Water softener

Abstract

To provide a water softener capable of suppressing waste water on regeneration and efficiently regenerating resin.SOLUTION: A water softener 100 includes 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 barrier membrane that partitions between the water softening chamber 201 and the neutralization chamber 202 in a manner enabling conduction of soft water, a first electrode 103 that acts as an anode on regeneration of the weakly acidic cation-exchange resin 101, and a second electrode 104 that acts as a cathode on regeneration of the weakly basic anion-exchange resin 102. The first electrode 103 is provided in the water softening chamber 201 and surrounded with the weakly acidic cation-exchange resin 101. The second electrode 104 is provided in the neutralization chamber 202 and surrounded with the weakly basic anion-exchange resin 102.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a water softening device that utilizes ion exchange resin. [Background technology]

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

[0003] Furthermore, in order to solve the issues of the workload involved in replenishing salt 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 (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 the electrodes and a cation exchange resin membrane on the cathode side.

[0005] In both of the conventional techniques, the resin needs to be regenerated when a certain amount of hardness ions are adsorbed onto the resin. For example, in the regeneration process in Patent Document 1, electrodes are used to apply a voltage to the BP membrane and resin chamber that are present between the electrodes. The BP membrane or ion exchange resin chamber has an interface between a cation exchange resin and an anion exchange resin. When a voltage is applied to this interface, water molecules are split into 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 [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6444939 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the technology described in Patent Document 1, the hardness ions released from the ion exchange resin are re-adsorbed on the ion exchange resin, which tends to inhibit the reaction during regeneration of the resin. Therefore, in order to discharge the released hardness ions, it is necessary to perform regeneration 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 invention has been made in consideration of the problems inherent in the prior art. An object of the present invention is to provide a water softening device that can suppress the amount of wastewater generated during regeneration and efficiently regenerate the resin. [Means for solving the problem]

[0009] In order to solve the above problems, the water softening device according to the present invention includes a water softening chamber containing a weakly acidic cation exchange resin and producing soft water from raw water containing hardness components, a neutralization chamber containing 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 soft water to pass therethrough, a first electrode that acts as an anode during regeneration of the weakly acidic cation exchange resin, and a second electrode that acts as a cathode during regeneration of the weakly basic anion exchange resin. The first electrode is provided in the water softening chamber and surrounded by the weakly acidic cation exchange resin, and the second electrode is provided in the neutralization chamber and surrounded by the weakly basic anion exchange resin. This achieves the intended object. Effect of the Invention

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

[0011] [Figure 1] A perspective view of a water softening device. [Diagram 2] Cross-sectional view of a water softener [Diagram 3] Diagram showing the principle of a water softener [Figure 4] FIG. 1 shows the hardness of soft water in the softening process before and after regeneration in Example 1. [Diagram 5] FIG. 1 shows the pH change over time in the water softening chamber and neutralization chamber during regeneration in Example 1. [Figure 6] FIG. 1 shows the change over time in the number of moles of each ion during regeneration in Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the following embodiment is an example of the present invention, and does not limit the technical scope of the present invention. Also, each figure described in the embodiment is a schematic diagram, and the ratio of the size and thickness of each component in each figure does not necessarily reflect the actual dimensional ratio.

[0013] (Embodiment 1) A water softening device 100 according to a first embodiment of the present invention will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a perspective view showing the configuration of the water softening device 100 according to the first embodiment of the present invention. Fig. 2 is a cross-sectional view showing the configuration of the water softening device 100 according to the first embodiment of the present invention. 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.

[0014] The water softening device 100 is a device that generates 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 100 from a water conveying section 107 described later, such as well water or tap water. The raw water contains hardness components (calcium ions, magnesium ions). By performing a 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 is hard. After performing the softening process for a certain period of time, the water softening device 100 performs a regeneration process to regenerate the weakly acidic cation exchange resin 101 and the weakly basic anion exchange resin 102 described later. The details of the softening process and the regeneration process will be described later.

[0015] 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.

[0016] 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 upper and lower surfaces of the casing 203 toward the outer periphery, there are a water-conducting section 107, a water-softening chamber 201, a neutralization chamber 202, and a water-conveying section 108. A water-conducting section inlet 111 is provided at the center of the lower surface of the casing 203, that is, on the central axis I. A water-conveying section outlet 110 is provided at the center of the upper surface of the casing 203, that is, on the central axis I. The central axis I of the casing 203 coincides with the central axes of the water-conducting section 107, the water-softening chamber 201, the neutralization chamber 202, and the water-conveying section 108. In the casing 203, the raw water is softened and the ion exchange resin is regenerated.

[0017] 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.

[0018] The water conducting part 107 is a cylindrical member, and its lower end is connected to a water conducting part inlet 111. The water conducting part 107 conducts raw water into the water softening device 100 and supplies it to the water softening chamber 201. As the water conducting part 107, a tube such as a pipe having a space inside can be used.

[0019] The water guide section 107 is configured to allow the raw water introduced into the water softening device 100 to flow uniformly to the water softening chamber 201 and the neutralization chamber 202. Specifically, the water guide section 107 is provided in the center of the casing 203, and the outer periphery of the water guide section 107 is in contact with the water softening chamber 201; in other words, the water guide section 107 is located on the central axis I. The water guide section 107 is provided from the lower part to the upper part of the water softening chamber 201 and the neutralization chamber 202, more precisely from the lower end to the upper end, and the length of the part 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. The water guide section 107 has a plurality of holes on its side surface, and sends out raw water from these holes in the outer periphery direction from the central axis I of the casing 203, that is, to the water softening chamber 201. Furthermore, the plurality of holes are preferably provided uniformly in the circumferential direction of the side surface of the water guide portion 107. With such a configuration, raw water introduced into the device can be made to flow uniformly to the water softening chamber 201 and the neutralization chamber 202. Therefore, raw water is evenly supplied to the weakly acidic cation exchange resin 101 particles packed in the water softening chamber 201 and the weakly basic anion exchange resin 102 particles packed in the neutralization chamber 202, so that the weakly acidic cation exchange resin 101 and the weakly basic anion exchange resin 102 can be used efficiently as a whole.

[0020] The multiple holes in the side surface of the water conducting part 107 are smaller than the particle diameter of the weakly acidic cation exchange resin particles, and since the lower limit of the particle diameter of the weakly acidic cation exchange resin is around 0.3 mm, the diameter of the holes provided in the surface of the water conducting part 107 is smaller than that. This makes it possible to prevent the outflow of the ion exchange resin from the water softening chamber 201 without impeding the permeation of water.

[0021] The water softening chamber 201 is a cylindrical space provided inside the casing 203 on the outer circumferential side of the water conducting portion 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 contacts the water conducting portion 107 on the inner surface side of the cylindrical shape, and contacts the inner diaphragm 105 on the outer surface side. In other words, the water softening chamber 201 surrounds the water conducting portion 107 and is surrounded by the inner diaphragm 105.

[0022] The upper surface of the water softening chamber 201 is in contact with the lid portion 112, and is configured to prevent water from flowing out. This is to prevent water from flowing out from the upper surface of the water softening chamber 201 and bypassing the weak acid cation exchange resin 101 and the weak basic anion exchange resin 102 in the water softening process. The details of the lid portion 112 will be described later.

[0023] 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 by the weakly acidic cation exchange resin 101, and soft water containing released protons in place of the hardness components is produced.

[0024] 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.

[0025] The volume of the weakly acidic cation exchange resin 101 filled in the water softening chamber 201 is determined by the neutralization amount of the weakly acidic cation exchange resin 101. It is smaller than the volume of the weakly basic anion exchange resin 102 filled in the chamber 202. This is because the water softening chamber 201 is located on the inner periphery side of the neutralization chamber 202, and its volume is smaller than the volume of the neutralization chamber 202.

[0026] The water softening chamber 201 is provided with a first electrode 103 .

[0027] The first electrode 103 is not energized in the water softening process, and acts as an anode in 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, being surrounded means that 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 over the entire circumference. However, the weakly acidic cation exchange resin 101 usually has a spherical shape, and it is necessary to ensure a water passage for the raw water. For this reason, the weakly acidic cation exchange resin 101 is not in contact with the surface of the first electrode 103 without any gaps, and a state in which it is arranged over the entire circumference in a state of partial contact also falls under "the first electrode 103 being surrounded by the weakly acidic cation exchange resin 101".

[0028] 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. As a result, a first space 204 is formed above the upper end of the first electrode 103 in the water softening chamber 201. The weakly acidic cation exchange resin 101 fills the water softening chamber 201. In other words, the weakly acidic cation exchange resin 101 is filled around the first electrode 103 and in the first space 204. 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 is near the upper 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 upper surface of the water softening chamber 201.

[0029] The first electrode 103 is configured so that, when the distance S from the water surface to the upper end of the first electrode 103 at the start of the regeneration process is compared 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. This allows air bubbles generated from the first electrode 103 to cause the weak acid cation exchange resin 101 to flow during the regeneration process described below, 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 FIG. 2.

[0030] The material of the first electrode 103 can be a precious metal or a precious metal alloy. This is because the precious metal acts as a catalyst for water electrolysis and does not dissolve even in acidic conditions. Examples of precious metal materials include platinum, iridium, and ruthenium.

[0031] The electrode may be in the form of a single precious metal wire electrode, an electrode in which a precious metal wire is wound around the outer periphery of a support, a mesh-shaped precious metal electrode, etc. A support may be a metal rod other than a precious metal, such as titanium (Ti), coated with a precious metal. 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 single precious metal or a precious metal alloy.

[0032] 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 weakly basic anion exchange resin 102. The central axis of the neutralization chamber 202 coincides with the central axis I of the casing 203. The neutralization chamber 202 is in contact with the outer surface of the inner diaphragm 105 on the inner side of the cylindrical shape, and in contact with the inner surface of the outer diaphragm 106 on the outer side of the cylindrical shape. In other words, the neutralization chamber 202 surrounds the inner diaphragm 105 and is surrounded by the outer diaphragm 106. The neutralization chamber 202 is filled with the weakly basic anion exchange resin 102. Details of the inner diaphragm 105 and the outer diaphragm 106 are described below. More on this later.

[0033] 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 in the water softening process.

[0034] The weakly basic anion exchange resin 102 may be a resin having a tertiary amine or a quaternary amine as a functional group, and in this embodiment, a resin having a higher proportion of tertiary amine than quaternary amine is used.

[0035] The volume of the weakly basic anion exchange resin 102 filled in the neutralization chamber 202 is larger than the volume of the weakly acidic cation exchange resin 101 filled in the water softening chamber 201. This is because the neutralization chamber 202 is located on the outer periphery side 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.

[0036] In the neutralization chamber 202, soft water with a neutral pH is generated by neutralizing the soft water generated in the water softening chamber 201. In the neutralization chamber 202, a second electrode 104 is provided.

[0037] The second electrode 104 is not energized in the water softening process, and acts as a cathode in 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 in the neutralization chamber 202. Here, being surrounded means that 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 over the entire circumference. However, like the weakly acidic cation exchange resin 101, the weakly basic anion exchange resin 102 usually has a spherical shape, and it is necessary to ensure a water passage for the raw water (strictly speaking, acidic soft water). For this reason, the weakly basic anion exchange resin 102 is not in contact with the surface of the second electrode 104 without any gaps, and a state in which it is arranged over the entire circumference in a state of partial contact also corresponds to "the second electrode 104 is surrounded by the weakly basic anion exchange resin 102".

[0038] 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) 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. 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. In order to smoothly regenerate the weakly basic anion exchange resin 102, it is preferable that the water surface at the start of the regeneration process is near the upper surface of the neutralization chamber 202, and in this embodiment, the water surface at the start of the regeneration process is coincident with the upper surface of the neutralization chamber 202.

[0039] The second electrode 104 is configured such that, when a distance V from the water surface to the upper end of the second electrode 104 at the start of the regeneration process is compared with a 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. This allows air bubbles generated from the second electrode 104 to flow through the weakly basic anion exchange resin 102 during the regeneration process described below, 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 FIG. 2.

[0040] A precious metal or a precious metal alloy can be used as the material of the second electrode 104. This is because the precious metal acts as a catalyst for water electrolysis and does not dissolve even in acidic conditions. Examples of precious metal materials include platinum, iridium, and ruthenium.

[0041] The first electrode 103 is provided in a pair with the second electrode 104, and the pair of the first electrode 103 and the second electrode 104 are provided on the same radius of the casing 203. This allows the distance between the first electrode 103 and the second electrode 104 to be shorter than when the pair of electrodes is not on the same radius, and the increase in power consumption due to an increase in voltage can be suppressed. In this embodiment, two pairs of electrodes (the first electrode 103a and the second electrode 104a, and the first electrode 103b and the second electrode 104b) are provided on the same diameter of the cylindrical casing 203. This allows the two pairs of electrodes to be evenly arranged in the casing 203, and therefore it is possible to suppress bias in the location of generation of hydrogen ions or hydroxide ions generated from the electrodes during regeneration. Therefore, the regeneration of the weakly acidic cation exchange resin 101 and the weakly basic anion exchange resin 102 can be efficiently performed.

[0042] The water softening chamber 201 and the neutralization chamber 202 are separated by the inner periphery side diaphragm 105. In other words, the weakly acidic cation exchange resin 101 and the weakly basic anion exchange resin 102 are separated by the inner periphery side diaphragm 105.

[0043] 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. 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. In this way, the inner diaphragm 105 allows the acidic soft water generated in the water softening chamber 201 to pass through, and separates the water softening chamber 201 from the neutralization chamber 202. 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.

[0044] 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 the 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, so the pore diameter of the inner diaphragm 105 is smaller than that.

[0045] A resin mesh sheet can be used as the inner periphery-side diaphragm 105. The material of the inner periphery-side diaphragm 105 is preferably a material having heat resistance and chemical resistance, such as a fluorine-based resin, a polyethylene resin, a polypropylene resin, a polyvinyl chloride resin, or a polyvinylidene fluoride resin.

[0046] A structure having through holes or slits or the like can also be used as the inner diaphragm 105. In order to allow water to flow evenly from the softening chamber 201 to the neutralization chamber 202 in 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 in the water softening process.

[0047] The neutralization chamber 202 and a water supply section 108 (described later) are separated by an outer peripheral diaphragm 106 .

[0048] 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. 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. This allows the soft water generated in the neutralization chamber to pass through, and separates the neutralization chamber 202 from the water supply section 108. Incidentally, "covering" means that it is sufficient to be positioned around the object, and it is not necessary to completely enclose the object.

[0049] 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.

[0050] A resin mesh sheet can be used as the outer periphery-side diaphragm 106. The material of the outer periphery-side diaphragm 106 is preferably a material having heat resistance and chemical resistance, and examples of the material include a fluorine-based resin, a polyethylene resin, a polypropylene resin, a polyvinyl chloride resin, and a polyvinylidene fluoride resin.

[0051] Moreover, a structure having through holes or slits or the like can 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 in the water softening process, it is preferable that the through holes or slits are evenly arranged on the surface of the outer periphery diaphragm 106. The opening area 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 in the water softening process.

[0052] The upper surfaces of the water-conducting portion 107 , the water-softening chamber 201 , the inner periphery-side diaphragm 105 , the neutralization chamber 202 , and the outer periphery-side diaphragm 106 are covered by a lid portion 112 .

[0053] The lid 112 has a water-impermeable structure, and may be made of, for example, a plate-shaped resin. The lid 112 comes into contact with and covers the upper surfaces of the water-conducting 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-conducting section 108 described below. This prevents water from flowing out of the upper surfaces into the water-conducting section 108. In other words, the lid 112 can form a water flow in which raw water flowing in from the water-conducting section inlet 111 passes through the water-conducting section 107, the water-softening chamber 201, the inner diaphragm 105, and the neutralization chamber 202, and is sent out from the side surface of the outer diaphragm 106 to the side space 108a of the water-conducting section 108.

[0054] 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.

[0055] The water supply unit 108 is provided within the casing 203 and includes a side space 108a and an upper space 108b.

[0056] The side space 108a is a cylindrical space provided on the outer circumferential side of the neutralization chamber 202 with respect to the central axis I of the casing 203 and surrounding 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 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 provided between the inner surface of the casing 203 and the outer surface of the outer circumferential diaphragm 106. In the direction parallel to the central axis I, the total length of the side space 108a is greater than the total length of the neutralization chamber 202, and when the bottom surfaces of the side space 108a and the neutralization chamber 202 are arranged on the same plane, the top surface of the side space 108a protrudes upward from the top surface of the neutralization chamber 202.

[0057] The upper space 108b is a cylindrical space provided above the top surfaces of the water-conducting section 107, the water-softening chamber 201, the inner circumference diaphragm 105, the neutralization chamber 202, and the outer circumference 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.

[0058] The side space 108a and the upper space 108b are virtually divided 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.

[0059] The water supply unit outlet 110 is provided on the top surface of the casing 203, and discharges the water in 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.

[0060] 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.

[0061] The water softening device 100 has the above configuration.

[0062] Next, the two processes (water softening process and regeneration process) of the water softening device 100 will be described.

[0063] First, the operation of the water softening device 100 in the water softening process and the principle of the water softening process will be described.

[0064] In the water softening device 100, raw water flows from the outside into the lower part of the water conducting part 107 through the water conducting part inlet 111. The flowing raw water is sent from the lower part to the upper part of the water conducting part 107, and flows out in the radial direction of the casing 203 from the holes provided in the side wall of the water conducting part 107. In other words, the raw water is sent out from the holes in the water conducting part 107 to the water softening chamber 201.

[0065] 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, magnesium ions) in the raw water are exchanged with hydrogen ions adsorbed to the weakly acidic cation exchange resin 101, and the raw water becomes acidic soft water containing hydrogen ions.

[0066] The acidic soft water produced in the water softening chamber 201 passes through the inner periphery diaphragm 105, which is a water-permeable membrane, and flows into the neutralization chamber 202 where it is neutralized. In detail, hydrogen ions in the soft water are removed from the soft water by being adsorbed by the weakly basic anion exchange resin 102, and neutral soft water is produced. During this neutralization reaction, anions such as sulfate ions contained in the soft water are also adsorbed by the weakly basic anion exchange resin 102.

[0067] 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 .

[0068] The soft water that flows into the water supply section 108 flows upward, rises in the side space 108a, and flows into the upper space 108b. The soft 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 section outlet 110 provided in the center of the top surface of the water softening device 100. In this manner, the raw water is softened in the water softening process.

[0069] To soften water efficiently, it is important to bring the ion exchange resin particles into sufficient contact with the hard water or acidic soft water. For this reason, water softeners using ion exchange resins must be designed so that water flows uniformly through the device. If water does not flow uniformly, it will tend to flow in the paths that are easiest for it to flow through, and so the water will pass through the water softening chamber 201 or neutralization chamber 202 without sufficient contact with the ion exchange resin. As a result, However, the water removed from the water softening device 100 may not be softened or may remain acidic.

[0070] In the water softening device 100 of this embodiment, raw water is introduced into the device from the bottom of the casing, passes through the water supply section 108, and is taken out as soft water from the water supply section outlet 110 provided at the top. This method of sending water from the bottom to the top is called an upward flow. In the case of an upward flow, ion exchange resin particles can easily flow, so there is little pressure loss when water is passed through the water softening chamber 201 and the neutralization chamber 202, and water flows easily. In addition, since the water softening device 100 is cylindrical, the distance from the central water conveying section 107 to the outer water supply section 108 is equal, and the water pressure applied to the water supply section 108 is uniform. Furthermore, the water softening device 100 is structured so that water flows out from the water supply section outlet 110 provided at the center of the top surface of the water softening device 100. The three features of the upward flow, the cylindrical shape, and the position of the water supply outlet 110 reduce the variation in 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. Therefore, the ion exchange resin can come into sufficient contact with the raw water or acidic soft water, enabling efficient water softening.

[0071] 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 about 3. In the water softening process, H in the weakly acidic cation exchange resin + When the pH of the water in the water softening chamber 201 becomes lower than the pKa, the COO - H + As a result, the acrylic acid skeleton, which has a low pKa, can exchange more cations than the methacrylic acid skeleton.

[0072] In addition, it is preferable to use a resin with a high ratio of tertiary amines as functional groups for the weakly basic anion exchange resin 102 filled in the neutralization chamber 202. The pKb of quaternary amines is about 11, which is higher than the pKb of tertiary amines, which is about 8. The upper limit of the pH of the soft water after passing acidic soft water through the weakly basic anion exchange resin 102 is the pKb of the amine groups. This is because, in the weakly basic anion exchange resin 102, the amine groups, which are ion exchange groups, do not function when the pH of the solution exceeds the pKb. The upper limit of the pH of tap water is set to 8.5 according to the water quality standard. When the ratio of quaternary amines in the weakly basic anion exchange resin 102 is high, the pH of the soft water is biased toward the alkaline side compared to when the ratio of quaternary amines is low. In other words, when the ratio of quaternary amines is high, the pH becomes higher than 8.5, which may not satisfy the water quality standard. Therefore, it is preferable to have a high ratio of tertiary amines in order to keep the pH of the soft water within the water quality standard.

[0073] 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 larger than the volume of the weakly acidic cation exchange resin. The reason for this will be explained from the viewpoint of the ion exchange reaction rate of the two resins.

[0074] In order to obtain soft water that meets the water quality standards during the water softening process, it is necessary to reduce the hardness of the raw water to 50 mg / L or less while the raw water passes through the softening chamber 201, and to return the pH of the raw water from around 3 to neutral while passing through the neutralization chamber 202. The amount of cations removed in the softening chamber 201 and the amount of anions and H removed in the neutralization chamber 202 are + 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 concentration of ion exchange groups, (b) the concentration of ions in the hard water (Ca 2+ , Cl - (c) the rate constant of the ion exchange reaction. The time it takes for water to pass through the resin depends on (d) the volume of the resin and (e) It depends on the water flow rate.

[0075] Among these five parameters, (b) the ion concentration in hard water and (e) the water flow rate cannot be controlled. (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, so (d) the resin volume can be adjusted to achieve the required water quality standard during the water softening process.

[0076] The volume ratio of each resin is determined from the viewpoints of (a) ion exchange group concentration and (c) ion exchange reaction. (a) ion exchange group concentration can be compared by the ion exchange equivalent (eq / L) of the ion exchange resin, that is, the number of moles of ion exchange group per resin volume. Since the ion exchange equivalent of the weakly acidic cation exchange resin 101 is about 4 eq / L, and the ion exchange equivalent of the weakly basic anion exchange resin 102 is at most 2 eq / L, (a) the ion exchange group concentration is higher in the weakly acidic cation exchange resin 101. In addition, (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 is higher in the weakly basic anion exchange resin, 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. In terms of the reaction rate taking into account (a) and (c), the weakly basic anion exchange resin 102 has a slightly smaller reaction rate than 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.

[0077] In such a water softening process, if the amount of hardness ions adsorbed to the weakly acidic cation exchange resin 101 or the amount of anions adsorbed to the weakly basic anion exchange resin 102 increases, the resin performance for water softening decreases, and therefore a regeneration process must be carried out.

[0078] Conventionally, when using a BP membrane to regenerate a water softener containing a mixture of weakly acidic cation exchange resin and weakly basic anion exchange resin, there was a problem that the desorbed hardness ions were re-adsorbed onto the ion exchange resin, which tended to inhibit the resin regeneration reaction. Therefore, in order 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 flowing through the device. This water flow operation resulted in a problem of a large amount of wastewater being discharged during the regeneration process. The cause of the above problem will be explained below.

[0079] 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 take place.

[0080] Both regeneration reactions are reversible, so Ca 2+ Or Cl - In addition to the forward reaction in which each ion is desorbed, the reverse reaction in which each ion is adsorbed also occurs. The amine group of the weakly basic anion exchange resin 102 is OH - The affinity with Cl - Therefore, Cl - The rate of the reverse reaction in which Ca is adsorbed is low, and the impact of the reverse reaction is small. On the other hand, the carboxyl group of the weakly acidic cation exchange resin 101 is 2+ Therefore, Ca 2+ The rate of the reverse reaction in which Ca is adsorbed is faster than that of weakly basic anion exchange resins, and a certain amount of Ca 2+ A re-adsorption reaction occurs.

[0081] 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+ is the concentration of H + High concentration of Ca 2+ When H is low, the speed of the rightward reproduction reaction is high. + Concentration is low, Ca 2+ Under high Ca2+ conditions, the rate of rightward regeneration slowed and the rate of leftward Ca2+ 2+The rate of the re-adsorption reaction increases, making it difficult to regenerate the resin.

[0082] In the regeneration process shown in Patent Document 1, H is generated at the interface between the BP membrane and the ion exchange resin. + and O.H. - are generated simultaneously. H + and O.H. - The original purpose of the generation is to regenerate the resin, but the generated H + and O.H. - is also consumed by side reactions other than the resin regeneration reaction. + and OH - Neutralization reaction by recombination of H and H by weakly basic anion exchange resin + There is an adsorption reaction. These H + and O.H. - In Patent Document 1, since multiple reactions occur that consume , the pH in the resin tank during the regeneration process becomes nearly neutral.

[0083] When the pH during the regeneration process becomes close to neutral, Ca 2+ Under high pH conditions, the regeneration of the weakly acidic cation exchange resin is difficult to proceed. 2+ Desorbed Ca from weakly acidic cation exchange resin to reduce the concentration 2+ Therefore, a drainage operation is required to discharge the wastewater from the system.

[0084] The amount of water discharged by this drainage operation can be estimated as follows. For a home water softener, the volume of ion exchange resin generally needs to be about 20L. The amount of water in the tank is roughly the same as that of the resin, based on the voids in the tank and the volume of the resin. If the water in the tank stagnates, 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 minutes. For example, if the water in the tank is replaced once every 10 minutes, it is necessary to keep the water flowing at 2L / min. The hydrogen ions and hydroxide ions that can be generated by the BP membrane method are each in units of several mmol / min. On the other hand, under standard usage conditions, the calcium ions and magnesium ions that are desorbed from the resin are on the order of several moles (if 1000L of raw water with a hardness of 250mg / L is softened per day, the hardness adsorbed by the resin is 2.5mol), so regeneration takes several hours. Even if the regeneration time were three hours, the amount of wastewater would be enormous: 2L / min x 3hr x 60min / hr = 360L.

[0085] Therefore, there is a demand for a water softening device that reduces the amount of wastewater discharged or eliminates the need for wastewater discharge.

[0086] The operation of the water softening device 100 in the regeneration process and the principle of the regeneration process will be described below with reference to FIG.

[0087] In the regeneration process, first, raw water flows from a raw water supply source into the water conducting section 107 via the water conducting 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.

[0088] 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.

[0089] The weakly acidic cation exchange resin 101, which has adsorbed hardness components in the water softening process, undergoes an exchange reaction between the hardness components and hydrogen ions when exposed to hydrogen ions, thereby regenerating the weakly acidic cation exchange resin 101.

[0090] Furthermore, the weakly basic anion exchange resin 102 to which anions have been adsorbed by the water softening process undergoes an exchange reaction between the adsorbed anions and the hydroxide ions when exposed to hydroxide ions, thereby regenerating the weakly basic anion exchange resin 102.

[0091] In this way, the weak acid cation exchange resin101 and the weak base anion exchange resin102 are regenerated. Regeneration of the ion exchange resin 102 is performed.

[0092] 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, so that hydrogen ions and hydroxide ions are generated separately, and both generated ions are quickly used to regenerate the ion exchange resin. If the generated hydrogen ions and hydroxide ions come into contact with each other, a neutralization reaction occurs, and both ions are consumed. However, in the configuration of this embodiment, the neutralization reaction caused by the contact of hydrogen ions and hydroxide ions is unlikely to occur, so that the hydrogen ion concentration in formula 3 in FIG. 3 can be increased, and even in a state in which calcium ions coexist, the regeneration reaction of the weakly acidic cation exchange resin 101 can be promoted. Therefore, the frequency of draining water for the purpose of reducing the calcium ion concentration in the water softening device 100 in the regeneration process can be reduced, or draining can be made unnecessary, thereby reducing the amount of drainage. In addition, the generated hydrogen ions and hydroxide ions are immediately consumed in the resin regeneration reaction, so that 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 increased. 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, platinum is dissolved by Cl) can be prevented. - This prevents the reaction of platinum with platinum ions to produce platinum chloride ions, thereby increasing the electrode life.

[0093] 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, since the electrodes are disposed near the resin with a high adsorbed ion concentration, 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. In detail, in the regeneration process, the resin regeneration reaction, represented by formulas (3) and (4) in FIG. 3, and H + , O.H. - The production reactions (5) and (6) occur simultaneously. H produced by water electrolysis +, O.H. - It is desirable that H be consumed immediately in the resin regeneration reaction. + , O.H. - It is also consumed by neutralization reactions in which H reacts with itself. + , O.H. - The diffusion rate of H is faster than that of other ions, so if it is not consumed in the resin regeneration reaction, it will easily undergo neutralization. + , O.H. - When the loss of H occurs, the number of moles of H in excess of the number stoichiometrically required by Eqs. (3) and (4) is exceeded. + , O.H. - This increases power consumption because H + , O.H. - It is necessary to make the rate of the resin regeneration reaction faster than the rate of the formation reaction.

[0094] The rate increase of the resin regeneration reaction is (R-COO - )2Ca 2+ and R3-NH + Cl - This can be achieved by increasing the concentration of H. + , O.H. - In the regeneration process, where the formation reaction occurs simultaneously, (R-COO - )2Ca 2+ and R3-NH + Cl - In order to increase the concentration of R-COO, it is effective to place the electrodes near the resin that has adsorbed more cations or anions in the water softening process. - )2Ca 2+ ya(R-COO - ) 2Mg 2+ In the neutralization chamber 202, the concentration of R3-NH + Cl - Or (R3-NH + )2SO4 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.

[0095] (Example) The present invention will now be described in detail with reference to examples and with reference to FIGS.

[0096] A water softening test and a regeneration test were carried out using the water softening device 100 shown in Fig. 1. In the water softening test, raw water was passed through a water conveyance pipe, and the hardness of the water taken out from the water softening device 100 was measured. The raw water used was hard water with a hardness of 310 mg / L.

[0097] The regeneration test was carried out in the following manner. The platinum electrode on the weakly acidic cation exchange resin 101 side was connected to the positive electrode of a DC power source, 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 passed from the DC power source for 6 hours. The water in the water softener 100 was not replaced during regeneration, and regeneration was carried out without draining. A small amount of water was taken out from the water softening chamber 201 and neutralization chamber 202 during regeneration, and the pH and ion concentration were measured.

[0098] After the first water softening test, a regeneration test was carried out, and then a water softening test was carried out again.

[0099] FIG. 4 is a diagram showing the change in 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 the hardness was reduced from 310 mg / L to 50 mg / L or less by passing water through the water softening device 100. The hardness was also reduced to the soft water level in the second water softening process performed after the regeneration process. When raw water was passed through the water softening device 100 for 40 minutes, the high hardness of 310 mg / L could be reduced to about 20 mg / L. This shows that the flow of water in the water softening device 100 is uniform, in other words, all of the resin particles in the water softening device 100 are being used.

[0100] FIG. 5 shows the pH changes in the water softening compartment 201 and neutralization compartment 202 during the regeneration process. It can be seen that the neutralization compartment 202 becomes neutral with a pH of 7-9, and weakly alkaline, while the water softening compartment 201 becomes acidic with a pH of 2.3-3.3. Although the diaphragm used allows water to easily pass through, the water softening compartment 201 remains acidic and the neutralization compartment 202 remains alkaline. In other words, the weakly acidic cation exchange resin 101 is H + Weakly basic anion exchange resin 102 was added to OH - It is clear that the water can be individually exposed to the above conditions. Furthermore, the pH of the water softening chamber 201 is slightly acidic at about pH 2.5, although it tends to be acidic, and the pH of the neutralization chamber 202 is slightly alkaline at about pH 9, although it tends to be alkaline. + and OH - The rate at which H is consumed at the electrode + 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 rapidly and becomes a strong alkali of pH 12 or more, while the pH in the softening chamber 201 decreases and becomes a strong acid of pH 2 or less. + or OH - This is because H is constantly being generated. Therefore, the pH does not suddenly become acidic or alkaline, which is the reason why H generated from the electrode + and O.H. - It can be said that Ca is immediately consumed in the resin regeneration reaction. 2+ Or Cl - It can be seen that by placing the electrodes near the resin that has absorbed a large amount of CO, the resin regeneration reaction can be controlled to become the rate-limiting reaction.

[0101] Figure 6 shows the Cl concentration during the regeneration process. - Ion, Mg 2+ ions, and Ca 2+ This is a diagram showing the change in the number of moles of ions. - Ions are transferred from weakly basic anion exchange resin 102 to Mg 2+ ions and Ca 2+Ions are released from the weakly acidic cation exchange resin 101. As the regeneration time increases, the number of moles of each ion increases. In addition, the number of moles of ions hardly changes between 5.5 hours and 6 hours. From the increase in the number of moles of ions with the increase in the regeneration time, it can be seen that cations are released from the weakly acidic cation exchange resin 101 and anions are released from the weakly basic anion exchange resin 102, and resin regeneration is progressing. In addition, even under the condition that no drainage is performed during the regeneration process, the result that ions are released by regeneration has demonstrated that the amount of drainage during regeneration can be reduced in the configuration of this embodiment. In addition, from two points that the amount of ions at the end of the regeneration hardly changes and that the hardness of the soft water after regeneration in FIG. 4 is almost the same level as before regeneration, it can be seen that the resin can be regenerated to a level that allows water to be softened by the water softener of the embodiment.

[0102] The present invention has been described above based on the embodiments. These embodiments are merely examples. It will be understood by those skilled in the art that various modifications are possible in the combination of each of these components or each of the treatment processes, and that such modifications are also within the scope of the present invention.

[0103] In the first embodiment, since the water softener 100 is cylindrical, the two diaphragms (the inner diaphragm 105 and the outer diaphragm 106) are distinguished as being on the inner side and the outer periphery side, but the two diaphragms are not necessarily located on the inner side and the outer periphery side depending on the shape of the water softener 100. The names "inner diaphragm" and "outer diaphragm" are merely names for distinguishing between the two types of diaphragms, and do not indicate the positions of the inner diaphragm 105 and the outer periphery side diaphragm 106.

[0104] In the water softening device 100 according to the first embodiment, the casing 203, the water conducting section 107, the water softening chamber 201, the inner circumference side diaphragm 105, the neutralization chamber 202, and the outer circumference side diaphragm 106 are cylindrical in shape, but are not limited thereto. For example, they may be rectangular tubes.

[0105] In the water softening device 100 according to the first embodiment, a tube such as a pipe having minute holes on its surface is used as the water guiding section 107, but this is not limiting. For example, it is also possible to make the center part of the water softening chamber 201 a gap, and use this gap as the water guiding section 107. In this way, the same effect can be obtained.

[0106] In the water softening device 100 according to the first embodiment, a container having a cylindrical hollowed-out center is used for the water softening chamber 201, but this is not limiting. For example, the space partitioned by the outer periphery of the water-conducting section 107 and the inner periphery-side diaphragm 105 may be used as the water softening chamber 201. In this way, the same effect can be obtained.

[0107] In the water softener 100 according to the first embodiment, a container having a cylindrical hollowed-out center is used for the neutralization chamber 202, but this is not limiting. For example, the space partitioned by the inner diaphragm 105 and the outer diaphragm 106 can also be used as the neutralization chamber 202. The same effect can be obtained in this way.

[0108] In the water softener 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 is not limited thereto. The lid 112 may have any structure that prevents water from flowing out 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 have a structure that individually 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. This structure can also prevent water from flowing out from the upper surfaces to the water supply section 108.

[0109] In the water softener 100 according to the first embodiment, the volume of the weakly basic anion exchange resin 102 is equal to or larger 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 soft 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 less, so 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.

[0110] In the water softener 100 according to the first embodiment, the first electrode 103 and the second electrode 104 can be arranged in any manner 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. 104 is the generated H + and O.H. - The arrangement of the first electrode 103 is not particularly limited as long as the loss can be suppressed by the neutralization reaction of the weak acid cation exchange resin 101 and consumed in the ion exchange resin regeneration reaction. However, from the viewpoint of cost reduction, the first electrode 103 is preferably arranged anywhere in the height direction from the bottom surface filled with the weak acid cation exchange resin 101 to the halfway position of the top surface filled with the weak acid cation exchange resin 101. Also, from the viewpoint of cost reduction, the second electrode 104 is preferably arranged anywhere in the height direction from the bottom surface filled with the weak basic anion exchange resin 102 to the halfway position of the top surface filled with the weak basic anion exchange resin 102.

[0111] In the water softening apparatus 100 according to the first embodiment, the case where the water softening apparatus 100 is used alone has been described, but it is also possible to connect a plurality of water softening apparatuses 100 in parallel and use the apparatus as a system consisting of two or more water softening apparatuses 100 connected in parallel. By connecting the water softening apparatuses 100 in parallel, the flow rate per tank can be reduced. When the flow rate is reduced, the time that the raw water passes through the water softening apparatus 100 increases, and the amount of hardness removed in the water softening process increases.

[0112] It is also possible to connect a plurality of water softeners 100 in series and use the system as a system consisting of two or more water softeners 100 connected in series. By connecting water softeners 100 in series, the number of theoretical plates of the ion exchange resin layer increases. This increases the ion exchange capacity of the ion exchange resin that can be practically used. Specifically, when the ion exchange capacity of an ion exchange resin in two series-connected tanks is compared with that of a single tank under the condition that the total amount of ion exchange resin is the same, the system consisting of two series-connected tanks has about five times the capacity of the single tank.

[0113] Furthermore, the water softeners 100 can be connected in series and in parallel to be used as a system consisting of four or more tanks of the water softeners 100. When configured in this manner, the amount of hardness removed in the water softening process is the highest compared to the above-mentioned configurations in which only parallel connections are used and in which only series connections are used. [Industrial Applicability]

[0114] The water softening device of the present invention can reduce the frequency of drainage or even eliminate the need for drainage altogether, thereby reducing the amount of drainage, and as a secondary effect, it can also shorten the regeneration time and increase the electrode life, making it useful as a water softening device, etc. [Explanation of symbols]

[0115] 100 Water softener 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 Conveyance Section 108 Water supply section 109 Air vent valve 110 Water supply section outlet 111 Water Conduit Entrance 112 Lid 113 Border 201 Water softening room 202 Neutralization room 203 Casing 204 First space 205 Second space

Claims

1. 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 so that the soft water can pass therethrough; A first electrode that acts 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 weak acid cation exchange resin; The second electrode is disposed in the neutralization chamber and surrounded by the weakly basic anion exchange resin.

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

3. the first electrode has an upper end positioned below the water level in the water softening chamber at the start of regeneration of the weakly acidic 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; 2. The water softening device according to claim 1, wherein the weakly acidic cation exchange resin is filled in the space around and above the first electrode in the water softening chamber.

4. the second electrode is configured such that an 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; 2. The water softening apparatus according to claim 1, wherein the weakly basic anion exchange resin is filled in the space around and above the second electrode in the neutralization chamber.

5. A cylindrical casing having the water softening chamber and the neutralization chamber therein is provided, 2. The water softening device according to claim 1, wherein the neutralization chamber is disposed on an outer circumferential side of the water softening chamber with respect to a central axis of the cylinder and surrounds the water softening chamber.

6. A water conveying section is provided for introducing the raw water into the water softening chamber, The water softening device according to claim 5 , wherein the water conveying section is provided from the lower part to the upper part of the water softening chamber, and the raw water is sent out from a side surface of the water conveying section in an outer circumferential direction with respect to the central axis of the cylinder.

7. a water supply unit provided on an outer circumferential side of the neutralization chamber with respect to the central axis of the cylinder and surrounding the neutralization chamber; The water softening apparatus according to claim 5 , wherein the water supply unit supplies the water in the neutralization chamber, which is discharged from the neutralization chamber in an outer circumferential direction with respect to the central axis, to the outside of the apparatus from above an upper portion of the neutralization chamber.

8. The water softening device according to claim 5 , wherein the pair of the first electrode and the second electrode are provided on the same radius of the casing.

9. 2. The water softening apparatus 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 diaphragm is a membrane that is permeable to water and has a pore size smaller than the particle size of the ion exchange resin.

2. The water softening device according to claim 1.

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