Electrochemical catalytic hydrogen concentration detection system and method

Abstract

The application discloses an electrochemical catalytic hydrogen concentration detection system and method. The detection system comprises a gas sampling module, a gas-water separation device, a chemical filtering device and an electrochemical electrode detection module. The gas sampling module is used for obtaining sample gas containing hydrogen from a measured gas pipeline. The gas-water separation device is used for controlling the humidity of the sample gas within a predetermined range. The chemical filtering device is used for removing impurity gas toxic to the catalyst in the sample gas. The electrochemical electrode detection module is in communication with the chemical filtering device and comprises an ion exchange membrane electrode assembly with an anode and a cathode, which is used for electrochemical reaction with hydrogen in the sample gas and generates an electrochemical signal. A self-power generation and signal processing module is electrically connected with the electrochemical electrode detection module, which is used for collecting the electrochemical signal and at least partially using the electric energy generated by the electrochemical reaction to supply power for itself. The system and method provided by the application can improve the sensitivity, stability and safety of trace hydrogen detection under the oxygen-rich working condition.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to an electrochemical catalytic hydrogen concentration detection system and method. Background Technology

[0002] In hydrogen production, storage, transportation, and fuel cell applications, highly sensitive and reliable online monitoring of hydrogen-containing gases or potentially leaking hydrogen is a core safety requirement. Particularly important is monitoring hydrogen concentration in oxygen streams (such as high-purity oxygen produced at the cathode side of an electrolyzer, oxygen-enriched process gases, and air at hydrogen refueling stations). Because the lower explosive limit of hydrogen is significantly reduced and the ignition energy is drastically decreased in oxygen-enriched environments, even trace amounts of hydrogen accumulating in the tens to hundreds of ppm range can pose serious safety hazards. Therefore, there is an urgent market demand for developing a detection device capable of online detection of hydrogen concentration in oxygen with ppm-level accuracy, suitable for high-risk oxygen-enriched environments.

[0003] Currently, existing technologies for hydrogen concentration detection mainly include thermal conductivity detectors, catalytic combustion sensors, metal oxide semiconductor sensors, and electrochemical sensors. However, these existing technologies have many shortcomings when applied to the detection of trace hydrogen in oxygen. While thermal conductivity detectors are sensitive to the difference in thermal conductivity between hydrogen and oxygen, their complex structure, high baseline stability requirements, and the need for high-purity carrier gas and precise temperature control make compact, low-cost online deployment difficult. Catalytic combustion sensors are prone to peroxidation and accelerated degradation when operating in oxygen-rich atmospheres, resulting in a significantly shortened lifespan. Their detection limits are typically only a few hundred to a few thousand ppm, failing to meet the trace detection requirements for early warning. Metal oxide semiconductor sensors are extremely sensitive to water vapor, ambient temperature, and cross-gas interference, exhibiting poor long-term stability and severe signal drift in humid oxygen environments. Electrochemical sensors mostly use liquid or solid electrolytes and typically operate in atmospheric background conditions, lacking specific designs for high oxygen partial pressure and high humidity conditions. In addition, most of these sensors require an external power supply circuit, while oxygen-enriched environments often have inherent safety requirements for electrical equipment. Introducing an external power supply increases wiring costs and potential ignition risks.

[0004] Therefore, it is necessary to propose a technical solution to overcome the shortcomings of existing technologies. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention proposes an electrochemical catalytic hydrogen concentration detection system and method, which can improve the sensitivity, stability and safety of trace hydrogen detection under oxygen-rich conditions.

[0006] This invention is achieved through the following technical solution: an electrochemical catalytic hydrogen concentration detection system, comprising: The gas sampling module is used to obtain hydrogen-containing sample gas from the gas pipeline being tested; A gas-water separation device, connected to the gas sampling module, is used to control the humidity of the sample gas within a predetermined range; A chemical filtration device, connected to the gas-liquid separation device, is used to remove impurity gases that are poisonous to the catalyst from the sample gas. An electrochemical electrode detection module is connected to the chemical filtration device. The electrochemical electrode detection module includes an ion exchange membrane electrode assembly with an anode and a cathode, which is used to react electrochemically with hydrogen in the sample gas and generate an electrochemical signal. The self-generating and signal processing module is electrically connected to the electrochemical electrode detection module and is used to collect the electrochemical signal and at least partially utilize the electrical energy generated by the electrochemical reaction to power itself.

[0007] As a further improved technical solution, the gas sampling module includes a Venturi ejector, which uses the process gas pressure difference of the gas pipeline being measured as the driving force to perform passive gas sampling.

[0008] As a further improved technical solution, the gas sampling module includes a Venturi ejector, which uses the pressure difference formed by the driving gas introduced into the gas pipeline to be measured as the driving force to perform passive gas sampling.

[0009] As a further improved technical solution, the Venturi ejector is configured such that the volume ratio of the ejector gas to the driving gas is 5:1 to 20:1.

[0010] As a further improved technical solution, the gas-water separation device includes a hydrocyclone separator and a hydrophobic microporous membrane. The hydrocyclone separator uses centrifugal force to throw out droplets, and the hydrophobic microporous membrane has a pore size of 0.2-1μm and a water contact angle greater than 130° to block liquid water. The humidity of the sample gas is controlled at 30%-80% relative humidity.

[0011] As a further improved technical solution, the chemical filtration device includes an activated carbon layer, a catalytic oxidation layer, and a soda lime layer, used to remove carbon monoxide, sulfides, ammonia, and volatile organic compounds from the sample gas.

[0012] As a further improved technical solution, the chemical filtration device includes a bypass sampling interface for sampling and analyzing the gas before and after filtration.

[0013] As a further improved technical solution, the anode of the electrochemical electrode detection module includes a catalyst coating film, a gas diffusion layer, and an electrode plate, wherein the platinum loading of the catalyst coating film is 0.05-0.2 mg / cm³.2 The gas diffusion layer is a carbon layer with a thickness of 150-250 μm. The hydroxide reaction at the anode generates an open-circuit voltage signal, and the relationship between the open-circuit voltage signal and the hydrogen concentration conforms to the Nernst equation.

[0014] As a further improved technical solution, the self-generating and signal processing module includes a DC-DC boost converter, a supercapacitor, and a signal acquisition circuit. The DC-DC boost converter boosts the voltage generated by the electrochemical reaction to the operating voltage required by the signal acquisition circuit. The supercapacitor is used to maintain short-term power supply to the signal acquisition circuit when the hydrogen concentration in the sample gas is lower than a preset threshold.

[0015] This invention is also achieved through the following technical solution: an electrochemical catalytic hydrogen concentration detection method, implemented using the system described above, the method comprising the following steps: Sample gas is obtained from a hydrogen-containing oxygen stream using a gas sampling module; Liquid water is removed from the sample gas using a gas-liquid separator to control the relative humidity within a predetermined range; Catalyst-poisoned impurities in the sample gas are removed using a chemical filtration device; The processed sample gas is introduced into the anode side of the electrochemical electrode detection module, and the reference gas is introduced into the cathode side, generating an electrochemical signal related to the hydrogen concentration. The electrical energy generated by the electrochemical reaction is used to power the signal acquisition circuit, and the electrochemical signal is acquired to calculate the hydrogen concentration.

[0016] The electrochemical catalytic hydrogen concentration detection system provided by this invention achieves highly sensitive and stable online detection of trace hydrogen in oxygen or oxygen-enriched atmospheres through the systematic integration of a gas sampling module, a gas-liquid separation device, a chemical filtration device, an electrochemical electrode detection module, and a self-generating and signal processing module. On one hand, the gas-liquid separation device controls the sample gas humidity within a suitable range for ion exchange membrane operation, avoiding mass transfer blockage and signal drift caused by water flooding. The chemical filtration device effectively removes catalyst poisoning impurities such as carbon monoxide and hydrogen sulfide, significantly extending the electrode's lifespan and ensuring long-term stability of detection accuracy. On the other hand, the self-generating and signal processing module utilizes the electrical energy generated by the electrochemical reaction of hydrogen on the electrodes to power the signal acquisition circuit, achieving at least partial self-powered operation of the device. This reduces dependence on external power sources and wiring costs. Furthermore, the gas sampling module can employ a passive, non-powered sampling method, further enhancing inherent safety and deployment flexibility in high-risk oxygen-enriched environments. This device achieves ppm-level detection limits, rapid response, and long-term maintenance-free online monitoring. Attached Figure Description

[0017] Figure 1 This is a block diagram of the electrochemical catalytic hydrogen concentration detection system of the present invention.

[0018] Figure 2 This is a schematic diagram of the operation flow of the electrochemical electrode detection module and the self-generating power and signal processing module in the electrochemical catalytic hydrogen concentration detection system of the present invention.

[0019] Figure 3 This is an exploded view of the electrodes in the electrochemical electrode detection module of the electrochemical catalytic hydrogen concentration detection system of the present invention.

[0020] Figure 4 This is a calibration curve of open-circuit voltage versus hydrogen concentration in one embodiment of the electrochemical catalytic hydrogen concentration detection system of the present invention.

[0021] The reference numerals in the attached diagram are as follows: 1. Gas sampling module; 2. Gas-water separation device; 3. Chemical filtration device; 4. Electrochemical electrode detection module; 41. Anode plate; 42. Anode gas diffusion layer; 43. Catalyst coating film; 44. Cathode gas diffusion layer; 45. Cathode plate; 5. Self-generated power and signal processing module. Detailed Implementation

[0022] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] like Figures 1 to 4 As shown, this invention provides an electrochemical catalytic hydrogen concentration detection system, which includes a gas sampling module 1, a gas-liquid separation device 2, a chemical filtration device 3, an electrochemical electrode detection module 4, and a self-generating and signal processing module 5. The gas sampling module 1 is used to obtain a hydrogen-containing sample gas from the gas pipeline being tested, and its outlet is connected to the inlet of the gas-liquid separation device 2; the outlet of the gas-liquid separation device 2 is connected to the inlet of the chemical filtration device 3; the outlet of the chemical filtration device 3 is connected to the anode-side inlet of the electrochemical electrode detection module 4; and the output terminal of the electrochemical electrode detection module 4 is electrically connected to the input terminal of the self-generating and signal processing module 5. All modules work together to achieve highly sensitive and stable online detection of trace hydrogen in oxygen or oxygen-enriched atmospheres.

[0025] Specifically, the gas sampling module 1 includes a Venturi ejector. This ejector utilizes the naturally occurring process gas pressure difference or a small flow of driving gas in the gas pipeline being tested as the driving force, allowing the sample gas to be drawn from the main pipeline without the need for an external electric pump or fan. In one embodiment, the Venturi ejector can be configured to perform passive gas sampling using the process gas pressure difference in the gas pipeline being tested as the driving force. For example, a small stream of driving gas can be drawn from the high-pressure side of the main pipeline, creating a low-pressure zone through the ejector nozzle, thereby drawing in the gas being tested. In another embodiment, the Venturi ejector can also utilize the pressure difference formed by the driving gas specifically introduced into the gas pipeline being tested as the driving force for passive gas sampling. For example, an external compressed air or nitrogen can be used as the driving gas source. This driving gas source also does not require an electric pump; it can simply utilize the existing compressed gas pipeline network on site. Regardless of the method used, the Venturi ejector has no moving parts, fundamentally eliminating the risk of electrical sparks, making it particularly suitable for high-risk explosion-proof scenarios such as oxygen or oxygen-enriched atmospheres. Experiments show that by rationally designing the nozzle diameter, mixing chamber length, and diffusion angle of the ejector, the volume ratio of the ejector gas (i.e., the sample gas being drawn in) to the driving gas can reach 5:1 to 20:1. Within this ejection ratio range, it is possible to ensure a sufficiently representative sample gas flow rate from the main pipeline without causing downstream pressure oscillations or excessive sample loss due to excessive ejection volume. Controlling the ejection ratio within this range also allows the Venturi ejector to operate stably with a smaller driving gas consumption, further reducing the system's demand for external energy and facilitating the energy balance of the subsequent self-generating module. A buffer chamber can also be installed at the outlet of the gas sampling module 1. This buffer chamber can smooth out flow fluctuations caused by ejector pulsation, making the airflow entering the downstream gas-liquid separator 2 more stable, thereby improving the signal-to-noise ratio of the entire detection system.

[0026] The gas sampling module 1 delivers the sample gas into the gas-liquid separator 2. Since the gas to be tested typically contains a high concentration of water vapor or even entrained liquid water mist, excessive moisture entering the electrochemical electrode detection module 4 can flood the ion exchange membrane, clogging the microporous channels of the gas diffusion layer and causing a sharp increase in mass transfer resistance. This can lead to electrochemical signal drift, slower response, or even complete failure. By setting up the gas-liquid separator 2, the humidity of the sample gas can be controlled within a predetermined range. In a preferred embodiment, the gas-liquid separator 2 includes a hydrocyclone separator and a hydrophobic microporous membrane. The hydrocyclone separator, as the first-stage separation unit, utilizes centrifugal force to separate large droplets. Specifically, when the sample gas enters the hydrocyclone separator tangentially, under the action of centrifugal force, denser droplets are thrown against the wall and collected before being discharged from the bottom drain, while the gas flows upward from the center. After hydrocyclone separation, most droplets with a particle size greater than 5 μm have been removed, but small droplets or high-humidity water vapor may still remain in the gas. At this point, the second-stage hydrophobic microporous membrane further plays its role. The hydrophobic microporous membrane is preferably made of polytetrafluoroethylene (PTFE), with a pore size controlled between 0.2 μm and 1 μm and a water contact angle greater than 130°. Due to surface tension, liquid water cannot permeate the membrane, while gas molecules such as hydrogen and oxygen can diffuse freely. This two-stage combined gas-water separation device 2 can stabilize the relative humidity of the sample gas within a predetermined range of 30% to 80% over a wide range of gas flow rates and humidity. Controlling the humidity within this range avoids both excessively high relative humidity (>80% RH) which would cause liquid water to condense inside the electrode, preventing flooding, and excessively low relative humidity (<30% RH) which would cause the ion exchange membrane to lose water and significantly reduce conductivity, thus maintaining the electrode in its optimal operating state. After processing by the gas-water separation device 2, the liquid water in the sample gas is essentially eliminated, and the water vapor content is adjusted to a level suitable for subsequent electrochemical detection.

[0027] The sample gas after passing through the gas-liquid separator 2 enters the chemical filter 3 for impurity gas filtration. In practical industrial applications, the oxygen stream may carry trace impurities that poison the platinum catalyst at the anode electrode, such as carbon monoxide (CO), sulfides (acidic gases such as H2S and SO2), ammonia (NH3), and various volatile organic compounds. These impurity gases are irreversibly adsorbed onto the platinum active sites, leading to a decrease in the exchange current density of the hydrogen oxidation reaction (HOR), which in turn attenuates the open-circuit voltage signal, reduces detection sensitivity, and shortens electrode life. By setting up the chemical filter 3, the aforementioned impurity gases that poison the catalyst can be removed. In a preferred embodiment, the chemical filter 3 includes an activated carbon layer, a catalytic oxidation layer, and a soda lime layer. The activated carbon layer, with its abundant microporous structure and large specific surface area, effectively captures volatile organic compounds and some sulfides through physical adsorption. The catalytic oxidation layer preferably uses potassium permanganate (KMnO4) or manganese dioxide (MnO2), which can be supported on a porous ceramic or metal foam framework. Under room temperature conditions, it utilizes sufficient oxygen in an oxygen-rich gas environment to catalytically oxidize carbon monoxide to non-toxic carbon dioxide (CO2), while also oxidizing some sulfides to sulfates or sulfur dioxide, which are then absorbed by subsequent layers. The soda lime layer, mainly composed of a mixture of calcium hydroxide and sodium hydroxide, can absorb acidic gases such as hydrogen sulfide, sulfur dioxide, and chlorine, as well as residual carbon dioxide. It should be noted that although carbon dioxide itself does not directly poison the platinum catalyst, excessive CO2 may cause carbonate deposition on the cathode side of the electrode, affecting long-term stability. Therefore, the soda lime layer serves as a preventative measure. The three filter layers are arranged sequentially according to the airflow direction, but the order can be adjusted or other functional layers can be added depending on the specific application. To facilitate monitoring the saturation level of the chemical filtration device 3, it further includes a bypass sampling interface. This interface can be connected to a three-way valve to draw sample gas from upstream and downstream of the filter, respectively. The sample is then compared and analyzed using an external portable gas analyzer or a periodic gas sampling bag. When no significant difference is found in the concentration of carbon monoxide or hydrogen sulfide in the gas before and after filtration, it indicates that the filter layer is nearing saturation and needs timely replacement. Furthermore, the system can automatically determine the filter status based on the baseline potential drift output by the electrochemical electrode detection module 4. When the baseline potential continuously decreases beyond a preset threshold and other interfering factors are eliminated, a filter replacement alarm can be issued. Through the pretreatment of the chemical filtration device 3, the concentration of poisons in the sample gas is reduced to a level that has virtually no effect on the platinum catalyst, thereby significantly extending the continuous working life of the electrochemical electrode detection module 4, which is expected to reach more than two years. It should be noted that the order of the gas-liquid separation device 2 and the chemical filtration device 3 can be interchanged, or they can be integrated into a single module.

[0028] The sample gas, after undergoing dual pretreatment of gas-liquid separation and chemical filtration, is introduced into the electrochemical electrode detection module 4. For example... Figure 3 As shown, the core component of the electrochemical electrode detection module 4 is the electrode assembly, which, from the inside out, includes a catalyst coating film 43, an anode gas diffusion layer 42, an anode plate 41, a cathode gas diffusion layer 44, and a cathode plate 45. The catalyst coating film 43 consists of an ion exchange membrane and catalyst layers coated on its upper and lower surfaces. The anode-side catalyst is platinum (Pt), used to catalyze the hydrogen oxidation reaction (HOR); the cathode-side catalyst can be platinum or platinum-carbon, but it mainly provides a stable reference potential under a reference atmosphere. To reduce costs while ensuring catalytic activity, the platinum loading of the anode-side catalyst coating film 43 is preferably controlled at 0.05 mg / cm³. 2 Up to 0.2 mg / cm 2 The loading range ensures a sufficiently high hydrogen oxidation rate even at trace hydrogen partial pressures in the ppm range, while avoiding excessive use of precious metals. The anode gas diffusion layer 42 and cathode gas diffusion layer 44 are preferably made of carbon paper or carbon cloth, with a thickness of 150 μm to 250 μm. This thickness range provides appropriate porosity and mechanical strength, ensuring rapid diffusion of hydrogen from the flow field to the catalyst layer while also supporting the electrodes and preventing deformation. The anode plate 41 and cathode plate 45 are specifically, for example, bipolar plates, which can be formed from 316L stainless steel or graphite. A flow field structure is provided on the side facing the gas diffusion layer, preferably a serpentine or parallel flow channel. The depth and width of the flow channel are designed to ensure uniform distribution of the sample gas throughout the active region of the anode, avoiding localized concentration polarization. During operation, the electrochemical electrode detection module 4 introduces the pre-treated sample gas (oxygen stream containing trace amounts of hydrogen) to the anode side, while a reference gas is introduced to the cathode side. The reference gas can be pure nitrogen, air, or chemically filtered ambient air. Since there is a hydrogen partial pressure on the anode side and theoretically zero hydrogen partial pressure on the cathode side, hydrogen undergoes a hydrogen oxidation reaction under the action of the platinum catalyst at the anode: H₂ → 2H₂ + + 2e -The generated ions migrate to the cathode through the ion exchange membrane, while electrons flow to the cathode through the external circuit. Since there is no hydrogen gas at the cathode, this electrochemical cell is actually in a concentration cell state, and its open-circuit voltage (OCV) and the partial pressure of hydrogen gas at the anode conform to the Nernst equation: E = E° + (RT / 2F) × ln(P_H2 / P_ref), where E is the standard hydrogen electrode potential, R is the gas constant, T is the absolute temperature, F is the Faraday constant, P_H2 is the partial pressure of hydrogen gas at the anode, and P_ref is the partial pressure of hydrogen gas on the reference side (approaching 0). In practical applications, due to non-ideal factors such as electrode overpotential, the measured OCV value is slightly lower than the theoretical calculation value of the Nernst equation, but the two still maintain a good logarithmic linear relationship. A standard curve between OCV and hydrogen concentration is obtained through calibration, as shown below. Figure 4 As shown, quantitative detection is thus achieved. The electrochemical signal generated by the electrochemical electrode detection module 4, i.e., the open-circuit voltage, is output to the self-generating power and signal processing module 5 via the positive and negative electrode wires.

[0029] The self-generating power and signal processing module 5 is electrically connected to the electrochemical electrode detection module 4, used to acquire the electrochemical signal and at least partially utilize the electrical energy generated by the electrochemical reaction to power itself. In a preferred embodiment, the self-generating power and signal processing module 5 includes a DC-DC boost converter, a supercapacitor, and a signal acquisition circuit. Specifically, when the hydrogen concentration in the sample gas is high, for example, above 50 ppm, the open-circuit voltage generated by the electrochemical electrode detection module 4 is typically between 300mV and 500mV, with an output power in the microwatt to milliwatt range. This voltage and power level cannot directly drive a conventional signal acquisition circuit, so the generated electrical energy is first fed into the DC-DC boost converter. This boost converter uses a low-input-voltage start-up chip, which can gradually boost the voltage output by the electrode to 3.3V or 5V while performing impedance matching to maximize energy transfer efficiency. The stabilized voltage after boosting powers the signal acquisition circuit on one hand, and stores excess electrical energy in the supercapacitor on the other. The supercapacitor, also known as a farad capacitor, has the advantages of large capacity, low equivalent series resistance, and long charge-discharge cycle life. When the hydrogen concentration is high, the supercapacitor is charging. When the hydrogen concentration drops to a preset threshold, such as below 30 ppm, the power generated by the electrodes is insufficient to maintain the continuous operation of the signal acquisition circuit. At this time, the supercapacitor automatically discharges, providing short-term power to the signal acquisition circuit. Simultaneously, the signal acquisition circuit can enter a low-power intermittent operating mode: the microcontroller (MCU) wakes up every few seconds or tens of seconds, quickly completes one ADC sampling and data processing cycle, and immediately returns to sleep mode, reducing the average power consumption to below 50 μW. This collaborative working mechanism of self-generating supercapacitor buffering and intermittent sampling enables the self-generating and signal processing module 5 to operate self-sustainingly over a wide range of hydrogen concentrations, without the need for any external battery or mains power.

[0030] The core of the signal acquisition circuit includes a high input impedance differential amplifier, an analog-to-digital converter (ADC), a temperature sensor, and a microcontroller. The open-circuit voltage signal output from the electrochemical electrode detection module 4 first undergoes impedance transformation and voltage tracking via the differential amplifier to reduce the load effect of the measurement circuit on the electrode. The amplified signal is then converted into a digital value by the ADC and sent to the microcontroller. Simultaneously, the temperature sensor measures the ambient temperature or electrode temperature in real time, as the temperature term T in the Nernst equation has a significant impact on the OCV value. The MCU converts the ADC sampled value into the corresponding hydrogen concentration value based on the pre-stored calibration curve and temperature compensation algorithm. To adapt to different interface requirements in industrial settings, the self-generating and signal processing module 5 also integrates multiple output methods, including a 4-20mA analog current output and an RS485 digital communication interface. When the hydrogen concentration exceeds a preset safety alarm threshold, such as 200 ppm, the device can also issue an alarm signal through an optocoupler-isolated switch output terminal.

[0031] Based on the above detection system, the present invention also provides an electrochemical catalytic hydrogen concentration detection method, the method comprising the following steps: obtaining sample gas from a hydrogen-containing oxygen stream through a gas sampling module; removing liquid water from the sample gas through a gas-liquid separation device to control the relative humidity within a predetermined range; removing catalyst poisoning impurities from the sample gas through a chemical filtration device; allowing the treated sample gas to enter the anode side of an electrochemical electrode detection module, and a reference gas to enter the cathode side, generating an electrochemical signal related to the hydrogen concentration; using the electrical energy generated by the electrochemical reaction to power a signal acquisition circuit, and acquiring the electrochemical signal to calculate the hydrogen concentration.

[0032] The system and method of the present invention will be further described below with reference to two specific application examples. However, it should be understood that these embodiments do not constitute a limitation on the scope of protection of the present invention.

[0033] Application 1: Online hydrogen concentration monitoring at the oxygen outlet of the cathode in a PEM water electrolyzer.

[0034] Specifically, a certain PEM water electrolysis hydrogen production device produces high-purity oxygen (purity ≥99.5%) on the cathode side. During normal operation, the H2 concentration carried by the oxygen is <200 ppm. When the membrane experiences local pinhole failure, the H2 concentration may abnormally rise to 500–2000 ppm or even higher, posing an explosion risk.

[0035] The electrochemical catalytic hydrogen concentration detection system of this invention is installed on the bypass of the cathode oxygen outlet pipeline of the PEM water electrolysis hydrogen production device. The gas sampling module 1 uses a Venturi ejector, utilizing a pressure difference of approximately 0.05 MPa formed by a back pressure valve in the main pipeline as the driving force, with an ejection flow rate of 50 mL / min. The sample gas enters the gas-liquid separator 2 to control the relative humidity at 60% RH, and then enters the chemical filtration device 3 to remove impurities. The treated sample gas enters the anode side of the electrochemical electrode detection module 4, while compressed air that has undergone the same chemical filtration is introduced to the cathode side as a reference gas. The active area of ​​the electrode is 5 cm². 2 The anode Pt loading is 0.1 mg / cm³. 2 Before installation, the system was calibrated using standard H2 / O2 mixtures at concentrations of 10 ppm, 50 ppm, 100 ppm, 200 ppm, 500 ppm, and 1000 ppm to establish the logarithmic relationship between OCV and concentration. At 25°C, the measured OCV for 100 ppm H2 was approximately 320 mV, which agrees well with the theoretical value of the Nernst equation.

[0036] The test results show that the system can run continuously for 720 hours, with the detection limit stable at 5 ppm H2 (3σ noise level), response time <60 seconds, and output of 4–20 mA signal synchronously connected to the electrolytic cell control system to realize automatic alarm interlock for over-limit.

[0037] Application example two is the monitoring of trace hydrogen leaks in the air of the hydrogen storage cylinder group area of ​​a hydrogen refueling station.

[0038] Specifically, the safety leak monitoring scenario for hydrogen storage cylinders at hydrogen refueling stations requires the detection of hydrogen in the ppm range in air or oxygen-enriched gas. The existing catalytic combustion sensors have a minimum detection limit of about 500 ppm, which cannot meet the early warning requirements.

[0039] This system uses ambient air (approximately 21% O2) as the cathode reference gas and on-site sampled gas (oxygen-enriched stream containing trace amounts of H2) as the anode inlet gas. The ejector passively samples using a 0.02 MPa process pressure differential. The chemical filtration unit focuses on removing CO that may be present in the air.

[0040] The test results show that, within the range of 10–500 ppm H2, the linearity R... 2 >0.998; detection limit is 1 ppm (3σ); the device generates its own power and enters normal power supply mode when the H2 concentration is ≥30 ppm, and starts supercapacitor power supply mode when the H2 concentration is <30 ppm. The MCU wakes up to collect data once every 30 seconds, and the standby power consumption is <50 μW.

[0041] In summary, the electrochemical catalytic hydrogen concentration detection system and method provided by this invention, through the systematic integration of a gas sampling module 1, a gas-liquid separation device 2, a chemical filtration device 3, an electrochemical electrode detection module 4, and a self-generating and signal processing module 5, achieves highly sensitive and stable online detection of trace hydrogen in oxygen or oxygen-enriched atmospheres. The gas-liquid separation device 2 controls the sample gas humidity within a suitable range for ion exchange membrane operation, avoiding mass transfer blockage and signal drift caused by water flooding; the chemical filtration device 3 effectively removes catalyst poisoning impurities such as carbon monoxide and hydrogen sulfide, significantly extending the electrode's lifespan and ensuring long-term stability of detection accuracy; the self-generating and signal processing module 5 utilizes the electrical energy generated by the electrochemical reaction of hydrogen on the electrode to power the signal acquisition circuit, achieving at least partial self-powered operation of the device, reducing dependence on external power sources and wiring costs; and the Venturi ejector, as a non-powered sampling method, further enhances inherent safety and deployment flexibility in high-risk oxygen-enriched scenarios. This device can detect hydrogen concentration in oxygen with a lower limit of ≤10 ppm, a response time of ≤60 seconds, and long-term maintenance-free online monitoring. It is suitable for various hydrogen energy safety scenarios such as PEM electrolyzers, hydrogen refueling stations, and oxygen-enriched process gas monitoring.

[0042] This invention has been illustrated through several specific embodiments. Those skilled in the art will understand that various modifications and equivalent substitutions can be made to this invention without departing from its scope. Furthermore, various modifications can be made to this invention for specific situations or circumstances without departing from its scope. Therefore, this invention is not limited to the specific embodiments disclosed, but should include all embodiments falling within the scope of the claims.

Claims

1. An electrochemical catalytic hydrogen concentration detection system, characterized in that, include: The gas sampling module is used to obtain hydrogen-containing sample gas from the gas pipeline being tested; A gas-water separation device, connected to the gas sampling module, is used to control the humidity of the sample gas within a predetermined range; A chemical filtration device, connected to the gas-liquid separation device, is used to remove impurity gases that are poisonous to the catalyst from the sample gas. An electrochemical electrode detection module is connected to the chemical filtration device. The electrochemical electrode detection module includes an ion exchange membrane electrode assembly with an anode and a cathode, which is used to react electrochemically with hydrogen in the sample gas and generate an electrochemical signal. The self-generating and signal processing module is electrically connected to the electrochemical electrode detection module and is used to collect the electrochemical signal and at least partially utilize the electrical energy generated by the electrochemical reaction to power itself.

2. The electrochemical catalytic hydrogen concentration detection system as described in claim 1, characterized in that, The gas sampling module includes a Venturi ejector, which performs passive gas sampling using the process gas pressure difference of the gas pipeline being measured as the driving force.

3. The electrochemical catalytic hydrogen concentration detection system as described in claim 1, characterized in that, The gas sampling module includes a Venturi ejector, which uses the pressure difference formed by the driving gas introduced into the gas pipeline to be measured as the driving force for passive gas sampling.

4. The electrochemical catalytic hydrogen concentration detection system as described in claim 3, characterized in that, The Venturi ejector is configured such that the volume ratio of the ejector gas to the driving gas is 5:1 to 20:

1.

5. The electrochemical catalytic hydrogen concentration detection system as described in claim 1, characterized in that, The gas-water separation device includes a hydrocyclone separator and a hydrophobic microporous membrane. The hydrocyclone separator uses centrifugal force to throw out droplets. The hydrophobic microporous membrane has a pore size of 0.2-1 μm and a water contact angle greater than 130° to block liquid water. The humidity of the sample gas is controlled at 30%-80% relative humidity.

6. The electrochemical catalytic hydrogen concentration detection system as described in claim 1, characterized in that, The chemical filtration device includes an activated carbon layer, a catalytic oxidation layer, and a soda lime layer, used to remove carbon monoxide, sulfides, ammonia, and volatile organic compounds from the sample gas.

7. The electrochemical catalytic hydrogen concentration detection system as described in claim 6, characterized in that, The chemical filtration device includes a bypass sampling interface for sampling and analyzing gases before and after filtration.

8. The electrochemical catalytic hydrogen concentration detection system as described in claim 1, characterized in that, The anode of the electrochemical electrode detection module includes a catalyst coating film, a gas diffusion layer, and an electrode plate, wherein the platinum loading of the catalyst coating film is 0.05-0.2 mg / cm³. 2 The gas diffusion layer is a carbon layer with a thickness of 150-250 μm. The hydroxide reaction at the anode generates an open-circuit voltage signal, and the relationship between the open-circuit voltage signal and the hydrogen concentration conforms to the Nernst equation.

9. The electrochemical catalytic hydrogen concentration detection system as described in claim 1, characterized in that, The self-generating power and signal processing module includes a DC-DC boost converter, a supercapacitor, and a signal acquisition circuit. The DC-DC boost converter boosts the voltage generated by the electrochemical reaction to the operating voltage required by the signal acquisition circuit. The supercapacitor is used to maintain short-term power supply to the signal acquisition circuit when the hydrogen concentration in the sample gas is below a preset threshold.

10. An electrochemical catalytic hydrogen concentration detection method, implemented using the system as described in any one of claims 1 to 9, characterized in that, The method includes the following steps: Sample gas is obtained from a hydrogen-containing oxygen stream using a gas sampling module; Liquid water is removed from the sample gas using a gas-liquid separator to control the relative humidity within a predetermined range; Catalyst-poisoned impurities in the sample gas are removed using a chemical filtration device; The processed sample gas is introduced into the anode side of the electrochemical electrode detection module, and the reference gas is introduced into the cathode side, generating an electrochemical signal related to the hydrogen concentration. The electrical energy generated by the electrochemical reaction is used to power the signal acquisition circuit, and the electrochemical signal is acquired to calculate the hydrogen concentration.

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