Electrodeionization device for low-chlorine electrode water

Abstract

The invention discloses an electrodeionization device for low-chlorine electrode water, which comprises a negative electrode (11), a positive electrode (41), a plurality of anion exchange membranes (20) and a plurality of cation exchange membranes (30), the anion exchange membranes (20) and the cation exchange membranes (30) are alternately positioned between the negative electrode (11) and the positive electrode (41), and the membrane adjacent to the positive electrode (41) is the cation exchange membrane (30); a negative electrode chamber (1) is formed between the negative electrode (11) and the adjacent membrane, a positive electrode chamber (4) is formed between the positive electrode (41) and the adjacent membrane, and a fresh water chamber (2) and a concentrated water chamber (3) are alternately formed between the adjacent membranes; the positive electrode chamber (4) is adjacent to the concentrated water chamber (3), and inlet water PEI of the positive electrode chamber (4) is ultrapure water. According to the electrodeionization device for the low-chlorine electrode water provided by the invention, the effluent PEO of the positive electrode chamber is approximately neutral, so that the risk of chlorine oxidation is greatly reduced.

Description

Technical Field

[0001] The present application relates to the technical field of membrane separation, and particularly to an electro-deionization device for low-chlorine electrode water. Background Art

[0002] Electro-de-ionization (EDI or Continuous electro-de-ionization, CEDI) is a membrane separation process in which ion exchange resins adsorb anions and cations in a fresh water stream, and at the same time, under the action of an electric field, the adsorbed anions and cations migrate through anion and cation exchange membranes respectively to a concentrated water stream. The result of this process is that ions in the fresh water stream are removed, while ions in the concentrated water stream are enriched. Compared with the ion exchange method, electro-de-ionization has the advantages of not requiring chemical regeneration and stable desalination, and is usually used for the preparation of ultrapure water.

[0003] In recent years, due to the shortage of water resources, it has become a common practice to reuse the drainage of electro-deionization components (including concentrated water effluent, positive electrode chamber inlet water, and negative electrode chamber effluent). However, since the positive electrode water of electro-deionization contains dissolved chlorine, the drainage of electro-deionization components has oxidizing properties, posing a threat to oxidizing reverse osmosis membranes and ion exchange resins inside electro-deionization, and easily causing accidents of oxidation of ion exchange resins or reverse osmosis membranes.

[0004] To solve the above problems of oxidation and burning, there are various designs for the external structure of existing electro-deionization components, such as "three inlets and three outlets", "two inlets and three outlets", "two inlets and two outlets", and "one inlet and two outlets", etc., but none of these designs have well solved the problem of the oxidizing property of positive electrode water. Summary of the Invention

[0005] To solve the above technical problems, the first object of the present invention is to provide an electro-deionization device for low-chlorine electrode water; the electro-deionization device for low-chlorine electrode water provided by the present application defines that adjacent to the positive electrode chamber is a concentrated water chamber, and the membrane adjacent to the positive electrode chamber is a cation exchange membrane, and the inlet water of the positive electrode chamber is ultrapure water, thus preventing anions from entering the positive electrode chamber through electro-migration; at the same time, since the inlet water PEI of the positive electrode chamber is ultrapure water, the electrochemical process in the positive electrode chamber is simplified, and its products are almost all oxygen and hydrogen ions, among which the hydrogen ions participate in conduction equivalently and are migrated to the adjacent concentrated water chamber. Therefore, the effluent PEO of the positive electrode chamber is approximately neutral, and the risk of chlorine oxidation is greatly reduced.

[0006] The technical solution provided by the present invention is as follows:

[0007] An electro-deionization device for low-chlorine electrode water, comprising a negative electrode, a positive electrode, a plurality of anion exchange membranes, and a plurality of cation exchange membranes,

[0008] Anion exchange membranes and cation exchange membranes are alternately located between the negative electrode and the positive electrode, and the membrane adjacent to the positive electrode is a cation exchange membrane;

[0009] A negative electrode chamber is formed between the negative electrode and the adjacent membrane, a positive electrode chamber is formed between the positive electrode and the adjacent membrane, and fresh water chambers and concentrated water chambers are alternately formed between adjacent membranes;

[0010] The positive electrode chamber is adjacent to the concentrated water chamber, and the inlet PEI of the positive electrode chamber is ultrapure water.

[0011] Preferably, the anion exchange membrane between the negative electrode chamber and the concentrated water chamber is adjacent, and the inlet NEI of the negative electrode chamber is ultrapure water.

[0012] Preferably, the ultrapure water used for the inlet PEI of the positive electrode chamber and the inlet NEI of the negative electrode chamber is the outlet DO of the fresh water chamber.

[0013] Preferably, the outlet PEO of the positive electrode chamber and the outlet NEO of the negative electrode chamber are combined into the electrode water outlet EO; or, the outlet PEO of the positive electrode chamber, the outlet NEO of the negative electrode chamber and the outlet CO of the concentrated water chamber are combined into the drainage RO.

[0014] Preferably, the inlet PEI of the positive electrode chamber, the inlet NEI of the negative electrode chamber and the outlet DO of the fresh water chamber are combined; and / or,

[0015] The inlet CI of the concentrated water chamber and the outlet DO of the fresh water chamber are combined.

[0016] Preferably, the water flow directions in the fresh water chamber and the concentrated water chamber are opposite; and / or,

[0017] The water flow directions in the fresh water chamber and the negative electrode chamber are opposite; and / or,

[0018] The water flow directions in the fresh water chamber and the positive electrode chamber are opposite.

[0019] Preferably, the channel of the outlet DO of the fresh water chamber turns back inside the device, so that the interface of the outlet DO of the fresh water chamber and the interface of the inlet DI of the fresh water chamber are on the same side of the device.

[0020] Preferably, the negative electrode chamber further includes a negative electrode insulating plate, and the negative electrode insulating plate is arranged on the side of the negative electrode away from the membrane;

[0021] The positive electrode chamber further includes a positive electrode insulating plate, and the positive electrode insulating plate is arranged on the side of the positive electrode away from the membrane;

[0022] A negative electrode pressing plate is further arranged on the side of the negative electrode insulating plate away from the negative electrode;

[0023] A positive electrode pressing plate is further arranged on the side of the positive electrode insulating plate away from the positive electrode.

[0024] Preferably, a negative electrode frame plate is further arranged between the negative electrode and the adjacent membrane, and a positive electrode frame plate is further arranged between the positive electrode and the adjacent membrane;

[0025] A fresh water frame plate is provided between the anion exchange membrane and the cation exchange membrane in the fresh water chamber, and a concentrated water frame plate is provided between the anion exchange membrane and the cation exchange membrane in the concentrated water chamber;

[0026] The negative electrode frame plate, the positive electrode frame plate, the fresh water frame plate and the concentrated water frame plate are connected to the water distribution pipeline.

[0027] Preferably, an ion conductor is optionally filled in the negative electrode chamber, the fresh water chamber, the concentrated water chamber and the positive electrode chamber.

[0028] The present application discloses an electro - desalination device for low - chlorine electrode water, which includes a negative electrode, a positive electrode, a plurality of anion exchange membranes and a plurality of cation exchange membranes. The anion exchange membranes and the cation exchange membranes are alternately located between the negative electrode and the positive electrode, and the membrane adjacent to the positive electrode is a cation exchange membrane; a negative electrode chamber is formed between the negative electrode and the adjacent membrane, a positive electrode chamber is formed between the positive electrode and the adjacent membrane, and fresh water chambers and concentrated water chambers are alternately formed between adjacent membranes; the positive electrode chamber is adjacent to the concentrated water chamber, and the inlet water of the positive electrode chamber is ultra - pure water. The present application defines that the chamber adjacent to the positive electrode chamber is a concentrated water chamber, the membrane adjacent to the positive electrode chamber is a cation exchange membrane, and the inlet water of the positive electrode chamber is ultra - pure water. Therefore, anions such as chloride ions, sulfate ions, carbonate ions, and hydroxide ions are prevented from entering the positive electrode chamber through electro - migration; at the same time, since the inlet water of the positive electrode chamber is ultra - pure water, the electrochemical process in the positive electrode chamber is simplified, and its products are almost all oxygen and hydrogen ions. The electrode reaction is:

[0029] 2H 2 O→O 2 +4H++4e -

[0030] Among them, hydrogen ions participate in conduction equivalently and are migrated to the adjacent concentrated water chamber. Therefore, the outlet water of the positive electrode chamber is approximately neutral, and the risk of chlorine oxidation is greatly reduced. Description of the Drawings

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0032] Figure 1 It is a schematic diagram of the principle of the electro - desalination device for low - chlorine electrode water in the embodiment of the present invention (the negative electrode chamber is adjacent to the fresh water chamber; the outlet water PEO of the positive electrode chamber and the outlet water NEO of the negative electrode chamber are combined into the electrode water outlet EO; the inlet water PEI of the positive electrode chamber, the inlet water NEI of the negative electrode chamber and the outlet water DO of the fresh water chamber are combined);

[0033] Figure 2Schematic diagram of the principle of the electro - deionization device for low - chlorine electrode water in the embodiments of the present invention (the negative electrode chamber is adjacent to the concentrated water chamber; the effluent PEO from the positive electrode chamber and the effluent NEO from the negative electrode chamber are combined into the electrode water effluent EO; the influent PEI to the positive electrode chamber, the influent NEI to the negative electrode chamber, and the effluent DO from the fresh water chamber are combined);

[0034] Figure 3 Schematic diagram of the principle of the electro - deionization device for low - chlorine electrode water in the embodiments of the present invention (the negative electrode chamber is adjacent to the concentrated water chamber; the effluent PEO from the positive electrode chamber and the effluent NEO from the negative electrode chamber are combined into the electrode water effluent EO; the influent PEI to the positive electrode chamber, the influent NEI to the negative electrode chamber, and the effluent DO from the fresh water chamber are combined, and the influent CI to the concentrated water chamber and the effluent DO from the fresh water chamber are combined);

[0035] Figure 4 Schematic diagram of the principle of the electro - deionization device for low - chlorine electrode water in the embodiments of the present invention (the negative electrode chamber is adjacent to the concentrated water chamber; the effluent PEO from the positive electrode chamber, the effluent NEO from the negative electrode chamber, and the effluent CO from the concentrated water chamber are combined into the drainage RO; the influent PEI to the positive electrode chamber, the influent NEI to the negative electrode chamber, and the effluent DO from the fresh water chamber are combined, and the influent CI to the concentrated water chamber and the effluent DO from the fresh water chamber are combined);

[0036] Figure 5 Schematic diagram of the principle of the electro - deionization device for low - chlorine electrode water in the embodiments of the present invention (the negative electrode chamber is adjacent to the concentrated water chamber; the effluent PEO from the positive electrode chamber, the effluent NEO from the negative electrode chamber, and the effluent CO from the concentrated water chamber are combined into the drainage RO; the influent PEI to the positive electrode chamber, the influent NEI to the negative electrode chamber, and the effluent DO from the fresh water chamber are combined, and the influent CI to the concentrated water chamber and the effluent DO from the fresh water chamber are combined; the water flow direction of the influent DI to the fresh water chamber is opposite to that of the effluent DO from the fresh water chamber);

[0037] Figure 6 Schematic diagram of the principle of the electro - deionization device for low - chlorine electrode water in the embodiments of the present invention (the negative electrode chamber is adjacent to the concentrated water chamber; the effluent PEO from the positive electrode chamber, the effluent NEO from the negative electrode chamber, and the effluent CO from the concentrated water chamber are combined into the drainage RO; the influent PEI to the positive electrode chamber, the influent NEI to the negative electrode chamber, and the effluent DO from the fresh water chamber are combined, and the influent CI to the concentrated water chamber and the effluent DO from the fresh water chamber are combined; the water flow direction of the influent DI to the fresh water chamber is opposite to that of the effluent DO from the fresh water chamber, and the channel of the effluent DO from the fresh water chamber turns back inside the device, so that the interface of the effluent DO from the fresh water chamber and the interface of the influent DI to the fresh water chamber are on the same side of the device);

[0038] Reference numerals: 1 - negative electrode chamber; 11 - negative electrode; 12 - negative electrode insulating plate; 13 - negative electrode pressing plate; 2 - fresh water chamber; 3 - concentrated water chamber; 4 - positive electrode chamber; 41 - positive electrode; 42 - positive electrode insulating plate; 43 - positive electrode pressing plate; 20 - anion exchange membrane; 30 - cation exchange membrane; DI - influent to the fresh water chamber, DO - effluent from the fresh water chamber, CI - influent to the concentrated water chamber, CO - effluent from the concentrated water chamber, EI - electrode water influent, EO - electrode water effluent, RO - mixed drainage, Anion exchange resin, Cation exchange resin. Detailed implementation manners

[0039] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of this application.

[0040] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly disposed on the other element; when an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0041] It should be understood that the orientation or positional relationship indicated by terms such as "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation to this application.

[0042] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of this application, "a plurality of" or "several" means two or more, unless otherwise specifically defined.

[0043] It should be noted that the structures, ratios, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those skilled in this technology to understand and read, and are not used to limit the limited conditions under which this application can be implemented. Therefore, they do not have a technical essence. Any modification of the structure, change in the proportional relationship, or adjustment of the size, without affecting the effects that this application can produce and the purposes that can be achieved, should still fall within the scope covered by the technical content disclosed in this application.

[0044] As shown in the figure, the embodiment of the present invention provides an electro-deionization device for low-chlorine electrode water, including a negative electrode 11, a positive electrode 41, a plurality of anion exchange membranes 20, and a plurality of cation exchange membranes 30.

[0045] The anion exchange membrane 20 and the cation exchange membrane 30 are alternately located between the negative electrode 11 and the positive electrode 41, and the membrane adjacent to the positive electrode 41 is the cation exchange membrane 30;

[0046] A negative electrode chamber 1 is formed between the negative electrode 11 and the adjacent membrane, a positive electrode chamber 4 is formed between the positive electrode 41 and the adjacent membrane, and a fresh water chamber 2 and a concentrated water chamber 3 are alternately formed between adjacent membranes;

[0047] The positive electrode chamber 4 is adjacent to the concentrated water chamber 3, and the inlet PEI of the positive electrode chamber 4 is ultrapure water.

[0048] Regarding the problem of easy oxidation during the operation of the electro-deionization device, the applicant has conducted research and analysis and summarized the reasons as follows:

[0049] In the existing electro-deionization components, a fresh water chamber is usually adjacent to the positive electrode chamber. The inlet water of the positive electrode chamber and the inlet water of the negative electrode chamber are combined into the electrode water inlet, and the outlet water of the positive electrode chamber and the outlet water of the negative electrode chamber are combined into the electrode water outlet. The electrode water inlet is usually the electro-deionization feed water. Since the electro-deionization feed water contains chloride ions, and since chloride ions migrate into the positive electrode chamber through electro-migration from the adjacent fresh water chamber, the chloride ion concentration in the positive electrode chamber is significantly higher than the chloride ion concentration in the electro-deionization feed water.

[0050] If the chloride ion concentration in the inlet water of the positive electrode chamber is CCl1 (ppm) and the flow rate is F1; the chloride ion concentration in the inlet water of the fresh water chamber adjacent to the positive electrode is CCl2 (ppm) and the flow rate is F2. Since the main application of electro-deionization is to prepare ultrapure water, it can be assumed that all the chloride ions in the fresh water chamber adjacent to the positive electrode chamber migrate into the positive electrode chamber through electro-migration (or the remaining chloride ions in the fresh water are ignored). Then the chlorine weight concentration (ppm) content in the water flow of the positive electrode chamber is:

[0051] CCl2≈(C CL1 *F1+C CL2 *F2) / F1

[0052] The existing electro-deionization components operate normally under the condition of a large amount of residual current. The so-called excess current Ie refers to the remaining part of the working current Iw after removing the effective current Io required for migrating the inherent ions in the water, that is, Ie = Iw - Io. It is generally considered that due to a large amount of residual current during electro-deionization operation, all the chloride ions in the positive electrode chamber are electrolyzed into chlorine gas, and part of the excess current is used to generate oxygen.

[0053] To illustrate the problem, assume that the chloride ion content in the inlet water of the positive electrode chamber and the fresh water inlet is both 5 ppm, the positive electrode water flow rate is 30 L / h, and the flow rate of the adjacent fresh water chamber is 100 L / h. The chlorine content in the inlet water of the positive electrode chamber is:

[0054] C Cl2 =(5*30+5*100) / 30=22 ppm

[0055] For a common large-scale electrodeionization unit, the concentrated water flow rate is about 10% of the fresh water flow rate, and the electrode water flow rate including the effluent from the positive electrode chamber and the negative electrode chamber is about 1% of the fresh water flow rate. Under these conditions, the electrodeionization drainage flow rate is about 20 times the positive electrode water effluent flow rate. Therefore, the chlorine content in the electrodeionization drainage is approximately equal to 1.1 ppm. When this part of the water is mixed with about 10 times the amount of raw water during the reuse process, the chlorine concentration is about 0.1 ppm. This chlorine concentration poses a fatal threat to both the ion exchange resin and the reverse osmosis membrane in the electrodeionization module. Therefore, it is urgent to reduce the chlorine concentration in the effluent from the positive electrode chamber to solve the problems existing in the existing electrodeionization modules.

[0056] To address the above problems, the present application discloses an electrodeionization device for low-chlorine electrode water, which includes a negative electrode 11, a positive electrode 41, a plurality of anion exchange membranes 20, and a plurality of cation exchange membranes 30. The anion exchange membranes 20 and the cation exchange membranes 30 are alternately located between the negative electrode 11 and the positive electrode 41, and the membrane sheet adjacent to the positive electrode 41 is a cation exchange membrane 30; a negative electrode chamber 1 is formed between the negative electrode 11 and the adjacent membrane sheet, a positive electrode chamber 4 is formed between the positive electrode 41 and the adjacent membrane sheet, and fresh water chambers 2 and concentrated water chambers 3 are alternately formed between adjacent membrane sheets; the positive electrode chamber 4 is adjacent to the concentrated water chamber 3, and the influent PEI of the positive electrode chamber 4 is ultrapure water. The present application defines that adjacent to the positive electrode chamber 4 is a concentrated water chamber 3, and the membrane sheet adjacent to the positive electrode chamber 4 is a cation exchange membrane 30, and the influent of the positive electrode chamber 4 is ultrapure water. Therefore, anions such as chloride ions, sulfate ions, carbonate ions, and hydroxide ions are prevented from entering the positive electrode chamber 4 through electromigration; at the same time, since the influent PEI entering the positive electrode chamber 4 is ultrapure water, the electrochemical process in the positive electrode chamber 4 is simplified, and its products are almost all oxygen and hydrogen ions. The electrode reaction is:

[0057] 2H 2 O→O 2 +4H++4e -

[0058] Among them, hydrogen ions participate in conduction equivalently and are migrated to the adjacent concentrated water chamber 3. Therefore, the effluent PEO of the positive electrode chamber is approximately neutral, and the risk of chlorine oxidation is greatly reduced.

[0059] Preferably, the anion exchange membrane 20 of the negative electrode chamber 1 is adjacent to the concentrated water chamber 3, and the influent NEI of the negative electrode chamber 1 is ultrapure water.

[0060] The negative electrode chamber 1 can be adjacent to the cation exchange membrane 30 of the fresh water chamber 2 or the anion exchange membrane 20 of the concentrated water chamber 3, and both can cooperate with the above positive electrode chamber etc. to achieve the effect of low-chlorine electrode water.

[0061] More preferably, the anion exchange membrane 20 of the negative electrode chamber 1 is adjacent to the concentrated water chamber 3, and at this time, the influent NEI of the negative electrode chamber 1 is ultrapure water.

[0062] Regarding this problem, the analysis is as follows: In the existing electrodialysis demineralization components, a fresh water chamber is usually adjacent to the negative electrode chamber, and the water inlet of the negative electrode chamber is usually the feed water for electrodialysis demineralization. Due to the electro-migration effect, the cations in the fresh water chamber adjacent to the negative electrode chamber are migrated into the negative electrode chamber. Coupled with the inherent cations in the feed water of the negative electrode chamber, the cation concentration in the negative electrode chamber is significantly greater than that in the feed water for electrodialysis demineralization.

[0063] The main electrochemical reactions in the negative electrode chamber are:

[0064] 2H + +2e - →H 2

[0065] 2Na + +2H 2 O+2e - →H 2 +2NaOH

[0066] Ca 2+ +2H 2 O+2e - →H 2 +Ca(OH) 2

[0067] Mg 2+ +2H 2 O+2e - →H 2 +Mg(OH) 2

[0068] 2H 2 O+2e-→H 2 +2OH -

[0069] Therefore, the water outlet of the negative electrode is strongly alkaline and contains concentrated calcium and magnesium ions. The tendency of calcium and magnesium ions to scale in the alkaline environment of the negative electrode chamber is obvious. Once solid dirt is generated, the water flow in the negative electrode chamber loses uniformity. The long-term accumulation of such scaling will cause insufficient heat dissipation in the negative electrode chamber and lead to burnout accidents.

[0070] The best solution in the prior art to solve this problem is to separately set up the inlet and / or outlet pipelines for the electrode water in order to detect the flow rate of the electrode water in real time. When the flow rate significantly decreases, the negative electrode chamber is cleaned in a timely manner. The best solution for real-time detection of the electrode water flow rate is to detect the inlet of the electrode water because the outlet of the electrode water contains a mixed explosive gas of hydrogen, chlorine, and oxygen, making it difficult to detect the flow rate and posing an obstacle to the discharge of the explosive gas. However, even when detecting the inlet of the electrode water, there are still problems such as lag and the need to stop the machine to clean the negative electrode chamber.

[0071] However, this application adopts the solution of "placing the anion exchange membrane 20 of the negative electrode chamber 1 adjacent to the anion exchange membrane of the concentrated water chamber 3, and at this time, the influent NEI of the negative electrode chamber 1 is ultrapure water". Because the presence of the anion exchange membrane 20 prevents cations such as calcium, magnesium, and sodium from entering the negative electrode chamber 1 through electromigration, and since the influent NEI of the negative electrode chamber 1 is ultrapure water, the cation concentration therein is very low. Therefore, the electrochemical process in the negative electrode chamber 1 is simplified, and its products are hydrogen and hydroxide ions:

[0072] 2H 2 O+2e - →H 2 +2OH -

[0073] The hydroxide ions participate in conduction equivalently and are migrated to the adjacent concentrated water chamber 3. Therefore, the water in the negative electrode chamber 1 is approximately neutral; at the same time, due to the absence of calcium and magnesium ions entering, the possibility of scaling in the negative electrode chamber 1 is greatly reduced.

[0074] Preferably, the ultrapure water used for the influent PEI of the positive electrode chamber 4 and the influent NEI of the negative electrode chamber 1 is the effluent DO of the fresh water chamber 2.

[0075] Preferably, the ultrapure water used for the influent PEI of the above positive electrode chamber 4 is the effluent DO of the fresh water chamber 2, and preferably, the ultrapure water used for the influent NEI of the negative electrode chamber 1 is the effluent DO of the fresh water chamber 2.

[0076] Common electro-deionization components are used to prepare ultrapure water. The resistivity of the fresh water effluent DO is generally greater than 15 MΩ·cm (broadly speaking, the resistivity of ultrapure water is greater than 1 MΩ·cm, usually greater than 15 MΩ·cm, and specifically greater than 18 MΩ·cm). Recycling the effluent DO of the fresh water chamber 2 can not only save resources but also have no adverse impact on the normal operation of the device.

[0077] Preferably, the effluent PEO of the positive electrode chamber 4 and the effluent NEO of the negative electrode chamber 1 are combined into the electrode water effluent EO; or, the effluent PEO of the positive electrode chamber 4, the effluent NEO of the negative electrode chamber 1, and the effluent CO of the concentrated water chamber 3 are combined into the drain RO.

[0078] Preferably, the influent PEI of the positive electrode chamber 4, the influent NEI of the negative electrode chamber 1, and the effluent DO of the fresh water chamber 2 are combined; and / or,

[0079] The influent CI of the concentrated water chamber 3 and the effluent DO of the fresh water chamber 2 are combined.

[0080] Analysis of the external structure problems of the existing electrodeionization device is as follows: The most basic water circuit design of the electrodeionization component is "three inlets and three outlets", that is, interfaces are respectively set for fresh water inlet, fresh water outlet, concentrated water inlet, concentrated water outlet, electrode water inlet, and electrode water outlet. This technical solution is still common and the safest and most reliable, but the pipeline installation is relatively complex. There is an existing technical solution of "two inlets and three outlets" that combines the concentrated water inlet and the electrode water inlet. The disadvantage of this technical solution is that only the flow rate of the electrode water outlet can be detected. However, since the electrode water flow rate is very low and carries explosive gases, a float flowmeter is usually required for detection. And the float flowmeter requires a relatively long flow channel from bottom to top. Therefore, the electrode water usually needs to flow downward first, then flow upward through the float flowmeter, and also needs to pass through a control valve for flow regulation. This poses an obstacle to the smooth evacuation of the mixed explosive gases contained in the electrode water and brings potential safety hazards. There is also an existing technical solution of "two inlets and two outlets" that combines the concentrated water inlet and the electrode water inlet and combines the concentrated water outlet and the electrode water outlet. This technical solution completely makes it impossible to detect the electrode water flow rate, and the electrode water containing oxidizing and explosive gases cannot be separated from the concentrated water with reuse value at all. This is the main reason for the oxidation accident in the reuse of the electrodeionization discharge water, and there is also a hidden danger of the gradual accumulation of explosive gases in the electrodeionization equipment workshop.

[0081] Moreover, the solution provided by this application solves the problem of the oxidizing property of the PEO in the positive electrode chamber 4 effluent and also solves the scaling problem in the negative electrode chamber 1. Therefore, the necessity of real-time control of the electrode water flow rate is greatly reduced. Furthermore, it becomes a feasible technical solution to cancel the separately established electrode water pipeline and the electrode water flow rate detection device.

[0082] Assume that the ultrapure water used as the influent is the DO in the effluent of the fresh water chamber 2. When its resistivity is 15 MΩ·cm (conductivity is 0.067 μS / cm), assume that the conductivity contributed by the ionization of the water for desalination except for the contribution to the conductivity (0.055 μS / cm) is all contributed by sodium chloride. Converted to the chloride ion concentration, it is about 0.0034 ppm. Even if all these chloride ions are electrolyzed into chlorine gas, the chlorine gas concentration in the PEO effluent of the positive electrode chamber is about 0.0034 ppm. As mentioned above, the CO flow rate of the concentrated water effluent of a large electrodeionization component is usually 20 times the PEO flow rate of the positive electrode chamber effluent. Therefore, the chlorine gas concentration in the RO drainage of the electrodeionization component including the PEO effluent of the positive electrode chamber, the NEO effluent of the negative electrode chamber, and the CO effluent of the concentrated water is about 0.00017 ppm. The electrodeionization component drainage is usually mixed with about 10 times the raw water during reuse. After mixing, the chlorine gas concentration from the PEO effluent of the positive electrode chamber of the electrodeionization component is reduced to below 0.00002 ppm (0.02 ppb). The oxidizing property of chlorine gas at this concentration to the membrane and ion exchange resin can be completely ignored. Therefore, from the perspective of reusing the electrodeionization component drainage, there is no need to set up a separate electrode water drainage pipeline, and the electrode water drainage pipeline can be merged with the concentrated water outlet pipeline inside the electrodeionization component.

[0083] Therefore, in the present application, the PEO discharged from the positive electrode chamber 4 and the NEO discharged from the negative electrode chamber 1 can be combined into the electrode water effluent EO; or, the PEO discharged from the positive electrode chamber 4, the NEO discharged from the negative electrode chamber 1, and the CO discharged from the concentrated water chamber 3 can be combined into the drainage RO.

[0084] Furthermore, the PEI fed into the positive electrode chamber 4, the NEI fed into the negative electrode chamber 1, and the DO discharged from the fresh water chamber 2 can be combined, and the electrode water inlet EI interface in the prior art can be cancelled. The CI fed into the concentrated water chamber 3 and the DO discharged from the fresh water chamber 2 can be combined, and the concentrated water inlet CI interface in the prior art can be cancelled.

[0085] When the PEO discharged from the positive electrode chamber 4, the NEO discharged from the negative electrode chamber 1, and the CO discharged from the concentrated water chamber 3 are combined into the drainage RO, and the PEI fed into the positive electrode chamber 4, the NEI fed into the negative electrode chamber 1, and the DO discharged from the fresh water chamber 2 are combined, and the CI fed into the concentrated water chamber 3 and the DO discharged from the fresh water chamber 2 are combined, the concentrated water effluent CO interface and the electrode water effluent EO interface in the prior art are combined, thus realizing the most simplified external structure of the electrodialysis demineralization component of "one inlet and two outlets", and at the same time, the technical problems of electrode water oxidation and electrode chamber scaling can be solved.

[0086] The above combination is achieved by connecting the corresponding pipelines.

[0087] Preferably, the water flow directions of the fresh water chamber 2 and the concentrated water chamber 3 are opposite; and / or,

[0088] the water flow directions of the fresh water chamber 2 and the negative electrode chamber 1 are opposite; and / or,

[0089] the water flow directions of the fresh water chamber 2 and the positive electrode chamber 4 are opposite.

[0090] In the present application, setting the water flow directions of the fresh water chamber 2 and the concentrated water chamber 3 to be opposite can significantly reduce the possibility of scaling in the concentrated water chamber. Setting the water flow directions of the fresh water chamber 2 and the negative electrode chamber 1 to be opposite is beneficial to simplifying the internal structure of the electrodialysis demineralization component. Setting the water flow directions of the fresh water chamber 2 and the positive electrode chamber 4 to be opposite is also beneficial to simplifying the internal structure of the electrodialysis demineralization component, which is convenient for the installation and fixation of structures such as pipelines. When the above three water flow directions are all opposite, the effect is better and the pipeline structure is more simplified.

[0091] Preferably, the channel of the DO discharged from the fresh water chamber 2 turns back inside the device, so that the interface of the DO discharged from the fresh water chamber 2 and the interface of the DI fed into the fresh water chamber 2 are located on the same side of the device.

[0092] Preferably, the channel of the DO discharged from the fresh water chamber 2 turns back inside the device, so that the interface of the DO discharged from the fresh water chamber 2 and the interface of the DI fed into the fresh water chamber 2 are located on the same side of the device, so as to facilitate the pipeline connection of the electrodialysis demineralization device.

[0093] Preferably, the negative electrode chamber 1 further includes a negative electrode insulating plate 12, and the negative electrode insulating plate 12 is arranged on the side of the negative electrode 11 away from the diaphragm;

[0094] The positive electrode chamber 4 further includes a positive electrode insulating plate 42, which is disposed on the side of the positive electrode 41 away from the diaphragm.

[0095] On the side of the negative electrode insulating plate 12 away from the negative electrode 11, there is further provided a negative electrode pressing plate 13.

[0096] On the side of the positive electrode insulating plate 42 away from the positive electrode 41, there is further provided a positive electrode pressing plate 43.

[0097] Preferably, the positive electrode end and the negative electrode end respectively have the structure of an insulating plate and a pressing plate, and are connected by means well known in the art such as bolts and screws.

[0098] Preferably, there is further provided a negative electrode frame plate between the negative electrode 11 and the adjacent diaphragm, and a positive electrode frame plate between the positive electrode 41 and the adjacent diaphragm.

[0099] A fresh water frame plate is provided between the anion exchange membrane 20 and the cation exchange membrane 30 in the fresh water chamber 2, and a concentrated water frame plate is provided between the anion exchange membrane 20 and the cation exchange membrane 30 in the concentrated water chamber 3.

[0100] The negative electrode frame plate, the positive electrode frame plate, the fresh water frame plate and the concentrated water frame plate are connected to the water distribution pipeline.

[0101] Preferably, structures such as the negative electrode frame plate, the positive electrode frame plate, the fresh water frame plate and the concentrated water frame plate are provided to separate the negative electrode 11, the positive electrode 41 and the diaphragm, etc. Each frame plate is also used to connect the corresponding water distribution pipeline.

[0102] Preferably, an ion conductor is optionally filled in the negative electrode chamber 1, the fresh water chamber 2, the concentrated water chamber 3 and the positive electrode chamber 4.

[0103] Preferably, an ion conductor is optionally filled in the negative electrode chamber 1, the fresh water chamber 2, the concentrated water chamber 3 and the positive electrode chamber 4. The ion conductor is preferably an anion exchange resin, a cation exchange resin or a mixed ion exchange resin. Common anion exchange resins, cation exchange resins or mixed ion exchange resins in the art can be used for filling, and there is no special limitation in this application.

[0104] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An electric desalination device for low-chlorine polar water, characterized in that: The invention comprises a negative electrode (11), a positive electrode (41), a plurality of anion exchange membranes (20) and a plurality of cation exchange membranes (30), The anion exchange membrane (20) and the cation exchange membrane (30) are alternately located between the negative electrode (11) and the positive electrode (41), and the membrane sheet adjacent to the positive electrode (41) is the cation exchange membrane (30); A negative electrode chamber (1) is formed between the negative electrode (11) and the adjacent membrane, a positive electrode chamber (4) is formed between the positive electrode (41) and the adjacent membrane, and a fresh water chamber (2) and a concentrated water chamber (3) are alternately formed between adjacent membranes; The positive electrode chamber (4) is adjacent to the concentrated water chamber (3), and the inlet water PEI of the positive electrode chamber (4) is ultrapure water.

2. The electric desalination device according to claim 1, characterized in that: The negative electrode chamber (1) is closely adjacent to the anion exchange membrane (20) of the concentrated water chamber (3), and the inlet water NEI of the negative electrode chamber (1) is ultrapure water.

3. The electric desalination device according to any one of claims 1 to 2, characterized in that: The ultrapure water used for the inlet water PEI of the positive electrode chamber (4) and the inlet water NEI of the negative electrode chamber (1) is the outlet water DO of the fresh water chamber (2).

4. The electric desalination device according to claim 2, characterized in that: The effluent PEO from the positive electrode chamber (4) and the effluent NEO from the negative electrode chamber (1) are combined into the effluent EO; or, the effluent PEO from the positive electrode chamber (4), the effluent NEO from the negative electrode chamber (1) and the effluent CO from the concentrated water chamber (3) are combined into the effluent RO.

5. The electric desalination device according to claim 2, characterized in that: The inlet water PEI of the positive electrode chamber (4), the inlet water NEI of the negative electrode chamber (1) and the outlet water DO of the fresh water chamber (2) are combined; and / or, The inlet water CI of the concentrated water chamber (3) and the outlet water DO of the fresh water chamber (2) are combined.

6. The electric desalination device according to any one of claims 1 to 2, characterized in that: The water flow directions in the fresh water chamber (2) and the concentrated water chamber (3) are opposite; and / or, The water flow directions in the fresh water chamber (2) and the negative electrode chamber (1) are opposite; and / or, The water flow directions in the fresh water chamber (2) and the positive electrode chamber (4) are opposite.

7. The electric desalination device according to claim 6, characterized in that: The channel of the water outlet DO of the fresh water chamber (2) is folded back inside the device, so that the interface of the water outlet DO of the fresh water chamber (2) and the interface of the water inlet DI of the fresh water chamber (2) are located on the same side of the device.

8. The electric desalination device according to claim 1, characterized in that: The negative electrode chamber (1) further comprises a negative electrode insulating plate (12), wherein the negative electrode insulating plate (12) is arranged on a side of the negative electrode (11) away from the diaphragm; The positive electrode chamber (4) further comprises a positive electrode insulating plate (42), wherein the positive electrode insulating plate (42) is arranged on a side of the positive electrode (41) away from the diaphragm; A negative electrode pressing plate (13) is also provided on the side of the negative electrode insulating plate (12) away from the negative electrode (11); A positive electrode pressing plate (43) is also provided on the side of the positive electrode insulating plate (42) away from the positive electrode (41).

9. The electric desalination device according to claim 8, characterized in that: A negative electrode frame plate is provided between the negative electrode (11) and the adjacent membrane, and a positive electrode frame plate is provided between the positive electrode (41) and the adjacent membrane; A fresh water frame plate is provided between the anion exchange membrane (20) and the cation exchange membrane (30) in the fresh water chamber (2), and a concentrated water frame plate is provided between the anion exchange membrane (20) and the cation exchange membrane (30) in the concentrated water chamber (3); The negative electrode frame plate, the positive electrode frame plate, the fresh water frame plate and the concentrated water frame plate are connected to the water distribution pipeline.

10. The electric desalination device according to any one of claims 1-2, 4-5, 7-9, characterized in that: Ion conductors are optionally filled into the negative electrode chamber (1), the fresh water chamber (2), the concentrated water chamber (3) and the positive electrode chamber (4).

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