Vertical differential counterflow electrolytic cell

Abstract

The application discloses a vertical differential reverse flow electrolytic cell. It comprises a polar plate, a cathode material, a diaphragm, an anode material, an electrolyte inlet pipe, a hydrogen outlet channel and an oxygen outlet channel; the polar plate, the cathode material, the diaphragm and the anode material are arranged in sequence from bottom to top; every two polar plates, one cathode material, one diaphragm and one anode material constitute a vertical water electrolysis hydrogen production unit; a hydrogen generation area and an oxygen generation area are respectively located on both sides of the diaphragm; the bottom of the vertical differential reverse flow electrolytic cell is provided with the electrolyte inlet pipe, and the two sides are respectively provided with the hydrogen outlet channel and the oxygen outlet channel; the electrolyte inlet pipe is in communication with the hydrogen generation area and the oxygen generation area; the hydrogen generation area is in communication with the hydrogen outlet channel; the oxygen generation area is in communication with the oxygen outlet channel; and a plurality of vertical water electrolysis hydrogen production units are arranged in sequence from bottom to top. The application has the advantages of improving the electrolyte temperature, not making the electrolyte vaporize at the highest temperature, and reducing the floor area.

Description

Technical Field

[0001] This invention relates to the fields of energy sources and chemical engineering, and more specifically, to a vertical countercurrent electrolytic cell. More specifically, it is a vertical differential countercurrent electrolytic cell employing water-flow-patterned electrolytic cell electrodes. Background Technology

[0002] Hydrogen energy, as a secondary energy source, produces water as its byproduct and generates no pollutants. It is a crucial component of my country's clean energy strategy, an effective way to protect and improve the environment, a key support for promoting the clean energy revolution and restructuring the low-carbon industrial system, and an important element in cultivating new growth drivers and developing a new economy. Green hydrogen produced through renewable energy water electrolysis serves as an important raw material for industries such as chemicals and steel, significantly reducing carbon emissions. Simultaneously, renewable energy water electrolysis can effectively improve the stability of renewable energy power generation, reducing wind and solar curtailment while also serving as a large-scale energy storage method to enhance the grid's capacity to absorb renewable energy power. Against this backdrop, water electrolysis hydrogen production technology has experienced rapid development.

[0003] The process of producing hydrogen through water electrolysis is an electrochemical process accompanied by exothermic reactions at the electrodes. As the electrolyte flows through the electrolysis chamber, electrochemical reactions occur at the anode and cathode. The resulting H2 and O2 are then sent to a downstream purification system for further reaction, ultimately producing hydrogen with a purity of up to 99.99%. However, with the full development of the water electrolysis hydrogen production industry, the focus of electrolyzer design has shifted from simply pursuing large-scale production to more refined design, and issues such as electrolysis energy consumption and thermal efficiency have gradually become research hotspots.

[0004] The electrochemical reaction for hydrogen production through water electrolysis is directly proportional to temperature; that is, the higher the temperature, the faster the electrolysis rate. Therefore, the higher the liquid temperature in the electrolyzer, the better. However, during water electrolysis, some electrical energy is converted into heat energy. If the electrolyte inlet temperature is set too high, it will cause the electrolyte to vaporize within the cell, potentially leading to a safety accident. Therefore, ensuring the average temperature of the liquid within the electrolyzer is as high as possible, while preventing vaporization at the highest possible temperature, and guaranteeing sufficient residence time for the electrolyte within the cell, have become the three core elements of electrolyzer structure and fluid design.

[0005] Another issue of concern is the design of the electrolyzers and their associated plant buildings. Due to the flammable and explosive nature of hydrogen, electrolyzer workshops are typically designed as single-story buildings with good ventilation and high ceilings. However, as the scale of hydrogen production through water electrolysis continues to expand, the hydrogen production capacity of a single electrolyzer system has also increased from the initial 50 Nm³. 3 / h increased to 1000Nm 3 / h, and the area occupied has also increased from the initial 20m 2 Increase to 300-400m 2With the gradual scarcity of land resources, traditional horizontally arranged electrolytic cells, gas-liquid separators and other equipment occupy a large area and can no longer meet the needs of use.

[0006] Furthermore, since the electrolyzer produces H2 and O2 on both sides of the electrode by electrolyzing water, with 2 mol H2O producing 2 mol H2 and 1 mol O2, the gas volume on both sides of the electrode is twice that of the electrode. This can easily lead to excessive differences in electrolyte density and temperature on both sides of the electrode, resulting in gas penetration and safety accidents.

[0007] Therefore, it is necessary to develop an electrolytic cell that can maximize electrolyte temperature without vaporization while ensuring safety, reducing floor space, and improving safety. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a vertical differential countercurrent electrolytic cell that, while ensuring safety, maximizes the electrolyte temperature without causing vaporization at the highest electrolyte temperature, and ensures sufficient residence time of the electrolyte in the cell. It also achieves efficient utilization of the high space in existing factory buildings, saving space, reducing floor space, and improving safety. This overcomes the problems of existing technologies, which cannot maximize the average temperature of the liquid in the electrolytic cell while preventing vaporization at the highest electrolyte temperature, cannot guarantee sufficient residence time of the electrolyte in the cell, have a large equipment footprint, and are prone to safety accidents caused by excessive density and temperature differences of the electrolyte on both sides of the electrode plates leading to gas penetration.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows: a vertical differential countercurrent electrolyzer, characterized in that it includes an electrode plate, a cathode material, a diaphragm, an anode material, an electrolyte inlet pipe, a hydrogen outlet channel, and an oxygen outlet channel;

[0010] The electrode plate, cathode material, diaphragm, and anode material are arranged sequentially from bottom to top;

[0011] Each pair of electrode plates, a cathode material, a diaphragm, and an anode material constitute a vertical water electrolysis hydrogen production unit;

[0012] In the vertical water electrolysis hydrogen production unit, the hydrogen generation zone is located between the cathode material and the electrode plate; the oxygen generation zone is located between the anode material and the electrode plate; the hydrogen generation zone and the oxygen generation zone are located on both sides of the diaphragm, respectively.

[0013] The bottom of the vertical differential countercurrent electrolyzer is equipped with an electrolyte inlet pipe, and hydrogen outlet channels and oxygen outlet channels are respectively set on both sides.

[0014] The electrolyte inlet pipe is connected to the hydrogen generation zone and the oxygen generation zone respectively; the hydrogen generation zone is connected to the hydrogen outlet channel; and the oxygen generation zone is connected to the oxygen outlet channel.

[0015] Multiple vertical water electrolysis hydrogen production units are arranged sequentially from bottom to top; multiple hydrogen generation zones are arranged sequentially from bottom to top at intervals and interconnected; multiple oxygen generation zones are arranged sequentially from bottom to top at intervals and interconnected; the oxygen generation zone is located between two adjacent hydrogen generation zones that are spaced apart.

[0016] In the above technical solution, the upper and lower surfaces of the electrode plate are the cathode surface and the anode surface, respectively;

[0017] The cathode surface and the cathode material are arranged opposite each other and are located on both sides of the hydrogen generation zone;

[0018] The anode surface and the anode material are arranged opposite each other and are located on both sides of the oxygen generation zone.

[0019] In the above technical solution, dark flow patterns are provided on both the cathode surface and the anode surface;

[0020] The patterns at the entrance of the dark flow pattern are relatively sparse, while those at the exit are relatively dense.

[0021] In the above technical solution, the thickness of the electrode plate decreases uniformly near the fluid outlet end, and the bending radius of the arc surface of the electrode plate is more than 5 times the thickness of the electrode plate.

[0022] In the above technical solutions, the electrode plates are circular, elliptical, or square.

[0023] In the above technical solution, the electrolyte inlet pipe includes a cathode pipe and an anode pipe;

[0024] The cathode and anode pipelines enter the hydrogen generation zone and oxygen generation zone from opposite sides of the vertical water electrolysis hydrogen production unit, respectively.

[0025] In the above technical solution, valves are installed on both the cathode pipeline and the anode pipeline.

[0026] The present invention has the following advantages:

[0027] (1) The present invention utilizes the method of making the water electrolysis reaction easier to carry out after the electrolyte convective heat exchange, and the hydrogen production efficiency of the electrolyzer is higher.

[0028] (2) The present invention adds a control valve, which allows the flow rate of electrolyte fluid on both sides of the diaphragm to be controlled separately, thereby improving the temperature distribution of the electrolyzer and ultimately increasing the gas production while improving safety.

[0029] (3) The present invention adopts an electrolyte countercurrent arrangement, with the H2 and O2 outlets located on both sides of the electrolytic cell, which reduces the risk of deflagration caused by malfunction or gas leakage.

[0030] (4) Under the premise of ensuring safety, the present invention uses a differential countercurrent structure to make the average temperature of the liquid in the electrolytic cell as high as possible, and the highest temperature of the electrolyte cannot cause it to vaporize, while ensuring that the electrolyte has a sufficient residence time in the cell.

[0031] (5) The present invention adopts a vertical structure, and arranges multiple vertical water electrolysis hydrogen production units from bottom to top, so as to make effective use of the existing high space of the plant, save space, reduce the footprint, and save engineering costs. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of the present invention.

[0033] Figure 2 This is a schematic diagram of an electrolysis unit assembly structure according to the present invention.

[0034] Figure 3 This is a schematic diagram of an existing conventional electrolytic cell structure.

[0035] Figure 4 This is a schematic diagram of the electrode plate of the present invention.

[0036] Figure 5 This is a schematic diagram of the multi-unit assembly structure of the present invention.

[0037] Figure 6 for Figure 1 Enlarged view of point A.

[0038] Figure 7 The diaphragm temperature distribution diagrams fitted for different flow modes (co-current and counter-current) in the embodiments of the present invention are shown.

[0039] Figure 8 This is a schematic diagram of the electrolyte flow pattern in an embodiment of the present invention, which adopts the prior art of co-current flow.

[0040] Figure 9 This is a schematic diagram of the electrolyte flow pattern in an embodiment of the present invention, which adopts the countercurrent flow structure of the present invention.

[0041] Figure 4 Figure (a) shows one possible structural form of the electrode plate of the present invention; Figure 4 Figure (b) shows a second possible structural form of the electrode plate of the present invention; Figure 4 Figure (c) in the figure shows the third possible structural form of the electrode plate of the present invention; Figure 4 Figure (d) in the figure shows the fourth possible structural form of the electrode plate of the present invention.

[0042] Figure 1 , Figure 5 , Figure 8 , Figure 9The arrows in the diagram indicate the direction of electrolyte flow.

[0043] exist Figure 3 In this context, H2O represents water; O2 represents oxygen; and H2 represents hydrogen.

[0044] exist Figure 5 In this context, O2 represents oxygen gas; H2 represents hydrogen gas.

[0045] In the diagram, 1-plate, 1.1-cathode surface, 1.2-anode surface, 1.3-dark flow lines, 2-cathode material, 3-diaphragm, 4-anode material, 5-electrolyte inlet pipe, 5.1-cathode pipeline, 5.2-anode pipeline, 6-hydrogen generation zone, 7-oxygen generation zone, 8-hydrogen outlet channel, 9-oxygen outlet channel, 10-valve. Detailed Implementation

[0046] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, these descriptions do not constitute a limitation of the present invention and are merely illustrative. The advantages of the present invention will become clearer and easier to understand through this description.

[0047] Referring to the attached drawings, a vertical differential countercurrent electrolyzer includes an electrode plate 1, a cathode material 2, a diaphragm 3, an anode material 4, an electrolyte inlet pipe 5, a hydrogen outlet channel 8, and an oxygen outlet channel 9.

[0048] The electrode plate 1, cathode material 2, diaphragm 3, and anode material 4 are arranged sequentially from bottom to top;

[0049] Each pair of electrode plates 1, a cathode material 2, a diaphragm 3, and an anode material 4 constitute a vertical water electrolysis hydrogen production unit;

[0050] The hydrogen generation zone 6 of the vertical water electrolysis hydrogen production unit is located between the cathode material 2 and the electrode plate 1; the oxygen generation zone 7 is located between the anode material 4 and the electrode plate 1; the hydrogen generation zone 6 and the oxygen generation zone 7 are located on both sides of the diaphragm 3, respectively.

[0051] The bottom of the vertical differential countercurrent electrolyzer is equipped with an electrolyte inlet pipe 5, and hydrogen outlet channel 8 and oxygen outlet channel 9 are respectively provided on both sides; hydrogen outlet channel 8 and oxygen outlet channel 9 are connected by a main pipe to discharge hydrogen and oxygen vertically upward.

[0052] Electrolyte inlet pipe 5 is connected to hydrogen generation zone 6 and oxygen generation zone 7 respectively; hydrogen generation zone 6 is connected to hydrogen outlet channel 8; oxygen generation zone 7 is connected to oxygen outlet channel 9; forming a differential counter-current structure.

[0053] Multiple vertical water electrolysis hydrogen production units are arranged sequentially from bottom to top; multiple hydrogen generation zones 6 are arranged sequentially from bottom to top at intervals and interconnected; multiple oxygen generation zones 7 are arranged sequentially from bottom to top at intervals and interconnected; the oxygen generation zone 7 is located between two adjacent hydrogen generation zones 6 at intervals (e.g., Figure 1 , Figure 2 , Figure 5 (As shown). This invention uses a counter-current structure to maximize the average temperature of the liquid in the electrolytic cell, while preventing the electrolyte from vaporizing at its highest temperature.

[0054] Further, the upper and lower surfaces of plate 1 are the cathode surface 1.1 and the anode surface 1.2, respectively;

[0055] During assembly, the cathode surface 1.1 and the cathode material 2 are arranged facing each other;

[0056] Anode surface 1.2 and anode material 4 are arranged opposite each other (e.g.) Figure 1 , Figure 2 , Figure 5 , Figure 6 (As shown).

[0057] Furthermore, different dark flow patterns 1.3 are set on the cathode surface 1.1 and the anode surface 1.2 according to the adsorption and flow characteristics of hydrogen and oxygen;

[0058] 1.3 Flow patterns, following the direction of liquid flow, show relatively sparse patterns at the inlet and relatively dense patterns at the outlet (e.g., Figure 4 (As shown).

[0059] Further, the thickness of electrode 1 decreases uniformly near the fluid outlet end, and the bending radius of the arc surface of electrode 1 is more than 5 times the thickness of electrode 1.

[0060] In one further location, the electrode plate 1 takes various shapes, such as round, elliptical, or square (e.g. Figure 4 (As shown).

[0061] Further, the electrolyte inlet pipe 5 is divided into two at the bottom of the hydrogen production unit, including a cathode pipe 5.1 and an anode pipe 5.2;

[0062] Cathode line 5.1 and anode line 5.2 enter hydrogen generation zone 6 and oxygen generation zone 7 from opposite sides of the hydrogen production unit (i.e., vertical water electrolysis hydrogen production unit), respectively. Figure 1 , Figure 5 As shown, the electrolyte flows in opposite directions on both sides of the diaphragm 3.

[0063] Furthermore, valves 10 are installed on both the cathode conduit 5.1 and the anode conduit 5.2 (e.g., ...). Figure 1As shown); during operation, the valve 10 is kept at different openings according to the different gas generation characteristics in the hydrogen generation zone 6 and the oxygen generation zone 7, and the electrolyte flow rate on both sides of the electrode plate is controlled respectively, so that the electrolyte flow rate on both sides of the diaphragm is different, forming a differential speed. By controlling the flow rate, the electrolyte is ensured to have a sufficient and reasonable residence time in the tank, so as to meet the requirements of the flow rate and residence time of the different gases generated on both sides of the diaphragm.

[0064] Verification test

[0065] Reference Figure 3 As shown: Most conventional electrolytic cells are horizontally arranged, with the electrolyte entering from the bottom and the gas-liquid mixture exiting from the top. After the electrolyte enters the electrolysis chamber, it electrolyzes the gas and is simultaneously heated by the electrodes. Taking a certain project as an example, the electrolyte temperature at the inlet is 70°C and the temperature at the outlet is 90°C.

[0066] Reference Figure 1 and Figure 3 As shown, this invention adopts a vertical countercurrent arrangement, which, compared to the existing conventional horizontal arrangement of electrolytic cells (such as...), Figure 2 As shown in the figure, in this invention, the electrolyte flows in opposite directions on the cathode and anode sides. Using an inlet temperature of 70°C as the boundary condition, the diaphragm temperature distribution fitted by different flow patterns (co-current and counter-current) is calculated according to the relevant formulas for convective heat transfer. Figure 7 As shown, "co-current" refers to the direction of fluid flow on both sides of the electrode plate; "co-current" means flowing in the same direction and "counter-current" means flowing in opposite directions. Figure 7 The term "concurrent flow" refers to the flow pattern of the electrolyte in existing technologies. Figure 7 The term "countercurrent" refers to the flow pattern of the electrolyte in this invention.

[0067] Depend on Figure 7 As can be seen, changing the flow pattern in a conventional electrolyzer does not alter the overall energy balance; therefore, the initial and final temperatures are both 70°C and 90°C, respectively. However, when the counter-current flow pattern described in this invention is adopted, the temperature distribution of the diaphragm changes compared to the conventional co-current flow pattern. The calculated temperature in some areas is higher than that in the original parallel flow pattern, with the highest temperature increasing by approximately 2°C.

[0068] From a physical perspective, the original parallel flow method (i.e., the existing conventional horizontal arrangement of electrolytic cells, such as...) Figure 2 As shown, the electrolyte gradually absorbs the heat generated by electrolysis and its temperature gradually rises from 70°C to 90°C during flow. However, when the flow pattern is changed (i.e., the vertical differential countercurrent electrolytic cell described in this invention, such as...), the temperature rises from 70°C to 90°C. Figure 1 and Figure 5 As shown in the diagram, the electrolyte liquid absorbs heat conducted by the fluid on the opposite side while being heated by the electrodes, causing the temperature in some areas to be higher than the temperature in the parallel flow state during the flow process. This invention changes the conventional parallel flow of the electrolyte to counter-flow, so that the electrodes move from point a to point b (as shown in the diagram). Figure 9 The local temperature (as shown) is higher than that of conventional electrolyte co-current heat transfer methods (such as... Figure 8 As shown in the figure, according to the relevant formula, the average values ​​of the parallel flow mode and the counterflow mode are 75.76℃ and 77.28℃, respectively.

[0069] The relevant calculation formulas for fluid heat transfer are as follows:

[0070]

[0071]

[0072]

[0073] The main formulas for thermal calculations are as shown above, where:

[0074] γ: Thermal conductivity, which is a function of temperature;

[0075] q: Heat flux density, the amount of heat passing through a unit area per unit time;

[0076] L: Length of the plate;

[0077] T: Outlet temperature, °C;

[0078] t: Inlet temperature, °C;

[0079] △G=△HT·△S<0;

[0080] Furthermore, according to the Gibbs free energy formula, when the boundary conditions such as reaction enthalpy and entropy are constant, the Gibbs free energy of the reaction decreases with increasing temperature (the entropy of the water electrolysis reaction increases). Therefore, when the average temperature of the electrode surface is increased, the water electrolysis reaction is easier to carry out (the reaction proceeds spontaneously with a negative Gibbs free energy). That is, after the present invention adopts the electrolyte convection heat transfer, the water electrolysis reaction is easier to carry out, and the hydrogen production efficiency of the electrolyzer is higher.

[0081] Furthermore, the chemical reaction formula for hydrogen production by water electrolysis shows that every 2 mol of H₂O will produce 2 mol of H₂ and 1 mol of O₂ after electrolysis. According to Avogadro's law, equal molar volumes of gas contain the same number of particles; that is, each mole of H₂ and O₂ has the same number of molecules and, under the same conditions, the same volume. Therefore, during water electrolysis, the volume of H₂ produced per unit time is twice that of O₂, as shown in the following formula:

[0082] 2H₂O=2H₂+O₂

[0083] Specifically, regarding the two sides of the diaphragm in the electrolytic cell, the volume of H2 produced on the cathode side is larger, while the volume of O2 produced on the anode side is smaller. These different gas volumes and densities directly lead to fundamental differences in the thermal conductivity and flow properties of the fluids on both sides of the diaphragm. If the electrolyte flow rate is kept constant on both sides of the diaphragm, overheating is likely to occur on one side, while the temperature on the other side will be too low. Furthermore, it could lead to significant local pressure differences on both sides, causing high-pressure gas to penetrate the diaphragm to the low-pressure side, potentially resulting in a safety accident. Therefore, compared to... Figure 3 In contrast to existing conventional electrolytic cells, this invention adds a control valve 10. This valve allows for separate control of the electrolyte flow rate on both sides of the diaphragm, thereby improving the temperature distribution within the electrolytic cell and ultimately increasing gas production. Simultaneously, the independent control of the electrolyte flow rate on both sides of the electrode plate enhances safety. This overcomes the limitations of existing technologies, which cannot maximize the average temperature of the liquid within the electrolytic cell while preventing vaporization at the highest electrolyte temperature, cannot guarantee the electrolyte's residence time within the cell, have a large equipment footprint, and are prone to safety accidents caused by excessive differences in electrolyte density and temperature on both sides of the electrode plate, leading to gas penetration.

[0084] Furthermore, by adopting a countercurrent electrolyte arrangement, the outlets of H2 and O2 in this invention are located on both sides of the electrolytic cell, reducing the risk of deflagration caused by malfunctions or gas leaks.

[0085] The parts not described in detail above are all existing technologies.

Claims

1. A vertical differential countercurrent electrolytic cell, characterized in that: This includes electrode plates, cathode materials, diaphragms, anode materials, electrolyte inlet pipes, hydrogen outlet channels, and oxygen outlet channels; The electrode plate, cathode material, diaphragm, and anode material are arranged sequentially from bottom to top; Each pair of electrode plates, a cathode material, a diaphragm, and an anode material constitute a vertical water electrolysis hydrogen production unit; In the vertical water electrolysis hydrogen production unit, the hydrogen generation zone is located between the cathode material and the electrode plate, and the oxygen generation zone is located between the anode material and the electrode plate; the hydrogen generation zone and the oxygen generation zone are located on both sides of the diaphragm, respectively. The bottom of the vertical differential countercurrent electrolyzer is equipped with an electrolyte inlet pipe, and hydrogen outlet channels and oxygen outlet channels are respectively set on both sides. The electrolyte inlet pipe includes a cathode pipe and an anode pipe; The cathode and anode lines enter the hydrogen generation zone and oxygen generation zone from opposite sides, respectively, and the electrolyte flows in opposite directions on both sides of the diaphragm. Valves are installed on both the cathode and anode lines. During operation, the valves are kept at different openings according to the different gas generation characteristics in the hydrogen generation zone and the oxygen generation zone to control the electrolyte flow rate on both sides of the electrode plate, so that the electrolyte flow rate on both sides of the diaphragm is different, forming a differential flow rate. The hydrogen generation zone is connected to the hydrogen outlet channel; the oxygen generation zone is connected to the oxygen outlet channel. Multiple vertical water electrolysis hydrogen production units are arranged sequentially from bottom to top; multiple hydrogen generation zones are arranged sequentially from bottom to top at intervals and interconnected; multiple oxygen generation zones are arranged sequentially from bottom to top at intervals and interconnected; the oxygen generation zone is located between two adjacent hydrogen generation zones that are spaced apart.

2. The vertical differential countercurrent electrolytic cell according to claim 1, characterized in that: The upper and lower surfaces of the electrode plate are the cathode surface and the anode surface, respectively. The cathode surface and the cathode material are arranged opposite to each other; The anode surface and the anode material are arranged opposite each other.

3. The vertical differential countercurrent electrolytic cell according to claim 2, characterized in that: Dark flow patterns are provided on both the cathode and anode surfaces; The patterns at the entrance of the dark flow pattern are relatively sparse, while those at the exit are relatively dense.

4. The vertical differential countercurrent electrolytic cell according to claim 3, characterized in that: The thickness of the electrode plate decreases uniformly near the fluid outlet end, and the bending radius of the arc surface of the electrode plate is more than 5 times the thickness of the electrode plate.

5. The vertical differential countercurrent electrolytic cell according to claim 4, characterized in that: The plates are round, elliptical, or square.

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