Cryogenic fluid storage tank

Abstract

The invention relates to a storage tank for cryogenic fluid, for example liquefied hydrogen or helium, comprising a storage casing (2) of generally cylindrical shape extending in a longitudinal direction which is horizontal in the configuration of use of the tank (1), the storage casing (2) comprising within it a device (3) for homogenizing the temperature of the fluid vertically in the tank (1), the homogenizing device consisting of at least one heat transfer wall (3) made of a material with a thermal conductivity coefficient 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 casing (2) and extending longitudinally over at least 50% of the length of the storage casing (2).

Description

[0001] The invention relates to a cryogenic fluid storage tank.

[0002] One such tank is known from FR3122717A1.

[0003] The invention relates more particularly to a cryogenic fluid storage tank, for example, for liquefied hydrogen or helium, comprising a generally cylindrical storage shell extending longitudinally, which is horizontal in the tank's operating configuration. The storage shell includes a device for homogenizing the fluid temperature vertically within the tank. The homogenization device consists of at least one heat transfer wall made of a material with a thermal conductivity coefficient greater than 30 W·m⁻¹·K⁻¹. Cryogenic tanks, particularly those containing fluids with very low specific enthalpies of vaporization and significant density differences between the liquid and vapor phases, such as helium or hydrogen, tend to exhibit large temperature differences between their liquid and vapor phases.This results in faster pressure increases than would be observed if the two phases had similar temperatures. This phenomenon is often called "stratification".

[0004] During prolonged storage, the cryogenic tank can eventually reach its maximum pressure due to this pressure buildup. It may then be necessary to vent molecules to prevent exceeding this value. The stratification effect will amplify this drawback.

[0005] One aim of the invention is to reduce or eliminate stratification in cryogenic tanks.

[0006] A known solution for liquid helium storage involves placing an aluminum plate in the upper part of the tank, with its lower part immersed in the liquid helium phase, which is generally located near the bottom. This solution only partially addresses the problem; in particular, it is not sufficiently satisfactory for liquefied hydrogen tanks.

[0007] One aim of the present invention is to overcome all or part of the disadvantages of the prior art noted above.

[0008] To this end, the tank according to the invention, which also conforms to the generic definition given in the preamble above, is essentially characterized in that the transfer wall is arranged parallel to the longitudinal direction of the tank and extending vertically over 20 to 100% of the height of the storage envelope and extending longitudinally over at least 50% of the length of the storage envelope.

[0009] Furthermore, embodiments of the invention may include one or more of the following characteristics: The transfer wall extends vertically over 60 to 100%, for example 80 to 100% and preferably 90 to 100% of the height of the storage enclosure; the transfer wall extends longitudinally over at least 80% of the length of the storage enclosure; the transfer wall is made of aluminum or a stainless metal alloy; the transfer wall has a thickness between 1 mm and 8 mm; the transfer wall has holes and / or corrugations and / or at least one fin extending transversely relative to the transfer wall; the transfer wall has one or more fins extending transversely relative to the wall over a distance across the transfer wall that is less than half and preferably less than one quarter of the diameter of the generally cylindrical storage enclosure; the transfer wall is fixed to the storage enclosure by welding and / or screwing and / or riveting.The tank includes a set of circuitry and equipment within the storage casing; the transfer wall forms a support for at least part of the circuitry and / or equipment. The tank is of the double-walled type, i.e., it includes an outer casing arranged around the storage casing with a gap that includes thermal insulation.

[0010] The 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. Other features and advantages will become apparent from the following description, given with reference to the figures in which: Brief description of the figures

[0011] The invention will be better understood upon reading the following description, given solely by way of example and made with reference to the accompanying drawings in which: [Fig. 1 ] is a schematic perspective and transparent view of a reservoir according to an embodiment of the invention, [ Fig. 2 ] is a schematic cross-sectional view of the reservoir of the [ Fig. 1 ], [ Fig. 3 ] is a schematic side view of another example of a transfer wall that can be used in a tank according to the invention, [ Fig. 4 ] is a schematic cross-sectional view of another embodiment of the tank according to the invention. Description détaillée

[0012] In all the figures, the same references refer to the same elements.

[0013] In this detailed description, the following embodiments are examples. Although the description refers to one or more embodiments, this does not mean that the features apply only to a single embodiment. Simple features from different embodiments can also be combined and / or interchanged to provide other embodiments.

[0014] The cryogenic fluid storage tank 1 shown is, for example, designed for the storage of liquefied hydrogen or helium. This tank 1 comprises a storage shell 2, generally cylindrical in shape, extending in a longitudinal direction that is preferably horizontal in the tank 1's operating configuration.

[0015] As illustrated, the storage envelope 2 has a central cylindrical portion, preferably of circular cross-section, and whose two ends are closed by respective domes.

[0016] As schematically shown in the [ Fig. 2 ], the tank 1 is preferably of the double-walled type, i.e. includes an outer jacket 6 arranged around the storage jacket 2 with a spacing (e.g. under vacuum) comprising thermal insulation, e.g. multilayer thermal insulation (“MLI”).

[0017] The storage tank 2 includes a device 3 for vertically homogenizing the temperature of the fluid within the tank 1 (anti-stratification). This homogenization device comprises, or consists of, at least one heat transfer wall 3 made of a material with a thermal conductivity coefficient greater than 30 W.m⁻¹.K⁻¹. This heat transfer wall 3 is arranged parallel to the longitudinal direction of the tank 1 and extends vertically for 20 to 100% of the height of the storage tank 2 and longitudinally for at least 50% of the length of the storage tank 2. For example, the heat transfer wall 3 extends vertically for 60 to 100% or 80 to 100%, and preferably 90 to 100%, of the height of the storage tank 2. Preferably, the height of wall 3 is greater for mobile tanks which have an extended operating range (liquid level), for example between 10% and 100% of the volume.Conversely, wall 3 can extend to a lesser height, for example, in the upper part of a tank where the level remains essentially between 80 and 100% of its volume. This transfer wall 3 structure occupies all or almost all of the height of the storage shell 2 and therefore limits stratification regardless of the liquid level within it. This wall 3 may be a single unit.

[0018] The length of the transfer wall 3 is preferably maximized to promote heat transfer between relatively cold and hot parts.

[0019] For example, the length of the transfer wall 3 is equal to or substantially equal to the available length inside the storage enclosure 2. In particular, the transfer wall 3 can extend beyond the central cylindrical section to also reach the volumes located at the ends of the storage enclosure 2 at the domes.

[0020] The material constituting the transfer wall 3 is chosen to have high thermal conductivity at cryogenic temperatures. For example, aluminum, particularly grades 1050, 1350 or 6063.

[0021] The geometry of the transfer wall 3 can be optimized to increase its exchange surface area with fluids and / or limit the mass of the wall 3. This optimization may include a corrugation and / or perforations 5.

[0022] For example, the transfer wall 3 may have a corrugated shape, with waves parallel to each other in the longitudinal or vertical direction.

[0023] These features (or other structural modifications) make it possible to increase the exchange surface area and / or create more turbulence in the fluid, particularly in the vertical direction.

[0024] As illustrated in the [ Fig. 3 In addition to promoting heat transfer and therefore temperature uniformity along the vertical axis and over a long length in the storage envelope 2, the transfer wall 3 can form a support allowing the installation of additional equipment such as instrumentation (and / or wiring), lines or mixing plates; also facilitating integration into the tank.

[0025] As schematically shown in the [ Fig. 4The transfer wall 3 may be provided with one or more fins 7 extending transversely relative to the wall 3 over a limited transverse distance to the transfer wall 5, preferably less than half or less than one-quarter of the diameter of the storage enclosure 2. For example, these fins 7 do not extend beyond 10 cm from the vertical transfer wall 3. The fins 7 may be provided vertically along all or part of the transfer wall 3.

Claims

1. A cryogenic fluid storage tank, for example for liquefied hydrogen or helium, comprising a storage enclosure (2) of generally cylindrical shape extending along a longitudinal direction which is horizontal in the configuration of use of the tank (1), the storage enclosure (2) comprising therein a device (3) for homogenizing the temperature of the fluid vertically in the tank (1), the homogenization device being constituted by at least one heat transfer wall (3) made of a material having a thermal conductivity coefficient greater than 30 W. m-1.K-1, said transfer wall (3) being disposed parallel to the longitudinal direction of the tank (1) and extending vertically over 20 to 100% of the height of the storage enclosure (2) and extending longitudinally over at least 50% of the length of the storage enclosure (2).

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

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

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

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

6. The tank according to any one of claims 1 to 5, characterized in that the transfer wall (3) has holes (5) and / or corrugations and / or at least one fin (7) extending transversely relative to the transfer wall (3).

7. The tank according to claim 6, characterized in that the transfer wall (3) has one or more fin(s) (7) extending transversely relative to the wall (3) over a distance transversal to the transfer wall (5) which is less than half and preferably less than one quarter of the diameter of the generally cylindrical storage enclosure (2).

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

9. The tank according to any one of claims 1 to 8, characterized in that it comprises an assembly of circuitry and equipment within the storage enclosure (2), the transfer wall (3) forming a support for at least a part of the circuitry (4) and / or equipment.

10. The tank according to any one of claims 1 to 9, characterized in that it is of the double-walled type, that is to say, it comprises an outer enclosure (6) disposed around the storage enclosure (2) with a space comprising thermal insulation.

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