Liquid nitrogen storage tank and processing system

Abstract

The invention discloses a liquid nitrogen storage tank and a processing system, and relates to the technical field of heat insulation structure.The liquid nitrogen storage tank comprises a shell, an inner container and a heat insulation structure, and the inner container is arranged in the shell and used for storing liquid nitrogen; the heat insulation structure is arranged between the inner container and the shell, the heat insulation structure comprises a plurality of reflecting layers and a plurality of spacing layers which are arranged in a stacked mode, the reflecting layers and the spacing layers are alternately arranged, the reflecting layers are used for reflecting infrared radiation light rays, the spacing layers are foamed aluminum layers, and the reflecting layers are used for reflecting infrared radiation light rays. And the heat insulation layer is used for forming physical support and heat insulation for the two adjacent reflecting layers. According to the technical scheme, the stability of the liquid nitrogen in the storage process is improved, explosion of the liquid nitrogen storage tank is avoided, and therefore the processing system is more stable when the liquid nitrogen storage tank is applied.

Description

Technical Field

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

[0002] In the existing related research and practice of applying liquid nitrogen technology, there is a relatively prominent problem, that is, the storage stability of liquid nitrogen is poor. During the storage process of liquid nitrogen, it is extremely vulnerable to the influence of external temperature changes, resulting in an unstable storage state. This temperature sensitivity leads to an increase in the evaporation loss of liquid nitrogen and a drastic change in the internal pressure of the storage container, making the storage container prone to explosion and affecting the normal application of liquid nitrogen in the processing system. Summary of the Invention

[0003] The main object of the present invention is to propose a liquid nitrogen storage tank and a processing system, aiming to improve the stability of liquid nitrogen during storage, avoid the explosion of the liquid nitrogen storage tank, and thus make the processing system more stable when applying the liquid nitrogen storage tank.

[0004] To achieve the above object, a liquid nitrogen storage tank proposed by the present invention includes a housing, an inner tank, and an adiabatic structure. The inner tank is disposed inside the housing and is used for storing liquid nitrogen. The adiabatic structure is disposed between the inner tank and the housing. The adiabatic structure includes a plurality of reflective layers and a plurality of spacer layers arranged in a stacked manner. The plurality of reflective layers and the plurality of spacer layers are alternately arranged. The reflective layer is used for reflecting infrared radiation light, and the spacer layer is an aluminum foam layer, which is used for physically supporting and insulating heat between two adjacent reflective layers.

[0005] In one embodiment, the liquid nitrogen storage tank further includes a release valve, and the release valve includes: A valve body, which is disposed on the top of the housing. The valve body has a valve cavity, a through hole communicating with the valve cavity, an air inlet hole, an air outlet hole, and a guiding through hole. The air inlet hole is located at the bottom of the valve body, the air outlet hole is located at the side of the valve body, the through hole is located at the center of the top of the valve body, and the guiding through hole is located between the air inlet hole and the air outlet hole. A valve stem, which is movably connected in the valve cavity. A valve core, which is connected to one end of the valve stem and is movably connected between the guiding through hole and the air inlet hole. And A thermal expansion element, which is connected to the end of the valve stem away from the valve core. The end of the thermal expansion element away from the valve stem extends between the inner tank and the adiabatic structure and contacts the inner tank and the adiabatic structure, and is used for sensing the temperature of the adiabatic structure to drive the valve stem to push the valve core closer to or farther away from the guiding through hole.

[0006] In one embodiment, 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 perforation to between the inner container and the heat insulation structure and contacts the inner container and the heat 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 through the lever amplification mechanism.

[0007] In one embodiment, the temperature sensing member includes a plurality of temperature sensing portions and a heat conducting strip connected to the plurality of temperature sensing portions. The heat conducting strip is connected to the deformable diaphragm and extends from the perforation. The plurality of temperature sensing members are axially spaced apart along the outer surface of the inner container and are all connected to the heat conducting strip, and two adjacent temperature sensing portions are connected.

[0008] In one embodiment, the surface of the temperature sensing member is coated with a nano-aluminum oxide coating for reflecting residual radiant heat.

[0009] 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 communicated with the air outlet of the valve body for recovering high-pressure nitrogen and liquefying the high-pressure nitrogen into liquid nitrogen; the liquid nitrogen delivery pump is communicated with the condensation recovery container and the inner container and is configured to start when the pressure in the inner container is lower than a set threshold value and deliver the condensed liquid nitrogen into the inner container.

[0010] In one embodiment, the aluminum foam is closed-cell aluminum foam; or, the pores of the aluminum foam are filled with fumed silica powder.

[0011] In one embodiment, a layer of flexible base film is provided on the surface of each reflection layer for increasing the flexibility of the reflection layer; And / or, an aluminized layer is provided on the surface of the flexible base film for reflecting infrared radiation light; And / or, a fiberglass mesh cloth is embedded in the spacer layer for enhancing its structural rigidity.

[0012] In one embodiment, the outside of the heat insulation structure is coated with a vacuum layer, and the vacuum layer includes: A porous core material; and A barrier film which is coated on the outer surface of the porous core material and evacuated and sealed for blocking gas heat conduction; and the porous core material is fumed silica or fiberglass felt.

[0013] The present invention also provides a processing system, and the processing system includes: A processing control host; A processing main body device which is electrically connected to the processing control host and is configured to perform processing operations on products; An alarm auxiliary device, which is electrically connected to the processing control host and is used to remind personnel to carry out accident prevention work when receiving an alarm signal sent by the processing control host; and The liquid nitrogen storage tank as described above, the liquid nitrogen storage tank has an electric control valve, the release valve of the liquid nitrogen storage tank has an air inlet pipe communicating with the air inlet hole, the electric control valve is arranged on the air inlet pipe and is electrically connected to the processing control host, and is used to open and close the air inlet pipe when receiving a signal from the processing control host in a non-discharge state.

[0014] The liquid nitrogen storage tank of the technical solution of the present invention includes a shell, an inner tank and a heat insulation structure. The inner tank is arranged inside the shell and is used to store liquid nitrogen; the heat insulation structure is arranged between the inner tank and the shell, and the heat insulation structure includes a plurality of reflective layers and a plurality of spacer layers arranged in a stacked manner. The plurality of reflective layers and the plurality of spacer layers are arranged alternately. The reflective layer is used to reflect infrared radiation light, and the spacer layer is a foam aluminum layer, which is used to form physical support and heat insulation for two adjacent reflective layers. By actively blocking radiant heat through the reflective layer and combining with the foam aluminum layer to inhibit conductive heat, a synergistic heat insulation effect is formed. The synergistic effect of the reflective layer and the foam aluminum layer improves the heat insulation performance, effectively reduces the amount of heat intrusion during the storage of liquid nitrogen, slows down the evaporation rate of liquid nitrogen, improves the stability of liquid nitrogen during storage, and avoids the explosion of the liquid nitrogen storage tank, thereby making the processing system more stable when applying the liquid nitrogen storage tank. Description of the Drawings

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0016] Figure 1 It is the front view of the liquid nitrogen storage tank provided by the present invention; Figure 2 It is the longitudinal sectional view of one side inner wall of the liquid nitrogen storage tank provided by the present invention; Figure 3 It is the structural schematic diagram of the release valve of the liquid nitrogen storage tank provided by the present invention; Figure 4 It is the structural schematic diagram of the liquid nitrogen storage tank provided by the present invention with a temperature sensing part arranged; Figure 5 It is the longitudinal sectional view of the reflective layer of the liquid nitrogen storage tank provided by the present invention; Figure 6 It is the structural schematic diagram of the spacer layer of the liquid nitrogen storage tank provided by the present invention.

[0017] Description of the attached reference numerals: 10. Outer shell; 20. Thermal insulation structure; 21. Reflective layer; 21a. Flexible base film; 21b. Aluminum-plated layer; 22. Spacer layer; 22a. Fiberglass mesh cloth; 23. Vacuum layer; 231. Porous core material; 232. Barrier film; 24. Moisture-proof layer; 25. Protective layer; 30. Inner container; 40. Release valve; 41. Valve body; 41a. Valve cavity; 41b. Perforation; 41c. Intake hole; 41d. Outlet hole; 41e. Through hole; 42. Valve stem; 43. Valve core; 44. Thermal expansion element; 441. Deformation diaphragm; 442. Temperature-sensing part; 442a. Temperature-sensing portion; 442b. Heat-conducting strip; 50. Condensation recovery container; 60. Liquid nitrogen transfer pump.

[0018] The realization, functional features, and advantages of the object of the present invention will be further described in conjunction with the embodiments and with reference to the accompanying drawings. Specific embodiments

[0019] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0020] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention, then the directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0021] In addition, if there are descriptions such as "first", "second", etc. in the embodiments of the present invention, then the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, if "and / or" or "and / or" appears throughout the text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or a solution where A and B are satisfied simultaneously. In addition, the technical solutions between the embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0022] In the prior art, liquid nitrogen storage containers generally face the problem of insufficient insulation performance. Traditional storage tanks mostly use a single insulating material to fill the interlayer between the inner tank and the outer shell. However, the temperature fluctuations in the external environment are easily introduced into the container interior through heat conduction and radiation, resulting in an accelerated evaporation rate of liquid nitrogen. As the evaporation amount increases, the internal pressure of the container rises sharply, posing an explosion risk. For example, in an industrial processing scenario, when the ambient temperature around the storage tank rises, the pressure fluctuations generated by the rapid gasification of liquid nitrogen may damage the structural integrity of the container.

[0023] Therefore, referring to Figure 1 and Figure 2 , this application proposes that the liquid nitrogen storage tank includes an outer shell 10, an inner tank 30, and an insulation structure 20. The inner tank 30 is arranged inside the outer shell 10 for storing liquid nitrogen. The insulation structure 20 is located between the inner tank 30 and the outer shell 10 and is composed of alternately stacked reflective layers 21 and spacer layers 22. The reflective layer 21 is used to reflect infrared radiation light, and the spacer layer 22 is made of aluminum foam material, which not only provides physical support for the adjacent reflective layers 21 but also isolates heat transfer through its closed-cell structure.

[0024] 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 implemented using stainless steel or aluminum alloy materials to resist external mechanical impacts. The inner tank 30 refers to a sealed container directly in contact with liquid nitrogen, which can be specifically implemented using a double-layer austenitic stainless steel welded structure to prevent low-temperature brittle fracture. The insulation structure 20 refers to a composite heat insulation layer arranged between the inner tank 30 and the outer shell 10, which can be specifically realized by alternately laying metal foil reflective layers 21 and aluminum foam layers to form multiple thermal barrier layers. The reflective layer 21 refers to a thin-layer material with a high reflectivity, which can be specifically implemented using aluminized polyester film, and the aluminum layer on its surface can reflect infrared radiation. The spacer layer 22 refers to a heat insulation material layer with a supporting function.

[0025] Specifically, the reflective layer 21 and the aluminum foam layer are alternately stacked to form a composite insulation barrier. When external heat is transferred by radiation, the aluminized reflective layer 21 reflects most of the infrared rays back to the external environment. When the remaining heat enters the aluminum foam layer by conduction, the closed pores inside it form a low-thermal-conductivity path, significantly slowing down the heat transfer towards the inner tank 30. The aluminum foam layer also provides rigid support for the adjacent reflective layers 21, preventing the interlayer collapse from causing a decline in insulation performance. This structure forms a continuous thermal barrier layer axially and maintains a low-temperature environment for the inner tank 30 through a dual-barrier mechanism of reflection and conduction radially.

[0026] Compared with the prior art, traditional storage tanks mostly use glass wool or polyurethane foam as a single insulating layer, which can only delay heat transfer through the low thermal conductivity of the material itself. In this solution, the reflective layer 21 actively blocks radiant heat, combined with the aluminum foam layer to inhibit conductive heat, forming a synergistic heat insulation effect. The rigid support characteristic of the aluminum foam overcomes the problem that traditional multi-layer insulating materials are prone to compression deformation, ensuring the long-term stability of the insulating structure 20.

[0027] Through the above technical solution, the present application effectively reduces the amount of heat intrusion during the storage of liquid nitrogen, slows down the evaporation rate of liquid nitrogen, thereby maintaining the stability of the internal pressure of the storage tank. The synergistic effect of the reflective layer 21 and the aluminum foam layer improves the heat insulation performance. This structure also enhances the mechanical impact resistance of the storage tank, avoiding the local heat bridge effect caused by the collapse of the insulating layer.

[0028] Please refer to Figures 1 to 3 , the present application further proposes a liquid nitrogen storage tank, which further 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 outer shell 10. The valve body 41 has a valve cavity 41a, a perforation 41b communicating with the valve cavity 41a, an air inlet hole 41c, an air outlet hole 41d and a guiding hole 41e. The air inlet hole 41c is located at the bottom of the valve body 41, the air outlet hole 41d is located at the side of the valve body 41, the perforation 41b is located at the center of the top of the valve body 41, and the guiding hole 41e is located between the air inlet hole 41c and the air outlet hole 41d. The valve stem 42 is movably connected in the valve cavity 41a. The valve core 43 is connected to one end of the valve stem 42 and is movably connected between the guiding hole 41e and the air inlet hole 41c. The thermal expansion element 44 is connected to the end of the valve stem 42 far from the valve core 43. The end of the thermal expansion element 44 far from the valve stem 42 extends between the inner liner 30 and the insulating structure 20 and contacts the inner liner 30 and the insulating structure 20, and is used to sense the temperature of the insulating structure 20 to drive the valve stem 42 to push the valve core 43 closer to or farther away from the guiding hole 41e.

[0029] Among them, the valve body 41 refers to a rigid structure for constructing a gas passage, which can be specifically realized by casting and processing stainless steel or aluminum alloy. The internal valve cavity 41a forms a gas flow space, and the air inlet hole 41c, the guiding hole 41e, and the air outlet hole 41d are precisely drilled by a numerically controlled machine tool to form a directional air flow path. The valve stem 42 refers to a transmission component for transmitting mechanical displacement, which can be specifically realized by a steel rod with a chrome-plated surface, and its axial movement is realized through a sliding bearing or a linear guide rail. The valve core 43 refers to a sealing component for controlling the on-off of gas, which can be specifically made of a conical sealing surface with a polytetrafluoroethylene-coated metal matrix, and forms a contact seal with the guiding hole 41e. The thermal expansion element 44 refers to a driving component that generates deformation based on temperature changes. When the temperature of the heat insulation structure 20 rises, the thermal expansion element 44 expands thermally and elongates, pushing the valve stem 42 to drive the valve core 43 away from the guiding hole 41e, so that the air inlet hole 41c is communicated with the air outlet hole 41d to release pressure.

[0030] Specifically, when the temperature between the inner tank 30 and the heat insulation structure 20 rises due to external heat intrusion, the thermal expansion element 44 directly contacts this area and expands thermally, generating an axial displacement. This displacement is transmitted to the valve core 43 through the valve stem 42, causing the valve core 43 to disengage from the guiding hole 41e, and the air inlet hole 41c and the air outlet hole 41d form a passage. At this time, the high-pressure nitrogen gas generated by the evaporation of liquid nitrogen inside the inner tank 30 enters the valve cavity 41a through the air inlet hole 41c and is discharged to the external recovery system through the air outlet hole 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 re-close the guiding hole 41e and blocking the gas discharge. This process realizes autonomous pressure regulation through mechanical linkage without relying on external power or sensors.

[0031] Compared with the prior art, 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, and the latter has the risk of circuit failures and response delays. This solution directly couples the thermal expansion element 44 with the mechanical transmission structure, enabling the pressure relief action to be synchronized with temperature changes in real time, avoiding the reliability problems of electronic components and improving the accuracy of pressure control.

[0032] 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 heat insulation structure 20 rises abnormally, effectively suppressing the risk of explosion of the storage tank caused by the sudden increase in pressure due to liquid nitrogen evaporation. At the same time, the pressure relief process realizes closed-loop control through physical contact temperature sensing, ensuring that the pressure release is strictly matched with the temperature state and reducing the loss of liquid nitrogen caused by unnecessary pressure relief.

[0033] Please refer to Figures 2 to 4, this application further proposes that the thermal expansion element 44 includes a deformable diaphragm 441 and a temperature sensing element 442 connected to the deformable diaphragm 441. The temperature sensing element 442 extends from the perforation 41b and reaches between the inner container 30 and the heat insulation structure 20, and contacts the inner container 30 and the heat insulation structure 20. On the side of the deformable diaphragm 441 away from the temperature sensing element 442, a lever amplification mechanism is provided and is connected to the valve stem 42 through the lever amplification mechanism.

[0034] In this embodiment, the deformable diaphragm 441 refers to a metal or alloy material that can deform with temperature changes, such as nickel-titanium alloy or 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 container 30 and the heat insulation structure 20, such as a copper pipe or an aluminum bellows, and is used to quickly transfer temperature changes to the deformable diaphragm 441. The lever amplification mechanism refers to a mechanical structure composed of a fulcrum, a force arm, and a connecting rod, such as a combination of a stainless steel hinge and a connecting rod, which can amplify the small displacement of the deformable diaphragm 441 and then transfer it to the valve stem 42.

[0035] Specifically, when the temperature of the heat insulation structure 20 rises due to heat penetration, the temperature sensing element 442 transfers the temperature change to the deformable diaphragm 441, causing it to undergo thermal expansion deformation. The deformation amount of the deformable diaphragm 441 is amplified by the lever amplification mechanism, and then drives the valve stem 42 to generate sufficient displacement, driving the valve core 43 to move to control the opening or closing of the guide through hole 41e. For example, when the temperature exceeds the set threshold, the lever amplification mechanism can amplify the small displacement of the deformable diaphragm 441, so as to ensure that the valve core 43 completely disengages from the guide through hole 41e to achieve pressure relief.

[0036] Compared with the prior art, the traditional thermal expansion element 44 usually adopts a single metal rod or spring structure, with limited deformation amount and slow response speed, and cannot accurately control the displacement of the valve core 43. However, in this solution, through the combination of the deformable diaphragm 441 and the lever amplification mechanism, small temperature changes can be converted into effective mechanical actions, and at the same time, the temperature sensing element 442 directly contacts the inner container 30 and the heat insulation structure 20, and can sense temperature anomalies in real time.

[0037] Through the above technical solution, this application can improve the temperature sensing sensitivity and mechanical response efficiency, quickly trigger the pressure relief action at the initial stage of the failure of the heat insulation structure 20, and avoid the explosion of the liquid nitrogen storage tank due to a sudden increase in internal pressure. At the same time, the lever amplification mechanism reduces the requirement for the material deformation threshold of the deformable diaphragm 441 and extends the service life of the thermal expansion element 44.

[0038] Please refer to Figures 2 to 4, the present application further proposes that the temperature sensing element 442 includes a plurality of temperature sensing parts 442a and a heat conducting strip 442b connected to the plurality of temperature sensing parts 442a. The heat conducting strip 442b is connected to the deformation diaphragm 441 and extends out from the perforation 41b. The plurality of temperature sensing elements 442 are axially spaced and distributed along the outer surface of the inner container 30, and are all connected to the heat conducting strip 442b, and two adjacent temperature sensing parts 442a are connected.

[0039] In this embodiment, the temperature sensing part 442a is a plurality of independently distributed metal temperature sensing units (such as copper cylinders), which are axially spaced and fixed on the outer surface of the inner container 30, directly contacting the innermost layer of the heat insulation structure 20, and capturing local temperature rise signals (heat insulation failure points) in real time. The heat conducting strip 442b is a high heat conducting metal strip, which connects a plurality of temperature sensing parts 442a and extends to the perforation 41b of the valve body 41, and is used to collect the heat of each temperature sensing part 442a and transfer the temperature change to the deformation diaphragm 441.

[0040] When the heat insulation fails at a certain place, the local temperature of the outer wall of the inner container 30 suddenly rises from -196°C, causing the nearest temperature sensing part 442a to quickly absorb heat. The adjacent temperature sensing parts 442a form a heat network through the heat conducting strip 442b in parallel, and the heat is transferred axially to the deformation diaphragm 441. After being heated, the deformation diaphragm 441 bends towards the low expansion side to generate displacement, thereby pushing the valve stem 42 to move linearly. The displacement of the valve stem 42 drives the valve core 43 away from the guide hole 41e, and the high-pressure nitrogen is output from the guide hole 41e to the air outlet 41d, triggering the pressure relief and subsequent recovery process.

[0041] In this embodiment, by axially arranging the temperature sensing parts 442a in a dot matrix, the entire area of the outer surface of the inner container 30 is covered, eliminating the monitoring blind area; any single-point failure can be covered by the adjacent temperature sensing parts 442a, improving the reliability; the heat conducting strip 442b synchronously transmits the local temperature rise signal, better controlling the trigger delay.

[0042] Please refer to 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 for reflecting residual radiant heat.

[0043] In this embodiment, the nano-aluminum oxide 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 by the sol-gel method or chemical vapor deposition method. This coating reduces the radiant heat absorbed by the temperature sensing element 442 through high reflectivity. Among them, the residual radiant heat refers to the heat transferred to the periphery of the temperature sensing element 442 that the heat insulation structure 20 fails to completely block. Specifically, it may come from the external environment or the heat conduction generated by the phase change of liquid nitrogen. This heat will cause temperature sensing errors of the temperature sensing element 442.

[0044] Specifically, when the adiabatic structure 20 experiences local failure or external heat source intrusion, 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 into the adiabatic structure 20 due to its high reflectivity, reducing the heat transferred to the body of the temperature sensing element 442. The surface of the temperature sensing element 442 is completely covered by the coating. For example, a full-wrap coating process is used to ensure that the heat reflection effect is evenly distributed in the contact area between the temperature sensing element 442, the inner container 30, and the adiabatic structure 20. Thus, the temperature sensing element 442 deforms only based on the actual ambient temperature change, avoiding misoperation of the valve core 43 caused by residual heat interference.

[0045] Compared with the prior art, the temperature sensing element 442 of the traditional liquid nitrogen storage tank is directly exposed to the gap of the adiabatic structure 20 and is easily affected by local thermal radiation, resulting in temperature misjudgment and causing the release valve 40 to open prematurely or delay. This solution forms a passive thermal shielding layer through the nano-aluminum oxide coating, which can suppress thermal interference without additional energy consumption and improve the temperature sensing accuracy.

[0046] Please refer to Figures 1 to 4 , this application further proposes that the liquid nitrogen storage tank further includes a condensation recovery container 50 and a liquid nitrogen delivery pump 60. The condensation recovery container 50 is connected to the air outlet hole 41d of the valve body 41 for recovering high-pressure nitrogen and liquefying the high-pressure nitrogen into liquid nitrogen; the liquid nitrogen delivery pump 60 is connected to the condensation recovery container 50 and the inner container 30, and is used to start when the pressure in the inner container 30 is lower than the set threshold, and deliver the condensed liquid nitrogen to the inner container 30.

[0047] In this embodiment, the condensation recovery container 50 refers to a closed container for collecting and liquefying high-pressure nitrogen, and specifically can be implemented by using a low-temperature container with a cooling coil and a compressor, and converting gaseous nitrogen into liquid by reducing the temperature and increasing the pressure. The liquid nitrogen delivery pump 60 refers to a mechanical device for delivering liquid nitrogen, and specifically can be implemented by using an electromagnetic drive type cryogenic pump, and controlling the start and stop state by detecting the pressure change inside the inner container 30. The set threshold refers to a preset pressure critical value, and specifically can be implemented by the linkage of a pressure sensor and a controller, and triggers the liquid nitrogen delivery pump 60 to work when the pressure is lower than this value.

[0048] Specifically, when the release valve 40 opens due to the temperature rise of the adiabatic structure 20, the high-pressure nitrogen enters the condensation recovery container 50 through the air outlet hole 41d and is re-liquefied in the low-temperature environment. The liquefied liquid nitrogen is stored in the condensation recovery container 50. When the pressure in the inner container 30 drops to the set threshold due to the evaporation of liquid nitrogen, the liquid nitrogen delivery pump 60 automatically starts, and pumps the liquid nitrogen in the condensation recovery container 50 back into the inner container 30, forming a closed-loop circulation system. This process maintains the dynamic balance of the pressure inside the inner container 30 through the linkage of pressure monitoring and pumping control.

[0049] Compared with the prior art, traditional liquid nitrogen storage tanks directly discharge nitrogen during pressure relief, resulting in waste of resources and inability to compensate for liquid nitrogen loss, leading to a sharp drop in pressure and the need for manual replenishment. This solution adds a condensation recovery and automatic replenishment system to convert the discharged gas into reusable liquid nitrogen and achieve automatic replenishment when the pressure is insufficient, avoiding potential safety hazards caused by lagging manual intervention.

[0050] Please refer to Figures 2 to 4 , in the adiabatic structure 20 of the liquid nitrogen storage tank further proposed in this application, the aluminum foam is closed-cell aluminum foam, or the pores of the aluminum foam are filled with fumed silica powder.

[0051] Among them, closed-cell aluminum foam refers to an aluminum foam material with independent and closed internal pores, which can be specifically prepared by powder metallurgy or melt foaming method. Its closed-cell structure can reduce convective heat transfer caused by gas flow. Fumed silica powder refers to nanoscale silica particles prepared by chemical vapor deposition process, which can be specifically produced by high-temperature hydrolysis of silicon tetrachloride. Its low thermal conductivity can fill the pores of aluminum foam to block the radiation heat transfer path.

[0052] Specifically, when the closed-cell aluminum foam is used as the spacer layer 22, its closed pore structure can avoid heat convection caused by gas flow, and at the same time support the reflective layer 21 through the aluminum matrix framework. When the pores of the aluminum foam are filled with fumed silica powder, the powder particles form a dense packing in the pores, reducing the heat radiation transfer efficiency by scattering and absorbing infrared radiation. Both implementation methods can enhance the heat insulation ability of the adiabatic structure 20, thereby reducing the pressure fluctuation caused by liquid nitrogen evaporation.

[0053] Please refer to Figure 2 , Figure 5 and Figure 6 , in this application, a flexible base film 21a is further provided on the surface of each reflective layer 21, and the flexible base film 21a is used to increase the flexibility of the reflective layer 21.

[0054] 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 realized by using polyimide film or polyester film. It provides elastic support for the reflective layer 21 through the ductility of the material itself, so that the reflective layer 21 can disperse local stress through the bending of the base film during the deformation process.

[0055] 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.

[0056] 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.

[0057] 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 characteristics of the metal, thereby reducing the evaporation loss of liquid nitrogen caused by thermal radiation penetration.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] In this embodiment, a glass fiber grid is embedded inside the spacer layer 22 to form a three-dimensional reinforcement framework. This structure provides shear resistance through the uniform distribution of the fiber grid, preventing creep deformation of the thermal insulation structure 20 during pressure fluctuations. Among them, the glass fiber grid cloth 22a refers to a mesh fabric woven from inorganic glass fibers, and its mesh aperture can be adjusted according to the thickness of the spacer layer 22. This material forms a rigid support through its high modulus characteristics, and at the same time, the inorganic material maintains dimensional stability in a low-temperature environment, avoiding internal stress caused by thermal expansion and contraction.

[0062] Specifically, the glass fiber grid cloth 22a is embedded in the preparation process of the spacer layer 22 in a pre-impregnation manner to form a reinforcement network penetrating the thickness of the material. Under alternating temperature or external load, the grid cloth disperses stress through the node connections between the fibers, suppressing the compressive deformation of the spacer layer 22. Since the thermal conductivity of glass fiber is lower than that of metal materials, the grid cloth will not form a thermal bridge between adjacent reflective layers 21, maintaining the low heat conduction characteristics of the thermal insulation structure 20.

[0063] This 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 working conditions, thereby maintaining the stable laminated structure of the reflective layer 21 and the spacer layer 22 of the thermal insulation structure 20, and improving the thermal insulation performance and container reliability during liquid nitrogen storage.

[0064] Please refer to Figure 2 、 Figure 5 and Figure 6 , this application further proposes that the interlayer density of multiple reflective layers 21 decreases gradually in a gradient manner from the outside to the inside along the radial direction of the container.

[0065] In this embodiment, the interlayer density refers to the material distribution degree of the reflective layer 21 per unit volume, which can be specifically achieved by adjusting the foil thickness or the corrugated structure spacing. Among them, the gradient decrease means that the density of the reflective layer 21 gradually decreases from the outer surface to the inner cavity along the radial direction of the container, which can be specifically achieved by gradually reducing the corrugated structure compression rate layer by layer or selecting metal foils with different porosities. This design enables the outer layer to preferentially reflect most of the incident thermal radiation, while the inner layer maintains the basic reflection performance through a lower density and reduces the concentration of thermal stress.

[0066] Specifically, the high-density reflective layer 21 on the outside of the thermal insulation structure 20 forms a dense thermal reflection interface, reflecting the infrared radiation transmitted from the external environment and reducing the penetration of heat to the inside; the density of the intermediate layer gradually decreases, gradually releasing the deformation stress generated by temperature changes while maintaining the thermal reflection ability; the low-density reflective layer 21 on the innermost side reduces the overall mass of the thermal insulation structure 20, avoiding interlayer peeling caused by differences in thermal expansion of materials. Through layer-by-layer thermal resistance matching, non-uniform heat conduction caused by the temperature difference between the inside and outside of the container is reduced, the liquid nitrogen evaporation rate is suppressed, and pressure fluctuations are alleviated.

[0067] This solution optimizes the thermal resistance distribution through gradient density distribution, enabling the outer layer to primarily undertake the function of heat reflection and the inner layer to focus on maintaining structural stability, effectively balancing the requirements of heat reflection efficiency and mechanical strength, and reducing the interference of temperature changes on the storage state.

[0068] Please refer to Figure 2 、 Figure 5 and Figure 6 For this, the present application further proposes to coat a vacuum layer 23 on the outer side of the adiabatic structure 20; the vacuum layer 23 includes a porous core material 231 and a barrier film 232, and the barrier film 232 is coated on the outer surface of the porous core material 231 and evacuated and sealed; the porous core material 231 is selected from fumed silica or fiberglass felt.

[0069] In this embodiment, the vacuum layer 23 refers to a closed space structure formed by evacuation, which is filled with the porous core material 231 and wrapped by the barrier film 232, and is used to eliminate the heat conduction path of gas molecules and inhibit the transfer of external heat by gas convection. The porous core material 231 refers to a material with a nanoscale pore structure, such as fumed silica or fiberglass felt, which adsorbs residual gas molecules through a high specific surface area, reduces the solid heat conduction rate, and at the same time 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 degree.

[0070] Specifically, the vacuum layer 23 is arranged on the outer side of the adiabatic structure 20, and a closed cavity is formed by evacuating through the barrier film 232 to block the heat of the external environment from entering the container interior through gas convection and conduction. The nanoscale pore structure of the porous core material 231 can reduce the solid contact heat transfer area and lower the heat conduction efficiency of the material itself. The adsorption characteristics of fumed silica or fiberglass felt can capture the residual gas molecules in the vacuum cavity and avoid the heat conduction generated by the movement of gas molecules. The vacuum layer 23 and the alternately arranged reflection layer 21 and spacer layer 22 on the inner side form a composite adiabatic barrier. The reflection 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 heat barrier mechanism.

[0071] This solution, through the superposition of the vacuum layer 23 and the reflection-spacer composite structure, while blocking gas heat conduction, synchronously suppresses radiative heat transfer and solid heat conduction, realizes multi-dimensional heat barrier, and thus significantly reduces the thermal interference of external temperature changes on the liquid nitrogen in the container.

[0072] Please refer to Figure 2 、 Figure 5 and Figure 6, the present application further proposes that a moisture-proof layer 24 and a protective layer 25 are sequentially stacked outside the vacuum layer 23. The moisture-proof layer 24 is used to block the penetration of water vapor, and the protective layer 25 is used to resist mechanical shock 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 sheet or a glass fiber-reinforced polyurethane layer.

[0073] In this embodiment, the moisture-proof layer 24 refers to an airtight barrier structure composed of multiple composite materials. Specifically, an aluminum-plastic composite film or a metallized polyester film can be used to achieve it. Its metal coating or aluminum foil layer blocks the water molecule penetration path through a dense structure, preventing external moisture from invading the inside of the vacuum layer 23 and causing an increase in the heat conduction efficiency. The protective layer 25 refers to an outer covering structure with mechanical strength and weather resistance. Specifically, a galvanized steel sheet or a glass fiber-reinforced polyurethane layer can be used to achieve it. The former forms an oxide film through the metal coating to resist the erosion of corrosive media, and the latter disperses the external impact load through the fiber-reinforced matrix. Both can maintain the integrity of the storage tank shell 10.

[0074] Specifically, the aluminum-plastic composite film forms multiple water vapor barrier layers through the composite superposition of the polyethylene layer and the aluminum foil, while maintaining flexibility. The metallized polyester film forms a nanoscale metal layer on the surface of the polyester substrate through a vacuum aluminizing process. Both can effectively reduce the water vapor transmission rate. The galvanized steel sheet forms sacrificial anode protection on the surface of the steel substrate through the zinc layer, delaying the oxidation corrosion process. The glass fiber-reinforced polyurethane layer forms a rigid shell with a high flexural modulus through the composite curing of the glass fiber grid and the polyurethane resin. The combined action of the two can resist the collision and extrusion stress during the transportation or installation of the storage tank. The superimposed layout of the moisture-proof layer 24 and the protective layer 25 forms a staged protection mechanism: the moisture-proof layer 24 is close to the vacuum layer 23 to preferentially block the penetration of water vapor, and the protective layer 25, as the outermost layer, directly responds to external mechanical damage and chemical corrosion. This structural layer effectively extends the service life of the vacuum insulation system.

[0075] This solution realizes the full protection of the liquid nitrogen storage environment through the material combination and spatial arrangement optimization 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.

[0076] Please refer to Figure 2 、 Figure 5 and Figure 6 , the present application further proposes that the thicknesses of multiple spacer layers 22 increase gradually in a gradient manner from the outside to the inside along the radial direction of the container.

[0077] 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 direction. Specifically, it can be achieved by gradually increasing the size of the polyimide honeycomb unit or changing the foaming density of the foam layer layer by layer, and different regional thermal resistance differential configurations are realized through the adjustment of the thickness distribution.

[0078] Specifically, during the storage of liquid nitrogen, when external heat is transferred from the container to the inside, the outer region bears a greater heat load due to the fluctuation of the ambient temperature. The thickness of the spacer layer 22 increases from the outside to the inside, which reduces the spacing of the outer reflective layer 21 and increases the density of the reflective interface per unit volume, enhancing the reflection ability of external thermal radiation; the increase in the thickness of the inner spacer layer 22 forms a longer solid heat conduction path, reducing the heat transfer rate. This gradient structure enables the heat insulation performance of different regions of the thermal insulation structure 20 to match the heat load distribution. The outer side rapidly attenuates the radiant heat through the high-density reflective layer 21, and the inner side suppresses the penetration of heat into the liquid nitrogen storage area through the low heat conduction path, thereby reducing the evaporation amount of liquid nitrogen and the amplitude of pressure fluctuation caused by temperature changes as a whole.

[0079] This solution realizes the dynamic adaptation of the thermal resistance distribution through the gradient thickness design, solves the problem of unbalanced thermal conduction between the inner and outer sides under the uniform structure, and at the same time avoids the structural redundancy and cost increase caused by simply increasing the number of reflective layers 21.

[0080] Please refer to Figure 1 、 Figure 2 、 Figure 5 and Figure 6 In this application, a processing system is further proposed, which includes a processing control host, a processing main device, an alarm auxiliary device, and a liquid nitrogen storage tank. The liquid nitrogen storage tank is provided with an electric control valve. The release valve 40 has an intake pipe communicating with the intake hole 41c. The electric control valve is arranged on the intake pipe and is electrically connected to the processing control host, and is used to open and close the intake pipe when receiving a signal from the processing control host in the non-discharge state.

[0081] In this embodiment, the electric control valve refers to an automatic control valve installed on the intake pipe, and specifically can be realized by using a solenoid valve or an electric ball valve, and controls the on-off of the pipeline by receiving an electric signal. The intake pipe refers to the pipeline structure connecting the intake hole 41c of the release valve 40, and can be specifically made of metal or low-temperature resistant polymer material, and is used to guide external gas into the valve body 41. The processing control host refers to a central processing device integrating a control module, and specifically can be an industrial computer or a programmable logic controller, and is used to coordinate the linkage operation of the processing main device, the alarm auxiliary device, and the electric control valve.

[0082] Specifically, in the non-discharge state, the processing control host sends a closing signal to the electric control valve to block the intake pipe and prevent external gas from entering the liquid nitrogen storage tank and causing pressure fluctuations. When the processing system detects an abnormal working condition, the processing control host sends a signal to the alarm auxiliary device to trigger an alarm, and at the same time judges whether to open the electric control valve for pressure relief operation according to a preset program. Through the linkage control of the electric control valve and the host, the opening and closing state of the intake pipe can accurately match the operation requirements of the system.

[0083] Compared with the prior art, the intake pipeline of traditional liquid nitrogen storage tanks usually adopts manual valves or independent pressure switches for control, which has problems such as response lag and operation dependence on manual labor. Through the direct electrical connection between the electric control valve and the processing control host, this solution realizes the automatic control of the opening and closing of the intake pipeline, can dynamically adjust based on the real-time working conditions of the system, and avoids the risk of pressure out of control caused by delays in manual operation.

[0084] Through the above technical solution, this application effectively solves the problem of drastic pressure changes caused by the intrusion of external gas during the liquid nitrogen storage process. By automatically blocking the intake pipeline, it reduces the evaporation loss of liquid nitrogen, reduces the explosion hazard caused by abnormal increase in the internal pressure of the storage tank, and at the same time improves the overall operation stability of the processing system.

[0085] The above is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made under the technical concept of the present invention by using the content of the specification and drawings 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 a housing, an inner tank, and a thermal insulation structure. The inner tank is disposed within the housing and is used for storing liquid nitrogen. The thermal insulation structure is disposed between the inner tank and the housing and includes a plurality of reflective layers and a plurality of spacer layers that are stacked and arranged alternately. The reflective layers are used for reflecting infrared radiation light, and the spacer layers are aluminum foam layers that provide physical support and heat insulation between two adjacent reflective layers.

2. The liquid nitrogen storage tank according to claim 1, characterized in that, The liquid nitrogen storage tank further includes a release valve, and the release valve includes: A valve body disposed at the top of the housing. The valve body has a valve cavity, a through hole communicating with the valve cavity, an air inlet hole, an air outlet hole, and a guiding through hole. The air inlet hole is located at the bottom of the valve body, the air outlet hole is located at the side of the valve body, the through hole is located at the center of the top of the valve body, and the guiding through hole is located between the air inlet hole and the air outlet hole. A valve stem movably connected within the valve cavity. A valve core connected to one end of the valve stem and movably connected between the guiding through hole and the air inlet hole; and A thermal expansion element connected to the end of the valve stem away from the valve core. The end of the thermal expansion element away from the valve stem extends between the inner tank and the thermal insulation structure and contacts the inner tank and the thermal insulation structure, and is used for sensing the temperature of the thermal insulation structure to drive the valve stem to push the valve core closer to or away from the guiding through hole.

3. The liquid nitrogen storage tank according to claim 2, wherein The thermal expansion element includes a deformation diaphragm and a temperature sensing member connected to the deformation diaphragm. The temperature sensing member extends from the through hole between the inner tank and the thermal insulation structure and contacts the inner tank and the thermal insulation structure. A lever amplification mechanism is provided on the side of the deformation diaphragm away from the temperature sensing member and is connected to the valve stem through the lever amplification mechanism.

4. The liquid nitrogen storage tank according to claim 3, wherein, The temperature sensing member includes a plurality of temperature sensing portions and a heat conducting strip connected to the plurality of temperature sensing portions. The heat conducting strip is connected to the deformation diaphragm and extends from the through hole. The plurality of temperature sensing members are axially spaced apart along the outer surface of the inner tank and are all connected to the heat conducting strip, and two adjacent temperature sensing portions are connected.

5. The liquid nitrogen storage tank according to claim 3, characterized in that, The surface of the temperature sensing member is coated with a nano-aluminum oxide coating for reflecting residual radiant heat.

6. The liquid nitrogen storage tank according to claim 2, wherein The liquid nitrogen storage tank further includes a condensation recovery container and a liquid nitrogen transfer pump. The condensation recovery container is communicated with the air outlet hole of the valve body and is used for recovering high-pressure nitrogen gas and liquefying the high-pressure nitrogen gas into liquid nitrogen. The liquid nitrogen transfer pump is communicated with the condensation recovery container and the inner tank and is used for starting when the pressure in the inner tank is lower than a set threshold value and transferring the condensed liquid nitrogen into the inner tank.

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

8. The liquid nitrogen storage tank according to claim 1, wherein, A flexible base film is provided on the surface of each reflective layer, and the flexible base film is used for increasing the flexibility of the reflective layer; And / or, an aluminized layer is provided on the surface of the flexible base film, and the aluminized layer is used for reflecting infrared radiation light; And / or, a fiberglass mesh cloth is embedded in the spacer layer for enhancing its structural rigidity.

9. The liquid nitrogen storage tank according to claim 1, wherein The outside of the thermal insulation structure is coated with a vacuum layer, and the vacuum layer includes: A porous core material; and A barrier film, which is coated on the outer surface of the porous core material and evacuated and sealed to block gas heat conduction; and the porous core material is fumed silica or glass fiber felt.

10. A processing system, characterized in that, The processing system includes:[[]] A processing control host computer; A processing main body device, which is electrically connected to the processing control host computer and is used for performing processing operations on products; An alarm auxiliary device, which is electrically connected to the processing control host computer and is used for reminding personnel to carry out accident prevention work when receiving an alarm signal sent by the processing control host computer; and The liquid nitrogen storage tank according to any one of claims 1 to 9, the liquid nitrogen storage tank has an electric control valve, the release valve of the liquid nitrogen storage tank has an intake pipeline communicating with the intake hole, the electric control valve is arranged on the intake pipeline and is electrically connected to the processing control host computer, and is used for opening and closing the intake pipeline when receiving a signal from the processing control host computer in a non-discharge state.

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