JPH08150393A - Production of deionized water by electrolytic deionization method - Google Patents

Abstract

PURPOSE: To enhance the conductivity of a concentration chamber to improve a current effect and to economically produce deionized water by specifying the flow rate ratio of the water to be treated to concnd. water and the linear velocity of the water to be treated and concd. water when the waters are introduced into the desalting chamber and concentration chamber. CONSTITUTION: An ion exchanger is packed between a cation-exchange membrane 4 and an anion-exchange membrane 5 to constitute a desalting chamber 1, and concentration chambers 2 are formed on both sides of the desalting chamber 1 through the cation-exchange membrane 4 and anion-exchange membrane 5. The desalting chamber 1 and concentration chamber 2 are arranged between an anode 9 and a cathode 10, the water to be treated is introduced into the desalting chamber 1 while impressing a voltage, and concd. water is introduced into the concentration chamber 2 to remove the impurity ions in the water. The flow rate ratio of the water to be treated to concd. water is controlled to 6:1 to 12:1 and the linear velocity of the water to be treated and concd. water to 75-150m/hr when the waters are introduced into the desalting chamber 1 and concentration chamber 2. Consequently, the electric resistance of the concentration chamber 2 is lowered, and the conductivity is enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to the production of deionized water for efficiently producing deionized water used in various industries such as semiconductor manufacturing industry, pharmaceutical industry, food industry, or research facilities by an electric deionization method. Regarding the method.

[0002]

2. Description of the Related Art As a method for producing deionized water, a method has been conventionally known in which deionized water is passed through an ion-exchange resin to be treated. In this method, when the ion-exchange resin is saturated with ions, It is necessary to regenerate with an acid and alkaline aqueous solution, and in order to eliminate such a disadvantage in processing operation, in recent years, a deionized water production method by an electric deionization method, which does not require regeneration with a chemical, has been established and put to practical use. Has arrived.

[0003]

According to this electrodeionization method, an ion exchange resin is filled between the cation exchange membrane and the anion exchange membrane to form a desalting chamber, and the concentration is performed on both outsides of the desalting chamber. A chamber is provided, and the desalting chamber and the concentrating chamber are arranged between the positive electrode and the negative electrode, and the water to be treated flows into the desalting chamber and the concentrated water flows into the concentrating chamber while applying a voltage. In this method, deionized water is produced by removing impurity ions in the water to be treated and electrically sucking the impurity ions to move them to the concentrating chamber. According to this method, the ion exchange resin is saturated with ions. Since there is no need to regenerate with chemicals, it has the advantage of increasing the manufacturing cost from the aspect of power consumption because a high voltage is applied on the one hand. Is important to reduce It has become an issue.

What is important in solving the above problems is to facilitate the flow of electricity to the desalting chamber and the concentrating chamber, that is, to increase the conductivity of the desalting chamber and the concentrating chamber. Here, the desalting chamber is filled with an ion exchanger, and since this ion exchanger functions as a kind of conductor, the conductivity of the concentration chamber is an important factor from the viewpoint of improving conductivity. In order to solve the problem of reducing the applied voltage, it is necessary to increase the conductivity of the concentrating chamber.

Several attempts have been made to increase the conductivity of the concentrating chamber. The first attempt is to reduce the flow rate of concentrated water. In the conventional deionized water production method using the electric deionization method, the practical flow rate ratio of the water to be treated and the concentrated water is 3:
1 to 5: 1, and as a result, when the water to be treated was deionized to pure water, the concentration ratio of impurity ions in the concentrated water was 4 to 6 times. Therefore, the first attempt is to reduce the flow rate of concentrated water to increase the concentration ratio, thereby increasing the conductivity and thereby reducing the applied voltage.

However, in order to prevent the concentration gradient of ions from occurring in the concentrating chamber and prevent scale precipitation of hardness components such as Ca ions and Mg ions, the concentrated water is caused to flow at a certain flow rate to cause turbulent flow. Although it is necessary to reduce the flow rate of the concentrated water as described above, there is a problem that turbulent flow cannot be generated.

The second attempt is to increase the ionic concentration of the concentrated water by recycling the concentrated water, thereby increasing the conductivity. This method requires a tank for temporarily storing the concentrated water and a pump for sending the concentrated water from the tank to circulate the concentrated water.
There is a drawback that operation management becomes complicated.

The third attempt is to increase the conductivity by adding a chemical such as salt or acid to the concentrated water, but a new facility for supplying the chemical must be provided, and likewise the facility However, there is a drawback in that it becomes large and operation management becomes complicated.

The fourth attempt is to fill the concentration chamber with an ion exchange resin to enhance conductivity, but it is difficult to fill the ion exchange resin because the thickness of the concentration chamber is small. poor. If it is attempted to realize this, it is necessary to increase the thickness of the concentrating chamber, which causes a problem that the device becomes large.

Thus, some attempts to increase the conductivity of the concentrating chamber have their own drawbacks, and have not reached the fundamental solution.

In view of the above points, the inventors of the present invention have conducted diligent research to solve the above-mentioned problems, and as a result, by increasing the flow rate ratio and the linear velocity of the water to be treated and the concentrated water more than ever, It has been found that the amount of migrating ions can be increased, thereby increasing the conductivity of the concentrating chamber. By the way, the flow rate ratio and the linear velocity of the water to be treated and the concentrated water are also factors related to the water quality of the treated water, and if the values are too large, the water quality of the treated water may be deteriorated. Therefore, as a result of further research by the present inventors in consideration of this point, the flow ratio of the treated water to the concentrated water is set to 6: 1 to 12: 1. In addition, regarding the linear velocities of the treated water and the concentrated water, 75 to 150 m / h
It was concluded that the linear velocities of r are optimum flow rate ratios and linear velocities for solving the above problems without deteriorating the quality of treated water, respectively, and completed the present invention.

Thus, the present invention enhances the conductivity of the concentrating chamber to improve the current efficiency, thereby reducing the applied voltage, and thus economically advantageous deionized water by the electric deionization method. It is intended to provide a manufacturing method.

[0013]

According to the present invention, (1) an ion exchanger is filled between a cation exchange membrane and an anion exchange membrane to form a desalting chamber, and the above cation exchange membrane and anion exchange membrane are provided. A concentration chamber is provided on both sides of the demineralization chamber through these, and the deionization chamber and the concentration chamber are arranged between the anode and the cathode. Concentrated water is flowed into to remove the impurity ions in the water to be treated,
In the method for producing deionized water by the electric deionization method for producing deionized water, the flow ratio of the water to be treated and the concentrated water is 6:
1 to 12: 1, and the treated water and the concentrated water are introduced into the desalting chamber and the concentrating chamber so that the linear velocities of the treated water and the concentrated water are 75 to 150 m / hr, respectively. A method for producing deionized water by an electric deionization method,
(2) The desalting chamber has a thickness of 7 to 10 mm, the concentration chamber has a thickness of 0.5 to 2 mm, and the water to be treated and the concentrated water are caused to flow at a predetermined flow rate ratio and a predetermined linear velocity. 1) The method for producing deionized water by the electric deionization method according to 1), so that the inflow direction of the water to be treated into the desalting chamber and the inflow direction of the concentrated water into the concentration chamber are opposite to each other. The method for producing deionized water by the electric deionization method according to (1) or (2) above, wherein the water to be treated and the concentrated water are allowed to flow into the demineralizing chamber and the concentrating chamber, respectively, and (4) to the demineralizing chamber. The method for producing deionized water by the electric deionization method according to the above (1) or (2), wherein the treated water first passed through the anion exchanger layer, (5) the treated water flowing into the desalination chamber Water first passes through the anion exchanger layer and then the cation and anion exchanger mix. And gist the above (4) The method of producing deionized water by electrodeionization method according to pass through the ion exchanger layer.

The present invention is to produce deionized water by an electric deionization method, and in carrying out the present invention, desalting is carried out by filling an ion exchanger between a cation exchange membrane and an anion exchange membrane. Electric deionized water producing apparatus comprising a chamber, a concentration chamber provided on both sides of the desalting chamber through the cation exchange membrane and the anion exchange membrane, and an anode and a cathode arranged on both outsides of these chambers. Is used.

An example of the construction of such an electric deionized water producing apparatus is shown in FIG. Hereinafter, the present invention will be described in detail by taking the case of producing deionized water using the apparatus shown in FIG. 1 as an example.

In the figure, 1 is a desalting chamber, 2 is a concentrating chamber,
A plurality of desalting chambers 1 and concentration chambers 2 are alternately provided. Generally, when constructing the desalination chamber 1, it is manufactured as one module product. That is, a cation exchange membrane 4 and an anion exchange membrane 5 are adhered to both sides of a frame body 3 made of, for example, a synthetic resin formed in a four-circle frame shape, and an ion exchanger, for example, an ion exchange resin 6 (cation exchange membrane 6) is attached to the inner space thereof. Resin and anion exchange resin) to fill the deionization module 7, and the ion exchange resin filling portion in the deionization module 7 is configured as the deionization chamber 1.

A plurality of the deionization modules 7 are arranged side by side with a space therebetween. A spacer 8 made of a watertight member such as a rubber packing formed in a four-circle frame shape is interposed between the deionization modules 7 and 7, and the space portion thus formed constitutes the concentration chamber 2. In the internal space of the concentrating chamber 2, in order to prevent the adhesion of the ion exchange membranes 4 and 5 to each other and to secure a flow path of the concentrated water, a flow path forming material such as an ion exchange fiber or a synthetic resin net body is usually used. Is filled.

An anode 9 and a cathode 10 are arranged on both sides of the alternating arrangement of the desalting chamber 1 and the concentrating chamber 2 as described above. Partitioning films are provided in the vicinity of the anode 9 and the cathode 10, respectively, although not particularly shown. A space between the partition film and the anode 9 is configured as an anode chamber 11, and a space between the partition film and the cathode 10 is configured as a cathode chamber 12.

In the figure, 13 is a treated water inflow line, 14 is a deionized water outflow line, 15 is a concentrated water inflow line, 16
Is a concentrated water outflow line, 17 is an electrode water inflow line, and 18 is an electrode water outflow line.

In producing deionized water using the apparatus constructed as described above, the treated water inflow line 13 is used.
More water to be treated flows into the desalination chamber 1, concentrated water flows into the concentration chamber 2 through the concentrated water inflow line 15, and the anode chamber 1
1. Electrode water inflow lines 17, 17 in the cathode chamber 12 respectively
Through the electrode water. As the concentrated water, the same water as the water to be treated which is supplied to the desalting chamber 1 is usually supplied. On the other hand, a voltage is applied between the anode 9 and the cathode 10, and a direct current is passed in a direction perpendicular to the flow directions of the water to be treated and the concentrated water.

The flow rate of the treated water in the demineralizing chamber 1 must be larger than the flow rate of the concentrated water in the concentrating chamber 2. In the present invention, the flow rate ratio of the treated water to the concentrated water is from 6: 1 to 1.
It is set to 2: 1 and preferably 8: 1 to 10: 1. That is, the flow rate of the water to be treated is 6 to 12 times, preferably 8 to 10 times the flow rate of the concentrated water. Conventional general,
The flow rate ratio of the water to be treated and the concentrated water is 3: 1 to 5: 1. Compared with this conventional flow rate ratio, the flow rate of the water to be treated in the present invention is greatly increased.

In the present invention, the above flow rate ratio is 6: 1 to 1
2: 1 means that the flow rate of the treated water is 6 times the flow rate of the concentrated water.
If it is less than double, the ion concentration of the concentrated water in the concentrating chamber 2 cannot be sufficiently increased, so that the conductivity of the concentrating chamber cannot be increased, and if the flow rate of the water to be treated exceeds 12 times the flow rate of the concentrated water. This is because the efficiency of deionization may decrease and the water quality of deionized water may deteriorate.

The present invention is not required to satisfy the condition that the flow rate ratio is 6: 1 to 12: 1. Desalination chamber 1 for water to be treated within the above flow rate ratio range
Even if it flows into the desalination chamber 1, if the flow rate in the desalination chamber 1 is too slow, the desalination chamber 1
However, if the thickness of the desalting chamber 1 is too large, the current efficiency will be deteriorated, which is not preferable. Therefore, in the present invention, the linear velocity of the water to be treated flowing in the desalination chamber 1 is an important factor together with the above flow rate ratio. In the present invention, the linear velocity of the water to be treated in the desalination chamber 1 is 75 to 150 m / h.
r, preferably 90 to 120 m / hr.

In the present invention, the linear velocity is set to 75 to 150.
As described above, when the linear velocity is less than 75 m / hr, it is necessary to increase the thickness of the demineralization chamber 1 in order to obtain the same amount of demineralized water. If the linear velocity exceeds 150 m / hr, the pressure loss in the deionization chamber 1 becomes too large, which is not preferable, and the time during which the water to be treated is in contact with the ion exchange resin is shortened, resulting in deionization. This is because there is a risk that the efficiency will decrease and the quality of deionized water will decrease. That is, the larger the linear velocity of the water to be treated is, the thinner the desalination chamber 1 required to obtain the same amount of demineralized water is. Therefore, from the viewpoint of improving the current efficiency, the water to be treated is improved. The linear velocity is preferably high, but the upper limit of the linear velocity is 150 m / hr in order to perform the treatment without deteriorating the quality of deionized water.

On the other hand, the linear velocity of the concentrated water in the concentrating chamber 2 is also set to 75 to 150 m / hr. Although this numerical range is the same as the linear velocity of the water to be treated, both do not necessarily have the same numerical value.

If the linear velocity of the concentrated water is less than 75 m / hr, sufficient turbulent flow cannot be generated in the concentrated water flowing through the concentrating chamber 2. Normally, a concentration gradient of the ions transferred from the desalting chamber is generated in the concentrated water flowing through the concentrating chamber.
Cations such as a ion and Mg ion are anion exchange membrane 5
The most is distributed in the vicinity, and the anions such as Cl ions are most distributed in the vicinity of the cation exchange membrane 4. Therefore, in the case of hardness components such as Ca ions and Mg ions, there is a possibility that a phenomenon of scale deposition may occur in the concentrating chamber. In order to prevent such scale precipitation and obtain a uniform ion concentration, it is necessary to generate sufficient turbulent flow in the concentrated water, but in order to generate this turbulent flow, the linear velocity is 75 m / h.
It must be r or more.

When the linear velocity of the concentrated water exceeds 150 m / hr, the pressure loss in the concentrating chamber 2 becomes large because the channel forming material is usually filled in the concentrating chamber 2 as described above. Too practical.

Under the above conditions, the water to be treated and the concentrated water are supplied to the desalting chamber 1 and the concentrating chamber 2, respectively.
The treated water that has flowed in through the treated water inflow line 13 flows downward in the desalting chamber 1, and impurity ions are removed when passing through the packed bed of the ion exchange resin 6, whereby deionized water is obtained. The deionized water is discharged to the deionized water outflow line 14
More outflow.

On the other hand, the concentrated water flowing in from the concentrated water inflow line 15 flows upward in the concentrating chamber 2 in an upward flow. Impurity ions in the water to be treated removed in the desalting chamber 1 are electrically sucked and move to the concentration chamber 2 through the cation exchange membrane 4 or the anion exchange membrane 5. That is, among the impurity ions, cations such as Na ions are attracted to the cathode 10 side, move to the concentrating chamber 2 through the cation exchange membrane 4, and anions such as Cl ions are attracted to the anode 9 side, and the anion exchange membrane is attracted. It moves to the concentration room 2 through 5. The concentrated water flowing through the concentrating chamber 2 receives the moving impurity ions and flows out from the concentrated water outflow line 16 as concentrated water in which the impurity ions are concentrated. From the electrode water inflow line 17 to the anode chamber 11 and the cathode chamber 1
The electrode water flowing into 2 flows out from the electrode water outflow line 18.

In the present invention, the flow rate ratio of the flow rate of the water to be treated in the demineralizing chamber to the flow rate of the concentrated water in the concentrating chamber is from 6: 1 to.
Since the treated water and the concentrated water are supplied so as to have a ratio of 12: 1, and the treated water and the concentrated water are supplied so that the linear velocity thereof is 75 to 150 m / hr, the desalting chamber 1 The amount of ions transferred per unit time from the liquid to the concentrating chamber 2 increases dramatically, which can increase the ion concentration of the concentrated water in the concentrating chamber.
The electric resistance of is reduced and the conductivity is increased.

In the conventional general flow rate ratio of treated water to concentrated water of 3: 1 to 5: 1, the ion concentration ratio of concentrated water when the treated water is deionized to pure water is 4-
6 times, but the flow rate ratio in the present invention is from 6: 1 to 12: 1.
In the case of, the ion concentration ratio is 7 to 13 times. Since the value obtained by multiplying the conductivity of the concentrated water when supplied to the concentration chamber by the ion concentration ratio is the conductivity of the concentrated water near the outlet of the concentration chamber, in the present invention, the concentrated water near the outlet of the concentration chamber It means that the electric conductivity of is 7 to 13 times the electric conductivity of the concentrated water at the time of supply.

In the present invention, in order to give the specific flow rate ratio and linear velocity as described above, the thickness of the deionization chamber 1 (referred to as the distance between the cation exchange membrane 4 and the anion exchange membrane 5 facing each other): t _It is preferable that ₁ is 7 to 10 mm, and the thickness of the concentrating chamber 2 (which means the distance between the cation exchange membrane 4 and the anion exchange membrane 5 in the opposite direction): t ₂ is 0.5 to ₂ mm.

The apparatus used to carry out the present invention is not limited to that shown in FIG. For example, in the apparatus shown in the figure, the deionization chamber 1 is formed by using the deionization module 7.
The method of forming is not limited to this, and other means may be used.

The apparatus of FIG. 1 adopts a counterflow type in which the inflow direction of the water to be treated into the desalination chamber 1 and the inflow direction of the concentrated water into the concentration chamber 2 are opposite to each other. In the present invention, the inflow directions may be opposite to each other (counterflow type) or may be the same direction (parallel flow type). However, the countercurrent type has the following advantages.

That is, taking FIG. 1 as an example, the ion concentration of the water to be treated in the desalting chamber 1 is highest near the inlet of the desalting chamber, that is, at the upper part of the desalting chamber, and becomes lower as it goes downward. The ionic concentration of the concentrated water in the concentrating chamber 2 is highest near the outlet of the concentrating chamber, that is, in the upper part of the concentrating chamber, and becomes lower as it goes downward. Therefore, desalination chamber 1 and concentration chamber 2
The tendency of the concentration distribution of the same is the same, the ion concentration is highest in both the upper part of the deionization chamber 1 and the concentration chamber 2, and when deionization is performed at the high ion concentration, the deionization efficiency becomes good and the treated water The water quality is significantly improved.

As a result, even if the flow rate of the water to be treated is increased, the impurity ions can be removed more satisfactorily than in the case of the co-current system. From this point, the counter-current system is preferred in the present invention.

In the case of the parallel flow system, the ionic concentration of the concentrated water is lowest near the inlet of the concentrating chamber 2 (for example, the upper portion of the concentrating chamber in FIG. 1), and as the concentration approaches the outlet (for example, the lower portion of the concentrating chamber in FIG. 1). Get higher Therefore, in this case, the tendency of the concentration distributions in the desalting chamber 1 and the concentrating chamber 2 are opposite to each other, the concentration difference between the ion concentration in the desalting chamber and the concentrating chamber becomes large, and in the lower part of the concentrating chamber having a high ion concentration Ions may leak to the lower part of the demineralization chamber where the ion concentration is low. Leakage of ions causes contamination of treated water and must be avoided.

On the other hand, in the case of the countercurrent type, since the difference in ion concentration between the desalting chamber 1 and the concentrating chamber 2 is extremely small, there is no risk of ion leakage, and the countercurrent type is preferable also from this point.

In the present invention, the deionization chamber 1 is filled with a cation exchange resin and an anion exchange resin, but it is preferable that the water to be treated first passes through the anion exchange resin layer. Therefore, as shown in FIG. 1, when the water to be treated flows in a downward flow, it is preferable to fill the anion exchange resin in the upper part of the desalting chamber 1 and the cation exchange resin in the lower part (of course, of course). In the case of upward flow, the order is reversed). The layer structure of the anion exchange resin layer and the cation exchange resin layer may be two layers or three or more layers.

That is, the case of a downward flow will be described as an example. An embodiment in which the upper portion of the desalting chamber 1 is an anion exchange resin layer and a lower portion thereof is a cation exchange resin layer, and the upper portion is anion exchange resin layer. There is a mode in which a resin layer and a cation-exchange resin layer below the resin layer are provided, and two or more sets of laminated portions are repeatedly provided in this order, and the layer has three or more layers.

It is also possible to provide a mixed ion exchange resin layer of a cation exchange resin and an anion exchange resin. In this case, the layer constitution is such that the upper portion of the desalting chamber 1 is the anion exchange resin layer and the lower portion thereof is the cation exchange resin. As a layer, one set of this laminated part is provided or two or more sets are repeatedly provided, and a mixed ion exchange resin layer is further provided below it. A mode comprising three or more layers and an upper part thereof as an anion exchange resin layer, and a lower part thereof is mixed. There is an aspect including two layers, which are ion exchange resin layers.

Generally, weak acid components contained as impurities in the water to be treated have a small dissociation degree and are difficult to remove. For example, carbonate ion has a low dissociation degree of carbon dioxide gas in water and contains a large amount of free carbonic acid, and silicate ion has a very low dissociation degree of silica, and the present situation is that the removal rate is considerably low.

When the water to be treated first passes through the anion exchange resin layer in the desalting chamber, the removal rate of such weak acid components can be improved.
This is because when the water to be treated first comes into contact with the anion exchange resin, mainly anions among the impurity ions are deionized, and only the anions move to the concentration chamber, and cations are present in the portion of the desalting chamber. However, the amount of alkali equivalent to this cation is temporarily generated, and as a result, the water to be treated becomes alkaline temporarily, the dissociation degree of the weak acid component is improved, and the weak acid ion moves to the concentration chamber. It is considered that the removal rate can be improved by increasing the amount.

According to the present invention, the water to be treated is caused to flow at a high flow ratio,
Since the amount of impurity ions transferred to the concentrating chamber is increased, by supplying the water to be treated so that it first passes through the anion exchange resin layer, the amount of transfer of anions as impurity ions synergistically increases. However, as a result, the alkalinity of the water to be treated becomes higher, and there is an advantage that the removal efficiency of the weak acid component can be improved more than before.

In order to improve the removal rate of the weak acid component, the water to be treated first passes through the anion exchange resin layer in the desalting chamber and then passes through the mixed ion exchange resin layer of the cation exchange resin and the anion exchange resin. Is most preferable, and such a method can further improve the removal rate of the weak acid component.

The reason for this is that the mixed ion-exchange resin layer has a larger electric resistance than the anion-exchange resin layer, so that a larger amount of current flows through the anion-exchange resin layer to remove the anions as impurity ions and to remove the anions. It is believed that this is based on the efficient transfer of the to the concentrating chamber.

According to the present invention, the frame 3 and both ion exchange membranes 4, 5 are used.
At the time of filling the space portion between and with the ion exchange resin 6, the deionization chamber 1 can be divided into a plurality by providing the frame 3 with a dividing bar.

In the present invention, as the ion exchange resin,
MR type or MP type (macroporous type) with a huge mesh structure
It is preferable to use the ion exchange resin of. The resin has an advantage that it has excellent physical strength and can prevent bead fragmentation.
By the way, heretofore, there has been a problem that the flow path in the desalting chamber is blocked by the crushing of beads.

That is, a deionized water outlet is provided in the frame 3 constituting the demineralizing chamber, and a dividing bar is provided to divide the demineralizing chamber into, for example, two upper and lower chambers. A treated water passage port is provided on the crossbar, and a saran net is usually attached to these outflow ports and passage ports so that resin particles of the ion exchange resin do not pass through. However, when the beads were crushed, the crushed pieces did not pass through the saran net and were clogged there, resulting in the problem of blocking the flow path in the desalination chamber.

The present invention can solve this problem by using an ion exchange resin having a huge network structure such as the MR type ion exchange resin described above.
The treated water passage port and the deionized water outlet port in the desalting chamber are preferably configured as a comb-shaped screen having a slit gap that does not allow the ion exchange resin particles to pass but allows the crushed beads to pass.

According to this structure, even if beads of the MR type ion-exchange resin are crushed, the crushed fragments pass through the slits of the screen, so that the flow path can be prevented from being blocked and the demineralization chamber can be prevented. There is an advantage that the flow velocity distribution can be made uniform. In this case, it is preferable to replaceably attach a porous filter having a pore diameter of 100 μm or less to an appropriate position of the deionized water outflow line 14 so as to collect the fragmented beads.

[0052]

【Example】

Examples, Comparative Examples Industrial water having the water quality shown in Table 1 was treated with a reverse osmosis membrane device to obtain permeated water having the water quality shown in the table. This permeated water was used as water to be treated and concentrated water, and was supplied to an electric deionized water producing apparatus as shown in FIG. In this case, the device is
A configuration in which two deionization modules are arranged in parallel (Example) and a configuration in which four deionization modules of the same size are arranged in parallel (Comparative Example 1 and Comparative Example 2)
Was used. Water to be treated and concentrated water were passed through the desalting chamber and the concentrating chamber in these devices to produce deionized water. However, unlike FIG. 1, both the water to be treated and the concentrated water were passed in a downward flow (that is, water was passed in a parallel flow type). The conditions of the flow rate ratio of the treated water and the concentrated water, the linear velocity of the treated water and the concentrated water, and the flow rate of the deionized water obtained at this time are as shown in Table 2.
The deionization module used had a desalting chamber thickness t ₁ of 8 mm and a concentrating chamber thickness t ₂ of 0.8 mm, and the desalting chamber had a mixture of a cation exchange resin and an anion exchange resin. The entire salt chamber was filled to a height of 600 mm.

[0053]

[Table 1]

[0054]

[Table 2]

The applied voltage and the direct current value are as shown in Table 3. The applied voltage has a deionized water resistivity of 10 MΩ.
The applied voltage required to obtain deionized water having good water quality of not less than cm. The electrical conductivity of the concentrated water at the outlet of the concentrated water was measured, and the presence or absence of scale formation of hardness component after continuous operation for 1000 hours was observed. The results are shown in Table 3.

[0056]

[Table 3]

As is clear from the above results, the present invention has a device scale half that of Comparative Examples 1 and 2 which are conventional examples.
Moreover, it is possible to obtain deionized water having substantially the same amount and the same water quality as in Comparative Examples 1 and 2 with a lower applied voltage than Comparative Examples 1 and 2. Moreover, it can be seen that scale formation of the hardness component does not occur even though the electrical conductivity of the concentrated water is high (that is, the ion concentration of the concentrated water is high).

[0058]

As described above, according to the present invention, the water to be treated and the concentrated water are allowed to flow into the desalting chamber and the concentrating chamber, respectively, at a specific flow rate ratio and linear velocity. The amount of the generated impurity ions transferred to the concentrating chamber increases, which increases the conductivity of the concentrating chamber and reduces the electric resistance of the entire device. As a result, in the case of obtaining the same amount of deionized water, it becomes possible to manufacture deionized water with good treated water quality even if the applied voltage is lowered, and there is an effect that power consumption can be reduced.

Further, according to the present invention, since the water to be treated is supplied at a flow rate ratio higher than the conventional one, the amount of deionized water produced in the same scale of equipment also increases, and as a result, the equipment becomes large in size. It has an effect that a large amount of processing can be performed without the need.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view showing an example of an electric deionized water producing apparatus used for carrying out the method of the present invention.

[Explanation of symbols]

 1 Desalination chamber 2 Concentration chamber 4 Cation exchange membrane 5 Anion exchange membrane 6 Ion exchange resin 9 Anode 10 Cathode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsumi Okugawa 5-5-16 Hongo, Bunkyo-ku, Tokyo Organo Corporation

Claims (5)

[Claims] 1. A desalting chamber is formed by filling an ion exchanger between a cation exchange membrane and an anion exchange membrane, and a concentration chamber is provided on both sides of the desalination chamber through the cation exchange membrane and the anion exchange membrane. The demineralizing chamber and the concentrating chamber are provided between the anode and the cathode, and the water to be treated flows into the demineralizing chamber while applying a voltage. In a method for producing deionized water by an electric deionization method, which removes impurity ions and produces deionized water, the flow ratio of the water to be treated and the concentrated water is 6: 1 to 12: 1, and the water to be treated and the concentrated water are concentrated. A method for producing deionized water by an electric deionization method, wherein water to be treated and concentrated water are made to flow into a desalting chamber and a concentrating chamber, respectively, so that the linear velocity of water is 75 to 150 m / hr. . 2. The desalination chamber has a thickness of 7 to 10 mm and the concentration chamber has a thickness of 0.5 to 2 mm, and the water to be treated and the concentrated water are caused to flow at a predetermined flow rate ratio and a predetermined linear velocity. The method for producing deionized water according to claim 1, wherein the electrodeionization method is used. 3. The desalination chamber and the concentrating chamber are treated so that the inflow direction of the treated water into the desalting chamber and the inflowing direction of the concentrated water into the concentrating chamber are opposite to each other. 3. The method for producing deionized water according to claim 1, wherein the deionized water is made to flow into the chamber. 4. The method for producing deionized water by the electric deionization method according to claim 1, wherein the water to be treated which has flowed into the deionization chamber first passes through the anion exchanger layer. 5. The method according to claim 4, wherein the water to be treated which has flowed into the desalting chamber first passes through the anion exchanger layer and then passes through the mixed ion exchanger layer of the cation exchanger and the anion exchanger. Method for producing deionized water by electric deionization method.