JP2002336864A - Desalted water making method and desalted water making apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a desalted water making method capable of preventing scale deposition at a concentration chamber and also capable of keeping the treating efficiency for obtaining the desalted water from raw water in a good state. SOLUTION: In the desalted water making method, raw water is supplied to a continuous electrically deionizing unit 30 having the concentration chamber 35 and a dilution chamber 36, and desalted water is collected from the dilution chamber 36, and the concentrated water discharged from a concentration chamber 35 outlet is circulated to a concentration chamber 35 inlet. When the hardness of the concentrated water is higher than a previously set reference value, the effluent obtained by passing the concentrated water through a flow-through type electric double-layer capacitor 2 is circulated to the concentration chamber 35 inlet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the supply of water for boilers in power plants, the production of semiconductors, the production of pure water used for fuel cell power generation, the production and circulation of water for cooling towers, and the collection of various wastewaters. The present invention relates to a method and an apparatus for producing desalinated water used.

[0002]

2. Description of the Related Art Demineralized water and so-called pure water are widely used in semiconductor manufacturing plants, nuclear power plants, fuel cell power generators and the like. As a method for producing such desalted water or pure water, a plurality of anion exchange membranes and cation exchange membranes are alternately arranged between electrodes to form a concentration chamber and a dilution chamber alternately, and an anion exchange resin is provided in the dilution chamber. 2. Description of the Related Art A continuous electrodeionization apparatus for filling a mixture with a cation exchange resin in a mixed state is known (JP-A-61-107906).

[0003] The deionization of water by such a continuous electrodeionization apparatus will be described with reference to FIG. In FIG. 6, the applied current potential is represented by (+) and (−).
In this example, reference numeral 30 denotes a continuous electrodeionization device, and the continuous electrodeionization device 30 includes a concentration chamber 35a between an anion exchange membrane 31 and a cation exchange membrane 32.
A dilution chamber 36 is provided between the cation exchange membrane 32 and the anion exchange membrane 33 to form an anion exchange membrane 33 and a cation exchange membrane 34.
A concentration chamber 35b is formed between the two, and a dilution chamber (not shown) and a concentration chamber (not shown) are formed alternately in the same manner. The dilution chamber 36 is filled with a mixed resin of a cation exchange resin 37 and an anion exchange resin 38. The filling of the dilution chamber 36 may be any good electric conductor, but is preferably an ion exchange resin. Examples of the ion exchange resin include, for example, those obtained by introducing a sulfonic acid group in the case of a cation exchange resin and a quaternary ammonium group in the case of an anion exchange resin to a styrene polymer crosslinked with divinylbenzene. Powdery, fibrous, film-like materials and the like can be used.

When ions in raw water are represented by Na ⁺ and Cl ⁻ , ions entering the dilution chamber 36 are ion-exchange resin 3 based on affinity, concentration and mobility.
Reacts with 7,38. The ions move through the resin in the direction of the potential gradient, and further across the membrane 32 or 33, keeping charge neutralization in all chambers. And
Due to the semi-osmotic properties of the membrane and the direction of the potential gradient, the ions in the solution are reduced in the dilution chamber 36 and concentrated in the adjacent concentration chambers 35a and 35b. Therefore, deionized water is recovered from the dilution chamber 36. The continuous electrodeionization apparatus does not require chemical regeneration like an ion-exchange resin, can perform perfect continuous water sampling, and has an excellent effect that extremely high-purity water can be obtained.

[0005]

By the way, in such a continuous electrodeionization apparatus 30, the concentrated water derived from the concentration chamber is discharged to the outside of the production line simply by passing the raw water. Therefore, there is a problem that the treatment efficiency for obtaining the desalinated water from the raw water is poor, and the cost and productivity are poor.

The present invention has been made in view of the above circumstances, and has as its object to prevent scale precipitation in a concentration chamber and maintain a good treatment efficiency for obtaining desalinated water from raw water. It is an object of the present invention to provide a desalinated water producing method which can be performed and a desalinated water producing apparatus suitable for performing the method.

[0007]

In the method for producing demineralized water according to the present invention, raw water is supplied to a continuous electrodeionization apparatus having a concentration chamber and a dilution chamber, and demineralized water is sampled from the dilution chamber. A method for producing desalinated water in which concentrated water discharged from an outlet is circulated to an inlet of a concentrated chamber, wherein when the hardness of the concentrated water is higher than a predetermined reference value, the concentrated water is passed through a liquid-type electric double layer condenser. Circulating the effluent obtained as described above to the inlet of the concentrating chamber is a means for solving the above-mentioned problem.

According to this manufacturing method, when the hardness of the concentrated water led out of the concentration chamber is higher than the reference value, the concentrated water is passed through the liquid-type electric double layer condenser for processing.
Since the obtained treated water is circulated to the concentrating chamber, the concentrated water circulated to the concentrating chamber always has a hardness lower than the reference value, and therefore, scale precipitation due to the hardness component in the concentrating chamber is prevented.

In the apparatus for producing desalinated water of the present invention, a continuous electrodeionization apparatus having a raw water inlet, a desalinated water outlet, a concentration chamber, and a dilution chamber, a flow-through electric double layer condenser, A first circulating means for circulating the discharged concentrated water to the concentration chamber inlet, and a second means for circulating the concentrated water in the order of the concentration chamber outlet, the flow-through type electric double layer condenser, and the concentration chamber inlet.
And a means for measuring the hardness of the concentrated water and a means for controlling the flow of liquid to the first and second circulation means based on the measured hardness value.

According to this manufacturing apparatus, since the hardness detecting means is provided on the inlet side of the flow-through type electric double layer condenser provided in the circulation path, when the hardness of the concentrated water led out from the concentration chamber is high, This concentrated water is passed through a liquid-type electric double layer condenser to remove the hardness component and to circulate the concentrated component in the concentration chamber, thereby preventing scale precipitation due to the hardness component in the concentration chamber.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The present inventor has earnestly studied to solve the above-mentioned problems, and has obtained the following findings. That is, as shown in FIG. 7, a part of the concentrated water C led out from the concentration chamber 35 can be discharged, and the remaining part can be circulated to the concentration chamber 35. That is, for example, conventionally, 1300 liters of raw water per hour is passed through the continuous electrodeionization apparatus 30, and the dilution water D
1000 liters / hour and 300 liters / hour of concentrated water C, and the entire amount of the concentrated water C was discharged out of the production line. In the example shown in FIG. The liter is discharged and 200 liters are circulated to the concentration chamber 35.

As a result, 1100 liters of raw water is passed through the continuous electrodeionization apparatus 30, 100 liters of which are flowed into the concentration chamber 35 together with the circulated concentrated water C, and 1000 liters are flowed into the dilution chamber 36. This makes it possible to produce 1000 liters of dilution water D per hour. Therefore, conventionally, raw water 1300
While 1000 liters of dilution water D is obtained from 1 liter, according to the method shown in FIG. 7, dilution water D of 1100 liters of raw water to 1000 liters can be obtained.

However, even in this case, since the concentrated water C is circulated, even if the concentrated water C is diluted with raw water, the hardness component (Ca ion, M
(g ions) are concentrated, and scale is deposited. This scale hindrance sometimes lowers processing efficiency and impairs stable operation.

The present invention has been made to solve such inconvenience. FIG. 1 is a diagram showing an embodiment of a desalinated water producing apparatus according to the present invention. In FIG. 1, reference numeral 1 denotes a desalinated water producing apparatus. As described above, the desalinated water producing apparatus 1 includes a continuous electric deionization apparatus 30 having the dilution chamber 36 and the concentration chamber 35, the liquid-flow type electric double layer condenser 2, and the liquid-flow type electric double layer condenser. 2 and a hardness detecting means 3 provided on the inlet side. The continuous electrodeionization apparatus 30 has the same configuration as that of the conventional one described for the deionization action with reference to FIG. It has a circulation path 4 that circulates on the inlet side. Note that a liquid feed pump P is provided in the circulation path 4.

The liquid-permeation type electric double layer capacitor 2 has a structure in which two conductor layers having a high specific surface area are interposed with a liquid passage therebetween, and a collector electrode is arranged outside these conductor layers. By applying a voltage to the collector electrode, ions in the raw water are electrically adsorbed to the conductor layer, and treated water having a reduced salt concentration can be obtained. Activated carbon is suitable as such a conductor having a high specific surface area. In this example, the liquid-permeation type electric double layer capacitor 2 is provided in the circulation path 4 and has a structure shown in FIG.
As shown in (a) and (b), activated carbon layers 6 and 6 mainly composed of activated carbon having a high specific surface area are arranged with a separator 5 made of an electrically insulating porous liquid-permeable sheet interposed therebetween. , 6 are arranged outside the collecting electrodes 7, 7, and press plates 9, 9 are arranged outside the collecting electrodes 7, 7 via gaskets 8, 8.

The separator 5 includes a filter paper, a porous polymer membrane,
Woven fabrics, non-woven fabrics, etc., made of organic or inorganic sheets with easy liquid passage and electrical insulation
The thickness is preferably about 0.01 to 0.5 mm, particularly about 0.02 to 0.3 mm.

The activated carbon layer 6 is formed of a layer mainly composed of activated carbon having a high specific surface area. The high specific surface area activated carbon has a BET specific surface area of 1000 m ² / g or more, preferably 1500 m ² / g or more, more preferably 200 m ² / g or more.
0 to 2500 m ² / g activated carbon. If the BET specific surface area is too small, the removal rate of the ionic substance when passing through a liquid (raw water) containing the ionic substance decreases.
If the BET specific surface area is too large, the removal rate of ionic substances tends to decrease rather.
It is not necessary to increase the T specific surface area more than necessary.

The activated carbon constituting the activated carbon layer 6 can be in any shape such as powder or granule, or fibrous.
In the case of a powdery or granular material, it is used after being formed into a flat plate or a sheet. In the case of a fibrous material, it is used after being processed into a woven or nonwoven fabric. When powdered and granular activated carbon is formed into a flat plate or sheet, it is significantly more advantageous in terms of cost than when fibrous activated carbon is processed into a woven or nonwoven fabric.

For forming the granular activated carbon into a flat plate or a 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.). This can be carried out by forming into a plate shape and, if necessary, subjecting it to a heat treatment. When the activated carbon layers 6 and 6 are formed into a flat plate or a sheet, the perforations may be formed as necessary. The thickness of the activated carbon layer 6 is preferably about 0.1 to 3 mm, particularly about 0.5 to 2 mm, but is not necessarily limited to this range.

The collector electrode 7 is made of a good electrical conductor such as a copper plate, an aluminum plate, a carbon plate, or foil-like graphite, and is formed and arranged in close contact with the activated carbon layer 6. The thickness of the collector 7 is not particularly limited, but is preferably about 0.1 to 0.5 mm. Note that each of the collector electrodes 7 is provided with a terminal (lead) 7a to facilitate application of a voltage.

As the holding plate 9, a flat plate made of a material such as resin which is electrically insulating and hardly deformed is used. A liquid inlet 10 is formed on one of the holding plates 9 and 9, and a liquid outlet 11 is formed on the other. A large number of fixing bolt holes 12 are formed in both holding plates 9, 9, and bolts 13 are inserted into these bolt holes 12, 12 and fastened by nuts 14. With such a configuration, the liquid-permeation type electric double layer capacitor 2 has a plate-like structure in which each member is pressed by the holding plates 9, 9.

The gaskets 8, 8 provided between the collecting electrodes 7, 7 and the holding plates 9, 9 maintain the gap between the collecting electrodes 7, 7 and the holding plates 9, 9 in a liquid-tight manner. It is a frame shape for. Instead of providing the gaskets 8, 8, a member having a sealing function may be provided on the holding plates 9, 9.

In the flow-through type electric double layer capacitor 2 having such a configuration, a liquid containing ionic substances (raw water in the present invention) is treated according to the principle described below. This processing principle will be described with reference to FIGS. 3A and 3B in a case where the liquid containing an ionic substance is a saline solution, for example. When a voltage is applied, the liquid flows as shown in FIG. The sodium ions in the liquid water are electrically adsorbed on the activated carbon layer 6 in contact with the collector electrode 7 on the anode side, and the chloride ions are electrically adsorbed on the activated carbon layer 6 in contact with the collector electrode 7 on the cathode side. Therefore, the purified water (treated water) obtained from the liquid outlet has a significantly reduced salt concentration.

Further, if the liquid is continuously passed for a long time, the adsorption of both ions to the activated carbon layers 6 reaches saturation, so that the salt concentration of the treated water obtained from the liquid outlet becomes close to the salt concentration of the raw water. . Therefore, if the cathode side and the anode side are short-circuited or connected in reverse at an appropriate timing, the sodium ions and chlorine ions adsorbed on the activated carbon layers 6, 6 are desorbed as shown in FIG. The influent containing sodium chloride at a concentration much higher than the salt concentration in the influent is discharged from the outlet. It is preferable to reduce the flow rate at this time, because sodium chloride adsorbed on the activated carbon layer can be discharged with a small amount of outflow water.

Such a flow-through type electric double layer capacitor 2
In this case, since each member has a plate-like structure pressed by the holding plates 9, 9, the plate-like or sheet-like activated carbon layers 6, 6 are evenly compressed, so that when the liquid flows, The drift of the liquid is effectively prevented.
Therefore, the removal rate of the ionic substance is stabilized, and the removal rate is sufficiently increased.

The hardness detecting means 3 is provided in the circulation path 4 similarly to the flow-through type electric double layer capacitor 2,
This is provided on the inlet side of the flow-through type electric double layer capacitor 2 and is used to determine whether or not to perform the ion removal processing in the flow-through type electric double layer capacitor 2 as described later. is there. The hardness detecting means 3 is constituted by a conductivity meter or a calcium or magnesium ion concentration meter, and detects the hardness of the concentrated water flowing in the circulation path 4, that is, the content of calcium ions and magnesium ions. This is to detect whether the value is equal to or less than a set reference value.

When a conductivity meter is used as the hardness detecting means 3, the relationship between the hardness of the raw water and the conductivity is determined in advance by experiments or the like, and the hardness is estimated from the conductivity based on the result. Such a method is adopted. Similarly, when an ion concentration meter is used, a method is employed in which the relationship between the hardness of raw water and the concentration of each ion is checked, and the hardness is estimated from the measured ion concentration based on the result. In the present embodiment, a conductivity meter is employed as the hardness detecting means 3.

In this embodiment, the reference value of the hardness of the concentrated water, that is, the reference value for determining whether or not to perform the ion removal treatment in the electric double layer condenser 2 is, for example, 5 ppm in terms of calcium carbonate. And Therefore, when the concentrated water C derived from the concentration chamber 35 is higher than the reference value, the concentrated water C is subjected to the ion removal treatment by the liquid-flow type electric double layer condenser 2, while the concentrated water C is reduced to the reference value. If the concentration is equal to or lower than this, the concentrated water C is circulated to the concentration chamber 35 without being treated by the liquid-type electric double layer condenser 2.

Hereinafter, an example of the desalinated water production method of the present invention will be described based on the operation method of the desalinated water production apparatus 1 having such a configuration. In this example, the raw water is supplied to the continuous electrodeionization apparatus 30 in the same manner as the case shown in FIG.
The dilution water D was passed through at a flow rate of 00 liters, 100 liters of which were allowed to flow into the concentration chamber 35, and 1000 liters were allowed to flow into the dilution chamber 36, whereby the dilution water D was supplied at a rate of 1000 liters per hour.
L to produce. Also, 300 liters of concentrated water C is drawn out from the concentration chamber 35 per hour, 100 liters of which are discharged out of the system of the production line, and 200 liters are circulated to the concentration chamber 35 together with 100 liters of raw water.

When the desalinated water composed of the dilution water D is produced in this manner, it is taken out of the concentration chamber 35 and returned to the concentration chamber 3 again.
The concentrated water C circulated to 5 is not unconditionally introduced into the concentrating chamber 35 without any change, but its hardness is detected by the hardness detecting means 3 as described above, and whether or not the hardness is higher than a preset reference value is determined. Ask for. If this is higher than the reference value, that is, if the degree of contamination of the concentrated water C is high, the concentrated water C is passed through the liquid-flow type electric double layer condenser 2.
Through which the ions of Ca and Mg are removed, and the resulting treated water is concentrated in the concentration chamber 3 of the continuous electrodeionization apparatus 30.
Introduce to 5. That is, it is made to pass through a route serving as the second circulation means in the present invention.

On the other hand, when the concentrated water C matches or is lower than the reference value, the concentrated water C is circulated to the concentration chamber 35 without being processed by the liquid-type electric double layer condenser 2. Specifically, a bypass 15 is provided in the circulation path 4, and by operating the valves 16 and 17, the concentrated water C is prevented from passing through the liquid-type electric double layer condenser 2. That is, it is made to pass through a route serving as the first circulation means in the present invention. By forming the valves 16 and 17 by electromagnetic valves or the like, the hardness detecting means 3
It is also possible to automatically switch the opening and closing of these valves 16 and 17 by a control means (not shown) based on the result of the detection in (1), that is, whether or not the hardness of the concentrated water C is higher than the reference value. After regenerating the liquid-flow type electric double layer capacitor 2, the concentrated water may be passed through the liquid-flow type electric double layer capacitor 2 in a state where power is not supplied by switching from the bypass 15.

In such a method for producing desalinated water,
When the hardness of the concentrated water C led out of the concentration chamber 35 is higher than the reference value, the concentrated water C is passed through the liquid-type electric double layer condenser 2 to perform ion removal treatment, and the obtained treated water is discharged. Since the water is circulated to the concentration chamber 35, the concentrated water C circulated to the concentration chamber 35 can always have a hardness lower than the reference value. In addition, a reduction in processing efficiency due to scale failure can be suppressed, and operation can be stabilized.

When the concentrated water C is equal to or lower than the reference value, the concentrated water C is passed through the flow-through type electric double layer condenser 2.
In this case, the concentration of the concentrated water (processed water) circulated through the concentration chamber 35 is greatly changed by excessively treating the concentrated water C. Inconveniences such as impairing stable operation of the continuous electrodeionization device 30 can be avoided,
In addition, by minimizing the operation of the flow-through type electric double layer capacitor 2, the operation cost can be reduced.

In the above example, a part of the concentrated water C is discharged out of the system of the production line. However, in the demineralized water production apparatus of the present invention, the flow-through electric double layer condenser 2 Since the circulation path 4 is normally operated without blowing, the regenerated wastewater can be discharged only when the liquid-flow type electric double layer condenser 2 is regenerated by providing the hardness detector 3 and the hardness detection means 3. That is, in the demineralized water production apparatus 1 of the present invention, as shown in FIG. 4, raw water is passed through the continuous electrodeionization apparatus 30 at a flow rate of 1000 liters / hour, and the entire amount is allowed to flow into the dilution chamber 36. On the other hand, the concentrated water C can be circulated at a flow rate of 300 liters / hour through the circulation path 4 that circulates through the concentration chamber 35.

In such an operation, the hardness detecting means 3 detects whether or not the hardness of the concentrated water C led out of the concentration chamber 35 is higher than a reference value, as in the example shown in FIG. When the concentration is high, the concentrated water C is passed through the liquid-type electric double layer condenser 2, while when the concentration is not high, the liquid C is concentrated without operating the liquid-permeation type electric double layer condenser 2 or through the bypass 15. Circulate in chamber 35.

According to such an operation method, in particular, the flow-through type electric double layer condenser 2 is provided in the circulation path 4 and the concentrated water C
Is reduced so as to circulate through the concentration chamber 35, so that the entire concentrated water C can be circulated without diluting it with the raw water, and thus the raw water with respect to the obtained desalinated water (dilution water D) Of deionized water can be made with very high efficiency.

When the liquid-flow type electric double-layer condenser 2 reaches the adsorption saturation, the raw water is introduced into the liquid-flow type electric double-layer condenser 2 and the liquid-flow type electric double-layer condenser 2 is operated. By short-circuiting the collector electrodes 7 of the multilayer capacitor 2 or applying a reverse voltage, impurities such as ions adsorbed on the activated carbon layer 6 are eluted and discharged out of the system.

Although the scale component (Ca, Mg) is removed by the flow-through type electric double layer condenser 2, the concentrated water C circulated to the concentration chamber 35 always has a hardness lower than the reference value. At the same time, the ion concentration also decreases, and the operating efficiency of the continuous electrodeionization device 30 may decrease. Therefore, it is preferable to add a salt (or an aqueous solution thereof) that does not become a scale component such as sodium chloride to the concentrated water C from which the flow-through type electric double layer capacitor 2 is led out so as to maintain the ion concentration of the concentrated water C at a certain level or more. desirable.

Also, in the present invention, the liquid-flow type electric double-layer capacitor is replaced with the liquid-flow type electric double-layer capacitor 2 shown in FIGS. 2A and 2B, as shown in FIG. The liquid-flow type electric double layer capacitor 50 disclosed in JP-A-11-505463 can also be used.

This liquid passing type electric double layer capacitor 50 is
Two end plates 23 spaced apart on opposite sides
1 and 232 and two single-sided terminal electrodes 233 and 234 adjacent to each other with the insulating layers 235 and 236 interposed therebetween. Each of the terminal electrodes 233 and 234 has a collector made of a titanium sheet and a sheet made of a conductor (here, activated carbon) having a high specific surface area joined to one side of the collector by a binder such as conductive epoxy. Two end electrodes 233, 23
4, the two-sided intermediate electrodes 237 to 243 are arranged at equal distances from each other. Each double-sided electrode (for example, 237) is obtained by joining an activated carbon sheet to both sides of a collector electrode made of a titanium sheet. The number of the intermediate electrodes is not limited, and is appropriately adjusted so as to have a surface area capable of obtaining a necessary capacity (FIG. 5 shows seven double-sided intermediate electrodes 237 to 24).
Only three are shown).

Each electrode of the liquid-permeation type electric double layer capacitor having such a configuration is alternately used as an anode and a cathode. That is, for example, the terminal electrode 233, the intermediate electrodes 238, 24
0, 243 as anodes, and intermediate electrodes 237, 239,
241, 242 and the terminal electrode 234 are used as cathodes. Then, each adjacent electrode pair (anode and cathode) forms an independent processing chamber.

Therefore, when the raw water is introduced into the liquid-flow type electric double layer condenser 50, first, as shown by the arrow A, the raw water passing through the first processing chamber 250 flows substantially parallel to the electrode surface. Then, since the electrodes on both sides are polarized, the ions are electrostatically removed from the raw water, and are retained in the electric double layer formed on the activated carbon layer surfaces of the electrodes 233 and 237.

The raw water is then supplied to the hole 2 as indicated by the arrow B.
It flows through 63 to the next processing chamber. Here, the ions in the raw water are further removed by the polarization of the processing chamber formed by the intermediate electrodes 237 and 238. Then, the raw water is continuously passed through the remaining processing chambers as shown by arrows C to G, and the ions are removed. afterwards,
As indicated by the arrow H, the treated water passes through the terminal electrode 234, the insulating layer 236, etc.
Is derived from

Therefore, even in such a liquid-flow type electric double-layer capacitor 50, various ions such as metal ions such as calcium and magnesium are extracted from raw water similarly to the liquid-flow type electric double-layer capacitor 2. Thus, it is possible to replace the capacitor 2 with the liquid-flow type electric double layer capacitor 2.

[0045]

As described above, according to the method for producing desalinated water of the present invention, the treated water is circulated to the concentrating chamber, whereby the treatment efficiency for obtaining the desalinated water from the raw water is improved. It can be maintained and the concentrated water circulated to the concentration chamber always has a hardness lower than the reference value, preventing scale precipitation due to hardness components in the concentration chamber and suppressing a decrease in treatment efficiency due to scale obstacles In addition, the operation can be stabilized.

When the concentrated water is not higher than the reference value, if the concentrated water is circulated to the concentration chamber without being treated by the liquid-type electric double layer condenser, the concentrated water can be treated excessively. As a result, the ion concentration of the concentrated water (treated water) circulated to the concentration chamber fluctuates greatly, which can avoid the disadvantage of impairing the stable operation of the continuous electrodeionization apparatus. By minimizing the operation of the condenser, the operation cost can be reduced. Furthermore, by providing the flow-through type electric double layer condenser in the circulation path, it is possible to circulate the entire amount of the concentrated water drawn out of the concentration chamber, and thus to reduce the amount of raw water with respect to the obtained desalinated water (dilution water). It can be close to 1: 1 so that demineralized water can be produced with very high efficiency.

According to the desalinated water producing apparatus of the present invention, the hardness detecting means is provided on the inlet side of the flow-through type electric double layer condenser provided in the circulation path. When the concentration is high, the concentrated water can be passed through the liquid-type electric double layer condenser to remove the hardness component and to circulate the concentrate in the concentration chamber, thereby preventing scale precipitation due to the hardness component in the concentration chamber. . Therefore, it is possible to suppress the decrease in the processing efficiency due to the scale failure, to stabilize the operation, and to produce the demineralized water with extremely high efficiency.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a schematic configuration of an embodiment of a desalinated water producing apparatus according to the present invention.

FIGS. 2A and 2B are diagrams showing a schematic configuration of a flow-through type electric double layer capacitor, wherein FIG. 2A is an exploded perspective view and FIG. 2B is a side sectional view.

3 (a) and 3 (b) are diagrams for explaining the processing principle of the liquid-permeation type electric double layer capacitor shown in FIG. 2.

FIG. 4 is a diagram for explaining an operation method when the circulation path of the desalinated water producing apparatus shown in FIG. 1 is used as a closed system.

FIG. 5 is a side sectional view showing a schematic configuration of another example of the flow-through type electric double layer capacitor.

FIG. 6 is a diagram for explaining the deionizing action of water by a continuous electrodeionization device.

FIG. 7 is a diagram for explaining a schematic configuration of an example of a desalinated water producing apparatus using a continuous electrodeionization apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Demineralized water manufacturing apparatus, 2, 50 ... Pass-through electric double layer condenser, 3 ... Hardness detecting means, 4 ... Circulation path, 30 ... Continuous electric deionization apparatus, 35 ... Concentration chamber, 36 ... Dilution chamber, C …
Concentrated water, D: dilution water

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Keihiro Matsushita F-term (reference) in Kurita Kogyo Co., Ltd. 3-7-4 Nishishinjuku, Shinjuku-ku, Tokyo 4D006 GA17 JA30Z JA43Z JA44Z JA51A KA41 KB01 KE14P MA13 MA14 MB07 MC24 PA01 PB02 PC01 PC31 4D061 DA02 DB13 DB18 EA09 EB05 EB12 EB13 EB17 EB23 EB30 GA21

Claims (2)

[Claims] 1. A method for supplying raw water to a continuous electrodeionization apparatus having a concentration chamber and a dilution chamber, collecting demineralized water from the dilution chamber, and circulating concentrated water discharged from an outlet of the concentration chamber to an inlet of the concentration chamber. If the hardness of the concentrated water is higher than a predetermined reference value, the effluent obtained by passing the concentrated water through the liquid-type electric double layer condenser is circulated to the inlet of the concentration chamber. A method for producing desalinated water, comprising: 2. A continuous electrodeionization apparatus having a raw water inlet, a desalinated water outlet, a concentration chamber, and a dilution chamber, a flow-through type electric double layer condenser, and a concentrated water discharged from the concentration chamber outlet. First circulating means for circulating to the chamber inlet; second circulating means for circulating the concentrated water in the order of the outlet of the concentrating chamber, the flow-through electric double layer condenser, and the inlet of the concentrating chamber; and means for measuring the hardness of the concentrated water. An apparatus for producing deionized water, comprising means for controlling the flow of liquid to the first and second circulation means based on the measured hardness value.