Storage container and method

Abstract

A storage container (1) for storing a cryogenic agent (H2), comprising 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 line (22) for extracting only the cryogenic agent (H2) from the inner container (3) wherein the extraction line (22) is operably connected to the latent heat reservoir (19), the phase change material (N2) is introduced into the extraction line (22) such that the cryogenic agent (H2) absorbed in the extraction line (22) exchanges heat with the phase change material (N2), and wherein the latent heat reservoir (19) can be fluidly connected to the surroundings (23) of the storage container (1) solely by means of the discharge line (24).

Description

[0001] The invention relates to a storage container for storing a cryogenic agent and a method for operating such a storage container.

[0002] The applicant has disclosed an internal double-walled storage container for liquid hydrogen, which has an outer container and an inner container arranged in the outer container for accommodating the liquid hydrogen. A vacuum is applied to the gap arranged between the inner container and the outer container. The gap can be filled at least in sections with an insulating material.

[0003] In order to use such storage vessels in a marine environment, in the event of a malfunction, the storage vessel may need to achieve a holding time of 15 days at maximum filling, starting from the operating pressure. This means that during this period, the maximum allowable pressure in the inner container must not be exceeded and no hydrogen must escape from the storage vessel.

[0004] Due to the holding time requirements, storage vessels can currently only be filled with liquid hydrogen to a certain extent, depending on the heat incidence and the thermodynamic equilibrium temperature of the stored liquid hydrogen. Under current typical conditions, sometimes only 70% to 80% of the geometric container volume of the storage vessel can be used to store liquid hydrogen. There is a need to improve this.

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

[0006] Therefore, a storage container for storing a cryogen is proposed. The storage container comprises an inner container for accommodating the cryogen, a latent heat storage for accommodating a phase change material, and an extraction line for extracting the cryogen only from the inner container, wherein the extraction line is operably connected to the latent heat storage so that the cryogen absorbed in the extraction line exchanges heat with the phase change material, and wherein the latent heat storage can be fluidically connected to the periphery of the storage container only by means of a discharge line.

[0007] Due to the provision of a latent heat storage, during the phase change from solid to liquid, the phase change enthalpy of the phase change material can be used, for example, to cool a shield surrounding the inner container or other parts of the storage container. Thus, the holding time of the cryogenic storage container can be extended. In particular, emergency cooling can be achieved. In addition, a higher degree of cryogenic filling in the inner container can also be achieved.

[0008] The storage container is also particularly suitable for transporting cryogens. Therefore, the storage container can also be referred to as a transport container. The storage container is preferably at least double-walled and comprises, in addition to the inner container, an outer container surrounding the inner container. Therefore, the storage container can also be referred to as a double-walled storage container. The storage container can be part of a vehicle, in particular part of a ship. In this case, the storage container is suitable for mobile use. However, the storage container can also be used stationarily, for example in construction technology.

[0009] The extraction line leads, for example, from the storage container to a consumer in the form of a fuel cell. For example, the consumer can supply power to an electric motor, which drives, for example, a propeller of a ship. The liquid cryogen can be evaporated before the consumer, so that the gaseous cryogen is supplied to the consumer at a suitable supply pressure and a suitable supply temperature.

[0010] The cryogen may be liquid hydrogen. Since the storage container is preferably suitable for containing liquid hydrogen, the storage container may also be referred to as a hydrogen storage container or a hydrogen storage tank. In this case, the term "cryogen" may be interchangeable with the term "hydrogen" and vice versa. However, the cryogen may also be liquid helium, liquid neon, etc.

[0011] The cryogen is contained in the inner container. As long as the cryogen is located in the two-phase region, a gas region with a vaporized cryogen and a liquid region with a liquid cryogen can be provided in the inner container. Therefore, after being filled into the inner container, the cryogen has two phases with different aggregation states, namely a liquid state and a gaseous state. That is to say, in the inner container, there is a phase boundary between the liquid cryogen and the gaseous cryogen. Only the liquid cryogen is extracted from the inner container through the extraction line. The end of the extraction line located on or in the inner container is arranged in the lower part of the inner container in the gravity direction or on the lower part of the inner container. The end is preferably located in or on the lower third of the inner container, and particularly preferably located in or on the lower sixth of the inner container. Particularly preferably, the end of the extraction line is spaced up to 30 mm from the lowest point of the inner container in the gravity direction, and more particularly preferably up to 20 mm.

[0012] The storage container is preferably configured rotationally symmetrically with respect to the axis of symmetry or the central axis. Thus, the inner container and the outer container can also be configured rotationally symmetrically with respect to the central axis. The storage container is preferably arranged such that the central axis extends perpendicularly to the direction of gravity. That is, the storage container is arranged horizontally. However, the storage container can also be arranged vertically. In this case, the central axis is oriented parallel to the direction of gravity.

[0013] The inner container is preferably cylindrical. The inner container has in particular a tubular or cylindrical base, which can be designed rotationally symmetrically with respect to the central axis. The base of the inner container is closed at the ends with two outwardly bent covers. However, this does not necessarily have to be provided in this way. The covers can also be designed in different ways. The inner container can also be referred to as an inner tank.

[0014] Latent heat storage can also be called phase change storage or phase change material storage. In this case, "latent heat storage" should be understood to be a special type of heat storage, which stores most of the thermal energy supplied to it in the form of latent heat, for example for a phase change from solid to liquid.

[0015] In particular, a phase change material is used which has a melting point higher than the storage and / or transportation temperature of the cryogen contained in the inner container.

[0016] Nitrogen is preferably used as phase change material. Therefore, in this case, the term "phase change material" can be replaced by the term "nitrogen". However, argon, for example, can also be used as phase change material.

[0017] The phase change material can be part of the latent heat storage and therefore also part of the storage container. The phase change material can realize a phase change from solid to liquid and from liquid to gas and vice versa. Preferably, in normal operation of the storage container, during the extraction of cryogen from the storage container, only a phase change between solid and liquid or between liquid and solid is provided. The phase change material absorbs heat during the phase change from solid to liquid and releases heat during the phase change from liquid to solid. In the phase change from liquid to solid, the heat required for this purpose can be taken away from the shield surrounding the inner container, thereby cooling the inner container. The shield can be part of the storage container.

[0018] In particular, the extraction line is thermally conductively connected to the latent heat storage, so that the cryogen flowing through the extraction line can extract heat from the phase change material, whereby the phase change material undergoes a phase change from liquid to solid. For example, if the cryogen is no longer extracted from the storage container within a short period of time, the phase change material performs a phase change from solid to liquid. In this case, the phase change material absorbs heat, which heat can be used in particular to cool the inner container, for example by means of the above-mentioned shield.

[0019] For example, the withdrawal line can be connected externally to the latent heat storage. However, the withdrawal line can also pass directly through the latent heat storage. In this case, the fact that the withdrawal line is "operably connected" to the latent heat storage is to be understood in particular that the withdrawal line can be in heat exchange with the latent heat storage in any desired manner, so that heat can be transferred from the latent heat storage to the withdrawal line and vice versa.

[0020] In normal operation of the above-mentioned storage container, the latent heat storage forms a closed system which is not connected to the surroundings. In this case, "normal operation" is to be understood as the extraction of cryogenic agent from the storage container and, if necessary, the extraction of cryogenic agent is interrupted for a short time. If the extraction of cryogenic agent is interrupted for a longer time, for example in the event of a malfunction of the storage container, the latent heat storage can be connected to the surrounding fluid by means of an extraction line, wherein the gaseous phase change material is released into the surroundings.

[0021] In this case, the latent heat store can be connected to the surroundings "exclusively" or "only" by means of the withdrawal line, which means that apart from the withdrawal line no further fluid connection between the latent heat store and the surroundings exists or cannot be produced.

[0022] However, during normal operation of the latent heat storage, a fluid connection of the latent heat storage with the surroundings does not occur. Only in the event of a fault is the latent heat storage fluidly connected to the surroundings via the extraction line. In this case, the fact that the latent heat storage is "fluidically connected" to the surroundings is to be understood in particular as meaning that the gaseous phase change material can be released from the latent heat storage into the surroundings via the extraction line. For example, when the maximum permissible pressure in the latent heat storage is exceeded, the extraction line discharges the gaseous phase change material into the surroundings.

[0023] According to one embodiment, the withdrawal line passes through the latent heat store.

[0024] The latent heat storage device can have, for example, a cylindrical geometry. The withdrawal line can pass through the latent heat storage device several times. For this purpose, the withdrawal line can be designed, for example, in a curved manner. However, the withdrawal line can also be spiral or helical. However, the withdrawal line can also pass directly through the latent heat storage device. Alternatively, the withdrawal line can also be connected to the latent heat storage device externally.

[0025] According to a further embodiment, a heat exchanger arranged in the latent heat store is attached to the withdrawal line.

[0026] The heat exchanger is preferably plate-shaped. The heat exchanger can be, for example, brazed or welded to the extraction line. The heat exchanger is made in particular of a material with good thermal conductivity, such as aluminum or copper. The heat exchanger can comprise a plurality of heat exchanger plates placed in the latent heat storage.

[0027] According to another embodiment, the latent heat storage is filled at least in sections with a heat-conducting, fluid-permeable material structure. This can be a woven, knitted or braided fabric, preferably metallic. The material structure can include metal threads or wires. Preferably, it is metal wool. Optionally, the material structure can also include smooth and / or structured metal sheets and / or metal foils. The material structure can be made of aluminum, an aluminum alloy, copper or a copper alloy.

[0028] In particular, the material structure can be connected to the heat exchanger. The material structure is impregnated with the phase change material. This achieves a particularly good contact of the phase change material with the material structure and thus also with the heat exchanger. Preferably, the material structure can be or include copper, a copper alloy, aluminum and / or an aluminum alloy wool. The material structure with good thermal conductivity ensures a good heat transfer between the heat exchanger and the solid phase change material.

[0029] According to another embodiment, the discharge line comprises a discharge valve for discharging the phase change material into the surroundings.

[0030] The discharge valve preferably opens at a predetermined pressure. For example, a maximum permissible pressure is specified for the latent heat storage. When the phase change material evaporates, once this maximum permissible pressure is reached, the discharge valve opens and the gaseous phase change material is discharged into the surroundings.

[0031] According to a further embodiment, the storage container further comprises a shroud which surrounds the inner container and the latent heat store, wherein the latent heat store is connected to the shroud in a heat-conducting manner.

[0032] The latent heat storage device can be part of the shield and vice versa. The shield is preferably made of a material with good thermal conductivity, such as aluminum or copper. The shield has in particular a tubular base, which can be designed rotationally symmetrically with respect to the central axis. At the end side, the shield is closed by two cover parts. The cover parts can be bent outwards relative to the base. The inner container and the latent heat storage device are arranged in the shield. The latent heat storage device can be connected to the shield in a thermally conductive manner, for example by means of a heat conducting element or a plurality of heat conducting elements. Therefore, the phase change material can carry away heat from the shield via the heat conducting element or via a plurality of heat conducting elements, so that the shield is cooled.

[0033] According to a further embodiment, the latent heat storage is arranged between the cover of the inner container and the cover of the hood.

[0034] As mentioned above, the inner container has two covers, in particular a first cover and a second cover. Correspondingly, the hood also has two covers, in particular a first cover and a second cover. When viewed along the central axis, the latent heat storage is particularly preferably arranged between the second cover of the inner container and the second cover of the hood.

[0035] According to a further embodiment, the discharge line is thermally conductively connected to the shield.

[0036] This improves the heat transfer between the discharge line and the shroud. The cold gaseous phase change material can carry away heat from the shroud, thereby further cooling the shroud. For example, the discharge line is brazed or welded to the shroud. In this case, the discharge line can be arranged inside the shroud or outside the shroud. In this case, "inside" the shroud means facing the inner container. In this case, "outside" the shroud means facing away from the inner container.

[0037] According to another embodiment, the discharge line extends helically inwardly or outwardly around the shroud.

[0038] This lengthens the exhaust line, thereby improving heat transfer from the exhaust gaseous phase change material to the shroud.

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

[0040] The outer container has in particular a tubular base, which can be designed rotationally symmetrically with respect to the central axis. At the end, the outer container is closed by means of two covers, in particular by means of a first cover and a second cover. The covers are preferably bent outwards relative to the base. The outer container surrounds the hood, which in turn surrounds the inner container and the latent heat storage. The hood is thus arranged completely within the outer container.

[0041] According to another embodiment, the storage container further comprises a multi-layer insulation element which at least partially fills a gap provided between the inner container and the outer container.

[0042] The insulating element may also be referred to as a spacer element. The insulating element serves for the insulation of the inner container. In particular, the above-mentioned shield is arranged in the gap. The gap may be completely filled by the insulating element and the shield. Optionally, the gap may also be only partially filled with the insulating element. The insulating element preferably surrounds the base and the cover of the inner container. The insulating element preferably comprises a plurality of stacks or a plurality of layers. In particular, the insulating element is a so-called multi-layer insulation (MLI). The insulating element comprises a plurality of alternately arranged layers or stacks of perforated and / or embossed aluminum foil as reflector and glass paper as spacer between adjacent aluminum foils. The glass paper may be perforated and / or punched.

[0043] According to a further embodiment, the shield is embedded in the insulating element.

[0044] This means in particular that the layers of aluminum foil and cellophane can be arranged inside and outside the shield. In particular, the shield is embedded in the outer layer of the insulation element. Here, "outside" is to be understood as in the region or direction of the outer container.

[0045] Furthermore, a method for operating such a storage container for storing a cryogen is proposed. The method comprises the following steps: a) extracting liquid cryogen from the storage container, wherein during step a), a phase change material contained in a latent heat storage of the storage container undergoes a phase change from liquid to solid by transferring heat from the phase change material to the liquid cryogen, or wherein the phase change material remains solid during step a), b) completing step a), wherein the phase change material undergoes a phase change from solid to liquid, and c) during steps a) and b), separating the latent heat storage from the surrounding fluid of the storage container.

[0046] In step a), in particular, a portion of the liquid cryogen is extracted from the storage container via an extraction line. During step a), the phase change material absorbed in the latent heat storage undergoes a phase change from liquid to solid by transferring heat from the phase change material to the cryogen. In the case where the phase change material is already solid, the phase change material remains solid during step a). In this case, heat is also further taken away from the phase change material. In step b), step a) ends. This means that, at least for a short time, no cryogen flows through the extraction line anymore. Step b) can be performed until the entire phase change material melts. In particular, step b) can be performed until the maximum permissible pressure as described above is reached in the latent heat storage. Therefore, during step b), the phase change material undergoes a phase change from solid to liquid, or maintains its solid aggregate state. Step c) is preferably performed in parallel with steps a) and b). That is, during steps a) and b), the latent heat storage according to step c) is separated from the surrounding fluid of the storage container. That is, during steps a) to c), the discharge valve is always closed. The separation of the latent heat storage from the surrounding fluid is only eliminated when the phase change material is at least partially gaseous and the maximum permissible pressure in the latent heat storage is exceeded. This can occur, for example, during a malfunction of the storage container, where cryogenic agent is no longer extracted from the inner container for a long time. The gaseous phase change material is then discharged to the surroundings via the discharge line and the discharge valve.

[0047] According to one embodiment, during step b), the heat required for the phase change is removed from the shroud surrounding the inner container of the storage container.

[0048] In particular, during step b), the heat required for the phase change from solid to liquid is taken away from the shield. As a result, the shield is cooled.

[0049] According to another embodiment, steps a) to c) are performed during normal operation of the storage container, wherein only when a malfunction occurs in the storage container is the discharge valve of the storage container opened, whereby the gaseous phase change material is discharged to the surroundings.

[0050] "Normal operation" of the storage container is understood to mean that liquid cryogen is extracted from the storage container. However, normal operation may also include brief interruptions in the extraction of liquid cryogen. A fault occurs when the phase change material undergoes a phase change from liquid to gaseous state and the pressure in the latent heat storage rises above the maximum permissible pressure. That is, only in the event of a fault is the latent heat storage connected to the surroundings via the discharge valve to discharge the gaseous phase change material.

[0051] "One" is not necessarily to be understood here as being limited to exactly one element. On the contrary, a plurality of elements, for example two, three or more, may also be provided. All other counting words used here are also not to be understood as necessarily implementing an exact limitation to an exactly corresponding number of elements. On the contrary, upward and downward numerical deviations are possible.

[0052] The embodiments and features described for the storage container apply correspondingly to the proposed method and vice versa.

[0053] Other possible implementations of storage container and / or method also include the combination of features or embodiments not explicitly mentioned previously or hereinafter described with respect to the embodiment. In this case, those skilled in the art will also add a single aspect as an improvement or supplement to the corresponding basic form of storage container and / or method.

[0054] Further advantageous embodiments of the storage container and / or the method are the subject matter of the dependent claims and of 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 with reference to the drawings using preferred embodiments.

[0055] Figure 1 A schematic cross-sectional view of an embodiment of a storage container is shown;

[0056] Figure 2 Shown is the Figure 1 A schematic cross-sectional view of an embodiment of a latent heat storage of a storage container;

[0057] Figure 3 Shown according to Figure 1 Detailed view III; and

[0058] Figure 4 Shown according to Figure 1 Schematic block diagram of an embodiment of a method for operating a storage container.

[0059] In the figures, identical elements or elements having the same function are provided with the same reference numerals unless otherwise indicated.

[0060] Figure 1 A schematic sectional view of an embodiment of a storage container 1 is shown.

[0061] The storage container 1 may also be referred to as a storage tank. The storage container 1 is suitable for containing a cryogenic agent H2. In this case, the cryogenic agent H2 is hydrogen, also referred to as hydrogen hereinafter. The storage container 1 is preferably suitable for containing liquid hydrogen H2 (boiling point: 1 bar: 20.268K = -252.882°C). Therefore, the storage container 1 may also be referred to as a hydrogen storage container or a hydrogen storage tank.

[0062] However, the storage container 1 can also be used for other cryogenic liquids. In addition to the above-mentioned hydrogen H2, an example of a cryogenic fluid or cryogenic liquid or simply a cryogen is liquid helium He (boiling point 1 bar: 4.222K=-268.928°C).

[0063] The storage container 1 can be a transport container. For example, liquid hydrogen H2 can be transported in the storage container 1. The storage container 1 can be part of a vehicle, in particular part of a ship. In this case, the storage container 1 is suitable for mobile applications. However, the storage container 1 can also be used stationarily, for example in building technology.

[0064] In order to use the storage container 1 in a marine environment, the storage container 1 must be filled to a maximum of 15 days from the operating pressure in the event of a fault. This means that during this period, the maximum permissible pressure in the inner container 3 must not be exceeded and no hydrogen H2 must escape from the storage container 1.

[0065] Due to the holding time requirements, the storage container 1 can currently only be filled with liquid hydrogen H2 to a certain extent, depending on the heat input and the thermodynamic equilibrium temperature of the stored liquid hydrogen H2. Under typical conditions today, sometimes only 70% to 80% of the geometric container volume of the storage container 1 can be used to store liquid hydrogen H2. There is a need to improve this.

[0066] The storage container 1 is designed rotationally symmetrically with respect to an axis of symmetry or central axis 2. The central axis 2 is oriented perpendicularly to the direction of gravity g. The storage container 1 comprises a first container or inner container 3, which is also designed rotationally symmetrically with respect to the central axis 2. The inner container 3 comprises a tubular or cylindrical base 4, which is also designed rotationally symmetrically with respect to the central axis 2. The cross section of the base 4 can have a circular or approximately circular geometry.

[0067] The base 4 is closed at both ends by a cover 5, 6 in each case. The cover 5, 6 is arched. The first cover 5 and the second cover 6 are bent in opposite directions so that the cover 5, 6 are bent outward relative to the base 4. The inner container 3 is fluid-tight, in particular gas-tight. The inner container 3 is made of stainless steel.

[0068] Liquid hydrogen H2 is contained in the inner container 3. As long as the hydrogen H2 is in a two-phase region, a gas region 7 having evaporated hydrogen H2 and a liquid region 8 having liquid hydrogen H2 can be provided in the inner container 3. Therefore, after being filled in the inner container 3, the hydrogen H2 has two phases having different aggregation states, namely, a liquid state and a gaseous state. That is, in the inner container 3, there is a phase boundary 9 between the liquid hydrogen H2 and the gaseous hydrogen H2.

[0069] The inner container 3 is completely arranged in the second container or outer container 10. Therefore, the storage container 1 is double-walled. The outer container 10 is also configured to be rotationally symmetrical with respect to the central axis 2. Like the inner container 3, the outer container 10 includes a tubular or cylindrical base 11 that is rotationally symmetrical with respect to the central axis 2. The cross section of the base 11 can have a circular or approximately circular geometry.

[0070] The end sides of the base 11 are closed in each case by a cover 12, 13. In particular, a first cover 12 and a second cover 13 are provided. The covers 12, 13 are bent in opposite directions so that the covers 12, 13 are bent outwardly relative to the base 11. The outer container 10 is fluid-tight, in particular gas-tight. The outer container 10 is also made of stainless steel.

[0071] Between the inner container 3 and the outer container 10, a gap 14 is provided which completely surrounds or encloses the inner container 3. A vacuum is applied to the gap 14. In this case, "vacuum" means in particular less than 300 mbar, preferably less than 10 -3 mbar, more preferably less than 10 -7 mbar pressure. The storage container 1 is thus vacuum-insulated or vacuum-isolated. In this case, the fact that the gap 14 completely "surrounds" or "wraps" the inner container 3 means that the gap 14 extends completely around the base 4 circumferentially on the one hand and is also arranged between the two cover parts 5, 12 and between the two cover parts 6, 13 on the other hand.

[0072] A shield or hood 15, in particular a so-called soft hood, is arranged between the inner container 3 and the outer container 10. The hood 15 is therefore placed in the gap 14. The hood 15 is made of a material with good thermal conductivity, for example copper or aluminum. The hood 15 is preferably fluid-permeable, in particular gas-permeable. The hood 15 has a cylindrical base 16 which is rotationally symmetrical with respect to the center axis 2. The base 16 is closed at the end by a first cover 17 and a second cover 18.

[0073] The latent heat storage 19 is placed in the shield 15. Figure 1 In the orientation of the inner container 3, the latent heat storage 19 is placed next to the inner container 3. In particular, the latent heat storage 19 is arranged between the cover parts 6, 18. The latent heat storage 19 is filled at least sectionally with a phase change material N2 (English: Phase Change Material, PCM), which will be explained further below. In this case, the phase change material N2 is nitrogen. However, the phase change material N2 can also be, for example, argon.

[0074] In the following, it is assumed that the phase change material N2 is nitrogen. Therefore, the phase change material N2 is referred to as nitrogen in the following. The latent heat storage 19 is connected to the shield 15, in particular to the base 16 of the shield 15, by a heat conducting element 20 rotating around the central axis 2. The heat conducting element 20 can be disc-shaped.

[0075] A heat exchanger or heat exchanger 21 is arranged in the latent heat store 19. The heat exchanger 21 is connected thermally conductively to a withdrawal line 22 which opens below the phase boundary 9 into the inner container 3, through the latent heat store 19 and through the hood 15 and the outer container 10 into the surroundings 23 of the storage container 1.

[0076] The heat exchanger 21 is connected to the extraction line 22 so that the extraction line 22 can transfer heat to the heat exchanger 21 and vice versa. The heat exchanger 21 can be a metal plate, in particular an aluminum plate or a copper plate, welded or brazed to the extraction line 22. The heat exchanger 21 can also be composed of several such metal plates.

[0077] A discharge line 24 with a discharge valve 25 discharges from the latent heat storage 19. The discharge line 24 may be guided inside the hood 15. The discharge line 24 may be connected to the hood 15 in a heat-conducting manner. The discharge line 24 may extend helically or spirally around the central axis 2 and may be fixed inside or outside the hood 15. The discharge valve 25 may discharge the evaporated nitrogen N2 to the surroundings 23.

[0078] Figure 2 A schematic sectional view of an embodiment of a latent heat storage 19 as described above is shown.

[0079] The latent heat storage 19 serves as a thermal buffer for the storage container 1. The latent heat storage 19 encloses an interior space 26 in which the heat exchanger 21 is accommodated, which is in contact with the solid nitrogen N2. The latent heat storage 19 can be completely or partially filled with solid nitrogen N2. The interior space 26 is at least partially or completely filled with a heat-conducting, fluid-permeable material structure, for example a knitted fabric 27 in this embodiment.

[0080] The knitted fabric 27 can be made of aluminum wire and / or copper wire. In particular, the knitted fabric 27 can be copper and / or aluminum wool. The knitted fabric 27 is thermally conductively connected to the heat exchanger 21. The knitted fabric 27 is impregnated with nitrogen N2. The knitted fabric 27 with good thermal conductivity ensures good heat transfer between the heat exchanger 21 and the solid nitrogen N2.

[0081] Figure 3 Shown according to Figure 1 Detailed view of storage container 1 III.

[0082] A heat insulating element or insulation element 28 which completely wraps or surrounds the inner container 3 is arranged in the gap 14. That is, the insulation element 28 surrounds the base 4 and the cover 5, 6 of the inner container 3. The insulation element 28 is used for thermal insulation. The insulation element 28 is multi-layered. That is, the insulation element 28 includes a plurality of stacks or layers. Therefore, the insulation element 28 can also be referred to as a multi-layer insulation element or a multi-layer heat insulation element.

[0083] In particular, the insulation element 28 is a so-called multi-layer insulation (MLI). The insulation element 28 comprises a plurality of alternately arranged layers or stacks of perforated and / or embossed aluminum foils 29 as reflectors and cellophane 30 as spacers between adjacent aluminum foils 29. The cellophane 30 may be perforated and / or holed.

[0084] exist Figure 3 In the embodiment, only two layers of aluminum foil 29 and two layers of cellophane 30 are each provided with a reference number. The cellophane 30 serves as a spacer between two adjacent aluminum foils 29, whereby the insulating element 28 can be subjected to the vacuum prevailing in the gap 14. The insulating element 28 rests on the outside of the inner container 3.

[0085] The insulating element 28 may partially or completely fill the gap 14, such as Figure 3 As shown. The shield 15 can be embedded in the insulating element 28. This means that the layers of aluminum foil 29 and cellophane 30 can be arranged inside and outside the shield 15. In particular, the shield 15 is embedded in the outer layer of the insulating element 28. "Outside" here is understood to be in the region of the outer container 10.

[0086] The function of the storage container 1 is explained below. During normal operation of the storage container 1, liquid hydrogen H2 is extracted substantially constantly from the inner container 3 via the extraction line 22. When the liquid hydrogen H2 passes through the latent heat storage 19, the latent heat storage 19 removes heat Q from the nitrogen N2 via the heat exchanger 21 and the knitted fabric 27.

[0087] In the case where the nitrogen N2 is in a liquid state, the nitrogen N2 undergoes a phase change from a liquid state to a solid state. In the case where the nitrogen N2 is already in a solid state, it remains in a solid state. That is, in normal operation of the storage container 1, the nitrogen N2 absorbed in the latent heat storage 19 is solid. In this case, the latent heat storage 19 is at least partially thermally separated from the inner container 3.

[0088] If liquid hydrogen H2 is no longer extracted within a short period of time, the solid nitrogen N2 melts and the pressure in the latent heat storage 19 increases moderately. When the solid nitrogen N2 melts, it takes away heat Q from the shield 15 through the heat conducting element 20. Since the latent heat storage 19 is connected to the shield 15 through the heat conducting element 20, the shield 15 is cooled.

[0089] If the extraction of liquid hydrogen H2 is subsequently resumed, a reverse phase transition of the nitrogen N2 from liquid to solid occurs, since the liquid hydrogen H2 flowing through the extraction line 22 removes heat Q from the liquid nitrogen N2. Therefore, in normal operation of the storage vessel 1, it is a closed system.

[0090] If liquid hydrogen H2 is no longer extracted for a long time, the solid nitrogen N2 melts, starts to boil and finally evaporates. Then, the gaseous nitrogen N2 can be discharged to the surroundings 23 through the discharge line 24 and the discharge valve 25. As mentioned above, the discharge line 24 can spiral around the shield 15, wherein the cold gaseous nitrogen N2 further removes heat Q from the shield 15.

[0091] In normal operation, the phase change of the nitrogen N2 from solid to liquid (and vice versa) prevents the loss of nitrogen N2 via the discharge line 24 and the discharge valve 25 and / or the necessity to select the maximum permissible pressure in the latent heat storage 19 too high. During an accident, the shield 15 cooled by the nitrogen N2 significantly reduces the heat input into the inner container 3. This increases the retention time of the hydrogen H2.

[0092] Thus, in normal operation of the storage container 1, the latent heat storage 19 together with the heat exchanger 21 forms a closed system in which the phase change from solid to liquid takes place alternately. Only in the event of a malfunction, i.e. when no liquid hydrogen H2 is extracted for a long time, does the nitrogen N2 evaporate and is blown into the surroundings 23.

[0093] Compared to a storage container 1 without such a latent heat storage 19, the filling degree of the storage container 1 with liquid hydrogen H2 can be significantly increased, so that a greater mass of hydrogen H2 can be stored under the same structural space (English: Footprint) of the storage container 1. The compact structure of the storage container 1 obtained in this way is particularly advantageous for use on ships retrofitted with liquid hydrogen H2 systems. The latent heat storage 19 in particular allows emergency cooling of the shield 15 and thus also of the storage container 1.

[0094] Figure 4 A schematic block diagram of an embodiment of a method for operating a storage container 1 is shown.

[0095] In the method, in step S1, a portion of liquid hydrogen H2 is extracted from the storage container 1 through the extraction line 22. During step S1, the nitrogen N2 absorbed in the latent heat storage 19 undergoes a phase change from liquid to solid by transferring heat Q from the nitrogen N2 to the hydrogen H2. In the case where the nitrogen N2 is already solid, the nitrogen N2 remains solid during step S1.

[0096] In step S2, step S1 ends. This means that no more hydrogen H2 flows through the extraction line 22. Step S2 can be performed until all the nitrogen N2 is melted. Therefore, during step S2, the nitrogen N2 undergoes a phase change from solid to liquid.

[0097] In step S3, which is preferably performed in parallel with steps S1, S2, the latent heat storage 19 is fluidically separated from the surroundings 23 of the storage container 1. The fluid separation of the latent heat storage 19 from the surroundings 23 is only released when the nitrogen N2 is at least partially gaseous and an excessively high pressure builds up in the latent heat storage 19. This can occur during an accident. When the maximum permissible pressure in the latent heat storage 19 is reached, the gaseous nitrogen N2 is then discharged to the surroundings 23 via the discharge line 24 and the discharge valve 25.

[0098] During step S2, the heat Q required for the phase change of the nitrogen N2 from solid to liquid is taken away from the hood 15 surrounding the inner container 3 of the storage vessel 1. As a result, the hood 15 is cooled.

[0099] In particular, steps S1 to S3 are performed only during normal operation of the storage container 1 , and the discharge valve 25 of the storage container 1 is opened only when a malfunction occurs in the storage container, whereby the gaseous nitrogen N2 is discharged to the surroundings 23 .

[0100] Although the invention has been described on the basis of embodiments, it can be modified in many ways.

[0101] Reference numerals used

[0102] 1 Storage container

[0103] 2 Central axis

[0104] 3. Inner container

[0105] 4 Base

[0106] 5 cover

[0107] 6 cover

[0108] 7 Gas Zone

[0109] 8 Liquid Zone

[0110] 9 Phase Boundary

[0111] 10 Outer container

[0112] 11 Base

[0113] 12 cover

[0114] 13 cover

[0115] 14 Gap

[0116] 15 Shield

[0117] 16 base

[0118] 17 cover

[0119] 18 cover

[0120] 19 Latent heat storage

[0121] 20 Thermal Conductive Components

[0122] 21 Heat exchanger

[0123] 22 Extraction pipeline

[0124] 23 around

[0125] 24 Discharge line

[0126] 25 Drain valve

[0127] 26 Interior Space

[0128] 27 Knitted fabrics

[0129] 28 Insulation elements

[0130] 29 Aluminum foil

[0131] 30 Cellophane

[0132] g direction of gravity

[0133] H2 Hydrogen / Cryogenic Agent

[0134] N2 nitrogen / phase change material

[0135] Q Heat

[0136] S1 Step

[0137] S2 Step

[0138] S3 Steps

Claims

1. A storage container (1) for storing a cryogen (H2), comprising an inner container (3) for containing the cryogen (H2), a latent heat storage (19) for containing a phase change material (N2), and an extraction pipeline (22) for extracting only the liquid phase of the cryogen (H2) from the inner container (3), wherein: The extraction line (22) is operatively connected to the latent heat storage (19) so that the liquid cryogen (H2) absorbed in the extraction line (22) exchanges heat with the phase change material (N2), and wherein the latent heat storage (19) can be fluidically connected to the surroundings (23) of the storage container (1) only by means of a discharge line (24).

2. The storage container according to claim 1, wherein: The withdrawal line (22) passes through the latent heat storage (19).

3. The storage container according to claim 1 or 2, wherein: A heat exchanger (21) arranged in the latent heat storage (19) is attached to the extraction line (22).

4. The storage container according to any one of claims 1 to 3, wherein: The latent heat storage (19) is filled at least in sections with a thermally conductive, fluid-permeable material structure, in particular a knitted fabric (27).

5. The storage container according to any one of claims 1 to 4, wherein: The discharge line (24) comprises a discharge valve (25) for discharging the phase change material (N2) into the environment (23).

6. The storage container according to any one of claims 1 to 5, further comprising a shield (15) surrounding the inner container (3) and the latent heat storage (19), wherein: The latent heat storage (19) is thermally connected to the shield (15).

7. The storage container according to claim 6, wherein: The latent heat storage (19) is arranged between the cover (6) of the inner container (3) and the cover (18) of the protective cover (15).

8. The storage container according to claim 6 or 7, wherein: The discharge line (24) is thermally conductively connected to the shield (15).

9. The storage container according to claim 8, wherein: The discharge line (24) extends spirally inwardly or outwardly around the shroud (15).

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

11. The storage container according to claim 10, further comprising a multi-layer insulation element (28) at least sectionally filling a 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 insulating element (28).

13. A method for operating a storage container (1) for storing a cryogen (H2) according to any one of claims 1 to 12, comprising the following steps: a) extracting (S1) liquid cryogen (H2) from the storage container (1), wherein: During step a), a phase change material (N2) contained in a latent heat storage (19) of the storage container (1) undergoes a phase change from liquid to solid by transferring heat (Q) from the phase change material (N2) to the liquid cryogen (H2), or wherein the phase change material (N2) remains solid during step a), b) completing step a) (S2), wherein the phase change material (N2) undergoes a phase change from solid to liquid, and c) During steps a) and b), the latent heat storage (19) is separated (S3) from the surrounding (23) fluid of the storage container (1).

14. The method according to claim 13, wherein: During step b), the heat (Q) required for the phase change is removed from the hood (15) surrounding the inner container (3) of the storage vessel (1).

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

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