Alkaline electrolyzer

Abstract

The utility model discloses a basic electrolytic cell belongs to electrolytic water hydrogen field. Including setting negative end pressure plate, negative end pole plate, bipolar plate, positive end pole plate, positive end pressure plate in proper order, be equipped with gasket between negative end pole plate and bipolar plate, between positive end pole plate and bipolar plate, the top of negative end pressure plate is equipped with oxygen export and hydrogen export, the negative end pressure plate, negative end pole plate, gasket, bipolar plate, positive end pole plate upper portion all are equipped with lye inlet. Lye inlet on the negative end pressure plate, negative end pole plate, gasket, bipolar plate, positive end pole plate each has two, and is located the top both sides of corresponding component respectively. The basic electrolytic cell provided by the utility model can improve the temperature uniformity of the height direction of the electrolytic cell, improve the sealing reliability and improve the electrolysis efficiency.

Description

Technical Field

[0001] This utility model relates to hydrogen production by water electrolysis, and in particular to an alkaline electrolyzer. Background Technology

[0002] Alkaline water electrolyzers are one of the mainstream technologies for hydrogen production from renewable energy sources. In large-scale filter press fuel cell stacks, thermal management and temperature uniformity are key factors affecting energy efficiency and lifespan. For example... Figure 1-3 As shown, in a traditional electrolytic cell, the electrolyte inlet is located at the bottom of the negative end plate. Low-temperature electrolyte enters the cell from the bottom of the negative end plate, flows through the bottom through-holes of the bipolar plate to the cavity inside the positive end plate, and then flows back from the cavity of the positive end plate to distribute to each electrolytic chamber. During this process, the electrolyte flows in a Z-shaped path, ensuring uniform distribution of the alkali solution. The temperature of the alkali solution entering the electrolytic chamber continuously increases, reaching its maximum at the top, and finally converges and exits through the outlet. Currently, the mainstream design typically uses a bottom inlet combined with a Z-shaped manifold, followed by a flow field from bottom to top within the electrolytic chamber. During operation, the heat of electrolysis (especially ohmic heat) continuously accumulates in the electrolytic chamber. Simultaneously, the current conduction through the metal end plate causes a focusing effect due to resistance, resulting in a significantly higher temperature in the upper region of the negative end plate than in the lower region. The measured temperature gradient exceeds 15°C. Long-term operation can lead to seal aging, stress concentration, and an increased risk of leakage.

[0003] Traditional alkaline electrolytic cells have long suffered from the problem of overheating at the top and a large temperature gradient. The large temperature difference in the height direction of the electrolytic cell will affect the following two aspects: (1) Poor gasket sealing effect: The sealing of alkaline electrolytic cells mainly relies on the compression of modified PTFE gaskets. The compression rate and sealing effect of the gaskets are related to temperature. When there is a continuous temperature difference of 15°C in the height direction of the electrolytic cell, the deformation compression rate of the gaskets along the height direction is different. Under the condition of long-term repeated start-up and shutdown, the pressure and temperature will change periodically, and different areas of the gaskets will have different degrees of stress relaxation, resulting in poor sealing. The risk of failure is significantly increased, and the risk of seal failure is even greater when multiple electrolysis chambers are stacked; (2) The electrolysis efficiency is low: after the low-temperature alkaline solution enters the electrolysis cell, it preferentially cools the bottom area of ​​the electrolysis cell. The temperature in this area is low, resulting in a temperature difference of about 15°C in the height direction of the electrolysis cell. According to the principle of electrochemical reaction, temperature is the key variable that determines the catalytic activity of the catalyst. The higher the temperature, the better the catalytic activity and the higher the electrolysis efficiency; conversely, the lower the temperature, the lower the catalytic efficiency. The large temperature difference inside the electrolysis cell will result in relatively low catalyst activity at the bottom of the electrolysis cell, thus making the overall electrolysis efficiency low. Summary of the Invention

[0004] Purpose of the utility model: The purpose of this utility model is to provide an alkaline electrolytic cell that improves the temperature uniformity in the height direction of the electrolytic cell, improves the sealing reliability, and increases the electrolysis efficiency.

[0005] Technical solution: The alkaline electrolytic cell of this utility model includes a negative end pressure plate, a negative end electrode plate, a bipolar plate, a positive end electrode plate, and a positive end pressure plate arranged in sequence. Gaskets are provided between the negative end electrode plate and the bipolar plate, and between the positive end electrode plate and the bipolar plate. An oxygen outlet and a hydrogen outlet are provided at the top of the negative end pressure plate. An alkaline solution inlet is provided in the upper part of the negative end pressure plate, the negative end electrode plate, the gaskets, the bipolar plate, and the positive end electrode plate.

[0006] Preferably, there are two alkaline inlets on each of the negative end pressure plate, negative end electrode plate, gasket, bipolar plate, and positive end electrode plate, respectively located on the top two sides of the corresponding components.

[0007] Preferably, there are three alkali inlets on each of the negative end pressure plate, negative end electrode plate, gasket, bipolar plate, and positive end electrode plate, which are located on the top of the corresponding components. The alkali inlets on the negative end pressure plate are arranged alternately with the oxygen outlet and hydrogen outlet.

[0008] Preferably, the negative end pressure plate, negative end electrode plate, gasket, bipolar plate, positive end electrode plate, and positive end pressure plate are circular, square, or irregularly shaped.

[0009] Preferably, there are two alkaline inlets on each of the negative end pressure plate, negative end electrode plate, gasket, bipolar plate, and positive end electrode plate, located on the left and right sides of each square component, respectively.

[0010] Preferably, the alkaline inlet is circular or square.

[0011] Preferably, the bipolar plate is made of metal or plastic.

[0012] Beneficial effects: Compared with the prior art, this utility model has the following advantages: (1) The alkaline inlet on each part of the electrolytic cell is set in the middle and upper part, which reduces the temperature difference between the bottom and top of the electrolytic cell and improves the electrolysis efficiency. At present, the industry mainly controls the outlet temperature of the electrolytic cell to about 90°C. The closer the inlet temperature is to the outlet temperature, the better the electrochemical activity of the electrode, the less energy is required for water electrolysis, and the lower the power consumption. (2) Improve the sealing performance of the electrolytic cell: Reduce the temperature difference between the bottom and top of the electrolytic cell. The deformation of the modified PTFE gasket is proportional to the temperature. For large-scale electrolytic cells, the length is long. If the temperature difference between the bottom and top of the electrolytic cell is large, and after long-term pressure, temperature and load changes, it is easy to cause electrolyte leakage. Reducing the temperature difference of the gasket can control its compression rate within an effective range, thereby improving the reliability of the gasket and the electrolytic cell. (3) This utility model has certain versatility. It is not only applicable to round electrolytic cells, but also to square or other irregular electrolytic cells. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the negative end pressure plate in the prior art; Figure 2 This is a schematic diagram of the overall structure of an electrolytic cell in the prior art; Figure 3 This is a schematic diagram of the flow of alkaline solution inside an alkaline electrolytic cell in the prior art; Figure 4 This is a schematic diagram of the electrolytic cell described in Example 1; Figure 5 This is a schematic diagram of the alkaline solution flow inside the electrolytic cell described in this utility model; Figure 6 This is a schematic diagram of the negative end pressure plate described in Example 2; Figure 7 This is a schematic diagram of the negative end pressure plate described in Example 3. Detailed Implementation

[0014] The technical solution of this utility model will be further described below with reference to the embodiments.

[0015] Example 1

[0016] like Figure 4 As shown, the alkaline electrolytic cell of this invention includes a negative end pressure plate 1, a negative end electrode plate 2, a bipolar plate 4, a positive end electrode plate 5, and a positive end pressure plate 6 arranged sequentially. Gaskets 3 are provided between the negative end electrode plate 2 and the bipolar plate 4, and between the positive end electrode plate 5 and the bipolar plate 4. Gaskets (not shown in the figure) are also provided between the negative end pressure plate 1 and the negative end electrode plate 2, and between the positive end electrode plate 5 and the positive end pressure plate 6. In other words, gaskets are provided between every two components to enhance the sealing of the device. The top of the negative end pressure plate 1 has an oxygen outlet 11 and a hydrogen outlet 12. Alkali inlets 7 are provided in the upper part of the negative end pressure plate 1, the negative end electrode plate 2, the gaskets 3, the bipolar plate 4, and the positive end electrode plate 5.

[0017] There are two alkali inlets 7 on each of the negative end pressure plate 1, negative end electrode plate 2, gasket 3, bipolar plate 4, and positive end electrode plate 5, located on the top sides of the respective components. The alkali inlets 7 are circular.

[0018] The negative end pressure plate 1, negative end electrode plate 2, gasket 3, bipolar plate 4, positive end electrode plate 5, and positive end pressure plate 6 are all circular.

[0019] Bipolar plate 4 is made of metal or plastic.

[0020] Example 2

[0021] The similarities between this embodiment and Embodiment 1 will not be repeated here; the differences are as follows: Figure 6As shown, the negative end pressure plate 1 is square, and correspondingly, the negative end electrode plate 2, gasket 3, bipolar plate 4, positive end electrode plate 5, and positive end pressure plate 6 are also square (not shown in the figure). There are three alkali inlets 7 on each of the negative end pressure plate 1, negative end electrode plate 2, gasket 3, bipolar plate 4, and positive end electrode plate 5, located at the top of their respective components. The alkali inlets 7 on the negative end pressure plate 1 are alternately arranged with the oxygen outlet 11 and the hydrogen outlet 12. Within the safe range of the inlet alkali flow rate (generally 1.5-2 m / s), the number of alkali inlets can be flexibly arranged according to actual needs. To ensure more uniform heat exchange, the number of alkali inlets can be alternated with the hydrogen and oxygen outlets.

[0022] Example 3

[0023] The similarities between this embodiment and Embodiment 1 will not be repeated here; the differences are as follows: Figure 7 As shown, the negative end pressure plate 1 is square, and correspondingly, the negative end electrode plate 2, gasket 3, bipolar plate 4, positive end electrode plate 5, and positive end pressure plate 6 are also square (not shown in the figure); the alkali inlet 7 is square, and there are two alkali inlets 7 on each of the negative end pressure plate 1, negative end electrode plate 2, gasket 3, bipolar plate 4, and positive end electrode plate 5, which are located on the left and right sides of the upper middle part of the corresponding components, respectively.

[0024] like Figure 5 As shown, during the use of the alkaline electrolytic cell described in this utility model, the alkaline solution flows into the electrolytic cell from the alkaline solution inlet at the upper part of the negative end pressure plate. Since the temperature of the alkaline solution at the inlet is low, it can reduce the temperature of the upper part inside the electrolytic cell. At the same time, the temperature of the alkaline solution at the inlet is increased through heat exchange. The alkaline solution collected inside the positive end plate is then redistributed to each electrolysis chamber, which again carries away the heat and bubbles inside the electrolytic cell until the outlet of the electrolytic cell.

[0025] The principle behind the alkaline electrolytic cell described in this invention that produces the corresponding technical effects is as follows: (1) Thermal management optimization: alleviate top overheating and reduce vertical temperature difference.

[0026] In traditional alkaline electrolyzers, the alkaline solution flows from bottom to top, resulting in a relatively low temperature at the bottom and a high temperature at the top. Over long-term operation, this leads to a significant temperature gradient within the electrolyzer, with a temperature difference as high as 15-20℃, causing problems such as thermal stress concentration and seal aging. This invention introduces the unreacted, low-temperature alkaline solution from the upper part of the electrolyzer, allowing it to preferentially exchange heat with the upper electrode plates or structural cavities. This effectively absorbs heat from the top, providing active cooling, significantly reducing the risk of overheating at the top, mitigating material fatigue and aging caused by temperature differences, and extending the electrolyzer's lifespan. Related experiments show that this solution can reduce the temperature difference between the inlet and outlet of the electrolyzer to 8-12℃, although this value varies depending on the electrolyzer diameter.

[0027] (2) Improved electrolysis efficiency: Temperature uniformity promotes the consistency of reactions in each unit.

[0028] Temperature is a core parameter affecting electrolysis efficiency. Traditional structures suffer from large temperature differences, with variations in the operating temperatures of different chambers, easily leading to uneven current distribution and impacting overall efficiency and gas purity. This invention modifies the alkali solution flow path, prioritizing heat exchange at the top before uniformly entering the chambers from the bottom. This improves local polarization, reduces uneven gas evolution, lowers energy consumption, and enhances single-cell electrolysis efficiency and gas purity. Related experiments show a 1-3% increase in current efficiency.

[0029] (3) Enhanced sealing performance: relieves high temperature stress and extends gasket life.

[0030] The sealing system is a critical weak point in the long-term operation of alkaline electrolytic cells. The high temperature in the top area makes the sealing material more prone to aging, uneven expansion, and increased leakage risk. This invention significantly reduces the top heat load through top cooling liquid heat exchange, allowing the sealing gasket to operate under lower temperatures for extended periods. It also reduces thermal deformation of the frame caused by temperature differences between the top and bottom, fundamentally improving sealing performance. This invention is particularly suitable for large-size tanks and high current density applications.

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