Electrolytic cell air tightness monitoring structure

Abstract

The utility model discloses a kind of electrolytic cell air tightness monitoring structure, comprising: sealing unit, it includes the sealing cavity compatible with electrolytic cell outer shape, to form the opposite closed space between electrolytic cell outside and sealing cavity;Tracer medium filling unit, it is used to control to fill into tracer gas in closed space, and create tracer monitoring chamber of tracer gas atmosphere;Tracer monitoring unit, it includes the sensor module of real-time detection tracer gas parameter, sensor module detects tracer gas parameter;PLC interlock control unit, receive the detection data of tracer monitoring unit, according to preset alarm concentration threshold trigger alarm and interlock action.The utility model realizes electrolytic cell air tightness real-time accurate monitoring, combined with sealing cavity, helium tracer and PLC interlock control, overcome traditional manual sampling lag, low precision problem;Through hierarchical alarm and emergency response guarantee safety, adapt new equipment and online running scene, give consideration to detection efficiency and production continuity.

Description

Technical Field

[0001] This utility model relates to the field of electrolytic cell testing technology, specifically to an electrolytic cell airtightness monitoring structure. Background Technology

[0002] In industrial fields such as electrolytic hydrogen production and alkali production, the electrolyzer is a core production equipment, and the overall sealing of its structure, which consists of multiple electrolysis chambers sealed by stacked gaskets, is crucial. The sealing effect between the electrolysis chambers directly depends on the fit accuracy between the electrode plates and the gaskets. However, during long-term operation, factors such as temperature fluctuations, pressure changes, and mechanical vibrations can cause slight displacement of the electrode plates, leading to gasket seal failure and ultimately, leakage from the electrolyzer.

[0003] Existing detection technologies for this type of leak have significant shortcomings. Traditional manual detection methods rely on periodic inspections, judging the seal by observing for signs of alkaline leakage or applying soapy water, which is not only time-consuming and inefficient but also fails to detect minute leaks, often only becoming apparent after the leak has expanded, missing the opportunity for early intervention. Some online monitoring solutions using single sensors directly detect leaking media such as hydrogen or alkaline solutions, but due to the complex environment around the electrolyzer, which is susceptible to interference from humidity, temperature, and other gas components, the detection accuracy is low, leading to frequent false alarms and missed alarms.

[0004] Furthermore, existing technologies lack a systematic monitoring design for the overall sealing status of the electrolytic cell. Most solutions only detect localized areas, failing to comprehensively cover the sealing interfaces of all electrolysis chambers. This is particularly problematic for accurately detecting minute leaks caused by electrode displacement. These deficiencies prevent timely detection and handling of leaks, leading to anything from material waste and reduced production efficiency to serious safety accidents such as fires and explosions caused by leaks of flammable and explosive gases like hydrogen. Additionally, alkali leaks corrode equipment and pollute the environment, posing significant safety hazards and economic losses to industrial production.

[0005] For the reasons mentioned above, it is necessary to propose a monitoring structure for the airtightness of the electrolytic cell to solve the above problems. Utility Model Content

[0006] The purpose of this invention is to overcome the defects in the existing technology and provide an electrolytic cell airtightness monitoring structure.

[0007] To achieve the above objectives, the technical solution of this utility model is as follows: An electrolytic cell airtightness monitoring structure includes: The sealing unit includes a sealing cavity adapted to the shape of the electrolytic cell, which forms a wrapping cover over the outside of the electrolytic cell, creating a relatively closed space between the outside of the electrolytic cell and the sealing cavity. The tracer medium filling unit is used to control the filling of tracer gas into a closed space and to create a tracer monitoring chamber with a preset pressure and content of tracer gas in the closed space. The tracer monitoring unit includes a sensor module for real-time detection of tracer gas parameters, the sensor module detecting tracer gas parameters in an enclosed space and / or the external environment; The PLC interlocking control unit receives detection data from the tracer monitoring unit and triggers alarms and interlocking actions based on preset alarm concentration thresholds.

[0008] Furthermore, the sealing cavity is made of a high-temperature resistant and corrosion-resistant metal or composite material shell, or a corrosion-resistant and low-permeability flexible membrane.

[0009] Furthermore, forming the enclosed space also includes providing a sealing strip at the connection between the sealed cavity and the electrolytic cell, and a sealing gasket structure at the flange hole where the tension bolts of the electrolytic cell pass through.

[0010] Furthermore, the tracer medium filling unit includes a vacuum pump and a tracer medium injection device. The vacuum pump includes a vacuum pump, a vacuum gauge, and a vacuum pipeline. The tracer medium injection device includes a gas storage tank, a pressure reducing valve, a flow regulating valve, a solenoid valve, and a filling pipeline.

[0011] Furthermore, the tracer gas includes any one of helium, sulfur hexafluoride, krypton, and xenon.

[0012] Furthermore, the sensor module includes a helium concentration sensor and a pressure sensor; the tracer monitoring unit includes an environmental monitoring unit for tracking gas parameters in the monitoring environment located around the tension nut, and a leakage monitoring unit located inside the tracer monitoring chamber.

[0013] Furthermore, the sensor modules of the environmental monitoring unit are arranged around the flange and tension nut of the electrolytic cell; the sensor modules of the leakage monitoring unit are evenly distributed in an array within the tracer monitoring chamber.

[0014] Furthermore, the PLC interlocking control unit incorporates a gas flow simulation algorithm, which, based on the diffusion characteristics of helium within a sealed cavity, reverse-simulates the helium diffusion path to locate the leak point coordinates. The gas flow simulation algorithm includes the following steps: S11: Concentration gradient field calculation. The PLC interlocking control unit generates a continuous helium concentration gradient field in a three-dimensional network model based on the discrete concentration data of the sensor array, and identifies areas of abnormal concentration. S12: Reverse location of the leak point. Based on the distribution characteristics of the concentration gradient field and combined with the fluid momentum conservation equation, calculate the theoretical path and concentration decay law of helium diffusion from each potential leak point to the sensor, and match it with the actual detection data. If the theoretical diffusion model of a potential leak point has a good fit of ≥90% with the actual concentration change curve measured by the sensor, then the point is determined to be the actual leak point. S13: Diffusion trend simulation. After locating the leak point, the model simulates the diffusion range of helium in the next few minutes based on the change in concentration over time during the diffusion process. If the leakage is stable, the concentration distribution cloud map at different time points is predicted. If the leakage increases, the second derivative of the concentration change rate is used to determine the diffusion acceleration trend and output a risk warning in advance.

[0015] A method for using an electrolytic cell airtightness monitoring structure includes the following steps: S21: System preparation, cover and seal the electrolytic cell, evacuate the enclosed space, check unit connections, and initialize PLC parameters; S22: Helium filling, filling the enclosed space with helium, the PLC monitors the pressure and concentration, and stops after stabilization; S23: Real-time monitoring, the detection unit continuously collects concentration data, and the PLC analyzes the rate of change to determine leakage; S24: Interlock response, triggering first-level and second-level alarms according to the concentration threshold, and executing interlock shutdown when a second-level alarm occurs; S25: Leakage investigation and recovery, locate and repair the leak, refill with helium for verification, and restore operation.

[0016] Furthermore, step S21 also includes evacuating the inside of the electrolytic cell; Step S23 includes installing a helium mass spectrometer leak detector at the electrolytic cell outlet to monitor the amount of helium gas leaking into the electrolytic cell, wherein the leakage amount is less than 10. -6 If the air tightness of the electrolytic cell is determined to be qualified if the curve is stable for more than half an hour, the air tightness of the electrolytic cell is determined to be qualified.

[0017] The advantages and beneficial effects of this utility model are as follows: First, it has strong real-time performance: it continuously monitors the gas pressure of the electrolyzer and the concentration of surrounding gases, promptly detects gas tightness anomalies, continuously collects data with a high-frequency monitoring cycle, analyzes and processes data in real time, and immediately alarms and can link with the execution unit once an anomaly is detected, effectively shortening the response time, reducing safety hazards, and ensuring the stable operation of the stack and the entire fuel cell system.

[0018] Secondly, it boasts high accuracy: through sensors deployed at multiple locations, combined with precise data processing algorithms, it can accurately capture subtle changes in airtightness, significantly improving monitoring accuracy compared to traditional monitoring methods and enabling earlier detection of potential leak risks. Simultaneously, multi-sensor data fusion and location algorithms can precisely pinpoint leak locations, facilitating rapid repairs.

[0019] Third, remote monitoring: It supports remote viewing and alarm reception, which facilitates remote management by operation and maintenance personnel, helps enterprises achieve intelligent and unmanned workshop operation and maintenance mode, reduces labor costs, and improves production safety and stability.

[0020] Fourth, intelligent features: automatic hierarchical alarms and remote push notifications link on-site and remote management, improving emergency response speed; data storage and traceability functions provide data support for equipment maintenance and process optimization. This helps technicians deeply analyze the performance variation patterns of the fuel cell stack, providing strong evidence for fuel cell stack design improvements and operation and maintenance strategy optimization.

[0021] Fifth, versatility: It is compatible with different media electrolyzers (such as hydrogen production, chlor-alkali, etc.) and can be applied simply by replacing the corresponding gas sensor and adjusting the parameters, thus possessing wide applicability. It also facilitates the subsequent expansion of more functions, such as interfacing with intelligent diagnostic systems to achieve more advanced fault prediction and health management. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of an electrolytic cell airtightness monitoring structure according to the present invention; Figure 2 yes Figure 1 One of the enlarged views of the flange hole circled in the center; Figure 3 This is a schematic diagram showing the warping at the folded edge of the sealing gasket structure in this utility model; Figure 4 This is a cross-sectional schematic diagram of the mesh frame module along the weft frame direction in this utility model; In the diagram: 1. Electrolytic cell; 2. Sealed cavity; 3. Tracer monitoring chamber; 4. Filling pipeline; 5. Sensor module; 6. PLC interlocking control unit; 7. Alarm unit; 8. U-shaped convex ring; 9. Sealing gasket structure; 10. Sealing strip; 11. Tensioning bolt; 12. Flange hole; 13. End pressure plate; 14. Helium filling port; 15. Vacuum pump; 16. Vacuum gauge; 17. Vacuum pipeline; 18. Helium storage tank; 19. Pressure reducing valve; 20. Flow regulating valve; 21. Washer section; 22. Sleeve section; 23. Folded edge; 24. Sealing sleeve; 25. Sealing lip ring; 26. Limiting ring; 27. Hoop groove; 28. Hoop spring; 29. ​​Warp; 30. Flat washer; 31. Disc spring; 32. Sensor array; 33. Mesh frame module; 34. Axial frame; 35. Weft frame; 36. C-type spring clip. Detailed Implementation

[0023] The specific embodiments of this utility model will be further described below with reference to examples. These examples are only used to more clearly illustrate the technical solution of this utility model and should not be construed as limiting the scope of protection of this utility model.

[0024] An electrolytic cell airtightness monitoring structure. It mainly comprises the following components: Sealing Unit: A sealed cavity 2 designed to fit the shape of the electrolytic cell 1, possessing resistance to electrolyte corrosion and high temperature. It completely encloses the electrolytic cell 1 and related connecting pipelines, forming a closed space for monitoring.

[0025] Tracer medium filling unit: In this embodiment, helium is used as the tracer medium. Helium is the gas with the smallest molecular diameter in nature (atomic radius of about 0.31 Å), and has extremely strong diffusion ability. Even tiny leaks, such as micron-sized gaps caused by the displacement of the electrodes in the electrolysis chamber, can be quickly penetrated and diffused by helium. This strong diffusion property allows the leakage signal to be captured quickly, reducing detection lag. At the same time, the natural background concentration of helium in the air is extremely low, about 5.2 ppm, with minimal interference from the external environment. When high-purity helium is filled into the sealed cavity 2, if a leak occurs in the electrolysis cell 1, helium will enter the electrolysis chamber through the leak point, or the leaked medium will enter the tracer monitoring chamber 3, causing fluctuations in helium concentration. Small changes in concentration (at the ppm level) can be detected by the corresponding sensors in the sensor module 5, thus achieving high detection accuracy, reaching the ppm or even ppb level.

[0026] Specifically, the enclosed space is first brought to a vacuum state. Then, high-purity helium is supplied by helium storage tank 18, pressure is adjusted to an appropriate range by pressure reducing valve 19, and flow regulating valve 20 precisely controls the filling flow rate. Helium is then filled into the enclosed space between sealed cavity 2 and electrolytic cell 1 through filling pipeline 4.

[0027] The tracer monitoring unit includes a sensor module 5 for real-time detection of tracer gas parameters. Sensor module 5 includes a helium concentration sensor and a pressure sensor. The helium sensor is positioned within the enclosed space and around the electrolytic cell 1, enabling monitoring of both the interior and external environment of the tracer monitoring chamber 3, continuously collecting helium concentration data within the space. The pressure sensor is installed inside the tracer monitoring chamber 3 and at key locations in the connecting pipes to monitor the internal pressure in real time. It is understood that the internal monitoring targets the interior of the tracer monitoring chamber 3, detecting any external leaks in the electrolytic cell 1. The external environment monitoring targets weak points in the seal, such as the joint between the sealed cavity 2 and the electrolytic cell 1, and the flange hole 12, preventing leakage of helium from the tracer monitoring chamber 3 and affecting the monitoring structure.

[0028] PLC Interlock Control Unit 6: Employs an industrial-grade PLC to receive signals from helium concentration and pressure sensors. It has a built-in control logic program to analyze, calculate, and judge the data. Based on preset thresholds, when an abnormal helium concentration is detected, an interlock action is triggered. For example, the first-level alarm threshold for helium concentration is 500 ppm, the second-level alarm threshold is 300 ppm, and the pressure fluctuation range is ±5 kPa. These thresholds can be set according to actual conditions. The monitored data is compared with the preset thresholds to determine the leakage level and trigger appropriate actions such as alarm activation, suspension of electrolytic cell 1 operation, and closure of relevant valves.

[0029] Alarm Unit 7: Includes a local audible and visual alarm and a remote alarm module; the local audible and visual alarm is installed around the electrolytic cell 1, and uses yellow (level 1) and red (level 2) LED lights and buzzers of different frequencies to distinguish the alarm levels; the remote alarm module: communicates with the central control room monitoring system through industrial Ethernet and sends information including "alarm level, coordinates of the leakage area, and real-time concentration / pressure value".

[0030] Alarm unit 7 alarms in stages according to PLC instructions. Level 1 alarm indicates a minor leak and is indicated by a yellow audible and visual warning. Level 2 alarm indicates a serious leak and is indicated by a red audible and visual warning, along with a simultaneous remote alarm.

[0031] The sealing cavity 2 is made of a high-temperature resistant and corrosion-resistant metal or composite material shell, or a corrosion-resistant and low-permeability flexible membrane. Specifically, the metal material can be, for example, stainless steel, which has excellent high-temperature resistance and can withstand the high-temperature environment generated during the operation of the electrolytic cell 1, ensuring structural stability under high-temperature conditions and preventing deformation due to thermal expansion and contraction that could affect the sealing effect. The composite material can be made of fiber-reinforced resin-based composite material. Through reasonable fiber selection and resin formulation design, excellent high-temperature and corrosion resistance can be achieved. This composite material is often lightweight, easy to install and maintain, and highly designable, allowing for customized production according to the specific shape of the electrolytic cell 1, conforming to its outer contour and enhancing sealing reliability. For the corrosion-resistant and low-permeability flexible membrane, fluororubber membrane can be selected, which has good chemical stability and is resistant to various corrosive media such as acids, alkalis, and organic solvents. Its low permeability effectively prevents leakage of tracer gases such as helium. In some scenarios where installation space is limited and the shape of the electrolytic cell 1 is complex, the flexible film can be tightly attached to the surface of the electrolytic cell 1 by wrapping, pasting or other means to form an effective sealed space.

[0032] The specific operating steps are as follows: A flexible fluororubber film is placed over the electrolytic cell, and the edges where the electrolytic cell contacts the flexible film are sealed. Sealing strips are used at the seal, and the flexible film is tightly bound around the outer ring to form a well-sealed cavity. High-purity helium is then introduced into the sealed cavity through vacuuming or displacement. The electrolytic cell is then evacuated, and a helium mass spectrometer leak detector is placed at the outlet of the electrolytic cell to detect the helium gas. In actual operation, helium is introduced until the helium concentration at the bottom of the film cover (sealed cavity) reaches 10%, and a pressure difference has been established inside the electrolytic cell through vacuuming. The helium leakage at the outlet of the electrolytic cell is detected using a helium mass spectrometer leak detector, and the leakage is 10%. -6 If the gas flow rate is within pa.m3 / s and the curve remains stable for more than half an hour, the electrolytic cell is considered to be of qualified air tightness. Helium has low background noise, small molecular weight and viscosity coefficient, and can easily pass through leaks and diffuse. Therefore, choosing helium testing as the method to evaluate the air tightness of the electrolytic cell is the highest standard and the most reliable.

[0033] Regarding the material selection for the sealing cavity 2, the flexible film is relatively simple and quick to lay, but it is not suitable for long-term monitoring. Furthermore, the flexible film is easily deformable, so it is not suitable to establish a high helium pressure inside the sealing cavity 2 formed by the flexible film. Its advantages are low cost and quick laying, making it more suitable for temporary leak monitoring of the electrolytic cell 1, and especially suitable for leak monitoring of the electrolytic cell 1 that is offline or newly assembled. This is because the electrolytic cell 1 that is offline for maintenance or the new electrolytic cell 1 is usually under normal pressure when tested, so the sealing cavity 2 of the flexible film does not need to create a high helium pressure for monitoring. Helium leaks from the leak point into the electrolytic cell 1 and is monitored by the helium concentration sensor installed on the outlet pipe of the electrolytic cell 1.

[0034] The metal or composite material sealing cavity 2, due to the robustness of its materials, is more suitable for long-term monitoring and facilitates the creation of high helium pressure within the tracer monitoring chamber 3; it is suitable for monitoring the electrolytic cell 1 during online operation. However, a key issue is that when the electrolytic cell 1 is powered by a green electricity system, its operation must adapt to fluctuations in green electricity supply, resulting in frequent adjustments to its operating load. Thermal expansion and contraction cause the electrolytic cell 1 to expand and contract. Since the metal or composite material is a fixed structure, the sealing joint between the sealing cavity 2 and the electrolytic cell 1 experiences significant stress during these expansions and contractions, potentially leading to leakage. Therefore, in this embodiment, the metal or composite material sealing cavity 2 incorporates an expansion compensation structure to accommodate the expansion and contraction of the electrolytic cell 1. Figure 1As shown, the expansion and contraction compensation structure includes multiple U-shaped protruding rings 8 formed on the sealing cavity 2. It can be understood that when the electrolytic cell 1 expands and contracts, the U-shaped protruding rings 8 deform first. Through the elongation or contraction of the two side walls of the U-shaped protruding rings 8 in conjunction with the expansion and contraction of the electrolytic cell 1, the deformation stress of the sealing part connecting the sealing cavity 2 and the electrolytic cell 1 is reduced, thereby avoiding leakage of the sealing cavity 2.

[0035] Preferably, the edge of the sealed cavity 2 is sealed to the base or support of the electrolytic cell 1 by a sealing strip 10. When forming a closed space, a sealing strip 10 is provided at the connection between the edge of the sealed cavity 2 and the electrolytic cell 1, and a sealing gasket structure 9 is provided at the point where the tension bolt 11 of the electrolytic cell 1 passes through the flange hole 12.

[0036] Furthermore, the tracer medium filling unit also includes a helium filling port 14, a helium detection port, and a pressure balancing port for filling the enclosed space with tracer gas. The gap between the helium filling port and the outer surface of the electrolytic cell 1 constitutes a helium monitoring chamber. The pressure balancing port is used to balance the internal and external pressures to avoid affecting the normal operation of the electrolytic cell 1. The helium filling port 14 is connected to a nitrogen storage tank through a filling pipe to fill the helium monitoring chamber with helium.

[0037] Furthermore, the tracer medium filling unit also includes equipment for evacuating the tracer detection chamber. The vacuum state within the tracer detection chamber is achieved by a vacuum pump 15, a vacuum gauge 16, and a vacuum pipeline 17. First, the vacuum pump 15 evacuates the air from the enclosed space, and the reading on the vacuum gauge 16 is observed. When the vacuum gauge 16 indicates that the enclosed space has reached a predetermined vacuum level, the evacuation stops. This is to ensure that the air in the enclosed space is evacuated as much as possible, creating conditions for subsequent nitrogen filling. The nitrogen filling consists of a helium storage tank 18, a pressure reducing valve 19, a flow regulating valve 20, and a solenoid valve.

[0038] The helium storage tank 18 stores high-purity helium. The pressure is adjusted to a suitable range by the pressure reducing valve 19, the flow regulating valve 20 controls the filling flow, and the solenoid valve, as the on / off actuator, receives the PLC control signal to realize the precise filling and shut-off of helium into the sealed cavity 2.

[0039] As needed, the filling pipeline 4 connected to the helium storage tank 18 is connected to the helium detection chamber from the helium filling port 14 reserved in the enclosed space.

[0040] Electrolytic cell 1 is equipped with tension bolts 11, which are core connecting components for fastening the structure of electrolytic cell 1. These bolts counteract the expansion force generated by heating during electrolysis, ensuring the stability of core components such as electrodes and diaphragms, and maintaining the sealing performance and operational safety of electrolytic cell 1. When forming the tracer monitoring chamber 3, the tension bolts 11 pass through the flange hole 12 of the end pressure plate 13 of electrolytic cell 1, creating a relatively weak sealing point. Figure 2, 3 As shown, in this embodiment, a targeted sealing reinforcement is achieved at this location using a sealing gasket structure 9. Specifically, the sealing gasket structure 9 has an annular structure, including a gasket portion 21 and a sleeve portion 22. The sleeve portion 22 is perpendicular to the gasket portion 21, and the gasket portion 21 is coaxially connected to the end of the sleeve portion 22. The gasket portion 21 is fitted to the outside of the flange hole 12 of the end plate. The sleeve portion 22 passes through the flange hole 12 and is sleeved onto the tension bolt 11. The gasket portion 21 is a metal-graphite or metal-PTFE spiral wound gasket structure. The sleeve portion 22 is connected to the inner ring of the gasket portion 21. It can be made of a flexible material, such as rubber. The sleeve portion 22 has a folded edge 23 and a sealing sleeve 24. The outer ring of the folded edge 23 is sealed to the inner ring of the gasket portion 21. The folded edge 23 has a certain width in the radial direction to compensate for the gap between the tension bolt 11 and the flange hole 12. The inner ring of the folded edge 23 is connected to the sealing sleeve 24. The sealing sleeve 24 passes through the flange hole 12 axially. The end of the sealing sleeve 24 that passes through the flange hole 12 forms a sealing lip 25. The outer wall of the sealing lip 25 is provided with a limiting retaining ring 26 and a hoop groove 27. A hoop is provided in the hoop groove 27. A clamping spring 28 is provided, which is positioned between the limiting retaining ring 26 and the washer portion 21. The clamping spring 28 has at least one turn. During actual installation, when the end plate is inserted into the tensioning bolt 11, the clamping spring 28 is first pre-fitted onto the tensioning bolt 11. Then, the end of the tensioning bolt 11 passes through the flange hole 12, and the sealing gasket structure 9 is inserted from the outside of the flange hole 12, so that the sealing sleeve 24 is fitted onto the tensioning bolt 11 and the washer portion 21 is pressed against the outer wall of the flange hole 12. Then, the flat washer 30, the disc spring 31, and the nut are installed and tightened in sequence. When the nut is tightened, the disc spring... 31. The flat washer 30 compresses the washer portion 21 to compress the spiral wound gasket structure to form a seal, while the tension bolt 11 and the flange hole 12 are sealed by the sleeve portion 22. The sleeve portion 22 is made of a flexible material and its end protrudes from the end plate. It can be understood that after the nut is tightened, the sleeve portion 22 is exposed from the inside of the end plate. Then, the clamping spring 28 is sequentially inserted into the clamping ring groove 27. The clamping spring 28 tightly clamps the sleeve portion 22 onto the tension bolt 11, thereby sealing the gap between the tension bolt 11 and the flange hole 12, thus achieving a good seal in the enclosed space.

[0041] Furthermore, to achieve a better sealing effect, the inner diameter of the folded edge 23 should be set slightly smaller than the diameter of the tension bolt 11. When the sealing gasket structure 9 is installed in the flange hole 12, the smaller inner diameter of the folded edge 23 causes it to warp outwards 29. When the flat gasket 30 presses against it, the warped portion 29 is flattened inwards, thus applying a clamping force oriented towards the axis to the tension bolt 11. It can be understood that this structure forms multiple seals along the tension bolt 11, successively consisting of the seal of the multi-turn clamping spring 28 and the clamping seal formed by the flattening of the folded edge 23 after warping 29. During installation, the sealing gasket structure 9 is installed at both ends of each tension bolt 11 in the electrolytic cell 1, ensuring good sealing of the enclosed space. Furthermore, the sensor module 5 for monitoring the external environment, installed on the outside of the end pressure plate 13 flange, allows for real-time monitoring of the flange hole 12, a weak point in the seal, ensuring that the sealed space reaches the preset sealing level.

[0042] Furthermore, the tracer detection unit specifically uses helium as the tracer gas and is equipped with a helium sensor and a pressure sensor. The pressure sensor, installed within the enclosed space and at key locations on the connecting pipes, monitors the internal gas pressure of the enclosed space. The helium concentration sensor, arranged around the tension nut of the electrolytic cell 1 and within the enclosed space, collects helium concentration data in real time.

[0043] The pressure sensor and helium concentration sensor mentioned above transmit real-time detection data to the PLC control system. Preferably, the helium concentration sensors are arranged at equal intervals (not exceeding 5cm) along the flange sealing surface and tension nut of electrolytic cell 1.

[0044] The advantage of using an array of helium concentration sensors evenly distributed in a closed space is that it comprehensively covers the entire helium detection chamber, allows for real-time monitoring of helium concentration at each point, quickly detects changes in helium concentration, and accurately locates leak points. For example... Figure 1 , 4As shown, the sensor array 32 formed by the uniform distribution of the helium concentration sensors described above can be based on a mesh frame module 33. The mesh frame module 33 is disposed between two adjacent tension bolts 11. The mesh frame includes multiple axial frames 34 arranged parallel to the axial direction of the electrolytic cell 1, and multiple rows of latitudinal frames 35 arranged latitudinally along the latitudinal direction of the electrolytic cell 1. The latitudinal frames 35 and axial frames 34 are spaced at a preset interval and sensor modules 5 are placed at their intersections to form the sensor array 32. Furthermore, the mesh frame module 33 and the sensor module 5 installed at the intersections can be disposed between each adjacent tension bolt 11, thereby enabling the sensor array 32 to be arranged in the sealed cavity 2. The mesh frame module 33 can be fixed by C-shaped spring clips 36 provided at both ends of the latitudinal frames 35 that cooperate with the tension bolts 11, allowing for convenient installation and disassembly, and facilitating precise adjustment of the position of the mesh frame module 33.

[0045] During setup, the sensor probe should be positioned directly over the sealing gap and connected to the PLC interlocking control unit 6 via a high-temperature resistant cable. The arrangement and quantity of the pressure sensor and helium concentration sensor can be adjusted according to the actual structure and dimensions of the electrolytic cell 1 to achieve comprehensive and effective monitoring.

[0046] Preferably, the helium concentration sensor is a high-sensitivity, high-resolution semiconductor or mass spectrometry sensor to ensure the detection of concentration changes caused by minute leaks. A pressure sensor with appropriate accuracy and range is selected to assist in determining the filling status and whether abnormal pressure fluctuations are caused by leaks, working in conjunction with the helium concentration sensor to improve the accuracy of leak detection.

[0047] Preferably, the PLC interlocking control unit 6 serves as the core of the system, receiving signals from the helium concentration sensor and pressure sensor, and has a built-in control logic program to analyze, calculate, and judge the data.

[0048] The PLC control system outputs interlocking control commands based on preset thresholds (such as helium concentration alarm thresholds and pressure fluctuation ranges), such as triggering the closure of the helium charging solenoid valve, activating the leak emergency handling device, and sending alarm signals to the central control system. Furthermore, in addition to the helium charging solenoid valve, the PLC interlocking control unit 6 can be expanded to connect to the power system interlocking device of the electrolytic cell 1, ventilation equipment, etc. When the PLC determines an airtightness abnormality, it quickly executes the interlocking action to ensure equipment and personnel safety.

[0049] In this embodiment, specifically, the helium detection unit collects data from the electrolyzer 1 in real time. When a leak occurs in the electrolyzer 1, for example, if the initial helium concentration in the sealed cavity 2 is 1000 ppm and the pressure is 5 kPa, after 30 minutes of operation, the sensor at the flange detects that the concentration has dropped to 480 ppm (a decrease of 20 ppm within 1 minute), and the pressure has risen to 7 kPa. The data is transmitted to the PLC in real time. The PLC performs a logical judgment, comparing the concentration of 480 ppm with the preset first-level alarm threshold of 500 ppm (480 < 500). The pressure fluctuation is 2 kPa (not exceeding the ±5 kPa threshold), which is determined to be a "first-level leakage risk". The PLC then performs corresponding interlocking actions, such as: sending a first-level alarm command to the alarm unit 7; activating the helium replenishment valve to maintain a stable concentration in the cavity and avoid false alarms; and sending a "load reduction reminder signal" to the electrolyzer 1 control system, suggesting that the operator pay attention. Furthermore, if the concentration continues to drop to 280ppm (below the secondary threshold of 300ppm) after 10 minutes, and the pressure rises to 12kPa (exceeding the threshold), the PLC will determine that there is a "secondary leakage risk" and trigger the following actions: send a secondary alarm command to alarm unit 7; forcibly close the feed valve of electrolytic cell 1 and suspend the operation of electrolytic cell 1; activate the emergency isolation device to prevent the leakage from spreading; and both the primary and secondary alarms will simultaneously trigger the on-site audible and visual alarms.

[0050] Furthermore, the PLC interlocking control unit 6 can, based on data analysis and processing, predict the leakage trend after determining a leak, combining historical data, the operating time of the electrolytic cell 1, and other information, providing more references for operation and maintenance decisions. Specifically, the PLC interlocking control unit 6 incorporates a gas flow simulation algorithm, which, based on the diffusion law of helium in the sealed cavity 2, reversely simulates the helium diffusion path to locate the coordinates of the leak point; Specifically, by establishing a mathematical model of helium flow and diffusion inside the sealed cavity 2, and using real-time data from the helium concentration sensor array 32, the location coordinates of the leak point are calculated in reverse (accuracy ≤ 5mm), and the diffusion path and concentration change trend of helium in the cavity after the leak occurs are simulated, providing accurate positioning basis for the PLC interlocking control unit 6.

[0051] A geometric model is established based on the actual dimensions and internal structure of the sealed cavity 2 and the spatial coordinates of the sensor array 32. A simplified three-dimensional mesh model (mesh accuracy 1mm×1mm×1mm) is constructed in the PLC system to clarify the cavity boundary conditions, such as the position of the sealing strip 10 and the coordinates of the filling port / detection port. In this embodiment, the 1mm mesh accuracy does not mean that a helium concentration sensor is set every 1mm. The following relationship exists between the two, and the 1mm accuracy is achieved through corresponding methods: A 1mm precision grid is used to digitally divide the space of the sealed cavity 2 and the internal electrolytic cell 1, facilitating calculation and analysis by the gas flow simulation algorithm; it serves as a virtual computational model. The uniformly distributed array of sensor modules 5 is the actual hardware used to collect physical data (helium concentration, pressure, etc.). The data collected by the sensors forms the basis for the algorithm's calculations on the grid model. By analyzing, processing, and interpolating the data from a finite number of sensors, the helium concentration distribution within the entire grid space is inferred, thereby achieving precise location of the leak point and simulation of its diffusion trend.

[0052] The interpolation calculation based on sensor data is performed within a constructed 3D mesh model, using an interpolation algorithm to achieve a simulation accuracy of 1mm. Kriging interpolation is employed, utilizing helium concentration data collected by sensors at known locations to perform interpolation calculations between mesh nodes, thereby obtaining a continuous concentration distribution across the entire mesh. This allows for the calculation of high-precision concentration change information on a virtual mesh even with a limited number of actual sensors.

[0053] Furthermore, by incorporating a gas diffusion model, the physical laws and mathematical models of gas diffusion are used to analyze the data collected by the sensors. When a leak occurs, based on the concentration changes detected by sensors at different locations, and combined with the diffusion model, the concentration at different locations around the leak point is inferred. This allows for a more accurate determination of the leak point location and diffusion trend on a grid model, helping to achieve the positioning requirement with 1mm accuracy.

[0054] Specifically, the gas flow simulation algorithm includes the following steps: S11: Concentration gradient field calculation. The PLC interlock control unit 6 uses the Kriging interpolation method to generate a continuous helium concentration gradient field in the three-dimensional mesh model based on the discrete concentration data of the sensor array 32, and identifies areas with abnormal concentration. If the concentration in a certain area is significantly lower than that of the surrounding area, it indicates that there may be a leak point - helium diffuses to the leak point, causing a local decrease in concentration. S12: Reverse location of the leak point. Based on the distribution characteristics of the concentration gradient field and combined with the fluid momentum conservation equation, calculate the theoretical path and concentration decay law of helium diffusion from each potential leak point to the sensor, and match it with the actual detection data. If the theoretical diffusion model of a potential leak point has a good fit of ≥90% with the actual concentration change curve measured by the sensor, then the point is determined to be the actual leak point. S13: Diffusion trend simulation. After locating the leak point, based on Fick's second law (which describes the change of concentration over time during diffusion), the diffusion range of helium in the model is simulated within the next 5-10 minutes. If the leakage is stable, the concentration distribution cloud map at different time points is predicted. If the leakage increases, the diffusion acceleration trend is judged by the second derivative of the concentration change rate, and a risk warning is output in advance.

[0055] According to a specific embodiment of the above steps: the scenario is that during the operation of electrolytic cell 1, a small electrolytic chamber has a 0.1mm gap (minor leakage) due to slight displacement of the electrode plate. The sealed cavity 2 has been filled with helium and is in the pressure stabilization monitoring stage. The helium concentration sensor array 32 (distributed at 5cm intervals) collects data in real time.

[0056] Step 1, Calculation of concentration gradient field Input data: In sensor array 32, for example, number S 12 The helium concentration located directly above the flange sealing surface of the electrolysis chamber is 850 ppm (initial stable concentration is 1000 ppm), and the adjacent sensor S 11 S 13 The concentrations were 980ppm and 970ppm, while the sensor concentrations in other areas were 990-1000ppm; the pressure in the sealed chamber 2 was stable at 5kPa, the ambient temperature was 25℃, and the helium diffusion coefficient was 0.63cm² / s.

[0057] Calculation process: The discrete data is processed into a three-dimensional grid using the Kriging interpolation method to generate the concentration gradient field — S 12 A "concentration depression" formed around it, with the concentration increasing from 850 ppm to the periphery at a rate of 15-20 ppm per centimeter. The clearly defined abnormal area is a circular region with a diameter of about 10 cm.

[0058] Step 2: Reverse location of the leak point Model assumptions: The leak point is assumed to be a "point source". Helium diffuses from this point into the electrolysis chamber. Since the chamber is a relatively low-pressure hydrogen environment, it conforms to the "point source diffusion decay law" (the concentration increases exponentially with distance).

[0059] Matching calculation: Substitute the fluid momentum conservation equation to calculate different potential points (S 12 Theoretical concentration distribution within a 5cm radius: When the potential point is located at S 12 3cm directly below (corresponding to the joint between the flange sealing surface of the electrolysis chamber and the tension nut), the theoretically calculated S 12 The concentration was 845 ppm, which had a good fit of 99.4% with the measured value of 850 ppm, far exceeding the 90% threshold. The point was determined to be the leak point, and the coordinates could be located based on the three-dimensional grid (e.g., X=125mm, Y=380mm, Z=50mm).

[0060] Step 3: Diffusion Trend Simulation Model input: The concentration change rate at the leak point is -2ppm / min (slowly decreasing), which is judged as a stable small leak.

[0061] Simulation results: Based on Fick's second law, the diffusion trend over the next 10 minutes was simulated: after 5 minutes, the "concentration depression" expanded to a diameter of 15 cm, S 11 S 13 The concentration dropped to 950 ppm and 940 ppm; after 10 minutes, the diffusion range stabilized and did not affect adjacent electrolysis chambers, and the risk level was "low".

[0062] A method for using an airtightness monitoring system for an electrolytic cell 1 includes the following steps: (1) System preparation: Completely cover the electrolytic cell 1 with the sealed cavity 2 that is adapted to the shape of the electrolytic cell 1 to ensure good sealing. Check that the vacuum unit, helium filling unit, detection unit and PLC interlock control unit 6 are connected normally. Initialize the PLC parameters and set the normal threshold for helium concentration and the leakage alarm threshold.

[0063] (2) Gas treatment: First, the closed space is brought to a vacuum state. Helium is then introduced into the closed monitoring space through the helium storage tank 18. During the filling process, the PLC monitors the filling pressure and flow rate in real time. When the pressure in the closed monitoring space reaches the required value and the helium concentration tends to stabilize, the filling is stopped and the pressure stabilization monitoring stage begins.

[0064] (3) Real-time monitoring: The helium detection unit continuously collects helium concentration data and pressure values ​​in the enclosed space and environment, and transmits them to the PLC every 5 seconds. The PLC filters and analyzes the data and calculates the helium concentration change rate. If the concentration change rate exceeds the set value, it is determined that there may be a leak.

[0065] (4) Interlock response: When the helium concentration reaches the first-level alarm threshold, the PLC triggers a yellow audible and visual alarm on site and records the alarm time and concentration data at the same time; if the second-level alarm threshold is reached, the PLC immediately triggers a red audible and visual alarm and a remote alarm, and automatically executes interlock actions, such as cutting off the power supply to electrolytic cell 1 and closing the electrolyte inlet and outlet valves to prevent the leakage from expanding.

[0066] (5) Leakage investigation and recovery: After the alarm, the maintenance personnel locate the leak point based on the concentration distribution data recorded by the PLC and the sensor location. After repair, the system preparation and helium charging process is re-executed. After confirming that the helium concentration is stable and there are no abnormal changes, the interlock is released and the operation of electrolytic cell 1 is restored.

[0067] As one embodiment, the above steps are applied to the leak detection of the new electrolytic cell 1 equipment (in an unused state, with the interior being a low-pressure hydrogen side). If the interior of the electrolytic cell is low-pressure (such as the hydrogen side), helium will diffuse towards the leak point, causing a decrease in the local helium concentration in the cavity.

[0068] S21: System preparation. The new electrolytic cell 1 is not yet in use. Its interior is evacuated or under low pressure, and its exterior is enclosed by the sealed cavity 2 of the sealing unit, forming a closed helium monitoring chamber. At this time, a pressure difference of "high outside and low inside" is formed between the sealed cavity 2 and the interior of the electrolytic cell—the chamber will be filled with high-purity helium through the gas unit, while the interior of the electrolytic cell will maintain a low pressure, providing driving force for helium diffusion. It is understandable that since the electrolytic cell 1 is a new device or a device that has been disassembled and is under maintenance, it is in an offline state. Therefore, a relatively simple and low-cost flexible thin film material can be used as the sealed cavity 2. Specifically, a fluororubber film can be used to completely cover the exterior of the electrolytic cell 1, forming a relatively closed space, with the edges sealed by the sealing strip 10. The tracer medium filling unit replaces the gas inside the tracer monitoring chamber 3 and creates a helium atmosphere with a preset pressure and content.

[0069] S22: Helium filling. The gas unit first extracts air from the monitoring chamber using vacuum pump 15. After reaching the predetermined vacuum level, the vacuuming stops, and high-purity helium is then injected into the chamber through filling pipeline 4 until the helium concentration and pressure in the chamber stabilize (PLC monitors and controls the filling process in real time). At this time, the helium pressure in the sealed chamber 2 is higher than the low pressure inside the electrolysis chamber, satisfying the physical condition of "gas diffusion from high-pressure area to low-pressure area"—if there is a leak in the electrolysis chamber, such as a gap caused by electrode plate installation deviation or a gap formed by gasket not being pressed tightly, the helium in the chamber will diffuse into the chamber along the leak.

[0070] S23: Real-time monitoring. If sensor modules 5 are evenly distributed in an array, helium at the leak point will continuously flow into the small chamber (low-pressure area), causing insufficient helium replenishment in the surrounding chamber area and forming a local concentration drop zone—for example, the helium concentration within 1-5 cm of the leak point will be lower than the average concentration of the chamber, and the closer to the leak point, the more significant the concentration drop. If helium concentration sensors and pressure sensors are installed at the hydrogen and oxygen outlets of electrolyzer 1 for detection, the presence of a leak in electrolyzer 1 can be directly determined by the monitoring values ​​of the helium concentration sensors and the increase in internal pressure of electrolyzer 1.

[0071] S24: Interlock Response. After receiving sensor data, the PLC interlock control unit 6 analyzes the magnitude, rate of change, and spatial distribution of the local concentration decrease (combined with the location information of the array sensors) to determine that a leak exists. Subsequently, the PLC triggers the alarm unit 7 (such as a first-level audible and visual alarm) to prompt the operator to check for the leak.

[0072] As another embodiment, the above steps are applied to the detection method of online operating electrolytic cell 1, as follows: S21: System preparation. The electrolytic cell 1, which is operating online, is filled with alkaline solution, hydrogen, and other media to maintain normal operating pressure. It is externally enclosed by a sealed cavity 2, forming a closed space. The edges are sealed with sealing strips 10, creating a closed helium monitoring chamber. A pressure balancing port is provided in the chamber to ensure that the internal pressure is slightly lower than that of the electrolytic cell 1 (to avoid affecting production). The chamber has been filled with high-purity helium through the gas unit and is in a stable pressure monitoring state.

[0073] It is understandable that this embodiment is for long-term online leakage monitoring of the electrolytic cell 1, so the sealed cavity 2 should preferably be made of metal or composite materials to provide sufficient material strength and service life. Furthermore, in the helium detection unit, array-type helium concentration sensors are evenly distributed within the tracer monitoring chamber 3; and for weak points in the seal, external environmental monitoring is also implemented, with sensors densely arranged (spaced ≤ 5cm) along the flange sealing surface, tension nuts, and other leak-prone areas. Pressure sensors are installed at key locations within the cavity to collect data in real time and transmit it to the PLC interlocking control unit 6.

[0074] S22: Helium filling, similar to the aforementioned embodiments.

[0075] S23: Real-time monitoring. When a leak occurs in electrolytic cell 1 due to electrode displacement, gasket aging, etc., the leaking medium overflows. The high-pressure medium inside electrolytic cell 1 diffuses into the chamber through the leak. Because the chamber pressure is lower than the internal pressure of electrolytic cell 1, a pressure difference of "high inside, low outside" is formed, driving the medium to actively overflow. Change in chamber state: After the overflowing medium enters the chamber, it will compress the space originally occupied by helium, causing the internal pressure of the chamber to rise. The pressure sensor captures this change in real time. Furthermore, the helium concentration is diluted. The leaking medium mixes with the helium in the chamber, reducing the helium content per unit volume. This is manifested as an overall decrease in helium concentration, resulting in a decrease in the value detected by the concentration sensor, with a more significant decrease in concentration near the leak.

[0076] S24: Interlock response. The PLC receives the "pressure rise value" from the pressure sensor and the "concentration change rate" data from the concentration sensor, and compares them with preset thresholds (such as the allowable range of pressure fluctuation ±5kPa and the concentration decrease rate threshold of 0.5ppm / s).

[0077] If the pressure rises above the threshold and the rate of decrease in helium concentration continues to exceed the set value (e.g., the concentration drops from 1000ppm to 900ppm within 1 minute, with a decrease rate of 1.67ppm / s > 0.5ppm / s), the PLC determines that "a leak exists." Combining this with the spatial distribution data of the array sensors, such as the area where the sensor concentration decreases most rapidly and the pressure rises most significantly, the approximate location of the leak can be further pinpointed.

[0078] This embodiment utilizes the pressure difference between the "high internal pressure and low chamber pressure" of the online electrolytic cell 1 to make the leaking medium a passive tracer source: the pressure rise and helium concentration drop signals caused by the overflow of the medium are captured by the sensor, and after analysis by the PLC, the leak can be accurately judged and responded to, which can effectively ensure the safety and continuity of the electrolytic cell 1 during operation.

[0079] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A structure for monitoring the airtightness of an electrolytic cell, characterized in that, include: The sealing unit includes a sealing cavity adapted to the shape of the electrolytic cell, which forms a wrapping cover over the outside of the electrolytic cell, creating a relatively closed space between the outside of the electrolytic cell and the sealing cavity. The tracer medium filling unit is used to control the filling of tracer gas into a closed space and to create a tracer monitoring chamber with a preset pressure and content of tracer gas in the closed space. A sealing gasket structure is provided at the flange hole where the tension bolt of the electrolytic cell passes. The sealing gasket structure is a ring structure, including a gasket part and a sleeve part. The sleeve part is perpendicular to the gasket part. The gasket part is coaxially connected to the end of the sleeve part. The gasket part is fitted to the outside of the flange hole of the end plate. The sleeve part passes through the flange hole and is sleeved on the tension bolt for sealing. The tracer monitoring unit includes a sensor module for real-time detection of tracer gas parameters, which detects tracer gas parameters in an enclosed space and / or the external environment.

2. The electrolytic cell airtightness monitoring structure according to claim 1, characterized in that, The sealing cavity is made of high-temperature resistant and corrosion-resistant metal or composite material shell or corrosion-resistant and low-permeability flexible membrane.

3. The electrolytic cell airtightness monitoring structure according to claim 1, characterized in that, Forming the enclosed space also includes providing a sealing strip at the connection between the sealed cavity and the electrolytic cell; The sleeve portion has a folded edge and a sealing sleeve. The outer ring of the folded edge is sealed to the inner ring of the gasket portion. The folded edge has a certain width in the radial direction to compensate for the gap between the tension bolt and the flange hole. The inner ring of the folded edge is connected to the sealing sleeve. The sealing sleeve passes through the flange hole axially. The end of the sealing sleeve that protrudes from the flange hole forms a sealing lip. The outer wall of the sealing lip is provided with a limiting retaining ring and a hoop groove. A hoop spring is provided in the hoop groove.

4. The electrolytic cell airtightness monitoring structure according to claim 1, characterized in that, The tracer medium filling unit includes a vacuum pump and a tracer medium injection device. The vacuum pump includes a vacuum pump, a vacuum gauge, and a vacuum pipeline. The tracer medium injection device includes a gas storage tank, a pressure reducing valve, a flow regulating valve, a solenoid valve, and a filling pipeline.

5. The electrolytic cell airtightness monitoring structure according to claim 1, characterized in that, The tracer gas includes any one of helium, sulfur hexafluoride, krypton, and xenon.

6. The electrolytic cell airtightness monitoring structure according to claim 1, characterized in that, The sensor module includes a helium concentration sensor and a pressure sensor; the tracer monitoring unit includes an environmental monitoring section for tracer gas parameters located around the tension nut, and a leakage monitoring section located inside the tracer monitoring chamber.

7. The electrolytic cell airtightness monitoring structure according to claim 6, characterized in that, The sensor modules of the environmental monitoring unit are arranged around the flange and tension nut of the electrolytic cell; the sensor modules of the leakage monitoring unit are evenly distributed in an array within the tracer monitoring chamber.

8. The electrolytic cell airtightness monitoring structure according to claim 3, characterized in that, The inner diameter of the folded edge is slightly smaller than the diameter of the tension bolt. When the sealing gasket structure is installed in the flange hole, the folded edge forms a warp pointing outwards.

9. The electrolytic cell airtightness monitoring structure according to claim 1, characterized in that, A telescopic compensation structure is provided on the sealed cavity, and the telescopic compensation structure includes multiple U-shaped protruding rings formed on the sealed cavity.

10. The electrolytic cell airtightness monitoring structure according to claim 7, characterized in that, The array is uniformly distributed based on a mesh frame module, which is set between two adjacent tension bolts. The mesh frame includes multiple axial frames arranged parallel to the axial direction of the electrolytic cell and multiple columns of latitudinal frames arranged in the latitudinal direction of the electrolytic cell. The latitudinal frames and axial frames are arranged at preset intervals and sensor modules are set at the intersections to form a sensor array.

Images