Liquid nitrogen storage tanks and processing systems

Abstract

The present invention discloses a liquid nitrogen storage tank and processing system, relating to the field of thermal insulation structure technology. The liquid nitrogen storage tank includes an outer shell, an inner liner, and an insulation structure. The inner liner is disposed within the outer shell and is used to store liquid nitrogen. The insulation structure is disposed between the inner liner and the outer shell and includes a plurality of stacked reflective layers and a plurality of spacer layers, the plurality of reflective layers and the plurality of spacer layers being alternately arranged. The reflective layers are used to reflect infrared radiation, and the spacer layers are foamed aluminum layers that are used to provide physical support and heat insulation for two adjacent reflective layers. The technical solution provided by the present invention improves the stability of liquid nitrogen during storage, prevents explosion of the liquid nitrogen storage tank, and thus makes the processing system using the liquid nitrogen storage tank more stable.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal insulation structures, in particular to a liquid nitrogen storage tank and a processing system. Background Art

[0002] A prominent issue in existing research and practice regarding liquid nitrogen technology is its poor storage stability. During storage, liquid nitrogen is highly susceptible to temperature fluctuations, resulting in unstable storage conditions. This temperature sensitivity leads to increased evaporation losses and dramatic pressure fluctuations within storage containers, making them susceptible to explosion and compromising their proper use in processing systems. Summary of the Invention

[0003] The main purpose of the present invention is to propose a liquid nitrogen storage tank and processing system, aiming to improve the stability of liquid nitrogen during storage and avoid explosion of liquid nitrogen storage tanks, thereby making the processing system more stable when using liquid nitrogen storage tanks.

[0004] To achieve the above objectives, the present invention proposes a liquid nitrogen storage tank, which includes an outer shell, an inner liner and an insulation structure. The inner liner is arranged in the outer shell and is used to store liquid nitrogen; the insulation structure is arranged between the inner liner and the outer shell, and the insulation structure includes a plurality of stacked reflective layers and a plurality of spacer layers, and the plurality of reflective layers and the plurality of spacer layers are alternately arranged. The reflective layer is used to reflect infrared radiation, and the spacer layer is a foam aluminum layer, which is used to provide physical support and heat insulation for two adjacent reflective layers.

[0005] In one embodiment, the liquid nitrogen storage tank further comprises a release valve, wherein the release valve comprises:

[0006] a valve body, the valve body being disposed at the top of the housing, the valve body comprising a valve cavity, a through-hole communicating with the valve cavity, an air inlet, an air outlet, and a conducting hole, the air inlet being located at the bottom of the valve body, the air outlet being located at the side of the valve body, the through-hole being located at the top center of the valve body, and the conducting hole being located between the air inlet and the air outlet;

[0007] a valve stem movably connected to the valve cavity;

[0008] a valve core connected to one end of the valve stem and movably connected between the guide hole and the air inlet hole; and

[0009] A thermal expansion element is connected to an end of the valve stem away from the valve core, and the end of the thermal expansion element away from the valve stem extends between the inner liner and the insulation structure and contacts the inner liner and the insulation structure, and is used to sense the temperature of the insulation structure to drive the valve stem to push the valve core closer to or away from the guide hole.

[0010] In one embodiment, the thermal expansion element includes a deformable diaphragm and a temperature sensing component connected to the deformable diaphragm, the temperature sensing component extends from the through-hole to between the inner liner and the thermal insulation structure, and contacts the inner liner and the thermal insulation structure. A lever amplification mechanism is provided on the side of the deformable diaphragm away from the temperature sensing component, and is connected to the valve stem through the lever amplification mechanism.

[0011] In one embodiment, the temperature sensing element includes a plurality of temperature sensing parts and a thermally conductive strip connected to the plurality of temperature sensing parts. The thermally conductive strip is connected to the deformable diaphragm and extends from the through-hole. The plurality of temperature sensing parts are axially spaced apart along the outer surface of the inner tank and are all connected to the thermally conductive strip. Two adjacent temperature sensing parts are connected.

[0012] In one embodiment, the surface of the temperature sensing element is coated with a nano-aluminum oxide coating to reflect residual radiant heat.

[0013] In one embodiment, the liquid nitrogen storage tank further includes a condensation recovery container and a liquid nitrogen delivery pump. The condensation recovery container is connected to the air outlet of the valve body and is used to recover high-pressure nitrogen and liquefy the high-pressure nitrogen into liquid nitrogen; the liquid nitrogen delivery pump is connected to the condensation recovery container and the inner tank and is used to start when the pressure of the inner tank is lower than a set threshold and deliver the condensed liquid nitrogen into the inner tank.

[0014] In one embodiment, the aluminum foam is a closed-cell aluminum foam; or, the pores of the aluminum foam are filled with fumed silica powder.

[0015] In one embodiment, a flexible base film is provided on the surface of each of the reflective layers, and the flexible base film is used to increase the flexibility of the reflective layer;

[0016] And / or, an aluminum coating is provided on the surface of the flexible base film, and the aluminum coating is used to reflect infrared radiation;

[0017] And / or, glass fiber mesh cloth is embedded in the spacer layer to enhance its structural rigidity.

[0018] In one embodiment, the outer side of the thermal insulation structure is covered with a vacuum layer, and the vacuum layer includes:

[0019] porous core material; and

[0020] A barrier film is coated on the outer surface of the porous core material and is vacuum-sealed to block gas heat conduction; and the porous core material is fumed silica or glass fiber felt.

[0021] The present invention further provides a processing system, comprising:

[0022] Processing control host;

[0023] A processing main device, which is electrically connected to the processing control host and is used to perform processing operations on the product;

[0024] an alarm auxiliary device, the alarm auxiliary device being electrically connected to the processing control host and being used to remind personnel to carry out accident prevention work upon receiving an alarm signal sent by the processing control host; and

[0025] As described above, the liquid nitrogen storage tank has an electric control valve, and the release valve of the liquid nitrogen storage tank has an air intake pipe connected to the air intake hole. The electric control valve is provided in the air intake pipe and is connected to the processing control host and the electrical connection, and is used to open and close the air intake pipe when receiving a signal from the processing control host in a non-discharge state.

[0026] The liquid nitrogen storage tank of the technical solution of the present invention includes an outer shell, an inner liner, and an insulation structure. The inner liner is arranged in the outer shell and is used to store liquid nitrogen. The insulation structure is arranged between the inner liner and the outer shell. The insulation structure includes multiple reflective layers and multiple spacer layers arranged in a stacked manner. The multiple reflective layers and the multiple spacer layers are arranged alternately. The reflective layers are used to reflect infrared radiation. The spacer layers are foamed aluminum layers, which are used to provide physical support and heat insulation for two adjacent reflective layers. The reflective layers actively block radiant heat, and the foamed aluminum layers suppress conductive heat, forming a synergistic insulation effect. The synergistic effect of the reflective layers and the foamed aluminum layers improves the insulation performance, effectively reduces the amount of heat intrusion during liquid nitrogen storage, slows the evaporation rate of liquid nitrogen, improves the stability of liquid nitrogen during storage, and avoids explosion of the liquid nitrogen storage tank, thereby making the processing system more stable when using the liquid nitrogen storage tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] 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 only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0028] Figure 1 A front view of the liquid nitrogen storage tank provided by the present invention;

[0029] Figure 2 A longitudinal cross-sectional view of one side inner wall of the liquid nitrogen storage tank provided by the present invention;

[0030] Figure 3 A schematic structural diagram of a release valve for a liquid nitrogen storage tank provided by the present invention;

[0031] Figure 4 This is a structural diagram of the liquid nitrogen storage tank provided by the present invention with a temperature sensing portion arranged therein;

[0032] Figure 5 A longitudinal cross-sectional view of the reflective layer of the liquid nitrogen storage tank provided by the present invention;

[0033] Figure 6 This is a schematic structural diagram of the spacer layer of the liquid nitrogen storage tank provided by the present invention.

[0034] Description of Figure Numbers:

[0035] 10. Outer shell; 20. Insulation structure; 21. Reflective layer; 21a. Flexible base film; 21b. Aluminum-plated layer; 22. Spacer layer; 22a. Glass fiber mesh cloth; 23. Vacuum layer; 231. Porous core material; 232. Barrier film; 24. Moisture-proof layer; 25. Protective layer; 30. Inner liner; 40. Release valve; 41. Valve body; 41a. Valve cavity; 41b. Perforation; 41c. Air inlet; 41d. Air outlet; 41e. Through hole; 42. Valve stem; 43. Valve core; 44. Thermal expansion element; 441. Deformable diaphragm; 442. Temperature sensing element; 442a. Temperature sensing part; 442b. Thermal conductive strip; 50. Condensation recovery container; 60. Liquid nitrogen delivery pump.

[0036] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0038] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0039] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of such features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0040] In existing technology, liquid nitrogen storage containers generally face the problem of insufficient insulation performance. Traditional storage tanks often use a single insulating material to fill the interlayer between the inner liner and the outer shell. However, ambient temperature fluctuations can easily penetrate the container through heat conduction and radiation, causing the liquid nitrogen to evaporate faster. As the evaporation rate increases, the internal pressure of the container rises sharply, posing an explosion risk. For example, in industrial processing scenarios, when the ambient temperature around the storage tank rises, the pressure fluctuations caused by the rapid vaporization of liquid nitrogen can damage the structural integrity of the container.

[0041] Therefore, see Figure 1 and Figure 2 This application proposes a liquid nitrogen storage tank comprising an outer shell 10, an inner liner 30, and an insulation structure 20. The inner liner 30 is disposed within the outer shell 10 for storing liquid nitrogen. The insulation structure 20 is located between the inner liner 30 and the outer shell 10 and is composed of alternating layers of reflective layers 21 and spacer layers 22. The reflective layers 21 are used to reflect infrared radiation, and the spacer layers 22 are made of foamed aluminum material, which not only provides physical support for the adjacent reflective layers 21 but also isolates heat transfer through a closed-cell structure.

[0042] In this embodiment, the outer shell 10 refers to a rigid protective shell wrapped around the outside of the storage tank, which can be specifically made of stainless steel or aluminum alloy materials to resist external mechanical shocks. The inner liner 30 refers to a sealed container that is in direct contact with liquid nitrogen, which can be specifically made of a double-layer austenitic stainless steel welded structure to prevent low-temperature brittle fracture. The thermal insulation structure 20 refers to a composite thermal insulation layer arranged between the inner liner 30 and the outer shell 10, which can be specifically made by alternately laying a metal foil reflective layer 21 and a foam aluminum layer to form a multiple thermal barrier. The reflective layer 21 refers to a thin layer of material with high reflectivity, which can be specifically made of aluminum-plated polyester film, and its surface aluminum layer can reflect infrared radiation. The spacer layer 22 refers to a thermal insulation material layer with a supporting function.

[0043] Specifically, the reflective layer 21 and the foamed aluminum layer are alternately stacked to form a composite insulation barrier. When external heat is transferred by radiation, the aluminum-plated reflective layer 21 reflects most of the infrared rays back to the external environment. When the remaining heat enters the foamed aluminum layer by conduction, the closed pores inside it form a low thermal conductivity path, which significantly slows down the transfer of heat toward the inner liner 30. The foamed aluminum layer also provides rigid support for the adjacent reflective layer 21 to avoid interlayer collapse and the resulting decrease in thermal insulation performance. This structure forms a continuous thermal barrier layer in the axial direction, and maintains a low temperature environment of the inner liner 30 in the radial direction through a dual barrier mechanism of reflection and conduction.

[0044] Compared to existing technologies, traditional storage tanks often use glass wool or polyurethane foam as a single insulation layer, which only slows heat transfer due to the material's inherent low thermal conductivity. This solution, however, actively blocks radiant heat through a reflective layer 21, combined with the aluminum foam layer to inhibit conductive heat, creating a synergistic insulation effect. The rigid support properties of aluminum foam overcome the compressive deformation issues of traditional multi-layer insulation materials, ensuring the long-term stability of the insulation structure 20.

[0045] Through the above technical solution, the present application effectively reduces heat intrusion during liquid nitrogen storage, slowing the evaporation rate of liquid nitrogen, thereby maintaining a stable internal pressure in the tank. The synergistic effect of the reflective layer 21 and the aluminum foam layer improves thermal insulation performance. This structure also enhances the tank's resistance to mechanical impact and prevents localized thermal bridge effects caused by the collapse of the insulation layer.

[0046] See also Figures 1 to 3 The present application further proposes a liquid nitrogen storage tank, which also includes a release valve 40. The release valve 40 includes a valve body 41, a valve stem 42, a valve core 43, and a thermal expansion element 44. The valve body 41 is arranged at the top of the housing 10. The valve body 41 has a valve cavity 41a, a through-hole 41b connected to the valve cavity 41a, an air inlet 41c, an air outlet 41d, and a conducting hole 41e. The air inlet 41c is located at the bottom of the valve body 41, the air outlet 41d is located on the side of the valve body 41, the through-hole 41b is located at the top center of the valve body 41, and the conducting hole 41e is located between the air inlet 41c and the air outlet 41d. The valve stem 42 is movably connected to the valve cavity 41a. The valve core 43 is connected to one end of the valve stem 42 and is movably connected between the conducting hole 41e and the air inlet 41c. The thermal expansion element 44 is connected to the end of the valve stem 42 away from the valve core 43. The end of the thermal expansion element 44 away from the valve stem 42 extends between the inner liner 30 and the insulation structure 20, and contacts the inner liner 30 and the insulation structure 20. It is used to sense the temperature of the insulation structure 20 to drive the valve stem 42 to push the valve core 43 close to or away from the guide hole 41e.

[0047] The valve body 41 is a rigid structure used to create a gas passageway. Specifically, it can be cast from stainless steel or aluminum alloy. Its internal valve cavity 41a forms the gas flow space. The inlet 41c, the guide hole 41e, and the outlet 41d are precisely drilled using a CNC machine tool to create a directional airflow path. The valve stem 42 is a transmission component that transmits mechanical displacement. Specifically, it can be a chrome-plated steel rod, with axial movement achieved via a sliding bearing or linear guide. The valve core 43 is a sealing component that controls the flow of gas. Specifically, it can be a polytetrafluoroethylene-coated metal substrate with a conical sealing surface, forming a contact seal with the guide hole 41e. The thermal expansion element 44 is a driving component that deforms in response to temperature changes. When the temperature of the insulation structure 20 rises, the thermal expansion element 44 expands, pushing the valve stem 42 and the valve core 43 away from the guide hole 41e, connecting the inlet 41c with the outlet 41d and releasing pressure.

[0048] Specifically, when the temperature between the inner liner 30 and the insulation structure 20 rises due to the intrusion of external heat, the thermal expansion element 44 directly contacts this area and expands due to the heat, resulting in axial displacement. This displacement is transmitted to the valve core 43 through the valve stem 42, causing the valve core 43 to detach from the conduction hole 41e, and forming a passage between the air inlet 41c and the air outlet 41d. At this time, the high-pressure nitrogen generated by the evaporation of liquid nitrogen inside the inner liner 30 enters the valve cavity 41a through the air inlet 41c, and is discharged to the external recovery system through the air outlet 41d, thereby reducing the internal pressure of the storage tank. When the temperature drops to the safety threshold, the thermal expansion element 44 contracts and resets, driving the valve core 43 to reclose the conduction hole 41e and block the gas discharge. This process achieves autonomous pressure regulation through mechanical linkage without relying on external electricity or sensors.

[0049] Compared to existing technologies, traditional liquid nitrogen storage tanks use fixed pressure relief valves or electronically controlled valves that rely on external pressure sensors. The former cannot dynamically respond to pressure fluctuations caused by temperature changes, while the latter carries the risk of circuit failure and delayed response. This solution, through direct coupling of the thermal expansion element 44 with the mechanical transmission structure, synchronizes the pressure relief action with temperature changes in real time, avoiding reliability issues with electronic components while improving the accuracy of pressure control.

[0050] Through the above technical solution, the present application can quickly trigger the pressure relief mechanism when the temperature between the inner tank 30 and the insulation structure 20 rises abnormally, effectively suppressing the risk of tank rupture caused by the sudden increase in liquid nitrogen vapor pressure. At the same time, the pressure relief process is closed-loop controlled through physical contact temperature sensing, ensuring that pressure release is strictly matched to temperature conditions, reducing liquid nitrogen loss caused by unnecessary release.

[0051] See also Figures 2 to 4The present application further proposes that the thermal expansion element 44 includes a deformable diaphragm 441 and a temperature sensing component 442 connected to the deformable diaphragm 441. The temperature sensing component 442 extends from the through-hole 41b to between the inner liner 30 and the thermal insulation structure 20, and contacts the inner liner 30 and the thermal insulation structure 20. A lever amplification mechanism is provided on the side of the deformable diaphragm 441 away from the temperature sensing component 442, and is connected to the valve stem 42 through the lever amplification mechanism.

[0052] In this embodiment, the deformable diaphragm 441 refers to a metal or alloy material that can deform with temperature changes, such as a nickel-titanium alloy or a copper-based composite material, which converts temperature changes into mechanical displacement through the thermal expansion effect. The temperature sensing element 442 refers to a heat-conducting element that directly contacts the inner liner 30 and the insulation structure 20, such as a copper tube or aluminum bellows, which is used to quickly transmit temperature changes to the deformable diaphragm 441. The lever amplification mechanism refers to a mechanical structure composed of a fulcrum, a lever arm, and a connecting rod, such as a stainless steel hinge and connecting rod combination, which can amplify the tiny displacement of the deformable diaphragm 441 and transmit it to the valve stem 42.

[0053] Specifically, when the insulation structure 20 heats up due to heat infiltration, the temperature sensing element 442 transmits this temperature change to the deformable diaphragm 441, causing it to expand and deform. The deformation of the deformable diaphragm 441 is amplified by the lever-amplifying mechanism, which in turn drives the valve stem 42 to produce sufficient displacement, driving the valve core 43 to control the opening or closing of the conduction hole 41e. For example, when the temperature exceeds a set threshold, the lever-amplifying mechanism amplifies the tiny displacement of the deformable diaphragm 441, ensuring that the valve core 43 completely disengages the conduction hole 41e, thereby releasing pressure.

[0054] Compared to existing technologies, traditional thermal expansion element 44 typically utilizes a single metal rod or spring structure, which has limited deformation and slow response, making it incapable of precisely controlling the displacement of valve core 43. This solution, however, utilizes a combination of a deformable diaphragm 441 and a lever amplification mechanism to convert minute temperature changes into effective mechanical action. Furthermore, temperature sensing element 442 directly contacts inner liner 30 and insulation structure 20, enabling real-time detection of temperature anomalies.

[0055] Through the above-mentioned technical solution, the present application can improve temperature sensing sensitivity and mechanical response efficiency, quickly triggering pressure relief at the initial stage of failure of the insulation structure 20, thereby preventing the liquid nitrogen storage tank from exploding due to a sudden increase in internal pressure. Furthermore, the lever amplification mechanism reduces the material deformation threshold requirement of the deformable diaphragm 441, thereby extending the service life of the thermal expansion element 44.

[0056] See also Figures 2 to 4The present application further proposes that the temperature sensing element 442 includes a plurality of temperature sensing portions 442a and a heat-conducting strip 442b connected to the plurality of temperature sensing portions 442a. The heat-conducting strip 442b is connected to the deformable diaphragm 441 and extends from the through-hole 41b. The plurality of temperature sensing elements 442 are axially spaced apart along the outer surface of the inner tank 30 and are all connected to the heat-conducting strip 442b. Two adjacent temperature sensing portions 442a are connected.

[0057] In this embodiment, the temperature-sensing portion 442a comprises multiple independently distributed metal temperature-sensing units (e.g., copper cylinders) fixed to the outer surface of the inner liner 30 at axial intervals. They directly contact the innermost layer of the insulation structure 20 and capture local temperature rise signals (insulation failure points) in real time. A thermally conductive strip 442b, a highly thermally conductive metal strip, connects the multiple temperature-sensing portions 442a and extends to the through-hole 41b of the valve body 41. This strip collects heat from each temperature-sensing portion 442a and transmits the temperature change to the deformable diaphragm 441.

[0058] When insulation fails at a certain point, the local temperature of the outer wall of the inner liner 30 rises sharply from -196°C, causing the nearest temperature-sensing portion 442a to rapidly absorb heat. Adjacent temperature-sensing portions 442a are connected in parallel via heat-conducting strips 442b to form a heat network, transferring heat axially to the deformable diaphragm 441. Heated, the deformable diaphragm 441 bends toward the lower expansion side, causing displacement, which in turn propels the valve stem 42 in linear motion. This displacement of the valve stem 42 drives the valve core 43 away from the conduction hole 41e, allowing high-pressure nitrogen to be discharged through the conduction hole 41e to the outlet hole 41d, triggering pressure relief and the subsequent recovery process.

[0059] In this embodiment, the temperature sensing parts 442a are arranged in an axial dot matrix to cover the entire area of ​​the outer surface of the inner tank 30, eliminating monitoring blind spots; any single point failure can be covered by the adjacent temperature sensing parts 442a, improving reliability; the thermal conductive strips 442b synchronously transmit the local temperature rise signal to better control the trigger delay.

[0060] See also Figures 2 to 4 The present application further proposes that the surface of the temperature sensing element 442 is coated with a nano-aluminum oxide coating to reflect residual radiant heat.

[0061] In this embodiment, the nano-alumina coating refers to a covering layer composed of nano-scale aluminum oxide particles. Specifically, a dense layer can be formed on the surface of the temperature sensing element 442 using a sol-gel method or chemical vapor deposition method. This coating reduces the radiant heat absorbed by the temperature sensing element 442 through its high reflectivity. Residual radiant heat refers to heat that is not completely blocked by the thermal insulation structure 20 and is transferred to the vicinity of the temperature sensing element 442. This heat may originate from heat conduction from the external environment or from the phase change of liquid nitrogen. This heat can cause temperature errors in the temperature sensing element 442.

[0062] Specifically, when the insulation structure 20 fails locally or an external heat source invades, the residual radiant heat acts on the temperature sensing element 442 through heat conduction or radiation. The nano-aluminum oxide coating reflects part of the radiant heat back to the interior of the insulation structure 20 through its high reflective properties, reducing the amount of heat transferred to the temperature sensing element 442. The surface of the temperature sensing element 442 is completely covered by the coating, for example, by a full-wrap coating process, to ensure that the heat reflection effect is evenly distributed in the contact area between the temperature sensing element 442 and the inner tank 30 and the insulation structure 20. As a result, the temperature sensing element 442 only deforms based on the actual ambient temperature change, avoiding malfunction of the valve core 43 due to residual thermal interference.

[0063] Compared to existing technologies, the temperature sensing element 442 of traditional liquid nitrogen storage tanks is directly exposed to the gaps in the insulation structure 20, making it susceptible to localized heat radiation and causing temperature misjudgment, leading to premature or delayed opening of the release valve 40. This solution uses a nano-alumina coating to form a passive heat shield, suppressing thermal interference without requiring additional energy, thereby improving temperature sensing accuracy.

[0064] See also Figures 1 to 4 The present application further proposes that the liquid nitrogen storage tank also includes a condensation recovery container 50 and a liquid nitrogen delivery pump 60. The condensation recovery container 50 is connected to the air outlet 41d of the valve body 41, and is used to recover high-pressure nitrogen and liquefy the high-pressure nitrogen into liquid nitrogen; the liquid nitrogen delivery pump 60 is connected to the condensation recovery container 50 and the inner tank 30, and is used to start when the pressure of the inner tank 30 is lower than the set threshold, and deliver the condensed liquid nitrogen to the inner tank 30.

[0065] In this embodiment, the condensate recovery container 50 refers to a sealed container for collecting and liquefying high-pressure nitrogen. Specifically, this can be achieved by using a cryogenic container with a cooling coil and a compressor. The gaseous nitrogen is converted into liquid by lowering the temperature and increasing the pressure. The liquid nitrogen delivery pump 60 refers to a mechanical device for delivering liquid nitrogen. Specifically, it can be implemented by using an electromagnetically driven cryogenic pump. The start and stop states are controlled by detecting changes in the internal pressure of the inner liner 30. The set threshold refers to a pre-set critical pressure value. Specifically, it can be implemented by using a pressure sensor and a controller to activate the liquid nitrogen delivery pump 60 when the pressure falls below this value.

[0066] Specifically, when the release valve 40 opens due to the temperature rise of the insulation structure 20, high-pressure nitrogen enters the condensate recovery container 50 through the outlet 41d, where it is re-liquefied in the low-temperature environment. The liquefied liquid nitrogen is stored in the condensate recovery container 50. When the pressure of the inner liner 30 drops to a set threshold due to evaporation of the liquid nitrogen, the liquid nitrogen delivery pump 60 automatically activates and pumps the liquid nitrogen from the condensate recovery container 50 back into the inner liner 30, forming a closed-loop circulation system. This process maintains a dynamic pressure balance within the inner liner 30 through the linkage of pressure monitoring and pumping control.

[0067] Compared with existing technologies, traditional liquid nitrogen storage tanks directly release nitrogen when depressurized, resulting in resource waste and no way to compensate for liquid nitrogen loss, requiring manual replenishment after a sudden pressure drop. This solution incorporates a condensate recovery and automatic replenishment system to convert the released gas into reusable liquid nitrogen and automatically replenish it when pressure is insufficient, avoiding the safety hazards caused by delayed manual intervention.

[0068] See also Figures 2 to 4 The present application further proposes that in the thermal insulation structure 20 of the liquid nitrogen storage tank, the foam aluminum is a closed-cell foam aluminum, or the pores of the foam aluminum are filled with fumed silica powder.

[0069] Closed-cell aluminum foam refers to a foam material with independent and closed internal pores. It can be produced using powder metallurgy or melt foaming methods. Its closed-cell structure can reduce convective heat transfer caused by gas flow. Fumed silica powder refers to nano-sized silica particles produced through a vapor deposition process. It can be produced by the high-temperature hydrolysis of silicon tetrachloride. Its low thermal conductivity can fill the pores of the aluminum foam to block radiative heat transfer.

[0070] Specifically, when closed-cell aluminum foam serves as the spacer layer 22, its closed pore structure prevents heat convection generated by gas flow, while also supporting the reflective layer 21 through the aluminum matrix framework. When the aluminum foam pores are filled with fumed silica powder, the powder particles form a dense accumulation within the pores, reducing the efficiency of thermal radiation transfer by scattering and absorbing infrared radiation. Both implementations enhance the heat insulation capability of the insulation structure 20, thereby reducing pressure fluctuations caused by liquid nitrogen evaporation.

[0071] See also Figure 2 、 Figure 5 and Figure 6 The present application further proposes to provide a flexible base film 21 a on the surface of each reflective layer 21 , and the flexible base film 21 a is used to increase the flexibility of the reflective layer 21 .

[0072] In this embodiment, the flexible base film 21a refers to a polymer film layer attached to the surface of the reflective layer 21, which can be specifically implemented by a polyimide film or a polyester film. The flexible base film 21a provides elastic support for the reflective layer 21 through the ductility of the material itself, so that the reflective layer 21 disperses local stress through the bending of the base film during deformation.

[0073] Specifically, the reflective layer 21, due to its excessive rigidity, may cause stress concentration when the container deforms or experiences temperature fluctuations. However, the flexible base film 21a forms a buffer interface through its own elastic deformation, absorbing mechanical stress caused by radial deformation or thermal expansion and contraction. The flexible base film 21a, when combined with the reflective layer 21, not only maintains the reflective layer 21's infrared radiation reflectivity, but also reduces direct contact friction between the rigid materials through microscopic interface deformation, preventing brittle fracture of the reflective layer 21 due to stress concentration. This composite structure ensures that the insulation structure 20 maintains the integrity of the interlayer structure even under dynamic operating conditions.

[0074] See also Figures 1 to 4 The present application further proposes to provide an aluminum-plated layer 21b on the surface of the flexible base film 21a, and the aluminum-plated layer 21b is used to reflect infrared radiation light.

[0075] In this embodiment, the aluminum-plated layer 21b refers to a metal reflective layer 21 formed on the surface of the flexible base film 21a by vacuum evaporation or magnetron sputtering. Its function is to enhance the reflection ability of infrared radiation through the high reflectivity of the metal, thereby reducing the evaporation loss of liquid nitrogen caused by thermal radiation penetration.

[0076] Specifically, the flexible base film 21a is first fixed in the reflective layer 21 structure as a base layer, and its own ductility meets the deformation requirements of the container structure during dynamic changes. The aluminum-plated layer 21b is attached to the surface of the base film in the form of a thin film, and uses the high reflectivity characteristics of aluminum to efficiently reflect the incident infrared radiation, forming a double barrier mechanism for thermal radiation transfer. During the liquid nitrogen storage process, when external heat is transferred inward through the container, the aluminum-plated layer 21b directly reflects most of the infrared radiation energy, while the residual heat that is not reflected is dissipated by multiple scattering at the interface between the flexible base film 21a and the aluminum-plated layer 21b. This layered structure not only maintains the overall flexibility of the reflective layer 21, but also improves the thermal radiation reflection efficiency through surface metallization treatment, thereby maintaining a stable thermal insulation effect when the container is slightly deformed.

[0077] Through the above-mentioned technical solution, the present application can effectively reduce evaporation losses caused by thermal radiation penetration during liquid nitrogen storage, while ensuring that the reflective layer 21 maintains its structural integrity when the container deforms. The composite structure of the flexible base film 21a and the aluminum-plated layer 21b prevents the thermal insulation structure 20 from breaking when subjected to the stress generated by the thermal expansion and contraction of the container, maintaining a stable infrared reflective interface, thereby extending the liquid nitrogen storage period and reducing the risk of pressure fluctuations.

[0078] See also Figure 2 、 Figure 5 and Figure 6 The present application further proposes that a glass fiber mesh cloth 22a is embedded in the spacer layer 22 to enhance its structural rigidity.

[0079] In this embodiment, a glass fiber mesh is embedded within the spacer layer 22 to form a three-dimensional reinforced skeleton. This structure, through the uniform distribution of the fiber mesh, provides shear resistance, preventing creep deformation of the insulation structure 20 during pressure fluctuations. The glass fiber mesh 22a is a mesh fabric woven from inorganic glass fibers, with mesh apertures adjustable according to the thickness of the spacer layer 22. This material provides rigid support through its high modulus properties, while the inorganic material maintains dimensional stability in low-temperature environments, preventing internal stress caused by thermal expansion and contraction.

[0080] Specifically, a pre-impregnated glass fiber mesh 22a is embedded in the spacer layer 22 during its fabrication, forming a reinforcement network that extends throughout the thickness of the material. Under temperature fluctuations or external loads, the mesh disperses stress through the node connections between the fibers, suppressing compressive deformation of the spacer layer 22. Because glass fiber has a lower thermal conductivity than metal, the mesh prevents thermal bridges from forming between adjacent reflective layers 21, maintaining the low thermal conductivity of the insulation structure 20.

[0081] The present application effectively suppresses the deformation failure problem of the container caused by temperature fluctuations or pressure changes, ensures the structural rigidity of the spacer layer 22 under long-term low-temperature conditions, thereby maintaining the stable stacking structure of the insulation structure 20, the reflective layer 21 and the spacer layer 22, and improving the thermal insulation performance and container reliability during liquid nitrogen storage.

[0082] See also Figure 2 、 Figure 5 and Figure 6 The present application further proposes that the interlayer density of the multiple reflective layers 21 decreases gradually from the outside to the inside along the radial direction of the container.

[0083] In this embodiment, interlayer density refers to the distribution of reflective layer 21 material per unit volume, which can be achieved by adjusting the foil thickness or the spacing between the corrugated structures. A gradient decrease refers to a distribution pattern in which the density of the reflective layer 21 decreases radially from the outer surface to the inner cavity of the container. This can be achieved by gradually reducing the compression ratio of the corrugated structure or selecting metal foils with varying porosities. This design allows the outer layer to preferentially reflect the majority of incident thermal radiation, while the lower density of the inner layer maintains basic reflective performance and reduces thermal stress concentration.

[0084] Specifically, the high-density reflective layer 21 on the outer surface of the insulation structure 20 forms a dense heat-reflecting interface, reflecting infrared radiation from the external environment and reducing heat penetration. The density of the intermediate layer gradually decreases, gradually releasing deformation stress caused by temperature changes while maintaining heat reflection capabilities. The innermost low-density reflective layer 21 reduces the overall mass of the insulation structure 20 and prevents interlayer delamination caused by material thermal expansion differences. By matching the thermal resistance layer by layer, the non-uniform heat conduction caused by the temperature difference between the inside and outside of the container is reduced, suppressing the evaporation rate of liquid nitrogen and alleviating pressure fluctuations.

[0085] This solution optimizes thermal resistance distribution through gradient density distribution, so that the outer layer takes priority in heat reflection function, and the inner layer focuses on maintaining structural stability, effectively balancing heat reflection efficiency and mechanical strength requirements, and reducing the interference of temperature changes on storage status.

[0086] See also Figure 2 、 Figure 5 and Figure 6 The present application further proposes to cover the outer side of the insulation structure 20 with a vacuum layer 23; the vacuum layer 23 includes a porous core material 231 and a barrier film 232, the barrier film 232 is covered on the outer surface of the porous core material 231 and is vacuum sealed; the porous core material 231 is selected from gas-phase silica or glass fiber felt.

[0087] In this embodiment, the vacuum layer 23 refers to a closed space structure formed by vacuuming, which is filled with a porous core material 231 and wrapped by a barrier film 232, which is used to eliminate the heat conduction path of gas molecules and inhibit the transfer of external heat through gas convection. The porous core material 231 refers to a material with a nanoscale pore structure, such as fumed silica or glass fiber felt, which adsorbs residual gas molecules through a high specific surface area, reduces the solid heat conduction rate, and maintains the stability of the vacuum environment. The barrier film 232 refers to a composite film material with high airtightness, which is used to wrap the porous core material 231 and form a vacuum sealed cavity to prevent external gas from infiltrating and causing a decrease in vacuum.

[0088] Specifically, the vacuum layer 23 is arranged on the outside of the insulation structure 20, and a closed cavity is formed by vacuuming the barrier film 232 to block the external environment heat from entering the interior of the container through gas convection and conduction. The nanoporous structure of the porous core material 231 can reduce the solid contact heat transfer area and reduce the thermal conductivity efficiency of the material itself. The adsorption properties of gas-phase silica or glass fiber felt can capture the gas molecules remaining in the vacuum cavity and avoid the heat conduction caused by the movement of gas molecules. The vacuum layer 23 forms a composite insulation barrier with the reflective layer 21 and the spacer layer 22 alternately arranged on the inner side. The reflective layer 21 reflects infrared radiation heat through the metal surface, the spacer layer 22 blocks the solid heat conduction path, and the vacuum layer 23 eliminates gas heat conduction. The three work together to form a multi-dimensional thermal barrier mechanism.

[0089] This solution achieves multi-dimensional thermal isolation by superimposing the vacuum layer 23 and the reflective-spacer composite structure. On the basis of blocking gas heat conduction, it simultaneously suppresses radiation heat conduction and solid heat conduction, thereby significantly reducing the thermal interference of external temperature changes on the liquid nitrogen in the container.

[0090] See also Figure 2 、 Figure 5 and Figure 6The present application further proposes that a moisture-proof layer 24 and a protective layer 25 are stacked in sequence on the outside of the vacuum layer 23. The moisture-proof layer 24 is used to block water vapor penetration, and the protective layer 25 is used to resist mechanical impact and environmental corrosion; the moisture-proof layer 24 is an aluminum-plastic composite film or a metallized polyester film; the protective layer 25 is a galvanized steel plate or a glass fiber reinforced polyurethane layer.

[0091] In this embodiment, the moisture-proof layer 24 is an airtight barrier structure composed of multiple layers of composite material, specifically an aluminum-plastic composite film or metallized polyester film. Its metal coating or aluminum foil layer, through its dense structure, blocks the permeation path of water molecules, preventing external moisture from invading the interior of the vacuum layer 23 and increasing heat conduction efficiency. The protective layer 25 is an outer covering structure that provides mechanical strength and weather resistance, specifically a galvanized steel sheet or a glass fiber-reinforced polyurethane layer. The former resists erosion by corrosive media through the oxide film formed by the metal coating, while the latter disperses external impact loads through a fiber-reinforced matrix. Both maintain the integrity of the tank shell 10.

[0092] Specifically, the aluminum-plastic composite film, through the composite stacking of polyethylene layers and aluminum foil, forms multiple water vapor barriers while maintaining flexibility. Metallized polyester film, through a vacuum aluminum plating process, forms a nano-scale metal layer on the surface of the polyester substrate. Both effectively reduce water vapor transmission rate. The zinc layer on the galvanized steel sheet forms sacrificial anode protection on the steel substrate, slowing the progression of oxidative corrosion. The glass fiber reinforced polyurethane layer, through the composite curing of the glass fiber mesh and polyurethane resin, forms a rigid shell with a high flexural modulus. Together, these two layers can withstand the impact and extrusion stresses experienced during tank transportation or installation. The stacking of the moisture-proof layer 24 and the protective layer 25 creates a phased protection mechanism: the moisture-proof layer 24, adjacent to the vacuum layer 23, prioritizes water vapor penetration, while the protective layer 25, as the outermost layer, directly addresses external mechanical damage and chemical corrosion. This structural hierarchy effectively extends the service life of the vacuum insulation system.

[0093] This solution achieves all-round protection for the liquid nitrogen storage environment by optimizing the material combination and spatial arrangement of the moisture-proof layer 24 and the protective layer 25. Especially in humid or highly corrosive working conditions, the multi-layer protection system significantly reduces the risk of performance degradation of the vacuum layer 23.

[0094] See also Figure 2 、 Figure 5 and Figure 6 The present application further proposes that the thickness of the plurality of spacer layers 22 gradually increases from the outside to the inside along the radial direction of the container.

[0095] In this embodiment, the gradient increase means that the thickness of the spacer layer 22 gradually increases from the outside of the container to the inner cavity. Specifically, this can be achieved by increasing the size of the polyimide honeycomb unit layer by layer or changing the foaming density of the foam layer. The differentiated thermal resistance configuration of different areas can be achieved by adjusting the thickness distribution.

[0096] Specifically, during liquid nitrogen storage, when external heat is transferred from the container to the interior, the outer areas experience a greater heat load due to ambient temperature fluctuations. The increasing thickness of the spacer layer 22 from the outside to the inside reduces the spacing between the outer reflective layers 21, increases the density of reflective interfaces per unit volume, and enhances the ability to reflect external thermal radiation. The increased thickness of the inner spacer layer 22 creates a longer solid-state heat conduction path, reducing the heat flow transfer rate. This gradient structure aligns the thermal insulation performance of different areas of the insulation structure 20 with the heat load distribution. The high-density reflective layer 21 on the outside rapidly attenuates radiant heat, while the low-thermal conductivity path on the inside inhibits heat penetration into the liquid nitrogen storage area, thereby overall reducing the amount of liquid nitrogen evaporation and pressure fluctuations caused by temperature changes.

[0097] This solution achieves dynamic adaptation of thermal resistance distribution through gradient thickness design, solves the problem of unbalanced heat conduction between the inside and outside under a uniform structure, and avoids structural redundancy and cost increase caused by simply increasing the number of reflective layers 21.

[0098] See also Figure 1 、 Figure 2 、 Figure 5 and Figure 6 This application further proposes a processing system comprising a processing control host, main processing equipment, alarm auxiliary equipment, and a liquid nitrogen storage tank. The liquid nitrogen storage tank has an electrically controlled valve, and the release valve 40 has an air intake line connected to the air intake hole 41c. The electrically controlled valve is disposed in the air intake line and is electrically connected to the processing control host. In the non-releasing state, the valve is used to open and close the air intake line in response to a signal from the processing control host.

[0099] In this embodiment, the electrically controlled valve refers to an automatically controlled valve installed in the air intake line. Specifically, it can be implemented as a solenoid valve or an electric ball valve. It controls the opening and closing of the line by receiving an electrical signal. The air intake line refers to the pipe structure connected to the air inlet 41c of the release valve 40. Specifically, it can be made of metal or a low-temperature-resistant polymer material, and is used to guide external air into the valve body 41. The processing control host refers to the central processing unit of the integrated control module. Specifically, it can be implemented as an industrial computer or a programmable logic controller. It coordinates the coordinated operation of the main processing equipment, alarm auxiliary equipment, and the electrically controlled valve.

[0100] Specifically, when not in the release state, the processing control host sends a closing signal to the electronically controlled valve, blocking the air intake line and preventing external gas from entering the liquid nitrogen storage tank and causing pressure fluctuations. If the processing system detects an abnormal operating condition, the processing control host sends a signal to the alarm auxiliary equipment to trigger an alarm. Simultaneously, a pre-set program determines whether to open the electronically controlled valve for pressure relief. Through the coordinated control of the electronically controlled valve and the host, the opening and closing states of the air intake line can be precisely matched to system operating requirements.

[0101] Compared with existing technologies, the air intake lines of traditional liquid nitrogen storage tanks are typically controlled by manual valves or independent pressure switches, which are subject to response lag and manual operation. This solution, through a direct electrical connection between the electronically controlled valve and the processing control host, achieves automated control of the air intake line opening and closing. This solution can dynamically adjust based on the system's real-time operating conditions, eliminating the risk of pressure loss due to manual operation delays.

[0102] Through the above technical solution, the present application effectively solves the problem of drastic pressure changes caused by external gas intrusion during liquid nitrogen storage. By automatically blocking the air inlet pipeline, the evaporation loss of liquid nitrogen is reduced, and the explosion hazard caused by abnormal increase in internal pressure of the storage tank is reduced, while improving the overall operational stability of the processing system.

[0103] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformation made by utilizing the contents of the present invention's description and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A liquid nitrogen storage tank, characterized in that: The liquid nitrogen storage tank includes an outer shell, an inner liner, and an insulation structure. The inner liner is disposed within the outer shell and is used to store liquid nitrogen. The insulation structure is disposed between the inner liner and the outer shell and includes a plurality of stacked reflective layers and a plurality of spacer layers. The plurality of reflective layers and the plurality of spacer layers are alternately arranged. The reflective layers are used to reflect infrared radiation. The spacer layers are foamed aluminum layers and are used to provide physical support and heat insulation for two adjacent reflective layers. The liquid nitrogen storage tank further includes a release valve, which includes: a valve body, the valve body being disposed at the top of the housing, the valve body comprising a valve cavity, a through-hole communicating with the valve cavity, an air inlet, an air outlet, and a conducting hole, the air inlet being located at the bottom of the valve body, the air outlet being located at the side of the valve body, the through-hole being located at the top center of the valve body, and the conducting hole being located between the air inlet and the air outlet; a valve stem movably connected to the valve cavity; a valve core connected to one end of the valve stem and movably connected between the guide hole and the air inlet hole; and a thermal expansion element, the thermal expansion element being connected to an end of the valve stem away from the valve core, the end of the thermal expansion element away from the valve stem extending between the inner liner and the thermal insulation structure and in contact with the inner liner and the thermal insulation structure, and being configured to sense the temperature of the thermal insulation structure to drive the valve stem to push the valve core toward or away from the guide hole; The thermal expansion element includes a deformable diaphragm and a temperature-sensing member connected to the deformable diaphragm. The temperature-sensing member extends from the through-hole to between the inner liner and the thermal insulation structure and contacts the inner liner and the thermal insulation structure. A lever amplification mechanism is provided on a side of the deformable diaphragm away from the temperature-sensing member and is connected to the valve stem via the lever amplification mechanism. The lever amplification mechanism includes a fulcrum, a lever arm, and a connecting rod, and is used to amplify a small displacement of the deformable diaphragm and transmit it to the valve stem. The temperature sensing element includes a plurality of temperature sensing portions and a heat conducting strip connected to the plurality of temperature sensing portions, the heat conducting strip being connected to the deformable diaphragm and extending from the through hole, the plurality of temperature sensing portions being axially spaced apart along the outer surface of the liner and all being connected to the heat conducting strip, and two adjacent temperature sensing portions being connected; A flexible base film is provided on the surface of each reflective layer, and the flexible base film is used to increase the flexibility of the reflective layer; And / or, an aluminum coating is provided on the surface of the flexible base film, and the aluminum coating is used to reflect infrared radiation; And / or, the spacer layer is embedded with glass fiber mesh cloth to enhance its structural rigidity; The outer side of the thermal insulation structure is covered with a vacuum layer, and the vacuum layer includes: porous core material; and A barrier film is coated on the outer surface of the porous core material and is vacuum-sealed to block gas heat conduction; and the porous core material is fumed silica or glass fiber felt.

2. The liquid nitrogen storage tank according to claim 1, characterized in that The surface of the temperature sensing element is coated with a nano-aluminum oxide coating for reflecting residual radiant heat.

3. The liquid nitrogen storage tank according to claim 1, characterized in that The liquid nitrogen storage tank also includes a condensation recovery container and a liquid nitrogen delivery pump. The condensation recovery container is connected to the air outlet of the valve body and is used to recover high-pressure nitrogen and liquefy the high-pressure nitrogen into liquid nitrogen. The liquid nitrogen delivery pump is connected to the condensation recovery container and the inner tank and is used to start when the pressure of the inner tank is lower than a set threshold and deliver the condensed liquid nitrogen to the inner tank.

4. The liquid nitrogen storage tank according to claim 1, characterized in that The aluminum foam is a closed-cell aluminum foam; or, the pores of the aluminum foam are filled with fumed silica powder.

5. A processing system, characterized in that: The processing system comprises: Processing control host; A processing main device, which is electrically connected to the processing control host and is used to perform processing operations on the product; an alarm auxiliary device, the alarm auxiliary device being electrically connected to the processing control host and being used to remind personnel to carry out accident prevention work upon receiving an alarm signal sent by the processing control host; and The liquid nitrogen storage tank according to any one of claims 1 to 4, wherein the liquid nitrogen storage tank has an electrically controlled valve, the release valve of the liquid nitrogen storage tank has an air intake pipe connected to the air intake hole, the electrically controlled valve is provided in the air intake pipe, and is electrically connected to the processing control host, and is used to open and close the air intake pipe when receiving a signal from the processing control host in a non-discharge state.

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