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] The invention relates more particularly to a storage tank for cryogenic fluid, for example 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 consisting 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, in particular 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 have significant temperature differences between their liquid and vapor phases.This results in faster pressure rises than would be observed if the two phases had similar temperatures. This phenomenon is often referred to as "stratification."

[0003] During prolonged parking, the cryogenic tank may eventually reach its maximum pressure due to this pressure increase. It may then be necessary to evacuate molecules to avoid exceeding this value. The stratification effect will amplify this disadvantage.

[0004] An object of the invention is to reduce or eliminate stratification in cryogenic tanks.

[0005] A known solution for liquid helium storage is to provide an aluminum plate placed in the upper part of the tank, the lower part of which is immersed in the liquid helium phase, which is generally close to the lower end. This solution partially addresses the problem; in particular, it is not sufficiently satisfactory for liquefied hydrogen tanks.

[0006] An aim of the present invention is to overcome all or part of the drawbacks of the prior art noted above.

[0007] To this end, the tank according to the invention, which is otherwise in accordance with 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 envelope and extends longitudinally over at least 50% of the length of the storage envelope.

[0008] Furthermore, embodiments of the invention may include one or more of the following features: 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 envelope, the transfer wall extends longitudinally over at least 80% of the length of the storage envelope, the transfer wall is made of aluminum or a stainless metal alloy, the transfer wall has a thickness of 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 transverse to the transfer wall which is less than half and preferably less than a quarter of the diameter of the generally cylindrical storage envelope, the transfer wall is fixed to the storage envelope by welding and / or screwing and / or riveting,the tank comprises a set of circuitry and equipment in the storage envelope, 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 comprises an outer envelope arranged around the storage envelope with a spacing comprising a thermal insulator.

[0009] The invention may also relate to any alternative device or method comprising any combination of the above or below characteristics within the scope of the claims. Other features and advantages will appear on reading the description below, made with reference to the figures in which: Brief description of the figures

[0010] The invention will be better understood from reading the following description, given solely by way of example and with reference to the appended drawings in which: [Fig. 1 ] is a schematic perspective and transparent view of a tank according to one 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

[0011] In all figures, the same references refer to the same elements.

[0012] 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. Single features of different embodiments may also be combined and / or interchanged to provide other embodiments.

[0013] 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 casing 2 of generally cylindrical shape extending in a longitudinal direction which is preferably horizontal in the configuration of use of the tank 1.

[0014] As illustrated, the storage envelope 2 has a cylindrical central portion, preferably of circular section and the two ends of which are closed by respective domes.

[0015] As schematized in [ Fig. 2 ], the tank 1 is preferably of the double-walled type, i.e. comprises an outer casing 6 arranged around the storage casing 2 with a spacing (for example under vacuum) comprising a thermal insulator, for example a multi-layer thermal insulation (“MLI”).

[0016] The storage envelope 2 comprises within it a device 3 for homogenizing the temperature of the fluid vertically in 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, 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 envelope 2 and extending longitudinally over at least 50% of the length of the storage envelope 2. 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 envelope 2. Preferably, the height of the wall 3 is greater for mobile tanks which 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 volume. This transfer wall structure 3 occupies all or almost all of the height of the storage envelope 2 and therefore limits stratification independently of the liquid level within it. This wall 3 may be unique.

[0017] The length of the transfer wall 3 is preferably maximized to promote heat transfer between the relatively cold and hot parts.

[0018] For example, the length of the transfer wall 3 is equal or substantially equal to the length available inside the storage envelope 2. In particular, the transfer wall 3 may extend beyond the central cylindrical part in order to also reach the volumes located at the ends of the storage envelope 2 at the domes.

[0019] 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.

[0020] The geometry of the transfer wall 3 can be optimized in order to increase its exchange surface with the fluids and / or limit the mass of the wall 3. This optimization can include a corrugation and / or perforations 5.

[0021] For example, the transfer wall 3 may have a corrugated shape, with waves parallel to each other in the longitudinal or vertical direction.

[0022] These features (or other structural modifications) make it possible to increase the exchange surface and / or create more turbulence in the fluid, particularly in the vertical direction.

[0023] 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 cabling), lines or mixing plates; also facilitating integration into the tank.

[0024] As schematized 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 transverse distance to the transfer wall 5 which is limited and in particular preferably less than half or less than a quarter of the diameter of the storage envelope 2. For example, these fins 7 do not extend beyond 10 cm relative to the vertical transfer wall 3. The fins 7 may be provided vertically on all or part of the transfer wall 3.

Claims

1. Tank for storing cryogenic fluid, for example liquefied hydrogen or helium, comprising a storage envelope (2) of generally cylindrical shape extending in a longitudinal direction which is horizontal in the configuration of use of the tank (1), the storage envelope (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 envelope (2) and extending longitudinally over at least 50% of the length of the storage envelope (2).

2. Tank according to claim 1, characterized in thatthe 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 envelope (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 envelope (2).

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

6. 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. 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 transverse distance to the transfer wall (5) which is less than half and preferably less than a quarter of the diameter of the storage envelope (2) of generally cylindrical shape.

8. Tank 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 envelope (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 thatit is of the double-walled type, that is to say it comprises an outer casing (6) arranged around the storage casing (2) with a spacing comprising thermal insulation.

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