Improved low-temperature double-layer vacuum storage tank

Abstract

The invention relates to the field of cryogenic liquid storage equipment, in particular to an improved low-temperature double-layer vacuum storage tank which comprises an inner tank and an outer tank which are fixedly connected through a supporting structure, an anti-radiation shielding layer is arranged between the inner tank and the outer tank, and the anti-radiation shielding layer is fixed to the supporting structure. A first vacuum interlayer is arranged between the inner tank and the anti-radiation shielding layer, a second vacuum interlayer is formed between the outer tank and the anti-radiation shielding layer, and a heat insulation material layer is arranged on the surface, located on one side of the second vacuum interlayer, of the anti-radiation shielding layer. The supporting structure is a low-heat-conduction hollow cylinder made of epoxy glass fiber reinforced plastic, the inner tank and the outer tank are connected, the anti-radiation shielding layer is fixed through a hoop, structure sharing is achieved, and a solid heat conduction path is not additionally added. Compared with a traditional double-layer tank, the heat leakage flux can be reduced by about 57.3%, the cold insulation time of ultralow-temperature media such as liquid hydrogen and liquid helium is remarkably prolonged, and meanwhile the storage capacity and the structural stability of the storage tank are kept unchanged.

Description

Technical Field

[0001] This invention relates to the field of cryogenic liquid storage equipment technology, specifically to an improved cryogenic double-walled vacuum storage tank. Background Technology

[0002] In the storage and transportation of cryogenic liquids, minimizing external heat transfer is crucial for ensuring the long-term, undamaged storage of the medium. Current technologies often employ double-walled tanks filled with high-vacuum multilayer insulation (MLI) material in the interlayer. This structure typically consists of dozens of alternating layers of aluminum foil / aluminized film reflective layers and glass fiber or polyester mesh spacers, which can reduce radiation and residual gas heat conduction to some extent. However, for cryogenic media such as liquid hydrogen, traditional structures still have the following shortcomings: solid heat conduction dominates on the cryogenic side of the insulation layer near the inner tank, resulting in insufficient thermal resistance; while variable-density arrangements can locally optimize heat flow, the improvement is limited and increases material costs; adding an evaporative cooling screen can reduce tank wall temperature, but it leads to liquid evaporation losses; and the supporting structure is mostly metal, forming significant solid heat conduction channels. Therefore, the insulation performance of current cryogenic double-walled vacuum storage tanks still needs improvement. Summary of the Invention

[0003] To address the shortcomings of the existing technology, the purpose of this invention is to provide an improved cryogenic double-walled vacuum storage tank, which overcomes the defects of existing double-walled vacuum storage tanks in terms of large heat leakage and short cold preservation time under ultra-low temperature conditions, reduces heat leakage, has strong structural versatility, and can be applied to various cryogenic media such as liquid hydrogen, liquid helium, and liquefied natural gas (LNG).

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: An improved cryogenic double-walled vacuum storage tank includes an inner tank and an outer tank, which are fixedly connected by a support structure. A radiation shielding layer is provided between the inner tank and the outer tank. The radiation shielding layer is fixed to the support structure by clamps. A first vacuum interlayer is provided between the inner tank and the radiation shielding layer. A second vacuum interlayer is provided between the outer tank and the radiation shielding layer. An insulation material layer is provided on the surface of the radiation shielding layer located on one side of the second vacuum interlayer. The insulation material layer includes a reflective layer and a spacer material. The reflective layer and the spacer material are arranged alternately, with the spacer material closest to the radiation shielding layer and the reflective layer on the outermost side.

[0005] In a preferred embodiment of the present invention, ...

[0006] In a preferred embodiment of the present invention, the thickness of the spacer material is 0.04mm-0.09mm, and the thickness of the reflective layer is 0.006mm-0.015mm.

[0007] The radiation shielding layer is made of metal, so if the reflective layer is in direct contact with it, heat will be directly transferred, and even extremely low temperatures can damage the reflective layer. Furthermore, direct contact may cause frictional damage. A spacer material with low thermal conductivity can effectively block this heat and prevent direct contact, thus avoiding potential damage. Therefore, the spacer material is generally placed closer to the radiation shielding layer. The outermost layer is usually the reflective layer. Heat enters the tank from the outside via radiation. Compared to the spacer material, the reflective layer reflects more heat, hindering its entry. The aluminum-coated film material is typically 0.012mm thick, while the fiberglass is generally less than 0.07mm thick.

[0008] In a preferred embodiment of the present invention, the supporting structure material is provided with four on each side, for a total of eight, and is symmetrically distributed at 90°. One side is rigidly connected to the tank body, and the other side is slidably connected.

[0009] The symmetrical arrangement of the support structure is to ensure that the cryogenic storage tank has optimal performance in multiple aspects such as structure, thermal, stability, and safety.

[0010] To ensure structural mechanical balance and prevent the inner tank from shifting or twisting, the supporting structure is the only structural path connecting the inner and outer tanks and bears the entire load. If the arrangement is asymmetrical, the load cannot be evenly distributed, which will lead to: eccentricity or tilting of the inner tank; local overload of the supports; and structural fatigue and fracture after long-term use. Symmetrical arrangement ensures a balanced load path and does not generate additional torque.

[0011] To ensure symmetrical thermal stress and prevent uneven thermal bridging and structural deformation, the temperature difference between the inner and outer tanks of liquid hydrogen can reach as high as 273°C. Each support point inevitably conducts heat; if the arrangement is asymmetrical, localized heat flow concentration will occur, leading to uneven thermal expansion and contraction, and the tank may crack, deform, or fail due to stress concentration. A symmetrical arrangement ensures that the direction and magnitude of heat flow and deformation are consistent, preventing tank deformation or damage.

[0012] Earthquake resistance and transportation safety are crucial. Storage tanks are subject to shaking, vibration, or seismic loads during transportation or use. Asymmetrical arrangements can easily induce torsional vibration modes, causing asynchronous operation of support points and leading to structural failure. Symmetrical distribution of support points allows external forces from all directions to be transmitted and absorbed synchronously, resulting in better overall rigidity and making them less prone to loosening or breakage.

[0013] Convenient manufacturing and installation, and error control. During factory manufacturing or on-site installation, the support points must be precisely positioned; symmetrical arrangement facilitates mirror positioning and symmetrical mold processing, ensuring high precision; asymmetrical arrangement will introduce installation deviations, and may even lead to the failure of the entire inner tank installation or vacuuming failure.

[0014] The support structure features a rigid connection on one side and a sliding connection on the other. The core purpose is to allow the cryogenic storage tank to expand and contract due to temperature changes, preventing excessive internal stress and ensuring the safety of the tank and its supports. During operation, the inner and outer tanks experience significant temperature differences; the tank material undergoes thermal expansion and contraction, resulting in changes in length and volume. If both ends of the support are rigidly fixed, the deformation caused by thermal expansion and contraction is restricted, generating enormous thermal stress that could lead to damage, cracking, or instability of the tank or its supports. The rigid connection on one side stably secures the entire tank to the foundation or outer shell, providing structural positioning and force support; the sliding connection on the other side allows the support structure to move freely along the sliding direction when length changes occur due to thermal expansion and contraction, avoiding constraint on the thermal deformation of the inner or outer tank. This ensures the safety of the tank and its supports.

[0015] In a preferred embodiment of the present invention, the clamp is made of glass fiber reinforced plastic and is arranged below and on both sides of the radiation shielding layer to maintain a gap of 20mm-50mm between the radiation shielding layer and the outer wall of the inner tank.

[0016] In a preferred embodiment of the present invention, the thickness of the radiation shielding layer is 0.3mm-1mm, the material is stainless steel, and the surface is polished or aluminum-plated.

[0017] In a preferred embodiment of the present invention, the vacuum degree of both the first vacuum interlayer and the second vacuum interlayer is ≤1×10⁻⁶. -2 Pa.

[0018] Compared with the prior art, the beneficial effects of the present invention are: 1. The improved cryogenic storage tank provided by this invention isolates and reflects externally conducted heat radiation by setting multiple layers of insulation material outside the radiation shielding layer, thereby significantly reducing the heat leakage entering the inner tank. By adding a radiation shielding layer, the tank body forms a double vacuum structure, effectively reducing solid heat conduction without changing the storage capacity. The shared support structure ensures the stability and safety of the tank body, and no additional heat leakage path is created by setting other support structures. Combined with the use of low thermal conductivity glass fiber reinforced plastic clamps, the radiation shielding layer can be fixed without causing excessive additional heat leakage. The radiation shielding layer does not need to bear a large amount of structural strength like the inner and outer tank walls; it only needs to bear the weight of the wrapped insulation material. Thin materials can be selected, which not only saves materials and reduces weight but also reduces heat conduction and transfer.

[0019] 2. The structure of this invention is highly versatile and can be applied to various cryogenic media such as liquid hydrogen, liquid helium, and LNG. This invention adds a low emissivity radiation shielding vacuum interlayer in the low-temperature region to construct a locally suspended thermal resistance layer, forming a new thermal radiation reflection interface and reducing the heat conduction path between solids. Through layer-by-layer heat transfer model analysis, the heat flux is reduced to 1.05 W / m², and the performance improvement reaches 57.3%. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the storage tank of the present invention.

[0021] Figure 2 This is a partially enlarged view of the winding method of the multilayer thermal insulation material of the present invention.

[0022] Figure 3 This is a structural diagram of the thermal insulation material layer of the present invention.

[0023] Figure 4 This is a cross-sectional view of the support structure and clamp arrangement of the present invention.

[0024] Figure 5 The graph shows a comparison of the heat flux between the traditional structure and the structure of this invention.

[0025] Explanation of reference numerals in the attached figures: 1. Inner tank; 2. Radiation shielding layer; 3. Outer tank; 4. Support structure; 5. Clamp; 6. First vacuum interlayer; 7. Second vacuum interlayer; 8. Insulation material layer; 88. Reflective layer; 888. Spacer material. Detailed Implementation

[0026] The following detailed description, in conjunction with embodiments of the present invention and accompanying drawings, provides a clear and complete illustration of the technical solutions in these embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] It should be noted that all technical terms used in this invention are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.

[0028] This invention provides an improved double-vacuum cryogenic liquid storage tank; comprising an inner tank 1, a radiation shielding layer 2, an outer tank 3, a supporting structure 4, clamps 5, a first vacuum interlayer 6, a second vacuum interlayer 7, and a thermal insulation material layer 8; specifically as follows: Figures 1 to 4As shown, the inner tank 1 and the outer tank 3 are fixedly connected by a support structure 4. A radiation shielding layer 2 is provided between the inner tank 1 and the outer tank 3. The radiation shielding layer 2 is fixed to the support structure 4 by clamps 5. A first vacuum interlayer 6 is provided between the inner tank 1 and the radiation shielding layer 2. A second vacuum interlayer 7 is provided between the outer tank 3 and the radiation shielding layer 2. A heat insulation material layer 8 is provided on the surface of the radiation shielding layer 2 located on one side of the second vacuum interlayer 7. The heat insulation material layer 8 includes a reflective layer 88 and a spacer material 888.

[0029] In this invention, the inner tank 1, the radiation shielding layer 2, and the outer tank 3 are all cylindrical in the middle. The inner tank 1 and the radiation shielding layer 2 have semi-circular end caps at both ends, and the outer tank has a dish-shaped end cap, forming a closed tank body. The inner tank 1 and the radiation shielding layer 2 are not in direct contact, and a vacuum is drawn to form a first vacuum interlayer 6. The radiation shielding layer 2 and the outer tank 3 are not in contact, and a vacuum is drawn to form a vacuum interlayer 7.

[0030] In this invention, such as Figure 2 and Figure 3 As shown, in this invention, the heat insulation material is wound around the radiation shielding layer 2. The heat insulation material layer 8 includes a reflective layer 88 and a spacer material 888, which are arranged in alternating layers. The spacer material 888 is closest to the radiation shielding layer 2, and the outermost layer is the reflective layer 88. The reflective layer 88 reflects external heat, reducing the leakage of external heat. The spacer material 888 prevents the reflective layer 88 from directly contacting the radiation shielding layer 2. The reflective layer material is selected from aluminum foil or aluminized film with low emissivity, and the spacer material is selected from glass fiber or polyester mesh with low thermal conductivity.

[0031] In this invention Figure 1 As shown, it also includes a support structure set between the outer wall of the inner tank 1 and the inner wall of the outer tank 3. The support members are symmetrically distributed on the left and right sides of the tank, with 4 support members 4 on each side. The left side is rigidly connected to the tank body, and the right side is slidably connected, allowing for a small range of movement at different temperatures.

[0032] In this invention, the support structure 4 is a cylindrical structure with a hollow center, and the material is epoxy fiberglass with low thermal conductivity, which can reduce heat conduction while ensuring strength.

[0033] In this invention, such as Figure 4 As shown, there are 4 support structures on each side, and the support structures on each side are symmetrically distributed at 90° in the cross-sectional direction.

[0034] In this invention, since the radiation shielding layer 2 is mainly used to reflect heat, its strength requirement is relatively low. It is made of 316L stainless steel with low emissivity. The radiation shielding layer is surface polished or coated with an aluminum coating to make the surface emissivity sufficiently low, reaching 0.04-0.1, thereby reducing radiative heat transfer. The thickness can be controlled between 0.3mm and 1mm to reduce the weight of this layer. The radiation shielding layer 2 shares the support structure 4 with the outer tank 3 to prevent additional heat loss pathways.

[0035] In this invention, such as Figure 4 As shown, clamps 5 are used to fix the radiation shielding layer 2, with one clamp 5 paired with each support structure 4; in the vertical direction, the clamps 5 are all arranged below the radiation shielding layer 2, and in the horizontal direction, the clamps 5 are all arranged on both sides of the radiation shielding layer 2. Low thermal conductivity glass fiber reinforced plastic is used to prevent the radiation shielding layer 2 from moving, ensuring a stable 30mm gap between the radiation shielding layer 2 and the outer wall of the inner tank 1, while reducing radial heat transfer.

[0036] Results Analysis Figure 5 The graph shows a comparison of heat flux between the traditional structure and the structure of this invention. The conclusions are derived from layer-by-layer model analysis. The structure is a comparison between the improved cryogenic storage tank and a traditional double-walled tank. The inner tank contains liquid hydrogen, while the outer tank corresponds to the ambient temperature. It employs a 30-layer multi-layer insulation structure composed of alternating layers of fiberglass insulation pads and aluminized films. Both corresponding vacuum layers are 10°C. -2 Pa, at which point the heat flux of the conventional structure can be observed to be approximately 2.46 W / m. 2 , The improved cryogenic double-layer vacuum storage tank of this invention involves evacuating both the first and second vacuum jackets during use. Since the two jackets are not completely sealed, only one jacket needs to be evacuated. Once the required vacuum level is achieved, the tank is pre-cooled. A small amount of the desired cryogenic liquefied gas can then be slowly injected into the tank. This liquefied gas absorbs heat, vaporizes, and is discharged from the tank. After the tank temperature drops to a suitable level, it can be filled with cryogenic media such as liquid hydrogen.

[0037] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of the invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.

[0038] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. An improved cryogenic double-walled vacuum storage tank, characterized in that, The device includes an inner tank (1) and an outer tank (3), which are fixedly connected by a support structure (4). A radiation shielding layer (2) is provided between the inner tank (1) and the outer tank (3). The radiation shielding layer (2) is fixed to the support structure (4) by a clamp (5). A first vacuum interlayer (6) is provided between the inner tank (1) and the radiation shielding layer (2). A second vacuum interlayer (7) is provided between the outer tank (3) and the radiation shielding layer (2). A heat insulation material layer (8) is provided on the surface of the radiation shielding layer (2) located on the side of the second vacuum interlayer (7). The heat insulation material layer (8) includes a reflective layer (88) and a spacer material (888). The reflective layer (88) and the spacer material (888) are arranged alternately. The spacer material (888) is closer to the radiation shielding layer (2), and the outermost layer is the reflective layer (88).

2. The improved cryogenic double-walled vacuum storage tank according to claim 1, characterized in that, The reflective layer (88) can be any one of the following, and the spacer material (888) can be any one of the following.

3. The improved cryogenic double-walled vacuum storage tank according to claim 1, characterized in that, The thickness of the spacer material (888) is 0.04mm-0.09mm, and the thickness of the reflective layer (88) is 0.006mm-0.015mm.

4. The improved cryogenic double-walled vacuum storage tank according to claim 1, characterized in that, The supporting structure (4) is made of material, with four on each side, for a total of eight, and is symmetrically distributed at 90°. One side is rigidly connected to the tank body, and the other side is slidably connected.

5. The improved cryogenic double-walled vacuum storage tank according to any one of claims 1, characterized in that, The clamp (5) is made of glass fiber reinforced plastic and is arranged below and on both sides of the radiation shielding layer (2) to maintain a gap of 20mm-50mm between the radiation shielding layer (2) and the outer wall of the inner tank (1).

6. The improved cryogenic double-walled vacuum storage tank according to claim 1, characterized in that, The thickness of the radiation shielding layer (2) is 0.3mm-1mm, the material is stainless steel, and the surface is polished or aluminum plated.

7. The improved cryogenic double-walled vacuum storage tank according to claim 1, characterized in that, The vacuum levels of both the first vacuum interlayer (6) and the second vacuum interlayer (7) are ≤1×10⁻⁶. -2 Pa.

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