JP2001252672A - Operation method for electric deionized water production device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an operation method for an electric power-saving electric deionized water production device capable of easily removing a scale. SOLUTION: In this deionized water production device, an ion exchanger is packed at two small desalting chambers d1 and d2 divided by one side cation exchange membrane 3, the other side anion exchange membrane 4 and an intermediate ion exchange membrane 5 placed between both ion exchange membranes, and an anion exchanger is packed in the desalting chamber d1 as the ion exchanger packed to constitute a desalting chamber D1. The concentration chambers 1 are provided at the both sides of the desalting chamber D1 through the cation exchange membrane 3 and anion exchange membrane 4. The desalting chamber D1 and the concentration chamber 1 are arranged between an anode 7 and a cathode 6, and the water to be treated is made to flow into the desalting chamber d2 while applying voltage. Then, the effluent of the desalting chamber d2 is made to flow into the desalting chambers d1 and also concentrated water is made to flow into the concentration chamber 1 to remove an impurity ion in the water to be treated and to form the deionized water and a stage for washing the concentration chamber in which the effluent of the desalting chamber d2 is disparaged to the outside of the system without flowing into the desalting chambers d1 and also the concentrated water is made to flow into the concentration chamber 1 to remove an impurity anion in the water and to lower the pH of the concentrated water are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the field of semiconductor manufacturing,
Used in various industries or research laboratories, such as the pharmaceutical and pharmaceutical manufacturing fields, the power generation field such as nuclear power and thermal power, the food industry, etc., it is possible to reduce the electric resistance and save the scale in the concentration chamber by a simple method. The present invention relates to a method for operating a power-type electric deionized water producing apparatus.

[0002]

2. Description of the Related Art As a method for producing deionized water, there has been conventionally known a method in which deionized water is passed through ion-exchange resin through water to be treated. In order to eliminate such disadvantages in the treatment operation, it is necessary to regenerate with a chemical, and in recent years, a method for producing deionized water by an electric deionization method that does not require regeneration with a chemical has been established and put into practical use. Has been reached.

FIG. 2 is a schematic cross-sectional view of a typical conventional electric deionized water producing apparatus. As shown in FIG. 2, the cation exchange membranes 101 and the anion exchange membranes 102 are alternately arranged at a distance from each other, and every other ion exchanger 103 is placed in a space formed by the cation exchange membranes 101 and the anion exchange membranes 102. Fill to form a desalination chamber. The anion exchange resin 103a is filled on the inflow side (front stage) of the water to be treated in the desalination chamber,
A mixed ion exchange resin 103b of a cation exchange resin and an anion exchange resin is filled on the outflow side (the latter stage) of the water to be treated in the desalination chamber. In addition, the portions not adjacent to the ion-exchanger 103 formed by the anion exchange membrane 102 and the cation exchange membrane 101 located next to the desalination chamber 104 are used as the concentration chamber 105 for flowing the concentrated water.

Further, a cation exchange membrane 101, an anion exchange membrane 102, and an ion exchanger 103 filled therein.
To form a deionization module. That is, a cation exchange membrane is sealed on one side of the frame whose inside is omitted in the figure, and an anion exchange resin is placed on the upper part (front part) of the cut part of the frame, and the lower part (second part). Is filled with the mixed ion exchange resin, and then the other part of the frame is sealed with an anion exchange membrane. The ion-exchange membrane is relatively soft, and when the inside of the frame is filled with the ion-exchanger and both surfaces are sealed with the ion-exchange membrane, the ion-exchange membrane curves and the packed layer of the ion-exchanger becomes Generally, a plurality of ribs are provided vertically in the space of the frame body to prevent unevenness. In addition, an inlet for treated water is provided above the frame, and an outlet for treated water is provided below the frame.

FIG. 2 shows a state in which a plurality of such deionization modules are juxtaposed with a spacer interposed therebetween, and a cathode 109 is arranged on one side of the juxtaposed deionization modules. At the same time, the anode 110 is provided at the other end. The position sandwiching the spacer is the concentration chamber 105, and the cation exchange membrane 101 and the anion exchange membrane 10
2, or a partition membrane such as a mere diaphragm having no ion exchange property is provided, and both electrodes 109 and 11 separated by the partition membrane.
0 are in contact with the cathode chamber 112 and the anode chamber 1 respectively.
It is assumed to be 13. As described above, in the conventional electric deionized water producing apparatus, the number of the concentration chambers is one larger than the number of the desalination chambers, or the concentration chambers at both ends are separated from the electrode chambers without a partition membrane. In this case, the shape was one less.

A case of producing deionized water by such an electric deionized water producing apparatus will be described with reference to FIG. That is, a direct current is passed between the cathode 109 and the anode 110, the water to be treated flows in from the water inflow line 111, the concentrated water flows in from the concentrated water inflow line 115, and the electrode water inflow lines 117, 117 From each of the electrode water flows. The water to be treated flowing from the treated water inflow line 111 flows down the desalting chamber 104, and firstly, when passing through the anion exchange resin 103a at the preceding stage, anion components such as hydrochloric acid ions and sulfate ions are removed. Upon passing through the mixed ion exchange resin 103b of the latter cation exchange resin and anion exchange resin, cation components such as magnesium and calcium are removed. The concentrated water flowing from the concentrated water inflow line 115 rises in each concentration chamber 105, receives impurity ions moving through the cation exchange membrane 101 and the anion exchange membrane 102, and forms concentrated water as concentrated water in which the impurity ions are concentrated. Electrode water flowing out of the outflow line 116 and further flowing in through the electrode water inflow lines 117 and 117 flows out of the electrode water outflow lines 118 and 118. Therefore, deionized water is obtained from the deionized water outflow line 114.

On the other hand, various attempts have been made to reduce the electric resistance of the electric deionized water producing apparatus in order to use such an electric deionized water producing apparatus to remove impurity ions in the water to be treated with low power consumption. Has been made. In this case, in the desalting chamber, since the method of filling the ion exchanger used in the desalting chamber and the filling amount are determined by the quality of the treated water required, it is necessary to reduce the electric resistance of the desalting chamber. There is a limit.
Therefore, measures are often taken to reduce the electrical resistance of the concentrating chamber. For example, Japanese Patent Application Laid-Open No. 9-24374 discloses a method of reducing the electric resistance in a concentration chamber by adding and supplying an electrolyte to the concentration chamber. In addition, many methods have been reported for promoting the increase in conductivity by circulating concentrated water and reducing the electric resistance of the concentrating chamber.

[0008]

However, the method of reducing the electric resistance of the concentrating chamber by adding and supplying the electrolyte to the concentrating chamber involves a pump for supplying the electrolyte to the concentrating chamber, a chemical storage tank, a supply pipe and the like. It must be installed, which leads to an increase in installation area and installation cost. In addition, it is necessary to periodically supply and manage medicines, which requires human resources despite being a continuous regeneration type device. There is a problem. In addition, the method of promoting the increase in electrical conductivity by circulating the concentrated water and reducing the electric resistance of the concentrated chamber is based on the fact that the hardness components such as calcium and magnesium contained in the concentrated water are also thickened and the generation of scale is promoted. There is a problem that the electrical resistance is increased. Therefore, the power-saving operation of reducing the electric resistance of the electric deionized water producing apparatus can be performed, and the scale generation in the enrichment chamber is suppressed,
There has been a demand for an operation method capable of removing scale by a simple method in a short period of time without using a chemical even if scale generation occurs even in long-term operation.

Therefore, an object of the present invention is to reduce the electric resistance by drastically improving the structure of the electric deionized water producing apparatus without adding a chemical to the concentrated water,
A method for operating a power-saving electric deionized water producing apparatus that can suppress scale generation in a concentration chamber and can remove scale by a simple method even if scale generation occurs even if operation occurs for a long time. Is to provide.

[0010]

Under such circumstances, the present inventors have conducted intensive studies and as a result, have found that a cation exchange membrane is sealed on one side of the frame and an anion exchange membrane is sealed on the other side. In the conventional desalting chamber structure, an intermediate ion exchange membrane that divides the desalting chamber into two parts is further provided between the cation exchange membrane and the anion exchange membrane, and two small desalting chambers are provided adjacent to each other. The small desalination chamber divided by the anion exchange membrane and the intermediate ion exchange membrane is a desalination chamber filled with an anion exchanger, and the cation exchange membrane and the concentration chamber are provided on both sides of the desalination chamber via the anion exchange membrane. The desalting chamber and the concentrating chamber are arranged between the anode and the cathode, and the water to be treated is caused to flow into one of the small desalting chambers filled with the anion exchanger while applying a voltage. Effluent from the other small desalination chamber
A deionized water producing step of flowing the concentrated water into the concentration chamber to remove impurity ions in the water to be treated and obtaining deionized water; and the effluent of the one small desalination chamber to the other small desalination chamber. Without draining out the system, and discharging the concentrated water into the concentrated chamber to remove impurity anions in the water to be treated and reduce the pH of the concentrated water. In the deionized water production process, the number of concentrating chambers per one deionization chamber filled with the ion exchanger can be reduced to about half of the conventional one, and the electric resistance of the electric deionized water production apparatus is remarkably increased. The power saving type operation that can be reduced can be performed, and in the concentration chamber washing step, simply changing the flow path of stopping supplying the effluent of the one small desalination chamber to the other small desalination chamber, Only anions move to the concentration chamber, and p in the concentration chamber A lower acidified, it found such that the scale generated in the anion exchange membrane choice concentrating compartment can be hardly dissolved, thereby completing the present invention.

That is, the invention (1) according to claim 1 is defined by a cation exchange membrane on one side, an anion exchange membrane on the other side, and an intermediate ion exchange membrane located between the cation exchange membrane and the anion exchange membrane. The two small desalination chambers are filled with an ion exchanger, and the ion exchanger filled in one of the small desalination chambers constitutes a desalination chamber as an anion exchanger. Enrichment chambers are provided on both sides of the desalination chamber, and these desalination chambers and the enrichment chamber are arranged between the anode and the cathode, and a voltage is applied to the small desalination chamber filled with one anion exchanger. The water to be treated flows in, and then the effluent from the small desalination chamber flows into the other small desalination chamber, and the concentrated water flows into the concentration chamber to remove impurity ions in the water to be treated. A deionized water production process for producing water, and the water to be treated flows in The effluent of one small desalination chamber is discharged out of the system without flowing into the other small desalination chamber, and the concentrated water flows into the concentration chamber to remove impurity anions in the water to be treated. A method for operating an electric deionized water producing apparatus, comprising: a concentration chamber washing step of lowering the pH of concentrated water. By adopting such a configuration, in the deionized water production process, the number of the enrichment chambers per one deionization chamber filled with the ion exchanger can be reduced to about half of the conventional one, and the electric deionized water production can be performed. The electrical resistance of the device can be significantly reduced. In addition, since the number of concentrating chambers is relatively small as compared with the conventional apparatus, the ion concentration of the concentrated water flowing through the concentrating chamber can be increased,
The conductivity is improved, the electric resistance is further reduced, and the flow rate of the concentrated water flowing in the concentration chamber can be increased, so that the scale in the concentration chamber is less likely to be generated. In addition, when scale is generated in the concentration chamber due to long-term operation, the process is switched to the concentration chamber cleaning step, that is, only the flow path of the effluent of the small desalination chamber into which the water to be treated first flows in is changed. The pH in the concentration chamber is acidic, and the scale generated in the concentration chamber such as on the anion exchange membrane can be almost dissolved.

According to a second aspect of the present invention, the deionized water producing step is performed, and then the concentrating chamber cleaning step is performed, or the deionized water producing step is performed, and then the operation is stopped and then the operation is stopped. It is intended to provide an operation method of the electric deionized water producing apparatus according to (1), wherein the concentration chamber cleaning step is performed at the time of restart. By adopting such a configuration, in addition to achieving the same effects as those of the invention described above, during normal operation or after the end of the normal operation, that is, immediately after the operation is stopped, even after the operation is restarted after a stop period for a while after the operation is stopped. In any of the above, the concentration chamber can be easily acid-washed without using a chemical.

According to a third aspect of the present invention, in the third aspect, the ion exchanger packed in the other small desalting chamber partitioned by the cation exchange membrane on one side and the intermediate ion exchange membrane comprises a cation exchanger and an anion. It is intended to provide an operation method of the electric deionized water producing apparatus according to the above (1) or (2), which is a mixture of exchangers. By adopting such a configuration, in the deionized water production step, it is possible to sufficiently treat the water to be treated containing a large amount of anionic components, particularly the water to be treated containing a large amount of weakly acidic components such as silica and carbonic acid. Also,
When the flows of the water to be treated and the concentrated water flowing through the small desalting chamber filled with the mixture of the cation exchanger and the anion exchanger are opposite,
Concentrated water in which cation components such as magnesium and calcium ions are concentrated is immediately discharged from the concentration chamber to prevent generation of scale in the concentration chamber.

According to a fourth aspect of the present invention, the intermediate ion exchange membrane is a single membrane of a cation exchange membrane or an anion exchange membrane, or a double membrane having both an anion exchange membrane and a cation exchange membrane. (1)-characterized by the above
(3) An operation method of the electric deionized water producing apparatus according to (3). By adopting such a configuration, in addition to achieving the same effects as the above-described invention, in the deionized water production step, when a single membrane is used, the ion to be removed from the water to be treated is a cation or an anion, depending on whether the ion is an anion. Exchange membrane can be selected. Further, the double membrane has a cation exchange membrane or an anion exchange membrane disposed at the top or bottom of the apparatus. In this case, for example, a cation membrane or a cation membrane is disposed on the first small desalination chamber treated water side (inlet side). When the anion exchange membrane is disposed on the treated water side (outlet side) of the first small-size desalination chamber, the cation component is moved from the second small-size desalination chamber, and the pH of the first small-size desalination chamber is easily shifted to the alkali side. In other words, the ionization of the nonionic silica proceeds, and the effect is obtained that the silica is further reduced through the anion exchange membrane disposed on the treated water side (outlet side) of the first small demineralization chamber.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Electrodeionization used in the present invention
The water production apparatus will be described with reference to FIG. FIG. 1 shows the present embodiment.
FIG. 1 is a schematic view of an electric deionized water producing apparatus in a form.
You. As shown in FIG. 1, cation exchange membrane 3, intermediate ion
Exchange membranes 5 and anion exchange membranes 4 are alternately arranged at a distance.
Formed by the cation exchange membrane 3 and the intermediate ion exchange membrane 5
The first small desalination chamber is filled with an ion exchanger 8
d₁, D_Three, D_Five, D₇To form an intermediate ion exchange membrane 5
Anion exchange in the space formed by the
The second small desalting chamber d_Two, D_Four, D₆, D₈
And the first small desalination chamber d₁And the second small desalination chamber d_TwoDesalination with
Room D₁, 1st desalination room d_ThreeAnd the second small desalination chamber d_FourIn desalination room
D _Two, 1st desalination room d_FiveAnd the second small desalination chamber d₆Desalination room D
_Three, 1st desalination room d₇And the second small desalination chamber d₈Desalination room D_Four
And In addition, desalination room D_Two, D_ThreeLocated next to each
Formed by the anion exchange membrane 4 and the cation exchange membrane 3
The portion not filled with the on-exchanger 8 is for flowing concentrated water
Of the concentration chamber 1. These are sequentially installed, and from the left in the figure
Desalination room D₁, Concentration room 1, desalination room D_Two, Concentration room 1, desalination room
D_Three, Concentration room 1, desalination room D_FourTo form Also, interlayer film
In the two small desalination chambers adjacent to each other through the second small desalination chamber
Of the treated water in the first desalination chamber
The connection 13 is connected to the housing 13 by a connection pipe 19a. Ma
The connecting pipe 19a has a valve 191 in the middle of the pipe,
A branch arrangement including a valve 192 is provided upstream of the valve 191.
It has a tube 19b.

Operation of the electric deionized water producing apparatus of the present invention
When performing the deionized water production step in the method, the following
Is operated as follows. In this case, the valve 191 is opened and the valve
Block 192 is closed. That is, a direct voltage is applied between the cathode 6 and the anode 7.
Through the flowing current and from the treated water inflow line 11
As the water flows in, the concentrated water
Flows from the electrode water inflow lines 17, 17, respectively.
The electrode water flows. Inflow from treated water inflow line 11
Water to be treated is supplied to the second small desalination chamber d._Two, D_Four, D₆, D₈To
When flowing down and passing through the packed bed of the anion exchanger 81,
Pure ions are removed. Furthermore, treated water in the second small desalination chamber
The effluent passing through the outflow line 12 is treated in the first small desalination chamber.
The first small desalination chamber d through the water inlet line 13₁, D_Three,
d_Five, D ₇Again, the ion exchanger 8, for example,
Through a packed bed of a mixture of anion exchanger and cation exchanger
Impurity ions are removed when passing through, and deionized water is removed.
Obtained from the on-water outflow line 14. Also, concentrated water inflow
Concentrated water flowing in from line 15 rises in each concentrating chamber 1,
Moving through the cation exchange membrane 3 and the anion exchange membrane 4
Incoming impurity ions and concentrated the impurity ions
It is discharged from the concentrated water outflow line 16 as concentrated water,
The electrode water flowing from the electrode water inflow lines 17
It is discharged from the polar water discharge lines 18, 18. The above operations
Impurity ions in the water to be treated are electrically removed.
It is.

In the present embodiment, the intermediate ion exchange membrane may be any of a single cation exchange membrane or an anion exchange membrane, or a composite membrane having both an anion exchange membrane and a cation exchange membrane. Is also good. In the case of a double membrane having an anion exchange membrane or a cation exchange membrane at the top or bottom of the apparatus, the height (area) of each of the anion exchange membrane and the cation membrane is appropriately determined according to the quality of the water to be treated or the purpose of treatment. . When a single membrane is used, the ion exchange membrane is determined according to the ion species to be removed from the water to be treated.

The thickness of the first small desalting chamber is not particularly limited, and the optimum thickness may be determined according to the type of ion exchanger packed in the first small desalting chamber and the filling method. Further, since the second small desalting chamber is an anion exchanger, the optimum thickness is determined from the beginning. Therefore, the thickness of the first small desalination chamber may be set to 3 mm and the thickness of the second small desalination chamber may be set to 6 mm, and the overall thickness, that is, the thickness of the desalination chamber may be set to 9 mm. Thus, a plurality of desalination chambers and concentration chambers are alternately arranged, and the thickness of the desalination chamber divided by the cation exchange membrane and the anion exchange membrane arranged on both sides of the desalination chamber is larger than that of the conventional one. Thick, 1.5-18mm
, Preferably 6.5 to 15 mm, more preferably 9 to 15 mm.
It is appropriately determined within a range of 13 mm.

The ion exchanger packed in the first small desalting chamber partitioned by the cation exchange membrane on one side and the intermediate ion exchange membrane is not particularly limited, and the above-mentioned anion exchanger and cation In addition to a mixed bed of exchangers, a single bed of an anion exchanger, a single bed of a cation exchanger, a mixed bed of an anion exchanger and a cation exchanger, and a double layer obtained by combining these can also be used. Further, the ion exchanger may be any substance having an ion exchange function such as an ion exchange resin or an ion exchange fiber, or may be a combination thereof.

The flow directions of the water to be treated in the first and second small desalination chambers are not particularly limited. The flow direction in the small desalination chamber may be different. Also, the flow direction of the concentrated water is appropriately determined.

Next, in the method for operating the electric deionized water producing apparatus according to the present invention, when the washing step of the concentrating chamber is performed, the following operation is performed. In this case, in the operation of the above deionized water production process, the valve 191 is closed and the valve 1 is closed.
It is only necessary to open 92. That is, the cathode 6 and the anode 7
In the meantime, a direct current flows, and the water to be treated flows in from the treated water inflow line 11, the concentrated water flows in from the concentrated water inflow line 15, and the electrode water flows in from the electrode water inflow lines 17, 17, respectively. The treated water flowing from the treated water inflow line 11 is supplied to the second small desalination chambers d ₂ , d ₄ , d ₆ ,
flows down d _8, impurity anions are removed when passing through the packed bed of an anion exchanger 81. The effluent that has passed through the treated water outflow line 12 of the second small desalination chamber is discharged out of the system through a pipe 19a and a branch pipe 19b. Further, the concentrated water flowing from the concentrated water inflow line 15 rises in each of the concentration chambers 1, and there is no cation moving from the cation exchange membrane 3, and only the anions moving through the anion exchange membrane 4 are received. It is. Accordingly, the pH in the concentration chamber is acidic, and scale generated on the side of the concentration chamber on the anion exchange membrane can be almost dissolved.

In the above embodiment, in the case of the deionized water production step, the water to be treated flowing from the treated water inflow line 11 flows down the second small desalination chambers d ₂ , d ₄ , d ₆ and d ₈ . Then, when passing through the anion exchange resin, anion components such as hydrochloric acid ions and sulfate ions are moved to and removed from the concentration chamber through the anion exchange membrane, particularly near the inlet side of the water to be treated. In this case, the cation component in the water to be treated remains contained in the water to be treated. The effluent flowing through the treated water outflow line 12 of the second small desalination chamber passes through the treated water inflow line 13 of the first small desalination chamber, and the first small desalination chamber d ₁ ,
When flowing down d ₃ , d ₅ , and d ₇ and passing through a mixed bed of cation and anion exchange resin, magnesium and calcium ions are particularly present near the inlet of the first small desalting chamber (the inlet of the second small desalting chamber). Such cation components move to the concentration chamber side via the cation membrane and are removed. Therefore, deionized water is obtained from the deionized water outflow line 14.

In the washing step of the concentrating chamber, the water to be treated flowing from the treated water inflow line 11 is supplied to the second small desalting chamber d ₂ ,
When flowing down d ₄ , d ₆ , and d ₈ and passing through the anion exchange resin, anion components such as hydrochloric acid ions and sulfate ions, particularly near the inlet side of the water to be treated, pass through the anion exchange membrane to the concentration chamber side. Move and be removed. Then, the water to be treated containing the cation component is discharged to the outside of the system, and nothing flows in the first small desalination chamber. Absent. Therefore, the pH of the concentrated water is about 6.5 in the deionized water production process,
It can be reduced to H5 or less, especially to 4 or less, and can dissolve scale and the like. Where the scale occurs is usually
On the surface of the anion exchange membrane on the side of the concentration chamber, where the anion components such as hydrochloric acid ions and sulfate ions flow, and are exposed to water having a pH lower than the pH value measured in the effluent of the concentration chamber. It is. For this reason, it is very convenient to dissolve the scale.

In the operation method of the electric deionized water producing apparatus of the present invention, the deionized water producing step is a normal operation, and the concentrating chamber washing step is performed in the concentrating chamber as a result of, for example, a long-term normal operation. Since these are steps for removing the scales, these are firstly performed in a deionized water production step, and then performed in a concentration chamber cleaning step, or in the deionized water production step, and then stopped, The concentration chamber cleaning step is performed when the operation is resumed. The method for determining the timing of performing the concentration chamber cleaning step is not particularly limited, and includes, for example, a method of measuring a differential pressure of the concentration chamber and determining from a rise in differential pressure, a method of empirically determining from the quality of treated water, There is a method of judging from an increase in the electric resistance of the device. It is usually sufficient to perform the concentration chamber washing step for several minutes to several tens of minutes. In addition, as a method of determining the time when the concentration chamber cleaning step is stopped, a method of determining based on a differential pressure between an inlet and an outlet in the concentration chamber is used. In this case, it is preferable to stop the washing after the pressure difference in the enrichment chamber has substantially decreased to a value close to the value at the start of operation of the electric deionized water producing apparatus. In addition, pure water may be passed through, for example, pure water to a small desalination chamber partitioned by a cation exchange membrane and an intermediate membrane that does not pass water in the concentration chamber washing step, and the same effect as described above is obtained. There is also an effect that the temperature rise of the ion exchange membrane and the ion exchanger packed in the small desalination chamber can be suppressed, and thermal damage can be avoided.

In the present invention, the water to be treated is not particularly limited, and water containing anions containing hydrochloric acid ions and sulfate ions can be used. Specifically, well water, tap water, sewage, industrial water, and river water can be used. Water, permeated water subjected to reverse osmosis membrane treatment, in which washing water for cleaning semiconductor devices of a semiconductor manufacturing plant or recovered water from a concentration chamber is used alone or in combination to form a mixed state. In the method for operating the electric deionized water production apparatus of the present invention, the water to be treated used in the deionized water production step and the water to be treated used in the cleaning step of the concentrating chamber may be of the same supply source or different supply sources. However, it is preferable to use the same supply source, since it is not particularly necessary to provide a separate pipe or the like.

In this embodiment, an apparatus is used in which the number of concentrating chambers per desalting chamber (small desalting chamber) filled with an ion exchanger is reduced to about half that of the conventional apparatus, so that the electric resistance is significantly reduced. Power saving operation that can be reduced. In addition, since the number of the concentrating chambers is relatively small as compared with the conventional apparatus, the ion concentration of the concentrated water flowing through the concentrating chamber can be increased, the conductivity is improved, and the electric resistance is further reduced. At the same time, the flow rate of the concentrated water flowing in the concentration chamber can be increased, and scale in the concentration chamber is less likely to occur. Further, even if scale is generated in the enrichment chamber in a long-term operation, only the supply of the effluent flowing out of the small desalination chamber to the other small desalination chamber first is stopped. The concentration chamber can be so-called acid-washed only by a simple operation of changing the flow path, so that it is not necessary to add a new chemical.

[0027]

Next, the present invention will be described in more detail with reference to examples, but this is merely an example and does not limit the present invention. Example 1 Under the following apparatus specifications and operating conditions, water was passed through the desalination chamber and the concentration chamber of the electric deionized water producing apparatus having the configuration shown in FIG. 1, and the valve 191 was opened and the valve 192 was closed, and water was passed. Operation (deionized water production process) was performed. For the water flow operation, the initial differential pressure of the enrichment chamber is 0.05 MPa gauge pressure (0.5 kg
・ G / cm ² ) is 0.12MPa gauge pressure (1.2kg ・ G / cm ² )
When the pressure difference exceeding the limit was detected, the process was terminated. It was driving for about half a year. Next, the apparatus was disassembled and the presence or absence of scale in the concentration chamber was observed. As a result, adhesion of scale was observed on the membrane surface of the anion membrane on the side of the concentration chamber. Next, the operation was switched to the concentration chamber cleaning step. The concentration chamber cleaning step is performed by the valve 191 shown in FIG.
There was no change in the operating conditions except for the operations of closing and opening 192. The concentration chamber cleaning was terminated because the pressure difference in the concentration chamber became 0.07 MPa gauge pressure (0.7 kg · G / cm ² ) close to the initial pressure difference. The washing time was 15 minutes. Also, when measuring the pH of the concentrated water for a washing time of 10 minutes,
pH was 4. Next, as a result of disassembling the apparatus and observing the presence or absence of scale in the concentration chamber, no adhesion of scale was found on the membrane surface of the anion membrane on the side of the concentration chamber.

Water to be treated and concentrated water: Experimental water in which a hardness component was added to permeated water obtained by treating industrial water with a reverse osmosis membrane device to adjust the hardness to 0.2 mg CaCO ₃ / L. Deionization chamber; width 300 mm, height 600 mm, thickness 3 mm ・ First small desalination chamber filled ion exchange resin; mixed ion exchange resin of anion exchange resin (A) and cation exchange resin (K) (mixing ratio is volume A: K = 1: 1) ・ Second small desalination chamber; width 300 mm, height 600 mm, thickness 8 mm ・ Second small desalination chamber filled ion exchange resin; anion exchange resin ・ Flow rate of the entire apparatus: 1 m ³ / h.

[0029]

According to the first aspect of the present invention, in the deionized water production step, the deionization chamber 1 filled with the ion exchanger is used.
The number of concentrating chambers per unit can be reduced to about half of the conventional one, and the electric resistance of the electric deionized water producing apparatus can be significantly reduced. In addition, since the number of the concentrating chambers is relatively small as compared with the conventional apparatus, the ion concentration of the concentrated water flowing through the concentrating chamber can be increased, the conductivity is improved, and the electric resistance is further reduced. At the same time, the flow rate of the concentrated water flowing in the concentration chamber can be increased, and scale in the concentration chamber is less likely to occur. Further, when scale is generated in the concentration chamber due to long-term operation, the mode is switched to the concentration chamber cleaning step, that is, the effluent of the small desalination chamber into which the water to be treated first flows is transferred to the other small desalination chamber. The concentration chamber can be so-called acid-washed only by stopping the supply, that is, by a simple operation of changing the flow path of the effluent, so that it is not necessary to add a new chemical.

According to the second aspect of the present invention, in addition to having the same effects as the above-described invention, even during the normal operation or after the end of the normal operation, that is, immediately after the stop of the operation, there is a stop period for a while after the stop of the operation. At any time after the subsequent restart of operation, the concentration chamber can be easily acid-washed without using a chemical.

According to the third aspect of the present invention, in the process of producing deionized water, the water to be treated containing a large amount of anionic components, particularly the water to be treated containing a large amount of weakly acidic components such as silica and carbonic acid, can be sufficiently treated. It becomes possible. When the flow of the water to be treated and the concentrated water flowing through the small desalting chamber filled with the mixture of the cation exchanger and the anion exchanger are reversed, the concentrated water in which the cation components such as magnesium and calcium ions are concentrated is immediately removed. It can flow out of the concentration chamber and prevent scale generation in the concentration chamber.

According to the fourth aspect of the invention, in addition to having the same effects as the above-mentioned invention, in the step of producing deionized water, when a single membrane is used, the ions to be removed from the water to be treated are either cations or anions. An ion exchange membrane can be selected depending on whether it is an ion or not. Further, the double membrane has a cation exchange membrane or an anion exchange membrane disposed at the top or bottom of the apparatus. In this case, for example, a cation membrane or a cation membrane is disposed on the first small desalination chamber treated water side (inlet side). When the anion exchange membrane is disposed on the treated water side (outlet side) of the first small-size desalination chamber, the cation component is moved from the second small-size desalination chamber, and the pH of the first small-size desalination chamber is easily shifted to the alkali side. In other words, the ionization of the nonionic silica proceeds, and the effect is obtained that the silica is further reduced through the anion exchange membrane disposed on the treated water side (outlet side) of the first small demineralization chamber.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an electric deionized water producing apparatus used in an embodiment of the present invention.

FIG. 2 is a schematic view of a conventional electric deionized water producing apparatus.

[Explanation of symbols]

D, D _{1 to} D ₄ , 104 Desalination chamber d ₁ , d ₃ , d ₅ , d ₇ First small desalination chamber d ₂ , d ₄ , d ₆ , d ₈ Second small desalination chamber ₁ , 105 Concentration Chamber 2, 112, 113 Electrode chamber 3, 101 Cationic membrane 4, 102 Anion membrane 5 Intermediate ion exchange membrane 6, 109 Cathode 7, 110 Anode 8, 103 Ion exchanger 10, 100 Electric deionized water producing apparatus 11, 111 Treated water inflow line 12 Treated water outflow line in second small desalination chamber 13 Treated water inflow line in first small desalination chamber 14, 114 Deionized water outflow line 15, 115 Concentrated water inflow line 16, 116 Concentrated water Outflow line 17, 117 Electrode water inflow line 18, 118 Electrode water outflow line 19a, 19b Connection pipe 81 Anion exchanger 191, 192 Valve

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[Procedure amendment]

[Submission date] January 31, 2001 (2001.1.3)
1)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 1

[Correction method] Change

[Correction contents]

FIG.

Continued on the front page F term (reference) 4D006 GA17 HA47 HA95 JA39Z JA41Z JA42Z JA43Z JA44Z JA45Z JA55Z JA63Z JA68Z KA26 KA41 KA61 KB01 KB11 KC02 KC12 MA13 MA14 MA15 MB07 PA01 PA02 PB02 PB04 PB05 PB31 DA02PCB DAB PC DB05 DB13 DB18 DC19 EA09 EB04 EB13 FA08 FA09

Claims (4)

[Claims] 1. An ion exchange system comprising two small desalination chambers defined by a cation exchange membrane on one side, an anion exchange membrane on the other side, and an intermediate ion exchange membrane located between the cation exchange membrane and the anion exchange membrane. An ion exchanger filled with a body and filled in a small desalination chamber partitioned by the other side anion exchange membrane and the intermediate ion exchange membrane constitutes a desalination chamber as an anion exchanger, and the cation exchange membrane, Concentration chambers are provided on both sides of the desalination chamber via an anion exchange membrane, and the desalination chamber and the concentration chamber are arranged between the anode and the cathode. The water to be treated flows into the salt chamber, then the effluent from the small desalination chamber flows into the other small desalination chamber, and the concentrated water flows into the concentration chamber to remove impurity ions in the water to be treated. A deionized water producing step of producing deionized water, The effluent from one of the small desalination chambers into which the treated water flows is discharged out of the system without flowing into the other small desalination chamber, and the concentrated water flows into the concentrating chamber and the impurity anions in the water to be treated are discharged. And a concentration chamber cleaning step of reducing the pH of the concentrated water. 2. Performing the deionized water production step and then performing a concentration chamber cleaning step, or performing the deionized water production step and then stopping the operation, and then performing the concentration chamber cleaning step when the operation is resumed. The method for operating the electric deionized water production apparatus according to claim 1, wherein the operation is performed. 3. The ion exchanger filled in the other small desalting chamber partitioned by the one side cation exchange membrane and the intermediate ion exchange membrane is a mixture of a cation exchanger and an anion exchanger. The method for operating an electric deionized water producing apparatus according to claim 1 or 2, wherein: 4. The method according to claim 1, wherein the intermediate ion exchange membrane is a single membrane of a cation exchange membrane or an anion exchange membrane, or a double membrane in which both an anion exchange membrane and a cation exchange membrane are arranged. The method for operating the electric deionized water production apparatus according to any one of claims 3 to 7.