CN212269733U - Electrodialysis device for preventing polar water system from scaling by adopting directional driving technology - Google Patents
Electrodialysis device for preventing polar water system from scaling by adopting directional driving technology Download PDFInfo
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- CN212269733U CN212269733U CN202021850292.5U CN202021850292U CN212269733U CN 212269733 U CN212269733 U CN 212269733U CN 202021850292 U CN202021850292 U CN 202021850292U CN 212269733 U CN212269733 U CN 212269733U
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Abstract
The utility model relates to an electrodialysis device which adopts the directional driving technology to prevent the scaling of an electrode water system, comprising an electrodialysis reactor, a fresh water tank, a concentrated water tank and an electrode water tank; the electrodialysis reactor is formed by assembling an anode plate, a membrane stack and a cathode plate in sequence; wherein the arrangement mode of the membrane stack is sequentially (C-A2)n-C1, n is a natural number of 1-2000, and n fresh water channels, n concentrated water channels and 2 polar water channels are formed and are separated from each otherArranging; wherein: c1 refers to monovalent selective cation exchange membrane, C refers to common selective cation exchange membrane, a2 refers to common selective anion exchange membrane; the concentrated water tank, the concentrated water pump, the concentrated water filter and the membrane pile concentrated water channel are sequentially connected to form a concentrated water circulation passage. The utility model has the advantages that: utilize the utility model provides an electrodialysis reactor handles and contains salt waste water, can reduce the concentration of bivalent positive ion (mainly calcium ion and magnesium ion) in the polar water by a wide margin to reduce the negative plate scale deposit tendency.
Description
Technical Field
The utility model belongs to the technical field of the environmental protection water treatment, concretely relates to adopt directional drive technique to prevent electrodialysis device of utmost point water system scale deposit.
Background
With the rapid development of modern socioeconomic, the industrial production level is rapidly improved, and the problem of water pollution is increasingly serious. In recent years, with the successive promulgation and implementation of regulations such as "energy saving law" and "environmental protection law", the national requirements for water consumption, water discharge and water quality of discharged water of enterprises are becoming more and more strict, so that the reduction of wastewater discharge and the realization of wastewater resource utilization become important subjects in the field of water treatment.
Electrodialysis is a method of separating different ions by the permselectivity of ion exchange membranes under the action of an electric field. And cations and anions in the fresh water chamber pass through the selective membrane and are enriched in the concentrated water chamber, so that recyclable fresh water with low salt content and concentrated water with high salt content are obtained, and the separation of ions in water is realized. The electrodialysis technology has the advantages of high efficiency, cleanness, energy conservation, low cost and the like, and is widely applied to industries such as chemical metallurgy, light industry, papermaking, pharmaceutical industry and the like.
In the operation process of the electrodialysis device, certain polar water circulation operation needs to be configured,the polar water is generally sodium chloride solution prepared by deionized water without hardness. The cathode of the electrodialysis unit inevitably produces a large amount of OH during operation-Meanwhile, part of calcium and magnesium ions also migrate to an extreme water system during the operation process to further form Mg (OH)2、Ca(OH)2And the precipitates can be deposited at the polar plates or on the walls of polar water pipes, so that the resistance of the polar plates is increased, the current efficiency is reduced, the polar plates are overheated, polar water flow channels are blocked, and the like, and the safe operation of the electrodialysis system is seriously threatened. These precipitates can further cause electrode corrosion, destruction of electrode surface structure, thereby reducing the desalination efficiency of the system and increasing the overall energy consumption.
For a common electrodialysis system (CAC type, as shown in figure 3), cation exchange occurs between polar water and wastewater in the electrodialysis treatment process, divalent cations in the wastewater migrate into the polar water, and scaling occurs on a cathode plate after the electrodialysis system operates for a period of time, so that the current efficiency is reduced, and the wastewater concentration effect is influenced. Common anti-plate fouling strategies include: acid washing, periodic polar water discharge, acid addition to reduce the pH value of the polar water and the like. Thereby causing the problem of large demand of hydrochloric acid medicament, and having the defects of environmental pollution, complex operation, poor safety and the like of pickling waste water.
Therefore, there is a need to develop a novel electrodialysis reactor, which can avoid the large enrichment of calcium ions and magnesium ions in the polar water channel, thereby reducing the scaling tendency of the polar water system and ensuring the long-term reliable operation of the electrodialysis system.
SUMMERY OF THE UTILITY MODEL
The utility model discloses to the problem of the easy scale deposit of negative plate in the transmission of electricity in-process among the current electrodialysis technique, provide an adopt directional drive technique to prevent the electrodialysis device of utmost point water system scale deposit.
The electrodialysis device for preventing the scaling of the polar water system by adopting the directional driving technology comprises an electrodialysis reactor, a fresh water tank, a concentrated water tank and a polar water tank; the electrodialysis reactor is formed by assembling an anode plate, a membrane stack and a cathode plate in sequence; wherein the arrangement mode of the membrane stack is sequentially (C-A2)n-C1, n is a natural number of 1-2000, forming n fresh water channels, n concentrate channels and 2 polesThe water channels, the fresh water channels and the concentrated water channels are arranged at intervals; wherein: c1 refers to monovalent selective cation exchange membrane, C refers to common selective cation exchange membrane, a2 refers to common selective anion exchange membrane; the concentrated water tank, the concentrated water pump, the concentrated water filter and the membrane pile concentrated water channel are sequentially connected to form a concentrated water circulation passage; the fresh water tank, the fresh water pump, the fresh water filter and the membrane stack fresh water channel are sequentially connected to form a fresh water circulation passage; the polar water tank, the polar water pump, the polar water filter and the membrane stack polar water channel are sequentially connected to form a polar water circulation passage.
Preferably, the method comprises the following steps: the two sides of each membrane are respectively provided with a supporting clapboard, and the upper end and the lower end of the clapboard are respectively provided with a water flow hole and a communicating hole.
The utility model has the advantages that:
1. utilize the utility model provides an electrodialysis reactor handles and contains salt waste water, can reduce the concentration of divalent cation (mainly calcium ion and magnesium ion) in the polar water by a wide margin to reduce negative plate scale deposit tendency, slow down the scale deposit speed of calcium magnesium scale in the negative plate, reduce the pickling frequency.
2. The utility model discloses reduce the scale deposit of negative plate among the system operation process, can reduce electrode resistance, reduce the heat conversion of electric energy, improve electrodialysis ion migration efficiency (current efficiency promptly), promote the separation effect of the waste water ion that contains salt.
3. The utility model discloses system low cost, simple structure, almost no adverse effect to the suitability is strong, can be used for handling not softened industrial waste water, and the complicacy of different quality of water contains salt waste water in each trade.
Drawings
FIG. 1 is a structural and schematic diagram of an electrodialysis reactor employing directional drive techniques to prevent scaling in the polar water system;
FIG. 2 is a process flow diagram of an anti-scaling electrodialysis wastewater treatment system;
fig. 3 is a schematic diagram of a structure of a general electrodialysis reactor (CAC type).
Detailed Description
The present invention will be further described with reference to the following examples. The following description of the embodiments is merely provided to aid in understanding the invention. It should be noted that, for those skilled in the art, without departing from the principle of the present invention, the present invention can be further modified and modified, and such modifications and modifications also fall within the protection scope of the appended claims.
As shown in fig. 1, the electrodialysis reactor of the present invention is formed by assembling an anode plate, a membrane stack and a cathode plate in sequence. Wherein the arrangement mode of the membrane stack is sequentially (C-A2)nAnd the-C1, n is a natural number of 1-2000, and n fresh water channels, n concentrated water channels and 2 polar water channels are formed and are arranged at intervals. Wherein: c1 refers to a monovalent selective cation exchange membrane oriented to allow only monovalent cations to pass through, not more than divalent cations and all anions to pass through; c refers to a common selective cation exchange membrane, allowing cations of any valence state to pass through; a2 refers to a common selective anion exchange membrane. Fig. 1 shows the structure of the electrodialysis reactor and the ion separation effect when n is 3, a2 is a general selective anion exchange membrane, C is a general selective cation exchange membrane, and C1 is a monovalent selective cation exchange membrane.
And supporting partition plates are arranged on two sides of each membrane, so that the effects of supporting protection and shunting are mainly achieved. The upper end and the lower end of the clapboard are respectively provided with a water flow hole and a communication hole which can fix the water flow direction, so that all the fresh water channels and the external fresh water tank form circulation, all the concentrated water channels and the external concentrated water tank form circulation, and two polar water channels and the external polar water tank form circulation.
When the electrodialysis reactor is used for treating salt-containing wastewater, the polar water in the polar water channel is about 3% of sodium chloride solution, deionized water is used for preparing the polar water, and the hardness of the prepared polar water is not more than 10 mg/L.
In particular, due to the existence of the polar water channel monovalent selective cation exchange membrane, only monovalent cations are allowed to be driven directionally, ions above divalent are not allowed to pass through, divalent cations (mainly calcium ions and magnesium ions) of a cathode adjacent to a fresh water channel do not migrate to a great amount to the cathode polar water channel, and the rejection rate of the divalent cations exceeds 98%.
In the running process of the polar water system, OH is continuously generated at the cathode-The ions make the cathode water alkaline. However, due to the directional driving effect, no divalent calcium and magnesium ions can migrate to the cathode electrode water, so that hydroxide precipitates of calcium and magnesium cannot be formed.
And the cathode electrode water and the anode electrode water flow out from the electrode water outlet of the electrodialysis reactor, are mixed and then flow back to the electrode water inlet of the electrodialysis reactor in a circulating mode.
The cation membrane of the anode adjacent to the concentrated water channel is a common membrane, and allows the passage of mono-and divalent cations, so that small amount of calcium and magnesium ions migrating to the polar water system also return to the concentrated water system from the channel, thus not causing the enrichment of the calcium and magnesium ions in the polar water system.
As shown in figure 2, the electrodialysis reactor is used for forming a novel electrodialysis wastewater treatment system in a matching way, and can be used for separating ions in water. The system consists of an electrodialysis reactor, a concentrated water tank, a fresh water tank, an electrode water tank, a circulating pump, a filter, a heat exchanger and a matched pipeline valve meter. The concentrated water tank, the concentrated water pump, the concentrated water filter and the membrane pile concentrated water channel jointly form concentrated water circulation. The fresh water tank, the fresh water pump, the fresh water filter and the membrane stack fresh water channel jointly form fresh water circulation. The polar water tank, the polar water pump, the polar water filter and the membrane stack polar water channel jointly form polar water circulation.
The salt-containing wastewater treatment method by using the anti-scaling electrodialysis wastewater treatment system comprises the following steps: respectively placing the salt-containing wastewater in a concentrated water tank and a fresh water tank, and preparing a sodium chloride solution with the mass fraction of 3% as polar water. And simultaneously, starting a concentrated water pump, a fresh water pump and an electrode water pump to start concentrated water circulation, fresh water circulation and electrode water circulation. And after the system runs stably, the system supplies power to the electrodes of the electrodialysis reactor, adjusts the voltage and the current to proper values, and performs ion separation on the wastewater. After a period of time, the ion concentration on the fresh water side is greatly reduced, the ion concentration on the concentrated water side is greatly increased, the treated fresh water can be recycled, and the treated concentrated water can be subjected to subsequent advanced treatment. Adopt the utility model discloses in prevent negative pole scale deposit electrodialysis system (CACACAC 1 type, as shown in fig. 1), the electrodialysis is handled in-process negative pole water and waste water and only takes place monovalent cation exchange, after the operation under the same operating mode, negative plate scale deposit volume reduces to original 5%, and the current efficiency decline degree is lighter when the system moves for a long time.
Example (b):
certain coal fired power plant adopts the utility model discloses a directional drive technique prevents that electrodialysis device of utmost point water system scale deposit from handling desulfurization waste water, and most heavy metal ion has been got rid of through triplex box system preliminary treatment to this desulfurization waste water, but calcium ion, magnesium ion, sulfate ion, chloride ion concentration are higher. The specific water quality conditions are shown in the following table.
TABLE 1 desulfurization waste water quality condition table
The rated treatment flow of the configured system is 10 tons/hour, and the system consists of an electrodialysis reactor, a concentrated water tank, a fresh water tank, an electrode water tank, a circulating pump, a filter, a cooling system, corresponding pipelines and valves. The concentrated water, the fresh water and the polar water form three internal circulations through different channels of the membrane stack respectively. The outlet of the system concentrated water pump is connected with a bypass flue gas drying tower, and the concentrated and reduced desulfurization wastewater concentrated water is subjected to evaporation treatment by the original bypass flue gas evaporation system. An outlet of the fresh water pump is connected with a slurry pond in the desulfurization absorption tower area, and fresh water with high sulfate radical concentration and low chloride ion concentration is discharged and returned to the desulfurization system for resource utilization.
The electrodialysis reactor consists of an anode plate, a membrane stack and a cathode plate. The arrangement mode of the membrane stack is (common selective cation exchange membrane-common selective anion exchange membrane)nMonovalent selective cation exchange membranes, i.e. (C-A2)n-C1, where n is 80, forming a total of 80 spaced fresh water channels and concentrated water channels and 2 outermost polar water channels. Supporting clapboards are arranged between the exchange membranes to ensure the independent and smooth work of the passages of the concentrated water, the fresh water and the polar water. The structure and principle of the electrodialysis reactor in this embodiment are shown in fig. 1.
Three-header system of power plantAnd the desulfurization wastewater in the system outlet settling pond respectively enters a concentrated water tank and a fresh water tank to be used as initial concentrated water and initial fresh water. Analytically pure sodium chloride was used as initial pole water, formulated as a 3% mass fraction sodium chloride solution. Set up electrodialysis reactor voltage for maximum rated voltage, after this system 168 hours of continuous operation, the utility model discloses a novel electrodialysis system utmost point water calcium ion concentration is 38mg/L, magnesium ion concentration is 26mg/L in the utmost point water tank, and calcium magnesium concentration reduces more than 95% than original. And (4) disassembling and checking the surface of the cathode plate to be flat, and no obvious scale is formed. In contrast, after a conventional electrodialysis system (CAC type electrodialysis reactor) used in the past was continuously operated for 168 hours, the calcium ion concentration of the cathode water in the cathode water tank was 2069mg/L, the magnesium ion concentration was 899mg/L, the sulfate ion concentration was 58mg/L, the surface of the cathode plate was covered with a layer of white scale of about 0.5cm, and the scale was analyzed to have a main component of Mg (OH)2And Ca (OH)2Immediate pickling is required. The experiment proves, the utility model discloses a novel electrodialysis system can effectively prevent the negative plate scale deposit, reduces the pickling frequency.
After the anti-scaling electrodialysis system is normally put into operation, the quality of the polar water is qualified during operation, and scaling phenomena are not found in the cathode plate and the polar water system. The results show that the electrodialysis device for preventing the polar water system from scaling by adopting the directional driving technology has good scaling prevention performance.
Claims (2)
1. An electrodialysis device for preventing the scaling of an electrode water system by adopting a directional driving technology is characterized in that: comprises an electrodialysis reactor, a fresh water tank, a concentrated water tank and a polar water tank; the electrodialysis reactor is formed by assembling an anode plate, a membrane stack and a cathode plate in sequence; wherein the arrangement mode of the membrane stack is sequentially (C-A2)n-C1, n is a natural number of 1-2000, forming n fresh water channels, n concentrated water channels and 2 polar water channels, the fresh water channels and the concentrated water channels being arranged at intervals; wherein: c1 refers to monovalent selective cation exchange membrane, C refers to common selective cation exchange membrane, a2 refers to common selective anion exchange membrane; the concentrated water tank, the concentrated water pump, the concentrated water filter and the membrane pile concentrated water channel are sequentially connected to form a concentrated water circulation passage; fresh water tank and fresh waterThe pump, the fresh water filter and the membrane stack fresh water channel are sequentially connected to form a fresh water circulation passage; the polar water tank, the polar water pump, the polar water filter and the membrane stack polar water channel are sequentially connected to form a polar water circulation passage.
2. An electrodialysis unit using directional driving technique to prevent scaling of polar water system according to claim 1, wherein: the two sides of each membrane are respectively provided with a supporting clapboard, and the upper end and the lower end of the clapboard are respectively provided with a water flow hole and a communicating hole.
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| CN111960583A (en) * | 2020-08-28 | 2020-11-20 | 浙江浙能技术研究院有限公司 | Electrodialysis device and method for preventing polar water system from scaling by adopting directional driving technology |
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| CN111960583A (en) * | 2020-08-28 | 2020-11-20 | 浙江浙能技术研究院有限公司 | Electrodialysis device and method for preventing polar water system from scaling by adopting directional driving technology |
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