toward the periphery, i.e., toward the water softening chamber 201. Furthermore, it is preferable that the plurality of holes be uniformly arranged in the circumferential direction on the side surface of the water conveying section 107. With this configuration, raw water introduced into the device can be uniformly delivered to the water softening chamber 201 and the neutralization chamber 202. Therefore, the raw water is evenly supplied to the particles of the weakly acidic cation exchange resin 101 packed in the water softening chamber 201 and the particles of the weakly basic anion exchange resin 102 packed in the neutralization chamber 202. This allows efficient use of the weakly acidic cation exchange resin 101 and the weakly basic anion exchange resin 102 as a whole.

[0027] The plurality of holes formed on the side surface of the water conducting section 107 are smaller in diameter than the particle diameter of the weakly acidic cation exchange resin particles. Since the lower limit of the particle diameter of the weakly acidic cation exchange resin is approximately 0.3 mm, the diameter of the holes formed on the surface of the water conducting section 107 is smaller than that. This prevents the ion exchange resin from leaking out of the water softening chamber 201 without impeding the permeation of water.

[0028] The water softening chamber 201 is a cylindrical space that is provided inside the casing 203 on the outer circumferential side of the water conducting section 107 with respect to the central axis I of the casing 203, and contains the weakly acidic cation exchange resin 101. The central axis of the water softening chamber 201 coincides with the central axis I of the casing 203. The water softening chamber 201 is in contact with the water conducting section 107 on the inner surface side of the cylindrical shape, and in contact with the inner diaphragm 105 on the outer surface side. In other words, the water softening chamber 201 surrounds the water conducting section 107 and is surrounded by the inner diaphragm 105.

[0029] The top surface of the water softening chamber 201 is in contact with the lid 112, and is configured to prevent water from flowing out. This is to prevent water from flowing out from the top surface of the water softening chamber 201 and bypassing the weakly acidic cation exchange resin 101 and the weakly basic anion exchange resin 102 during the water softening process. Details of the lid 112 will be described later.

[0030] The water softening chamber 201 is filled with weakly acidic cation exchange resin 101. This weakly acidic cation exchange resin 101 produces soft water from raw water containing hardness components. In detail, in the water softening chamber 201, the hardness components contained in the raw water are adsorbed onto the weakly acidic cation exchange resin 101, and soft water containing protons released in place of the hardness components is produced.

[0031] The weakly acidic cation exchange resin 101 is an ion exchange resin having a carboxyl group, and for example, one having a methacrylic acid skeleton or one having an acrylic acid skeleton can be used. In this embodiment, a resin having an acrylic acid skeleton is used as the weakly acidic cation exchange resin 101.

[0032] The volume of the weakly acidic cation exchange resin 101 packed in the water softening chamber 201 is smaller than the volume of the weakly basic anion exchange resin 102 packed in the neutralization chamber 202, which will be described later. This is because the water softening chamber 201 is located on the inner periphery of the neutralization chamber 202 and its volume is smaller than the volume of the neutralization chamber 202.

[0033] The water softening chamber 201 is provided with a first electrode 103 .

[0034] The first electrode 103 is not energized during the water softening process and serves as an anode during the regeneration process of the weakly acidic cation exchange resin 101. The first electrode 103 is surrounded by the weakly acidic cation exchange resin 101 in the water softening chamber 201. Here, "surrounded" refers to a state in which the surface of the first electrode 103 is in contact with the surface of the weakly acidic cation exchange resin 101 from the top to the bottom around the entire circumference. However, the weakly acidic cation exchange resin 101 is usually spherical, and a water passage for the raw water must be secured. Therefore, the "first electrode 103 is surrounded by the weakly acidic cation exchange resin 101" does not necessarily mean that the weakly acidic cation exchange resin 101 is in complete contact with the surface of the first electrode 103, but also means that the weakly acidic cation exchange resin 101 is partially in contact with the surface of the first electrode 103 around the entire circumference.

[0035] The upper end of the first electrode 103 is located below the water surface in the water softening chamber 201 at the start of the regeneration process, thereby forming a first space 204 above the upper end of the first electrode 103 in the water softening chamber 201.

[0036] The weakly acidic cation exchange resin 101 fills the water softening chamber 201. That is, the weakly acidic cation exchange resin 101 is filled around the first electrode 103 and in the first space 204.

[0037] In order to smoothly regenerate the weakly acidic cation exchange resin 101, it is preferable that the water surface at the start of the regeneration process be near the top surface of the water softening chamber 201, and in this embodiment, the water surface at the start of the regeneration process is coincident with the top surface of the water softening chamber 201.

[0038] The first electrode 103 is configured so that when comparing the distance S from the water surface to the upper end of the first electrode 103 at the start of the regeneration process with the distance T from the bottom surface of the water softening chamber 201 to the lower end of the first electrode 103, the distance T is shorter than the distance S.

[0039] As a result, during the regeneration process described below, bubbles generated from the first electrode 103 cause the weakly acidic cation exchange resin 101 to flow, thereby improving the regeneration efficiency. In this embodiment, the lower end of the first electrode 103 is in contact with the bottom surface of the water softening chamber 201, and T=0, so T is not shown in Figure 2.

[0040] A noble metal or a noble metal alloy can be used as the material of the first electrode 103. This is because the noble metal contained in the first electrode 103 acts as a catalyst for water electrolysis and is not eluted even under acidic conditions. Examples of noble metal materials include platinum, iridium, and ruthenium.

[0041] Examples of the electrode form include a noble metal wire electrode alone, an electrode in which a noble metal wire is wound around the outer periphery of a support, or a mesh-shaped noble metal electrode. It is also possible to use a metal rod other than a noble metal, such as titanium (Ti), as the support, with a noble metal coated on the surface. However, since the presence of an interface between different metals is likely to cause deterioration due to the interface, it is preferable to use a noble metal or noble metal alloy alone.

[0042] The neutralization chamber 202 is a cylindrical space provided inside the casing 203 on the outer circumferential side of the water softening chamber 201 with respect to the central axis I of the casing 203, and contains the weak basic anion exchange resin 102. The central axis of the neutralization chamber 202 coincides with the central axis I of the casing 203. The inner surface of the neutralization chamber 202 contacts the outer surface of the inner circumferential diaphragm 105, and the outer surface of the cylindrical neutralization chamber 202 contacts the inner surface of the outer circumferential diaphragm 106. In other words, the neutralization chamber 202 surrounds the inner circumferential diaphragm 105 and is surrounded by the outer circumferential diaphragm 106. The neutralization chamber 202 is filled with the weak basic anion exchange resin 102. Details of the inner circumferential diaphragm 105 and the outer circumferential diaphragm 106 will be described later.

[0043] The upper surface of the neutralization chamber 202 is in contact with the lid 112, similar to the water softening chamber 201, and is configured to prevent water from flowing out. This is to prevent water from flowing out from the upper surface of the neutralization chamber 202 and bypassing the weakly acidic cation exchange resin 101 and the weakly basic anion exchange resin 102 during the water softening process.

[0044] The weakly basic anion exchange resin 102 may be a resin having tertiary amine and quaternary amine functional groups, and in this embodiment, a resin having a higher proportion of tertiary amine than quaternary amine is used.

[0045] The volume of the weakly basic anion exchange resin 102 packed in the neutralization chamber 202 is larger than the volume of the weakly acidic cation exchange resin 101 packed in the water softening chamber 201. This is because the neutralization chamber 202 is located on the outer periphery of the water softening chamber 201, and the volume of the neutralization chamber 202 is larger than the volume of the water softening chamber 201.

[0046] In the neutralization chamber 202, soft water with a neutral pH is produced by neutralizing the soft water produced in the water softening chamber 201. The neutralization chamber 202 is provided with a second electrode 104.

[0047] The second electrode 104 is not energized during the water softening process, but acts as a cathode during the regeneration process of the weakly basic anion exchange resin 102. The second electrode 104 is surrounded by the weakly basic anion exchange resin 102 within the neutralization chamber 202.

[0048] Here, "surrounded" refers to a state in which the surface of the second electrode 104 is in contact with the surface of the weakly basic anion exchange resin 102 from the top to the bottom around the entire periphery. However, like the weakly acidic cation exchange resin 101, the weakly basic anion exchange resin 102 usually has a spherical shape, and a water passage for the raw water (strictly speaking, acidic soft water) must be secured. Therefore, the term "second electrode 104 is surrounded by the weakly basic anion exchange resin 102" also applies to a state in which the weakly basic anion exchange resin 102 is not in complete contact with the surface of the second electrode 104, but is arranged around the entire periphery in a state of partial contact.

[0049] The upper end of the second electrode 104 is located below the water surface in the neutralization chamber 202 at the start of a regeneration process (regeneration process of the weakly basic anion exchange resin 102), which will be described later. As a result, a second space 205 is formed above the upper end of the second electrode 104 in the neutralization chamber 202.

[0050] The weakly basic anion exchange resin 102 fills the neutralization chamber 202. That is, the weakly basic anion exchange resin 102 is filled around the second electrode 104 and in the second space 205.

[0051] In addition, in order to smoothly regenerate the weakly basic anion exchange resin 102, it is preferable that the water level at the start of the regeneration process be near the upper surface of the neutralization chamber 202, and in this embodiment, the water level at the start of the regeneration process is coincident with the upper surface of the neutralization chamber 202.

[0052] The second electrode 104 is configured so that when comparing the distance V from the water surface at the start of the regeneration process to the upper end of the second electrode 104 with the distance W from the bottom surface of the neutralization chamber 202 to the lower end of the second electrode 104, the distance W is shorter than the distance V.

[0053] As a result, during the regeneration treatment described below, bubbles generated from the second electrode 104 cause the weakly basic anion exchange resin 102 to flow, thereby improving the regeneration efficiency. In this embodiment, the lower end of the second electrode 104 is in contact with the bottom surface of the neutralization chamber 202, and W=0, so W is not shown in Figure 2.

[0054] A noble metal or a noble metal alloy can be used as the material of the second electrode 104. This is because the noble metal contained in the second electrode 104 acts as a catalyst for water electrolysis and is not eluted even under acidic conditions. Examples of noble metal materials include platinum, iridium, and ruthenium.

[0055] The first electrode 103 is provided as a pair with the second electrode 104 , and the pair of first electrode 103 and second electrode 104 is provided on the same radius of the casing 203 .

[0056] This allows the distance between the first electrode 103 and the second electrode 104 to be shorter than when the pair of electrodes are not on the same radius, and makes it possible to suppress an increase in power consumption due to an increase in voltage.

[0057] In this embodiment, two pairs of electrodes (first electrode 103a and second electrode 104a, and first electrode 103b and second electrode 104b) are arranged on the same diameter of the cylindrical casing 203 (on the same straight line passing through the center when viewed in a plane).

[0058] This allows the two pairs of electrodes to be evenly arranged within the casing 203, thereby preventing bias in the location of hydrogen ions or hydroxide ions generated from the electrodes during regeneration, thereby enabling efficient regeneration of the weakly acidic cation exchange resin 101 and the weakly basic anion exchange resin 102.

[0059] The water softening chamber 201 and the neutralization chamber 202 are separated by an inner periphery-side diaphragm 105. That is, the weakly acidic cation exchange resin 101 and the weakly basic anion exchange resin 102 are separated by the inner periphery-side diaphragm 105.

[0060] The inner diaphragm 105 is a cylindrical membrane having water permeability. The inner surface of the inner diaphragm 105 covers the outer surface of the water softening chamber 201 and is in contact with the outer surface of the water softening chamber 201. In addition, the outer surface of the inner diaphragm 105 covers the inner surface of the neutralization chamber 202 and is in contact with the inner surface of the neutralization chamber 202.

[0061] As a result, the inner diaphragm 105 separates the water softening chamber 201 from the neutralization chamber 202 while allowing the acidic soft water produced in the water softening chamber 201 to pass through. Note that "covering" only requires that the inner diaphragm 105 be positioned around the object, and does not necessarily require that the object be completely enclosed.

[0062] The inner diaphragm 105 has pores smaller than the particle diameters of the weakly acidic cation exchange resin 101 and the weakly basic anion exchange resin 102 so as not to impede water permeation and to prevent outflow of the weakly acidic cation exchange resin 101 and the weakly basic anion exchange resin 102. Similar to the lower limit of the particle diameter of the weakly acidic cation exchange resin 101 described above, the lower limit of the particle diameter of the weakly basic anion exchange resin 102 is also around 0.3 mm, and therefore the pore diameter of the inner diaphragm 105 is smaller than that.

[0063] A resin mesh sheet can be used as the inner diaphragm 105. The material of the inner diaphragm 105 is preferably a heat-resistant and chemical-resistant material, such as a fluorine-based resin, a polyethylene resin, a polypropylene resin, a polyvinyl chloride resin, or a polyvinylidene fluoride resin.

[0064] Furthermore, a structure having through holes, slits, or the like can also be used as the inner diaphragm 105. In order to allow water to flow evenly from the water softening chamber 201 to the neutralization chamber 202 during the water softening process, it is preferable that the through holes or slits are evenly arranged on the surface of the inner diaphragm 105. The opening area of ​​each of the through holes or slits is smaller than the particle size of the weakly acidic cation exchange resin 101 and the weakly basic anion exchange resin 102, and is preferably an area that does not hinder the flow of water during the water softening process.

[0065] The neutralization chamber 202 and a water supply section 108 (described later) are separated by an outer peripheral diaphragm 106 .

[0066] The outer periphery-side diaphragm 106 is a cylindrical membrane having water permeability. The inner surface of the outer periphery-side diaphragm 106 covers the outer surface of the neutralization chamber 202 and is in contact with the outer surface of the neutralization chamber 202. In addition, the outer surface of the outer periphery-side diaphragm 106 covers the inner surface of the water supply section 108 and is in contact with the inner surface of the water supply section 108.

[0067] This allows the soft water generated in the neutralization chamber to pass through while separating the neutralization chamber 202 from the water supply unit 108. Note that "covering" only requires that the cover be positioned around the object, and does not necessarily require that the cover completely enclose the object.

[0068] The outer periphery diaphragm 106 has pores smaller than the particle size of the weakly basic anion exchange resin 102 so as not to impede water permeation and to prevent outflow of the weakly basic anion exchange resin 102. Since the lower limit of the particle size of the weakly basic anion exchange resin 102 is around 0.3 mm, the pore size of the outer periphery diaphragm 106 is smaller than that.

[0069] A resin mesh sheet can be used as the outer periphery diaphragm 106. The material of the outer periphery diaphragm 106 is preferably a heat-resistant and chemical-resistant material, such as a fluorine-based resin, a polyethylene resin, a polypropylene resin, a polyvinyl chloride resin, or a polyvinylidene fluoride resin.

[0070] Furthermore, a structure having through holes or slits may be used as the outer periphery diaphragm 106. In order to allow water to flow evenly from the neutralization chamber 202 to the water supply section 108 during the water softening process, the through holes or slits are preferably evenly arranged on the surface of the outer periphery diaphragm 106. The opening area of ​​the through holes or slits is preferably smaller than the particle diameters of the weakly acidic cation exchange resin 101 and the weakly basic anion exchange resin 102, and is preferably an area that does not impede the flow of water during the water softening process.

[0071] The upper surfaces of the water conveying section 107 , the water softening chamber 201 , the inner diaphragm 105 , the neutralization chamber 202 , and the outer diaphragm 106 are covered by a lid section 112 .

[0072] The lid 112 has a water-impermeable structure and can be made of, for example, a plate-shaped resin. The lid 112 contacts and covers the upper surfaces of the water conveying section 107, the water softening chamber 201, the inner diaphragm 105, the neutralization chamber 202, and the outer diaphragm 106, thereby separating the upper surfaces from the water conveying section 108, which will be described later.

[0073] This makes it possible to prevent water from flowing out from each upper surface into the water supply section 108. In other words, the cover section 112 makes it possible to form a water flow in which raw water flowing in from the water conveying section inlet 111 passes through the water conveying section 107, the water softening chamber 201, the inner periphery-side diaphragm 105, and the neutralization chamber 202, and is sent out from the side surface of the outer periphery-side diaphragm 106 into the side space 108a of the water supply section 108.

[0074] The water supply unit 108 supplies the soft water sent out from the neutralization chamber 202 to a water supply unit outlet 110 provided above the upper part of the neutralization chamber 202. The central axis of the water supply unit 108 coincides with the central axis I of the casing 203.

[0075] The water supply unit 108 is provided in the casing 203 and includes a side space 108a and an upper space 108b.

[0076] The side space 108a is a cylindrical space that is provided on the outer circumferential side of the neutralization chamber 202 with respect to the central axis I of the casing 203 and surrounds the neutralization chamber 202. The cylindrical inner surface of the side space 108a contacts the outer surface of the outer-circumferential diaphragm 106, and the cylindrical outer surface of the side space 108a contacts the inner surface of the casing 203. In other words, the side space 108a is a space that is provided between the inner surface of the casing 203 and the outer surface of the outer-circumferential diaphragm 106.

[0077] In a direction parallel to the central axis I, the total length of the side space 108a is longer than the total length of the neutralization chamber 202, and when the side space 108a and the bottom surfaces of the neutralization chamber 202 are aligned on the same plane, the top surface of the side space 108a protrudes above the top surface of the neutralization chamber 202.

[0078] The upper space 108b is a cylindrical space provided above the top surfaces of the water conveying section 107, the water softening chamber 201, the inner diaphragm 105, the neutralization chamber 202, and the outer diaphragm 106. The cylindrical top surface of the upper space 108b contacts the inner top wall of the casing 203, and the cylindrical bottom surface of the upper space 108b contacts the outer top wall of the lid section 112. The cylindrical outer surface of the upper space 108b contacts the inner surface of the side space 108a.

[0079] The side space 108a and the upper space 108b are virtually separated by a virtual boundary line 113. The boundary line 113 is a virtual line of a cylinder whose central axis coincides with the central axis I, and is located vertically above the outer periphery-side diaphragm 106.

[0080] The water supply unit outlet 110 is provided on the top surface of the casing 203 and discharges water from the upper space 108b to the outside of the water softening device 100. The central axis of the water supply unit outlet 110 coincides with the central axis I of the casing 203.

[0081] The air vent valve 109 is provided above the water supply section 108 and serves to discharge gases such as oxygen and hydrogen generated in the water softening chamber 201 and the neutralization chamber 202 during the regeneration process to the outside of the water softening device 100 .

[0082] The water softening device 100 has the above configuration.

[0083] Next, the two processes (water softening process and regeneration process) of the water softening device 100 will be described.

[0084] First, the operation of the water softening device 100 in the water softening process and the principles of the water softening process will be described.

[0085] In the water softening device 100, raw water flows from the outside into the lower part of the water conveying part 107 through the water conveying part inlet 111. The flowing raw water is sent from the lower part to the upper part of the water conveying part 107 and flows out in the radial direction of the casing 203 from holes provided in the side wall of the water conveying part 107. In other words, the raw water is sent out from the holes in the water conveying part 107 to the water softening chamber 201.

[0086] The raw water sent to the water softening chamber 201 is softened by the weakly acidic cation exchange resin 101 filled inside the water softening chamber 201. In detail, hardness components (calcium ions or magnesium ions) in the raw water are exchanged with hydrogen ions adsorbed on the weakly acidic cation exchange resin 101, and the raw water becomes acidic soft water containing hydrogen ions.

[0087] The acidic softened water produced in the water softening chamber 201 passes through the inner diaphragm 105, which is a water-permeable membrane, and flows into the neutralization chamber 202 where it is neutralized. Specifically, hydrogen ions in the softened water are removed from the softened water by being adsorbed onto the weakly basic anion exchange resin 102, and neutral softened water is produced. During this neutralization reaction, anions such as sulfate ions contained in the softened water are also adsorbed onto the weakly basic anion exchange resin 102.

[0088] The neutral soft water produced in the neutralization chamber 202 passes through the outer peripheral diaphragm 106, which is a water-permeable membrane, and flows into the water supply section 108.

[0089] The softened water that flows into the water supply unit 108 flows upward in the side space 108a and into the upper space 108b. The softened water that flows into the upper space 108b flows toward the center of the upper space 108b and is taken out from the water supply unit outlet 110 provided in the center of the top surface of the water softening device 100.

[0090] In this way, the raw water is softened in the water softening process.

[0091] For efficient water softening, it is important to ensure sufficient contact between the ion exchange resin particles and the hard water or acidic softened water. Therefore, a water softener using an ion exchange resin must be designed to allow water to flow uniformly within the water softener. If the water does not flow uniformly, it will tend to flow in a path that allows it to flow more easily, resulting in the water passing through the water softening chamber 201 or the neutralization chamber 202 without sufficient contact with the ion exchange resin. As a result, the water removed from the water softener 100 may not be softened or may remain acidic.

[0092] On the other hand, in the water softening apparatus 100 of this embodiment, raw water is introduced into the apparatus from the bottom of the casing 203, passes through the water conveyance section 108, and is taken out as softened water from the water conveyance section outlet 110 provided at the top. This method of conveying water from the bottom to the top is called an upward flow. In the case of an upward flow, the ion exchange resin particles can flow easily, so there is little pressure loss when the water is passed through the water softening chamber 201 and the neutralization chamber 202, and the water flows easily.

[0093] Furthermore, since the water softening device 100 is cylindrical, the distance from the central water conveying section 107 to the outer water conveying section 108 is equal, and the water pressure acting on the water conveying section 108 is uniform.

[0094] Furthermore, the water softening device 100 is configured so that water flows out from a water supply outlet 110 provided in the center of the top surface of the water softening device 100 .

[0095] The three features of the water softening device 100, namely, the upward flow, the cylindrical shape, and the location of the water conveying section outlet 110, reduce the variation in the flow path length when the water passes through the water softening device 100, and allow the water to flow uniformly within the space of the water softening device 100. This allows the ion exchange resin to come into sufficient contact with the raw water or acidic softened water, enabling efficient water softening.

[0096] The weakly acidic cation exchange resin 101 filled in the water softening chamber 201 is an ion exchange resin having a carboxyl group, and a resin having a methacrylic acid skeleton or an acrylic acid skeleton can be used. Of these, it is preferable to use a resin having an acrylic acid skeleton. In the case of a methacrylic acid skeleton, the pKa (acid dissociation constant), which is a physical property of the resin, is generally around 5. On the other hand, the pKa of an acrylic acid skeleton is around 3. In the water softening process, H in the weakly acidic cation exchange resin ＋ are exchanged with cations such as hardness ions and released into the water, and when the pH of the water in the water softening chamber 201 becomes equal to or lower than the pKa, the COO － H ＋ Therefore, an acrylic acid-based skeleton with a low pKa can exchange more cations than a methacrylic acid-based skeleton.

[0097] Furthermore, it is preferable to use a resin with a higher proportion of tertiary amine functional groups than quaternary amine functional groups as the weakly basic anion exchange resin 102 filled in the neutralization chamber 202. The pKb of quaternary amines is approximately 11, which is higher than the pKb of tertiary amines, which is approximately 8. The pKb of the amine groups is the upper limit of the pH of the softened water after passing acidic soft water through the weakly basic anion exchange resin 102. This is because the amine groups, which are ion exchange groups in the weakly basic anion exchange resin 102, cease to function when the pH of the solution exceeds the pKb. The upper limit of the pH of tap water is set at 8.5 according to water quality standards. When the weakly basic anion exchange resin 102 contains a high proportion of quaternary amines, the pH of the softened water tends to be more alkaline than when the proportion of quaternary amines is low. In other words, when the proportion of quaternary amines is high, the pH of the softened water increases above 8.5, potentially failing to meet water quality standards. Therefore, in order to keep the pH of soft water within the water quality standard, it is preferable that the proportion of tertiary amines is high.

[0098] In order to obtain soft water that satisfies the water quality standards, the volume of the weakly basic anion exchange resin 102 used must be equal to or greater than the volume of the weakly acidic cation exchange resin 101. The reason for this will be explained from the perspective of the ion exchange reaction rates of the two resins.

[0099] During the water softening process, in order to obtain soft water that meets water quality standards, the hardness of the raw water must be reduced to 50 mg / L or less while the raw water passes through the softening chamber 201, and the pH of the raw water must be returned from around 3 to neutral while passing through the neutralization chamber 202.

[0100] The amount of cations removed in the water softening chamber 201 and the amount of anions and H removed in the neutralization chamber 202 ＋ The amount of removal is determined by the rate of the ion exchange reaction and the time the water passes through the ion exchange resin. As can be seen from the reactions during the water softening process shown in equations (1) and (2) in Figure 3, the rate of the ion exchange reaction depends on (a) the ion exchange group concentration, (b) the ion concentration in hard water (Ca ２＋ , or Cl － The time it takes for water to pass through the resin is determined by (d) the resin volume, and (e) the water flow rate.

[0101] Among these five parameters, (b) the ion concentration in hard water and (e) the water flow rate cannot be controlled. Because (a) the ion exchange group concentration and (c) the rate constant of the ion exchange reaction are determined by the type and particle size of the resin, (d) the resin volume can be adjusted to achieve the required water quality standards during the water softening process.

[0102] The volume ratio of each resin is determined from the viewpoints of (a) the ion exchange group concentration and (c) the rate constant of the ion exchange reaction. (a) The ion exchange group concentration can be compared in terms of the ion exchange equivalent (eq / L) of the ion exchange resin, i.e., the number of moles of ion exchange groups per volume of resin.

[0103] The ion exchange equivalent capacity of the weakly acidic cation exchange resin 101 is about 4 eq / L, while the ion exchange equivalent capacity of the weakly basic anion exchange resin 102 is at most 2 eq / L. Therefore, (a) the ion exchange group concentration is higher in the weakly acidic cation exchange resin 101. Furthermore, (c) the reaction rate constant of the weakly basic anion exchange resin 102 is higher because the particle diameter of the weakly basic anion exchange resin 102 is very uniform and the average particle diameter is small. Therefore, (c) the reaction rate constant of the weakly basic anion exchange resin is higher, but (a) the ion exchange group concentration of the weakly basic anion exchange resin 102 is about half that of the weakly acidic cation exchange resin 101.

[0104] Considering (a) and (c), the reaction rate of the weakly basic anion exchange resin 102 is slightly lower than that of the weakly acidic cation exchange resin 101. Therefore, in terms of (d) resin volume, the volume of the weakly basic anion exchange resin 102 needs to be equal to or larger than the volume of the weakly acidic cation exchange resin 101.

[0105] In this water softening process, if the amount of hardness ions adsorbed onto the weakly acidic cation exchange resin 101 or the amount of anions adsorbed onto the weakly basic anion exchange resin 102 increases, the resin's water softening performance will decrease, and therefore a regeneration process will be required.

[0106] In the past, when using a BP membrane to regenerate a water softener containing a mixture of weakly acidic cation exchange resins and weakly basic anion exchange resins, the desorbed hardness ions would re-adsorb onto the ion exchange resin, hindering the resin regeneration reaction. Therefore, to prevent the re-adsorption of the desorbed hardness ions, it was necessary to discharge the water containing the desorbed hardness ions from the device, and regeneration had to be performed while water was being passed through the device. This water-passing operation resulted in a problem of a large amount of wastewater being discharged during the regeneration process. The cause of this problem is explained below.

[0107] In the regeneration process of the weakly acidic cation exchange resin and the weakly basic anion exchange resin, the reactions shown in formulas (3) and (4) in FIG. 3 occur.

[0108] Since both regeneration reactions are reversible, Ca ２＋or Cl － Not only the forward reaction in which OH is desorbed, but also the reverse reaction in which each ion is adsorbed occurs. － The affinity with Cl － It is overwhelmingly higher than other anions such as Cl. － On the other hand, the carboxyl group of the weakly acidic cation exchange resin 101 is adsorbed by Ca. ２＋ Therefore, the affinity for Ca is relatively high. ２＋ The reverse reaction rate of adsorption is faster than that of weakly basic anion exchange resins, and a certain amount of Ca ２＋ A re-adsorption reaction occurs.

[0109] As can be seen from equation (3), the rate of the forward reaction of the weakly acidic cation exchange resin is determined by H ＋ and Ca ２＋ The concentration of H ＋ High concentration of Ca ２＋ When H is low, the speed of the rightward regeneration reaction is high. ＋ The concentration is low, Ca ２＋ Under high Ca conditions, the rate of rightward regeneration slowed and the rate of leftward Ca increased. ２＋ The rate of the re-adsorption reaction increases, making it difficult to regenerate the resin.

[0110] In the regeneration process described in Patent Document 1, H is generated at the interface between the BP membrane and the ion exchange resin. ＋ and OH － is generated at the same time. ＋ and OH － The original purpose of the generation is to regenerate the resin, but the generated H ＋ and OH － is also consumed by side reactions other than the resin regeneration reaction. ＋ and OH － and the neutralization reaction in which H is recombined with H by weakly basic anion exchange resin. ＋ There is an adsorption reaction. ＋ and OH － In Patent Document 1, since multiple reactions consuming hydroxybenzoates occur, the pH in the resin tank during the regeneration step becomes nearly neutral.

[0111] When the pH during the regeneration process becomes near neutral, as explained in the mechanism of the regeneration reaction, Ca ２＋ Under conditions where Ca is high, the regeneration of the weakly acidic cation exchange resin is difficult to proceed. ２＋ Ca desorbed from the weakly acidic cation exchange resin to reduce the concentration ２＋ Therefore, a drainage operation is required to discharge the wastewater from the system.

[0112] The amount of water discharged during this draining operation can be estimated as follows: In the case of a domestic water softener, a volume of about 20 L of ion exchange resin is generally required. Given the void space in the tank where the resin is filled and the volume of the resin, the amount of water in the tank will be roughly the same as the amount of resin. If water stagnates in the tank, the calcium ion and magnesium ion concentrations will quickly increase, so it is desirable to replace the entire amount of water in the tank at least once every few tens of minutes.

[0113] For example, if the water in the tank is replaced once every 10 minutes, water must be continuously flowing at 2 L / min. The hydrogen ions and hydroxide ions that can be generated using the BP membrane method are each in the order of a few mmol / min. Meanwhile, under standard usage conditions, the calcium ions and magnesium ions that are desorbed from the resin are on the order of a few mol (if 1,000 L of raw water with a hardness of 250 mg / L is softened per day, the hardness adsorbed by the resin will be 2.5 mol), so regeneration takes several hours. Even if the regeneration time were three hours, the amount of wastewater would be enormous: 2 L / min x 3 hr x 60 min / hr = 360 L.

[0114] Therefore, there is a demand for a water softening device that reduces the amount of wastewater discharged or eliminates the need for wastewater discharge.

[0115] The operation of the water softening device 100 during the regeneration process and the principle of the regeneration process will be described below with reference to FIG.

[0116] In the regeneration process, first, raw water flows from the raw water supply source into the water conveying section 107 via the water conveying section inlet 111 and is filled into the water softening chamber 201 and the neutralization chamber 202. Next, electricity is passed through each electrode so that the first electrode 103 surrounded by the weakly acidic cation exchange resin 101 has a higher potential than the second electrode 104 surrounded by the weakly basic anion exchange resin 102.

[0117] As a result, a reaction that produces hydrogen ions (see formula (5) in FIG. 3) occurs at the first electrode 103, which is an anode, and a reaction that produces hydroxide ions (see formula (6) in FIG. 3) occurs at the second electrode 104, which is a cathode. In other words, hydrogen ions are produced in the water softening chamber 201, and hydroxide ions are produced in the neutralization chamber 202.

[0118] The weakly acidic cation exchange resin 101, which has adsorbed hardness components during the water softening process, undergoes an exchange reaction between the hardness components and the hydrogen ions when exposed to hydrogen ions, thereby regenerating the weakly acidic cation exchange resin 101.

[0119] Furthermore, when the weakly basic anion exchange resin 102 to which anions have been adsorbed in the water softening process is exposed to hydroxide ions, an exchange reaction between the adsorbed anions and the hydroxide ions occurs, thereby regenerating the weakly basic anion exchange resin 102.

[0120] In this manner, the weakly acidic cation exchange resin 101 and the weakly basic anion exchange resin 102 are regenerated in the regeneration process.

[0121] In this embodiment, the first electrode 103 and the second electrode 104 are provided in two separate compartments, the water softening chamber 201 and the neutralization chamber 202, surrounded by ion exchange resin. This allows hydrogen ions and hydroxide ions to be generated separately, and both ions are quickly used to regenerate the ion exchange resin. If the generated hydrogen ions and hydroxide ions were to come into contact, a neutralization reaction would occur, consuming both ions. However, in the configuration of this embodiment, the neutralization reaction due to contact between hydrogen ions and hydroxide ions is unlikely to occur. This increases the hydrogen ion concentration in equation (3) of FIG. 3 , enabling the regeneration reaction of the weakly acidic cation exchange resin 101 to proceed even in the presence of calcium ions. This reduces the frequency or even eliminates the need for drainage, thereby reducing the amount of water discharged, in order to reduce the calcium ion concentration in the water softening device 100 during the regeneration process.

[0122] Furthermore, since the generated hydrogen ions and hydroxide ions are immediately consumed in the resin regeneration reaction, the pH near the first electrode 103 does not drop significantly. Therefore, when platinum electrodes are used for the first electrode 103 and the second electrode 104, the electrode life can be extended. This is because the oxide film that naturally forms on the electrode surface can be prevented from being dissolved by hydrogen ions. If an oxide film is present, the platinum dissolution reaction (for example, when platinum is dissolved in Cl) can be prevented. － This prevents the reaction with platinum ions to produce platinum chloride ions, thereby increasing the electrode life.

[0123] In this embodiment, the first electrode 103 contacts the bottom surface of the water softening chamber 201, and the second electrode 104 contacts the bottom surface of the neutralization chamber 202. In other words, because the electrodes are located near the resin with a high concentration of adsorbed ions, the generated hydrogen ions and hydroxide ions are quickly used in the resin regeneration reaction. Therefore, hydrogen ions and hydroxide ions are less likely to be consumed by the neutralization reaction, and the regeneration process can be carried out efficiently.

[0124] In detail, in the regeneration process, the resin regeneration reaction is represented by the formulas (3) and (4) in FIG. 3 and H ＋ and OH－ The production reactions (5) and (6) occur simultaneously. ＋ and OH － It is desirable that H is immediately consumed in the resin regeneration reaction. ＋ and OH － It is also consumed by neutralization reactions between H ＋ and OH － The diffusion rate of H is faster than that of other ionic species, so if it is not consumed in the resin regeneration reaction, the neutralization reaction will occur easily. ＋ and OH － When this loss occurs, the number of moles of H in excess of the stoichiometrically required number determined by equations (3) and (4) is increased. ＋ and OH － Therefore, power consumption increases because H ＋ and OH － It is necessary to make the rate of the resin regeneration reaction faster than the rate of the production reaction.

[0125] The rate increase of the resin regeneration reaction is － ) ２ Ca ２＋ , and R ３ -NH ＋ Cl － This can be achieved by increasing the concentration of the resin. ＋ and OH － In the regeneration process, the formation reaction and the regeneration reaction simultaneously occur. － ) ２ Ca ２＋ , and R ３ -NH ＋ Cl － To increase the concentration of cations or anions, it is effective to place the electrode near the resin that has adsorbed more cations or anions during the water softening process.

[0126] In the water softening chamber 201, the closer to the bottom in the height direction, the greater the (R-COO － ) ２ Ca ２＋ and (R-COO － ) ２ Mg ２＋In the neutralization chamber 202, the concentration of R ３ -NH ＋ Cl － and (R ３ -NH ＋ ) ２ SO ４ ２－ Therefore, by having the first electrode 103 in contact with the bottom surface of the water softening chamber 201 and the second electrode 104 in contact with the bottom surface of the neutralization chamber 202, the regeneration process can be carried out efficiently.

[0127] EXAMPLES Hereinafter, the present disclosure will be described in detail using examples with reference to FIGS.

[0128] A water softening test and a regeneration test were carried out using the water softening device 100 shown in Figure 1. In the water softening test, raw water was passed through a water conveyance pipe, and the hardness of the water taken out of the water softening device 100 was measured. Hard water with a hardness of 310 mg / L was used as the raw water.

[0129] The regeneration test was carried out as follows. The platinum electrode on the weakly acidic cation exchange resin 101 side was connected to the positive electrode of a DC power supply, and the platinum electrode on the weakly basic anion exchange resin 102 side was connected to the negative electrode. A current of 5 A was applied from the DC power supply for 6 hours. The water in the water softening device 100 was not replaced during regeneration, and regeneration was carried out without draining. A small amount of water was taken out of the water softening chamber 201 and the neutralization chamber 202 during regeneration, and the pH and ion concentration were measured.

[0130] After the first water softening test, a regeneration test was carried out, and then another water softening test was carried out.

[0131] FIG. 4 shows the change in water hardness from 5 minutes to 40 minutes after the start of water flow in the first and second water softening tests. It can be seen that by passing water through the water softener 100, the hardness decreased from 310 mg / L to 50 mg / L or less. The second water softening process, performed after the regeneration process, also reduced the hardness to the soft water level. When raw water was passed through the water softener 100 for 40 minutes, the high hardness of 310 mg / L was successfully reduced to approximately 20 mg / L. This indicates that the water flow within the water softener 100 is uniform, or in other words, that all of the resin particles in the water softener 100 are being utilized.

[0132] FIG. 5 shows the pH change in the water softening compartment 201 and the neutralization compartment 202 during the regeneration process.

[0133] It can be seen that the neutralization chamber 202 becomes neutral to weakly alkaline with a pH of 7 to 9, and the water softening chamber 201 becomes acidic with a pH of 2.3 to 3.3. Although the diaphragm used allows water to easily pass through, the water softening chamber 201 is maintained acidic, and the neutralization chamber 202 is maintained alkaline. In other words, the weakly acidic cation exchange resin 101 is H ＋ The weakly basic anion exchange resin 102 is dissolved in OH. － It is clear that individuals can be individually exposed to

[0134] Furthermore, although the pH of the water softening chamber 201 is biased towards the acidic side, it is still weakly acidic at around pH 2.5, and although the pH of the water neutralization chamber 202 is biased towards the alkaline side, it is still weakly alkaline at around pH 9. ＋ and OH － The rate at which the electrode consumes H ＋ and OH － If the rate at which the water is generated is slower than the rate at which the water is generated, the pH in the neutralization chamber 202 rises sharply, becoming a strong alkali of pH 12 or more, and the pH in the water softening chamber 201 decreases, becoming a strong acid of pH 2 or less. ＋ or OH － Therefore, as shown in Figure 5, the pH does not suddenly become acidic or alkaline, which indicates that H generated from the electrode ＋ and OH－ It can be said that Ca is immediately consumed in the resin regeneration reaction. ２＋ or Cl － By placing the electrodes near the resin that has absorbed a large amount of CO, it is possible to control the resin regeneration reaction so that it becomes rate-determining.

[0135] FIG. 6 shows the Cl － ions, Mg ２＋ ions, and Ca ２＋ This is a diagram showing the change in the number of moles of ions. － The ions are released from the weakly basic anion exchange resin 102, and Mg ２＋ ions and Ca ２＋ The ions are released from the weakly acidic cation exchange resin 101. The number of moles of each ion increased with increasing regeneration time. Moreover, the number of moles of each ion remained almost unchanged between 5.5 hours and 6 hours.

[0136] As shown in Figure 6, the increase in the number of moles of ions with increasing regeneration time indicates that cations are released from the weakly acidic cation exchange resin 101 and anions are released from the weakly basic anion exchange resin 102, indicating that resin regeneration is progressing. Furthermore, even when no wastewater is discharged during the regeneration process, ion release occurs through regeneration, demonstrating that the configuration of this embodiment can reduce the amount of wastewater discharged during regeneration. Furthermore, the fact that the amount of ions remains almost unchanged at the end of regeneration and that the hardness of the softened water after regeneration (Figure 4) is approximately the same as before regeneration indicate that the resin can be regenerated to a level that allows water softening using the water softening device 100 of this embodiment.

[0137] The present disclosure has been described above based on the embodiments. These embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of each component or each treatment process, and that such modifications are also within the scope of the present disclosure.

[0138] (Modification) In the first embodiment, the water softener 100 is cylindrical, and therefore the two diaphragms (the inner diaphragm 105 and the outer diaphragm 106) are distinguished as being on the inner periphery side and the outer periphery side, but the two diaphragms are not necessarily located on the inner periphery side and the outer periphery side, respectively, depending on the shape of the water softener 100. The names inner periphery side diaphragm and outer periphery side diaphragm are merely names used to distinguish between the two types of diaphragms, and do not indicate the positions of the inner periphery side diaphragm 105 and the outer periphery side diaphragm 106.

[0139] In the water softening device 100 according to the first embodiment, the casing 203, the water conveying section 107, the water softening chamber 201, the inner periphery-side diaphragm 105, the neutralization chamber 202, and the outer periphery-side diaphragm 106 are cylindrical in shape, but are not limited thereto. For example, they may be rectangular tubes.

[0140] In the water softening device 100 according to the first embodiment, a pipe-like tube with tiny holes on its surface is used as the water conveying section 107, but this is not limitative. For example, it is also possible to make the center of the water softening chamber 201 a gap, and use this gap as the water conveying section 107. This also produces the same effect.

[0141] In the water softening device 100 according to the first embodiment, a container with a cylindrically hollowed-out center is used as the water softening chamber 201, but this is not limitative. For example, the space partitioned by the outer periphery of the water conveying section 107 and the inner periphery-side diaphragm 105 can also be used as the water softening chamber 201. This also provides the same effect.

[0142] In the water softening apparatus 100 according to the first embodiment, a container with a cylindrically hollowed-out center is used as the neutralization chamber 202, but this is not limitative. For example, the space partitioned by the inner diaphragm 105 and the outer diaphragm 106 can also be used as the neutralization chamber 202. This also provides the same effect.

[0143] In the water softening device 100 according to the first embodiment, the lid 112 is a plate-shaped resin provided across the upper surfaces of the water conveying section 107, the water softening chamber 201, the inner diaphragm 105, the neutralization chamber 202, and the outer diaphragm 106, but this is not limiting. The lid 112 may have any structure as long as it prevents water from leaking from the upper surfaces of the water conveying section 107, the water softening chamber 201, the inner diaphragm 105, the neutralization chamber 202, and the outer diaphragm 106 to the water supply section 108. For example, the lid 112 may be configured to individually cover the upper surfaces of the water conveying section 107, the water softening chamber 201, the inner diaphragm 105, the neutralization chamber 202, and the outer diaphragm 106. This structure also prevents water from leaking from the upper surfaces to the water supply section 108.

[0144] In the water softening apparatus 100 according to the first embodiment, the volume of the weakly basic anion exchange resin 102 is equal to or greater than that of the weakly acidic cation exchange resin 101. However, it is preferable to change the volume ratio of the weakly basic anion exchange resin 102 to the weakly acidic cation exchange resin 101 depending on the quality of the raw water and the target amount of raw water to be treated. When the raw water has low hardness or the amount of raw water to be treated is small, the pH of the softened water can be maintained near neutral even if the volumes of the weakly basic anion exchange resin 102 and the weakly acidic cation exchange resin 101 are the same. On the other hand, when the raw water has high hardness or the amount of raw water to be treated is large, the pH may drop to 6 or below. Therefore, it is preferable to make the volume of the weakly basic anion exchange resin 102 larger than that of the weakly acidic cation exchange resin 101.

[0145] In the water softening device 100 according to the first embodiment, the first electrode 103 and the second electrode 104 can be arranged in any position as long as the distance from the water surface to the top of the electrode at the start of the regeneration process is longer than the distance from the bottom of each chamber to the bottom of the electrode. ＋ and OH － The loss due to the neutralization reaction of H is suppressed. ＋ and OH － can be used without any particular limitation on the arrangement as long as it can be consumed in the ion exchange resin regeneration reaction.

[0146] However, from the viewpoint of reducing costs, it is preferable that the first electrode 103 be disposed anywhere in the height direction from the bottom surface filled with the weakly acidic cation exchange resin 101 to a position halfway up the top surface filled with the weakly acidic cation exchange resin 101. Also, from the viewpoint of reducing costs, it is preferable that the second electrode 104 be disposed anywhere in the height direction from the bottom surface filled with the weakly basic anion exchange resin 102 to a position halfway up the top surface filled with the weakly basic anion exchange resin 102.

[0147] Although the water softener 100 according to the first embodiment has been described as being used alone, it is also possible to connect a plurality of water softeners 100 in parallel and use the system as a system consisting of two or more parallel-connected water softeners 100. By connecting water softeners 100 in parallel, the flow rate per tank can be reduced. When the flow rate is reduced, the time that raw water passes through the water softener 100 increases, and the amount of hardness removed in the water softening process increases.

[0148] It is also possible to connect multiple water softeners 100 in series and use the system as a system consisting of two or more water softeners 100 connected in series. Connecting water softeners 100 in series increases the number of theoretical plates of the ion exchange resin layers. This increases the ion exchange capacity of the ion exchange resin that can be used. Specifically, when the ion exchange capacity of two ion exchange resin tanks connected in series is compared to that of a single ion exchange resin tank under the same total amount of ion exchange resin, the system consisting of two series tanks has about five times the capacity of the single tank.

[0149] Furthermore, the water softeners 100 can be connected in series and parallel to form a system with four or more tanks of the water softeners 100. This connection method results in the highest amount of hardness removal in the water softening process compared to the above-mentioned parallel-only and series-only configurations.

[0150] (Embodiment 2) In the technology described in Patent Document 1, hardness ions released from the ion exchange resin are re-adsorbed onto the ion exchange resin, which tends to inhibit the reaction during resin regeneration. Therefore, in order to discharge the released hardness ions, regeneration must be performed while passing water through the resin. This water passing operation has the problem of increasing the amount of wastewater discharged during resin regeneration.

[0151] The present disclosure has been made in view of the problems inherent in the prior art, and aims to provide a water softening device that can suppress wastewater generation during regeneration and efficiently regenerate resin.

[0152] The water softening device according to the present disclosure includes a water softening chamber containing a weakly acidic cation exchange resin for producing soft water from raw water containing hardness components, a neutralization chamber containing a weakly basic anion exchange resin for neutralizing the soft water, a diaphragm separating the water softening chamber from the neutralization chamber to allow soft water to pass through, a first electrode acting as an anode during regeneration of the weakly acidic cation exchange resin, a second electrode acting as a cathode during regeneration of the weakly basic anion exchange resin, and a control unit for controlling the regeneration of the weakly acidic cation exchange resin and the weakly basic anion exchange resin. The first electrode is disposed in the water softening chamber and surrounded by the weakly acidic cation exchange resin, and the second electrode is disposed in the neutralization chamber and surrounded by the weakly basic anion exchange resin. The control unit executes the following processes: a water softening process in which water to be treated is introduced from the bottom of the water softening chamber and passed through the water softening chamber and then the neutralization chamber to obtain soft water; a regeneration process in which current is applied to the first electrode and the second electrode to generate hydrogen ions from the first electrode by water electrolysis, generate hydroxide ions from the second electrode, regenerate the weakly acidic cation exchange resin with the generated hydrogen ions, and regenerate the weakly basic anion exchange resin with the generated hydroxide ions; a cleaning process in which cations released from the weakly acidic cation exchange resin by the regeneration process are discharged from the water softening chamber and anions released from the weakly basic anion exchange resin are discharged from the neutralization chamber; and an electrode cleaning process in which, during or after the regeneration process, the first electrode is connected to the negative electrode and the second electrode is connected to the positive electrode to dissolve solids that have adhered to the surface of the second electrode during the regeneration process.

[0153] According to the present disclosure, it is possible to provide a water softening device that can suppress wastewater during regeneration and efficiently regenerate resin.

[0154] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that each of the following embodiments is an example of the present disclosure and does not limit the technical scope of the present disclosure. Furthermore, each drawing used in each embodiment is a schematic drawing, and the ratios of the sizes and thicknesses of the components in each drawing do not necessarily reflect the actual dimensional ratios.

[0155] A water softening device 1100 according to a second embodiment of the present disclosure will be described with reference to FIGS. 7, 8, and 9. FIG.

[0156] Fig. 7 is a schematic diagram showing the configuration of a water softening device 1100 according to a second embodiment of the present disclosure. Fig. 8 is a perspective view showing the configuration of the water softening device 1100 according to the second embodiment of the present disclosure. Fig. 9 is a cross-sectional view showing the configuration of the water softening device 1100 according to the second embodiment of the present disclosure. Note that Figs. 7 to 9 conceptually show each element of the water softening device 1100. Furthermore, Fig. 8 omits the weakly acidic cation exchange resin 1213 and the weakly basic anion exchange resin 1214.

[0157] The water softening device 1100 is a device that produces neutral soft water from raw water containing hardness components supplied from the outside. The raw water is water (water to be treated) introduced into the water softening device 1100 from a raw water supply pipe 1104 (described later), and is, for example, well water or tap water. The raw water contains hardness components (calcium ions or magnesium ions).

[0158] By performing a water softening process to soften raw water using the water softening device 1100, neutral soft water with reduced hardness can be obtained from raw water with high hardness, and soft water can be used even in areas where the raw water has high hardness.

[0159] After carrying out the water softening process for a certain period of time, the water softening device 1100 carries out a regeneration process to regenerate the weakly acidic cation exchange resin 1213 and the weakly basic anion exchange resin 1214. Details of the water softening process and the regeneration process will be described later.

[0160] As shown in FIG. 7, the water softening device 1100 includes a raw water supply pipe 1104 , a casing 1109 , a softened water supply pipe 1105 , a drain pipe 1107 , and a control unit 1110 .

[0161] The raw water supply pipe 1104 is a pipe that connects a source of raw water, such as a water supply, to the water conveyance section inlet 1207, and is provided with a raw water conductivity measuring section 1101 on its flow path.

[0162] The raw water conductivity measuring unit 1101 calculates the total ion concentration of the raw water flowing into the raw water supply pipe 1104. The calculated total ion concentration information of the raw water is sent to the control unit 1110, which will be described later.

[0163] The casing 1109 is a hollow cylindrical member, and the raw water is softened and the ion exchange resin is regenerated within the casing 1109 .

[0164] As shown in Figures 8 and 9, the hollow space of the casing 1109 is provided with a water conveying section 1203, a water softening chamber 1209, a neutralization chamber 1210, and a water supply section 1204, in that order from the side closer to the central axis I connecting the top and bottom surfaces of the casing 1109 toward the outer periphery.

[0165] A water conveying section inlet 1207 is provided at the center of the lower surface of the casing 1109, i.e., on the central axis I. A water supply section outlet 1206 is provided at the center of the upper surface of the casing 1109, i.e., on the central axis I. The central axis I of the casing 1109 coincides with the central axes of the water conveying section 1203, the water softening chamber 1209, the neutralization chamber 1210, and the water supply section 1204.

[0166] The water conveying section inlet 1207 is provided on the bottom surface of the casing 1109 and supplies raw water to the water conveying section 1203. The central axis of the water conveying section inlet 1207 coincides with the central axis I of the casing 1109.

[0167] The water conveying section 1203 is a cylindrical member, and its lower end is connected to a water conveying section inlet 1207. The water conveying section 1203 conveys raw water into the water softening device 1100 and supplies it to the water softening chamber 1209. The water conveying section 1203 can be a tube such as a pipe having an internal space.

[0168] The water conveying section 1203 is configured to allow raw water introduced into the water softening device 1100 to flow uniformly through the water softening chamber 1209 and the neutralization chamber 1210. Specifically, the water conveying section 1203 is provided in the center of the casing 1109, and the outer periphery of the water conveying section 1203 is in contact with the water softening chamber 1209;

[0169] Furthermore, the water conveying section 1203 is provided from the bottom to the top of the water softening chamber 1209 and the neutralization chamber 1210, more precisely from the bottom to the top. The length of the part of the water conveying section 1203 that can supply raw water to the water softening chamber 1209 and the neutralization chamber 1210 is equal to the height of the water softening chamber 1209 and the neutralization chamber 1210.

[0170] The water conveying section 1203 has a plurality of holes on its side surface, through which raw water is delivered from the central axis I of the casing 1109 toward the periphery, i.e., toward the water softening chamber 1209. Furthermore, the plurality of holes are preferably uniformly arranged in the circumferential direction on the side surface of the water conveying section 1203. With this configuration, raw water introduced into the device can be uniformly delivered to the water softening chamber 1209 and the neutralization chamber 1210. Therefore, the raw water is evenly supplied to the particles of weakly acidic cation exchange resin 1213 packed in the water softening chamber 1209 and the particles of weakly basic anion exchange resin 1214 packed in the neutralization chamber 1210. This allows efficient use of the weakly acidic cation exchange resin 1213 and the weakly basic anion exchange resin 1214 as a whole.

[0171] The plurality of holes formed on the side surface of the water conducting section 1203 are smaller in diameter than the particles of the weakly acidic cation exchange resin 1213. Since the lower limit of the particle diameter of the weakly acidic cation exchange resin 1213 is around 0.3 mm, the diameter of the holes formed on the surface of the water conducting section 1203 is smaller than that. This prevents the ion exchange resin from leaking out of the water softening chamber 1209 without impeding the permeation of water.

[0172] The water softening chamber 1209 is a cylindrical space (first space 1211) that is provided inside the casing 1109 on the outer circumferential side of the water conducting section 1203 with respect to the central axis I of the casing 1109 and that contains a weakly acidic cation exchange resin 1213. The central axis of the water softening chamber 1209 coincides with the central axis I of the casing 1109. The water softening chamber 1209 is in contact with the water conducting section 1203 on its inner surface, in contact with an inner diaphragm 1215, which is a cylindrical membrane that is water permeable, on its outer surface, and in contact with the lid section 1208 on its top surface. The water softening chamber 1209 is provided with a plurality of first electrodes 1201 (first electrode 1201a and first electrode 1201b are exemplified).

[0173] The first electrode 1201 is not energized during the water softening process and serves as an anode in the regeneration process of the weakly acidic cation exchange resin 1213. The first electrode 1201 is surrounded by the weakly acidic cation exchange resin 1213 in the water softening chamber 1209. Here, "surrounded" refers to a state in which the surface of the first electrode 1201 is in contact with the surface of the weakly acidic cation exchange resin 1213 from top to bottom around the entire circumference. However, the weakly acidic cation exchange resin 1213 is usually spherical, and a water passage for the raw water must be secured. Therefore, the "first electrode 1201 is surrounded by the weakly acidic cation exchange resin 1213" does not necessarily mean that the weakly acidic cation exchange resin 1213 is in complete contact with the surface of the first electrode 1201, but rather a state in which the weakly acidic cation exchange resin 1213 is in partial contact with the surface of the first electrode 1201 around the entire circumference also falls under the category of "first electrode 1201 is surrounded by the weakly acidic cation exchange resin 1213."

[0174] The neutralization chamber 1210 is a cylindrical space (second space 1212) located inside the casing 1109 on the outer circumferential side of the water softening chamber 1209 with respect to the central axis I of the casing 1109, and contains a weakly basic anion exchange resin 1214. The central axis of the neutralization chamber 1210 coincides with the central axis I of the casing 1109. The neutralization chamber 1210 is in contact with the outer surface of the inner circumferential diaphragm 1215 on the inner surface side of the cylindrical shape, in contact with the inner surface of the outer circumferential diaphragm 1216, which is a cylindrical membrane having water permeability, on the outer surface side of the cylindrical shape, and in contact with the lid 1208 on the upper surface. The neutralization chamber 1210 is provided with a plurality of second electrodes 1202 (second electrode 1202a and second electrode 1202b are exemplified).

[0175] The second electrode 1202 is not energized during the water softening process, and acts as a cathode during the regeneration process of the weakly basic anion exchange resin 1214. The second electrode 1202 is surrounded by the weakly basic anion exchange resin 1214 within the neutralization chamber 1210.

[0176] Here, "surrounded" refers to a state in which the surface of the second electrode 1202 is in contact with the surface of the weakly basic anion exchange resin 1214 from the top to the bottom around the entire periphery. However, like the weakly acidic cation exchange resin 1213, the weakly basic anion exchange resin 1214 usually has a spherical shape and needs to have a water passage for the raw water (strictly speaking, acidic soft water). Therefore, the term "second electrode 1202 is surrounded by the weakly basic anion exchange resin 1214" also applies to a state in which the weakly basic anion exchange resin 1214 is not in complete contact with the surface of the second electrode 1202 but is arranged around the entire periphery in a state of partial contact.

[0177] The water softening device 1100 includes an electrode cleaning circuit (a circuit including a power source) that connects the first electrode 1201 to the negative electrode and the second electrode 1202 to the positive electrode.

[0178] The water supply unit 1204 supplies the soft water sent out from the neutralization chamber 1210 to a water supply unit outlet 1206 provided above the top of the neutralization chamber 1210. The central axis of the water supply unit 1204 coincides with the central axis I of the casing 1109.

[0179] The water supply section 1204 is provided with an air vent valve 1205 for venting air from inside the casing 1109 .

[0180] The water conveyance unit outlet 1206 is provided on the top surface of the casing 1109 and discharges the water in the water conveyance unit 1204 to the outside of the water softening device 1100. The central axis of the water conveyance unit outlet 1206 coincides with the central axis I of the casing 1109.

[0181] 7 , the soft water supply pipe 1105 is a pipe that connects the water supply unit outlet 1206 with the destination of the soft water supply, and is provided with a soft water conductivity measuring unit 1102 and a water volume measuring unit 1103 on its flow path. A drain pipe 1107 branches off from the soft water supply pipe 1105 midway along its flow path. A soft water supply pipe on-off valve 1106 is provided on the soft water supply pipe 1105 downstream of the branch point with the drain pipe 1107.

[0182] The soft water conductivity measuring unit 1102 calculates the total ion concentration of the soft water sent out from the water sending unit outlet 1206. The calculated total ion concentration information of the soft water is sent to the control unit 1110, which will be described later.

[0183] Any device capable of measuring the resistance of water can be used as the raw water conductivity measuring unit 1101 and the soft water conductivity measuring unit 1102 without any problems.

[0184] The drain pipe 1107 is a pipe branched from the soft water supply pipe 1105 upstream of the soft water supply pipe on-off valve 1106, and is a pipe for draining water during the regeneration process. The drain pipe 1107 is provided with a drain pipe on-off valve 1108 on its flow path.

[0185] The water volume measuring unit 1103 is a component that measures the volume of water passed through the water softening device 1100, and may use a device such as a water meter that can measure the cumulative volume of water. The measured water volume information is sent to the control unit 1110, which will be described later.

[0186] The control unit 1110 controls the execution of each of the processes described below: a water softening process, a regeneration process, a drainage process, a cleaning process, and an electrode cleaning process.

[0187] The control unit 1110 can be realized as hardware by elements and mechanical devices such as a computer CPU (Central Processing Unit), and as software by a computer program, etc. Therefore, these functional blocks can be realized in various forms by combining hardware and software.

[0188] The control unit 1110 includes an adsorption amount estimation unit 1111 , a storage unit 1112 , and a timer unit 1113 .

[0189] The adsorption amount estimation unit 1111 calculates the total amount of ions adsorbed in the water softening device 1100 using the total ion concentration of the raw water calculated by the raw water conductivity measurement unit 1101, the total ion concentration of the softened water calculated by the softened water conductivity measurement unit 1102, and the total amount of water passing through measured by the water volume measurement unit 1103.

[0190] The storage unit 1112 stores the various pieces of information transmitted to the control unit 1110 and the various pieces of information calculated by the control unit 1110 .

[0191] The timer 1113 measures the time elapsed since the start of the regeneration process, more specifically, the time elapsed since the start of energization of the first electrode 1201 and the second electrode 1202 .

[0192] The water softening device 1100 has the above configuration.

[0193] Next, the processes (water softening process, regeneration process, cleaning process, and electrode cleaning process) performed by the water softening device 1100 will be described.

[0194] First, the operation of the water softening device 1100 in the water softening process and the principle of the water softening process will be described.

[0195] In the water softening device 1100, raw water flows from the outside into the lower part of the water conveying part 1203 through the water conveying part inlet 1207. The flowing raw water is sent from the lower part to the upper part of the water conveying part 1203 and flows out in the radial direction of the casing 1109 from holes provided in the side wall of the water conveying part 1203. In other words, the raw water is sent out from the holes in the water conveying part 1203 to the water softening chamber 1209.

[0196] The raw water sent to the water softening chamber 1209 is softened by the weakly acidic cation exchange resin 1213 filled inside the water softening chamber 1209. In detail, hardness components (calcium ions or magnesium ions) in the raw water are exchanged with hydrogen ions adsorbed on the weakly acidic cation exchange resin 1213, and the raw water becomes acidic soft water containing hydrogen ions.

[0197] The acidic softened water produced in the water softening chamber 1209 passes through the inner diaphragm 1215, which is a water-permeable membrane, and flows into the neutralization chamber 1210, where it is neutralized. Specifically, hydrogen ions in the softened water are removed from the softened water by being adsorbed onto the weakly basic anion exchange resin 1214, and neutral softened water is produced. During this neutralization reaction, anions such as sulfate ions contained in the softened water are also adsorbed onto the weakly basic anion exchange resin 1214.

[0198] The neutral soft water produced in the neutralization chamber 1210 passes through the outer peripheral diaphragm 1216 , which is a water-permeable membrane, and flows into the water supply section 1204 .

[0199] The softened water that flows into the water supply section 1204 flows upward, rises in the side space 1204a of the water supply section 1204, and flows into the upper space 1204b of the water supply section 1204. The softened water that flows into the upper space 1204b flows toward the center of the upper space 1204b and is taken out from the water supply section outlet 1206 provided in the center of the top surface of the water softening device 1100.

[0200] In this way, the raw water is softened in the water softening process.

[0201] In the water softening process, if the amount of hardness ions adsorbed onto the weakly acidic cation exchange resin 1213 or the amount of anions adsorbed onto the weakly basic anion exchange resin 1214 increases, the resin's water softening performance will decrease, and a regeneration process will be required.

[0202] In the regeneration process, first, raw water flows from a raw water supply source into the water conveying section 1203 via the water conveying section inlet 1207, and is sent to the water softening chamber 1209 and the neutralization chamber 1210. Next, electricity is passed through each electrode so that the first electrode 1201 surrounded by the weakly acidic cation exchange resin 1213 has a higher potential than the second electrode 1202 surrounded by the weakly basic anion exchange resin 1214.

[0203] As a result, a reaction that produces hydrogen ions (see formula (15) in FIG. 10) occurs at the first electrode 1201, which is an anode, and a reaction that produces hydroxide ions (see formula (16) in FIG. 10) occurs at the second electrode 1202, which is a cathode. In other words, hydrogen ions are produced in the water softening chamber 1209, and hydroxide ions are produced in the neutralization chamber 1210.

[0204] When the weakly acidic cation exchange resin 1213, which has absorbed hardness components during the water softening process, is exposed to hydrogen ions, an exchange reaction between the hardness components and the hydrogen ions occurs, thereby regenerating the weakly acidic cation exchange resin 1213.

[0205] Furthermore, when the weakly basic anion exchange resin 1214 to which anions have been adsorbed in the water softening process is exposed to hydroxide ions, an exchange reaction between the adsorbed anions and the hydroxide ions occurs, thereby regenerating the weakly basic anion exchange resin 1214.

[0206] In this manner, the weakly acidic cation exchange resin 1213 and the weakly basic anion exchange resin 1214 are regenerated in the regeneration process.

[0207] In the regeneration process, the water softening device 1100 sets the regeneration time based on the conductivity of the raw water or softened water before and after passing through the casing 1109 or the amount of water that has passed through the casing 1109 .

[0208] Specifically, at the start of the water softening process, raw water conductivity measuring unit 1101 is activated and measures the conductivity of raw water flowing through raw water supply pipe 1104. Also, soft water conductivity measuring unit 1102 is activated and measures the conductivity of soft water flowing through soft water supply pipe 1105. Furthermore, water volume measuring unit 1103 measures the volume of water that has flowed through casing 1109. The measured raw water conductivity, soft water conductivity, and water volume are transmitted to control unit 1110 and stored in memory unit 1112.

[0209] The ions removed in the water softening chamber 1209 are mainly Mg ２＋ , and Ca ２＋ The ions removed in the neutralization chamber 1210 are mainly HCO ３ － , Cl－ , and S.O. ４ ２－ are anions. According to the principle of electroneutrality, the number of moles of cations adsorbed in the water softening chamber 1209 is equal to the number of moles of anions adsorbed in the neutralization chamber 1210. Therefore, the difference between the conductivity measured by the raw water conductivity measuring unit 1101 and the conductivity measured by the softened water conductivity measuring unit 1102 is derived from the total amount of Mg salts and Ca salts removed by the water softening device 1100. In this way, because the conductivity difference is the value of the removed ion concentration, it is possible to respond to changes in the water quality of the raw water and softened water, and the amount of adsorption can be calculated with high accuracy.

[0210] The adsorption amount estimation unit 1111 estimates the amount of ions adsorbed in the water softening device 1100. Specifically, it calculates the difference between the conductivity of the raw water stored in the memory unit 1112 and the conductivity of the softened water. This difference is the concentration of ions adsorbed in the water softening device 1100. The adsorption amount estimation unit 1111 multiplies the ion concentration obtained as the difference by the total amount of water passing through measured by the water volume measurement unit 1103. In this way, the amount of ions adsorbed in the water softening device 1100 during the regeneration process is estimated.

[0211] Here, the current value and current application time required to remove the estimated adsorbed ions from the water softening device 1100 and to regenerate the water softening device 1100 will be described.

[0212] In the regeneration process, one mole of electrons is converted to H ＋ 1 mole of electrons to OH － To release 1 mole of hardness ions from the resin, 1 mole of H ＋ Therefore, the number of moles of ions adsorbed in the water softening chamber 1209 and the number of moles of H required for resin regeneration are ＋ The relationship between the current value, the current value, and the time is expressed by equation (12) in FIG.

[0213] The control unit 1110 determines the current value and current application time required to regenerate the weakly acidic cation exchange resin 1213 and the weakly basic anion exchange resin 1214 from the number of moles of adsorbed ions estimated by the adsorption amount estimation unit 1111 and equation (12).

[0214] In the water softening device 1100, it is preferable to change the value of the applied current as the regeneration process progresses. The reason for this will be explained below.

[0215] As the regeneration process progresses, the ions adsorbed during the water softening process are released into the water from the weakly acidic cation exchange resin 1213 and the weakly basic anion exchange resin 1214, increasing the ion concentration in the water. In other words, as time elapses since the start of the regeneration process, the conductivity of the water in the water softening device 1100 increases compared to when power was first applied, and the voltage decreases. On the other hand, at the start of power application, the ion concentration of the water in the water softening device 1100 is low, so the voltage is high. Therefore, if the current value is kept constant from the start of power application, the voltage will be high at the start of power application and will gradually decrease as power application time passes.

[0216] At the end of the regeneration process, (R-COO － ) ２ Ca ２＋ , and R ３ -NH ＋ Cl ― As the concentration of hydrogen ions decreases, the regeneration rate slows. As a result, as shown in Figure 11, the consumption rate of the introduced hydrogen ions decreases, and the conversion rate drops. When the consumption rate is low, even if hydrogen ions or hydroxide ions in a concentration greater than the capacity of the resin are introduced into the weakly acidic cation exchange resin 1213 or the weakly basic anion exchange resin 1214, the hydrogen ions and hydroxide ions will react with each other without reacting with the ions in the resin, resulting in a loss.

[0217] In other words, according to the voltage characteristics at the beginning of the regeneration process described above, when applying current, it is preferable to gradually increase the current rather than immediately increasing it to the current value determined by the adsorption amount estimation unit 1111. This allows the voltage to be kept low, thereby reducing power consumption.

[0218] Furthermore, due to the reactivity of the resin, it is preferable to gradually reduce the current towards the end of the regeneration process, which prevents excess ions from reacting with each other, reduces current waste, and reduces power consumption.

[0219] In order to measure such a change in the applied current over time, a timer unit 1113 is used.

[0220] The storage unit 1112 stores a first reference value that maximizes the current and a second reference value that starts decreasing the current from the maximum value as reference times indicating when to change the current. The first reference value is set to about 30 minutes to 1 hour after the start of current application. The second reference value is set to a time later than the first reference value and 30 minutes to 1 hour before the end of current application.

[0221] The current and time required for the regeneration process are determined by the adsorbed hardness, as shown in equation (12). Therefore, if the time from the start of current application to the first reference value and the time from the end of current application to the second reference value are increased, the maximum current value or regeneration time must be increased.

[0222] The timer 1113 measures the elapsed time from the start of current application to the first electrode 1201 and the second electrode 1202. When the elapsed time measured by the timer 1113 reaches a first reference value, the controller 1110 stops increasing the applied current value and maintains the current value. Thereafter, when the elapsed time measured by the timer 1113 reaches a second reference value, the controller 1110 decreases the applied current value. Note that the increase in the current value from the start of current application to the first reference value, or the decrease in the current value from the second reference value to the end of current application, may be changed linearly or stepwise.

[0223] In the regeneration process, a determined current value is applied to the first electrode 1201 and the second electrode 1202 for a determined current application time, and the weakly acidic cation exchange resin 1213 and the weakly basic anion exchange resin 1214 are regenerated.

[0224] After the regeneration process is complete, high concentrations of ions released from the weakly acidic cation exchange resin 1213 and the weakly basic anion exchange resin 1214 remain in the water softening chamber 1209 and the neutralization chamber 1210. For this reason, it is necessary to perform a cleaning operation inside the water softening device 1100. If the cleaning is insufficient, the remaining ions will mix with the water during the water softening process, which could result in insufficient water softening. For this reason, a cleaning process is performed after the regeneration process is complete.

[0225] During the cleaning process, in the water softening device 1100, the softened water supply pipe on-off valve 1106 is closed and the drain pipe on-off valve 1108 is opened. This causes the water in the water softening chamber 1209 and the neutralization chamber 1210 to be drained outside the water softening device 1100 via the drain pipe 1107. Then, raw water flows in from the raw water supply pipe 1104, making it possible to restart the regeneration process.

[0226] When the end of the washing process is determined by time, the washing time, which is the time from the start to the end of the washing process, is set longer than the residence time, which is the time from when the raw water flows into the water softening chamber 1209 to when it flows out of the neutralization chamber 1210. This allows the water in the water softening chamber 1209 that contains a large amount of desorbed hardness ions to be discharged, and the water in the water softening chamber 1209 to be replaced with raw water.

[0227] During the regeneration process, solid calcium carbonate and other substances adhere to the electrode surface of the second electrode 1202. If the amount of calcium carbonate deposited on the electrode surface increases, problems such as an increase in voltage when current is applied and difficulty in peeling calcium carbonate from the electrode surface occur. Therefore, it is necessary to periodically perform an electrode cleaning process to remove calcium carbonate from the cathode surface.

[0228] In the electrode cleaning process, the first electrode 1201 is connected to the negative electrode and the second electrode 1202 is connected to the positive electrode. In other words, the electrode cleaning is performed by operating the device with the polarity of the electrodes reversed from that of the regeneration process. By this operation, H ＋ is generated, and calcium carbonate on the surface of the second electrode 1202 reacts with H ＋ The electrode cleaning process is carried out during or after the regeneration process is completed.

[0229] In this manner, in the water softening device 1100, the softening of raw water by the water softening process, and the maintenance of the water softening device 1100 by the regeneration process, cleaning process, and electrode cleaning process are repeatedly performed.

[0230] (Embodiment 3) A water softening device 1100b according to embodiment 3 of the present disclosure differs from embodiment 2 in that an electrolyte other than hydrogen ions and hydroxide ions is introduced into the water softening chamber and the neutralization chamber during the regeneration process. Other configurations are the same as those of the water softening device 1100 according to embodiment 2. Below, the content already explained in embodiment 2 will be omitted as appropriate, and differences from embodiment 2 will be mainly explained.

[0231] During the regeneration process, particularly at the start of power supply, if the electrolyte concentration of the water in the water softening device 1100b is low, the voltage when power is supplied to the first electrode 1201 and the second electrode 1202 will be high, resulting in problems such as the inability to apply a specified current or high power consumption.

[0232] Therefore, in this embodiment, electrolytes are supplied to reduce the resistance of water during electrolysis in the regeneration process. Specifically, by supplying raw water, the electrolytes in the raw water are utilized. The water softening device 1100b is primarily used in hard water regions. Since raw water in hard water regions contains many ions, including hardness ions, at high concentrations, by supplying raw water, the ions in the raw water before softening can be used as electrolytes at the start of the regeneration process.

[0233] A method for supplying electrolytes in a regeneration process using raw water will be described.

[0234] Before energizing the first electrode 1201 and the second electrode 1202 in the regeneration process, the water softening device 1100b is filled with raw water. Specifically, after closing the soft water supply pipe on-off valve 1106, the drain pipe on-off valve 1108 is opened, whereby raw water is supplied to the water softening device 1100b by tap water pressure. In other words, the water softening device 1100b includes a raw water supply pipe 1104 as an electrolyte supply unit.

[0235] After a certain time has elapsed since the start of supply, the drain pipe valve 1108 is closed to terminate drainage. Thereafter, current is started to be passed through the first electrode 1201 and the second electrode 1202. Note that if a long time elapses between the introduction of raw water into the water softener 1100b and the start of current application, ions in the raw water will be adsorbed by the weakly acidic cation exchange resin 1213 or the weakly basic anion exchange resin 1214. Therefore, it is preferable to start current application as soon as possible after closing the drain pipe valve 1108. The appropriate time for keeping the drain pipe valve 1108 open is at least the time required for the water in the water softener 1100b to be replaced, and if tap water is used for domestic use, it will only be a few minutes.

[0236] (Embodiment 4) A water softening apparatus 1100c according to embodiment 4 of the present disclosure differs from embodiment 3 in that it includes a chemical sustained-release unit 1302 as an electrolyte input unit that inputs electrolytes other than hydrogen ions and hydroxide ions as chemicals to raw water passing through the water softening chamber 1209 and the neutralization chamber 1210 during the regeneration process. The rest of the configuration is the same as that of the water softening apparatus 1100b according to embodiment 3. Below, the content already explained in embodiment 3 will be omitted as appropriate, and differences from embodiment 3 will be mainly explained.

[0237] Referring to FIG. 12, a water softening device 1100c according to this embodiment will be described.

[0238] Fig. 12 is a conceptual diagram showing the configuration of a water softening device 1100c according to this embodiment. Note that Fig. 12 conceptually shows each element of the water softening device 1100c.

[0239] The raw water supply pipe 1104a is a pipe that connects the source of raw water, such as a water supply, to the water conveyance section inlet 1207, and the chemical addition pipe 1301 branches off at a branch point located midway along the flow path (raw water supply pipe 1104a), and the chemical addition pipe 1301 reconnects at a junction point downstream of the branch point.

[0240] The soft water supply pipe 1105 is provided with a soft water supply pipe opening / closing valve 1106 downstream of the branch point with the drain pipe 1107 .

[0241] The raw water supply pipe 1104a is provided with a raw water supply pipe opening / closing valve 1304 downstream of the branch point with the chemical addition pipe 1301 and upstream of the junction point.

[0242] The chemical addition pipe 1301 is a pipe that bypasses the raw water supply pipe 1104a from its branch point to its junction point, and is provided with a chemical addition pipe opening / closing valve 1303 and a chemical sustained release section 1302 on the flow path.

[0243] The chemical release unit 1302 is located downstream of the chemical addition pipe on-off valve 1303 and adds a chemical to the raw water flowing into the chemical addition pipe 1301. This supplies electrolytes to the raw water. Any chemical that is harmless to the human body can be used as the chemical to be added; specifically, food-grade chemicals are preferred. Examples include sodium sulfate, sodium chloride, sodium chloride, calcium chloride, and sodium polyphosphate. The polarity is not particularly limited, but since the water is intended for daily use, neutral salts that result in a neutral pH are preferred. Among neutral salts, sulfates or phosphates, which have little effect on the anode life, are more preferred.

[0244] The raw water supply pipe on-off valve 1304 is provided on the raw water supply pipe 1104a and is a valve whose opening degree can be adjusted. By opening and closing the valve or adjusting the opening degree, the electrolyte concentration in the raw water can be adjusted.

[0245] If it is desired to increase the electrolyte concentration in the raw water, raw water supply pipe on-off valve 1304 is closed when chemical addition pipe on-off valve 1303 is opened. As a result, all raw water flowing into casing 1109 passes through chemical sustained release section 1302, resulting in water containing a higher concentration of electrolytes than the original raw water.

[0246] On the other hand, if it is desired to lower the electrolyte concentration in the raw water, raw water supply pipe on-off valve 1304 is also opened when chemical addition pipe on-off valve 1303 is opened. As a result, only a portion of the raw water flowing into casing 1109 passes through chemical slow-release section 1302, and the remaining raw water does not pass through chemical slow-release section 1302, so that water with a higher electrolyte concentration than the raw water but a lower electrolyte concentration than when raw water supply pipe on-off valve 1304 is closed is obtained.

[0247] The flow path configuration during the water softening process and the flow path configuration during the regeneration process in the fourth embodiment will be described.

[0248] In the water softening process, raw water is introduced into the water softening device 1100c with the raw water supply pipe on-off valve 1304 and the softened water supply pipe on-off valve 1106 open and the chemical addition pipe on-off valve 1303 and the drain pipe on-off valve 1108 closed. In this way, the raw water is softened in the same manner as in the second embodiment.

[0249] In the regeneration process, before supplying raw water, the softened water supply pipe on-off valve 1106 is closed, and the drain pipe on-off valve 1108 and the chemical addition pipe on-off valve 1303 are opened. To prevent the intrusion of chemicals into the softened water supply pipe 1105, it is preferable to close the softened water supply pipe on-off valve 1106 before opening the drain pipe on-off valve 1108 and the chemical addition pipe on-off valve 1303. By supplying raw water in this state, the chemical addition pipe on-off valve 1303 is opened, and the chemical is released from the chemical release unit 1302 into the raw water, dissolving the chemical in the raw water and producing electrolyte-containing water with a high concentration of electrolytes.

[0250] With this electrolyte-containing water filling the water softener 1100c, electrolysis is carried out by the first electrode 1201 and the second electrode 1202, and regeneration of the ion exchange resin progresses. After a certain time has elapsed since the start of electrolysis, the drain pipe on-off valve 1108 and the chemical addition pipe on-off valve 1303 are closed. To reduce the water pressure on the water softener 1100c, it is better to close the chemical addition pipe on-off valve 1303 first and then close the drain pipe on-off valve 1108. The time for which the electrolyte-containing water flows through the water softener 1100c, i.e., the time for which the drain pipe on-off valve 1108 is kept open, is appropriate to be at least the time it takes for the water in the water softener 1100c to be replaced, and if tap water is used for domestic use, a few minutes will suffice.

[0251] (Embodiment 5) A water softening device 1100d according to embodiment 5 of the present disclosure differs from embodiment 3 in that it uses wastewater discharged after the previous regeneration process as the electrolyte when current begins to flow in the regeneration process. Other configurations are the same as those of the water softening device 1100b according to embodiment 3. Below, the content already explained in embodiment 3 will be omitted as appropriate, and differences from embodiment 3 will be mainly explained.

[0252] Referring to FIG. 13, a water softening device 1100d according to this embodiment will be described.

[0253] Fig. 13 is a conceptual diagram showing the configuration of a water softening device 1100d according to this embodiment. Note that Fig. 13 conceptually shows each element of the water softening device 1100d.

[0254] The raw water supply pipe 1104b is a pipe that connects a source of raw water, such as a water supply, to the water conveyance section inlet 1207, and is connected to the reclaimed water return pipe 1405 described later at a junction located midway along the flow path.

[0255] The soft water supply pipe 1105a is a pipe that connects the water supply unit outlet 1206 and a supply destination of the soft water, and a drain pipe 1107a branches off from the soft water supply pipe 1105a midway through the flow path. The soft water supply pipe 1105a is provided with a soft water supply pipe opening / closing valve 1106 downstream of the branch point of the drain pipe 1107a.

[0256] The drain pipe 1107a is a pipe that branches off from the soft water supply pipe 1105a upstream of the soft water supply pipe on-off valve 1106, and is a pipe that drains water during the regeneration process. The drain pipe 1107a is provided with a drain pipe on-off valve 1108 on its flow path, and is connected to the soft water supply pipe 1105a at one end and to the storage chamber 1401 at the other end.

[0257] The storage chamber 1401 is a tank that stores the cleaning water drained from the water softening chamber 1209 and the neutralization chamber 1210 during the cleaning process described below, and is equipped with an inlet 1402, a first water supply port 1403, and a second water supply port 1404.

[0258] The inlet 1402 is an opening for introducing water into the storage chamber 1401, and is connected to the drain pipe 1107a. The inlet 1402 is preferably provided in the storage chamber 1401 at the top of the housing.

[0259] The first water supply port 1403 is an opening for discharging the water in the storage chamber 1401 to the outside of the water softening device 1100d, and is connected to a drain pipe 1107a through which drainage water flows. The first water supply port 1403 is preferably provided in the storage chamber 1401 at an upper part of the housing.

[0260] The second water supply port 1404 is connected to a reclaimed water return pipe 1405 described later, and is an opening for sending the water in the storage chamber 1401 to the reclaimed water return pipe 1405.

[0261] The reclaimed water return pipe 1405 has one end connected to the second water supply port 1404 and the other end connected to the raw water supply pipe 1104b, and supplies the wastewater in the storage chamber 1401 to the raw water supply pipe 1104b. The reclaimed water return pipe 1405 is provided with a reclaimed water return pipe opening / closing valve 1406 midway along its flow path.

[0262] That is, the water softening device 1100d includes a storage chamber 1401 as an electrolyte supply unit.

[0263] The flow path configuration during the water softening process and the flow path configuration during the regeneration process in the fifth embodiment will be described.

[0264] In the water softening process, the softened water supply pipe on-off valve 1106 is opened, and the drain pipe on-off valve 1108 and the reclaimed water return pipe on-off valve 1406 are closed, and raw water is introduced into the water softening device 1100d. In this way, the raw water is softened in the same manner as in the second embodiment.

[0265] In the regeneration process, before supplying raw water, the softened water supply pipe on-off valve 1106 is closed, and the drain pipe on-off valve 1108 and the reclaimed water return pipe on-off valve 1406 are opened. By this opening and closing operation, part of the raw water introduced from the raw water supply pipe 1104 is discharged from the first water supply port 1403 of the storage chamber 1401 to the outside of the water softening device 1100d, and the remaining raw water passes through the storage chamber 1401, from the second water supply port 1404, through the reclaimed water return pipe 1405, and is supplied again into the casing 1109. With this configuration, water from the storage chamber 1401 can be supplied into the casing 1109 by utilizing water line pressure, eliminating the need for a pump.

[0266] The wastewater discharged after the regeneration process contains a large amount of ions released during the process, so by utilizing this wastewater and supplying it to raw water, the electrolyte concentration in the raw water can be increased.The ions released from the resin during the regeneration process are ions that were originally contained in the raw water, so they can be used without any problems from a safety standpoint.

[0267] The timing for storing the wastewater containing electrolyte in the storage chamber 1401 is during the cleaning process that is carried out after the regeneration process.

[0268] The cleaning process is a process in which cations released from the weakly acidic cation exchange resin 1213 by the regeneration process are discharged from the water softening chamber 1209, and anions released from the weakly basic anion exchange resin 1214 are discharged from the neutralization chamber 1210.

[0269] At the beginning of the cleaning process, water containing a high concentration of ions released from the resin is discharged from casing 1109, but as cleaning progresses, the ion concentration in the wastewater decreases and becomes close to that of the raw water. Therefore, from the perspective of increasing the electrolyte concentration when current is applied to first electrode 1201 and second electrode 1202, it is preferable to retain as much water as possible at the beginning of the cleaning process in storage chamber 1401. By providing inlet 1402 and first water outlet 1403 at the top of the housing of storage chamber 1401, a structure is created that makes it easy for water to stagnate in storage chamber 1401, making it easier to retain water at the bottom of storage chamber 1401 at the beginning of cleaning.

[0270] (Embodiment 6) A water softening device 1100e according to embodiment 6 of the present disclosure differs from embodiment 2 in that it includes a plurality of water softening modules. Other configurations are the same as those of the water softening device 1100 according to embodiment 2. Below, the following will mainly describe the differences from embodiment 2, omitting redundant explanations of the content already explained in embodiment 2.

[0271] Referring to FIG. 14, a water softening device 1100e according to this embodiment will be described.

[0272] Fig. 14 is a conceptual diagram showing the configuration of a water softening device 1100e according to this embodiment. Note that Fig. 14 conceptually shows each element of the water softening device 1100e.

[0273] The water softening device 1100e includes a plurality of water softening modules, and in this embodiment includes two water softening modules 1501 (a water softening module 1501a and a water softening module 1501b).

[0274] The water softening module 1501 includes the casing 1109 and the configuration inside the casing 1109 in the second embodiment, and specifically includes at least a water softening chamber, a neutralization chamber, and a diaphragm.

[0275] The water softening module 1501a provided on the upstream side and the water softening module 1501b provided on the downstream side are connected by a connecting pipe 1502. Specifically, the water conveying section inlet 1207 of the water softening module 1501a is connected to the raw water supply pipe 1104, and the water conveying section outlet 1206 is connected to the connecting pipe 1502. Furthermore, the water conveying section inlet 1207 of the water softening module 1501b is connected to the connecting pipe 1502, and the water conveying section outlet 1206 is connected to the softened water supply pipe 1105.

[0276] The raw water supply pipe 1104 is provided with a conductivity meter 1503a, the connection pipe 1502 is provided with a conductivity meter 1503b, and the softened water supply pipe 1105 is provided with a conductivity meter 1503c.

[0277] The conductivity meter 1503a measures the conductivity of the water flowing through the raw water supply pipe 1104, that is, the water flowing into the water softening module 1501a.

[0278] The conductivity meter 1503b measures the conductivity of the water flowing through the connecting pipe 1502, that is, the water flowing out from the water softening module 1501a.

[0279] The conductivity meter 1503c measures the conductivity of the water flowing through the softened water supply pipe 1105, that is, the water flowing out from the water softening module 1501b.

[0280] When water softening modules are connected in multiple stages, the amount of ions adsorbed by each module often does not match. For example, when two water softening modules are connected, raw water flows into the first module, and water whose hardness has been reduced by the softening treatment in the first module flows into the second module.

[0281] From equation (11) shown in FIG. 10, as the water hardness decreases, the reaction rate of hardness adsorption slows, resulting in a decrease in the amount of hardness adsorbed into the water softening chamber 1209. The amount of adsorption into the neutralization chamber 1210 also decreases. Therefore, when comparing the ion adsorption amounts for each water softening module, the amount of adsorption into the upstream water softening module is greater than the amount of adsorption into the downstream water softening module. Therefore, it is desirable to set the current value or current application time according to the degree of resin wear in each water softening module, which also leads to reduced power consumption. Therefore, the water softening device 1100e calculates the optimal current value and current application time for each water softening module during the regeneration process.

[0282] During the regeneration process, conductivity meters 1503a, 1503b, and 1503c measure the conductivity of the water flowing through each flow path, and calculate the difference in conductivity before and after each water softening module. Water volume measurement unit 1103 also measures the cumulative amount of water passing through the water softening module. The current value and duration of current flow required to regenerate the water softening chamber and neutralization chamber of each water softening module are calculated from the resulting difference in conductivity and the cumulative amount of water passing.

[0283] (Seventh Embodiment) A water softening apparatus 1100f according to a seventh embodiment of the present disclosure differs from the second embodiment in that a drainage process is executed to drain the water from the apparatus during the regeneration process in order to reduce the ion concentration of the water in the water softening apparatus 1100f. Other configurations are the same as those of the water softening apparatus 1100 according to the second embodiment. Below, the content already explained in the second embodiment will be omitted as appropriate, and differences from the second embodiment will be mainly explained.

[0284] A water softening device 1100f according to this embodiment will be described with reference to Fig. 15. Fig. 15 is a conceptual diagram showing the configuration of the water softening device 1100f according to this embodiment. Note that Fig. 15 conceptually shows each element of the water softening device 1100f.

[0285] The water softening device 1100 f includes an upstream drain pipe 1601 .

[0286] The upstream drain pipe 1601 is a pipe branching off from the raw water supply pipe 1104, and is a pipe for draining water from the water softening device 1100f in the drainage process. The upstream drain pipe 1601 is provided with a drain valve 1602.

[0287] The drain valve 1602 is a valve provided on the upstream drain pipe 1601, and when the drain valve 1602 is opened, the water in the water softening device 1100f is drained from the upstream drain pipe 1601 to the outside of the water softening device 1100f.

[0288] A drainage water volume measuring unit 1603 is provided on the drainage pipe 1107. The drainage water volume measuring unit 1603 measures the volume of water that has flowed into the drainage pipe 1107.

[0289] During the regeneration process, the water softening apparatus 1100f executes a drainage process for draining the water in the water softening apparatus 1100f in order to reduce the ion concentration of the water in the water softening apparatus 1100f. The reason for this will be explained below.

[0290] In the regeneration process, as the time for which current is applied to the first electrode 1201 and the second electrode 1202 increases, the amount of Ca in the regenerated water decreases. ２＋ , and Mg ２＋ Concentration of cations such as ions, Cl － , and S.O. ４ ２－ When the concentration of these ions increases, the Ca ２＋ , and Cl － The concentration of ions increases, and the rate of the reaction in the opposite direction to the reaction that regenerates the ion exchange resins increases. As a result, the ions desorbed from each ion exchange resin inhibit the regeneration reactions of the weakly acidic cation exchange resin 1213 and the weakly basic anion exchange resin 1214. In the configuration of the present disclosure, the regeneration reaction proceeds even without draining the water, but draining the water to reduce the concentration can improve the efficiency of the regeneration reaction.

[0291] The timing of drainage in the drainage process is determined by the timing unit 1113. Specifically, when the elapsed time from the start of the regeneration process measured by the timing unit 1113 exceeds a certain time, the control unit 1110 opens the drain valve 1602 and drains the water with an increased ion concentration present in the water softening device 1100f to the outside via the upstream drain pipe 1601. This reduces the ion concentration of the water in the water softening device 1100f, improving the regeneration efficiency in the regeneration process.

[0292] When determining the timing of drainage based on the time elapsed since the start of the regeneration process, it is better to drain the water more frequently from the start to the middle of the regeneration and less frequently in the latter half of the regeneration.

[0293] As shown in Figure 11, the reaction efficiency is high up to the middle of the regeneration process, so the change in the desorbed ion concentration over time is large. On the other hand, the reaction efficiency is low in the latter half of the regeneration process, so the change in the desorbed ion concentration over time is small. For this reason, the drainage frequency in the latter half of the regeneration process can be less than in the middle of the regeneration process. In other words, it is preferable to increase the time interval between drainage processes as the regeneration process progresses. Taking into account both the reduction in the amount of drainage and the reduction in reaction inhibition caused by desorbed ions, the drainage interval is preferably about 30 minutes. For example, the drainage process is performed once every 20 minutes up to the middle of the regeneration process, and once every 40 minutes in the latter half of the regeneration process.

[0294] When drainage is complete, the control unit 1110 closes the drain valve 1602, and after closing the drain valve 1602, opens the drain pipe on-off valve 1108. This allows raw water to flow in from outside the water softening device 1100f, filling the water softening device 1100f with raw water, making it possible to carry out the regeneration process again. The timing to end the inflow of raw water is determined by the drainage water volume measurement unit 1603. Specifically, the inflow is ended when the amount of inflow water since the start of the drainage process, measured by the drainage water volume measurement unit 1603, becomes greater than the combined volume of the water softening chamber 1209 and the neutralization chamber 1210.

[0295] The present disclosure has been described above based on the embodiments. These embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of each component or each treatment process, and that such modifications are also within the scope of the present disclosure.

[0296] (Modification) In the second embodiment, the water volume measuring unit 1103 is provided on the softened water supply pipe 1105, but this is not limiting. For example, even if the water volume measuring unit 1103 is provided midway along the raw water supply pipe 1104, the amount of water passed through the water softening device 1100 can be measured.

[0297] In the second embodiment, the amount of ions adsorbed in the water softening device 1100 is determined by the adsorption amount estimation unit by calculating the concentration of ions adsorbed in the water softening device 1100 from the difference between the conductivities measured by the raw water conductivity measurement unit 1101 and the softened water conductivity measurement unit 1102, and multiplying the reduced ion concentration by the total amount of water flowing measured by the water volume measurement unit 1103, but this is not limited to this method.

[0298] For example, a method may be used in which the ion concentration of the raw water is calculated from the conductivity measured by the raw water conductivity measuring unit 1101, and the calculated raw water ion concentration is multiplied by the total amount of water flow measured by the water volume measuring unit 1103. With this calculation method, the amount of adsorbed ions according to the fluctuation in the water quality of the raw water can be determined without providing the soft water conductivity measuring unit 1102.

[0299] Alternatively, a method may be used in which the total amount of water passing through measured by the water amount measuring unit 1103 is multiplied by a pre-measured ion concentration. With this calculation method, the amount of ions adsorbed in the water softening device 1100 can be determined without providing the raw water conductivity measuring unit 1101 and the softened water conductivity measuring unit 1102.

[0300] In the second embodiment, the applied current value is controlled based on the elapsed time measured by the timer unit 1113 from the start of energization. However, this is not limiting. For example, the applied current value may be controlled using a voltage measurement unit that measures the voltage and the amount of change in voltage over time when energization is performed on the first electrode 1201 and the second electrode 1202. When the voltage measurement unit is used to change the current value, the amount of change in voltage over time is measured and the current is changed accordingly. At the start of energization, a current lower than the target current value determined by the adsorption amount estimation unit 1111 is applied, and the current is increased when the amount of change in voltage over time becomes small. Then, when the amount of change in voltage over time becomes small again, the current is further increased. This step is repeated. It is preferable to increase the current in approximately 10 steps. This is because, although it depends on the amount of increase in the current value, the voltage becomes constant in approximately 5 minutes from the time the current value is increased.

[0301] In the second embodiment, the timing to end the cleaning process is determined based on time, but this is not limiting. For example, it can also be determined by a drainage water volume measuring unit 1603 installed in the drainage pipe 1107. If the amount of water measured by the drainage water volume measuring unit 1603 from the start of the drainage process is equal to or greater than the volume of the water softening chamber 1209 and the neutralization chamber 1210, the drainage process can be ended.

[0302] The timing to end the cleaning process may also be determined by a wastewater conductivity measuring unit installed in the drain pipe 1107. The wastewater conductivity measuring unit measures the conductivity of the wastewater flowing out of the water softening device 1100 during the cleaning process. Because the cleaning process is carried out using raw water, if the desorbed ions in the water softening device 1100 can be discharged outside the water softening device 1100, the hardness of the drained water will be equal to or lower than the hardness of the raw water. The wastewater conductivity measuring unit measures the conductivity of the wastewater and compares it with the conductivity measured by the raw water conductivity measuring unit 1101. The cleaning process can be ended when the conductivity of the wastewater becomes equal to or lower than the conductivity of the raw water.

[0303] In the seventh embodiment, the timing of draining water is determined based on the elapsed time since the start of the regeneration process measured by the timer 1113, but this is not limited to this. For example, the timing of draining water may be determined using a reclaimed water conductivity measuring unit that measures the conductivity of the water in the water softening device 1100f and the amount of change in conductivity over time. In this case, when the conductivity of the reclaimed water conductivity measuring unit exceeds a certain value, the control unit 1110 controls the opening and closing of the drain pipe opening / closing valve 1108 or the drain valve 1602 to drain water from the water softening device 1100f.

[0304] When the timing of drainage is determined by the conductivity measurement unit, the drainage pipe on-off valve on the drainage pipe 1107 is opened when the conductivity exceeds a certain value, and closed after a predetermined time has elapsed. The location where conductivity is measured is the water conveying section, where hardness ions tend to accumulate. This is because hardness ions desorbed from the weakly acidic cation exchange resin 1213 by regeneration diffuse into the water conveying section and tend to accumulate in the water conveying section, and regeneration of the weakly acidic cation exchange resin 1213 is more likely to be inhibited by desorbed ions than that of the weakly basic anion exchange resin 1214.

[0305] The certain value of conductivity that serves as the standard for draining the water is not particularly limited, but is preferably about 3 mS / cm. When the conductivity of the water in the water conveying section reaches 3 mS / cm during the regeneration process, the hardness has increased to approximately 1000 mg / L. Even if the hardness is higher than 1000 mg / L, the regeneration of the weakly acidic cation exchange resin 1213 proceeds, but the efficiency decreases due to the influence of the reverse reaction. Therefore, draining the water when the conductivity reaches about 3 mS / cm can be more effective in preventing the reverse reaction.

[0306] The water softening device according to the present disclosure can reduce the frequency of drainage or eliminate the need for drainage altogether, thereby reducing the amount of drainage, and as a secondary effect, can also shorten the regeneration time and increase the electrode life, making it useful as a water softening device, etc.

[0307] Eighth Embodiment The technique described in Patent Document 1 has a problem in that hardness ions released from the ion exchange resin are re-adsorbed onto the ion exchange resin, which tends to inhibit the reaction during regeneration of the resin.

[0308] The present disclosure has been made in view of the problems inherent in the prior art, and aims to provide a water softening device that allows efficient regeneration of resin.

[0309] The water softening device according to the present disclosure comprises a water softening chamber containing a weakly acidic cation exchange resin and producing soft water from raw water containing hardness components; a neutralization chamber located on the outer periphery of the water softening chamber and containing a weakly basic anion exchange resin and neutralizing the soft water; a diaphragm that separates the water softening chamber and the neutralization chamber to allow soft water to pass through; a water conveying section located on the inner periphery of the water softening chamber and supplying raw water to the water softening chamber; a water conveying section that conveys the neutralized soft water produced in the neutralization chamber to the outside; and a control section that controls the regeneration of the weakly acidic cation exchange resin. The control unit executes a water softening process in which raw water is introduced from the water conveying unit and passed through the water softening chamber and then the neutralization chamber to obtain neutralized soft water; a regeneration process in which, after the water softening process has been performed for a predetermined period of time, water is electrolyzed and the weakly acidic cation exchange resin is regenerated using the generated hydrogen ions; and a drainage process in which cations released from the weakly acidic cation exchange resin during the regeneration process are discharged from the water softening chamber and anions released from the weakly basic anion exchange resin are discharged from the neutralization chamber. In the drainage process, the cation-containing water is drained from the water conveying unit. According to the present disclosure, a water softening device capable of efficient resin regeneration can be provided.

[0310] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that each of the following embodiments is an example of the present disclosure and does not limit the technical scope of the present disclosure. Furthermore, each drawing used in each embodiment is a schematic drawing, and the ratios of the sizes and thicknesses of the components in each drawing do not necessarily reflect the actual dimensional ratios.

[0311] A water softening device 2100 according to an eighth embodiment of the present disclosure will be described with reference to FIGS. 16, 17, and 18. FIG.

[0312] FIG. 16 is a schematic diagram showing the configuration of a water softening device 2100 according to an eighth embodiment of the present disclosure. FIG. 17 is a perspective view showing the configuration of a water softening device 2100 according to the eighth embodiment of the present disclosure. FIG. 18 is a cross-sectional view showing the configuration of a water softening device 2100 according to the eighth embodiment of the present disclosure. Note that FIGS. 16 to 18 conceptually show each element of the water softening device 2100. Furthermore, in FIG. 17, the weakly acidic cation exchange resin 2213 and the weakly basic anion exchange resin 2214 are omitted.

[0313] The water softening device 2100 is a device that produces neutral soft water from raw water containing hardness components that is supplied from the outside. The raw water is water (water to be treated) that is introduced into the water softening device 2100 from a raw water supply pipe 2104 (described later), and is, for example, well water or tap water. The raw water contains hardness components (calcium ions or magnesium ions).

[0314] By performing a water softening process to soften raw water using the water softening device 2100, neutral soft water with reduced hardness can be obtained from raw water with high hardness, and soft water can be used even in areas where the raw water has high hardness.

[0315] After carrying out the water softening process for a certain period of time, the water softening device 2100 carries out a regeneration process to regenerate the weakly acidic cation exchange resin 2213 and the weakly basic anion exchange resin 2214, which will be described later. The details of the water softening process and the regeneration process will be described later.

[0316] As shown in FIG. 16, the water softening device 2100 includes a raw water supply pipe 2104, a drain pipe 2107, a softened water supply pipe 2105, a bypass pipe 2114, a casing 2109, and a control unit 2110.

[0317] Raw water supply pipe 2104 is a pipe that connects a raw water source, such as a water supply, to a water conveyance section inlet 2207 (described later), and is provided with raw water conductivity measuring section 2101 on its flow path. Raw water supply pipe 2104 is connected to drain pipe 2107 downstream of raw water conductivity measuring section 2101 and upstream of the connection point with water conveyance section inlet 2207. A drain pipe opening / closing valve 2108 is provided at the connection point between raw water supply pipe 2104 and drain pipe 2107.

[0318] The raw water conductivity measuring unit 2101 calculates the total ion concentration of the raw water flowing into the raw water supply pipe 2104. The calculated total ion concentration information of the raw water is sent to the control unit 2110, which will be described later.

[0319] The drain pipe 2107 is a pipe branched off from the raw water supply pipe 2104 at a drain pipe opening / closing valve 2108, and is a pipe through which drainage is carried out during the drainage process described below.

[0320] The drain pipe on-off valve 2108 is a valve provided at the connection between the raw water supply pipe 2104 and the drain pipe 2107. By opening and closing the drain pipe on-off valve 2108, it is possible to switch between sending raw water from the water supply source to the water conveying section inlet 2207 via the raw water supply pipe 2104, or discharging water in a casing 2109 (described later) to the outside of the water softening device 2100 via the raw water supply pipe 2104 and the drain pipe 2107.

[0321] The soft water supply pipe 2105 is a pipe that connects the water supply unit outlet 2206 (described later) to the soft water supply destination, and is provided with a soft water conductivity measuring unit 2102, a water volume measuring unit 2103, and a soft water supply pipe opening / closing valve 2106 on its flow path.

[0322] The soft water conductivity measuring unit 2102 calculates the total ion concentration of the soft water sent out from the water sending unit outlet 2206 (see FIG. 17 ). The calculated total ion concentration information of the soft water is sent to the control unit 2110, which will be described later.

[0323] Any device capable of measuring the resistance of water can be used as the raw water conductivity measuring unit 2101 and the soft water conductivity measuring unit 2102 without any problems.

[0324] The water volume measuring unit 2103 is a component that measures the volume of water passed through the water softening device 2100, and may use a device such as a water meter that can measure the cumulative volume of water. The measured water volume information is sent to the control unit 2110, which will be described later.

[0325] The softened water supply pipe on-off valve 2106 is a valve provided in the softened water supply pipe 2105. By opening and closing the softened water supply pipe on-off valve 2106, it is possible to switch between supplying softened water to the outside and not supplying softened water to the outside.

[0326] The bypass pipe 2114 branches off from the raw water supply pipe 2104 upstream of the connection between the raw water supply pipe 2104 and the drainage pipe 2107, and connects to the softened water supply pipe 2105 upstream of the softened water supply pipe on-off valve 2106. Through the bypass pipe 2114, raw water is supplied from a raw water supply source to the water conveyance unit outlet 2206 during the drainage process and the cleaning process, which will be described later. The bypass pipe 2114 is provided with a bypass pipe on-off valve 2115 on its flow path.

[0327] The bypass pipe on-off valve 2115 is a valve provided on the bypass pipe 2114. By opening and closing the bypass pipe on-off valve 2115, raw water can be supplied from the water supply source to the water supply unit outlet 2206 via the bypass pipe 2114 and the softened water supply pipe 2105.

[0328] The casing 2109 is a hollow cylindrical member, and the raw water is softened and the ion exchange resin is regenerated within the casing 2109 .

[0329] 17 and 18 , a water conveying section 2203, a water softening chamber 2209, a neutralization chamber 2210, and a water supply section 2204 are provided in the hollow space of the casing 2109, in this order from the side closest to the central axis I connecting the top and bottom surfaces of the casing 2109 toward the outer periphery. A water conveying section inlet 2207 is provided at the center of the bottom surface of the casing 2109, i.e., on the central axis I. A water supply section outlet 2206 is provided at the center of the top surface of the casing 2109, i.e., on the central axis I. The central axis I of the casing 2109 coincides with the central axes of the water conveying section 2203, the water softening chamber 2209, the neutralization chamber 2210, and the water supply section 2204, respectively.

[0330] The water conveying section inlet 2207 is provided on the bottom surface of the casing 2109 and supplies raw water to the water conveying section 2203. The central axis of the water conveying section inlet 2207 coincides with the central axis I of the casing 2109. The water conveying section inlet 2207 is connected in communication with the raw water supply pipe 2104.

[0331] The water conveying section 2203 is a cylindrical member, and its lower end is connected to a water conveying section inlet 2207. The water conveying section 2203 conveys raw water into the water softening device 2100 and supplies it to the water softening chamber 2209. The water conveying section 2203 may be a tube such as a pipe having an internal space, or a water-permeable membrane.

[0332] The water conveying section 2203 is configured to allow raw water introduced into the water softening device 2100 to flow uniformly through the water softening chamber 2209 and the neutralization chamber 2210. Specifically, the water conveying section 2203 is provided in the center of the casing 2109, and the outer periphery of the water conveying section 2203 is in contact with the water softening chamber 2209;

[0333] Furthermore, the water conveying section 2203 is provided from the bottom to the top of the water softening chamber 2209 and the neutralization chamber 2210, more precisely from the bottom to the top. The length of the part of the water conveying section 2203 that can supply raw water to the water softening chamber 2209 and the neutralization chamber 2210 is equal to the height of the water softening chamber 2209 and the neutralization chamber 2210.

[0334] The water conveying section 2203 has a plurality of holes on its side surface, through which raw water is delivered from the central axis I of the casing 2109 toward the periphery, i.e., toward the water softening chamber 2209. Furthermore, it is preferable that the plurality of holes be uniformly arranged in the circumferential direction on the side surface of the water conveying section 2203. With this configuration, raw water introduced into the device can be uniformly delivered to the water softening chamber 2209 and the neutralization chamber 2210. Therefore, the raw water is evenly supplied to the particles of the weakly acidic cation exchange resin 2213 packed in the water softening chamber 2209 and the particles of the weakly basic anion exchange resin 2214 packed in the neutralization chamber 2210. This allows efficient use of the weakly acidic cation exchange resin 2213 and the weakly basic anion exchange resin 2214 as a whole.

[0335] The plurality of holes formed on the side surface of the water conducting section 2203 are smaller in diameter than the particles of the weakly acidic cation exchange resin 2213. Since the lower limit of the particle diameter of the weakly acidic cation exchange resin 2213 is around 0.3 mm, the diameter of the holes formed on the surface of the water conducting section 2203 is smaller than that. This prevents the ion exchange resin from leaking out of the water softening chamber 2209 without impeding the permeation of water.

[0336] The water softening chamber 2209 is a cylindrical space (first space 2211) that is provided inside the casing 2109 on the outer circumferential side of the water conducting section 2203 with respect to the central axis I of the casing 2109, and contains a weakly acidic cation exchange resin 2213. The central axis of the water softening chamber 2209 coincides with the central axis I of the casing 2109. The water softening chamber 2209 is in contact with the water conducting section 2203 on the inner surface side of its cylindrical shape, in contact with an inner circumferential diaphragm 2215, which is a cylindrical membrane that is water permeable, on the outer surface side, and in contact with the lid section 2208 on the top surface. The water softening chamber 2209 is filled with the weakly acidic cation exchange resin 2213, and is provided with a first electrode 2201.

[0337] The weakly acidic cation exchange resin 2213 is an ion exchange resin having a carboxyl group, and may be, for example, one having a methacrylic acid skeleton or one having an acrylic acid skeleton. In this embodiment, a resin having an acrylic acid skeleton is used as the weakly acidic cation exchange resin 2213.

[0338] The first electrode 2201 is not energized during the water softening process and serves as an anode during the regeneration process of the weakly acidic cation exchange resin 2213. The first electrode 2201 is surrounded by the weakly acidic cation exchange resin 2213 in the water softening chamber 2209. Here, "surrounded" refers to a state in which the surface of the first electrode 2201 is in contact with the surface of the weakly acidic cation exchange resin 2213 from top to bottom along the entire periphery. However, the weakly acidic cation exchange resin 2213 is usually spherical, and a water passage for the raw water must be secured. For this reason, the term "the first electrode 2201 is surrounded by the weakly acidic cation exchange resin 2213" also applies to a state in which the weakly acidic cation exchange resin 2213 is not in complete contact with the surface of the first electrode 2201, but is arranged in partial contact along the entire periphery.

[0339] The upper end of the first electrode 2201 is located below the water surface in the water softening chamber 2209 at the start of the regeneration process. A plurality of first electrodes 2201 (first electrode 2201a and first electrode 2201b are exemplified) are provided in the water softening chamber 2209 so that the distances between adjacent first electrodes 2201 are equal.

[0340] A noble metal or a noble metal alloy can be used as the material of the first electrode 2201. This is because the noble metal contained in the first electrode 2201 acts as a catalyst for water electrolysis and is not eluted even under acidic conditions. Examples of noble metal materials include platinum, iridium, and ruthenium.

[0341] Examples of the electrode form include a noble metal wire electrode alone, an electrode in which a noble metal wire is wound around the outer periphery of a support, or a mesh-shaped noble metal electrode. It is also possible to use a metal rod other than a noble metal, such as titanium (Ti), as the support, with a noble metal coated on the surface. However, since the presence of an interface between different metals is likely to cause deterioration due to the interface, it is preferable to use a noble metal or noble metal alloy alone.

[0342] The inner diaphragm 2215 is a water-permeable membrane that partitions the water softening chamber 2209 and the neutralization chamber 2210 to allow soft water to pass through. The inner surface of the inner diaphragm 2215 covers the outer surface of the water softening chamber 2209 and is in contact with the outer surface of the water softening chamber 2209. In addition, the outer surface of the inner diaphragm 2215 covers the inner surface of the neutralization chamber 2210 and is in contact with the inner surface of the neutralization chamber 2210.

[0343] As a result, the inner diaphragm 2215 separates the water softening chamber 2209 from the neutralization chamber 2210 while allowing the acidic soft water produced in the water softening chamber 2209 to pass through. Note that "covering" only requires that the membrane be positioned around the object, and does not necessarily require that the membrane completely enclose the object.

[0344] The neutralization chamber 2210 is a cylindrical space (second space 2212) located inside the casing 2109 on the outer circumferential side of the water softening chamber 2209 with respect to the central axis I of the casing 2109, and contains a weakly basic anion exchange resin 2214. The central axis of the neutralization chamber 2210 coincides with the central axis I of the casing 2109. The inner surface of the neutralization chamber 2210 contacts the outer surface of the inner circumferential diaphragm 2215, the outer surface of the neutralization chamber 2210 contacts the inner surface of the outer circumferential diaphragm 2216, which is a cylindrical membrane having water permeability, and the upper surface of the neutralization chamber 2210 contacts the lid 2208. The neutralization chamber 2210 is filled with a weakly basic anion exchange resin 2214, and is provided with a plurality of second electrodes 2202 (second electrode 2202a and second electrode 2202b are exemplified).

[0345] The weakly basic anion exchange resin 2214 is an ion exchange resin having tertiary amine and quaternary amine functional groups, and in this embodiment, a resin having a higher proportion of tertiary amine than quaternary amine is used.

[0346] The second electrode 2202 is not energized during the water softening process, and acts as a cathode during the regeneration process of the weakly basic anion exchange resin 2214. The second electrode 2202 is surrounded by the weakly basic anion exchange resin 2214 within the neutralization chamber 2210.

[0347] Here, "surrounded" refers to a state in which the surface of the second electrode 2202 is in contact with the surface of the weakly basic anion exchange resin 2214 from the top to the bottom around the entire periphery. However, like the weakly acidic cation exchange resin 2213, the weakly basic anion exchange resin 2214 usually has a spherical shape, and a water passage for the raw water (strictly speaking, acidic soft water) must be secured. For this reason, the term "second electrode 2202 is surrounded by the weakly basic anion exchange resin 2214" also applies to a state in which the weakly basic anion exchange resin 2214 is not in complete contact with the surface of the second electrode 2202 but is arranged around the entire periphery in a state of partial contact.

[0348] The upper end of the second electrode 2202 is located below the water surface in the neutralization chamber 2210 at the start of the regeneration process. A plurality of second electrodes 2202 are provided in the neutralization chamber 2210 so that the distance between adjacent second electrodes 2202 is equal.

[0349] A noble metal or a noble metal alloy can be used as the material of the second electrode 2202. This is because the noble metal contained in the second electrode 2202 acts as a catalyst for water electrolysis and is not eluted even under acidic conditions. Examples of noble metal materials include platinum, iridium, and ruthenium.

[0350] Examples of the electrode form include a noble metal wire electrode alone, an electrode in which a noble metal wire is wound around the outer periphery of a support, or a mesh-shaped noble metal electrode. Alternatively, a metal rod other than a noble metal, such as titanium (Ti), may be used as the support, with the surface coated with a noble metal. However, since the presence of an interface between dissimilar metals is likely to cause deterioration due to the interface, it is preferable to use a noble metal or noble metal alloy alone.

[0351] The first electrode 2201 is provided as a pair with the second electrode 2202 , and the pair of first electrode 2201 and second electrode 2202 is provided on the same radius of the casing 2109 .

[0352] This allows the distance between the first electrode 2201 and the second electrode 2202 to be shorter than when the pair of electrodes are not on the same radius, and makes it possible to suppress an increase in power consumption due to an increase in voltage.

[0353] The water softening device 2100 includes a circuit for cleaning electrodes (a circuit including a power source) that connects the first electrode 2201 to the negative electrode and the second electrode 2202 to the positive electrode.

[0354] The outer peripheral diaphragm 2216 is a water-permeable membrane that partitions the neutralization chamber 2210 and the water supply section 2204 so that soft water can pass through. The inner surface of the outer peripheral diaphragm 2216 covers the outer surface of the neutralization chamber 2210 and is in contact with the outer surface of the neutralization chamber 2210. In addition, the outer surface of the outer peripheral diaphragm 2216 covers the inner surface of the water supply section 2204 and is in contact with the inner surface of the water supply section 2204.

[0355] This allows the soft water generated in the neutralization chamber 2210 to pass through while separating the neutralization chamber 2210 from the water supply section 2204. Note that "covering" only requires that the cover be positioned around the object, and does not necessarily require that the cover completely enclose the object.

[0356] The upper surfaces of the water conveying section 2203 , the water softening chamber 2209 , the inner diaphragm 2215 , the neutralization chamber 2210 , and the outer diaphragm 2216 are covered by the lid section 2208 .

[0357] The lid 2208 has a water-impermeable structure and may be made of, for example, a plate-shaped resin. The lid 2208 contacts and covers the upper surfaces of the water conveying section 2203, the water softening chamber 2209, the inner diaphragm 2215, the neutralization chamber 2210, and the outer diaphragm 2216, thereby separating the upper surfaces from the water conveying section 2204, which will be described later.

[0358] This makes it possible to prevent water from flowing out from each upper surface into the water supply section 2204. In other words, the cover section 2208 makes it possible to form a water flow in which raw water flowing in from the water conveying section inlet 2207 passes through the water conveying section 2203, the water softening chamber 2209, the inner periphery-side diaphragm 2215, and the neutralization chamber 2210, and is sent out from the side surface of the outer periphery-side diaphragm 2216 to the side space 2204 a of the water supply section 2204.

[0359] The water supply unit 2204 supplies the soft water sent out from the neutralization chamber 2210 to a water supply unit outlet 2206 provided above the upper part of the neutralization chamber 2210. The central axis of the water supply unit 2204 coincides with the central axis I of the casing 2109.

[0360] The water supply part 2204 is provided with an air vent valve 2205 that vents air from inside the casing 2109. The water supply part 2204 includes a side space 2204a and an upper space 2204b.

[0361] The side space 2204a is a cylindrical space that is provided on the outer circumferential side of the neutralization chamber 2210 with respect to the central axis I of the casing 2109 and surrounds the neutralization chamber 2210. The side space 2204a is in contact with the outer surface of the outer circumferential diaphragm 2216 on the inner surface side of the cylindrical shape, and in contact with the inner surface of the casing 2109 on the outer surface side. In other words, the side space 2204a is a space that is provided between the inner surface of the casing 2109 and the outer surface of the outer circumferential diaphragm 2216.

[0362] In a direction parallel to the central axis I, the total length of the side space 2204a is longer than the total length of the neutralization chamber 2210, and when the side space 2204a and the bottom surfaces of the neutralization chamber 2210 are aligned on the same plane, the top surface of the side space 2204a protrudes upward above the top surface of the neutralization chamber 2210.

[0363] The upper space 2204b is a cylindrical space provided above the top surfaces of the water conveying section 2203, the water softening chamber 2209, the inner periphery diaphragm 2215, the neutralization chamber 2210, and the outer periphery diaphragm 2216. The cylindrical top surface of the upper space 2204b contacts the inner top wall of the casing 2109, and the cylindrical bottom surface of the upper space 2204b contacts the outer top wall of the lid section 2208. The cylindrical outer surface of the upper space 2204b contacts the inner surface of the side space 2204a.

[0364] The water supply unit outlet 2206 is provided on the top surface of the casing 2109, and discharges the water in the water supply unit 2204 to the outside of the water softening device 2100. The central axis of the water supply unit outlet 2206 coincides with the central axis I of the casing 2109. The water supply unit outlet 2206 is connected in communication with the softened water supply pipe 2105.

[0365] Returning to FIG. 16, the control unit 2110 controls the execution of each of the following processes: a water softening process, a regeneration process, a drainage process, a cleaning process, and an electrode cleaning process, which will be described later.

[0366] The control unit 2110 can be realized as hardware by elements and mechanical devices such as a computer CPU (Central Processing Unit), and as software by a computer program, etc. Therefore, these functional blocks can be realized in various forms by combining hardware and software.

[0367] The control unit 2110 includes an adsorption amount estimation unit 2111 , a storage unit 2112 , and a timer unit 2113 .

[0368] The adsorption amount estimation unit 2111 calculates the total amount of ions adsorbed in the water softening device 2100 using the total ion concentration of the raw water calculated by the raw water conductivity measurement unit 2101, the total ion concentration of the softened water calculated by the softened water conductivity measurement unit 2102, and the total amount of water passing through measured by the water volume measurement unit 2103.

[0369] The storage unit 2112 stores the various pieces of information transmitted to the control unit 2110 and the various pieces of information calculated by the control unit 2110 .

[0370] The timer 2113 measures the time elapsed since the start of the regeneration process, more specifically, the time elapsed since the start of energization of the first electrode 2201 and the second electrode 2202 .

[0371] The water softening device 2100 has the above configuration.

[0372] Next, the processes (water softening process, regeneration process, drainage process, cleaning process, and electrode cleaning process) executed by the water softening device 2100 will be described with reference to FIGS. 19 and 20. FIG.

[0373] Fig. 19 is a diagram including formulas showing the principle of the water softening device in embodiment 8. Fig. 20 is a diagram showing the change over time in the rate of hydrogen ion consumption by the weakly acidic cation exchange resin during the regeneration process.

[0374] First, the operation of the water softening device 2100 in the water softening process and the principle of the water softening process will be described.

[0375] 17 and 18 , in the water softening device 2100, raw water flows from the outside into the lower part of the water conveying section 2203 through the water conveying section inlet 2207. The flowing raw water is sent from the lower part to the upper part of the water conveying section 2203 and flows out in the radial direction of the casing 2109 from holes provided in the side wall of the water conveying section 2203. In other words, the raw water is sent out from the holes in the water conveying section 2203 to the water softening chamber 2209.

[0376] The raw water sent to the water softening chamber 2209 is softened by the weakly acidic cation exchange resin 2213 filled inside the water softening chamber 2209. In detail, hardness components (calcium ions or magnesium ions) in the raw water are exchanged with hydrogen ions adsorbed on the weakly acidic cation exchange resin 2213, and the raw water becomes acidic soft water containing hydrogen ions.

[0377] The acidic softened water produced in the water softening chamber 2209 passes through the inner diaphragm 2215, which is a water-permeable membrane, and flows into the neutralization chamber 2210, where it is neutralized. Specifically, hydrogen ions in the softened water are removed from the softened water by being adsorbed onto the weakly basic anion exchange resin 2214, and neutral softened water (neutralized softened water) is produced. During this neutralization reaction, anions such as sulfate ions contained in the softened water are also adsorbed onto the weakly basic anion exchange resin 2214.

[0378] The neutralized soft water produced in the neutralization chamber 2210 passes through the outer peripheral diaphragm 2216, which is a water-permeable membrane, and flows into the water supply section 2204.

[0379] The softened water that flows into the water supply section 2204 flows upward, rises in the side space 2204a of the water supply section 2204, and flows into the upper space 2204b of the water supply section 2204. The softened water that flows into the upper space 2204b flows toward the center of the upper space 2204b and is taken out from the water supply section outlet 2206 provided in the center of the top surface of the water softening device 2100.

[0380] In this way, the raw water is softened in the water softening process.

[0381] In the water softening process, if the amount of cations (more specifically, hardness ions such as calcium ions or magnesium ions) adsorbed onto the weakly acidic cation exchange resin 2213 or the amount of anions adsorbed onto the weakly basic anion exchange resin 2214 increases, the resin's water softening performance will decrease, and a regeneration process will be required.

[0382] In the regeneration process, first, raw water flows from a raw water supply source into the water conveying section 2203 via the water conveying section inlet 2207, and the flowing raw water is sent to the water softening chamber 2209 and the neutralization chamber 2210. Next, electricity is passed through each electrode so that the first electrode 2201 surrounded by the weakly acidic cation exchange resin 2213 has a higher potential than the second electrode 2202 surrounded by the weakly basic anion exchange resin 2214.

[0383] As a result, a reaction that produces hydrogen ions (see formula (25) in FIG. 19 ) occurs at the first electrode 2201, which is an anode, and a reaction that produces hydroxide ions (see formula (26) in FIG. 19 ) occurs at the second electrode 2202, which is a cathode. In other words, hydrogen ions are produced in the water softening chamber 2209, and hydroxide ions are produced in the neutralization chamber 2210.

[0384] When the weakly acidic cation exchange resin 2213, which has absorbed hardness components during the water softening process, is exposed to hydrogen ions, an exchange reaction between the hardness components and the hydrogen ions occurs, thereby regenerating the weakly acidic cation exchange resin 2213.

[0385] Furthermore, when the weakly basic anion exchange resin 2214 to which anions have been adsorbed in the water softening process is exposed to hydroxide ions, an exchange reaction between the adsorbed anions and the hydroxide ions occurs, thereby regenerating the weakly basic anion exchange resin 2214.

[0386] In this manner, the weakly acidic cation exchange resin 2213 and the weakly basic anion exchange resin 2214 are regenerated in the regeneration process.

[0387] In the regeneration process, the water softening device 2100 sets the regeneration time based on the conductivity of the raw water or softened water before and after passing through the casing 2109 or the amount of water passed through the casing 2109 .

[0388] Specifically, at the start of the water softening process, raw water conductivity measuring unit 2101 is activated and measures the conductivity of raw water flowing through raw water supply pipe 2104. Also, soft water conductivity measuring unit 2102 is activated and measures the conductivity of soft water flowing through soft water supply pipe 2105. Furthermore, water volume measuring unit 2103 measures the volume of water that has flowed through casing 2109. The measured raw water conductivity, soft water conductivity, and water volume are transmitted to control unit 2110 and stored in memory unit 2112.

[0389] The ions removed in the water softening chamber 2209 are mainly Mg ２＋ , and Ca ２＋ The ions removed in the neutralization chamber 2210 are mainly HCO ３ － , Cl － , and S.O. ４ ２－ are anions. According to the principle of electroneutrality, the number of moles of cations adsorbed in the water softening chamber 2209 is equal to the number of moles of anions adsorbed in the neutralization chamber 2210. Therefore, the difference between the conductivity measured by the raw water conductivity measuring unit 2101 and the conductivity measured by the softened water conductivity measuring unit 2102 is derived from the total amount of Mg salts and Ca salts removed by the water softening device 2100. In this way, because the conductivity difference is the value of the removed ion concentration, it is possible to respond to changes in the water quality of the raw water and softened water, and the amount of adsorption can be calculated with high accuracy.

[0390] The adsorption amount estimation unit 2111 estimates the amount of ions adsorbed in the water softening device 2100. Specifically, it calculates the difference between the conductivity of the raw water stored in the memory unit 2112 and the conductivity of the softened water. This difference is the concentration of ions adsorbed in the water softening device 2100. The adsorption amount estimation unit 2111 multiplies the ion concentration obtained as the difference by the total amount of water passing through measured by the water volume measurement unit 2103. In this way, the amount of ions adsorbed in the water softening device 2100 during the regeneration process is estimated.

[0391] Here, the current value and current application time required to remove the estimated adsorbed ions from the water softening device 2100 and to regenerate the water softening device 2100 will be described.

[0392] In the regeneration process, one mole of electrons is converted to H ＋1 mole of electrons to OH － To release 1 mole of hardness ions from the resin, 1 mole of H ＋ Therefore, the number of moles of ions adsorbed in the water softening chamber 2209 and the number of moles of H required for resin regeneration are ＋ The relationship between the current value, the current value, and the time is expressed by equation (22) in FIG.

[0393] The control unit 2110 determines the current value and current application time required to regenerate the weakly acidic cation exchange resin 2213 and the weakly basic anion exchange resin 2214 from the number of adsorbed ion moles estimated by the adsorption amount estimation unit 2111 and equation (22) in Figure 19.

[0394] In the water softening device 2100, it is preferable to change the value of the applied current as the regeneration process progresses. The reason for this will be explained below.

[0395] As the regeneration process progresses, the ions adsorbed during the water softening process are released into the water from the weakly acidic cation exchange resin 2213 and the weakly basic anion exchange resin 2214, increasing the ion concentration in the water. In other words, as the time elapses since the start of the regeneration process increases, the conductivity of the water in the water softening device 2100 increases compared to when power was first applied, and the voltage decreases. On the other hand, at the start of power application, the ion concentration of the water in the water softening device 2100 is low, so the voltage is high. Therefore, if the current value is kept constant from the start of power application, the voltage will be high at the start of power application and will gradually decrease as power application time passes.

[0396] At the end of the regeneration process, (R-COO － ) ２ Ca ２＋ , and R ３ -NH ＋ Cl ―As the concentration of hydrogen ions decreases, the regeneration rate slows down. As a result, as shown in Figure 20, the consumption rate of the introduced hydrogen ions decreases, and the conversion rate drops. When the consumption rate is low, even if hydrogen ions or hydroxide ions at a concentration greater than the concentration that can be consumed by the resin are introduced into the weakly acidic cation exchange resin 2213 or the weakly basic anion exchange resin 2214, they will not react with the ions in the resin but will react with each other, resulting in a loss.

[0397] In other words, according to the voltage characteristics at the beginning of the regeneration process described above, when applying current, it is preferable to gradually increase the current rather than immediately increasing it to the current value determined by the adsorption amount estimation unit 2111. This keeps the voltage low, thereby reducing power consumption.

[0398] Furthermore, due to the reactivity of the resin, it is preferable to gradually reduce the current towards the end of the regeneration process, which prevents excess ions from reacting with each other, reduces current waste, and reduces power consumption.

[0399] In order to measure such a change in the applied current over time, a timer unit 2113 is used.

[0400] The storage unit 2112 stores a first reference value that maximizes the current and a second reference value that starts decreasing the current from the maximum value as reference times indicating the timing to change the current. The first reference value is set to approximately 30 minutes to 1 hour after the start of current application. The second reference value is set to a time later than the first reference value and 30 minutes to 1 hour before the end of current application.

[0401] The current and time required for the regeneration process are determined by the adsorbed hardness, as shown in equation (22) in Figure 19. Therefore, if the time from the start of current application to the first reference value and the time from the end of current application to the second reference value are increased, the maximum current value or regeneration time must be increased.

[0402] The timer 2113 measures the elapsed time from the start of current application to the first electrode 2201 and the second electrode 2202. When the elapsed time measured by the timer 2113 reaches a first reference value, the controller 2110 stops increasing the applied current value and maintains the current value. Thereafter, when the elapsed time measured by the timer 2113 reaches a second reference value, the controller 2110 decreases the applied current value. Note that the increase in the current value from the start of current application to the first reference value, or the decrease in the current value from the second reference value to the end of current application, may be changed linearly or stepwise.

[0403] In the regeneration process, a determined current value is applied to the first electrode 2201 and the second electrode 2202 for a determined current application time, and the weakly acidic cation exchange resin 2213 and the weakly basic anion exchange resin 2214 are regenerated.

[0404] As described above, the regeneration process gradually increases the concentrations of various ions, including hardness ions such as calcium ions or magnesium ions released from the weakly acidic cation exchange resin 2213 and the weakly basic anion exchange resin 2214, over time. In particular, as the hardness ion concentration increases, the equilibrium shifts to the left in the reaction formula shown in (23) of Figure 19, i.e., toward the weakly acidic cation exchange resin 2213 again adsorbing the hardness ions. Therefore, to efficiently perform regeneration, it is important to suppress an increase in the calcium ion concentration in the water contained in the casing 2109.

[0405] On the other hand, if all the water contained in casing 2109 is discharged and raw water is supplied to casing 2109 to carry out the regeneration process, the ion concentration contained in the raw water is lower than the ion concentration of the water present in casing 2109 during the regeneration process, which is disadvantageous to the regeneration process. Therefore, in order to efficiently proceed with the regeneration process, it is preferable to reduce the concentration of hardness ions without significantly reducing the total ion concentration in casing 2109. For this reason, a drainage process is carried out to discharge some of the water in casing 2109.

[0406] In the drainage process, it is important to discharge an appropriate amount of water, in order to reduce the concentration of hardness ions while maintaining the electrolyte concentration in the water softening chamber 2209 and the neutralization chamber 2210 at a certain value or higher (for example, at or above the electrolyte concentration of the raw water) in preparation for carrying out the regeneration process again after the drainage process, thereby suppressing a decrease in the efficiency of the regeneration process.

[0407] Here, the amount of water discharged during the discharge process is preferably smaller than the sum of the volume of the water conveying section 2203, the volume of the water softening chamber 2209, and the volume of the neutralization chamber 2210, and it is more preferable that the volume of the area in the water softening chamber 2209 other than that occupied by the weakly acidic cation exchange resin 2213 is smaller than the sum of the volumes of the area in the neutralization chamber 2210 other than that occupied by the weakly basic anion exchange resin 2214. Also, it is preferable that the volume is larger than the volume of the area in the water softening chamber 2209 other than that occupied by the weakly acidic cation exchange resin 2213.

[0408] Here, the drainage will be described in detail with reference to FIGS. 21 and 22, illustrating specific numerical values.

[0409] FIG. 21 is a diagram showing an example in which the volumes of the water conveying section 2203, the water softening chamber 2209, and the neutralization chamber 2210 are larger than those in FIG.

[0410] Specifically, the volumes of the water-conducting section 2203, the water-softening chamber 2209, and the neutralization chamber 2210 in FIG. 21 are approximately 900 mL, approximately 1300 mL, and approximately 1600 mL, respectively.

[0411] FIG. 22 is a diagram showing the relationship between the amount of wastewater and the hardness contained in the wastewater after the regeneration process has been performed for one hour in the example of FIG.

[0412] In the examples shown in Figures 21 and 22, hard water (hardness: 300 mg / L) in an amount equivalent to the amount of wastewater is added after drainage. Although the volumes of the water softening chamber 2209 and the neutralization chamber 2210 are as described above, the water softening chamber 2209 is filled with a weakly acidic cation exchange resin 2213, and the neutralization chamber 2210 is filled with a weakly basic anion exchange resin 2214. Therefore, the amount of water filled in the water softening chamber 2209 and the neutralization chamber 2210 is less than the respective volumes. In other words, water exists only in the areas other than the spaces occupied by the weakly acidic cation exchange resin 2213 and the weakly basic anion exchange resin 2214. Experimental testing revealed that the amount of water filled in each space was approximately one-third the volume of the water softening chamber 2209 or the neutralization chamber 2210.

[0413] Therefore, in the example of Figure 21, the volume of the water softening chamber 2209 is 1300 mL, and there is approximately 400 mL of water in the water softening chamber 2209, and the volume of the neutralization chamber 2210 is 1600 mL, and there is approximately 500 mL of water in the neutralization chamber 2210.

[0414] According to Figure 22, the hardness of the wastewater reaches its maximum when the wastewater volume is approximately 550 mL. Even when the wastewater volume is 820 mL, the hardness is more than twice that of the injected water with a hardness of 300 mg / L. Therefore, when the wastewater volume in the wastewater process is in this range, the hardness can be efficiently reduced during regeneration. In other words, when the wastewater volume in the wastewater process is greater than the volume of the portion occupied by the weakly acidic cation exchange resin 2213 in the water softening chamber 2209, the ion concentration in the water softening chamber 2209 can be efficiently reduced, which is preferable. Furthermore, when the wastewater volume is greater than the sum of the volume of the portion occupied by the weakly acidic cation exchange resin 2213 in the water softening chamber 2209 and the volume of the portion occupied by the weakly basic anion exchange resin 2214 in the neutralization chamber 2210, the ion concentrations in the water softening chamber 2209 and the neutralization chamber 2210 can be efficiently reduced, which is preferable.

[0415] 22 shows that the hardness of the injected water is higher than 300 mg / L even when the amount of wastewater exceeds 1600 mL. Therefore, the hardness can be efficiently reduced during regeneration even when the amount of wastewater is greater than the volume of the water softening chamber 2209. However, it is preferable that the maximum amount of wastewater in the drainage process is smaller than the sum of the volumes of the water softening chamber 2209 and the neutralization chamber 2210.

[0416] Returning to FIG. 16, specific flow paths and the like in the drainage process will now be described.

[0417] During the regeneration process, the drain pipe on-off valve 2108 and the bypass pipe on-off valve 2115 are both closed. At the start of the drain process, the drain pipe on-off valve 2108 is set to a state in which the drain pipe 2107 and the water conveying section 2203 are connected, and the bypass pipe on-off valve 2115 is opened. This allows raw water to be injected into the casing 2109.

[0418] At this time, it is preferable that the flow rate of the discharged water is smaller than the flow rate during the water softening process, since the water can be discharged without stirring within the casing 2109. Furthermore, the amount of discharged water can be measured using any known method without any particular limitations, and examples include a method of determining a specified amount of discharged water using the output of the water volume measuring unit 2103, or a method of using the output of the timing unit 2113.

[0419] Furthermore, the timing for starting the drainage process can be determined based on, for example, the elapsed time since the start of the regeneration process. Specifically, when the elapsed time since the start of the regeneration process measured by the timing unit 2113 exceeds a certain time, the control unit 2110 performs the drainage process. This reduces the ion concentration of the water in the water softening device 2100, improving the regeneration efficiency of the regeneration process. It is preferable to perform the drainage process multiple times until regeneration is complete. This allows the regeneration process to be performed when the hardness ion concentration is low, which is preferable because it improves the efficiency of regeneration.

[0420] When determining the timing of the start of the drainage process based on the elapsed time from the start of the regeneration process, it is preferable to increase the frequency of the drainage process from the start of the regeneration process to the middle of the regeneration process and decrease the frequency of the drainage process in the latter half of the regeneration process. As shown in Figure 20, the reaction efficiency is high until the middle of the regeneration process, so the change over time in the desorbed ion concentration is large. On the other hand, the reaction efficiency is low in the latter half of the regeneration process, so the change over time in the desorbed ion concentration is small. Therefore, the drainage frequency in the latter half of the regeneration process can be less than in the middle of the regeneration process. In other words, it is preferable to increase the time interval between drainage processes as the regeneration process progresses. Considering both the reduction in the amount of drainage and the reduction of reaction inhibition caused by desorbed ions, the drainage interval is preferably about 30 minutes. For example, the drainage process is performed once every 20 minutes until the middle of the regeneration process and once every 40 minutes in the latter half of the regeneration process.

[0421] When the drainage is complete, the control unit 2110 closes the drain pipe opening / closing valve 2108 and the bypass pipe opening / closing valve 2115. This makes it possible to execute the regeneration process again.

[0422] Furthermore, in the drainage process, the direction of drainage is also important. The weakly acidic cation exchange resin 2213 in the water softening chamber 2209 has a biased distribution of the amount of hardness components adsorbed. That is, the weakly acidic cation exchange resin 2213 on the water conveying section 2203 side is the place where raw water first flows in, so it is likely to adsorb hardness components. On the other hand, the weakly acidic cation exchange resin 2213 on the inner circumference diaphragm 2215 side is downstream of the weakly acidic cation exchange resin 2213 on the water conveying section 2203 side, so it tends to adsorb fewer hardness components than the weakly acidic cation exchange resin 2213 on the water conveying section 2203 side.

[0423] In the regeneration process, protons are supplied to the weakly acidic cation exchange resin 2213 in this state to perform a regeneration treatment. During this regeneration treatment, the adsorbed hardness components are released from the weakly acidic cation exchange resin 2213. Therefore, in the water softening chamber 2209, more hardness components are released from the water conveying section 2203 side than from the inner periphery diaphragm 2215 side, and therefore water with a high hardness component concentration in the water softening chamber 2209 is located on the water conveying section 2203 side. Therefore, in the drainage process, by draining the water in the water softening chamber 2209 from the water conveying section 2203 side, the hardness component concentration in the water softening chamber 2209 can be reduced with a minimum amount of drainage.

[0424] Furthermore, if, in the drainage process, the water in the water softening chamber 2209 is passed through the inner periphery diaphragm 2215 and then the neutralization chamber 2210, as in the water softening process, and then sent to the outside from the water sending section 2204, there is a possibility that the hardness components that were desorbed from the weakly acidic cation exchange resin 2213 in the regeneration process will be re-adsorbed onto the weakly acidic cation exchange resin 2213. The reason for this will be specifically explained.

[0425] As described above, the weakly acidic cation exchange resin 2213 on the inner diaphragm 2215 side tends to adsorb less hardness components and release less hardness components in the regeneration process than the weakly acidic cation exchange resin 2213 on the water conveying section 2203 side. In this state, if water is passed through the inner diaphragm 2215 and then the neutralization chamber 2210, in the water softening chamber 2209, the water on the water conveying section 2203 side, which contains a relatively large amount of hardness components, may flow into the inner diaphragm 2215 side, which contains a relatively small amount of hardness components, and may be re-adsorbed by the weakly acidic cation exchange resin 2213 on the inner diaphragm 2215 side. Therefore, from the viewpoint of improving regeneration efficiency, it is preferable that the discharge direction be water conveying section 2204, neutralization chamber 2210, inner periphery diaphragm 2215, water softening chamber 2209, and water conveying section 2203, rather than water conveying section 2203, water softening chamber 2210, inner periphery diaphragm 2215, neutralization chamber 2210, and water conveying section 2204. In other words, when discharging water in the drainage process, it is preferable that water in casing 2109 be discharged from water conveying section 2203 via drainage piping 2107. It is also preferable that raw water be supplied into casing 2109 from water conveying section outlet 2206 via bypass piping 2114.

[0426] After the drainage process is completed, the regeneration process is started again, or if the regeneration is sufficient, the regeneration process is terminated.

[0427] After the regeneration process is complete, high concentrations of ions released from the weakly acidic cation exchange resin 2213 and the weakly basic anion exchange resin 2214 remain in the water softening chamber 2209 and the neutralization chamber 2210. Therefore, it is necessary to perform a cleaning operation inside the water softening device 2100. If the cleaning is insufficient, the remaining ions will mix with the water during the water softening process, which may result in insufficient water softening. Therefore, a cleaning process is performed after the regeneration process is complete.

[0428] In the cleaning process, in the water softening device 2100, the softened water supply pipe on-off valve 2106 is closed, and the bypass pipe on-off valve 2115 and the drain pipe on-off valve 2108 are opened. As a result, the water in the water softening chamber 2209 and the neutralization chamber 2210 is drained outside the water softening device 2100 via the drain pipe 2107. Then, raw water flows in from the bypass pipe 2114 via the water supply section 2204, making the water softening process possible.

[0429] When the end of the washing process is determined by time, it is preferable to set the washing time, which is the time from the start to the end of the washing process, longer than the residence time, which is the time from when the raw water flows into the neutralization chamber 2210 until it flows out of the water softening chamber 2209. This allows water containing a large amount of desorbed hardness ions present in the water softening chamber 2209 to be discharged, and the water in the water softening chamber 2209 to be replaced with raw water.

[0430] During the regeneration process, solid calcium carbonate and the like adhere to the electrode surface of the second electrode 2202. If the amount of calcium carbonate deposited on the electrode surface increases, problems such as an increase in voltage when current is applied and difficulty in peeling calcium carbonate from the electrode surface occur. Therefore, it is preferable to periodically perform an electrode cleaning process to remove calcium carbonate from the cathode surface.

[0431] In the electrode cleaning process, the first electrode 2201 is connected to the negative electrode and the second electrode 2202 is connected to the positive electrode, that is, the electrode polarity is reversed from that in the regeneration process, and the electrode cleaning is performed. ＋ is generated, and calcium carbonate on the surface of the second electrode 2202 reacts with H ＋ The electrode cleaning process may be carried out during the regeneration process or after the regeneration process is completed.

[0432] In this manner, in the water softening device 2100, the softening of raw water by the water softening process, and the maintenance of the water softening device 2100 by the regeneration process, drainage process, cleaning process, and electrode cleaning process are repeatedly performed.

[0433] (Effects, etc.) As described above, the water softening device 2100 according to this embodiment can provide the following effects.

[0434] (1) The water softening device 2100 includes a water softening chamber 2209 having a weakly acidic cation exchange resin 2213 and producing soft water from raw water containing hardness components; a neutralization chamber 2210 located on the outer periphery of the water softening chamber 2209 and having a weakly basic anion exchange resin 2214 and neutralizing the softened water; an inner diaphragm 2215 that partitions the water softening chamber 2209 and the neutralization chamber 2210 to allow softened water to pass through; a water conveying section 2203 located on the inner periphery of the water softening chamber 2209 and supplies raw water to the water softening chamber 2209; a water conveying section 2204 that conveys the neutralized softened water produced in the neutralization chamber 2210 to the outside; and a control section 2110 that controls the regeneration of the weakly acidic cation exchange resin 2213. The control unit 2110 executes a water softening process in which raw water is introduced from the water conveying unit 2203 and passed through the water softening chamber 2209, the inner diaphragm 2215, and the neutralization chamber 2210 in this order to obtain neutralized soft water, a regeneration process in which, after the water softening process has been executed for a predetermined period of time, water is electrolyzed and the weak acid cation exchange resin 2213 is regenerated using the generated hydrogen ions, and a cleaning process in which cations released from the weak acid cation exchange resin 2213 by the regeneration process are discharged from the water softening chamber 2209 and anions released from the weak basic anion exchange resin 2214 are discharged from the neutralization chamber 2210. In a drainage process, water containing cations is drained from the water conveying unit 2203.

[0435] With this configuration, the water can be discharged from the weakly acidic cation exchange resin 2213 side, which has a high concentration of hardness components. Therefore, the re-adsorption of cations onto the weakly acidic cation exchange resin 2213 during the cleaning process can be suppressed, and the water softening apparatus 2100 can be realized with improved regeneration efficiency.

[0436] (2) In the water softening device 2100, the amount of water discharged in the drainage process is set to be smaller than the sum of the volume of the water conveying section 2203, the volume of the water softening chamber 2209, and the volume of the neutralization chamber 2210. By setting the amount of water discharged in this manner, it is possible to prevent more water than necessary from being discharged in the drainage process, and it is possible to realize a water softening device 2100 that wastes less water.

[0437] (3) In the water softening device 2100, the weakly acidic cation exchange resin 2213 is filled in the water softening chamber 2209, and the weakly basic anion exchange resin 2214 is filled in the neutralization chamber 2210. It is preferable that the amount of wastewater in the drainage process is smaller than the sum of the volume of the water softening chamber 2209 other than the portion occupied by the weakly acidic cation exchange resin 2213 and the volume of the neutralization chamber 2210 other than the portion occupied by the weakly basic anion exchange resin 2214.

[0438] By setting the discharge amount to this level, the water in the water softening chamber 2209 and the neutralization chamber 2210 can be discharged, and therefore, in the regeneration process, the cations desorbed from the weakly acidic cation exchange resin 2213 and the anions desorbed from the weakly basic anion exchange resin 2214 can be discharged outside the water softening device 2100. Therefore, in the next water softening process, it is possible to prevent cations and anions from remaining in the water softening chamber 2209, and reduce the possibility of hardness components precipitating.

[0439] (4) In the water softening device 2100, the amount of wastewater in the drainage process is greater than the volume of the water in the water softening chamber 2209 other than the area occupied by the weakly acidic cation exchange resin 2213.

[0440] This allows the water present in the water softening chamber 2209 to be drained, ensuring the minimum amount of water to be drained. Therefore, it is possible to realize the water softening device 2100 that can improve the regeneration efficiency while suppressing the amount of water to be drained.

[0441] (5) In the water softening device 2100, it is preferable that the control unit 2110 performs the draining process multiple times during the regeneration process.

[0442] In this way, the water can be discharged multiple times during the regeneration process at appropriate times, thereby improving the efficiency of resin regeneration in the regeneration process.

[0443] (6) The water softening device 2100 further includes a first electrode 2201 that is provided in the water softening chamber 2209 and surrounded by the weakly acidic cation exchange resin 2213, and that acts as an anode during regeneration of the weakly acidic cation exchange resin 2213, and a second electrode 2202 that is provided in the neutralization chamber 2210 and surrounded by the weakly basic anion exchange resin 2214, and that acts as a cathode during regeneration of the weakly basic anion exchange resin 2214. In the regeneration process, the control unit 2110 applies a voltage between the first electrode 2201 and the second electrode 2202, and determines whether to execute the drainage process based on the applied voltage.

[0444] In this way, when the ion concentration in the water softening chamber 2209 increases, the water can be drained, and the efficiency of resin regeneration in the regeneration process can be improved.

[0445] (7) In the water softening device 2100, raw water supplied into the casing 2109 during the drainage process flows in from the water conveying section 2204 side.

[0446] By doing this, during the drainage process, raw water flows in from the water supply section 2204 and the water in the casing 2109 is drained from the water guide section 2203, thereby suppressing the re-adsorption of cations onto the weakly acidic cation exchange resin 2213.

[0447] The present disclosure has been described above based on the embodiments. These embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of each component or each treatment process, and that such modifications are also within the scope of the present disclosure.

[0448] (Modification) In the eighth embodiment, the timing to start the drainage process is determined based on the elapsed time from the start of the regeneration process, but this is not limited to this. For example, the execution of the drainage process may be determined based on the voltage applied between the first electrode and the second electrode during the regeneration process. Even in this case, the same effect as in the eighth embodiment can be obtained.

[0449] The water softening device according to the present disclosure is useful as an efficient recyclable water softening device, etc.

[0450] (Embodiment 9) In the technology described in Patent Document 1, hardness ions desorbed from the ion exchange resin are re-adsorbed onto the ion exchange resin, which tends to inhibit the reaction during resin regeneration. Therefore, in order to discharge the desorbed hardness ions, regeneration must be performed while passing water through the resin. This water passing operation has the problem of increasing the amount of wastewater discharged during resin regeneration.

[0451] The present disclosure has been made in view of the problems inherent in the prior art, and aims to provide a water softening device that can suppress wastewater generation during regeneration and efficiently regenerate resin.

[0452] The water softening device according to the present disclosure comprises a water softening chamber having a weakly acidic cation exchange resin for producing soft water from raw water containing hardness components, a neutralization chamber having a weakly basic anion exchange resin for neutralizing the soft water, a diaphragm that partitions the water softening chamber and the neutralization chamber to allow soft water to pass between them, a water conveying section that introduces raw water from the outside into the water softening chamber, a water conveying section that conveys the neutralized soft water produced in the neutralization chamber to the outside, a first electrode that is surrounded by the weakly acidic cation exchange resin in the water softening chamber and acts as an anode when the weakly acidic cation exchange resin is regenerated, and a second electrode that is surrounded by the weakly basic anion exchange resin in the neutralization chamber and acts as a cathode when the weakly basic anion exchange resin is regenerated. The water softening chamber, diaphragm, neutralization chamber, and water supply section are arranged in this order from the water conveying section, which has a central axis perpendicular to the bottom surface of the water softening chamber, toward the outer periphery of a circle centered on the central axis, and the first electrode is arranged in a position within the water softening chamber that is biased toward the water conveying section.

[0453] According to the present disclosure, it is possible to provide a water softening device that can suppress wastewater during regeneration and efficiently regenerate resin.

[0454] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that each of the following embodiments is an example of the present disclosure and does not limit the technical scope of the present disclosure. Furthermore, each drawing used in each embodiment is a schematic drawing, and the ratios of the sizes and thicknesses of the components in each drawing do not necessarily reflect the actual dimensional ratios.

[0455] A water softening device 3100 according to a ninth embodiment of the present disclosure will be described with reference to Figures 23, 24, and 25.

[0456] Fig. 23 is a schematic diagram showing the configuration of a water softening device 3100 according to a ninth embodiment of the present disclosure. Fig. 24 is a perspective view showing the configuration of the water softening device 3100 according to the ninth embodiment of the present disclosure. Fig. 25 is a cross-sectional view showing the configuration of the water softening device 3100 according to the ninth embodiment of the present disclosure. Note that Figs. 23 to 25 conceptually show each element of the water softening device 3100. Furthermore, Fig. 24 omits the weakly acidic cation exchange resin 3213 and the weakly basic anion exchange resin 3214.

[0457] The water softening device 3100 is a device that produces neutral soft water from raw water containing hardness components that is supplied from the outside. The raw water is water (water to be treated) that is introduced into the water softening device 3100 from a raw water supply pipe 3104 (described later), and is, for example, well water or tap water. The raw water contains hardness components (calcium ions or magnesium ions).

[0458] By performing a water softening process to soften raw water using the water softening device 3100, neutral soft water with reduced hardness can be obtained from raw water with high hardness, and soft water can be used even in areas where the raw water has high hardness.

[0459] After carrying out the water softening process for a certain period of time, the water softening device 3100 carries out a regeneration process to regenerate the weakly acidic cation exchange resin 3213 and the weakly basic anion exchange resin 3214, which will be described later. The details of the water softening process and the regeneration process will be described later.

[0460] As shown in FIG. 23, the water softening device 3100 includes a raw water supply pipe 3104 , a casing 3109 , a softened water supply pipe 3105 , a drain pipe 3107 , and a control unit 3110 .

[0461] The raw water supply pipe 3104 is a pipe that connects a source of raw water such as a water supply to a water conveyance section inlet 3207 described later, and is provided with a raw water conductivity measuring section 3101 on its flow path.

[0462] The raw water conductivity measuring unit 3101 calculates the total ion concentration of the raw water flowing into the raw water supply pipe 3104. The calculated total ion concentration information of the raw water is sent to the control unit 3110.

[0463] The casing 3109 is a hollow cylindrical member, and the raw water is softened and the ion exchange resin is regenerated within the casing 3109 .

[0464] As shown in Figures 24 and 25, the hollow space of the casing 3109 is provided with a water conveying section 3203, a water softening chamber 3209, a neutralization chamber 3210, and a water supply section 3204, in this order from the side closest to the central axis I connecting the top and bottom surfaces of the casing 3109 toward the outer periphery. A water conveying section inlet 3207 is provided at the center of the bottom surface of the casing 3109, i.e., on the central axis I. A water supply section outlet 3206 is provided at the center of the top surface of the casing 3109, i.e., on the central axis I. The central axis I of the casing 3109 coincides with the central axes of the water conveying section 3203, the water softening chamber 3209, the neutralization chamber 3210, and the water supply section 3204. The central axis I is perpendicular to the bottom surface of the water softening chamber 3209.

[0465] The water conveying section inlet 3207 is provided on the bottom surface of the casing 3109 and supplies raw water to the water conveying section 3203. The central axis of the water conveying section inlet 3207 coincides with the central axis I of the casing 3109. The water conveying section inlet 3207 is connected in communication with the raw water supply pipe 3104.

[0466] The water conveying section 3203 is a cylindrical member, and its lower end is connected to the water conveying section inlet 3207. The water conveying section 3203 conveys raw water into the water softening device 3100 and supplies it to the water softening chamber 3209. The water conveying section 3203 may be a tube such as a pipe having an internal space.

[0467] The water conducting section 3203 is configured to allow raw water introduced into the water softening device 3100 to flow uniformly through the water softening chamber 3209 and the neutralization chamber 3210. Specifically, the water conducting section 3203 is provided in the center of the casing 3109, and the outer periphery of the water conducting section 3203 is in contact with the water softening chamber 3209;

[0468] Furthermore, the water conveying section 3203 is provided from the bottom to the top of the water softening chamber 3209 and the neutralization chamber 3210, more precisely from the bottom to the top. The length of the part of the water conveying section 3203 that can supply raw water to the water softening chamber 3209 and the neutralization chamber 3210 is equal to the height of the water softening chamber 3209 and the neutralization chamber 3210.

[0469] The water conveying section 3203 has a plurality of holes on its side surface, through which raw water is delivered from the central axis I of the casing 3109 in the circumferential direction, i.e., to the water softening chamber 3209. Furthermore, the plurality of holes are preferably uniformly arranged in the circumferential direction on the side surface of the water conveying section 3203. With this configuration, raw water introduced into the device can be uniformly delivered to the water softening chamber 3209 and the neutralization chamber 3210. Therefore, the raw water is evenly supplied to the particles of weakly acidic cation exchange resin 3213 packed in the water softening chamber 3209 and the particles of weakly basic anion exchange resin 3214 packed in the neutralization chamber 3210. This allows efficient use of the weakly acidic cation exchange resin 3213 and the weakly basic anion exchange resin 3214 as a whole.

[0470] The plurality of holes formed on the side surface of the water conducting section 3203 are smaller in diameter than the particles of the weakly acidic cation exchange resin 3213. Since the lower limit of the particle diameter of the weakly acidic cation exchange resin 3213 is around 0.3 mm, the diameter of the holes formed on the surface of the water conducting section 3203 is smaller than that. This makes it possible to prevent the outflow of ion exchange resin from the water softening chamber 3209 without impeding the permeation of water.

[0471] The water softening chamber 3209 is a cylindrical space (first space 3211) that is provided inside the casing 3109 on the outer circumferential side of the water conducting section 3203 with respect to the central axis I of the casing 3109, and contains a weakly acidic cation exchange resin 3213. The central axis of the water softening chamber 3209 coincides with the central axis I of the casing 3109. The water softening chamber 3209 is in contact with the water conducting section 3203 on the inner surface side of its cylindrical shape, in contact with an inner circumferential diaphragm 3215, which is a cylindrical membrane that is water permeable, on the outer surface side, and in contact with the lid section 3208 on the top surface. The water softening chamber 3209 is filled with the weakly acidic cation exchange resin 3213, and is provided with a first electrode 3201.

[0472] The weakly acidic cation exchange resin 3213 is an ion exchange resin having a carboxyl group, and may be, for example, one having a methacrylic acid skeleton or one having an acrylic acid skeleton. In this embodiment, a resin having an acrylic acid skeleton is used as the weakly acidic cation exchange resin 3213.

[0473] The first electrode 3201 is not energized during the water softening process and serves as an anode during the regeneration process of the weakly acidic cation exchange resin 3213. The first electrode 3201 is surrounded by the weakly acidic cation exchange resin 3213 in the water softening chamber 3209. Here, "surrounded" refers to a state in which the surface of the first electrode 3201 is in contact with the surface of the weakly acidic cation exchange resin 3213 from top to bottom along the entire periphery. However, the weakly acidic cation exchange resin 3213 is usually spherical, and a water passage for the raw water must be secured. Therefore, the "first electrode 3201 is surrounded by the weakly acidic cation exchange resin 3213" does not necessarily mean that the weakly acidic cation exchange resin 3213 is in complete contact with the surface of the first electrode 3201, but rather a state in which the weakly acidic cation exchange resin 3213 is in partial contact with the surface of the first electrode 3201 along the entire periphery.

[0474] The upper end of the first electrode 3201 is located below the water surface in the water softening chamber 3209 at the start of the regeneration process. A plurality of first electrodes 3201 (first electrode 3201a and first electrode 3201b are exemplified) are provided in the water softening chamber 3209 so that the distances between adjacent first electrodes 3201 are equal.

[0475] A noble metal or a noble metal alloy can be used as the material of the first electrode 3201. This is because the noble metal contained in the first electrode 3201 acts as a catalyst for water electrolysis and is not eluted even under acidic conditions. Examples of noble metal materials include platinum, iridium, and ruthenium.

[0476] Examples of the electrode form include a noble metal wire electrode alone, an electrode in which a noble metal wire is wound around the outer periphery of a support, or a mesh-shaped noble metal electrode. It is also possible to use a metal rod other than a noble metal, such as titanium (Ti), as the support, with a noble metal coated on the surface. However, since the presence of an interface between different metals is likely to cause deterioration due to the interface, it is preferable to use a noble metal or noble metal alloy alone.

[0477] The inner diaphragm 3215 is a water-permeable membrane that partitions the water softening chamber 3209 and the neutralization chamber 3210 to allow soft water to pass through. The inner surface of the inner diaphragm 3215 covers the outer surface of the water softening chamber 3209 and is in contact with the outer surface of the water softening chamber 3209. In addition, the outer surface of the inner diaphragm 3215 covers the inner surface of the neutralization chamber 3210 and is in contact with the inner surface of the neutralization chamber 3210.

[0478] As a result, the inner diaphragm 3215 separates the water softening chamber 3209 from the neutralization chamber 3210 while allowing the acidic soft water produced in the water softening chamber 3209 to pass through. Note that "covering" only requires that the membrane be positioned around the object, and does not necessarily require that the membrane completely enclose the object.

[0479] The neutralization chamber 3210 is a cylindrical space (second space 3212) located inside the casing 3109 on the outer circumferential side of the water softening chamber 3209 with respect to the central axis I of the casing 3109, and contains a weakly basic anion exchange resin 3214. The central axis of the neutralization chamber 3210 coincides with the central axis I of the casing 3109. The inner surface of the neutralization chamber 3210 contacts the outer surface of the inner circumferential diaphragm 3215, the outer surface of the neutralization chamber 3210 contacts the inner surface of the outer circumferential diaphragm 3216, which is a cylindrical membrane with water permeability, and the upper surface of the neutralization chamber 3210 contacts the lid 3208. The neutralization chamber 3210 is filled with the weakly basic anion exchange resin 3214, and is provided with a plurality of second electrodes 3202 (second electrode 3202a and second electrode 3202b are exemplified).

[0480] The weakly basic anion exchange resin 3214 is an ion exchange resin having tertiary amine and quaternary amine functional groups, and in this embodiment, a resin having a higher proportion of tertiary amine than quaternary amine is used.

[0481] The second electrode 3202 is not energized during the water softening process, and acts as a cathode during the regeneration process of the weakly basic anion exchange resin 3214. The second electrode 3202 is surrounded by the weakly basic anion exchange resin 3214 within the neutralization chamber 3210.

[0482] Here, "surrounded" refers to a state in which the surface of the second electrode 3202 is in contact with the surface of the weakly basic anion exchange resin 3214 from the top to the bottom around the entire periphery. However, like the weakly acidic cation exchange resin 3213, the weakly basic anion exchange resin 3214 usually has a spherical shape, and a water passage for the raw water (strictly speaking, acidic soft water) must be secured. For this reason, the term "second electrode 3202 is surrounded by the weakly basic anion exchange resin 3214" also applies to a state in which the weakly basic anion exchange resin 3214 is not in complete contact with the surface of the second electrode 3202, but is arranged around the entire periphery in a state of partial contact.

[0483] The upper end of the second electrode 3202 is located below the water surface in the neutralization chamber 3210 at the start of the regeneration process. A plurality of second electrodes 3202 are provided in the neutralization chamber 3210 so that the distance between adjacent second electrodes 3202 is equal.

[0484] A noble metal or a noble metal alloy can be used as the material of the second electrode 3202. This is because the noble metal contained in the second electrode 3202 acts as a catalyst for water electrolysis and is not eluted even under acidic conditions. Examples of noble metal materials include platinum, iridium, and ruthenium.

[0485] Examples of the electrode form include a noble metal wire electrode alone, an electrode in which a noble metal wire is wound around the outer periphery of a support, or a mesh-shaped noble metal electrode. Alternatively, a metal rod other than a noble metal, such as titanium (Ti), may be used as the support, with the surface coated with a noble metal. However, since the presence of an interface between dissimilar metals is likely to cause deterioration due to the interface, it is preferable to use a noble metal or noble metal alloy alone.

[0486] The arrangement of the first electrode 3201 and the second electrode 3202 will be described in detail later.

[0487] The water softening device 3100 includes an electrode cleaning circuit (a circuit including a power source) that connects the first electrode 3201 to the negative electrode and the second electrode 3202 to the positive electrode.

[0488] The outer peripheral diaphragm 3216 is a water-permeable membrane that partitions the neutralization chamber 3210 and the water supply section 3204 so that soft water can pass through between them. The inner surface of the outer peripheral diaphragm 3216 covers the outer surface of the neutralization chamber 3210 and is in contact with the outer surface of the neutralization chamber 3210. In addition, the outer surface of the outer peripheral diaphragm 3216 covers the inner surface of the water supply section 3204 and is in contact with the inner surface of the water supply section 3204.

[0489] This allows the soft water generated in the neutralization chamber 3210 to pass through while separating the neutralization chamber 3210 from the water supply section 3204. Note that "covering" only requires that the cover be positioned around the object, and does not necessarily require that the cover completely enclose the object.

[0490] The upper surfaces of the water conveying section 3203 , the water softening chamber 3209 , the inner diaphragm 3215 , the neutralization chamber 3210 , and the outer diaphragm 3216 are covered by the lid section 3208 .

[0491] The lid 3208 has a water-impermeable structure and may be made of, for example, a plate-shaped resin. The lid 3208 contacts and covers the upper surfaces of the water conveying section 3203, the water softening chamber 3209, the inner diaphragm 3215, the neutralization chamber 3210, and the outer diaphragm 3216, thereby separating the upper surfaces from the water supply section 3204, which will be described later.

[0492] This makes it possible to prevent water from flowing out from each upper surface into the water supply section 3204. In other words, the cover section 3208 makes it possible to form a water flow in which raw water flowing in from the water conveying section inlet 3207 passes through the water conveying section 3203, the water softening chamber 3209, the inner periphery-side diaphragm 3215, and the neutralization chamber 3210, and is sent out from the side surface of the outer periphery-side diaphragm 3216 into the side space 3204 a of the water supply section 3204.

[0493] The water supply unit 3204 supplies the soft water sent out from the neutralization chamber 3210 to a water supply unit outlet 3206 provided above the upper part of the neutralization chamber 3210. The central axis of the water supply unit 3204 coincides with the central axis I of the casing 3109.

[0494] The water supply part 3204 is provided with an air vent valve 3205 that vents air from inside the casing 3109. The water supply part 3204 includes a side space 3204a and an upper space 3204b.

[0495] The side space 3204a is a cylindrical space provided on the outer circumferential side of the neutralization chamber 3210 with respect to the central axis I of the casing 3109, and surrounding the neutralization chamber 3210. The side space 3204a is in contact with the outer surface of the outer circumferential diaphragm 3216 on the inner surface side of the cylindrical shape, and in contact with the inner surface of the casing 3109 on the outer surface side. In other words, the side space 3204a is a space provided between the inner surface of the casing 3109 and the outer surface of the outer circumferential diaphragm 3216.

[0496] In a direction parallel to the central axis I, the total length of the side space 3204a is longer than the total length of the neutralization chamber 3210, and when the side space 3204a and the bottom surfaces of the neutralization chamber 3210 are aligned on the same plane, the top surface of the side space 3204a protrudes upward above the top surface of the neutralization chamber 3210.

[0497] The upper space 3204b is a cylindrical space provided above the top surfaces of the water conveying section 3203, the water softening chamber 3209, the inner periphery diaphragm 3215, the neutralization chamber 3210, and the outer periphery diaphragm 3216. The cylindrical top surface of the upper space 3204b contacts the inner top wall of the casing 3109, and the cylindrical bottom surface of the upper space 3204b contacts the outer top wall of the lid section 3208. The outer surface of the cylindrical shape of the upper space 3204b contacts the inner surface of the side space 3204a.

[0498] The water supply unit outlet 3206 is provided on the top surface of the casing 3109, and discharges the water in the water supply unit 3204 to the outside of the water softening device 3100. The central axis of the water supply unit outlet 3206 coincides with the central axis I of the casing 3109. The water supply unit outlet 3206 is connected in communication with the softened water supply pipe 3105.

[0499] 23 , the soft water supply pipe 3105 is a pipe that connects the water supply unit outlet 3206 with the soft water supply destination, and is provided with a soft water conductivity measuring unit 3102 and a water volume measuring unit 3103 on its flow path. A drain pipe 3107 branches off from the soft water supply pipe 3105 midway along its flow path. A soft water supply pipe on-off valve 3106 is provided on the soft water supply pipe 3105 downstream of the branch point with the drain pipe 3107.

[0500] The soft water conductivity measuring unit 3102 calculates the total ion concentration of the soft water sent out from the water sending unit outlet 3206. The calculated total ion concentration information of the soft water is sent to the control unit 3110, which will be described later.

[0501] Any device capable of measuring the resistance of water can be used as the raw water conductivity measuring unit 3101 and the soft water conductivity measuring unit 3102 without any problems.

[0502] The drain pipe 3107 is a pipe branched off from the soft water supply pipe 3105 upstream of the soft water supply pipe on-off valve 3106, and is a pipe for draining water during the regeneration process. The drain pipe 3107 is provided with a drain pipe on-off valve 3108 on its flow path.

[0503] The water volume measuring unit 3103 is a component that measures the volume of water passed through the water softening device 3100, and can use a device such as a water meter that can measure the cumulative volume of water. The measured water volume information is sent to the control unit 3110, which will be described later.

[0504] The control unit 3110 controls the execution of each of the processes described below: water softening process, regeneration process, drainage process, cleaning process, and electrode cleaning process.

[0505] The control unit 3110 can be realized as hardware by elements and mechanical devices such as a computer CPU (Central Processing Unit), and as software by a computer program, etc. Therefore, these functional blocks can be realized in various forms by combining hardware and software.

[0506] The control unit 3110 includes an adsorption amount estimation unit 3111 , a storage unit 3112 , and a timer unit 3113 .

[0507] The adsorption amount estimation unit 3111 calculates the total amount of ions adsorbed in the water softening device 3100 using the total ion concentration of the raw water calculated by the raw water conductivity measurement unit 3101, the total ion concentration of the softened water calculated by the softened water conductivity measurement unit 3102, and the total amount of water passing through measured by the water volume measurement unit 3103.

[0508] The storage unit 3112 stores the various pieces of information transmitted to the control unit 3110 and the various pieces of information calculated by the control unit 3110 .

[0509] The timer 3113 measures the time elapsed since the start of the regeneration process, more specifically, the time elapsed since the start of energization of the first electrode 3201 and the second electrode 3202 .

[0510] The positions of the first electrode 3201 and the second electrode 3202 will be described in more detail with reference to FIG.

[0511] Figure 26 is a cross-sectional view showing the positions of the first electrode 3201 and the second electrode 3202 of the water softening device 3100, and is a cross-sectional view taken along the A-A' plane shown in Figure 25. The A-A' plane is parallel to the bottom surface of the water softening chamber 3209. In other words, the plane shown in Figure 26 is a cross section parallel to the bottom surface of the water softening chamber 3209.

[0512] In a plan view, the water conveying section 3203, the water softening chamber 3209, the neutralization chamber 3210, and the water supply section 3204 are all configured in a substantially circular shape. Therefore, in the cross-sectional view shown in Fig. 26, each cross section is a circle, and the centers of the circles are substantially the same (point O). The water softening chamber 3209, the inner diaphragm 3215, the neutralization chamber 3210, and the water supply section 3204 are arranged in this order toward the outer periphery of an imaginary circle X centered at point O. In this embodiment, the imaginary circle X coincides with the outer periphery of the water supply section 3204.

[0513] A plurality of first electrodes 3201 and a plurality of second electrodes 3202 are provided. A pair of first electrodes 3201 and second electrodes 3202 are provided on the same radius of an imaginary circle X. Note that "on the same radius" means on a radius in the same direction, and refers to, for example, line B in Fig. 26. In this embodiment, eight pairs of electrodes are provided on the same radius (same diameter) of the cylindrical shape of the casing 3109.

[0514] In the water softening process, as described above, raw water flows through the water softening device 3100 in the following order: water conveying section 3203, water softening chamber 3209, neutralization chamber 3210, and water supply section 3204. In other words, the raw water flows from the center (point O) of imaginary circle X toward the outer periphery of imaginary circle X.

[0515] Therefore, in the water softening chamber 3209, hardness ions are adsorbed in order starting from the weakly acidic cation exchange resin 3213 closest to the water conveying section 3203, and in the neutralization chamber 3210, hydrogen ions are adsorbed in order starting from the weakly basic anion exchange resin 3214 closest to the inner diaphragm 3215.

[0516] That is, the weakly acidic cation exchange resin 3213 and the weakly basic anion exchange resin 3214 are consumed from the center of the cross section in FIG.

[0517] Meanwhile, in the regeneration process, the first electrode 3201 generates hydrogen ions necessary for regenerating the weakly acidic cation exchange resin 3213 , and the second electrode 3202 generates hydroxide ions necessary for regenerating the weakly basic anion exchange resin 3214 .

[0518] Therefore, by providing the first electrode 3201 and the second electrode 3202 at positions where the respective ion exchange resins are consumed, the regeneration efficiency of the ion exchange resins in the regeneration process can be improved.

[0519] Here, the first boundary portion 3401, the second boundary portion 3402, the intermediate portion 3403, and the intermediate portion 3404 will be defined.

[0520] The first boundary portion 3401 is the boundary between the water conveying portion 3203 and the water softening chamber 3209 .

[0521] The second boundary portion 3402 is the boundary between the neutralization chamber 3210 and the water supply portion 3204. In other words, the second boundary portion 3402 is the outer peripheral diaphragm 3216.

[0522] The intermediate portion 3403 is a substantially circular imaginary line centered at point O, and is provided equidistant from the first boundary portion 3401 and the inner diaphragm 3215, and is equidistant from the first boundary portion 3401 and the inner diaphragm 3215 on the same radius.

[0523] The intermediate portion 3404 is a substantially circular imaginary line centered at point O, and is provided equidistant from the inner diaphragm 3215 and the second boundary portion 3402, and is equidistant from the inner diaphragm 3215 and the second boundary portion 3402 on the same radius.

[0524] The first electrode 3201 is provided at a position shifted toward the water conducting section 3203 from the midpoint between the inner periphery diaphragm 3215 and a first boundary section 3401, which is the boundary between the water conducting section 3203 and the water softening chamber 3209, on the same radius in the cross section of the water softening device 3100. In other words, on the same radius, the distance between the first electrode 3201 and the first boundary section 3401 is shorter than the distance between the first electrode 3201 and the inner periphery diaphragm 3215.

[0525] Furthermore, the second electrode 3202 is provided at a position shifted toward the inner diaphragm 3215 from the midpoint between the inner diaphragm 3215 and a second boundary portion 3402, which is the boundary between the neutralization chamber 3210 and the water supply portion 3204, on the same radius in the cross section of the water softener 3100. In other words, on the same radius, the distance between the second electrode 3202 and the inner diaphragm 3215 is shorter than the distance between the second electrode 3202 and the second boundary portion 3402.

[0526] By using such an arrangement, the hydrogen ions or hydroxide ions required for regeneration can be supplied directly near the region where each ion exchange resin is highly consumed, thereby improving the regeneration efficiency in the regeneration process.

[0527] The first electrode 3201 can be positioned without any particular limitation as long as it is closer to the center than an intermediate portion 3403 between the first boundary portion 3401 and the inner diaphragm 3215. Similarly, the second electrode 3202 can be positioned without any particular limitation as long as it is closer to the center than an intermediate portion 3404 between the inner diaphragm 3215 and the second boundary portion 3402. However, the shorter the distance between the pair of first electrode 3201 and second electrode 3202, the lower the voltage applied between the first electrode 3201 and the second electrode 3202, and the lower the power consumption. Therefore, from the perspective of reducing power consumption, it is preferable to position the first electrode 3201 and the second electrode 3202 close to each other. The first electrode 3201 and the second electrode 3202 may be arranged so that the ratio of the distance from the water guide section 3203 to the first electrode 3201 to the first distance from the first boundary section 3401 to the inner periphery diaphragm 3215 is equal to the ratio of the distance from the inner periphery diaphragm 3215 to the second electrode 3202 to the second distance from the inner periphery diaphragm 3215 to the second boundary section 3402.

[0528] The water softening device 3100 has the above configuration.

[0529] Next, the processes (water softening process, regeneration process, cleaning process, and electrode cleaning process) executed by the water softening device 3100 will be described with reference to FIGS. 27 and 28. FIG.

[0530] Fig. 27 is a diagram including formulas showing the principle of the water softening device 3100 in embodiment 9. Fig. 28 is a diagram showing the change over time in the rate of hydrogen ion consumption by the weakly acidic cation exchange resin during the regeneration process.

[0531] First, the operation of the water softening device 3100 in the water softening process and the principle of the water softening process will be described.

[0532] 24 and 25 , in the water softening device 3100, raw water flows from the outside into the lower part of the water conveying section 3203 through the water conveying section inlet 3207. The flowing raw water is sent from the lower part to the upper part of the water conveying section 3203 and flows out in the radial direction of the casing 3109 from holes provided in the side wall of the water conveying section 3203. In other words, the raw water is sent out from the holes in the water conveying section 3203 to the water softening chamber 3209.

[0533] The raw water sent to the water softening chamber 3209 is softened by the weakly acidic cation exchange resin 3213 filled inside the water softening chamber 3209. In detail, hardness components (calcium ions or magnesium ions) in the raw water are exchanged with hydrogen ions adsorbed on the weakly acidic cation exchange resin 3213, and the raw water becomes acidic soft water containing hydrogen ions.

[0534] The acidic softened water produced in the water softening chamber 3209 passes through the inner diaphragm 3215, which is a water-permeable membrane, and flows into the neutralization chamber 3210, where it is neutralized. Specifically, hydrogen ions in the softened water are removed from the softened water by being adsorbed onto the weakly basic anion exchange resin 3214, and neutral softened water (neutralized softened water) is produced. During this neutralization reaction, anions such as sulfate ions contained in the softened water are also adsorbed onto the weakly basic anion exchange resin 3214.

[0535] The neutralized soft water produced in the neutralization chamber 3210 passes through the outer peripheral diaphragm 3216 , which is a water-permeable membrane, and flows into the water supply section 3204 .

[0536] The softened water that flows into the water supply section 3204 flows upward, rises in the side space 3204a of the water supply section 3204, and flows into the upper space 3204b of the water supply section 3204. The softened water that flows into the upper space 3204b flows toward the center of the upper space 3204b and is taken out from the water supply section outlet 3206 provided in the center of the top surface of the water softening device 3100.

[0537] In this way, the raw water is softened in the water softening process.

[0538] In the water softening process, if the amount of cations (more specifically, hardness ions such as calcium ions or magnesium ions) adsorbed onto the weakly acidic cation exchange resin 3213 or the amount of anions adsorbed onto the weakly basic anion exchange resin 3214 increases, the resin's water softening performance will decrease, and a regeneration process will be required.

[0539] In the regeneration process, first, raw water flows from a raw water supply source into the water conveying section 3203 via the water conveying section inlet 3207, and the flowing raw water is sent to the water softening chamber 3209 and the neutralization chamber 3210. Next, electricity is passed through each electrode so that the first electrode 3201 surrounded by the weakly acidic cation exchange resin 3213 has a higher potential than the second electrode 3202 surrounded by the weakly basic anion exchange resin 3214.

[0540] As a result, a reaction that produces hydrogen ions (see formula (35) in FIG. 27) occurs at the first electrode 3201, which is an anode, and a reaction that produces hydroxide ions (see formula (36) in FIG. 27) occurs at the second electrode 3202, which is a cathode. In other words, hydrogen ions are produced in the water softening chamber 3209, and hydroxide ions are produced in the neutralization chamber 3210.

[0541] When the weakly acidic cation exchange resin 3213, which has absorbed hardness components during the water softening process, is exposed to hydrogen ions, an exchange reaction between the hardness components and the hydrogen ions occurs, thereby regenerating the weakly acidic cation exchange resin 3213.

[0542] Furthermore, when the weakly basic anion exchange resin 3214 to which anions have been adsorbed in the water softening process is exposed to hydroxide ions, an exchange reaction between the adsorbed anions and the hydroxide ions occurs, thereby regenerating the weakly basic anion exchange resin 3214.

[0543] In this manner, the weakly acidic cation exchange resin 3213 and the weakly basic anion exchange resin 3214 are regenerated in the regeneration process.

[0544] In the regeneration process, the water softening device 3100 sets the regeneration time based on the conductivity of the raw water or softened water before and after passing through the casing 3109 or the amount of water that has passed through the casing 3109 .

[0545] Specifically, at the start of the water softening process, raw water conductivity measuring unit 3101 is activated and measures the conductivity of raw water flowing through raw water supply pipe 3104. Also, soft water conductivity measuring unit 3102 is activated and measures the conductivity of soft water flowing through soft water supply pipe 3105. Furthermore, water volume measuring unit 3103 measures the volume of water that has flowed through casing 3109. The measured raw water conductivity, soft water conductivity, and water volume are transmitted to control unit 3110 and stored in memory unit 3112.

[0546] The ions removed in the water softening chamber 3209 are mainly Mg ２＋ , and Ca ２＋ The ions removed in the neutralization chamber 3210 are mainly HCO ３ － , Cl － , and S.O. ４ ２－ are anions. According to the principle of electroneutrality, the number of moles of cations adsorbed in the water softening chamber 3209 is equal to the number of moles of anions adsorbed in the neutralization chamber 3210. Therefore, the difference between the conductivity measured by the raw water conductivity measuring unit 3101 and the conductivity measured by the softened water conductivity measuring unit 3102 is derived from the total amount of Mg salts and Ca salts removed by the water softening device 3100. In this way, because the conductivity difference is the value of the removed ion concentration, it is possible to respond to changes in the water quality of the raw water and softened water, and the amount of adsorption can be calculated with high accuracy.

[0547] The adsorption amount estimation unit 3111 estimates the amount of ions adsorbed in the water softening device 3100. Specifically, it calculates the difference between the conductivity of the raw water stored in the memory unit 3112 and the conductivity of the softened water. This difference is the concentration of ions adsorbed in the water softening device 3100. The adsorption amount estimation unit 3111 multiplies the ion concentration obtained as the difference by the total amount of water passing through measured by the water amount measurement unit 3103. In this way, the amount of ions adsorbed in the water softening device 3100 during the regeneration process is estimated.

[0548] Here, the current value and current application time required to remove the estimated adsorbed ions from the water softening device 3100 and to regenerate the water softening device 3100 will be described with reference to FIGS. 27 and 28. FIG.

[0549] In the regeneration process, one mole of electrons is converted to H ＋1 mole of electrons to OH － To release 1 mole of hardness ions from the resin, 1 mole of H ＋ Therefore, the number of moles of ions adsorbed in the water softening chamber 3209 and the number of moles of H required for resin regeneration are ＋ The relationship between the current value, the current value, and the time is expressed by equation (32) in FIG.

[0550] The control unit 3110 determines the current value and current application time required to regenerate the weakly acidic cation exchange resin 3213 and the weakly basic anion exchange resin 3214 from the number of adsorbed ion moles estimated by the adsorption amount estimation unit 3111 and equation (32) in Figure 27.

[0551] In the water softening device 3100, it is preferable to change the value of the applied current as the regeneration process progresses. The reason for this will be explained below.

[0552] As the regeneration process progresses, the ions adsorbed during the water softening process are released into the water from the weakly acidic cation exchange resin 3213 and the weakly basic anion exchange resin 3214, increasing the ion concentration in the water. In other words, as time elapses since the start of the regeneration process, the conductivity of the water in the water softening device 3100 increases compared to when power was first applied, and the voltage decreases. On the other hand, at the start of power application, the ion concentration of the water in the water softening device 3100 is low, so the voltage is high. Therefore, if the current value is kept constant from the start of power application, the voltage will be high at the start of power application and will gradually decrease as power application time passes.

[0553] At the end of the regeneration process, (R-COO － ) ２ Ca ２＋ , and R ３ -NH ＋ Cl ―As the concentration of hydrogen ions decreases, the regeneration rate slows down. As a result, as shown in Figure 28, the consumption rate of the introduced hydrogen ions decreases, and the conversion rate drops. When the consumption rate is low, even if hydrogen ions or hydroxide ions in a concentration greater than the concentration that can be consumed by the resin are introduced into the weakly acidic cation exchange resin 3213 or the weakly basic anion exchange resin 3214, they will not react with the ions in the resin but will react with each other, resulting in a loss.

[0554] In other words, according to the voltage characteristics at the beginning of the regeneration process described above, when applying current, it is preferable to gradually increase the current rather than immediately increasing it to the current value determined by the adsorption amount estimation unit 3111. This keeps the voltage low, thereby reducing power consumption.

[0555] Furthermore, due to the reactivity of the resin, it is preferable to gradually reduce the current towards the end of the regeneration process, which prevents excess ions from reacting with each other, reduces current waste, and reduces power consumption.

[0556] In order to measure such a change in the applied current over time, a timer unit 3113 is used.

[0557] The storage unit 3112 stores a first reference value that maximizes the current and a second reference value that starts decreasing the current from the maximum value as reference times indicating the timing to change the current. The first reference value is set to about 30 minutes to 1 hour after the start of current application. The second reference value is set to a time later than the first reference value and 30 minutes to 1 hour before the end of current application.

[0558] The current and time required for the regeneration process are determined by the adsorbed hardness, as shown in equation (32) in Figure 27. Therefore, if the time from the start of current flow to the first reference value and the time from the end of current flow to the second reference value are increased, the maximum current value or regeneration time must be increased.

[0559] The timer 3113 measures the elapsed time from the start of current application to the first electrode 3201 and the second electrode 3202. When the elapsed time measured by the timer 3113 reaches a first reference value, the controller 3110 stops increasing the applied current value and maintains the current value. Thereafter, when the elapsed time measured by the timer 3113 reaches a second reference value, the controller 3110 decreases the applied current value. Note that the increase in the current value from the start of current application to the first reference value, or the decrease in the current value from the second reference value to the end of current application, may be changed linearly or in a stepwise manner.

[0560] In the regeneration process, a determined current value is applied to the first electrode 3201 and the second electrode 3202 for a determined current application time, and the weakly acidic cation exchange resin 3213 and the weakly basic anion exchange resin 3214 are regenerated.

[0561] After the regeneration process is complete, high concentrations of ions released from the weakly acidic cation exchange resin 3213 and the weakly basic anion exchange resin 3214 remain in the water softening chamber 3209 and the neutralization chamber 3210. Therefore, it is necessary to perform a cleaning operation inside the water softening device 3100. If the cleaning is insufficient, the remaining ions will mix with the water during the water softening process, which could result in insufficient water softening. Therefore, a cleaning process is performed after the regeneration process is complete.

[0562] During the cleaning process, in the water softening device 3100, the softened water supply pipe on-off valve 3106 is closed and the drain pipe on-off valve 3108 is opened, thereby draining the water in the water softening chamber 3209 and the neutralization chamber 3210 out of the water softening device 3100 via the drain pipe 3107. Then, raw water flows in from the raw water supply pipe 3104, making it possible to resume the regeneration process.

[0563] When the end of the washing process is determined by time, the washing time, which is the time from the start to the end of the washing process, is set to be longer than the residence time, which is the time from when the raw water flows into the water softening chamber 3209 to when it flows out of the neutralization chamber 3210. This allows water containing a large amount of desorbed hardness ions present in the water softening chamber 3209 to be discharged, and the water in the water softening chamber 3209 to be replaced with raw water.

[0564] During the regeneration process, solid calcium carbonate and the like adhere to the electrode surface of the second electrode 3202. If the amount of calcium carbonate deposited on the electrode surface increases, problems such as an increase in voltage when current is applied and difficulty in peeling calcium carbonate from the electrode surface occur. Therefore, it is necessary to periodically perform an electrode cleaning process to remove calcium carbonate from the cathode surface.

[0565] In the electrode cleaning process, the first electrode 3201 is connected to the negative electrode and the second electrode 3202 is connected to the positive electrode, that is, the electrode polarity is reversed from that in the regeneration process, and the electrode cleaning is performed. ＋ is generated, and calcium carbonate on the surface of the second electrode 3202 reacts with H ＋ The electrode cleaning process is carried out during or after the regeneration process is completed.

[0566] In this manner, in the water softening device 3100, the softening of raw water by the water softening process, and the maintenance of the water softening device 3100 by the regeneration process, cleaning process, and electrode cleaning process are repeatedly performed.

[0567] (Effects, etc.) As described above, the water softening device 3100 according to this embodiment can provide the following effects.

[0568] (1) The water softening device 3100 includes a water softening chamber 3209 having a weakly acidic cation exchange resin 3213 and producing soft water from raw water containing hardness components, a neutralization chamber 3210 having a weakly basic anion exchange resin 3214 and neutralizing the soft water, an inner diaphragm 3215 that partitions the space between the water softening chamber 3209 and the neutralization chamber 3210 so that soft water can pass through, a water conveying section 3203 that introduces raw water from the outside into the water softening chamber 3209, and a neutralization chamber 3210 that neutralizes the soft water. The apparatus includes a water supply section 3204 that supplies the neutralized softened water to the outside, a first electrode 3201 that is provided in the water softening chamber 3209 and surrounded by a weakly acidic cation exchange resin 3213, and acts as an anode during regeneration of the weakly acidic cation exchange resin 3213, and a second electrode 3202 that is provided in the neutralization chamber 3210 and surrounded by a weakly basic anion exchange resin 3214, and acts as a cathode during regeneration of the weakly basic anion exchange resin 3214. The water softening chamber 3209, an inner diaphragm 3215, a neutralization chamber 3210, and a water supply section 3204 are arranged in this order from the water supply section 3203 having a central axis I perpendicular to the bottom surface of the water softening chamber 3209 toward the outer periphery of a circle centered on the central axis I. The first electrode 3201 is arranged in the water softening chamber 3209 at a position biased toward the water supply section 3203.

[0569] More specifically, the first electrode 3201 is positioned on the water conducting section 3203 side of the midpoint between the first boundary section 3401, which is the boundary between the water conducting section 3203 and the water softening chamber 3209, and the inner diaphragm 3215, on the same radius of a circle in a cross section parallel to the bottom surface of the water softening chamber 3209.

[0570] With this configuration, during the regeneration process, hydrogen ions can be generated near the weakly acidic cation exchange resin 3213, which has a large amount of hardness ion adsorption, in the water softening chamber 3209. This prevents the generated hydrogen ions from reacting with other ions and being lost before being used to regenerate the weakly acidic cation exchange resin 3213, thereby improving the regeneration efficiency.

[0571] (2) In the water softening device 3100, the second electrode 3202 is disposed in the neutralization chamber 3210 at a position biased toward the inner diaphragm 3215 side.

[0572] More specifically, the second electrode 3202 is positioned on the same radius closer to the inner diaphragm 3215 than the midpoint between the inner diaphragm 3215 and the second boundary portion 3402, which is the boundary between the neutralization chamber 3210 and the water supply section 3204.

[0573] With this configuration, during the regeneration process, hydroxide ions can be generated near the weakly basic anion exchange resin 3214, which has a large ion adsorption capacity, in the neutralization chamber 3210. This prevents the generated hydroxide ions from reacting with other ions and being lost before being used to regenerate the weakly basic anion exchange resin 3214, thereby improving the regeneration efficiency.

[0574] (3) In the water softening device 3100, the pair of first electrode 3201 and second electrode 3202 are arranged on the same radius in a cross section parallel to the bottom surface of the water softening chamber 3209, and are arranged at a position where the ratio of the distance from the water conducting section 3203 to the first electrode 3201 to the first distance from the first boundary section 3401 to the inner diaphragm 3215 is equal to the ratio of the distance from the inner diaphragm 3215 to the second distance from the inner diaphragm 3215 to the second boundary section 3402.

[0575] With this configuration, the first electrode 3201 and the second electrode 3202 are both disposed at the same position from the center side in each chamber.

[0576] The present disclosure has been described above based on the embodiments. These embodiments are excitation, and it will be understood by those skilled in the art that various modifications are possible in the combination of each component or each process, and that such modifications are also within the scope of the present disclosure.

[0577] (Modification) In the ninth embodiment, the first electrode 3201 is offset toward the center of the circle from the midpoint between the first boundary 3401 and the inner diaphragm 3215, and the second electrode 3202 is offset toward the center of the circle from the midpoint between the inner diaphragm 3215 and the second boundary 3402. However, the present disclosure is not limited to this. For example, only the first electrode 3201 may be offset toward the center from the midpoint between the first boundary 3401 and the inner diaphragm 3215. The water softening device according to the present disclosure can reduce the frequency of drainage or even eliminate drainage altogether, thereby reducing the amount of water drained. As a secondary effect, it is possible to shorten the regeneration time and extend the life of the electrodes, and therefore is useful as a water softening device, etc.

[0578] The water softening device according to the present disclosure can reduce the frequency of drainage or eliminate the need for drainage altogether, thereby reducing the amount of drainage, and as a secondary effect, can also shorten the regeneration time and increase the electrode life, making it useful as a water softening device, etc.

[0579] 100 Water softening device 101 Weakly acidic cation exchange resin 102 Weakly basic anion exchange resin 103, 103a, 103b First electrode 104, 104a, 104b Second electrode 105 Inner diaphragm 106 Outer diaphragm 107 Water conveying section 108 Water conveying section 108a Side space 108b Upper space 109 Air vent valve 110 Water conveying section outlet 111 Water conveying section inlet 112 Lid 113 Boundary line 201 Water softening chamber 202 Neutralization chamber 203 Casing 204 First space 205 Second space I Central axis S, T, V, W Distance 1100, 1100b, 1100c, 1100d, 1100e, 1100f Water softening device 1101 Raw water conductivity measuring unit 1102 Soft water conductivity measuring unit 1103 Water volume measuring unit 1104, 1104a, 1104b Raw water supply pipe 1105, 1105a Soft water supply pipe 1106 Soft water supply pipe on / off valve 1107, 1107a Drain pipe 1108 Drain pipe on / off valve 1109 Casing 1110 Control unit 1111 Adsorption amount estimating unit 1112 Memory unit 1113 Timer unit 1201, 1201a, 1201b First electrode 1202, 1202a, 1202b Second electrode 1203 Water conveying unit 1204 Water conveying unit 1204a Side space 1204b Upper space 1205 Air vent valve 1206 Water conveying section outlet 1207 Water conveying section inlet 1208 Lid section 1209 Water softening chamber 1210 Neutralization chamber 1211 First space 1212 Second space 1213 Weakly acidic cation exchange resin 1214 Weakly basic anion exchange resin 1215 Inner circumference side diaphragm 1216 Outer circumference side diaphragm 1301 Chemical addition piping 1302 Chemical sustained release section 1303 Chemical addition piping on / off valve 1304 Raw water supply piping on / off valve 1401 Storage chamber 1402 Inlet 1403 First water conveying port 1404 Second water conveying port 1405 Reclaimed water return piping 1406 Reclaimed water return piping on / off valve 1501, 1501a, 1501b Water softening module 1502 Connecting pipe 1503a, 1503b, 1503c conductivity meter1601 Upstream drain pipe 1602 Drain valve 1603 Drain water volume measurement unit 2100 Water softening device 2101 Raw water conductivity measurement unit 2102 Softened water conductivity measurement unit 2103 Water volume measurement unit 2104 Raw water supply pipe 2105 Softened water supply pipe 2106 Softened water supply pipe on / off valve 2107 Drain pipe 2108 Drain pipe on / off valve 2109 Casing 2110 Control unit 2111 Adsorption amount estimation unit 2112 Memory unit 2113 Timer unit 2114 Bypass pipe 2115 Bypass pipe on / off valve 2201, 2201a, 2201b First electrode 2202, 2202a, 2202b Second electrode 2203 Water conveyance unit 2204 Water conveyance unit 2204a Side space 2204b Upper space 2205 Air vent valve 2206 Water supply section outlet 2207 Water conveyance section inlet 2208 Lid 2209 Water softening chamber 2210 Neutralization chamber 2211 First space 2212 Second space 2213 Weakly acidic cation exchange resin 2214 Weakly basic anion exchange resin 2215 Inner circumference side diaphragm 2216 Outer circumference side diaphragm 3100 Water softening device 3101 Raw water conductivity measuring section 3102 Softened water conductivity measuring section 3103 Water volume measuring section 3104 Raw water supply pipe 3105 Softened water supply pipe 3106 Softened water supply pipe on / off valve 3107 Drain pipe 3108 Drain pipe on / off valve 3109 Casing 3110 Control section 3111 Adsorption amount estimation section 3112 Memory section 3113 Timer section 3201, 3201a, 3201b First electrode 3202, 3202a, 3202b Second electrode 3203 Water conveying section 3204 Water conveying section 3204a Side space 3204b Upper space 3205 Air vent valve 3206 Water conveying section outlet 3207 Water conveying section inlet 3208 Lid section 3209 Water softening chamber 3210 Neutralization chamber 3211 First space 3212 Second space 3213 Weakly acidic cation exchange resin 3214 Weakly basic anion exchange resin 3215 Inner circumference side diaphragm 3216 Outer circumference side diaphragm 3401 First boundary section 3402 Second boundary section 3403 Intermediate section3404 Middle section

Claims

1. A water softening device comprising: a water softening chamber having a weakly acidic cation exchange resin and producing soft water from raw water containing hardness components; a neutralization chamber having a weakly basic anion exchange resin and neutralizing the soft water; a diaphragm that partitions the water softening chamber and the neutralization chamber to allow the soft water to pass through; a first electrode that acts as an anode when the weakly acidic cation exchange resin is regenerated; and a second electrode that acts as a cathode when the weakly basic anion exchange resin is regenerated, wherein the first electrode is disposed within the water softening chamber and surrounded by the weakly acidic cation exchange resin, and the second electrode is disposed within the neutralization chamber and surrounded by the weakly basic anion exchange resin.

2. The water softening device according to claim 1, wherein the first electrode is provided in contact with the weakly acidic cation exchange resin, and the second electrode is provided in contact with the weakly basic anion exchange resin.

3. The water softening device of claim 1, wherein the upper end of the first electrode is positioned below the water level in the water softening chamber at the start of regeneration of the weak acid cation exchange resin, thereby forming a space above the upper end, and the distance from the bottom surface of the water softening chamber to the lower end of the first electrode is shorter than the distance from the water level to the upper end of the first electrode, and the weak acid cation exchange resin is filled in the space around and above the first electrode within the water softening chamber.

4. The water softening device described in claim 1, wherein the upper end of the second electrode is positioned below the water level in the neutralization chamber at the start of regeneration of the weakly basic anion exchange resin, thereby forming a space above the upper end, and the distance from the bottom surface of the neutralization chamber to the lower end of the second electrode is shorter than the distance from the water level to the upper end of the second electrode, and the weakly basic anion exchange resin is filled in the space around and above the second electrode within the neutralization chamber.

5. The water softening device according to claim 1, further comprising a cylindrical casing having the water softening chamber and the neutralization chamber therein, the neutralization chamber being disposed on the outer periphery of the water softening chamber with respect to the cylindrical central axis of the casing and surrounding the water softening chamber.

6. The water softening device according to claim 5, further comprising a water conveying section that introduces the raw water into the water softening chamber, the water conveying section being provided from the bottom to the top of the water softening chamber, and the raw water being discharged from a side surface of the water conveying section in an outer circumferential direction relative to the central axis of the cylinder.

7. A water softening device as described in claim 5, further comprising a water supply section provided on the outer periphery of the neutralization chamber relative to the central axis of the cylinder and surrounding the neutralization chamber, wherein the water supply section supplies the water within the neutralization chamber that has been discharged from the neutralization chamber in the outer periphery direction relative to the central axis to the outside of the device from above the top of the neutralization chamber.

8. The water softening device according to claim 5, wherein the pair of first and second electrodes are provided on the same radius when viewed in a plan view of the casing.

9. The water softening device according to claim 1, wherein the amount of the weakly basic anion exchange resin packed therein is equal to or greater than the amount of the weakly acidic cation exchange resin packed therein.

10. The water softening device according to claim 1, wherein the diaphragm is a membrane that is water permeable and has a pore size smaller than the particle size of the weakly acidic cation exchange resin and the particle size of the weakly basic anion exchange resin.

11. The system further comprises a control unit for controlling the regeneration of the weak acidic cation exchange resin and the weak basic anion exchange resin, the control unit being configured to: perform a water softening process in which water to be treated is introduced from the bottom of the water softening chamber and passed through the water softening chamber and then the neutralization chamber to obtain soft water; a regeneration process in which current is passed through the first electrode and the second electrode to generate hydrogen ions from the first electrode by water electrolysis and hydroxide ions from the second electrode, regenerate the weak acidic cation exchange resin with the generated hydrogen ions, and regenerate the weak basic anion exchange resin with the generated hydroxide ions; and a cleaning process in which cations released from the weak acidic cation exchange resin by the regeneration process are discharged from the water softening chamber and anions released from the weak basic anion exchange resin are discharged from the neutralization chamber.

2. The water softening apparatus according to claim 1, wherein during or after the regeneration process, the first electrode is connected to a negative electrode, the second electrode is connected to a positive electrode, and an electrode cleaning process is carried out to dissolve solids attached to a surface of the second electrode during the regeneration process.

12. A water softening device as described in claim 11, further comprising a water volume measuring unit that measures the volume of the raw water passed through the water softening chamber; a raw water conductivity measuring unit that measures the conductivity of the raw water before contact with the cation exchange resin; a soft water conductivity measuring unit that measures the conductivity of the neutralized soft water after contact with the anion exchange resin; and an adsorption amount estimating unit that estimates the amount of ions adsorbed into the water softening chamber during the water softening process, wherein the adsorption amount estimating unit estimates the amount of ions adsorbed into the water softening chamber during the water softening process based on the volume of the raw water measured by the water volume measuring unit, the conductivity of the raw water measured by the raw water conductivity measuring unit, and the conductivity of the neutralized soft water measured by the soft water conductivity measuring unit.

13. The water softening device according to claim 12, wherein the control unit sets an execution time of the regeneration process based on the amount of ion adsorption estimated by the adsorption amount estimation unit.

14. The water softening device according to claim 11, further comprising an electrolyte input section for inputting an electrolyte other than the hydrogen ions and the hydroxide ions into the water softening chamber and the neutralization chamber during the regeneration process.

15. The water softening device according to claim 14, wherein the electrolyte input section causes the raw water containing the hardness components to flow into the water softening chamber and the neutralization chamber before the energization in the regeneration process.

16. The water softening apparatus according to claim 14, wherein the electrolyte input unit adds a chemical containing the electrolyte to the raw water.

17. The water softening device according to claim 14, wherein the electrolyte input section inputs wastewater containing at least one of the cations or the anions discharged in the cleaning process carried out prior to the regeneration process into the water softening chamber and the neutralization chamber before the application of current in the regeneration process.

18. A water softening device as described in claim 17, further comprising a storage chamber for storing the wastewater, the storage chamber comprising: a housing; an inlet provided in an upper part of the housing for allowing the wastewater to flow into the housing; a first water supply port provided in the upper part of the housing for discharging the wastewater outside the housing; and a second water supply port provided in a lower part of the housing for supplying the wastewater to the water softening chamber, and the electrolyte input section inputs the wastewater supplied from the second water supply port into the water softening chamber.

19. The water softening device according to claim 11, wherein the control unit includes an adsorption amount estimation unit that specifies the amount of ions adsorbed into the water softening chamber, and in the regeneration process, the control unit controls the current values ​​passed through the first electrode and the second electrode based on the amount of ions adsorbed estimated by the adsorption amount estimation unit.

20. The water softening device according to claim 19, further comprising a timing unit that measures the elapsed time from the start of the regeneration process, and the control unit changes the current value applied to the first electrode and the second electrode based on the elapsed time measured by the timing unit.

21. The water softening device according to claim 20, wherein the control unit increases the value of the current applied to the first electrode and the second electrode when the elapsed time exceeds a specific first reference value.

22. The water softening device according to claim 19, further comprising a voltage measuring unit that measures a voltage when a current is applied, and the control unit changes the value of the current applied to the first electrode and the second electrode based on an amount of change in the voltage measured by the voltage measuring unit.

23. A water softening device as described in claim 11, comprising a plurality of water softening modules each having the water softening chamber, the neutralization chamber, and the diaphragm, and further comprising an adsorption amount estimation unit that identifies the amount of ions adsorbed into the water softening chamber of each of the plurality of water softening modules, and during the regeneration process, the control unit changes at least one of the current value passed through each of the plurality of water softening modules and the time for which current is passed, based on the amount of ions adsorbed estimated by the adsorption amount estimation unit.

24. The water softening device according to claim 11, wherein the control unit executes a drainage process for draining the acidic electrolyzed water in the water softening chamber and the alkaline electrolyzed water in the neutralization chamber to the outside of the device during the regeneration process.

25. The water softening device according to claim 24, wherein a drain time, which is the time from the start to the end of the drain process, is longer than a residence time, which is the time from when the raw water flows into the water softening chamber to when it flows out of the neutralization chamber.

26. A water softening device as described in claim 24, further comprising a water volume measuring unit that measures the volume of the softened water flowing out of the neutralization chamber, wherein the control unit, during the drainage process, continues execution of the drainage process if the water volume measured by the water volume measuring unit from the start of the drainage process is less than the volume of the water softening chamber and the neutralization chamber, and terminates the drainage process if the water volume measured by the water volume measuring unit from the start of the drainage process is equal to or greater than the volume of the water softening chamber and the neutralization chamber.

27. The water softening device according to claim 11, wherein a washing time, which is the time from the start to the end of the washing process, is longer than a residence time, which is the time from when the raw water flows into the water softening chamber to when it flows out of the neutralization chamber.

28. The water softening device of claim 11, further comprising a water volume measuring unit that measures the volume of the softened water flowing out of the neutralization chamber, and the control unit terminates the cleaning process when the water volume measured by the water volume measuring unit from the start of the cleaning process becomes greater than the volume of the water softening chamber and the neutralization chamber.

29. The water softening device of claim 11, further comprising: a raw water conductivity measuring unit that determines the conductivity of the raw water; and a wastewater conductivity measuring unit that determines the conductivity of the wastewater flowing out of the neutralization chamber during the cleaning process, wherein the control unit terminates the cleaning process when the conductivity of the wastewater determined by the wastewater conductivity measuring unit becomes equal to the conductivity of the raw water determined by the raw water conductivity measuring unit.

30. The water softening device according to claim 11, wherein the control unit further performs an electrode cleaning process during the regeneration process or after completion of the regeneration process, by connecting the first electrode to a negative electrode and connecting the second electrode to a positive electrode, and dissolving solids that have adhered to a surface of the second electrode during the regeneration process.

31. A water softening device as claimed in claim 1, further comprising: a water conveying section located on the inner periphery of the water softening chamber and supplying the raw water to the water softening chamber; a water conveying section which conveys the neutralized soft water produced in the neutralization chamber to the outside; and a control section which controls the regeneration of the weakly acidic cation exchange resin, wherein the neutralization chamber is located on the outer periphery of the water softening chamber, and the control section executes: a water softening process in which the raw water is introduced from the water conveying section and passed through the water softening chamber and then the neutralization chamber to obtain the neutralized soft water; a regeneration process in which, after the water softening process is executed for a predetermined period of time, water is electrolyzed and the weakly acidic cation exchange resin is regenerated using the generated hydrogen ions; and a drainage process in which cations released from the weakly acidic cation exchange resin by the regeneration process are discharged from the water softening chamber and anions released from the weakly basic anion exchange resin are discharged from the neutralization chamber, and during the drainage process, water containing the cations is discharged from the water conveying section.

32. The water softening device according to claim 31, wherein the amount of drainage in the drainage process is smaller than the sum of the volume of the water conveying section, the volume of the water softening chamber, and the volume of the neutralization chamber.

33. The water softening apparatus of claim 31, wherein the weakly acidic cation exchange resin is filled in the water softening chamber, the weakly basic anion exchange resin is filled in the neutralization chamber, and the amount of drainage in the drainage process is smaller than the sum of the volume of the part of the water softening chamber other than that occupied by the weakly acidic cation exchange resin and the volume of the part of the water softening chamber other than that occupied by the weakly basic anion exchange resin.

34. The water softening device according to claim 31, wherein the weakly acidic cation exchange resin is filled in the water softening chamber, and the amount of drainage in the drainage process is greater than the volume of the water softening chamber other than the portion occupied by the weakly acidic cation exchange resin.

35. The water softening apparatus according to claim 31, wherein the control unit performs the draining process multiple times during the regeneration process.

36. The water softening apparatus according to claim 35, wherein in the regeneration process, the control unit applies a voltage between the first electrode and the second electrode, and determines whether to execute the drainage process based on the applied voltage.

37. The water softening apparatus according to claim 31, wherein raw water supplied during the drainage process flows in from the water conveying section side.

38. A water softening device as described in claim 1, further comprising: a water conducting section which introduces the raw water from the outside into the water softening chamber; and a water supply section which supplies the neutralized soft water produced in the neutralization chamber to the outside, wherein the water softening chamber, the diaphragm, the neutralization chamber, and the water supply section are arranged in this order from the water conducting section, which has a central axis perpendicular to the bottom surface of the water softening chamber, toward the outer periphery of a circle centered on the central axis, and the first electrode is arranged in a position biased toward the water conducting section within the water softening chamber.

39. The water softening device according to claim 38, wherein the second electrode is disposed in the neutralization chamber at a position biased toward the diaphragm.

40. A water softening device as described in claim 38, wherein the first electrode is positioned on the water conducting side of a midpoint between the diaphragm and a first boundary portion which is a boundary between the water conducting portion and the water softening chamber, on the same radius of the circle in a cross section parallel to the bottom surface of the water softening chamber.

41. The water softening device according to claim 40, wherein the second electrode is disposed on the same radius on the diaphragm side of a midpoint between the diaphragm and a second boundary portion which is a boundary between the neutralization chamber and the water supply portion.

42. A water softening device as described in claim 41, wherein a pair of the first electrode and the second electrode are provided on the same radius in the cross section, and are provided at positions where a ratio of a distance from the water-conducting portion to the first electrode to a first distance from the first boundary portion to the diaphragm is equal to a ratio of a distance from the diaphragm to the second electrode to a second distance from the diaphragm to the second boundary portion.

Images