Tank for storing cryogenic fluid

Abstract

To reduce or eliminate stratification in cryogenic tanks.SOLUTION: The invention relates to a tank for storing cryogenic fluid, for example hydrogen or liquefied helium, comprising a storage shell 2 with a cylindrical overall shape extending in a longitudinal direction that is horizontal when the tank 1 is in the use configuration, the storage shell 2 comprising, within it, a homogenization device 3 for homogenizing the temperature of the fluid vertically in the tank 1, the homogenization device consisting of at least one heat transfer wall 3 consisting of a material with a coefficient of thermal conductivity of greater than 30 W m-1 K-1, said transfer wall 3 being arranged parallel to the longitudinal direction of the tank 1 and extending vertically over 20 to 100% of the height of the storage shell 2 and extending longitudinally over at least 50% of the length of the storage shell 2.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a tank for storing cryogenic fluids.

[0002] More specifically, the present invention relates to a tank for storing cryogenic fluids, such as hydrogen or liquid helium, comprising a storage shell having a cylindrical overall shape extending in a longitudinal direction that is horizontal when the tank is in use, the storage shell comprising, inside thereof, a homogenization device for vertically homogenizing the temperature of the fluid in the tank, the homogenization device comprising at least one heat transfer wall made of a material having a thermal conductivity greater than 30 W·m -1 ·K -1 and consisting of at least one heat transfer wall made of a material having a thermal conductivity greater than 30 W·m

Background Art

[0003] Cryogenic tanks, especially those containing fluids with very low specific evaporation enthalpies and significant density differences between the liquid and gas phases, such as helium or hydrogen, tend to have significant temperature differences between their liquid and gas phases. This results in a faster pressure increase than is observed when the two phases have similar temperatures. This phenomenon is often referred to as "stratification".

[0004] During long periods of parking, cryogenic tanks may reach their maximum pressure due to this pressure increase. In order to avoid exceeding this value, it is necessary to remove molecules. The stratification effect will amplify this drawback.

Summary of the Invention

[0005] An object of the present invention is to reduce or eliminate stratification in a cryogenic tank.

[0006] A known solution for storing liquid helium consists of providing an aluminum plate arranged at the top of the tank, the lower part of which is generally immersed in the liquid helium phase close to the lower end.

[0007] This solution only partially addresses the problem and is not entirely satisfactory, especially for liquid hydrogen tanks.

[0008] The object of the present invention is to overcome all or some of the above-mentioned drawbacks of the prior art.

[0009] For this purpose, the tank according to the invention complies in other respects with its general definition given in the above preamble, and is essentially characterized in that the heat transfer wall is arranged parallel to the longitudinal direction of the tank, extends vertically over 20 to 100% of the height of the storage shell, and extends longitudinally over at least 50% of the length of the storage shell.

[0010] Furthermore, embodiments of the present invention may have one or more of the following features: - The heat transfer wall extends vertically over 60 to 100%, for example 80 to 100%, preferably 90 to 100% of the height of the storage shell, - The heat transfer wall extends longitudinally over at least 80% of the length of the storage shell, - The heat transfer wall is made of aluminum or a stainless alloy, - The heat transfer wall has a thickness of 1 mm to 8 mm, - The heat transfer wall has holes and / or corrugations and / or at least one fin extending in a transverse direction with respect to the heat transfer wall, - The heat transfer wall has one or more fins extending in a transverse direction with respect to the wall over a transverse distance with respect to a heat transfer wall that is less than half, preferably less than a quarter, of the diameter of a storage shell having a cylindrical overall shape, - The heat transfer wall is fixed to the storage shell by welding and / or screwing and / or riveting, - The tank comprises a set of circuits and equipment inside the storage shell, and the heat transfer wall forms a support for at least some of the circuits and / or equipment, - The tank is of the double-wall type, i.e., it includes an outer shell arranged around the storage shell having a space containing a heat insulating material.

[0011] The present invention may also relate to any alternative device or method comprising any combination of the above or below features within the scope of the claims.

[0012] Further specific features and advantages will become apparent upon reading the following description provided with reference to the drawings.

Brief Description of the Drawings

[0013] The present invention will be more clearly understood upon reading the following description given by way of example only and with reference to the accompanying drawings.

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0014] Throughout the drawings, the same reference numerals relate to the same elements.

[0015] In this detailed description, the following embodiments are examples. The description refers to one or more embodiments, which does not mean that the features are applicable only to a single embodiment. The individual features of different embodiments can be combined and / or exchanged to provide other embodiments.

[0016] The tank 1 for storing a cryogenic fluid shown is intended to store, for example, hydrogen or liquid helium. This tank 1 comprises a storage shell 2 having an overall cylindrical shape extending in a longitudinal direction that is preferably horizontal when the tank 1 is in the use configuration.

[0017] As shown, the storage shell 2 preferably has a cylindrical central portion with a circular cross-section, and its two ends are closed by respective domes.

[0018] As schematically shown in [Figure 2], the tank 1 is preferably of the double-wall type, i.e., it includes an outer shell 6 arranged around a storage shell 2 having a space (e.g., under vacuum) containing a heat insulating material, such as a multilayer insulation (MLI).

[0019] The storage shell 2 is provided inside with a homogenizing device 3 for homogenizing the temperature of the fluid in the tank 1 in the vertical direction (preventing stratification). This homogenizing device comprises at least one heat transfer wall 3 made of a material having a thermal conductivity greater than 30 W·m -1 ·K -1 or consisting of the heat transfer wall 3. The heat transfer wall 3 is arranged parallel to the longitudinal direction of the tank 1, extends vertically over 20 - 100% of the height of the storage shell 2, and extends longitudinally over at least 50% of the length of the storage shell 2.

[0020] For example, the heat transfer wall 3 extends vertically over 60 - 100%, or 80 - 100%, preferably 90 - 100% of the height of the storage shell 2. Preferably, the height of the wall 3 is greater for a movable tank having an extended operating range (liquid level) between, for example, 10% and 100% of the volume. Conversely, the wall 3 may extend higher for a tank of the type where the level essentially remains between 80 - 100% of the volume.

[0021] The structure of this heat transfer wall 3 occupies all or almost all of the height of the storage shell 2, and as a result, limits stratification regardless of the liquid level therein. This wall 3 may be a single wall.

[0022] The length of the heat transfer wall 3 is preferably maximized to promote heat transfer between the relatively cold part and the relatively hot part.

[0023] For example, the length of the heat transfer wall 3 is equal to or substantially equal to the available length inside the storage shell 2. In particular, the heat transfer wall 3 may extend beyond the central cylindrical portion in order to also reach the volume located at the end of the storage shell 2 in the dome.

[0024] The material forming the heat transfer wall 3 is selected to have a high thermal conductivity at cryogenic temperatures. For example, it is aluminum, in particular grades 1050, 1350 or 6063.

[0025] The shape of the heat transfer wall 3 may be optimized to increase the exchange surface area with the fluid and / or to limit the mass of the wall 3. This optimization may include corrugations and / or perforations 5.

[0026] For example, the heat transfer wall 3 may have a corrugated shape with corrugations parallel to each other in the longitudinal or vertical direction.

[0027] These specific features (or other structural modifications) make it possible to increase the exchange surface area and / or to generate more turbulence in the fluid, especially in the vertical direction.

[0028] As shown in [Figure 3], in addition to promoting heat transfer and thus promoting temperature uniformity along the vertical axis and over a long length within the storage shell 2, the heat transfer wall 3 can form a support for installing additional equipment such as instrumentation (and / or cable wiring), lines, or mixing plates, which also facilitates integration within the tank.

[0029] As schematically shown in [Figure 4], the heat transfer wall 3 may comprise one or more fins 7 that extend transversely to the wall 3 over a transverse distance with respect to a heat transfer wall 5 that is limited, particularly preferably less than half or less than a quarter of the diameter of the storage shell 2. For example, these fins 7 do not extend more than 10 cm beyond the vertical heat transfer wall 3. The fins 7 may be provided perpendicular to all or part of the heat transfer wall 3.

Claims

1. A tank for storing a cryogenic fluid such as hydrogen or liquid helium, comprising a storage shell (2) having a cylindrical overall shape extending in a longitudinal direction that is horizontal when the tank (1) is in its operating configuration, wherein the storage shell (2) comprises, inside it, a homogenization device (3) for homogenizing the temperature of the cryogenic fluid vertically within the tank, and the homogenization device consists of at least one heat transfer wall (3) made of a material having a thermal conductivity greater than 30 W·m －１ ·K －１ and consisting of at least one heat transfer wall (3) made of a material having a thermal conductivity greater than 30 W·m·K, the heat transfer wall (3) being arranged parallel to the longitudinal direction of the tank (1), extending vertically over 20 to 100% of the height of the storage shell (2), and extending longitudinally over at least 50% of the length of the storage shell (2).

2. The heat transfer wall (3) extends vertically over 60 to 100%, for example 80 to 100%, preferably 90 to 100% of the height of the storage shell (2), and the tank according to claim 1 is characterized in that.

3. The heat transfer wall (3) extends over at least 80% of the length of the storage shell (2), and the tank according to claim 1 or 2 is characterized in that.

4. The heat transfer wall (3) is made of aluminum or a stainless alloy, and the tank according to any one of claims 1 to 3 is characterized in that.

5. The heat transfer wall (3) has a thickness of 1 mm to 8 mm, and the tank according to any one of claims 1 to 4 is characterized in that.

6. The heat transfer wall (3) has holes (5) extending in a transverse direction with respect to the heat transfer wall (3) and / or corrugations and / or at least one fin (7), and the tank according to any one of claims 1 to 5 is characterized in that.

7. The heat transfer wall (3) is a fin (7) less than half, preferably less than a quarter of the diameter of the storage shell (2) having a cylindrical overall shape, and extends in a transverse direction with respect to the heat transfer wall (3) over a transverse distance with respect to the heat transfer wall (3). The tank according to claim 6 is characterized by having one or more fins (7).

8. The heat transfer wall (3) is fixed to the storage shell (2) by welding and / or screwing and / or riveting, and the tank according to any one of claims 1 to 7 is characterized in that.

9. The tank includes a set of circuits and devices in the storage shell (2), and the heat transfer wall (3) forms a support for at least some of the circuits (4) and / or the devices. The tank according to any one of claims 1 to 8 is characterized in that.

10. The tank is of a double-wall type, that is, it includes an outer shell (6) arranged around the storage shell (2) having a space containing a heat insulating material, and the tank according to any one of claims 1 to 9 is characterized in that.

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