Storage containers and methods

Abstract

A storage container (1) for storing a cryogenic agent (H2) comprises an inner container (3) for containing the cryogenic agent (H2), a latent heat reservoir (19) for containing a phase change material (N2), and an extraction pipe (22) for extracting the cryogenic agent (H2) from the inner container (3). The extraction pipe (22) is coupled to the latent heat reservoir (19) so that the liquid cryogenic agent (H2) contained in the extraction pipe (22) exchanges heat with the phase change material (N2). The latent heat reservoir (19) is fluidly connected to the surrounding area (23) of the storage container (1) only by a blowpipe (24).

Description

Technical Field

[0001] The present invention relates to a storage container for storing cryogens, and to a method of operating such a type of storage container.

[0002] A double-walled storage container for liquid hydrogen, having an outer container and an inner container disposed inside the outer container for containing liquid hydrogen, is known to the applicants within the premises. A vacuum is applied to the gap provided between the inner container and the outer container, and this gap may be filled with a heat insulating material at least regionally.

[0003] In order to use such a type of storage container in a marine environment, it may be necessary for the storage container to achieve a durability period of 15 days in case of failure, assuming an operating pressure under maximum filling. That is, during this period, the maximum allowable pressure inside the inner container must not be exceeded, and hydrogen must not escape from the storage container to the outside.

[0004] Currently, due to the requirement of the durability period depending on the heat incidence and the thermodynamic equilibrium temperature of the stored liquid hydrogen, the storage container can only be filled with liquid hydrogen to a certain extent. Currently, under typical conditions, often only 70% to 80% of the geometric container volume of the storage container can be utilized for the storage of liquid hydrogen. This needs to be improved.

[0005] Based on such a background, an object of the present invention is to provide an improved storage container.

[0006] Accordingly, a storage container for storing cryogens is proposed. The storage container includes an inner container for containing the cryogen, a latent heat storage for containing a phase change material, and a withdrawal pipe for withdrawing the cryogen from the inner container. The withdrawal pipe is operatively coupled to the latent heat storage such that the cryogen contained in the withdrawal pipe exchanges heat with the phase change material, and the latent heat storage is fluidly connectable to the surroundings of the storage container only by a blowout pipe.

[0007] By incorporating a latent heat storage device, the enthalpy of the phase change of the phase-change material during the solid-to-liquid phase transition can be utilized for cooling, for example, the shield surrounding the inner container or other components of the storage container. This extends the lifespan of the storage container for the cryogenic agent. In particular, it enables emergency cooling. Furthermore, it allows for a higher degree of filling of the inner container with the cryogenic agent.

[0008] This storage container is particularly suitable for transporting refrigerants. Therefore, it can also be called a transport container. The storage container is preferably double-walled, including an inner container and an outer container surrounding the inner container. Therefore, it can also be called a double-walled storage container. The storage container may be part of a vehicle, particularly a water vehicle. In this case, the storage container is suitable for mobile applications. However, the storage container can also be used in a stationary manner, for example, in construction technology.

[0009] The extraction piping leads from the storage container to a consumption unit, such as a fuel cell. For example, the consumption unit can be energized to power an electric motor, such as a ship's propeller. A liquid cryogenic agent can be vaporized before reaching the consumption unit, thereby supplying the gaseous cryogenic agent to the consumption unit at the appropriate supply pressure and temperature.

[0010] The cryogenic agent may be liquid hydrogen. Since this storage container is particularly suitable for containing liquid hydrogen, it can also be called a hydrogen storage container or hydrogen storage tank. In this context, the concept of "cryogenic agent" can be interchanged with the concept of "hydrogen," and vice versa. However, the cryogenic agent may also be liquid helium, liquid neon, etc.

[0011] The cryogenic agent is contained within an inner container. The inner container may have a gaseous zone where the cryogenic agent is vaporized and a liquid zone where the cryogenic agent is liquid, insofar as the cryogenic agent is in a two-phase region. In other words, after being injected into the inner container, the cryogenic agent has two phases with different condensation states, namely liquid and gas. That is, there is a phase boundary between the liquid cryogenic agent and the gaseous cryogenic agent within the inner container. Only the liquid cryogenic agent is extracted from the inner container via an extraction pipe. The end of the extraction pipe, located on or inside the surface of the inner container, is positioned inside or on the lower portion of the inner container when viewed in the direction of gravity. This end is preferably located inside or on the lower one-third of the inner container, and particularly preferably inside or on the lower one-sixth of the inner container. This end of the extraction pipe is particularly preferably located at a maximum of 30 mm from the lowest point of the inner container, and even more particularly preferably at a maximum of 20 mm when viewed in the direction of gravity.

[0012] The storage container is preferably configured to be rotationally symmetric with respect to an axis of symmetry or a central axis. Accordingly, the inner and outer containers may also be configured to be rotationally symmetric with respect to the central axis. The storage container is preferably positioned such that its central axis extends perpendicular to gravity; that is, the storage container is positioned horizontally. However, the storage container may be positioned vertically. In this case, the central axis extends parallel to the direction of gravity.

[0013] The inner container is preferably cylindrical. The inner container has a tubular or cylindrical base section, which may be configured rotationally symmetric with respect to a central axis. The base section of the inner container is closed at its ends by two cover sections that curve outward. However, this is not mandatory. The cover sections may be manufactured in a different manner. The inner container may also be called an inner tank.

[0014] A latent heat storage device can also be called a phase change storage device or a PCM storage device (Phase Change Material). In this context, a "latent heat storage device" is understood to be a special type of heat storage device in which the majority of the thermal energy supplied to it is stored in the form of latent heat, for example, for a phase change from solid to liquid.

[0015] In particular, phase-change materials having a melting point higher than the storage and / or transport temperature of the cryogenic material contained in the inner container are used.

[0016] Nitrogen is preferred as the phase change material. In this case, the concept of "phase change material" can be replaced with the concept of "nitrogen." However, argon, for example, can also be used as the phase change material.

[0017] The phase change material may be part of the latent heat reservoir and, consequently, part of the storage container. The phase change material can undergo phase transitions from solid to liquid, and from liquid to gas, and vice versa. During the normal operation of the storage container, when the refrigerant is removed from the storage container, it is preferable that only phase transitions between solid and liquid, or between liquid and solid, are intended. The phase change material absorbs heat during the phase transition from solid to liquid and releases heat during the phase transition from liquid to solid. During the phase transition from liquid to solid, the heat required for this can be drawn from a shield surrounding the inner container, thereby cooling the shield. This shield may be part of the storage container.

[0018] The extraction piping is coupled in a heat conduction manner, particularly to the latent heat reservoir, so that the cryogenic fluid flowing through the extraction piping can absorb heat from the phase change material, causing the phase change material to undergo a phase change from liquid to solid. For example, if the cryogenic fluid is not removed from the storage container for a short period of time, the phase change material will undergo a phase change from solid to liquid. At this time, the phase change material absorbs heat, and this heat can be used, for example, to cool the inner container using the shield described above.

[0019] The take-off piping may be connected externally to the latent heat reservoir, for example. However, the take-off piping may also be routed to pass directly through the latent heat reservoir. In this context, "operationally connected" of the take-off piping to the latent heat reservoir is understood to mean that the take-off piping can exchange heat with the latent heat reservoir in any manner, thereby transferring heat from the latent heat reservoir to the take-off piping and vice versa.

[0020] The latent heat reservoir forms a closed system that is not connected to the surroundings during the normal operation of the storage container as described above. "Normal operation" in this case is understood to mean that the cryogenic material is removed from the storage container, and that the removal of the cryogenic material may be temporarily interrupted in some cases. For example, if the removal of the cryogenic material is interrupted for a relatively long period of time due to a malfunction of the storage container, the latent heat reservoir can be fluidly connected to the surroundings by a blowpipe, and at this time the gaseous phase change material is released into the surroundings.

[0021] The statement that a latent heat storage device can be connected to its surroundings "only" by a discharge pipe, or "solely" by a discharge pipe, means, in this case, that there is no fluid connection between the latent heat storage device and its surroundings other than the discharge pipe, or that such a connection cannot be established.

[0022] However, fluid connection between the latent heat reservoir and the surrounding environment does not occur during the normal operation of the latent heat reservoir. Fluid connection between the latent heat reservoir and the surrounding environment is established via a blowpipe only in the event of a malfunction. In this context, "fluid connection" between the latent heat reservoir and the surrounding environment is understood to mean that the gaseous phase-change material can be released from the latent heat reservoir to the surrounding environment via the blowpipe. For example, if the maximum allowable pressure in the latent heat reservoir is exceeded, the blowpipe will release the gaseous phase-change material to the surrounding environment.

[0023] In one embodiment, the extraction piping is guided to pass through a latent heat storage device.

[0024] The latent heat reservoir may have, for example, a cylindrical geometry. The extraction piping may be guided to pass through the latent heat reservoir multiple times. For this purpose, the extraction piping may be configured, for example, in a meander shape. However, the extraction piping may be configured in a spiral or helical shape. However, the extraction piping may be guided to pass through the latent heat reservoir in a straight line. Alternatively, the extraction piping may be coupled to the latent heat reservoir externally.

[0025] In another embodiment, a heat exchanger located inside the latent heat storage unit is attached to the extraction piping.

[0026] The heat exchanger is preferably plate-shaped. The heat exchanger may be soldered or welded to, for example, the blowdown piping. The heat exchanger is made from a material that conducts heat particularly well, such as aluminum or copper. The heat exchanger may have multiple heat exchanger plates arranged inside a latent heat reservoir.

[0027] In another embodiment, the latent heat reservoir is filled at least regionally with a thermally conductive and fluid-permeable material structure. This may preferably be a metallic woven, knitted, or woven material. The material structure may have metal fibers or metal wires. This is preferably metallic wool. Alternatively, the material structure may have smooth and / or structured metal plates and / or metal foils. The material structure may be made from aluminum, aluminum alloys, copper, or copper alloys.

[0028] In particular, the material structure may be coupled to the heat exchanger. The material structure is impregnated with the phase change material. This embodies particularly good contact between the material structure, and consequently the heat exchanger, and the phase change material. The material structure is, or preferably contains, copper wool, copper alloy wool, aluminum wool, and / or aluminum alloy wool. A material structure with good thermal conductivity ensures a good thermal transition between the heat exchanger and the solid phase change material.

[0029] In another embodiment, the blowing pipe has a blowing valve for blowing the phase change material to the surroundings.

[0030] The blowing valve preferably opens under a predetermined pressure. For example, for a latent heat storage device, the maximum allowable pressure is set. When the phase change material vaporizes and reaches such a maximum allowable pressure, the blowing valve immediately opens, and the gaseous phase change material is blown to the surroundings.

[0031] In another embodiment, the storage container further has an inner container and a shield surrounding the latent heat storage device, and the latent heat storage device is coupled to the shield so as to conduct heat.

[0032] The latent heat storage device may be part of the shield or vice versa. The shield is preferably made of a material with good heat conduction, such as aluminum or copper. The shield may particularly have a tubular base region configured to be rotationally symmetric with respect to the central axis. On the end face side, the shield is closed by two cover regions. The cover regions may curve outward with respect to the base region. The inner container and the latent heat storage device are arranged inside such a shield. The latent heat storage device may be coupled to the shield so as to conduct heat by, for example, one heat conduction member or a plurality of heat conduction members. Thus, the phase change material can take heat from the shield through one heat conduction member or a plurality of heat conduction members, thereby cooling the shield.

[0033] In another embodiment, the latent heat storage device is arranged between the cover region of the inner container and the cover region of the shield.

[0034] As described above, the inner container has two cover regions, particularly a first cover region and a second cover region. Correspondingly, the shield has two cover regions, particularly a first cover region and a second cover region. When viewed along the central axis, it is particularly preferable that the latent heat storage device is arranged between the second cover region of the inner container and the second cover region of the shield.

[0035] In another embodiment, the discharge piping is coupled to a shield to conduct heat.

[0036] This improves the thermal transition between the blowpipe and the shield. The low-temperature gaseous phase-change material can absorb heat from the shield, thereby providing additional cooling. For example, the blowpipe is soldered or welded to the shield. The blowpipe may be located inside or outside the shield. "Inside" the shield means facing the inner container. "Outside" the shield means facing away from the inner container.

[0037] In another embodiment, the discharge piping extends spirally around the shield, either on the inside or outside.

[0038] This allows for a longer discharge piping, which in turn improves the thermal transfer of the discharged gas from the phase-change material to the shield.

[0039] In another embodiment, the storage container further comprises an outer container surrounding the shield.

[0040] The outer container has a tubular base section, which may be configured to be rotationally symmetric with respect to the central axis. At the end face, the outer container is closed by two cover sections, particularly a first cover section and a second cover section. The cover sections are preferably curved outward with respect to the base section. The outer container surrounds the shield, which in turn surrounds the inner container and the latent heat reservoir. Thus, the shield is entirely located inside the outer container.

[0041] In another embodiment, the storage container further comprises a multilayer insulating member that at least partially fills the gap between the inner and outer containers.

[0042] The insulating material can also be called a shielding material. The insulating material serves to insulate the inner container from heat. The shield, in particular, as described above, is placed in the gap. The gap may be completely filled with the insulating material and the shield. Alternatively, the gap may be partially filled with the insulating material. It is preferable that the insulating material surrounds both the base area and the cover area of ​​the inner container. It is preferable that the insulating material comprises multiple layers or layers. In particular, the insulating material is a so-called multilayer insulating material (MLI). The insulating material comprises multiple layers or layers arranged alternately, consisting of perforated and / or embossed aluminum foil as reflectors and glass paper as spacers between adjacent aluminum foils. The glass paper may be perforated and / or punctured.

[0043] In another embodiment, the shield is embedded in a thermal insulation material.

[0044] In other words, layers of aluminum foil and glass paper may be provided both inside and outside the shield. Specifically, the shield is embedded in the outer layer of the insulating material. "Outer" here is understood to mean the region or direction of the outer container.

[0045] Furthermore, a method is proposed for operating such a type of storage container for storing cryogenic materials. This method includes the following steps: a) a step of removing liquid cryogenic material from the storage container, wherein during step a), the phase change material contained in the latent heat reservoir of the storage container undergoes a phase transition from liquid to solid by heat transfer from the phase change material to the liquid cryogenic material, or the phase change material remains solid during step a); b) a step of ending step a), wherein the phase change material undergoes a phase transition from solid to liquid; and c) a step of fluid separation of the latent heat reservoir from the surroundings of the storage container between steps a) and b).

[0046] In step a), in particular, a portion of the liquid cryogenic material is removed from the storage container via the extraction pipe. During step a), the phase change material contained in the latent heat reservoir undergoes a phase transition from liquid to solid due to the transfer of heat from the phase change material to the cryogenic material. If the phase change material is already solid, it remains solid during step a). In this case as well, heat continues to be removed from the phase change material. In step b), step a) is completed. That is, the cryogenic material stops flowing through the extraction pipe for at least a short time. Step b) can be performed until all of the phase change material has melted. In particular, step b) can be performed until the maximum allowable pressure described above is reached in the latent heat reservoir. Thus, during step b), the phase change material undergoes a phase transition from solid to liquid or remains in a solid aggregated state. It is preferable that step c) is performed in parallel with steps a) and b). That is, during steps a) and b), the latent heat reservoir is fluid-separated from the surroundings of the storage container based on step c). In other words, the blow-off valve is always closed between steps a) and c). Fluid separation of the latent heat reservoir from the surroundings is released only when the phase-change material has at least partially become gaseous and the maximum permissible pressure in the latent heat reservoir has been exceeded. This can occur, for example, during a storage container failure, when the cryogenic material is not removed from the inner container for a relatively long period of time. The gaseous phase-change material is then blown out to the surroundings through the blow-off piping and blow-off valve.

[0047] In one embodiment, during step b), the heat required for the phase transition is removed from the shield surrounding the inner container of the storage container.

[0048] In particular, during step b), the heat necessary for the phase transition from solid to liquid is removed from the shield. This cools the shield.

[0049] In another embodiment, steps a) to c) are performed during the normal operation of the storage container, and the discharge valve of the storage container is opened only when a malfunction occurs in the storage container, thereby blowing the gaseous phase change material into the surroundings.

[0050] The "normal operation" of the storage container is understood to be the withdrawal of liquid refrigerant. However, normal operation may also involve a temporary interruption in the withdrawal of liquid refrigerant. Failure occurs when the phase change material undergoes a phase transition from liquid to gas, causing the pressure in the latent heat storage container to rise above the maximum allowable pressure. In other words, only in the event of a failure does the latent heat storage container connect to the surroundings via a blow-off valve and blow out the gaseous phase change material.

[0051] Here, "one" does not necessarily mean limited to exactly one element. Rather, there may be, for example, two, three, or more elements. The other numbers used here do not necessarily mean that they are exactly limited to the number of elements mentioned. Rather, numerical differences up or down are possible.

[0052] The embodiments and constituent elements describing the storage containers apply accordingly to the proposed method, and vice versa.

[0053] Other possible embodiments of the storage container and / or method include combinations of constituent elements or embodiments not explicitly shown in relation to the examples described above or below. In this case, those skilled in the art may also add individual embodiments as improvements or supplements to each basic form of the storage container and / or method. [Brief explanation of the drawing]

[0054] Other advantageous embodiments of the storage container and / or method are subject to the dependent claims and the embodiments of the storage container and / or method described below. Preferred embodiments of the storage container and / or method will now be described in detail with reference to the accompanying drawings. [Figure 1] This is a schematic cross-sectional view showing an embodiment of a storage container. [Figure 2] Figure 1 is a schematic cross-sectional view showing an embodiment of a latent heat storage device for a storage container. [Figure 3]This is a detailed view III of Figure 1. [Figure 4] Figure 1 is a schematic block diagram of an embodiment of the method for operating the storage container.

[0055] Unless otherwise specified, identical elements or elements with the same function are given the same symbol in the diagrams.

[0056] Figure 1 shows a schematic cross-sectional view of an embodiment of storage container 1.

[0057] Storage container 1 can also be called a storage tank. Storage container 1 is suitable for containing the cryogenic agent H2. In this example, the cryogenic agent H2 is hydrogen, and will also be referred to as hydrogen below. Preferably, storage container 1 is suitable for containing liquid hydrogen H2 (boiling point: 1 bara: 20.268 K = -252.882 °C). Therefore, storage container 1 can also be called a hydrogen storage container or a hydrogen storage tank.

[0058] However, storage container 1 can also be used for other cryogenic liquids. Examples of cryogenic fluids or cryogenic liquids, or simply cryogenics, include, in addition to hydrogen (H2) mentioned above, liquid helium (He) (boiling point 1 bara: 4.222 K = -268.928 °C).

[0059] The storage container 1 may be a transport container. For example, liquid hydrogen (H2) can be transported using the storage container 1. The storage container 1 may be part of a vehicle, particularly a water vehicle. In this case, the storage container 1 is suitable for mobile applications. However, the storage container 1 can also be used in a stationary manner, for example, using construction technology.

[0060] For storage container 1 to be used in a marine environment, it may be necessary for storage container 1 to have a lifespan of 15 days in the event of a failure, assuming the operating pressure under maximum filling. That is, during this period, the pressure inside the inner container 3 must not exceed the maximum allowable pressure, and hydrogen H2 must not escape from storage container 1.

[0061] Currently, storage container 1 can only be filled to a certain extent with liquid hydrogen (H2) due to the required lifespan, which depends on the heat incidence and the thermodynamic equilibrium temperature of the stored liquid hydrogen (H2). Under typical conditions, only 70% to 80% of the geometric volume of storage container 1 can often be utilized for liquid hydrogen (H2) storage. This needs improvement.

[0062] The storage container 1 is configured to be rotationally symmetric with respect to an axis of symmetry or central axis 2. The central axis 2 is oriented perpendicular to the direction of gravity g. The storage container 1 includes a first container or inner container 3, which is also configured to be rotationally symmetric with respect to the central axis 2. The inner container 3 includes a tubular or cylindrical base area 4, which is also configured to be rotationally symmetric with respect to the central axis 2. The base area 4 may have a circular or approximately circular geometry when viewed in cross-section.

[0063] The base section 4 is closed on both sides by cover sections 5 and 6 at the end face. Cover sections 5 and 6 are curved. The first cover section 5 and the second cover section 6 are curved in opposite directions, so that cover sections 5 and 6 curve outward with respect to the base section 4. The inner container 3 is fluid-tight and especially airtight. The inner container 3 is made of special steel.

[0064] Liquid hydrogen (H2) is contained within the inner container 3. Within the inner container 3, there may be a gaseous zone 7 where the hydrogen (H2) is vaporized and a liquid zone 8 where the hydrogen (H2) is in liquid state, as long as the hydrogen (H2) is in a two-phase region. In other words, after being injected into the inner container 3, the hydrogen (H2) has two phases with different condensation states, namely liquid and gas. That is, there is a phase boundary 9 between the liquid hydrogen (H2) and the gaseous hydrogen (H2) within the inner container 3.

[0065] The inner container 3 is entirely located inside the second container or the outer container 10. Thus, the storage container 1 has a double wall. The outer container 10 is also configured rotationally symmetric with respect to the central axis 2. Like the inner container 3, the outer container 10 includes a tubular or cylindrical base area 11 that is configured rotationally symmetric with respect to the central axis 2. The base area 11 may have a circular or approximately circular geometry when viewed in cross-section.

[0066] The base area 11 is closed off at its end face by cover areas 12 and 13, respectively. In particular, a first cover area 12 and a second cover area 13 are provided. The cover areas 12 and 13 are curved in opposite directions, so that they curve outward with respect to the base area 11. The outer container 10 is fluid-tight and especially airtight. The outer container 10 is also made of special steel.

[0067] A gap 14 is positioned between the inner container 3 and the outer container 10, completely surrounding or encompassing the inner container 3. The gap 14 is subjected to a vacuum. In this case, "vacuum" specifically refers to a vacuum lower than 300 mbar, preferably 10 mbar. -3 Lower than mbar, more preferably 10 -7 It is understood that the pressure is lower than mbar. Thus, the storage container 1 is vacuum insulated or vacuum-heated. The fact that the gap 14 completely "encloses" or "encompasses" the inner container 3 means, in this case, that the gap 14 extends completely around the outer perimeter of the base area 4 on the one hand, and is also provided between both cover areas 5 and 12, and between both cover areas 6 and 13, on the other hand.

[0068] A shade or shield 15, particularly a so-called soft shield, is provided between the inner container 3 and the outer container 10. Thus, the shield 15 is positioned within the gap 14. The shield 15 is made of a material that conducts heat well, such as copper or aluminum. The shield 15 is fluid permeable, and preferably gas permeable. The shield 15 has a cylindrical base section 16 configured to be rotationally symmetric with respect to the central axis 2. The base section 16 is closed at its end face by a first cover section 17 and a second cover section 18.

[0069] A latent heat reservoir 19 is located inside the shield 15. In the arrangement shown in Figure 1, the latent heat reservoir 19 is located next to the inner container 3. Specifically, the latent heat reservoir 19 is located between the respective cover areas 6 and 18. The latent heat reservoir 19 is filled, at least regionally, with a phase change material N2 (PCM), which will be explained later. In this example, the phase change material N2 is nitrogen. However, the phase change material N2 may be, for example, argon.

[0070] In the following, it is assumed that the phase change material N2 is nitrogen. Therefore, in the following, the phase change material N2 will also be referred to as nitrogen. The latent heat reservoir 19 is connected to the shield 15, and in particular to the base area 16 of the shield 15, via a heat conductive member 20 that orbits the central axis 2. The heat conductive member 20 may be disc-shaped.

[0071] A heat transfer element or heat exchanger 21 is located inside the latent heat reservoir 19. The heat exchanger 21 is connected to an extraction pipe 22 to conduct heat, which communicates with the inner container 3 below the phase boundary 9, passes through the latent heat reservoir 19, and continues through the shield 15 and the outer container 10 to the perimeter 23 of the storage container 1.

[0072] The heat exchanger 21 is connected to the outlet piping 22, thereby allowing the outlet piping 22 to transfer heat to the heat exchanger 21 and vice versa. The heat exchanger 21 may be a metal plate welded or soldered to the outlet piping 22, and may be an aluminum plate or a copper plate in particular. The heat exchanger 21 may be composed of multiple such metal plates.

[0073] A discharge pipe 24 having a discharge valve 25 is led out from the latent heat storage unit 19. The discharge pipe 24 may pass inside the shield 15. The discharge pipe 24 may be coupled to the shield 15 to conduct heat. The discharge pipe 24 may be spiral or helical around a central axis 2 and be attached to the shield 15 on the inside or outside. The discharge valve 25 can release vaporized nitrogen N2 into the surrounding area 23.

[0074] Figure 2 shows a schematic cross-sectional view of the embodiment of the latent heat storage device 19 described above.

[0075] The latent heat reservoir 19 functions as a thermal buffer for the storage container 1. The latent heat reservoir 19 surrounds an internal space 26 containing a heat exchanger 21 that comes into contact with solid nitrogen N2. The latent heat reservoir 19 may be entirely or partially filled with solid nitrogen N2. The internal space 26 is at least partially or entirely filled with a thermally conductive and fluid-permeable material structure, in this embodiment with a knit material 27.

[0076] The knitted material 27 may be made from aluminum fibers and / or copper fibers. In particular, the knitted material 27 may be copper wool and / or aluminum wool. The knitted material 27 is coupled to the heat exchanger 21 in a thermal conduction manner. The knitted material 27 is impregnated with nitrogen N2. The knitted material 27, which has good thermal conductivity, ensures a good thermal transfer between the heat exchanger 21 and solid nitrogen N2.

[0077] Figure 3 shows a detailed diagram III of storage container 1 in Figure 1.

[0078] A thermal insulation member or heat insulating member 28 is provided within the gap 14, completely enclosing or surrounding the inner container 3. That is, the heat insulating member 28 surrounds not only the base area 4 of the inner container 3 but also the cover areas 5 and 6. The heat insulating member 28 serves to block heat. The heat insulating member 28 is multilayered; that is, it contains multiple layers or layers. Therefore, the heat insulating member 28 can also be called a multilayer heat insulating member or a multilayer thermal insulation member.

[0079] In particular, the thermal insulation member 28 is a so-called multilayer thermal insulation material (MLI). The thermal insulation member 28 includes multiple layers or sections arranged alternately, consisting of perforated and / or embossed aluminum foil 29 as reflectors and glass paper 30 as spacers between adjacent aluminum foils 29. The glass paper 30 may be perforated and / or punctured.

[0080] In Figure 3, only the two layers of aluminum foil 29 and the two layers of glass paper 30 are labeled. The glass paper 30 acts as a spacer between two adjacent layers of aluminum foil 29, thereby creating a vacuum in the gap 14 within the insulating member 28. The insulating member 28 abuts the inner container 3 on the outside.

[0081] The insulating member 28 partially or completely fills the gap 14 (as shown in Figure 3). The shield 15 may be embedded in the insulating member 28. That is, layers of aluminum foil 29 and glass paper 30 may be provided inside and outside the shield 15. In particular, the shield 15 is embedded in the outer layer of the insulating member 28. "Outside" here is understood to mean the area of ​​the outer container 10.

[0082] The functionality of storage container 1 is described below. In the normal operation of storage container 1, a substantially constant amount of liquid hydrogen H2 is extracted from the inner container 3 via the extraction pipe 22. As the liquid hydrogen H2 is guided through the latent heat reservoir 19, it absorbs heat Q from nitrogen N2 through the heat exchanger 21 and the nit material 27.

[0083] If nitrogen N2 is in a liquid state, it undergoes a phase transition from liquid to solid. If nitrogen N2 is already in a solid state, it remains in a solid state. That is, the nitrogen N2 contained in the latent heat reservoir 19 is solid during the normal operation of the storage container 1. At this time, the latent heat reservoir 19 is thermally separated from the inner container 3, at least partially.

[0084] When the extraction of liquid hydrogen (H2) is temporarily interrupted, solid nitrogen (N2) melts, causing a moderate pressure increase in the latent heat reservoir (19). As the solid nitrogen (N2) melts, it absorbs heat (Q) from the shield (15) via the heat conductive member (20). The shield (15) is cooled because the latent heat reservoir (19) is connected to the shield (15) via the heat conductive member (20).

[0085] When the extraction of liquid hydrogen (H2) is resumed, the reverse phase transition of nitrogen (N2) from liquid to solid occurs. This is because the liquid hydrogen (H2) flowing through the extraction pipe 22 absorbs heat Q from the liquid nitrogen (N2). Thus, in the normal operation of the storage container 1, this is a closed system.

[0086] If liquid hydrogen (H2) is not extracted for a relatively long period of time, solid nitrogen (N2) melts and eventually begins to boil and vaporize. In this case, gaseous nitrogen (N2) can be blown out into the surrounding area (23) via the blow-off pipe (24) and the blow-off valve (25). At this time, as described above, the blow-off pipe (24) can circulate spirally around the shield (15), and the low-temperature gaseous nitrogen (N2) further removes heat Q from the shield (15).

[0087] Under normal operation, the phase transition of nitrogen N2 from solid to liquid and vice versa prevents nitrogen N2 loss through the blowdown pipe 24 and blowdown valve 25, and / or prevents the selection of an excessively high maximum allowable pressure inside the latent heat reservoir 19. Heat injection into the inner vessel 3 is significantly reduced during failures by the nitrogen N2-cooled shield 15. This extends the lifespan of the hydrogen H2.

[0088] Thus, the latent heat storage container 19, including the heat exchanger 21, forms a closed system in which phase transitions from solid to liquid occur alternately during the normal operation of the storage container 1. Nitrogen N2 vaporizes and is blown out into the surroundings 23 only when a failure occurs, that is, when liquid hydrogen H2 is not extracted for a relatively long period of time.

[0089] The degree to which the storage container 1 can be filled with liquid hydrogen (H2) can be significantly increased compared to a storage container without this type of latent heat reservoir 19, so that a larger amount of hydrogen (H2) can be stored within the same design footprint for the storage container 1. The compact design of the storage container 1 thus obtained can be particularly advantageous for use in ships where the liquid hydrogen (H2) system is retrofitted. The latent heat reservoir 19 enables emergency cooling of the shield 15 and, consequently, the storage container 1.

[0090] Figure 4 shows a schematic block diagram of an embodiment of a method for operating the storage container 1.

[0091] In this method, in step S1, a portion of the liquid hydrogen H2 is removed from the storage container 1 via the extraction pipe 22. During step S1, the nitrogen N2 contained in the latent heat reservoir 19 undergoes a phase transition from liquid to solid due to the transfer of heat Q from nitrogen N2 to hydrogen H2. If the nitrogen N2 is already solid, it remains solid during step S1.

[0092] In step S2, step S1 is completed. That is, hydrogen H2 stops flowing through the extraction pipe 22. Step S2 can be performed until all nitrogen N2 has melted. In this way, during step S2, nitrogen N2 undergoes a phase transition from solid to liquid.

[0093] Preferably, in step S3, which is performed in parallel with steps S1 and S2, the latent heat reservoir 19 is fluid-separated from the surrounding area 23 of the storage container 1. The fluid separation of the latent heat reservoir 19 from the surrounding area 23 is released only when the nitrogen N2 has at least partially turned into a gas and an excessively high pressure rise occurs inside the latent heat reservoir 19. This can occur during a malfunction. When the gaseous nitrogen N2 reaches the maximum permissible pressure inside the latent heat reservoir 19, it is blown out to the surrounding area 23 through the blow-off pipe 24 and the blow-off valve 25.

[0094] During process S2, the heat Q required for the phase transition of nitrogen N2 from solid to liquid is removed from the shield 15 surrounding the inner container 3 of the storage container 1. This cools the shield 15.

[0095] Steps S1 to S3 are performed only during the normal operation of the storage container 1, and only in the event of a malfunction of the storage container 1 does the blow-off valve 25 of the storage container 1 open, thereby blowing gaseous nitrogen N2 into the surrounding area 23.

[0096] Although the present invention has been described using examples, it is possible to modify the present invention in various ways. [Explanation of symbols]

[0097] 1. Storage container 2 center axis 3 Inner container 4 Base Area 5. Coverage Area 6. Coverage Area 7. Gas Zone 8 Liquid Zones 9 phase boundary 10 Outer container 11 Base Area 12 Coverage Areas 13 Coverage Area 14 Gap 15 Shields 16 Base Area 17 Coverage Area 18 Coverage Areas 19 Latent heat storage 20 Heat conductive material 21 Heat exchanger 22 Output piping 23 Surroundings 24. Discharge piping 25. Blowing valve 26 Interior space 27 Knitted material 28 Insulation material 29 Aluminum foil 30 glass paper g direction of gravity H2 Hydrogen / Cryogenic Agent N2 Nitrogen / Phase Change Materials Q Heat S1 process S2 process S3 process

Claims

1. A storage container (1) for storing a cryogenic agent (H2), comprising an inner container (3) for containing the cryogenic agent (H2), a latent heat storage container (19) for containing a phase change material (N2), and an extraction pipe (22) for extracting only the liquid phase of the cryogenic agent (H2) from the inner container (3), wherein the extraction pipe (22) is coupled to the latent heat storage container (19) so that the liquid cryogenic agent (H2) contained in the extraction pipe (22) exchanges heat with the phase change material (N2), and the latent heat storage container (19) is fluidly connected to the surrounding area (23) of the storage container (1) only by a blowpipe (24).

2. The storage container according to claim 1, wherein the extraction pipe (22) is guided to pass through the latent heat storage device (19).

3. The storage container according to claim 1 or 2, wherein a heat exchanger (21) located inside the latent heat storage container (19) is attached to the outlet pipe (22).

4. The storage container according to any one of claims 1 to 3, wherein the latent heat storage container (19) is filled at least partially with a thermally conductive and fluid-permeable material structure, particularly with a knit material (27).

5. The storage container according to any one of claims 1 to 4, wherein the discharge pipe (24) has a discharge valve (25) for discharging the phase change material (N2) to the surrounding area (23).

6. A storage container according to any one of claims 1 to 5, further comprising an inner container (3) and a shield (15) surrounding the latent heat storage container (19), wherein the latent heat storage container (19) is coupled to the shield (15) to conduct heat.

7. The storage container according to claim 6, wherein the latent heat storage device (19) is positioned between the cover area (6) of the inner container (3) and the cover area (18) of the shield (15).

8. The storage container according to claim 6 or 7, wherein the blowing pipe (24) is coupled to the shield (15) to conduct heat.

9. The storage container according to claim 8, wherein the discharge pipe (24) spirals around the shield (15) either on the inside or outside.

10. The storage container according to any one of claims 6 to 9, further comprising an outer container (10) surrounding the shield (15).

11. The storage container according to claim 10, further comprising a multilayer heat insulating member (28) that at least partially fills the gap (14) provided between the inner container (3) and the outer container (10).

12. The storage container according to claim 11, wherein the shield (15) is embedded in the heat insulating member (28).

13. A method for operating a storage container (1) according to any one of claims 1 to 12 for storing a cryogenic agent (H2), comprising the following steps: a) A step (S1) in which the liquid cryogenic agent (H2) is removed from the storage container (1), wherein during step a), the phase change material (N2) contained in the latent heat storage container (19) of the storage container (1) undergoes a phase transition from liquid to solid by the transfer of heat (Q) from the phase change material (N2) to the liquid cryogenic agent (H2), or the phase change material (N2) remains solid during step a), b) A step (S2) to complete step a), in which the phase change material (N2) undergoes a phase transition from solid to liquid, c) A method comprising step (S3) in which the latent heat storage device (19) is fluidly separated from the surrounding area (23) of the storage container (1) during steps a) and b).

14. The method according to claim 13, wherein during step b), the heat (Q) necessary for the phase transition is removed from the shield (15) surrounding the inner container (3) of the storage container (1).

15. The method according to claim 13 or 14, wherein steps a) to c) are performed during the normal operation of the storage container (1), and only in the event of a malfunction of the storage container (1) the blow valve (25) of the storage container (1) is opened, thereby blowing the gaseous phase change material (N2) into the surroundings (23).

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