A hydrogen leakage on-line detection system and method based on quadrupole mass spectrometry

Abstract

The application discloses a hydrogen leakage online detection system and method based on a quadrupole mass spectrometry technology, and belongs to the technical field of hydrogen detection. The detection system comprises an air inlet module, a dynamic dilution module, a six-way valve quantitative sampling module and a quadrupole mass spectrometry detection system, can realize rapid and sensitive quantitative detection of hydrogen, saves the use amount of gas standard substances and samples, and is green, efficient, green and energy-saving. The detection method comprises the following steps: establishing a calibration curve, and calculating the concentration value of an unknown sample according to the absolute signal intensity value of the unknown hydrogen sample. The high-concentration gas standard substance is diluted on line to obtain different concentrations, and the trace hydrogen components in the samples with different pressures in the pipeline / gas cylinder and the ambient air can be reliably quantitatively detected. The application can be used for online measurement of hydrogen components in various industrial gases in high-pressure pipelines or steel cylinders, online monitoring of hydrogen leakage in hydrogen-related places such as hydrogenation stations, and online measurement of hydrogen components in closed spaces, field exploration and the like.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen detection technology, and in particular relates to an online detection system and method for hydrogen leaks based on quadrupole mass spectrometry. Background Technology

[0002] hydrogen( Hydrogen is an elemental form of hydrogen. At room temperature and pressure, hydrogen is a colorless, tasteless, odorless, non-toxic, highly flammable, and sparingly soluble gas. It is widely used in industries such as chemical engineering, petroleum, laboratories, medical facilities, fuel cell technology, aerospace exploration, and food and pharmaceuticals. With its unique advantages such as high energy density, environmental friendliness, and high diffusivity, hydrogen is considered a potential alternative to traditional energy sources, effectively reducing carbon dioxide emissions while possessing high efficiency. Therefore, accurate monitoring of hydrogen concentration is crucial for optimizing process flows and ensuring compliance with final product specifications.

[0003] However, due to its small molecular size, explosiveness, and low reactivity, hydrogen can easily leak into the environment, causing serious casualties and property damage. Therefore, rapid and highly sensitive detection of trace amounts of hydrogen in ambient air to provide early warning before accidents occur is particularly important. But precisely because of hydrogen's small molecular weight, detecting, quantifying, and monitoring trace amounts of hydrogen is more challenging than with other gases.

[0004] Currently, hydrogen sensors are the most widely used technology for detecting hydrogen leaks. However, this sensor technology has many drawbacks: excessively long response time (>1 second), insufficient accuracy, poor repeatability, and susceptibility to interference (such as...). It has low selectivity for CO and other substances, limited service life (6-12 months), and requires high-temperature operation (requiring the use of power-consuming heating elements), etc.

[0005] Existing spectroscopic techniques, such as tunable semiconductor laser absorption spectroscopy (TDLAS) and Raman spectroscopy, have detection limits >50 ppm, which fails to meet the ideal requirements for early leak detection. Although hydrogen detection technology based on gas chromatography can achieve a detection limit <1 ppm, it has disadvantages such as a complex valve system, a large system size that is inconvenient to operate, and the need for chromatographic separation and detection of samples, which takes a long time (generally >5 min).

[0006] In summary, current detection technologies on the market suffer from problems such as short lifespan, poor selectivity, large and inconvenient system operation, long detection time, and inability to reach the ppb level detection limit. They have not yet achieved truly high-sensitivity early detection and warning of hydrogen leaks. Summary of the Invention

[0007] The application aims to provide a hydrogen leakage online detection system and method based on a quadrupole mass spectrometry technology, so as to solve the problems of short service life, poor selectivity, large system, inconvenient operation, long detection time and ppb level detection limit of the existing detection technology.

[0008] The application aims to achieve the above-mentioned purpose by the following technical solutions.

[0009] The hydrogen leakage online detection system based on the quadrupole mass spectrometry technology comprises a gas inlet module, a dynamic dilution module, a six-way valve quantitative sampling module and a quadrupole mass spectrometry detection system arranged in sequence along a flow path direction.

[0010] The six-way valve quantitative sampling module comprises a six-way valve provided with a quantitative ring with a 10 mL sampling amount.

[0011] The high-pressure gas inlet module and the ambient air gas inlet module are respectively connected with an inlet end of the second mass flow controller through pipelines, and an inlet end of the first mass flow controller is connected with dilution gas.

[0012] The quadrupole mass spectrometry detection system comprises a quartz inert capillary and a quadrupole mass spectrometry detector, a turbo molecular pump and a vortex pump arranged in sequence along the flow path direction.

[0013] Interfaces of the six-way valve are respectively connected with the dynamic dilution module, a carrier gas module and a mass flow meter.

[0014] Further, a three-way joint is arranged between the static mixer and the first mass flow controller and the second mass flow controller, and outlet ends of the first mass flow controller and the second mass flow controller are respectively connected with an inlet end of the static mixer through the three-way joint.

[0015] Further, the high-pressure gas inlet module comprises pipeline gas, a high-pressure sample bottle, a gas standard substance gas bottle and a high-pressure multi-position selection valve, the pipeline gas, the high-pressure sample bottle and the gas standard substance gas bottle are respectively connected with the high-pressure multi-position selection valve through pipelines, the high-pressure multi-position selection valve is connected with the inlet end of the second mass flow controller through a pipeline, and a first pressure reducing valve is arranged between the high-pressure multi-position selection valve and the second mass flow controller.

[0016] Further, the ambient air gas inlet module comprises ambient air, a diaphragm pump, a digital pressure gauge and a first back pressure valve in sequence, and an outlet end of the ambient air gas inlet module is located at a rear end of the first pressure reducing valve.

[0017] Furthermore, a second back pressure valve and a digital pressure gauge are provided in the flow path between the dynamic dilution module and the six-way valve.

[0018] Furthermore, both the dilution gas and the carrier gas are made of 99.9999% nitrogen, and a second pressure reducing valve is provided between the dilution gas and the first mass flow controller.

[0019] Furthermore, a T-type connector is provided between the six-way valve and the quartz inert capillary tube, one interface of which is used for venting. Heating devices are provided on the outside of the six-way valve, the metering ring, and the quartz inert capillary tube.

[0020] Furthermore, the preferred detection conditions for the quadrupole mass spectrometer are: multi-ion detection mode, molecular turbopump pump speed of 60 L / s, secondary electron multiplier (SEM) detector voltage of 1000 V, emission current of 800 μA, residence time and interval time of 160 ms and 150 ms respectively, electron energy of 70 eV, and total system pressure maintained at [value missing]. arrive Between mbar.

[0021] The temperature of the six-way valve and the metering loop is set to 100 °C to ensure that no adsorption occurs on the sample. The sampling purge time (30 s) and the injection time (30 s) are controlled by a computer program.

[0022] Carrier gas flow rate: 30 mL / min; flow rate of gaseous standard and sample: 30 mL / min.

[0023] A method for online detection of hydrogen leaks based on quadrupole mass spectrometry includes the following steps:

[0024] S1: High-purity nitrogen is used as the carrier gas, and the system operates for more than 24 hours under the set conditions;

[0025] S2: Adjust the quadrupole mass spectrometer detector and set... The scanned ion fragments M / Z (mass-to-charge ratio) = 2;

[0026] S3: Obtain hydrogen gas standard materials with different concentrations in the range of 0~200 ppm ( The response value, step S3 includes sub-steps S31-S33:

[0027] S31: 199.35 ppm was obtained by gravimetric method. Gaseous standard reference materials

[0028] S32: 199.35 ppm The gaseous standard material is mixed with dilution gas (nitrogen) and dynamic dilution module at different dilution ratios to obtain different concentrations, resulting in no less than 7 concentration points. Each concentration point is injected into the quantitative loop at least 7 times, and the signal intensity of different concentrations is obtained by injection and analysis. The signal intensity is the partial pressure value of hydrogen response, and the unit is mbar.

[0029] S33: Subtract the corresponding baseline response value from the obtained signal intensity values ​​at different concentrations to obtain the absolute signal intensity values ​​at different concentrations;

[0030] S4: Fit the least squares linear regression curve based on the different concentration values ​​in S3 and the corresponding absolute intensity signal values ​​to obtain the calibration curve, and at the same time obtain the linear regression equation: y = ax + b, where x is the absolute signal intensity value in mbar; y is the concentration value in ppm; a is the slope; and b is the intercept.

[0031] S5: According to the formula In the formula, The standard deviation of the measurements from 10 blank samples. s The slope of the calibration curve in step S4 is the same as the slope of the linear regression equation. LOD is the detection limit. The ppb level detection limit can be obtained through steps S3 to S5.

[0032] S6: The concentration of the unknown sample can be calculated by substituting the absolute signal intensity value of the unknown hydrogen sample into the linear regression equation in S4.

[0033] The beneficial effects of this invention are:

[0034] 1) The system and method proposed in this invention are different from traditional online sample injection methods. They consume less sample (only 10 mL), saving the amount of gas standard materials and samples used, and are green, efficient and energy-saving.

[0035] 2) High-concentration gaseous standards can be diluted online to obtain different concentrations. A high-precision dynamic dilution module allows for mixing with dilution gas at different dilution ratios to achieve varying concentrations. This eliminates the need for multiple bottles of gaseous standards with different concentrations, reducing costs.

[0036] 3) Sample testing is fast, with a testing cycle of less than 30 seconds per sample. The entire testing process is green and efficient.

[0037] 4) The system and method proposed in this invention are suitable not only for measuring low-concentration hydrogen content but also for measuring high-concentration hydrogen content. When measuring high-concentration hydrogen components, a Faraday detector can be selected in the quadrupole mass spectrometer.

[0038] 5) The system and method proposed in this invention can be used for online measurement of hydrogen components in high-pressure pipelines or cylinders containing industrial gases, online monitoring of hydrogen leaks in hydrogen-related locations such as hydrogen refueling stations, and online measurement of hydrogen components in scenarios such as confined spaces and field exploration. Furthermore, by adding other M / Z values ​​(mass-to-charge ratio) to the system software, simultaneous measurement of other gas components can also be achieved. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of an online hydrogen leak detection system based on quadrupole mass spectrometry technology according to the present invention;

[0040] In the diagram, 11-High-pressure sample bottle, 12-Gas standard substance cylinder, 13-High-pressure multi-position selector valve, 14-Dilution gas, 15-Diaphragm pump, 16-Digital pressure gauge, 17-First back pressure valve, 18-First pressure reducing valve, 19-Second pressure reducing valve, 2-Dynamic dilution module, 21-First mass flow controller, 22-Second mass flow controller, 23-Static mixer, 31-Six-way valve, 32-Quartz inert capillary tube, 33-Quadrupole mass spectrometer, 34-Turbomolecular pump, 35-Vortex pump, 36-T-connector, 41-Third mass flow controller, 42-Second back pressure valve, 43-Mass flow meter. Detailed Implementation

[0041] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Example 1:

[0043] like Figure 1 As shown, an online hydrogen leak detection system based on quadrupole mass spectrometry technology includes an air inlet module, a dynamic dilution module 2, a six-way valve quantitative injection module, and a quadrupole mass spectrometry detection system arranged sequentially along the flow path. The air inlet module includes a high-pressure air inlet module and an ambient air inlet module. The dynamic dilution module 2 includes a first mass flow controller 21, a second mass flow controller 22, and a static mixer 23.

[0044] The high-pressure air intake module and the ambient air intake module are respectively connected to the air intake end of the second mass flow controller 22 through pipelines, and the air intake end of the first mass flow controller 21 is connected to the dilution gas 14.

[0045] The six-way valve quantitative injection module includes a six-way valve 31, which has a quantitative loop with an injection capacity of 10 mL.

[0046] Through the above technical solution, the detection system of this application can detect gas samples at different pressures. When high-pressure gas needs to be detected, the high-pressure gas inlet module is turned on, and the high-pressure gas sample in the pipeline gas or high-pressure gas cylinder enters the first pressure reducing valve 18 through the high-pressure multi-position selection valve 13 to reduce the pressure to 0.5 MPa (0.2~0.5 MPa is acceptable), and then enters the quadrupole mass spectrometry detection system through the dynamic dilution module 2 to detect the hydrogen content.

[0047] When ambient air at normal pressure needs to be tested, the ambient air intake module is turned on, and the ambient air is pressurized to 0.3 MPa (0.2~0.5 MPa is also acceptable) by the diaphragm pump 15. The pressurization status can be monitored by the digital pressure gauge 16 to ensure that the injection pressure and flow rate of each sample are consistent. Then, the pressure is controlled and maintained by the first back pressure valve 17. The pressurized ambient air enters the quadrupole mass spectrometer detection system to detect the hydrogen content after passing through the dynamic dilution module 2 and the six-way valve quantitative injection module.

[0048] The system can introduce samples at different pressures through the high-pressure air intake module and the ambient air intake module. The detection system can reliably perform trace quantitative detection on samples at different pressures, such as pipeline gas, high-pressure gas cylinders and ambient air.

[0049] The quadrupole mass spectrometry detection system includes a quartz inert capillary 32, a quadrupole mass spectrometer 33, a turbomolecular pump 34, and a vortex pump 35 arranged sequentially along the flow path; a T-connector 36 is provided between the six-way valve 31 and the quartz inert capillary 32. Only a very small amount of sample gas (approximately 20 mL / min, depending on the specific instrument settings) enters the vacuum chamber of the mass spectrometer for detection, and the excess sample gas is vented through one port of the T-connector 36.

[0050] The turbomolecular pump and vortex pump 35 are used for vacuuming to achieve a highly efficient and stable high-vacuum environment, ensuring the normal operation of the detector. Specifically, the vortex pump 35, as the forestage pump, first reduces the gas pressure in the vacuum chamber from atmospheric pressure to the medium vacuum range; the turbomolecular pump, as the post-stage pump, further reduces the vacuum level to the ultra-high vacuum state required for operation. By transferring momentum to gas molecules through high-speed rotating blades, it reduces ion collisions, background interference, and molecular reactions, improving the accuracy and resolution of mass spectrometry analysis, shortening the vacuum build-up time, and enhancing the reliability of the system.

[0051] Furthermore, the interfaces of the six-way valve 31 are connected to the dynamic dilution module 2, the carrier gas module, and the mass flow meter 43, respectively. The carrier gas module includes a carrier gas and a third mass flow controller 41, which controls the flow rate of the carrier gas, preferably 30 mL / min. The carrier gas is 99.9999% nitrogen, free of hydrogen impurities. The mass flow meter 43 is used to monitor the sample flow rate.

[0052] Furthermore, a second back pressure valve 42 and a digital pressure gauge 16 are provided in the flow path between the dynamic dilution module 2 and the six-way valve 31 to control the injection pressure and flow rate, ensuring that the injection pressure and flow rate of each sample are consistent.

[0053] Furthermore, heating devices are provided on the outside of the six-way valve 31 and the quartz inert capillary tube 32 respectively. The quartz inert capillary tube 32 is heated to 120°C by the heating devices, and the temperature of the six-way valve 31 and the metering ring is set to 100°C (temperature control range is 30~300°C) to ensure that no adsorption occurs on the sample.

[0054] Preferably, the detection conditions for the quadrupole mass spectrometer are as follows: scanning mode is multi-ion detection mode, pumping speed of molecular turbopump is 60 L / s, secondary electron multiplier (SEM) detector voltage is 1000 V, emission current is 800 μA, residence time and interval time are 160 ms and 150 ms respectively, electron energy is 70 eV, and the total system pressure is maintained at [value missing]. arrive The quadrupole mass spectrometer's computer program controls the sampling and purging time (30 s) and the injection time (30 s), while the flow rates of the gas standard and sample vials are 30 mL / min.

[0055] Furthermore, a T-connector is provided between the static mixer 23 and the first mass flow controller 21 and the second mass flow controller 22, and the outlet ends of the first mass flow controller 21 and the second mass flow controller 22 are respectively connected to the inlet end of the static mixer 23 through the T-connector.

[0056] Through the above technical solution, when it is necessary to dilute a high-concentration gaseous standard substance cylinder 12 online to obtain different concentrations, the gaseous standard substance cylinder 12 enters the static mixer 23 through a high-pressure multi-position selector valve and a second mass flow controller 22. Meanwhile, another dilution gas 14 (99.9999% nitrogen) enters the static mixer 23 through a first mass flow controller 21. The high-concentration gaseous standard substance cylinder 12 is then diluted by the dilution gas 14 and mixed uniformly in the static mixer 23. Different concentrations can be obtained by mixing the dilution gas 14 with the high-precision dynamic dilution module 2 at different dilution ratios.

[0057] Example 2:

[0058] Based on the detection system of Example 1, an online detection method for hydrogen leakage based on quadrupole mass spectrometry includes the following steps:

[0059] S1: High-purity nitrogen is used as the carrier gas. The system is operated for more than 24 hours under set conditions to stabilize the flow path and check the airtightness of the system.

[0060] S2: Adjust the quadrupole mass spectrometer detector and set... The scanned ion fragments M / Z (mass-to-charge ratio) = 2; in this embodiment, the total pressure of the detection system is set at... mbar.

[0061] S3: Obtain hydrogen gas standard materials with different concentrations in the range of 0~200 ppm ( The response value, step S3 includes sub-steps S31-S33:

[0062] S31: 199.35 ppm was obtained by gravimetric method. Gaseous standard reference materials

[0063] S32: 199.35 ppm The gaseous standard material is mixed with dilution gas (nitrogen) and dynamic dilution module at different dilution ratios to obtain different concentrations, resulting in no less than 7 concentration points. Each concentration point is injected into the quantitative loop at least 7 times, and the signal intensity of different concentrations is obtained by injection and analysis. The signal intensity is the partial pressure value of hydrogen response, and the unit is mbar.

[0064] S33: Subtract the corresponding baseline response value from the obtained signal intensity values ​​at different concentrations to obtain the absolute signal intensity values ​​at different concentrations;

[0065] S4: Fit the least squares linear regression curve based on the different concentration values ​​in S3 and the corresponding absolute intensity signal values ​​to obtain the calibration curve, and at the same time obtain the linear regression equation: y = ax + b, where x is the absolute signal intensity value in mbar; y is the concentration value in ppm; a is the slope; and b is the intercept.

[0066] S5: According to the formula In the formula, The standard deviation of the measurements from 10 blank samples. s The slope of the calibration curve in step S4 is the same as the slope of the linear regression equation. LOD is the detection limit. The ppb level detection limit can be obtained through steps S3 to S5.

[0067] S6: The concentration of the unknown sample can be calculated by substituting the absolute signal intensity value of the unknown hydrogen sample into the linear regression equation in S4.

[0068] The experimental data for step S3 are shown in Table 1, resulting in 7 groups of samples with different concentrations.

[0069] Table 1. Seven concentration and absolute signal intensity values ​​for the calibration curve.

[0070]

[0071] The calibration curve is obtained by fitting a least-squares linear regression curve to the different concentration values ​​and corresponding absolute intensity signal values ​​of seven groups of samples. The linear regression equation is also obtained as follows:

[0072] ;

[0073] Where x is the absolute signal intensity value in mbar and y is the concentration value in ppm.

[0074] The measurement values ​​of the 10 blank samples in step S5 are shown in Table 2. The standard deviation formula is common knowledge and will not be elaborated here. The standard deviation of the 10 blank sample measurement values ​​is obtained using the standard deviation formula. for .

[0075] Table 2 Measurement data of 10 blank samples

[0076]

[0077] According to the formula In the formula, The standard deviation of the measurements from 10 blank samples. for ; s is the slope of the calibration curve in step S4, taken as... The LOD (limit of detection) was found to be 0.373 ppm.

[0078] The detection limit is 0.373 ppm = 373 ppb, which brings the detection limit down to the ppb level. Furthermore, by increasing the total pressure, the injection volume of the instrument system can be increased, thereby improving the method's detection limit.

[0079] The accuracy verification of the calibration curve in step S4 is as follows:

[0080] Using 5.056 ppm Using a gaseous standard as the analyte, the corresponding signal intensity is obtained through injection analysis, and then the absolute signal intensity value is obtained. Substituting the absolute signal intensity value into the y-value of the linear regression equation, the calibration curve calculation result is 5.190 ppm, with a relative deviation of 2.66%.

[0081] Using 9.691 ppm Using a gaseous standard as the analyte, this method was used to test the hydrogen content. The calibration curve result was 9.383 ppm, with a relative deviation of 3.18%.

[0082] Using 19.548 ppm Using a gaseous standard as the analyte, the hydrogen content was tested using this method, and the calibration curve result was 19.750 ppm with a relative deviation of 1.03%. This demonstrates that the method of this invention is accurate and reliable.

[0083] The formula for calculating the relative deviation is as follows:

[0084] ;

[0085] In the formula, b (%) represents the relative deviation. For the calibration curve calculation value, This is the certified value for the standard substance. The preferred linear range of the calibration curve is: (2.072~199.35 ppm) ).

[0086] The linear regression equation for the calibration curve in step S4 is as follows:

[0087] ;in =0.9999, The coefficient of determination ranges from 0 to 1. In the linear regression equation of this embodiment... A value close to 1 indicates that the curve fits the data well.

[0088] The aforementioned detection method enables the quadrupole mass spectrometry system to achieve unprecedented sensitivity (detection limit = 0.373 ppm), speed (response time = 0.672 seconds), high precision (%RSD = 0.27% at 199.35 ppm), excellent accuracy (relative deviation <4%), and approximately 10% expanded uncertainty (corresponding to a 5.056 ppm hydrogen sample). The system exhibits high selectivity, with no interference from other gases on the hydrogen composition. This system overcomes the limitations of traditional online analysis methods, requiring only 10 mL of sample per analysis and completing one analysis in 30 seconds, making it green and efficient. It can effectively provide real-time analysis services for hydrogen refueling stations and confined spaces. Leak detection provides detection solutions.

[0089] Furthermore, the system and method proposed in this invention are suitable not only for measuring low-concentration hydrogen content but also for measuring high-concentration hydrogen content. When measuring high-concentration hydrogen components, a Faraday detector can be selected for the quadrupole mass spectrometer.

[0090] Furthermore, by adding other M / Z values ​​(mass-to-charge ratio) to the quadrupole mass spectrometer software, it is possible to simultaneously measure other gas components, thus expanding the range of applications.

[0091] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. An online detection system for hydrogen leaks based on quadrupole mass spectrometry, characterized in that: It includes an air intake module, a dynamic dilution module (2), a six-way valve quantitative injection module and a quadrupole mass spectrometer detection system arranged sequentially along the flow path. The air intake module includes a high-pressure air intake module and an ambient air intake module. The dynamic dilution module (2) includes a first mass flow controller (21), a second mass flow controller (22) and a static mixer (23). The high-pressure air intake module and the ambient air intake module are respectively connected to the air intake end of the second mass flow controller (22) through pipelines, and the air intake end of the first mass flow controller (21) is connected to the dilution gas (14). The six-way valve quantitative injection module includes a six-way valve (31), which has a quantitative loop with an injection capacity of 10 mL; The quadrupole mass spectrometry detection system includes a quartz inert capillary (32) and a quadrupole mass spectrometer (33), a turbomolecular pump (34) and a vortex pump (35) arranged sequentially along the flow path. The interface of the six-way valve (31) is connected to the dynamic dilution module (2), the carrier gas module and the mass flow meter (43) through pipelines respectively. The carrier gas module includes carrier gas and a third mass flow controller (41) in sequence. The high-pressure air intake module includes pipeline gas, high-pressure sample bottle (11), gas standard substance cylinder (12) and high-pressure multi-position selector valve (13). The pipeline gas, high-pressure sample bottle (11) and gas standard substance cylinder (12) are respectively connected to the high-pressure multi-position selector valve (13) through pipelines. The high-pressure multi-position selector valve (13) is connected to the air intake end of the second mass flow controller (22) through pipelines. A first pressure reducing valve (18) is provided between the high-pressure multi-position selector valve (13) and the second mass flow controller (22). The ambient air intake module includes ambient air, a diaphragm pump (15), a digital pressure gauge (16), and a first back pressure valve (17) in sequence. The outlet end of the ambient air intake module is located at the rear end of the first pressure reducing valve (18).

2. The online hydrogen leak detection system based on quadrupole mass spectrometry as described in claim 1, characterized in that: A three-way connector is provided between the static mixer (23) and the first mass flow controller (21) and the second mass flow controller (22). The outlet ends of the first mass flow controller (21) and the second mass flow controller (22) are respectively connected to the inlet end of the static mixer (23) through the three-way connector.

3. The online hydrogen leak detection system based on quadrupole mass spectrometry as described in claim 1, characterized in that: A second back pressure valve (42) and a digital pressure gauge (16) are provided in the flow path between the dynamic dilution module (2) and the six-way valve (31).

4. The online hydrogen leak detection system based on quadrupole mass spectrometry as described in claim 1, characterized in that: Both the dilution gas (14) and the carrier gas are made of 99.9999% nitrogen, which is free of hydrogen impurities. A second pressure reducing valve (19) is provided between the dilution gas (14) and the first mass flow controller (21).

5. The online hydrogen leak detection system based on quadrupole mass spectrometry as described in claim 1, characterized in that: A T-connector (36) is provided between the six-way valve (31) and the quartz inert capillary tube (32). One port of the T-connector (36) is used for venting. Heating devices are provided on the outside of the six-way valve (31) and the quartz inert capillary tube (32).

6. A method for online detection of hydrogen leaks based on quadrupole mass spectrometry, the online detection system for hydrogen leaks based on quadrupole mass spectrometry as described in any one of claims 1-5, characterized in that: Includes the following steps: S1: High-purity nitrogen is used as the carrier gas, and the system operates for more than 24 hours under the set conditions; S2: Adjust the quadrupole mass spectrometer detector and set... The scanned ion fragment M / Z mass-to-charge ratio is 2; S3: Obtain hydrogen gas standard materials with different concentrations in the range of 0~200 ppm. The response value, step S3 includes sub-steps S31-S33: S31: 199.35 ppm was obtained by gravimetric method. Gaseous standard reference materials S32: 199.35 ppm The gaseous standard material is mixed with dilution gas nitrogen and dynamic dilution module at different dilution ratios to obtain different concentrations, resulting in no less than 7 concentration points. Each concentration point is continuously injected into the quantitative loop more than 7 times, and the signal intensity of different concentrations is obtained by injection and analysis. The signal intensity is the partial pressure value of hydrogen response, and the unit is mbar. S33: Subtract the corresponding baseline response value from the obtained signal intensity values ​​at different concentrations to obtain the absolute signal intensity values ​​at different concentrations; S4: Fit the least squares linear regression curve based on the different concentration values ​​in S3 and the corresponding absolute intensity signal values ​​to obtain the calibration curve, and at the same time obtain the linear regression equation: y = ax + b, where x is the absolute signal intensity value in mbar; y is the concentration value in ppm; a is the slope; and b is the intercept. S5: According to the formula In the formula, The standard deviation of the measurements from 10 blank samples. s The slope of the calibration curve in step S4 is the same as the slope of the linear regression equation. LOD is the detection limit. The ppb level detection limit can be obtained through steps S3 to S5. S6: The concentration of the unknown sample can be calculated by substituting the absolute signal intensity value of the unknown hydrogen sample into the linear regression equation in S4.

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