A device and method for testing the vacuum resistance characteristics of a multilayer insulation material of a low-temperature storage tank

Abstract

The application provides a low-temperature storage tank multilayer insulation material vacuum resistance characteristic testing device and method, which comprises a cover plate and a shell, wherein the shell is internally sequentially provided with an upper protection cavity, a testing cavity and a lower protection cavity from top to bottom; the outer surfaces of the upper protection cavity and the lower protection cavity are coated with multilayer insulation materials, the outer surfaces of the sidewall and the bottom plate of the testing cavity are coated with multilayer insulation materials, a copper plate is arranged between the top plate of the testing cavity and the upper protection cavity, the edges of the top plate of the testing cavity and the edges of the copper plate are connected through a wire mesh, and the outer sides of the wire mesh and the copper plate are coated with multilayer insulation materials; a rewarming pipeline is arranged on the cover plate, one end of the rewarming pipeline is inserted into the area between the copper plate and the top plate of the testing cavity, the other end of the rewarming pipeline is extended out of the cover plate and connected with a second vacuum gauge. The pressure of the area between the copper plate and the testing cavity is measured through the second vacuum gauge, the interlayer pressure of the insulation material is obtained, the second vacuum gauge does not need to be arranged in the multilayer insulation material, and the insulation material is guaranteed not to be damaged.

Description

Technical Field

[0001] The present invention belongs to the field of cryogenic liquid storage and transportation, and in particular relates to a device and method for testing vacuum resistance characteristics of multi-layer thermal insulation materials of cryogenic storage tanks. Background Art

[0002] Heat leakage is inevitable during the storage and transportation of cryogenic liquids, which poses a huge challenge to the safety and economy of the cryogenic liquid storage process. The introduction of high vacuum multi-layer insulation technology has greatly reduced the heat leakage during the storage and transportation of cryogenic liquids. The core of this technology is to significantly weaken the thermal conductivity of gases by creating a high vacuum environment, introduce spacer materials with extremely low thermal conductivity to reduce solid thermal conductivity, and add radiation screens with extremely low emissivity to weaken radiation heat transfer. However, due to the influence of the interlayer resistance of the insulation material, the interlayer pressure level will be higher than the pressure at other locations in the tank interlayer. Normally, the interlayer pressure is better than 1.00×10 -2 Pa is required to achieve a good insulation effect. Specifically, the wrapping and winding method of multi-layer insulation materials, as well as the number of layers and layer density configuration, will all affect the interlayer pressure. For example, increasing the number of insulation layers will increase the vacuum resistance, making it more difficult to evacuate the gas between the layers, which in turn affects the insulation performance. Currently, the measurement and analysis of the insulation performance of high-vacuum multi-layer insulation materials is mostly carried out under unknown interlayer pressure, making quantitative research difficult.

[0003] In order to explore the vacuum resistance performance of multi-layer insulation materials and reveal the pressure level between layers, there are three main treatment methods in the existing literature.

[0004] One approach is to indirectly measure interlayer pressure using a capillary tube, as described in Chinese patent application publication number CN115238506A. During the test, a capillary tube is placed between layers of multilayer insulation material, and the pressure at the top of the capillary tube is measured using an ionization gauge. However, the use of a capillary tube can damage the insulation material, affecting its performance. Furthermore, the ionization gauge operates by ionizing gas molecules into ions under the influence of electric and magnetic fields. The interlayers of multilayer insulation material contain a rarefied gas, and the capillary tube has an extremely small diameter (1 mm; increasing the diameter increases parasitic heat leakage from the insulation material). This results in a significant deviation between the pressure measured by the ionization gauge and the interlayer pressure.

[0005] The second method is to use a self-made interlayer pressure measurement device developed by SLBapat et al. This device consists of a flexible disk mounted in a multilayer insulation material, along with a heating filament and thermocouple mounted on it. The heating filament and thermocouple serve as the thermocouple vacuum gauge elements for interlayer pressure measurement. However, the addition of the disk, thermocouple, and heating filament will damage the insulation material. Furthermore, due to the use of thermocouple sensitive elements, the minimum pressure measurement range is 133.32×10 -3Pa.

[0006] Finally, a vacuum resistance performance measurement device, disclosed in Chinese patent application publication number CN108489854A, was used. This device divides the inner liner into two parts, upper and lower, and places an ionization gauge in the area between the two liner to measure pressure. However, the ionization gauge is essentially inoperable in ultra-low temperature environments (the lowest normal temperature of semiconductor components is typically 213.15K. As the temperature decreases, the performance of the semiconductor component gradually weakens and eventually fails). When liquid helium, liquid hydrogen, or liquid nitrogen is placed in the inner liner, the temperature of the ionization gauge measuring end between the two liner can reach 4K, 20K, or 77K, respectively. At these times, the measured vacuum level deviates significantly from the actual result.

[0007] In summary, existing devices for measuring the vacuum resistance characteristics of multi-layer insulation materials often have the problem of damaging the insulation materials, and there is a large deviation between the measurement results and the actual interlayer pressure. Summary of the Invention

[0008] In order to solve the above-mentioned problems of the prior art, the present invention provides a device and method for testing the vacuum resistance characteristics of multi-layer insulation materials of low-temperature storage tanks, which ensures that the insulation materials are not damaged and improves the measurement accuracy.

[0009] The present invention is achieved through the following technical solutions:

[0010] In the first aspect, the present invention provides a device for testing the vacuum resistance characteristics of multi-layer thermal insulation materials of low-temperature storage tanks, comprising: a cover plate and an outer shell, the outer shell and the cover plate are sealed and connected to form a closed cavity, and an upper protection cavity, a test cavity and a lower protection cavity are sequentially arranged in the closed cavity from top to bottom; the side walls, bottom plate and outer surfaces of the top plate of the upper protection cavity and the lower protection cavity are all covered with multi-layer thermal insulation materials, the side walls and outer surfaces of the bottom plate of the test cavity are all covered with multi-layer thermal insulation materials, a copper plate is arranged parallel to the top plate of the test cavity and the upper protection cavity, the edge of the top plate of the test cavity is connected to the edge of the copper plate by a wire mesh, and the outer sides of the wire mesh and the copper plate are covered with multi-layer insulation materials. thermal material; the copper plate is connected to the bottom plate of the upper protection cavity through a copper column, and the outer surface of the copper column is covered with multiple layers of insulation material; the area between the upper protection cavity, the test cavity and the lower protection cavity and the outer shell is a vacuum interlayer, and a first vacuum gauge for measuring the pressure in the vacuum interlayer is provided on the cover plate; a rewarming pipe is provided on the cover plate, one end of the rewarming pipe is inserted into the area between the copper plate and the top plate of the test cavity, and the other end extends out of the cover plate and is connected to a second vacuum gauge; a vacuum pump is connected to the side wall of the outer shell; the upper protection cavity and the test cavity are both connected to a low-temperature liquid filling pipe and an emptying pipe, and the upper protection cavity and the lower protection cavity are connected through a pipe.

[0011] Preferably, the first vacuum gauge is a full-range gauge, and the second vacuum gauge is an ionization gauge.

[0012] Preferably, the top plate of the test chamber is made of polyester foam insulation material.

[0013] Preferably, a check valve is provided on one end of the exhaust pipe of the upper protective chamber extending out of the cover plate.

[0014] Preferably, a first gate valve and a mass flow meter are provided on one end of the exhaust pipe of the test chamber extending out of the cover plate, and the first gate valve is located between the mass flow meter and the cover plate.

[0015] Furthermore, an air cooling screen is provided in the multi-layer insulation material on the outer surface of the side wall of the test cavity.

[0016] Furthermore, a second gate valve is connected between the air-cooled screen and the exhaust pipe of the test chamber through a pipe, and the second gate valve is located in the shell. The air-cooled screen is also connected to the connecting pipe between the first gate valve and the mass flow meter through a pipe.

[0017] In a second aspect, the present invention provides a method for testing the vacuum resistance characteristics of multi-layer thermal insulation materials for cryogenic storage tanks, based on the above-mentioned apparatus for testing the vacuum resistance characteristics of multi-layer thermal insulation materials for cryogenic storage tanks, comprising:

[0018] Step 1: Apply multiple layers of insulation material to the outer surfaces of the side walls, bottom plate, and top plate of the upper and lower protective cavities according to the required layer density and number of layers, and also to the side walls and bottom plate of the test cavity, as well as the outer surfaces of the wire mesh, copper plate, and copper rod;

[0019] Step 2: Place the upper protection cavity, test cavity, and lower protection cavity in step 1 into the housing, and seal the cover plate to the housing;

[0020] Step 3: Use a vacuum pump to evacuate the vacuum interlayer;

[0021] Step 4: When the pressure values ​​of the first vacuum gauge and the second vacuum gauge are both lower than 0.01 Pa, inject cryogenic liquid into the upper protection chamber, the lower protection chamber, and the test chamber through the cryogenic liquid filling pipe;

[0022] Step 5: Read the vacuum degrees of the first vacuum gauge and the second vacuum gauge, and calculate the vacuum resistance characteristics based on the read vacuum degrees.

[0023] Preferably, in the method for testing the vacuum resistance characteristics of multi-layer insulation materials for cryogenic storage tanks, a first gate valve and a mass flow meter are provided on one end of the exhaust pipe of the test chamber extending out of the cover plate;

[0024] In step 5: When the mass flow meter reading is stable, read the vacuum degree of the full range gauge and the ionization gauge.

[0025] Furthermore, in the method for testing the vacuum resistance characteristics of multi-layer insulation materials for cryogenic storage tanks, an air-cooling screen is provided in the multi-layer insulation material on the outer surface of the side wall of the test chamber, and a second gate valve is connected between one end of the air-cooling screen extending out of the multi-layer insulation material and the exhaust pipe of the test chamber. The second gate valve is located in the housing, and the air-cooling screen is also connected to the connecting pipe between the first gate valve and the mass flow meter through a pipe.

[0026] In step 5: close the second gate valve, open the first gate valve, and when the mass flow meter reading is stable, read the vacuum degree of the full-scale gauge and the ionization gauge; or close the first gate valve, open the second gate valve, and when the mass flow meter reading is stable, read the vacuum degree of the full-scale gauge and the ionization gauge.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The method for measuring the interlayer pressure of the multilayer insulation material of the present invention is to cover a test chamber with a specific number of layers of the multilayer insulation material, and then measure the pressure in the area between the copper plate and the test chamber using a second vacuum gauge to obtain the interlayer pressure of the corresponding number of layers of insulation material. Due to the influence of the gas flow resistance between the multilayer insulation material, there is a difference between the interlayer pressure of the insulation material and the pressure within the vacuum interlayer. The difference between the two is the vacuum resistance performance of the multilayer insulation material. The second vacuum gauge of the present invention measures the pressure in the area between the copper plate and the test chamber, and there is no need to place the second vacuum gauge in the multilayer insulation material, thus ensuring that the insulation material is not damaged. The second vacuum gauge of the present invention connects the area between the copper plate and the top plate of the test chamber via a reset pipe. The rewarming pipe ensures that the temperature of the measuring end of the second vacuum gauge is higher than 263.15 K. This eliminates the need for the second vacuum gauge to be exposed to low temperatures, thus avoiding the increase in measurement errors caused by the weakening of semiconductor performance in low-temperature environments. This improves measurement accuracy and enables the measurement of the vacuum resistance performance of multi-layer insulation materials in cryogenic storage tanks in any temperature range (such as liquid helium temperature of 4.2 K, liquid hydrogen temperature of 20 K, and liquid nitrogen temperature of 77 K). In addition, compared with the combination of filaments and thermocouples to measure interlayer pressure, the present device uses a vacuum gauge to measure interlayer pressure, and the measurement range can be expanded to 1×10 -5 Pa, and the measurement accuracy is higher.

[0029] Furthermore, the first vacuum gauge of the present invention utilizes a full-range gauge, while the second vacuum gauge utilizes an ionization gauge. Because the vacuum level varies widely during the evacuation process, a full-range gauge, with its wide measuring range, can be used to measure the vacuum level within the vacuum interlayer and guide the opening and closing of the vacuum pump. In steady-state conditions, the interlayer pressure is in a high vacuum state, and an ionization gauge can meet these high-vacuum measurement requirements.

[0030] Furthermore, in order to avoid heat leakage in the test cavity due to temperature difference between the copper plate and the test cavity, the top plate of the test cavity is made of polyester foam insulation material, which can play an insulating role, thereby avoiding heat exchange between the test cavity and the copper plate.

[0031] Furthermore, a check valve is provided on one end of the exhaust pipe of the upper protection chamber extending out of the cover plate of the present invention, and the check valve is used to control the exhaust pressure of the upper protection chamber to avoid danger caused by excessive pressure in the upper protection chamber.

[0032] Furthermore, a first gate valve and a mass flow meter are provided on one end of the exhaust pipe of the test chamber extending out of the cover plate. The mass flow meter is used to measure the steam emission mass flow rate of the test chamber, and the heat leakage of the test chamber can be calculated based on the steam emission mass flow rate.

[0033] Furthermore, an air-cooled shield is installed within the multi-layer insulation material on the outer surface of the sidewall of the test chamber. A second gate valve is connected between the air-cooled shield and the test chamber's exhaust pipe via a pipe. The second gate valve is located within the housing. The first and second gate valves control the exhaust flow path of the test chamber. There are two options for evaporating gas from the test chamber: one is to be directly discharged through the pipe to the exterior of the housing via the first gate valve, and the other is to be introduced into the air-cooled shield through the pipe via the second gate valve, and then discharged from the air-cooled shield to the exterior of the housing. When the gas discharged from the test chamber enters the air-cooled shield through the pipe, the relatively low temperature of the evaporating gas can be cooled within the air-cooled shield, thereby recycling the cooling energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 Schematic diagram of the structure of the vacuum resistance characteristic measuring device of the present invention.

[0036] In the figure: 1. First vacuum gauge; 2. Second vacuum gauge; 3. Rewarming pipe; 4. Check valve; 5. First gate valve; 6. Mass flow meter; 7. Cover plate; 8. Vacuum pump; 9. Upper protective chamber; 10. Second gate valve; 11. Copper rod; 12. Copper plate; 13. Wire mesh; 14. Polyester foam insulation material; 15. Air-cooled screen; 16. Test chamber; 17. Lower protective chamber; 18. Multi-layer insulation material; 19. Housing. DETAILED DESCRIPTION

[0037] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0038] It should be noted that the process equipment or devices not specifically specified in the following embodiments are all conventional equipment or devices in the art.

[0039] It should be noted that the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or apparatuses. Furthermore, unless otherwise specified, the numbering of each method step is merely a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to define the scope of the invention. Changes or adjustments to their relative relationships, without substantially changing the technical content, should also be considered within the scope of the invention.

[0040] Furthermore, it should be noted that the terms "first," "second," and the like are used to distinguish similar objects and are not necessarily used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than that illustrated or described herein. The terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" and the like, indicating positions or relationships, are based on the positions or relationships shown in the accompanying drawings and are intended solely for the purpose of facilitating the description of the present invention and simplifying the description. They are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation, and are therefore not to be construed as limiting the present invention. Furthermore, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly, for example, to mean a fixed connection or a detachable connection; a direct connection or an indirect connection through an intermediate medium; or internal communication between two components.

[0041] like Figure 1As shown, in an embodiment of the present invention, the device for testing the vacuum resistance characteristics of multi-layer thermal insulation materials of low-temperature storage tanks includes: a first vacuum gauge 1, a second vacuum gauge 2, a rewarming pipe 3, a check valve 4, a first gate valve 5, a mass flow meter 6, a cover plate 7, a vacuum pump 8, an upper protective chamber 9, a second gate valve 10, a copper rod 11, a copper plate 12, a wire mesh 13, an air-cooled shield 15, a test chamber 16, a lower protective chamber 17, a multi-layer thermal insulation material 18 and a shell 19.

[0042] The vacuum pump 8 is installed on the side wall of the outer shell 19; the outer shell 19 is sealed with the cover plate 7 to form a closed cavity, and the upper protective cavity 9, the test cavity 16, and the lower protective cavity 17 are all arranged in the closed cavity. The area between the upper protective cavity 9, the test cavity 16, the lower protective cavity 17 and the outer shell 19 is a vacuum interlayer, and the vacuum pump 8 is used to evacuate the vacuum interlayer. A first vacuum gauge 1 for measuring the pressure in the vacuum interlayer is provided on the cover plate 7. The upper protective cavity 9 and the test cavity 16 are both connected to a low-temperature liquid filling pipe and an emptying pipe, and the upper protective cavity 9 and the lower protective cavity 17 are connected through a pipe. The present invention respectively arranges an upper protective cavity 9 and a lower protective cavity 17 above and below the test cavity 16. When in use, the low-temperature liquid injected into the upper protective cavity 9 and the lower protective cavity 17 can reduce the heat leakage of the test cavity 16, so that the test can be carried out normally.

[0043] The outer surfaces of the side walls, bottom plate, and top plate of the upper and lower protective chambers 9 and 17 are all coated with multiple layers of thermal insulation material 18. The outer surfaces of the side walls and bottom plate of the test chamber 16 are also coated with multiple layers of thermal insulation material 18. A copper plate 12 is positioned parallel to the top plate of the test chamber 16 and the upper protective chamber 9. The edges of the top plate of the test chamber 16 and the edges of the copper plate 12 are connected by a wire mesh 13. The outer surfaces of the wire mesh 13 and the copper plate 12 are both coated with multiple layers of thermal insulation material 18. The copper plate 12 is connected to the bottom plate of the upper protective chamber 9 via a copper rod 11. The outer surfaces of the side walls of the copper rod 11 are also coated with multiple layers of thermal insulation material 18. A rewarming pipe 3 is provided on the cover plate 7. One end of the rewarming pipe 3 is inserted into the area between the copper plate 12 and the top plate of the test chamber 16. The other end extends outside the cover plate 7 and is connected to a second vacuum gauge 2. The second vacuum gauge 2 is used to measure the pressure in the area between the copper plate 12 and the top plate of the test chamber 16.

[0044] A sufficient number of copper rods 11 (greater than four) are provided between the copper plate 12 and the upper protective cavity 9 to ensure that the temperature difference between the copper plate 12 and the upper protective cavity 9 is less than 2 K. To prevent heat leakage from the test cavity 16 due to a temperature difference between the copper plate 12 and the test cavity 16, the top plate of the test cavity 16 is made of polyester foam insulation material 14. The polyester foam insulation material 14 provides insulation, thereby preventing heat exchange between the test cavity 16 and the copper plate 12.

[0045] The present invention provides a copper plate 12, connected to the upper protective chamber 9 via a copper column 11, so that the temperature of the copper plate 12 is substantially consistent with the temperature within the upper protective chamber 9. This allows the copper plate 12 to maintain a temperature substantially consistent with that of the test chamber 16, thus preventing heat leakage from the test chamber 16. When a vacuum pump 8 is used to evacuate the chamber, the pressure in the area between the copper plate 12 and the top plate of the test chamber 16 is the same as the pressure within the multilayer insulation material 18 outside this area. Therefore, the pressure in the area between the copper plate 12 and the top plate of the test chamber 16, measured by a second vacuum gauge 2, reflects the pressure within the multilayer insulation material 18. The difference between this pressure and the pressure within the vacuum interlayer is the vacuum resistance of the multilayer insulation material 18.

[0046] The present invention does not require placement of the second vacuum gauge 2 within the multi-layer insulation material 18, thereby preventing damage to the multi-layer insulation material 18. Furthermore, the second vacuum gauge 2 of the present invention communicates with the area between the copper plate 12 and the top plate of the test chamber 16 via the reset pipe 3. The rewarming pipe 3 is sufficiently long (greater than 0.1 m) to maintain the temperature at the measuring end of the second vacuum gauge 2 above 263.15 K. Consequently, the second vacuum gauge 2 does not need to be exposed to low temperatures, thereby avoiding increased measurement errors caused by weakened semiconductor performance in low-temperature environments. This allows measurement of the vacuum resistance performance of the multi-layer insulation material of cryogenic storage tanks in any temperature range (e.g., liquid helium temperature of 4.2 K, liquid hydrogen temperature of 20 K, and liquid nitrogen temperature of 77 K).

[0047] The exhaust pipe of the upper protective chamber 9 of the present invention is equipped with a check valve 4 at one end extending outside the cover plate 7. Because the cryogenic liquid in the upper protective chamber 9 may evaporate, the evaporated gas needs to be discharged through the exhaust pipe. The check valve 4 is used to control the exhaust pressure of the upper protective chamber 9. When the check valve 4 is open, the pressure in the upper protective chamber 9 is greater than 0.103 MPa.

[0048] A first gate valve 5 and a mass flowmeter 6 are provided at one end of the exhaust pipe of the test chamber 16 extending outside the cover plate 7. The first gate valve 5 is located between the mass flowmeter 6 and the cover plate 7. An air-cooling shield 15 is provided within the multi-layer insulation material 18 on the outer surface of the side wall of the test chamber 16. The air-cooling shield 15 is connected to the exhaust pipe of the test chamber 16 via a pipe through a second gate valve 10. The second gate valve 10 is located within a housing 19. The air-cooling shield 15 is also connected to the connecting pipe between the first gate valve 5 and the mass flowmeter 6 via a pipe.

[0049] The mass flowmeter 6 measures the mass flow rate of steam discharged from the test chamber 16. Heat leakage from the test chamber 16 can be calculated based on the steam discharge mass flow rate. The first gate valve 5 and the second gate valve 10 control the discharge path of the test chamber 16. There are two options for evaporation from the test chamber 16: direct discharge through the first gate valve 5 via a pipeline to the exterior of the housing, or direct discharge through the second gate valve 10 via a pipeline to the air-cooled shield 15, from which it is then discharged to the exterior of the housing. When the evaporation gas from the test chamber 16 enters the air-cooled shield 15 through the pipeline, the pipeline should connect from the test chamber 16 to the area between the copper plate 12 and the upper protective chamber 9 to avoid damage to the wire mesh 13 and the multi-layer insulation material 18 on the sidewalls. When the evaporation gas from the test chamber 16 is introduced into the air-cooled shield 15 through the second gate valve 10, the relatively low temperature of the evaporation gas allows it to cool the air-cooled shield 15, effectively recycling the cooling energy.

[0050] In the embodiment of the present invention, the first vacuum gauge 1 is preferably a full-scale gauge, and the second vacuum gauge 2 is preferably an ionization gauge. Because the vacuum level varies widely during the evacuation process, a full-scale gauge, with its wide measuring range, can be used to measure the vacuum level within the vacuum interlayer and guide the opening and closing of the vacuum pump. In steady-state conditions, the interlayer pressure is in a high vacuum state, and an ionization gauge can meet these high-vacuum measurement requirements.

[0051] In the embodiment of the present invention, the vacuum pump 8 is a molecular pump unit.

[0052] The method for testing the vacuum resistance characteristics of multi-layer insulation materials for cryogenic storage tanks of the present invention comprises the following steps:

[0053] Step 1: Apply multi-layer insulation material 18 to the outer surfaces of the side walls, bottom plate, and top plate of the upper protection cavity 9 and the lower protection cavity 17 according to the layer density configuration and layer number requirements, and to the side walls and bottom plate of the test cavity 16 and the outer surfaces of the wire mesh 13, copper plate 12, and copper rod 11;

[0054] Step 2: Place the upper protection chamber 9, test chamber 16 and lower protection chamber 17 in step 1 into the housing 19, and then seal the cover plate 7 and the housing 19 with a flange;

[0055] Step 3: Use the vacuum pump 8 to evacuate the vacuum interlayer. Due to the resistance of gas flow between the layers of the multi-layer insulation material 18, there is a difference in the vacuum degree between the area between the copper plate 12 and the test cavity 16 and the vacuum interlayer;

[0056] Step 4: When the pressure values ​​of the first vacuum gauge 1 and the second vacuum gauge 2 in step 3 are both lower than 0.01 Pa, inject cryogenic liquid into the upper protection chamber 9, the lower protection chamber 17 and the test chamber 16;

[0057] Step 5: When the mass flow meter 6 reading is stable, read the vacuum degree of the first vacuum gauge 1 and the second vacuum gauge 2 to obtain the vacuum resistance characteristics of the insulation material under a specific layer density configuration, number of layers, and winding method.

Claims

1. A device for testing the vacuum resistance characteristics of multi-layer insulation materials for cryogenic storage tanks, characterized in that: include: The cover plate (7) and the shell (19) are sealed and connected to the cover plate (7) to form a closed cavity. The closed cavity is provided with an upper protective cavity (9), a test cavity (16) and a lower protective cavity (17) in sequence from top to bottom. The side walls, bottom plates and outer surfaces of the top plates of the upper protective cavity (9) and the lower protective cavity (17) are all covered with multiple layers of thermal insulation material (18). The side walls and outer surfaces of the bottom plates of the test cavity (16) are all covered with multiple layers of thermal insulation material (18). A copper plate (12) is arranged parallel between the top plate of the test cavity (16) and the upper protective cavity (9). The edge of the top plate of the test cavity (16) and the edge of the copper plate (12) are connected by a wire mesh (13). The outer sides of the wire mesh (13) and the copper plate (12) are both covered with multiple layers of thermal insulation material (18). The copper plate (12) is connected to the upper protective cavity (9) through a copper column (11). The bottom plate of the protective cavity (9) is connected, and the outer surface of the copper column (11) is covered with multiple layers of insulation material (18); the area between the upper protective cavity (9), the test cavity (16) and the lower protective cavity (17) and the shell (19) is a vacuum interlayer, and a first vacuum gauge (1) for measuring the pressure in the vacuum interlayer is provided on the cover plate (7); a rewarming pipe (3) is provided on the cover plate (7), one end of the rewarming pipe (3) is inserted into the area between the copper plate (12) and the top plate of the test cavity (16), and the other end extends out of the cover plate (7) and is connected to the second vacuum gauge (2); a vacuum pump (8) is connected to the side wall of the shell (19); a low-temperature liquid filling pipe and an emptying pipe are connected to the upper protective cavity (9) and the test cavity (16), and the upper protective cavity (9) and the lower protective cavity (17) are communicated through a pipe.

2. The device for testing vacuum resistance characteristics of multi-layer insulation materials for cryogenic storage tanks according to claim 1 is characterized in that: The first vacuum gauge (1) is a full-range gauge, and the second vacuum gauge (2) is an ionization gauge.

3. The device for testing vacuum resistance characteristics of multi-layer insulation materials for cryogenic storage tanks according to claim 1 is characterized in that: The top plate of the test chamber (16) is made of polyester foam insulation material (14).

4. The device for testing vacuum resistance characteristics of multi-layer insulation materials for cryogenic storage tanks according to claim 1 is characterized in that: A check valve (4) is provided on one end of the exhaust pipe of the upper protective chamber (9) extending outside the cover plate (7).

5. The device for testing vacuum resistance characteristics of multi-layer insulation materials for cryogenic storage tanks according to claim 1 is characterized in that: A first gate valve (5) and a mass flow meter (6) are provided on one end of the exhaust pipe of the test chamber (16) extending outside the cover plate (7), and the first gate valve (5) is located between the mass flow meter (6) and the cover plate (7).

6. The device for testing vacuum resistance characteristics of multi-layer insulation materials for cryogenic storage tanks according to claim 5 is characterized in that: An air cooling screen (15) is provided in the multi-layer heat insulating material (18) on the outer surface of the side wall of the test cavity (16).

7. The device for testing vacuum resistance characteristics of multi-layer insulation materials for cryogenic storage tanks according to claim 6 is characterized in that: The air-cooling screen (15) is connected to the exhaust pipe of the test chamber (16) through a pipe with a second gate valve (10), the second gate valve (10) is located in the housing (19), and the air-cooling screen (15) is also connected to the connecting pipe between the first gate valve (5) and the mass flow meter (6) through a pipe.

8. A method for testing the vacuum resistance characteristics of multi-layer insulation materials for cryogenic storage tanks, characterized in that: The device for testing vacuum resistance characteristics of multi-layer insulation materials for cryogenic storage tanks according to any one of claims 1 to 7 comprises: Step 1: Covering the side walls, bottom plate and top plate outer surfaces of the upper protection cavity (9) and the lower protection cavity (17) with a multilayer thermal insulation material (18) according to the layer density configuration and layer number requirements, and covering the side walls and bottom plate of the test cavity (16) and the outer surfaces of the wire mesh (13), the copper plate (12) and the copper rod (11); Step 2: Place the upper protective cavity (9), the test cavity (16), and the lower protective cavity (17) of step 1 into the housing (19), and seal the cover plate (7) to the housing (19); Step 3: Using a vacuum pump (8) to evacuate the vacuum interlayer; Step 4: When the pressure values ​​of the first vacuum gauge (1) and the second vacuum gauge (2) are both lower than 0.01 Pa, inject cryogenic liquid into the upper protection chamber (9), the lower protection chamber (17) and the test chamber (16) through the cryogenic liquid filling pipe; Step 5: Read the vacuum degrees of the first vacuum gauge (1) and the second vacuum gauge (2), and calculate the vacuum resistance characteristics based on the read vacuum degrees.

9. The method for testing vacuum resistance characteristics of multi-layer insulation materials for cryogenic storage tanks according to claim 8, characterized in that: A first gate valve (5) and a mass flow meter (6) are provided on one end of the exhaust pipe of the test chamber (16) extending out of the cover plate (7); In step 5: When the mass flow meter (6) reading is stable, read the vacuum degree of the full range gauge (1) and the ionization gauge (2).

10. The method for testing vacuum resistance characteristics of multi-layer insulation materials for cryogenic storage tanks according to claim 9, characterized in that: An air-cooling screen (15) is provided in the multi-layer insulation material (18) on the outer surface of the side wall of the test chamber (16); a second gate valve (10) is connected between one end of the air-cooling screen (15) extending out of the multi-layer insulation material (18) and an exhaust pipe of the test chamber (16); the second gate valve (10) is located in the housing (19); and the air-cooling screen (15) is further connected to a connecting pipe between the first gate valve (5) and the mass flow meter (6) through a pipe; In step five: close the second gate valve (10), open the first gate valve (5), and when the mass flow meter (6) reading is stable, read the vacuum degree of the full-scale gauge (1) and the ionization gauge (2); or close the first gate valve (5), open the second gate valve (10), and when the mass flow meter (6) reading is stable, read the vacuum degree of the full-scale gauge (1) and the ionization gauge (2).

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