A method for simulating boiling of a leaking LNG pool
By integrating experimental platforms and using precise control methods, the problems of low accuracy and poor repeatability of LNG leakage experimental data were solved, enabling high-precision and safe LNG pool boiling simulation experiments and obtaining reliable boiling characteristic data.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- RES INST OF CHEM DEFENSE PLA ACAD OF MILITARY SCI
- Filing Date
- 2026-05-05
- Publication Date
- 2026-07-14
AI Technical Summary
Existing LNG leakage experimental data suffers from low accuracy and poor repeatability, mismatched thermophysical properties of substitutes, and a lack of dedicated small- to medium-scale LNG leakage pool boiling simulation experimental methods.
An integrated experimental platform is adopted, including LNG storage tanks, insulated pipelines, liquid pool simulation devices, data acquisition instruments and PLC control system. By pre-cooling the insulated pipelines, accurately controlling the LNG introduction volume and data acquisition frequency, and combining real-time monitoring of methane concentration with linkage to the emergency system, a high-precision, safe and controllable experimental process is achieved.
High-precision and highly repeatable experiments on the boiling process of small- to medium-scale LNG pools were achieved, accurate boiling characteristic data were obtained, safety hazards were eliminated, and the accuracy and repeatability of the data were improved.
Smart Images
Figure CN122385667A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of hazardous chemical leakage mechanism research, specifically to a method for simulating boiling in a leaking LNG pool. Background Technology
[0002] LNG (Liquid Gas) is a liquid product obtained by cooling and compressing natural gas to its freezing point (-162°C). It is a core technology for long-distance transportation and large-scale storage of natural gas. As a typical cryogenic fluid, LNG has characteristics such as low boiling point, low density, low latent heat of vaporization, high compressibility, and strong temperature sensitivity. When a large amount of LNG leaks onto the ground or the surface of an installation, it will form a cryogenic liquid pool within a certain range, which may cause various hazards such as cryogenic brittle fracture of equipment, vapor cloud explosion, and pool fire. Studying the pool boiling characteristics of LNG leaks on different solid surfaces is of great significance for conducting practical or theoretical research on LNG leak disaster control.
[0003] Current experimental research on LNG leak safety accidents mainly focuses on large-scale LNG leaks on land or water, including the diffusion of flammable and explosive gas clouds, the consequences of fire and explosion, and risk assessment. However, the data from these large-scale experiments have low precision and poor repeatability, making them suitable only for engineering research. Considering safety issues, experiments studying the flow, pool boiling, and vapor diffusion of leaked LNG through small- to medium-scale simulations mostly use LN2 as a safe alternative to LNG. However, the thermophysical properties of these two cryogenic fluids differ significantly, making it difficult to generalize the conclusions to practical applications.
[0004] Therefore, there is an urgent need for a method to simulate the boiling of leaked LNG pools on a small to medium scale, with high precision, safety, controllability, and repeatability. Summary of the Invention
[0005] (a) Technical problems to be solved This invention aims to solve the technical problems of low accuracy, poor repeatability, mismatch of thermophysical properties of substitutes, and lack of dedicated boiling simulation experimental methods for leaked LNG pools in existing LNG leakage experiments, and to achieve accurate, safe, and repeatable testing of the boiling characteristics of leaked LNG pools on different solid surfaces at small and medium scales.
[0006] (II) Technical Solution To address the aforementioned problems, this invention proposes a method for simulating boiling in a leaking LNG pool. This method is based on an integrated experimental platform, such as... Figure 1As shown, the platform mainly includes an LNG storage tank 1, insulated pipelines 9, a liquid pool simulation device 17, an insulation layer 16, an electronic balance 19, thermocouples 18, a methane concentration sensor array 20, a data acquisition instrument 23, a weather instrument 21, a camera 22, a fine water mist truck 25, a water supply pipe 26, water mist nozzles 29, an explosion-proof isolation wall 11, a wooden floor 12, an anti-static floor 13, a roof 15, an exhaust skylight 14, and a PLC control system 24. The connection relationships of each component are shown in [reference needed]. Figures 1 to 4 The overall approach is to complete the four stages of experiment preparation, LNG export, data acquisition and safety monitoring, and experiment completion in sequence according to the preset procedure, so as to obtain high-precision boiling characteristic data while ensuring safety.
[0007] Specifically, the method of the present invention includes the following steps: S1: Experimental Preparation First, check the condition of the storage tank: observe whether there is frost or obvious damage to LNG storage tank 1 and insulation pipeline 9, confirm that the gas pressure in LNG storage tank 1 is within the working range by using the first pressure gauge 4, and check that the safety valves of LNG storage tank 1 and insulation pipeline 9 are in normal condition.
[0008] Then, the experimental equipment was checked: the fine water mist vehicle 25 was checked to see if it was operating normally; the effective connection between the PLC control system 24 and the methane concentration sensor array 20, data acquisition instrument 23, weather instrument 21, camera 22, various valves and instruments was checked to ensure that the data acquisition instrument 23 could normally acquire the thermocouple 18 signal and that the initial temperature of the liquid pool simulation device 17 met the standard.
[0009] Finally, record the environmental parameters: record the experimental environmental conditions such as ambient temperature, air humidity, atmospheric pressure, wind direction, and wind speed.
[0010] S2: LNG Export First, pre-cooling of the insulated pipeline is performed: control the opening and closing of the second valve 6 to introduce a small amount of LNG into the insulated pipeline 9, and slowly pre-cool until the LNG liquid phase in the insulated pipeline 9 reaches stability. This process can be automatically controlled by the PLC control system 24 to control the valve opening time and frequency, so that the pipeline temperature drops uniformly below the LNG temperature.
[0011] Then release the LNG: open the third valve 10 and pour the LNG from the LNG storage tank 1 into the liquid pool simulation device 17, while monitoring the mass data of the electronic balance 19. When the LNG mass reaches the required level for the experiment, close the third valve 10.
[0012] S3: Data Acquisition and Security Monitoring Simultaneously with the release of LNG, the testing system is activated, and the electronic balance 19, data acquisition instrument 23, methane concentration sensor array 20, and camera 22 begin data and image acquisition. The electronic balance 19 continuously collects data on LNG mass changes, reflecting the vaporization rate of the liquid pool; thermocouple 18 collects temperature changes at different depths of the liquid pool simulation device substrate, and can collect data from up to four temperature measurement points 18-1 to 18-4; the methane concentration sensor array 20 collects vapor concentrations at different spatial points, and the monitoring points can be adjusted according to experimental needs; the camera 22 records images of the entire experimental process.
[0013] During the test, the PLC control system 24 continuously monitors the data from the methane concentration sensor array 20. If the LNG vapor concentration exceeds a preset safety threshold (e.g., 20% of the lower explosive limit), the fine water mist vehicle 25 is automatically or manually activated to spray water mist into the enclosure system through the water pipe 26 and water mist nozzles 29 to dilute the LNG vapor and prevent excessive accumulation of LNG vapor within the enclosure system, thus avoiding potential safety hazards. The data acquisition frequency can be automatically adjusted by the PLC control system 24 according to the experimental stage. High-frequency acquisition (e.g., 10Hz) is used in the initial stage of LNG introduction, while low-frequency acquisition (e.g., 1Hz) is used in the stable vaporization stage to balance data accuracy and storage efficiency.
[0014] S4: Experiment ends Once the data collected by the electronic balance 19 reaches a stable state, that is, after the LNG in the liquid pool simulation device 17 has been completely vaporized, the collected data and image data will be numbered, saved, and recorded.
[0015] Shut down the test system, vent the remaining LNG in the insulated pipe 9 and the liquid pool simulation device 17, and ventilate the experimental site. When the methane concentration at all points of the methane concentration sensor array 20 is 0, shut down the fine water mist vehicle 25.
[0016] Finally, the experimental setup and valves were checked, the equipment was tidied up, and the experiment concluded.
[0017] (III) Beneficial Effects Compared with the prior art, the present invention has the following beneficial effects: 1. This invention integrates LNG export, multi-parameter synchronous acquisition and active safety monitoring into the same process flow, realizing high-precision and high-repeatability experiments on the boiling process of small and medium-scale LNG pools. The method steps are simple and can be remotely controlled and automatically recorded throughout the process.
[0018] 2. This invention ensures the consistency of experimental starting conditions and improves the accuracy and repeatability of data by using pre-cooled and insulated pipelines, precisely controlling the LNG import volume, and automatically adjusting the data acquisition frequency.
[0019] 3. This invention effectively avoids direct contact between experimental personnel and cryogenic LNG by real-time monitoring of methane concentration and linkage with the emergency system, eliminating safety hazards such as frostbite, suffocation, and explosion.
[0020] 4. This invention can obtain accurate LNG transient boiling curves, substrate temperature distribution, and vapor diffusion data, providing reliable basic data for LNG leak disaster prevention and control simulation research. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the experimental platform structure used in this invention; Figure 2 It is a frontal cross-sectional view of the liquid pool simulation device and a schematic diagram of the layout of the built-in thermocouples, insulation layer and electronic balance; Figure 3 This is a schematic diagram showing the recommended dimensions, material selection, insulation layer thickness, and internal thermocouple layout for the liquid pool simulation device. Figure 4 This is a schematic diagram of the installation and layout of the methane concentration sensor array; The components include: 1. LNG storage tank; 2. First valve; 3. Liquid inlet pipe; 4. First pressure gauge; 5. First safety valve; 6. Second valve; 7. Second safety valve; 8. Check valve; 9. Insulated pipe; 10. Third valve; 11. Explosion-proof isolation wall; 12. Timber floor; 13. Antistatic flooring; 14. Exhaust skylight; 15. Roof; 16. Insulation layer; 17. Liquid pool simulation device (17-1 side wall, 17-2 base, 17-3 support); 18. Thermocouples (18-1, 18-2, 18-3, 18-4); 19. Electronic balance; 20. Methane concentration sensor array (20-1 support base, 20-2 support pole, 20-3, 20-4, 20-5 support crossbar, 20-6, 20-7, 20-8 methane concentration sensor); 21. Weather instrument; 22. Camera; 23. Data acquisition instrument; 24. PLC control system, 25 fine water mist vehicle, 26 water supply pipe, 27 second pressure gauge, 28 fourth valve, 29 water mist nozzle. Detailed Implementation
[0022] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings.
[0023] refer to Figures 1 to 4The experimental apparatus used in this invention includes an LNG storage tank 1, insulated pipes 9, a liquid pool simulation device 17, an insulation layer 16, an electronic balance 19, thermocouples 18, a methane concentration sensor array 20, a data acquisition instrument 23, a weather instrument 21, a camera 22, a fine water mist vehicle 25, a water supply pipe 26, water mist nozzles 29, an explosion-proof isolation wall 11, a wooden floor 12, an anti-static floor 13, a roof 15, an exhaust skylight 14, and a PLC control system 24. For detailed structure of this apparatus, please refer to the patent "Experimental Apparatus for Boiling Simulation of Leaking LNG Pool" filed on the same day. Here, we only briefly describe its functions: the experimental system is used to store and export LNG; the testing system is used to collect mass, temperature, concentration, environmental, and image data; the emergency system is used to dilute LNG vapor; the enclosure system is used to provide a semi-enclosed environment; and the control system is used for automatic monitoring and control. The implementation process of this invention is described below with reference to specific embodiments.
[0024] Example 1: Simulation Experiment of LNG Pool Boiling on Concrete Substrate S1: Experimental Preparation S11 Storage Tank Status Inspection: Observe the LNG storage tank and pipeline for any frost or obvious damage. Ensure the pressure inside LNG storage tank 1 is within the working range using the first pressure gauge 4. Check that the safety valves of LNG storage tank 1 and insulation pipeline 9 are in normal condition.
[0025] S12 Experimental Equipment Inspection: Check whether the emergency system is operating normally; check the effective connection between the PLC control system and the methane concentration sensor array, data acquisition instrument, weather instrument, camera, various valves and instruments, and ensure that the data acquisition instrument can normally acquire thermocouple signals and that the initial temperature of the liquid pool simulation device meets the standard.
[0026] S13 Environmental Parameter Recording: Record experimental environmental conditions such as ambient temperature, air humidity, atmospheric pressure, wind direction, and wind speed.
[0027] S2: LNG Export S21 Insulated Pipeline Precooling: Control the opening and closing of the second valve 6 to introduce a small amount of LNG into the insulated pipeline 7, and slowly precool until the LNG liquid phase in the insulated pipeline 9 reaches stability.
[0028] S22 Release LNG: Open the third valve 10 to pour the LNG in the LNG storage tank 1 into the liquid pool simulation device 17, monitor the quality data of the electronic balance 19, and close the third valve 10 when the LNG quality reaches the experimental requirements.
[0029] S3: Data Acquisition and Security Monitoring While releasing LNG, S31 starts the test system, and the electronic balance 19, data acquisition instrument 23, methane concentration sensor array 20, and camera 22 begin to acquire data and images.
[0030] During the S32 test, the data from the methane concentration sensor array 20 is continuously monitored. If the LNG vapor concentration rises abnormally, the emergency system is automatically or manually activated to prevent excessive accumulation of LNG vapor in the enclosure system and the resulting safety hazards.
[0031] S4: Experiment End Phase S41 When the data collected by the electronic balance 19 reaches a stable state, that is, after the LNG in the liquid pool simulation device 17 has been completely vaporized, the reading of the electronic balance returns to zero and no longer changes. The collected data and image data are numbered, saved, and recorded.
[0032] S42 shuts down the test system, vents the remaining LNG in the insulated pipeline and liquid pool simulation device, ventilates the test site, and shuts down the emergency system when the methane concentration sensor array 20 shows 0 methane concentration.
[0033] S43 inspected the experimental setup and valves, tidied up the experimental equipment, and concluded the experiment.
[0034] As can be seen from the above embodiments, the method of the present invention can adapt to different substrate materials, different LNG quality and other working conditions, automatically complete data acquisition and safety monitoring, and obtain high-precision experimental data.
[0035] This specific embodiment is only used to illustrate the present invention and is not intended to limit the present invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also fall within the protection scope of the present invention.
Claims
1. A method for simulating boiling in a leaking LNG pool, characterized in that, An experiment was conducted using a boiling simulation device for a leaking LNG pool. The device includes an LNG storage tank (1), an insulated pipeline (9), a liquid pool simulation device (17), an electronic balance (19), a thermocouple (18), a methane concentration sensor array (20), a data acquisition instrument (23), a weather instrument (21), a camera (22), a fine water mist vehicle (25), and a PLC control system (24). The method includes the following steps: S1: Experimental preparation: Check the condition of the LNG storage tank, insulated pipelines, valves and instruments to ensure that the equipment is in good working order; start the control system and confirm that the communication connection between the PLC control system and the electronic balance, thermocouples, methane concentration sensor array, data acquisition instrument, weather instrument and camera is normal; record environmental parameters, including ambient temperature, air humidity, atmospheric pressure, wind direction and wind speed. S2: LNG Export: Pre-cool the insulated pipeline, and introduce a small amount of LNG into the insulated pipeline through the control valve until the LNG liquid phase in the pipeline reaches stability; then open the valve to introduce the LNG in the LNG storage tank into the liquid pool simulation device, while the quality of the introduced LNG is monitored in real time through an electronic balance. When the experimental set quality is reached, the valve is closed. S3: Data Acquisition and Safety Monitoring: Simultaneously with the release of LNG, the test system is activated. The electronic balance continuously collects LNG mass changes, thermocouples collect temperature changes at different depths of the liquid pool simulation device substrate, methane concentration sensor array collects vapor concentration at different spatial points, and a camera records the entire experimental process. The PLC control system monitors the methane concentration sensor array data in real time. If the LNG vapor concentration exceeds the preset safety threshold, the fine water mist vehicle is automatically or manually activated. S4: End of Experiment: Once the mass data collected by the electronic balance is stable, stop data acquisition and save the experimental data and image numbers; shut down the test system, vent the remaining LNG in the insulated pipes and liquid pool simulation device, and turn on the ventilation; when the methane concentration sensor array shows that the methane concentration is 0, turn off the fine water mist vehicle.
2. The method according to claim 1, characterized in that, In step S1, the tank status check includes observing whether there is frost or obvious damage to the LNG tank and pipeline, confirming that the gas pressure inside the LNG tank is within the working range through the first pressure gauge (4), and checking that the LNG tank and the safety valve of the insulation pipeline are in normal condition.
3. The method according to claim 1, characterized in that, In step S1, the experimental equipment inspection includes checking the operating status of the fine water mist vehicle, checking the effective connection between the PLC control system and the methane concentration sensor array, data acquisition instrument, weather instrument, camera, valves and instruments, ensuring that the data acquisition instrument can normally acquire thermocouple signals, and that the initial temperature of the liquid pool simulation device meets the standard.
4. The method according to claim 1, characterized in that, In step S2, the operation of the pre-cooled and insulated pipeline is automatically controlled by the PLC control system to control the opening time and number of valves, so that the pipeline temperature is uniformly reduced to below the LNG temperature.
5. The method according to claim 1, characterized in that, In step S2, the release of LNG is achieved by opening the third valve (10), monitoring the mass data of the electronic balance, and closing the third valve when the LNG mass reaches the required level for the experiment.
6. The method according to claim 1, characterized in that, In step S3, the frequency of data acquisition is automatically adjusted by the PLC control system according to the experimental stage. High-frequency acquisition is used in the initial stage of LNG introduction, and low-frequency acquisition is used in the stable gasification stage.
7. The method according to claim 1, characterized in that, In step S3, the safe threshold for LNG vapor concentration is 20% of the lower explosive limit.
8. The method according to claim 1, characterized in that, In step S4, the stability of the mass data collected by the electronic balance means that the reading of the electronic balance returns to zero and no longer changes after the LNG in the liquid pool simulation device is completely vaporized.
9. The method according to claim 1, characterized in that, In step S4, after venting the remaining LNG in the insulated pipes and liquid pool simulation device, the experimental site is ventilated until the methane concentration at all points of the methane concentration sensor array is 0.
10. The method according to claim 1, characterized in that, The PLC control system displays the electronic balance mass data, thermocouple temperature data, methane concentration data, and experimental images in real time during the experiment, and provides alarm prompts for abnormal data.