Tank for storing cryogenic fluid

Abstract

The invention relates to a storage tank for storing a cryogenic fluid, such as hydrogen or liquid helium, comprising a storage housing (2) having a substantially cylindrical shape extending in a longitudinal direction which is horizontal when the storage tank (1) is in a use configuration, according to the invention, the storage housing (2) comprises, inside it, homogenizing means (3) for vertically homogenizing the temperature of the fluid in the storage tank (1), said homogenizing means comprising at least one heat transfer wall (3) made of a material having a thermal conductivity greater than 30 W * m <-1 > * K <-1 >, said heat transfer wall being made of a material having a thermal conductivity greater than 30 W * m <-1 > * K <-1 >. The heat transfer wall (3) is arranged parallel to the longitudinal direction of the tank (1) and extends vertically by 20% to 100% of the height of the storage housing (2) and longitudinally by at least 50% of the length of the storage housing (2).

Description

Field of the Invention

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

[0002] More particularly, the present invention relates to a storage tank for storing cryogenic fluids such as hydrogen or liquid helium. The storage tank includes a storage shell having a generally cylindrical shape extending in a longitudinal direction, which is horizontal when the storage tank is in a use configuration. The storage shell includes inside thereof a homogenizing device for homogenizing the temperature of the fluid in the storage tank in the vertical direction. The homogenizing device includes at least one heat transfer wall made of a material having a thermal conductivity greater than 30 W·m -1 ·K -1 -1. Background Art

[0003] Cryogenic storage tanks, especially those containing fluids such as helium or hydrogen that have a very low specific enthalpy of vaporization and a significant density difference between the liquid and vapor phases, tend to have a significant temperature difference between their liquid and vapor phases. This results in a pressure increase that is faster than that observed when the two phases have similar temperatures. This phenomenon is generally referred to as "stratification".

[0004] During long periods of parking / standstill, due to this pressure increase, the cryogenic storage tank may eventually reach its maximum pressure. Then it may be necessary to remove molecules to avoid exceeding this value. The stratification effect amplifies this drawback.

[0005] The object of this invention is to reduce or eliminate stratification in cryogenic storage tanks.

[0006] A known solution for a liquid helium storage tank consists in providing aluminum plates that are arranged in the upper part of the storage tank, and the lower part of the storage tank is immersed in the liquid helium phase, usually near the lower end.

[0007] This solution partially solves the problem, but it is not entirely satisfactory, especially for liquid hydrogen storage tanks. Summary of the Invention

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

[0009] To this end, the basic feature of the storage tank according to the present invention, which is otherwise consistent with its general definition given in the above preamble, is that the heat transfer wall is arranged parallel to the longitudinal direction of the storage tank and extends vertically over 20% to 100% of the height of the storage shell and 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:

[0011] - 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 housing;

[0012] - The heat transfer wall extends longitudinally over at least 80% of the length of the storage housing;

[0013] - The heat transfer wall is made of aluminum or a stainless steel alloy;

[0014] - The thickness of the heat transfer wall is in the range of 1 mm to 8 mm;

[0015] - The heat transfer wall has at least one fin and / or (multiple) holes and / or (multiple) corrugations extending transversely to the heat transfer wall;

[0016] - The heat transfer wall has one or more fins extending transversely to the heat transfer wall, and the distance by which the one or more fins extend transversely to the heat transfer wall is less than half, preferably less than a quarter, of the diameter of the storage housing having a substantially cylindrical shape;

[0017] - The heat transfer wall is fastened to the storage housing by welding and / or threaded connection and / or riveting;

[0018] - The storage tank includes a set of circuits and devices in the storage housing, and the heat transfer wall is formed as a support for at least some of the circuits and / or devices in the set of circuits and devices;

[0019] - The storage tank is a double-walled storage tank, that is, it includes an outer housing arranged around the storage housing, and there is a space including a heat insulation structure between the storage housing and the outer housing.

[0020] The present invention may also relate to any alternative device or method including any combination of the above or following features falling within the scope of the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Further specific features and advantages will become apparent by reading the following description with reference to the drawings.

[0022] The present invention will be better understood by reading the following description, which is given only by way of example and with reference to the drawings, wherein:

[0023] Figure 1 is a perspective and transparent schematic view of a storage tank according to an embodiment of the present invention;

[0024] Figure 2 is Figure 1 a cross-sectional schematic view of the storage tank;

[0025] Figure 3 Is a schematic side view of another example of a heat transfer wall in a storage tank according to the present invention;

[0026] Figure 4 Is a cross-sectional schematic view of another embodiment of a storage tank according to the present invention. Detailed Description

[0027] In all the figures, the same reference numerals refer to the same elements.

[0028] In this detailed description, the following embodiments are examples. Although the description refers to one or more embodiments, this does not mean that these features are only applicable to a single embodiment. The various features of different embodiments can also be combined and / or interchanged to provide other embodiments.

[0029] The storage tank 1 shown for storing cryogenic fluids is intended to store, for example, hydrogen or liquid helium. The storage tank 1 includes a storage housing 2 having a generally cylindrical shape extending in a longitudinal direction which is preferably horizontal when the storage tank 1 is in the use configuration.

[0030] As shown, the storage housing 2 has a cylindrical central portion which preferably has a circular cross-section and whose ends are closed by respective domes.

[0031] As Figure 2 Schematically shown in, the storage tank 1 is preferably a double-walled storage tank, i.e., it includes an outer housing 6 arranged around the storage housing 2, with a space (e.g., under vacuum) including an insulating structure therebetween, the insulating structure being, for example, a multi-layer insulating structure (MLI).

[0032] The storage housing 2 includes inside it a homogenizing device 3 for homogenizing the temperature of the fluid in the storage tank 1 in the vertical direction (preventing stratification). The homogenizing device includes at least one heat transfer wall 3 or is constituted by at least one heat transfer wall 3, the at least one heat transfer wall being made of a material having a thermal conductivity greater than 30 W·m -1 ·K -1 And is arranged parallel to the longitudinal direction of the storage tank 1 and extends vertically over 20% to 100% of the height of the storage housing 2 and longitudinally over at least 50% of the length of the storage housing 2.

[0033] For example, the heat transfer wall 3 extends vertically over 60% to 100%, or 80% to 100%, preferably 90% to 100% of the height of the storage housing 2. Preferably, for such a movable storage tank, the height of the wall 3 is relatively large, i.e., the movable storage tank has an extended / wider operating range (liquid level), for example, within the range of 10% to 100% of the volume / capacity. Conversely, when the storage tank is of the type in which the liquid level remains substantially within the range of 80% to 100% of the capacity, the wall 3 can extend at a relatively small height, and for example, the wall 3 can extend in the upper part.

[0034] The structure of the heat transfer wall 3 occupies all or almost all of the height of the storage housing 2, thus restricting stratification, regardless of the liquid level in the storage housing 2. The heat transfer wall 3 can be a single wall.

[0035] The length of the heat transfer wall 3 is preferably maximized in order to facilitate heat transfer between the relatively cold and relatively hot parts.

[0036] For example, the length of the heat transfer wall 3 is equal to or substantially equal to the available length inside the storage housing 2. In particular, the heat transfer wall 3 can extend beyond the cylindrical central part in order to also reach the volume at the end of the storage housing 2 at the dome.

[0037] The material constituting the heat transfer wall 3 is selected to have high thermal conductivity at low temperatures. For example, aluminum, especially grades 1050, 1350 or 6063 of aluminum.

[0038] The geometry of the heat transfer wall 3 can be optimized in order to increase its exchange surface area with the fluid and / or to limit the mass of the wall 3. Such optimization can include corrugations and / or perforations 5.

[0039] For example, the heat transfer wall 3 can have a corrugated / wavy shape, where these corrugations are parallel to each other in the longitudinal direction or the vertical direction.

[0040] These special features (or other structural improvements) make it possible to increase the exchange surface area and / or to generate more turbulence in the fluid, especially in the vertical direction.

[0041] As Figure 3 shown, in addition to promoting heat transfer and thus promoting temperature uniformity along the vertical axis and over a large length in the storage housing 2, the heat transfer wall 3 can also be formed as a support, enabling the installation of additional devices, such as instruments (and / or wires / cables), pipelines or mixing plates; this also facilitates integration in the storage tank.

[0042] As Figure 4As schematically shown, the heat transfer wall 3 may be fitted with one or more fins 7 extending transversely with respect to the wall 3. The fins 7 extend transversely to the heat transfer wall 3 by a distance which is limited and particularly preferably less than half of the diameter of the storage housing 2 or less than a quarter of the diameter of the storage housing 2. For example, the amount by which these fins 7 extend beyond the vertical heat transfer wall 3 does not exceed 10 cm. The fins 7 may be provided vertically on all or part of the heat transfer wall 3.

Claims

1. A storage tank for storing cryogenic fluids, such as hydrogen or liquid helium, the storage tank comprising a storage housing (2) having a generally cylindrical shape extending in a longitudinal direction, which is horizontal when the storage tank (1) is in a use configuration, the storage housing (2) including inside thereof a homogenizing device (3) for homogenizing the temperature of the fluid in the storage tank (1) in the vertical direction, the homogenizing device including at least one heat transfer wall (3), the at least one heat transfer wall being made of a material having a thermal conductivity greater than 30 W·m -1 ·K -1 and being arranged parallel to the longitudinal direction of the storage tank (1) and extending vertically over 20% to 100% of the height of the storage housing (2) and longitudinally over at least 50% of the length of the storage housing (2).

2. The storage tank according to claim 1, characterized in that, 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 housing (2).

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

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

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

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

7. The storage tank according to claim 6, characterized in that, The heat transfer wall (3) has one or more fins (7) extending transversely with respect to the heat transfer wall (3), and the distance by which the one or more fins extend transversely to the heat transfer wall (3) is less than half, preferably less than a quarter, of the diameter of the storage housing (2) having a substantially cylindrical shape.

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

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

10. The storage tank according to any one of claims 1 to 9, characterized in that, The storage tank is a double-walled storage tank, i.e., the storage tank includes an outer housing (6) arranged around the storage housing (2), and there is a space including a heat insulation structure between the storage housing and the outer housing.

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