Storage container and method

Abstract

A storage container (1) for storing a cryogen (H2), comprising an inner container (3) for receiving the cryogen (H2), and a withdrawal apparatus (16) for withdrawing a liquid phase (LH2) of the cryogen (H2) from the inner container (3), wherein the withdrawal apparatus (16) comprises a withdrawal line (17) which is fluidically connected to the inner container (3), an inner barrier (21) in which the withdrawal line (17) is at least partially accommodated, an outer barrier (30) in which the inner barrier (21) is at least partially accommodated, and a leakage detection device (28) which is configured to detect, on the basis of a pressure change within an inner volume (23) enclosed by the inner barrier (21) and / or on the basis of a pressure change within an outer volume (32) enclosed by the outer barrier (30), whether the withdrawal line (17), the inner barrier (21) and / or the outer barrier (30) has a leak. The inner volume (23) is filled with a detection gas (He), wherein the detection gas (He) has an overpressure relative to the outer volume (32).

Description

[0001] The invention relates to a storage container for storing a cryogen, and to a method for detecting a leak in such a storage container.

[0002] According to internal findings, storage containers for liquid hydrogen have an inner container in which the liquid hydrogen is held and an outer container in which the inner container is arranged. A multilayer thermal insulating element is provided between the inner container and the outer container. To extract liquid hydrogen, an extraction line for extracting the liquid hydrogen extends from the underside of the inner container. To extract gaseous hydrogen, an extraction line for extracting the gaseous hydrogen extends from the top of the inner container. The extraction line runs through the outer container. A valve, in particular a shut-off valve, is installed in the extraction line.

[0003] The extraction line upstream of the valve is the most critical for leaks. If a leak occurs in this region in the extraction line, this can lead to the entire storage container emptying. As a result, the hydrogen can come into contact with the thermal insulating element and damage it. The outer container cools down to such an extent that air constituents condense on it. These condensed air constituents drip into a drip pan below the storage container and evaporate. This continues until all the liquid hydrogen, which can have a mass of several tons, has evaporated and been vented via emergency relief valves of the storage container. If the storage container has a foundation that cannot withstand cryogenic temperatures, it will be cooled far beyond its design temperature and destroyed. This applies, for example, to the use of carbon steels, often used in shipbuilding, as a material for the foundation. This must be improved.

[0004] DE 103 35 245 A1 relates to a cryotank system for a motor vehicle. The system has one or more test layers with test devices for monitoring the pressure within each test layer. This allows leaks or failures of the cryotank system to be detected.

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

[0006] Accordingly, a storage container for storing a cryogen is proposed. The storage container comprises an inner container for accommodating the cryogen and an extraction apparatus for extracting the cryogen from the inner container, wherein the extraction apparatus comprises: - an extraction line which is fluidically connected to the inner container, - an inner barrier in which the extraction line is at least partially accommodated and which encloses an inner volume, - an outer barrier in which the inner barrier is at least partially accommodated and which encloses an outer volume, wherein the inner volume is filled with a detection gas, and wherein the detection gas has an overpressure relative to the outer volume, and - a leakage detection device configured to detect, on the basis of a pressure change within the inner volume and / or on the basis of a pressure change within the outer volume, whether the extraction line, the inner barrier, and / or the outer barrier have a leak.

[0007] Due to the extraction line being accommodated in the inner barrier, in the event of a leak in the extraction line the cryogen flows into the inner barrier and is thus contained. The cryogen thus cannot penetrate into the outer volume. Due to the extraction apparatus having a leakage detection device, it is possible to detect at an early stage whether the extraction line, the inner barrier and / or the outer barrier are damaged.

[0008] The cryogen can be hydrogen. Therefore, the term "cryogen" can in the present case be replaced by the term "hydrogen", and vice versa. However, the cryogen can also be helium or the like. The storage container can also be referred to as a hydrogen storage container. Preferably, the storage container provides a gas zone filled with a gaseous phase of the cryogen and a liquid zone filled with the liquid phase of the cryogen. A phase boundary is provided between the gas zone and the liquid zone. The gas zone is characterized in particular by its ability to absorb the gaseous phase. The liquid zone is characterized in particular by its ability to absorb the liquid phase. The liquid phase of the cryogen is therefore located in the liquid zone within the storage container. The gaseous phase of the cryogen is therefore located in the gas zone. The phase boundary separates the gaseous phase from the liquid phase. The gaseous phase, viewed along a direction of the gravitational force, is located above the liquid phase. The extraction apparatus can be used to extract the liquid phase, the gaseous phase or both phases from the storage container. The cryogen preferably has a pressure of 2 to 20 bara, particularly preferably of 2 to 17 bara.

[0009] The liquid phase is preferably liquid hydrogen. Accordingly, the term "liquid phase" can be replaced by the term "liquid hydrogen", and vice versa. The gaseous phase is preferably gaseous hydrogen. Accordingly, the term "gaseous phase" can be replaced by the term "gaseous hydrogen", and vice versa.

[0010] The extraction apparatus is preferably provided on the underside of the inner container, with the extraction line extending from the liquid zone and / or gas zone. Alternatively, the extraction apparatus can be provided on the top of the inner container, with the extraction line extending from the gas zone. Due to its hydrostatic pressure, the liquid phase flows from the liquid zone into the extraction line. The fact that the extraction line is "fluidically connected" to the inner container means here in particular that the liquid and / or gaseous phase can flow from the inner container, in particular from the liquid zone or the gas zone, into the extraction line.

[0011] The inner barrier is preferably tubular. The inner barrier follows the course of the extraction line. The extraction line is enclosed or encapsulated by the inner barrier. However, this does not rule out the possibility that the extraction line may also project from the inner barrier. The outer barrier is preferably also tubular. The inner barrier passes through the outer barrier, wherein the extraction line passes through the inner barrier. This results in a three-layer structure of the extraction apparatus, wherein the three-layer structure comprises the extraction line, the inner barrier and the outer barrier. The inner barrier is at least partially enclosed or encapsulated by the outer barrier. However, this does not out the possibility that the inner barrier may project from the outer barrier.

[0012] The inner barrier encloses the inner volume. The outer barrier encloses the outer volume. The inner volume is arranged at least partially within the outer volume. The outer volume thus encloses the inner volume, at least partially. Preferably, the inner volume is filled with gas. The inner volume can be filled with a detection gas, for example in the form of helium. The outer barrier is preferably subjected to a vacuum.

[0013] Depending on whether the extraction line, the inner barrier and / or the outer barrier have a leak, a pressure change will occur within the inner volume and / or within the outer volume. Depending on whether there is only a pressure change in the inner volume or even a pressure change in both the inner and outer volumes, the leakage detection device can detect or ascertain exactly where the leak is located. Accordingly, "detection" in this context means, in particular, that the leakage detection device can provide information, based on the pressure change or changes, as to whether the extraction line, the inner barrier and / or the outer barrier have a leak.

[0014] In this context, "pressure change" can refer not only to a pressure increase or rise but also to a pressure decrease or drop in the inner volume and / or the outer volume. In this context, a "leak" can be understood as an opening, a crack, a break or the like in the extraction line, the inner barrier and / or the outer barrier. For example, a leak in the inner barrier causes the inner volume to be put into fluidic connection with the outer volume.

[0015] According to one embodiment, the storage container has an outer container that encloses the inner container, wherein a gap is provided between the inner container and the outer container, wherein the gap is subjected to a vacuum, and wherein the outer volume is fluidically connected to the gap.

[0016] The inner container is thus arranged inside the outer container. The outer container encapsulates the inner container. The gap and the outer volume form a common gas space that is subjected to a vacuum. In the present case, “vacuum” is understood to mean in particular a pressure of less than 300 mbar, preferably less than 10-3 mbar, more preferably less than 107 mbar. The storage container is therefore vacuum insulated or vacuum dampened. The vacuum provided in the gap and in the outer volume thus serves as thermal insulation.

[0017] According to a further embodiment, the outer barrier is connected in gas-tight fashion to the outer container.

[0018] For example, the outer barrier can be connected to the outer container by a material bond. Given integrally bonded connections, the connection partners are held together by atomic or molecular forces. Integrally bonded connections are non-releasable connections that can only be separated by destroying the connecting means and / or the connection partners. For example, the outer barrier is welded or soldered into the outer container. The outer barrier preferably does not contact the inner container. In particular, the outer barrier opens out of the gap provided between the inner container and the outer container.

[0019] According to a further embodiment, the inner barrier is connected in gas-tight fashion to the inner container.

[0020] For example, the inner barrier can be connected to the inner container by a material bond. The inner barrier can be welded or soldered into the inner container. The inner barrier is preferably routed through the outer container without contacting it.

[0021] According to another embodiment, the leakage detection device has an inner pressure sensor for detecting a pressure change in the inner volume and an outer pressure sensor for detecting a pressure change in the outer volume.

[0022] The outer pressure sensor can be located on the outer barrier or on the outer container. A plurality of outer pressure sensors can be provided. The inner pressure sensor is arranged in particular on the inner barrier. A plurality of inner pressure sensors can be provided. The inner pressure sensor can be operatively connected to the inner volume by means of an inner pressure sensor line. The outer pressure sensor can be operatively connected to the outer volume by means of an outer pressure sensor line.

[0023] According to another embodiment, the leakage detection device has an inner overpressure protection device to protect the inner barrier against overpressure and an outer overpressure protection device to protect the outer barrier against overpressure.

[0024] The overpressure protection devices can, for example, be designed as rupture disks. The inner overpressure protection device is designed to open the inner volume to the surrounding environment of the storage container when a defined overpressure is reached. Accordingly, the outer overpressure protection device is suitable for opening the outer volume to the environment when a defined overpressure is reached. The overpressure protection devices can each comprise a sensor system that sends a sensor signal to an evaluation unit of the leakage detection device when the inner overpressure protection device and / or the outer overpressure protection device is triggered. In other words, the evaluation unit can detect a triggering of the inner overpressure protection device and / or a triggering of the outer overpressure protection device. Triggering the overpressure protection devices can be used to detect or ascertain leaks in the extraction line, the inner barrier and / or the outer barrier.

[0025] According to a further embodiment, the leakage detection device has an evaluation unit operatively connected to the inner pressure sensor and to the outer pressure sensor, which unit detects a leak in the extraction line when there is a pressure equalization between the extraction line and the inner volume and simultaneously no pressure change in the outer volume, which unit detects a leak in the inner barrier when there is a pressure drop in the inner volume and simultaneously a pressure increase in the outer volume, and / or which unit detects a leak in the outer barrier when there is a pressure increase in the inner volume and simultaneously a pressure increase in the outer volume.

[0026] The inner overpressure protection device and / or the outer overpressure protection device can also be operatively connected to the evaluation unit. The evaluation unit can therefore also use the triggering of the overpressure protection devices to detect a leak. If there is a leak in the extraction line, the liquid and / or gaseous phase of the cryogen will be escaping from the extraction line and entering the inner volume. This results in pressure equalization between the extraction line and the inner volume. The outer volume is not affected by this. For this reason, there will be no pressure change in the outer volume. From these pressure conditions, it can be concluded that there can only be a leak in the extraction line. If there is a leak in the inner barrier, the detection gas flows from the inner volume into the outer volume, which is subjected to a vacuum. This means that there is a drop in pressure in the inner volume and simultaneously a rise in pressure in the outer volume, as the vacuum in the outer volume collapses. On the basis of these pressure conditions, it can be concluded that the inner barrier is damaged. If there is a leak in the outer barrier, the vacuum in the outer volume collapses, causing a pressure increase in the outer volume. Due to the loss of vacuum in the outer volume, the thermal insulation effect of the vacuum is lost and heat is introduced into the inner barrier and thus into the inner volume, resulting in the previously mentioned pressure increase in the inner volume. From this it can be concluded that only the outer barrier is damaged. It is therefore possible to easily and reliably determine, on the basis of the pressure conditions, whether the extraction line, the inner barrier and / or the outer barrier have a leak.

[0027] According to the invention, the inner volume is filled with a detection gas, wherein the detection gas has an overpressure relative to the outer volume. Preferably, the detection gas has an overpressure or differential pressure of 0.3 to 4 bara, particularly preferably 0.3 to 1 bara, relative to the outer volume during the extraction of cryogen via the extraction line.

[0028] For example, the detection gas is helium. However, the detection gas can also be, for example, argon or another, preferably inert, gas that remains in a gaseous state during the extraction of cryogen via the extraction line, i.e. does not condense. The detection gas can also be a mixture of the aforementioned gases.

[0029] The detection gas is introduced into the inner volume at a temperature and pressure that ensure that, when cryogen is extracted via the extraction line, during which the detection gas cools down and loses pressure, it maintains an overpressure or differential pressure relative to the outer volume, preferably corresponding to the pressure ranges mentioned above. At the same time, the detection gas in the inner volume should maintain a negative pressure or differential pressure relative to the cryogen in the extraction line. In other words, this means that the detection gas is introduced into the inner volume, or is present in the inner volume, at a pressure and temperature that ensure that when cryogen is extracted via the extraction line, the pressure of the detection gas is greater than the pressure prevailing in the outer volume. Preferably, the detection gas is introduced into the inner volume or is present in the inner volume at a pressure and temperature that ensure that when cryogen is extracted via the extraction line, the pressure of the detection gas is lower than the pressure of the cryogen in the extraction line. The pressure difference between the cryogen in the extraction line and the detection gas in the inner volume is preferably at least 0.3 bara, particularly preferably at least 1 bara. The pressure difference or overpressure between the detection gas in the inner volume and the pressure prevailing in the outer volume is preferably at least 0.3 bara, particularly preferably at least 1 bara.

[0030] According to another embodiment, the extraction apparatus has a valve box that encloses an accommodating chamber in which a valve connected in the extraction line is accommodated.

[0031] The valve box can also be called a valve chamber. The valve box is preferably vacuum-insulated. A wide variety of valves can be arranged inside the valve box.

[0032] According to another embodiment, the outer barrier is connected in gas-tight fashion to the valve box, wherein the outer volume is fluidically separated from the accommodating chamber.

[0033] For example, the outer barrier is connected to the valve box by a material bond. The outer barrier can be welded or soldered to the valve box. In particular, the outer barrier can be connected in gas-tight fashion to a wall of the valve box. This wall fluidically separates the outer volume from the accommodating chamber.

[0034] According to another embodiment, the inner barrier ends within the accommodating chamber, whereby the inner volume is fluidically separated from the accommodating chamber.

[0035] The inner barrier projects into the accommodating chamber. However, the inner barrier is sealed gas-tight with respect to the accommodating chamber.

[0036] According to another embodiment, the inner barrier surrounds the valve in a gas-tight fashion.

[0037] For this purpose, the inner barrier can have an accommodating section for accommodating the valve. The valve can have an actuating element that is routed out of the previously mentioned accommodating section of the inner barrier and out of the valve box in a gas-tight fashion. The actuating element can be shaft-shaped or rod-shaped. The actuating element can be driven by a drive element, for example in the form of an electric motor.

[0038] According to another embodiment, the inner container and / or the inner barrier are sheathed by a thermal insulating element.

[0039] The thermal insulating element is multilayered. This means that the thermal insulating element comprises a plurality of layers. The thermal insulating element can therefore also be referred to as a multilayered thermal insulating element or as a multilayered insulating element. In particular, the thermal insulating element is a so-called multilayer insulation (MLI).

[0040] Furthermore, a method for detecting a leak in such a storage container for storing a cryogen is proposed. The storage container has an inner container for accommodating the cryogen and an extraction apparatus for extracting the cryogen from the inner container, wherein the extraction apparatus has an extraction line which is fluidically connected to the inner container, an inner barrier in which the extraction line is at least partially accommodated and which encloses an inner volume, and an outer barrier in which the inner barrier is at least partially accommodated and which encloses an outer volume. According to the invention, the inner volume is filled with a detection gas, wherein the detection gas has an overpressure relative to the outer volume. The method comprises the following steps: a) acquiring a pressure change within the inner volume and / or a pressure change within the outer volume, and b) detecting, on the basis of the pressure change in each case, whether the extraction line, the inner barrier and / or the outer barrier have a leak.

[0041] The method is carried out in particular with the help of the leakage detection device described above. Using this method, it is therefore reliably possible to detect or ascertain whether the extraction line, the inner barrier and / or the outer barrier are damaged or have a leak.

[0042] According to one embodiment, a leak in the extraction line is detected when there is a pressure equalization between the extraction line and the inner volume and simultaneously no pressure change in the outer volume, wherein a leak in the inner barrier is detected when there is a pressure drop in the inner volume and simultaneously a pressure increase in the outer volume and / or wherein a leak in the outer barrier is detected when there is a pressure increase in the inner volume and simultaneously a pressure increase in the outer volume.

[0043] As explained previously, it is possible to detect or ascertain, using the respective pressure conditions, whether the extraction line, the inner barrier, and / or the outer barrier have a leak.

[0044] The embodiments and features described for the proposed storage container apply correspondingly to the proposed method and vice versa.

[0045] In the present case, “a(n)” is not necessarily to be understood as limiting to exactly one element. It is rather the case that a plurality of elements, such as two, three, or more, may also be provided. Any other numerical word used herein is also not to be understood as meaning an exact limitation to exactly the corresponding number of elements. Rather, numerical differences upwards or downwards are possible.

[0046] Further possible implementations of the storage container and / or of the method also include not explicitly mentioned combinations of features or embodiments described above or below with respect to the exemplary embodiments. In this case, a person skilled in the art will also add individual aspects as improvements or additions to the relevant basic form of the storage container and / or of the method.

[0047] Further advantageous embodiments of the storage container and / or of the method are the subject matter of the subclaims and of the exemplary embodiments of the storage container and / or of the method described below. The storage container and / or the method are explained below in more detail with reference to the accompanying figures based on preferred embodiments.

[0048] Fig. 1 shows a schematic sectional view of an embodiment of a storage container for storing a cryogen; Fig. 2 shows a schematic sectional view of an embodiment of an extraction apparatus for the storage container; and Fig. 3 shows a schematic block diagram of an embodiment of a method for recognizing a leak in the storage container according to Fig. 1.

[0049] In the figures, the same or functionally equivalent elements have been provided with the same reference signs unless otherwise indicated.

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

[0051] The storage container 1 can also be referred to as a storage tank. The storage container 1 is preferably suitable for holding hydrogen H2 (boiling point: 1 bara: 20.268 K = -252.882 °C) as a cryogen. The storage container 1 can therefore also be referred to as a hydrogen storage container or as a hydrogen storage container. However, the storage container 1 can also be used for other cryogenic liquids. Examples of cryogenic fluids or liquids, or cryogens for short, are, in addition to the aforementioned hydrogen H2, liquid helium He (boiling point 1 bara: 4.222 K=-268.928 °C), liquid nitrogen N2 (boiling point at 1 bara: 77.35 K = -195.80°C.) or liquid oxygen O2 (boiling point: 1 bara: 90.18 K = -182.97°C). The cryogen preferably has a pressure of 2 to 20 bara, particularly preferably 2 to 17 bara.

[0052] The storage container 1 can be a transport container. For example, liquid hydrogen LH2 can be transported with the storage container 1. The storage container 1 can be part of a vehicle, in particular a watercraft. In the present 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 in building technology.

[0053] The storage container 1 is rotationally symmetrical with respect to an axis of symmetry or center axis 2. The center axis 2 is oriented in particular perpendicularly to the direction of the gravitational force g. The storage container 1 comprises a first container or inner container 3 which is also rotationally symmetrical with respect to the center axis 2. The inner container 3 comprises a tubular or cylindrical base section 4, which also has a rotationally symmetrical design in relation to the center axis 2. In crosssection, the base section 4 can have a circular or approximately circular geometry.

[0054] The base section 4 is closed at both ends with the aid of a cover section 5, 6. The cover sections 5, 6 are domed. A first cover section 5 and a second cover section 6 are domed in opposite directions so that the two cover sections 5, 6 are domed outward in relation to the base section 4. The inner container 3 is fluid-tight, in particular gas-tight. The inner container 3 can be made of stainless steel.

[0055] The cryogen, in this example liquid hydrogen LH2, is contained in the inner container 3. As long as the hydrogen H2 is in the two-phase region, a gas zone 7 containing gaseous hydrogen GH2 and a liquid zone 8 containing liquid hydrogen LH2 can be provided in the inner container 3. After entering the inner container 3, the hydrogen H2 therefore has two phases with different aggregate states, namely, liquid and gaseous. That is to say, in the inner container 3 there is a phase boundary 9 between the liquid hydrogen LH2 and the gaseous hydrogen GH2. The gaseous hydrogen GH2 can also be referred to as the gaseous phase. The liquid hydrogen LH2 can also be referred to as the liquid phase.

[0056] The inner container 3 is arranged completely within a second container or outer container 10. The storage container 1 is therefore double-walled. The outer container 10 also has a rotationally symmetrical design in relation to center axis 2. The outer container 10, like the inner container 3, comprises a tubular or cylindrical base section 11 which has a rotationally symmetrical design in relation to the center axis 2. In crosssection, the base section 11 can have a circular or approximately circular geometry.

[0057] The base section 11 is closed off at the ends in each case by a cover section 12, 13. In particular, a first cover section 12 and a second cover section 13 are provided. The cover sections 12, 13 are domed in opposite directions so that the cover sections 12, 13 are domed outward in relation to the base section 11. The outer container 10 is fluid-tight, in particular gastight. The outer container 10 can also be made of stainless steel, for example.

[0058] A gap 14 completely surrounding or encompassing the inner container 3 is provided between the inner container 3 and the outer container 10. The gap 14 is subjected to a vacuum. In the present case, “vacuum” is understood to mean in particular a pressure of less than 300 mbar, preferably less than 103 mbar, more preferably less than 10-7 mbar. The storage container 1 is therefore vacuum-insulated. The fact that the gap 14 completely "encompasses" or "encases" the inner container 3 means in the present case that the gap 14, on the one hand, runs completely around the base section 4 and, on the other hand, is also provided between the two cover sections 5, 12 as well as between the two cover sections 6, 13. The outer container 10 delimits the storage container 1 at an environment 15 of the storage container 1.

[0059] A thermal insulation element or insulation element (not shown), which completely encompasses or encloses the inner container 3, is provided in the gap 14. That is to say, the thermal insulating element encloses not only the base section 4 but also the lid sections 5, 6 of the inner container 3. The thermal insulating element serves for thermal insulation. The thermal insulating element is multilayered. This means that the thermal insulating element comprises a plurality of layers. The thermal insulating element can therefore also be referred to as a multilayered thermal insulating element or as a multilayered insulating element. In particular, the thermal insulating element is a so-called multilayer insulation (MLI).

[0060] Fig. 2 shows a schematic sectional view of an embodiment of an extraction apparatus 16 for the storage container 1.

[0061] The extraction apparatus 16 has an extraction line 17 which, in the present example, extends from the liquid zone 8 of the storage container 1. Alternatively, the extraction line can also extend from the gas zone of the storage container (not shown in the figures). Liquid hydrogen LH2 can be extracted from the storage container 1 with the aid of the extraction line 17. The liquid hydrogen LH2 can then be vaporized, for example, and supplied as gaseous hydrogen GH2 to a consumer, for example in the form of a fuel cell. The extraction apparatus 16 is attached to the underside of the storage container 1.

[0062] Due to its hydrostatic pressure, liquid hydrogen LH2 can flow into the extraction line 17. The extraction line 17 leads through the inner container 3 and through the outer container 10. For example, the extraction line 17 can be welded or soldered into the inner container 3, in particular into the base section 4 of the inner container 3. The extraction line 17 is passed through the gap 14. The extraction line 17 does not contact the outer container 10. As shown in Fig. 2, the extraction line 17 can be curved. However, the extraction line 17 can also be straight.

[0063] A valve 18 is connected into the extraction line 17. The valve 18 can be an on-off valve. This means that valve 18 can either be fully open or closed. However, the valve 18 can also be configured to continuously adjust the volume flow of the liquid hydrogen LH2 flowing through the valve 18. The valve 18 has assigned to it a rod-shaped actuating element 19, which is coupled to a valve body of valve 18. For example, the valve 18 can be opened and closed with the aid of the actuating element 19 by, for example, rotating the valve body. The actuating element 19 can be operated manually. Alternatively, a drive element 20, for example in the form of an electric motor, can be coupled to the actuating element 19 to actuate the valve 18.

[0064] The extraction line 17 is at least partially enclosed by a first or inner barrier 21. The inner barrier 21 is tubular and follows the course of the extraction line 17. The inner barrier 21 is connected in gas-tight fashion to the inner container 3, in particular to the base section 4 of the inner container 3. For example, the inner barrier 21 can be welded or soldered to the base section 4. The inner barrier 21 passes through the gap 14 and through the outer container 10, in particular through the base section 11 of the outer container 10. The inner barrier 21 does not contact the outer container 10.

[0065] The inner barrier 21 has an accommodating section 22 in which the valve 18 is accommodated. The accommodating section 22 can be cylindrical or box-shaped. The accommodating section 22 surrounds or encapsulates the valve 18 in a gas-tight fashion. The actuating element 19 is routed out of the accommodating section 22 in a gas-tight fashion. For this purpose, a suitable seal can be provided between the actuating element 19 and the accommodating section 22, which allows movement, in particular rotation, of  the actuating element  19  relative to  the accommodating section 22. The extraction line 17 is routed out of the accommodating section 22 in a gas-tight fashion. For this purpose, the extraction line 17 can, for example, be welded or soldered into the accommodating section 22.

[0066] The inner barrier 21 encloses or encapsulates an unchanging and closed first or inner volume 23 through which the extraction line 17 passes at least partially, and in which the valve 18 is arranged. The inner volume 23 is filled with a detection gas He. The detection gas He in this case is helium and will therefore also be referred to as helium below. The helium He in the inner volume 23 has an overpressure relative to the outer volume 32, i.e. during the extraction of cryogen via the extraction line 17 or during times when no extraction is taking place. The inner volume 23 is filled with helium He under controlled conditions, usually at a predetermined pressure and temperature. The pressure of the helium He in the inner volume 23 is chosen such that, despite cooling and the associated pressure reduction, the helium He always maintains an overpressure relative to the outer volume 32 when hydrogen LH2 is being extracted via the extraction line 17. Preferably, the detection gas He in the inner volume 23 has an overpressure relative to the outer volume 32 of 0.3 to 4 bara, particularly preferably of 0.3 to 1 bara, when cryogen LH2 is being extracted via the extraction line 17. This can be achieved for example by introducing the helium He into the inner volume 23 at a temperature between 0 and 30°C and a pressure of 8 bara.

[0067] The inner volume 23 is assigned an inner pressure sensor or inner pressure transducer 24, with the help of which the pressure of the helium He in the inner volume 23 can be detected. The inner pressure sensor 24 can be coupled to the inner barrier 21 via an inner pressure sensor line 25. The inner pressure sensor line 25 can be welded or soldered into the inner barrier 21.

[0068] The extraction apparatus 16 is assigned an evaluation unit 26 which is operatively connected to the inner pressure sensor 24 via a data connection 27. The data connection 27 can be wired or wireless. The evaluation unit 26 can be a computer or comprise a computer. The evaluation unit 26 can, for example, have a screen with whose aid the pressure of the helium He within the inner volume 23 can be displayed. The inner pressure sensor 24 and the evaluation unit 26 are part of a leakage detection device 28 for determining, detecting or ascertaining a leak in the extraction apparatus 16. The leakage detection device 28 can also include the inner pressure sensor line 25 and the data connection 27. The leak recognition device 28 can be part of the extraction apparatus 16.

[0069] The leakage detection device 28 can have a temperature measurement function for measuring an outside temperature of the extraction line 17. The temperature measurement function of the leakage detection device 28 is explained below. The inner volume 23 is defined and unchanging. Since the inner volume 23 was filled with the helium He under controlled conditions, a specific temperature of the helium He can be unambiguously assigned to a specific pressure of the helium He in the inner volume 23. If the temperature of the helium He in the inner volume 23 changes, for example if the extraction line 17 heats up due to an interruption of the volume flow of liquid hydrogen LH2 flowing through the extraction line 17, the inner volume 23 itself cannot change but the pressure of the helium He in the inner volume 23 changes. An isochoric change of state of the helium (He) takes place. "Isochoric" is a term from thermodynamics. It describes a change of state of a substance, in this case helium He, in which its volume, in this case the inner volume 23, remains constant. The following then applies: p — = constant T

[0070] Here, p represents the pressure and T the temperature of the helium He within the inner volume 23. It follows that a relative change in pressure p corresponds to a relative change in temperature T: p 2 _ 22 pl = T1

[0071] Here, p1 represents the absolute pressure before heat is added, p2 represents the absolute pressure after heat is added, T1 represents a temperature before heat is added, and T2 represents a temperature after heat is added. If the pressure p2 is now ascertained with the aid of the inner pressure sensor 24, it will be possible to determine the temperature T2, for example, with the aid of a suitable table. Such a table can be stored electronically in the evaluation unit 26, so that the evaluation unit can output the temperature T2. The temperature T2 of the helium He then corresponds to an outer temperature of the extraction line 17. The temperature T2 of the extraction line 17 after it has been heated can thus be measured indirectly with the aid of the leakage detection device 28. The same applies to a cooling of the extraction line 17. This eliminates the need to provide temperature sensors directly on the extraction line 17.

[0072] The inner barrier 21 or the inner volume 23 is assigned a first or inner overpressure protection device 29, for example in the form of a rupture disk, which is suitable for opening the inner volume 23 to the environment 15 when a defined overpressure is reached. The inner overpressure protection device 29 can be attached to the inner pressure sensor line 25. The inner overpressure protection device 29 can have a sensor system that sends a sensor signal to the evaluation unit 26 when the inner overpressure protection device 29 is triggered. In other words, the evaluation unit 26 can detect a triggering of the inner overpressure protection device 29 and, if necessary, output an acoustic and / or visual signal.

[0073] Returning to the extraction apparatus 16, this device has a second or outer barrier 30 which at least partially encapsulates or surrounds the inner barrier 21, wherein the inner barrier 21 at least partially encapsulates or surrounds the extraction line 17. The inner pressure sensor line 25 passes through the outer barrier 30. For example, the inner pressure sensor line 25 can be welded or soldered into the outer barrier 30. The outer barrier 30 is tubular and follows the course of the extraction line 17. The outer barrier 30 is connected in gas-tight fashion to the outer container 10, in particular to the base section 11 of the outer container 10. For example, the outer barrier 30 can be welded or soldered into the base section 11. The outer barrier 30 does not contact the inner container 3.

[0074] The outer barrier 30 leads from the outer container 10 to a valve box 31. The valve box 31 can also be called a valve chamber. The outer barrier 30 is connected in gas-tight fashion to the valve box 31. For example, the outer barrier 30 can be welded or soldered to the valve box 31. The outer barrier 30 encloses a second or outer volume 32, which is subjected to a vacuum. The outer volume 32 is fluidically connected to the gap 14. In other words, the outer volume 32 and the gap 14 form a common gas space. The outer volume 32 is -like the gap 14 - subjected to a vacuum. As mentioned above, a thermal insulating element 33, in particular in the form of an MLI, is accommodated in the gap 14. The thermal insulating element 33 can be wound onto the inner container 3. The thermal insulating element 33 can also fill the outer volume 32 at least partially. In this case, the thermal insulating element 33 is wound onto the inner barrier 21.

[0075] The valve box 31 encloses an accommodating chamber 34, within which the valve 18 and other valves not shown are arranged. The inner barrier 21 leads into the accommodating chamber 34. The outer volume 32 is not fluidically connected to the accommodating chamber 34. The actuating element 19 is routed out of the valve box 31 in a gas-tight fashion, so that the drive element 20 is arranged outside the valve box 31. The inner barrier 21 ends with the accommodating section 22, in which the valve 18 is accommodated, in the accommodating chamber 34. The extraction line 17 is routed out from the valve box 31. The valve box 31 can be vacuum-insulated.

[0076] An outer pressure sensor or outer pressure transducer 35 is assigned to the outer volume 32. The outer pressure sensor 35 can be connected to the outer barrier 30 by an outer pressure sensor line 36. The outer pressure sensor line 36 can be welded or soldered into the outer barrier 30. Since the outer volume 32 is fluidically connected to the gap 14, the outer pressure sensor 35 can also be positioned at any position on the outer container 10. The outer pressure sensor 35 is connected to the evaluation unit 26 by means of a data connection 37. The data connection can 37 be wired or wireless. The outer pressure sensor 35 is part of the leakage detection device 28. The outer pressure sensor line 36 and the data connection 37 can also be part of the leakage detection device 28.

[0077] A second or outer overpressure protection device 38, for example in the form of a rupture disk, is assigned to the outer barrier 30 or the outer volume 32, which is suitable for opening the outer volume 32 to the environment 15 when a defined overpressure is reached. The outer overpressure protection device 38 can be attached to the outer pressure sensor line 36. The outer overpressure protection device 38 can have a sensor system that sends a sensor signal to the evaluation unit 26 when the outer overpressure protection device 38 is triggered. In other words, the evaluation unit 26 can detect a triggering of the outer overpressure protection device 38 and, if necessary, output an acoustic and / or visual signal.

[0078] The functioning of the extraction apparatus 16 is explained below. The extraction line 17 upstream of the valve 18 is the most critical for leaks. If a leak occurs in this region in the extraction line 17, this can lead to the entire storage container 1 emptying. This can cause the liquid hydrogen LH2 to come into contact with the thermal insulating element 33 and damage it. The outer container 10 cools down to such an extent that air constituents condense on it. These condensed air constituents drip into a drip pan below the storage container 1 and evaporate. This continues until all the liquid hydrogen LH2, which can have a mass of several tons, has evaporated and been vented via emergency relief valves of the storage container 1.

[0079] If the storage container 1 has a foundation that cannot withstand cryogenic temperatures, it will be cooled far beyond its design temperature and destroyed. This applies, for example, to the use of carbon steels, often used in shipbuilding, as a material for the foundation. A leak in the outer barrier 30 will lead to a loss of vacuum in the outer volume 32 and the gap 14 and consequently to the undesirable result explained above.

[0080] With the help of the extraction apparatus 16, a vacuum loss in the event of a leak can now be detected or sensed and the foundation protected from excessively low temperatures. For this purpose, the extraction apparatus 16 has the two barriers 21, 30 and the leakage detection device 28. Together with the extraction line 17, the two barriers 21, 30 result in a three-layer structure of the extraction apparatus 16.

[0081] If the extraction line 17 breaks, the liquid hydrogen LH2 will flow into the inner volume 23 and be collected there. The liquid hydrogen LH2 cannot reach the thermal insulating element 33 and the vacuum in the outer volume 32 and the gap 14 does not collapse. Temperature-related damage to the foundation is prevented. A pressure equalization occurs between the inner volume 23 and the extraction line 17. If the pressure of the helium He in the inner volume 23 and in the extraction line 17 equalizes, it can be deduced that there is a leak between the extraction line 17 and the inner volume 23. This pressure equalization is detected with the aid of the inner pressure sensor 24. With the help of the evaluation unit 26, it can then be signaled, for example visually and / or acoustically, that a leak has occurred in the extraction line 17.

[0082] If a leak occurs between the inner volume 23 and the outer volume 32, for example in the form of a crack in the inner barrier 21, the pressure of the helium He in the inner volume 23 decreases since the helium He is flowing from the inner volume 23 into the outer volume 32. This pressure drop is detected with the aid of the inner pressure sensor 24. In addition, the pressure in the outer volume 32 will increase and may trigger the outer overpressure protection device 38. From the fact that the pressure of the helium He in the inner volume 23 decreases and the pressure in the outer volume 32 increases, and that the outer overpressure protection device 38 is possibly triggered, it can be concluded that there is a leak in the inner barrier 21. With the help of the evaluation unit 26, it can then be signaled, for example visually and / or acoustically, that a leak has occurred in the inner barrier 21.

[0083] If the outer barrier 30 has a leak, the vacuum in the outer volume 32 will collapse, which can be detected with the aid of the outer pressure sensor 35. Due to the vacuum in the outer volume 32 being lost, the thermal insulation effect of the outer volume 32 can no longer be guaranteed. Heat introduced into the inner barrier 21 then ensures that the pressure of the helium He in the inner volume 23 immediately increases and, if necessary, the inner overpressure protection device 29 is triggered. From this, it can then be concluded that there is a leak in the outer barrier 30. Here too, for example an optical and / or acoustic signal can then be output with the aid of the evaluation unit 26.

[0084] Fig. 3 shows a schematic block diagram of an embodiment of a method for detecting a leak in the storage container 1.

[0085] In the method, in step S1 a pressure change within the inner volume 23 enclosed by the inner barrier 21 and / or a pressure change within the outer volume 32 enclosed by the outer barrier 30 is detected. In step S2, on the basis of the pressure change in each case it is ascertained whether the extraction line 17, the inner barrier 21 and / or the outer barrier 30 have a leak.

[0086] In particular, a leak in the extraction line 17 is detected if there is a pressure equalization between the extraction line 17 and the inner volume 23 and simultaneously no pressure change in the outer volume 32. Furthermore, a leak in the inner barrier 21 is detected if there is a pressure drop in the inner volume 23 and simultaneously a pressure increase in the outer volume 32. A leak in the outer barrier 30 is ascertained when there is a pressure increase in the inner volume 23 and simultaneously a pressure increase in the outer volume 32.

[0087] Although the present invention has been described with reference to embodiments, it can be modified in many ways within the scope of the claims. Reference signs used 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 Storage container Center axis Inner container Base section Cover section Cover section Gas zone Liquid zone Phase boundary Outer container Base section Cover section Cover section Gap Environment Extraction apparatus Extraction line Valve Actuating element Drive element Barrier Accommodating section Volume Pressure sensor Pressure sensor line Evaluation unit Data connection Leakage detection device Overpressure protection device Barrier Valve box Volume Thermal insulating element Accommodating chamber Pressure sensor Pressure sensor line Data connection Overpressure protection device g GH2 H2 He LH2 Direction of gravity Gaseous phase / gaseous hydrogen Cryogen / hydrogen Detection gas / helium Liquid phase / liquid hydrogen S1 S2 Step Step

Claims

1. A storage container (1) for storing a cryogen (H2), comprising an inner container (3) for accommodating the cryogen (H2) and an extraction apparatus (16) for extracting the cryogen (H2) from the inner container (3), wherein the extraction apparatus (16) comprises:- an extraction line (17) which is fluidically connected to the inner container (3),- an inner barrier (21) in which the extraction line (17) is at least partially accommodated and which encloses an inner volume (23), wherein the inner volume (23) is filled with a detection gas (He),- an outer barrier (30) in which the inner barrier (21) is at least partially accommodated and which encloses an outer volume (32), wherein the detection gas (He) in the inner volume (23) has an overpressure relative to the outer volume (32), and- a leakage detection device (28) that is configured to detect, on the basis of a pressure change within the inner volume (23) and / or on the basis of a pressure change within the outer volume (32), whether the extraction line (17), the inner barrier (21), and / or the outer barrier (30) have a leak.

2. The storage container according to claim 1, wherein the storage container (1) has an outer container (10) enclosing the inner container (3), wherein a gap (14) is provided between the inner container (3) and the outer container (10), wherein the gap (14) is subjected to a vacuum, and wherein the outer volume (32) is fluidically connected to the gap (14).

3. The storage container according to claim 2, wherein the outer barrier (30) is connected in gas-tight fashion to the outer container (10).

4. The storage container according to one of claims 1 - 3, wherein the inner barrier (21) is connected to the inner container (3) in gas-tight fashion.

5. The storage container according to one of claims 1 - 4, wherein the leakage detection device (28) has an inner pressure sensor (24) for detecting a pressure change in the inner volume (23) and an outer pressure sensor (35) for detecting a pressure change in the outer volume (32).

6. The storage container according to claim 5, wherein the leakage detection device (28) has an inner overpressure protection device (29) to protect the inner barrier (21) against overpressure and an outer overpressure protection device (38) to protect the outer barrier (30) against overpressure.

7. The storage container according to claim 5 or 6, wherein the leakage detection device (28) has an evaluation unit (26) operatively connected to the inner pressure sensor (24) and to the outer pressure sensor (35), which unit detects a leak in the extraction line (17) when there is a pressure equalization between the extraction line (17) and the inner volume (23) and simultaneously no pressure change in the outer volume (32), which unit detects a leak in the inner barrier (21) when there is a pressure drop in the inner volume (23) and simultaneously a pressure increase in the outer volume (32), and / or which unit detects a leak in the outer barrier (30) when there is a pressure increase in the inner volume (23) and simultaneously a pressure increase in the outer volume (32).

8. The storage container according to one of claims 1 - 7, wherein the detection gas (He) in the inner volume (23) has an overpressure of 0.3 to 4 bara, in particular of 0.3 to 1 bara, relative to the pressure prevailing in the outer volume (32).

9. The storage container according to one of claims 1 - 8, wherein the extraction apparatus (16) has a valve box (31) which encloses an accommodating chamber (34) within which a valve (18) connected to the extraction line (17) is accommodated.

10. The storage container according to claim 9, wherein the outer barrier (30) is connected in gas-tight fashion to the valve box (31), and wherein the outer volume (32) is fluidically separated from the accommodating chamber (34).

11. The storage container according to claim 9 or 10, wherein the inner barrier (21) terminates within the accommodating chamber (34), and wherein the inner volume (23) is fluidically separated from the accommodating chamber (34).

12. The storage container according to one of claims 9 - 11, wherein the inner barrier (21) surrounds the valve (18) in a gas-tight fashion.

13. The storage container according to one of claims 1 - 12, wherein the inner container (3) and / or the inner barrier (21) are enclosed by a thermal insulating element (33).

14. A method for detecting a leak in a storage container (1) for storing a cryogen (H2), wherein the storage container (1) comprises an inner container (3) for accommodating the cryogen (H2) and an extraction apparatus (16) for extracting a liquid phase (LH2) of the cryogen (H2) from the inner container (3), wherein the extraction apparatus (16) comprises an extraction line (17) which is fluidically connected to the inner container (3), an inner barrier (21) in which the extraction line (17) is at least partially accommodated and which encloses an inner volume (23) wherein the inner volume (23) is filled with a detection gas (He), and an outer barrier (30) in which the inner barrier (21) is at least partially accommodated and which encloses an outer volume (32) wherein the detection gas (He) has an overpressure relative to the outer volume (32), with the following steps:a) acquiring (S1) a pressure change within the inner volume (23) and / or of a pressure change within the outer volume (32), andb) detecting (S2), on the basis of the pressure change in each case, whether the extraction line (17), the inner barrier (21) and / or the outer barrier (30) have a leak.5   15. The method according to claim 14, wherein a leak in the extraction line(17) is detected when there is a pressure equalization between the extraction line (17) and the inner volume (23) and simultaneously no pressure change in the outer volume (32), wherein a leak in the inner barrier (21) is detected when there is a pressure drop in the inner volume (23) and simultaneously a10 pressure increase in the outer volume (32), and / or wherein a leak in the outer barrier (30) is detected when there is a pressure increase in the inner volume (23) and simultaneously a pressure increase in the outer volume (32).

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