Storage container and method

Abstract

The invention relates to a storage container (1) for storing a cryogen (H2), having an inner container (3) for receiving the cryogen (H2), wherein the inner container (3) has a liquid zone (8), which is suitable for receiving a liquid phase (LH2) of the cryogen (H2), and a gas zone (7), which is arranged above the liquid zone (8) as seen in a direction of gravity (g) and which is suitable for receiving a gaseous phase (GH2) of the cryogen (H2), further having a pressure build-up system (20) for building up pressure within the inner container (3), wherein the pressure build-up system (20) has a base (21) which is arranged within the inner container (3) and is only permeable for the gaseous phase (GH2), wherein the base (21) forms a gas chamber (22) arranged below the liquid zone (8) as seen in the direction of gravity (g), and wherein the pressure build-up system (20) is configured to remove some of the liquid phase (LH2) from the liquid zone (8), to evaporate same and supply same to the gas chamber (22) as a gaseous phase (GH2) such that the gaseous phase (GH2) flows from the gas chamber (22) through the base (21) into the liquid zone (8).

Description

[0001] Description

[0002] Storage tanks and processes

[0003] The invention relates to a storage container for storing a cryogen and a method for operating such a storage container.

[0004] Storage tanks for liquid hydrogen comprise a liquid zone containing liquid hydrogen and a gas zone containing gaseous hydrogen arranged above the liquid zone. According to internal company knowledge, such a storage tank can have a pressure build-up circuit. The use of such a pressure build-up circuit can cause a thermodynamic imbalance between the liquid hydrogen and the gaseous hydrogen due to superheated steam in the gas zone. Due to movement of the storage tank, particularly during mobile use, a mixture of the liquid hydrogen and the gaseous hydrogen within the storage tank can lead to a pressure drop within the storage tank.However, a consumer, such as a fuel cell, requires a nearly constant supply pressure, which cannot be guaranteed using such a pressure build-up circuit. This needs to be improved.

[0005] Against this background, it is an object of the present invention to provide an improved storage container.

[0006] Accordingly, a storage container for storing a cryogen is proposed.The storage container comprises an inner container for receiving the cryogen, wherein the inner container has a liquid zone which is suitable for receiving a liquid phase of the cryogen, and a gas zone which is arranged above the liquid zone as viewed along a direction of gravity and is suitable for receiving a gaseous phase of the cryogen, and a pressure build-up system for building up pressure within the inner container, wherein the pressure build-up system has a base which is arranged within the inner container and is permeable only to the gaseous phase, wherein the base forms a gas space which is arranged below the liquid zone as viewed along the direction of gravity, and wherein the pressure build-up system is configured to remove a portion of the liquid phase from the liquid zone, to evaporate it, and to supply it to the gas space as a gaseous phase, such that the gaseous phase flows from the gas space through the base into the liquid zone.

[0007] As the gaseous phase flows from the gas space through the bottom into the liquid zone, the gaseous phase rises in the form of gas bubbles within the liquid phase and can thereby heat it. In other words, heat is transferred from the gaseous phase to the liquid phase. Furthermore, the inflowing gaseous phase can increase the gas pressure in the gas zone. However, the cryogen remains in its thermodynamic equilibrium state. The previously mentioned problem of an undesirable pressure drop within the storage vessel during movement-induced mixing of the liquid and gaseous phases no longer occurs or is at least mitigated. This means that so-called sloshing effects, in particular, are prevented or reduced.

[0008] The storage container is particularly suitable for transporting the cryogen. Therefore, the storage container can also be referred to as a transport container. The storage container is preferably at least double-walled and, in addition to the inner container, comprises an outer container enclosing the inner container. The storage container can therefore also be referred to as a double-walled storage container. The storage container can be part of a vehicle, in particular a watercraft. In this case, the storage container is suitable for mobile applications. However, the storage container can also be used stationary, for example, in building services engineering.

[0009] A gap can be provided between the inner container and the outer container. A thermal insulation element that completely encloses or surrounds the inner container can be provided in the gap. The insulation element serves as thermal insulation. The insulation element is multi-layered. This means that the insulation element comprises a plurality of layers. In particular, the insulation element is a so-called multilayer insulation (MLI).

[0010] The cryogen can, in particular, be liquid hydrogen. Since the storage container is preferably designed to hold liquid hydrogen, the storage container can also be referred to as a hydrogen storage container or hydrogen storage tank. The term "cryogen" can be replaced with the term "hydrogen" and vice versa. However, the cryogen can also be liquid helium, liquid oxygen, or liquid nitrogen.

[0011] The cryogen is contained in the inner container. As long as the cryogen is in the two-phase region, a gas zone containing the gaseous phase and a liquid zone containing the liquid phase form within the inner container. Thus, after being filled into the inner container, the cryogen has two phases with different aggregate states: liquid and gaseous. This means that there is a phase boundary between the liquid and gaseous phases within the inner container.

[0012] In this context, "cryogen" can refer to both the liquid and gaseous phases of the cryogen. The liquid phase can, in particular, be evaporated and thus converted into the gaseous phase. Conversely, the gaseous phase can condense and thus be converted into the liquid phase. After evaporation, the cryogen is a gas or can be referred to as gaseous or vaporized cryogen. If both the gaseous and liquid phases exist simultaneously, the phase boundary lies between the liquid and gaseous phases. The cryogen is thus in the two-phase region.

[0013] Cryogen can be converted from the liquid phase to the gaseous phase through phase transitions. In this case, this means, in particular, that the liquid phase can transition from liquid to gaseous into the gaseous phase through a phase transition. The liquid phase evaporates. Conversely, the gaseous phase can transition from gaseous to liquid into the liquid phase through a phase transition. The gaseous phase condenses. The cryogen thus has at least two states of matter: liquid and gaseous. The cryogen can also transition into a solid phase, for example, in the form of ice.

[0014] The storage tank is preferably rotationally symmetrical to a symmetry or

[0015] The storage container is preferably arranged so that the central axis is perpendicular to the direction of gravity. This means that the storage container is arranged horizontally or horizontally. However, the storage container can also be arranged vertically or vertically. In this case, the central axis is oriented parallel to the direction of gravity.

[0016] The inner container is preferably cylindrical. The inner container has, in particular, a tubular or cylindrical base section, which can be constructed rotationally symmetrically to the central axis. The base section of the inner container is closed at each end by two outwardly curved lid sections. However, this is not mandatory. The lid sections can also be designed differently. The inner container can also be referred to as an inner tank.

[0017] The base can be inserted, welded, and / or soldered into the inner vessel. The base separates the gas space from the liquid zone. The gas space is filled exclusively with the gaseous phase. The pressure build-up system can remove the liquid phase from the inner vessel, in particular the liquid zone, feed it to a pressure build-up evaporator, evaporate it, and feed it to the gas space as the gaseous phase. The gaseous phase then rises from the gas space through the base, against the direction of gravity, upwards through the liquid zone. The gaseous phase rises in the form of gas bubbles in the liquid phase. This results in heat transfer from the gaseous phase to the liquid phase.

[0018] The tray is, in particular, a so-called column tray and can therefore also be referred to as such. A "column tray" in this case refers to a plate-shaped component of a rectification column, for example, for air separation. By using a column tray for the tray, the storage vessel can be manufactured cost-effectively. The fact that the tray is "permeable" to the gaseous phase means, in this case, in particular that only or exclusively the gaseous phase can flow through the tray, whereas the liquid phase preferably cannot enter the gas space through the tray. The tray is thus semipermeable. "Semipermeable" in this case refers, in particular, to the fact that the tray is permeable only to the gaseous phase and not to the liquid phase. The tray can, for example, have a membrane that is permeable only to the gaseous phase and is supported by a supporting structure.

[0019] The fact that the base "forms" the gas space means in particular that the gas space is separated or delimited from the liquid zone by means of the base. The gas space is thus bounded or enclosed by a part of the inner container and the base. At the front, the gas space is bounded by the aforementioned lid sections of the inner container. During operation of the storage container, the liquid phase is contained in the liquid zone, and the gaseous phase is contained in the gas zone. The respective extent of the liquid zone and the gas zone is determined or defined by the phase boundary. This means, in particular, that the liquid zone and the gas zone each have a variable or changing extent or size. The gaseous phase forms a gas cushion layered above the liquid zone. The gas space, in turn, forms a gas cushion layered below the liquid zone.

[0020] According to one embodiment, the pressure build-up system comprises a pressure build-up evaporator, wherein the pressure build-up evaporator is arranged below the inner container as viewed along the direction of gravity.

[0021] Because the pressure buildup evaporator is arranged below the inner vessel, viewed along the direction of gravity, it is possible to convey the liquid phase to be evaporated from the liquid zone to the pressure buildup evaporator solely due to the hydrostatic pressure of the liquid phase. Thus, a so-called natural circulation can be achieved. "Natural circulation" in this context means that no additional external energy, for example, from a pump or compressor, is required to convey the liquid phase from the liquid zone to the evaporator and to convey the gaseous phase from the evaporator to the gas space. This makes the storage vessel less susceptible to failure.

[0022] According to a further embodiment, the pressure build-up evaporator is fluidically connected to the liquid zone by means of a withdrawal line, wherein the pressure build-up evaporator is fluidically connected to the gas space by means of a first supply line.

[0023] Viewed along the direction of gravity, the withdrawal line preferably exits the liquid zone directly above the tray. The withdrawal line opens into an inlet of the pressure build-up evaporator. The first supply line exits an outlet of the pressure build-up evaporator.

[0024] According to a further embodiment, the extraction line has a valve, wherein the first supply line has a valve.

[0025] This means that both the extraction line and the first supply line can be assigned their own valve. This enables, for example, so-called batch operation of the pressure buildup evaporator. In particular, this means that the volume flow of the gaseous phase from the gas space through the base into the liquid zone can be interrupted, allowing the storage vessel to be operated temporarily without the pressure buildup system.

[0026] According to a further embodiment, the pressure build-up evaporator is fluidly connected to the gas zone by means of a second supply line.

[0027] The second supply line preferably opens from the first supply line. The second supply line preferably also has a valve that allows the second supply line to be opened and closed. With the help of the second supply line, the gaseous phase generated by the evaporator can be fed directly into the gas space. This allows for a rapid pressure buildup in the gas zone. In this case, the gaseous phase is not cooled by the liquid phase.

[0028] According to a further embodiment, the second supply line has a valve.

[0029] The valve can be controlled, for example, using a control unit of the storage tank. This also applies to the other valves mentioned above. Control can be based, for example, on signals from a sensor system in the storage tank. The sensor system can, for example, include pressure sensors and / or temperature sensors arranged in or on the inner tank.

[0030] According to a further embodiment, the pressure build-up system is designed to maintain a gas pressure of the gaseous phase in the gas space above a sum of a hydrostatic pressure of the liquid phase acting on the ground and a gas pressure of the gaseous phase in the gas zone.

[0031] This ensures that the gaseous phase can flow through the tray from the gas zone into the liquid zone. At the same time, it ensures that the liquid phase cannot flow through the tray into the gas space.

[0032] According to a further embodiment, the base has a plurality of gas supply devices which are designed to allow the gaseous phase to flow from the gas space into the liquid zone and at the same time to prevent a backflow of the liquid phase from the liquid zone into the gas space.

[0033] In particular, the base comprises a base plate with a plurality of openings. Each opening can be assigned such a gas supply device. The gas supply devices act as check valves and prevent the liquid phase from flowing back from the liquid zone into the gas space. The gas supply devices can be valves, in particular check valves.

[0034] According to a further embodiment, each gas supply device has a tubular base section extending into the liquid zone and a dome-shaped cover section attached to the end of the base section.

[0035] In particular, the gas supply devices each have a bell-shaped or mushroom-shaped geometry. The base can therefore also be referred to as a bell-shaped base. According to a further embodiment, a lower edge of the lid section is arranged below an upper edge of the base section, viewed along the direction of gravity.

[0036] This geometry reliably prevents the liquid phase from flowing back from the liquid zone into the gas space.

[0037] According to a further embodiment, each gas supply device has a valve flap rotatably mounted on the base.

[0038] In particular, each valve flap is mounted on the base plate of the floor with a pivot point assigned to the respective valve flap. The valve flaps can also be referred to as check valves.

[0039] Furthermore, a method for operating a storage container for a cryogen, in particular for hydrogen, is proposed. The storage container has an inner container for containing the cryogen and a pressure build-up system for building up pressure within the inner container, wherein the inner container has a liquid zone which is suitable for containing a liquid phase of the cryogen, and a gas zone which is arranged above the liquid zone as viewed along a direction of gravity and is suitable for containing a gaseous phase of the cryogen, wherein the pressure build-up system has a base arranged within the inner container and is permeable only to the gaseous phase, and wherein the base forms a gas space arranged below the liquid zone as viewed along the direction of gravity.The method comprises the following steps: a) withdrawing a portion of the liquid phase from the liquid zone, b) evaporating the liquid phase withdrawn during step a), and c) supplying the evaporated liquid phase as a gaseous phase to the gas space, so that the gaseous phase flows from the gas space through the bottom into the liquid zone.

[0040] In particular, the gaseous phase flows spontaneously from the gas space through the bottom into the liquid zone. The gaseous phase rises in the form of gas bubbles against the direction of gravity within the liquid phase. This process involves a transfer of heat from the gas bubbles to the liquid phase. Heat is extracted from the gaseous phase, and this extracted heat is transferred to the liquid phase.

[0041] According to one embodiment, steps a) and c) are carried out by means of a natural circulation of the cryogen.

[0042] As mentioned before, this eliminates the need for a pump or compressor.

[0043] According to a further embodiment, by means of the natural circulation, a gas pressure in the gas space is maintained above a sum of a hydrostatic pressure of the liquid phase acting on the bottom in the liquid zone and a gas pressure of the gaseous phase in the gas zone.

[0044] This ensures that the gaseous phase can enter the liquid zone from the gas space. At the same time, it ensures that the liquid phase cannot flow back from the liquid zone into the gas zone.

[0045] According to a further embodiment, with the aid of the natural circulation, the gas pressure in the gas space is kept below a sum of a hydrostatic pressure of the liquid phase acting on an evaporator of the pressure build-up system and the gas pressure of the gaseous phase in the gas zone.

[0046] This is made possible by the fact that the pressure build-up evaporator is located below the bottom, as viewed along the direction of gravity. Keeping the gas pressure in the gas space below the sum of the hydrostatic pressure of the liquid phase acting on the pressure build-up evaporator and the gas pressure of the gaseous phase in the gas zone ensures that the gaseous phase can flow automatically from the evaporator into the gas space. A compressor or the like is unnecessary.

[0047] The embodiments and features described for the storage container apply accordingly to the proposed method, and vice versa. "One" is not necessarily to be understood as limiting the number to exactly one element. Rather, multiple elements, such as two, three, or more, can also be provided. Any other counting term used here should also not be understood as requiring a precise limitation to the corresponding number of elements. Rather, numerical deviations upwards and downwards are possible.

[0048] Further possible implementations of the storage container and / or the method also include combinations of features or embodiments described above or below with respect to the exemplary embodiments that are not explicitly mentioned. In this case, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the storage container and / or the method.

[0049] Further advantageous embodiments of the storage container and / or the method are the subject of the dependent claims and the exemplary embodiments of the storage container and / or the method described below. The storage container and / or the method are explained in more detail below using preferred embodiments with reference to the accompanying figures.

[0050] Fig. 1 shows a schematic sectional view of an embodiment of a storage container;

[0051] Fig. 2 shows a schematic sectional view of the storage container according to the section line ll-ll of Fig. 1;

[0052] Fig. 3 shows the detailed view III according to Fig. 2;

[0053] Fig. 4 shows again the detailed view III according to Fig. 2; and

[0054] Fig. 5 shows a schematic block diagram of an embodiment of a method for operating the storage container according to Fig. 1.

[0055] Fig. 1 shows a schematic sectional view of an embodiment of a

[0056] Storage container 1. Fig. 2 shows a schematic sectional view of the storage container 1 according to the section line 11-11 of Fig. 1. In the following, reference is made simultaneously to Figs. 1 and 2.

[0057] The storage vessel 1 can also be referred to as a storage tank. The storage vessel 1 is preferably suitable for storing hydrogen H2 (boiling point: 1 bara: 20.268 K = -252.882 °C). Therefore, the storage vessel 1 can also be referred to as a hydrogen storage vessel or a hydrogen storage tank. However, the storage vessel 1 can also be used for other cryogenic liquids. Examples of cryogenic fluids or liquids, or cryogens for short, in addition to the aforementioned hydrogen H2, are liquid helium He (boiling point: 1 bara: 4.222 K = -268.928 °C), liquid nitrogen N2 (boiling point: 1 bara: 77.35 K = -195.80 °C), or liquid oxygen O2 (boiling point: 1 bara: 90.18 K = -182.97 °C).

[0058] In the following, it is assumed that hydrogen H2 is used as the cryogen. Accordingly, the terms "hydrogen" and "cryogen" can be interchanged at will.

[0059] The storage container 1 can be a transport container. For example, the storage container 1 can be used to transport liquid hydrogen (LH2). The storage container 1 can be part of a vehicle, in particular a watercraft. In this case, the storage container 1 is suitable for mobile applications. However, the storage container 1 can also be used stationary, for example, in building services engineering.

[0060] The storage container 1 is constructed rotationally symmetrically to a symmetry or central axis 2. The central axis 2 is oriented perpendicular to a direction of gravity g. The storage container 1 comprises a first container or inner container 3, which is also constructed rotationally symmetrically to the central axis 2. The inner container 3 comprises a tubular or cylindrical base section 4, which is also constructed rotationally symmetrically to the central axis 2. The base section 4 can have a circular or approximately circular geometry in cross-section. Only the inner container 3 is shown in Fig. 2.

[0061] The base section 4 is closed at both ends by a lid section 5, 6. The lid sections 5, 6 are curved. A first lid section 5 and a second lid section 6 are curved in opposite directions, so that the lid sections 5, 6 are curved outward relative to the base section 4. The inner container 3 is fluid-tight, in particular gas-tight. The inner container 3 is made of stainless steel.

[0062] The liquid hydrogen LH2 is contained in the inner container 3. As long as the hydrogen H2 is in the two-phase region, a gas zone 7 with gaseous hydrogen GH2 and a liquid zone 8 with liquid hydrogen LH2 can be provided in the inner container 3. Thus, after being filled into the inner container 3, the hydrogen H2 can have two phases with different aggregate states, namely liquid and gaseous. This means that a phase boundary 9 is present in the inner container 3 between the liquid hydrogen LH2 and the gaseous hydrogen GH2.

[0063] Gaseous hydrogen GH2 can also be referred to as the gaseous phase in this context. Accordingly, the terms "gaseous hydrogen" and "gaseous phase" can be interchanged at will. Liquid hydrogen LH2 can also be referred to as the liquid phase in this context. Accordingly, the terms "liquid hydrogen" and "liquid phase" can be interchanged at will.

[0064] The inner container 3 is arranged entirely within a second container or outer container 10. The storage container 1 is thus double-walled. The outer container 10 is also constructed rotationally symmetrically to the central axis 2. The outer container 10, like the inner container 3, comprises a tubular or cylindrical base section 11, which is constructed rotationally symmetrically to the central axis 2. The base section 11 can have a circular or approximately circular geometry in cross-section. The outer container 10 is not shown in Fig. 2.

[0065] The base section 11 is closed at each end by a lid section 12, 13. In particular, a first lid section 12 and a second lid section 13 are provided. The lid sections 12, 13 are curved in opposite directions, so that the lid sections 12, 13 are curved outward relative to the base section 11. The outer container 10 is fluid-tight, in particular gas-tight. The outer container 10 is also made of stainless steel. Between the inner container 3 and the outer container 10, a gap 14 is provided that completely surrounds or encloses the inner container 3. The gap 14 is subjected to a vacuum. In the present case, a "vacuum" is understood to mean, in particular, a pressure of less than 300 mbar, preferably less than 10 -3 mbar, more preferably less than 10 -7mbar. The storage container 1 is thus vacuum-insulated or vacuum-insulated. The fact that the gap 14 completely "encloses" or "envelops" the inner container 3 means, in this case, that the gap 14, on the one hand, completely surrounds the base section 4 and, on the other hand, is also provided between the two first cover sections 5, 12 and between the two second cover sections 6, 13.

[0066] A thermal insulation element (not shown) that completely encloses or surrounds the inner container 3 is provided in the gap 14. This means that the insulation element encloses both the base section 4 and the lid sections 5, 6 of the inner container 3. The insulation element serves for thermal insulation. The insulation element is multi-layered. This means that the insulation element comprises a plurality of layers. The insulation element can therefore also be referred to as a multi-layer insulation element or a multi-layer thermal insulation element. In particular, the insulation element is a so-called multilayer insulation (MLI). The outer container 10 borders an environment 15 of the storage container 1.

[0067] A withdrawal line 16 leads from the liquid zone 8, through which liquid hydrogen LH2 can be withdrawn from the storage tank 1. The withdrawal line 16 leads to an evaporator 17, through which the liquid hydrogen LH2 can be evaporated into gaseous hydrogen GH2. The evaporator 17 can evaporate the liquid hydrogen LH2 electrically or with the aid of a heating medium. A valve 18 can be connected into the withdrawal line 16 between the storage tank 1 and the evaporator 17.

[0068] From the evaporator 17, the extraction line 16 leads to a consumer 19. The consumer 19 is preferably a fuel cell. A "fuel cell" is understood here to be a galvanic cell that converts the chemical reaction energy of a continuously supplied fuel, in this case gaseous hydrogen GH2, and an oxidizing agent, in this case oxygen, into electrical energy. With the aid of the evaporator 17, the gaseous hydrogen GH2 can be made available to the consumer 19 at a suitable supply pressure and temperature.

[0069] The storage container 1 further comprises a pressure build-up system 20. The pressure build-up system 20 has a base 21 arranged within the inner container 3, which separates a gas space 22 filled with gaseous hydrogen GH2 from the liquid zone 8. In other words, the gas space 22 is located below the liquid zone 8, viewed along the direction of gravity g.

[0070] The pressure build-up system 20 has a withdrawal line 23, which, like the withdrawal line 16, opens out of the liquid zone 8. A valve 24 can be connected into the withdrawal line 23. Viewed along the direction of gravity g, the withdrawal line 23 can open out of the liquid zone 8 below the withdrawal line 16. The withdrawal line 23 leads to a pressure build-up evaporator 25, which is designed to evaporate liquid hydrogen LH2 into gaseous hydrogen GH2.

[0071] A first supply line 26 leads from the pressure build-up evaporator 25 to the gas space 22 in order to supply the liquid hydrogen LH2 evaporated by the pressure build-up evaporator 25 to the gas space 22 as gaseous hydrogen GH2. A valve 27 is connected to the first supply line 26. Upstream of the valve 27, a second supply line 28 issues from the first supply line 26 and opens into the gas zone 7. The second supply line 28 has a valve 29. With the aid of the second supply line 28, the liquid hydrogen LH2 evaporated by the pressure build-up evaporator 25 can be supplied to the gas zone 7 as gaseous hydrogen GH2.

[0072] The storage container 1, the extraction line 16, the evaporator 17, the valve 18, and the pressure buildup system 20 can form a gas supply device 30, in particular a hydrogen supply device, which is suitable for providing the consumer 19 with the gaseous hydrogen GH2 at the aforementioned supply pressure and supply temperature. The gas supply device 30 can have a control unit 31, which can control the evaporator 17, the valve 18, and / or the pressure buildup system 20, in particular the valves 24, 27, 29 and the pressure buildup evaporator 25. This control can be based on sensor signals from a sensor system 32. The sensor system 32 can, for example, comprise temperature and / or pressure sensors arranged in or on the inner container 3, the extraction line 16, the evaporator 17, the valve 18, the consumer 19 and / or the pressure build-up system 20.

[0073] Fig. 3 shows the detailed view III according to Fig. 2.

[0074] The base 21 has a base plate 33 which includes a plurality of openings 34. Each opening 34 is assigned a gas supply device 35A, with the aid of which the gaseous hydrogen GH2 can be supplied to the liquid zone 8 from the gas space 22 in the form of gas bubbles 36. Only one gas supply device 35A will be discussed below. The gas supply device 35A is bell-shaped. Therefore, the base 21 can also be referred to as a bubble-cap base. The gas supply device 35A has a tubular or cylindrical base section 37 which can be soldered or welded into the opening 34. The base section 37 projects into the liquid zone 8. At the end, i.e. facing away from the base plate 33, a dome-shaped or spherical cap-shaped cover section 38 is attached to the base section 37.

[0075] During operation of the gas supply device 35A, the gaseous hydrogen GH2 flows from the gas space 22 through the base section 37 upwards towards the gas zone 7. The gaseous hydrogen GH2 then flows in the form of gas bubbles 36 over a lower edge 39 of the lid section 38 into the liquid zone 8. An upper edge 40 of the base section 37 is arranged below the lower edge 39, viewed along the direction of gravity g. The lid section 38 is connected to the base section 37 by means of a gas-permeable connecting plate 41. The connecting plate 41 is perforated. Instead of the connecting plate 41, struts can also be provided, with the aid of which the lid section 38 is supported on the base section 37. Alternatively, the base 21 can also have a membrane permeable only to gaseous hydrogen GH2 and a support structure for supporting the membrane. In this case, the gas supply device 35A can be omitted.In other words, in this case, the soil 21 is permeable to gaseous hydrogen GH2.

[0076] Fig. 4 again shows the detailed view III according to Fig. 2.

[0077] In particular, Fig. 4 shows an alternative embodiment of a gas supply device 35B as previously explained. The gas supply device 35B has the same functionality as the gas supply device 35A, namely the introduction of gaseous hydrogen GH2 from the gas space 22 in the form of gas bubbles 36 into the liquid zone 8. Therefore, only differences between the two gas supply devices 35A, 35B will be discussed below.

[0078] In contrast to the gas supply device 35A, the gas supply device 35B is not bell-shaped, but rather has a valve flap 42 that is mounted on the base plate 33 so as to be rotatable about a pivot point 43 in order to open and close the respective opening 34. The valve flap 42 is a check valve and can therefore also be referred to as such. In other words, the gas supply device 35B is a check valve and can therefore also be referred to as such.

[0079] Returning now to Figs. 1 and 2, particularly in maritime applications, movement of the liquid hydrogen LH2 contained in the storage tank 1 caused by sea conditions must be expected. If the storage tank 1 is arranged horizontally, as shown in Fig. 1, the inertia of the liquid hydrogen LH2 and the curvature of the storage tank 1 caused by the horizontal installation promote extensive sloshing of the liquid hydrogen LH2 both on its cylindrical outer wall and at its ends.

[0080] This sloshing, also known as sloshing, leads to the cooling of the gaseous hydrogen GH2 above the liquid hydrogen LH2 and, as a result, to an abrupt pressure drop in a gas cushion of gaseous hydrogen GH2 formed above the liquid hydrogen LH2. Depending on the current sea state, this can have adverse effects on the supply pressure available for the operating components of the consumer 19, which can lead to unstable operation of the consumer 19. This can be prevented with the help of the pressure build-up system 20, as explained below.

[0081] During operation of storage vessel 1, a gas pressure p1 prevails in gas zone 7. In gas space 22, a gas pressure p2 prevails that is greater than gas pressure p1. A hydrostatic pressure phydl of the liquid hydrogen LH2 acts on the base 21. At an inlet 44 of the pressure buildup evaporator 25, a hydrostatic pressure phyd2 of the liquid hydrogen LH2 acts, which is greater than the hydrostatic pressure phydl.

[0082] In order for the gaseous hydrogen GH2 to flow out of the gas space 22 in the form of gas bubbles 36 into the liquid zone 8, the following applies in the gas space 22, for example at any measuring point 45 on the underside of the base 21: p2 > pl + phydl

[0083] In order to ensure an independent conveyance of the gaseous hydrogen GH2 from the pressure build-up evaporator 25 to the gas space 22, the following applies at an outlet 46 of the pressure build-up evaporator 25: p2 < pl + phyd2

[0084] Furthermore: pl + phydl < p2 < pl + phyd2 phydl < p2 — pl < phyd2

[0085] This results in a maximum pressure difference between the gas pressures p1 , p2 of:

[0086] (p2 - pl) max = phyd2 - phydl During operation of the pressure build-up system 20, the gaseous hydrogen GH2 can enter the liquid zone 8 from the gas space 22 with the aid of the gas supply devices 35A, 35B, thereby increasing the gas pressure p1 and / or a temperature of the hydrogen H2, while the system remains in a state of thermodynamic equilibrium. The problems resulting from sloshing no longer occur or are at least mitigated.

[0087] Due to the effect of the hydrostatic pressure phydl, phyd2, liquid hydrogen LH2 is withdrawn from the storage vessel 1 and fed to the pressure buildup evaporator 25, which is located below the storage vessel 1 as viewed along the direction of gravity g. Superheated gaseous hydrogen GH2 emerging from the pressure buildup evaporator 25 is fed into the gas space 22 in a lower region of the storage vessel 1. From there, the gaseous hydrogen GH2 can enter the liquid zone 8 above, which is filled with liquid hydrogen LH2, via the gas supply devices 35A, 35B. The previously explained design of the gas supply devices 35A, 35B prevents liquid hydrogen LH2 from flowing into the gas space 22.

[0088] The interaction of the hydrostatic pressure phydl, phyd2 of the liquid hydrogen LH2 with the pressure buildup evaporator 25 ensures a continuous flow of gaseous hydrogen GH2 into the liquid zone 8 via the tray 21. Batch operation is possible by closing the valves 24, 27 upstream and downstream of the pressure buildup evaporator 25. The processes described above allow the gas pressure p1 to build up in the storage tank 1. Hydrogen H2 can thus be withdrawn via the withdrawal line 16 at a constant gas pressure p2 and supplied to the consumer 19.

[0089] Furthermore, for rapid pressure buildup, superheated gaseous hydrogen GH2 can be discharged downstream of the pressure buildup evaporator 25 via the valve 29 and returned directly to the gas zone 7 via the second supply line 28. To increase the performance of the pressure buildup system 20, a pump or compressor connected to the first supply line 26 can additionally be used. Optionally, a buffer tank for gaseous hydrogen GH2 can be integrated downstream of the pressure buildup evaporator 25 to further minimize pressure fluctuations. The additional introduction of thermal conducting plates can promote the establishment of thermodynamic equilibrium conditions between the gas zone 7 and the liquid zone 8.

[0090] The storage tank 1 has the following advantages. The pressure build-up system 20 is implemented in the sense of natural circulation. No additional energy is required from compressors or pumps. The performance of the pressure build-up is independent of the fill level in the inner tank 3. Only a height difference between the base 21 and the pressure build-up evaporator 25 is decisive for the function of the pressure build-up system 20. A constant state of equilibrium and thus controllable conditions can be achieved in the storage tank 1, even during movements of the storage tank 1. In other words, the occurrence of a sudden pressure drop due to shloshing effects is prevented. Reliable operation of the consumer 19 is ensured.

[0091] Fig. 5 shows a schematic block diagram of an embodiment of a method for operating the storage container 1.

[0092] In the method, in a step S1, a portion of the liquid hydrogen LH2 is withdrawn from the liquid zone 8 of the storage vessel 1. In a step S2, the liquid hydrogen LH2 withdrawn during step S1 is evaporated using the pressure buildup evaporator 25. In a step S3, the evaporated liquid hydrogen LH2 is fed to the gas space 22 as gaseous hydrogen GH2. The gaseous hydrogen GH2 then flows from the gas space 22 through the base 21 into the liquid zone 8.

[0093] Steps S1 and S2 are carried out with the aid of natural circulation of the hydrogen H2. In particular, with the aid of natural circulation, the gas pressure p2 in the gas space 22 is kept above the sum of the hydrostatic pressure phyd1 of the liquid hydrogen LH2 acting on the tray 21 in the liquid zone 8 and the gas pressure p1 of the gaseous hydrogen GH2 in the gas zone 7. In particular, with the aid of natural circulation, the gas pressure p2 in the gas space 22 is kept below the sum of the hydrostatic pressure phyd2 of the liquid hydrogen LH2 acting on the pressure build-up evaporator 25 and the gas pressure p1 of the gaseous hydrogen GH2 in the gas zone 7. Although the present invention has been described using exemplary embodiments, it is susceptible to numerous modifications.

[0094] Reference symbols used

[0095] 1 storage tank

[0096] 2 central axis

[0097] 3 inner containers

[0098] 4 Basic section

[0099] 5 Lid section

[0100] 6 Lid section

[0101] 7 Gas Zone

[0102] 8 Liquid zone

[0103] 9 Phase boundary

[0104] 10 outer containers

[0105] 11 Base section

[0106] 12 Lid section

[0107] 13 Lid section

[0108] 14 gap

[0109] 15 Surroundings

[0110] 16 Withdrawal line

[0111] 17 evaporators

[0112] 18 Valve

[0113] 19 consumers

[0114] 20 Pressure build-up system

[0115] 21 Floor

[0116] 22 Gas room

[0117] 23 Withdrawal line

[0118] 24 valve

[0119] 25 pressure build-up evaporators

[0120] 26 Supply line

[0121] 27 Valve

[0122] 28 Supply line

[0123] 29 Valve

[0124] 30 Gas supply device

[0125] 31 Control and regulation unit

[0126] 32 Sensor technology

[0127] 33 Base plate 34 Breakthrough

[0128] 35A Gas supply device

[0129] 35B Gas supply device

[0130] 36 Gas bubble

[0131] 37 Base section

[0132] 38 lid section

[0133] 39 bottom edge

[0134] 40 top edge

[0135] 41 Connecting plate

[0136] 42 valve flap

[0137] 43 Pivot point

[0138] 44 Entrance

[0139] 45 measuring point

[0140] 46 Output g Gravity direction

[0141] GH2 gaseous hydrogen / gaseous phase

[0142] H2 Hydrogen / Cryogen

[0143] LH2 liquid hydrogen / liquid phase phydl hydrostatic pressure phyd2 hydrostatic pressure p1 gas pressure p2 gas pressure

[0144] 51 steps

[0145] 52 steps

[0146] 53 steps

Claims

Patent claims 1 . Storage container (1) for storing a cryogen (H2), comprising an inner container (3) for receiving the cryogen (H2), wherein the inner container (3) has a liquid zone (8) which is suitable for receiving a liquid phase (LH2) of the cryogen (H2), and a gas zone (7) which is arranged above the liquid zone (8) as viewed along a direction of gravity (g) and is suitable for receiving a gaseous phase (GH2) of the cryogen (H2), and a pressure build-up system (20) for pressure build-up within the inner container (3), wherein the pressure build-up system (20) has a base (21) arranged within the inner container (3) and permeable only to the gaseous phase (GH2), wherein the base (21) forms a gas space (22) arranged below the liquid zone (8) as viewed along the direction of gravity (g), and wherein the pressure build-up system (20) is designed to provide the liquid zone (8) to remove part of the liquid phase (LH2),to evaporate and supply to the gas space (22) as a gaseous phase (GH2), so that the gaseous phase (GH2) flows from the gas space (22) through the bottom (21) into the liquid zone (8).

2. Storage container according to claim 1, wherein the pressure build-up system (20) has a pressure build-up evaporator (25), wherein the pressure build-up evaporator (25) is arranged below the inner container (3) when viewed along the direction of gravity (g).

3. Storage container according to claim 2, wherein the pressure build-up evaporator (25) is fluidically connected to the liquid zone (8) by means of a withdrawal line (23), and wherein the pressure build-up evaporator (25) is fluidically connected to the gas space (22) by means of a first supply line (26).

4. Storage container according to claim 3, wherein the extraction line (23) has a valve (24), and wherein the first supply line (26) has a valve (27).

5. Storage container according to claim 3 or 4, wherein the pressure build-up evaporator (25) is fluidically connected to the gas zone (7) by means of a second supply line (28).

6. Storage container according to claim 5, wherein the second supply line (28) has a valve (29).

7. Storage container according to one of claims 1 - 6, wherein the pressure build-up system (20) is designed to maintain a gas pressure (p2) of the gaseous phase (GH2) in the gas space (22) above a sum of a hydrostatic pressure (phydl) of the liquid phase (LH2) acting on the bottom (21) and a gas pressure (p1) of the gaseous phase (GH2) in the gas zone (7).

8. Storage container according to one of claims 1 - 7, wherein the base (21) has a plurality of gas supply devices (35A, 35B) which are designed to allow the gaseous phase (GH2) to flow from the gas space (22) into the liquid zone (8) and at the same time to prevent a backflow of the liquid phase (LH2) from the liquid zone (8) into the gas space (22).

9. A storage container according to claim 8, wherein each gas supply device (35A) has a tubular base portion (37) extending into the liquid zone (8) and a dome-shaped lid portion (38) attached to the end of the base portion (37).

10. Storage container according to claim 9, wherein a lower edge (39) of the lid portion (38) is arranged below an upper edge (40) of the base portion (37) when viewed along the direction of gravity (g).

11. Storage container according to claim 8, wherein each gas supply device (35B) has a valve flap (42) rotatably mounted on the base (21).

12. Method for operating a storage container (1) for a cryogen (H2), in particular for hydrogen, wherein the storage container (1) has an inner container (3) for receiving the cryogen (H2) and a pressure build-up system (20) for pressure build-up within the inner container (3), wherein the inner container (3) has a liquid zone (8) which is suitable for receiving a liquid phase (LH2) of the cryogen (H2), and a gas zone (7) which is arranged above the liquid zone (8) as viewed along a direction of gravity (g), and which is suitable for is suitable for receiving a gaseous phase (GH2) of the cryogen (H2), wherein the pressure build-up system (20) has a base (21) arranged within the inner container (3) and permeable only to the gaseous phase (GH2), and wherein the base (21) forms a gas space (22) arranged below the liquid zone (8) as viewed along the direction of gravity (g), with the following steps: a) removing (S1) a part of the liquid phase (LH2) from the liquid zone (8), b) evaporating (S2) the liquid phase (LH2) removed during step a), and c) feeding (S3) the evaporated liquid phase (LH2) as a gaseous phase (GH2) to the gas space (22), so that the gaseous phase (GH2) flows from the gas space (22) through the base (21) into the liquid zone (8).

13. The method according to claim 12, wherein steps a) and c) are carried out by means of a natural circulation of the cryogen (H2).

14. The method according to claim 13, wherein with the aid of the natural circulation a gas pressure (p2) in the gas space (22) is maintained above a sum of a hydrostatic pressure (phydl) of the liquid phase (LH2) in the liquid zone (8) acting on the bottom (21) and a gas pressure (p1) of the gaseous phase (GH2) in the gas zone (7).

15. The method according to claim 14, wherein with the aid of the natural circulation the gas pressure (p2) in the gas space (22) is kept below a sum of a hydrostatic pressure (phyd2) of the liquid phase (LH2) acting on a pressure build-up evaporator (25) of the pressure build-up system (20) and the gas pressure (p1) of the gaseous phase (GH2) in the gas zone (7).

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