JP2003039070A - Desalinated water production apparatus and desalinated water production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a desalinated water production apparatus and a desalinated water production method which can maintain high desalination performance and are easy to produce. SOLUTION: A positive electrode and a negative electrode, a dielectric disposed between the two electrodes while being electrically insulated from the two electrodes, and both electrodes and the dielectric are disposed, and an inlet and a treatment of water to be treated are provided. A desalinated water production apparatus having a desalination chamber having a water outlet; and a desalinated water production method using the desalinated water production apparatus.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to water supply for boilers such as power plants, production of pure water used in semiconductor manufacturing processes, fuel cell power generation, etc., production / circulation use of water for cooling towers, recovery of various wastewater, Alternatively, the present invention relates to an apparatus for producing demineralized water and a method for producing demineralized water used for purifying by removing ions from seawater, brackish water, alcohol and the like.

[0002]

2. Description of the Related Art Conventionally, as this type of demineralized water producing apparatus, there is one using a deionizing apparatus equipped with an ion exchange membrane and an ion exchange resin. A desalination apparatus using an ion-exchange membrane or an ion-exchange resin usually requires regeneration and exchange of the membrane and resin, which increases the processing cost and requires a lot of labor for the work, which is economical. In addition, improvement in work efficiency was also desired. In recent years, as a demineralized water production apparatus capable of improving such inconveniences related to replacement and regeneration, a deionization apparatus called a liquid-passing type electric double layer capacitor has been provided. As this liquid-passing type electric double layer capacitor, the one described in JP-A-6-325983 can be exemplified. The liquid-passing type electric double layer capacitor has two high surface area conductor layers with a liquid passage interposed therebetween, and a collector electrode is in intimate contact with the outside of these conductor layers. By applying a voltage to the collecting electrode, the ionic substance in the feed water flowing through the liquid passage can be electrically adsorbed to the conductor layer in contact with the collecting electrode, and treated water with a reduced ionic substance concentration can be obtained. You can do it. Activated carbon is suitable as the conductor forming the conductor layer.

[0003]

However, in such a through-flow type electric double layer capacitor, if the electrodes and the conductor are not in close contact with each other, the flow of electricity becomes non-uniform and a sufficient current does not flow through the conductor. Since the desalination rate may decrease, sufficient precision was required for manufacturing and processing. Further, in order to adsorb the ionic substance, it must be a conductor, and the material usable as the conductor is also limited in terms of life and cost.

Therefore, the present invention is relatively easy to manufacture as compared with the conventional liquid-flow type electric double layer capacitor,
It is an object of the present invention to provide a desalinated water production apparatus having a degree of freedom in materials used and a desalinated water production method using the same.

[0005]

As a result of intensive studies to achieve the above object, the present inventor has found that a demineralized water producing apparatus having a structure in which a dielectric is arranged in a state of being electrically insulated from both electrodes. For example, when electricity is applied to both electrodes, the dielectric is polarized and the surface is charged, so there is no need for the dielectric to be in intimate contact with the electrodes, and it is relatively easy to manufacture and process. The present invention has been completed based on the finding that the material used has a degree of freedom because it can be used as a dielectric as long as it is a material that is dielectrically polarized regardless of a conductive material. That is, the present invention provides a positive electrode and a negative electrode, a dielectric disposed between the electrodes in a state of being electrically insulated from the electrodes, the electrodes and the dielectric, and an inlet for the water to be treated. And a desalination chamber having an outlet of treated water. The present invention also provides a method for producing demineralized water using such an apparatus for producing demineralized water.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.
1A and 1B show an embodiment of the desalinated water producing apparatus of the present invention. In FIG. 1, a demineralized water production apparatus 1 includes separators 3 and 3 made of an electrically insulating water-permeable sheet with a dielectric 2 sandwiched between them. Outside the separators 3 and 3, feed electrodes 4 and 4 (a positive electrode, (Cathode electrode) is arranged, and a gasket 5,
It has a flat plate shape in which the pressing plates 6 and 6 are arranged with the pressing plate 5 interposed therebetween.

The dielectric material may be conductive or non-conductive as long as it can be polarized when an electric field is applied. Specific examples include metals, ceramics, fibrous activated carbon, granular activated carbon, powdered activated carbon, polyvinyl chloride, synthetic resins such as PVDF, paraffin, and titanium oxide.
In the conventional through-flow type electric double layer capacitor, the substance that adsorbs the ionic substance is limited to the conductive substance, but in the present invention, the range of selection of the material to be used is widened, and it is used for long-term desalination. Also, it is possible to select a material having a low degree of deterioration.
It is preferable to use the dielectric material in the form of a sheet or a flat plate to arrange it in the desalting chamber. The dielectric material can be processed into a sheet shape or a flat plate shape, or the dielectric material can be mixed or covered with paper or a plastic sheet. Furthermore, a water-permeable bag or container may be filled with the dielectric. When it is fibrous, it can be used after being processed into a woven or non-woven fabric. When powdered granular activated carbon is used after being formed into a flat plate shape or a sheet shape, it is significantly advantageous in terms of cost, compared with the case where fibrous activated carbon is processed into a woven or non-woven fabric and used.

[0008] The dielectric material is such that when an electric field is applied, the side surface perpendicular to the direction of the electric field is positively or negatively charged, and anions or cations are trapped on both side surfaces. Those having a large surface area are preferable. Specifically, the surface area is preferably 2 times or more and less than 10000 times the projected area. If it is less than 2 times, the surface area is not sufficiently large, and the amount of trapped ions is not always sufficient.
If it is 000 times or more, the amount of trapped ions tends to rather decrease. Moreover, the thickness of the dielectric is 0.05 to 10 m.
m is preferred.

For forming the granular activated carbon into a flat plate or sheet, for example, the granular activated carbon is mixed with a binder component (polytetrafluoroethylene, phenol resin, carbon black, etc.) and / or a dispersion medium (solvent, etc.). Can be formed into a plate shape, and further heat-treated as necessary. If a flat plate or sheet is used as the dielectric 2, it may be perforated if necessary.

The material of the separator 3 is not particularly limited as long as it has an insulating property. Examples thereof include synthetic resins such as polypropylene, polyethylene, nylon, polyacryl and polystyrene, and paper such as Kent paper, copy paper and carbon paper. In the present invention, these materials can be used by forming a woven cloth, a non-woven cloth, a sheet, a plate-like body and the like. The separator 3 serves as a liquid passage through which the water to be treated flows, and may be a water-permeable material such as a woven fabric or a non-woven fabric, or a porous, lattice-shaped or other formed body, or a sheet or plate. It may be one in which a large number of openings are provided in the body. If the thickness is too thick, it is necessary to increase the power supply voltage, so 10 mm or less is preferable.

In the present invention, it is necessary that the electrode and the dielectric are electrically insulated. To be electrically insulated means that electricity does not flow when water is not supplied to the desalting chamber in which the electrode and the dielectric are arranged. In order to electrically insulate the electrodes from the dielectric, for example, a space may be provided between the electrodes and the dielectric.
As illustrated in, a separator formed of an insulating material may be interposed between the electrode and the dielectric. In the present invention, it is preferable to interpose a separator.

The feed electrode (positive electrode, negative electrode) 4 is made of a metal plate (foil) such as a copper plate or an aluminum plate, a carbon plate, or a good electrical conductor such as foil graphite. Although the thickness of the positive electrode and the negative electrode 4 is not particularly limited,
Those having a thickness of about 0.05 to 10 mm are suitable. In addition,
In order to easily apply a voltage, each electrode is preferably provided with a terminal (lead) 4a.

As the holding plate 6, a flat plate made of a material such as resin that is electrically insulating and hardly deformed is used. A liquid inlet 7 for introducing the water to be treated is provided on one of the holding plates 6, 6, and a liquid outlet 8 for discharging the treated water is formed on the other. Further, a large number of fixing bolt holes are formed in both the holding plates 6, 6, and bolts are inserted into these bolt holes and fastened by nuts to form a desalination chamber. With such a configuration, the desalinated water producing apparatus 1 has a flat plate-shaped structure in which each member is pressed by the holding plates 6, 6. Note that the gaskets 5 and 5 provided between the electrodes 4 and 4 and the holding plates 6 and 6 are frames for holding the electrodes 4 and 4 and the holding plates 6 and 6 in a liquid-tight manner. It is a shape. Further, instead of providing such gaskets 5 and 5, members having a sealing function may be provided on the pressing plates 6 and 6 side. The desalination water production apparatus of the present invention has a desalination chamber formed by such a configuration.

In the desalinated water producing apparatus 1 described above, the arrangement of electrodes, dielectrics and separators is schematically shown in FIG.
Is the street. That is, the dielectric B is placed between the electrodes A on both ends.
Exists, and the separator C electrically insulates the electrode A and the dielectric B (this structure is hereinafter referred to as “unit type”).
If the dielectric B is not in contact with the electrode A, the separator C may not be present.

The desalinated water producing apparatus of the present invention is not limited to the above unit type, and various forms are possible. For example, in Figure 3
The separators C and the dielectrics B are alternately arranged between the electrodes A at both ends (multilayer type). Each dielectric B is arranged in a state of being electrically insulated by the separator C. Further, FIG. 4 shows a plurality of unit type demineralized water producing devices arranged in series (series type). With such a configuration, the demineralization chamber becomes large, and high-purity demineralized water can be obtained. Further, FIG. 5 shows a plurality of unit type demineralized water producing devices arranged in parallel (parallel type). With this configuration, a large amount of demineralized water can be obtained even if the water flow rate is slow. Moreover, since the differential pressure is small, the device has excellent durability. In addition, in the series type and the parallel type of FIGS. 4 and 5, the laminated type of FIG. 3 can be used instead of the unit type.

Next, regarding the method for producing demineralized water using the apparatus for producing demineralized water according to the present invention, the ionic substance contained in the inflow water is sodium chloride, and FIG. This will be described with reference to a) and (b). Figure 6
As shown in (a), when water to be treated is supplied and a voltage is applied, the anode side of the dielectric 2 is polarized negatively and the cathode side is polarized positively (bipolar). Sodium ions in the water to be treated are adsorbed on the negatively polarized side of the dielectric, and chlorine ions are adsorbed on the positively polarized side of the dielectric, and treated water having a low salt concentration is obtained (desalting step). The desalinated final treated water is discharged out of the system.

Further, when water is continued for a long time, the adsorption of ions to the dielectric 2 approaches saturation, so that the concentration of sodium chloride in the treated water obtained from the outlet becomes high. Therefore,
If the anode side and the cathode side are short-circuited (shorted) or reversely connected before reaching the adsorption saturation, sodium ions and chlorine ions adsorbed on the dielectric 2 are desorbed as shown in FIG. 6B. Separated, effluent containing sodium chloride having a much higher concentration than the concentration of sodium chloride in the water to be treated is discharged from the outlet (regeneration step). As shown in FIG. 1, this demineralized water producing apparatus has a flat plate-shaped structure in which each member is clamped by the holding plates 6, 6 so that the flat plate-shaped or sheet-shaped dielectric 2 is uniformly compressed. As a result, uneven flow of the liquid at the time of liquid passage is effectively prevented. Therefore, the removal rate of the ionic substance can be stabilized, and the removal rate can be sufficiently increased.

[0018]

As described above, the demineralized water producing apparatus of the present invention has the same effect as the conventional liquid-flow type electric double layer capacitor, and the dielectric polarization regardless of the conductive substance or the non-conductive substance. Since any substance that can be used can be used, there is a degree of freedom in the material used, and since it is not necessary to bring the dielectric material into close contact with the electrode, manufacturing and processing are relatively easy. Therefore, by using the method for producing demineralized water of the present invention, it is possible to produce high-purity demineralized water,
It is also advantageous from the economical point of view.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a first embodiment of a desalinated water production apparatus of the present invention.

FIG. 2 is a view schematically showing an arrangement of both electrodes, a separator, and a dielectric of a unit type demineralized water producing apparatus.

FIG. 3 is a diagram schematically showing an arrangement of both electrodes, a separator, and a dielectric of a laminated type demineralized water production apparatus.

FIG. 4 is a diagram schematically showing the arrangement of an in-line type demineralized water production apparatus.

[Fig. 5] Fig. 5 is a diagram schematically showing an arrangement of parallel-type desalinated water producing apparatuses.

FIG. 6 is a diagram for explaining the processing principle of the desalinated water production apparatus.

[Explanation of symbols]

1 ... Demineralized water production apparatus, 2 ... Dielectric material, 3 ... Separator, 4
... Positive electrode or negative electrode, A ... Supply electrode (anode or negative electrode),
B ... Dielectric, C ... Separator

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshihiro Matsushita             Kurita, 3-4-3 Nishi-Shinjuku, Shinjuku-ku, Tokyo             Industry Co., Ltd. F term (reference) 4D061 DA01 DA05 DA08 DB13 EA02                       EB01 EB04 EB14 EB19 EB23                       EB24 EB27 EB29

Claims (5)

[Claims] 1. A positive electrode and a negative electrode, a dielectric disposed between the electrodes in a state of being electrically insulated from the both electrodes, both electrodes and the dielectric are disposed, and an inlet for water to be treated and A desalination water production apparatus having: a desalination chamber having an outlet for treated water. 2. The desalinated water production apparatus according to claim 1, wherein the state of being electrically insulated from both electrodes is formed by disposing a water-permeable insulator between the electrode and the dielectric. 3. A plurality of dielectrics are arranged in a state of being electrically insulated from each other.
The desalination water production apparatus described. 4. A demineralized water production device in which a plurality of demineralized water production devices according to any one of claims 1 to 3 are arranged. 5. A method for producing demineralized water using the apparatus for producing demineralized water according to any one of claims 1 to 4.