Cryogenic fluid storage tank

Abstract

The invention relates to a cryogenic fluid storage tank, for example, for liquefied hydrogen or helium, comprising a generally cylindrical storage casing (2) extending along a longitudinal direction that is horizontal in the operating configuration of the tank (1). The storage casing (2) includes within it a device (3) for homogenizing the temperature of the fluid vertically within the tank (1). The homogenization device 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. Said 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 casing (2) and longitudinally for at least 50% of the length of the storage casing (2). (Short figure: Fig. 1)

Description

Title of the invention: Cryogenic fluid storage tank

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

[0002] The invention relates more particularly to a cryogenic fluid storage tank, for example of liquefied hydrogen or helium, comprising a storage envelope of generally cylindrical shape extending in a longitudinal direction which is horizontal in the configuration of use of the tank, the storage envelope comprising within it a device for homogenizing the temperature of the fluid vertically in the tank, the homogenizing device being made up of at least one heat transfer wall made of a material with a coefficient of thermal conductivity greater than 30 W. nr'.K-1.

[0003] 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 pressure increases that are more rapid than would be observed if the two phases had similar temperatures. This phenomenon is often called "stratification".

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

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

[0006] A known solution for liquid helium storage consists of providing an aluminum plate disposed in the upper part of the tank and whose lower part is immersed in the liquid helium phase which is generally close to the upper end.

[0007] This solution partially addresses the problem, in particular it is not sufficiently satisfactory for liquefied hydrogen tanks.

[0008] One object of the present invention is to overcome all or part of the disadvantages of the prior art noted above.

[0009] To this end, the tank according to the invention, which otherwise 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 extends vertically over 20 to 100% of the height of the storage casing and extends longitudinally over at least 50% of the length of

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[0017] the storage container. 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 aluminium or a stainless metal alloy, - the transfer wall has a thickness between 1mm and 8mm, - the transfer wall has holes and / or corrugations and / or at least a 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 transverse to the transfer wall which is less than half and preferably less than a 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 enclosure, the transfer wall forming a support for at least part of the circuitry and / or equipment, - the tank is of the double-walled type, that is to say it includes an outer casing arranged around the storage casing with a spacing including thermal insulation. 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 upon reading the description below, which refers to the figures in which: Brief description of the figures The invention will be better understood upon reading the following description, given solely by way of example and made with reference to the attached drawings in which: [Fig. 1] is a schematic perspective and transparent view of a reservoir according to one embodiment of the invention, [Fig.2] is a schematic cross-sectional view of the tank in [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,

[0018] [Fig.4] is a schematic cross-sectional view of another embodiment of the tank according to the invention. Detailed description

[0019] In all figures, the same references refer to the same elements.

[0020] In this detailed description, the following are examples. Well The fact that the description refers to one or more embodiments 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.

[0021] The illustrated cryogenic fluid storage tank 1 is, for example, intended for the storage of liquefied hydrogen or helium. This tank 1 comprises a storage shell 2 of generally cylindrical shape extending in a longitudinal direction which is preferably horizontal in the configuration of use of the tank 1.

[0022] 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.

[0023] As schematically shown in [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 (for example under vacuum) comprising thermal insulation, for example multilayer thermal insulation (“MLI”).

[0024] The storage casing 2 includes within it a device 3 for homogenizing the temperature of the fluid vertically in the reservoir 1 (anti-stratification). This homogenization device comprises or is made up of at least one heat transfer wall 3 made of a material with a thermal conductivity coefficient greater than 30 W.ml.K-1, said heat transfer wall 3 being arranged parallel to the longitudinal direction of the reservoir 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.

[0025] For example, the transfer wall 3 extends vertically over 60 to 100% or 80 to 100%, and preferably 90 to 100%, of the height of the storage enclosure 2. Preferably, the height of the wall 3 is greater for mobile tanks that have a wide operating range (liquid level), for example, between 10% and 100% of the volume. Conversely, the wall 3 may extend to a lesser height, for example, in the upper part, when the tank is of the type in which the level remains essentially between 80 and 100% of the volume.

[0026] This transfer wall structure 3 occupies all or almost all of the height of the storage enclosure 2 and therefore limits stratification independently of the liquid level within it. This wall 3 must be unique.

[0027] The length of the transfer wall 3 is preferably maximized to promote heat transfer between relatively cold and hot parts.

[0028] 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 in order to also reach the volumes located at the ends of the storage enclosure 2 at the domes.

[0029] The material constituting the transfer wall 3 is chosen so as to have high thermal conductivity at cryogenic temperatures. For example, aluminum, in particular grades 1050, 1350 or 6063.

[0030] The geometry of the transfer wall 3 can be optimized to increase its exchange surface with the fluids and / or limit the mass of the wall 3. This optimization may include a corrugation and / or perforations 5.

[0031] For example, the transfer wall 3 may have a corrugated shape, with waves parallel to each other in the longitudinal or vertical direction.

[0032] 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.

[0033] As illustrated in [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.

[0034] As schematically illustrated in [Fig. 4], the 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, and in particular 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

Demands

1. Cryogenic fluid storage tank, for example of liquefied hydrogen or helium, comprising a storage shell (2) of generally cylindrical shape extending in a longitudinal direction which is horizontal in the configuration of use of the tank (1), the storage shell (2) comprising within it a device (3) for homogenizing the temperature of the fluid vertically in the tank (1), the homogenizing device being made of at least one heat transfer wall (3) made of a material having a thermal conductivity coefficient greater than 30 W. m-'.K-1, said heat 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).

2. 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. 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 shell (2).

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

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

6. Reservoir 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. Tank according to claim 6, characterized in that the transfer wall (3) has one or more fins (7) extending transversely relative to the wall (3) over a distance transverse to the transfer wall (5) which is less than half and preferably less than one quarter of the diameter of the generally cylindrical storage shell (2).

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

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

10. Tank according to any one of claims 1 to 9, characterized in that it is of the double-walled type, i.e. comprises an outer casing (6) arranged around the storage casing (2) with a spacing comprising thermal insulation.

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