Electrochemical reactor with multiple electrode groups connected in parallel and through cathode liquid

Abstract

The invention relates to the technical field of water treatment, in particular to a catholyte-through multi-electrode-group parallel electrochemical reactor which comprises a reaction tank and a plurality of groups of electrode assemblies arranged in the reaction tank, the electrode assembly includes an anode; the cathode is annularly arranged outside the anode; the separation net is arranged between the anode and the cathode and is configured to isolate the catholyte from the anolyte; the base and the cover are provided with grooves for mounting the anode, the separation net and the cathode and are respectively mounted at the bottoms and the tops of the anode, the separation net and the cathode; the positive terminal is inserted into the cover and is connected with the anode; the negative terminal is inserted into the cover and is connected with the cathode; the acid extraction opening is formed in the center of the cover and penetrates through the cover to extend into the anode area of the anode; and the external pump is connected with the acid pumping port through a pipeline. The problem of insufficient utilization of hydroxyl in the existing water softening technology is solved, the number of the electrode groups can be flexibly adjusted according to actual requirements, the industrial-scale water treatment requirements are met, and meanwhile, the operation cost is effectively reduced.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment, and more particularly to a multi-electrode parallel electrochemical reactor with cathode liquid passing through. Background Art

[0002] One of the challenges in the field of water treatment is scaling caused by hardness. Calcium and magnesium ions in water form scale in pipes, heat exchangers and cooling systems, which not only hinders water flow and heat exchange, but also accelerates equipment aging, thereby reducing production efficiency and even posing a risk of explosion.

[0003] The current water softening methods mainly include chemical precipitation, ion exchange and electrochemistry. The chemical precipitation method first adds alkali to form a mixed precipitate with calcium and magnesium to remove hardness, and then introduces acid to neutralize the soft water, which not only consumes a large amount of chemicals but also produces a large amount of solid waste. The resin of the ion exchange method needs to be regenerated with concentrated brine, which not only continuously produces waste brine, but also has a limited life span of the resin, which also produces solid waste.

[0004] Electrochemical water softening technology uses the hydroxide generated at the cathode to react with Ca in the water. 2+ Mg 2+ 、HCO3 - The reaction generates CaCO3 and Mg(OH)2 precipitation, thereby removing the hardness. Compared with chemical precipitation and ion exchange, it has the advantage of not requiring chemical agents. However, the electrochemical softening process relies on the deposition of calcium carbonate and magnesium hydroxide on the cathode surface to remove hardness. The insulating scale layer covers the cathode, causing a rapid increase in energy consumption until the electrochemical reaction is terminated. Cathode scaling has become a concomitant phenomenon of electrochemical water softening and is theoretically unavoidable. Commercially available electrochemical descaling equipment is based on the above principle. After the scale layer on the cathode surface accumulates to a certain extent, these scales are removed by manual scraping, pickling, ultrasonic cleaning, etc. For example, patents with publication numbers CN118878017A, CN221940256U, and CN220393398U use mechanical scraping to scrape off the scale, patents with publication numbers CN219950606U and CN115745090A use a reverse pole method for descaling, and patents with publication number CN214611981U use ultrasonic cleaning for descaling. These descaling modes not only interrupt the reaction but also reduce the electrode life.

[0005] In recent years, enhanced homogeneous nucleation technology has emerged, which uses microbubbles generated at the cathode to promote the diffusion of hydroxide into the solution, so that scale crystal nucleation occurs mainly in the solution rather than on the electrode, thereby inhibiting cathode scaling, for example, references "Spatial and Temporal Regulation of Homogeneous Nucleation and Crystal Growthfor High-flux Electrochemical Water Softening" and "Scaling-Free Cathodes: Enabling Electrochemical Extraction of High-Purity Nano-CaCO3 and-Mg(OH)2inSeawater". However, the diffusion distance of hydroxide promoted by microbubbles is limited, and the hydroxide concentration in the cathode liquid decreases monotonically with the distance from the cathode. Only the pH of the solution close to the cathode surface can meet the homogeneous nucleation requirement of 9.3 or above. The cathode liquid farther away cannot complete the softening reaction due to insufficient pH. If the proportion of cathode liquid that does not participate in softening is too high, the water softening efficiency will not meet the requirements. The boundary of the cathode pool of the reported homogeneous nucleation electrochemical reactor is composed of the cathode and the reactor wall. In order to make as much cathode liquid as possible have softening ability, the volume of the cathode pool cannot be enlarged, and the water treatment capacity can only be improved by connecting multiple groups of unit reactors in parallel. There are two problems with this reactor stacking amplification method: high investment cost, large area of ​​​​water treatment capacity per ton, and difficult maintenance; in order to make the pH of the cathode liquid farthest from the cathode high enough, the pH of the cathode surface must be higher, exceeding the nucleation requirements, increasing energy consumption and the risk of cathode scaling. These two problems make the existing reactors technically and economically impractical. Summary of the invention

[0006] In order to solve the problem of insufficient utilization of hydroxide that is common in existing water softening technologies, the present invention develops an electrochemical reactor that fully utilizes hydroxide to achieve efficient water softening. The present invention proposes a new electrode assembly that seals the anolyte inside and exposes the cathode liquid outside. Multiple groups of electrode assemblies are placed in a large reactor, and the cathode liquids are interconnected. The hydroxide concentration is balanced by superimposing multiple components. Not only does the pH on the cathode surface not need to rise too high, but the volume of the cathode liquid that meets the pH requirement for homogeneous nucleation is larger. This parallel amplification method of the components can also directly utilize existing water treatment facilities such as cooling tower pools. Compared with the parallel amplification of reactors, it has significant advantages in terms of land occupation, investment, energy consumption, and softening efficiency.

[0007] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0008] The present invention provides a multi-electrode parallel electrochemical reactor with cathode liquid passing through, comprising a reaction tank with a water inlet and a water outlet; a single or multiple electrode assemblies arranged in the reaction tank, the multiple electrode assemblies are arranged in parallel along a first direction, each electrode assembly includes multiple electrode assemblies arranged in parallel along a second direction, an angle is formed between the first direction and the second direction, and the multiple electrode assemblies are connected in parallel;

[0009] The electrode assembly includes an anode; a cathode, which is arranged outside the anode in a ring; a separator, which is arranged between the anode and the cathode and is configured to separate the cathode liquid and the anode liquid; a base and a cover, which have grooves for installing the anode, the separator and the cathode, and are respectively installed at the bottom and top of the anode, the separator and the cathode; a positive electrode terminal, which is inserted into the cover and connected to the anode; a negative electrode terminal, which is inserted into the cover and connected to the cathode; an acid extraction port, which is installed in the center of the cover and penetrates through the cover into the anode area of ​​the anode; an external pump, which is configured to extract the acid in the anode area, and the external pump is connected to the acid extraction port through a pipeline;

[0010] The spacing between adjacent electrode assemblies is 0.1m to 0.3m, and the spacing between the electrode assembly close to the inner wall of the reaction tank and the reaction tank is 0.1m to 0.3m;

[0011] The height of the anode, separator and cathode is 0.01m to 5m.

[0012] Under the preferred solution, during normal operation, the acid extraction flow rate of the external pump is set to less than 50 L / h; when cleaning the cathode scale layer, the acid extraction flow rate of the external pump is set to greater than 100 L / h.

[0013] In a preferred embodiment, the cathode is made of metal, and the metal is stainless steel, iron, copper, titanium, nickel or aluminum.

[0014] In a preferred embodiment, the separator is an ion exchange membrane, a nylon separator, a polytetrafluoroethylene mesh or a vinylidene fluoride membrane.

[0015] In a preferred embodiment, the separator is a nylon separator, and the pore size of the nylon separator is not less than 74 μm or 0.001 to 40 μm.

[0016] In a preferred embodiment, the anode, the separator and the cathode are in the shape of a cylinder, an elliptical cylinder, a polygonal cylinder, a line or a diamond.

[0017] In a preferred embodiment, the anode, the separator and the cathode are cylindrical in shape, and the outer diameter of the cylinder is 0.1 m to 1 m.

[0018] In the preferred embodiment, the current density in the reaction tank is 1-1000 mA / cm 2 .

[0019] In the preferred embodiment, a valve is provided below the reaction tank.

[0020] In a preferred embodiment, the spacing between adjacent electrode assemblies is 0.1m to 0.15m, and the spacing between the electrode assembly close to the inner wall of the reaction tank and the reaction tank is 0.1m to 0.15m.

[0021] Beneficial effects of the present invention:

[0022] 1. The present invention adopts an innovative multi-electrode parallel electrochemical reactor with cathode liquid passing through, and achieves uniformity and stability of the electrochemical reaction area by controlling the parallel spacing of the components. The number of electrode groups can be flexibly adjusted according to the processing volume requirements to meet the needs of industrial-scale water treatment, while effectively reducing operating costs.

[0023] 2. During the use of the electrochemical reactor provided by the present invention, the water to be treated flows through the electrolysis area, that is, the area in the reaction tank, so that hardness ions such as calcium and magnesium in the water are deposited in the cathode area, thereby achieving the effect of water softening. In order to reduce the problem of acid accumulation, the present invention is provided with an acid extraction port, which can adjust the insertion depth according to the liquid level and extract the acid solution in time, while maintaining the pH stability of the cathode area, and can also clean the cathode by adjusting the acid extraction rate.

[0024] 3. The reactor provided by the present invention can enlarge the processing capacity of a single electrode group to 1m 3 / h, the floor space is less than 2 square meters, the investment cost is less than 50,000 yuan, the energy consumption is less than 3.0kw·h / kgCaCO3, and the softening efficiency is greater than 200g / (m 2 h), energy consumption and softening efficiency are both in the leading position in the same field.

[0025] 4. The present invention solves the problem of insufficient hydroxide utilization in existing electrochemical water softening technology through the innovative combination of cathode liquid through-hole design and multi-electrode group parallel operation. This design makes full use of hydroxide and improves the uniformity and efficiency of the reaction. By realizing multi-component parallel operation, the application scenarios of the equipment are broadened, and it is particularly suitable for the treatment of large flow and high hardness water. The present invention shows significant advantages in structural flexibility, economy and stability, and provides a new solution for the industrial application of electrochemical water softening technology. It is a breakthrough innovation in the field of water treatment technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the overall structure of the electrode assembly of the present invention;

[0027] Figure 2 is a vertical cross-sectional view of the interior of the electrode assembly of the present invention;

[0028] Figure 3 This is a partial plan view of the electrode assembly cover of the present invention;

[0029] Figure 4is a top view of the base of the electrode assembly of the present invention;

[0030] Figure 5 is a schematic diagram of the operation of a reactor in which a single electrode assembly is provided in Examples 1, 4 and 9 of the present invention;

[0031] Figure 6 is a schematic diagram of the operation of a reactor in which four electrode assemblies are arranged in Examples 2 and 5 of the present invention;

[0032] Figure 7 is a schematic diagram of the operation of a reactor provided with nine electrode assemblies in Examples 3 and 6 of the present invention;

[0033] Figure 8 1 is a schematic diagram of the operation of a reactor with nine electrode assemblies in Example 7 of the present invention where the spacing between elements is too large;

[0034] Fig. 9 This is a schematic diagram of the operation of a reactor with nine electrode assemblies in Example 8 of the present invention where the spacing between the elements is too small;

[0035] Fig.10 This is the effect of increasing the acid extraction ratio on voltage in Example 9 of the present invention.

[0036] In the figure, 1. anode; 2. separator; 3. cathode; 4. base; 5. positive electrode terminal; 6. negative electrode terminal; 7. acid extraction port; 8. first groove; 9. second groove; 10. third groove; 11. cover; 12. fourth groove; 13. fifth groove; 14. sixth groove; 15. water inlet; 16. water outlet; 17 water to be treated; 18. reaction tank; 19. valve. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0038] Unless otherwise specified, the experimental processes of the present invention are all carried out under conventional laboratory conditions, and the raw materials of the present invention can be obtained through common commercial channels.

[0039] The present invention provides a unique electrochemical reactor, wherein multiple electrode groups consisting of cathode-diaphragm-anode are connected in parallel and cathode liquid is connected. Figures 1 to 7As shown, a multi-electrode parallel electrochemical reactor with cathode liquid passing through comprises an outermost reaction tank 18 and multiple electrode assemblies inside, each electrode assembly comprises an innermost anode 1, a screen 2 sleeved on the outer side of the anode 1 for isolating cathode liquid and anode liquid (liquid in the closed area of ​​the anode is regarded as anode liquid, and liquid outside the cathode is regarded as cathode liquid), a cathode 3 on the outer side of the screen 2, a base 4 and a cover 11; the anode 1, the screen 2 and the cathode 3 are arranged in sequence from the center to the outside; a groove is provided on the base 4 for keeping the anode 1, the screen 2 and the cathode 3 fixed when inserted and isolating the cathode liquid from the anode liquid for neutralization; the cover 11 is arranged above the anode 1, the screen 2 and the cathode 3, and a corresponding groove is provided on the cover, corresponding to the groove on the base 4; the acid extraction port 7 is located at the center of the cover 11, passes through the cover 11 and reaches the anode area included in the anode 1 (the closed area included in the anode 1 is regarded as the anode area); the positive electrode terminal 5 is inserted on the cover 11 and connected to the anode 1; the negative electrode terminal 6 is inserted on the cover 11 and connected to the cathode 3.

[0040] When multiple groups of electrode assemblies are operated in parallel, they need to be placed in parallel inside the reaction tank 18. When a single assembly is in operation, the pH value gradually decreases from near to far, but because the distal alkaline area (the area greater than 25 cm from the cathode is called the distal area) overlaps when multiple assemblies are in operation, the pH value at the superposition increases and is greater than 9.3 required for homogeneous nucleation. At this time, the distance between the electrode assemblies is 0.05m to 0.5m, and the distance between the electrode assemblies and the reaction tank 18 is 0.05m to 0.3m. If it is too close, OH - Waste accumulation causes insufficient diffusion, and if it is too far, it will exceed the OH - Effective action distance, loses parallel effect.

[0041] The height of the anode 1, the screen 2 and the cathode 3 of a single electrode assembly is the same, ranging from 0.01m to 5m; the interval between the anode 1 and the cathode 3 is less than 0.1m to ensure the compactness of the structure and the electrolysis efficiency; since the interval between the anode 1 and the cathode 3 is determined, the floor space of the assembly is mainly determined by the vertical area of ​​the anode 1. If the vertical area of ​​the anode is too small, the processing capacity of the reactor will be weakened. If the vertical area of ​​the anode is too large, the anode area will occupy too much of the effective volume of the reaction tank, resulting in more acid production. Taking a circle as an example, the reasonable anode radius range is 0.05m to 0.5m.

[0042] The acid extraction port 7 is connected to an external pump through a pipeline, and the acid generated during the electrolysis process in the anode 1 area is continuously extracted to maintain the electrolysis efficiency. During normal operation, the acid extraction flow rate is less than 50L / h; when the cathode scale layer needs to be cleaned, the acid extraction flow rate can be temporarily set to greater than 100L / h, and the scale on the cathode surface will fall off with the water flow.

[0043] The cathode 3 is made of metal, which is selected from one of pure metals or alloys, including but not limited to stainless steel, iron, copper, titanium, nickel, and aluminum. When the cathode is made of stainless steel, its mesh number is 5 to 500 meshes or the aperture range is 0.025 to 4.5 mm.

[0044] The separator 2 includes but is not limited to one of an ion exchange membrane, a nylon separator, a polytetrafluoroethylene mesh, and a vinylidene fluoride membrane. When the separator is a nylon separator, its mesh number is ≥ 200 meshes or the pore size range is 0.001 to 40 μm.

[0045] The material of the anode 1 is metal, and the metal is selected from one of pure metals or alloys, including but not limited to ruthenium, iridium, titanium, iron, copper, aluminum, titanium, zinc, nickel, and stainless steel.

[0046] The geometric shapes of the anode 1, the separator 2 and the cathode 3 include but are not limited to cylindrical, elliptical cylindrical, polygonal cylindrical, linear and diamond shapes.

[0047] The current density of the electrochemical system is 1-1000 mA / cm 2 .

[0048] Example 1

[0049] like Figures 1 to 5 As shown, the present invention provides a multi-electrode parallel electrochemical reactor with cathode liquid passing through, including a reaction tank 18, in which an electrode assembly is arranged; the electrode assembly includes an anode 1, a separator 2, a cathode 3, a base 4 and a cover 11.

[0050] The cathode 3 is arranged around the outer periphery of the anode 1, and the separator 2 is arranged between the anode 1 and the cathode 3 to separate the cathode liquid from the anode liquid. The base 4 and the cover 11 are respectively installed at the bottom and top of the anode 1, the separator 2, and the cathode 3. The base 4 and the cover 11 are respectively provided with grooves for installing the anode 1, the separator 2, and the cathode 3. The base 4 is installed at the bottom of the anode 1, the separator 2, and the cathode 3, and the cover 11 is installed at the top of the anode 1, the separator 2, and the cathode 3.

[0051] Specifically, the top of the base 4 is provided with a first groove 8 for mounting the anode 1, a second groove 9 for mounting the screen 2, and a third groove 10 for mounting the cathode 3. The bottom of the cover 11 is provided with a fourth groove 12 for mounting the anode 1, a fifth groove 13 for mounting the screen 2, and a sixth groove 14 for mounting the cathode 3.

[0052] A positive electrode terminal 5 is provided on the anode 1 , and the positive electrode terminal 5 passes through the cover 11 and is connected to the anode 1 ; a negative electrode terminal 6 is provided on the cathode 3 , and the negative electrode terminal 6 passes through the cover 11 and is connected to the cathode 3 .

[0053] The electrode assembly also includes an acid extraction port 7, which is arranged at the center of the cover 11. One end of the acid extraction port 7 passes through the center of the cover 11 and extends into the anode area of ​​the anode 1. The other end of the acid extraction port 7 is connected to an external pump through a pipeline.

[0054] One or more water inlets 15 and one or more water outlets 16 are arranged on the outer wall of the reaction tank 18, and the water inlets 15 and the water outlets 16 are both connected to the interior of the reaction tank 18; preferably, the water inlets 15 and the water outlets 16 are arranged on opposite sides of the reaction tank 18; more preferably, at least one water outlet 16 is arranged on the outer wall of the reaction tank 18 downstream near the bottom of the reaction tank 18, and a valve 19 is installed on the downstream side wall of the reaction tank 18.

[0055] The distance between the electrode assembly and the side wall of the reaction tank 18 is set to 0.05m to 0.3m; the heights of the anode 1, the screen 2 and the cathode 3 are the same, set to 0.01m to 5m. The distance between the anode 1 and the cathode 3 is less than 0.1m. The current density of the electrochemical system in the reaction tank 18 is 1 to 1000mA / cm 2 The anode 1, the separator 2 and the cathode 3 are cylindrical in shape, and the radius of the anode 1 is set to 0.05m to 0.5m. In addition, the anode 1, the separator 2 and the cathode 3 can also be set to other shapes, including but not limited to elliptical cylinder, polygonal cylinder, linear shape, and diamond shape.

[0056] The anode 1 is made of a metal material; optionally, the metal material is one of pure metals or alloys, including but not limited to ruthenium, iridium, titanium, iron, copper, aluminum, titanium, zinc, nickel, and stainless steel.

[0057] The material of the separator 2 includes but is not limited to one of ion exchange membrane, nylon separator, polytetrafluoroethylene mesh, and vinylidene fluoride membrane; wherein, when a nylon separator is selected as the separator 2, the mesh number of the nylon separator is ≥ 200 meshes or the pore size of the nylon separator is 0.001 to 40 μm.

[0058] The cathode 3 is made of a metal material; optionally, the metal material is a pure metal or an alloy, including but not limited to stainless steel, iron, copper, titanium, nickel, and aluminum.

[0059] Example 2

[0060] like Figures 1 to 4 As shown in 7, the present invention provides a multi-electrode parallel electrochemical reactor with cathode liquid passing through, including a reaction tank 18, in which four electrode assemblies are arranged in parallel as a group, and two groups of electrode assemblies are arranged in parallel in the reaction tank 18; the electrode assembly includes an anode 1, a separator 2, a cathode 3, a base 4 and a cover 11.

[0061] The cathode 3 is arranged around the outer periphery of the anode 1, and the separator 2 is arranged between the anode 1 and the cathode 3 to separate the cathode liquid from the anode liquid. The base 4 and the cover 11 are respectively installed at the bottom and top of the anode 1, the separator 2, and the cathode 3. The base 4 and the cover 11 are respectively provided with grooves for installing the anode 1, the separator 2, and the cathode 3. The base 4 is installed at the bottom of the anode 1, the separator 2, and the cathode 3, and the cover 11 is installed at the top of the anode 1, the separator 2, and the cathode 3.

[0062] Specifically, the top of the base 4 is provided with a first groove 8 for mounting the anode 1, a second groove 9 for mounting the screen 2, and a third groove 10 for mounting the cathode 3. The bottom of the cover 11 is provided with a fourth groove 12 for mounting the anode 1, a fifth groove 13 for mounting the screen 2, and a sixth groove 14 for mounting the cathode 3.

[0063] A positive electrode terminal 5 is provided on the anode 1 , and the positive electrode terminal 5 passes through the cover 11 and is connected to the anode 1 ; a negative electrode terminal 6 is provided on the cathode 3 , and the negative electrode terminal 6 passes through the cover 11 and is connected to the cathode 3 .

[0064] The electrode assembly also includes an acid extraction port 7, which is arranged at the center of the cover 11. One end of the acid extraction port 7 passes through the center of the cover 11 and extends into the anode area of ​​the anode 1. The other end of the acid extraction port 7 is connected to an external pump through a pipeline.

[0065] One or more water inlets 15 and one or more water outlets 16 are arranged on the outer wall of the reaction tank 18, and the water inlets 15 and the water outlets 16 are both connected to the interior of the reaction tank 18; preferably, the water inlets 15 and the water outlets 16 are arranged on opposite sides of the reaction tank 18; more preferably, at least one water outlet 16 is arranged on the outer wall of the reaction tank 18 downstream near the bottom of the reaction tank 18, and a valve 19 is installed on the downstream side wall of the reaction tank 18.

[0066] The distance between the electrode assembly and the side wall of the reaction tank 18 is set to 0.05m to 0.3m, and the distance between two adjacent electrode assemblies is 0.05m to 0.5m. The heights of the anode 1, the separator 2 and the cathode 3 are the same, set to 0.01m to 5m. The distance between the anode 1 and the cathode 3 is less than 0.1m. The current density of the electrochemical system in the reaction tank 18 is 1 to 1000mA / cm 2 The anode 1, the separator 2 and the cathode 3 are cylindrical in shape, and the radius of the anode 1 is set to 0.05m to 0.5m. In addition, the anode 1, the separator 2 and the cathode 3 can also be set to other shapes, including but not limited to elliptical cylinder, polygonal cylinder, linear shape, and diamond shape.

[0067] The anode 1 is made of a metal material; optionally, the metal material is one of pure metals or alloys, including but not limited to ruthenium, iridium, titanium, iron, copper, aluminum, titanium, zinc, nickel, and stainless steel.

[0068] The material of the separator 2 includes but is not limited to one of ion exchange membrane, nylon separator, polytetrafluoroethylene mesh, and vinylidene fluoride membrane; wherein, when a nylon separator is selected as the separator 2, the mesh number of the nylon separator is ≥ 200 meshes or the pore size of the nylon separator is 0.001 to 40 μm.

[0069] The cathode 3 is made of a metal material; optionally, the metal material is a pure metal or an alloy, including but not limited to stainless steel, iron, copper, titanium, nickel, and aluminum.

[0070] Example 3

[0071] like Figures 1 to 4 As shown in Figure 6, the present invention provides a multi-electrode parallel electrochemical reactor with cathode liquid passing through, including a reaction tank 18, in which nine electrode assemblies are arranged in parallel as a group, and three groups of electrode assemblies are arranged in parallel in the reaction tank 18; the electrode assembly includes an anode 1, a separator 2, a cathode 3, a base 4 and a cover 11.

[0072] The cathode 3 is arranged around the outer periphery of the anode 1, and the separator 2 is arranged between the anode 1 and the cathode 3 to separate the cathode liquid from the anode liquid. The base 4 and the cover 11 are respectively installed at the bottom and top of the anode 1, the separator 2, and the cathode 3. The base 4 and the cover 11 are respectively provided with grooves for installing the anode 1, the separator 2, and the cathode 3. The base 4 is installed at the bottom of the anode 1, the separator 2, and the cathode 3, and the cover 11 is installed at the top of the anode 1, the separator 2, and the cathode 3.

[0073] Specifically, the top of the base 4 is provided with a first groove 8 for mounting the anode 1, a second groove 9 for mounting the screen 2, and a third groove 10 for mounting the cathode 3. The bottom of the cover 11 is provided with a fourth groove 12 for mounting the anode 1, a fifth groove 13 for mounting the screen 2, and a sixth groove 14 for mounting the cathode 3.

[0074] A positive electrode terminal 5 is provided on the anode 1 , and the positive electrode terminal 5 passes through the cover 11 and is connected to the anode 1 ; a negative electrode terminal 6 is provided on the cathode 3 , and the negative electrode terminal 6 passes through the cover 11 and is connected to the cathode 3 .

[0075] The electrode assembly also includes an acid extraction port 7, which is arranged at the center of the cover 11. One end of the acid extraction port 7 passes through the center of the cover 11 and extends into the anode area of ​​the anode 1. The other end of the acid extraction port 7 is connected to an external pump through a pipeline.

[0076] One or more water inlets 15 and one or more water outlets 16 are arranged on the outer wall of the reaction tank 18, and the water inlets 15 and the water outlets 16 are both connected to the interior of the reaction tank 18; preferably, the water inlets 15 and the water outlets 16 are arranged on opposite sides of the reaction tank 18; more preferably, at least one water outlet 16 is arranged on the outer wall of the reaction tank 18 downstream near the bottom of the reaction tank 18, and a valve 19 is installed on the downstream side wall of the reaction tank 18.

[0077] The distance between the electrode assembly and the side wall of the reaction tank 18 is set to 0.05m to 0.3m, and the distance between two adjacent electrode assemblies is 0.05m to 0.5m. The heights of the anode 1, the separator 2 and the cathode 3 are the same, set to 0.01m to 5m. The distance between the anode 1 and the cathode 3 is less than 0.1m. The current density of the electrochemical system in the reaction tank 18 is 1 to 1000mA / cm 2 The anode 1, the separator 2 and the cathode 3 are cylindrical in shape, and the radius of the anode 1 is set to 0.05m to 0.5m. In addition, the anode 1, the separator 2 and the cathode 3 can also be set to other shapes, including but not limited to elliptical cylinder, polygonal cylinder, linear shape, and diamond shape.

[0078] The anode 1 is made of a metal material; optionally, the metal material is one of pure metals or alloys, including but not limited to ruthenium, iridium, titanium, iron, copper, aluminum, titanium, zinc, nickel, and stainless steel.

[0079] The material of the separator 2 includes but is not limited to one of ion exchange membrane, nylon separator, polytetrafluoroethylene mesh, and vinylidene fluoride membrane; wherein, when a nylon separator is selected as the separator 2, the mesh number of the nylon separator is ≥ 200 meshes or the pore size of the nylon separator is 0.001 to 40 μm.

[0080] The cathode 3 is made of a metal material; optionally, the metal material is a pure metal or an alloy, including but not limited to stainless steel, iron, copper, titanium, nickel, and aluminum.

[0081] Example 4

[0082] The multi-electrode parallel electrochemical reactor with cathode liquid provided in Example 1 is used to treat the treated water 17 (containing Ca 2+ Mg 2+ The simulated water was treated to achieve the removal of calcium and magnesium ions and resource recovery. Before treatment, the total hardness of the simulated water was 500mg / L (calculated as CaCO3); the calcium ion concentration was 120mg / L, the hardness was 300mg / L, the magnesium ion concentration was 48mg / L, the hardness was 200mg / L, the alkalinity was 9mmol / L, and the inlet pH was 8.4.

[0083] like Figure 1 and 5As shown, in this embodiment, a stainless steel wire mesh with a mesh number of 10 is selected as the cathode 3, a nylon mesh with a mesh number of 400 is selected as the mesh 2, and a ruthenium-iridium-titanium mesh is selected as the anode 1. The anode 1, the mesh 2, and the cathode 3 are fixedly installed between the base 4 and the cover 11, and then the electrode assembly is placed in the reaction tank 18. The water to be treated 17 is introduced into the reaction tank 18 from the water inlet 15, and then flows out through the water outlet 16 after the treatment is completed. During the water treatment, the residence time of the water to be treated 17 in the reaction tank 18 is set to 10 minutes, and the current density of the cathode 3 is adjusted to 10mA / cm 2 The flow rate of the external pump to extract acid is 1 / 10 of the inlet flow rate, and the distance between the cathode 3 and the inner wall of the reaction tank 18 is set to 10 cm. After the outlet water is stable, the inlet and outlet water quality is measured, and the test results are shown in Table 1. After the reaction, the valve 19 is opened to discharge the solid-liquid mixture at the bottom of the reaction tank 18. The energy consumption of the whole process is less than 3.0 kw·h / kgCaCO3.

[0084] Table 1 Calcium and magnesium hardness and pH value in solution

[0085]

[0086] Excessive concentration of calcium and magnesium ions in water can lead to scaling, which is one of the difficult problems in the field of water treatment. Therefore, the concentration of calcium and magnesium ions (hardness) in water is usually used to evaluate the scaling tendency of water bodies. The lower the total hardness, the less likely it is to scale. - Will be with Ca 2+ Mg 2+ 、HCO3 - Reaction, thereby removing the hardness of water, so usually the OH in the solution - The more the amount, that is, the higher the pH value, the lower the hardness in the water. The results in Table 1 show that after being treated by the reactor provided by the present invention, the removal rates of calcium and magnesium ions in the effluent water solution reached more than 95%, and the pH of the water solution increased from 8.4 to 11.6.

[0087] Example 5

[0088] The multi-electrode parallel electrochemical reactor with cathode liquid provided in Example 2 is used to treat the treated water 17 (containing Ca 2+ Mg 2+ The simulated water was treated with four electrochemical components and a reaction tank 18 in the manner of Example 4. Before treatment, the total hardness of the simulated water was 5750 mg / L (calculated as CaCO3); wherein the calcium ion concentration was 300 mg / L, the hardness was 750 mg / L, the magnesium ion concentration was 1200 mg / L, the hardness was 5000 mg / L, the alkalinity was 3 mmol / L, and the inlet pH was 8.4.

[0089] like Figure 1 and 6 As shown, in this embodiment, a stainless steel wire mesh with a mesh number of 10 is selected as the cathode 3, a nylon mesh with a mesh number of 400 is selected as the mesh 2, and a ruthenium-iridium-titanium mesh is selected as the anode 1. The water to be treated 17 is introduced into the reaction tank 18 from the water inlet 15, and then flows out through the water outlet 16 after the treatment is completed. During the water treatment, the residence time of the water to be treated 17 in the reaction tank 18 is set to 10 minutes, the distance between the cathodes 3 and the distance from the reactor wall are set to 10 cm, and the current density of the four cathodes 3 is adjusted to 10 mA / cm 2 The flow rate of the external pump to extract acid is 1 / 10 of the inlet flow rate. After the outlet water is stable, the inlet and outlet water quality is measured, and the test results are shown in Table 2. After the reaction, the valve 19 is opened to discharge the solid-liquid mixture at the bottom of the reaction tank 18. The energy consumption of the whole process is less than 3.0kw·h / kg CaCO3.

[0090] Table 2 Calcium and magnesium hardness and pH value in solution

[0091]

[0092] The results in Table 2 show that after being treated by the reactor provided by the present invention, the removal rates of calcium and magnesium ions in the effluent water solution both reached more than 34.8%, and the pH of the water solution increased from 8.4 to 10.3.

[0093] Example 4 of the present invention uses a reactor with a single electrode assembly to treat simulated water with a total hardness of 500 mg / L, and the removal rates of calcium and magnesium ions are both over 95%, indicating that the reactor provided by the present invention can cause hardness ions such as calcium and magnesium in water to be deposited in the cathode region, thereby achieving the effect of water softening. Example 5 increases the total hardness of the simulated water to 5750 mg / L, and only sets four electrode assemblies to treat high-hardness simulated water, and the removal rates of calcium and magnesium ions are both over 34.8%. Correspondingly, Example 6 expands the reaction system of the reactor of the present invention, increases the number of electrode assemblies to 9 according to different water hardnesses and water flow rates, and treats simulated water with a total hardness of 5750 mg / L, with the removal rates of calcium and magnesium ions both reaching over 78%.

[0094] Before using the reactor of the present invention, according to different water hardness and water flow, the corresponding cathode area can be calculated according to the water softening rate that should be achieved in theory, and then the number of components can be inferred according to the cathode area. Taking the inlet water hardness of 1000mg / L and the flow rate of 100L / h as an example, if you want to remove more than 70% of the hardness, the calculation formula for the hardness that needs to be processed is as follows:

[0095] Hardness to be treated = inlet water hardness × flow rate × removal rate = 1000 mg / L × 100 L / h × 0.7 = 70 g / h

[0096] The water softening rate of the electrode assembly provided by the present invention is generally 200g / (m 2 ·h), the total area is calculated as follows:

[0097]

[0098] If the cathode area of ​​a single component is set to 0.04m 2 , the calculation formula for the number of electrode assemblies required is as follows:

[0099]

[0100] The calculation shows that 8.75 electrode assemblies are needed, that is, 9 electrode assemblies of this size. The present invention can flexibly adjust the number of electrode groups according to the processing volume requirements, adapt to the water treatment needs of industrial scale, and effectively reduce the operating cost.

[0101] Example 6

[0102] The multi-electrode parallel electrochemical reactor with cathode liquid provided in Example 3 is used to treat the treated water 17 (containing Ca 2+ Mg 2+ The simulated water was treated with 9 electrochemical components and the reaction tank 18 in the manner of Example 4. Before treatment, the total hardness of the simulated water was 5750 mg / L (calculated as CaCO3); wherein the calcium ion concentration was 300 mg / L, the hardness was 750 mg / L, the magnesium ion concentration was 1200 mg / L, the hardness was 5000 mg / L, the alkalinity was 3 mmol / L, and the inlet pH was 8.4.

[0103] like Figure 7 As shown, in this embodiment, a stainless steel wire mesh with a mesh number of 10 is selected as the cathode 3, a nylon mesh with a mesh number of 400 is selected as the mesh 2, and a ruthenium-iridium-titanium mesh is selected as the anode 1. The water to be treated 17 is introduced into the reaction tank 18 from the water inlet 15, and then flows out through the water outlet 16 after the treatment is completed. During the water treatment, the residence time of the water to be treated 17 in the reaction tank 18 is set to 10 minutes, and the current density of the nine cathodes 3 is adjusted to 10 mA / cm 2 The flow rate of the external pump to extract acid is 1 / 10 of the inlet flow rate, and the distance between the cathodes 3 and the distance from the reactor wall are set to 10 cm. After the effluent is stable, the inlet and outlet water quality is measured, and the test results are shown in Table 3. After the reaction, the valve 19 is opened to discharge the solid-liquid mixture at the bottom of the reaction tank 18. The energy consumption of the whole process is less than 3.0 kw·h / kg CaCO3.

[0104] Table 3 Calcium and magnesium hardness and pH value in solution

[0105]

[0106] The results in Table 3 show that after being treated by the reactor provided by the present invention, the removal rates of calcium and magnesium ions in the effluent water solution both reached more than 78%, and the pH of the water solution increased from 8.4 to 11.1.

[0107] Example 7

[0108] This embodiment is basically the same as embodiment 6, using a multi-electrode parallel electrochemical reactor with cathode liquid passing through to treat water 17 (containing Ca 2+ Mg 2+ The simulated water was treated with nine electrochemical components and a reaction tank 18 in the manner of Example 4. However, unlike the reactor provided in Example 6, the spacing between adjacent electrode assemblies and the spacing between the electrode assemblies and the reactor wall were increased. When untreated, the total hardness of the simulated water was 5750 mg / L (calculated as CaCO3); wherein the calcium ion concentration was 300 mg / L, the hardness was 750 mg / L, the magnesium ion concentration was 1200 mg / L, the hardness was 5000 mg / L, the alkalinity was 3 mmol / L, and the inlet pH was 8.4.

[0109] like Figure 8 As shown, in this comparative example, a stainless steel wire mesh with a mesh number of 10 is selected as the cathode 3, a nylon mesh with a mesh number of 400 is selected as the mesh 2, and a ruthenium-iridium-titanium mesh is selected as the anode 1. The water to be treated 17 is introduced into the reaction tank 18 from the water inlet 15, and then flows out through the water outlet 16 after the treatment is completed. During the water treatment, the residence time of the water to be treated 17 in the reaction tank 18 is set to 10 minutes, and the current density of the nine cathodes 3 is adjusted to 10 mA / cm 2 The flow rate of the external pump to extract acid is 1 / 10 of the inlet flow rate, and the distance between the cathodes and the distance from the reactor wall is set to 50 cm. After the effluent is stable, the inlet and outlet water quality is measured, and the test results are shown in Table 4. After the reaction, the valve 19 is opened to discharge the solid-liquid mixture at the bottom of the reaction tank 18. The energy consumption of the whole process is still less than 3.0 kw·h / kg CaCO3.

[0110] Table 4 Calcium and magnesium hardness and pH value in solution

[0111]

[0112] The results in Table 4 show that after being treated by the reactor provided by the present invention, the removal rates of calcium and magnesium ions in the effluent water solution were only 55%, and the pH of the water solution was increased from 8.4 to 10.7.

[0113] Example 8

[0114] This embodiment is basically the same as embodiment 6, using a multi-electrode parallel electrochemical reactor with cathode liquid passing through to treat water 17 (containing Ca 2+ Mg 2+The simulated water was treated with nine electrochemical components and a reaction tank 18 in the manner of Example 4. However, unlike the reactor provided in Example 6, the spacing between adjacent electrode assemblies and the spacing between the electrode assemblies and the reactor wall were shortened. Without treatment, the total hardness of the simulated water was 5750 mg / L (calculated as CaCO3); wherein the calcium ion concentration was 300 mg / L, the hardness was 750 mg / L, the magnesium ion concentration was 1200 mg / L, the hardness was 5000 mg / L, the alkalinity was 3 mmol / L, and the inlet pH was 8.4.

[0115] like Fig. 9 As shown, in this embodiment, a stainless steel wire mesh with a mesh number of 10 is selected as the cathode 3, a nylon mesh with a mesh number of 400 is selected as the mesh 2, and a ruthenium-iridium-titanium mesh is selected as the anode 1. The water to be treated 17 is introduced into the reaction tank 18 from the water inlet 15, and then flows out through the water outlet 16 after the treatment is completed. During the water treatment, the residence time of the water to be treated 17 in the reaction tank 18 is set to 10 minutes, the distance between the cathodes and the distance from the reactor wall are set to 5 cm, and the current density of the nine cathodes 3 is adjusted to 10 mA / cm 2 The flow rate of the external pump to extract acid is 1 / 10 of the inlet flow rate. After the outlet water is stable, the water quality of the inlet and outlet water is measured, and the test results are shown in Table 5. After the reaction, the valve 19 is opened to discharge the solid-liquid mixture at the bottom of the reaction tank 18. The energy consumption of the whole process is higher than 5.0kw·h / kg CaCO3.

[0116] Table 5 Calcium and magnesium hardness and pH value in solution

[0117]

[0118] The results in Table 5 show that after being treated by the reactor provided by the present invention, the removal rates of calcium and magnesium ions in the effluent water solution were only 54.8%, and the pH of the water solution was increased from 8.4 to 10.8.

[0119] Examples 6 to 8 investigated the effects of the spacing between the electrode assemblies and between the electrode assemblies and the reaction tank 18 on the removal rate of calcium and magnesium ions, OH and the removal rate of ions in the water to be treated 17 by the reactor of the present invention. - The results show that when the spacing is at an appropriate distance, the OH utilization of the entire system -The utilization rate (low energy consumption, high water softening rate) is the highest. Too large a spacing will increase the energy consumption of the entire process. Too large or too small a spacing between the electrode assembly and the electrode assembly and between the electrode assembly and the reaction tank 18 will affect the calcium and magnesium ion removal rate, causing the calcium and magnesium ion removal rate to decrease. Compared with the calcium and magnesium ion removal rates of Examples 6 to 8, under the same conditions, the calcium and magnesium ion removal rates of Example 6 can reach more than 78%, while the calcium and magnesium ion removal rates of Examples 7 to 8 do not exceed 55%. Further experimental investigations found that when the electrode assembly and the electrode assembly and the electrode assembly and the reaction tank 18 are respectively set to 0.1m to 0.3m (more preferably, they are respectively set to 0.1m to 0.15m), the OH of the reactor of the present invention - The utilization rate and calcium and magnesium ion removal rate are the best.

[0120] Example 9

[0121] The multi-electrode parallel electrochemical reactor with cathode liquid provided in Example 1 is used to treat the treated water 17 (containing Ca 2+ Mg 2+ The simulated water was treated to achieve the removal of calcium and magnesium ions and resource recovery. Before treatment, the total hardness of the simulated water was 500mg / L (calculated as CaCO3); the calcium ion concentration was 120mg / L, the hardness was 300mg / L, the magnesium ion concentration was 48mg / L, the hardness was 200mg / L, the alkalinity was 9mmol / L, and the inlet pH was 8.1.

[0122] like Figure 5 As shown, in this embodiment, a stainless steel wire mesh with a mesh number of 10 is selected as the cathode 3, a nylon mesh with a mesh number of 400 is selected as the mesh 2, and a ruthenium-iridium-titanium mesh is selected as the anode 1. The anode 1, the mesh 2, and the cathode 3 are fixedly installed between the base 4 and the cover 11, and then the electrode assembly is placed in the reaction tank 18. The water to be treated 17 is introduced into the reaction tank 18 from the water inlet 15, and then flows out through the water outlet 16 after the treatment is completed. During the water treatment, the residence time of the water to be treated 17 in the reaction tank 18 is set to 10 minutes, and the current density of the nine cathodes 3 is adjusted to 10mA / cm 2 , the flow rate of the external pump to extract acid is 1 / 10 of the water flow rate. Fig.10 As shown in the figure, the initial voltage is 5V. After running for 180 hours, the component voltage changes and gradually rises to about 5.4V, and a scale layer appears on the outside of the cathode. At this time, the acid extraction ratio is adjusted, and the flow rate of the external pump acid is changed to the same as the water flow rate. At this time, the voltage drops back to 5V. At this time, the scale layer on the cathode side automatically falls off under the disturbance of the water flow, and the voltage returns to the initial state, achieving self-cleaning.

[0123] Voltage is usually used to indicate the stability of the reaction and the scaling of the cathode. When the reaction is run under constant current conditions, the scaling on the cathode surface causes an increase in resistance, thereby increasing the voltage and, in turn, increasing energy consumption. The scale on the cathode is usually removed by reversing the electrode, manually scraping, or ultrasound. This method not only damages the electrode but also requires the reaction to be interrupted. Increasing the acid extraction ratio removes the scale on the cathode surface by flushing with water without interrupting the reaction.

[0124] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A multi-electrode parallel electrochemical reactor with cathode liquid passing through, characterized in that: It comprises a reaction tank (18) having a water inlet (15) and a water outlet (16); a single or multiple groups of electrode assemblies are arranged in the reaction tank (18), the multiple groups of electrode assemblies are arranged in parallel along a first direction, each group of electrode assemblies comprises multiple electrode assemblies arranged in parallel along a second direction, the first direction and the second direction have an angle, and the multiple groups of electrode assemblies are connected in parallel; The electrode assembly comprises an anode (1); a cathode (3) arranged around the outside of the anode (1); a separator (2) arranged between the anode (1) and the cathode (3) and configured to separate the cathode liquid from the anode liquid; a base (4) and a cover (11) having grooves for mounting the anode (1), the separator (2) and the cathode (3) and being mounted on the bottom and top of the anode (1), the separator (2) and the cathode (3) respectively; a positive electrode terminal (5) inserted in the cover (11) and connected to the anode (1); a negative electrode terminal (6) inserted in the cover (11) and connected to the cathode (3); an acid extraction port (7) installed in the center of the cover (11) and penetrating through the cover (11) into the anode region of the anode (1); an external pump configured to extract acid in the anode region, the external pump being connected to the acid extraction port (7) via a pipeline; The spacing between adjacent electrode assemblies is 0.1m to 0.3m, and the spacing between the electrode assembly close to the inner wall of the reaction tank (18) and the reaction tank (18) is 0.1m to 0.3m; The heights of the anode (1), the separator (2) and the cathode (3) are 0.01 m to 5 m.

2. The multi-electrode parallel electrochemical reactor with cathode liquid passing through according to claim 1, characterized in that: During normal operation, the acid extraction flow rate of the external pump is set to be less than 50 L / h; when cleaning the cathode scale layer, the acid extraction flow rate of the external pump is set to be greater than 100 L / h.

3. The multi-electrode parallel electrochemical reactor with cathode liquid passing through according to claim 1, characterized in that: The cathode (3) is made of metal, and the metal is stainless steel, iron, copper, titanium, nickel or aluminum.

4. The multi-electrode parallel electrochemical reactor with cathode liquid passing through according to claim 1, characterized in that: The separator (2) is an ion exchange membrane, a nylon separator, a polytetrafluoroethylene mesh or a vinylidene fluoride membrane.

5. The multi-electrode parallel electrochemical reactor with cathode liquid passing through according to claim 4, characterized in that: The separator (2) is a nylon separator, and the pore size of the nylon separator is not less than 74 μm or 0.001 to 40 μm.

6. The multi-electrode parallel electrochemical reactor with cathode liquid passing through according to claim 1, characterized in that: The anode (1), the separator (2) and the cathode (3) are in the shape of a cylinder, an elliptical cylinder, a polygonal cylinder, a line or a rhombus.

7. The multi-electrode parallel electrochemical reactor with cathode liquid passing through according to claim 1, characterized in that: The anode (1), the separator (2) and the cathode (3) are cylindrical in shape, and the outer diameter of the cylinder is 0.1m to 1m.

8. The multi-electrode parallel electrochemical reactor with cathode liquid passing through according to claim 1, characterized in that: The current density in the reaction tank (18) is 1 to 1000 mA / cm 2 .

9. The multi-electrode parallel electrochemical reactor with cathode liquid passing through according to claim 1, characterized in that: A valve (19) is provided below the reaction tank (18).

10. The multi-electrode parallel electrochemical reactor with cathode liquid passing through according to claim 1, characterized in that: The spacing between adjacent electrode assemblies is 0.1m to 0.15m, and the spacing between the electrode assembly close to the inner wall of the reaction tank (18) and the reaction tank (18) is 0.1m to 0.15m.

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