Modularized alkaline electrolytic cell

Abstract

The invention discloses a modular alkaline electrolytic bath, and belongs to the field of water electrolysis hydrogen production systems. Comprising a small electrolysis chamber, a bipolar plate, a pole frame and an end pressing plate, an alkali liquor outlet is formed in the upper portion of the pole frame, an alkali liquor inlet is formed in the lower portion of the pole frame, n power transmission plates are installed on the periphery of the electrolysis cell, n is an integer not smaller than 3, the power transmission plates are welded to the outer side of the pole frame, and a valve for controlling a switch is arranged on a connecting pipeline of the pole frame and the BOP. The n power transmission plates are one negative electrode power transmission plate and four positive electrode power transmission plates or one positive electrode power transmission plate and four negative electrode power transmission plates. The modularized alkaline electrolytic cell provided by the invention can achieve the effects of module independence, balanced operation and high purity of hydrogen and oxygen.

Description

Technical Field

[0001] This invention relates to a water electrolysis hydrogen production system, and more particularly to a modular alkaline electrolyzer. Background Technology

[0002] Hydrogen energy, as an important component of clean energy, has attracted widespread attention regarding the safety and economic efficiency of its production process. Alkaline electrolyzers are widely used due to their mature technology and low cost, but they have a prominent problem when operating at low loads: when the current density decreases, the electrolysis reaction rate slows down, leading to a significant increase in the hydrogen content in the oxygen, which can easily exceed safety standards and pose an explosion risk. This is the core pain point restricting the flexibility of alkaline electrolyzers and their operation amidst the fluctuations of renewable energy.

[0003] The most common solutions in the industry currently include the following: (1) Start-up and shutdown strategy: When the power is insufficient, the electrolyzer is stopped directly and restarted when the power is restored. Although this method avoids the risk of hydrogen and oxygen exceeding the standard under low load, frequent start-up and shutdown will accelerate equipment aging, increase maintenance costs, and reduce the overall utilization efficiency of the system.

[0004] (2) Additional energy storage system: By configuring batteries or other energy storage devices, surplus electricity can be stored to supplement the operating power of the electrolyzer during off-peak hours. This method can alleviate the low load problem to a certain extent, but the investment in energy storage equipment is huge, which increases the overall cost of the system.

[0005] (3) Nitrogen replacement and dilution: When the electrolyzer is running at low load, the hydrogen concentration is diluted by introducing nitrogen or other inert gases into the oxygen side, thereby reducing the risk of explosion. Although this method is simple, it will significantly reduce the purity of the gas, increase the cost of separation and purification, and is uneconomical to operate.

[0006] (4) Gas-liquid separation and system optimization: Some studies have attempted to reduce the hydrogen content on the oxygen side by improving the gas-liquid separator or adding cooling and degassing steps to the circulating alkali solution. However, such methods often increase equipment complexity and still cannot fundamentally solve the problem of gas composition imbalance under low load operation.

[0007] In summary, all existing solutions have limitations and cannot simultaneously achieve low-load security, operational flexibility, and system economy. Summary of the Invention

[0008] Purpose of the invention: The purpose of this invention is to provide a modular alkaline electrolyzer that balances module independence, balanced operation, and high purity of hydrogen and oxygen.

[0009] Technical solution: The modular alkaline electrolytic cell of the present invention includes an electrolysis chamber, a bipolar plate, an electrode frame, and an end pressure plate. An alkaline solution outlet is opened at the upper part of the electrode frame, and an alkaline solution inlet is opened at the lower part of the electrode frame. n power transmission plates are installed around the electrolytic cell, where n is an integer not less than 3. The power transmission plates are welded to the outside of the electrode frame, and the connecting pipe between the electrode frame and the BOP is equipped with a valve for controlling the switch.

[0010] Preferably, the n transmission plates consist of one negative transmission plate and four positive transmission plates. The negative transmission plate is located on one side of all the transmission plates. The positive transmission plates include a first positive transmission plate located on both sides and a second, third, and fourth positive transmission plate located in the middle. The positive and negative transmission plates respectively form multiple electrolysis modules. The alkali outlet is a first alkali outlet that does not penetrate the electrode frame, and the alkali inlet is an alkali inlet that does not penetrate the electrode frame. The opening direction of the first alkali outlet is opposite to that of the alkali inlet.

[0011] Preferably, the negative electrode transmission board is fixedly connected to the negative electrode of the power supply, and one of the positive electrode transmission boards is selectively connected to the positive electrode of the power supply through a switching device.

[0012] Preferably, temperature sensors are installed in the electrolysis modules at the leftmost and rightmost ends.

[0013] In another preferred embodiment, the n transmission plates consist of one positive transmission plate and four negative transmission plates. The positive transmission plate is located in the middle, and the negative transmission plates include a first negative transmission plate, a second negative transmission plate, a third negative transmission plate, and a fourth negative transmission plate. The first and second negative transmission plates are located on both sides, and the third and fourth negative transmission plates are located on both sides of the positive transmission plate. Multiple electrolysis modules are formed between the negative and positive transmission plates. The alkali outlet is a first alkali outlet that does not penetrate the electrode frame, and the alkali inlet is an alkali inlet that does not penetrate the electrode frame. The opening directions of the first alkali outlet and the alkali inlet are opposite.

[0014] Preferably, the positive electrode transmission board is fixedly connected to the positive electrode of the power supply, and one of the negative electrode transmission boards is selectively connected to the negative electrode of the power supply through a switching device.

[0015] Preferably, each electrolysis module is equipped with a temperature sensor, and an electronic insulation section is provided between the inlet and outlet of the electrolysis module and the BOP.

[0016] Preferably, the switching device is a mechanical or electronic DC switching switch.

[0017] In the third preferred embodiment, the n transmission plates consist of one negative transmission plate and four positive transmission plates. The negative transmission plate is located on one side of all the transmission plates. The positive transmission plates include a first positive transmission plate located on both sides and a second, third, and fourth positive transmission plate located in the middle. The alkali outlet is a second alkali outlet that penetrates the electrode frame. The alkali inlets located at the bottom of the electrode frame connected to the second positive transmission plate are two inlets that do not penetrate the electrode frame and have opposite openings. The alkali inlets located at the bottom of the electrode frames connected to the first, third, and fourth positive transmission plates all penetrate the electrode frame.

[0018] Invention Principle: The modular alkaline electrolyzer of this invention divides the electrolyzer into multiple independent electrolysis modules. The alkaline solutions in each module are not interconnected, and each module has its own independent inlet and outlet pipelines and switching valves. When power is sufficient, multiple modules operate simultaneously; when power is insufficient, only some electrolysis modules can be selected to operate, ensuring good gas purity and system safety even under low load. During operation, the alkaline solution is diverted at the inlet, flowing into each electrolysis module. At the outlet, the gas-liquid mixture generated by each module flows out and is then re-mixed before entering a unified gas-liquid separation and purification system.

[0019] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) High safety: avoids the risk of hydrogen in oxygen or oxygen in hydrogen exceeding the standard due to gas cross-contamination during low load operation, and avoids the dangerous situation of significant increase in hydrogen content in oxygen; (2) Simplified power supply: only one power supply is required, reducing cost and control complexity; (3) Centralized separation: multiple electrolysis modules share a gas-liquid separation unit, reducing redundancy, improving system compactness, and reducing operating costs; (4) Flexible operation: different modules can be selectively activated by switching positive / negative poles to adapt to fluctuating power supply; (5) Extended lifespan: the independence between each module is conducive to reducing the range difference and extending the lifespan of the electrolyzer. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall appearance of Example 1; Figure 2 This is a schematic diagram showing the flow direction of the alkaline solution in the electrolytic cell described in Example 1; Figure 3 These are cross-sectional views of the pole frames in Examples 1 and 2; Figure 4 This is a schematic diagram of the overall appearance of Example 2; Figure 5 This is a schematic diagram showing the flow direction of the alkaline solution in the electrolytic cell described in Example 2; Figure 6 This is a schematic diagram of the overall appearance of Example 3; Figure 7This is a cross-sectional view of the pole frame in Example 3; Figure 8 This is a schematic diagram of the flow direction of the alkaline solution in the electrolytic cell described in Example 3. Detailed Implementation

[0021] The technical solution of the present invention will be further described below with reference to the embodiments.

[0022] Example 1

[0023] like Figure 1-3 As shown, the modular alkaline electrolyzer of the present invention includes an electrolysis chamber, a bipolar plate 20, an electrode frame 16, and an end pressure plate 17. The upper part of the electrode frame 16 has a first alkaline solution outlet 8 with an opening facing right, and the lower part of the electrode frame 16 has an electrolyzer alkaline solution inlet 9 that does not penetrate the electrode frame 16 and has an opening facing left. A negative electrode transmission plate 1 or a positive electrode transmission plate is welded to the outside of the electrode frame 16, and the connecting pipe between the electrode frame 16 and the BOP is equipped with a valve 2 for controlling the switch.

[0024] The negative electrode transmission plate 1 is located on one side of all the transmission plates, and the positive electrode transmission plate includes the first positive electrode transmission plate 3 located on both sides and the second positive electrode transmission plate 4, the third positive electrode transmission plate 5 and the fourth positive electrode transmission plate 6 located in the middle.

[0025] Each positive electrode plate and the negative electrode plate 1 form multiple electrolysis modules 7, and the electrolytes in each electrolysis module 7 are not interconnected.

[0026] The negative power supply board 1 is fixedly connected to the negative power supply, and one of the positive power supply boards is selectively connected to the positive power supply through a switching device.

[0027] A support member 21 is provided at the bottom of the bipolar plate 20 located in the middle of the electrolytic cell to prevent the components in the middle of the electrolytic cell from sagging due to gravity after long-term operation, which would affect the sealing of the electrolytic cell (this structure is the same as in Embodiment 3 and is not shown in Embodiment 1).

[0028] A support plate 18 is mounted on the bottom corner of the end pressure plate 17, and a roller 19 is provided between the support plate 18 and the bottom end of the end pressure plate 17. During the operation of the electrolytic cell, the components will move elastically due to thermal expansion and contraction. The roller 19 helps to reduce the friction during movement (this structure is the same as in Embodiment 3, and is not shown in Embodiment 1).

[0029] The switching device is a mechanical or electronic DC switching switch. During switching, the current needs to be slowly reduced to below 10% of the rated current to avoid arcing.

[0030] A valve 2 is installed at the inlet of each electrolysis module 7, which can effectively control the alkali flow rate of the working module. For the working module, the valve is in the normally open state, while the valve of the non-working module is in the normally closed state.

[0031] Temperature sensors (not shown in the diagram) are installed in the leftmost and rightmost electrolysis modules. Theoretically, the sensors on both sides will have the same temperature when the electrolysis cell is running at full load. When only some electrolysis modules are operating, the leftmost sensor acts as a control point for the electrolysis cell outlet temperature, with an optimal temperature range of 85-95℃. The rightmost sensor controls the temperature of the non-operating modules. When the temperature drops below 60℃, the inlet valve of the non-operating module is opened, allowing high-temperature alkali solution to enter, thereby increasing the alkali solution temperature in the non-operating module and maintaining a hot standby state, thus improving the switching speed of the electrolysis cell from low load to high load.

[0032] An electronic insulation section is provided between the inlet and outlet of electrolysis module 7 and the BOP. The BOP connects different modules, and there is a potential difference between the different modules. Therefore, the electronic path needs to be insulated to prevent short circuits between the modules.

[0033] Each electrolysis module shares a set of electrolyte storage tank, inlet diversion device, and outlet manifold device (none of which are shown in the figure).

[0034] The control system can automatically schedule the module's operating status and adjust the flow rate according to power grid fluctuations to ensure the circulation efficiency of the hot standby compartment and the active compartment.

[0035] During operation, if power is sufficient, open the valve connecting the positive electrode to the electrode furthest from the negative electrode plate, allowing all electrolysis modules to operate simultaneously. If power is insufficient, open the valve connecting the positive electrode to the electrode closest, second closest, or second farthest from the negative electrode plate, allowing only some electrolysis modules to operate. Figure 2 As shown in the figure, the arrows represent the flow direction of the electrolyte. The electrolyte flows into each electrolysis module through the inlet diversion device. After the electrolysis reaction is completed in the electrolysis module, it is merged into the gas-liquid separation and purification system through the outlet manifold device.

[0036] It can be seen that the working time of the first electrolysis module, which is closest to the negative electrode transmission plate, is no less than that of the other electrolysis modules. This results in uneven lifespans of the electrolysis modules. The structure of the following embodiment 2 can solve this problem.

[0037] Example 2

[0038] like Figure 2 , 4As shown in Figure 5, the modular alkaline electrolyzer described in this embodiment is similar to that in Embodiment 1 and will not be repeated here. The difference is that it includes an electrolysis chamber, a bipolar plate 20, an electrode frame 16, and an end pressure plate 17. The upper part of the electrode frame 16 has a first alkaline solution outlet 8 with an opening facing right, and the lower part of the electrode frame 16 has an electrolyzer alkaline solution inlet 9 that does not penetrate the electrode frame 16 and has an opening facing left. The positive electrode transmission plate 11 or the negative electrode transmission plate is welded to the outside of the electrode frame 16. The connecting pipe between the electrode frame 16 and the BOP is equipped with a valve 2 for controlling the switch.

[0039] The positive electrode transmission plate 11 is located in the middle, and the negative electrode transmission plate includes a first negative electrode transmission plate 12, a second negative electrode transmission plate 13, a third negative electrode transmission plate 14, and a fourth negative electrode transmission plate 15. The first negative electrode transmission plate 12 and the second negative electrode transmission plate 13 are located on both sides of all the transmission plates, and the third negative electrode transmission plate 14 and the fourth negative electrode transmission plate 15 are located on both sides of the positive electrode transmission plate 11.

[0040] Each negative electrode power transmission plate and the positive electrode power transmission plate 11 form multiple electrolysis modules 7, and the electrolytes of each electrolysis module 7 are not interconnected.

[0041] The positive power supply plate 11 is fixedly connected to the positive power supply, and one of the negative power supply plates is selectively connected to the negative power supply through a switching device.

[0042] Each electrolysis module is equipped with a temperature sensor (not shown in the figure) to detect the temperature of the working and non-working modules.

[0043] Compared with Example 1, Example 2 has the following advantages: the positive electrode transmission plate is located in the middle of the auxiliary device, and the negative electrode transmission plates that can be selectively switched are respectively arranged on both sides. Since the two electrolysis modules adjacent to the positive electrode transmission plate have the same function, the electrolysis modules can be used in turn, which can avoid the defect of uneven lifespan between other electrolysis modules caused by the long-term use of one electrolysis module.

[0044] Example 3

[0045] like Figure 6-8 The modular alkaline electrolyzer described in this embodiment is similar to that in Embodiment 1, and the difference is that it includes an electrolysis chamber, a bipolar plate 20, an electrode frame 16, and an end pressure plate 17. A second alkaline outlet 10 is provided on the upper part of the electrode frame 16, and a negative electrode transmission plate 1 or a positive electrode transmission plate is welded to the outside of the electrode frame 16.

[0046] The negative electrode transmission plate 1 is located on one side of all the transmission plates, and the positive electrode transmission plate includes the first positive electrode transmission plate 3 located on both sides and the second positive electrode transmission plate 4, the third positive electrode transmission plate 5 and the fourth positive electrode transmission plate 6 located in the middle.

[0047] The alkaline inlet 9 located at the bottom of the pole frame 16 connected to the second positive electrode transmission plate 4 consists of two inlets that do not penetrate the pole frame 16 and have opposite openings. The alkaline inlets 9 located at the bottom of the pole frame 16 connected to the first positive electrode transmission plate 3, the third positive electrode transmission plate 5 and the fourth positive electrode transmission plate 6 all penetrate the pole frame 16.

[0048] The electrode frame 16, which is welded with the third positive electrode transmission plate 5, is connected to the BOP via two valves 2 with control switches, which are used to control the electrolysis modules on the left and right sides of the third positive electrode transmission plate 5, respectively.

[0049] The negative power supply board 1 is fixedly connected to the negative power supply, and the third positive power supply board 5 is connected to the positive power supply.

[0050] Temperature sensors (not shown in the figure) are installed in the leftmost and rightmost electrolysis modules. The temperature sensor on the left is used to monitor the temperature of the working chamber to prevent local overheating. The signal from this sensor is used to control the maximum allowable operating temperature of the electrolyzer, which is approximately 90±2℃. The cooling system of the hydrogen production system maintains this temperature as the optimal temperature.

[0051] The temperature sensor on the right monitors the temperature of the non-working compartment. The controller, based on the sensor signal, adjusts the valve opening time to maintain the inactive compartment in a hot standby state. The electrolytic cell operates at approximately 90±2℃. When the temperature of the non-working compartment is detected to be below 60℃, the alkali solution switching valve for that compartment opens, allowing high-temperature alkali solution to flow into the non-working compartment, raising its temperature and maintaining it in a hot standby state, thus improving its rapid response speed. When the temperature exceeds 70℃, the switching valve closes, allowing only the alkali solution in the working compartment to flow normally, reducing pressure loss throughout the electrolytic cell and improving operating efficiency.

[0052] A variable frequency circulating pump is matched in the electrolytic cell, which automatically adjusts the flow rate according to the number of active cells to ensure hot standby and circulation efficiency of active cells.

[0053] In use, if the power is insufficient, open the valve on the left to allow the alkali solution to enter the electrolytic cell through the alkali solution inlet on the left, flow into the electrolysis module on the left, and enter the electrolysis chamber. The outlet is then connected to the electrode frame outlet connected to the second power supply plate and connected to the BOP system. If the power is sufficient, open both valves, and allow the alkali solution to enter the electrolytic cell through the alkali solution inlets on the left and right sides respectively. After electrolysis occurs in the electrolysis modules on both sides, the solution flows into the BOP system through the alkali solution outlet at the top of the electrode frame connected to the second power supply plate.

Claims

1. A modular alkaline electrolytic cell, comprising an electrolysis chamber, bipolar plates (20), an electrode frame (16), and an end pressure plate (17), wherein the upper part of the electrode frame (16) has an alkaline solution outlet, and the lower part of the electrode frame (16) has an alkaline solution inlet, characterized in that, n power transmission plates are installed around the electrolytic cell, where n is an integer not less than 3. The power transmission plates are welded to the outside of the pole frame (16). The connection pipe between the pole frame (16) and the BOP is equipped with a valve (2) for controlling the switch.

2. The modular alkaline electrolytic cell according to claim 1, characterized in that, The n power transmission plates are one negative power transmission plate (1) and four positive power transmission plates.

3. The modular alkaline electrolytic cell according to claim 2, characterized in that, The negative electrode plate (1) is located on one side of all the electrode plates. The positive electrode plate includes a first positive electrode plate (3) located on both sides and a second positive electrode plate (4), a third positive electrode plate (5) and a fourth positive electrode plate (6) located in the middle. The positive electrode plate and the negative electrode plate (1) respectively form multiple electrolysis modules (7). The alkaline outlet is a first alkaline outlet (8) that does not penetrate the electrode frame (16). The alkaline inlet is an alkaline inlet (9) that does not penetrate the electrode frame (16). The opening direction of the first alkaline outlet (8) and the alkaline inlet (9) is opposite.

4. The modular alkaline electrolytic cell according to claim 1, characterized in that, The n power transmission plates are one positive power transmission plate (11) and four negative power transmission plates.

5. The modular alkaline electrolytic cell according to claim 4, characterized in that, The positive electrode plate (11) is located in the middle, and the negative electrode plate includes a first negative electrode plate (12), a second negative electrode plate (13), a third negative electrode plate (14), and a fourth negative electrode plate (15). The first negative electrode plate (12) and the second negative electrode plate (13) are located on both sides, and the third negative electrode plate (14) and the fourth negative electrode plate (15) are located on both sides of the positive electrode plate (11). The negative electrode plate and the positive electrode plate (11) respectively form multiple electrolysis modules (7). The alkaline outlet is a first alkaline outlet (8) that does not penetrate the electrode frame (16), and the alkaline inlet is an alkaline inlet (9) that does not penetrate the electrode frame (16). The opening directions of the first alkaline outlet (8) and the alkaline inlet (9) are opposite.

6. The modular alkaline electrolytic cell according to claim 2, characterized in that, The negative electrode plate (1) is located on one side of all the electrode plates. The positive electrode plate includes a first positive electrode plate (3) located on both sides and a second positive electrode plate (4), a third positive electrode plate (5) and a fourth positive electrode plate (6) located in the middle. The alkaline outlet is a second alkaline outlet (10) that penetrates the electrode frame (16). The alkaline inlet (9) opened at the bottom of the electrode frame (16) connected to the second positive electrode plate (4) are two inlets that do not penetrate the electrode frame (16) and have opposite openings. The alkaline inlets (9) opened at the bottom of the electrode frame (16) connected to the first positive electrode plate (3), the third positive electrode plate (5) and the fourth positive electrode plate (6) all penetrate the electrode frame (16).

7. The modular alkaline electrolytic cell according to claim 3, characterized in that, The negative electrode power supply board (1) is fixedly connected to the negative electrode of the power supply, and one of the positive electrode power supply boards is selectively connected to the positive electrode of the power supply through a switching device.

8. The modular alkaline electrolytic cell according to claim 5, characterized in that, The positive electrode transmission plate (11) is fixedly connected to the positive electrode of the power supply, and one of the negative electrode transmission plates is selectively connected to the negative electrode of the power supply through a switching device.

9. The modular alkaline electrolytic cell according to claim 7 or 8, characterized in that, The switching device is a mechanical or electronic DC switching switch.

10. The modular alkaline electrolytic cell according to claim 3 or 5, characterized in that, An electronic insulation section is provided between the inlet and outlet of the electrolysis module (7) and the BOP.

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