Testing device for testing sealing performance of flange and valve under pure hydrogen-doped methane condition

Abstract

The invention relates to a testing device for testing the sealing performance of a flange and a valve under the condition of pure hydrogen doped with methane, which comprises an anti-explosion sealing box, a gas inlet pipeline, a gas outlet pipeline, a circulating pipeline, a first emptying pipeline, a second emptying pipeline and a gas supplementing device, and is characterized in that the anti-explosion sealing box is provided with a door capable of being opened or closed; the air inlet pipeline and the air outlet pipeline penetrate through the two side walls of the anti-explosion sealing box respectively, one end of the air inlet pipeline and one end of the air outlet pipeline are both located in the anti-explosion sealing box, a flange or a valve to be tested is connected between one end of the air inlet pipeline and one end of the air outlet pipeline, and the circulation pipeline is connected between the other end of the air inlet pipeline and the other end of the air outlet pipeline. The gas supplementing device is connected with the other end of the gas inlet pipeline, the first emptying pipeline is connected with the other end of the gas inlet pipeline, an emptying opening is formed in the side wall of the anti-explosion sealing box, the second emptying pipeline is connected with the emptying opening, and the anti-explosion sealing box is provided with a hydrogen concentration detector. The device has the advantages that leaked gas can be effectively collected and treated, and safety accidents caused by the leaked gas are prevented.

Description

Technical Field

[0001] The invention relates to the technical field of hydrogen equipment sealing performance detection, and in particular to a test device for testing the sealing performance of flanges and valves under pure hydrogen mixed with methane conditions. Background Art

[0002] Hydrogen is a highly flammable gas that burns very quickly, and the heat and flame temperature generated during combustion are very high. The explosion limit of hydrogen is roughly between 4.0% and 75.6% (volume concentration). This means that when the volume concentration of hydrogen in the air falls within this range, it may cause an explosion once it encounters ignition conditions such as a fire source or high temperature. Hydrogen is lighter than air, and once it leaks, it will quickly diffuse upward and remain in high places such as the roof. This diffusivity makes hydrogen difficult to detect after leakage, thereby increasing the risk of explosion. In addition, hydrogen has a small molecular weight and is very easy to enter the gap between metal molecules or escape through the sealing surface. Therefore, whether the sealing performance of valves and flanges commonly used on natural gas pipelines can adapt to the operation of hydrogen pipelines and whether they are safe enough requires re-testing of sealing performance. In order to ensure the safe operation of pure hydrogen or hydrogen-blended natural gas pipelines, it is particularly important to test the sealing performance of valves and flanges used in these pipelines. Nowadays, there are still deficiencies in the special methods for testing the sealing performance of flanges and valves under pure hydrogen or hydrogen-blended conditions in national standards, industry standards and enterprise standards. There are no test methods and test devices that can be directly referenced in the relevant national standards for valves / flanges used in hydrogen environments; there are no test methods for valves and flanges in hydrogen environments in the existing valve / flange sealing performance test standards. At the same time, the existing valve / flange sealing performance test methods usually lack a recovery and orderly venting mechanism for the treatment of potential leaked gases. When facing highly flammable and explosive hydrogen gas that is prone to spontaneous combustion, the relevant detection methods have more significant safety hazards, and the environmental protection is not sufficient. In particular, if the suction gun method mentioned in GB40177 is used as a leakage rate detection method, under the premise that the accuracy can be guaranteed, for large-scale experimental equipment or equipment that needs to perform valve / flange sealing tests multiple times at the same point, the leakage and escape amount of hydrogen tested successively may cause qualitative changes due to quantitative changes, resulting in environmental and safety risks. It can be seen that it is urgent to establish a set of special detection devices that can adapt to comprehensive sealing detection of various types of valves and flanges under pure hydrogen or hydrogen-doped conditions, while ensuring the safety of personnel and the environment.

[0003] At present, pipeline transportation is still the most economical and environmentally friendly way to transport hydrogen energy over long distances and on a large scale. Pipeline transportation of hydrogen can be mainly divided into pure hydrogen transportation and natural gas mixed with hydrogen transportation. Since the molecular weight and density of hydrogen are relatively small, it may pose new challenges to the sealing of valves, flanges and other equipment on the pipeline. As hydrogen is a flammable and explosive gas, its leakage will have a serious impact on society and the environment. Therefore, it is necessary to conduct a more in-depth field study on the sealing of valves and flanges used in hydrogen transportation pipelines. In addition, the existing sealing detection lacks detection equipment specifically for valves and flanges for hydrogen pipelines. In terms of detection methods, the safety of hydrogen leakage is not considered, or leakage detection under high-pressure hydrogen environment is not involved, or the amount of hydrogen leakage of the equipment is not quantitatively detected. The sealing performance data of valves and flanges on hydrogen pipelines cannot be directly obtained. Therefore, it is necessary to build a test device for testing the sealing performance of flanges and valves under pure hydrogen mixed with methane.

[0004] Based on this, it is necessary to develop a test device for testing the sealing performance of flanges and valves under pure hydrogen-doped methane conditions to solve the above problems. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a test device for testing the sealing performance of flanges and valves under the condition of pure hydrogen mixed with methane, which effectively overcomes the defects of the prior art.

[0006] The technical solution of the present invention to solve the above technical problems is as follows:

[0007] A test device for testing the sealing performance of flanges and valves under pure hydrogen-methane conditions, comprising an explosion-proof sealed box, an air inlet pipeline, an air outlet pipeline, a circulation pipeline, a first venting pipeline, a second venting pipeline and a gas replenishing device, wherein the explosion-proof sealed box is provided with a door that can be opened or closed, the air inlet pipeline and the air outlet pipeline respectively penetrate the side walls of the explosion-proof sealed box on both sides, one end of the air inlet pipeline and the air outlet pipeline are both in the explosion-proof sealed box, a flange or valve to be tested is connected between one end of the air inlet pipeline and the air outlet pipeline, the circulation pipeline is connected between the other ends of the air inlet pipeline and the air outlet pipeline, the gas replenishing device is connected to the other end of the air inlet pipeline, the first venting pipeline is connected to the other end of the air inlet pipeline, the side wall of the explosion-proof sealed box is provided with a venting port, the second venting pipeline is connected to the venting port, and the explosion-proof sealed box is provided with a hydrogen concentration detector.

[0008] Based on the above technical solution, the present invention can also be improved as follows.

[0009] Furthermore, the air inlet pipeline and the air outlet pipeline are respectively provided with a first pressure measuring device and a first control valve.

[0010] Furthermore, the circulation pipeline is provided with a check valve, a first flow meter, a gas circulation pump and a second control valve.

[0011] Furthermore, the first vent pipeline is provided with a second pressure measuring device and a first vent valve.

[0012] Furthermore, a second vent valve is provided on the second vent pipeline.

[0013] Furthermore, the gas replenishing device includes a gas pipe and a high-pressure gas supply system, one end of the gas pipe is connected to the other end of the air intake pipeline, and the other end of the gas pipe is connected to the high-pressure gas supply system. A second flow meter and a third control valve are provided on the gas pipe.

[0014] Furthermore, the above-mentioned high-pressure gas transmission system includes a pure hydrogen tank and a natural gas tank, and the outlets of the above-mentioned pure hydrogen tank and the natural gas tank are connected to the above-mentioned gas transmission pipe through pipelines, and the pipelines are respectively provided with a fourth control valve.

[0015] Furthermore, it also includes a gas replacement pipeline. The side wall of the explosion-proof sealed box is provided with a gas replacement port. One end of the gas replacement pipeline is connected to the gas replacement port, and the other end is connected to the replacement gas tank. A fifth control valve is provided on the gas replacement pipeline.

[0016] Furthermore, it also includes a controller, which is respectively connected to the first pressure measuring device, the first control valve, the check valve, the first flow meter, the gas circulation pump, the second control valve, the second pressure measuring device, the first vent valve, the second vent valve, the second flow meter, the third control valve, the fourth control valve and the fifth control valve.

[0017] Furthermore, one end of the first venting pipeline away from the air inlet pipeline and one end of the second venting pipeline away from the explosion-proof sealing box are merged and connected to the venting torch.

[0018] The beneficial effects of the present invention are: simple and reasonable design, effective collection and treatment of leaked gas, and prevention of safety accidents caused by leaked gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of the test device for testing the sealing performance of flanges and valves under the condition of pure hydrogen mixed with methane according to the present invention;

[0020] Figure 2 It is a structural schematic diagram of another embodiment of the test device for testing the sealing performance of flanges and valves under pure hydrogen mixed with methane conditions of the present invention;

[0021] Figure 3 The structure of the explosion-proof sealing box in the test device for testing the sealing performance of flanges and valves under pure hydrogen mixed with methane is shown in the figure. Figure 1 ;

[0022] Figure 4 The structure of the explosion-proof sealing box in the test device for testing the sealing performance of flanges and valves under pure hydrogen mixed with methane is shown in the figure. Figure 2 .

[0023] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0024] 1. Explosion-proof sealed box; 2. Air inlet pipeline; 3. Air outlet pipeline; 4. Circulation pipeline; 5. First venting pipeline; 6. Second venting pipeline; 8. Gas replenishment device; 9. Hydrogen concentration detector; 20. Venting torch; 30. Gas replacement pipeline; 40. Replacement gas tank; 41. Check valve; 42. First flow meter; 43. Gas circulation pump; 44. Second control valve; 51. Second pressure measuring device; 52. First venting valve; 61. Second venting valve; 71. Flange; 72. Valve; 81. Gas pipeline; 82. Second flow meter; 83. Third control valve; 84. Pure hydrogen tank; 85. Natural gas tank; 86. Fourth control valve; 101. First pressure measuring device; 102. First control valve; 301. Fifth control valve. DETAILED DESCRIPTION

[0025] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0026] Example: Figure 1 , 2 As shown, the test device for testing the sealing performance of flanges and valves under pure hydrogen-doped methane conditions in this embodiment includes an explosion-proof sealed box 1, an air inlet pipeline 2, an air outlet pipeline 3, a circulation pipeline 4, a first venting pipeline 5, a second venting pipeline 6 and a gas replenishing device 8. The explosion-proof sealed box 1 is provided with an openable or closable door, the air inlet pipeline 2 and the air outlet pipeline 3 respectively penetrate the side walls of the explosion-proof sealed box 1 on both sides, one end of the air inlet pipeline 2 and the air outlet pipeline 3 are both in the explosion-proof sealed box 1, and the flange 71 to be tested (such as Figure 3 as shown) or valve 72 (as shown Figure 4 The above-mentioned first vent line 5 is connected to the other end of the above-mentioned inlet pipeline 2 and the outlet pipeline 3, the above-mentioned second vent line 6 is connected to the above-mentioned vent port, and the above-mentioned explosion-proof sealed box 1 is provided with a vent port on the side wall, and the above-mentioned second vent line 6 is connected to the above-mentioned vent port. The above-mentioned explosion-proof sealed box 1 is provided with a hydrogen concentration detector 9.

[0027] When the test device for testing the sealing performance of flanges and valves under the condition of pure hydrogen mixed with methane is used, the flange 71 or valve 72 to be tested is connected between the ports of the inlet pipeline 2 and the outlet pipeline 3 in the explosion-proof sealed box 1 (the connection between the flange 71 or valve 72 to be tested and the ports of the inlet pipeline 2 and the outlet pipeline 3 belongs to a conventional connection structure, which is not described here). During the process, the test pure hydrogen mixed with methane gas is transported to the inlet pipeline 2 through the gas replenishing device 8, and enters the outlet pipeline 3 after passing through the flange 71 or valve 72 to be tested, and then enters the circulation pipeline 4 through the outlet pipeline 3, and then continues to enter the inlet pipeline 2 and the outlet pipeline 3 through the circulation pipeline 4 to form a cycle. In the above process, the hydrogen concentration in the explosion-proof sealed box 1 is detected in real time by the hydrogen concentration detector 9, and the gas volume input through the gas replenishing device 8 and the gas pressure in the pipeline are measured throughout the process. After the detection is completed, the gas in the pipeline and the explosion-proof sealed box 1 is vented by opening the first venting pipeline 5 and the second venting pipeline 6. The overall structural design is simple and reasonable, which can effectively collect and process leaked gas and prevent safety accidents caused by leaked gas.

[0028] In this embodiment, the first pressure measuring device 101 and the first control valve 102 are respectively provided on the air inlet pipeline 2 and the air outlet pipeline 3. The first pressure measuring device 101 can measure the pressure at the air inlet end and the air outlet end, that is, the air pressure information at both ends of the flange 71 or the valve 72 to be measured, and the first control valve 102 can control the gas flow state of the pipeline (such as cut-off or unblocked), which is convenient and flexible to operate.

[0029] The first pressure measuring device 101 adopts a conventional pressure gauge (such as an electronic pressure gauge), and the specific model can be flexibly adapted according to actual needs. The first control valve 102 adopts a conventional shut-off valve or other control valves, and the specific model can be flexibly adapted according to actual needs.

[0030] In this embodiment, the circulation pipeline 4 is provided with a check valve 41, a first flow meter 42, a gas circulation pump 43 and a second control valve 44. The check valve 41 ensures that the airflow circulates in one direction without backflow, the first flow meter 42 can measure the fluid flow on the circulation pipeline 4, the second control valve 44 is used to control the gas flow state (such as cut-off or unblocked) of the circulation pipeline 4, and the gas circulation pump 43 can keep the gas in the pipeline flowing. The valves and flow meters and other components mentioned above can all be products of suitable models on the market.

[0031] In this embodiment, the first vent line 5 is provided with a second pressure measuring device 51 and a first vent valve 52. The second pressure measuring device 51 can measure the pressure information on the first vent line 5, and the first vent valve 52 can control the gas flow state (such as cut-off or unblocked) of the first vent line 5.

[0032] In this embodiment, a second venting valve 61 is provided on the second venting pipeline 6. The second venting valve 61 can control the gas flow state of the second venting pipeline 6 (such as cut-off or unblocked).

[0033] As a preferred embodiment, the gas replenishing device 8 includes a gas pipe 81 and a high-pressure gas transmission system, one end of the gas pipe 81 is connected to the other end of the air intake pipeline 2, and the other end of the gas pipe 81 is connected to the high-pressure gas transmission system, and a second flow meter 82 and a third control valve 83 are provided on the gas pipe 81.

[0034] In the above embodiment, pure hydrogen-doped methane gas is transported to the gas pipeline 81 through a high-pressure gas transmission system, and then enters the test pipeline composed of the gas inlet pipeline 2, the gas outlet pipeline 3, and the circulation pipeline 4 through the gas pipeline 81 (hereinafter collectively referred to as the gas circulation pipeline), and then subsequent effective detection can be carried out.

[0035] In this embodiment, the high-pressure gas transmission system includes a pure hydrogen tank 84 and a natural gas tank 85. The outlets of the pure hydrogen tank 84 and the natural gas tank 85 are connected to the gas transmission pipe 81 through pipelines, and the pipelines are respectively provided with fourth control valves 86. During the test, the pure hydrogen tank 84 and the natural gas tank 85 synchronously output hydrogen and natural gas, and the two are input at a set flow rate ratio, mixed in the gas transmission pipe 81, and then enter the test pipeline composed of the inlet pipeline 2, the outlet pipeline 3, and the circulation pipeline 4.

[0036] As a preferred embodiment, Figure 2 As shown, it also includes a gas replacement pipeline 30. The side wall of the explosion-proof sealed box 1 is provided with a gas replacement port. One end of the gas replacement pipeline 30 is connected to the gas replacement port, and the other end is connected to the replacement gas tank 40. The gas replacement pipeline 30 is provided with a fifth control valve 301.

[0037] In the above embodiment, when it is necessary to replace the gas in the pipeline, the valve at the outlet of the replacement gas tank 40 is opened, and the gas (generally nitrogen) inside it will enter the explosion-proof sealed box 1 through the gas replacement pipeline 30, and then the hydrogen-containing gas leaked in the explosion-proof sealed box 1 will be replaced through the second venting pipeline 6. Only after the replacement is completed can the explosion-proof sealed box 1 be opened to disassemble the flange 71 or valve 72 to be tested.

[0038] The following takes the static sealing test of valves as an example to illustrate the test method of the test device for flange and valve sealing performance under pure hydrogen mixed with methane conditions, as follows:

[0039] (1) Connect the valve 72 to be tested to the test device, check the hydrogen concentration in the explosion-proof sealed box 1, and open the explosion-proof sealed box 1 only if the hydrogen concentration is within the safe range. If it exceeds the safe range, the gas in the explosion-proof sealed box 1 should be vented and replaced with nitrogen;

[0040] (2) The explosion-proof sealed box 1 can be opened only when the hydrogen concentration in the explosion-proof sealed box 1 is far below the lower explosion limit, and the valve 72 to be tested is correctly connected between the inlet pipeline 2 and the outlet pipeline 3, and the valve 72 is ensured to be in the test state. When the static sealing test is performed, the valve 72 should be in a half-open state, and then the explosion-proof sealed box 1 is closed to achieve a sealed state;

[0041] (3) Close the first vent valve 52 and the second vent valve 61, and inject the test gas into the gas circulation pipeline through the gas replenishing device 8 until the test pressure is reached. After the test pressure is reached, open the gas circulation pump 43 to keep the gas in the pipeline flowing, and record the hydrogen concentration and pressure value in the explosion-proof sealing box 1 at this time.

[0042] (4) After the gas begins to circulate, if leakage occurs at the valve stem seal and valve seat seal of the valve 72, the leaked hydrogen will enter the explosion-proof sealed box 1. After the test is carried out for a specified time, the hydrogen concentration and pressure value in the explosion-proof sealed box 1 are recorded again, and the gas circulation pump 43 is turned off. The gas in the gas circulation pipeline and the explosion-proof sealed box 1 is vented and replaced with nitrogen. After both are replaced, the explosion-proof sealed box 1 can be opened to disassemble the valve 72 to be tested.

[0043] (5) The hydrogen leakage amount of the sealing test of the valve 72 in a hydrogen environment can be obtained by replacing the hydrogen concentration and pressure values ​​recorded twice and the volume of the explosion-proof sealing box 1.

[0044] Overall, it has the following technical effects:

[0045] (1) If hydrogen leakage occurs in the component to be tested (flange or valve) under specific working conditions, the hydrogen will only exist in the explosion-proof sealed box and can be safely released through the discharge pipeline (that is, two vent pipelines) without escaping to the external environment. Therefore, the test device has the safety of valve / flange sealing detection in a hydrogen environment.

[0046] (2) The test device is suitable for any type of valve / flange sealing detection method and can adapt to a variety of detection methods. The present invention does not restrict the leakage detection method and the corresponding hydrogen leakage amount or leakage rate detection method data can be selected as needed.

[0047] (3) The test device can explore the influence of multiple factors on the sealing of hydrogen-doped / pure hydrogen valve flanges; this device can not only study the quantitative influence of multiple factors such as hydrogen doping ratio, working pressure, bolt preload, rubber seal size and rubber seal material type on valve / flange leakage or leakage rate, but also can conduct leakage detection under the motion state of the valve by opening and closing the valve, and detect the internal leakage of the valve when the valve is under unilateral pressure in the stopped state, so as to comprehensively evaluate the leakage performance of valves, flanges and other seals.

[0048] As a preferred embodiment, it also includes a controller, which is respectively connected to the first pressure measuring device 101, the first control valve 102, the check valve 41, the first flow meter 42, the gas circulation pump 43, the second control valve 44, the second pressure measuring device 51, the first vent valve 52, the second vent valve 61, the second flow meter 82, the third control valve 83, the fourth control valve 86 and the fifth control valve 301.

[0049] In the above implementation scheme, a control system can be formed by connecting the above electrical components through a controller, and the operating state of the above electrical components can be controlled by the controller to realize the automatic and intelligent operation of the entire test device. Among them, the controller can adopt a PLC controller of a suitable model on the market.

[0050] In this embodiment, the end of the first venting pipeline 5 away from the air intake pipeline 2 and the end of the second venting pipeline 6 away from the explosion-proof sealed box 1 are merged and connected to the venting torch 20. The venting torch 20 is used to ignite and vent the venting gas, and the processing method is relatively simple.

[0051] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0052] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0053] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0054] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0055] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0056] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A test device for testing the sealing performance of flanges and valves under pure hydrogen mixed with methane, characterized in that: The invention comprises an explosion-proof sealed box (1), an air inlet pipeline (2), an air outlet pipeline (3), a circulation pipeline (4), a first venting pipeline (5), a second venting pipeline (6) and a gas replenishing device (8), wherein the explosion-proof sealed box (1) is provided with a door that can be opened or closed, the air inlet pipeline (2) and the air outlet pipeline (3) respectively penetrate the side walls of the explosion-proof sealed box (1), one end of each of the air inlet pipeline (2) and the air outlet pipeline (3) is located in the explosion-proof sealed box (1), and a flange (71) or a valve (72) to be tested is connected to the flange (71) or the valve (72) to be tested. The gas supply device (8) is connected to the other end of the gas inlet pipeline (2), the first venting pipeline (5) is connected to the other end of the gas inlet pipeline (2), the explosion-proof sealed box (1) is provided with a venting port on the side wall, the second venting pipeline (6) is connected to the venting port, and the explosion-proof sealed box (1) is provided with a hydrogen concentration detector (9).

2. A test device for testing the sealing performance of flanges and valves under pure hydrogen mixed with methane according to claim 1, characterized in that: The air inlet pipeline (2) and the air outlet pipeline (3) are respectively provided with a first pressure measuring device (101) and a first control valve (102).

3. A test device for testing the sealing performance of flanges and valves under pure hydrogen mixed with methane according to claim 2, characterized in that: The circulation pipeline (4) is provided with a check valve (41), a first flow meter (42), a gas circulation pump (43) and a second control valve (44).

4. A test device for testing the sealing performance of flanges and valves under pure hydrogen mixed with methane according to claim 3, characterized in that: The first venting pipeline (5) is provided with a second pressure measuring device (51) and a first venting valve (52).

5. A test device for testing the sealing performance of flanges and valves under pure hydrogen mixed with methane according to claim 4, characterized in that: The second venting pipeline (6) is provided with a second venting valve (61).

6. A test device for testing the sealing performance of flanges and valves under pure hydrogen mixed with methane according to claim 5, characterized in that: The gas replenishing device (8) comprises a gas delivery pipe (81) and a high-pressure gas delivery system, one end of the gas delivery pipe (81) is connected to the other end of the gas inlet pipeline (2), and the other end of the gas delivery pipe (81) is connected to the high-pressure gas delivery system, and the gas delivery pipe (81) is provided with a second flow meter (82) and a third control valve (83).

7. A test device for testing the sealing performance of flanges and valves under pure hydrogen mixed with methane according to claim 6, characterized in that: The high-pressure gas transmission system comprises a pure hydrogen tank (84) and a natural gas tank (85), wherein the outlets of the pure hydrogen tank (84) and the natural gas tank (85) are respectively connected to the gas transmission pipe (81) via pipelines, and the pipelines are respectively provided with fourth control valves (86).

8. A test device for testing the sealing performance of flanges and valves under pure hydrogen mixed with methane according to claim 7, characterized in that: It also comprises a gas replacement pipeline (30), a gas replacement port is provided on the side wall of the explosion-proof sealed box (1), one end of the gas replacement pipeline (30) is connected to the gas replacement port, and the other end is connected to the replacement gas tank (40), and a fifth control valve (301) is provided on the gas replacement pipeline (30).

9. A test device for testing the sealing performance of flanges and valves under pure hydrogen mixed with methane according to claim 8, characterized in that: The invention also includes a controller, which is respectively connected to the first pressure measuring device (101), the first control valve (102), the check valve (41), the first flow meter (42), the gas circulation pump (43), the second control valve (44), the second pressure measuring device (51), the first vent valve (52), the second vent valve (61), the second flow meter (82), the third control valve (83), the fourth control valve (86) and the fifth control valve (301).

10. A test device for testing the sealing performance of flanges and valves under pure hydrogen mixed with methane according to any one of claims 1 to 9, characterized in that: An end of the first venting pipeline (5) away from the air inlet pipeline (2) and an end of the second venting pipeline (6) away from the explosion-proof sealing box (1) are joined and connected to the venting torch (20).

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