Electro-concentration system

Abstract

The invention discloses an electric concentration system, which is used for carrying out electrodialysis concentration treatment on high-concentration metal salt wastewater precipitated and filtered by a grid, and comprises a plurality of electric pile modules, a water inlet module and a water outlet module, and the high-concentration metal salt wastewater is uniformly pumped and distributed to each electric pile module by the water inlet module for treatment; a water outlet module comprising a concentrated water tank and a fresh water tank is used for receiving concentrated water and fresh water treated by the electric pile module; the galvanic pile module comprises a plurality of electrolytic cells, a compensation range is a range which is located in a single galvanic pile and extends by 30% in the length direction of the two sides with the center line as the benchmark, and conductive modules used for forming electric field intensity homogenization in the single galvanic pile are arranged in the electrolytic cells in the compensation range.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrodialysis concentration equipment, and in particular relates to an electric concentration system. Background Art

[0002] Electroconcentration is a technology that uses an electric field to drive the migration of ions or charged particles in a solution, thereby separating and concentrating solutes from water. Its core principle is based on electrochemical migration and membrane separation (such as electrodialysis and electroadsorption). 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 toward the cathode and anions move toward the anode.

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

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

[0006] Concentration of high-salinity wastewater is a common application in wastewater treatment, particularly in chemical, printing and dyeing, and coal chemical industries. Electrodialysis concentrates the salts in a concentrate chamber, allowing the effluent from the dilute chamber to meet discharge standards or be reused. The concentrate is then further treated (e.g., by evaporation and crystallization) to reduce wastewater volume. While electroconcentration technology offers advantages in wastewater treatment, such as efficient separation and significant resource utilization potential, its development is limited by energy consumption, membrane fouling, cost, and water quality compatibility. Many electroconcentration dialysis systems utilize a dual-side electrode arrangement with several intermediate chambers for the discharge of concentrated and dilute water. This arrangement results in excessively high applied electric field strength and high energy consumption. Furthermore, in electroconcentration equipment, when the electrodes are located at the ends of the stack, the electric field strength in the intermediate chamber can be weakened due to a "voltage drop along the path," resulting in reduced ion migration efficiency. This phenomenon is primarily due to the accumulation of solution resistance, membrane resistance, and flow resistance, resulting in a lower effective driving voltage in the intermediate region than at the ends. Improving performance by simply increasing the voltage / current at the ends can exacerbate energy consumption, electrode corrosion, and concentration polarization. Summary of the Invention

[0007] In order to solve the problems existing in the prior art, the present invention provides an electric concentration system. By optimizing its structure, a conductive module is arranged in the middle gradient to homogenize the electric field effect, so that the indicators of the entire concentrated water and fresh water outlet are relatively close, avoiding secondary treatment.

[0008] The technical solution adopted in the present invention is:

[0009] In a first aspect, the present invention provides an electroconcentration system for performing electrodialysis concentration treatment on high-concentration metal salt wastewater after grid sedimentation and filtration. The system comprises a plurality of stack modules, an inlet module, and an outlet module. The inlet module pumps the high-concentration metal salt wastewater evenly to each stack module for treatment, and the outlet module, which comprises a concentrated water tank and a fresh water tank, receives the concentrated water and fresh water after treatment from the stack modules.

[0010] The stack module includes several electrolytic cells, and the compensation range is within 30% of the length on both sides of the center line of a single stack. The electrolytic cells within the compensation range are provided with conductive modules for forming a homogenous electric field strength in the single stack.

[0011] In combination 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 fuel cell stack, the mass of the flocculent graphite material is gradually reduced from the center line to both sides.

[0012] In combination with the first aspect, the present invention provides a second implementation of the first aspect, wherein the conductive module is a porous conductive plate, and within the compensation range of a single battery stack, the volume of the porous conductive plate is gradually reduced from the center line to both sides.

[0013] In combination 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 polymer plate structure with a hollow middle portion, adjacent electrolytic cells are bonded and fixed, and a positive membrane or a negative membrane is provided between adjacent electrolytic cells for isolation.

[0014] In combination 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, a water inlet port is provided at the bottom of the electrolytic cell, an offset water outlet is provided at the top, and the water outlets of adjacent electrolytic cells are arranged at intervals.

[0015] The so-called bias means that the midpoint of the top of the electrolytic cell is used as the reference point, and the water outlet is offset to one side of the reference point. In order to distinguish the fresh water chamber and the concentrated water chamber, and to facilitate the water outlet management of the same fuel cell stack, the water outlets of the two adjacent electrolytic cells are respectively set in the left and right directions through the interval-arranged water outlets, which is suitable for electrolytic cells with fresh water and concentrated water arranged at intervals.

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

[0017] In combination with the fourth embodiment of the first aspect, the present invention provides a sixth embodiment of the first aspect, wherein a concentrated water collection box and a fresh water collection box are provided on the top of the fuel cell stack, the concentrated water collection box is connected to the water outlets of several electrolytic cells storing concentrated water, and the fresh water collection box is connected to the water outlets of several electrolytic cells storing fresh water.

[0018] In combination 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 combination with the sixth embodiment of the first aspect, the present invention provides an eighth embodiment of the first aspect, wherein the concentrated water collection box is connected to the concentrated water tank via a concentrated water pipe, and the fresh water collection box is connected to the fresh water tank via a fresh water pipe.

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

[0021] The beneficial effects of the present invention are:

[0022] The present invention divides the battery stack into multiple sub-stacking cells by inserting neutral electrodes at regular intervals of membrane pairs in the middle of the battery stack. The neutral electrodes do not participate in the electrochemical reaction but only conduct current, thereby shortening the single-segment electric field path. At the same time, high-conductivity ion exchange membranes or guide plates are used to optimize the flow channel, reduce the solution resistance, and reduce the voltage drop in the middle area. At the same time, the turbulence effect of the solution inlet is increased, thereby improving the concentration efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a plan view of an electric concentration system according to an embodiment of the present invention;

[0024] Figure 2 is an axonometric schematic diagram of an electric concentration system according to an embodiment of the present invention;

[0025] Figure 3 Schematic diagram of the internal disassembly of the two electrolytic cell structures in the electroconcentration system in an embodiment of the present invention.

[0026] In the figure: 1-pressing plate, 2-concentrated water tank, 3-fresh water tank, 4-concentrated water pipe, 5-fresh water pipe, 6-concentrated water collecting box, 7-fresh water collecting box, 8-electrolyzer, 9-distribution box, 10-anion membrane, 11-cation membrane, 12-water outlet, 13-porous conductive plate. DETAILED DESCRIPTION

[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 the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in the present application without making any creative efforts shall fall within the scope of protection of the present application.

[0030] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0031] In the description of this application, it should be noted that if the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or the orientation or position relationship in which the product of the application is usually placed when in use. It is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, it cannot be understood as a limitation on this application. In addition, if the terms "first", "second", etc. appear in the description of this application, they are only used to distinguish the description and cannot be understood 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 necessarily imply that a component must be absolutely horizontal or suspended, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical" and does not mean that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0033] It should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. A person of ordinary skill in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0034] Example 1:

[0035] This embodiment discloses an electroconcentration system for performing electrodialysis concentration treatment on high-concentration metal salt wastewater after grid sedimentation filtration. In this embodiment, the influent water undergoes certain treatment to filter out solid waste such as sediment and suspended matter in the water, thereby avoiding affecting the electrode or membrane material.

[0036] Specifically, the electric concentration system in this embodiment is also used as an electric concentration dialysis system, including several stack modules, water inlet modules and water outlet modules. The water inlet module pumps high-concentration metal salt wastewater evenly to each stack module for treatment, and the water outlet module including the concentrated water tank 2 and the fresh water tank 3 receives the concentrated water and fresh water treated from the stack module; the stack module includes several electrolytic cells 8, and the compensation range is 30%-50% of the length extending on both sides of the center line in a single stack. The electrolytic cell 8 within the compensation range is provided with a conductive module for forming a homogenized electric field strength in the single stack.

[0037] As an embodiment, referring to Figure 1-Figure 2 This embodiment discloses an electroconcentration system. Its stack module comprises several electrolytic cells 8. A compensation range is defined as an area extending 30% of the length of each cell stack's centerline. Within the compensation range, flocculent graphite material is evenly distributed within the cells 8 as a conductive module. This material has a loose, porous, fibrous structure and is electrochemically inert. It does not participate in the electrochemical reaction 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 is reduced linearly toward both sides. For example, 50g of graphite is filled per liter of electrolytic cell 8 volume at the center line, and the density decreases to 30g at the edges on both sides. This creates a conductivity gradient from the center to the edges, compensating for the electric field attenuation caused by the distance from the electrode. The electrolytic cells 8 are made of a hollowed-out polymer sheet (such as polypropylene). Adjacent electrolytic cells 8 are fixed by bonding, with a cation exchange membrane or an anion exchange membrane sandwiched between them to separate the dilute chamber from the concentrated chamber.

[0039] A water inlet port is provided at the bottom of each electrolytic cell 8, which is connected to the water distributor at the bottom of the fuel cell 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 5-15 cm to the left or right with the midpoint of the top as the reference. The water outlets 12 of adjacent electrolytic cells 8 are arranged in an alternating left-right manner to ensure that the water outlet directions of the dilute chamber and the concentrated chamber are separated.

[0040] The exterior of the stack is clamped by two steel pressure plates 1. Four tension rods run through the pressure plates 1 and the electrolytic cell 8, applying preload force to form a sealed structure. A distribution box 9 is embedded in the surface of the pressure plates 1, with a conductive copper busbar integrated inside. This is connected to the external DC power supply module via a wiring harness, providing a stable electric field for the 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 in the compensation range enhances the conductivity of the middle area, so that the difference in electric field strength in each chamber is controlled within 5%. The concentrated water is collected into the top concentrated water collection box 6 through the right water outlet 12, and flows into the concentrated water tank 2 through the concentrated water pipe 4. The fresh water enters the fresh water collection box 7 through the left water outlet 12 and then flows into the fresh water tank 3, achieving efficient separation.

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

[0043] The electrolytic cell 8 is a polymer plate component of uniform specifications, with a hollow cavity in the shape of a rectangle. The diameter of the bottom water inlet port is 10 mm, the top offset water outlet 12 is 8 mm in diameter, and it is offset 1.5 cm to the left or right with the midpoint as the reference. The water outlets 12 of adjacent electrolytic cells 8 are arranged in an alternating manner on the left and right, and the alternating arrangement of the middle cation membrane 11 and the anion membrane 10 forms an interval distribution of the dilute chamber and the concentrated chamber.

[0044] During stack assembly, electrolytic cells 8 and ion exchange membranes are stacked alternately, secured by tensioning rods on either side with pressure plates 1. Fluid channels are provided along the edges of the pressure plates 1, connecting to the bottom water distributor and the top concentrated and fresh water collection boxes 7. A diverter plate is installed within the water distributor to evenly distribute wastewater pumped from the inlet module to the inlet port of each electrolytic cell 8. As water flows through the porous conductive plates 13 within the electrolytic cells 8, the gradient volume design of the conductive plates increases the conductivity of the solution in the central region by over 20%, effectively reducing voltage drop.

[0045] The top concentrated water collection box 6 and the fresh water collection box 7 are connected to the concentrated water pipe 4 and the fresh water pipe 5 respectively via flanges. Electromagnetic flowmeters and electric valves are installed on the pipes to achieve real-time metering and diversion of concentrated and fresh water. The distribution box 9 is integrated on the outside of the pressure plate 1 and connected to an external adjustable DC power supply via a copper cable. The voltage can be dynamically adjusted according to the quality of the treated water. In conjunction with the electric field homogenization effect of the porous conductive plate 13, the ion migration rate in the middle of the stack is improved compared to traditional structures, while avoiding the side reactions of hydrogen and oxygen evolution caused by local high voltage, reducing overall energy consumption 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 raw water, facilitating subsequent evaporation and crystallization recovery.

[0046] As an implementation method, the electrolytic cells 8 of the stack module adopt a modular design. All electrolytic cells 8 are processed using polypropylene plates of the same specifications. The hollow cavity depth is 15 mm. 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 fresh water.

[0047] In the compensation range (30% of the length on both sides of the center line), the electrolytic cell 8 is filled with flocculent graphite material, and its mass distribution follows a quadratic function gradient, that is, the density at the center line is the peak value, and the density at both sides is y=ax 2 +b, and the parameters are optimized through COMSOL simulation so that the difference between the electric field intensity in the middle area and that at both ends is controlled within 8%.

[0048] The conductive modules and ion exchange membranes are installed in the following order: alternating arrangement: cation membrane 11 - electrolytic cell 8 (containing conductive material) - anion membrane 10 - electrolytic cell 8 (excluding conductive material). Conductive material is only installed in the electrolytic cells 8 within the compensation range, while the non-compensation area maintains a conventional structure to balance cost and performance. The external pressure plate 1 of the stack is made of aluminum alloy with an insulating coating. An internally embedded conductive busbar connects to the distribution box 9, which is connected to an external constant-current power supply via a waterproof wiring harness to ensure uniform current loading.

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

[0050] This embodiment effectively solves the problem of low efficiency in the middle area of the traditional fuel cell stack through the precise gradient arrangement of the conductive modules and the optimization of the structure of the electrolytic cell 8, while avoiding the gas precipitation and corrosion risks caused by additional electrodes. It is suitable for continuous industrial wastewater treatment scenarios, the equipment operation stability is improved by 30%, and the maintenance cycle is extended to more than 6 months.

[0051] The present invention is not limited to the above optional embodiments. Anyone can derive various other forms of products based on the teachings of the present invention. The above specific embodiments should not be construed as limiting the scope of protection of the present invention. The scope of protection of the present invention shall be based on the scope defined in the claims, and the description can be used to interpret the claims.

Claims

1. An electroconcentration system for electrodialysis concentration of high-concentration metal salt wastewater after grid sedimentation and filtration, characterized by: The system comprises a plurality of stack modules, a water inlet module and a water outlet module. The water inlet module pumps high-concentration metal salt wastewater evenly to each stack module for treatment, and the water outlet module comprises a concentrated water tank (2) and a fresh water tank (3) to receive concentrated water and fresh water after treatment from the stack modules. The stack module comprises a plurality of electrolytic cells (8), wherein a compensation range is defined as a range extending 30% in the length direction on both sides of a center line of a single stack, and a conductive module for forming a homogenized electric field intensity in the single stack is provided in the electrolytic cells (8) within the compensation range.

2. The electric concentration system according to claim 1, characterized in that: The conductive module is a flocculent graphite material uniformly distributed in the electrolytic cell (8), and within the compensation range of a single stack, the mass of the flocculent graphite material is reduced in a gradient from the center line to both sides.

3. The electric concentration system according to claim 1, characterized in that: The conductive module is a porous conductive plate (13), and within the compensation range of a single battery stack, the volume of the porous conductive plate (13) is reduced in a gradient from a center line to both sides.

4. The electric concentration system according to claim 3, characterized in that: The electrolytic cell (8) is a polymer plate structure with a hollow center. Adjacent electrolytic cells (8) are fitted and fixed together, and a positive membrane (11) or a negative membrane (10) is provided between adjacent electrolytic cells (8) for isolation.

5. The electric concentration system according to claim 4, characterized in that: The electrolytic cells (8) in the stack all adopt a polymer plate structure of the same specification. 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 arranged at intervals.

6. An electric concentration system according to any one of claims 1 to 5, characterized in that: The stack module comprises two pressing plates (1) and a plurality of electrolytic cells (8) arranged between the pressing plates (1); the pressing plates (1) are tightened and fixed with the electrolytic cells (8) via a plurality of tension rods.

7. The electric concentration system according to claim 5, characterized in that: A concentrated water collection box (6) and a fresh water collection box (7) are provided on the top of the stack. The concentrated water collection box (6) is connected to the water outlets (12) of a plurality of electrolytic cells (8) storing concentrated water, and the fresh water collection box (7) is connected to the water outlets (12) of a plurality of electrolytic cells (8) storing fresh water.

8. The electric concentration system according to claim 7, characterized in that: The bottom of the stack is provided with a water distributor, which is connected to the water inlet port of the electrolytic cell (8) and the water inlet module.

9. The electric concentration system according to claim 7, characterized in that: The concentrated water collection box (6) is connected to the concentrated water tank (2) via a concentrated water pipe (4), and the fresh water collection box (7) is connected to the fresh water tank (3) via a fresh water pipe (5).

10. The electric concentration system according to claim 6, characterized in that: A power distribution box (9) is provided on the pressure plate (1), and the power distribution box (9) is connected to an external power supply module via a wiring harness.

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