A leakage LNG pool boiling simulation experiment device

Abstract

The present application belongs to the field of dangerous chemical leakage mechanism research, and specifically provides a kind of leakage LNG pool boiling simulation experimental device, solve the problem that existing device is difficult to accurately simulate the pool boiling process of cryogenic LNG on solid surface, including experiment, test, emergency, enclosure and control five systems;Experimental system includes LNG storage tank, adiabatic pipeline, insulation layer and liquid pool simulation device;Test system includes electronic balance, thermocouple, methane concentration sensor array, data acquisition instrument, weather meter and camera;Emergency system includes water mist car, water pipe and water mist nozzle;Enclosure system includes explosion-proof isolation wall, wood bone floor, anti-static ground glue, roof and exhaust skylight;Control system includes PLC control system, display instrument and control valve.The present application realizes small scale leakage LNG pool boiling simulation through remote control and safety redundancy, avoids asphyxia, frostbite and combustion explosion injury caused by LNG, can automatically collect data, has high measurement accuracy and strong repeatability.

Description

Technical Field

[0001] This invention relates to the field of hazardous chemical leakage mechanism research, specifically to a boiling simulation experimental device for 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 boiling simulation experimental device for leaked LNG pools that can achieve small-to-medium scale, 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 existing technologies, such as the lack of a dedicated experimental device for boiling LNG pools leaking from small and medium-sized solid surfaces, low accuracy and poor repeatability of large-scale experimental data, and difficulty in applying experimental conclusions of substitutes to engineering.

[0006] (II) Technical Solution To address the aforementioned issues, this invention proposes a boiling simulation experimental device for leaked LNG pools. This device employs a modular design, integrating five major systems: experimentation, testing, emergency response, containment, and control. It achieves safe storage, controllable export, simultaneous acquisition of multiple parameters, and proactive safety protection for cryogenic LNG. The overall approach involves eliminating environmental interference through a semi-enclosed containment structure, utilizing a PLC control system for remote automatic control, and simulating different solid surfaces using replaceable substrates to obtain high-precision pool boiling characteristic data.

[0007] Specifically, the present invention comprises five parts: an experimental system, a testing system, an emergency system, a containment system, and a control system.

[0008] The experimental system is used to simulate LNG storage and leakage, and mainly includes an LNG storage tank 1, an insulated pipeline 9, an insulation layer 16, and a liquid pool simulation device 17. Figure 1 As shown, LNG storage tank 1 is a welded insulated gas cylinder. The internal pressure of the tank is monitored by a pressure gauge, and the pressure inside the tank is used as a power source to extract LNG. Both LNG storage tank 1 and the insulated pipeline 9 are equipped with valves and safety valves. The opening and closing of these valves pre-cools the insulated pipeline and smoothly extracts the LNG to the liquid pool simulation device 17. An insulation layer 16 wraps around the outer surface of the liquid pool simulation device 17 to simulate the insulation boundary conditions. By replacing the liquid pool simulation device 17 with different base materials, the boiling-related characteristics of LNG liquid pools with different solid surface leaks can be studied.

[0009] The testing system is used to collect data such as temperature, concentration, mass, visible cloud concentration, experimental meteorological environment, and images. It includes an electronic balance 19, thermocouples 18, a methane concentration sensor array 20, a data acquisition unit 23, a meteorological instrument 21, and a camera 22. The electronic balance 19 is located at the bottom of the liquid pool simulation device 17 and is used to record the vaporization rate of the leaking LNG pool in real time. Thermocouples 18 are built into different positions inside the liquid pool simulation device base 17-2, with up to four temperature measurement points 18-1 to 18-4, used to record the temperature changes of the liquid pool simulation device base. The methane concentration sensor array 20 is used to record the concentration distribution of LNG vapor clouds at different spatial points; its monitoring points can be adjusted according to different operating conditions. The data acquisition unit 23 is connected to the thermocouples 18 to collect temperature signals. The meteorological instrument 21 is used to record parameters such as temperature, humidity, atmospheric pressure, wind direction, and wind speed of the experimental environment. The camera 22 is used to capture images of the entire experiment.

[0010] The emergency system, designed to prevent excessive accumulation of LNG vapor and eliminate potential experimental accidents, includes a fine water mist vehicle 25, a water supply pipe 26, and water mist nozzles 29. When the methane concentration rises abnormally, the fine water mist vehicle 25 can be automatically or manually activated to spray water mist into the enclosure system through the water supply pipe 26 and water mist nozzles 29 to dilute the LNG vapor.

[0011] The enclosure system is used to create a semi-enclosed environment, eliminating the influence of factors such as wind speed and heat radiation on the boiling characteristics of the LNG pool while ensuring safety. It includes an explosion-proof isolation wall 11, a wooden floor 12, an anti-static floor 13, a roof 15, and ventilation skylights 14. The explosion-proof isolation wall 11 is located around the perimeter, the wooden floor 12 is laid on the ground, the anti-static floor 13 covers the upper surface of the wooden floor 12, the roof 15 is located at the top, and the ventilation skylights 14 can be opened for ventilation.

[0012] The control system, used to monitor the experimental platform's status parameters and control the experimental process, includes a PLC control system 24, display instruments, and control valves. The PLC control system 24 is connected to an electronic balance 19, a weather instrument 21, a camera 22, a methane concentration sensor array 20, a fine water mist vehicle 25, and a data acquisition unit 23. The data acquisition unit 23 is connected to a thermocouple 18. The display instruments include a first pressure gauge 4 and a second pressure gauge 27, which are installed on the LNG storage tank 1 and the fine water mist vehicle 25, respectively, and are connected to the PLC control system 24. The control valves include a first valve 2, a first safety valve 5, a second valve 6, a second safety valve 7, a check valve 8, a third valve 10, and a fourth valve 28, all connected to the PLC control system 24 to achieve automatic control.

[0013] LNG storage tank 1 and fine water mist vehicle 25 are located outside the enclosure system and connected to the testing system through insulation pipe 9 and water supply pipe 26, respectively, passing through explosion-proof isolation wall 11 to ensure operational safety. Liquid pool simulation device 17 is securely placed on electronic balance 19 via support 17-3 to ensure accurate mass measurement.

[0014] (III) Beneficial Effects Compared with the prior art, the present invention has the following beneficial effects: 1. This invention integrates an LNG storage tank, insulated pipeline, liquid pool simulation device, multi-sensor system and PLC control system to achieve accurate simulation and automatic monitoring of the boiling process of a cryogenic LNG leak pool. The device has a compact structure and high safety redundancy.

[0015] 2. This invention, through remote control and safety redundancy design, avoids direct contact between experimental personnel and cryogenic LNG, eliminating safety hazards such as frostbite, suffocation, and explosion.

[0016] 3. This invention, through its replaceable substrate design, can simulate leakage conditions on various solid surfaces (such as concrete, metal, soil, etc.), and has a wide range of applications.

[0017] 4. This invention, through a high-precision electronic balance, multi-point thermocouples, methane concentration sensor array, and automatic data acquisition system, can obtain high-precision LNG vaporization rate, substrate temperature distribution, and vapor diffusion data, with strong experimental repeatability. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the layout of the LNG leak pool boiling simulation test platform; 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. Thermocouple (18-1, 18-2, 18-3, 18-4 are temperature measurement points at different depths); 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 unit, 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

[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings.

[0020] refer to Figure 1 , Figure 2 , Figure 3 and Figure 4 The LNG leak pool boiling simulation test platform consists of five parts: experimental system, testing system, emergency system, containment system, and control system.

[0021] The experimental system is used to realize the storage and export of cryogenic LNG, and mainly includes an LNG storage tank 1, an insulated pipeline 9, a liquid pool simulation device 17, and an insulation layer 16. The LNG storage tank 1 is a welded insulated gas cylinder, on which a first pressure gauge 4 is installed to monitor the gas pressure inside the tank. The LNG storage tank 1 is connected to the liquid pool simulation device 17 via the insulated pipeline 9, which is equipped with a second valve 6, a check valve 8, and a third valve 10, and is connected to a second safety valve 7. The insulation layer 16 wraps around the outer surface of the liquid pool simulation device 17 to simulate the adiabatic boundary conditions of the outer surface. The liquid pool simulation device 17 includes a sidewall 17-1, a base 17-2, and a support 17-3. The base 17-2 can be replaced with different materials (such as concrete, carbon steel, stainless steel, etc.) according to experimental needs to study the pool boiling characteristics of different solid surfaces.

[0022] The testing system includes an electronic balance 19, thermocouples 18, a methane concentration sensor array 20, a data acquisition unit 23, a weather instrument 21, and a camera 22. The electronic balance 19 is located at the bottom of the liquid pool simulation device 17, which is securely placed on it via supports 17-3. Thermocouples 18 are embedded in different positions within the substrate 17-2; depending on the substrate thickness, up to four thermocouples 18-1 to 18-4 can be deployed to measure temperature changes at different depths. The methane concentration sensor array 20 includes multiple supports, each consisting of a support base 20-1, a support column 20-2, and multiple support cross plates 20-3 to 20-5. The cross plates are fixed to the support column with detachable screws, allowing for the installation of multiple methane concentration sensors 20-6 to 20-8 to measure concentration at different heights. Depending on experimental requirements, 1 to 3 supports can be arranged at appropriate distances. The data acquisition unit 23 is connected to the thermocouples 18 to acquire temperature signals. Weather instrument 21 is used to record parameters such as ambient temperature, humidity, atmospheric pressure, wind direction, and wind speed. Camera 22 is used to capture images of the entire experiment.

[0023] The emergency system includes a fine water mist truck 25, a water supply pipe 26, and water mist nozzles 29. The fine water mist truck 25 is located outside the enclosure system and enters the enclosure system through the explosion-proof isolation wall 11 via the water supply pipe 26. The water mist nozzles 29 are installed at the end of the water supply pipe 26. When the methane concentration rises abnormally, the fine water mist truck 25 can be automatically or manually activated via the PLC control system 24 to spray and dilute the methane.

[0024] The enclosure system includes an explosion-proof isolation wall 11, a wooden floor 12, an anti-static floor 13, a roof 15, and an exhaust skylight 14, which together form a semi-enclosed experimental space to eliminate interference from external factors such as wind speed and heat radiation, while preventing the diffusion of LNG vapor.

[0025] The control system includes a PLC control system 24, display instruments, and control valves. The PLC control system 24 is connected to an electronic balance 19, a weather instrument 21, a camera 22, a methane concentration sensor array 20, a fine water mist vehicle 25, and a data acquisition unit 23, respectively, to collect data in real time and issue control commands. The display instruments include a first pressure gauge 4 and a second pressure gauge 27, which are installed on the LNG storage tank 1 and the fine water mist vehicle 25, respectively, and are connected to the PLC control system 24 for remote monitoring. The control valves include a first valve 2, a first safety valve 5, a second valve 6, a second safety valve 7, a check valve 8, a third valve 10, and a fourth valve 28, all connected to the PLC control system 24, which automatically controls the opening and closing of the valves.

[0026] Through the above structure, the present invention realizes the safe storage, controllable export, multi-parameter synchronous acquisition and active safety protection of cryogenic LNG, and can accurately simulate the pool boiling process of LNG leaking from different solid surfaces.

[0027] 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 boiling simulation experimental apparatus for a leaking LNG pool, characterized in that, This includes experimental systems, testing systems, emergency systems, enclosure systems, and control systems; The experimental system includes an LNG storage tank (1), an insulated pipe (9), an insulation layer (16), and a liquid pool simulation device (17). The LNG storage tank (1) is connected to the liquid pool simulation device (17) through the insulated pipe (9). The insulation layer (16) is wrapped around the outer surface of the liquid pool simulation device (17). The experimental system is used to realize the storage and leakage simulation of LNG. The testing system includes an electronic balance (19), a thermocouple (18), a methane concentration sensor array (20), a data acquisition unit (23), a weather instrument (21), and a camera (22). The electronic balance (19) is located at the bottom of the liquid pool simulation device (17). The thermocouple (18) is built into the base of the liquid pool simulation device (17). The methane concentration sensor array (20) is set in the surrounding space of the liquid pool simulation device (17). The data acquisition unit (23) is connected to the thermocouple (18). The testing system is used to collect temperature, concentration, mass, cloud concentration, experimental environment, and image data. The emergency system includes a fine water mist vehicle (25), a water supply pipe (26), and water mist nozzles (29). The emergency system is used to prevent excessive accumulation of LNG vapor. The enclosure system includes an explosion-proof isolation wall (11), a wooden floor (12), an anti-static floor mat (13), a roof (15), and an exhaust skylight (14). The enclosure system is used to form a semi-enclosed experimental environment. The control system includes a PLC control system (24), display instruments and control valves. The control system is used to monitor the status parameters of the experimental platform and control the experimental process. The LNG storage tank (1) and the fine water mist vehicle (25) are placed outside the enclosure system and are connected to the test system through the explosion-proof isolation wall (11) via the heat insulation pipe (9) and the water supply pipe (26), respectively. The PLC control system (24) is connected to the electronic balance (19), the weather instrument (21), the camera (22), the methane concentration sensor array (20), the fine water mist vehicle (25), and the data acquisition instrument (23), respectively.

2. The LNG leak pool boiling simulation experimental apparatus according to claim 1, characterized in that, The LNG storage tank (1) is a welded insulated gas cylinder with a first pressure gauge (4) on it. Valves and safety valves are provided on both the LNG storage tank (1) and the insulated pipeline (9). The pressure inside the LNG storage tank (1) is used as a power source to export LNG.

3. The LNG leak pool boiling simulation experimental apparatus according to claim 1, characterized in that, The liquid pool simulation device (17) includes a side wall (17-1), a base (17-2) and a support (17-3). The base (17-2) is a replaceable structure, and leakage simulation of different solid surfaces can be achieved by replacing the base with a base of different materials.

4. The LNG leak pool boiling simulation experimental apparatus according to claim 1, characterized in that, The thermocouple (18) is arranged along the thickness direction of the substrate (17-2), and a maximum of four temperature measuring points (18-1, 18-2, 18-3, 18-4) are provided.

5. The LNG leak pool boiling simulation experimental apparatus according to claim 1, characterized in that, The methane concentration sensor array (20) includes at least one support, each support having multiple detachable and fixed methane concentration sensors.

6. The LNG leak pool boiling simulation experimental apparatus according to claim 5, characterized in that, The support includes a support base (20-1), a support upright (20-2), and multiple support horizontal plates (20-3, 20-4, 20-5). The support horizontal plates and the support upright are fixedly connected by detachable screws.

7. The LNG leak pool boiling simulation experimental apparatus according to claim 1, characterized in that, The display instrument includes a first pressure gauge (4) and a second pressure gauge (27). The first pressure gauge (4) is installed on the LNG storage tank (1), and the second pressure gauge (27) is installed on the fine water mist vehicle (25). The first pressure gauge (4) and the second pressure gauge (27) are respectively connected to the PLC control system (24).

8. The LNG leak pool boiling simulation experimental apparatus according to claim 1, characterized in that, The control valves include a first valve (2), a first safety valve (5), a second valve (6), a second safety valve (7), a check valve (8), a third valve (10), and a fourth valve (28). The first valve (2) is installed on the liquid inlet pipe (3) leading to the LNG storage tank (1). The first safety valve (5) is installed on the pipe leading to the LNG storage tank (1). The LNG storage tank (1) is connected to the second safety valve (7) through an insulated pipe (9). The second valve (6), the check valve (8), and the third valve (10) are respectively connected to the insulated pipe (9). The first safety valve (5), the second valve (6), the second safety valve (7), the third valve (10), and the fourth valve (28) are respectively connected to the PLC control system (24).

9. The LNG leak pool boiling simulation experimental apparatus according to claim 1, characterized in that, The liquid pool simulation device (17) is securely placed on the electronic balance (19) by a support (17-3). The electronic balance (19) is used to measure the mass change of LNG in the liquid pool simulation device (17) in real time.

10. The LNG leak pool boiling simulation experimental apparatus according to claim 1, characterized in that, The explosion-proof isolation wall (11) is located around the enclosure system, the wooden floor (12) is laid on the ground, the anti-static floor mat (13) is covered on the upper surface of the wooden floor (12), the enclosure roof (15) is located at the top of the enclosure system, and the exhaust skylight (14) is set on the enclosure roof (15).

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