Cryogenic tank

Abstract

To optimize tank mass in a transportable tank made of a metal material.SOLUTION: A cryogenic tank comprises an inner shell intended to contain cryogenic fluid, and an outer shell arranged around the inner shell and delimiting a space between the inner and outer shells under vacuum, the outer shell extending in a longitudinal direction (A) and having a plurality of reinforcing ribs (4) distributed in planes that is perpendicular to the longitudinal direction, the reinforcing ribs being formed by deformations, for example by knurling, on a same wall of the outer shell. The cryogenic tank (1) also comprises at least one reinforcing element for reinforcing at least a part of at least one of the reinforcing ribs, the reinforcing element comprising a strip rigidly connected to two portions of the wall situated at a base part and on both sides of the reinforcing rib.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to cryogenic tanks.

[0002] More specifically, the present invention is a cryogenic tank, particularly for transporting cryogenic fluids such as liquid helium or hydrogen, comprising an inner shell made of a metallic material or alloy and intended to contain the cryogenic fluid, and an outer shell made of a metallic material or alloy, disposed around the inner shell and separating the space between the inner and outer shells, the space being under vacuum, the outer shell extending in the longitudinal direction and comprising a plurality of reinforcing ribs distributed in a plane perpendicular to the longitudinal direction, the reinforcing ribs being formed by deformation, for example by knurling, on the same wall of the outer shell, related to the tank.

Background Art

[0003] Conventionally, cryogenic tanks have used a vacuum-insulated double-shell structure to ensure the self-discipline of storage when transporting cryogenic liquids.

[0004] These shells made of metal or alloy are manufactured by canning operations and thus comply with the manufacturing standards (e.g., ASME VIII) of the canning operations. These shells must withstand external pressure as they enclose a vacuum and must not affect the mass of the tank (or the container in which it is stored).

[0005] Tanks under vacuum are mainly dimensioned to resist external pressure. This mechanical resistance is ensured by the appropriate thickness of the shell rings (welded metal plates forming a cylindrical shell) and / or by stiffening elements.

[0006] In the case of transportable tanks made of metallic materials, optimizing the mass is a major issue, and the solution of thickening the shell walls does not make it possible to obtain an appropriate tank mass. One solution would be to use a metallic material of the aluminum alloy type, but the low Young's modulus of this material requires an increase in thickness.

[0007] One known solution, therefore, consists of adding stiffeners (ribs) to the wall, which is to add hoops that are either welded or formed by deforming the shell ring (e.g., knurling) in order to stiffen the shell ring.

[0008] Reinforcing with welded hoops can present problems in terms of bulkiness, and these hoops must be present around the entire circumference of the shell ring to ensure their effectiveness. These hoops are generally thicker than the shell ring and add mass to the instrument.

[0009] Reinforcing the tank with ribs formed by deforming metal sheets (knurling process) does not add any mass to the tank, but it does pose a problem in terms of the low axial stiffness of the shell ("accordion" effect). This effect is even more pronounced in aluminum shells. [Overview of the Initiative]

[0010] One objective of the present invention is to overcome all or some of the drawbacks of the prior art outlined above.

[0011] For this purpose, the tank according to the present invention, otherwise conforming to the comprehensive definition given in the above preface, is characterized in that the tank also comprises at least one reinforcing element for reinforcing at least a portion of at least one of the reinforcing ribs, wherein the reinforcing element comprises strips rigidly connected to the base of the reinforcing rib and to two portions of the wall located on both sides thereof.

[0012] Furthermore, embodiments of the present invention may have one or more of the following features: - The strip is made of a metal material or alloy and welded to the outer shell. - The reinforcing ribs extend over all or part of the circumference of the outer shell, and at least part of the reinforcing ribs are provided with at least one strip. -At least a portion of the reinforcing ribs is provided with multiple individual strips, for example, three strips, distributed over a portion of the circumference of the outer shell. - The strip extends in a plane perpendicular to the longitudinal direction over 40-80%, preferably 50-70%, of the circumference of the outer shell. -One or more strips have a width that is 1 to 3 times the width of the reinforcing rib, measured parallel to the longitudinal direction. - The inner and outer shells have a general cylindrical shape with a circular cross-section and extending in the longitudinal direction and in the circular cross-section, and the longitudinal axis is oriented horizontally when the cryogenic tank is in transport or operational configuration. - The reinforcing ribs protrude from the outer surface of the outer shell.

[0013] The present invention may also relate to any alternative device or method comprising any combination of the above or below features of the claims.

[0014] Other notable features and advantages will become apparent upon reading the following description, which is provided with reference to the diagram.

[0015] The present invention will be better understood by reading the following description, which is given merely as an example and with reference to the accompanying drawings. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic partial perspective view of an example of a tank according to the present invention. [Figure 2] This is a schematic partial view of the longitudinal cross-section of the tank. [Figure 3] This is a schematic partial perspective view of the detailed cross-section of the tank. [Modes for carrying out the invention]

[0017] Throughout the diagram, the same reference numerals refer to the same elements.

[0018] In the embodiments for carrying out this invention, the following embodiments are examples. The description refers to one or more embodiments, but this does not mean that the features are applicable only to a single embodiment. The individual features of different embodiments can also be combined and / or exchanged to provide other embodiments.

[0019] The exemplary tank 1 is a cryogenic tank for storing and transporting cryogenic fluids, for example, liquefied helium or hydrogen.

[0020] This tank 1 is made of a metallic material or alloy and includes an inner shell 2 intended to contain the cryogenic fluid. The tank 1 also includes an outer shell 3 made of a metallic material or alloy, disposed around the inner shell 2, and separating the space between the inner shell 2 and the outer shell 3. This space is under vacuum and preferably includes a heat insulating material, for example, multilayer insulation (MLI).

[0021] The tank 1, particularly the outer shell 3, extends in the longitudinal direction A.

[0022] As illustrated, the inner shell 2 and the outer shell 3 preferably have a generally cylindrical shape with a circular cross-section that extends in the longitudinal direction A.

[0023] That is, each shell has a central cylindrical portion formed by a metal plate or shell ring, and its ends are closed by respective domes.

[0024] Preferably, the longitudinal axis A is oriented horizontally when the tank 1 is in the transport or use configuration.

[0025] The outer shell 3 includes a plurality of reinforcing ribs 4 distributed in a plane perpendicular to the longitudinal direction A. The reinforcing ribs 4 are formed by deformation, for example, knurling, on the same wall (central cylindrical portion) of the outer shell 3.

[0026] As illustrated, these ribs 4 preferably protrude from the outer surface of the outer shell 3. Preferably, the ribs 4 are formed along the entire circumference of the outer shell 3. For example, the ribs 4 are formed on the cylindrical wall so that they are spaced apart in the longitudinal direction A by a distance of 50 to 200 mm, for example, about 100 mm.

[0027] Preferably, the ribs 4 are regularly distributed longitudinally A on the cylindrical portion (shell ring) according to the following formula, for example: d = L / (n+2), where d = the distance between two adjacent ribs, L = the length of the shell ring, and n = the number of ribs. The distance d may vary depending on other assembly elements (e.g., the position of the feet on the tank), but the distance d is preferably constant between each rib to distribute the stiffness of the shell ring.

[0028] The shell ring (the cylindrical portion of the component) is thus equipped with multiple ribs 4 obtained by mechanical deformation.

[0029] Furthermore, at least one, preferably all, of the ribs 4 are provided with at least one reinforcing element 5. The reinforcing element 5 comprises a strip 5 made of, for example, metal or alloy, which is rigidly connected (fixed) to the base of the rib 4 and to two parts of the wall located on both sides.

[0030] The strip 5 is preferably welded to the outer shell 3 on both sides of the rib 4.

[0031] The rib 4 extends like a strip 5 in a plane perpendicular to the longitudinal direction A, over all or part of the circumference of the outer shell 3.

[0032] For example, one, more, or all of the ribs 4 may be provided with multiple individual strips 5 distributed around the circumference of the shell 3, for example, three strips 5. Preferably, the strips are uniformly distributed around the periphery of the tank 1.

[0033] For example, the strip 5 extends in a plane perpendicular to the longitudinal direction A over at least half of the circumference of the outer shell 3, and is therefore (welded / fixed) over at least half of the circumference of the shell 3.

[0034] Preferably, one or more strips 5 have a width L5 that is 1 to 3 times the width L4 of the reinforcing rib 4 and is measured in a direction parallel to the longitudinal direction A.

[0035] The proposed solution allows the axial rigidity of tank 1 to be improved by limiting or preventing the accordion effect. These strips 5 can be fixed to the inner surface of the outer shell 3.

[0036] These strips 5 increase the axial stiffness of the tank 1 and also function as force transmission elements. The strips 5 are preferably made of the same material as the shell 3 that is being stiffened. They allow the vacuum resistance of the tank 1 to be maintained. When forces pass through the support structure, the strips are preferably positioned in line with the support (tie rods / collars, etc.).

[0037] As explained above, these strips 5 can be fixed only at specific locations on the shell 3 (in practice, it is not necessary to provide these reinforcements 5 around the entire periphery of each rib 4). This limits the impact on the total mass of the tank 1.

Claims

1. In particular, a cryogenic tank for transporting cryogenic fluids, such as liquefied helium or hydrogen, comprising: an inner shell (2) made of a metallic material or alloy and intended to contain the cryogenic fluid; and an outer shell (3) made of a metallic material or alloy, positioned around the inner shell (2) and separating the space between the inner shell (2) and the outer shell (3), wherein the space is under vacuum, and the outer shell (3) comprises a plurality of reinforcing ribs (4) extending in the longitudinal direction (A) and distributed in a plane perpendicular to the longitudinal direction (A), wherein the reinforcing ribs (4) are formed by deformation on the same wall of the outer shell (3), for example by knurling, in a cryogenic tank, The cryogenic tank (1) also comprises at least one reinforcing element (5) for reinforcing at least a portion of at least one of the reinforcing ribs (4), wherein the reinforcing element (5) comprises a strip (5) rigidly connected to the base of the reinforcing rib (4) and to two portions of the wall located on both sides of it.

2. The tank according to claim 1, characterized in that the strip (5) is made of a metal material or alloy and is welded to the outer shell (3).

3. The tank according to claim 1 or 2, characterized in that the reinforcing ribs (4) extend over all or part of the circumference of the outer shell (3), and at least part of the reinforcing ribs (4) is provided with at least one strip (5).

4. The tank according to claim 1 or 2, characterized in that at least a portion of the reinforcing rib (4) is provided with a plurality of individual strips (5), for example three strips (5), distributed over a portion of the circumference of the outer shell (3).

5. The tank according to claim 4, characterized in that the strip (5) extends in a plane perpendicular to the longitudinal direction (A) over 40 to 80%, preferably 50 to 70%, of the circumference of the outer shell (3).

6. The tank according to claim 1 or 2, characterized in that one or more of the strips (5) have a width (L5) that is 1 to 3 times the width (L4) of the reinforcing rib (4) when measured in a direction parallel to the longitudinal direction (A).

7. The tank according to claim 1 or 2, wherein the inner shell (2) and the outer shell (3) have a circular cross-section and have a general cylindrical shape extending in the longitudinal direction (A) and in the circular cross-section, and the longitudinal axis (A) is oriented horizontally when the cryogenic tank (1) is in a transport or use configuration.

8. The tank according to claim 1 or 2, characterized in that the reinforcing rib (4) protrudes from the outer surface of the outer shell (3).

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