High-pressure hydrogen storage container leak detection method and system based on deuterium mass spectrum

Abstract

The invention discloses a high-pressure hydrogen storage container leak detection method and system based on deuterium mass spectrometry, and belongs to the technical field of hydrogen energy storage equipment detection, and the method comprises the following steps: (1) preparing a deuterium-nitrogen mixed gas, enabling the deuterium concentration in the deuterium-nitrogen mixed gas to be 3-6%, and taking the deuterium-nitrogen mixed gas as a leak detection medium; (2) pressurizing a leak detection medium to 5-40MPa, and then filling the leak detection medium into the mixer; (3) performing leak rate detection on the mixer by adopting a helium mass spectrometer leak detector, and judging leakage by detecting an ion signal of which the mass number is 4; and (4) evaluating the sealing performance of the mixer according to a comparison result of the leakage rate obtained through detection and a preset threshold value. The deuterium-nitrogen mixed gas with low deuterium content is used as a leak detection medium, hydrogen is replaced by isotope deuterium of hydrogen to serve as the leak detection medium, interference of water on a detection result is effectively avoided, the requirement for safe use is met, the mass number of deuterium gas molecules is the same as that of helium atoms, and the leak detection efficiency is improved. The system can be directly compatible with an existing helium mass spectrometer leak detector for leak detection.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen energy storage device detection, and in particular, relates to a deuterium mass spectrometry-based high-pressure hydrogen storage container leak detection method and system. Background Art

[0002] Hydrogen is a clean energy source, and developing clean, renewable energy to replace or partially replace traditional fossil fuels has made it a research hotspot. In the industrialization of hydrogen energy, the flammability and explosiveness of hydrogen make its safe storage and transportation a key technology that requires significant development. This also places higher demands on the sealing properties of hydrogen storage containers and the corresponding nondestructive testing techniques.

[0003] Currently, non-destructive testing of hydrogen storage containers is usually carried out using helium mass spectrometry. This method can relatively quickly and sensitively detect whether the sealing of the container meets the design specifications. At the same time, combined with the absorption inspection method, it can also quickly locate the leakage point. However, helium resources are scarce and rely on imports, which is costly.

[0004] Compared to helium as a leak detection medium, hydrogen has a smaller viscosity coefficient and is more sensitive in mass spectrometry. This allows for more sensitive determination of whether the container being inspected meets design specifications and can also detect leaks in certain container materials that are only permeable to hydrogen. This makes it particularly suitable for leak detection of hydrogen storage containers, especially high-pressure hydrogen storage containers that require higher leak tightness. However, using hydrogen as a leak detection medium not only presents explosion risks and is susceptible to interference from water vapor, but also requires specialized hydrogen mass spectrometry equipment for leak detection. Therefore, using hydrogen as a leak detection medium for leak detection of high-pressure hydrogen storage containers still presents challenges in safety, high detection background, and the need to reintroduce mass spectrometer helium leak detectors capable of detecting hydrogen.

[0005] Due to the flammable and explosive nature of hydrogen in the air, in order to address the safety issues associated with using hydrogen in leak detection operations, it has been proposed to use a hydrogen-nitrogen mixture as the leak detection medium. Although this method can reduce risks, it lacks sensitivity and is incompatible with general leak detection equipment. Summary of the Invention

[0006] The purpose of the present invention is to provide a high-pressure hydrogen storage container leak detection method and system based on deuterium mass spectrometry. By adopting a deuterium-nitrogen mixed gas with a low deuterium content as the leak detection medium and using deuterium, an isotope of hydrogen, instead of hydrogen as the leak detection medium, the interference of water on the detection results is effectively avoided, thereby meeting the requirements of safe use. In addition, the mass number of deuterium gas molecules is the same as that of helium atoms, and it is directly compatible with existing helium mass spectrometers for leak detection.

[0007] To achieve the purpose of the present invention, the technical solution adopted is: A method for leak detection of a high-pressure hydrogen storage container based on deuterium mass spectrometry comprises the following steps: (1) Prepare a deuterium-nitrogen mixed gas so that the deuterium concentration in the deuterium-nitrogen mixed gas is 3% to 6%, and use the deuterium-nitrogen mixed gas as a leak detection medium; (2) Pressurize the leak detection medium to 5MPa~40MPa and then fill it into the mixer; (3) Use a helium mass spectrometer leak detector to detect the leak rate of the mixer and determine the leak by detecting the ion signal with a mass number of 4; (4) Evaluate the sealing performance of the mixer based on the comparison between the leak rate detected and the preset threshold.

[0008] Furthermore, the concentration of deuterium in the deuterium-nitrogen mixture is 4.5% to 5.5%.

[0009] Furthermore, the preparation process of the deuterium-nitrogen mixed gas includes: mixing high-purity deuterium gas and high-purity nitrogen gas in proportion, and uniformly pressurizing them in a mixer.

[0010] Furthermore, the conversion relationship between the detection leak rate and the equivalent helium leak rate is: in, Is the equivalent helium leak rate, unit: Pa·m 3 / s; is the leak rate of the leak detection medium, Pa·m 3 / s; C is a constant, and its value range is 5 to 7.

[0011] A high-pressure hydrogen storage container leak detection system based on deuterium mass spectrometry includes a booster pump, a mixer, a high-pressure leak and a helium mass spectrometer leak detector connected in sequence through a pipe system, and a nitrogen gas source and a deuterium gas source are connected in parallel to the inlet end of the booster pump through the pipe system, and a vacuum pump, a pressure relief pipe, a pressure sensor and a vacuum gauge are connected in parallel to the pipe system between the booster pump and the mixer.

[0012] Furthermore, the deuterium gas source is a deuterium gas tank, and the nitrogen gas source is a nitrogen gas tank.

[0013] Furthermore, high-pressure valves are installed on the outlet of the deuterium gas tank, the outlet of the nitrogen gas tank, the outlet of the booster pump, the inlet of the vacuum pump, the inlet of the pressure sensor, the inlet of the vacuum gauge, the inlet of the mixer and the pressure relief pipeline.

[0014] Furthermore, the mixer is a spherical container.

[0015] The beneficial effects of the present invention are: 1. By using a deuterium-nitrogen mixture with a low deuterium content as the leak detection medium, and using deuterium, an isotope of hydrogen, instead of hydrogen as the leak detection medium, the leak detection of the mixer can be carried out. This not only avoids the interference of water on the test results, but also the low-concentration deuterium-nitrogen mixture meets the requirements for safe use. At the same time, since the mass number of deuterium gas molecules is the same as that of helium atoms (both are 4), helium mass spectrometer leak detectors can be used for leak detection, which removes the limitation of detection equipment for the promotion of deuterium mass spectrometer leak detection technology.

[0016] 2. By using a deuterium-nitrogen mixture as the leak detection medium, since deuterium has a smaller viscosity coefficient and can detect leaks caused by certain container materials that are only permeable to hydrogen or deuterium, the method provided by the present invention is particularly suitable for testing the sealing of high-pressure hydrogen storage containers with higher sealing requirements.

[0017] 3. By adopting the leak detection system and leak detection method provided by the present invention, the detection sensitivity is increased by about 6 times compared with nitrogen, and hydrogen leakage detection is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings illustrate exemplary embodiments of the present invention and together with the description serve to explain the principles of the present invention. These drawings are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this specification.

[0019] Figure 1 This is a system diagram of a high-pressure hydrogen storage container leak detection system based on deuterium mass spectrometry; Figure 2 The comparison curve of deuterium and helium leak rates versus pressure; Figure 3 Figure 4 shows the variation of leakage rate with pressure under mixed gas with different deuterium nitrogen concentrations.

[0020] Markings and corresponding parts names in the accompanying drawings: 1. Deuterium gas source, 2. Nitrogen gas source, 3. Booster pump, 4. Pressure relief pipe, 5. Pressure sensor, 6. Vacuum gauge, 7. Vacuum pump, 8. Mixer, 9. High-pressure leak, 10. Helium mass spectrometer leak detector; V-1~V-7, high pressure valves. DETAILED DESCRIPTION

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It will be understood that the specific embodiments described herein are intended only to explain the relevant content and are not intended to limit the present invention. It should also be noted that, for ease of description, only portions relevant to the present invention are shown in the accompanying drawings.

[0022] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0023] like Figure 1 As shown, the present invention provides a high-pressure hydrogen storage container leak detection system based on deuterium mass spectrometry, which includes a booster pump 3, a mixer 8, a high-pressure leak hole 9 and a helium mass spectrometer leak detector 10 connected in sequence through a pipe system, and the inlet end of the booster pump 3 is connected in parallel with a nitrogen gas source 2 and a deuterium gas source 1 through a pipe system, and the pipe system between the booster pump 3 and the mixer 8 is connected in parallel with a vacuum pump 7, a pressure relief pipe 4, a pressure sensor 5 and a vacuum gauge 6.

[0024] Nitrogen source 2 and deuterium source 1 are pressurized and mixed by booster pump 3 before being fed into mixer 8, resulting in mixed gases at varying pressures. Booster pump 3 is used to raise the pressure of the mixed gas to the required detection range. During this process, pressure data is read by pressure sensor 5, and deuterium-nitrogen mixtures of varying concentrations at low deuterium content are prepared and used as the detection medium.

[0025] The vacuum pump 7 is used to evacuate the leak detection system and remove other impurity molecules in the experimental system.

[0026] The vacuum gauge 6 is used to determine the impurity gas content in the leak detection system, that is, the lower the vacuum degree, the lower the impurity gas in the system.

[0027] The pressure relief line 4 is used to relieve the pressure of the entire system after leak detection is completed.

[0028] The helium mass spectrometer leak detector 10 is used to detect leakage signals.

[0029] In this leak detection system, the mixer 8 is used to mix deuterium and nitrogen in proportion. The mixer 8 is a spherical container. In addition to the consideration of withstanding high-pressure gas, the mixer 8 also takes into account that the spherical container is more conducive to uniform mixing of gases, thereby reducing the fluctuation of detection data caused by changes in the deuterium content in the mixed gas.

[0030] In this leak detection system, the deuterium gas source 1 is a deuterium gas tank, and the nitrogen gas source 2 is a nitrogen gas tank.

[0031] In this leak detection system, the outlet of the deuterium gas tank is installed with a high-pressure valve V-1, the outlet of the nitrogen gas tank is installed with a high-pressure valve V-2, the outlet of the booster pump 3 is installed with a high-pressure valve V-3, the inlet of the pressure sensor 5 is installed with a high-pressure valve V-4, the pressure relief pipe 4 is installed with a high-pressure valve V-5, the inlet of the vacuum gauge 6 is installed with a high-pressure valve V-6, the inlet of the mixer 8 is installed with a high-pressure valve V-7, and the inlet of the vacuum pump 7 is installed with a high-pressure valve V-8. Specifically, the pressure sensor 5, the vacuum gauge 6, the pressure relief pipe 4 and the vacuum pump 7 are all connected in parallel between the high-pressure valve V-3 and the high-pressure valve V-7 through the pipeline system.

[0032] In this leak detection system, by adjusting the closing state of the high-pressure valve V-7, it presents a certain leakage rate at a given pressure (usually 1atm), and by adjusting the pressure through the booster pump 3, the leakage rate can be changed to simulate a channel-type leak in the experiment.

[0033] Based on the above leak detection system, the present invention also provides a high-pressure hydrogen storage container leak detection method based on deuterium mass spectrometry, comprising the following steps: (1) Open the high-pressure valve V-3, high-pressure valve V-4, high-pressure valve V-6, high-pressure valve V-7, and high-pressure valve V-8, and start the vacuum pump 7. The vacuum pump 7 evacuates the booster pump 3, the mixer 8, and the piping system. After the vacuuming is completed; (2) Open the high-pressure valve V-1 and the high-pressure valve V-2, and start the booster pump 3. Mix the deuterium gas and nitrogen and pressurize them to 5MPa~40MPa through the booster pump 3. Then fill them into the mixer 8 and pressurize them evenly in the mixer 8. According to the opening of the high-pressure valve V-1 and the high-pressure valve V-2, mix the high-purity deuterium gas and the high-purity nitrogen in proportion so that the deuterium concentration in the mixed gas in the mixer 8 is 3%~6%. At this time, the deuterium-nitrogen mixed gas in the mixer 8 is the leak detection medium.

[0034] (3) Close the high-pressure valves V-1, V-2, and V-7, open the high-pressure leak hole 9, use the helium mass spectrometer leak detector 10 to detect the leak rate of the mixer 8, and determine the leak by detecting the ion signal with a mass number of 4.

[0035] (4) Evaluate the sealing performance of the mixer 8 based on the comparison result between the leak rate detected and the preset threshold value.

[0036] In the present leak detection method, preferably, the concentration of deuterium in the deuterium-nitrogen mixed gas is 4.5% to 5.5%.

[0037] In this leak detection method, the conversion relationship between the detection leak rate and the equivalent helium leak rate is: in, Is the equivalent helium leak rate, unit: Pa·m 3 / s; is the leak rate of the leak detection medium, Pa·m 3 / s; C is a constant, and its value range is 5 to 7.

[0038] In this leak detection method, when the deuterium concentration in the mixed gas is 5%, the booster pump 3 pressurizes the mixed gas to 5MPa-40MPa and fills it into the mixer 8. By opening the high-pressure leak hole 9, the helium mass spectrometer leak detector 10 is used for detection. At this time, if the detected leak rate is lower than the preset threshold (e.g., 1×10 -6 If the pressure is higher than 0.05 Pa·m³ / s, the seal is judged to be qualified. For higher sensitivity requirements, mixed gas can be tested by staged pressurization.

[0039] like Figure 2 As shown, by using a helium mass spectrometer leak detector 10 to detect the same leak using deuterium and helium as leak detection media, the leak rates of the two gases change with pressure below 40 MPa. Under the same pressure, regardless of whether deuterium or helium is used as the leak detection medium, the leak rate of the same leak increases exponentially with increasing pressure, which is consistent with the relationship between the leak rate of a channel-type leak and pressure following the following formula: Q=C×p n in, Q is the leakage rate, Pa·m 3 / s; p is the gas pressure, Pa; C is a constant, m3 / (Pa n-1 s), n is a constant and dimensionless.

[0040] At the same pressure, the deuterium leak rate is significantly greater than the helium leak rate, and becomes more significant with increasing pressure. In the range of 5MPa to 40MPa, the deuterium leak rate is about 6 times that of the helium leak rate. Under the same conditions, using deuterium as a leak detection medium has higher detection sensitivity than helium.

[0041] like Figure 3 As shown in the figure, under different deuterium-nitrogen concentration mixed gases, the detected leak rate of the leak hole increases with the increase of deuterium concentration in the deuterium-nitrogen mixed gas. With the increase of pressure, the change trend is more significant, and when the leak rate is lower than 5MPa, the difference in the detected leak rate is small.

[0042] In the present invention, when using deuterium mass spectrometry for leak detection, since deuterium and helium have the same molecular weight, a helium standard leak can also be used to calibrate the helium mass spectrometer leak detector 10. Furthermore, by using deuterium, an isotope of hydrogen, instead of hydrogen as the leak detection medium, interference of water on the detection results is effectively avoided.

[0043] This invention replaces helium with a deuterium-nitrogen mixture containing a low deuterium concentration. Because deuterium has the same molecular weight as helium (mass number 4), leak detection equipment that originally used helium can be used directly. Furthermore, deuterium's chemical properties are similar to those of hydrogen, enabling the detection of defects that leak hydrogen but not helium. By controlling the deuterium concentration in the deuterium-nitrogen mixture to around 5%, safety is ensured while maintaining detection sensitivity that meets industrial requirements.

[0044] It should be understood by those skilled in the art that the above embodiments are merely for the purpose of illustrating the present invention clearly, and are not intended to limit the scope of the present invention. For those skilled in the art, other changes or modifications may be made based on the above disclosure, and these changes or modifications are still within the scope of the present invention.

Claims

1. A method for leak detection of high-pressure hydrogen storage containers based on deuterium mass spectrometry, characterized in that: The steps include: (1) Prepare a deuterium-nitrogen mixed gas so that the deuterium concentration in the deuterium-nitrogen mixed gas is 3% to 6%, and use the deuterium-nitrogen mixed gas as a leak detection medium; (2) The leak detection medium is pressurized to 5MPa to 40MPa and then charged into the mixer (8); (3) using a helium mass spectrometer leak detector (10) to detect the leak rate of the mixer (8), and judging the leak by detecting the ion signal with a mass number of 4; (4) Evaluate the sealing performance of the mixer (8) based on the comparison result of the leak rate obtained by detection with the preset threshold value.

2. The method for leak detection of high-pressure hydrogen storage containers based on deuterium mass spectrometry according to claim 1, characterized in that: The concentration of deuterium in the deuterium-nitrogen mixture is 4.5% to 5.5%.

3. The method for leak detection of high-pressure hydrogen storage containers based on deuterium mass spectrometry according to claim 1, characterized in that: The preparation process of the deuterium-nitrogen mixed gas includes: mixing high-purity deuterium gas and high-purity nitrogen gas in proportion, and uniformly pressurizing them in a mixer (8).

4. The method for leak detection of high-pressure hydrogen storage containers based on deuterium mass spectrometry according to claim 1, characterized in that: The conversion relationship between the detection leak rate and the equivalent helium leak rate is: in, Is the equivalent helium leak rate, unit: Pa·m 3 / s; is the leak rate of the leak detection medium, Pa·m 3 / s; C is a constant, and its value range is 5 to 7.

5. A high-pressure hydrogen storage container leak detection system based on deuterium mass spectrometry, characterized in that: The invention comprises a booster pump (3), a mixer (8), a high-pressure leak (9) and a helium mass spectrometer leak detector (10) which are sequentially connected through a pipe system, and a nitrogen gas source (2) and a deuterium gas source (1) are connected in parallel to the inlet end of the booster pump (3) through the pipe system, and a vacuum pump (7), a pressure relief pipe (4), a pressure sensor (5) and a vacuum gauge (6) are connected in parallel to the pipe system between the booster pump (3) and the mixer (8).

6. The high-pressure hydrogen storage container leak detection system based on deuterium mass spectrometry according to claim 5 is characterized in that: The deuterium gas source (1) is a deuterium gas tank, and the nitrogen gas source (2) is a nitrogen gas tank.

7. The high-pressure hydrogen storage container leak detection system based on deuterium mass spectrometry according to claim 6, characterized in that: High-pressure valves are installed on the outlet of the deuterium gas tank, the outlet of the nitrogen gas tank, the outlet of the booster pump (3), the inlet of the vacuum pump (7), the inlet of the pressure sensor (5), the inlet of the vacuum gauge (6), the inlet of the mixer (8) and the pressure relief pipeline (4).

8. The high-pressure hydrogen storage container leak detection system based on deuterium mass spectrometry according to claim 5, characterized in that: The mixer (8) is a spherical container.

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