An electro-concentration system

Abstract

This invention discloses an electro-concentration system for electrodialysis concentration of high-concentration metal salt wastewater after grating sedimentation filtration. The system includes several electrolytic cells, an inlet module, and an outlet module. The inlet module uniformly pumps and distributes the high-concentration metal salt wastewater to each electrolytic cell for treatment. The outlet module, including a concentrate tank and a desalination tank, receives the concentrate and desalination water processed from the electrolytic cells. Each electrolytic cell includes several electrolytic cells. Within a single electrolytic cell, a compensation range extends 30% along both sides of the centerline. Within this compensation range, the electrolytic cells are equipped with conductive modules to homogenize the electric field intensity within the single electrolytic cell.

Description

Technical Field

[0001] This invention belongs to the technical field of electrodialysis concentration equipment, and specifically relates to an electroconcentration system. Background Technology

[0002] Electroconcentration is a technique that uses an electric field to drive the migration of ions or charged particles in a solution, thereby achieving the separation and concentration of solute and water. Its core principle is based on electrochemical migration and membrane separation (such as electrodialysis and electroadsorption), and the specific process is as follows:

[0003] Electric field-driven ion migration: Under the action of a DC electric field, cations in the solution move towards the cathode, and anions move towards the anode.

[0004] Selective separation using ion exchange membranes: Alternating cation exchange membranes (allowing cations to pass through while blocking anions) and anion exchange membranes (allowing anions to pass through while blocking cations) separate a solution into "dilute compartments" and "concentrated compartments." Ions migrate out of the dilute compartment, diluting the solution; ions accumulate in the concentrated compartment, achieving concentration.

[0005] Electroadsorption and electrodeposition: For charged colloids or organic matter, they can be enriched or degraded through adsorption on the electrode surface (such as electroadsorption technology) or redox reactions (such as electro-Fenton, electrocatalysis).

[0006] In wastewater treatment, high-salinity wastewater concentration is a common application, such as in chemical, dyeing, and coal chemical wastewater. Electrodialysis concentrates salts into a concentrated chamber, while the effluent from the dilute chamber meets discharge standards or is reused. The concentrated wastewater is further treated (e.g., by evaporation and crystallization) to reduce wastewater volume. Electrodialysis technology offers advantages in wastewater treatment, including high-efficiency separation and significant resource recovery potential. However, its development is limited by issues such as energy consumption, membrane fouling, cost, and water quality adaptability. One common problem is that many electrodialysis systems use a two-sided electrode arrangement with several chambers in the middle for discharging concentrated and dilute wastewater. This arrangement results in excessively high applied electric field strength and energy consumption. Furthermore, when the electrodes are located at the ends of the electrode stack, the electric field strength in the middle chamber may indeed weaken due to "voltage drop along the flow path," leading to decreased ion migration efficiency. This phenomenon mainly stems from the accumulation of solution resistance, membrane resistance, and flow channel resistance, causing the effective driving voltage in the middle region to be lower than at the ends. Simply increasing the voltage / current at the ends exacerbates problems such as energy consumption, electrode corrosion, and concentration polarization. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides an electroconcentration system. By optimizing its structure and arranging conductive modules in the intermediate gradient, the electric field effect is homogenized, making the indicators of the concentrated and desalinated water effluents more similar and avoiding secondary treatment.

[0008] The technical solution adopted in this invention is as follows:

[0009] In a first aspect, the present invention provides an electro-concentration system for electrodialysis concentration treatment of high-concentration metal salt wastewater after grid sedimentation filtration. The system includes several electro-pile modules, an inlet module, and an outlet module. The inlet module pumps and distributes the high-concentration metal salt wastewater evenly to each electro-pile module for treatment, and the outlet module, which includes a concentrate tank and a desalination tank, receives the concentrate and desalination water treated from the electro-pile modules.

[0010] The fuel cell module includes several electrolytic cells. Within a single fuel cell, the compensation range extends 30% along the length on both sides of the centerline. Within the compensation range, the electrolytic cells are equipped with conductive modules for homogenizing the electric field intensity within the single fuel cell.

[0011] In conjunction with the first aspect, the present invention provides a first embodiment of the first aspect, wherein the conductive module is a flocculent graphite material uniformly distributed in the electrolytic cell, and within the compensation range of a single stack, the mass of the flocculent graphite material is gradually reduced from the center line to both sides.

[0012] In conjunction with the first aspect, the present invention provides a second embodiment of the first aspect, wherein the conductive module is a porous conductive plate, and within the compensation range of a single fuel cell stack, the volume of the porous conductive plate is gradually reduced from the centerline to both sides.

[0013] In conjunction with the second embodiment of the first aspect, the present invention provides a third embodiment of the first aspect, wherein the electrolytic cell is a high-polymer plate structure with a hollow center, adjacent electrolytic cells are bonded and fixed together, and an anolyte or an anion membrane is provided between adjacent electrolytic cells for isolation.

[0014] In conjunction with the third embodiment of the first aspect, the present invention provides a fourth embodiment of the first aspect, wherein the electrolytic cells in the fuel cell stack all adopt a polymer plate structure of the same specification, the bottom of the electrolytic cell is provided with a water inlet port, the top is provided with an offset water outlet, and the water outlets of adjacent electrolytic cells are spaced apart.

[0015] The term "offset" refers to setting the outlet off to one side of the reference point, with the midpoint of the top of the electrolytic cell as the reference point. This is done to distinguish between the desalination chamber and the concentrate chamber, and to facilitate the management of the water output from the same electrolytic cell stack. By setting the outlets at intervals, the outlets of two adjacent electrolytic cells are located in the left and right directions, respectively. This method is suitable for electrolytic cells with alternating desalination and concentrate settings.

[0016] In conjunction with the first aspect or several embodiments of the first aspect, the present invention provides a fifth embodiment of the first aspect, wherein the fuel cell stack module includes two pressure plates and several electrolytic cells disposed between the pressure plates, and the pressure plates are tightened and fixed to the electrolytic cells by several tension rods.

[0017] In conjunction with the fourth embodiment of the first aspect, the present invention provides a sixth embodiment of the first aspect, wherein the top of the fuel cell stack is provided with a concentrate collection box and a desalination collection box, the concentrate collection box being connected to the outlet of a plurality of electrolytic cells containing concentrate, and the desalination collection box being connected to the outlet of a plurality of electrolytic cells containing desalination.

[0018] In conjunction with the sixth embodiment of the first aspect, the present invention provides a seventh embodiment of the first aspect, wherein the bottom of the fuel cell stack has a water distributor, and the water distributor is connected to the water inlet port of the electrolytic cell and the water inlet module.

[0019] In conjunction with the sixth embodiment of the first aspect, the present invention provides an eighth embodiment of the first aspect, wherein the concentrate collection box is connected to the concentrate tank through a concentrate pipe, and the desalination collection box is connected to the desalination tank through a desalination pipe.

[0020] In conjunction with the fifth embodiment of the first aspect, the present invention provides a ninth embodiment of the first aspect, wherein the pressure plate is provided with a power distribution box, and the power distribution box is connected to an external power supply module via a wiring harness.

[0021] The beneficial effects of this invention are as follows:

[0022] This invention divides the fuel cell stack into multiple sub-stacks by inserting neutral electrodes at regular intervals in the middle of the stack. These electrodes do not participate in the electrochemical reaction but only conduct current, thus shortening the single-segment electric field path. At the same time, it uses highly conductive ion exchange membranes or flow guides to optimize the flow channel, reduce solution resistance, reduce voltage drop in the middle region, and also increase the turbulence effect of the solution inlet, thereby improving concentration efficiency. Attached Figure Description

[0023] Figure 1 This is a plan view of the electroconcentration system in an embodiment of the present invention;

[0024] Figure 2 This is an isometric schematic diagram of the electroconcentration system in an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram showing the internal breakdown of the two electrolytic cells in the electroconcentration system of this invention.

[0026] In the diagram: 1-Pressure plate, 2-Concentrate tank, 3-Desalinate tank, 4-Concentrate pipe, 5-Desalinate pipe, 6-Concentrate collection box, 7-Desalinate collection box, 8-Electrolytic cell, 9-Distribution box, 10-Anion membrane, 11-Cation membrane, 12-Outlet, 13-Porous conductive plate. Detailed Implementation

[0027] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments.

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0030] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0031] In the description of this application, it should be noted that the use of terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" to indicate orientation or positional relationships is based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationships commonly used when the product is in use. These terms are used solely for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the use of terms such as "first" and "second" in the description of this application is only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0032] Furthermore, the use of terms such as "horizontal" and "vertical" in the description of this application does not imply that the component is required to be absolutely horizontal or suspended, but rather that it may be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but rather that it may be slightly tilted.

[0033] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0034] Example 1:

[0035] This embodiment discloses an electro-concentration system for electrodialysis concentration of high-concentration metal salt wastewater after it has been filtered by a grid. In this embodiment, the influent is treated to remove precipitates, suspended solids and other solid wastes, thereby avoiding any impact on the electrodes or membrane materials.

[0036] Specifically, the electroconcentration system in this embodiment, also a type of electroconcentration dialysis system, includes several electrolytic cells, an inlet module, and an outlet module. The inlet module pumps and distributes high-concentration metal salt wastewater evenly to each electrolytic cell for treatment, and the outlet module, including a concentrate tank 2 and a desalination tank 3, receives the concentrate and desalination water treated from the electrolytic cells. The electrolytic cell includes several electrolytic cells 8, with a compensation range of 30%-50% extending in the length direction on both sides of the centerline within a single electrolytic cell. Within the compensation range, the electrolytic cells 8 are equipped with conductive modules for homogenizing the electric field intensity within the single electrolytic cell.

[0037] As one implementation method, refer to Figures 1-2 This embodiment discloses an electroconcentration system, whose stack module includes several electrolytic cells 8. A compensation range is defined by extending 30% along the length of each individual stack centerline. Within the electrolytic cells 8 within the compensation range, a uniformly distributed flocculent graphite material serves as a conductive module. This material has a loose, porous, fibrous structure, is electrochemically inert, does not participate in electrochemical reactions, and only improves the electric field distribution through a conductive network.

[0038] In the specific arrangement, the density is highest at the center line, and the mass of flocculent graphite decreases linearly towards both sides. For example, 50g of graphite is filled per liter of electrolytic cell 8 volume at the center line, and the amount decreases to 30g at the edge regions on both sides, forming a conductivity gradient from the center to the edge to compensate for the electric field attenuation caused by the distance from the electrode. Electrolytic cells 8 are made of hollow polymer plates (such as polypropylene), and adjacent electrolytic cells 8 are fixed by bonding, with cation exchange membranes or anion exchange membranes sandwiched between them to isolate the dilute and concentrated chambers.

[0039] Each electrolytic cell 8 has a water inlet port at the bottom, which is connected to the water distributor at the bottom of the stack. The water distributor is connected to the centrifugal pump of the water inlet module through a pipe to achieve uniform distribution of wastewater. An offset water outlet 12 is provided at the top, which is offset to the left or right by 5-15cm from the midpoint of the top. The water outlets 12 of adjacent electrolytic cells 8 are arranged alternately on the left and right to ensure that the water outlet directions of the dilute chamber and the concentrated chamber are separated.

[0040] The fuel cell stack is clamped between two steel pressure plates 1 and four tension rods that pass through the pressure plates 1 and the electrolytic cell 8 to apply pre-tightening force, forming a sealed structure. A distribution box 9 is embedded on the surface of the pressure plate 1, which integrates conductive copper busbars and is connected to an external DC power supply module through a wiring harness to provide a stable electric field for the fuel cell stack.

[0041] During the treatment process, high-concentration wastewater enters the electrolytic cell 8 through the water distributor. Under the action of the electric field, ions migrate through the exchange membrane. The flocculent graphite within the compensation range enhances the conductivity of the middle area, so that the difference in electric field strength between the chambers is controlled within 5%. The concentrated water flows into the top concentrated water collection box 6 through the right outlet 12 and then into the concentrated water tank 2 through the concentrated water pipe 4. The desalinated water enters the desalinated water collection box 7 through the left outlet 12 and then flows into the desalinated water tank 3, achieving efficient separation.

[0042] As one implementation method, different from the above-described implementation method, refer to, Figure 3 The conductive module of the fuel cell stack adopts a porous conductive plate 13 structure, made of carbon-based porous fiberboard, which has high specific surface area and stable conductivity. Within the compensation range of a single fuel cell stack (30% of the length region on both sides of the center line), the volume of the porous conductive plate 13 decreases exponentially from the center to both sides. For example, the thickness of the conductive plate at the center line is 8mm, accounting for 40% of the height of the electrolytic cell 8, and decreases by 2mm for every 10cm to both sides, with the thickness in the edge region decreasing to 4mm, thus forming a targeted reinforcement of the weak electric field region in the middle.

[0043] Electrolytic cell 8 is a uniformly sized polymer board component with a rectangular hollow cavity. The bottom water inlet port has a diameter of 10mm, and the top offset water outlet 12 has a diameter of 8mm. It is offset to the left or right by 1.5cm from the midpoint. The water outlets 12 of adjacent electrolytic cells 8 are arranged in an alternating left and right manner, and are arranged in conjunction with the alternating cation membrane 11 and anion membrane 10 in the middle to form a dilute chamber and a concentrated chamber.

[0044] During the assembly of the electrolytic cell stack, the electrolytic cells 8 and ion exchange membranes are stacked alternately, and the pressure plates 1 on both sides are fixed by tension rods. Fluid channels are opened at the edges of the pressure plates 1, which are connected to the bottom water distributor and the top concentrate and desalination collection boxes 7. The water distributor is equipped with a flow distribution plate to evenly distribute the wastewater pumped by the water inlet module to the inlet port of each electrolytic cell 8. When the water flows through the porous conductive plate 13 in the electrolytic cell 8, the gradient volume design of the conductive plate increases the conductivity of the solution in the middle region by more than 20%, effectively reducing the voltage drop.

[0045] The top-mounted concentrated water collection box 6 and fresh water collection box 7 are connected to the concentrated water pipe 4 and fresh water pipe 5 respectively via flanges. Electromagnetic flow meters and electric valves are installed on the pipes to achieve real-time metering and diversion of concentrated and fresh water. The power distribution box 9 is integrated on the outside of the pressure plate 1 and is connected to an external adjustable DC power supply via copper cable. The voltage can be dynamically adjusted according to the water quality. Combined with the homogenization effect of the electric field of the porous conductive plate 13, the ion migration rate in the middle of the stack is improved compared with the traditional structure. At the same time, it avoids the side reactions of hydrogen and oxygen evolution caused by local high voltage, and the overall energy consumption is reduced by 15%. This structure is particularly suitable for high-salt wastewater containing heavy metal ions such as nickel and copper. After treatment, the metal ion concentration of the fresh water can be reduced to below 10 mg / L, and the salt concentration of the concentrated water is enriched to 8-10 times that of the original water, which is convenient for subsequent evaporation, crystallization and recovery.

[0046] In one implementation, the electrolytic cell 8 of the fuel cell stack module adopts a modular design. All electrolytic cells 8 are processed using polypropylene plates of the same specifications. The hollow cavity is 15mm deep. The bottom water inlet port and the top offset water outlet 12 are integrally formed by a mold. The offset distance of the water outlet 12 is 1 / 4 of the top width, ensuring that the water outlet directions of adjacent electrolytic cells 8 are opposite, which facilitates the separation of concentrated and desalinated water.

[0047] Within the compensation range (30% of the length on both sides of the center line), the electrolytic cell 8 is filled with flocculent graphite material, whose mass distribution follows a quadratic function gradient, i.e., the density peaks at the center line and decreases towards both sides with a gradient of y = ax. 2 The electric field strength decreases in the form of +b. The parameters are optimized through COMSOL simulation to keep the difference between the electric field strength in the middle region and that at both ends within 8%.

[0048] The installation sequence of the conductive modules and ion exchange membranes is as follows: alternating arrangement of cation membrane 11 - electrolytic cell 8 (including conductive material) - anion membrane 10 - electrolytic cell 8 (excluding conductive material). Conductive material is only installed in electrolytic cell 8 within the compensation range, while the non-compensation area maintains the conventional structure to balance cost and effectiveness. The external pressure plate 1 of the fuel cell stack is made of aluminum alloy with an insulating coating on the surface. Conductive busbars are embedded inside and connected to the distribution box 9. The distribution box 9 is connected to an external constant current power supply through a waterproof wiring harness to ensure uniform current loading.

[0049] The bottom water distributor is made of ABS engineering plastic, with an internal flow channel designed as a tree-like branching structure. A 5μm filter is installed before each water inlet to prevent suspended solids from clogging the electrolytic cell 8. The top concentrated water collection box 6 and the desalinated water collection box 7 are both made of PVC, with an anti-corrosion coating on the inner wall. The bottom of the collection box is tilted at 5° to facilitate the rapid flow of concentrated and desalinated water into the pipeline. During operation, high-concentration metal salt wastewater is pressurized to 0.3MPa by the screw pump of the inlet module and evenly enters each electrolytic cell 8 through the water distributor. With the assistance of gradient-distributed flocculent graphite, the ion migration resistance in the middle region is reduced, and the electric field energy is concentrated on the target ions (such as Na+, Cl-, Ni). 2The migration of +) can achieve a total salt removal rate of over 92% in freshwater and increase the concentration factor of concentrated water to 15 times.

[0050] This embodiment effectively solves the problem of low efficiency in the middle area of ​​traditional fuel cell stacks by precisely arranging the conductive modules and optimizing the structure of the electrolytic cell 8. At the same time, it avoids the risks of gas evolution and corrosion caused by additional electrodes. It is suitable for continuous industrial wastewater treatment scenarios, improves equipment operation stability by 30%, and extends the maintenance cycle to more than 6 months.

[0051] This invention is not limited to the optional embodiments described above, and anyone can derive other various forms of products based on the inspiration of this invention. The specific embodiments described above should not be construed as limiting the scope of protection of this invention; the scope of protection of this invention should be determined by the claims, and the specification can be used to interpret the claims.

Claims

1. An electro-concentration system for electrodialysis concentration treatment of high-concentration metal salt wastewater after grating sedimentation and filtration, characterized in that: It includes several fuel cell stack modules, an inlet water module and an outlet water module. The inlet water module pumps and distributes high-concentration metal salt wastewater evenly to each fuel cell stack module for treatment, and the outlet water module, which includes a concentrate tank (2) and a desalination tank (3), receives the concentrate and desalination water after treatment from the fuel cell stack modules. The stack module includes several electrolytic cells (8). The compensation range is within 30% of the length on both sides of the center line within a single stack. Within the compensation range, the electrolytic cells (8) are equipped with conductive modules for homogenizing the electric field intensity within a single stack. The conductive module is a flocculent graphite material uniformly distributed in the electrolytic cell (8). Within the compensation range of a single stack, the mass of the flocculent graphite material is gradually reduced from the center line to both sides. Alternatively, the conductive module may be a porous conductive plate (13), and within the compensation range of a single stack, the volume of the porous conductive plate (13) is gradually reduced from the center line to both sides.

2. The electroconcentration system according to claim 1, characterized in that: The electrolytic cell (8) is a high-polymer plate structure with a hollow center. Adjacent electrolytic cells (8) are attached and fixed together, and a positive membrane (11) or an negative membrane (10) is provided between adjacent electrolytic cells (8) for isolation.

3. The electroconcentration system according to claim 2, characterized in that: The electrolytic cells (8) in the stack all adopt the same polymer plate structure. The bottom of the electrolytic cell (8) is provided with a water inlet port and the top is provided with an offset water outlet (12). The water outlets (12) of adjacent electrolytic cells (8) are spaced apart.

4. An electroconcentration system according to any one of claims 1-3, characterized in that: The fuel cell stack module includes two pressure plates (1) and several electrolytic cells (8) disposed between the pressure plates (1). The pressure plates (1) are tightened and fixed to the electrolytic cells (8) by several tension rods.

5. An electroconcentration system according to claim 3, characterized in that: The top of the fuel cell stack is provided with a concentrated water collection box (6) and a fresh water collection box (7). The concentrated water collection box (6) is connected to the outlet (12) of a plurality of electrolytic cells (8) containing concentrated water, and the fresh water collection box (7) is connected to the outlet (12) of a plurality of electrolytic cells (8) containing fresh water.

6. An electroconcentration system according to claim 5, characterized in that: The bottom of the fuel cell stack has a water distributor, which is connected to the water inlet port of the electrolytic cell (8) and the water inlet module.

7. An electroconcentration system according to claim 5, characterized in that: The concentrated water collection box (6) is connected to the concentrated water tank (2) through the provided concentrated water pipe (4), and the fresh water collection box (7) is connected to the fresh water tank (3) through the provided fresh water pipe (5).

8. An electroconcentration system according to claim 4, characterized in that: The pressure plate (1) is provided with a power distribution box (9), which is connected to an external power supply module through a wire harness.

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