Low-temperature expansion joint testing apparatus and testing method

Abstract

This invention belongs to the technical field of cryogenic expansion joint testing equipment, and discloses a cryogenic expansion joint testing device and method. The cryogenic expansion joint testing device includes a container, a drive mechanism, a liquid storage tank, and a detection component. The container has a mounting base connected to the first end of the cryogenic expansion joint. The container is connected to a vacuum pump configured to evacuate the container. The output end of the drive mechanism is connected to the second end of the cryogenic expansion joint. The liquid storage tank is connected to the cryogenic expansion joint and stores a liquid cryogenic medium. When the liquid cryogenic medium is liquid helium, the detection component is configured to detect the presence of helium at the outlet of the vacuum pump during the expansion and contraction of the cryogenic expansion joint. When the liquid cryogenic medium is liquid nitrogen, after the cryogenic expansion joint reaches a preset number of expansion and contraction cycles, the cryogenic expansion joint is connected to a helium source, and the detection component is configured to detect the presence of helium at the outlet of the vacuum pump. The cryogenic expansion joint testing device improves the reliability and accuracy of the test results.

Description

Technical Field

[0001] This invention relates to the field of low-temperature expansion joint testing equipment, and more particularly to a low-temperature expansion joint testing device and testing method. Background Technology

[0002] The transport of cryogenic fluids such as liquid hydrogen and liquid helium requires the use of cryogenic expansion joints to compensate for the cold contraction of the transport pipeline. The reliability of cryogenic expansion joints is crucial to the transport pipeline.

[0003] Currently, factory testing of cryogenic expansion joints typically involves performing expansion life tests at room temperature. However, because the fatigue characteristics of cryogenic expansion joint materials differ significantly between low-temperature and room-temperature conditions, room-temperature test results cannot accurately reflect their actual service life under low-temperature conditions. Related technologies for testing the low-temperature performance of cryogenic expansion joints usually involve multiple immersions and reheating in a liquid cryogenic medium, followed by leak testing. These testing methods can only verify that the cryogenic expansion joint has the ability to withstand low temperatures; they cannot effectively assess the reliability and service life of cryogenic expansion joints under long-term use in low-temperature environments.

[0004] Therefore, there is an urgent need for a low-temperature expansion joint testing device and method to solve the above-mentioned technical problems. Summary of the Invention

[0005] One object of the present invention is to provide a low-temperature expansion joint testing device, which can perform expansion and contraction performance and life tests on low-temperature expansion joints in a low-temperature environment, thereby improving the reliability and accuracy of the test results.

[0006] To achieve this objective, the present invention adopts the following technical solution: The low-temperature expansion joint testing device includes: A container, wherein a mounting base is provided inside the container, the mounting base is connected to the first end of a cryogenic expansion joint, the container is connected to a vacuum pump, and the vacuum pump is configured to evacuate the container. A drive mechanism, the output end of which is connected to the second end of the cryogenic expansion joint, the drive mechanism being configured to drive the cryogenic expansion joint to perform telescopic movement; A liquid storage tank is connected to the cryogenic expansion joint so that the liquid level in the cryogenic expansion joint is equal to the liquid level in the liquid storage tank, and the liquid storage tank is configured to store a liquid cryogenic medium. The detection component, when the liquid cryogenic medium is liquid helium, is configured to detect whether helium is present at the outlet of the vacuum pump during the expansion and contraction of the cryogenic expansion joint; When the liquid cryogenic medium is liquid nitrogen, after the cryogenic expansion joint reaches a preset number of expansions and contractions, the cryogenic expansion joint is connected to the helium source, and the detection component is configured to detect whether there is helium at the outlet of the vacuum pump.

[0007] Optionally, the liquid storage tank is provided with a first outlet and a first inlet, the cryogenic expansion joint is provided with a first interface and a second interface, and the cryogenic expansion joint testing device further includes: A first connecting pipe, one end of which is connected to the first outlet and the other end of which is connected to the first interface; The second connecting pipe has one end connected to the first inlet and the other end connected to the second interface; A first valve is disposed on the first connecting pipe, and the first valve is configured to connect or disconnect the first outlet and the first interface. A second valve is disposed on the second connecting pipe, and the second valve is configured to connect or disconnect the first inlet and the second interface.

[0008] Optionally, the liquid storage tank further includes a liquid inlet and a liquid inlet valve, wherein the liquid inlet valve is disposed at the liquid inlet, and the liquid inlet is used to replenish the liquid cryogenic medium into the liquid storage tank.

[0009] Optionally, the storage tank is equipped with a heater, which is configured to heat the liquid cryogenic medium inside the storage tank; And / or, the liquid storage tank is further provided with a first vent, and a vent valve is provided at the first vent.

[0010] Optionally, the drive mechanism includes: A first driving member, the output end of which is connected to the second end of the cryogenic expansion joint, the first driving member being configured to drive the cryogenic expansion joint to perform telescopic movement; Alternatively, the driving mechanism includes a second driving member and a transmission assembly. The second driving member is connected to the input end of the transmission assembly, and the output end of the transmission assembly is connected to the second end of the cryogenic expansion joint. The second driving member drives the cryogenic expansion joint to perform telescopic movement through the transmission assembly.

[0011] Optionally, the cryogenic expansion joint testing device further includes: A third connecting pipe and a third valve, wherein the third valve is disposed on the third connecting pipe, one end of the third connecting pipe is connected to the cryogenic expansion joint, and the other end is connected to a nitrogen source; The fourth connecting pipe and the fourth valve are provided. One end of the fourth connecting pipe is connected to the first interface, and the other end is provided with a second outlet. The fourth valve is provided on the fourth connecting pipe.

[0012] Optionally, the cryogenic expansion joint testing device further includes: The fifth connecting tube has one end connected to the second interface and the other end connected to a helium source; A fifth valve is provided on the fifth connecting pipe. When both the first valve and the second valve are closed, the fifth valve is configured to connect or disconnect the cryogenic expansion joint from the helium source.

[0013] Optionally, the cryogenic expansion joint testing device further includes a safety valve, which is connected to the first connecting pipe and is configured to open when the pressure in the first connecting pipe is greater than or equal to a pressure threshold.

[0014] Another objective of this invention is to provide a method for testing low-temperature expansion joints. Using the aforementioned low-temperature expansion joint testing device, the expansion and contraction performance and lifespan of low-temperature expansion joints can be tested in a low-temperature environment, thereby improving the accuracy and reliability of the test results.

[0015] To achieve this objective, the present invention adopts the following technical solution: The low-temperature expansion joint testing method, performed using the aforementioned low-temperature expansion joint testing device, includes: The cryogenic expansion joint is placed in the container, with its first end connected to the mounting base and its second end connected to the output end of the drive mechanism. The container is connected to the vacuum pump. A liquid cryogenic medium is introduced into the storage tank, and the storage tank is connected to the cryogenic expansion joint so that the liquid level in the cryogenic expansion joint is equal to the liquid level in the storage tank. Start the vacuum pump and the drive mechanism to evacuate the container and drive the cryogenic expansion joint to perform axial reciprocating telescopic motion. When the liquid cryogenic medium is liquid helium, the detection component is configured to detect whether there is helium gas at the outlet of the vacuum pump during the expansion and contraction of the cryogenic expansion joint, so as to determine whether the cryogenic expansion joint is damaged. When the liquid cryogenic medium is liquid nitrogen, after the cryogenic expansion joint reaches a preset number of tests, the cryogenic expansion joint is connected to a helium source, and the detection component detects whether there is helium at the outlet of the vacuum pump to determine whether the cryogenic expansion joint is damaged.

[0016] Optionally, after the cryogenic expansion joint breaks or after the preset number of expansions and contractions is reached, the following further steps are taken: The liquid cryogenic medium inside the cryogenic expansion joint is discharged, and room temperature nitrogen gas is introduced into the cryogenic expansion joint; Turn off the vacuum pump and introduce air into the container to restore the container to normal pressure. The test is then complete.

[0017] Beneficial effects: The cryogenic expansion joint testing device provided by this invention connects the cryogenic expansion joint to a storage tank containing a liquid cryogenic medium. The liquid level in the cryogenic expansion joint is kept consistent with the liquid level in the storage tank, ensuring the cryogenic expansion joint is in a cryogenic environment. Simultaneously, the cryogenic expansion joint is placed in a vacuum container to reduce the impact of external heat exchange on the expansion joint and maintain its temperature stability. A drive mechanism drives the cryogenic expansion joint to repeatedly expand and contract. When the liquid cryogenic medium is liquid helium, real-time leak detection can be performed by checking the presence of helium at the vacuum pump outlet during the expansion and contraction process. When the liquid cryogenic medium is liquid nitrogen, helium can be introduced into the cryogenic expansion joint after it has reached a preset number of expansion and contraction cycles, and leak detection can be performed by checking the presence of helium at the vacuum pump outlet. This allows for real-time or phased evaluation of the cryogenic expansion joint's expansion performance and service life in a cryogenic environment, improving the reliability and accuracy of the test results.

[0018] The low-temperature expansion joint testing method provided by this invention uses the aforementioned low-temperature expansion joint testing device to perform expansion and contraction life testing on low-temperature expansion joints in a low-temperature environment, which can improve the reliability and accuracy of the test results. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a low-temperature expansion joint testing device provided in a specific embodiment of the present invention.

[0020] In the picture: 10. Low-temperature expansion joint; 100. Container; 110. Mounting base; 200. Drive mechanism; 300. Storage tank; 310. Replenishment valve; 320. Heater; 330. Vent valve; 410. First connecting pipe; 411. First valve; 420. Second connecting pipe; 421. Second valve; 430. Third connecting pipe; 431. Third valve; 450. Fifth connecting pipe; 451. Fifth valve; 440. Fourth connecting pipe; 441. Fourth valve; 460. Sixth valve; 470. Safety valve. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0022] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0024] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0025] Example 1 This embodiment provides a low-temperature expansion joint testing device, such as... Figure 1 As shown, the cryogenic expansion joint testing device includes a container 100, a drive mechanism 200, a liquid storage tank 300, and a detection component. The container 100 has a mounting base 110 connected to the first end of the cryogenic expansion joint 10. The container 100 is connected to a vacuum pump configured to evacuate the container 100. The output end of the drive mechanism 200 is connected to the second end of the cryogenic expansion joint 10, and the drive mechanism 200 is configured to drive the cryogenic expansion joint 10 to perform telescoping motion. The liquid storage tank 300 is connected to the cryogenic expansion joint 10 to ensure that the liquid level in the cryogenic expansion joint 10 is equal to the liquid level in the liquid storage tank 300. The liquid storage tank 300 is configured to store a liquid cryogenic medium. When the liquid cryogenic medium is liquid helium, the detection component is configured to detect whether helium gas is present at the outlet of the vacuum pump during the telescoping process of the cryogenic expansion joint 10, thereby evaluating the telescoping performance and service life of the cryogenic expansion joint 10 in a cryogenic environment in real time, improving the reliability and accuracy of the test results.

[0026] Optionally, by placing the cryogenic expansion joint 10 inside the container 100 and using a vacuum pump to evacuate the container 100, the influence of external heat exchange on the temperature of the cryogenic expansion joint 10 is reduced, which helps maintain the temperature stability of the cryogenic expansion joint 10. In this embodiment, the container 100 is connected to the vacuum pump through a vacuum tube, and a sixth valve 460 is provided on the vacuum tube. The sixth valve 460 is used to connect or disconnect the container 100 from the vacuum pump.

[0027] like Figure 1 As shown, the liquid storage tank 300 is provided with a first outlet and a first inlet, the cryogenic expansion joint 10 is provided with a first interface and a second interface, and the cryogenic expansion joint testing device also includes a first connecting pipe 410, a second connecting pipe 420, a first valve 411 and a second valve 421. One end of the first connecting pipe 410 is connected to the first outlet and the other end is connected to the first interface; one end of the second connecting pipe 420 is connected to the first inlet and the other end is connected to the second interface; the first valve 411 is provided on the first connecting pipe 410 and is configured to connect or disconnect the first outlet and the first interface; the second valve 421 is provided on the second connecting pipe 420 and is configured to connect or disconnect the first inlet and the second interface. When both the first valve 411 and the second valve 421 are open, the bottom of the storage tank 300 is connected to the bottom of the cryogenic expansion joint 10, and the top of the cryogenic expansion joint 10 is connected to the top of the storage tank 300. Utilizing the principle of communicating vessels, the liquid level inside the cryogenic expansion joint 10 is kept consistent with the liquid level inside the storage tank 300. Therefore, by controlling the liquid level inside the storage tank 300, the liquid level inside the cryogenic expansion joint 10 can be controlled. Due to the large volume of the storage tank 300, the liquid level inside the cryogenic expansion joint 10 can be relatively stable, maintaining the cryogenic expansion joint 10 in a cryogenic environment for a long time and improving the reliability of the test results. In this embodiment, the liquid cryogenic medium is liquid helium; therefore, the temperature of the cryogenic expansion joint 10 during the test is approximately 4.5K, or about -268.6℃.

[0028] Optionally, the first connecting pipe 410 is provided with a first flexible section at the end near the first interface, and the second connecting pipe 420 is provided with a second flexible section at the end near the second interface, so as to ensure that the cryogenic expansion joint 10 can smoothly complete the expansion and contraction.

[0029] like Figure 1 As shown, the storage tank 300 also includes a replenishment port and a replenishment valve 310. The replenishment valve 310 is located at the replenishment port, which is used to replenish the storage tank 300 with liquid cryogenic medium. Since the cryogenic expansion joint 10 is connected to the storage tank 300, replenishing the storage tank 300 with liquid cryogenic medium ensures that the liquid level in the cryogenic expansion joint 10 is maintained at the top of the cryogenic expansion joint 10, ensuring that the entire cryogenic expansion joint 10 is in a cryogenic environment, thus improving the reliability of the test results.

[0030] like Figure 1 As shown, a heater 320 is provided inside the liquid storage tank 300, which is configured to heat the liquid cryogenic medium inside the liquid storage tank 300; and / or, the liquid storage tank 300 is also provided with a first vent, at which an vent valve 330 is provided. The pressure inside the liquid storage tank 300 can be controlled by the heater 320 and the vent valve 330, ensuring the pressure inside the liquid storage tank 300 is stable, thereby improving the accuracy and reliability of the test results.

[0031] like Figure 1 As shown, the cryogenic expansion joint testing device also includes a third connecting pipe 430, a third valve 431, a fourth connecting pipe 440, and a fourth valve 441. The third valve 431 is disposed on the third connecting pipe 430, one end of which is connected to the cryogenic expansion joint 10, and the other end is connected to a nitrogen source. One end of the fourth connecting pipe 440 is connected to the first interface, and the other end has a second outlet. The fourth valve 441 is disposed on the fourth connecting pipe 440. After the test is completed, the first valve 411 and the second valve 421 are closed to disconnect the cryogenic expansion joint 10 from the liquid storage tank 300. Then, the fourth valve 441 is opened to discharge the liquid cryogenic medium in the cryogenic expansion joint 10. Then, the third valve 431 is opened to connect the cryogenic expansion joint 10 to the nitrogen source. Heating the cryogenic expansion joint 10 with room temperature nitrogen can restore the cryogenic expansion joint 10 to room temperature, facilitating subsequent removal of the cryogenic expansion joint 10. In this embodiment, the nitrogen source is a nitrogen tank.

[0032] Optionally, the drive mechanism 200 includes a first drive member, the output end of which is connected to the second end of the cryogenic expansion joint 10. The first drive member is configured to drive the cryogenic expansion joint 10 to perform telescopic movement. The direct connection between the first drive member and the cryogenic expansion joint 10 simplifies the transmission path and improves transmission efficiency. In this embodiment, the first drive member is a drive cylinder. Drive cylinders have a fast response speed and can precisely control the telescopic frequency and movement of the cryogenic expansion joint 10, improving the accuracy of the detection results.

[0033] In other embodiments, the drive mechanism 200 includes a second drive member and a transmission assembly. The second drive member is connected to the input end of the transmission assembly, and the output end of the transmission assembly is connected to the second end of the cryogenic expansion joint 10. The second drive member drives the cryogenic expansion joint 10 to perform telescopic movement through the transmission assembly. By setting the transmission assembly, the arrangement position of the second drive member can be flexibly adjusted according to test requirements.

[0034] Optionally, the second driving component is a drive motor, and the transmission assembly is a lead screw and nut assembly or a gear and rack assembly. The drive motor drives the cryogenic expansion joint 10 to perform telescopic movement through the lead screw and nut assembly and the gear and rack assembly. The lead screw and nut assembly and the gear and rack assembly are existing technologies, and their specific structures will not be described in detail.

[0035] Optionally, the detection component is a helium leak detector suction gun, which can quickly detect helium leaks by drawing samples from the outlet of the vacuum generator.

[0036] Example 2 This embodiment provides a cryogenic expansion joint testing device, which is basically the same as Embodiment 1, except that the liquid cryogenic medium is liquid nitrogen. After the cryogenic expansion joint 10 reaches a preset number of expansion and contraction cycles, the cryogenic expansion joint 10 is connected to a helium source. The detection component is configured to detect whether helium is present at the outlet of the vacuum pump, thereby enabling the phased evaluation of the expansion and contraction performance and service life of the cryogenic expansion joint 10 in a cryogenic environment, and improving the reliability and accuracy of the test results.

[0037] like Figure 1 As shown, the cryogenic expansion joint testing device also includes a fifth connecting pipe 450 and a fifth valve 451. One end of the fifth connecting pipe 450 is connected to the second interface, and the other end is connected to a helium source. The fifth valve 451 is disposed on the fifth connecting pipe 450. When both the first valve 411 and the second valve 421 are closed, the fifth valve 451 is configured to connect or disconnect the cryogenic expansion joint 10 from the helium source. Thus, after the cryogenic expansion joint 10 reaches a preset number of expansion and contraction cycles, the first valve 411 and the second valve 421 are closed, and the fifth valve 451 is opened, connecting the cryogenic expansion joint 10 to the helium source. Simultaneously, the pressure inside the cryogenic expansion joint 10 can be controlled through the fourth valve 441. If the cryogenic expansion joint 10 is damaged, the detection component can detect helium at the outlet of the vacuum pump. In this embodiment, the helium source can be a helium cylinder, thus providing a stable helium source for the cryogenic expansion joint 10.

[0038] Alternatively, when the cryogenic medium is liquid nitrogen, the temperature of the cryogenic expansion joint 10 is approximately 77 K, roughly -196 °C. Compared to liquid helium, liquid nitrogen is less expensive, which can further reduce testing costs.

[0039] like Figure 1 As shown, the low-temperature expansion joint testing device also includes a safety valve 470, which is connected to the first connecting pipe 410. The safety valve 470 is configured to open when the pressure in the first connecting pipe 410 is greater than or equal to a pressure threshold, thereby improving the safety of the test.

[0040] In this embodiment, the safety valve 470 is connected to the first connecting pipe 410 via the fourth connecting pipe 440. This configuration allows for pressure relief in the first connecting pipe 410 if the pressure is greater than or equal to a pressure threshold when the first valve 411 and the second valve 421 are open and all other valves are closed, thus improving test safety. Furthermore, when the first valve 411 and the second valve 421 are both closed, and the fifth valve 451 is open and helium is introduced into the cryogenic expansion joint 10 via the fifth connecting pipe 450, the safety valve 470 can limit the pressure during the filling process, thereby improving test safety.

[0041] like Figure 1 As shown, the first connecting pipe 410 is provided with a first branch interface, which is located between the outlet of the first valve 411 and the first interface. The second connecting pipe 420 is provided with a second branch interface, which is located between the inlet of the second valve 421 and the second interface. The end of the third connecting pipe 430 away from the third valve 431 is connected to the first branch interface. The fourth connecting pipe 440 is connected to the first branch interface. The third connecting pipe 430 is provided with a third branch interface, which is located between the outlet of the third valve 431 and the second branch interface. The end of the fifth connecting pipe 450 away from the fifth valve 451 is connected to the third branch interface, which facilitates the layout and installation of the pipeline and improves the convenience of installation.

[0042] Example 3 This embodiment provides a method for testing low-temperature expansion joints, which is performed using the low-temperature expansion joint testing device described in Embodiment 1 or Embodiment 2 above. The low-temperature expansion joint testing method includes: The cryogenic expansion joint 10 is placed in the container 100. The first end of the cryogenic expansion joint 10 is connected to the mounting base 110, and the second end is connected to the output end of the drive mechanism 200. The container 100 is connected to the vacuum pump. Liquid cryogenic medium is introduced into the storage tank 300, and the storage tank 300 is connected to the cryogenic expansion joint 10 so that the liquid level in the cryogenic expansion joint 10 is equal to the liquid level in the storage tank 300. Start the vacuum pump and drive mechanism 200 to evacuate the container 100 and drive the cryogenic expansion joint 10 to perform axial reciprocating telescopic motion. When the liquid cryogenic medium is liquid helium, the detection component is configured to detect whether there is helium gas at the outlet of the vacuum pump during the expansion and contraction of the cryogenic expansion joint 10, so as to determine whether the cryogenic expansion joint 10 is damaged. When the liquid cryogenic medium is liquid nitrogen, after the cryogenic expansion joint 10 reaches the preset number of tests, the cryogenic expansion joint 10 is connected to the helium source, and the detection component detects whether there is helium at the outlet of the vacuum pump to determine whether the cryogenic expansion joint 10 is damaged.

[0043] This low-temperature expansion joint testing method uses the aforementioned low-temperature expansion joint testing device to perform expansion and contraction life testing on the low-temperature expansion joint 10 in a low-temperature environment, which can improve the reliability and accuracy of the test results.

[0044] Optionally, after the cryogenic expansion joint 10 breaks or after reaching a preset number of expansion and contraction cycles, the following further applies: The liquid cryogenic medium inside the cryogenic expansion joint 10 is discharged, and room temperature nitrogen gas is introduced into the cryogenic expansion joint 10 to restore the temperature of the cryogenic expansion joint 10 to room temperature. Turn off the vacuum pump and introduce air into container 100 to restore the pressure inside container 100 to normal. The test is then complete. This setup improves the standardization and safety of the testing process.

[0045] For example, the specific test steps of the test method for the low-temperature expansion joint 10 are roughly as follows: Step 1: Open the replenishment valve 310 to replenish the liquid in the storage tank 300, vent the air valve 330 and control the pressure inside the storage tank 300 to maintain the pressure in the storage tank 300 near the design pressure of the cryogenic expansion joint 10, and maintain the liquid level inside the cryogenic expansion joint 10 near the top of the corrugated section of the cryogenic expansion joint 10; open the sixth valve 460 to evacuate the container 100 to prevent excessive heat leakage from the cryogenic expansion joint 10, and keep the other valves closed.

[0046] Step 2: Open the first valve 411 and the second valve 421. At this time, the liquid helium in the storage tank 300 enters the cryogenic expansion joint 10 through the bottom first connecting pipe 410. After the liquid vaporizes, it returns to the storage tank 300 through the top second connecting pipe 420. The replenishment valve 310 controls the liquid level, and the exhaust valve 330 controls the pressure. After the liquid level and pressure in the storage tank 300 are stable, the internal pressure of the cryogenic expansion joint 10 is the design pressure of the cryogenic expansion joint 10, and the temperature is the phase transition temperature of liquid helium / liquid nitrogen.

[0047] Step 3: If the liquid tank 300 contains liquid helium, the drive mechanism 200 drives the cryogenic expansion joint 10 to move up and down according to the designed extension and retraction amount. A helium leak detector suction gun is fixed to the outlet of the vacuum pump to monitor whether there is helium at the outlet of the vacuum pump. If helium is present, the cryogenic expansion joint 10 has been damaged. If no helium is present, the process can continue until the required number of extension and retraction cycles is reached.

[0048] If the tank contains liquid nitrogen, the drive mechanism 200 drives the cryogenic expansion joint 10 to move up and down according to its designed extension and retraction. After a certain number of times, such as 500 times, the first valve 411 and the second valve 421 are closed, the fourth valve 441 is used to control the internal pressure of the cryogenic expansion joint 10, the fifth valve 451 is opened, and helium gas is introduced into the cryogenic expansion joint 10. A helium leak detector is fixed to the outlet of the vacuum pump to monitor whether there is helium gas at the outlet of the vacuum pump. If helium gas is present, the cryogenic expansion joint 10 has been damaged. If no helium gas is present, the fifth valve 451 and the fourth valve 441 are closed, the first valve 411 and the second valve 421 are opened, and the process is repeated. This process is repeated every certain number of times to determine the range in which the cryogenic expansion joint 10 was damaged.

[0049] Step 4: After the cryogenic expansion joint 10 is damaged or reaches the required number of tests, it needs to be restored to room temperature to facilitate its removal. At this time, close the first valve 411 and the second valve 421, shut down the drive mechanism 200, and open the fourth valve 441 to allow liquid nitrogen / liquid helium to drain from it. Then, open the third valve 431 and heat the cryogenic expansion joint 10 with room temperature nitrogen until it reaches room temperature. Finally, turn off the vacuum pump connected to the container 100 and release air into the container 100 to restore it to atmospheric pressure, thus ending the test.

[0050] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A low-temperature expansion joint testing device, characterized in that, include: A container (100) is provided with a mounting base (110) inside the container (100), the mounting base (110) is connected to the first end of a cryogenic expansion joint (10), the container (100) is connected to a vacuum pump, and the vacuum pump is configured to evacuate the container (100). A drive mechanism (200) is provided, the output end of which is connected to the second end of the cryogenic expansion joint (10), and the drive mechanism (200) is configured to drive the cryogenic expansion joint (10) to perform telescopic movement. A liquid storage tank (300) is connected to the cryogenic expansion joint (10) so that the liquid level in the cryogenic expansion joint (10) is equal to the liquid level in the liquid storage tank (300), and the liquid storage tank (300) is configured to store a liquid cryogenic medium. The detection component is configured to detect whether helium is present at the outlet of the vacuum pump during the expansion and contraction of the cryogenic expansion joint (10) when the liquid cryogenic medium is liquid helium. When the liquid cryogenic medium is liquid nitrogen, after the cryogenic expansion joint (10) reaches a preset number of expansions and contractions, the cryogenic expansion joint (10) is connected to the helium source, and the detection component is configured to detect whether there is helium at the outlet of the vacuum pump.

2. The low-temperature expansion joint testing device according to claim 1, characterized in that, The liquid storage tank (300) is provided with a first outlet and a first inlet, the cryogenic expansion joint (10) is provided with a first interface and a second interface, and the cryogenic expansion joint testing device further includes: The first connecting pipe (410) has one end connected to the first outlet and the other end connected to the first interface; The second connecting pipe (420) has one end connected to the first inlet and the other end connected to the second interface; A first valve (411) is disposed on the first connecting pipe (410), and the first valve (411) is configured to connect or disconnect the first outlet and the first interface; A second valve (421) is disposed on the second connecting pipe (420), and the second valve (421) is configured to connect or disconnect the first inlet and the second interface.

3. The low-temperature expansion joint testing device according to claim 1, characterized in that, The liquid storage tank (300) also includes a liquid inlet and a liquid inlet valve (310). The liquid inlet valve (310) is located at the liquid inlet and is used to replenish the liquid cryogenic medium into the liquid storage tank (300).

4. The low-temperature expansion joint testing device according to claim 1, characterized in that, The storage tank (300) is equipped with a heater (320), which is configured to heat the liquid cryogenic medium in the storage tank (300); And / or, the liquid storage tank (300) is further provided with a first vent, and a vent valve (330) is provided at the first vent.

5. The low-temperature expansion joint testing device according to claim 1, characterized in that, The drive mechanism (200) includes: A first driving member, the output end of which is connected to the second end of the cryogenic expansion joint (10), the first driving member being configured to drive the cryogenic expansion joint (10) to perform telescopic movement; Alternatively, the drive mechanism (200) includes a second drive member and a transmission assembly. The second drive member is connected to the input end of the transmission assembly, and the output end of the transmission assembly is connected to the second end of the cryogenic expansion member. The second drive member drives the cryogenic expansion joint (10) to perform telescopic movement through the transmission assembly.

6. The low-temperature expansion joint testing device according to claim 2, characterized in that, The low-temperature expansion joint testing device also includes: The third connecting pipe (430) and the third valve (431) are provided on the third connecting pipe (430). One end of the third connecting pipe (430) is connected to the cryogenic expansion joint (10), and the other end is connected to the nitrogen source. The fourth connecting pipe (440) and the fourth valve (441) are provided. One end of the fourth connecting pipe (440) is connected to the first interface, and the other end is provided with a second outlet. The fourth valve (441) is provided on the fourth connecting pipe (440).

7. The low-temperature expansion joint testing device according to claim 6, characterized in that, The low-temperature expansion joint testing device also includes: The fifth connecting tube (450) has one end connected to the second interface and the other end connected to a helium source; The fifth valve (451) is disposed on the fifth connecting pipe (450). When the first valve (411) and the second valve (421) are both closed, the fifth valve (451) is configured to connect or disconnect the cryogenic expansion joint (10) from the helium source.

8. The low-temperature expansion joint testing device according to claim 7, characterized in that, The low-temperature expansion joint testing device also includes a safety valve (470), which is connected to the first connecting pipe (410) and is configured to open when the pressure in the first connecting pipe (410) is greater than or equal to a pressure threshold.

9. A method for testing low-temperature expansion joints, performed using the low-temperature expansion joint testing apparatus as described in any one of claims 1-8, characterized in that, The low-temperature expansion joint testing method includes: The cryogenic expansion joint (10) is placed in the container (100), the first end of the cryogenic expansion joint (10) is connected to the mounting base (110), the second end is connected to the output end of the drive mechanism (200), and the container (100) is connected to the vacuum pump. A liquid cryogenic medium is introduced into the storage tank (300), and the storage tank (300) is connected to the cryogenic expansion joint (10) so that the liquid level in the cryogenic expansion joint (10) is equal to the liquid level in the storage tank (300); Start the vacuum pump and the drive mechanism (200) to evacuate the container (100) and drive the cryogenic expansion joint (10) to perform axial reciprocating telescopic motion; When the liquid cryogenic medium is liquid helium, the detection component is configured to detect whether there is helium at the outlet of the vacuum pump during the expansion and contraction of the cryogenic expansion joint (10) in order to determine whether the cryogenic expansion joint (10) is damaged. When the liquid cryogenic medium is liquid nitrogen, after the cryogenic expansion joint (10) reaches the preset number of tests, the cryogenic expansion joint (10) is connected to the helium source, and the detection component detects whether there is helium at the outlet of the vacuum pump to determine whether the cryogenic expansion joint (10) is damaged.

10. The method for testing low-temperature expansion joints according to claim 9, characterized in that, After the cryogenic expansion joint (10) breaks or after the preset number of expansions and contractions is reached, the following steps are also included: The liquid cryogenic medium inside the cryogenic expansion joint (10) is discharged, and room temperature nitrogen gas is introduced into the cryogenic expansion joint (10); Turn off the vacuum pump and introduce air into the container (100) to restore the container (100) to normal pressure. The test ends.

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