Simulation experiment device for heat-fluid-solid coupling effect of LNG underground storage tank and soil layer

Abstract

The utility model belongs to the technical field of underground storage tank model test devices, and particularly discloses a simulation experiment device for a heat-fluid-solid coupling effect of an LNG underground storage tank and a soil layer. Comprising an anti-seepage test soil box, an LNG storage tank reduced scale model, a cold source loading system, a circulating supply seepage system, an optical fiber temperature measurement and strain measurement system, a high-definition camera displacement monitoring system, a soil pressure monitoring system, a test environment monitoring system, a data acquisition and visual control system and a closed heat insulation system. The anti-seepage test soil box comprises an inner box made of high-performance tempered glass, an outer frame welded by angle steel bars is arranged at the upper end of the inner box, two perforated steel partition plates are fixed in the inner box through high-waterproof and anti-seepage structural mucilage glue, the inner box is divided into three cavities by the perforated steel partition plates, and the perforated steel partition plates are arranged in the inner box. A left cabin, a main cabin and a right cabin are sequentially arranged from left to right. Flexible porous partition plates are arranged on the periphery in the main cabin, and the main cabin is filled with test soil.

Description

Technical Field

[0001] The utility model relates to the technical field of underground storage tank model test devices, in particular to a simulation test device for thermal fluid-solid coupling between an LNG underground storage tank and a soil layer. Background Art

[0002] Liquefied natural gas (LNG for short), whose main component is methane, is colorless, odorless, non-toxic and non-corrosive. Its volume is about 1 / 625 of the volume of the same amount of gaseous natural gas, and its mass is only about 45% of the same volume of water. Liquefied natural gas is natural gas that has been compressed and cooled to its boiling point (-161.5℃) to become a liquid. Usually, liquefied natural gas is stored in low-temperature storage tanks at -161.5℃ and about 0.1MPa.

[0003] At present, due to the constraints of economic, technical and other conditions, my country is still lacking in the technology and development of LNG underground storage tanks. Compared with above-ground storage tanks, in terms of force performance, their stability and safety are crucial to preventing secondary disasters caused by tank settlement, tilting, and instability. LNG underground storage tanks have more advantages. LNG underground storage tanks have better seismic resistance and safety, are less likely to be hit by aerial objects, are less affected by wind loads, and have less impact from leakage. LNG underground storage tanks are the direction of my country's energy reserves, and related technical research and reserves are needed.

[0004] Mastering the thermal-fluid-solid coupling mechanism between LNG underground storage tanks and the surrounding soil is a necessary prerequisite for breaking through the relevant technologies of LNG underground storage tanks. Clarifying the stress and deformation mechanism of the underground tank structure and the soil, the distribution of the temperature field, and the transfer path of the cold can play an important guiding role in making full use of the advantages of underground storage tanks, designing more reasonable structural forms, and optimizing construction processes. There are two basic methods to solve the thermal-fluid-solid coupling problem between LNG underground storage tanks and the surrounding soil, one is numerical simulation, and the other is model testing. Large finite element software such as ANSYS, ABAQUS, COMSOL, etc. can perform three-dimensional simulation of thermal-fluid-solid coupling of underground structures, but the numerical calculations basically include some idealized assumptions, lack of verification of experimental data, and even less of actual engineering data. For this reason, it is necessary to design a reasonable LNG underground storage tank model test device to truly simulate the thermal-fluid-solid coupling between LNG underground storage tanks and the surrounding soil layers. Utility Model Content

[0005] In view of the actual needs of scientific research on LNG underground storage tanks, the utility model designs a simulation experimental device for the thermal-fluid-solid coupling between LNG underground storage tanks and soil layers, which is used to simulate the thermal-fluid-solid coupling between the LNG storage tank structure and the surrounding soil under cold source loading conditions, and provides a platform for experimental verification for numerical simulation or theoretical research on this problem.

[0006] To achieve the above-mentioned purpose, the utility model provides the following technical solutions: a simulation experimental device for thermal fluid-solid coupling between an LNG underground storage tank and a soil layer, comprising an anti-seepage test soil box, a scaled model of an LNG storage tank, a cold source loading system, a circulating supply seepage system, an optical fiber temperature and strain measurement system, a high-definition camera displacement monitoring system, a soil pressure monitoring system, a test environment monitoring system, a data acquisition and visualization control system, and a closed thermal insulation system;

[0007] The anti-seepage test soil box comprises an inner box made of high-performance tempered glass, an outer frame welded with angle steel bars is arranged at the upper end of the inner box, two perforated steel partitions are fixed inside the inner box by highly waterproof and anti-permeability structural adhesive, and the perforated steel partitions divide the inner box into three chambers, which are the left cabin, the main cabin and the right cabin from left to right; flexible porous partitions are arranged around the inside of the main cabin and the test soil is filled inside the main cabin, and a scale model of an LNG storage tank is buried inside the test soil; the scale model of the LNG storage tank is made of stainless steel or aluminum alloy, and a refrigerant inlet valve and a refrigerant outlet valve are arranged on the top of the scale model of the LNG storage tank; the outside of the anti-seepage test soil box is provided with a thermal insulation bottom plate and a thermal insulation partition to surround and seal, and an opening and closing door is arranged on one side of the thermal insulation partition; an air-conditioning indoor unit is installed on the inner wall of the thermal insulation partition, and the air-conditioning indoor unit is connected to the air-conditioning outdoor unit, and the air-conditioning outdoor unit is installed on the outside of the thermal insulation partition;

[0008] The cold source loading system consists of a low-temperature thermostatic tank and a refrigerant transmission pipe. The low-temperature thermostatic tank is arranged inside the thermal insulation partition. The output end of the low-temperature thermostatic tank is connected to a refrigerant transmission pipe with a thermal insulation sleeve. The other end of the refrigerant transmission pipe is connected to the scaled model of the LNG storage tank.

[0009] The circulating replenishment seepage system is composed of a left cabin, a right cabin, a circulating water pump and a water pipe;

[0010] The optical fiber temperature and strain measurement system is composed of a bare optical fiber, force transmission beads, a fixed elastic capillary tube and an external optical fiber demodulator;

[0011] The high-definition camera displacement monitoring system includes a high-definition camera, a light source and a matching software system;

[0012] The soil pressure monitoring system is composed of a soil pressure gauge and a pore water pressure gauge, a matching data acquisition instrument and a software system. The soil pressure gauge and the pore water pressure gauge are fixed on a plastic grid, and the plastic grid is arranged around the scaled model of the LNG storage tank in the main cabin of the anti-seepage test soil box;

[0013] The test environment monitoring system includes temperature, humidity, harmful gas monitoring sensors and smoke alarms;

[0014] The data acquisition and visualization control system integrates the corresponding hardware and software such as the optical fiber demodulator, soil pressure and pore water pressure data acquisition instrument, thin film pressure sensor demodulator and data acquisition software into the control console;

[0015] The closed thermal insulation system includes two parts: one is the inner thermal insulation composed of the thermal insulation cover on the anti-seepage test box, and the other is the outer thermal insulation composed of the thermal insulation partition, the thermal insulation bottom plate, the air conditioner indoor unit and the air conditioner outdoor unit.

[0016] Preferably, a water inlet is provided at the upper end of the left cabin, and a water pumping outlet is provided at the upper end of the right cabin. The water inlet and the water pumping outlet are arranged opposite to each other, the water inlet is connected to a water pipe, and the water pumping outlet is also connected to a section of water pipe. The two sections of water pipes are connected in the middle by a circulating water pump, and the water pipe connected to the water pumping outlet is arranged at the bottom of the right cabin and is equipped with a filter head.

[0017] Preferably, the interior of the left compartment and the right compartment are filled with gravel and pebbles.

[0018] Preferably, scale lines are provided on the sides of the left compartment and the right compartment.

[0019] Preferably, a pressure film sensor is attached to the outer periphery of the tank wall of the scaled model of the LNG storage tank.

[0020] Preferably, the liquid inlet pipe of the refrigerant inlet valve is short and close to the top of the storage tank, and the liquid outlet pipe of the refrigerant outlet valve is long and close to the bottom of the storage tank.

[0021] Preferably, the low-temperature constant temperature bath can output both refrigerant and heat medium, the temperature range is about [-80°C, 100°C], and the temperature control accuracy is about 0.1°C.

[0022] Preferably, the bare optical fiber sleeve is provided with a thin protective hose.

[0023] Preferably, the bare optical fiber is distributed around the scaled model of the LNG storage tank, and further, the bare optical fiber is arranged in the test soil around the scaled model of the LNG storage tank through a fixed elastic capillary.

[0024] Preferably, the thermal insulation cover is arranged on the periphery of the outer frame of the anti-seepage test soil box, the shape of the thermal insulation cover is consistent with the inner box of the anti-seepage test soil box, and the bottom surface of the thermal insulation cover is fixed to the top surface of the inner box.

[0025] Compared with the prior art, the utility model has the following beneficial effects: the utility model can simulate various working conditions of normal operation of the outer tank wall of a conventional underground LNG storage tank and LNG leakage. It can create the effect of thermal fluid-solid coupling between the LNG underground storage tank and the surrounding soil under the groundwater seepage environment with different seepage velocities; it can carry out deep cold tests of half tanks, single tanks, double tanks and group tanks; it can help people understand the stress and deformation mechanism of the LNG underground tank structure and the soil, the distribution of the temperature field, and the transfer path of the cold through model tests, which can play an important guiding role in making full use of the advantages of underground storage tanks, designing more reasonable structural forms, and optimizing construction processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the overall structure of the underground storage tank model test platform of the utility model;

[0027] Figure 2 This is a cross-sectional view of the anti-seepage test soil box and the LNG scaled tank body of the utility model component;

[0028] Figure 3 This is the layout diagram of the bare optical fiber sensor of the utility model component;

[0029] Figure 4 This is the layout diagram of the earth pressure gauge and pore water pressure gauge components of the utility model.

[0030] In the figure: 100, cold source loading system; 200, circulating supply seepage system; 300, optical fiber temperature and strain measurement system; 400, high-definition camera displacement monitoring system; 500, soil pressure monitoring system; 600, test environment monitoring system; 700, data acquisition and visual control system; 800, closed thermal insulation system; 1, anti-seepage test soil box; 2, LNG storage tank scale model; 201, inner box; 202, outer frame; 3, test soil; 4, low-temperature constant temperature tank; 5, refrigerant transmission pipe; 6, circulating water pump; 7, water pipe; 8, air conditioner Indoor unit; 9. Air conditioning outdoor unit; 10. Insulation partition; 11. Insulation bottom plate; 12. Opening and closing door; 13. Perforated steel partition; 14. Plastic grid; 15. Earth pressure gauge; 16. Pore water pressure gauge; 17. Refrigerant outlet valve; 18. Refrigerant inlet valve; 19. Left cabin; 1901. Water inlet; 20. Main cabin; 21. Right cabin; 2101. Pumping outlet; 2102. Filter head; 22. Insulation cover; 23. Bare optical fiber; 24. Force transmission beads; 25. Fixed elastic capillary; 26. Optical fiber demodulator; 27. Pressure film sensor. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0032] In the description of the present invention, it should be noted that the terms "vertical", "up", "down", "horizontal", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0033] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] See also Figure 1-4 The utility model provides a technical solution: a simulation experimental device for thermal fluid-solid coupling between an LNG underground storage tank and a soil layer, comprising an anti-seepage test soil box 1, a scaled model of an LNG storage tank 2, a cold source loading system 100, a circulating supply seepage system 200, an optical fiber temperature and strain measurement system 300, a high-definition camera displacement monitoring system 400, an earth pressure monitoring system 500, a test environment monitoring system 600, a data acquisition and visualization control system 700 and a closed thermal insulation system 800;

[0035] The anti-seepage test soil box 1 includes an inner box 201 made of high-performance tempered glass, an outer frame 202 welded with angle steel bars is arranged at the upper end of the inner box 201, two perforated steel partitions 13 are fixed inside the inner box 201 by highly waterproof and anti-permeability structural adhesive, and the perforated steel partitions 13 divide the inner box 201 into three chambers, which are the left cabin 19, the main cabin 20 and the right cabin 21 from left to right; flexible porous partitions are arranged around the main cabin 20 and the test soil 3 is filled inside the main cabin 20, and the flexible porous partitions serve as the flexible boundaries of the test soil 3, simulating the semi-infinite boundary of the underground soil, and also preventing the soil from frost heaving and deforming too much and squeezing A soil box, a scaled model 2 of an LNG storage tank is buried inside the test soil body 3; the scaled model 2 of the LNG storage tank is made of stainless steel or aluminum alloy, and a refrigerant inlet valve 18 and a refrigerant outlet valve 17 are arranged on the top of the scaled model 2 of the LNG storage tank, which are used to simulate the cold source loading conditions of different liquid level heights of LNG in the storage tank; the outside of the anti-seepage test soil box 1 is provided with a thermal insulation bottom plate 11 and a thermal insulation partition 10 to be surrounded and sealed, and an opening and closing door 12 is arranged on one side of the thermal insulation partition 10; an air conditioner indoor unit 8 is installed on the inner wall of the thermal insulation partition 10, and the air conditioner indoor unit 8 is connected to the air conditioner outdoor unit 9, and the air conditioner outdoor unit 9 is installed on the outside of the thermal insulation partition 10;

[0036] The cold source loading system 100 is composed of a low-temperature thermostatic tank 4 and a refrigerant transmission pipe 5. The low-temperature thermostatic tank 4 is arranged inside the thermal insulation partition 10. The output end of the low-temperature thermostatic tank 4 is connected to the refrigerant transmission pipe 5 with a thermal insulation sleeve. The other end of the refrigerant transmission pipe 5 is connected to the LNG storage tank scale model 2.

[0037] The circulating replenishment seepage system 200 is composed of the left cabin 19, the right cabin 21, the circulating water pump 6 and the water pipe 7; its function is to provide the test platform with a stable water circulation effect to simulate stable groundwater seepage. By controlling the flow rate of the circulating water pump and the head difference between the left and right cabins, groundwater seepage conditions with different speeds can be created;

[0038] The optical fiber temperature and strain measurement system 300 is composed of a bare optical fiber 23, a force transmission bead 24, a fixed elastic capillary 25, and an external optical fiber demodulator 26; the distributed bare optical fiber 23 sensor can measure temperature and strain at the same time, and the bare optical fiber 23 around the LNG storage tank scale model 2 can monitor the changes in tank temperature and tank wall stress; in addition, the bare optical fiber 23 is arranged in the test soil 3 through the fixed elastic capillary 25 and the capillary protective sleeve to measure the changes in soil temperature during the LNG cold source loading process, and the layered and circular arrangement of the bare optical fiber 23 can measure a relatively clear temperature distribution change law in the internal space of the soil, and after post-processing, a three-dimensional spatial temperature distribution diagram of the soil over time can be formed;

[0039] The high-definition camera displacement monitoring system 400 includes a high-definition camera, a light source, and a matching software system; it is used to monitor the frost heave displacement caused by the freezing effect on the soil surface during the sample process;

[0040] The soil pressure monitoring system 500 is composed of a soil pressure gauge 15 and a pore water pressure gauge 16, a matching data acquisition instrument and a software system. The soil pressure gauge 15 and the pore water pressure gauge 16 are fixed on a plastic grid 14, and the plastic grid 14 is arranged around the LNG tank scale model 2 in the main compartment 20 of the anti-seepage test soil box 1;

[0041] The test environment monitoring system 600 includes temperature, humidity, harmful gas monitoring sensors and smoke alarms, etc., and is used to monitor the indoor environment of the entire test platform;

[0042] The data acquisition and visualization control system 700 integrates the corresponding hardware and software such as the optical fiber demodulator 26, the soil pressure and pore water pressure data acquisition instrument, the membrane pressure sensor demodulator and the data acquisition software into the control console, so as to facilitate the test personnel to smoothly operate the test and monitor the data;

[0043] The closed thermal insulation system 800 includes two parts: one is the internal insulation consisting of the insulation cover 22 on the anti-seepage test box 1, and the other is the external insulation consisting of the insulation partition 10, the insulation bottom plate 11 and the air-conditioning indoor unit 8 and the air-conditioning outdoor unit 9. Through the internal and external insulation layers, the model test box maintains the environmental temperature conditions required for the test.

[0044] Furthermore, a water inlet 1901 is provided at the upper end of the left cabin 19, and a water pumping outlet 2101 is provided at the upper end of the right cabin 21. The water inlet 1901 and the water pumping outlet 2101 are arranged opposite to each other. The water inlet 1901 is connected to a water pipe 7, and the water pumping outlet 2101 is also connected to a section of the water pipe 7. The two sections of the water pipe 7 are connected by a circulating water pump 6. The water pipe 7 connected to the water pumping outlet 2101 is arranged at the bottom of the right cabin 21 and is equipped with a filter head 2102.

[0045] Furthermore, the left chamber 19 and the right chamber 21 are filled with gravel and pebbles to facilitate the control of the water flow pattern and simulate the laminar flow pattern as much as possible.

[0046] Furthermore, scale lines are provided on the sides of the left compartment 19 and the right compartment 21 to facilitate reading of the water levels of the two compartments, and the two compartments are used to simulate groundwater seepage environments with different speeds.

[0047] Furthermore, a pressure film sensor 27 is attached to the outer periphery of the tank wall of the LNG storage tank scale model 2 to monitor the additional frost heave pressure on the tank body caused by the frost heave of the soil layer around the LNG storage tank scale model 2 when the soil body freezes.

[0048] Furthermore, the liquid inlet pipe of the refrigerant inlet valve 18 is short and close to the top of the inside of the LNG storage tank scale model 2, and the liquid outlet pipe of the refrigerant outlet valve 17 is long and close to the bottom of the inside of the LNG storage tank scale model 2, which is convenient for the circulation of the refrigerant; the refrigerant pumped from the low-temperature constant temperature tank 4 to the LNG storage tank scale model 2 is continuously circulated, and the low-temperature constant temperature tank 4 acts to maintain the refrigerant temperature stable.

[0049] Furthermore, the low-temperature constant temperature tank 4 can output both refrigerant and heat medium, with a temperature range of approximately [-80°C, 100°C] and a temperature control accuracy of approximately 0.1°C, which can meet the test simulation of the fluid-solid thermal coupling between the storage tank and the surrounding soil, and can also meet the requirements of the simulated environment of similar underground structures.

[0050] Furthermore, the bare optical fiber 23 is provided with a thin protective hose.

[0051] Furthermore, the bare optical fiber 23 is distributed around the scaled model 2 of the LNG storage tank. In addition, the bare optical fiber 23 is arranged in the test soil 3 around the scaled model 2 of the LNG storage tank through a fixed elastic capillary 25 .

[0052] Furthermore, the thermal insulation cover 22 is arranged outside the outer frame 202 of the anti-seepage test soil box 1, the shape of the thermal insulation cover 22 is consistent with the inner box 201 of the anti-seepage test soil box 1, and the bottom surface of the thermal insulation cover 22 is fixed to the top surface of the inner box 201.

[0053] Working principle: The utility model provides a simulation experimental device for the thermal fluid-solid coupling between an LNG underground storage tank and a soil layer. When used, the circulating supply seepage system 200 is first adjusted according to the test needs, and groundwater seepage conditions are created in the anti-seepage test soil box 1. Then, a cold source loading system 100 is set, and a cold medium is added to the low-temperature constant temperature tank 4 according to the test requirements. Figure 2 , Figure 3 , Figure 4The schematic diagram shows the arrangement of the optical fiber temperature and strain measurement system 300, the high-definition camera displacement monitoring system 400, the soil pressure monitoring system 500 and the test environment monitoring system 600. The data acquisition and visualization control system 700 is turned on to observe and read the test data. The utility model can simulate the normal operation of the outer tank wall of a conventional underground LNG storage tank and various working conditions when LNG leaks. It can create the effect of thermal fluid-solid coupling between the LNG underground storage tank and the surrounding soil under the groundwater seepage environment with different seepage velocities; it can carry out half-tank, single-tank, double-tank and group-tank deep-cold tests; it can help people understand the stress and deformation mechanism of the LNG underground tank structure and the soil, the distribution of the temperature field, and the transfer path of the cold through model tests, which can play an important guiding role in making full use of the advantages of underground storage tanks, designing more reasonable structural forms, and optimizing construction processes.

[0054] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A simulation experimental device for thermal fluid-solid coupling between an LNG underground storage tank and a soil layer, characterized by: The system comprises an anti-seepage test soil box (1), a scaled model of an LNG storage tank (2), a cold source loading system (100), a circulating supply seepage system (200), an optical fiber temperature and strain measurement system (300), a high-definition camera displacement monitoring system (400), an earth pressure monitoring system (500), a test environment monitoring system (600), a data acquisition and visual control system (700), and a closed thermal insulation system (800); The anti-seepage test soil box (1) comprises an inner box (201) made of high-performance tempered glass, an outer frame (202) welded with angle steel bars is arranged at the upper end of the inner box (201), two perforated steel partitions (13) are fixed inside the inner box (201) by highly waterproof and anti-permeability structural adhesive, and the perforated steel partitions (13) divide the inner box (201) into three chambers, which are a left cabin (19), a main cabin (20) and a right cabin (21) from left to right; flexible porous partitions are arranged around the inside of the main cabin (20) and the inside of the main cabin (20) is filled with a test soil body (3), and the inside of the test soil body (3) A scaled model (2) of an LNG storage tank is buried; the scaled model (2) of the LNG storage tank is made of stainless steel or aluminum alloy, and a refrigerant inlet valve (18) and a refrigerant outlet valve (17) are arranged on the top of the scaled model (2); a heat-insulating bottom plate (11) and a heat-insulating partition (10) are arranged on the outside of the anti-seepage test soil box (1) to surround and seal the bottom plate, and an opening and closing door (12) is arranged on one side of the heat-insulating partition (10); an air-conditioning indoor unit (8) is installed on the inner wall of the heat-insulating partition (10), and the air-conditioning indoor unit (8) is connected to an air-conditioning outdoor unit (9), and the air-conditioning outdoor unit (9) is installed on the outside of the heat-insulating partition (10); The cold source loading system (100) is composed of a low-temperature thermostatic tank (4) and a refrigerant transmission pipe (5), wherein the low-temperature thermostatic tank (4) is arranged inside a heat-insulating partition (10), the output end of the low-temperature thermostatic tank (4) is connected to a refrigerant transmission pipe (5) with a heat-insulating sleeve, and the other end of the refrigerant transmission pipe (5) is connected to a scaled model (2) of an LNG storage tank; The circulating replenishment seepage system (200) is composed of a left cabin (19), a right cabin (21), a circulating water pump (6) and a water delivery pipe (7); The optical fiber temperature and strain measurement system (300) is composed of a bare optical fiber (23), force transmission beads (24), a fixed elastic capillary (25), and an external optical fiber demodulator (26); The high-definition camera displacement monitoring system (400) comprises a high-definition camera, a light source and a matching software system; The soil pressure monitoring system (500) is composed of a soil pressure gauge (15) and a pore water pressure gauge (16), a matching data acquisition instrument and a software system. The soil pressure gauge (15) and the pore water pressure gauge (16) are fixed on a plastic grid (14). The plastic grid (14) is arranged around the LNG storage tank scale model (2) in the main compartment (20) of the anti-seepage test soil box (1); The test environment monitoring system (600) comprises temperature, humidity, harmful gas monitoring sensors and a smoke alarm; The data acquisition and visualization control system (700) integrates the optical fiber demodulator (26), soil pressure and pore water pressure data acquisition instrument, thin film pressure sensor demodulator and data acquisition software corresponding hardware and software into a control console; The closed thermal insulation system (800) comprises two parts: one is the internal insulation consisting of a thermal insulation cover (22) on the anti-seepage test soil box (1); and the other is the external insulation consisting of a thermal insulation partition (10), a thermal insulation bottom plate (11), an air conditioner indoor unit (8), and an air conditioner outdoor unit (9).

2. The simulation experimental device for thermal fluid-solid coupling between an LNG underground storage tank and a soil layer according to claim 1, characterized in that: The upper end of the left cabin (19) is provided with a water inlet (1901), and the upper end of the right cabin (21) is provided with a water pumping outlet (2101). The water inlet (1901) and the water pumping outlet (2101) are arranged opposite to each other. The water inlet (1901) is connected to a water pipe (7), and the water pumping outlet (2101) is also connected to a section of the water pipe (7). The two sections of the water pipe (7) are connected in the middle by a circulating water pump (6). The water pipe (7) connected to the water pumping outlet (2101) is arranged at the bottom of the right cabin (21) and is equipped with a filter head (2102).

3. The simulation experimental device for thermal fluid-solid coupling between an LNG underground storage tank and a soil layer according to claim 1, characterized in that: The left chamber (19) and the right chamber (21) are filled with gravel and pebbles.

4. The simulation experimental device for thermal fluid-solid coupling between an LNG underground storage tank and a soil layer according to claim 1, characterized in that: The sides of the left compartment (19) and the right compartment (21) are both provided with scale lines.

5. The simulation experimental device for thermal fluid-solid coupling between an LNG underground storage tank and a soil layer according to claim 1, characterized in that: A pressure film sensor (27) is attached to the outer periphery of the tank wall of the LNG storage tank scale model (2).

6. The simulation experimental device for thermal fluid-solid coupling between an LNG underground storage tank and a soil layer according to claim 1, characterized in that: The liquid inlet pipe of the refrigerant inlet valve (18) is short and close to the top of the interior of the LNG storage tank scale model (2), and the liquid outlet pipe of the refrigerant outlet valve (17) is long and close to the bottom of the interior of the LNG storage tank scale model (2).

7. The simulation experimental device for thermal fluid-solid coupling between an LNG underground storage tank and a soil layer according to claim 1, characterized in that: The low-temperature constant temperature bath (4) can output both refrigerant and heat medium, with a temperature range of approximately [-80°C, 100°C] and a temperature control accuracy of approximately 0.1°C.

8. The simulation experimental device for thermal fluid-solid coupling between an LNG underground storage tank and a soil layer according to claim 1, characterized in that: The bare optical fiber (23) is sheathed with a thin protective hose.

9. The simulation experimental device for thermal fluid-solid coupling between an LNG underground storage tank and a soil layer according to claim 1, characterized in that: The bare optical fiber (23) is distributed around the scaled model (2) of the LNG storage tank. In addition, the bare optical fiber (23) is arranged in the test soil (3) around the scaled model (2) of the LNG storage tank through a fixed elastic capillary (25).

10. The simulation experimental device for thermal fluid-solid coupling between an LNG underground storage tank and a soil layer according to claim 1, characterized in that: The heat-insulating cover (22) is arranged outside the outer frame (202) of the anti-seepage test soil box (1); the shape of the heat-insulating cover (22) is consistent with the inner box (201) of the anti-seepage test soil box (1); and the bottom surface of the heat-insulating cover (22) is fixed to the top surface of the inner box (201).

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