WO1997046491A1

WO1997046491A1 - Process for producing deionized water by electrical deionization technique

Info

Publication number: WO1997046491A1
Application number: PCT/JP1996/001517
Authority: WO
Inventors: Yasutaka Shinmei; Koichi Hosoda; Makio Tamura; Katsumi Okugawa
Original assignee: Organo Corporation
Priority date: 1994-11-29
Filing date: 1996-06-03
Publication date: 1997-12-11

Abstract

A conventional process for producing deionized water by the electrical deionization technique using an electrical deionization apparatus provided with desalting chambers and concentration chambers arranged alternately is problematic in that the power consumption is high, though it is advantageous in that it can dispense with the regeneration of ion-exchange resins by using chemicals. In order to solve this problem, the process of the invention comprises supplying nontreated water and nonconcentrated water to, respectively, the desalting chambers and the concentration chambers in such a manner that the ratio of the flow rate of nontreated water to that of nonconcentrated water ranges from 6:1 to 12:1 and the linear velocity of both of the waters ranges from 75 to 150 m/h. The above-specified ratio and velocity are necessary to increase the amount of migration of impurity ions toward the concentration chambers to thereby increase the conductivity of these chambers.

Description

Description Method for producing deionized water by electric deionization

The present invention relates to a deionized water production method for efficiently producing deionized water used in various industries such as a semiconductor manufacturing industry, a pharmaceutical industry, and a food industry, or a research facility, by an electrodeionization method. Background art

As a method for producing deionized water, there has been conventionally known a method in which deionized water is passed through water to be treated through an ion exchange resin. In this method, when the ion exchange resin is saturated with ion, acid and acid are removed. In order to eliminate such disadvantages in the treatment operation, a method for producing deionized water by the electrodeionization method, which completely eliminates the need for chemical regeneration, has been established in recent years. It has become.

In this electrodeionization method, a deionization chamber is formed by filling an ion exchange resin between a cation exchange membrane and an anion exchange membrane, and a concentration chamber is provided on both outer sides of the deionization chamber. The chamber and the concentrator are placed between the positive and negative electrodes, and the water to be treated flows into the desalination chamber and the concentrated water flows into the concentrator while voltage is applied. In addition to removing the ion, the impurity ion is electrically suctioned and moved to a concentration chamber to produce deionized water. According to this method, the ion exchange resin is not saturated with ions, so that the drug is not saturated. Has the advantage of not requiring regeneration, but on the other hand, since a high voltage is applied, there is the problem of increased production costs in terms of power consumption, and how to reduce power consumption Is an important issue.

What is essential in solving the above problems is to make it easier for electricity to flow to the desalination and concentration chambers, that is, to increase the conductivity of the desalination and concentration chambers. 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 enrichment chamber is important from the viewpoint of improving the conductivity. It becomes a factor, and it is necessary to increase the conductivity of the enrichment chamber in order to reduce the applied voltage and solve the problems.

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

However, in order to suppress the generation of ion concentration gradients in the concentration chamber and prevent scale precipitation of hardness components such as Ca ions and Mg ions, turbulence is generated by flowing concentrated water at a certain flow rate. However, reducing the flow rate of the concentrated water as described above has a problem that turbulence cannot be generated.

The second approach is to increase the ion concentration of the concentrated water by circulating and reusing the concentrated water, thereby increasing the conductivity. This method requires a tank for temporarily storing the concentrated water and a pump for sending and circulating the concentrated water from the tank, which has the disadvantage that the equipment becomes large and the operation management becomes complicated. The third attempt is to increase the conductivity by adding chemicals such as salts and acids to the concentrated water, but new equipment must be provided to supply the chemicals, and the equipment is also large. And operation management becomes complicated. The fourth attempt is to increase the conductivity by filling the concentration chamber with ion-exchange resin, or it is difficult to fill with ion-exchange resin due to the small thickness of the concentration chamber, and the feasibility is poor. . If this were to be achieved, the thickness of the enrichment chamber would need to be increased, resulting in a problem that the equipment would become larger.

Several attempts to increase the conductivity of the enrichment chamber each have their drawbacks and have not led to a fundamental solution.

In view of the points described above, the present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, the ions moving to the concentration chamber by increasing the flow ratio and the linear velocity of the water to be treated and the concentrated water as compared with the conventional case. And increased the conductivity of the enrichment chamber. Incidentally, the flow ratio and the linear velocity of the water to be treated and the concentrated water are also factors related to the quality of the treated water, and if these values are too large, the quality of the treated water may be reduced. Therefore, the present inventors have further studied in consideration of this point, and as a result, regarding the flow ratio of the treated water and the concentrated water, the flow ratio of the treated water to the concentrated water is 6: 1 to 12: 1. Regarding the linear velocities of the water to be treated and the concentrated water, a linear velocity of 75 to 15 Om / hr is optimal for solving the above problems without reducing the quality of the treated water. It was concluded that the flow rate was a linear velocity, and the present invention was completed.

Thus, the present invention enhances the conductivity of the concentrating chamber to improve the current efficiency, thereby realizing a reduction in the applied voltage. It is intended to provide. Disclosure of the invention

In the present invention, a desalting chamber is formed by filling an ion exchanger between a cation exchange membrane and an anion exchange membrane, and concentration chambers are provided on both sides of the desalination chamber via the cation exchange membrane and the anion exchange membrane. The desalination chamber and the concentration chamber are placed between the anode and the cathode, The water to be treated flows into the deionization chamber while applying pressure, and the concentrated water flows into the concentration chamber to remove impurity ions in the water to be treated. The treated water and the concentrated water are desalted in a desalting chamber, respectively, so that the flow rate ratio of the treated water and the concentrated water is 6: 1 to 12: 1 and the linear velocity of the treated water and the concentrated water is 75 to 15 Om / hr. It is designed to flow into the concentration chamber. In order to provide the specific flow ratio and linear velocity as described above in the present invention, the thickness of the desalting chamber is preferably set to 7-1 O mm, and the thickness of the concentrating chamber is preferably set to 0.5 to 2 mm. .

According to the present invention, the water to be treated and the concentrated water flow into the desalting chamber and the concentrating chamber at a specific flow ratio and linear velocity, respectively, so that the impurity ions removed in the desalting chamber move to the enriching chamber. As a result, the conductivity of the concentration chamber is increased, and the electric resistance of the entire apparatus can be reduced. As a result, even when the same amount of deionized water is obtained, it is possible to produce deionized water having a good quality of treated water even if the applied voltage is reduced, which has the effect of reducing power consumption.

In addition, according to the present invention, since the water to be treated is supplied at a larger flow rate ratio than before, the amount of deionized water produced by the same-scale apparatus increases, and as a result, the apparatus does not need to be enlarged. There is an effect that a larger amount of processing can be performed than before. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic longitudinal sectional view showing an example of an electric deionized water producing apparatus used for carrying out the method of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

The present invention is to produce deionized water by an electric deionization method.In carrying out the present invention, desalination is performed by filling an ion exchanger between a cation exchange membrane and an anion exchange membrane. And the cation exchange membrane and the anion exchange membrane An electric deionized water production device including a concentration chamber provided on both sides of the desalting chamber and an anode and a cathode disposed on both outer sides of the chamber is used.

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

In the figure, 1 is a desalination room, 2 is a concentration room, and a plurality of these desalination rooms 1 and 2 are provided alternately. Generally, the desalination chamber 1 is manufactured as one module product. That is, a cation exchange membrane 4 and an anion exchange membrane 5 are respectively adhered to both sides of a frame 3 made of, for example, a synthetic resin formed in a four-circle frame shape, and an ion exchanger such as an ion exchange resin 6 (cation exchange The deionization module 7 is manufactured by filling resin and anion exchange resin), and the ion exchange resin filling portion in the deionization module 7 is configured as a desalination chamber 1. A plurality of the above-mentioned deion modules 7 are arranged in parallel at a distance. A spacer 8 made of a water-tight member such as a rubber packing formed in a four-circle frame is interposed between the deionization modules 7 and 7, and the space thus formed is referred to as a concentration chamber 2. Constitute. In order to prevent the ion exchange membranes 4 and 5 from adhering to each other and to secure the flow path of the concentrated water, a flow path forming material such as an ion exchange fiber or a synthetic resin net is usually provided in the internal space of the concentration chamber 2. Is satisfied.

An anode 9 and a cathode 10 were arranged on both sides of the alternately arranged body of the desalting chamber 1 and the concentration chamber 2 as described above, and although not shown, partition membranes were provided near the anode 9 and the cathode 10, respectively. The space between the partition membrane and the anode 9 is configured as an anode chamber 11, and the space between the partition membrane and the cathode 10 is configured as a cathode chamber 12.

In the figure, 13 is the treated water inflow line, 14 is the deionized water outflow line, 15 is the concentrated water inflow line, 16 is the concentrated water outflow line, 17 is the electrode water inflow line, and 18 is the electrode water Outflow line. - In producing deionized water using the apparatus configured as described above, the water to be treated flows into the desalination chamber 1 from the water inflow line 13 to be treated, and the concentrated water flows into the desalination chamber 1 from the concentrated water inflow line 15. Electrode water flows into the concentration chamber 2 and flows into the anode chamber 11 and the cathode chamber 12 through the electrode water inflow lines 17 and 17, respectively. As the concentrated water, the same water as the water to be supplied to the desalination 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 flows in a direction perpendicular to the flow direction of the water to be treated and the concentrated water.

The flow rate of the to-be-treated water in the desalination chamber 1 needs to be larger than the flow rate of the concentrated water in the concentrating chamber 2. In the present invention, the flow ratio of the to-be-treated water to the concentrated water is 6: 1 to 12: 1. , 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. The flow rate ratio of the water to be treated and the concentrated water is generally 3: 1 to 5: 1, and the flow rate of the water to be treated in the present invention is greatly increased in comparison with the conventional flow rate ratio. In the present invention, the flow ratio is set to 6: 1 to 12: 1 because the ion concentration of the concentrated water in the concentration chamber 2 can be sufficiently increased if the flow rate of the water to be treated is less than 6 times the flow rate of the concentrated water. Therefore, if the flow rate of the water to be treated exceeds 12 times the flow rate of the concentrated water, the efficiency of deionization is reduced and the quality of the deionized water is reduced. This is because there is a risk of lowering.

The present invention does not suffice if the flow rate ratio satisfies the condition of 6: 1 to 12: 1. Even if the water to be treated flows into the desalination chamber 1 within the above flow rate ratio, if the flow rate in the desalination chamber 1 is too slow, the same amount of It is necessary to increase the thickness to increase the cross-sectional area of water in the desalination chamber 1. However, if the thickness of the desalination chamber 1 is too large, it is not preferable because the current efficiency deteriorates. Therefore, in the present invention, the treatment flowing in the B salt chamber 1 The linear velocity of the water is an important factor together with the flow ratio. In the present invention, the linear velocity of the water to be treated in the desalting chamber 1 is set to 75 to 15 Om / hr, preferably 90 to 12 Om / hr.

In the present invention, the linear velocity is set to 75 to 15 OmZhr, as described above, when the linear velocity is less than 75 mZhr, when the same amount of demineralized water is to be obtained, the thickness of the desalination chamber 1 is increased. The current efficiency becomes worse,

If it exceeds 15 Om / hr, the pressure loss in the desalting chamber 1 will be too large, which is not preferable, and the time during which the water to be treated is in contact with the ion exchange resin will be short, and the deionization efficiency will be reduced. This is because there is a possibility that the quality of deionized water will be reduced. In other words, as the linear velocity of the water to be treated increases, the thickness of the desalination chamber 1 required to obtain the same amount of desalinated water decreases as the numerical value increases. A higher linear velocity is preferable, or the upper limit of the linear velocity is 15 Om / hr in order to perform treatment without lowering the quality of deionized water.

On the other hand, the linear velocity of the concentrated water in the concentration chamber 2 is also set to 75 to 15 OmZhr. Although this numerical range is the same as the linear velocity of the water to be treated, both need not necessarily have the same numerical value. A preferred range for the linear velocity of the retentate is 75-0 OmZhr.

If the linear velocity of the concentrated water is less than 75 m / hr, sufficient turbulence cannot be generated in the concentrated water flowing through the concentration chamber 2. Normally, in the concentrated water flowing through the concentration chamber, a concentration gradient of ions moving from the desalting chamber occurs, and cations such as Na ions, Ca ions, and Mg ions are distributed most in the vicinity of the anion exchange membrane 5 and C 1 ions Such anions are distributed most in the vicinity of the cation exchange membrane 4. Therefore, in the case of a hardness component such as Ca ion and Mg ion, there is a possibility that a phenomenon called scale precipitation may occur in the enrichment chamber. In order to prevent such scale deposition and obtain a uniform ion concentration, it is necessary to generate sufficient turbulence in the concentrated water. In order to achieve this, the linear velocity must be 75 m / hr or more.

When the linear velocity of the concentrated water exceeds 150 mZ hr, the pressure loss in the concentrated chamber 2 is usually large because the flow path forming material is filled in the concentrated chamber 2 as described above. Too impractical.

Thus, the water to be treated and the condensed water are supplied to the desalting chamber 1 and the condensing chamber 2 under the above conditions. The treated water flowing from the treated water inflow line 13 flows down the desalination chamber 1 in a downward flow, and when passing through the packed bed of the ion exchange resin 6, impurity ions are removed. This deionized water flows out of the deionized water outflow line 14.

On the other hand, the concentrated water flowing from the concentrated water inflow line 15 flows into the concentration chamber 2 in the upward flow and rises. The impurity ions in the water to be treated removed in the desalting chamber 1 are electrically attracted and move to the concentration chamber 2 through the cation exchange membrane 4 or the anion exchange membrane 5. That is, cations such as Na ions among the impurity ions are attracted to the cathode 10 side, move to the concentration chamber 2 through the cation exchange membrane 4, and anions such as C 1 ions are attracted to the anode 9 side, It moves to the concentration chamber 2 through the anion exchange membrane 5. The concentrated water flowing through the concentration chamber 2 receives the moving impurity ions and flows out of the concentrated water outflow line 16 as concentrated water in which the impurity ions are concentrated. Electrode water flowing into the anode chamber 11 and the cathode chamber 12 from the electrode water inflow line 17 flows out from the electrode water outflow line 18.

The present invention supplies the water to be treated and the concentrated water so that the flow ratio between the flow rate of the water to be treated in the desalting chamber and the flow rate of the concentrated water in the concentration chamber becomes 6: 1 to 12: 1. The water to be treated and the concentrated water are supplied so that the linear velocity becomes 75 to 15 O m / hr. The amount of transfer is dramatically increased, thereby increasing the ion concentration of the concentrated water in the concentration chamber. As a result, the electric resistance of the concentration chamber 2 is reduced, and the conductivity is increased. Can be

In the conventional general flow rate ratio of treated water to concentrated water of 3 _: 1 to 5: 1, the ion enrichment ratio of concentrated water is 4 to 6 if the treated water is deionized to pure water. In the case of the flow rate ratio of 6 1 to 1 2 1 in the present invention, what is the ion enrichment factor? ~ 13 times. The value obtained by multiplying the conductivity of the concentrated water when supplied to the concentration chamber by the above-mentioned ion concentration magnification is substantially the conductivity of the concentrated water near the outlet of the concentration chamber. Is the conductivity of the water the conductivity of the condensed water at the time of supply? Means ~ 13 times.

In the present invention, in order to give the specific flow rate ratio and the linear velocity as described above, the thickness of the desalting chamber 1 (refers to the distance in the direction in which the cation exchange membrane 4 and the anion exchange membrane 5 face each other): t, And the thickness of the concentration chamber 2 (meaning the distance in the direction in which the cation exchange membrane 4 and the anion exchange membrane 5 face each other): t ₂ is preferably 0.5 to ₂ mm.

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

Further, the apparatus shown in FIG. 1 employs a direction in which the flow direction of the water to be treated into the desalting chamber 1 and the direction of the inflow of the concentrated water into the concentration chamber 2 are opposite to each other, that is, a countercurrent type. The inflow directions may be opposite to each other (countercurrent type) or may be the same direction (cocurrent type). However, in the case of the countercurrent type, there are the following advantages.

That is, referring to FIG. 1 as an example, the ion concentration of the water to be treated in the desalination chamber 1 is highest near the inlet of the desalination chamber, that is, at the upper part of the desalination chamber, and decreases as it goes down. The ion concentration of the concentrated water in the concentration chamber 2 is highest near the outlet of the concentration chamber, that is, in the upper part of the concentration chamber, and decreases as it goes downward. Therefore, the tendency of the concentration distribution between the desalting chamber 1 and the concentrating chamber 2 is consistent, and the upper part of the desalting chamber 1 and the concentrating chamber 2 In both cases, the ion concentration is the highest, and if deionization is performed at the high ion concentration, the deionization efficiency is improved and the quality of the treated water is remarkably improved. As a result, even if the flow rate of the water to be treated is increased, the impurity ions can be removed more sufficiently than in the case of the co-current type. In view of this, the counter-current type is preferred in the present invention.

In the case of the co-current type, the ion concentration of the concentrated water is the lowest near the inlet of the concentrating chamber 2 (for example, in the upper part of the concentrating chamber in Fig. 1), and becomes higher near the outlet (for example, in the lower part of the condensing chamber in Fig. 1). . Therefore, in this case, the tendency of the concentration distribution in the desalting chamber 1 and the concentrating chamber 2 is exactly opposite, and the difference in ion concentration between the desalting chamber and the concentrating chamber becomes large, and the lower part of the concentrating chamber with a high ion concentration is However, there is a risk that ions may leak to the lower part of the desalting chamber having a low ion concentration. Leakage of ions must be avoided because it causes contamination of the treated water.

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

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

In other words, taking the case of downward flow as an example, an embodiment consisting of two layers, the upper part of the desalting chamber 1 being an anion exchange resin layer and the lower part being a cation exchange resin layer, and the upper part being an anion exchange resin layer, The lower part is a cation exchange resin layer, and in this order 1]

There is an embodiment composed of three or more layers in which two or more laminated portions are repeatedly provided.

It is also possible to provide a mixed ion exchange resin layer of a cation exchange resin and an anion exchange resin, and in this case, the upper part of the desalting chamber 1 is an anion exchange resin layer, and the lower part is a cation exchange resin layer. One or more sets of this laminated part are provided repeatedly, and a mixed ion-exchange resin layer is further provided at the lower part. An embodiment composed of three or more layers, the upper part is an anion-exchange resin calendar, and the lower part is a mixed layer. There is an embodiment in which the on-exchange resin layer is composed of two layers.

Generally, weak acid components contained as impurities in the water to be treated have a low degree of dissociation and are difficult to remove. For example, carbonate ions have a low degree of dissociation of carbon dioxide in water, contain a lot of free carbonic acid, and silicate ions have a very low degree of dissociation of silica, and the removal rate of both is quite low at present.

If the water to be treated first passes through the anion exchange resin layer in the desalting chamber, the removal rate of such a weak acid component can be improved. This is because when the water to be treated first comes into contact with the anion exchange resin, only the anion among the impurity ions is mainly deionized, and only the anion moves to the concentration chamber.

However, cations remain in the corresponding portion of the desalting chamber, and an amount of alcohol corresponding to the cations is temporarily generated. As a result, the water to be treated is temporarily alkaline.

However, it is considered that the degree of dissociation of the weak acid component is improved, the amount of the weak acid ions transferred to the concentration chamber is large, and the removal rate can be improved.

In the present invention, the water to be treated is caused to flow at a high flow ratio to increase the amount of impurity ions transferred to the enrichment chamber, so that the water to be treated is supplied first so as to pass through the anion exchange resin layer. Synergistically, the amount of ions transferred as impurity ions increases, thereby increasing the alkalinity of the water to be treated, and has the advantage that the efficiency of removing weak acid components can be improved as compared with the conventional method.

In order to improve the removal rate of the weak acid component, the water to be treated must Most preferably, the mixture passes through the on-exchange resin layer, and then passes through the ion-exchange resin layer, which is a mixture of the cation exchange resin and the anion exchange resin. According to such a method, the removal rate of the weak acid component is further improved. Can be.

The reason is that the mixed ion-exchange resin layer has a higher electric resistance than the anion-exchange resin layer, so that more current flows through the anion-exchange resin layer, and the ion ions are removed as impurity ions and the anion is removed. It seems that this is based on the fact that the transfer to the enrichment room proceeds efficiently.

In filling the ion exchange resin 6 into the space between the frame 3 and the ion-exchange membranes 4 and 5, the present invention provides a dividing bar in the frame 3 to provide a plurality of desalination chambers 1. It can also be split.

In the present invention, it is preferable to use an MR type or MP type (macroporous type) ion exchange resin having a giant network structure as the ion exchange resin. The resin is excellent in physical strength and has an advantage that bead crushing can be prevented. By the way, conventionally, there was a problem that the flow path in the desalting chamber was blocked by the crushing of the heat.

That is, the frame 3 constituting the desalting chamber is provided with a deionized water outlet, and when a dividing bar is provided to divide the desalting chamber into two upper and lower rooms, for example, There is a passage for treated water, and a sarannet is usually attached to these outlets and passages to prevent resin particles of the ion exchange resin from passing through. However, when bead crushing occurred, the crushed pieces did not pass through the sarannet and clogged there, causing a problem of blocking the flow path in the B 兑 salt room.

The present invention can address this problem by using an ion-exchange resin having a huge network structure such as the MR-type ion-exchange resin described above, but the present invention further provides the above-mentioned treated water passage in a desalination chamber. Comb with a slit gap that allows ion-exchange resin particles not to pass but crushed beads to pass through the deionized water outlet It is preferable to configure as a screen.

With this configuration, even if beads are crushed in the MR-type ion exchange resin, etc., the crushed pieces pass through the slit of the screen, so that the flow path can be prevented from being blocked, and the flow rate in the desalting chamber can be reduced. There is an advantage that the distribution can be made uniform. In this case, it is preferable that a porous filter having a pore diameter of 100 m or less be exchangeably attached to an appropriate position of the deionized water outflow line 14 so as to collect broken beads. Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

Industrial water having the quality shown in Table 1 was treated with a reverse osmosis membrane device to obtain permeated water having the quality shown in the table. This permeated water was used as the water to be treated and the concentrated water, and supplied to an electric deionized water production apparatus as shown in FIG. In this case, as the device, a device configured by arranging two deionization modules in parallel (Example) and a device configured by arranging four deion modules of the same size (Comparative Example 1) And Comparative Example 2) were used. The water to be treated and the concentrated water were passed through the desalting and concentrating chambers of these devices, respectively, to produce deionized water. However, unlike Fig. 1, both the water to be treated and the concentrated water flowed in a downward flow (that is, in parallel flow). At this time, the conditions of the flow 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 obtained deionized water are as shown in Table 2. Incidentally, those thickness t of deionized module desalting compartment used, but 8 mm, thickness t ₂ of the concentrating compartment is 0. 8 mm, also in the desalting compartment of a mixture of cation exchange resin and Anion exchange resin Was filled with a height of 600 mm throughout the desalting chamber.

The applied voltage and DC current values are as shown in Table 3. The applied voltage is an applied voltage necessary for obtaining deionized water having good water quality, having a deionized water resistivity of 10ΜΩ · cm or more. The conductivity of the concentrated water at the concentrated water outlet was measured, and the presence or absence of scale formation of the hardness component after continuous operation for 1000 hours was observed. Conclusion The results are shown in Table 3.

As is clear from the above results, the present invention is a comparative example, which is a conventional example, and has a device scale of 1/2 of that of Comparative Example 2, and is lower than Comparative Example 1 and Comparative Example 2; Deionized water having substantially the same amount and the same water quality as Comparative Example 2 can be obtained. Moreover, it can be seen that the scale formation of the hardness component does not occur despite the high conductivity of the concentrated water (that is, the high ion concentration of the concentrated water). Industrial applicability

INDUSTRIAL APPLICABILITY The present invention is useful as a deionized water production method for efficiently producing deionized water used in various industries such as the semiconductor manufacturing industry, the pharmaceutical industry, the food industry, and the like, research facilities, and the like by an electrodeionization method. .

Table 1 Permeability of industrial water (/ S / CEπ) 2785.0

PH 6. 7 5. 3 best thione _{(mg CaC0 3 / L) 1} 1 4 1. 2 hardness components _{(mg CaC0 3 ZL) 74 0.} 2 total Anion _{(mg C a C0 3 / L} ) 1 26 1. 5

Table 2

Table 3

Scale of hardness component is formed on anion exchange membrane 麵 in concentration chamber

Claims

The scope of the claims

1. A desalting chamber is formed by filling an ion exchanger between the cation exchange membrane and the anion exchange membrane, and concentration chambers are provided on both sides of the desalination chamber via the cation exchange membrane and the anion exchange membrane. The desalination chamber and the concentrating chamber are placed between the anode and the cathode, and while the voltage is being applied, the water to be treated flows into the desalting chamber, and the concentrated water flows into the concentrating chamber and the impurity ions in the water to be treated are contaminated. The method for producing deionized water by the electric deionization method for producing deionized water, wherein 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 Deionization by the electric deionization method, characterized in that the water to be treated and the condensed water flow into the deionization chamber and the concentration chamber, respectively, so that the linear velocity becomes 75 to 150 m / hr. Water production method.

2. The method for producing deionized water by an electric deionization method according to claim 1, wherein the flow ratio of the water to be treated and the concentrated water is 8: 1 to 10: 1.

3. The linear velocity of the water to be treated is 90 ~! 2. The method for producing deionized water by the electrodeionization method according to claim 1, wherein the deionized water is 20 m / hr.

4.fl The thickness of the salt chamber is set to 7 to 10 mm, and the thickness of the concentrating chamber is set to 0.5 to 2 mm, so that the water to be treated and the concentrated water flow at a predetermined flow rate and a predetermined linear velocity. The method for producing deionized water by the electrodeionization method according to claim 1.

5. The water to be treated and the concentrated water are supplied to the desalination chamber and the concentration chamber, respectively, so that the inflow direction of the water to be treated into the desalination chamber and the inflow direction of the concentrated water into the concentration chamber are opposite to each other. A method for producing a deionized water by the electric deionization method according to claim 1 wherein the water is introduced.

6. The method for producing deionized water by the electrodeionization method according to claim 1, wherein the water to be treated that has flowed into the deionization chamber first passes through the anion exchanger layer.

7. The treated water flowing into the B salt chamber first passes through the anion exchanger layer, 7. The method for producing deionized water by an electric deionization method according to claim 6, wherein the mixture is made to pass through a mixed ion exchanger layer of a carbon ion exchanger and an anion exchanger.