Electrolytic cell and device for using porous structure to regulate bubbles, and method

Abstract

An electrolytic cell and device for using a porous structure to regulate bubbles, and a method. The electrolytic cell (1) comprises a plurality of parallel electrolytic chambers, each electrolytic chamber comprising a cathode plate (11) and an anode plate (15) on two sides, wherein a separator (13) is provided between the cathode plate and the anode plate; a cathode electrode (12) and an anode electrode (14) are provided on two sides of the separator (13), respectively; and inner porous coalescing members (17) are mounted in the electrolytic chambers between the cathode plate (11) and the cathode electrode (12) and between the anode plate (15) and the anode electrode (14). By means of mounting the inner porous coalescing members (17) in the electrolytic chambers, the turbulence of a liquid is increased, the collision probability of micro-bubbles is improved, and coalescence sites are provided for the micro-bubbles, thereby inducing the coalescence and growth of the micro-bubbles. The problems of the increased voltage of the electrolytic chambers, the high electrolysis energy consumption and the difficulty in further increasing the current density, which are caused by micro-bubble clusters, can be effectively solved, and the foaming of two-phase flows in the chambers can be effectively prevented. Due to the reduction in the micro-bubbles, the efficiency of subsequent gas-liquid separation is greatly improved, and the volume of a gas-liquid separation device is effectively reduced.

Description

Electrolytic cell, electrolytic device and method for regulating bubbles using porous structure Technical Field

[0001] The present invention belongs to the technical field of bubble control in electrolysis technology, and specifically relates to an electrolytic cell, an electrolytic device and a method for controlling bubbles using a porous structure. Background Art

[0002] Due to its mature, efficient and clean technology, electrolysis technology has attracted widespread attention in many electrolysis fields such as electrolytic hydrogen production, electrolytic aluminum, chlor-alkali electrolysis, and electrolytic rare earth. It is a major strategic direction for the world's energy and power transformation and has broad application prospects in industry.

[0003] Generally speaking, the solubility of the product gases in the electrolyte during electrolysis is very low, and they exist almost entirely as bubbles. Furthermore, the bubbles mixed in the electrolyte are very small, with over 90% of them measuring only about 30 to 120 microns in diameter. Especially during high current density electrolysis, the surfaces of the anode and cathode plates of the electrolytic cell are covered with a large number of insulating, microscopic bubbles. This not only reduces the effective working area of ​​the electrodes but also increases the ohmic resistance drop, leading to higher energy consumption. Furthermore, as the current density increases further, the microscopic bubbles in the electrolyte can cause foaming, increasing system operational risks and limiting further increases in current density.

[0004] CN115799532A proposes a method for bubble aggregation and detachment on porous surfaces based on tree-like superaerophilic rails. This method addresses the difficulty in discharging carbon dioxide bubbles from the porous surface of the anode gas diffusion layer of a methanol fuel cell. The method leverages the aerosol affinity and multi-stage bifurcated diffusivity of the superaerophilic rails to rapidly aggregate and grow microbubbles that are difficult to detach from the porous surface, allowing them to easily detach from the porous surface, thereby improving the performance of the methanol fuel cell. However, this device targets a rail structure on the surface of the anode gas diffusion layer substrate, and the rails are complex to manufacture, making them unsuitable for large-scale electrolysis equipment such as hydrogen production.

[0005] Therefore, during the electrolysis process, especially for the electrolysis process at high current density, how to regulate the electrolysis to produce a large number of fine bubbles, thereby inducing bubble aggregation, reducing the ohmic resistance drop generated by the fine bubble group, reducing the electrolysis energy consumption, while reducing the equipment operation risk and increasing the upper limit of current density, is of great significance in industrial applications.

[0006] Summary of the Invention

[0007] The present invention aims to overcome the shortcomings of the prior art by providing an electrolytic cell, electrolysis device, and method that utilize a porous structure to regulate bubbles. The porous structure induces the coalescence of electrolytic bubbles at high current densities, reducing the ohmic drop caused by the clustering of fine bubbles, as well as electrolysis energy consumption and costs. This reduces equipment operating risks, increases the upper limit of current density, and further enhances gas-liquid separation and electrolysis efficiency.

[0008] To achieve the above objectives, the first aspect of the present invention provides an electrolytic cell that utilizes a porous structure to control bubbles and achieve high electrical density, the electrolytic cell comprising a plurality of parallel electrolytic chambers, wherein:

[0009] A single electrolysis chamber includes a cathode plate and an anode plate on both sides; a diaphragm is provided between the cathode plate and the anode plate to prevent mixing of gases generated on both sides of the cathode and anode electrodes; a cathode electrode and an anode electrode are respectively provided on both sides of the diaphragm and between the cathode plate and the anode plate;

[0010] The electrolysis chambers between the cathode plate and the cathode electrode, and between the anode plate and the anode electrode are both equipped with porous agglomeration internal components for inducing the growth of fine bubbles in the gas-liquid mixture generated by electrolysis;

[0011] The electrolytic cell inlet is arranged at the lower end of the electrolytic cell, and the electrolytic cell outlet is arranged at the upper end, including a first outlet and a second outlet respectively arranged on the cathode side and the anode side of the electrolytic cell, for outputting the gas-containing electrolyte on the cathode side and the anode side respectively.

[0012] The present invention is further configured such that the porous agglomerate inner component can be processed by injection molding, braided fiber stacking, and the like.

[0013] The present invention is further configured such that the porous coalescing internal component can be in the form of a three-dimensional porous foam structure, a two-dimensional mesh stacking structure, etc. The porous coalescing internal component is embedded in the electrolysis chamber, with its two ends respectively attached to the plate and the electrode, wherein:

[0014] For porous agglomerated internal components with three-dimensional porous foam structure, they are embedded in the electrolysis chamber as a whole without distinguishing the direction;

[0015] For porous agglomeration internal components with a two-dimensional mesh stacking structure, the bubble coalescence effect is adjusted by adjusting the stacking method and the angle between the stacking layer and the electrolyte flow direction to avoid the formation of ineffective flow channels through which fine bubbles can flow directly.

[0016] Furthermore, the stacking method is adjusted to include staggered distribution of meshes in different stacking layers, or different sizes and shapes of meshes in different stacking layers; the angle θ between the stacking layer and the flow direction of the electrolyte is adjusted to 0°<θ<180°, that is, the stacking layer cannot be parallel to the flow direction of the electrolyte, preferably 60°≤θ≤120°, more preferably θ=90°, that is, the stacking layer is more preferably perpendicular to the flow direction of the electrolyte.

[0017] The present invention is further configured such that the height of the porous coalescing internal component is adjustable, and the bubble size increases with the increase in the height of the porous internal component; the height of the porous coalescing internal component is configured to be 10 to 800 mm, preferably 10 to 200 mm.

[0018] The present invention is further configured such that the porous agglomeration internal components can be provided as a single one or as multiple ones on both sides of the diaphragm in each electrolysis chamber; and the porous agglomeration internal components on the cathode side and the anode side can be provided symmetrically or asymmetrically, and the number of porous agglomeration internal components on both sides can be the same or different.

[0019] In the case where the number of the porous coalescence internal component is only one, the porous coalescence internal component is placed in the middle of the electrolysis chamber; specifically, the installation height is 50% to 70% of the height of the electrolysis chamber.

[0020] In the case where there are multiple porous coalescing internal components, the porous coalescing internal components are arranged in steps along the flow direction of the electrolyte to achieve step-by-step induced coalescence of fine bubbles.

[0021] The present invention is further configured such that the material of the porous agglomeration internal component is a hydrophobic material or the surface is a hydrophobic coating, and its porous structure and its hydrophobic properties can provide sites for the aggregation of bubbles and adhesion and aggregation, thereby inducing the bubbles to aggregate and grow.

[0022] Furthermore, the hydrophobic material or the hydrophobic coating is made of one or more materials selected from polyurethane, polyolefin, polycarbonate, polyamide, polyacrylonitrile, polyester, PTFE, FEP, ETFE, PFA, etc.

[0023] The present invention is further configured such that the porous agglomeration inner component undergoes surface roughening treatment to increase surface roughness, enhance the capture of bubbles by the porous structure, and enhance the aggregation and growth of bubbles.

[0024] The present invention is further configured such that the porous agglomerate internal component is installed inside the electrolysis chamber by interference fit or overfitting between the electrode and the plate through a corrosion-resistant bracket, so as to produce an inductive effect on all gas-liquid mixtures flowing therethrough.

[0025] A second aspect of the present invention provides an electrolysis device for regulating bubbles using a porous structure, the electrolysis device comprising the electrolytic cell, a gas-liquid separation device, and a circulation pump, wherein:

[0026] There are two gas-liquid separation devices, and their mixed liquid inlets are respectively connected to the first outlet and the second outlet of the electrolytic cell, and are used to respectively enter the gas-liquid mixture on the cathode and anode sides of the electrolysis into the gas-liquid separation device for gas-liquid separation; the gas phase outlet of the gas-liquid separation device is connected to a subsequent processing device or is used for direct discharge; there are also two circulation pumps, and the liquid phase outlet of each gas-liquid separation device is respectively connected to the electrolytic cell inlet through a circulation pump, and is used to transport the electrolyte after gas-liquid separation back to the electrolytic cell.

[0027] A third aspect of the present invention provides an electrolysis method using the electrolysis device, the method comprising:

[0028] The electrolyte is pumped into the electrolytic cell from the bottom via a circulation pump, flowing upward within the cell. As the electrolysis reaction proceeds, a large number of microbubbles are generated within the cell. As these microbubbles pass through the porous agglomeration internals, the porous structure increases the turbulence of the liquid, increasing the probability of collisions. It also provides sites for microbubbles to adhere, inducing them to settle and coalesce. The resulting large bubbles, along with the electrolyte, are then discharged into the gas-liquid separation device. After gas-liquid separation, the electrolyte is returned to the electrolytic cell via the circulation pump for recycling, while the gas is discharged from the gas-liquid separation device.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The present invention utilizes the porous structure of the porous agglomeration internal component to increase the turbulence of the liquid in the electrolysis chamber and the collision probability of the microbubbles. At the same time, the porous structure provides agglomeration sites for the microbubbles, inducing the microbubbles to aggregate and grow. It can effectively solve the problems of increased voltage in the electrolysis chamber, high electrolysis energy consumption, and difficulty in further increasing the current density caused by the microbubble group, thereby improving the electrolysis efficiency. At the same time, it can effectively prevent the foaming of the two-phase flow in the chamber and reduce the risk of system operation.

[0031] (2) The porous agglomeration internal component provided in the present invention reduces the presence of microbubbles in the electrolyte, solves the separation difficulties caused by the small diameter of the microbubbles, solves the problems of slow speed and low efficiency of traditional gas-liquid separation in the electrolysis system, and reduces the volume of the gas-liquid separation device.

[0032] (3) The porous agglomerate internal component of the present invention is directly installed between the electrode and the electrode plate, and can replace the supporting layer structure on the electrode plate, such as the mastoid and support rod, to play the role of supporting the electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG1 is a schematic diagram of an electrolysis process flow diagram of the present invention for controlling bubbles using a porous structure;

[0034] FIG2 is a schematic structural diagram of a single electrolysis chamber;

[0035] FIG3 is a schematic diagram of the installation position of the porous agglomeration internal component;

[0036] FIG4 is a schematic structural diagram of the interior of a local electrolysis chamber;

[0037] FIG5 is a schematic diagram of a porous coalesced internal component of a three-dimensional porous foam structure;

[0038] FIG6 is a schematic diagram of gas-liquid flow in a local electrolysis chamber;

[0039] FIG7 is a schematic diagram of the porous structure and agglomeration principle of a partially porous agglomeration internal component;

[0040] FIG8 is a schematic diagram of a porous agglomerated internal component with a two-dimensional network stacking structure. DETAILED DESCRIPTION

[0041] The technical solutions of the present invention are described clearly and completely below with reference to specific embodiments. It should be understood that the embodiments described are only a portion of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of the present invention. Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art.

[0042] Example 1

[0043] As shown in FIG1 , the electrolytic cell and electrolytic device of the present embodiment utilize a three-dimensional foam porous structure to regulate bubbles. The electrolytic cell 1 includes a plurality of parallel electrolytic chambers. As shown in FIG2 , a single electrolytic chamber includes a cathode plate 11 and an anode plate 15 on both sides, that is, an electrolytic chamber is formed between adjacent cathode plates 11 and anode plates 15 in the electrolytic cell 1; a diaphragm 13 is provided between the cathode plate 11 and the anode plate 15 to prevent the gases generated on both sides of the positive and negative electrodes from mixing; both sides of the diaphragm 13 are provided between the cathode plate 11 and the anode plate 15. A cathode electrode 12 and an anode electrode 14 are respectively provided with a diaphragm 13; a porous agglomeration internal component 17 is installed in the electrolysis chamber between the cathode plate 11 and the cathode electrode 12, and between the anode plate 15 and the anode electrode 14, for inducing the growth of fine bubbles in the gas-liquid mixture generated by electrolysis; an electrolytic cell inlet 16 is provided at the lower end of the electrolytic chamber, and an electrolytic cell outlet is provided at the upper end, including a first outlet 18 and a second outlet 19 respectively provided on the cathode side and the anode side of the electrolytic chamber, for respectively outputting the gas-containing electrolyte on the cathode and anode sides.

[0044] Furthermore, as shown in FIG2 and FIG3, the cross-sectional diameter of the electrolysis chamber in this embodiment is 900 cm, and the current density is 5000 A / m 2 The distance between the cathode plate 11 and the cathode electrode 12, and the distance between the anode plate 15 and the anode electrode 14 are both 2 mm; the porous agglomeration internal components 17 respectively arranged on the cathode side and the anode side are used to induce the product bubbles on the cathode and anode sides to coalesce and grow, respectively. Two porous agglomeration internal components 17 are provided in each electrolysis chamber to realize the step-by-step induced coalescence of electrolytic fine bubbles.

[0045] Preferably, the height of the porous agglomeration internal component 17 is 60 mm and the width is 2 mm. Two porous agglomeration internal components are respectively installed at heights of 300 cm and 700 cm from the bottom of the electrolysis chamber.

[0046] Furthermore, as shown in FIG4 and FIG5 , the porous agglomeration inner member 17 is a three-dimensional porous foam structure produced by injection molding and is embedded in the electrolysis chamber.

[0047] Furthermore, the porous coalescing internal member 17 is made of a hydrophobic material, as shown in Figure 7. Its porous structure and hydrophobic properties provide sites for bubble aggregation and adhesion, thereby inducing bubble aggregation and growth. Furthermore, the porous coalescing internal member 17 undergoes a surface roughening treatment to increase surface roughness, enhance the porous structure's ability to capture bubbles, and strengthen bubble aggregation and growth.

[0048] Furthermore, the porous agglomeration internal component 17 is installed inside the electrolysis chamber through interference fit with a corrosion-resistant bracket.

[0049] Furthermore, the porous agglomeration internal component 17 is directly installed between the electrode and the electrode plate to support the electrode, and there is no need to use a mastoid support layer structure on the electrode plate.

[0050] Furthermore, the electrolysis device includes the electrolytic cell 1, the first gas-liquid separation device 2-1, the first circulation pump 3-1, the second gas-liquid separation device 2-2 and the second circulation pump 3-2, wherein:

[0051] The mixed liquid inlet 21 of the first and second gas-liquid separation devices are respectively connected to the first outlet 18 and the second outlet 19 of the electrolytic cell 1 through pipelines, and are used to allow the electrolyzed gas-liquid mixture on the cathode and anode sides to enter the gas-liquid separation device for gas-liquid separation; the gas phase outlet 22 of the first and second gas-liquid separation devices is connected to the subsequent processing device through a pipeline or is directly discharged; the liquid phase outlet 23 of the first and second gas-liquid separation devices is respectively connected to the first circulation pump 3-1 and the second circulation pump 3-2 through a pipeline, and is connected to the electrolytic cell inlet 16, and is used to transport the electrolyte after gas-liquid separation back to the electrolytic cell 1.

[0052] The electrolysis method and principle of the electrolysis device using the three-dimensional foam porous structure to control bubbles are as follows:

[0053] The first circulation pump 3-1 and the second circulation pump 3-2 pump the electrolyte from the bottom of the electrolytic cell 1, and the electrolyte flows from bottom to top in the electrolytic cell 1. As the electrolysis reaction proceeds, a large number of fine bubbles are generated in the electrolytic cell 1. When the fine bubbles pass through the porous coalescing internal component 17, the porous structure increases the turbulence of the liquid, increases the collision probability of the fine bubbles, and provides sites for the fine bubbles to adhere, inducing the fine bubbles to stay and coalesce to form large bubbles. When the large bubbles pass through the upper layer of porous coalescing internal component 17, they are sheared and broken to cause disturbance, continue to coalesce and carry away some of the bubbles that remain above, and quickly induce the coalescence of the fine bubbles without causing the retention of excessively large bubbles. Finally, the large bubbles are discharged together with the electrolyte to the first gas-liquid separation device 2-1 and the second gas-liquid separation device 2-2. After further separation by the gas-liquid separation device, the electrolyte passes through the first circulation pump 3-1 and the second circulation pump 3-2 and returns to the electrolytic cell 1 for recycling, and the gas is discharged from the gas outlet of the gas-liquid separation device.

[0054] The electrolysis device was used to electrolyze the electrolyte of 30 wt% potassium hydroxide solution to generate hydrogen and oxygen. The electrolyte inlet flow rate was set to 0.5m 3 / h. Due to the use of two porous agglomeration internal components, this embodiment can greatly reduce the number of fine bubbles in the electrolysis chamber, thereby reducing the electrolysis chamber voltage, improving the electrolysis efficiency, reducing the system operation risk, and increasing the current density upper limit; according to testing, the gas holdup at the top of the electrolysis chamber is about 18%, and the bubble size is 200μm~20mm.

[0055] Example 2

[0056] The configuration of this embodiment is basically the same as that of embodiment 1, with the only difference being that the porous agglomeration inner component 17 is formed by fiber weaving. Specifically, the porous agglomeration inner component 17 is formed by a stacking structure of several layers of two-dimensional mesh fiber layers. As shown in FIG8 , this embodiment uses three layers of two-dimensional mesh fiber layers 171, 172, and 173 to stack to obtain the porous agglomeration inner component 17, and the mesh structures of different layers are cross-distributed to prevent the formation of invalid flow channels through which small bubbles can flow directly. The installation angle of the two-dimensional mesh fiber layer is perpendicular to the flow direction of the electrolyte in the electrolysis chamber.

[0057] The operating conditions of the electrolysis device in this embodiment are the same as those in Example 1. According to testing, under these conditions, the gas holdup at the top of the electrolysis chamber is about 26%, and the bubble size is 20 μm to 30 mm.

[0058] Comparative Example 1

[0059] This comparative example has essentially the same setup as Examples 1-2, differing only in that the porous agglomerating internal member 17 is omitted, and only a conventional electrolysis device is employed. The electrolysis device also operates under the same conditions as Examples 1-2. Testing under these conditions reveals that the gas holdup at the top of the electrolysis chamber is approximately 43%, and the bubble size ranges from 20 μm to 180 μm.

[0060] The bubble size results in the electrolyte at the top of the electrolytic cell after high current density electrolysis in Example 1, Example 2 and Comparative Example 1 are shown in Table 1. In Examples 1-2, the porous structure can effectively induce the fine bubbles generated by electrolysis in the electrolytic chamber to coalesce and grow, and reduce the gas content in the electrolytic cell.

[0061] Table 1

[0062] This application is described in detail for the purpose of enabling those skilled in the art to understand the contents of this application and implement them. This does not limit the scope of protection of this application. Any equivalent changes or modifications made according to the spirit of this application should be included in the scope of protection of this application.

Claims

1. An electrolytic cell utilizing a porous structure to control bubbles, characterized in that: The electrolytic cell comprises a plurality of parallel electrolytic chambers, wherein: A single electrolysis chamber comprises a cathode plate and an anode plate on both sides; a diaphragm is provided between the cathode plate and the anode plate; a cathode electrode and an anode electrode are provided on both sides of the diaphragm and between the cathode plate and the anode plate respectively; The electrolysis chambers between the cathode plate and the cathode electrode, and between the anode plate and the anode electrode are all equipped with porous agglomeration internal components for inducing the growth of fine bubbles in the gas-liquid mixture generated by electrolysis; The porous coalescing internal components are arranged in plurality on both sides of the diaphragm in each electrolytic cell, and the porous coalescing internal components are arranged in steps along the flow direction of the electrolyte to achieve step-induced coalescence of fine bubbles; The porous coalescing internal component adopts a three-dimensional porous foam structure or a two-dimensional mesh stacking structure, wherein: For porous agglomeration internal components adopting three-dimensional porous foam structure, they are embedded in the electrolysis chamber as a whole without distinguishing directions; for porous agglomeration internal components adopting two-dimensional mesh stacking structure, the bubble coalescence effect is adjusted by adjusting the stacking method and the angle between the stacking layer and the electrolyte flow direction.

2. The electrolytic cell according to claim 1, characterized in that The porous agglomeration inner component is processed by injection molding or woven fiber stacking.

3. The electrolytic cell according to claim 1, characterized in that For porous agglomerated internal components with a two-dimensional mesh stacking structure, the stacking method includes staggered distribution of meshes in different stacking layers, or different sizes and shapes of meshes in different stacking layers; the angle θ between the stacking layer and the electrolyte flow direction is set to 0°<θ<180°.

4. The electrolytic cell according to claim 1, characterized in that The porous agglomeration internal components on both sides of the diaphragm in each electrolytic cell are symmetrically or asymmetrically arranged, and the numbers of the porous agglomeration internal components on both sides are the same or different.

5. The electrolytic cell according to claim 1, characterized in that The porous agglomeration inner component is made of a hydrophobic material or has a hydrophobic coating on its surface, and the hydrophobic material or the hydrophobic coating is made of one or more selected from polyurethane, polyolefin, polycarbonate, polyamide, polyacrylonitrile, polyester, PTFE, FEP, ETFE, and PFA.

6. The electrolytic cell according to claim 1, characterized in that The porous agglomeration inner component is subjected to surface roughening treatment to increase the surface roughness.

7. The electrolytic cell according to claim 1, characterized in that The porous agglomeration internal component is installed in the electrolysis chamber through interference fit or overfitting between the electrode and the pole plate through a corrosion-resistant bracket.

8. An electrolysis device for regulating bubbles using a porous structure, characterized in that: The electrolysis device comprises any one of the electrolysis cells described in claims 1 to 7, and further comprises a gas-liquid separation device and a circulation pump, wherein: The lower end of the electrolysis chamber is provided with an electrolytic cell inlet, and the upper end is provided with an electrolytic cell outlet, including a first outlet and a second outlet; There are two gas-liquid separation devices, and the mixed liquid inlets thereof are respectively connected to the first outlet and the second outlet of the electrolytic cell; There are two circulating pumps, and the liquid phase outlet of each gas-liquid separation device is connected to the inlet of the electrolytic cell through a circulating pump.

9. An electrolysis method of an electrolysis device using a porous structure to control bubbles as claimed in claim 8, characterized in that: The method comprises: The electrolyte is pumped into the electrolytic cell from the bottom through a circulation pump and flows from bottom to top in the electrolytic cell. As the electrolysis reaction proceeds, a large number of microbubbles are generated in the electrolytic cell. When the microbubbles pass through the porous agglomeration internal component, the porous structure increases the turbulence of the liquid and the collision probability of the microbubbles. At the same time, it provides sites for the microbubbles to adhere, inducing the microbubbles to stay and coalesce. The formed large bubbles are discharged to the gas-liquid separation device together with the electrolyte. After the gas-liquid separation, the electrolyte returns to the electrolytic cell through the circulation pump for recycling, and the gas is discharged from the gas-liquid separation device.

Images