A test system and method for testing liquid methane transient filling of a large volume pipeline

Abstract

The application belongs to the technical field of cryogenic propellant filling, and discloses a test system and method for testing liquid methane transient filling of a large-capacity cavity pipeline, wherein the test system for testing liquid methane transient filling of a large-capacity cavity pipeline comprises a liquid methane storage unit, a liquid methane supply unit, a nitrogen supply unit, a liquid methane pressurizing unit, a liquid methane filling unit, a liquid methane recovery unit, a liquid methane PLC control unit, a liquid methane visual observation unit and a data monitoring unit; the application can carry out test and measurement on the process of filling a large-capacity cavity pipeline at room temperature by liquid methane, and obtain the pipeline flow rate and the temperature and pressure values of each section of the pipeline during the filling process, so as to accurately predict the changes of each physical quantity in the pipeline during the starting process of a rocket engine and determine a reasonable ignition timing.

Description

Technical Field

[0001] This invention relates to the field of cryogenic propellant filling technology, specifically to a test system and method for testing the transient filling of a large-volume pipeline with liquid methane. Background Technology

[0002] With the rapid development of aerospace technology, propellant selection has undergone three major evolutionary stages: from "meeting basic needs" to "pursuing high efficiency," and finally to "achieving sustainable development." In this development process, liquid methane has stood out due to its superior comprehensive performance. It possesses advantages such as high specific impulse, good combustion stability, low emissions, low cost, long engine life, and simple design (its temperature is similar to liquid oxygen). These characteristics enable liquid methane to achieve a near-perfect balance between propulsion efficiency, economy, and environmental friendliness, making it particularly suitable for the needs of reusable launch vehicles and deep space exploration missions, thus becoming a strategic choice for the development of contemporary aerospace propulsion technology.

[0003] During the startup process of a cryogenic liquid rocket engine, critical components such as the main valve downstream piping and combustion chamber cannot be pre-cooled. Therefore, the propellant system inevitably undergoes a complex two-phase filling process when the main valve opens instantaneously. During this process, the propellant flow within the ambient temperature piping is accompanied by intense multiphase heat and mass transfer phenomena. These complex heat and mass transfer characteristics affect the pressure within the piping and the propellant flow rate into the engine, thus decisively influencing the engine's startup performance.

[0004] Cavitation occurs during the filling of large-volume pipelines at room temperature with liquid methane propellant, significantly reducing the propellant mass flow rate into the engine, resulting in insufficient engine power or even failure to ignite. The pressure within the pipeline also changes continuously with filling time, playing a crucial role in propellant entry into the engine and consequently affecting the engine's ignition timing. However, no experimental studies on transient liquid methane filling have been reported.

[0005] Therefore, there is an urgent need to accurately predict the changes in the physical state of the propellant during the propellant filling process before the rocket engine is started. Summary of the Invention

[0006] The purpose of this invention is to provide a test system and method for testing liquid methane transient filling of a large-volume pipeline, in order to overcome the problems existing in the prior art. This invention can conduct test tests on the process of liquid methane filling a room-temperature large-volume pipeline, and obtain the pipeline flow rate and temperature and pressure values ​​of each section of the pipeline during the filling process. In addition, it can accurately predict the changes of various physical quantities in the pipeline during the rocket engine start-up process and determine a reasonable ignition sequence.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] In a first aspect, the present invention provides a test system for testing a large-volume pipeline transiently filled with liquid methane, comprising:

[0009] Liquid methane storage unit, including liquid methane storage tank;

[0010] A liquid methane supply unit is connected to a liquid methane storage tank.

[0011] A nitrogen supply unit is connected to a liquid methane storage tank.

[0012] The liquid methane pressurization unit is connected to both the liquid methane storage tank and the liquid methane supply unit.

[0013] The liquid methane filling unit includes a filling test pipeline. The inlet of the filling test pipeline is connected to the liquid methane storage tank. The filling test pipeline is connected to the liquid methane PLC control unit, the liquid methane visualization observation unit, and the data monitoring unit, respectively.

[0014] The liquid methane recovery unit is connected to the liquid methane supply unit, the liquid methane pressurization unit, the outlet of the filling test pipeline, and the liquid methane storage unit, respectively.

[0015] The liquid methane PLC control unit is connected to the liquid methane recovery unit, the liquid methane pressurization unit, the liquid methane filling unit, and the liquid methane storage unit, respectively.

[0016] A liquid methane visualization observation unit is connected to the filling test pipeline;

[0017] The data monitoring unit is connected to the filling test pipeline.

[0018] According to one embodiment of the present invention, the liquid methane recovery unit includes a horizontal methane storage tank, a compressor, a cooler, a fifteenth shut-off valve, a fifth pressure sensor, and a fourth temperature sensor;

[0019] The inlet of the horizontal methane storage tank is connected to the outlet of the filling test pipeline. A fifth pressure sensor and a fourth temperature sensor are sequentially installed on the pipeline between the outlet of the filling test pipeline and the inlet of the horizontal methane storage tank. The fifth pressure sensor and the fourth temperature sensor are respectively connected to the liquid methane PLC control unit. The outlet of the horizontal methane storage tank is sequentially connected to the compressor and the cooler. The cooler is connected to the return port of the horizontal methane storage tank through the fifteenth shut-off valve.

[0020] According to one embodiment of the present invention, the liquid methane supply unit includes a liquid methane supply plant, a first shut-off valve, a third shut-off valve, and a first full-opening safety valve;

[0021] The outlet of the liquid methane supply plant is connected to the first liquid phase inlet and the first liquid phase outlet of the liquid methane storage tank via a first shut-off valve. The first pipeline between the first shut-off valve and the liquid methane storage tank is connected to the inlet of the horizontal methane storage tank via a first full-lift safety valve. The second pipeline between the first shut-off valve and the liquid methane storage tank is connected to the inlet of the horizontal methane storage tank via a third shut-off valve.

[0022] According to one embodiment of the present invention, the liquid methane booster unit includes a room temperature nitrogen manifold and exhaust booster device and a self-boosting device;

[0023] The ambient temperature nitrogen manifold, exhaust, and pressurization device includes a nitrogen cylinder group, a first pressure regulating valve, a seventh shut-off valve, and a first pressure sensor. The nitrogen cylinder group is connected to the second liquid phase inlet of the liquid methane storage tank in sequence through the first pressure regulating valve and the seventh shut-off valve. The first pressure regulating valve is connected to the first pressure sensor, and the first pressure sensor is connected to the liquid methane PLC control unit.

[0024] The self-pressurizing device includes a self-pressurizing vaporizer, a second full-lift safety valve, a fourth shut-off valve, a fifth shut-off valve, and a sixth shut-off valve. The first inlet of the self-pressurizing vaporizer is connected to the inlet of the horizontal methane storage tank through the second full-lift safety valve. The second inlet of the self-pressurizing vaporizer is connected to the first liquid phase inlet of the liquid methane storage tank through the fourth shut-off valve. The outlet of the self-pressurizing vaporizer is connected to the first liquid phase outlet of the liquid methane storage tank through the fifth shut-off valve. The pipeline between the fifth shut-off valve and the first liquid phase outlet of the liquid methane storage tank is connected to the outlet of the liquid methane supply plant in sequence through the sixth shut-off valve and the first shut-off valve. The fourth shut-off valve is also connected to the first liquid phase outlet of the liquid methane storage tank through the sixth shut-off valve.

[0025] According to one embodiment of the present invention, the liquid methane filling unit further includes a mass flow meter, a fourth full-opening safety valve, a fourth pressure sensor, a third temperature sensor, an automatic quick-opening valve, and a fourteenth shut-off valve.

[0026] The inlet of the filling test pipeline is connected to the second liquid phase outlet of the liquid methane storage tank via a mass flow meter. The pipeline between the mass flow meter and the second liquid phase outlet of the liquid methane storage tank is connected to the outlet of the liquid methane supply plant via a fourth full-lift safety valve, a first full-lift safety valve, and a first shut-off valve in sequence.

[0027] The inlet of the filling test pipeline is connected to a main pipeline. An automatic quick-opening valve and a hemispherical container are sequentially installed on the main pipeline. The automatic quick-opening valve is connected to the liquid methane PLC control unit. The outlet of the main pipeline is connected to the inlet of the horizontal methane storage tank. A bypass is connected in parallel on the main pipeline, and a fourteenth shut-off valve is installed on the bypass.

[0028] According to one embodiment of the present invention, the data monitoring unit includes a plurality of orifice plates, a plurality of parameter monitoring elements, a plurality of internal thermocouples, a plurality of wall thermocouples and a data collection center;

[0029] The orifice plates and parameter monitoring elements are installed on the main pipeline. The internal thermocouples are distributed along the length of the main pipeline, and the wall thermocouples are distributed along the pipe side. The orifice plates, parameter monitoring elements, wall thermocouples, and internal thermocouples are connected to the data collection center.

[0030] According to one embodiment of the present invention, the liquid methane storage unit further includes a level gauge, an eighth shut-off valve, a second pressure regulating valve, a ninth shut-off valve, a tenth shut-off valve, an eleventh shut-off valve, a twelfth shut-off valve, a thirteenth shut-off valve, a first needle valve, a second needle valve, a third needle valve, a fourth needle valve, a third full-opening safety valve, a first temperature sensor, a second temperature sensor, a second pressure sensor, and a third pressure sensor.

[0031] The third liquid phase inlet of the liquid methane storage tank is connected to the inlet of the horizontal methane storage tank in sequence through the eighth shut-off valve, the third full-lift safety valve, and the thirteenth shut-off valve. The first pipeline of the second liquid phase inlet of the liquid methane storage tank is connected to the inlet of the horizontal methane storage tank through the ninth shut-off valve. The second pipeline of the second liquid phase inlet of the liquid methane storage tank is connected to the inlet of the horizontal methane storage tank in sequence through the second pressure regulating valve and the tenth shut-off valve. The second pressure regulating valve is connected to the second pressure sensor.

[0032] The fourth liquid phase inlet of the liquid methane storage tank is connected to the third liquid phase outlet of the liquid methane storage tank in sequence through the eleventh shut-off valve, the first needle valve, the fourth needle valve, the level gauge, the third needle valve, the twelfth shut-off valve, and the pipeline between the first needle valve and the twelfth shut-off valve is connected through the second needle valve.

[0033] The first temperature sensor is located between the third liquid phase inlet and the fourth liquid phase inlet of the liquid methane storage tank, the second temperature sensor is located on one side of the third liquid phase outlet of the liquid methane storage tank, the first needle valve is connected to the third pressure sensor, and the second pressure sensor, the third pressure sensor, the first temperature sensor and the second temperature sensor are all connected to the liquid methane PLC control unit.

[0034] According to one embodiment of the present invention, the liquid methane PLC control unit includes a PLC control center, a first pressure transmitter, a second pressure transmitter, a third pressure transmitter, a fourth pressure transmitter, a fifth pressure transmitter, a first temperature transmitter, a second temperature transmitter, a third temperature transmitter, a fourth temperature transmitter, a liquid level transmitter, and a mass flow transmitter.

[0035] The PLC control center is connected to the first pressure transmitter, the second pressure transmitter, the third pressure transmitter, the fourth pressure transmitter, the fifth pressure transmitter, the first temperature transmitter, the second temperature transmitter, the third temperature transmitter, the fourth temperature transmitter, the level transmitter, and the mass flow transmitter. The first pressure transmitter is connected to the first pressure sensor, the second pressure transmitter is connected to the second pressure sensor, the third pressure transmitter is connected to the third pressure sensor, the fourth pressure transmitter is connected to the fourth pressure sensor, the fifth pressure transmitter is connected to the fifth pressure sensor, the first temperature transmitter is connected to the first temperature sensor, the second temperature transmitter is connected to the second temperature sensor, the third temperature transmitter is connected to the third temperature sensor, the fourth temperature transmitter is connected to the fourth temperature sensor, the level transmitter is connected to the level gauge, and the mass flow transmitter is connected to the mass flow meter.

[0036] According to one embodiment of the present invention, the liquid methane visualization observation unit includes a visualization segment and a camera;

[0037] The visualization section is installed on the filling test pipeline and is connected to the camera signal; the nitrogen supply unit includes a liquid nitrogen supply tanker and a second shut-off valve.

[0038] The liquid nitrogen supply tanker is connected to the first liquid phase inlet of the liquid methane storage tank via a second shut-off valve.

[0039] This invention provides a test method for testing a large-volume pipeline with transient liquid methane filling. Based on the above embodiments, this invention also provides a test system for testing a large-volume pipeline with transient liquid methane filling, comprising the following steps:

[0040] Nitrogen is introduced into the liquid methane storage tank through the nitrogen supply unit to purge the pipeline and check its airtightness. Nitrogen supply is stopped after the airtightness check is completed.

[0041] Liquid methane is added to the liquid methane storage tank via the liquid methane supply unit;

[0042] The liquid methane storage tank is pressurized by the liquid methane pressurization unit after liquid methane is added. During the pressurization process, the pressure of the liquid methane storage tank is monitored in real time by the liquid methane PLC control unit. When the liquid methane PLC control unit detects that the pressure of the liquid methane storage tank reaches the set value, it automatically triggers the opening of the filling test pipeline and the liquid methane visualization observation unit.

[0043] The pressurized liquid methane enters the filling test pipeline for transient filling. The data monitoring unit collects the parameter data of the filling test pipeline in real time during the transient filling process and visualizes the fluid morphology of the pressurized liquid methane during the transient filling process.

[0044] After the transient filling is completed, the filling fluid is obtained and enters the liquid methane recovery unit for recovery.

[0045] The above technical solution has the following advantages or beneficial effects:

[0046] Firstly, this invention provides an experimental system for testing the transient filling of a large-volume pipeline with liquid methane. By constructing an integrated experimental system encompassing liquid methane storage, supply, pressurization, filling, recovery, and multi-dimensional monitoring and control, this invention effectively simulates the transient filling process of liquid methane in a large-volume pipeline at room temperature. This system can collect flow rate, temperature, and pressure data in real time during the filling process, and combined with visual observation, comprehensively reveal the dynamic characteristics of the fluid and the phase change heat transfer law. The experimental results can provide key physical parameters for the rocket engine start-up phase, enabling accurate prediction of complex transient processes within the pipeline, thereby optimizing ignition timing design, improving the reliability and safety of engine start-up, and providing important support for the development of liquid rocket engines.

[0047] In some embodiments, the present invention achieves efficient and safe recovery and recycling of cryogenic methane after filling through a liquid methane recovery unit comprising a horizontal storage tank, a compressor, a cooler, and a closed-loop control structure; it can quickly and stably recover gaseous methane and liquefy and reflux it through compression and cooling, significantly improving the utilization rate of the medium and effectively avoiding the safety and environmental risks caused by direct methane emissions; at the same time, the integration of pressure and temperature sensors and linkage with a PLC system enables precise monitoring and automatic control of the recovery process, ensuring the stability and reliability of the recovery process, providing important protection for continuous and repeated transient filling tests, and reducing test costs and operational risks.

[0048] In some embodiments, the present invention optimizes the pipelines and valves of the liquid methane supply unit to construct a safe, flexible, and efficient medium supply guarantee. This unit achieves stable delivery of liquid methane from the supply plant to the main storage tank through a first shut-off valve, and forms a reliable connection with the recovery unit through two independent pipelines connected in parallel with a first full-opening safety valve and a third shut-off valve. This not only establishes an overpressure protection mechanism for the main supply path, but also forms an emergency or supplementary delivery channel, significantly improving the system's ability to cope with pressure fluctuations and emergency conditions, ensuring the stability and safety of the liquid methane supply process, and laying a solid foundation for the continuous and reliable operation of the entire test system.

[0049] In some embodiments, this invention constructs a flexible, stable, and reliable liquid methane pressurization unit by integrating two independent and complementary pressurization schemes: ambient temperature nitrogen replenishment pressurization and liquid methane self-pressurization. This provides a precise and controllable pressure environment for transient filling tests. Within this unit, the ambient temperature nitrogen manifold replenishment pressurization device, through closed-loop control of a pressure regulating valve and a pressure sensor, achieves precise and stable pressurization of the liquid methane storage tank with rapid response, making it particularly suitable for test conditions requiring rapid pressure establishment or precise pressure control. Simultaneously, the self-pressurization device cleverly utilizes the system's own... The liquid methane resource is pressurized by a vaporizer and equipped with redundant valves, pipelines, and safety valves. This not only achieves internal circulation and efficient utilization of the medium, reducing dependence on external gas sources, but also connects to the recovery unit through a second full-opening safety valve, forming an overpressure protection loop and significantly improving the inherent safety of the system. The two sets of devices can work independently or in tandem, greatly enhancing the test system's adaptability to different working conditions, ensuring the accuracy and reliability of pressure conditions during the filling process, and providing crucial support for obtaining high-quality test data.

[0050] In some embodiments, the present invention achieves high-precision control and safety assurance of the transient filling process by optimizing the structural design of the liquid methane filling unit. The unit is equipped with a mass flow meter at the inlet of the filling test pipeline, which can accurately measure and record the instantaneous flow rate during the filling process, providing key data for analyzing transient flow characteristics. By connecting the main pipeline in parallel with a bypass with a shut-off valve and combining it with an automatic quick-opening valve, the system can simulate different filling conditions. In particular, the rapid response of the quick-opening valve accurately reproduces the rapid filling process during engine startup. The integrated fourth full-opening safety valve forms multiple safety relief paths, effectively ensuring pipeline overpressure safety. At the same time, the arrangement of pressure and temperature sensors enables real-time monitoring of the filling status, so that the system can not only accurately test the dynamic process of liquid methane filling a large cavity, but also provide reliable experimental basis and data support for determining the reasonable ignition sequence of the engine.

[0051] In some embodiments, this invention achieves precise capture and comprehensive analysis of the entire transient filling process of liquid methane by integrating a multi-dimensional, high-density data monitoring unit. This unit arranges orifice plates and parameter monitoring elements on the main pipeline to accurately acquire key dynamic parameters of the fluid. At the same time, internal thermocouples distributed along the pipe length and wall thermocouples distributed along the pipe side together construct a three-dimensional monitoring network of the internal fluid temperature field and the pipe wall temperature field. All sensor data are transmitted to the data collection center in real time, providing researchers with a complete data chain of flow evolution, phase change heat transfer, and thermal shock effects during the filling process. This greatly enhances the ability to analyze complex transient physical phenomena and provides solid data support for accurately predicting the rocket engine start-up process and optimizing the ignition timing.

[0052] In some embodiments, this invention significantly improves the safety, stability, and accuracy of the liquid methane storage process by providing a highly integrated and fully functional monitoring and control subsystem for the liquid methane storage unit. This unit, through the coordinated arrangement of a level gauge and multiple temperature and pressure sensors, achieves comprehensive real-time monitoring of the medium state within the storage tank. Through multiple inlet pipelines, particularly the precise pressure regulation loop formed by the second pressure regulating valve, the storage tank can flexibly receive gaseous or liquid methane from the recovery unit and achieve precise pressure control, providing a stable supply back pressure for upstream filling tests. Simultaneously, the unit internally forms a complete level gauge calibration pipeline. Through the precise combination of multiple needle valves and shut-off valves, online calibration and maintenance of the level gauge can be safely and conveniently completed without affecting the main process, ensuring the long-term reliability of key monitoring data. The installation of a third full-opening safety valve and multiple relief pipelines provides redundant overpressure protection for the storage tank. Through the integrated design of monitoring, control, calibration, and safety protection, the liquid methane storage state is always known, controllable, and adjustable, laying a solid foundation for the continuous and stable operation of the entire test system.

[0053] In some embodiments, this invention, by constructing a highly integrated and automated liquid methane PLC control unit, achieves precise monitoring and intelligent control of the entire test system process, significantly improving the reliability, safety, and efficiency of the test. This unit connects all pressure and temperature sensors, level gauges, and mass flow meters distributed throughout the key nodes of the system to the PLC control center via a dedicated signal transmitter, constructing a centralized and unified data acquisition and monitoring network. The PLC control center, as the core brain, can receive and process all key parameters from the storage tank, pressurization pipeline, filling pipeline, and recovery unit in real time, forming a comprehensive and immediate perception of the system's operating status. Based on this, the control system can not only centrally display and record data, but also precisely control actuators such as automatic quick-opening valves and pressure regulating valves through programming logic, achieving automatic start and stop of the filling process, precise pressure adjustment, and monitoring and early warning of safety thresholds. This minimizes human error and intervention delays, ensuring high repeatability and data consistency in the transient filling test process, providing crucial control assurance for obtaining high-quality test data and accurately predicting the engine start-up process.

[0054] In some embodiments, the present invention significantly improves the observation capability and preprocessing efficiency of the test system by introducing a liquid methane visualization observation unit and an independent nitrogen supply unit. The visualization observation unit is equipped with a transparent visualization section and a high-speed camera on the filling test pipeline, which can directly capture and record key visual information such as phase changes, flow pattern transformations, and two-phase flow characteristics of liquid methane during the filling process. The intuitive image data and sensor data corroborate each other, providing an irreplaceable basis for in-depth analysis of the transient filling mechanism. The independent nitrogen supply unit, through the liquid nitrogen supply tank truck and shut-off valve, can quickly and efficiently purge and pre-cool the liquid methane pipeline and cavity before the test, effectively removing moisture and impurities from the system, preventing freezing and blockage, and allowing the pipeline to smoothly transition from room temperature to low temperature conditions. This greatly improves the purity, safety, and stability of the subsequent liquid methane filling test, ensuring the accuracy and reliability of the test data.

[0055] Secondly, this invention provides a test method for testing liquid methane transient filling of a large-volume pipeline. Based on the aforementioned highly integrated and automated test system, it can safely, accurately, and efficiently complete the entire process test of liquid methane transient filling. This method ensures the purity and safety of the test system through standardized purging and airtightness checks. The automatic triggering and precise control of the pressurization and filling process are achieved using a PLC control unit, ensuring the consistency and reproducibility of test conditions. During the filling process, the data monitoring unit and the visualization observation unit work synchronously, which can simultaneously acquire intuitive images of multiple physical parameters such as flow rate, temperature, and pressure, as well as fluid morphology, providing a complete data chain for a comprehensive analysis of the complex two-phase flow and heat transfer phenomena during the transient filling process. This method achieves the safe recovery of the filling fluid, forming a closed-loop process from preparation and testing to recovery, providing key and reliable test basis for determining the ignition sequence of rocket engines. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of a test system for transiently filling a large-volume pipeline with test liquid methane, as shown in some embodiments of this specification.

[0057] Figure 2 This is a schematic diagram of the main pipeline structure of the filling test pipeline according to some embodiments of this specification;

[0058] In all the accompanying drawings, the same reference numerals denote the same technical features, specifically:

[0059] 1. Liquid methane supply plant; 2. Liquid nitrogen supply tanker; 3. Liquid methane storage tank; 4. Nitrogen cylinder group; 5. Self-pressurizing vaporizer; 6. PLC control center; 7. Data collection center; 8. Mass flow meter; 9. Filling test pipeline; 10. Visualization section; 11. Camera; 12. Horizontal methane storage tank; 13. Compressor; 14. Cooler; 15. Level gauge; V1, First shut-off valve; V2, Second shut-off valve; V3, Third shut-off valve; V4, First full-lift safety valve; V5, Second full-lift safety valve; V6, Fourth shut-off valve; V7, Fifth shut-off valve; V8, Sixth shut-off valve; V9, ... 1. Pressure regulating valve; V10. Seventh shut-off valve; V11. Eighth shut-off valve; V12. Third full-lift safety valve; V13. Second pressure regulating valve; V14. Ninth shut-off valve; V15. Tenth shut-off valve; V16. First needle valve; V17. Eleventh shut-off valve; V18. Twelfth shut-off valve; V19. Second needle valve; V20. Third needle valve; V21. Fourth needle valve; V22. Thirteenth shut-off valve; V23. Automatic quick-opening valve; V24. Fourteenth shut-off valve; V25. Fifteenth shut-off valve; V26. Fourth full-lift safety valve; P1. First pressure sensor; P2. Second pressure sensor; P3. The following pressure sensors are listed: P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16; T1, P2, P15, P16; T1, P17, P18, P19, P10, P11, P12, P13, P14 ...1, P12, P15, P16, P17, P18, P19, P11, P12, P13, P14, P15, P16; T1, P17, P18, P19, P11, P12, P15, P16, P17, P18, P19, P11, P16, P19, P11, P12, P16, P19, P11, P12, P13, P14, P15, P16, P17, P18, P19, P11, P16, P19, P11, P12, P16, P19, P11, P12, P16, P19, P11, P12, P16, P19, P11, P12, P16, P19, P11, P16, P19, P T6, sixth temperature sensor; T7, seventh temperature sensor; T8, eighth temperature sensor; T9, ninth temperature sensor; T10, tenth temperature sensor; T11, eleventh temperature sensor; T12, twelfth temperature sensor; T13, thirteenth temperature sensor; T14, fourteenth temperature sensor; T15, fifteenth temperature sensor; T16, sixteenth temperature sensor; T17, seventeenth temperature sensor; T18, eighteenth temperature sensor; T19, nineteenth temperature sensor; K1, first orifice plate; K2, second orifice plate; K3, third orifice plate; M1, mass flow transmitter. Detailed Implementation

[0060] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0061] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, 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 this invention.

[0062] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0063] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., 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, an electrical connection, or a communication 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 according to the specific circumstances.

[0064] 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 being 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 being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0065] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0066] Example:

[0067] This invention provides a test system for testing liquid methane transient filling of a large-volume pipeline. It can conduct tests on the process of liquid methane filling a room-temperature large-volume pipeline, and obtain the pipeline flow rate and temperature and pressure values ​​of each section of the pipeline during the filling process. In addition, it can accurately predict the changes of various physical quantities in the pipeline during the rocket engine start-up process and determine a reasonable ignition sequence.

[0068] Figure 1 This is a schematic diagram of a test system for testing a large-volume pipeline with transient liquid methane filling, according to some embodiments of this specification. The test system for testing a large-volume pipeline with transient liquid methane filling includes: a liquid methane storage unit, a liquid methane supply unit, a nitrogen supply unit, a liquid methane pressurization unit, a liquid methane filling unit, a liquid methane recovery unit, a liquid methane PLC control unit, a liquid methane visualization observation unit, and a data monitoring unit.

[0069] The liquid methane storage unit includes a liquid methane storage tank 3, a liquid methane supply unit connected to the liquid methane storage tank 3, a nitrogen supply unit connected to the liquid methane storage tank 3, and a liquid methane pressurization unit connected to both the liquid methane storage tank 3 and the liquid methane supply unit. The liquid methane filling unit includes a filling test pipeline 9 with a large-capacity structure. The inlet of the filling test pipeline 9 is connected to the liquid methane storage tank 3. The filling test pipeline 9 is connected to a liquid methane PLC control unit, a liquid methane visualization observation unit, and a data monitoring unit. The liquid methane recovery unit is connected to the liquid methane supply unit, the liquid methane pressurization unit, the outlet of the filling test pipeline 9, and the liquid methane storage unit. The liquid methane PLC control unit is connected to the liquid methane recovery unit, the liquid methane pressurization unit, the liquid methane filling unit, and the liquid methane storage unit. The liquid methane visualization observation unit is connected to the filling test pipeline 9, and the data monitoring unit is connected to the filling test pipeline 9.

[0070] In some embodiments, the liquid methane storage tank 3 is a 1.5 cubic meter liquid methane storage tank.

[0071] In some embodiments, the liquid methane recovery unit includes a horizontal methane storage tank 12, a compressor 13, a cooler 14, a fifteenth shut-off valve V25, a fifth pressure sensor P5, and a fourth temperature sensor T4, and is mainly used to recover the methane used during the filling process and the methane discharged when a malfunction occurs.

[0072] The inlet of the horizontal methane storage tank 12 is connected to the outlet of the filling test pipeline 9. A fifth pressure sensor P5 and a fourth temperature sensor T4 are sequentially installed on the pipeline between the outlet of the filling test pipeline 9 and the inlet of the horizontal methane storage tank 12. The fifth pressure sensor P5 and the fourth temperature sensor T4 are respectively connected to the liquid methane PLC control unit. The outlet of the horizontal methane storage tank 12 is sequentially connected to the compressor 13 and the cooler 14. The cooler 14 is connected to the return port of the horizontal methane storage tank 12 through the fifteenth shut-off valve V25.

[0073] In some embodiments, the storage tank used in the liquid methane recovery unit has a volume of tens of thousands of cubic meters, and the horizontal methane storage tank 12 has a volume of up to 30,000 cubic meters.

[0074] In some embodiments, the liquid methane recovery unit adopts a closed system, which reduces resource waste and avoids contact between methane gas and air, ensuring the safety of the experiment. Meanwhile, the horizontal methane storage tank 12 has a volume of up to 30,000 cubic meters, and the amount of methane flowing through it during filling results in very little pressure, eliminating the possibility of a sudden pressure increase leading to an explosion, thus ensuring the safety of the experiment. The pressure and temperature changes within the 30,000 cubic meter horizontal methane storage tank 12 are monitored in real time using the fifth pressure sensor P5 and the fourth temperature sensor T4, and a BOG reliquefaction cycle is implemented in the 30,000 cubic meter horizontal methane storage tank 12. The methane levels within the 30,000 cubic meter horizontal methane storage tank 12 can be adjusted as needed using the compressor 13, cooler 14, and fifteenth shut-off valve V25.

[0075] In some embodiments, the liquid methane recovery unit employs a BOG reliquefaction cycle, and the tank pressure can be adjusted during the test by liquefying the gas at the top of the tank.

[0076] In some embodiments, the liquid methane supply unit includes a liquid methane supply plant 1, a first shut-off valve V1, a third shut-off valve V3, and a first full-opening safety valve V4;

[0077] The outlet of the liquid methane supply plant 1 is connected to the first liquid phase inlet and the first liquid phase outlet of the liquid methane storage tank 3 via a first shut-off valve V1. A first pipeline between the first shut-off valve V1 and the liquid methane storage tank 3 is connected to the inlet of the horizontal methane storage tank 12 via a first full-lift safety valve V4. A second pipeline between the first shut-off valve V1 and the liquid methane storage tank 3 is connected to the inlet of the horizontal methane storage tank 12 via a third shut-off valve V3. The liquid methane supply unit is used to provide sufficient liquid methane to the liquid methane storage unit. Liquid methane is supplied through a system where the first shut-off valve V1 is the main valve, controlling the flow of liquid methane from the plant into the test system. When the first shut-off valve V1 malfunctions and cannot be closed, the liquid methane storage unit will be unable to receive a continuous supply of liquid methane. At this time, the first full-opening safety valve V4 will automatically open to allow the liquid methane to flow directly to the 30,000 cubic meter horizontal methane storage tank 12. If the first full-opening safety valve V4 also malfunctions and cannot be opened, the third shut-off valve V3 will be opened to allow the liquid methane to flow to the 30,000 cubic meter horizontal methane storage tank 12.

[0078] In some embodiments, the first pipeline and the second pipeline between the first shut-off valve V1 and the liquid methane storage tank 3 are arranged in parallel.

[0079] In some embodiments, the liquid methane booster unit includes a room temperature nitrogen manifold and exhaust booster device and a self-boosting device;

[0080] The ambient temperature nitrogen manifold, gas supply, and pressurization device includes a nitrogen cylinder group 4, a first pressure regulating valve V9, a seventh shut-off valve V10, and a first pressure sensor P1. When the pressure is too high, it is adjusted by the safety protection device of the liquid methane storage unit. The nitrogen cylinder group 4 is connected to the second liquid phase inlet of the liquid methane storage tank 3 in sequence through the first pressure regulating valve V9 and the seventh shut-off valve V10. The first pressure regulating valve V9 is connected to the first pressure sensor P1, and the first pressure sensor P1 is connected to the liquid methane PLC control unit.

[0081] The self-pressurizing device includes a self-pressurizing vaporizer 5, a second full-lift safety valve V5, a fourth shut-off valve V6, a fifth shut-off valve V7, and a sixth shut-off valve V8. The first inlet of the self-pressurizing vaporizer 5 is connected to the inlet of the horizontal methane storage tank 12 through the second full-lift safety valve V5. The second inlet of the self-pressurizing vaporizer 5 is connected to the first liquid phase inlet of the liquid methane storage tank 3 through the fourth shut-off valve V6. The outlet of the self-pressurizing vaporizer 5 is connected to the first liquid phase outlet of the liquid methane storage tank 3 through the fifth shut-off valve V7. The pipeline between the fifth shut-off valve V7 and the first liquid phase outlet of the liquid methane storage tank 3 is connected to the outlet of the liquid methane supply plant 1 in sequence through the sixth shut-off valve V8 and the first shut-off valve V1. The fourth shut-off valve V6 is also connected to the first liquid phase outlet of the liquid methane storage tank 3 through the sixth shut-off valve V8. When the pressure is too high, it is adjusted by the second full-lift safety valve V5. In addition, methane from the liquid methane supply plant 1 can be directly introduced into the self-pressurizing vaporizer 5 for pressurization through the sixth shut-off valve V8.

[0082] In some embodiments, Figure 2 The schematic diagram of the main pipeline structure of the filling test pipeline shown in some embodiments of this specification is shown. The liquid methane filling unit also includes a mass flow meter 8, a fourth full-lift safety valve V26, a fourth pressure sensor P4, a third temperature sensor T3, an automatic quick-opening valve V23 and a fourteenth shut-off valve V24, which is the core unit of the system.

[0083] The inlet of the filling test pipeline 9 is connected to the second liquid phase outlet of the liquid methane storage tank 3 via a mass flow meter 8. The pipeline between the mass flow meter 8 and the second liquid phase outlet of the liquid methane storage tank 3 is connected to the outlet of the liquid methane supply plant 1 via a fourth full-lift safety valve V26, a first full-lift safety valve V4, and a first shut-off valve V1. The inlet of the filling test pipeline 9 is connected to a main pipeline. An automatic quick-opening valve V23 and a hemispherical container 16 are sequentially installed on the main pipeline. The automatic quick-opening valve V23 is connected to the liquid methane PLC control unit. The main pipeline outlet is connected to the inlet of the horizontal methane storage tank 12; a bypass is connected in parallel on the main pipeline, and the fourteenth shut-off valve V24 is installed on the bypass to pre-cool the pipeline before the fourteenth shut-off valve V24, and at the same time fill the pipeline before the fourteenth shut-off valve V24 with liquid methane, so that the filling process is closer to the actual situation. It should be noted that in order to obtain a good pre-cooling effect and fill the pipeline before the quick-opening valve as completely as possible with liquid methane, the pipeline inlet of the liquid methane bypass unit should be as close as possible to the upstream of the fourteenth shut-off valve V24.

[0084] In some embodiments, the piping of the liquid methane filling unit includes, but is not limited to, structures such as orifice plates, bends, and large cavities.

[0085] In some embodiments, the front end of the bypass pipeline is close to the front end of the automatic quick-opening valve V23 in the liquid methane filling unit.

[0086] In some embodiments, the data monitoring unit includes several orifice plates, several parameter monitoring elements, several internal thermocouples, several wall thermocouples, and a data collection center 7;

[0087] The orifice plates and parameter monitoring elements are installed on the main pipeline. Several internal thermocouples are distributed along the length of the main pipeline, and several wall thermocouples are distributed along the pipe side. The orifice plates, parameter monitoring elements, wall thermocouples, and internal thermocouples are connected to the data collection center 7. It is mainly used to monitor and record the measurement data of the pressure sensors and temperature sensors arranged in the filling test pipeline 9 in real time.

[0088] In some embodiments, the plurality of perforated plates includes a first perforated plate K1, a second perforated plate K2, and a third perforated plate K3; the number of internal thermocouples is 6; and the number of wall thermocouples is 9.

[0089] The parameter monitoring elements include several other pressure sensors and several other temperature sensors, with 10 other pressure sensors and 15 other temperature sensors.

[0090] In some embodiments, the remaining pressure sensors include a sixth pressure sensor P6, a seventh pressure sensor P7, an eighth pressure sensor P8, a ninth pressure sensor P9, a tenth pressure sensor P10, an eleventh pressure sensor P11, a twelfth pressure sensor P12, a thirteenth pressure sensor P13, a fourteenth pressure sensor P14, and a fifteenth pressure sensor P15.

[0091] The remaining temperature sensors include the fifth temperature sensor T5, the sixth temperature sensor T6, the seventh temperature sensor T7, the eighth temperature sensor T8, the ninth temperature sensor T9, the tenth temperature sensor T10, the eleventh temperature sensor T11, the twelfth temperature sensor T12, the thirteenth temperature sensor T13, the fourteenth temperature sensor T14, the fifteenth temperature sensor T15, the sixteenth temperature sensor T16, the seventeenth temperature sensor T17, the eighteenth temperature sensor T18, and the nineteenth temperature sensor T19.

[0092] The main pipeline is sequentially equipped with the following sensors: fifth temperature sensor T5, sixth pressure sensor P6, sixth temperature sensor T6, first orifice plate K1, seventh pressure sensor P7, seventh temperature sensor T7, eighth temperature sensor T8, eighth pressure sensor P8, second orifice plate K2, ninth pressure sensor P9, ninth temperature sensor T9, tenth temperature sensor T10, tenth pressure sensor P10, eleventh pressure sensor P11, eleventh temperature sensor T11, twelfth temperature sensor T12, thirteenth temperature sensor T13, twelfth pressure sensor P12, fourteenth temperature sensor T14, fifteenth temperature sensor T15, hemispherical container 16, third orifice plate K3, fourteenth pressure sensor P14, eighteenth temperature sensor T18, nineteenth temperature sensor T19, and fifteenth pressure sensor P15.

[0093] The sixth pressure sensor P6, the seventh pressure sensor P7, the eighth pressure sensor P8, the ninth pressure sensor P9, the tenth pressure sensor P10, the eleventh pressure sensor P11, the twelfth pressure sensor P12, the thirteenth pressure sensor P13, the fourteenth pressure sensor P14, the fifteenth pressure sensor P15, the fifth temperature sensor T5, the sixth temperature sensor T6, the seventh temperature sensor T7, the eighth temperature sensor T8, the ninth temperature sensor T9, the tenth temperature sensor T10, the eleventh temperature sensor T11, the twelfth temperature sensor T12, the thirteenth temperature sensor T13, the fourteenth temperature sensor T14, the fifteenth temperature sensor T15, the sixteenth temperature sensor T16, the seventeenth temperature sensor T17, the eighteenth temperature sensor T18, and the nineteenth temperature sensor T19 are all connected to the data collection center 7.

[0094] The sixteenth temperature sensor T16 is located at the inlet of the hemispherical container 16, the seventeenth temperature sensor T17 is located at the outlet of the hemispherical container 16, and the thirteenth pressure sensor P13 is located in the hemispherical container 16.

[0095] In some embodiments, the pressure change in the pipe mainly occurs before and after the orifice plate. Therefore, the evaporation of liquid methane in the pipe also mainly occurs after the orifice plate and at the hot wall surface. At the same time, evaporation is more likely to occur at the bend because the contact with the wall surface is more sufficient. Therefore, the arrangement of several parameter monitoring elements is mainly near the orifice plate, away from the orifice plate, the bend, and the hemispherical container 16.

[0096] In some embodiments, the liquid methane storage unit further includes a level gauge 15, an eighth shut-off valve V11, a second pressure regulating valve V13, a ninth shut-off valve V14, a tenth shut-off valve V15, an eleventh shut-off valve V17, a twelfth shut-off valve V18, a thirteenth shut-off valve V22, a first needle valve V16, a second needle valve V19, a third needle valve V20, a fourth needle valve V21, a third full-opening safety valve V12, a first temperature sensor T1, a second temperature sensor T2, a second pressure sensor P2, and a third pressure sensor P3, for providing liquid methane under certain conditions to the liquid methane filling unit;

[0097] The third liquid phase inlet of the liquid methane storage tank 3 is connected to the inlet of the horizontal methane storage tank 12 via the eighth shut-off valve V11, the third full-lift safety valve V12, and the thirteenth shut-off valve V22 in sequence. The first pipeline of the second liquid phase inlet of the liquid methane storage tank 3 is connected to the inlet of the horizontal methane storage tank 12 via the ninth shut-off valve V14. The second pipeline of the second liquid phase inlet of the liquid methane storage tank 3 is connected to the inlet of the horizontal methane storage tank 12 via the second pressure regulating valve V13 and the tenth shut-off valve V15 in sequence. The second pressure regulating valve V13 is connected to the second pressure sensor P2. The fourth liquid phase inlet of the liquid methane storage tank 3 is connected to the eleventh shut-off valve V17, the first needle valve V16, and the fourth shut-off valve V22 in sequence. Needle valve V21, level gauge 15, third needle valve V20, twelfth shut-off valve V18 are connected to the third liquid phase outlet of liquid methane storage tank 3. The pipeline between first needle valve V16 and twelfth shut-off valve V18 is connected through second needle valve V19. First temperature sensor T1 is set between the third liquid phase inlet and the fourth liquid phase inlet of liquid methane storage tank 3. Second temperature sensor T2 is set on one side of the third liquid phase outlet of liquid methane storage tank 3. First needle valve V16 is connected to third pressure sensor P3. Second pressure sensor P2, third pressure sensor P3, first temperature sensor T1 and second temperature sensor T2 are all connected to liquid methane PLC control unit.

[0098] The eighth shut-off valve V11, the second pressure regulating valve V13, the third full-opening safety valve V12, and the thirteenth shut-off valve V22 constitute the safety protection device for the 1.5 cubic meter liquid methane storage tank 3. When the pressure inside the 1.5 cubic meter liquid methane storage tank 3 is abnormal, it can release pressure in time to prevent explosion. The second pressure regulating valve V13 and the tenth shut-off valve V15 work together with the liquid methane pressurization unit to regulate the pressure inside the 1.5 cubic meter liquid methane storage tank 3. If the second pressure regulating valve V13 fails, the tenth shut-off valve V15 is closed, and manual adjustment is performed through the ninth shut-off valve V14. The eleventh shut-off valve V17, the twelfth shut-off valve V18, and the second needle valve V1 9. The third needle valve V20, the fourth needle valve V21, and the level gauge 15 together constitute the level measurement system of the 1.5 cubic meter liquid methane storage tank 3, which is used to monitor the changes in the liquid level in the 1.5 cubic meter liquid methane storage tank 3 at all times, and can accurately monitor the methane flow rate in the pipeline during the filling process; the first needle valve V16 and the third pressure sensor P3 are used to monitor the pressure changes in the 1.5 cubic meter liquid methane storage tank 3 at all times, the first temperature sensor T1 is used to monitor the temperature changes of the top gas phase in the 1.5 cubic meter liquid methane storage tank 3 at all times, and the second temperature sensor T2 is used to monitor the temperature changes of the bottom liquid phase in the 1.5 cubic meter liquid methane storage tank 3 at all times.

[0099] In some embodiments, the first pipeline and the second pipeline of the second liquid phase inlet of the liquid methane storage tank 3 are arranged in parallel.

[0100] In some embodiments, the liquid methane PLC control unit includes a PLC control center 6, a first pressure transmitter, a second pressure transmitter, a third pressure transmitter, a fourth pressure transmitter, a fifth pressure transmitter, a first temperature transmitter, a second temperature transmitter, a third temperature transmitter, a fourth temperature transmitter, a liquid level transmitter, and a mass flow transmitter M1.

[0101] The PLC control center 6 is connected to the first pressure transmitter, the second pressure transmitter, the third pressure transmitter, the fourth pressure transmitter, the fifth pressure transmitter, the first temperature transmitter, the second temperature transmitter, the third temperature transmitter, the fourth temperature transmitter, the level transmitter, and the mass flow transmitter M1. The first pressure transmitter is connected to the first pressure sensor P1, the second pressure transmitter is connected to the second pressure sensor P2, the third pressure transmitter is connected to the third pressure sensor P3, the fourth pressure transmitter is connected to the fourth pressure sensor P4, the fifth pressure transmitter is connected to the fifth pressure sensor P5, the first temperature transmitter is connected to the first temperature sensor T1, the second temperature transmitter is connected to the second temperature sensor T2, the third temperature transmitter is connected to the third temperature sensor T3, the fourth temperature transmitter is connected to the fourth temperature sensor T4, the level transmitter is connected to the level gauge 15, and the mass flow transmitter M1 is connected to the mass flow meter 8.

[0102] The liquid methane PLC control unit is mainly used to monitor and record the measurement data of the first pressure sensor P1, second pressure sensor P2, third pressure sensor P3, fourth pressure sensor P4, fifth pressure sensor P5, first temperature sensor T1, second temperature sensor T2, third temperature sensor T3, fourth temperature sensor T4, mass flow meter 8, and level gauge 15, which are arranged in addition to the filling test pipeline 9 (also known as the actual filling test pipeline). At the same time, it controls the opening of the automatic quick-opening valve V23 and the high-speed camera 11 to achieve a high degree of automation. The pressure value inside the 1.5 cubic meter liquid methane storage tank 3 is set by the PLC control center 6, and the pressure is increased by the liquid methane pressurization unit. The PLC control center 6 judges the pressure status inside the 1.5 cubic meter liquid methane storage tank 3 through the data transmitted by the pressure transmitter. When the pressure reaches the set value, the PLC control center 6 simultaneously controls the opening of the automatic quick-opening valve V23 and the high-speed camera 11, and the filling process starts automatically.

[0103] In some embodiments, the liquid methane visualization observation unit includes a visualization segment 10 and a camera 11; the visualization segment 10 is disposed on the filling test pipeline 9, and the visualization segment 10 is signal-connected to the camera 11.

[0104] In some embodiments, the liquid methane visualization observation unit is located at the end of the filling test pipeline 9 and monitors the form of methane flowing out of the filling test pipeline 9 using a high-speed camera 11.

[0105] In some embodiments, the liquid methane visualization monitoring unit is composed of double-layered quartz glass, with the interlayer evacuated by a vacuum pump to maintain a state of approximately 1 Pa.

[0106] In some embodiments, the nitrogen supply unit includes a liquid nitrogen supply tanker 2 and a second shut-off valve V2; the liquid nitrogen supply tanker 2 is connected to the first liquid phase inlet of the liquid methane storage tank 3 through the second shut-off valve V2; it is mainly used to purge the pipelines and containers before the start of the test, on the one hand to remove residues and impurities in the system to ensure the safety of the test process; on the other hand to check the sealing of the system to ensure the continuity and stability of the process flow.

[0107] In some embodiments, the nitrogen supply unit is used for purging and replacing the system before the test to ensure the safety of the test process; it is also used to test the airtightness of the system to ensure the continuity and accuracy of the test process. The liquid methane supply unit provides sufficient liquid methane during the system filling process. The liquid methane storage unit provides liquid methane under certain conditions for the filling process of large-volume pipelines. The liquid methane pressurization unit pressurizes the system through a combination of a self-pressurizing vaporizer and a room-temperature nitrogen manifold to ensure pressurization stability, maintaining the liquid methane storage unit at its rated pressure. The liquid methane pressurization unit is gas-connected to the liquid methane storage tank. The liquid methane PLC control unit consists of an explosion-proof cabinet and configuration software, used for automatically opening the quick-opening valve and the pressure protection regulating valve. Simultaneously, it continuously monitors the temperature, pressure, and liquid level changes of the liquid methane storage unit in the PLC control interface. One end of the liquid methane bypass unit is connected to the liquid methane storage unit, and the other end is connected to the pipeline before the quick-opening valve. The liquid methane filling unit is primarily used for testing, and its structure includes, but is not limited to, orifice plates, hemispherical containers, and bends. A quick-opening valve is installed at the front of the liquid methane filling unit to control the start and end of the filling process. The liquid methane visualization observation unit is composed of double-layered quartz glass, with the interlayer evacuated by a vacuum pump to maintain a pressure of approximately 1 Pa. The fluid state exiting the hemispherical cavity can be observed through this unit, which is connected to the end of the liquid methane filling unit via a flange. A high-speed camera is used for filming in the liquid methane visualization observation section, and a PLC control unit synchronizes the quick-opening valve and high-speed camera filming using an automatic control method. The liquid methane recovery unit recovers the liquid methane used in the filling process through a large liquid methane storage tank, and the pressure changes within the tank are monitored continuously during the test. The data monitoring unit consists of pressure and temperature sensors, mainly used to monitor the pressure, temperature, and wall temperature along the filling pipeline during the filling process.

[0108] In some embodiments, the liquid methane storage unit and the liquid methane pressurization unit are equipped with a pressure regulating valve for adjusting the tank pressure in the liquid methane storage unit. At the same time, a shut-off valve is connected in parallel with the pressure regulating valve in the liquid methane storage unit to ensure the safety of the liquid methane storage unit.

[0109] In some embodiments, a self-test of the test system is required before the test begins, including the calibration of the automatic control function of the liquid methane PLC control unit and the various measuring instruments used in the data monitoring unit.

[0110] In some embodiments, the liquid methane pressurization unit uses a combination of a self-pressurizing vaporizer and ambient temperature nitrogen manifold to pressurize the liquid methane storage unit, thereby ensuring the stability of the pressurization.

[0111] In some embodiments, both the liquid methane PLC control unit and the data monitoring unit can achieve millisecond-level data acquisition technology.

[0112] In some embodiments, the gas in the entire system needs to be replaced through the nitrogen supply unit before the test begins, and the airtightness of the system is monitored at the same time.

[0113] In some embodiments, liquid nitrogen is used for calibration before the formal start of the liquid methane filling test, which improves the success rate of the test while saving resources.

[0114] The present invention also provides a test method for testing the transient filling of a large-volume pipeline with liquid methane, comprising the following steps:

[0115] Step 1: Nitrogen gas is introduced into liquid methane storage tank 3 through the nitrogen supply unit to purge and replace the pipeline and check its airtightness. Nitrogen supply is stopped after the airtightness check is completed. This specifically includes:

[0116] Using liquid nitrogen supply tanker 2 as the nitrogen source, room temperature high-pressure nitrogen is supplied through its vaporization system. The second shut-off valve V2 is opened to allow nitrogen to enter the system. Then, the relevant valves of the liquid methane supply unit, liquid methane storage unit, liquid methane pressurization unit (partial passage), liquid methane filling unit (including main pipeline and bypass), and liquid methane recovery unit are opened in sequence (such as the first shut-off valve V1, the eighth shut-off valve V11, the ninth shut-off valve V14, the tenth shut-off valve V15, the thirteenth shut-off valve V22, the fourteenth shut-off valve V24, etc., the specific valve opening and closing combination needs to form a purging flow path). Nitrogen gas is allowed to flow through all pipelines and containers requiring purification. The existing gas is replaced by brief venting at each exhaust point (such as safety valve interfaces and instrument interfaces). After purging, all outlet valves are closed, and nitrogen is introduced into the system to a certain pressure (usually 1.0-1.1 times the design or test pressure). The pressure data from the connected first pressure sensor P1, second pressure sensor P2, and third pressure sensor P3 are monitored in real time via the liquid methane PLC control unit 6. The pressure is maintained for a period of time (e.g., 30 minutes), and the pressure gauge readings are observed to ensure stability. If the pressure drop is within the allowable range, the airtightness is qualified; otherwise, the leak point needs to be located and repaired. After purging, close all outlet valves and fill the system with nitrogen to a certain pressure (usually 1.0-1.1 times the design pressure or test pressure). Monitor the pressure data of the connected first pressure sensor P1, second pressure sensor P2, and third pressure sensor P3 in real time through the liquid methane PLC control unit 6. Maintain the pressure for a period of time (e.g., 30 minutes) and observe whether the pressure gauge reading is stable. If the pressure drop is within the allowable range, the airtightness is qualified; otherwise, the leak point needs to be located and repaired.

[0117] The purpose of step one is to remove air, moisture, impurities, and any flammable gases from the entire test system (including the liquid methane storage tank, all pipelines, valves, and containers) to ensure a pure, inert environment within the system; at the same time, it is to test the system's sealing performance to prevent methane leakage from causing safety accidents during the test.

[0118] Step two involves adding liquid methane to the liquid methane storage tank 3 via the liquid methane supply unit to pre-cool the filling test pipeline 9. This specifically includes:

[0119] Remove air, moisture, impurities, and any flammable gases from the entire test system (including liquid methane storage tank 3, all pipelines, valves, and containers) to ensure a pure, inert environment. Simultaneously, test the system's sealing performance to prevent methane leakage and potential safety accidents during the test. Liquid methane mainly enters the liquid methane storage tank 3 through the pipeline after the first shut-off valve V1. The liquid level in the liquid methane storage tank 3 is monitored in real time using the level gauge 15 and its associated valve system (eleventh shut-off valve V17, twelfth shut-off valve V18, first needle valve V16, second needle valve V19, third needle valve V20, and fourth needle valve V21) until the predetermined level is reached. Open the fourteenth shut-off valve V24 (bypass valve) connected to the main pipeline of the filling test pipeline 9. Liquid methane flows out of liquid methane storage tank 3, passes through mass flow meter 8, and bypasses the automatic quick-opening valve V23. Instead, it flows through a section of the filling test pipeline 9 (especially the pipeline before quick-opening valve V23) and finally enters the horizontal methane storage tank 12. This process utilizes the cooling capacity of the liquid methane to initially cool the pipeline. During the pre-cooling process, the data monitoring unit 7 observes the readings of the various temperature sensors and wall thermocouples arranged on the filling test pipeline 9 in real time to monitor the cooling rate and temperature distribution of the pipeline, ensuring a smooth pre-cooling process and avoiding excessive thermal stress. The liquid methane PLC control unit 6 simultaneously monitors the pressure and temperature of liquid methane storage tank 3. When the temperature of the filling test pipeline 9, especially the pipeline before automatic quick-opening valve V23, stabilizes near the liquid methane saturation temperature and the temperature difference between each measuring point is small, the pre-cooling is considered complete, and the fourteenth shut-off valve V24 is closed to stop the bypass flow.

[0120] The purpose of step two is to add sufficient liquid methane into the liquid methane storage tank 3 and use the liquid methane to cool the room temperature filling test pipeline 9, so that its temperature is gradually reduced to close to the working temperature of liquid methane (about -161°C), so as to avoid the instability of two-phase flow, violent pressure fluctuation or water hammer caused by violent heat exchange during formal filling.

[0121] Step 3: The methane storage tank 3, after being filled with liquid methane, is pressurized by the liquid methane pressurization unit. During the pressurization process, the pressure of the liquid methane storage tank 3 is monitored in real time by the liquid methane PLC control unit. When the liquid methane PLC control unit detects that the pressure of the liquid methane storage tank 3 has reached the set value, it automatically triggers the opening of the filling test pipeline 9 and the liquid methane visualization observation unit, specifically including:

[0122] Open the fourth shut-off valve V6 and the fifth shut-off valve V7, and part of the liquid methane in the liquid methane storage tank 3 flows into the self-pressurizing vaporizer 5, absorbs ambient heat and vaporizes into gaseous methane, and then returns to the gas phase space of the liquid methane storage tank 3, increasing the pressure. At the same time, or as needed, open the seventh shut-off valve V10, and set the replenishment pressure through the first pressure regulating valve V9. Nitrogen gas enters the gas phase space of the liquid methane storage tank 3 from the nitrogen cylinder group 4 after pressure regulation to replenish the pressure. The two methods are used in combination to ensure stable and controllable pressurization. The liquid methane PLC control unit 6 monitors the pressure of the liquid methane storage tank 3 in real time through the second pressure sensor P2 and the third pressure sensor P3. The PLC control center 6 adjusts the pressurization rate and final pressure by controlling the opening of the first pressure regulating valve V9 or the opening and closing of the self-pressurization circuit valve based on the comparison between the set value and the feedback value. When the liquid methane PLC control unit 6 detects that the pressure of the liquid methane storage tank 3 reaches the preset test pressure value, it immediately sends two control signals at the same time: First, it triggers the automatic quick-opening valve V23 to open rapidly and fully, starting the transient filling of the main pipeline of the filling test pipeline 9 (especially the one containing the large cavity structure) with liquid methane; Second, it triggers the high-speed camera 11 to start shooting and record the fluid morphology changes of the liquid methane visualization observation section 10.

[0123] The purpose of step three is to increase the pressure of liquid methane storage tank 3 to the set value required for the test, so as to provide sufficient driving force for the subsequent transient filling process, and to start the filling process and observation equipment precisely and synchronously when the pressure reaches the set value through automated control.

[0124] Step four: The pressurized liquid methane enters the filling test pipeline 9 for transient filling. The data monitoring unit collects the parameter data of the filling test pipeline 9 in real time during the transient filling process, and visualizes the fluid morphology of the pressurized liquid methane during the transient filling process, specifically including:

[0125] Driven by differential pressure, liquid methane flows out of liquid methane storage tank 3, passes through mass flow meter 8, and enters the main pipeline of filling test pipeline 9 through the opened automatic quick-opening valve V23. The liquid methane flows sequentially through complex structures such as orifice plates, bends, and hemispherical containers 16, completing the filling of the large-volume pipeline. Mass flow meter 8 measures and records transient flow changes in real time, and the data is sent to PLC control unit 6 and data collection center 7 via mass flow transmitter M1. Data monitoring unit 7 synchronously collects data from all pressure and temperature sensors (including internal thermocouples and wall thermocouples) arranged on filling test pipeline 9 at millisecond-level frequency. These sensors are densely distributed before and after the orifice plate. The bends, inlets and outlets of the hemispherical container 16, and other key locations along the pipeline are used to capture details such as pressure fluctuations, temperature stratification, and vaporization during the filling process. The high-speed camera 11 captures the state of liquid methane flowing through the visualization section 10 (usually located at the end of the pipeline) at a high frame rate, recording whether the fluid is liquid, gas-liquid two-phase, or gas phase, as well as the transient changes in flow pattern (such as bubbly flow, slug flow, annular flow, etc.). The double-layer vacuum glass structure of the visualization section 10 ensures the clarity and safety of the observation. The liquid methane PLC control unit 6 continuously monitors the status of key points in the entire system (such as the pressure and level of the liquid methane storage tank 3, the inlet pressure P5 and temperature T4 of the recovery unit, etc.) to ensure the safe conduct of the experiment.

[0126] The purpose of step four is to comprehensively and accurately obtain transient change data of physical parameters such as flow rate, pressure, and temperature of the fluid in the pipeline during the rapid filling of the large-capacity pipeline at room temperature with liquid methane, and to visually observe the phase state and behavior of the fluid.

[0127] Step 5: After the transient filling is completed, the filling fluid is obtained. The filling fluid enters the liquid methane recovery unit for recovery, specifically including:

[0128] After the filling process continues for a predetermined time or reaches a predetermined condition, the operator closes the automatic quick-opening valve V23 through the liquid methane PLC control unit 6 to cut off the liquid methane supply. Simultaneously, stop the high-speed camera 11 from recording; open the relevant pressure relief valves or purge valves designed in the system (such as using the ninth shut-off valve V14, the tenth shut-off valve V15, etc.) to fill the test pipeline 9 and the methane gas guide liquid methane recovery unit in its subsequent pipelines. All recovered methane gas eventually enters the horizontal methane storage tank 12. The pressure and temperature of the horizontal methane storage tank 12 are monitored in real time by the fifth pressure sensor P5 and the fourth temperature sensor T4. Due to the huge volume of the storage tank (30,000 cubic meters), the pressure change caused by normal recovery is very small. If the storage tank pressure tends to rise due to the high temperature or large amount of recovered gas, the BOG (evaporated gas) reliquefaction cycle is started: the compressor 13 is turned on to extract the BOG at the top of the storage tank. After compression, it enters the cooler 14 for liquefaction. The liquefied methane returns to the horizontal methane storage tank 12 through the fifteenth shut-off valve V25, thereby effectively controlling the storage tank pressure and ensuring safety. After confirming that all methane has been recovered and the system pressure has dropped to a safe range, close all operating valves. The data recorded by the data monitoring unit and the visualization observation unit are saved and backed up. The experimental system is then restored to standby mode, ready for the next test or maintenance.

[0129] The purpose of step five is to safely terminate the filling test and recover the methane gas used during the filling process and any residual methane gas in the system, avoiding direct emissions that would cause waste and environmental pollution, while ensuring the safety of the storage tank.

[0130] In some embodiments, the experimental system needs to be debugged before it can be put into operation, including the following steps:

[0131] Step 1: Connect the PLC control center 6 to the test bench and ensure that the temperature, pressure, and flow data on the PLC control console are displayed normally, and that the automatic quick-opening valve V23 and high-speed camera 11 can be started normally.

[0132] Step 2: Sensor connection. Ensure that all temperature sensors T and pressure sensors P are functioning correctly and can record data, and that the values ​​are displayed correctly.

[0133] Step 3: Connect the vacuum pump to the visualization section 10 and ensure that the vacuum pump pressure display is normal;

[0134] Step 4: Purge and replace the entire system using the nitrogen supply unit;

[0135] Step 5: Hold the pressure for about half an hour, then observe the airtightness of the system and whether the pressure sensor display is normal;

[0136] Step Six: Pre-cool and inject liquid nitrogen, and observe whether the pressure, temperature, and liquid level in the 1.5 cubic meter liquid methane storage tank 3 are normal;

[0137] Step 7: Close the automatic quick-opening valve V23, open the fourteenth shut-off valve V24, pre-cool with a small flow of liquid nitrogen, observe for leaks, and check whether the flow, temperature and pressure sensors are functioning normally;

[0138] Step 8: Start the automatic quick-opening valve V23 at atmospheric pressure. Liquid nitrogen flows through the filling test pipeline 9 and the visualization section 10, gradually increasing the pressure inside the 1.5 cubic meter liquid methane storage tank 3, so that the flow rate gradually increases, allowing the test section to be immersed in liquid nitrogen. At the same time, record the measured pressure, temperature, and flow rate data.

[0139] Step 9: Verify whether the PLC control unit can automatically open under overpressure conditions;

[0140] Step 10: Verify whether the PLC control unit can achieve the function of pressurizing and stabilizing liquid discharge. Start the automatic quick-opening valve V23 and observe the pressure and temperature changes in the test section.

[0141] Step 11: Verify whether the liquid level drop in the PLC control unit is consistent with the measurement data of mass flow meter 8;

[0142] Step 12: After ensuring that there are no problems as described above, begin the formal liquid nitrogen commissioning test;

[0143] Step Thirteen: Begin the liquid methane filling test.

[0144] This invention establishes a highly accurate, stable, safe, and autonomous experimental system and method for testing large-volume liquid methane transient filling pipelines. It enables full-process data acquisition and coordinated control of the liquid methane storage unit, liquid methane filling unit, liquid methane visualization observation unit, and liquid methane recovery unit. It overcomes the limitations of millimeter-level fast-opening valve and camera autonomous opening technology and achieves millisecond-level data collection technology, significantly improving the accuracy of the liquid methane transient filling test process. Furthermore, by controlling the liquid methane pressurization unit, this invention regulates the temperature, flow rate, and pressure of the liquid methane at the filling pipeline inlet, enabling… This invention studies the physical state changes during the transient filling process of liquid methane under different operating conditions. A visualization observation section is set at the end of the filling pipeline using a double-layer quartz glass vacuum method, and millisecond-level imaging technology is achieved through a high-speed camera. This allows for real-time observation and recording of the methane morphology entering the engine, providing a more vivid understanding of the physical changes during the liquid methane filling process, in-depth research into the theoretical mechanism of this process, and precise guidance for the rocket ignition process. This invention is used to accurately measure the state changes of the fuel transient filling supply pipeline before the start-up of a cryogenic liquid rocket engine, providing technical support for the normal ignition sequence of the engine.

[0145] It should be noted that the pressure sensor, temperature sensor, mass flow meter, and level gauge used in the embodiments of the present invention all include data transmitters. These data transmitters belong to the liquid methane PLC control unit and data collection unit. For the sake of clarity in the accompanying drawings, the data transmitters are not shown. Therefore, the pressure transmitter, temperature transmitter, mass flow meter, and level gauge mentioned in the liquid methane PLC control unit and data collection unit correspond one-to-one with the pressure sensor, temperature sensor, mass flow meter, and level gauge in the accompanying drawings.

[0146] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0147] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A test system for testing the transient filling of a large-volume pipeline with liquid methane, characterized in that, include: Liquid methane storage unit, including liquid methane storage tank (3); A liquid methane supply unit is connected to a liquid methane storage tank (3); A nitrogen supply unit is connected to a liquid methane storage tank (3); The liquid methane pressurization unit is connected to the liquid methane storage tank (3) and the liquid methane supply unit, respectively; The liquid methane filling unit includes a filling test pipeline (9), the inlet of which is connected to the liquid methane storage tank (3), and the filling test pipeline (9) is connected to the liquid methane PLC control unit, the liquid methane visualization observation unit and the data monitoring unit respectively; it also includes a mass flow meter (8), a fourth full-lift safety valve (V26), a fourth pressure sensor (P4), a third temperature sensor (T3), an automatic quick-opening valve (V23) and a fourteenth shut-off valve (V24). The inlet of the filling test pipeline (9) is connected to the liquid methane storage tank (3) through the mass flow meter (8), and the pipeline between the mass flow meter (8) and the liquid methane storage tank (3) is connected to the liquid methane supply unit in sequence through the fourth full-lift safety valve (V26). The inlet of the filling test pipeline (9) is connected to a main pipeline, the automatic quick-opening valve (V23) is installed on the main pipeline, a bypass is connected in parallel on the main pipeline, and the fourteenth shut-off valve (V24) is installed on the bypass. The liquid methane recovery unit is connected to the liquid methane supply unit, the liquid methane pressurization unit, the outlet of the filling test pipeline (9), and the liquid methane storage unit, respectively. The liquid methane recovery unit is connected to the outlet of the main pipeline. The liquid methane PLC control unit is connected to the liquid methane recovery unit, the liquid methane pressurization unit, the liquid methane filling unit, and the liquid methane storage unit, respectively. The liquid methane PLC control unit is also connected to the automatic quick-opening valve (V23). The liquid methane visualization observation unit is connected to the filling test pipeline (9); The data monitoring unit is connected to the filling test pipeline (9).

2. The test system for testing the transient filling of a large-volume pipeline with liquid methane according to claim 1, characterized in that, The liquid methane recovery unit includes a horizontal methane storage tank (12), a compressor (13), a cooler (14), a fifteenth shut-off valve (V25), a fifth pressure sensor (P5), and a fourth temperature sensor (T4). The inlet of the horizontal methane storage tank (12) is connected to the outlet of the filling test pipeline (9). A fifth pressure sensor (P5) and a fourth temperature sensor (T4) are sequentially installed on the pipeline between the outlet of the filling test pipeline (9) and the inlet of the horizontal methane storage tank (12). The fifth pressure sensor (P5) and the fourth temperature sensor (T4) are respectively connected to the liquid methane PLC control unit. The outlet of the horizontal methane storage tank (12) is sequentially connected to the compressor (13) and the cooler (14). The cooler (14) is connected to the return port of the horizontal methane storage tank (12) through the fifteenth shut-off valve (V25).

3. The test system for testing the transient filling of a large-volume pipeline with liquid methane according to claim 2, characterized in that, The liquid methane supply unit includes a liquid methane supply plant (1), a first shut-off valve (V1), a third shut-off valve (V3), and a first full-opening safety valve (V4). The outlet of the liquid methane supply plant (1) is connected to the first liquid phase inlet and the first liquid phase outlet of the liquid methane storage tank (3) through the first shut-off valve (V1). The first pipeline between the first shut-off valve (V1) and the liquid methane storage tank (3) is connected to the inlet of the horizontal methane storage tank (12) through the first full-lift safety valve (V4). The second pipeline between the first shut-off valve (V1) and the liquid methane storage tank (3) is connected to the inlet of the horizontal methane storage tank (12) through the third shut-off valve (V3).

4. The test system for testing the transient filling of a large-volume pipeline with liquid methane according to claim 3, characterized in that, The liquid methane booster unit includes a room-temperature nitrogen manifold, exhaust, and replenishment booster device and a self-boosting device; The ambient temperature nitrogen manifold and pressurization device includes a nitrogen cylinder group (4), a first pressure regulating valve (V9), a seventh shut-off valve (V10), and a first pressure sensor (P1). The nitrogen cylinder group (4) is connected to the second liquid phase inlet of the liquid methane storage tank (3) in sequence through the first pressure regulating valve (V9) and the seventh shut-off valve (V10). The first pressure regulating valve (V9) is connected to the first pressure sensor (P1), and the first pressure sensor (P1) is connected to the liquid methane PLC control unit. The self-pressurizing device includes a self-pressurizing vaporizer (5), a second full-lift safety valve (V5), a fourth shut-off valve (V6), a fifth shut-off valve (V7), and a sixth shut-off valve (V8). The first inlet of the self-pressurizing vaporizer (5) is connected to the inlet of the horizontal methane storage tank (12) through the second full-lift safety valve (V5). The second inlet of the self-pressurizing vaporizer (5) is connected to the first liquid phase inlet of the liquid methane storage tank (3) through the fourth shut-off valve (V6). The outlet of the self-pressurizing vaporizer (5) is connected to the first liquid phase outlet of the liquid methane storage tank (3) through the fifth shut-off valve (V7). The pipeline between the fifth shut-off valve (V7) and the first liquid phase outlet of the liquid methane storage tank (3) is connected to the outlet of the liquid methane supply plant (1) in sequence through the sixth shut-off valve (V8) and the first shut-off valve (V1). The fourth shut-off valve (V6) is also connected to the first liquid phase outlet of the liquid methane storage tank (3) through the sixth shut-off valve (V8).

5. The test system for testing the transient filling of a large-volume pipeline with liquid methane according to claim 4, characterized in that, The inlet of the filling test pipeline (9) is connected to the second liquid phase outlet of the liquid methane storage tank (3) via a mass flow meter (8). The pipeline between the mass flow meter (8) and the second liquid phase outlet of the liquid methane storage tank (3) is connected to the outlet of the liquid methane supply plant (1) via a fourth full-lift safety valve (V26), a first full-lift safety valve (V4), and a first shut-off valve (V1). The automatic quick-opening valve (V23) and the hemispherical container (16) are installed sequentially on the main pipeline, and the outlet of the main pipeline is connected to the inlet of the horizontal methane storage tank (12).

6. The test system for testing the transient filling of a large-volume pipeline with liquid methane according to claim 5, characterized in that, The data monitoring unit includes several orifice plates, several parameter monitoring elements, several internal thermocouples, several wall thermocouples, and a data collection center (7). The orifice plates and parameter monitoring elements are installed on the main pipeline, the internal thermocouples are distributed along the length of the main pipeline, the wall thermocouples are distributed along the pipe side, and the orifice plates, parameter monitoring elements, wall thermocouples and internal thermocouples are connected to the data collection center (7).

7. The test system for testing the transient filling of a large-volume pipeline with liquid methane according to claim 5, characterized in that, The liquid methane storage unit also includes a level gauge (15), an eighth shut-off valve (V11), a second pressure regulating valve (V13), a ninth shut-off valve (V14), a tenth shut-off valve (V15), an eleventh shut-off valve (V17), a twelfth shut-off valve (V18), a thirteenth shut-off valve (V22), a first needle valve (V16), a second needle valve (V19), a third needle valve (V20), a fourth needle valve (V21), a third full-opening safety valve (V12), a first temperature sensor (T1), a second temperature sensor (T2), a second pressure sensor (P2), and a third pressure sensor (P3). The third liquid phase inlet of the liquid methane storage tank (3) is connected to the inlet of the horizontal methane storage tank (12) in sequence through the eighth shut-off valve (V11), the third full-lift safety valve (V12), and the thirteenth shut-off valve (V22). The first pipeline of the second liquid phase inlet of the liquid methane storage tank (3) is connected to the inlet of the horizontal methane storage tank (12) through the ninth shut-off valve (V14). The second pipeline of the second liquid phase inlet of the liquid methane storage tank (3) is connected to the inlet of the horizontal methane storage tank (12) in sequence through the second pressure regulating valve (V13) and the tenth shut-off valve (V15). The second pressure regulating valve (V13) is connected to the second pressure sensor (P2). The fourth liquid phase inlet of the liquid methane storage tank (3) is connected to the third liquid phase outlet of the liquid methane storage tank (3) in sequence through the eleventh shut-off valve (V17), the first needle valve (V16), the fourth needle valve (V21), the level gauge (15), the third needle valve (V20), and the twelfth shut-off valve (V18). The pipeline between the first needle valve (V16) and the twelfth shut-off valve (V18) is connected through the second needle valve (V19). The first temperature sensor (T1) is located between the third liquid phase inlet and the fourth liquid phase inlet of the liquid methane storage tank (3), the second temperature sensor (T2) is located on one side of the third liquid phase outlet of the liquid methane storage tank (3), the first needle valve (V16) is connected to the third pressure sensor (P3), and the second pressure sensor (P2), the third pressure sensor (P3), the first temperature sensor (T1) and the second temperature sensor (T2) are all connected to the liquid methane PLC control unit.

8. The test system for testing the transient filling of a large-volume pipeline with liquid methane according to claim 7, characterized in that, The liquid methane PLC control unit includes a PLC control center (6), a first pressure transmitter, a second pressure transmitter, a third pressure transmitter, a fourth pressure transmitter, a fifth pressure transmitter, a first temperature transmitter, a second temperature transmitter, a third temperature transmitter, a fourth temperature transmitter, a liquid level transmitter, and a mass flow transmitter (M1); the liquid methane filling unit also includes a fourth pressure sensor (P4) and a third temperature sensor (T3). The PLC control center (6) is connected to the first pressure transmitter, the second pressure transmitter, the third pressure transmitter, the fourth pressure transmitter, the fifth pressure transmitter, the first temperature transmitter, the second temperature transmitter, the third temperature transmitter, the fourth temperature transmitter, the level transmitter, and the mass flow transmitter (M1) respectively. The first pressure transmitter is connected to the first pressure sensor (P1), the second pressure transmitter is connected to the second pressure sensor (P2), the third pressure transmitter is connected to the third pressure sensor (P3), the fourth pressure transmitter is connected to the fourth pressure sensor (P4), the fifth pressure transmitter is connected to the fifth pressure sensor (P5), the first temperature transmitter is connected to the first temperature sensor (T1), the second temperature transmitter is connected to the second temperature sensor (T2), the third temperature transmitter is connected to the third temperature sensor (T3), the fourth temperature transmitter is connected to the fourth temperature sensor (T4), the level transmitter is connected to the level gauge (15), and the mass flow transmitter (M1) is connected to the mass flow meter (8).

9. The test system for testing the transient filling of a large-volume pipeline with liquid methane according to claim 1, characterized in that, The liquid methane visualization observation unit includes a visualization segment (10) and a camera (11). The visualization segment (10) is installed on the filling test pipeline (9), and the visualization segment (10) is connected to the camera (11) for signal transmission. The nitrogen supply unit includes a liquid nitrogen supply tanker (2) and a second shut-off valve (V2); The liquid nitrogen supply tanker (2) is connected to the first liquid phase inlet of the liquid methane storage tank (3) via the second shut-off valve (V2).

10. A test method for testing the transient filling of a large-volume pipeline with liquid methane, characterized in that, A test system for testing a large-volume pipeline with transient liquid methane filling, based on any one of claims 1-9, comprises the following steps: Nitrogen is introduced into the liquid methane storage tank (3) through the nitrogen supply unit to purge the pipeline and check its airtightness. Nitrogen supply is stopped after the airtightness check is completed. Liquid methane is added to the liquid methane storage tank (3) through the liquid methane supply unit; The liquid methane storage tank (3) is pressurized after being filled with liquid methane by the liquid methane pressurization unit. During the pressurization process, the pressure of the liquid methane storage tank (3) is monitored in real time by the liquid methane PLC control unit. When the liquid methane PLC control unit detects that the pressure of the liquid methane storage tank (3) reaches the set value, it automatically triggers the opening of the filling test pipeline (9) and the liquid methane visualization observation unit. The pressurized liquid methane enters the filling test pipeline (9) for transient filling. The data monitoring unit collects the parameter data of the filling test pipeline (9) in real time during the transient filling process and visualizes the fluid morphology of the pressurized liquid methane during the transient filling process. After the transient filling is completed, the filling fluid is obtained and enters the liquid methane recovery unit for recovery.

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