Liquefied gas storage tank

Abstract

A tank for storing liquefied gases, particularly liquefied hydrogen, is disclosed. The tank includes a shell (2) defining a storage volume extending in a main direction (A), which is horizontal in the use configuration of the tank (1). The tank (1) includes at least one deflecting wall (3) in the storage volume. The tank is characterized in that it includes a plurality of deflecting walls (3) in the storage space, which extend offset in the main direction (A) to force fluid to make at least one round trip in the longitudinal direction (A) as it passes between the lower and upper ends of the storage space (2).

Description

[0001] The present invention relates to a tank for storing liquefied gases, particularly liquefied hydrogen.

[0002] More specifically, the present invention relates to a tank for storing liquefied gases, particularly liquefied hydrogen, the tank comprising a shell defining a storage volume extending in a main direction, which is horizontal in the configuration of use of the tank, the tank including at least one deflecting wall in the storage volume.

[0003] When large quantities of hydrogen products must be stored or transported over long distances, it is preferable that the hydrogen be in liquid form. Another advantage of liquid hydrogen is that at a temperature of 20K, virtually all impurities from the gas are eliminated (these impurities are solid at this temperature), thus optimizing the operation of fuel cells using liquid hydrogen.

[0004] In contrast, the liquid has a lower density than water, which, for example, limits the amount of pressure obtainable through the hydrostatic head, and the low temperature can result in considerable evaporation losses during transfer. Losses that could occur in systems used to unload trucks and tanks at hydrogen supply stations could be as high as 15% of production.

[0005] Of course, these truck pressurization losses can be wasted at each station or recovered, reheated, recompressed, and re-injected into the liquefaction unit. But this requires investment in loss recycling systems and scaling up the liquefaction system.

[0006] The transport of supercooled liquids requires precautions to prevent the pressure in the tank from dropping below atmospheric pressure. This could pose a danger to the mechanical strength of the tank or to the possibility of air entering the fluid being transported.

[0007] The truck from the liquefier must be pressurized in order to unload liquid hydrogen from the truck into a storage tank at the station (this storage tank is typically kept pressurized to ensure the operation of the liquid pumps or to enable the supply of hydrogen in a pressurized state). This pressurization is accomplished by vaporizing and reheating (PBU) the hydrogen from the truck. Thus, energy is introduced into the truck.

[0008] Once a certain amount of liquid has been transferred to the user, the truck can continue supplying another station or return to the liquefier for resupply. Truck movement causes a pressure drop due to the movement of liquid within the storage volume and its contact with the gas phase. On the other hand, the resulting pressure will always be greater than the initial pressure due to the addition of energy to the system.

[0009] Ultimately, the amount of hydrogen charged by trucks and the necessary pressure for these stations will determine the amount wasted or to be reliquefied in liquefiers after the round trip.

[0010] When pressure is released from a cryogenic liquid reservoir to another device, several different scenarios can occur. In this case, if the liquid and vapor are in equilibrium, the pressure reduction inside the reservoir causes the liquid to evaporate (bubbles appear in the liquid). This evaporation tends to homogenize the temperature of the liquid (non-stratification). The mass of liquid to be extracted from the reservoir to reduce pressure is directly related to the temperature of the vapor leaving the reservoir (the lower the vapor temperature, the higher the density, and the greater the mass to be extracted for the same pressure change).

[0011] When a cryogenic liquid storage container is pressurized by introducing heat or by transferring it from another container, several different scenarios can occur. In this regard, the more vapor stratifies above the liquid, the faster the pressure inside the container rises (as the vapor density decreases with increasing temperature). For the same pressure increase, a larger mass of cold vapor (at equilibrium temperature) must be injected compared to the mass of “hot” vapor in terms of gas density.

[0012] When filling a cryogenic liquid reservoir with liquid from another tank, several different scenarios can occur. In this regard, when filling from the bottom of the reservoir without removing vapor from the top, the more vapor stratification occurs above the liquid, the faster the pressure rises. When filling the reservoir from the top (falling), the lower the temperature of the liquid is compared to the vapor present in the reservoir, the greater the pressure drop.

[0013] Discharging a cryogenic liquid reservoir can lead to several different outcomes. In this respect, when the reservoir is discharged without adding vapor to the top, the more the liquid deviates from equilibrium (supercooling), the faster the pressure drops; otherwise, evaporation occurs, as in depressurization conditions.

[0014] When discharging from the reservoir by adding steam to the top, the further the steam temperature deviates from equilibrium, the greater the decrease in the quality of the steam to be added.

[0015] In summary, the ideal configuration of vapor (gas phase) and liquid in the tank can be varied for each operation (depressurization, filling, etc.) and can be summarized as follows.

[0016] Pressure reduction: stratified vapor, subcooled liquid.

[0017] Filling: stratified vapor, subcooled liquid.

[0018] Storage / transportation when full: non-stratified vapor, supercooled liquid.

[0019] Partially filled / empty storage / transport: stratified vapor, supercooled liquid.

[0020] Pressurization: stratified vapor, subcooled liquid.

[0021] Emissions: stratified vapor, subcooled liquid.

[0022] Therefore, only full-capacity storage and / or transport require equilibrium (no stratification) in the vapor phase to avoid a significant increase in vapor pressure within the small volume. Thus, liquid stratification and subcooling are preferred in terms of equilibrium temperature at the pressure within the storage vessel.

[0023] The purpose of this invention is to overcome all or some of the defects of the prior art mentioned above.

[0024] Therefore, a substantial feature of the tank according to the invention and also according to the general definition given in the preceding preamble is that the tank includes a plurality of deflecting walls in the storage volume, which extend in an offset manner in the main direction to force the fluid to make at least one round trip in the main direction as it passes between the lower and upper ends of the storage volume.

[0025] This structure allows the temperature of the stratified subcooled liquid to be maintained despite the possible movement of the liquid caused by transport, natural convection, or filling / draining operations.

[0026] Furthermore, embodiments of the present invention may have one or more of the following features:

[0027] - The deflection wall extends from one end of the shell along the main direction over a portion of the storage volume.

[0028] - The deflecting walls in the configuration of the can are horizontal or substantially horizontal.

[0029] - The deflection wall extends horizontally across the entire cross-section of the storage volume.

[0030] - Jars with an odd number of deflecting walls, especially three deflecting walls

[0031] - The can has a filling and / or extraction port located in the lower portion of a longitudinal end of the shell.

[0032] - The can has a filling and / or extraction port located in the upper part of a longitudinal end of the shell.

[0033] - The tank has a fluid filling or extraction port located at a longitudinal end and at an intermediate height between the upper and lower portions of the storage volume.

[0034] -The can has a deflecting wall pierced by multiple orifices.

[0035] - The can has a deflecting wall pierced by multiple orifices, for example, multiple orifices piercing only a portion of the surface of the deflecting wall.

[0036] - The deflection wall located in the upper part of the storage volume is pierced by multiple orifices.

[0037] - At least some of the deflection walls are made of a flexible material, which is lighter than the material used to manufacture the shell.

[0038] The present invention may also relate to any alternative apparatus or method that includes any combination of the features described above or below within the scope of the claims.

[0039] Further specific features and advantages will become apparent from the following description, with reference to the accompanying drawings:

[0040] [ Figure 1 A schematic partial vertical cross-sectional view is shown, illustrating a first exemplary embodiment of the tank according to the present invention.

[0041] [ Figure 2 A schematic partial vertical cross-sectional view is shown, illustrating a second exemplary embodiment of the tank according to the present invention.

[0042] [ Figure 3 A schematic partial vertical cross-sectional view is shown, illustrating a third exemplary embodiment of the tank according to the present invention.

[0043] The tank 1 shown schematically is configured to store liquefied gases, particularly liquefied hydrogen.

[0044] The tank includes, for example, a shell 2 having an integral cylindrical shape, which defines a storage volume extending in a main direction A. For example, the main direction A is the longitudinal direction of the tank. The generatrix of the cylindrical portion may be parallel to the main direction A or an axis. The main direction A may be horizontal in the configuration of use of the tank 1. That is, the tank 1 may be a "horizontal" or "vertical" or spherical type tank (in the latter case, the main direction A may be horizontal) or have any other suitable form.

[0045] In the schematic representation, only the shell 2 is shown. Of course, the tank 1 can be a double-walled type, having walls surrounding the shell 2, thus forming an insulated space under vacuum.

[0046] Tank 1 includes multiple horizontal deflecting walls 3 within a storage volume, which extend in an offset manner in the main direction A. These deflecting walls 3 are arranged to force the fluid to make at least one round trip in the main direction A as it passes between the lower and upper ends of the storage volume 2.

[0047] In the example shown, three deflection walls are set. Of course, two or more than three walls can be set.

[0048] The deflection wall 3 extends from one longitudinal end of the housing 2 along a portion of the storage volume. For example, the deflection wall 3 is successively and alternately connected to one longitudinal end of the housing 2 and then to the other longitudinal end in the vertical direction.

[0049] In the case of three deflecting walls 3, as shown, this creates three turns, thereby forcing the fluid to change direction three times in the longitudinal direction so as to flow from the top of the tank to the bottom (or vice versa).

[0050] The deflection wall 3 preferably extends horizontally over the entire cross section of the storage volume and is connected to the housing on its lateral periphery (except at the end referred to as the free end, which forms a vertical channel for fluid).

[0051] These deflection walls 3 restrict the contact or transfer of liquid at the bottom of the storage volume with liquid or vapor at the top of the storage volume.

[0052] This allows the stratified subcooled liquid to be kept at the bottom of the storage volume. Depending on the charge height, the vapor can also be stratified or not, depending on the desired benefits.

[0053] like[ Figure 2 ]and[ Figure 3 As shown, the tank may have a lower portion located at one longitudinal end of the shell 2 and connected to a filling or extraction port 4 of a pipe.

[0054] Similarly, the tank may have an upper portion located at one longitudinal end of the shell 2 and connected to a filling or extraction port 5 for the pipeline.

[0055] When filling from the bottom, the cold liquid arriving through orifice 4 must flow through the length of the storage volume before it can rise to the next height, and so on.

[0056] If the wall temperature of housing 2 is too high, the liquid will be reheated and partially evaporate. However, the vapor or the liquid nearing equilibrium is forced toward the top of the storage volume by the horizontal deflection wall without interacting with the cold liquid arriving via the supply.

[0057] The vapor leaving the reservoir is reheated after it comes into contact with the hot wall (which is cooled) as it rises in the reservoir.

[0058] When the storage volume is full, the liquid is kept in stratification by deflection walls, and vapor stratification caused by movement (for transport) or by extracting vapor from stationary storage containers can be limited.

[0059] This solution also allows for the advantageous replacement, where appropriate, of the "anti-sloshing" walls traditionally installed in movable tanks to prevent liquid sloshing. This is because, by limiting the mass of liquid that may begin to move through the deflecting wall 3, the liquid sloshing effect during sudden movement is automatically reduced.

[0060] like[ Figure 2 ]or[ Figure 3 As shown in the figure, fluid, preferably along with vapor, can be refluxed into the storage volume via an orifice 6 located at an intermediate height between the upper and lower portions of the storage volume.

[0061] The intermediate orifice 6 can be connected to a pipe and can be located between two deflecting walls 3 so that the fluid and part of the vapor can pass through the liquid to condense it, while still keeping some of the supercooled liquid in the lower part.

[0062] Additionally or alternatively, such as [ Figure 3 As shown, the final (upper) deflection wall 3 can have a perforated structure (multiple holes) to allow gas to pass through and increase the contact area between the gas and the liquid.

[0063] This option can also be advantageously used in situations where the storage volume is filled from the top to increase the exchange area between the incoming (falling) liquid and the present gas. This makes it possible to avoid having to install an "injector" type liquid dispenser along the length of the tank.

[0064] Additionally or alternatively, the deflecting walls 3 may be made of a lightweight, flexible material (e.g., lighter than the rest of the can) that retains its mechanical properties at low temperatures in order to limit the additional mass of these deflecting walls 3 within the can (see, for example, FR 2966899 A). This is because, for cans used for transport, the mass of the can limits the maximum amount of product that can be transported.

[0065] According to the invention, the tank, since the deflecting wall is at least partially immersed in the liquid phase, allows for the maintenance of liquid stratification while still maintaining liquid-gas phase equilibrium at the interface with the gas phase (typically at pressures above atmospheric pressure). This makes it possible to retain the subcooled layer of liquid in the lower portion of the tank. This is particularly advantageous for tanks used for transport, especially for transporting subcooled liquids.

Claims

1. A tank for storing liquefied gas, the tank comprising a shell (2) having an integral cylindrical shape defining a storage volume extending in a main longitudinal direction (A), wherein the generatrix of the cylindrical portion is parallel to the main longitudinal direction (A), the main longitudinal direction being horizontal in the usage configuration of the tank (1), the tank (1) comprising a plurality of deflecting walls (3) in the storage volume, the deflecting walls extending in an offset manner in the main longitudinal direction (A) to force fluid to make at least one round trip in the main longitudinal direction (A) as it passes between the lower and upper ends of the storage volume, characterized in that, These multiple deflection walls (3) are located in the lower half of the storage volume, and the tank further has a filling and / or extraction port (4) located in the lower portion of a longitudinal end of the housing (2), and / or a filling and / or extraction port (5) located in the upper portion of a longitudinal end of the housing (2), and / or a fluid filling and / or extraction port (6) located in a longitudinal end and at an intermediate height between the upper and lower portions of the storage volume.

2. The tank as described in claim 1, characterized in that, The liquefied gas is liquefied hydrogen.

3. The tank as described in claim 1, characterized in that, These deflection walls (3) extend from one end of the housing (2) along the main longitudinal direction (A) over a portion of the storage volume.

4. The tank as described in claim 2, characterized in that, These deflection walls (3) extend from one end of the housing (2) along the main longitudinal direction (A) over a portion of the storage volume.

5. The tank as described in claim 1, characterized in that, These deflecting walls (3) are horizontal or substantially horizontal in the configuration of the can (1).

6. The tank as described in claim 2, characterized in that, These deflecting walls (3) are horizontal or substantially horizontal in the configuration of the can (1).

7. The tank as described in claim 3, characterized in that, These deflecting walls (3) are horizontal or substantially horizontal in the configuration of the can (1).

8. The tank as described in claim 4, characterized in that, These deflecting walls (3) are horizontal or substantially horizontal in the configuration of the can (1).

9. The can as described in any one of claims 1 to 8, characterized in that, These deflection walls (3) extend horizontally across the entire cross section of the storage volume.

10. The can as claimed in any one of claims 1 to 8, characterized in that, The jar has an odd number of deflecting walls (3).

11. The can as claimed in claim 9, characterized in that, The jar has an odd number of deflecting walls (3).

12. The tank as claimed in claim 10, characterized in that, The can has three deflecting walls (3).

13. The can as claimed in any one of claims 1 to 8, characterized in that, The container has a deflecting wall (3) through which multiple orifices (7) are passed.

14. The can as claimed in claim 9, characterized in that, The container has a deflecting wall (3) through which multiple orifices (7) are passed.

15. The tank as claimed in claim 10, characterized in that, The container has a deflecting wall (3) through which multiple orifices (7) are passed.

16. The tank as claimed in claim 12, characterized in that, The container has a deflecting wall (3) through which multiple orifices (7) are passed.

17. The can as claimed in any one of claims 1 to 8, characterized in that, The deflection wall (3) of the can has multiple orifices (7) penetrating only a portion of the surface of the deflection wall (3).

18. The can as claimed in claim 9, characterized in that, The deflection wall (3) of the can has multiple orifices (7) penetrating only a portion of the surface of the deflection wall (3).

19. The tank as claimed in claim 10, characterized in that, The deflection wall (3) of the can has multiple orifices (7) penetrating only a portion of the surface of the deflection wall (3).

20. The tank as claimed in claim 12, characterized in that, The deflection wall (3) of the can has multiple orifices (7) penetrating only a portion of the surface of the deflection wall (3).

21. The tank as claimed in claim 13, characterized in that, The deflection wall (3) of the can has multiple orifices (7) penetrating only a portion of the surface of the deflection wall (3).

22. The can as claimed in any one of claims 1 to 8, characterized in that, The deflection wall (3) located in the upper part of the storage volume has multiple openings (7).

23. The can as claimed in claim 9, characterized in that, The deflection wall (3) located in the upper part of the storage volume has multiple openings (7).

24. The tank as claimed in claim 10, characterized in that, The deflection wall (3) located in the upper part of the storage volume has multiple openings (7).

25. The tank as claimed in claim 12, characterized in that, The deflection wall (3) located in the upper part of the storage volume has multiple openings (7).

26. The tank as claimed in claim 13, characterized in that, The deflection wall (3) located in the upper part of the storage volume has multiple openings (7).

27. The tank as claimed in claim 17, characterized in that, The deflection wall (3) located in the upper part of the storage volume has multiple openings (7).

28. The can as claimed in any one of claims 1 to 8, characterized in that, At least some of these deflection walls (3) are made of flexible materials.

29. The can as claimed in claim 9, characterized in that, At least some of these deflection walls (3) are made of flexible materials.

30. The tank as claimed in claim 10, characterized in that, At least some of these deflection walls (3) are made of flexible materials.

31. The tank as claimed in claim 12, characterized in that, At least some of these deflection walls (3) are made of flexible materials.

32. The tank as claimed in claim 13, characterized in that, At least some of these deflection walls (3) are made of flexible materials.

33. The tank as claimed in claim 17, characterized in that, At least some of these deflection walls (3) are made of flexible materials.

34. The tank as claimed in claim 22, characterized in that, At least some of these deflection walls (3) are made of flexible materials.

35. The tank as claimed in claim 28, characterized in that, The flexible material is lighter than the material used to manufacture the shell.

36. The tank as claimed in any one of claims 1 to 8, characterized in that, The tank contains liquefied gas, and at least some of these deflecting walls (3) are immersed in the liquid phase.

37. The can as claimed in claim 9, characterized in that, The tank contains liquefied gas, and at least some of these deflecting walls (3) are immersed in the liquid phase.

38. The can as claimed in claim 10, characterized in that, The tank contains liquefied gas, and at least some of these deflecting walls (3) are immersed in the liquid phase.

39. The tank as claimed in claim 12, characterized in that, The tank contains liquefied gas, and at least some of these deflecting walls (3) are immersed in the liquid phase.

40. The tank as claimed in claim 13, characterized in that, The tank contains liquefied gas, and at least some of these deflecting walls (3) are immersed in the liquid phase.

41. The tank as claimed in claim 17, characterized in that, The tank contains liquefied gas, and at least some of these deflecting walls (3) are immersed in the liquid phase.

42. The tank as claimed in claim 22, characterized in that, The tank contains liquefied gas, and at least some of these deflecting walls (3) are immersed in the liquid phase.

43. The tank as claimed in claim 28, characterized in that, The tank contains liquefied gas, and at least some of these deflecting walls (3) are immersed in the liquid phase.

44. The tank as claimed in claim 35, characterized in that, The tank contains liquefied gas, and at least some of these deflecting walls (3) are immersed in the liquid phase.

45. A method for storing cryogenic liquefied gases using a tank as described in any one of claims 1 to 44, characterized in that, The liquefied gas is stored in the tank (1) with the liquid level above at least one of the deflecting walls.

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