JP4481417B2 - Deionized water production method - Google Patents

Description

【００３２】
【発明の効果】
本発明によれば、濃縮水や電極水はより電解質濃度が高まり、脱塩室の入口側から出口側の全体に渡り電流密度を均一化でき、消費電力を低減できる。また、電解質として酸を使用すれば、付着したスケールを酸洗浄できる。この電解質溶液の添加は、ひとつの脱塩室が２つの小脱塩室からなる当該電気式脱イオン水製造装置においては特に有効である。すなわち、当該装置においては２つの小脱塩室、濃縮室などで水の流れがそれぞれに存在し、電流の流れやすい箇所、流れ難い箇所もそれぞれに存在するので電流の偏りが生じ易く、処理水の水質を低下させる場合があるが、電解質溶液の添加によりこれらの問題を解決できる。
【図面の簡単な説明】
【図１】本発明で使用する電気式脱イオン水製造装置の１例を示す模式図である。
【図２】従来の電気式脱イオン水製造装置の模式図である。
【符号の説明】
Ｄ、Ｄ₁ 〜Ｄ₄ 、１０４ 脱塩室
ｄ₁ 、ｄ₃ 、ｄ₅ 、ｄ₇ 第１小脱塩室
ｄ₂ 、ｄ₄ 、ｄ₆ 、ｄ₈ 第２小脱塩室
１、１０５ 濃縮室
２、１１２、１１３ 電極室
３、１０１ カチオン膜
４、１０２ アニオン膜
５ 中間イオン交換膜
６、１０９ 陰極
７、１１０ 陽極
８、１０３ イオン交換体
１０、１００ 電気式脱イオン水製造装置
１１、１１１ 被処理水流入ライン
１２ 第２小脱塩室の処理水流入ライン
１３ 第１小脱塩室の処理水流入ライン
１４、１１４ 脱イオン水流出ライン
１５、１１５ 濃縮水流入ライン
１６、１１６ 濃縮水流出ライン
１７ａ、１７ｂ、１１７ 電極水流入ライン
１８ａ、１８ｂ、１１８ 電極水流出ライン[0001]
BACKGROUND OF THE INVENTION
The present invention reduces the electrical resistance of power-saving electrical deionized water production equipment used in various industries such as semiconductor manufacturing field, pharmaceutical manufacturing field, power generation field such as nuclear power and thermal power, food industry, and laboratory facilities. The present invention relates to a method for producing deionized water.
[0002]
[Prior art]
As a method for producing deionized water, there is conventionally known a method in which deionized water is passed through an ion exchange resin to be treated. In this method, regeneration is performed with a drug when the ion exchange resin is saturated with ions. In order to eliminate such disadvantages in processing operations, recently, a method for producing deionized water by an electric deionization method which does not require any regeneration by a chemical agent has been established and has been put into practical use.
[0003]
FIG. 2 is a schematic sectional view of the conventional typical electric deionized water production apparatus. As shown in FIG. 2, the cation exchange membrane 101 and the anion exchange membrane 102 are alternately arranged apart from each other, and every other ion exchanger 103 is placed in the space formed by the cation exchange membrane 101 and the anion exchange membrane 102. Fill with desalination chamber. The treated water inflow side (front stage) of the desalting chamber is filled with anion exchange resin 103a, and the treated water outflow side (rear stage) of the desalting chamber is filled with a mixed ion exchange resin 103b of a cation exchange resin and an anion exchange resin. Filled. Further, a portion not filled with the ion exchanger 103 formed by the anion exchange membrane 102 and the cation exchange membrane 101 located adjacent to each of the desalting chambers 104 is a concentration chamber 105 for flowing concentrated water.
[0004]
Further, a deionization module is formed by the cation exchange membrane 101, the anion exchange membrane 102, and the ion exchanger 103 filled therein. That is, a cation exchange membrane is sealed on one side of a frame body whose interior is omitted in the figure, an anion exchange resin is placed on the upper part (front stage) of the hollowed part of the frame body, and the lower part (rear stage). Each is mixed with a mixed ion exchange resin, and then an anion exchange membrane is sealed to the other part of the frame. The ion exchange membrane is relatively soft, and when the ion exchanger is filled inside the frame and sealed on both sides with the ion exchange membrane, the ion exchange membrane is curved and the packed layer of the ion exchanger becomes In order to prevent non-uniformity, a plurality of ribs are generally provided vertically in the space of the frame.
[0005]
FIG. 2 shows a state in which a plurality of such deionization modules are sandwiched between them with a spacer not shown in the figure interposed therebetween. A cathode 109 is arranged on one side of the deionization modules arranged side by side. And an anode 110 is disposed on the other end side. In addition, the position where the above-mentioned spacer is sandwiched is the concentrating chamber 105, and on both outer sides of the concentrating chamber 105 at both ends, if necessary, a partition such as a cation exchange membrane 101, an anion exchange membrane 102, or a simple membrane having no ion exchange properties. The portions where the membranes are arranged and the electrodes 109 and 110 that are partitioned by the partition membrane are in contact with each other are referred to as a cathode chamber 112 and an anode chamber 113, respectively. Thus, in the conventional electric deionized water production apparatus, the number of concentration chambers is one more than the number of demineralization chambers, or the concentration chambers at both ends are separated from the electrode chamber without a partition membrane. In that case, it was one less.
[0006]
The case where deionized water is manufactured by such an electric deionized water manufacturing apparatus will be described with reference to FIG. That is, a direct current is passed between the cathode 109 and the anode 110, water to be treated flows from the water to be treated inflow line 111, concentrated water from the concentrated water inflow line 115, and electrode water inflow lines 117 and 117. Electrode water flows from each. To-be-treated water flowing from the to-be-treated water inflow line 111 flows down the desalting chamber 104, and first passes through the anion exchange resin 103a in the previous stage and then the mixed ion exchange resin 103b, and then, hydrochloric acid ions, sulfate ions, Mg and Ca. Cation components such as are removed. Concentrated water flowing in 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 concentrates as concentrated water in which impurity ions are concentrated. The electrode water flowing out from the outflow line 116 and further flowing in from the electrode water inflow lines 117 and 117 flows out from the electrode water outflow lines 118 and 118. Accordingly, demineralized water is obtained from the deionized water outflow line 114.
[0007]
On the other hand, various attempts have been made to reduce the electrical resistance of the electrical deionized water production apparatus in order to remove the impurity ions in the water to be treated with power saving using such an electrical deionized water production apparatus. Yes. In this case, in the desalting chamber, since the filling method of the ion exchanger used in the desalting chamber and the quality of the treated water required are determined, the electric resistance of the desalting chamber can be reduced. There is a limit. Therefore, in many cases, a method is adopted in which the increase in the conductivity is promoted by the circulation of the concentrated water and the electric resistance of the concentration chamber is reduced. This method is extremely effective in reducing the electric resistance of the concentrating chamber.
[0008]
[Problem to be Solved by the Invention]
However, for example, when a part of the permeated water of the reverse osmosis membrane device which is the treated water is used as concentrated water, hardness components such as Ca and Mg which are initially present in a minute amount in the concentrated water are used for a long period of circulation. It becomes easy to precipitate as a scale in the concentration chamber. When the scale occurs, the electrical resistance at that portion increases, and current does not flow easily. That is, in order to pass the same current value as when no scale is generated, it is necessary to increase the voltage, which increases power consumption. In addition, the current density differs in the concentration chamber depending on the place where the scale is deposited, and current non-uniformity occurs in the desalting chamber. Further, when the scale adhesion amount further increases, a water flow differential pressure is generated and the voltage further increases. When the maximum voltage value of the apparatus is exceeded, the current value decreases. In this case, the current value necessary for ion removal cannot flow, and the quality of the treated water is deteriorated.
[0009]
Therefore, the object of the present invention is to improve the electrical conductivity of electrode water and concentrated water in addition to drastic improvement from the structural aspect of the electric deionized water production apparatus, and reduce the electrical resistance and An object of the present invention is to provide a method for producing deionized water that can prevent the generation of scale.
[0010]
[Means for Solving the Problems]
In this situation, the present inventors have conducted intensive studies, and as a result, (1) partitioned 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 two membranes 2 A small desalting chamber is filled with an ion exchanger to form a desalting chamber, and a concentration chamber is provided on both sides of the desalting chamber via the cation exchange membrane and anion exchange membrane. If an electric deionized water production apparatus having a structure in which an anode chamber having an anode and a cathode chamber having a cathode are used is used, at least one of the two small desalting chambers is filled. The ion exchanger can be a single ion exchanger such as only an anion exchanger, or only a cation exchanger, or a mixed exchanger of an anion exchanger and a cation exchanger. Reduce resistance and get high performance (2) When deionized water is produced using the electric deionized water production apparatus having the above structure, an electrolyte solution may be added and supplied to the concentrated water or electrode water. For example, the current density can be made uniform from the inlet side to the outlet side of the desalting chamber, and the power consumption can be further reduced. (3) If an inorganic acid is used as the electrolyte, the attached scale can be acid-washed, etc. As a result, the present invention has been completed.
[0011]
That is, the invention (1) of claim 1 is directed to a cation exchange membrane on one side, an anion exchange membrane on the other side, and an intermediate ion that is a single membrane or a dual membrane located between the cation exchange membrane and the anion exchange membrane. Two small desalting chambers partitioned by an exchange membrane are filled with ion exchangers to form a desalting chamber, and concentration chambers are provided on both sides of the desalting chamber via the cation exchange membrane and anion exchange membrane. The desalting chamber and the concentrating chamber are disposed between an anode chamber equipped with an anode and a cathode chamber equipped with a cathode, and water to be treated flows into one small desalting chamber while applying a voltage. In the method of producing deionized water by flowing the effluent from the demineralization chamber into the other small desalination chamber and removing the impurity ions in the water to be treated by flowing the concentrated water into the concentration chamber, Concentrated water supplied, anode water supplied to the anode chamber and supplied to the cathode chamber Of the cathode water that is intended to provide a deionized water producing method characterized by the addition supplying the electrolyte solution in at least one. By adopting such a configuration, the ion exchanger filled in at least one of the two small desalting chambers is, for example, only an anion exchanger, or a single ion exchanger or anion such as only a cation exchanger. It can be a mixed exchanger of an exchanger and a cation exchanger, and can be set to an optimum thickness for reducing the electric resistance and obtaining high performance for each type of ion exchanger. Concentrated water and electrode water have a higher electrolyte concentration, and the current density can be made uniform from the inlet side to the outlet side of the desalting chamber, thereby further reducing power consumption. Further, if an acid is used as the electrolyte, the attached scale can be washed with an acid. The addition of the electrolyte solution is particularly effective in the electric deionized water production apparatus in which one desalting chamber is composed of two small desalting chambers. That is, in this apparatus, water flows in two small desalination chambers, concentration chambers, etc., and there are locations where current easily flows and locations where current does not flow easily. However, these problems can be solved by adding an electrolyte solution.
[0012]
The invention (2) of claim 2 is a cation exchange membrane on one side, an anion exchange membrane on the other side, and an intermediate ion exchange membrane which is a single membrane or a multiple membrane located between the cation exchange membrane and the anion exchange membrane. The two small desalting chambers are filled with ion exchangers to form a desalting chamber, and concentration chambers are provided on both sides of the desalting chamber via the cation exchange membrane and anion exchange membrane. A salt chamber and a concentrating chamber are disposed between an anode chamber having an anode and a cathode chamber having a cathode, and water to be treated flows into one small desalting chamber while applying a voltage, and then the small desalting chamber In the method for producing deionized water by flowing out the effluent of the chamber into the other small desalination chamber and removing the impurity ions in the water to be treated by flowing the concentrated water into the concentration chamber, the deionized water is supplied to the concentration chamber. Concentrated water, anode water supplied to the anode chamber, or cathode supplied to the cathode chamber Is to provide a deionized water producing method thereof conductivity, characterized in that a 100~1000μS / cm. By adopting such a configuration, the same effects as those of the above-described invention can be obtained, and concentrated water and electrolyzed water can be managed with a conductivity meter, which is a relatively simple device, and operation management is easy. Further, when the concentration of the electrolyte in the concentrated water is high, there is a concern that the quality of the treated water is deteriorated due to the osmotic pressure, but this worry is eliminated.
[0013]
Invention (3) of claim 3 provides the method for producing deionized water according to (1), wherein the electrolyte solution is a solution containing no hardness ions. By adopting such a configuration, it is possible to eliminate the hardness component in the concentrated water and electrolytic water as much as possible to increase the electrolyte concentration, and to prevent the generation of scale.
[0014]
Invention (4) of claim 4 provides the method for producing deionized water according to item (1), wherein the electrolyte is an inorganic acid. By adopting such a configuration, the scale in the concentrating chamber is removed by the cleaning action of the inorganic acid, and the scale is hardly generated.
[0015]
The invention (5) of claim 5 is a cation exchange membrane on one side, an anion exchange membrane on the other side, and an intermediate ion exchange membrane which is a single membrane or a multiple membrane located between the cation exchange membrane and the anion exchange membrane. The two small desalting chambers are filled with ion exchangers to form a desalting chamber, and concentration chambers are provided on both sides of the desalting chamber via the cation exchange membrane and anion exchange membrane. A salt chamber and a concentrating chamber are disposed between an anode chamber having an anode and a cathode chamber having a cathode, and water to be treated flows into one small desalting chamber while applying a voltage, and then the small desalting chamber In the method for producing deionized water by flowing out the effluent of the chamber into the other small desalination chamber and removing the impurity ions in the water to be treated by flowing the concentrated water into the concentration chamber, the deionized water is supplied to the concentration chamber. Concentrated water, anode water supplied to the anode chamber, or cathode supplied to the cathode chamber Is to provide a deionized water producing method characterized by its pH is 1-5. By adopting such a configuration, the same effects as those of the above-described invention can be obtained, and concentrated water and electrode water can be managed with a pH meter which is a relatively simple device, and operation management is easy.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
An electric deionized water production apparatus used in the deionized water production method of the present invention will be described with reference to FIG. FIG. 1 is a schematic view showing an example of an electric deionized water production apparatus. As shown in FIG. 1, the cation exchange membrane 3, the intermediate ion exchange membrane 5 and the anion exchange membrane 4 are alternately arranged apart from each other, and ion exchange is performed in the space formed by the cation exchange membrane 3 and the intermediate ion exchange membrane 5. The body 8 is filled to form the first small desalting chambers d ₁ , d ₃ , d ₅ , d ₇ and the space formed by the intermediate ion exchange membrane 5 and the anion exchange membrane 4 is filled with the ion exchanger 8. The second small desalting chambers d ₂ , d ₄ , d ₆ , and d ₈ are formed, and the first small desalting chamber d ₁ and the second small desalting chamber d _{2 form} the desalting chamber D ₁ and the first small desalting chamber d _2. The desalting chamber D ₃ and the second small desalting chamber d ₄ are the desalting chamber D ₂ , and the first small desalting chamber d ₅ and the second small desalting chamber d ₆ are the desalting chamber D ₃ and the first small desalting chamber. The chamber d ₇ and the second small desalting chamber d ₈ are referred to as a desalting chamber D ₄ . A portion not filled with the ion exchanger 8 formed by the anion exchange membrane 4 and the cation exchange membrane 3 located next to each of the desalting chambers D ₂ and D ₃ is a concentration chamber 1 for flowing concentrated water. To do. Drawing sequentially features this depletion chamber D ₁ from the left, concentrating chamber 1, desalting D _2, concentrating chamber 1, depletion chamber D _3, concentrating chamber 1, to form a depletion chamber D _4. Further, the cathode chamber 2a through the cation exchange membrane 3 to the left of the depletion chamber D _1, provided respectively anode chamber 2b through the anion exchange membrane 4 to the right of the depletion chamber D _4. Further, in two small desalination chambers adjacent via the intermediate membrane 5, the treated water outflow line 12 of the treated water in the second small desalting chamber is connected to the treated water inflow line 13 of the first small desalting chamber. Has been.
[0017]
Such a desalting chamber is composed of a deionization module formed by two framed hollow bodies and three ion exchange membranes. That is, a cation exchange membrane is sealed on one side of the first frame that is not shown in the figure, the hollowed portion of the first frame is filled with the ion exchanger, and then the other portion of the first frame is filled. An intermediate ion exchange membrane is sealed to form a first small desalting chamber. Next, the second frame is sealed so as to sandwich the intermediate ion exchange membrane, and the hollowed portion of the second frame is filled with the ion exchanger, and then the other portion of the second frame is filled with the anion exchange membrane. To form a second small desalted material.
[0018]
The electric deionized water production apparatus is usually operated as follows. That is, a direct current is passed between the cathode 6 and the anode 7, and water to be treated flows from the treated water inflow line 11, concentrated water flows from the concentrated water inflow line, and the cathode water inflow line 17 a and the anode water flow in. Cathode water and anode water flow in from the line 17b, respectively. To-be-treated water flowing from the to-be-treated water inflow line 11 flows down the second small desalination chambers d ₂ , d ₄ , d ₆ , and d ₈ , and impurity ions are removed when passing through the packed bed of the ion exchanger 8. Is done. Furthermore, the effluent that has passed 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 chambers d ₁ , d ₃ , d. ₅ and d ₇ flow down, and again, when passing through the packed bed of the ion exchanger 8, impurity ions are removed and deionized water is obtained from the deionized water outflow line 14. Further, the concentrated water flowing in from the concentrated water inflow line 15 rises in each concentration chamber 1, receives impurity ions moving through the cation exchange membrane 3 and the anion exchange membrane 4, and concentrates the impurity ions as concentrated water. Cathode water flowing out from the concentrating chamber outflow line 16 and further flowing in from the cathode water inflow line 17a flows out from the cathode water outflow line 18a, and anode water flowing in from the anode water inflow line 17b flows out from the anode water outflow line 18b. The By the above operation, impurity ions in the water to be treated are electrically removed. The flow direction in the first small desalination chamber and the second small desalination chamber of the water to be treated is not particularly limited, and in addition to the above embodiment, in the first small desalination chamber and the second small desalination chamber. The flow direction may be different. In addition to the above embodiment, the small desalination chamber into which the water to be treated flows first flows the water to be treated into the first small desalination chamber and then flows down, and then flows out of the first small desalination chamber. Water may flow into the second small desalting chamber. Further, the flow direction of the concentrated water is also appropriately determined.
[0019]
In the deionized water production method of the present invention, when using the electric deionized water production apparatus, the concentrated water supplied to the concentration chamber, the anode water supplied to the anode chamber, and the cathode chamber are supplied. An electrolyte solution is added and supplied to at least one selected from the cathode water. The electrolyte solution is added and supplied, for example, by a metering pump, continuously or intermittently added to the concentrated water supplied to the concentration chamber or the electrode water supplied to the electrode chamber via the injection tube. Done. The electrolyte solution may be added to one or more of concentrated water, anode water, and cathode water, and the electrolyte solution may be added to all concentrated water, anode water, and cathode water. The method is preferable from the viewpoint of making the current density uniform over the entire effective area of the desalting chamber and reducing the electrical resistance. In addition, when an electrolyte solution is added and supplied to concentrated water, anode water, or cathode water, if the method of recirculating the concentrated water, anode water, or cathode water is employed, the supply amount of electrolyte solution is reduced. You can also
[0020]
The electrolyte used in the deionized water production method of the present invention is not particularly limited, and may be an inorganic electrolyte or an organic electrolyte. Examples of inorganic electrolytes include nitric acid, sulfuric acid, inorganic acids such as phosphoric acid such as H ₃ PO ₄ and H ₄ P ₂ O ₇ , metal hydroxides such as NaOH, KOH, and CuOH, K ₂ SO ₄ , NaNO _{3 and the} like. Examples thereof include metal salts. It is preferable that the inorganic electrolyte does not contain a metal species of a hardness component such as Ca or Mg that may be deposited as a scale. Further, since chlorine may be generated at the anode, it is better not to use chlorides such as HCl and NaCl. As the inorganic electrolyte, it is particularly preferable to use an inorganic acid such as nitric acid or sulfuric acid having a cleaning action on the scale. Organic electrolytes include water-soluble organic acids such as carboxylic acids such as formic acid, acetic acid and oxalic acid, amines such as ethylamine and ethylenediamine, polyaminocarboxylic acids such as EDTA (ethylenediaminetetraacetic acid), and oxycarboxylic acids such as glyceric acid and glycolic acid. Examples include chelating agents for acids. It is particularly preferable to use EDTA as the organic electrolyte. These electrolytes may be used alone or in a combination of two types.
[0021]
Moreover, in the deionized water manufacturing method of this invention, the electrical conductivity of concentrated water, anode water, and cathode water is 100-1000 microsiemens / cm normally, Preferably it is 300-800 microsiemens / cm. If the electrical conductivity is less than 100 μS / cm, the effect of reducing the electric resistance is reduced, and if it exceeds 1000 μS / cm, the concentrated water leaks through the ion exchange membrane to the desalting chamber due to the osmotic pressure. It is not preferable at the point which reduces the quality of treated water.
[0022]
Moreover, in the deionized water manufacturing method of this invention, when an acid is used for electrolyte, pH of concentrated water, anode water, and cathode water is 1-5, Preferably it is 1.5-3.0. If the pH is less than 1, there is a high possibility that anion components such as sulfate ions and nitrate ions will diffuse back to the desalting chamber side, and if the pH exceeds 5, it becomes difficult to dissolve the scale attached to the electrode chamber. The acid cleaning ability is reduced.
[0023]
The treated water used in the deionized water production method of the present invention is not particularly limited. For example, from well water, tap water, sewage, industrial water, river water, washing waste water or concentration chambers such as semiconductor devices in semiconductor manufacturing plants. Permeated water obtained by treating the recovered water with a reverse osmosis membrane. In this way, the reverse osmosis membrane treatment is performed as a pretreatment, and when using a part of the permeated water as the concentrated water, the treated water supplied to the desalting chamber and the concentrated water supplied to the concentration chamber are softened, It is preferable to use it in that scale generation can be suppressed. The softening method is not particularly limited, but a softener using a sodium ion exchange resin or the like is suitable.
[0024]
In the electric deionized water production apparatus used in the present invention, as the intermediate ion exchange membrane, any of a single membrane of a cation exchange membrane or an anion exchange membrane, or a multiple membrane in which both an anion exchange membrane and a cation exchange membrane are arranged It may be. In case of a dual membrane in which both an anion exchange membrane and a cation exchange membrane are arranged in the upper part or lower part of the device, the height (area) of each of the anion exchange membrane and the cation exchange membrane depends on the quality of the water to be treated or the purpose of treatment. It is determined appropriately. Moreover, when using a single membrane, an ion membrane is determined according to the ion species to be removed from the water to be treated.
[0025]
The ion exchanger filled in the desalting chamber is not particularly limited, and examples thereof include an anion exchanger single bed, a cation exchanger single bed, a mixed bed of an anion exchanger and a cation exchanger, or a combination thereof. 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. In addition, the conductivity of the desalting chamber can be further increased by adding a conductive substance to both the ion exchangers. The shape of the conductive biomaterial to be added is not particularly limited, and may be fiber or granular. Examples of the conductive fiber include carbon fiber or synthetic fiber such as nylon-based, acrylic-based, polyester-based or the like alone or kneaded to form a composite fiber whose surface is coated with carbon black. Examples of the granular conductive material include small graphite and small activated carbon.
[0026]
【Example】
Example 1
In the following apparatus specifications and operating conditions, an electric deionized water production apparatus constituted by arranging three deionization modules (six small demineralization chambers) in parallel with the same configuration as in FIG. 1 was used. As the water to be treated, reverse osmosis membrane permeated water for industrial water was used, and its conductivity was 3.0 μS / cm. Moreover, some treated water was used as concentrated water and electrode water. About 5% Na ₂ SO ₄ solution was added and supplied to the concentrated water flowing into the concentration chamber and the electrode water flowing into the electrode chamber (cathode chamber and anode chamber) with a metering pump. In this case, the concentrated water or the electrode water was operated in the subsequent operation, and the metering pump was operated so that the conductivity of the influent water in the concentration chamber and the electrode chamber was approximately 600 μS / cm. The operation time was 5000 hours. Table 1 shows operating conditions for obtaining treated water having a resistivity of 17.9 MΩ-cm after 5000 hours.
[0027]
(Operating conditions)
・ Electric deionized water production equipment; prototype EDI
・ First small desalination chamber: width 300mm, height 600mm, thickness 3mm
-Ion exchange resin filled in the first small desalting chamber; mixed ion exchange resin of anion exchange resin (A) and cation exchange resin (K) (mixing ratio is A: K = 1: 1 by volume)
・ Second small desalination chamber; width 300mm, height 600mm, thickness 8mm
・ Second ion exchange resin filled in small desalting chamber; anion exchange resin ・ Flow rate of the entire apparatus: 1 m ³ / h
[0028]
Example 2
Instead of the approximately 5% Na ₂ SO ₄ solution added to the concentrated water and the electrode water, an approximately 3% H ₂ SO ₄ solution is added and supplied. The procedure was the same as in Example 1 except that the pH was sometimes added so that the pH was approximately 2. In this experiment, the water flow differential pressure in the concentrating chamber after 5000 hours was also measured. The results are shown in Table 1.
[0029]
Comparative Example 1
In the following apparatus specifications and operating conditions, an electric deionized water production apparatus configured by arranging six deionization modules in parallel with the same configuration as in FIG. 2 was used. However, the concentrated water and the electrode water were used by branching a part of the treated water, and the concentrated water was returned to the treated water side of the reverse osmosis membrane device. Moreover, the thing similar to Example 1 was used for to-be-processed water. The operation time was 5000 hours. The water flow differential pressure in the concentration chamber after 5000 hours was measured in the same manner. Table 1 shows the operating conditions for obtaining treated water having a resistivity of 17.9 MΩ-cm at the same time.
[0030]
(Operating conditions)
-Electric deionized water production equipment; EDI (manufactured by Organo)
・ Desalination chamber: width 300mm, height 600mm, thickness 8mm
・ Ion exchange resin packed downstream of the desalting chamber; mixture of anion exchange resin (A) and cation exchange resin (K) (mixing ratio is A: K = 1: 1 by volume)
・ Flow rate of the entire device: 1m ³ / h
[0031]
[Table 1]

[0032]
【The invention's effect】
According to the present invention, the concentration of electrolyte in concentrated water and electrode water is further increased, the current density can be made uniform from the inlet side to the outlet side of the desalting chamber, and the power consumption can be reduced. Further, if an acid is used as the electrolyte, the attached scale can be washed with an acid. The addition of the electrolyte solution is particularly effective in the electric deionized water production apparatus in which one desalting chamber is composed of two small desalting chambers. That is, in this apparatus, water flows in two small desalination chambers, concentration chambers, etc., and there are locations where current easily flows and locations where current does not flow easily. However, these problems can be solved by adding an electrolyte solution.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of an electrical deionized water production apparatus used in the present invention.
FIG. 2 is a schematic view of a conventional electric deionized water production 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 production apparatus 11, 111 Processed water inflow line 12 Processed water inflow line 13 in the second small desalination chamber Processed water inflow line 14, 114 in the first small desalination chamber Deionized water outflow line 15, 115 Concentrated water inflow line 16, 116 Concentrated water outflow Lines 17a, 17b, 117 Electrode water inflow lines 18a, 18b, 118 Electrode water outflow lines

Claims (5)

Two small desalting chambers defined by a cation exchange membrane on one side, an anion exchange membrane on the other side, and an intermediate ion exchange membrane that is a single membrane or a dual membrane located between the cation exchange membrane and the anion exchange membrane An ion exchanger is filled to form a desalting chamber. Concentration chambers are provided on both sides of the desalting chamber via the cation exchange membrane and anion exchange membrane, and the desalting chamber and the concentration chamber are provided with an anode. Arranged between the anode chamber and the cathode chamber provided with the cathode, the water to be treated flows into one small desalination chamber while applying a voltage, and then the effluent from the small desalination chamber flows into the other In the method for producing deionized water by flowing concentrated water into the concentrating chamber to remove impurity ions in the water to be treated and supplying deionized water, the concentrated water supplied to the concentrating chamber is supplied to the anode chamber. At least one of anode water supplied to the cathode chamber Deionized water production method is characterized by adding supplying an electrolyte solution. Two small desalting chambers defined by a cation exchange membrane on one side, an anion exchange membrane on the other side, and an intermediate ion exchange membrane that is a single membrane or a dual membrane located between the cation exchange membrane and the anion exchange membrane An ion exchanger is filled to form a desalting chamber. Concentration chambers are provided on both sides of the desalting chamber via the cation exchange membrane and anion exchange membrane, and the desalting chamber and the concentration chamber are provided with an anode. Arranged between the anode chamber and the cathode chamber provided with the cathode, the water to be treated flows into one small desalination chamber while applying a voltage, and then the effluent from the small desalination chamber flows into the other In the method for producing deionized water by flowing concentrated water into the concentrating chamber to remove impurity ions in the water to be treated and supplying deionized water, the concentrated water supplied to the concentrating chamber is supplied to the anode chamber The anode water supplied to the cathode chamber or the cathode chamber has a conductivity of 100. Deionized water production method which is a 1000 .mu.s / cm.   The method for producing deionized water according to claim 1, wherein the electrolyte solution is a solution containing no hardness ions.   The method for producing deionized water according to claim 1, wherein the electrolyte is an inorganic acid. Two small desalting chambers defined by a cation exchange membrane on one side, an anion exchange membrane on the other side, and an intermediate ion exchange membrane that is a single membrane or a dual membrane located between the cation exchange membrane and the anion exchange membrane An ion exchanger is filled to form a desalting chamber. Concentration chambers are provided on both sides of the desalting chamber via the cation exchange membrane and anion exchange membrane. Arranged between the anode chamber and the cathode chamber provided with the cathode, the water to be treated flows into one small desalination chamber while applying a voltage, and then the effluent from the small desalination chamber flows into the other small desalination chamber. In the method for producing deionized water by flowing concentrated water into the concentrating chamber to remove impurity ions in the water to be treated and supplying deionized water, the concentrated water supplied to the concentrating chamber is supplied to the anode chamber The anode water supplied to the cathode chamber or the cathode chamber has a pH of 1 to 5. Deionized water producing method comprising Rukoto.

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