Liquid ammonia pipeline leakage experiment device and method

Abstract

The invention relates to a liquid ammonia pipeline leakage experiment device and method. The liquid ammonia pipeline leakage experiment device comprises a pipeline pressurization system, a power system, a data acquisition system and a leakage system, the pipeline pressurization system comprises an air compressor, a liquid ammonia tank, a pneumatic booster pump, a water bath constant temperature device and a buffer tank, the pneumatic booster pump is connected with the air compressor, the liquid ammonia tank and the buffer tank, and the water bath constant temperature device is connected with the buffer tank; the power system comprises a sliding vane pump and a mass flow meter, and the sliding vane pump is connected with the buffer tank and the mass flow meter; the data acquisition system comprises pressure transmitters and temperature transmitters which are electrically connected with the control module, and the plurality of pressure transmitters are distributed at the top of the experimental pipeline; the plurality of temperature transmitters are distributed at the bottom of the experimental pipeline; the leakage system comprises an opening adjusting valve and a leakage control valve, and the leakage control valve is arranged on the output side of the experiment pipeline. Accurate control over the ammonia phase state can be achieved, and the real flowing condition of fluid in the pipeline under the ammonia pipeline leakage working condition is simulated.

Description

Technical Field

[0001] This invention belongs to the field of liquid new energy pipeline technology, and particularly relates to a liquid ammonia pipeline leakage test device and method. Background Technology

[0002] With the increasing global demand for clean energy, countries are transitioning towards green energy. Liquid ammonia, as a hydrogen-rich energy carrier, possesses significant advantages such as high energy density and low storage and transportation costs, demonstrating enormous potential in the global energy transition. Liquid ammonia pipeline systems, as a large-scale, long-distance, economical, and safe method of ammonia transportation, can effectively solve current challenges in hydrogen storage and transportation. However, during liquid ammonia pipeline transportation, ruptures and leaks are inevitable due to human error or inherent defects. Rapid leakage of liquid ammonia within the pipeline leads to a sudden drop in temperature and pressure, increasing the risk of low-temperature brittle fracture failure; furthermore, the toxic nature of high-concentration ammonia can cause serious problems such as personal injury and environmental pollution. Therefore, it is necessary to conduct research on the characteristics of liquid ammonia pipeline leakage processes to provide guidance and reference for the prediction and control of such accidents.

[0003] Due to the limited length of long-distance liquid ammonia pipelines in China, industry standards and design specifications are still immature, making it difficult to effectively guide their design, construction, and operation. Furthermore, existing research on liquid ammonia leaks primarily focuses on storage tanks, concentrating on near-field multiphase jetting during ammonia leakage into the atmosphere and far-field diffusion phenomena after leakage. Therefore, experimental testing studies on liquid ammonia pipeline leaks are not yet reported, and the evolution of characteristic parameters in this process remains poorly understood.

[0004] To address these challenges, it is urgent to build a liquid ammonia pipeline leakage test platform that integrates high-frequency data acquisition, high-precision temperature and pressure control, and phase adjustment to achieve simulation testing of various pipeline leakage accident conditions. Summary of the Invention

[0005] The present invention addresses the problems existing in the prior art, namely, the technical problem to be solved by the present invention is to provide a liquid ammonia pipeline leakage test device and method.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a liquid ammonia pipeline leakage test device, comprising a pipeline pressurization system, a power system, a data acquisition system, and a leakage system; The pipeline pressurization system includes an air compressor, a liquid ammonia tank, a pneumatic booster pump, a water bath thermostat, and a buffer tank. The drive inlet of the pneumatic booster pump is connected to the air compressor, the pre-boost inlet of the pneumatic booster pump is connected to the liquid ammonia tank, the high-pressure outlet of the pneumatic booster pump is connected to the inlet of the buffer tank, and the water bath thermostat is connected to the buffer tank. The power system includes a vane pump and a mass flow meter. The inlet of the vane pump is connected to the outlet of the buffer tank, and the outlet of the vane pump is connected to the mass flow meter. The mass flow meter is installed on the input side of the experimental pipeline. The data acquisition system includes pressure transmitters and temperature transmitters electrically connected to the control module. There are multiple pressure transmitters, which are distributed along the axial direction of the experimental pipeline at the top of the experimental pipeline. There are also multiple temperature transmitters, which are distributed along the axial direction of the experimental pipeline at the bottom of the experimental pipeline. The leakage system includes an opening regulating valve and a leakage control valve. The opening regulating valve is located between the experimental pipeline and the mass flow meter; the leakage control valve is located on the output side of the experimental pipeline.

[0007] Furthermore, the water bath thermostat is wrapped around the outside of the buffer tank.

[0008] Furthermore, a first manual ball valve is installed in the pipeline between the air compressor and the drive air inlet of the pneumatic booster pump; a second manual ball valve is installed in the pipeline between the liquid ammonia tank and the pre-boost air inlet of the pneumatic booster pump; a third manual ball valve is installed in the pipeline between the high-pressure outlet of the pneumatic booster pump and the inlet of the buffer tank, and a first pneumatic switch valve is installed on the output side of the third manual ball valve.

[0009] Furthermore, a second pneumatic switching valve is installed in the pipeline between the inlet of the vane pump and the outlet of the buffer tank.

[0010] Furthermore, a check valve is installed in the pipeline between the outlet of the vane pump and the mass flow meter.

[0011] Furthermore, the vane pump is connected to the frequency converter.

[0012] Furthermore, the multiple pressure transmitters include a first pressure transmitter, a second pressure transmitter, and a third pressure transmitter, which are spaced apart from the end of the test pipeline to the leak end; the multiple temperature transmitters include a first temperature transmitter, a second temperature transmitter, and a third temperature transmitter, which are spaced apart from the end of the test pipeline to the leak end. The first pressure transmitter and the first temperature transmitter are located on the same cross-section of the pipeline, the second pressure transmitter and the second temperature transmitter are located on the same cross-section of the pipeline, and the third pressure transmitter and the third temperature transmitter are located on the same cross-section of the pipeline.

[0013] Furthermore, the data acquisition system also includes a viewing window and a camera. The viewing window is connected to the experimental pipeline, and a third pneumatic switch valve is provided between the viewing window and the opening adjustment valve. The camera captures the flow state and phase changes of liquid ammonia inside the experimental pipeline through the viewing window, and the camera is connected to the control module.

[0014] Furthermore, the leakage system also includes an exhaust hose and an absorption tower, with one end of the exhaust hose connected to a leakage control valve and the other end of the exhaust hose connected to the absorption tower.

[0015] Another technical solution adopted in this invention is: a method for testing leakage in a liquid ammonia pipeline, the method comprising the following steps: Step S1: Open the first manual ball valve, the second manual ball valve, the third manual ball valve, and the first pneumatic switch valve in the order of flow direction. The liquid ammonia in the liquid ammonia tank enters the buffer tank through the pneumatic booster pump. Then, close the first pneumatic switch valve and turn on the water bath constant temperature device, set the corresponding working temperature, and control the temperature of the liquid ammonia in the buffer tank. Step S2: Open the second pneumatic switch valve, the opening adjustment valve, and the third pneumatic switch valve in the order of flow direction. Then start the vane pump. The liquid ammonia in the buffer tank passes through the vane pump and finally enters the experimental pipeline. Step S3: Control the opening degree through the opening adjustment valve, and at the same time control the speed of the vane pump to provide power for the liquid ammonia production, thereby controlling the ammonia flow rate in the pipeline; observe the liquid ammonia flow state and phase change inside the experimental pipeline through the viewing window, and observe the liquid ammonia flow rate through the mass flow meter until the liquid ammonia in the viewing window is in a full flow state and the mass flow meter reading is 0. Step S4: After observing the liquid ammonia in the experimental pipe through the viewing window for 5 seconds, reduce the opening of the control valve until it is closed, and at the same time turn off the vane pump to achieve a full and closed state of the experimental pipe section. Step S5: Use the first pressure transmitter, the second pressure transmitter, the third pressure transmitter, the first temperature transmitter, the second temperature transmitter, and the third temperature transmitter to record the pipeline pressure and temperature. Step S6: After the liquid ammonia in the closed experimental pipe section stabilizes, open the leakage control valve to conduct a leakage test and collect data. The control module program is set to the following settings: for the first 30 seconds, the acquisition frequency of the first, second, and third pressure transmitters is 100 kHz, and the acquisition frequency of the first, second, and third temperature transmitters is 50 Hz; after 30 seconds, the acquisition frequency of the first, second, and third pressure transmitters, as well as the first, second, second, and third temperature transmitters, is 50 Hz. Step S7: Observe the pressure value on the control module acquisition program. When the pressure value is displayed as 0.001MPa, close the leakage control valve, end the data storage of the control module, save the experimental data, and the experiment test ends.

[0016] Compared with the prior art, the present invention has the following advantages: The present invention is reasonably designed and can achieve precise control of the ammonia phase, simulate the real flow of fluid in the pipeline under the condition of ammonia pipeline leakage, and collect transient changes of physical parameters in the pipeline at high frequency. In particular, under the condition of leakage, it can accurately observe and record the temperature, pressure, decompression wave and phase changes of ammonia in the pipeline, and can analyze the influence of initial conditions such as pressure, temperature, leakage orifice diameter and pipeline length on the phase changes and transient flow characteristics in the pipeline. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention; Figure 2 This is a schematic diagram showing the distribution of pressure transmitters and temperature transmitters in an embodiment of the present invention.

[0018] In the picture: 1-Air compressor; 2-Liquid ammonia tank; 301-First manual ball valve; 302-Second manual ball valve; 303-Third manual ball valve; 4-Pneumatic booster pump; 501-First pneumatic switch valve; 502-Second pneumatic switch valve; 503-Third pneumatic switch valve; 6-Water bath thermostat; 7-Buffer tank; 8-Sliding vane pump; 9-Frequency converter; 10-Check valve; 11-Mass flow meter; 12-Opening regulating valve; 1301-First pressure transmitter; 1302-Second pressure transmitter; 1303-Third pressure transmitter; 1401-First temperature transmitter; 1402-Second temperature transmitter; 1403-Third temperature transmitter; 15-Viewing window; 16-Camera; 17-Computer; 18-Leakage regulating valve; 19-Exhaust hose; 20-Absorption tower; 21-Experimental pipeline. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0020] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0021] The following example uses a liquid ammonia pipeline leak. The experimental pipeline consists of a 18-m long pipe with an inner diameter of 26 mm. The viewing window is made of transparent plexiglass, while the other pipe sections are made of 304 stainless steel. The outer walls of the pipe sections are all covered with 3 mm thick aluminum foil insulation sleeves.

[0022] like Figures 1-2 As shown, the present invention provides a liquid ammonia pipeline leakage test device, which includes a pipeline pressurization system, a power system, a data acquisition system, and a leakage system.

[0023] The pipeline pressurization system includes an air compressor 1, a liquid ammonia tank 2, a pneumatic booster pump 4, a water bath thermostat 6, and a buffer tank 7. The drive inlet of the pneumatic booster pump 4 is connected to the air compressor 1, the pre-boost inlet of the pneumatic booster pump 4 is connected to the liquid ammonia tank 2, and the high-pressure outlet of the pneumatic booster pump 4 is connected to the inlet of the buffer tank 7. The water bath thermostat 6 is connected to the buffer tank 7 and is used to heat and control the temperature of the buffer tank. Using the liquid ammonia tank 2 as the ammonia source, the temperature and pressure of the liquid ammonia in the buffer tank can be controlled by controlling the air compressor 1, the pneumatic booster pump 4, and the water bath thermostat 6 surrounding the buffer tank.

[0024] The power system includes a vane pump 8 and a mass flow meter 11. The inlet of the vane pump 8 is connected to the outlet of the buffer tank 7, and the outlet of the vane pump 8 is connected to the mass flow meter 11, which is installed on the input side of the experimental pipeline 21. The vane pump 8 uses vanes and has good self-priming performance, enabling it to handle gas-containing liquids effectively and provide power for the initial commissioning process of the liquid ammonia pipeline.

[0025] The data acquisition system includes pressure transmitters and temperature transmitters electrically connected to the control module. There are multiple pressure transmitters, which are distributed along the axial direction of the experimental pipe 21 at the top of the experimental pipe 21. There are also multiple temperature transmitters, which are distributed along the axial direction of the experimental pipe 21 at the bottom of the experimental pipe 21.

[0026] The leakage system includes an opening regulating valve 12 and a leakage control valve 18. The opening regulating valve 12 is located between the experimental pipeline 21 and the mass flow meter 11. The leakage control valve is located on the output side of the experimental pipeline 21 and is used to control the opening and closing of the leakage experiment.

[0027] In this embodiment, the water bath constant temperature device 6 surrounds the outside of the buffer tank 7.

[0028] In this embodiment, in the pipeline pressurization system, a first manual ball valve 301 is provided in the pipeline between the air compressor 1 and the drive air inlet of the pneumatic booster pump 4; a second manual ball valve 302 is provided in the pipeline between the liquid ammonia tank 2 and the pre-boost air inlet of the pneumatic booster pump 4; a third manual ball valve 303 is provided in the pipeline between the high-pressure outlet of the pneumatic booster pump 4 and the inlet of the buffer tank 7, and a first pneumatic switch valve 501 is provided on the output side of the third manual ball valve 303.

[0029] In this embodiment, a second pneumatic switching valve 502 is provided in the pipeline between the inlet of the vane pump 8 and the outlet of the buffer tank 7 in the power system.

[0030] In this embodiment, a check valve 10 is installed in the pipeline between the outlet of the vane pump 8 and the mass flow meter 11 in the power system.

[0031] In this embodiment, in the power system, the vane pump 8 is connected to the frequency converter 9, and the speed of the vane pump is adjusted by the frequency converter.

[0032] In this embodiment, in the data acquisition system, multiple pressure transmitters are included, extending from the end of the experimental pipeline 21 to the leak end (i.e., Figure 2 The pressure transmitters 1301, 1302, and 1303 are spaced apart from right to left in the middle; multiple temperature transmitters are distributed from the end of the experimental pipe 21 to the leak end (i.e., Figure 2 The temperature transmitters 1401, 1402, and 1403 are spaced apart from right to left. Each pressure transmitter, temperature transmitter, and mass flow meter can be connected to the control module via a data cable, allowing for real-time monitoring, data storage, and plotting of corresponding transient response curves. Furthermore, the arrangement of the pressure and temperature transmitters is as follows... Figure 2 As shown, multiple pressure transmitters are positioned corresponding to multiple temperature transmitters. Specifically, the first pressure transmitter 1301 and the first temperature transmitter 1401 are located on the same cross-section of the experimental pipeline, the second pressure transmitter 1302 and the second temperature transmitter 1402 are located on the same cross-section of the experimental pipeline, and the third pressure transmitter 1303 and the third temperature transmitter 1403 are located on the same cross-section of the experimental pipeline, measuring the changes in pressure and temperature inside the pipe at different locations along the pipeline.

[0033] In this embodiment, the first pressure transmitter 1301, the second pressure transmitter 1302, and the third pressure transmitter 1303 can be 100kHz high-frequency pressure transmitters; the first temperature transmitter 1401, the second temperature transmitter 1402, and the third temperature transmitter 1403 can be 50Hz temperature transmitters.

[0034] In this embodiment, the data acquisition system further includes a viewing window 15 and a camera 16. The viewing window is connected to the experimental pipeline, and a third pneumatic switch valve 503 is installed between the viewing window 15 and the opening adjustment valve 12. The third pneumatic switch valve 503 is installed in the experimental pipeline. The camera 16 is positioned corresponding to the viewing window 15, and the camera 16 captures the flow state and phase changes of liquid ammonia inside the experimental pipeline 21 through the viewing window 15. The camera 16 is connected to the control module. Furthermore, a high-speed camera is used. The viewing window 15 can withstand a pressure of 5MPa, and the transient changes of the fluid during commissioning and leakage can be observed through the viewing window.

[0035] In this embodiment, the leakage system further includes an exhaust hose 19 and an absorption tower 20. One end of the exhaust hose 19 is connected to the leakage control valve 18, and the other end of the exhaust hose 19 is connected to the absorption tower 20.

[0036] In this embodiment, the control module includes a computer 7 equipped with a data acquisition card. The camera 16, the first pressure transmitter 1301, the second pressure transmitter 1302, the third pressure transmitter 1303, the first temperature transmitter 1401, the second temperature transmitter 1402, the third temperature transmitter 1403, and the mass flow meter 11 can all be connected to the computer 7 via data cables, which can monitor and store data in real time and plot the corresponding transient response curves.

[0037] In this embodiment, the first pneumatic switching valve 501, the second pneumatic switching valve 502, the third pneumatic switching valve 503, and the leakage control valve 18 can all be electro-pneumatic valves, such as the JKYQ-320P model. The valve body and sealing materials undergo special low-temperature treatment to withstand -40 degrees Celsius and have a maximum pressure resistance of 32 MPa. The opening adjustment valve 12 is the CLT0-02T model, driven by a 24 VDC input voltage, with a rated torque of 20 N•m. The input signal is adjusted via an external signal generator to achieve precise adjustment of the valve opening. Simultaneously, a vane pump and a frequency converter are used to control the flow rate of liquid ammonia when it is added to the experimental pipeline. The liquid level changes in the viewing window are observed, and the valve opening and liquid ammonia flow rate are adjusted in a timely manner to ensure the experimental pipeline is full of liquid.

[0038] It should be noted that the leaking end of the experimental pipeline has a leak hole, and the leak control valve 18 is used to control the opening or closing of the leak hole.

[0039] In this embodiment, to ensure the piping system is free of impurities during the formal experiment, the specific operating steps include: controlling the pressure reducing valve at the nitrogen cylinder outlet to introduce low-pressure nitrogen gas at 0.2 MPa; opening valves sequentially according to the flow direction (storage tank, pump chamber, experimental pipe section); the purging time for each pipe section depends on the size of the chamber; and ensuring that all moisture and impurities in the system are completely removed to prevent ammonia from dissolving in water during ammonia purging. A white cloth is placed at the outlet of the experimental pipe section, and the absence of watermarks and impurities on the cloth within 10 consecutive minutes indicates whether the purging is complete. Then, ammonia gas at a relatively higher pressure is introduced to purge the nitrogen, following the same operating steps as the nitrogen purging, with a purging time of no less than 10 minutes.

[0040] It should be noted that electrical equipment such as data acquisition systems, frequency converters, and transmitters must be grounded and subjected to insulation tests to avoid electromagnetic interference or malfunction of instruments and equipment affecting the accuracy of experimental results.

[0041] In this embodiment, the vane pump 8, the pneumatic booster pump 4, and the water bath thermostat 6 are all electrically connected to the computer 7 and are controlled by the computer to start and stop.

[0042] In this embodiment, the liquid ammonia pipeline leakage test method can accurately collect temperature, pressure, mass flow rate, and phase changes within the pipeline at high frequency under set operating conditions. The method includes the following steps: Step S1: Open the first manual ball valve 301, the second manual ball valve 302, the third manual ball valve 303, and the first pneumatic switch valve 501 in the order of flow direction. The liquid ammonia in the liquid ammonia tank 2 enters the buffer tank 7 through the pneumatic booster pump 4. Then close the first pneumatic switch valve 501, turn on the water bath constant temperature device 6, set the corresponding working temperature, and control the temperature of the liquid ammonia in the buffer tank 7. Step S2: Open the second pneumatic switch valve 502, the opening adjustment valve 12, and the third pneumatic switch valve 503 in the order of flow direction. Then start the vane pump 8. The liquid ammonia in the buffer tank 7 passes through the vane pump 8 and finally enters the experimental pipeline 21. Step S3: Control the opening degree through the opening adjustment valve 12, and use the frequency converter 9 to control the speed of the vane pump 8 to provide power for the liquid ammonia production, thereby controlling the ammonia flow rate in the experimental pipeline; observe the liquid ammonia flow state and phase change inside the experimental pipeline 21 through the viewing window 15, and observe the liquid ammonia flow rate through the mass flow meter 11 until the liquid ammonia in the viewing window 15 is in a full flow state and the mass flow meter 11 reading is 0; Step S4: After observing through the viewing window 15 that the liquid ammonia in the experimental pipe 21 is in a full flow state for 5 seconds, control the opening of the opening regulating valve 12 until it is closed, and at the same time turn off the vane pump 8 to achieve the experimental pipe section 21 being full of liquid and closed. Step S5: Use a 100kHz first pressure transmitter 130, a 100kHz second pressure transmitter 1302, a 100kHz third pressure transmitter 1303, a 50Hz first temperature transmitter 1401, a 50Hz second temperature transmitter 1402, and a 50Hz third temperature transmitter 1403 to record the pipeline pressure and temperature. Step S6: After the liquid ammonia in the closed experimental pipe section stabilizes, open the leakage control valve 18 to conduct a leakage test. Simultaneously, start the data acquisition on the computer to collect data. The program is set to the following settings: for the first 30 seconds, the acquisition frequency of the first pressure transmitter 1301, the second pressure transmitter 1302, and the third pressure transmitter 1303 is 100 kHz, and the acquisition frequency of the first temperature transmitter 1401, the second temperature transmitter 1402, and the third temperature transmitter 1403 is 50 Hz; after 30 seconds, the acquisition frequency of the first pressure transmitter 1301, the second pressure transmitter 1302, the third pressure transmitter 1303, the first temperature transmitter 1401, the second temperature transmitter 1402, and the third temperature transmitter 1403 is 50 Hz. Step S7: Observe the pressure value on the control module acquisition program. When the pressure value is displayed as 0.001MPa, close the leakage control valve 18, and at the same time end the computer data storage, save the experimental data, and the experimental test ends.

[0043] This invention utilizes a water bath thermostat, a pneumatic booster pump, and a vane pump to regulate the temperature and pressure of liquid ammonia, achieving precise control of temperature and pressure within liquid ammonia pipelines. Pressure transmitters, temperature transmitters, and mass flow meters are connected to a data acquisition card, which in turn connects to a computer via a data cable. Programming software on the computer monitors and stores changes in the instrument acquisition frequency. Simultaneously, the computer directly controls the start / stop and power of the vane pump, pneumatic booster pump, and water bath thermostat, providing significant convenience for researchers. In summary, this invention allows for leakage experiments under various accident conditions by injecting liquid ammonia into pipelines. The experiments are characterized by short cycles, high accuracy, strong observability, and high measurement precision and acquisition frequency, providing guidance for liquid ammonia pipeline design and safety control schemes.

[0044] The advantages of this invention are: (1) It can achieve precise control of the ammonia phase state, simulate the real flow of fluid in the pipeline under the condition of ammonia pipeline leakage, and collect the transient changes of physical parameters in the pipeline at high frequency. Especially under the condition of leakage, it can accurately observe and record the temperature, pressure, decompression wave and phase state changes of ammonia in the pipeline, and analyze the influence of initial conditions such as pressure, temperature, leakage orifice diameter and pipeline length on the phase state changes and transient flow characteristics in the pipeline. (2) Able to collect various test data and plot parameter change curves through a computer; (3) It has advantages such as high measurement accuracy, high acquisition frequency, strong visibility, intuitive experimental results, good safety performance and convenient operation, which are of great significance for formulating pipeline design and safety control schemes.

[0045] If this invention discloses or relates to components or structural parts that are fixedly connected to each other, then, unless otherwise stated, a fixed connection can be understood as: a fixed connection that can be detached (e.g., using bolts or screws), or a fixed connection that cannot be detached (e.g., riveting, welding). Of course, a fixed connection can also be replaced by an integral structure (e.g., manufactured in one piece using a casting process) (except where it is obviously impossible to use an integral molding process).

[0046] In addition, unless otherwise stated, the terms used in any of the technical solutions disclosed in this invention to indicate positional relationships or shapes include states or shapes that are similar to, close to, or approximate with those states or shapes.

[0047] Any component provided by this invention can be assembled from multiple individual components or can be a single component manufactured by a one-piece molding process.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A liquid ammonia pipeline leakage test apparatus, characterized in that: This includes pipeline pressurization systems, power systems, data acquisition systems, and leakage systems; The pipeline pressurization system includes an air compressor, a liquid ammonia tank, a pneumatic booster pump, a water bath thermostat, and a buffer tank. The drive inlet of the pneumatic booster pump is connected to the air compressor, the pre-boost inlet of the pneumatic booster pump is connected to the liquid ammonia tank, the high-pressure outlet of the pneumatic booster pump is connected to the inlet of the buffer tank, and the water bath thermostat is connected to the buffer tank. The power system includes a vane pump and a mass flow meter. The inlet of the vane pump is connected to the outlet of the buffer tank, and the outlet of the vane pump is connected to the mass flow meter. The mass flow meter is installed on the input side of the experimental pipeline. The data acquisition system includes pressure transmitters and temperature transmitters electrically connected to the control module. There are multiple pressure transmitters, which are distributed along the axial direction of the experimental pipeline at the top of the experimental pipeline. There are also multiple temperature transmitters, which are distributed along the axial direction of the experimental pipeline at the bottom of the experimental pipeline. The leakage system includes an opening regulating valve and a leakage control valve. The opening regulating valve is located between the experimental pipeline and the mass flow meter; the leakage control valve is located at the leakage end of the experimental pipeline.

2. The liquid ammonia pipeline leakage test device according to claim 1, characterized in that: The water bath thermostat is wrapped around the outside of the buffer tank.

3. The liquid ammonia pipeline leakage test apparatus according to claim 1, characterized in that: A first manual ball valve is installed in the pipeline between the air compressor and the drive air inlet of the pneumatic booster pump; a second manual ball valve is installed in the pipeline between the liquid ammonia tank and the pre-boost air inlet of the pneumatic booster pump; a third manual ball valve is installed in the pipeline between the high-pressure outlet of the pneumatic booster pump and the inlet of the buffer tank, and a first pneumatic switch valve is installed on the output side of the third manual ball valve.

4. The liquid ammonia pipeline leakage test apparatus according to claim 3, characterized in that: A second pneumatic switch valve is installed in the pipeline between the inlet of the vane pump and the outlet of the buffer tank.

5. The liquid ammonia pipeline leakage test apparatus according to claim 1, characterized in that: A check valve is installed in the pipeline between the outlet of the vane pump and the mass flow meter.

6. The liquid ammonia pipeline leakage test apparatus according to claim 1, characterized in that: The vane pump is connected to the frequency converter.

7. The liquid ammonia pipeline leakage test apparatus according to claim 4, characterized in that: Multiple pressure transmitters include a first pressure transmitter, a second pressure transmitter, and a third pressure transmitter, which are spaced apart from the end of the test pipeline to the leak end; multiple temperature transmitters include a first temperature transmitter, a second temperature transmitter, and a third temperature transmitter, which are spaced apart from the end of the test pipeline to the leak end. The first pressure transmitter and the first temperature transmitter are located on the same cross-section of the pipeline, the second pressure transmitter and the second temperature transmitter are located on the same cross-section of the pipeline, and the third pressure transmitter and the third temperature transmitter are located on the same cross-section of the pipeline.

8. The liquid ammonia pipeline leakage test apparatus according to claim 7, characterized in that: The data acquisition system also includes a viewing window and a camera. The viewing window is connected to the experimental pipeline, and a third pneumatic switch valve is provided between the viewing window and the opening adjustment valve. The camera captures the flow state and phase changes of liquid ammonia inside the experimental pipeline through the viewing window, and the camera is connected to the control module.

9. The liquid ammonia pipeline leakage test apparatus according to claim 1, characterized in that: The leakage system also includes an exhaust hose and an absorption tower. One end of the exhaust hose is connected to a leakage control valve, and the other end of the exhaust hose is connected to the absorption tower.

10. A method for testing leakage in a liquid ammonia pipeline, characterized in that: The method includes using the liquid ammonia pipeline leakage test apparatus as described in claim 8, and the method comprises the following steps: Step S1: Open the first manual ball valve, the second manual ball valve, the third manual ball valve, and the first pneumatic switch valve in the order of flow direction. The liquid ammonia in the liquid ammonia tank enters the buffer tank through the pneumatic booster pump. Then, close the first pneumatic switch valve and turn on the water bath constant temperature device, set the corresponding working temperature, and control the temperature of the liquid ammonia in the buffer tank. Step S2: After opening the second pneumatic switch valve, the opening adjustment valve, and the third pneumatic switch valve in the order of flow direction, start the vane pump. The liquid ammonia in the buffer tank passes through the vane pump and finally enters the experimental pipeline. Step S3: Control the opening degree through the opening adjustment valve, and at the same time control the speed of the vane pump to provide power for the liquid ammonia production, thereby controlling the ammonia flow rate in the pipeline; observe the liquid ammonia flow state and phase change inside the experimental pipeline through the viewing window, and observe the liquid ammonia flow rate through the mass flow meter until the liquid ammonia in the viewing window is in a full flow state and the mass flow meter reading is 0. Step S4: After observing the liquid ammonia in the experimental pipe through the viewing window for 5 seconds, reduce the opening of the control valve until it is closed, and at the same time turn off the vane pump to achieve a full and closed state of the experimental pipe section. Step S5: Use the first pressure transmitter, the second pressure transmitter, the third pressure transmitter, the first temperature transmitter, the second temperature transmitter, and the third temperature transmitter to record the pipeline pressure and temperature. Step S6: After the liquid ammonia in the closed experimental pipe section stabilizes, open the leakage control valve to conduct a leakage test and collect data. The control module program is set to the following settings: for the first 30 seconds, the acquisition frequency of the first, second, and third pressure transmitters is 100 kHz, and the acquisition frequency of the first, second, and third temperature transmitters is 50 Hz; after 30 seconds, the acquisition frequency of the first, second, and third pressure transmitters, as well as the first, second, second, and third temperature transmitters, is 50 Hz. Step S7: Observe the pressure value on the control module acquisition program. When the pressure value is displayed as 0.001MPa, close the leakage control valve, end the data storage of the control module, save the experimental data, and the experiment test ends.

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