A falling film electrolyzer and an electrolysis system for reducing energy consumption of a water hydrogen production electrolyzer

Abstract

The utility model belongs to electrolytic technical field provides a kind of falling film electrolytic cell and electrolytic system for reducing water hydrogen electrolytic cell energy consumption, the electrolytic cell is alkaline electrolytic cell or PEM electrolytic cell, the upper portion of the tank body is equipped with liquid falling film device for making electrode surface cover downward flowing liquid film, the liquid falling film device selects one or more of overflow device, high pressure distribution device or flushing device;When electrolytic cell is alkaline electrolytic cell, the upper portion of tank body on both sides of each pair of electrode plate is equipped with liquid falling film device, when electrolytic cell is PEM electrolytic cell, the upper portion of tank body on anode side is equipped with liquid falling film device.The electrolytic cell described in the utility model covers the surface of electrode plate far from diaphragm in the form of falling film flow with electrolyte, significantly reduces the formation and accumulation of gas bubble on electrode surface, thereby reducing local overpotential and reducing electric energy consumption;And the falling film electrolytic cell structure improvement is simple, maintenance is convenient, and it is convenient to use.

Description

Technical Field

[0001] This utility model belongs to the field of electrolysis technology, specifically, it relates to a falling film electrolyzer and electrolysis system for reducing the energy consumption of a water-to-hydrogen electrolyzer. Background Technology

[0002] Hydrogen plays a crucial role in the transition to a cleaner, more sustainable, and lower-emission zero-carbon energy system. As a feedstock for industrial production, hydrogen is widely used in oil refining, ammonia synthesis, methanol synthesis, and other chemical processes. Reports indicate that hydrogen applications account for 33% in oil refining, 27% in ammonia synthesis, 10% in methanol synthesis, 5% in the steel industry, and approximately 26% in other sectors. Globally, hydrogen production via electrolysis accounts for only 4% of total hydrogen production due to its higher cost compared to fossil fuels. However, water electrolysis can be flexibly coupled with renewable energy sources (wind, solar, hydropower, etc.) to convert intermittent renewable electricity into hydrogen for storage, thus mitigating the instability of renewable energy grid connection. As a key industrial feedstock and clean energy carrier, hydrogen plays an irreplaceable role in promoting global and Chinese low-carbon transformation. With technological advancements and cost reductions, water electrolysis is expected to play an even greater role in energy transition and the achievement of zero-carbon goals.

[0003] Hydrogen production technologies through water electrolysis mainly include alkaline water electrolysis (AWE) and proton exchange membrane electrolysis (PEM). Currently, during the operation of hydrogen production equipment, the impact of bubbles is a long-standing limiting issue for the performance of water electrolysis hydrogen production. Bubbles of different scales generated during electrolysis cause problems such as hindering catalyst active sites, increasing electrolyte resistance, bubble accumulation leading to localized overheating, corrosion of the gas-liquid-solid three-phase interface, reduced gas purity, pressure imbalance, reduced gas-liquid separator volume (slow heating and slow start-up), pump cavitation, and other issues. Under the combined effect of these problems, industrial water electrolysis hydrogen production faces challenges such as high energy loss, difficulty in increasing current density, poor adaptability to the volatility of renewable energy sources, and the risk of hydrogen-oxygen mixture explosions.

[0004] To improve the performance of water-to-hydrogen electrolyzers, existing technologies offer many improvement methods. For example, applying an external physical field during electrolysis accelerates bubble desorption, thereby reducing battery voltage and energy consumption. However, this method requires additional equipment to generate the external physical field, significantly increasing investment costs and potentially leading to material fatigue or wear, making its industrial-scale application challenging. Another approach is to add surfactants to the electrolyte to alter the interfacial properties of bubbles and reduce bubble retention; however, this direct surfactant addition method also presents problems in practice. Surfactants can cause side reactions on the electrode surface, leading to energy consumption and even catalyst poisoning. Furthermore, the presence of surfactants can form a stable microbubble emulsion system, increasing the difficulty of subsequent gas-liquid separation. These issues hinder the widespread industrial application of surfactant-added methods.

[0005] Furthermore, existing technical solutions are based on providing "passive" bubble management methods on submerged electrolyzers, which all accelerate the desorption and removal of generated bubbles, but fail to fundamentally change the bubble generation environment.

[0006] To address the impact of air bubbles, researchers developed a novel capillary electrolyzer, as illustrated in the paper Nature Communications, 2022, 13(1): 1. Article 11 discloses a capillary alkaline electrolyzer. This type of electrolyzer utilizes capillary action to absorb electrolyte through the diaphragm between the electrode plates, wetting the side of the electrode plates facing the diaphragm, and then carrying out the electrolytic reaction. Since the electrode plates and the diaphragm are in close contact, this method can effectively mitigate the influence of air bubbles. However, this technical solution can only be applied in the laboratory stage and cannot be industrially promoted for the following reasons: (1) When this type of electrolyzer is running, the electrolyte flows upward through the diaphragm wetting. Since the diaphragm, cathode, and anode are in close contact, the circulation of the electrolyte is very slow during operation. If a scale-up experiment is conducted, the process will be even slower. As shown in the data in the above literature, as the height of the diaphragm increases, the flow rate of electrolyte that can be transported by capillary action will decrease, and the maximum electrolytic current density that can be supported will also decrease. Therefore, this structure cannot be used in large-scale production equipment. (2) Since this device wets the electrode surface, in practical applications, technicians need to screen the parameters of the diaphragm (including pore size, surface structure, etc.), and the electrode structure needs to adopt a porous structure to provide a high specific surface area and abundant active sites so that the electrolysis reaction can operate normally, and the directional escape of H2 and O2 must be considered. Therefore, it cannot be obtained by simply modifying a traditional electrolyzer, and the modification cost is very high. In addition, it is also very difficult to apply this type of electrolyzer structure to a PEM electrolyzer.

[0007] Therefore, it remains essential to design a water-to-hydrogen electrolyzer that can be applied on an industrial scale and effectively reduce the negative impact of bubbles. Utility Model Content In view of this, the present invention provides a falling film electrolyzer and electrolysis system for reducing the energy consumption of water-to-hydrogen electrolyzers, offering a novel solution and combining it with a new electrolyzer to reduce the generation of bubbles at the source, thereby effectively eliminating the impact of bubbles.

[0008] To achieve the above objectives, the technical solution of this utility model is as follows: A falling film electrolyzer for reducing energy consumption in water-to-hydrogen electrolyzers, comprising a tank body and one or more parallel electrolysis chambers disposed within the tank body, each electrolysis chamber comprising a pair of electrode plates and a diaphragm sandwiched between the pair of electrolysis plates, wherein the electrolyzer is an alkaline electrolyzer or a PEM electrolyzer; a liquid falling film device is provided in the upper part of the tank body, through which electrolyte entering the tank body via the electrolyte inlet is covered by the liquid falling film device to form a downward flowing liquid film on the surface of the electrode plates away from the diaphragm; the liquid falling film device is selected from one or more of an overflow device, a high-level pressure distribution device, or a flushing device; wherein... The overflow device includes an overflow weir and a horizontal support plate for supporting the bottom of the overflow weir. The overflow weir is slidably placed on the horizontal support plate. A guide plate inclined downwards along the direction close to the electrode plate is provided on the overflow port side of the overflow weir. After the electrolyte entering the overflow weir overflows through the overflow port side, it flows downwards along the guide plate to the surface of the electrode plate, forming a downward-flowing liquid film. The high-level pressure distribution device includes a horizontal partition that divides the tank into upper and lower parts. The upper part forms a high-level liquid storage tank. A liquid distribution slit is provided between the side of the horizontal partition close to the electrode plate and the electrode plate. The electrolyte in the high-level liquid storage tank flows downwards through the liquid distribution slit to the surface of the electrode plate, forming a downward-flowing liquid film. The flushing device includes at least one nozzle. The inlet of the nozzle is connected to the electrolyte inlet. The outlet of the nozzle is directly opposite the top of the electrode plate and perpendicular to the surface of the electrode plate. The electrolyte sprayed through the nozzle flushes the electrode plate and forms a continuously downward-flowing liquid film on its surface. When the electrolytic cell is an alkaline electrolytic cell, the liquid falling film device is provided on the upper part of the tank body on both sides of the pair of electrode plates; when the electrolytic cell is a PEM electrolytic cell, the liquid falling film device is provided on the upper part of the tank body on the anode side.

[0009] Furthermore, when the liquid falling film device uses an overflow device, an adjusting bolt is installed on the outer wall of the tank body away from the overflow port. The adjusting bolt extends into the inner end of the tank body and abuts against the side wall of the overflow weir, which is used to adjust the horizontal distance between the overflow weir and the electrode plate.

[0010] Furthermore, the overflow outlet of the overflow weir is serrated. This type of falling film electrolyzer achieves a relatively uniform liquid film distribution on a large-area electrode through the overflow weir.

[0011] Furthermore, when the liquid falling film device is a high-pressure distribution device, the width of the liquid distribution slit is 2~5mm.

[0012] Furthermore, when the liquid falling film device is a high-pressure distribution device, an overflow port is also provided on the top side wall of the tank above the horizontal partition. This high-pressure electrolyte distribution method is suitable for scenarios where liquid is prone to accumulation or where precise liquid volume control is required, achieving stable liquid distribution by adjusting the liquid level pressure.

[0013] Furthermore, when the electrolytic cell is a PEM electrolytic cell, the angle θ between the electrode plate and the diaphragm and the horizontal direction is 45~90°; preferably 45~75°.

[0014] Furthermore, the thickness of the liquid film on the surface of the electrode plate is 0.5~2.0 mm.

[0015] This utility model also provides a water-to-hydrogen electrolysis system, including a falling film electrolyzer, a gas-liquid separation device, and a circulating pump. The gas-liquid separation device has a gas phase outlet at its top and a liquid phase outlet at its bottom, and a gas-containing electrolyte inlet on its side wall. The gas-containing electrolyte inlet is connected to the electrolyte outlet of the tank, and the liquid phase outlet is connected to the electrolyte inlet of the tank. A circulating pump is installed on the connecting pipeline between the liquid phase outlet and the electrolyte inlet. The falling film electrolyzer is the aforementioned falling film electrolyzer. The addition of the gas-liquid separation device in the water-to-hydrogen electrolysis system promptly discharges the gas generated in the circulating liquid. This invention provides a falling film electrolyzer for reducing energy consumption in water-to-hydrogen electrolyzers. It replaces traditional immersion contact by allowing the electrolyte to form a rapidly flowing thin liquid film on the electrode surface. In this method, the gas generated by the electrodes migrates out of the liquid film through an efficient "dissolution-diffusion" mechanism before forming macroscopic bubbles, thus fundamentally avoiding overpotential loss caused by the traditional bubble effect.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) Compared with traditional immersion alkaline and PEM electrolyzers, the falling film electrolyzer provided by this utility model is superior. By covering the electrode plate with the electrolyte in a falling film flow manner on the side away from the diaphragm, the hydrogen and oxygen generated by the reaction can escape from the liquid phase and enter the gas phase in a timely manner, which significantly reduces the formation and accumulation of bubbles on the electrode surface. The bubble coverage rate on the electrode surface can be greatly reduced, and the gas content of the electrolyte is also reduced, thereby reducing local overpotential and energy consumption. This improvement also helps to stably increase the current density and expand the operating range of the electrolysis equipment.

[0017] (2) By adopting the technical solution of this utility model, the gas generated can quickly diffuse to the outside of the liquid film, reducing the adhesion and obstruction caused by bubble growth; at the same time, it can quickly remove the heat of reaction and product gas, avoiding local overheating and accumulation of high-concentration ion areas, thereby maintaining a better consistency of the reaction environment. Based on this mechanism, under the same operating current density, this utility model can effectively reduce energy loss and improve electrolysis efficiency.

[0018] (3) The falling film electrolytic cell of this utility model does not require the introduction of expensive or scarce materials, and does not require optimization and screening of electrode and membrane materials. The overall structure of the device is relatively simple and can be obtained by simple modification based on the existing traditional immersion electrolytic cell. The modification cost is low and it has good industrial adaptability.

[0019] (4) For alkaline electrolyzers and PEM electrolyzers of different sizes or structures, this utility model provides multiple distribution modes such as overflow type, direct flushing type, and high-level liquid storage tank pressure distribution. Each distribution mode can also be combined with each other, with high process flexibility, which can meet the diverse needs from laboratory research to industrial scale-up. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the falling film alkaline electrolyzer described in Example 1.

[0021] Figure 2 This is a schematic diagram of the falling film electrolytic cell experimental system in Example 1.

[0022] Figure 3 This is a schematic diagram of the immersion electrolytic cell experimental system in Comparative Example 1.

[0023] Figure 4 The images show the bubble conditions on the electrode surface during the electrolysis reaction in Example 1 and Comparative Example 1. A represents Example 1, and B represents Comparative Example 1.

[0024] Figure 5 The air volume fraction on the electrode surface under different inlet flow rates in Example 3 is represented by the inlet flow rates increasing sequentially from A to D.

[0025] Figure 6 The results are from the impedance characteristic characterization experiment in Example 4.

[0026] Figure 7 This is a schematic diagram of the falling film alkaline electrolyzer described in Example 5.

[0027] Figure 8 for Figure 7 Side view of the central overflow weir.

[0028] Figure 9 This is a schematic diagram of the falling film alkaline electrolyzer described in Example 6.

[0029] Figure 10 This is a schematic diagram of the falling film PEM electrolyzer described in Example 7.

[0030] Figure 11 This is a schematic diagram of the falling film PEM electrolyzer described in Example 8.

[0031] The components include: 1. Tank body; 101. Cathode plate; 102. Anode plate; 103. Diaphragm; 104. Electrolyte outlet; 105. Electrolyte inlet; 106. Vent; 107. Overflow weir; 108. Horizontal support plate; 109. Guide plate; 110. Adjusting bolt; 111. Horizontal baffle; 112. High-level liquid storage tank; 113. Liquid distribution slit; 114. Electrolyte overflow outlet; 2. Fluid pulse damper; 3. Peristaltic pump; 4. Electrolyte storage tank; 5. Electrochemical workstation; 6. Computer; 7. Industrial camera; 8. LED fill light. Detailed Implementation

[0032] The technical solution of this utility model will be clearly and completely described below with reference to specific embodiments. It should be understood that the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of this utility model. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar with the art.

[0033] Example 1 like Figure 1As shown, this embodiment provides a falling film alkaline electrolyzer, including a tank body 1, a cathode plate 101 and an anode plate 102 disposed within the tank body 1, and a diaphragm 103 provided between the cathode plate 101 and the anode plate 102. The diaphragm is used to prevent the mixing of gases generated on both sides of the cathode and anode. Adjacent cathode plates 101 and anode plates 102 form an electrolysis chamber. A pair of electrolyte inlets 105 and electrolyte outlets 104 are respectively opened on the upper sidewalls and bottom of the tank body 1 on both sides of the cathode plate 101 and the anode plate 102, and a pair of exhaust ports 106 are opened on the top for discharging the produced hydrogen and oxygen; liquid falling film devices are also respectively provided on the upper part of the tank body 1 on both sides of the cathode plate 101 and the anode plate 102.

[0034] In this embodiment, the electrolyte entering the tank 1 is distributed by liquid flushing. The liquid falling film device includes a circular nozzle (not shown in the figure). The inlet of the circular nozzle is inserted into the electrolyte inlet 105 and connected to the electrolyte supply pipe. The outlet of the circular nozzle is directly opposite the top of the cathode plate 101 and the anode plate 102 and is perpendicular to the surfaces of the cathode plate 101 and the anode plate 102. The electrolyte sprayed through the nozzle flushes the surfaces of the cathode plate 101 and the anode plate 102, forming a downward-flowing liquid film on the side of the electrode plate away from the diaphragm in a falling film flow manner, and then is discharged through the electrolyte outlet 104.

[0035] This embodiment uses, as follows: Figure 2 The electrolytic cell experimental system shown is used to test the performance of the aforementioned falling film alkaline electrolytic cell. The electrolytic cell experimental system includes an electrolytic cell, a fluid pulse damper 2, a peristaltic pump 3, an electrolyte storage tank 4, an electrochemical workstation 5, a computer 6, an industrial camera 7, and an LED supplementary light 8. The electrolyte inlet located at the top of the cell 1 and the electrolyte outlet at the bottom are both connected to the electrolyte storage tank 4. The fluid pulse damper 2 and the peristaltic pump 3 are installed on the connecting pipe between the electrolyte inlet and the electrolyte storage tank. By adjusting the pump flow rate, the flow rate entering the electrolytic cell can be precisely controlled, thereby regulating the thickness and renewal rate of the falling film. The electrochemical workstation 5 is connected to the electrolytic cell to monitor the voltage and operating current of the cell 1 in real time. The industrial camera 7 and the LED supplementary light 8 are used for visual analysis of the experimental results.

[0036] In this embodiment, both the cathode and anode are made of nickel mesh commonly used in the art, the diaphragm is a PPS diaphragm commonly used in the art, a 30% KOH aqueous solution is used as the electrolyte, the effective geometric area of ​​the electrode is 5.199 cm², and it operates at room temperature (approximately 25°C). The operation process of the electrolysis system is as follows: S1. Pre-wetting: Before electrolysis begins, the electrolyte is first delivered. The electrolyte enters the tank 1 through the top electrolyte inlet 105 and the nozzle. The flow rate is adjusted so that the electrolyte sprayed through the nozzle forms a liquid film on the electrode surface and flows downwards. It is then discharged into the electrolyte storage tank 4 through the electrolyte outlet 104. The system runs continuously for about 5 to 10 minutes to fully pre-wet the electrodes and diaphragm, ensuring that the electrode surface is uniformly and stably covered by the electrolyte, forming an effective falling film state.

[0037] S2. When the DC power supply is turned on, an electrolytic reaction occurs on the cathode plate 101 and the anode plate 102, producing hydrogen and oxygen.

[0038] In this embodiment, the electrolyte circulation flow rate entering the electrolytic cell through the electrolyte inlet was set to 400 mL / min. Constant voltages of 1.9V, 2.0V, 2.2V, 2.4V, 2.6V, and 2.8V were applied to the electrolytic cell, and after stabilizing for 10 minutes at each voltage point, the steady-state operating current density was recorded. The results are shown in Table 1. Simultaneously, the bubble behavior and liquid film state on the electrode surface were recorded using an industrial camera. Figure 4 As shown.

[0039] Comparative Example 1 like Figure 3 As shown, compared to Example 1, the difference lies in that this comparative example uses a conventional fully submerged electrolytic cell. The electrolytic cell is filled with electrolyte, and the electrodes are completely submerged in the electrolyte. The electrolyte inlet is located at the bottom of the electrolytic cell, and the electrolyte outlet is located at the top. All other experimental conditions are the same. Constant voltages of 1.9V, 2.0V, 2.2V, 2.4V, 2.6V, and 2.8V were applied to the electrolytic cell, and after stabilizing for 10 minutes at each voltage point, the steady-state operating current density was recorded. The results are shown in Table 1 below. Simultaneously, the bubble behavior and liquid film state on the electrode surface were recorded using an industrial camera, as shown below. Figure 4 As shown.

[0040] Table 1 Electrolysis current density (A / m²) at different potentials As shown in Table 1, the falling film electrolyzer exhibits significant performance advantages in the lower voltage range. At 1.9 V, the current density of the falling film mode (294.0 A / m²) is approximately 13.0% higher than that of the immersion mode (260.2 A / m²). At a typical industrial voltage of 2.0 V, the current density of the falling film mode (841.4 A / m²) further increases to approximately 28.2% compared to the immersion mode (656.1 A / m²). Figure 4The visual observation images show that there are almost no bubbles on the electrode surface in the falling film electrolyzer, and the electrolyte is clear, while there are many bubbles in the submerged electrolyzer, and the electrolyte is significantly more turbid. This proves the effectiveness of the technical solution of this utility model in suppressing bubbles.

[0041] Example 2 The falling film alkaline electrolyzer and experimental system shown in Example 1 were used. The difference from Example 1 was that the electrolyte circulation flow rate of the falling film electrolyzer was changed under a constant voltage of 1.95V. The flow rate of the circulation pump 3 was adjusted to 200, 300, 400, 600, and 1200 mL / min in sequence. After stabilizing at each flow rate point, the corresponding steady-state current density was recorded and compared with the conventional fully submerged electrolyzer described in Comparative Example 1. Under a constant voltage of 1.95V, the current density of the fully submerged electrolyzer during electrolysis was 381.7658 A / m². The results are shown in Table 2 below.

[0042] Table 2. Effect of electrolyte flow rate on falling film mode current density (voltage = 1.95V) As shown in Table 2, in falling film mode, when the flow rate increases from 200 mL / min to 1200 mL / min, the current density increases from 364 A / m² to 548 A / m², and the performance can be further improved by 50.7%, proving that the electrolysis efficiency can be effectively optimized by adjusting the flow rate. Furthermore, when the flow rate increases to above 300 mL / min, the electrical performance is significantly better than that of the submerged electrolyzer. Considering that the efficiency of improving electrical performance begins to decline after the flow rate reaches ≥400 mL / min, and that excessively high flow rates will lead to increased electrolysis costs, in subsequent embodiments, the electrolyte flow rate is preferably 400 mL / min.

[0043] Example 3 To further investigate the macroscopic flow characteristics of the film under varying electrolyte flow rates, particularly the changes in film thickness and velocity, and their relationship with electrolytic performance, this study employed the CFD module of COMSOL Multiphysics software to conduct a two-dimensional hydrodynamic simulation of the two-phase flow within the electrolytic cell. To simplify the calculations, an air-water system was used in the simulation, and the turbulent k-ε model combined with the level set method was applied to track the gas-liquid interface. This simulation assumed that the KOH solution was homogeneous and that the temperature was uniform and at room temperature throughout, meaning it only included the simulation of the flow state.

[0044] The inlet flow rates set in the simulation were 1.06 m / s, 1.59 m / s, 2.12 m / s, and 3.18 m / s, corresponding to the electrolyte circulation rates of 200 mL / min, 300 mL / min, 400 mL / min, and 600 mL / min used in the experiment. The simulation process first initialized the phase through a steady-state solution step, followed by a transient solver to simulate flow development until the flow reached a quasi-steady state for analysis. After the flow stabilized, the liquid film thickness and the average flow velocity at a specific vertical position in the middle of the electrode, i.e., y = -50 mm, were calculated. The simulation results are shown in Table 3 and... Figure 5 As shown.

[0045] Table 3 Simulated liquid film thickness and average flow velocity at different flow rates According to Table 3 and Figure 5 The simulation results show that as the flow rate increases from 200 mL / min to 600 mL / min, the liquid film thickness shows a slight increasing trend, while the average flow velocity of the liquid film at the same location shows a significant and continuous increase. That is, the increase in electrolyte circulation flow rate mainly leads to a significant increase in liquid film flow velocity, which enhances convection, improves bubble management, and enhances mass transfer to obtain higher current density.

[0046] Example 4 To further investigate the intrinsic mechanism by which falling film flow improves electrolysis performance and to explain the performance differences observed at specific voltages, this embodiment utilizes electrochemical impedance spectroscopy (EIS) to characterize the impedance characteristics of falling film and submerged operating modes using the electrolyzers described in Example 1 and Comparative Example 1, respectively, under a constant voltage of 2.0 V and an electrolyte flow rate of 400 mL / min. The EIS test frequency range was 0.01 Hz to 100 kHz, and the applied AC perturbation voltage amplitude was 10 mV. The test results are shown in Table 4 below. Figure 6 As shown.

[0047] Table 4 Electrochemical impedance spectroscopy test results For Table 4 and Figure 6 Analysis of the test results shows that, compared with the immersion method, although the solution resistance is slightly higher in the falling film method, the polarization resistance is significantly reduced. The resistance of the immersion mode electrolysis is about 35.86% higher than that of the falling film mode electrolysis. Polarization resistance (R...) pThe significant reduction in the polarization resistance is a comprehensive manifestation of how falling film flow effectively improves the electrode interface process. On the one hand, the extremely thin liquid film inhibits the coverage of bubbles on the electrode surface, increasing the effective electrochemical reaction area and thus reducing the charge transfer resistance. On the other hand, the thin and rapidly renewing liquid film greatly enhances the transport of reactants to the electrode surface and the transport of products from the electrode surface, effectively mitigating the concentration gradient and thus significantly reducing the mass transfer resistance. Falling film flow effectively improves the kinetic performance of the alkaline water electrolysis process by significantly reducing the polarization resistance of the electrode process.

[0048] Example 5 refer to Figure 7 and Figure 8 This embodiment provides a falling film alkaline electrolyzer. Compared with Embodiment 1, the difference is that: in this embodiment, the liquid falling film device includes a pair of overflow weirs 107 installed on the upper part of the tank body 1 on both sides of the cathode plate 101 and the anode plate 102, and a pair of horizontal support plates 108 for supporting the bottom sides of the overflow weirs 107. The overflow weirs 107 are slidably placed on the horizontal support plates 108. A guide plate 109 inclined downward along the direction close to the electrode plate is provided on the overflow port side of the overflow weirs 107. After the electrolyte entering the overflow weirs 107 overflows from the overflow port side, it flows downward along the guide plate 109 to the surface of the cathode plate 101 and the anode plate 102 to form a flowing liquid film. An adjusting bolt 110 is installed on the side wall of the tank away from the overflow port. The adjusting bolt 110 extends into the inner end of the tank 1 and abuts against the outer wall of the overflow weir 107. By adjusting the bolt 110, the overflow weir 107 slides horizontally on the horizontal support plate 108, thereby adjusting the distance between the overflow weir 107 and the electrode plate to adapt to different flow conditions. The electrolyte inlet 105 is located at the top of the tank above the overflow weir 107, and the vent 106 is located on the side wall of the tank below the horizontal support plate 108.

[0049] In this embodiment, the overflow outlet of the overflow weir 107 is serrated to prevent liquid from concentrating in a certain area and to ensure that the entire electrode surface can contact the liquid.

[0050] Example 6 refer to Figure 9This embodiment provides a falling film alkaline electrolyzer. Compared with Embodiment 1, the difference lies in that the falling film device includes horizontal partitions 111 disposed on both sides of the cathode plate 101 and the anode plate 102. The horizontal partitions 111 divide the tanks 1 on both sides of the electrode plates into upper and lower parts, with the upper part forming a high-level storage tank 112. A liquid distribution slit 113 is provided between the side of the horizontal partition 111 closest to the electrode plate and the electrode plate. After the liquid level in the high-level storage tank 112 rises to a certain height, the fluid pressure causes the electrolyte to flow through the liquid distribution slit 113 to form a falling film, flowing downwards through the liquid distribution slit 113 to the surface of the electrode plate to form a flowing liquid film. An electrolyte overflow port 114 is also provided on the top side wall of the high-level storage tank 112 to prevent the electrolyte level from becoming too high due to flow fluctuations, thus ensuring the safe operation of the system. The electrolyte inlet 105 is located at the top of the tank body 1, and the vent 106 is located on the side wall of the tank body below the horizontal partition 111.

[0051] During subsequent continuous operation and control, the liquid level in the storage tank and the width of the liquid distribution slit 113 can be adjusted to ensure the high efficiency and safety of the electrolysis process.

[0052] Example 7 refer to Figure 10 This embodiment provides a falling film PEM electrolyzer, which differs from Embodiment 6 in that: in this embodiment, the electrolyzer is a PEM electrolyzer, and the diaphragm is a PEM membrane. The liquid falling film device includes a horizontal partition 111 disposed on the side near the anode plate 102. The horizontal partition divides the tank 1 on the side near the anode plate 102 into upper and lower parts, with the upper part forming a high-level liquid storage tank 112. A liquid distribution slit 113 is provided between the side of the horizontal partition 111 near the anode plate 102 and the anode plate 102. After the liquid level in the high-level liquid storage tank 112 rises to a certain height, the fluid pressure causes the electrolyte to flow through the liquid distribution slit to form a falling film flow, flowing downward through the liquid distribution slit to the surface of the anode plate 102 to form a flowing liquid film. The electrolyte inlet 105 is opened at the top of the tank 1 on the side of the anode plate 102, and exhaust ports 106 are opened on the side walls of the tank on both sides of the electrode plate below the horizontal partition 111.

[0053] The performance of the falling film PEM electrolyzer described in Example 1 was tested using the electrolyzer experimental system described in Example 1. The electrolyte was high-purity deionized water. After fully wetting the anode plate, cathode plate, and proton exchange membrane, a direct current was applied between the cathode plate 101 and the anode plate 102 to start the electrolysis reaction.

[0054] In this embodiment, the electrolyte circulation flow rate entering the electrolytic cell through the electrolyte inlet is set to 400 mL / min, and the electrode area is approximately 10 cm². 2Constant voltages of 1.9V, 2.0V, 2.2V, 2.4V, 2.6V, and 2.8V were applied to the electrolytic cell, and electrolytic current data were collected to evaluate the working effect of the electrolytic cell. The results are shown in Tables 5 and 6.

[0055] Comparative Example 2 Compared to Example 7, the difference lies in the use of the traditional PEM electrolysis method with completely submerged electrodes. The anode side of the electrolytic cell is filled with electrolyte, and the electrodes are completely submerged in the electrolyte. The electrolyte inlet is located at the bottom of the electrolytic cell, and the electrolyte outlet is located at the top of the electrolytic cell. All other experimental conditions are the same. The results are shown in Tables 5 and 6.

[0056] Table 5 Total electrolysis current (in A) at different potentials Table 6 Electrolysis current density at different potentials (unit: A / m²) As can be seen from the results in Tables 5 and 6, the current value is significantly increased when using a falling film electrolyzer compared to a traditional submerged electrolyzer. Therefore, adopting a falling film feeding method can significantly improve the performance of a PEM electrolyzer.

[0057] Example 8 refer to Figure 11 This embodiment provides a falling film PEM electrolyzer. Compared with Embodiment 7, the difference is that the anode plate 102, cathode plate 101, and diaphragm device are tilted as a whole towards the cathode plate, with an tilt angle θ = 45~75°. This arrangement can further improve the uniformity of electrolyte distribution on the electrode surface.

[0058] This application provides a detailed description, the purpose of which is to enable those skilled in the art to understand and implement the content of this application, but it should not be used to limit the scope of protection of this application. All equivalent changes or modifications made in accordance with the spirit and essence of this application should be included within the scope of protection of this application.

Claims

1. A falling film electrolyzer for reducing energy consumption in a water-to-hydrogen electrolyzer, the electrolyzer comprising a tank body and one or more parallel electrolysis chambers disposed within the tank body, each electrolysis chamber comprising a pair of electrode plates and a diaphragm sandwiched between the pair of electrolysis plates, the electrolyzer being an alkaline electrolyzer or a PEM electrolyzer; characterized in that, The upper part of the tank is equipped with a liquid falling film device. Electrolyte entering the tank through the electrolyte inlet is coated with a downward-flowing liquid film on the surface of the electrode plate away from the diaphragm by the liquid falling film device. The liquid falling film device is selected from one or more of an overflow device, a high-level pressure distribution device, or a flushing device. The overflow device includes an overflow weir and a horizontal support plate for supporting the bottom of the overflow weir. The overflow weir is slidably placed on the horizontal support plate. A guide plate inclined downwards along the direction close to the electrode plate is provided on the overflow port side of the overflow weir. After the electrolyte entering the overflow weir overflows through the overflow port side, it flows downwards along the guide plate to the surface of the electrode plate, forming a downward-flowing liquid film. The high-level pressure distribution device includes a horizontal partition that divides the tank into upper and lower parts. The upper part forms a high-level liquid storage tank. A liquid distribution slit is provided between the side of the horizontal partition close to the electrode plate and the electrode plate. The electrolyte in the high-level liquid storage tank flows downwards through the liquid distribution slit to the surface of the electrode plate, forming a downward-flowing liquid film. The flushing device includes at least one nozzle. The inlet of the nozzle is connected to the electrolyte inlet. The outlet of the nozzle is directly opposite the top of the electrode plate and perpendicular to the surface of the electrode plate. The electrolyte sprayed through the nozzle flushes the electrode plate and forms a continuously downward-flowing liquid film on its surface. When the electrolytic cell is an alkaline electrolytic cell, the liquid falling film device is provided on the upper part of the tank body on both sides of the pair of electrode plates; when the electrolytic cell is a PEM electrolytic cell, the liquid falling film device is provided on the upper part of the tank body on the anode side.

2. The falling film electrolytic cell according to claim 1, characterized in that, When the liquid falling film device uses an overflow device, an adjusting bolt is installed on the outer wall of the tank body away from the overflow port. The adjusting bolt extends into the inner end of the tank body and abuts against the side wall of the overflow weir, which is used to adjust the horizontal distance between the overflow weir and the electrode plate.

3. The falling film electrolytic cell according to claim 1, characterized in that, The overflow outlet of the overflow weir is serrated.

4. The falling film electrolytic cell according to claim 1, characterized in that, When the liquid falling film device is selected as a high-pressure distribution device, the width of the liquid distribution slit is 2~5mm.

5. The falling film electrolytic cell according to claim 1, characterized in that, When the liquid falling film device is selected as a high-level pressure distribution device, an overflow port is also provided on the top side wall of the tank above the horizontal partition.

6. The falling film electrolytic cell according to claim 1, characterized in that, When the electrolytic cell is a PEM electrolytic cell, the angle θ between the electrode plate and the diaphragm and the horizontal direction is 45~90°.

7. The falling film electrolytic cell according to claim 6, characterized in that, When the electrolytic cell is a PEM electrolytic cell, the angle θ between the electrode plate and the diaphragm and the horizontal direction is 45~75°.

8. The falling film electrolyzer according to claim 1, characterized in that, The thickness of the liquid film on the surface of the electrode plate is 0.5~2.0 mm.

9. A water-to-hydrogen electrolysis system, characterized in that, The device includes a falling film electrolyzer, a gas-liquid separation device, and a circulating pump. The gas-liquid separation device has a gas phase outlet at the top and a liquid phase outlet at the bottom, and a gas-containing electrolyte inlet on the side wall. The gas-containing electrolyte inlet is connected to the electrolyte outlet of the tank body, and the liquid phase outlet is connected to the electrolyte inlet of the tank body. A circulating pump is provided on the connecting pipeline between the liquid phase outlet and the electrolyte inlet. The falling film electrolyzer is the falling film electrolyzer according to any one of claims 1 to 8.

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