Alkaline electrolytic cell capable of flexibly adjusting minimum operation load and adjusting method thereof

Abstract

The invention discloses an alkaline electrolytic bath capable of flexibly adjusting the minimum operation load and an adjusting method of the alkaline electrolytic bath. The alkaline electrolytic bath comprises an electrolytic bath fastening device, an anode side unit, a first bipolar plate unit, a middle current collection bipolar plate unit, a second bipolar plate unit and a cathode side unit, the anode side unit, the middle collector bipolar plate unit and the cathode side unit are respectively connected with an anode copper bar, a first cathode copper bar and a second cathode copper bar of the rectifier; the first bipolar plate unit comprises N1 first bipolar plate assemblies, the second bipolar plate unit comprises N2 second bipolar plate assemblies, and the number ratio of N1 to N2 is (0.5-1): 1; sealing gaskets are arranged on the two sides of any bipolar plate assembly; the rectifier is configured as follows: when the output load of the rectifier does not reach (N1 / (N1 + N2))% of the set minimum operation load of the electrolytic cell, the rectifier controls the first negative electrode to supply power and the second negative electrode not to supply power; otherwise, the second cathode is controlled to supply power, and the first cathode does not supply power. The method has good adaptability to green electricity.

Description

Technical Field

[0001] This invention relates to the field of hydrogen production technology through water electrolysis. More specifically, this invention relates to an alkaline electrolyzer with flexibly adjustable minimum operating load and a method for adjusting the same. Background Technology

[0002] The hydrogen energy industry has entered a phase of rapid development, and green electricity hydrogen production technology has begun large-scale promotion in my country. Due to its advantages such as high single-cell hydrogen production capacity, high technological maturity, and low equipment cost, alkaline water electrolysis hydrogen production is currently the mainstream technology, accounting for over 90% of the domestic market share. The alkaline electrolyzer is the core equipment in alkaline water electrolysis hydrogen production. In green electricity hydrogen production projects, to reduce the proportion of grid power usage and maintain the operation of the electrolyzer, it is necessary to keep it operating at a low load. However, low-load operation of the alkaline electrolyzer can lead to an increase in hydrogen in the oxygen content, posing a fire and explosion risk. To ensure safety, the minimum operating load of the alkaline electrolyzer is usually set at 30-50% of the rated load. However, wind and solar power are intermittent and highly volatile. When used as external power sources, if the output power of wind and solar power is lower than the minimum operating load of the alkaline electrolyzer, it will trigger the interlock protection of the hydrogen production system, causing the system to stop hydrogen production.

[0003] Currently, both domestic and international methods such as adjusting the alkaline solution flow rate, operating temperature, and injecting hydrogen into the hydrogen side of the hydrogen production system are used to control the hydrogen content in oxygen to ensure it does not exceed the standard, thereby further reducing the minimum operating load of the electrolyzer to adapt to the intermittent and highly volatile characteristics of wind and solar power. However, these methods have limited effect on reducing the minimum operating load of the electrolyzer and still cannot achieve the operation of alkaline electrolyzers at a load below 20% of the rated power. Moreover, the adjustment speed is slow, and the adaptability to wind and solar power is poor, failing to meet the requirements for large-scale adjustment of green electricity hydrogen production.

[0004] Therefore, with the large-scale promotion of green electricity hydrogen production, there is an urgent need to develop an alkaline electrolyzer and adjustment method that can flexibly adjust the minimum operating load to effectively reduce the minimum operating load to below 20%, so that the alkaline electrolyzer can adapt to the fluctuating characteristics of green electricity and promote the rapid development of the green electricity hydrogen production industry. Summary of the Invention

[0005] Another objective of this invention is to provide an alkaline electrolyzer with a flexibly adjustable minimum operating load and its adjustment method, which is well adapted to green electricity, can effectively save grid power consumption, and reduce hydrogen production costs.

[0006] To achieve these objectives and other advantages according to the present invention, an alkaline electrolyzer with flexibly adjustable minimum operating load is provided, comprising an electrolyzer fastening device, and an anode-side unit, a first bipolar plate unit, an intermediate current collector bipolar plate unit, a second bipolar plate unit, and a cathode-side unit that are sequentially stacked and pressed together by the electrolyzer fastening device. The lower portions of the anode-side unit, the intermediate current collector bipolar plate unit, and the cathode-side unit are respectively connected to an anode terminal block, a first cathode terminal block, and a second cathode terminal block. The anode terminal block, the first cathode terminal block, and the second cathode terminal block are respectively connected to the positive copper busbar, the first negative copper busbar, and the second negative copper busbar of a rectifier via copper busbars. The rectifier is connected to an external power supply. The first bipolar plate unit includes N1 stacked and pressed first bipolar plate assemblies, and the second bipolar plate unit includes N2 stacked and pressed second bipolar plate assemblies, with the ratio of N1 to N2 being (0.5 to 1):1; sealing gaskets are provided on both sides of each bipolar plate assembly; The rectifier is configured as follows: When the output load of the rectifier does not reach (N1 / (N1+N2))% of the minimum operating load set by the electrolytic cell, the rectifier controls the first negative terminal to be powered and the second negative terminal to be de-powered; conversely, it controls the second negative terminal to be powered and the first negative terminal to be de-powered.

[0007] Preferably, the anode side unit includes an anode end plate assembly connected to the anode terminal block, and an anode end plate attached to the non-active surface of the anode end plate assembly. Insulating pads are provided on both sides of the anode end plate. The active surface of the anode end plate assembly is a concave structure, in which an anode support mesh and an anode electrode are installed. The top and bottom of the anode end plate assembly are respectively provided with a first oxygen flow hole and a first alkali flow hole, both of which are connected to the concave structure.

[0008] Preferably, the first bipolar plate assembly and the second bipolar plate assembly have the same structure, both including a pole frame, pole plates, a cathode support mesh, a cathode electrode, an anode support mesh, an anode electrode, and a diaphragm; The electrode plate is welded inside the electrode frame. Both sides of the electrode plate are concave structures. The cathode support mesh, cathode electrode, and diaphragm are installed in the concave structure on the cathode side of the electrode plate, and the anode support mesh and anode electrode are installed in the concave structure on the anode side of the electrode plate. The top of the electrode frame has a through second oxygen flow hole and a first hydrogen flow hole, which are connected to the concave structure on the anode side and the concave structure on the cathode side, respectively. The bottom of the electrode frame has a through second alkali flow hole, which is connected to the two concave structures.

[0009] Preferably, the intermediate current collector bipolar plate unit includes an intermediate current collector bipolar plate assembly connected to the first cathode terminal block. Both sides of the intermediate current collector bipolar plate assembly are concave structures. A cathode support mesh, a cathode electrode, and a diaphragm are installed in the concave structure on the cathode side of the intermediate current collector bipolar plate assembly, and an anode support mesh and an anode electrode are installed in the concave structure on the anode side of the intermediate current collector bipolar plate assembly. The top of the intermediate current collector bipolar plate assembly has a through-hole for third oxygen and a through-hole for second hydrogen, which are respectively connected to the concave structure on the anode side and the concave structure on the cathode side. The bottom of the intermediate current collector bipolar plate assembly has a through-hole for third alkali solution, which is connected to the two concave structures.

[0010] Preferably, the cathode-side unit includes a cathode end plate assembly connected to the second cathode terminal block, and a cathode end plate attached to the non-active surface of the cathode end plate assembly. Insulating pads are provided on both sides of the cathode end plate. The active surface of the cathode end plate assembly is a concave structure, in which a cathode support mesh, a cathode electrode, and a diaphragm are installed. A fourth oxygen flow hole and a third hydrogen flow hole are provided through the top of the cathode end plate assembly, and a fourth alkali flow hole is provided through the bottom. The fourth oxygen flow hole, the third hydrogen flow hole, and the fourth alkali flow hole are all connected to the concave structure. The upper part of the cathode end plate is provided with a through fifth oxygen flow hole and a fourth hydrogen flow hole, and the lower part is provided with a through fifth alkali flow hole.

[0011] A method for adjusting an alkaline electrolyzer with flexibly adjustable minimum operating load includes the following steps: S1: Connect the positive copper busbar, the first negative copper busbar, and the second negative copper busbar of the rectifier to the anode terminal block of the anode side unit, the first cathode terminal block of the intermediate current collector bipolar plate unit, and the second cathode terminal block of the cathode side unit through copper busbars. S2: Start the electrolytic cell. The rectifier controls the first negative electrode to supply power, while the second negative electrode is not supplied with power. During the operation of the electrolytic cell, if the output load of the rectifier does not reach (N1 / (N1+N2))% of the minimum operating load set by the electrolytic cell, the rectifier maintains the first negative electrode supplying power and the second negative electrode not supplying power. If the output load of the rectifier reaches (N1 / (N1+N2))% of the minimum operating load set by the electrolytic cell, the rectifier automatically switches to the second negative electrode supplying power and cuts off the first negative electrode supplying power.

[0012] The present invention includes at least the following beneficial effects: An intermediate current-collecting bipolar plate unit is set between the first and second bipolar plate units, and the rectifier is specially configured to have two automatically switchable power supply modes. When the output power of external wind and photovoltaic power reaches (N1 / (N1+N2))% of the minimum operating load set for the electrolyzer, the rectifier is powered by the second negative electrode, and all bipolar plate units of the electrolyzer operate to produce hydrogen. When the output power of external wind and photovoltaic power fluctuates and does not reach (N1 / (N1+N2))% of the minimum operating load set for the electrolyzer, the rectifier automatically switches to the first negative electrode, and the electrolyzer operates by the first bipolar plate unit to produce hydrogen. The overall operating load of the electrolyzer can be reduced to (N1 / (N1+N2))% of the set minimum operating load. The electrolyzer can operate at a load lower than the set minimum operating load, ensuring continuous and efficient hydrogen production, and ultimately achieving the goal of adapting the operation of the electrolyzer to the power fluctuation characteristics of wind and photovoltaic power.

[0013] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the alkaline electrolyzer of the present invention, which allows for flexible adjustment of the minimum operating load; Figure 2 This is a schematic diagram of the structure of the anode electrode assembly of the present invention; Figure 3 This is a schematic diagram of the intermediate current collector bipolar plate assembly of the present invention; Figure 4 This is a schematic diagram of the bipolar plate assembly of the present invention; Figure 5 This is a schematic diagram of the cathode end plate assembly of the present invention; Figure 6 This is a schematic diagram of the structure of the cathode end plate of the present invention; Figure 7 This is a schematic diagram showing the flow directions of the alkaline solution, hydrogen, and oxygen in this invention. Explanation of reference numerals in the instruction manual: 1. Electrolytic cell fastening device; 2. Anode end plate; 3. Anode end plate assembly; 31. First oxygen flow hole; 32. Anode terminal block; 33. First alkali flow hole; 4. Intermediate current collector bipolar plate unit; 41. Intermediate current collector bipolar plate assembly; 42. First cathode terminal block; 43. Third alkali flow hole; 44. Second hydrogen flow hole; 45. Third oxygen flow hole; 5. Sealing gasket; 6. Bipolar plate assembly; 61. Electrode frame; 62. Electrode plate; 63. Second alkali flow hole; 64. First hydrogen flow hole; 65. Second oxygen flow hole; 7. Cathode end plate assembly; 71. Third hydrogen flow hole; 72. Second cathode terminal block; 73. Fourth alkali flow hole; 74. Fourth oxygen flow hole; 8. Cathode end plate; 81. Fifth alkali flow hole; 82. Fifth oxygen flow hole; 83. Fourth hydrogen flow hole; 9. Insulating pad. Detailed Implementation

[0015] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0016] It should be noted that in the description of this invention, the terms "lateral", "longitudinal", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0017] like Figure 1-7 As shown, the present invention provides an alkaline electrolyzer with flexibly adjustable minimum operating load, including an electrolyzer fastening device 1, and an anode side unit, a first bipolar plate unit, an intermediate current collector bipolar plate unit 4, a second bipolar plate unit, and a cathode side unit that are stacked and pressed together in sequence by the electrolyzer fastening device 1. The lower parts of the anode side unit, the intermediate current collector bipolar plate unit 4, and the cathode side unit are respectively connected to an anode terminal block 32, a first cathode terminal block 42, and a second cathode terminal block 72. The anode terminal block 32, the first cathode terminal block 42, and the second cathode terminal block 72 are respectively connected to the positive electrode copper busbar, the first negative electrode copper busbar, and the second negative electrode copper busbar of the rectifier through copper busbars. The rectifier is connected to an external power supply. The first bipolar plate unit includes N1 stacked and pressed first bipolar plate assemblies, and the second bipolar plate unit includes N2 stacked and pressed second bipolar plate assemblies, with the ratio of N1 to N2 being (0.5 to 1):1; sealing gaskets 5 are provided on both sides of each bipolar plate assembly; The rectifier is configured as follows: When the output load of the rectifier does not reach (N1 / (N1+N2))% of the minimum operating load set by the electrolytic cell, the rectifier controls the first negative terminal to be powered and the second negative terminal to be de-powered; conversely, it controls the second negative terminal to be powered and the first negative terminal to be de-powered.

[0018] like Figure 1 As shown, the alkaline electrolyzer of the present invention, which can flexibly adjust the minimum operating load, is composed of an electrolyzer fastening device 1, an anode side unit, a first bipolar plate unit, an intermediate current collector bipolar plate unit 4, a second bipolar plate unit, and a cathode side unit. The electrolyzer fastening device 1 stacks the anode side unit, the first bipolar plate unit, the intermediate current collector bipolar plate unit 4, the second bipolar plate unit, and the cathode side unit in sequence and axially presses them together so that the components fit tightly together to form a sealed and conductive electrolysis chamber.

[0019] The anode side unit consists of an anode end plate assembly 3 and an anode end plate 2. One side of the anode end plate 2 is attached to the electrolytic cell fastening device 1, and the other side is attached to the non-active surface of the anode end plate assembly 3. The anode end plate 2 is square or round, made of carbon steel, and nickel-plated. Insulating pads 9 are attached to both sides of the anode end plate 2. Multiple fastening holes adapted to the electrolytic cell fastening device 1 are opened on the anode end plate 2 and the insulating pads 9. like Figure 2 As shown, the anode plate assembly 3 is square or round, made of carbon steel, and nickel-plated on the surface. The active surface of the anode plate assembly 3 is processed into a concave surface, and an anode support mesh A1 and an anode electrode B1 are installed sequentially inside the concave surface. A first alkali flow hole 33 is processed at the bottom of the anode plate assembly 3 corresponding to the concave surface, and a first oxygen flow hole 31 is processed at the top of the concave surface. Both the first alkali flow hole 33 and the first oxygen flow hole 31 are opened through the thickness direction of the anode plate assembly 3 and are connected to the interior of the concave surface. An anode terminal block 32 is also connected to the bottom of the anode plate assembly 3. The anode terminal block 32 is connected to the positive copper busbar of the rectifier through a copper busbar. The rectifier is connected to an external power supply.

[0020] The first bipolar plate unit consists of N1 stacked and pressed first bipolar plate assemblies, and the second bipolar plate unit consists of N2 stacked and pressed second bipolar plate assemblies, with a N1:N2 ratio of (0.5 to 1):1. The first and second bipolar plate units are separated by an intermediate current collector bipolar plate unit 4. The first and second bipolar plate assemblies are identical bipolar plate assemblies, and sealing gaskets 5 are provided on both sides of each bipolar plate assembly. Figure 4As shown, the bipolar plate assembly 6 consists of an electrode frame 61, an electrode plate 62, a cathode support mesh A2, a cathode electrode B2, an anode support mesh A1, an anode electrode B1, and a diaphragm C. The electrode frame 61 and the electrode plate are square or round, and both are made of carbon steel with a nickel-plated surface. The electrode plate is thinner than the electrode frame 61. The electrode plate is welded to the electrode frame 61, and both sides of the electrode plate are machined into concave surfaces. The cathode support mesh A2, the cathode electrode B2, and the diaphragm C are sequentially installed on the concave surfaces of the cathode side of the electrode plate. Inside, the anode support mesh A1 and the anode electrode B1 are sequentially installed in the concave surface on the anode side of the electrode plate; the top of the electrode frame 61 is machined with a through second oxygen flow hole 65 and a first hydrogen flow hole 64 along the thickness direction of the electrode frame 61. The second oxygen flow hole 65 communicates with the interior of the concave surface on the anode side, and the first hydrogen flow hole 64 communicates with the interior of the concave surface on the cathode side. The bottom of the electrode frame 61 is machined with a through second alkali solution flow hole 63 along the thickness direction of the electrode frame 61, which communicates with the interior of both concave surfaces.

[0021] The intermediate current collector bipolar plate unit 4 is the intermediate current collector bipolar plate assembly 41, such as... Figure 3 As shown, it is square or round, made of carbon steel, and nickel-plated. The bottom of the intermediate current collector bipolar plate assembly 41 is connected to the first cathode terminal plate 42, which is connected to the first negative electrode copper busbar of the rectifier through a copper busbar. Both sides of the intermediate current collector bipolar plate assembly 41 are processed into concave surfaces. The cathode support mesh A2, cathode electrode B2 and diaphragm C are installed sequentially in the concave surface of the cathode side of the intermediate current collector bipolar plate assembly 41, and the anode support mesh A1 and anode electrode B1 are installed sequentially in the concave surface of the anode side. The bottom of the intermediate current collector bipolar plate assembly 41 has a through-hole 43 that communicates with the interior of both concave surfaces along its thickness direction. The top of the intermediate current collector bipolar plate assembly 41 has a through-hole 45 that communicates with the interior of the concave surface of the anode side and a second hydrogen flow hole 44 that communicates with the interior of the concave surface of the cathode side, respectively, corresponding to the two concave surfaces.

[0022] The cathode-side unit consists of a cathode end plate assembly 7 and a cathode end plate 8. One side of the cathode end plate 8 is attached to the electrolytic cell fastening device 1, and the other side is attached to the non-active surface of the cathode end plate assembly 7. Figure 5 As shown, the cathode end plate assembly 7 is square or round, made of carbon steel, and nickel-plated. A second cathode terminal block 72 is connected to the bottom of the cathode end plate assembly 7, and the second cathode terminal block 72 is connected to the second negative electrode copper busbar of the rectifier via a copper busbar. The active surface of the cathode end plate assembly 7 is processed into a concave surface, within which a cathode support mesh A2, a cathode electrode B2, and a diaphragm C are sequentially installed. A fourth alkali solution flow hole 73 is processed at the bottom corresponding to the concave surface of the cathode end plate assembly 7, and a fourth oxygen flow hole 74 and a third hydrogen flow hole 71 are processed at the top corresponding to the concave surface. The fourth oxygen flow hole 74, the fourth alkali solution flow hole 73, and the third hydrogen flow hole 71 are all connected to the interior of the concave surface.

[0023] like Figure 6 As shown, the cathode end plate 8 is square or round, made of carbon steel, and nickel-plated on the surface. Insulating pads 9 are attached to both sides of the cathode end plate 8. Multiple fastening holes adapted to the electrolytic cell fastening device 1 are opened on the cathode end plate 8 and the insulating pads 9. A fifth oxygen flow hole 82 and a fourth hydrogen flow hole 83 are opened in the upper part of the cathode end plate 8 along the thickness direction of the cathode end plate 8, and a fifth alkali flow hole 81 is opened in the lower part. The electrolytic cell fastening device 1 can be fastened with screws. First, stack and align the anode side unit, the first bipolar plate unit, the intermediate current collector bipolar plate unit 4, the second bipolar plate unit, and the cathode side unit, as well as the corresponding sealing gaskets 5 and insulating pads 9 in sequence. Then, pass the screw through the fastening holes on the end plates and the insulating pads 9, put on the nuts, and tighten them to make the components fit tightly and eliminate the stacking gaps. Alternatively, hydraulic fastening can be used.

[0024] like Figure 7 As shown, the flow paths of the three media in the electrolytic cell are as follows: The alkali solution enters from the fifth alkali solution flow hole 81 at the bottom of the cathode end plate 8, and then flows sequentially through the fourth alkali solution flow hole 73 at the bottom of the cathode end plate assembly 7, the second alkali solution flow hole 63 at the bottom of the second bipolar plate assembly, the third alkali solution flow hole 43 at the bottom of the intermediate current collector bipolar plate assembly, the second alkali solution flow hole 63 at the bottom of the first bipolar plate assembly, and the first alkali solution flow hole 33 at the bottom of the anode end plate assembly 3, into the corresponding support mesh of each assembly.

[0025] Oxygen flows from the first oxygen flow hole 31 at the top of the anode plate assembly 3, the second oxygen flow hole 65 at the top of the first bipolar plate assembly, the third oxygen flow hole 45 at the top of the intermediate current collector bipolar plate assembly 41, the second oxygen flow hole 65 at the top of the second bipolar plate assembly, and the fourth oxygen flow hole 74 at the top of the cathode plate assembly 7, and flows out from the fifth oxygen flow hole 82 at the top of the cathode plate 8.

[0026] Hydrogen gas is collected from the first hydrogen flow hole 64 at the top of the first bipolar plate assembly, the second hydrogen flow hole 44 at the top of the intermediate current collector bipolar plate assembly 41, the first hydrogen flow hole 64 at the top of the second bipolar plate assembly, and the third hydrogen flow hole 71 at the top of the cathode end plate assembly 7, and flows out from the fourth hydrogen flow hole 83 at the top of the cathode end plate 8.

[0027] The external power sources of this invention are wind power and photovoltaic power, which have inherent characteristics of strong intermittency and large fluctuations in output power. When the output power of wind power and photovoltaic power is lower than the minimum operating load set by the alkaline electrolyzer, the electrolyzer will trigger the system interlock protection mechanism, causing the hydrogen production operation to be interrupted, which seriously affects the continuity and reliability of the hydrogen production system.

[0028] To address the aforementioned technical issues, this application includes an intermediate current-collecting bipolar plate unit 4 positioned between the first and second bipolar plate units. The rectifier is specially configured to have two automatically switchable power supply modes, enabling the electrolytic cell to operate in two modes. This ultimately achieves the goal of adapting the electrolytic cell's operation to the power fluctuation characteristics of wind and solar power. The rectifier is configured such that when the output power of external wind and solar power reaches (N1 / (N1+N2))% of the electrolytic cell's set minimum operating load, the rectifier is powered by the second negative terminal, and the electrolytic cell... All bipolar plate units produce hydrogen. When the output power of external wind and solar power fluctuates and does not reach (N1 / (N1+N2))% of the minimum operating load set by the electrolyzer, the rectifier automatically switches to the first negative terminal for power supply. The electrolyzer then produces hydrogen through the first bipolar plate unit, and the overall operating load of the electrolyzer can be reduced to (N1 / (N1+N2))% of the set minimum operating load. The electrolyzer can operate at a load lower than the set minimum operating load, ensuring continuous and efficient hydrogen production, improving the utilization rate of green electricity, and reducing grid electricity consumption.

[0029] A method for adjusting an alkaline electrolyzer with flexibly adjustable minimum operating load includes the following steps: S1: Connect the positive copper busbar, the first negative copper busbar, and the second negative copper busbar of the rectifier to the anode terminal block 32 of the anode side unit, the first cathode terminal block 42 of the intermediate current collector bipolar plate unit 4, and the second cathode terminal block 72 of the cathode side unit through copper busbars. S2: The initial state of the rectifier is preset to power supply to the first negative terminal and no power supply to the second negative terminal. When starting the electrolytic cell, the rectifier drives the electrolytic cell to establish the initial operating conditions by power supply to the first negative terminal. During the startup process, if the output power of the external power supply does not reach (N1 / (N1+N2))% of the minimum operating load set by the electrolytic cell, the rectifier maintains power supply to the first negative terminal. If the output power of the external power supply fluctuates and reaches (N1 / (N1+N2))% of the minimum operating load set by the electrolytic cell, the rectifier automatically switches to power supply to the second negative terminal and cuts off the power supply to the first negative terminal to ensure the continuous operation of the electrolytic cell. S3. During stable operation of the electrolytic cell, if the output load of the external power supply does not reach (N1 / (N1+N2))% of the minimum operating load set by the electrolytic cell, the rectifier will automatically switch to the first negative terminal for power supply and the second negative terminal will not be powered; if the output load of the external power supply reaches (N1 / (N1+N2))% of the minimum operating load set by the electrolytic cell, the rectifier will automatically switch to the second negative terminal for power supply and cut off the power supply to the first negative terminal.

[0030] <Example 1> One alkaline electrolyzer with a hydrogen production capacity of 1000 standard cubic meters per hour is equipped with a hydraulic fastening device. The anode plate 2, anode plate assembly 3, intermediate current collector bipolar plate assembly 41, cathode plate assembly 7, cathode plate 8, bipolar plate assembly, sealing gasket 5, and insulating gasket 9 are all square structures. There are a total of 320 bipolar plate assemblies with a rated current of 8000A, N1=160, N2=160, N1 / (N1+N2)=1 / 2, and the minimum operating load set for the electrolyzer is about 30%.

[0031] During the start-up process of the electrolyzer, the output current of the rectifier is <4000A, that is, the load is <50%. The rectifier is always powered by the first negative electrode, and the electrolyzer produces hydrogen by the first bipolar plate unit. During the operation of the electrolyzer, when the external power fluctuation causes the output current of the rectifier to be <4000A, that is, the load is <50%, the rectifier is kept powered by the first negative electrode, and the overall operating load of the electrolyzer can be reduced to 30 × (1 / 2) = 15%.

[0032] <Example 2> One alkaline electrolyzer with a hydrogen production capacity of 2000 standard cubic meters per hour is equipped with a screw fastening device. The anode plate 2, anode plate assembly 3, intermediate current collector bipolar plate assembly 41, cathode plate assembly 7, cathode plate 8, bipolar plate assembly, sealing gasket 5, and insulating gasket 9 are all circular structures. There are a total of 480 bipolar plate assemblies with a rated current of 10000A, N1=160, N2=320, N1 / (N1+N2)=1 / 3, and the minimum operating load set for the electrolyzer is approximately 30%.

[0033] In the initial stage of startup, when the rectifier output current is <3300A (i.e., the load is <33%), the rectifier is powered by the first negative electrode. During startup, as the output power of the external power supply increases, the rectifier output current becomes ≥3300A (i.e., the load becomes ≥33%), and the rectifier automatically switches to the second negative electrode for power supply. All bipolar plate units of the electrolyzer then operate to produce hydrogen, ensuring the continuous operation of the electrolyzer.

[0034] During operation, the external power input of the electrolytic cell is reduced, resulting in the rectifier output current being less than 3300A, i.e. the load is less than 33%. The rectifier automatically switches to the first negative terminal for power supply again, and the overall operating load of the electrolytic cell is reduced to 30 × (1 / 3) = 10%.

[0035] Against the backdrop of the large-scale promotion of green electricity hydrogen production, this invention proposes an alkaline electrolyzer with flexibly adjustable minimum operating load and its adjustment method, which can effectively reduce the minimum operating load to about 10%, enabling the alkaline electrolyzer to adapt to the fluctuating characteristics of green electricity, improve the utilization rate of green electricity, reduce grid electricity consumption, and promote the rapid development of the green electricity hydrogen production industry.

[0036] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. An alkaline electrolytic cell with adjustable minimum operating load, characterized in that, The device includes an electrolytic cell fastening device, and an anode side unit, a first bipolar plate unit, an intermediate current collector bipolar plate unit, a second bipolar plate unit, and a cathode side unit that are sequentially stacked and pressed together by the electrolytic cell fastening device. The lower parts of the anode side unit, the intermediate current collector bipolar plate unit, and the cathode side unit are respectively connected to an anode terminal block, a first cathode terminal block, and a second cathode terminal block. The anode terminal block, the first cathode terminal block, and the second cathode terminal block are respectively connected to the positive copper busbar, the first negative copper busbar, and the second negative copper busbar of the rectifier via copper busbars. The rectifier is connected to an external power source. The first bipolar plate unit includes N1 stacked and pressed first bipolar plate assemblies, and the second bipolar plate unit includes N2 stacked and pressed second bipolar plate assemblies, with the ratio of N1 to N2 being (0.5 to 1):1; sealing gaskets are provided on both sides of each bipolar plate assembly; The rectifier is configured as follows: When the output load of the rectifier does not reach (N1 / (N1+N2))% of the minimum operating load set by the electrolytic cell, the rectifier controls the first negative terminal to be powered and the second negative terminal to be de-powered; conversely, it controls the second negative terminal to be powered and the first negative terminal to be de-powered.

2. The alkaline electrolytic cell with adjustable minimum operating load as described in claim 1, characterized in that, The anode side unit includes an anode end plate assembly connected to the anode terminal block, and an anode end plate attached to the non-active surface of the anode end plate assembly. Insulating pads are provided on both sides of the anode end plate. The active surface of the anode end plate assembly is a concave structure, in which an anode support mesh and an anode electrode are installed. The top and bottom of the anode end plate assembly are respectively provided with a first oxygen flow hole and a first alkali flow hole, both of which are connected to the concave structure.

3. The alkaline electrolytic cell with adjustable minimum operating load as described in claim 2, characterized in that, The first bipolar plate assembly and the second bipolar plate assembly have the same structure, both including a pole frame, pole plates, a cathode support mesh, a cathode electrode, an anode support mesh, an anode electrode, and a diaphragm; The electrode plate is welded inside the electrode frame. Both sides of the electrode plate are concave structures. The cathode support mesh, cathode electrode, and diaphragm are installed in the concave structure on the cathode side of the electrode plate, and the anode support mesh and anode electrode are installed in the concave structure on the anode side of the electrode plate. The top of the electrode frame has a through second oxygen flow hole and a first hydrogen flow hole, which are connected to the concave structure on the anode side and the concave structure on the cathode side, respectively. The bottom of the electrode frame has a through second alkali flow hole, which is connected to the two concave structures.

4. The alkaline electrolytic cell with adjustable minimum operating load as described in claim 3, characterized in that, The intermediate current collector bipolar plate unit includes an intermediate current collector bipolar plate assembly connected to the first cathode terminal block. Both sides of the intermediate current collector bipolar plate assembly are concave structures. A cathode support mesh, a cathode electrode, and a diaphragm are installed in the concave structure on the cathode side of the intermediate current collector bipolar plate assembly, and an anode support mesh and an anode electrode are installed in the concave structure on the anode side of the intermediate current collector bipolar plate assembly. The top of the intermediate current collector bipolar plate assembly has a through third oxygen flow hole and a second hydrogen flow hole, which are connected to the concave structure on the anode side and the concave structure on the cathode side, respectively. The bottom of the intermediate current collector bipolar plate assembly has a through third alkali flow hole, which is connected to the two concave structures.

5. The alkaline electrolytic cell with adjustable minimum operating load as described in claim 3, characterized in that, The cathode-side unit includes a cathode end plate assembly connected to the second cathode terminal block, and a cathode end plate attached to the non-active surface of the cathode end plate assembly. Insulating pads are provided on both sides of the cathode end plate. The active surface of the cathode end plate assembly is a concave structure, in which a cathode support mesh, a cathode electrode, and a diaphragm are installed. A fourth oxygen flow hole and a third hydrogen flow hole are provided through the top of the cathode end plate assembly, and a fourth alkali flow hole is provided through the bottom. The fourth oxygen flow hole, the third hydrogen flow hole, and the fourth alkali flow hole are all connected to the concave structure. The upper part of the cathode end plate is provided with a through fifth oxygen flow hole and a fourth hydrogen flow hole, and the lower part is provided with a through fifth alkali flow hole.

6. A method for adjusting an alkaline electrolyzer with flexibly adjustable minimum operating load as described in claim 1, characterized in that, Includes the following steps: S1: Connect the positive copper busbar, the first negative copper busbar, and the second negative copper busbar of the rectifier to the anode terminal block of the anode side unit, the first cathode terminal block of the intermediate current collector bipolar plate unit, and the second cathode terminal block of the cathode side unit through copper busbars. S2: Start the electrolytic cell. The rectifier controls the first negative electrode to supply power, while the second negative electrode is not supplied with power. During the operation of the electrolytic cell, if the output load of the rectifier does not reach (N1 / (N1+N2))% of the minimum operating load set by the electrolytic cell, the rectifier maintains the first negative electrode supplying power and the second negative electrode not supplying power. If the output load of the rectifier reaches (N1 / (N1+N2))% of the minimum operating load set by the electrolytic cell, the rectifier automatically switches to the second negative electrode supplying power and cuts off the first negative electrode supplying power.

Images