storage tank

Abstract

The present invention relates to a storage tank (5) for liquid hydrogen (H2), comprising a wall (19), a base (18) closing the wall (19) at one end, a top (17) closing the wall (19) at an end opposite the base (18), and intermediate walls (23, 26) arranged inside the wall (19) and spaced apart from the wall (19), wherein a gap (25) is provided between a lower edge (24) of the intermediate walls (23, 26) and the base (18) such that an interior (12) enclosed by the intermediate walls (23, 26) is in fluid communication with an interior (11) enclosed by the wall (19).

Description

[Technical Field]

[0001] The present invention relates to a storage tank for liquid hydrogen.

[0002] According to the applicant's internal research, a storage tank for liquid hydrogen has a cylindrical geometry with a tubular base section along with two domed end cap sections that close the base section at its ends. For marine applications of such storage tanks, swell-induced liquid hydrogen movement within the storage tank must be anticipated. When the storage tank is positioned sideways or vertically, sloshing of liquid hydrogen can occur over a wide area due to the mass inertia of the liquid hydrogen and the existing curvature of both the base and end cap sections of the storage tank. This sloshing, also known as swashing, can lead to cooling of the vapor phase of hydrogen present within the storage tank, which in turn can lead to a pressure drop in the gas cushion created by the vapor phase. Depending on the current swell, this can have an undesirable effect on the hydrogen supply pressure available to operating components, such as fuel cells. This can lead to unstable operation of the operating components, which must be prevented.

[0003] Against this background, it is an object of the present invention to provide an improved storage tank.

[0004] Therefore, a storage tank for liquid hydrogen is proposed, which comprises a wall, a base closing the wall at one end, a top closing the wall at an end opposite the base, and an intermediate wall arranged inside the wall and spaced apart from the wall, with a gap between a lower edge of the intermediate wall and the base so that the interior space enclosed by the intermediate wall is fluidly connected to the interior space enclosed by the wall.

[0005] Due to the fact that the storage tank can be arranged vertically and has an additional intermediate wall, a significant reduction in the sloshing effect can be achieved not only in comparison with horizontal storage tanks but also in comparison with vertically arranged storage tanks without such intermediate walls, since the movement of the liquid hydrogen acts the same in all spatial directions and longitudinal and transverse movements do not need to be taken into account.

[0006] The storage tank is particularly suitable for marine applications. Therefore, the storage tank can also be called a marine storage tank. For example, the storage tank can be mounted on a vehicle, in particular a ship. Therefore, a vehicle, in particular a ship, having such a storage tank is also proposed. The storage tank can also be called a hydrogen storage tank. The storage tank is preferably suitable for holding liquid hydrogen. However, the storage tank can also be used for other cryogenic liquids. Examples of cryogenic fluids or liquids, or cryogens for short, are, for example, liquid helium, liquid nitrogen, or liquid oxygen.

[0007] After or during filling with hydrogen, a gas region containing gaseous hydrogen is formed in the storage tank, below which a liquid region containing liquid hydrogen is formed. A phase boundary is provided between the gas region and the liquid region. After entering the storage tank, helium has two phases with different condensation states: a liquid phase and a gas phase. Hydrogen can transition from the liquid phase to the gas phase and vice versa. An intermediate wall protrudes at least partially into the liquid region. The intermediate wall is preferably always at least partially flushed with liquid hydrogen.

[0008] The wall is specifically cylindrical, preferably circularly cylindrical. The intermediate wall also has a circularly cylindrical geometry. The intermediate wall being "spaced" from the wall means in this case that there is no direct contact between the wall and the intermediate wall. Specifically, the intermediate wall is arranged at a radial distance from the wall. The intermediate wall has open ends, particularly when viewed from the base. This means that the term "enclosed" also includes embodiments in which each internal space is open to the other internal spaces. The internal spaces being "fluidly connected" in this case means that liquid hydrogen can flow between the internal spaces. With respect to the direction of gravity, the top is specifically arranged above the base. That is, the storage tank is arranged upright or vertical.

[0009] According to a particularly preferred development of the storage tank, the storage tank comprises an axis of symmetry extending along the direction of gravity, a wall that is rotationally symmetrical with respect to the axis of symmetry, a base that closes the wall at one end, a top that closes the wall at one end opposite the base, and an intermediate wall that is arranged inside the wall and at a distance from the wall and that is rotationally symmetrical with respect to the axis of symmetry.

[0010] In this case, the fact that the axis of symmetry extends along the direction of gravity means that the axis of symmetry, and therefore the storage tank, is arranged vertically and not horizontally. That is, the top is located at the top in the direction of gravity, and the base is located at the bottom and therefore below the top. The walls connect the top to the base. The top and base are domed, specifically facing outwards with respect to the walls.

[0011] According to one embodiment, the wall is rotationally symmetrical about an axis of symmetry extending along the direction of gravity.

[0012] The wall is therefore preferably tubular or cylindrical.

[0013] According to a further embodiment, the intermediate wall is rotationally symmetrical about an axis of symmetry.

[0014] The intermediate wall thus extends around the axis of symmetry at a radial distance from the wall.

[0015] According to another embodiment, a gap is provided between the wall and the intermediate wall, extending around the axis of symmetry.

[0016] The gap is preferably annular. The gap extends completely around the axis of symmetry. The gap is preferably gas-filled. The gap can also be at least partially liquid-filled. That is, the gap can be at least partially filled with liquid hydrogen and at least partially filled with gaseous hydrogen.

[0017] According to a further embodiment, the storage tank comprises a plurality of intermediate walls which are rotationally symmetrical about an axis of symmetry, the intermediate walls being arranged coaxially with respect to one another.

[0018] The number of intermediate walls is arbitrary. For example, two, three, or more intermediate walls may be provided. The intermediate walls are preferably all cylindrical and have a rotationally symmetric structure about a common axis of symmetry. Here, "coaxial" specifically means that the intermediate walls share a common axis of symmetry.

[0019] According to a further embodiment, a gap is provided between the first intermediate wall and the second intermediate wall arranged within the first intermediate wall, the gap extending around the axis of symmetry.

[0020] The gap is preferably annular. The gap is particularly gas-filled. The gap can also be at least partially liquid-filled. A third intermediate wall and a fourth intermediate wall with corresponding gaps can also be provided.

[0021] According to a further embodiment, the intermediate wall is supported on the wall by supports.

[0022] The supports can be in the form of columns connecting the intermediate wall to the wall of the storage tank. A second intermediate wall can be supported directly on the wall in the same way, or the second intermediate wall can be supported on the first intermediate wall. The number of supports can be any number. Preferably, at least three supports are provided, evenly distributed around the axis of symmetry.

[0023] According to a further embodiment, the intermediate wall is spaced apart from the base by a gap when viewed along the axis of symmetry.

[0024] This means that the intermediate wall is not connected to the base, and in particular has a lower edge that protrudes into the liquid hydrogen, and in particular is spaced apart from the base by a gap.

[0025] According to a further embodiment, the intermediate wall is connected to the top.

[0026] The storage tank preferably comprises an outer tank and an inner tank housed in the outer tank, the intermediate wall being fixedly connected, in particular by welding or soldering, to the top section of the inner tank.

[0027] According to a further embodiment, the storage tank further comprises an inner tank for holding hydrogen and an outer tank in which the inner tank is housed, and an intermediate wall section starting from the top and extending along the axis of symmetry towards the base extends into the inner tank.

[0028] An insulating element may be provided between the inner tank and the outer tank. The inner tank and the outer tank each have a tubular base section that is rotationally symmetric about an axis of symmetry. Each base section is connected at one end to a top section and at an end opposite the top section to a bottom section. Each top section forms the top of the storage tank, and each bottom section forms the base of the storage tank. The base sections form the walls of the storage tank.

[0029] According to a further embodiment, the intermediate wall extends into the inner tank along at least half of the length of the inner tank.

[0030] This means that the intermediate wall has a length along the axis of symmetry that is at least equal to or greater than half the length of the inner tank, provided that the aforementioned gap is still provided between the lower edge of the intermediate wall and the base of the storage tank.

[0031] According to a further embodiment, the base and top are domed outwardly and in opposite directions relative to the wall.

[0032] That is, the base and top are curved away from the wall along the axis of symmetry. As previously mentioned, the base includes the bottom sections of the inner and outer tanks, and the top includes the top sections of the inner and outer tanks.

[0033] In this case, "a(n)" should not be understood as necessarily limiting to exactly one element. Rather, there can be several elements, such as two, three, or more. Any other numerical term used herein should not be understood to imply that a strict limitation on the number of exactly corresponding elements must be achieved. Rather, upward or downward variations in numerical value are possible.

[0034] Further possible implementations of the storage tank also include combinations not expressly mentioned of the features or embodiments described above or below with respect to the exemplary embodiments. Those skilled in the art will also add individual aspects as improvements or additions to each of the basic forms of the storage tank. [Brief explanation of the drawings]

[0035] Further advantageous embodiments of the storage tank are the subject of the dependent claims and of the exemplary embodiments of the storage tank described below. The storage tank is described in more detail below on the basis of preferred embodiments with reference to the provided drawings. [Figure 1] 1 shows a schematic side view of one embodiment of a vehicle. [Figure 2] 2 shows a schematic cross-sectional view of an embodiment of a storage tank for the vehicle according to FIG. 1; [Figure 3] 3 shows a further schematic cross-sectional view of the storage tank according to section line III-III of FIG. 2;

[0036] In the drawings, identical or functionally equivalent elements are designated by the same reference symbols unless otherwise indicated.

[0037] 1 shows a highly simplified schematic side view of one embodiment of a vehicle 1. The vehicle 1 may be, for example, a marine vessel, specifically a ship. The vehicle 1 may be referred to as a marine vehicle. Specifically, the vehicle 1 may be a marine passenger ferry. Alternatively, the vehicle 1 may be a land vehicle. However, in the following, it will be assumed that the vehicle 1 is a ship.

[0038] The vehicle 1 comprises a buoyant hull 2. A bridge 3 is provided on or above the hull 2. The vehicle 1 is preferably powered by hydrogen. For this purpose, the vehicle 1 may have a fuel cell 4. In this case, "fuel cell" is understood to mean a galvanic cell that converts the energy of a chemical reaction between a continuously supplied fuel, in this case hydrogen, and an oxidant, in this case oxygen, into electrical energy. The electrical energy obtained may, for example, power an electric motor (not shown), which in turn drives, for example, a ship's screw for propelling the vehicle 1.

[0039] A storage tank 5 is provided for storing liquid hydrogen to supply hydrogen to the fuel cell 4. The storage tank 5 is rotationally symmetrical about a central axis or axis of symmetry 6. The storage tank 5 can be arranged, for example, inside the hull 2, in particular in the engine room, on the bridge 3, or on the deck of the hull 2, said deck serving as a support structure 7. The axis of symmetry 6 is oriented along the direction of gravity. That is, the storage tank 5 is arranged upright or vertically. The axis of symmetry 6 is therefore perpendicular to the support structure 7. If the vehicle 1 is, for example, a vehicle converted to hydrogen power, the storage tank 5 can also be arranged, for example, in a funnel or stack of the vehicle 1.

[0040] In marine applications, swell-induced movement of the liquid hydrogen contained in the storage tank 5 must be anticipated. In the case of a horizontally oriented cylindrical storage tank (not shown), sloshing of large areas of liquid hydrogen is promoted by the mass inertia of the liquid hydrogen and the curvature of the storage tank that exists at both the cylindrical outer wall and ends of the storage tank due to its horizontal installation.

[0041] This sloshing, also known as swathing, leads to a cooling of the gas phase above the liquid hydrogen, thereby leading to a pressure drop in the gas cushion formed above the liquid hydrogen. Depending on the current swell, this can have an undesirable effect on the hydrogen supply pressure available to the operating components of the fuel cell 4, which can lead to unstable operation of the fuel cell 4. This must be prevented.

[0042] Figure 2 is a schematic cross-sectional view of one embodiment of the storage tank 5 as described above. Figure 3 shows a further cross-sectional view of the storage tank 5 according to section line III-III in Figure 2. In the following, reference will be made simultaneously to Figures 2 and 3.

[0043] The storage tank 5 can also be called a storage vessel. As mentioned above, the storage tank 5 is suitable for holding liquid hydrogen H2 (boiling point at 1 bara: 20.268 K = -252.882 °C). Therefore, the storage tank 5 can also be called a hydrogen storage tank. However, the storage tank 5 can also be used for other cryogenic liquids. Examples of cryogenic fluids or liquids, or cryogens for short, in addition to the aforementioned liquid hydrogen H2, include liquid helium He (boiling point at 1 bara: 4.222 K = -268.928 °C), liquid nitrogen N2 (boiling point at 1 bara: 77.35 K = -195.80 °C), or liquid oxygen O2 (boiling point at 1 bara: 90.18 K = -182.97 °C).

[0044] The storage tank 5 is rotationally symmetrical about an axis of symmetry 6. The storage tank 5 comprises an outer tank 8 which is rotationally symmetrical about the axis of symmetry 6, and an inner tank 9 which is rotationally symmetrical about the axis of symmetry 6. The inner tank 9 is arranged completely inside the outer tank 8. Between the outer tank 8 and the inner tank 9, an insulating element 10 is provided. The insulating element 10 can comprise or be designed as a multi-layer insulator (MLI).

[0045] The outer tank 8 comprises a tubular or cylindrical base section 11, which may have a rotationally symmetrical design with respect to the axis of symmetry 6. The base section 11 is closed at both ends with the aid of a top section 12 and a bottom section 13. When viewed in the orientation of FIG. 2 or along the direction of gravity g, the top section 12 is arranged above the bottom section 13. In cross section, the base section 11 may have a circular or approximately circular geometric shape. The top section 12 and the bottom section 13 are dome-shaped. The top section 12 and the bottom section 13 are domed in opposite directions such that the top section 12 and the bottom section 13 are curved outward with respect to the base section 11. The outer tank 8 is fluid-tight and, in particular, gas-tight.

[0046] Like the outer tank 8, the inner tank 9 comprises a tubular or cylindrical base section 14 that is rotationally symmetric about an axis of symmetry 6. In the orientation of FIG. 2 , the base section 14 is closed at its top end by a top section 15 and at its bottom end by a bottom section 16. In cross section, the base section 14 can have a circular or approximately circular geometric shape. The top section 15 and the bottom section 16 are domed. Specifically, the top section 15 and the bottom section 16 are domed in opposite directions such that the top section 15 and the bottom section 16 are outwardly domed with respect to the base section 14. The outer tank 9 is fluid-tight and, in particular, gas-tight. The outer tank 8 and / or the inner tank 9 can have a bleed valve (not shown).

[0047] The two top sections 12, 15, together with the insulating element 10 between them, form the top 17 of the storage tank 5. The two bottom sections 13, 16, together with the insulating element 10 between them, form the base 18 of the storage tank 5, and the two base sections 11, 14, together with the insulating element 10 between them, form a wall 19 of the storage tank 5, which extends rotationally symmetrically about the axis of symmetry 6. The wall 19 surrounds the interior space I1 of the storage tank 5.

[0048] Liquid hydrogen H2 is held in the inner tank 9 or the internal space I1. As long as the hydrogen H2 is in a two-phase region, a gas region 20 having vaporized hydrogen H2 and a liquid region 21 having liquid hydrogen H2 can be provided in the inner tank 9. Therefore, after entering the inner tank 9, the hydrogen H2 has two phases with different condensation states, namely, a liquid phase and a gas phase. That is, in the inner tank 9, there is a phase boundary 22 between the liquid hydrogen H2 and the gaseous hydrogen H2.

[0049] The storage tank 5 also has at least one intermediate wall 23 within the inner tank 9. The intermediate wall 23 has a cylindrical, specifically circular-cylindrical, geometric shape and is rotationally symmetrical about the axis of symmetry 6. In this case, the intermediate wall 23 is connected to the top 17 of the storage tank 5, specifically to the top section 15 of the inner tank 9. For example, the intermediate wall 23 can be welded or soldered to the top section 15. The intermediate wall 23 encloses an internal space I2 that is fluidly connected to the internal space I1. The internal space I2 is not closed and is open toward the base 18. The internal spaces I1 and I2 are therefore fluidly connected to each other.

[0050] The intermediate wall 23 is constructed concentrically with respect to the wall 19 or with respect to the base sections 11, 14 of the outer and inner tanks 8, 9. The intermediate wall 23 extends from the top 17 to the base 18 along the direction of gravity. However, there is no connection between the base 18 and the intermediate wall 23. Specifically, a gap 25 is provided between the lower edge 24 of the intermediate wall 23 and the base 18. The intermediate wall 23 extends into the inner tank 9 along the axis of symmetry 6 over at least half of the length 1 of the inner tank 9. In this case, the intermediate wall 23 at least partially protrudes into the liquid region 21. That is, the intermediate wall 23 is partially washed away by the liquid hydrogen H2.

[0051] A plurality of such intermediate walls 23 may be provided. For example, a first intermediate wall 23 and a second intermediate wall 26 may be provided. The second intermediate wall 26 is likewise cylindrical and rotationally symmetrical about the axis of symmetry 6. The second intermediate wall 26 is disposed within the first intermediate wall 23. That is, the second intermediate wall 26, the first intermediate wall 23 and the wall 19 are disposed concentrically. The second intermediate wall 26 also terminates at a lower edge 24.

[0052] The first intermediate wall 23 and / or the second intermediate wall 26 can be supported against the wall 19 or against the base section 14 of the inner tank 9 with the help of supports 27, 28. The number of supports 27, 28 can be any number. For example, three such supports 27, 28 are provided, evenly distributed around the axis of symmetry 6.

[0053] Between the wall 19 and the first intermediate wall 23 there is a gap 29 extending about the axis of symmetry 6. The gap 29 can be partly filled with liquid hydrogen H2 and partly filled with gaseous hydrogen H2. Between the first intermediate wall 23 and the second intermediate wall 26 there is a gap 30 extending about the axis of symmetry 6. The gap 30 can also be partly filled with liquid hydrogen H2 and partly filled with gaseous hydrogen H2.

[0054] 3, the second intermediate wall portion 26 has a diameter d26 that is smaller than the diameter d23 of the first intermediate wall portion 23. The diameter d23 is smaller than the diameter d19, specifically the inner diameter, of the wall portion 19 or the base section 14 of the inner tank 9.

[0055] The function of the storage tank 5 is explained below. Due solely to the vertical structure or vertical arrangement of the storage tank 5, the aforementioned sloshing effect is already reduced, since the movement of the liquid hydrogen H2 excited by swells is significantly reduced by the vertical installation, which only impacts the vertically arranged wall 19. By installing the first intermediate wall 23 or the intermediate walls 23, 26, the sloshing of the liquid hydrogen H2 in the storage tank 5 is further reduced. The installation of the intermediate walls 23, 26 in a vertically arranged storage tank 5 can be realized with little effort, since the movement of the liquid hydrogen H2 acts the same in all directions and there is no need to consider the longitudinal and transverse movements of the liquid hydrogen H2.

[0056] Although the present invention has been described with reference to exemplary embodiments, the present invention can be modified in various ways within the scope of the appended claims.

[0057] [Table 1]

Claims

1. A storage tank (5) for liquid hydrogen (H2), the storage tank (5) comprising a cylindrical wall (19) constructed rotationally symmetrically with respect to an axis of symmetry (6) extending along the direction of gravity (g), a base (18) closing the wall (19) at one end, a top (17) closing the wall (19) at the end opposite the base (18), and intermediate walls (23, 26) arranged inside the wall (19) and spaced apart from the wall (19). a gap (25) is provided between the lower edge (24) of the intermediate wall (23, 26) and the base (18) of the tank (5) so that the internal space (12) enclosed by the intermediate wall (23, 26) is in fluid communication with the internal space (11) enclosed by the cylindrical wall (19), allowing the liquid hydrogen to flow between the internal spaces (11, 12); and a gap (29) is provided between the cylindrical wall (19) and the intermediate wall (23) and extends around the axis of symmetry (6); the base (18) and the top (17) are domed outwardly and in opposite directions relative to the cylindrical wall (19); The storage tank comprises an inner tank (9) for holding the liquid hydrogen and an outer tank (8) in which the inner tank is housed, and the intermediate wall portions (23, 26) are disposed within the inner tank (9); an insulating element is provided between the inner tank and the outer tank; the insulating element comprises a multi-layer insulation; A storage tank, characterized in that said intermediate wall (23, 26) has a length along said axis of symmetry (6) equal to at least half the length of said inner tank (9).

2. 2. A storage tank according to claim 1, wherein the intermediate walls (23, 26) are rotationally symmetrical about the axis of symmetry (6).

3. 3. A storage tank according to claim 1 or 2, comprising a plurality of intermediate walls (23, 26) which are rotationally symmetrical with respect to the axis of symmetry (6), the intermediate walls (23, 26) being arranged coaxially with respect to one another.

4. 4. The storage tank according to claim 3, wherein a gap (30) extending around the axis of symmetry (6) is provided between a first intermediate wall (23) and a second intermediate wall (26) arranged within the first intermediate wall (23).

5. A storage tank according to any one of claims 1 to 4, wherein the intermediate walls (23, 26) are supported on the wall (19) by supports (27, 28).

6. Storage tank according to any one of claims 1 to 5, wherein the intermediate wall (23, 26) is connected to the top (17).

7. A storage tank as described in any one of claims 1 to 6, wherein the intermediate wall portions (23, 26) start from the top (17) and extend into the inner tank (9) along the axis of symmetry (6) in the direction of the base (18).

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