CN108911059A - A kind of electric dialyzator - Google Patents

Abstract

The invention discloses an electrodialyzer, which comprises an anode plate, a membrane stack, a cathode plate and a pressing plate for fixing and sealing the membrane stack; the membrane stack includes a monovalent selective anion exchange membrane which selectively permeates monovalent anions, Cation exchange membranes and separators for cations and multivalent cations; there are n sheets of monovalent selective anion exchange membranes, n+1 sheets of the cation exchange membranes, and the cation exchange membranes and the monovalent selective anion exchange membranes are pressed The tight plates are alternately arranged; the partition plate includes a middle plate and a support plate, a compartment is provided in the middle of the middle plate, and water flow holes and communication holes arranged at intervals are respectively provided at the upper end and the lower end of the middle plate; the flow channel communicates with the water flow hole and the compartment; the supporting plate on both sides of the middle plate covers the remaining part of the flow channel; this invention can selectively separate and concentrate multivalent anions and multivalent cations that are easy to scale, preventing Scaling of electrodialysis equipment.

Description

an electrodialyzer

technical field

The invention relates to an electrodialyzer, in particular to an electrodialyzer for preventing fouling.

Background technique

With the deteriorating problem of water shortage in our country, the problem of overexploitation of groundwater in northern China is serious. Industrial water is a major user of water resources in my country. my country's long-term plan is to achieve a reuse rate of more than 80% for industrial wastewater, but currently it is generally only about 50%. Therefore, there will be a lot of room for growth in the reuse of industrial wastewater. At the same time, my country's environmental protection policy requires thermal power plants, electroplating, coal chemical industry and other industries to achieve zero discharge of wastewater.

When dealing with saline wastewater, the electrodialyzer has the advantages of high concentration multiple, low operating pressure and high recovery rate. But in many saline wastewater, such as desulfurization wastewater, reverse osmosis concentrated water and circulating cooling tower sewage, etc., the wastewater solution to be treated contains a variety of ions, mainly An ⁺ , ^Bn- , C ⁺ and D ^- , Among them, A ⁿ⁺ represents multivalent cations including calcium ions, magnesium ions, iron ions, copper ions, etc., B ^n- represents multivalent anions such as sulfate ions, phosphate ions, and carbonate ions, and C ⁺ represents sodium ions, potassium ions, etc. , ammonium ions and other monovalent cations, D ^- represents monovalent anions such as chloride ions, nitrate ions, etc. Calcium ions, magnesium ions and sulfate ions, phosphate ions, and carbonate ions are easily combined to form precipitation, which is easy to cause electrodialysis Fouling of equipment.

Contents of the invention

The object of the present invention is to provide an electrodialyzer, which can selectively separate and concentrate multivalent anions and multivalent cations that are easy to scale, so as to prevent fouling of electrodialysis equipment.

In order to solve this technical problem, the technical solution of the present invention is: an electrodialyzer comprising an anode plate, a membrane stack, a cathode plate and a compression plate for fixing and sealing the membrane stack; A monovalent selective anion exchange membrane, a cation exchange membrane and a separator through which monovalent cations and multivalent cations pass; there are n sheets of monovalent selective anion exchange membranes, and n+1 sheets of the cation exchange membranes, the cation exchange membranes and The monovalent selective anion exchange membranes are arranged alternately between the compression plates;

The partition includes a middle plate and support plates on both sides of the middle plate, a compartment covered with a mesh is provided in the middle of the middle plate, and water flow holes and communication holes arranged at intervals are respectively provided at the upper end and the lower end of the middle plate ; the middle plate is provided with a flow channel communicating with the water flow hole and the compartment; the middle of the support plate is provided with a first hole communicating with the compartment; the upper end and the lower end of the support plate are corresponding to the The position of the water flow hole and the communication hole is respectively provided with a corresponding second hole, the end of the flow channel facing the communication hole is located between the second holes on both sides, and the two sides of the middle plate The support plate covers the remainder of its said flow channel.

As a further improvement, a set of flow channels is provided between each of the communication holes on the intermediate plate and the compartment, and each set of flow channels is radially distributed toward the compartment. Due to the supporting effect of the support plate, it is possible to avoid the crossing of the flow passages of two adjacent partitions in the membrane pair to generate pressure on the ion exchange membrane in the middle of the two partitions, thereby avoiding the ion exchange membrane at the intersection of the flow passages on both sides. Indentations are produced on the sides, so the setting of the flow channels of the three-layer sandwich structure is not limited by the flow channels of two adjacent separators that cannot cross, that is, the flow channels of two adjacent separators can cross each other. Therefore, the water entering the concentrated chamber or the dilute chamber can evenly enter and exit the water, reduce the polarization phenomenon, improve the efficiency of ion grouping, and reduce the possibility of scaling; on the other hand, the cation exchange membrane and the monovalent selective anion The exchange membrane can be protected by the support plate to reduce the occurrence of indentation. The three-layer sandwich structure partition between the two ensures that the ion exchange membrane in the present invention is effectively protected. It has uniform water distribution and prevents dead zones. While appearing, it also has the characteristics of reliable use and long service life.

As a further improvement, the turning point of each of the flow channels from the compartment to its corresponding communication hole is in the shape of an arc with a radius of 5 to 10 mm. The smooth flow channel is designed in an arc shape at the corner. The smooth flow channel reduces the water flow resistance, and at the same time, it can also reduce the blockage of the flow channel caused by the precipitation of particles in the water.

As a further improvement, one end of each group of flow passages on both sides of the compartment connected to the compartment is evenly distributed on the middle plate, and the other end of the flow passages connected to the communication hole is evenly distributed on the middle plate on the middle plate. Further uniform distribution of flow channels on the water inlet or outlet side of the compartment makes the water distribution of the compartment more uniform and prevents dead space in the compartment.

As a further improvement, the communication holes located at the lower end of each intermediate plate and the communication holes located at the upper end of the intermediate plate are alternately arranged; between two adjacent communication holes located on the same side of the intermediate plate are A water hole. Through the above settings, each block can ensure that the concentrated water or fresh water in the compartment can fully flow and prevent the generation of dead zones.

Preferably, the width of each of the flow channels is equal, the width of each flow channel is 0.5 to 2.5 mm, and the number of flow channels corresponding to each of the communication holes is 5 to 15; the thickness of the middle plate is 0.3 to 1 mm; The thickness of the support plate is 0.15 to 0.5 mm. By adjusting the number of flow channels and the thickness of the intermediate plate, it is ensured that the total cross-sectional area of the flow channels corresponding to each of the communication holes is 5 to 12 mm ² . Combining the selected width of the flow channel and the thickness of the support plate to ensure that the support plate does not produce obvious indentations at the flow channel under the pressure of 0.5Mpa.

By adopting the above-mentioned technical scheme, the beneficial effects of the present invention are: in the present invention, by repeatedly setting the cation-exchange membrane-separator-separator-selectively permeating the monovalent selective anion-exchange membrane-separator of monovalent anions The two partitions are stacked in two forms, and the compartments of the two partitions are respectively a concentrated chamber and a dilute chamber; the present invention converts A ⁿ⁺ , B ^n- , C ⁺ and D ^- (A ⁿ⁺ represents multivalent cations including calcium ions, magnesium ions, iron ions, copper ions, etc., B ^n- represents multivalent anions such as sulfate ions, phosphate ions, and carbonate ions, and C ⁺ represents such as sodium ions, potassium ions, etc. ions, ammonium ions and other monovalent cations, D ^- represents monovalent anions such as chloride ions and nitrate ions, among which calcium ions, magnesium ions and sulfate ions, phosphate ions, and carbonate ions are easy to scale,) for separation , the concentrated chamber concentrates A ^{n+ ,} C ⁺ and D ^- in the dilute chamber on both sides, and An+, C ⁺ and D ^- in the dilute chamber pass through the cation exchange membrane and the monovalent selective anion exchange membrane on both sides respectively Entering the concentrated chambers on both sides, because the B ^n- in the dilute chamber cannot pass through the ion exchange membranes on both sides into the concentrated chamber, thus realizing the separation of B ^n- and A ⁿ⁺ , the formation in the concentrated chamber is easy to scale The ion composition form composed of mixed cations and monovalent anions in various valence states in non-toxic wastewater is not easy to scale, that is, the selective separation and concentration of A ⁿ⁺ and B ^n- that are easy to scale are realized; the combination of the above membrane pairs Cooperate with the structure of the partition, the communication hole at the upper end of the middle plate and the second holes on both sides corresponding to the communication hole constitute the water outlet or water inlet hole of the partition; the communication hole at the lower end of the middle plate And the second hole on both sides corresponding to the communication hole constitutes the water inlet or outlet hole of the partition; the flow channel at the upper or lower end of the middle plate points to the corresponding communication hole. One end is located between the second holes of the support plates on both sides; the remaining part of the flow channel is covered by the support plates on both sides. In the present invention, by setting the partition plate as a three-layer sandwich structure, that is, the middle plate in the middle and the support plates on both sides of the middle plate, the support plates cover the flow channels on the middle plate to prevent the cation exchange membrane and the unit price selectivity. The anion exchange membrane sinks into the flow channel under the action of fluid pressure, on the one hand to prevent the flow channel from being blocked, on the other hand it can also prevent the water flow from being blocked after the flow channel is blocked, resulting in slow thermal diffusion and film burning; the present invention can not only realize selectivity Concentration and separation of ions that are easy to scale and the effect of selective separation and concentration are good; the invention also has the characteristics of reliability, safety and long service life.

Thereby realize above-mentioned purpose of the present invention.

Description of drawings

Fig. 1 is the structural representation of a kind of electrodialyzer that the present invention relates to;

Fig. 2 is a schematic diagram of the principle of the present invention;

Fig. 3 is the partial enlarged view of dividing plate in the present invention;

Fig. 4 is the structural representation of middle plate among the present invention;

Fig. 5 is a structural schematic diagram of a support plate in the present invention.

In the picture:

Membrane stack 100; compression plate 2; monovalent selective anion exchange membrane 3; cation exchange membrane 4; separator 5; middle plate 51; compartment 511; Support plate 52 ; first hole 521 ; second hole 522 .

Detailed ways

In order to further explain the technical solution of the present invention, the present invention will be described in detail below through specific examples.

The invention discloses an electrodialyzer, as shown in Figures 1 to 5, comprising an anode plate, a membrane stack 100, a cathode plate, and a pressing plate 2 for fixing and sealing the membrane stack 100; the membrane stack 100 includes a selectively permeable A monovalent selective anion exchange membrane 3 for monovalent anions, a cation exchange membrane 4 and a separator 5 through which monovalent cations and multivalent cations pass; the number of monovalent selective anion exchange membranes 3 is n, and the cation exchange membrane 4 is n+1 Zhang, the cation exchange membranes 4 and the monovalent selective anion exchange membranes 3 are alternately arranged between the compression plates 2;

The partition plate 5 includes a middle plate 51 and support plates 52 on both sides of the middle plate 51. The middle part of the middle plate 51 is provided with a compartment 511 covered with a mesh 515. The upper end and the lower end of the middle plate 51 are respectively provided with Water flow holes 512 and communication holes 513 arranged at intervals; the middle plate 51 is provided with a flow channel 514 communicating with the water flow holes 512 and the compartment 511; The same first hole 521 as the compartment 51; the upper end and the lower end of the support plate 52 are respectively provided with corresponding second holes 522 at positions corresponding to the water flow hole 512 and the communication hole 513, and the flow channel 514 One end facing the communication hole 513 is located between the second holes 522 on both sides thereof, and the support plates 52 on both sides of the middle plate 51 cover the rest of the flow channel 514 thereof. In the present embodiment, the cation exchange membrane 4-partition 5-monovalent selective anion exchange membrane 3-partition 5 is set repeatedly, and the compartments 511 of the two partitions 5 are respectively a concentrated chamber and a light chamber; in this embodiment A ⁿ⁺ , B ^n- , C ⁺ and D ^- in the wastewater to be treated (wherein A ⁿ⁺ represents multivalent cations including calcium ions, magnesium ions, iron ions, copper ions, etc., B ^n- represents sulfate ions, phosphate ions, carbonate ions and other polyvalent anions, C ⁺ represents monovalent cations such as sodium ions, potassium ions, ammonium ions, etc., D ^- represents monovalent anions such as chloride ions, nitrate ions, etc., calcium ions, magnesium ions and sulfate ions , phosphate ions, and carbonate ions are prone to scaling,) for separation, the concentrated chamber concentrates An ⁺ , C ⁺ and D ^- in the light chambers on both sides, ^and An ⁺ , C ⁺ and D in the light chambers ^-permeate from the cation exchange membrane 4 on both sides and the monovalent selective anion exchange membrane 3 into the concentrated chambers on both sides, because the ^Bn in the light chamber cannot permeate from the ion exchange membranes on both sides and enter the concentrated chambers In this way, the separation of B ^n- and A ⁿ⁺ is realized, and the ion composition form composed of mixed cations and monovalent anions in various valence states in the fouling-prone wastewater is formed in the concentrated chamber, which is not easy to scale. A ⁿ⁺ and B ^n- of the scale are selectively separated and concentrated; the matching of the above-mentioned membrane pair matches the structure of the separator 5, the communication hole 513 on the upper end of the middle plate 51 and the two sides of the corresponding position of the communication hole 513 The second hole 522 forms the water outlet hole or the water inlet hole of the dividing plate 5; the communicating hole 513 at the lower end of the intermediate plate 51 and the second holes 522 on both sides corresponding to the communicating hole 513 form the dividing plate 5 water inlet or water outlet holes; the flow channel 514 located at the upper or lower end of the middle plate 51 points to the corresponding communication hole 513 and one end is located at the second hole 522 of the support plate 52 on both sides Between; the remaining part of the flow channel 514 is covered by the support plates 52 on both sides. In the present invention, by setting the partition plate 5 as a three-layer sandwich structure, that is, the intermediate plate 51 in the middle and the supporting plates 52 positioned on both sides of the intermediate plate 51, the supporting plates 52 cover the flow channels 514 on the intermediate plate 51 to prevent The cation exchange membrane 4 and the monovalent selective anion exchange membrane 3 are recessed in the flow channel 514, on the one hand to prevent the flow channel 514 from being blocked, and on the other hand to prevent the water flow from being blocked after the flow channel 514 is blocked, resulting in slow thermal diffusion and membrane burning; The invention not only can realize the selective separation and concentration of easily scaled ions, but also has good selective separation and concentration effect; the invention also has the characteristics of reliability, safety and long service life.

In this embodiment, a set of flow channels 514 is provided between each communication hole 513 of the intermediate plate 51 and the compartment 511 , and each set of flow channels 514 is distributed radially toward the compartment 511 . Due to the supporting effect of the supporting plate 52, it is possible to prevent the flow channels 514 of the two adjacent separators 5 from intersecting to generate pressure on the ion-exchange membrane between the two separators 5, thereby preventing the ion-exchange membrane from flowing on both sides. The side surfaces at the crossing of the channels 514 are pressed by the separators 5 with flow channels 514 to produce indentations, so the arrangement of the separators 5 with the flow channels 514 of the three-layer sandwich structure is not affected by the flow channels 514 of two adjacent separators 5. The limitation that cannot cross, that is, the flow channels 514 of two adjacent partitions 5 can be crossed and reattached to each other, so the water entering the concentrated chamber or the dilute chamber can evenly enter and exit the water, reduce the polarization phenomenon, and improve the ion density. The efficiency of grouping reduces the possibility of fouling; on the other hand, both the cation exchange membrane 4 and the monovalent selective anion exchange membrane 3 can be protected by the support plate 52, reducing the occurrence of indentations, and between the two due to the three-layer sandwich structure The partition plate 5 ensures that the ion exchange membrane in the present invention is effectively protected, and has the characteristics of reliable use and long life while having uniform water distribution and preventing the occurrence of flow dead zones.

In this embodiment, each flow channel 514 turns from the compartment 511 to the corresponding communication hole 513 in an arc shape, and the radius of the arc is 5 to 10 mm. The smooth flow channel 514 is designed in an arc shape at the corner, and the smooth flow channel 514 reduces the water flow resistance, and at the same time, it can also reduce the blockage of the flow channel 514 caused by the precipitation of particles in the water.

In this embodiment, one end of each group of flow channels 514 located on both sides of the compartment 511 connected to the compartment 511 is evenly distributed on the middle plate 51, and the flow channels 514 communicate with the communication holes. The other ends of 513 are evenly distributed on the middle plate 51 . Further uniform distribution of the flow channel 514 on the water inlet or outlet side of the compartment 511 makes the water distribution of the compartment 511 more uniform and prevents dead space in the compartment 511 .

In this embodiment, the communication holes 513 at the lower end of each intermediate plate 51 and the communication holes 513 at the upper end of the intermediate plate 51 are alternately arranged. A water flow hole 512 is provided between two adjacent communication holes 513 on the same side of the middle plate 51 . Through the above arrangement, it is ensured that the concentrated water or the fresh water in the compartment 511 can flow sufficiently to prevent the generation of dead zones.

In this embodiment, preferably each of the flow channels 514 has the same width, the width of each flow channel 514 is 0.5 to 2.5mm, and the number of flow channels 514 corresponding to each of the communication holes 513 is 5 to 15; The thickness of the plate 51 is 0.3 to 1 mm; the thickness of the supporting plate 52 is 0.15 to 0.5 mm. By adjusting the number of flow channels 514 and the thickness of the intermediate plate 51 , it is ensured that the total cross-sectional area of the flow channels 514 corresponding to each communication hole 513 is 5 to 12 mm ² . Combined with the width selected for the flow channel 514 , it is ensured that the support plate 52 does not produce obvious indentations at the flow channel 514 under the pressure of 0.5 MPa. Further preferably, the thickness of the support plate 52 in this embodiment is 0.25mm.

Further preferably, the membrane stack 100 in this embodiment contains a total of 201 cation exchange membranes 4 , 200 monovalent selective anion exchange membranes 3 , and 400 separators 5 . The size of the separator 5 and the monovalent selective anion exchange membrane 3 and the cation exchange membrane 4 are both 500mm*1100mm. In this embodiment, the number of the water collecting holes at the upper or lower end of the middle plate 51 is 8; the number of the communication holes 513 at the upper or lower end of the middle plate 51 is 4. In this embodiment, one electrodialyzer is used for intermittent operation, and the water in the water inlet tanks corresponding to the concentrated chamber and the dilute chamber is treated by the electrodialyzer and then flows back to the respective water inlet tanks. 0.45m ³ of pure water treated by reverse osmosis is passed into the water inlet tank corresponding to the concentrated chamber of the electrodialyzer, and the conductivity of the pure water is ^4.3us /cm. The conductivity of wastewater and desulfurization wastewater is 46706us/cm, the content of calcium ions is 4470mg/L, the content of magnesium ions is 3150mg/L, the content of sodium ions is 2275mg/L, the content of chloride ions is 18200mg/L, and the sulfate radical is 3000mg/L. The saturation index is as high as 158%, which is very easy to cause scaling. The water flow rate of the concentrated chamber is 5m ³ /h, and the pressure is 2kpa. The water inlet flow rate of the desalination chamber is 8m ³ /h, and the water inlet pressure is 3kpa. Electrodialysis adopts a constant voltage operation mode, the operating voltage is 150V, and the current range is 40-150A. After running for 70 minutes, the concentrated water and fresh water inlet tanks obtained 0.5m ³ and 1.95m ³ of product water respectively. Sampling and analysis of the produced water in the water inlet tank, the water quality analysis results are: the conductivity of the most produced water in the concentrated water tank is 133947us/cm, the content of calcium ions is 15700mg/L, the content of magnesium ions is 11320mg/L, and the content of sodium ions is 7205mg/L , chloride ion 71819mg/L, sulfate radical 11mg/L. The conductivity of the most produced water in the fresh water tank is 5443us/cm, the calcium ion content is 558mg/L, the magnesium ion content is 328mg/L, the sodium ion content is 485mg/L, the chloride ion is 323mg/L, and the sulfate radical is 3094mg/L. After being treated by the electrodialyzer, the desulfurization wastewater is desalinated, and 1.95m ³ of fresh water is obtained, which can be reused in the desulfurization tower. At the same time, 0.5m3 concentrated water is obtained. ^The concentrated water is mainly in the form of a combination of monovalent anions and multiple valent cations. The sulfate radical is only 11mg/L, and the saturation index of sulfate radical and calcium ion is only 1.18%, which avoids the presence of calcium sulfate in the Scaling occurs in the concentrated compartment of the electrodialyzer.

The above-mentioned embodiments and drawings do not limit the form and style of the product of the present invention, and any appropriate changes or modifications made by those skilled in the art should be considered as not departing from the patent scope of the present invention.

Claims (6)

1. a kind of electric dialyzator, it is characterised in that：Including anode plate, membrane stack (100), cathode plate and fixing seal membrane stack (100) Pressure plate (2)；The membrane stack (100) include selectivity through monovalent anion Monovalent selectivity anion-exchange membrane (3), Through the cation-exchange membrane (4) and partition (5) of univalent cation and polyvalent cation；Monovalent selectivity anion-exchange membrane It (3) is n, the cation-exchange membrane (4) is n+1, the cation-exchange membrane (4) and the Monovalent selectivity anion Exchange membrane (3) is arranged alternately between pressure plate (2)；

The partition (5) includes the support plate (52) of intermediate plate (51) and intermediate plate (51) two sides, in the middle part of the intermediate plate (51) Equipped with the compartment (511) for being paved with filter (515), the top and bottom of the intermediate plate (51) are respectively equipped with spaced water flow Hole (512) and intercommunicating pore (513)；The intermediate plate (51) is equipped with the stream of the connection water flow hole (512) and the compartment (511) Road (514)；The first hole (521) being connected with compartment (511) is equipped among the support plate (52)；The support plate (52) Top and bottom are respectively equipped with corresponding second hole in the position of the correspondence water flow hole (512) and the intercommunicating pore (513) (522), one end of runner (514) towards the intercommunicating pore (513) is located between the second hole (522) described in its two sides, institute The support plate (52) for stating intermediate plate (51) two sides covers the remainder of its runner (514).

2. a kind of electric dialyzator as described in claim 1, it is characterised in that：Described each described intercommunicating pore of intermediate plate (51) (513) one group of runner (514) is equipped between the compartment (511), runner described in each group (514) is towards the compartment (511) it radially distributes.

3. a kind of electric dialyzator as claimed in claim 2, it is characterised in that：Runner described in each (514) is from the compartment It (511) is arc-shaped to the turning point of its corresponding intercommunicating pore (513), arc radius is 5 to 10mm.

4. a kind of electric dialyzator as claimed in claim 2, it is characterised in that：Positioned at each group of the compartment (511) two sides One end that the runner (514) is connected to the compartment (511) is evenly spaced on the intermediate plate (51), the runner (514) other end for being connected to the intercommunicating pore (513) is evenly spaced on the intermediate plate (51).

5. a kind of electric dialyzator as described in claim 1, it is characterised in that：The each piece of intermediate plate (51) is located at lower end The intercommunicating pore (513) is staggered with the intercommunicating pore (513) for being located at the intermediate plate (51) upper end；Positioned at the centre A water flow hole (512) is equipped between ipsilateral adjacent two intercommunicating pore (513) of plate (51).

6. a kind of electric dialyzator as described in claim 1, it is characterised in that：Runner described in each (514) width is equal, often The width of one runner (514) is 0.5 to 2.5mm, and corresponding runner (514) quantity of each intercommunicating pore (513) is 5 to 15 Item；The intermediate plate (51) with a thickness of 0.3 to 1mm；The support plate (52) is with a thickness of 0.15 to 0.5mm.