Electrolytic cell on-line diagnosis system and method based on cathode water quality characteristics

Abstract

The present application relates to the technical field of water electrolysis hydrogen production, and specifically discloses an electrolytic tank online diagnosis system and method based on cathode water quality characteristics, which continuously monitors the water quality characteristic parameters of the water outlet of the cathode of the electrolytic tank, compares and analyzes the water quality characteristic parameters with the safety upper limit value or the reference threshold value of the water quality characteristic parameters, and determines whether the electrolytic tank is contaminated by ions; the water quality characteristic parameters include conductivity, pH value and water temperature value. The present application effectively replaces the traditional electrical performance diagnosis of electrolytic tank ion contamination, realizes early warning of electrolytic tank ion contamination (contamination incubation period), can be directly connected with the cathode outlet, and embedded in a hydrogen production system; it is suitable for high-power electrolytic tank coupling wind and light fluctuation energy and other industrial scenes, and solves the four problems of large hysteresis, poor anti-interference, inability to capture dynamic characteristics and high integration cost of the prior art.

Description

Technical Field

[0001] This invention relates to the field of water electrolysis for hydrogen production technology, and more specifically, to an online diagnostic system and method for electrolyzers based on the characteristics of cathode effluent water quality. Background Technology

[0002] Proton exchange membrane electrolysis for hydrogen production has become a core pathway for green hydrogen production due to its high efficiency, fast response, and high hydrogen purity. However, the long-term performance and durability of this technology are severely limited by the quality of the feed water. Research and engineering practice show that over 80% of field operation failures originate from ion contamination, such as Na+ ions. + Ca² + Fe³ + Impurities can originate from residual feedwater or corrosion in system pipelines. These impurity ions compete for proton exchange sites within the membrane electrode, catalyze membrane degradation, or poison the catalyst, leading to increased membrane resistance, accelerated performance degradation of the electrolyzer, and increased energy consumption.

[0003] Currently, commercial PEM electrolysis hydrogen production systems mainly rely on monitoring macroscopic parameters such as voltage and current, generally lacking the ability to directly perceive the chemical state inside the electrolyzer. For the core risk of ion contamination, existing assessment methods have significant limitations, and methods relying on changes in electrical properties for diagnosis are slow to respond. Offline laboratory water quality analysis cannot meet the needs of real-time, continuous monitoring. This results in "blind spots" in operation and maintenance, making it difficult to achieve early warning of ion contamination in the electrolyzer. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide an online diagnostic system and method for electrolyzers based on the characteristics of cathode effluent water quality, which effectively replaces the traditional electrical performance diagnostic method for ion contamination in electrolyzers and realizes early warning (contamination latency period) of ion contamination in electrolyzers; it can be directly connected to the cathode outlet and embedded in a hydrogen production system; it is suitable for industrial scenarios such as high-power electrolyzers coupled with wind and solar wave energy, and solves the four major problems of existing technologies: large lag, poor anti-interference, inability to capture dynamic characteristics, and high integration cost.

[0005] The solution adopted by this invention to solve the technical problem is: on the one hand: This invention provides an online diagnostic method for electrolyzers based on the characteristics of cathode effluent water quality. By continuously monitoring the water quality characteristic parameters of the effluent from the cathode outlet of the electrolyzer and comparing them with the set safe upper limit or benchmark threshold of the water quality characteristic parameters, it is determined whether the electrolyzer is contaminated by ions. The water quality characteristics include conductivity, pH value, and water temperature.

[0006] In some possible implementations, the specific steps include: Step S1: Real-time acquisition of the conductivity σ of the effluent from the cathode outlet of the electrolyzer. raw-i pH value raw-i and water temperature value T i Based on water temperature value T i Corrected to conductivity σ at standard temperature of 25°C raw-i pH value raw-i Standardization is performed to obtain the equivalent conductivity σ at standard temperature. i and equivalent pH value i ; Step S2: Calculate the equivalent conductivity σ at any given time. i or equivalent pH value i Compared with the set safe upper limit value of conductivity σ max Or pH safety upper limit pH max Perform a comparative judgment; if σ i >σ max or pH i >pH max This confirms that the electrolytic cell is contaminated with ions; Step S3: Calculate the equivalent conductivity σ i and equivalent pH value i The electrolyzer is compared with the set conductivity reference threshold σ0 and pH reference threshold pH0 to determine whether the electrolyzer is normal or abnormal. Step S4: When the electrolytic cell malfunctions, the continuously obtained equivalent conductivity σ i By performing differential calculations, we can obtain the slope k of its change over time. σ By varying the slope k σ Determine if the abnormality of the electrolytic cell continues to worsen; Step S5: When the electrolyzer abnormality continues to deteriorate, track the equivalent conductivity σ over a certain period of time. i pH equivalent i Real-time data and trends, and analysis and judgment; If the equivalent pH value is i Simultaneously presenting the same equivalent pH value σ i If the same trend of change is observed, it confirms that the electrolyzer is suffering from ion contamination.

[0007] In some possible implementations, determining whether the electrolytic cell is normal or abnormal in step S3 specifically refers to: If σ i ≤σ0 and pH i If the pH value is ≤0, the electrolytic cell is considered to be normal. If σ i >σ0 and pH i If the pH value is greater than 0, the electrolytic cell is determined to be abnormal, and step S4 is executed.

[0008] In some possible implementations, the change in slope k σ Determining whether an electrolytic cell malfunction is continuously worsening specifically refers to: If k σ If the value is ≤0, it is determined that the abnormal trend of the electrolyzer has not worsened, and monitoring continues. Return to step S3. If k σ If the value is >0, the electrolytic cell is determined to be abnormal and showing a continuous deterioration trend, and it is confirmed whether it is operating under special conditions. The special operating conditions are at least one of the membrane electrode activation process, startup process, or shutdown process.

[0009] In some possible implementations, when the electrolytic cell is abnormal and shows a continuous deterioration trend, and the electrolytic cell is operating under special conditions, it is determined that the current abnormality and continuous deterioration trend of the electrolytic cell is caused by the special conditions. After the special conditions period ends, the process returns to step S3. When the electrolytic cell is abnormal and shows a continuous deterioration trend, and is not under special operating conditions, proceed to step S5.

[0010] In some possible implementations, a time period in step S5 is 1-5 minutes.

[0011] In some possible implementations, the upper limit of the conductivity σ max 5 μS / cm, pH safety upper limit pH max The conductivity reference threshold σ0 is 0.1 μS / cm, and the pH reference threshold pH0 is 7.0.

[0012] on the other hand: The present invention also provides an online diagnostic system for an electrolyzer based on the characteristics of cathode effluent water quality, comprising a sampling unit connected to the cathode outlet of the electrolyzer for sampling water samples, a detection unit connected to the sampling unit for real-time monitoring of the water samples collected by the sampling unit, and a control unit connected to the monitoring unit for executing the online diagnostic method for an electrolyzer based on the characteristics of cathode effluent water quality described above.

[0013] In some possible implementations, a gas-liquid separation unit is also included, which is connected to the cathode outlet of the electrolytic cell and the sampling unit, respectively.

[0014] In some possible implementations, the gas-liquid separation unit is provided with an inlet connected to the cathode outlet of the electrolytic cell, a gas outlet, and a liquid outlet connected to the sampling unit; the gas outlet is externally connected to a hydrogen processing pipeline.

[0015] In some possible implementations, the gas-liquid separation unit is a vertical separation tank, and a multi-layer wire mesh coalescer is arranged within the gas-liquid separation unit and along its axial direction; the surface of the wire mesh coalescer is treated with corrosion resistance.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention directly and continuously monitors key cathode effluent water quality parameters (conductivity, pH value) that reflect the pollution process and performs real-time status analysis. Before pollutants cause irreversible damage to the membrane electrode and before the macroscopic electrical performance deteriorates significantly, abnormal signals are captured. This advances the diagnostic point from "verification after performance failure" to "early warning before pollution accumulation", creating conditions for proactive intervention. Attached Figure Description

[0017] Figure 1 This is a flowchart of the process of the present invention; Figure 2 This is a schematic diagram of the system structure in this invention; Figure 3 This is a schematic diagram of the polarization curves in Comparative Example 1; in: 1. Gas-liquid separation unit; 2. Entrance; 3. Gas outlet; 4. Wire mesh coalescer; 5. Sampling unit; 6. Detection unit; 7. Control unit; 8. Electrolytic cell. Detailed Implementation

[0018] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. The terms "first," "second," and similar terms used in this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, "a" or "one," etc., do not indicate a quantity limitation, but rather indicate the existence of at least one. In the implementation of this application, "and / or" describes the association relationship of related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more. For example, multiple positioning posts refer to two or more positioning posts. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0019] The present invention will now be described in detail.

[0020] like Figures 1-3 As shown: This invention provides an online diagnostic method for an electrolyzer 8 based on the characteristics of the cathode effluent. By continuously monitoring the water quality characteristic parameters of the effluent from the cathode outlet of the electrolyzer 8 and comparing them with the set safe upper limit or benchmark threshold of the water quality characteristic parameters, it is determined whether the electrolyzer 8 is contaminated by ions. The water quality characteristic parameters include conductivity, pH value and water temperature value.

[0021] In some possible implementations, the specific steps include: Step S1: Real-time acquisition of the conductivity σ of the water effluent from the cathode outlet of electrolytic cell 8. raw-i pH value raw-i and water temperature value T i Based on water temperature value T i Corrected to conductivity σ at standard temperature of 25°C raw-i pH value raw-i Standardization was performed to obtain the equivalent conductivity σ at a standard temperature of 25℃. i and equivalent pH value i ; The upper limit value of conductivity σ max 5 μS / cm, pH safety upper limit pH max The conductivity reference threshold σ0 is 0.1 μS / cm, and the pH reference threshold pH0 is 7.0.

[0022] Step S2: Calculate the equivalent conductivity σ at any given time. i or equivalent pH value i Compared with the set safe upper limit value of conductivity σ max Or pH safety upper limit pH max Perform a comparative judgment; if σ i >σ max or pH i >pH max If this is confirmed, electrolytic cell 8 will be contaminated with ions, a red light will be displayed and an alarm will be triggered; Step S3: Calculate the equivalent conductivity σ i and equivalent pH value i The electrolytic cell 8 is compared with the set conductivity reference threshold σ0 and pH reference threshold pH0 to determine whether it is normal or abnormal. If σ i ≤σ0 and pH i If the pH value is ≤0, then electrolytic cell 8 is considered to be normal, and a green light will be displayed. If σ i >σ0 and pH i If the pH value is greater than 0, then electrolytic cell 8 is determined to be abnormal, and a yellow light will be displayed to proceed to step S4.

[0023] Step S4: When electrolytic cell 8 malfunctions, the continuously acquired equivalent conductivity σ i By performing differential calculations, we can obtain the slope k of its change over time. σ By varying the slope k σ Determine if the abnormality of electrolytic cell 8 continues to worsen; If k σ If the value is ≤0, it is determined that the abnormal trend of electrolytic cell 8 has not worsened. The yellow light will be maintained and continuous monitoring will continue. Return to step S3. If k σ If the value is >0, it indicates that electrolytic cell 8 is abnormal and shows a continuous deterioration trend. It also confirms whether the cell is operating under special conditions and displays a blue light. When the electrolytic cell 8 is abnormal and shows a continuous deterioration trend, and the electrolytic cell 8 is operating under special conditions, it is determined that the current abnormality and continuous deterioration trend of the electrolytic cell 8 is caused by special conditions, and the light changes from blue to yellow. After the special conditions period ends, return to step S3. When electrolytic cell 8 malfunctions and shows a continuous deterioration trend, and is not under special operating conditions, a red light will be displayed; proceed to step S5. The special operating conditions are at least one of the membrane electrode activation process, startup process, or shutdown process.

[0024] Step S5: When the abnormality of electrolytic cell 8 continues to deteriorate, track the equivalent conductivity σ over a certain period of time. i pH equivalent iThe real-time data and trends are analyzed and judged; one time period in step S5 is 1-5 minutes. If the equivalent pH value is i Simultaneously presenting the same equivalent pH value σ i If the same trend of change is observed, a red light will be displayed and a warning will be issued, confirming that electrolytic cell 8 has been contaminated with ions. At this time, the maintenance personnel should shut down the machine and only restart it after the problem has been investigated and corrected. If the equivalent pH value is i If no change trend is observed, it is not a typical characteristic of ion contamination. The blue light should be maintained, and the situation should be assessed by maintenance personnel. This invention enables early identification and warning of ion contamination trends by continuously monitoring and dynamically analyzing key parameters of cathode effluent (such as conductivity and pH value), providing a direct basis for preventive maintenance. This invention replaces traditional electrical performance-based diagnosis of ion contamination in electrolyzers with dynamic time-series analysis of water quality parameters, enabling early warning (contamination latency period) of ion contamination in electrolyzers. It solves four major problems of existing technologies: large lag, poor anti-interference, inability to capture dynamic features, and high integration costs. Verification through examples shows that this solution can achieve early warning of ion contamination, providing core technological support for large-scale cost reduction in the green hydrogen industry, avoiding large-scale system overhauls, and significantly reducing equipment investment and maintenance costs while achieving accurate monitoring.

[0025] on the other hand: The present invention also provides an online diagnostic system for an electrolyzer 8 based on the characteristics of cathode effluent water quality, comprising a sampling unit 5 connected to the cathode outlet of the electrolyzer 8 for water sample collection, a detection unit 6 connected to the sampling unit 5 for real-time monitoring of the water sample collected by the sampling unit 5, a control unit 7 connected to the monitoring unit for executing the online diagnostic method for an electrolyzer 8 based on the characteristics of cathode effluent water quality described above, and a gas-liquid separation unit 1 connected to the cathode outlet of the electrolyzer 8 and the sampling unit 5 respectively; the control unit 7 is equipped with an audible and visual early warning module; Specifically, the detection unit 6 includes a temperature sensor, a pH sensor, and a conductivity sensor, which directly measures the water sample collected by the sampling unit 5 in real time. In some possible implementations, the gas-liquid separation unit 1 is provided with an inlet 2 connected to the cathode outlet of the electrolytic cell 8, a gas outlet 3 and a liquid outlet connected to the sampling unit 5; the gas outlet 3 is externally connected to a hydrogen processing pipeline.

[0026] In some possible implementations, the gas-liquid separation unit 1 is a vertical separation tank, and a multi-layer wire mesh coalescer 4 is arranged in the gas-liquid separation unit 1 along its axial direction; the surface of the wire mesh coalescer 4 is treated with corrosion resistance. This design effectively prevents the leaching of metal ions while ensuring efficient gas-liquid separation and low flow resistance. Specifically, gas outlet 3 is located at the top of the vertical separator, and liquid outlet is located at the top of the vertical separator and connected to the acquisition unit; water from the cathode outlet of electrolytic cell 8 enters the gas-liquid separation unit 1 for gas-liquid separation; the acquisition unit collects water samples from its liquid outlet for the detection unit 6 to monitor conductivity, pH value and water temperature, and transmits the data to the control unit 7 for dynamic analysis and processing.

[0027] Example 1: This embodiment simulates the online diagnostic process performed by the present invention when electrolytic cell 8 is in the membrane polarization activation process; in this embodiment, electrolytic cell 8 is a PEM electrolytic cell. In this invention, the inlet 2 of the gas-liquid separation unit 1 of the online diagnostic system for electrolyzer 8 based on cathode effluent water quality characteristics is connected to the cathode outlet of electrolyzer 8. The gas outlet 3 at the top of the gas-liquid separation unit 1 is used to connect to the hydrogen treatment pipeline, and the liquid outlet at the bottom is connected to the sampling unit 5. The detection unit 6 is built into the sampling unit 5. The control unit 7 is an embedded controller that is connected to the solenoid valve signals of the detection unit 6 and the sampling unit 5 via cables. It has pre-set diagnostic programs and control logic.

[0028] The gas-liquid separation unit 1 adopts a vertical 316L stainless steel separation tank with an inner wall treated by pickling and passivation. The tank is equipped with three layers of wire mesh coalescers 4 as the core separation components.

[0029] The wire mesh coalescer 4 is woven from 316L stainless steel wire with a diameter of 0.4 mm and a mesh count of 200. The surface is electroplated with a platinum layer of about 150 nm thickness.

[0030] Sampling unit 5 includes a quantitative chamber with a volume of 5 mL, controlled by upper and lower solenoid valves. Detection unit 6 integrates temperature, pH, and conductivity sensors to directly measure the water sample within the quantitative chamber in real time.

[0031] The initial judgment threshold set in this embodiment is: At standard temperature, the conductivity reference threshold σ0 is 0.1 μS / cm, and the pH reference threshold pH0 is 7.0.

[0032] During the activation process in electrolytic cell 8, the current density was first maintained at 0.2 A / cm² for 30 minutes, then increased to 1 A / cm² for 30 minutes, and finally maintained at 2 A / cm² for 3 hours. Equivalent conductivity σ i pH equivalent i The changes over time and the corresponding indicator signal states are shown in Table 1; In the initial stage of energization, the equivalent conductivity σ of the water sample at the cathode outlet i If the conductivity is below the baseline threshold σ0, the audible and visual warning module displays a first-level green signal, indicating that the status is normal.

[0033] When the current density increases to 1 A / cm², the equivalent conductivity σ i If the conductivity threshold σ0 is exceeded, a primary anomaly is triggered and dynamic trend monitoring is initiated. The audible and visual warning module displays a yellow light, indicating a secondary warning. Subsequently, the equivalent conductivity σ i It exhibits a slow upward trend, and its slope k changes over time. σ >0, at this time, since the operation phase is confirmed to be the preset membrane electrode activation process, as shown in Table 1, the membrane electrode activation is confirmed at 15:12, the sound and light warning module displays a blue light, the activation time is to last for 4 hours, that is, it ends at 19:12; execute the alarm suppression logic, the sound and light warning module blue light turns to yellow light and maintains yellow light, continuously monitors, and does not upgrade the alarm. When the activation process reaches 3A / cm 2 When the slope of change is above 100, the slope k is 100. σ As the conductivity gradually decreases, the measured conductivity value also decreases and eventually stabilizes, and the equivalent conductivity σ i If the value falls below the baseline threshold σ0 again, the audible and visual warning module will resume displaying the first-level green signal.

[0034] This complete dynamic process demonstrates that the present invention can successfully distinguish between expected normal activation conditions and actual ion contamination anomalies. Furthermore, after activation, monitoring data confirms that impurity ions have been almost completely released, and the electrolyzer 8 has returned to a normal stable operating state.

[0035]

[0036] Table 1 Example 2: To verify the effectiveness of the system of the present invention in early warning of ion contamination, this embodiment simulates the scenario of ion contamination in electrolyzer 8. Based on embodiment 1, the raw water is changed to contain 0.5 ppm Na. + The solution, used to simulate ion contamination in an electrolytic cell, was used in electrolytic cell 8 at a current density of 1 A / cm². 2It will continue to run until it reaches a steady state.

[0037] The system monitors the real-time conductivity of the cathode outlet water to obtain the equivalent conductivity σ. i As shown in Table 2, after energization, the equivalent conductivity σ i Rapidly exceeding the conductivity reference threshold σ0, equivalent pH value pH i If the pH value rapidly exceeds the pH reference threshold of pH0, the system immediately triggers a primary anomaly, and the audible and visual warning module displays a yellow light, indicating a secondary warning. The system then initiates dynamic trend monitoring and calculates the equivalent conductivity σ. i The slope k changes with time σ ; During the steady-state operation phase, the slope k changes σ A value >0 indicates that pollution is accumulating continuously. Based on this, the system determines it to be a persistent anomaly, and the audible and visual warning module displays a red light, upgrading to a level four warning. After triggering the Level 4 warning and confirming that it is not a special operating condition, the system immediately initiates a short-term monitoring window of 5 minutes to simultaneously track the equivalent conductivity σ. i pH equivalent i Real-time data and trends; determine the equivalent pH value. i Synchronously present the same σ i The same trend of change confirmed that electrolytic cell 8 was contaminated with ions. The control unit output a fifth-level fault confirmation signal, that is, the sound and light warning module displays a red light and emits an alarm sound.

[0038]

[0039] Table 2 Comparative Example 1: This comparative example demonstrates the assessment of the state of electrolyzer 8 using current electrochemical monitoring methods, specifically referring to: The same apparatus and activation process as in Example 1 are used, but the difference is that the online diagnostic system and method of the present invention are not configured, and the detection relies entirely on offline laboratory analysis after the operation is completed.

[0040] Electrolytic cell 8 performs a stepped current density activation operation. First, it is run at a constant current density of 0.2 A / cm² for 30 minutes. Then, the current density is increased to 1 A / cm² and maintained for 30 minutes. Finally, it is run at a current density of 2 A / cm² for 3 hours to complete the activation. After the electrolytic cell 8 was activated, its polarization curve was immediately tested. The results showed that the forward and reverse scan curves basically overlapped. Figure 3 As shown, through Figure 3It can be seen that the membrane electrode is in an initial healthy state; at the same time, offline collection of outlet water samples from the cathode side for testing showed that the conductivity σ was 0.07 μS / cm and the pH value was 5.40.

[0041] To simulate the ion contamination process, referring to Example 2, the raw water was replaced with water containing 0.5 ppm Na. + The solution was used, and the electrolyzer operated continuously for 200 hours at a constant current density of 2A / cm². During this period, no real-time online water quality monitoring was performed on the cathode circulating water, and the system did not trigger any warnings or protective operations related to ion contamination.

[0042] After 200 hours of operation, the condition of the electrolytic cell was tested and verified; for example... Figure 3 As shown, polarization curve analysis revealed a significant shift between the forward and reverse scan curves, indicating that the membrane electrode had suffered severe ion contamination. Offline laboratory testing of the cathode effluent confirmed that the water quality had deteriorated significantly, with a conductivity σ as high as 10.17 μS / cm and a pH value rising to 10.25, significantly exceeding the safe operating limit of electrolyzer 8.

[0043] Therefore, it is evident that traditional methods relying on periodic offline water quality testing and polarization curve analysis suffer from severe monitoring lag. Problems are only detected after the electrolyzer has been running continuously for 200 hours and irreversible performance damage has already occurred due to ion contamination. This method cannot provide early warning during the contamination accumulation process, exposing the electrolyzer to membrane degradation, severe efficiency reduction, and safety risks. In terms of timeliness and safety, it is significantly inferior to the online monitoring and early warning method proposed in this embodiment of the invention.

[0044] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. An online diagnostic method for electrolytic cells based on cathode effluent water quality characteristics, characterized in that, By continuously monitoring the water quality characteristics of the effluent from the cathode outlet of the electrolyzer and comparing them with the set safe upper limit or benchmark threshold of the water quality characteristics, it can be determined whether the electrolyzer is contaminated by ions. The water quality characteristics include conductivity, pH value, and water temperature.

2. The online diagnostic method for electrolytic cells based on cathode effluent water quality characteristics according to claim 1, characterized in that, Specifically, the following steps are included: Step S1: Real-time acquisition of the conductivity of the effluent from the cathode outlet of the electrolyzer. σ raw-i pH value raw-i and water temperature value T i Based on water temperature value T i Corrected to conductivity at standard temperature of 25°C σ raw-i pH value raw-i Standardization is performed to obtain the equivalent conductivity σ at standard temperature. i and equivalent pH value i ; Step S2: Calculate the equivalent conductivity σ at any given time. i or equivalent pH value i Compared with the set safe upper limit value of conductivity σ max Or pH safety upper limit pH max Compare and judge; if the equivalent conductivity σ i >Safe upper limit of conductivity σ max or equivalent pH value i > pH safety upper limit pH max This confirms that the electrolytic cell is contaminated with ions; Step S3: Calculate the equivalent conductivity σ i and equivalent pH value i The electrolyzer is compared with the set conductivity reference threshold σ0 and pH reference threshold pH0 to determine whether the electrolyzer is normal or abnormal. Step S4: When the electrolytic cell malfunctions, the continuously obtained equivalent conductivity σ i By performing differential calculations, we can obtain the slope k of its change over time. σ By varying the slope k σ Determine if the abnormality of the electrolytic cell continues to worsen; Step S5: When the electrolyzer abnormality continues to deteriorate, track the equivalent conductivity σ over a certain period of time. i pH equivalent i Real-time data and trends, and analysis and judgment; If the equivalent pH value is i Simultaneously presenting the same equivalent pH value σ i If the same trend of change is observed, it confirms that the electrolyzer is suffering from ion contamination.

3. The online diagnostic method for electrolytic cells based on cathode effluent water quality characteristics according to claim 2, characterized in that, The step S3, determining whether the electrolytic cell is normal or abnormal, specifically refers to: If σ i ≤σ0 and pH i If the pH value is ≤0, the electrolytic cell is considered to be normal. If σ i >σ0 and pH i If the pH value is greater than 0, the electrolytic cell is determined to be abnormal, and step S4 is executed.

4. The online diagnostic method for electrolytic cells based on cathode effluent water quality characteristics according to claim 2, characterized in that, The method of changing the slope k σ Determining whether an electrolytic cell malfunction is continuously worsening specifically refers to: If k σ If the value is ≤0, it is determined that the abnormal trend of the electrolyzer has not worsened, and monitoring continues. Return to step S3. If k σ If the value is >0, the electrolytic cell is determined to be abnormal and showing a continuous deterioration trend, and it is confirmed whether it is operating under special conditions. The special operating conditions are at least one of the membrane electrode activation process, startup process, or shutdown process.

5. The online diagnostic method for an electrolyzer based on cathode effluent water quality characteristics according to claim 4, characterized in that, When the electrolytic cell is abnormal and shows a continuous deterioration trend, and the electrolytic cell is operating under special conditions, it is determined that the current abnormality and continuous deterioration trend of the electrolytic cell is caused by the special conditions. After the special conditions period ends, return to step S3. When the electrolytic cell is abnormal and shows a continuous deterioration trend, and is not under special operating conditions, proceed to step S5.

6. The online diagnostic method for an electrolyzer based on cathode effluent water quality characteristics according to claim 2, characterized in that, One time period in step S5 is 1-5 minutes.

7. The online diagnostic method for an electrolyzer based on cathode effluent water quality characteristics according to claim 2, characterized in that, The upper limit value of conductivity σ max 5 μS / cm, pH safety upper limit pH max The conductivity reference threshold σ0 is 0.1 μS / cm, and the pH reference threshold pH0 is 7.

0.

8. An online diagnostic system for an electrolyzer based on the characteristics of cathode effluent water quality, characterized in that, The device includes a sampling unit connected to the cathode outlet of the electrolytic cell for water sampling, a detection unit connected to the sampling unit for real-time monitoring of the water samples collected by the sampling unit, a control unit connected to the monitoring unit for performing the online diagnostic method for the electrolytic cell based on the characteristics of the cathode effluent water as described in any one of claims 1-7, and a gas-liquid separation unit connected to the cathode outlet of the electrolytic cell and the sampling unit respectively.

9. The online diagnostic system for an electrolyzer based on cathode effluent water quality characteristics according to claim 8, characterized in that, The gas-liquid separation unit is provided with an inlet connected to the cathode outlet of the electrolytic cell, a gas outlet, and a liquid outlet connected to the sampling unit; the gas outlet is externally connected to a hydrogen processing pipeline.

10. An online diagnostic system for an electrolyzer based on cathode effluent water quality characteristics according to claim 9, characterized in that, The gas-liquid separation unit is a vertical separation tank, and a multi-layer wire mesh coalescer is arranged inside the gas-liquid separation unit along its axial direction; the surface of the wire mesh coalescer is treated with corrosion resistance.

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