Method and conveying apparatus

Abstract

The present invention relates to a method for transporting a cryogen (H2) from a storage vessel (5) to a load (4), comprising: a) a step (S1) of introducing the cryogen (H2) from the storage vessel (5) into an equalization tank (13A, 13B), in which the cryogen (H2) flows from the storage vessel (5) into the equalization tank (13A, 13B) solely due to the hydrostatic pressure of the cryogen; b) a step (S2) of bringing the cryogen (H2) contained in the equalization tank (13A, 13B) into its supercritical state; and c) a step (S3) of discharging the cryogen (H2) from the equalization tank (13A, 13B) to the load (4), in which the cryogen (H2) contained in the equalization tank (13A, 13B) is kept in a supercritical state during step c).

Description

Technical Field

[0001] The present invention relates to a method for transporting a cryogen and a transport device for transporting a cryogen.

[0002] According to the in-house know-how of the applicant, a storage container for liquid hydrogen can have a pressure increase vaporizer that enables the pressure to be increased inside the storage container, whereby gaseous hydrogen can be utilized for a load in the form of a fuel cell, for example, at a stable supply pressure of about 6 bara. During the operation of such a storage container in a marine area, it is very difficult to keep the operating conditions inside the storage container stable so that the supply pressure required for the fuel cell can be kept constant due to natural movements caused by the sea state.

[0003] The applicant also recognizes the in-house prior art in which hydrogen is stored in the storage container at substantially zero pressure. In this case, hydrogen is transported using a cryogenic pump and supplied to the fuel cell at the aforementioned supply pressure. However, such a cryogenic pump has moving parts, and these moving parts require a certain amount of maintenance work and thus may result in downtime. Furthermore, according to the in-house investigation results, it is also possible to vaporize hydrogen upstream of the fuel cell and then compress it in order to achieve the required supply pressure. However, this is not preferable from the perspective of energy use.

[0004] From such a background, an object of the present invention is to provide an improved method for transporting a cryogen.

[0005] Therefore, a method for transporting a cryogen from a storage container to a load is proposed. This method includes: a) a step of introducing the cryogen from the storage container to an adjustment tank, wherein the cryogen flows from the storage container to the adjustment tank due only to the hydrostatic pressure of the cryogen; b) a step of bringing the cryogen contained in the adjustment tank into its supercritical state; and c) a step of discharging the cryogen from the adjustment tank to the load, wherein the cryogen contained in the adjustment tank is kept in the supercritical state during step c).

[0006] The cryogenic material contained within the conditioning tank is maintained in a supercritical state, and therefore, since there are no phase boundaries, even if the conditioning tank moves due to, for example, high waves, it does not adversely affect the temperature distribution within the tank. Furthermore, the storage container can be operated at the lowest possible pressure. This extends the retention time of the cryogenic material.

[0007] The cryogen is preferably hydrogen. Therefore, the terms “cryogen” and “hydrogen” are interchangeable as desired. However, in principle, the cryogen may be any other cryogen. Examples of cryogenic fluids or liquids, or simply cryogen, include, for example, liquid helium, liquid nitrogen, or liquid oxygen. Therefore, “cryogen” should be understood specifically as a liquid. The cryogen can also be vaporized and converted into a gas phase. After vaporization, the cryogen is a gas, or may be referred to as a gaseous or vaporizing cryogen.

[0008] The load is preferably a fuel cell. In this case, “fuel cell” is understood to mean a galvanic cell that converts the chemical reaction energy of a continuously supplied fuel, in this case hydrogen, and an oxidizer, in this case oxygen, into electrical energy. The cryogenic agent is supplied to the load itself at a specified supply pressure, particularly in gaseous form. This means that the cryogenic agent is vaporized before or upstream of the load. For example, the cryogenic agent is supplied to the load at a supply pressure of 6 bara and a temperature of 10-25°C.

[0009] A gaseous region and a sub-liquid region are formed within the storage container after or during the cryogenic fill operation. A phase boundary is created between the gaseous and liquid regions. Therefore, it is preferable that the cryogenic material, after entering the storage container, has two phases in different condensation states, namely a liquid phase and a gaseous phase. The liquid phase can transition to the gaseous phase, and vice versa. A pure liquid fill operation is also possible.

[0010] It is preferable that a line extending between the storage container and the adjustment tank is provided to introduce the refrigerant from the storage container to the adjustment tank. In this case, the storage container is preferably positioned above the adjustment tank with respect to the direction of gravity, so that the refrigerant flows from the storage container into the adjustment tank solely due to static pressure.

[0011] In this context, “hydrostatic pressure,” “static pressure,” “gravitational pressure,” or “gravitational pressure” should be understood, in particular, as the pressure arising from the influence of gravity or gravitational force in a stationary fluid, in this case, a cryogenic fluid. The statement that the cryogenic fluid flows or is transported from the storage container to the adjustment tank “only,” “simply,” or “only” due to the hydrostatic pressure of the cryogenic fluid specifically means that the cryogenic fluid is transported from the storage container to the adjustment tank “exclusively” by hydrostatic pressure. Therefore, the terms “only,” “simply,” “only,” or “exclusively” are interchangeable as needed. “Exclusively” specifically means that there is no other type of transport of the cryogenic fluid except that based on the hydrostatic pressure of the cryogenic fluid. “Flow” can be replaced, in particular, with “transported.”

[0012] This flow or transport of the cryogenic material from the storage container to the conditioning tank, which is simply due to hydrostatic pressure, can be achieved, as described above, for example, by a storage container positioned at least partially above or above the conditioning tank when viewed along the direction of gravity. In particular, the point or region where the cryogenic material is discharged or removed from the storage container is positioned higher or above the point or region where the cryogenic material is introduced or supplied to the conditioning tank.

[0013] Therefore, a pump is not required to transport the refrigerant from the storage container to the adjustment tank, and can therefore be omitted. Thus, this method, and especially step a), is performed in a "pumpless" or "pump-free" manner. This means, in particular, that in step a), the refrigerant is introduced or transported from the storage container to the adjustment tank without a pump. Thus, step a) can also be described as the pumpless introduction of the refrigerant from the storage container to the adjustment tank. Omitting the pump eliminates the need for moving parts, which leads to a higher reliability of this method.

[0014] After introducing the cryogenic substance from the storage container to the adjustment tank, the valve between the storage container and the adjustment tank is preferably closed. The "supercritical state" or "critical point" should be understood as the thermodynamic state of the cryogenic substance, which is characterized by the agreement of the densities of the liquid and gas phases. The difference between the two condensation states disappears at the critical point; that is, there is no phase boundary in the supercritical state.

[0015] A cryogenic material can be brought to a supercritical state, for example, by placing it under pressure. For example, heat can be introduced into a regulating tank, thereby increasing the pressure in the regulating tank. In particular, the pressure in the regulating tank is increased exclusively by the introduction of heat. This means that the cryogenic material can be brought to a supercritical state by heat alone, or exclusively by heat. The cryogenic material is kept in a supercritical state continuously or steadily, particularly during step c).

[0016] The removal of the product, in this case the cryogenic agent, is carried out in the supercritical state of the cryogenic agent. Therefore, the pressure in the adjustment tank is kept steady and constant during its operation. During step c), the cryogenic agent is, in particular, always or constantly in a single-phase state, i.e., a supercritical state. "Always" means that it is undesirable, and in particular, does not or cannot deviate from the supercritical state. This can be achieved, for example, during step c), i.e., while the cryogenic agent is being removed from the adjustment tank, by a continuous supply of heat.

[0017] During step c), the cryogen is preferably kept in a supercritical state at all times, so that the supercritical state is maintained even when the cryogen is discharged from the conditioning tank, while the cryogen is supplied to the load. This means that, in particular, during step c), i.e., while the cryogen is being removed from the conditioning tank, heat is continuously introduced into the conditioning tank to maintain a constant pressure in the conditioning tank during step c), so that the cryogen remains in a supercritical state at all times, even while the cryogen is being discharged. The pressure in the conditioning tank is maintained, in particular kept constant, and in particular exclusively maintained by the introduction of heat.

[0018] According to one embodiment, after step a), the adjustment tank is separated from the storage container by a valve, by which the valve is closed.

[0019] The valve is preferably a shut-off valve. The valve may also be an on / off valve. This means that the valve can be in two states, namely an open state and a closed state. The aforementioned valve is located in or on a line between the storage container and the regulating tank.

[0020] In a further embodiment, a valve provided between the adjustment tank and the load is opened in step c).

[0021] A line that can be shut off via the aforementioned valve is similarly provided between the regulating tank and the load. The valve is located downstream of the regulating tank.

[0022] In a further embodiment, heat is introduced into the conditioning tank during step b) to bring the cryogenic agent to a supercritical state.

[0023] For this purpose, a heating element may be provided inside or on top of the conditioning tank. The heating element may be, for example, an electric heating element. The heating element may also have a heating medium, through which heat is introduced into the chilling agent.

[0024] In a further embodiment, heat is introduced into the conditioning tank during step c) to maintain the refrigerant in a supercritical state.

[0025] This means that heat is continuously introduced into the cryogenic material while the adjustment tank is being emptied. As a result, the supercritical state can be maintained while the adjustment tank is empty.

[0026] According to a further embodiment, during step c), the density of the cryogenic agent in the adjustment tank decreases.

[0027] While the density is decreasing, the refrigerant is continuously kept in the supercritical state and the refrigerant is supplied to the load.

[0028] According to a further embodiment, during step c), the pressure in the regulating tank is kept constant.

[0029] In this case, "constant" may mean a deviation from the target pressure of ± 1 bar. Preferably, the pressure in the regulating tank is maintained at 14 bara.

[0030] According to a further embodiment, step c) ends after a predetermined temperature is reached in the regulating tank.

[0031] The predetermined temperature is, for example, -230 °C. After the predetermined temperature is reached, heat is preferably no longer introduced into the regulating tank.

[0032] According to a further embodiment, the regulating tank is depressurized by venting into the load until the supply pressure of the load is achieved.

[0033] The supply pressure is, for example, 6 bara. By depressurizing the regulating tank by venting into the load, the regulating tank can be further emptied.

[0034] According to a further embodiment, when the supply pressure is achieved, the regulating tank is depressurized by venting into the storage container.

[0035] This means that immediately after the pressure in the regulating tank drops below the supply pressure, the refrigerant is no longer supplied to the load and is instead supplied to the storage container. In this case, the gaseous refrigerant can be introduced into the storage container either from above, i.e., into the gas region of the storage container, or from the side or from below, i.e., into the liquid region of the storage container. In the latter case, at least partial condensation of the gaseous refrigerant introduced into the storage container is possible.

[0036] According to another embodiment, the first and second regulating tanks are operated intermittently.

[0037] For example, step a) is performed using the first adjustment tank, while step b) or c) is performed using the second adjustment tank. This makes it possible to supply a continuous flow of refrigerant to the load.

[0038] Furthermore, a conveying device is proposed for transporting the cryogenic agent from a storage container to a load. The conveying device includes a regulating tank positioned between the storage container and the load, and the storage container and the regulating tank are arranged so that the cryogenic agent flows from the storage container to the regulating tank only by the hydrostatic pressure of the cryogenic agent. The regulating tank is configured to supply the cryogenic agent introduced from the storage container to the load in a supercritical state, and to maintain the cryogenic agent contained in the regulating tank in a supercritical state while it is being supplied to the load.

[0039] The conveying device may include a storage container. The storage container is preferably rotationally symmetric with respect to a central axis or axis of symmetry. Therefore, the storage container is preferably cylindrical. The conditioning tank may also be cylindrical. The conditioning tank may also be referred to as the conditioning container. When the conditioning tank is "configured" to bring the cryogenic substance introduced into the conditioning tank to a supercritical state and supply it to the load means, in this case, it means that the conditioning tank has means, such as a heating element, that can reach a supercritical state. Means, such as the heating element described above, are also provided to maintain the supercritical state. To supply the cryogenic substance to the load, the conditioning tank has, for example, lines and valves, or lines and valves are assigned to the conditioning tank. To achieve a flow of cryogenic substance from the storage container to the conditioning tank due only to the hydrostatic pressure of the cryogenic substance or solely to the hydrostatic pressure of the cryogenic substance, the storage container is preferably positioned or placed so that it is at least partially higher than the conditioning tank when viewed along the direction of gravity.

[0040] According to one embodiment, the adjustment tank includes a heating element for introducing heat into the cryogenic substance contained in the adjustment tank to bring the cryogenic substance to a supercritical state.

[0041] The pressure inside the regulating tank can be increased by introducing heat. As a result, the cryogenic material enters a supercritical state.

[0042] In a further embodiment, the conveying device further comprises a first adjustment tank and a second adjustment tank, the first adjustment tank and the second adjustment tank being capable of intermittent operation.

[0043] As described above, the intermittent operation of the first and second regulating tanks makes it possible to supply a continuous flow of refrigerant to the load. Preferably, as described above, a vaporizer is placed before the load, which vaporizes the refrigerant supplied to the load, and thus brings it to a supply pressure of 6 bara at a temperature of, for example, 10-25°C. The vaporizer may be, for example, an electric vaporizer. The vaporizer may also use a heating medium to vaporize the refrigerant.

[0044] According to a further embodiment, the adjustment tank is positioned such that the refrigerant flows automatically into the storage container due to gravity, relative to the direction of gravity.

[0045] As a result, when the cryogenic agent is introduced from the storage container to the adjustment tank, the adjustment tank can be filled into the storage container purely by the static pressure of the cryogenic agent. Pumps with moving parts can be omitted.

[0046] Therefore, the embodiments and features described in the method apply to the proposed conveying device, and vice versa.

[0047] In this case, "a(n)" should not necessarily be understood as strictly limited to one element. Rather, several elements may be provided, such as two, three, or more. Any other numeric terms used herein should also not be understood as implying a strict limitation on the number of elements that strictly correspond to them. Rather, an upward or downward difference in the numbers is possible.

[0048] Further possible implementations of the method and / or conveying apparatus also include combinations of features or embodiments described above or below with respect to exemplary embodiments that are not explicitly mentioned. Those skilled in the art will also add individual embodiments as improvements or additions to each of the basic forms of the method and / or conveying apparatus. [Brief explanation of the drawing]

[0049] Further advantageous embodiments of the method and / or conveying apparatus are the subject of the dependent claims and the exemplary embodiments of the method and / or conveying apparatus described below. Furthermore, the method and / or conveying apparatus will be described in more detail below with reference to the accompanying drawings based on preferred embodiments. [Figure 1] This is a schematic diagram of one embodiment of the vehicle. [Figure 2] This is a schematic diagram of one embodiment of a transport device for transporting hydrogen. [Figure 3] This is a pressure-enthalpy diagram of hydrogen. [Figure 4] This is a schematic block diagram of one embodiment of a method for transporting hydrogen. In the diagram, unless otherwise indicated, identical or functionally equivalent elements are denoted by the same reference numeral.

[0050] Figure 1 shows a highly simplified schematic side view of one embodiment of Vehicle 1. Vehicle 1 can be, for example, a maritime vessel, in particular a ship. Vehicle 1 may be referred to as a maritime vehicle. In particular, Vehicle 1 may be a maritime passenger ferry. Alternatively, Vehicle 1 may also be a land vehicle or an aircraft. However, in the following, we will assume that Vehicle 1 is a ship.

[0051] Vehicle 1 comprises a buoyant hull 2. A bridge 3 is provided on or above the hull 2. Vehicle 1 is preferably powered by hydrogen. For this purpose, vehicle 1 may have a load 4. The load 4 is preferably a fuel cell. In this case, “fuel cell” is understood to mean a galvanic cell that converts the chemical reaction energy of a continuously supplied fuel, in this case hydrogen, and an oxidizer, in this case oxygen, into electrical energy. The resulting electrical energy can be used to power, for example, an electric motor (not shown), which in turn drives, for example, a ship’s propeller to propel vehicle 1.

[0052] A storage container 5 for storing liquid hydrogen is provided to supply hydrogen to the load 4. To ensure stable operation of the load 4, it is necessary to supply gaseous hydrogen to the load 4 at a specified supply pressure. The storage tank 5 is rotationally symmetric with respect to a central axis or axis of symmetry 6. The storage container 5 can be located, for example, inside the hull 2, particularly in the engine room, on the bridge 3, or on the deck of the hull 2, where the deck functions as a support structure 7.

[0053] The axis of symmetry 6 can be oriented perpendicular to the direction of gravity g. This means that the storage container 5 is positioned flat or horizontally. Thus, the axis of symmetry 6 is parallel to the support structure 7. However, the storage container 5 can also be positioned upright or vertically. In this case, the axis of symmetry 6 is oriented parallel to the direction of gravity g. If the vehicle 1 is, for example, a vehicle converted to hydrogen drive, the storage tank 5 can also be positioned, for example, within the funnel or stack of the vehicle 1.

[0054] In marine applications, the movement of liquid hydrogen contained in the storage tank 5 due to sea conditions must be anticipated. In the case of a horizontally positioned cylindrical storage container 5, sloshing of liquid hydrogen over a wide area is facilitated by the mass inertia of the liquid hydrogen and the curvature of the storage container present in both the cylindrical outer wall and the ends of the storage container due to the horizontal installation of the storage container.

[0055] This sloshing, also known as swashing, leads to the cooling of the gas phase above the liquid hydrogen, which in turn leads to a pressure drop in the gas cushion formed above the liquid hydrogen. Depending on the current state of the ocean, this could have an undesirable impact on the hydrogen supply pressure available to the operating components of Load 4, potentially causing instability in the operation of Load 4.

[0056] To provide supply pressure to load 4, a liquid-cooled, embedded liquid pump can be used to pump liquid hydrogen. However, such pumps have moving parts. In addition, in the case of intermittent pump operation, bubbles may form in the liquid hydrogen due to the pump overheating. This can lead to pump malfunction. Alternatively, the hydrogen can be vaporized first and then compressed to the required supply pressure using a compressor. However, this is undesirable from an energy usage standpoint.

[0057] Furthermore, the storage container 5 can also be operated directly by the supply pressure. In this case, an equilibrium state is established within the storage container 5 between the liquid phase and the gas phase layered on top of the liquid phase. Due to the low surface tension of liquid hydrogen, for example, when the storage container 5 is moved while it is positioned on the vehicle 1 as described above, the liquid phase and the gas phase mix with each other, and the liquid hydrogen cools the warmer gaseous hydrogen. In this case, it is impossible to maintain the supply pressure until an equilibrium state is established between the temperatures of the liquid hydrogen and the gaseous hydrogen.

[0058] Figure 2 shows a schematic diagram of an embodiment of the conveying device 8 which may have a storage container 5. Alternatively, the storage container 5 may not be part of the conveying device 8. The conveying device 8 is configured to continuously supply gaseous hydrogen H2 to the load 4 at a constant supply pressure of about 6 bara, regardless of the state of the sea or other movement of the storage container 5.

[0059] The storage tank 5 may also be referred to as a storage container. As described above, the storage container 5 is suitable for holding liquid hydrogen H2 (boiling point at 1 bar: 20.268 K = -252.882 °C). Therefore, the storage container 5 may also be referred to as a hydrogen storage container or hydrogen storage tank. However, the storage tank 5 can also be used for other cryogenic liquids. Examples of cryogenic fluids or liquids, i.e., refrigerants, in addition to the aforementioned liquid hydrogen H2, include liquid helium He (boiling point at 1 bar: 4.222 K = -268.928 °C), liquid nitrogen N2 (boiling point at 1 bar: 77.35 K = -195.80 °C), or liquid oxygen O2 (boiling point at 1 bar: 90.18 K = -182.97 °C).

[0060] Liquid hydrogen (H2) is contained in a storage container (5). As long as the hydrogen (H2) is in a two-phase region, a gaseous region (9) containing vaporized hydrogen (H2) and a liquid region (10) containing liquid hydrogen (H2) can be provided within the storage container (5). Therefore, after entering the storage container (5), the hydrogen (H2) has two phases in different condensation states, namely a liquid phase and a gaseous phase. This means that within the storage container (5), there is a phase boundary (11) between the liquid hydrogen (H2) and the gaseous hydrogen (H2).

[0061] The conveying device 8 includes conveying units 12A and 12B. Preferably, two conveying units 12A and 12B are provided, i.e., a first conveying unit 12A and a second conveying unit 12B. It is also possible to provide only one conveying unit 12A or 12B. The conveying units 12A and 12B can be operated intermittently.

[0062] The transport units 12A and 12B are constructed identically. The components of the first transport unit 12A are indicated by the letter "A" in Figure 2. Therefore, the components of the second transport unit 12B are indicated by the letter "B" in Figure 2. Below, only the first transport unit 12A will be described, but the description of the first transport unit 12A can be appropriately applied to the second transport unit 12B.

[0063] The first transport unit 12A includes a conditioning tank 13A suitable for containing hydrogen H2. The conditioning tank 13A may also be referred to as a conditioning vessel. With respect to the direction of gravity g, the conditioning tank 13A is located below the storage container 5. The conditioning tank 13A has a heating element 14A for introducing heat W into the hydrogen H2. Line 15A leads from the storage container 5 to the conditioning tank 14. Line 15A opens out of the storage container 5 on the lower side of the storage container 5. This means that line 15A opens out of the storage container 5 below the phase boundary 11, thereby allowing liquid hydrogen H2 to be supplied to the conditioning tank 13A. Line 16A branches off from line 15A toward the conditioning tank 13A.

[0064] Line 15A is equipped with valve V1A upstream of line 16A. Valve V1A is a shut-off valve. Valve V1A can be an on / off valve. Valve V1A is cold-resistant. This means that valve V1A performs its valve function even at extremely low temperatures, for example, at the boiling point of hydrogen H2 at -252.882°C. For example, valve V1A may be a solenoid valve or a shut-off valve. Valve V1A is preferably automatically actuated. Line 15A is equipped with valve V4A downstream of line 16A. Valves V1A and V4A can be constructed identically. Load 4 is located downstream of valve V4A. This means that line 15A leads to load 4.

[0065] Line 17A extends upward from the adjustment tank 13A in the opposite direction to gravity g. Line 17A opens into line 18A, which opens into the storage container 5 on the upper side, i.e., above the phase boundary 11. Line 18A has a valve V3A. Valve V3A may be the same as valves V1A and V4A. Upstream of valve V3A, line 19A branches off from line 18A and opens into the storage container 5 laterally. Line 19A opens into the storage container 5 below the phase boundary 11. Line 17A has a valve V2A. Valve V2A may be the same as valves V1A, V3A and V4A. The first transport unit 12A further includes a pressure control device 20A and a temperature control device 21A. The vaporizer 22 is connected upstream of the load 4. The vaporizer 22 can vaporize hydrogen H2 electrically or using a heat transfer medium.

[0066] The functions of the conveying device 8 or conveying units 12A and 12B are described below with reference to the pressure-enthalpy diagram shown in Figure 3. The pressure-enthalpy diagram is a phase diagram with specific enthalpy h on the horizontal axis and pressure p on the vertical axis. Figure 3 shows a log-ph diagram with pressure p scaled logarithmically. In Figure 3, a represents the two-phase region where the gaseous and liquid phases of hydrogen H2 coexist simultaneously. The pure gaseous phase is represented by b. The supercritical region is represented by c. The pure liquid phase is represented by d.

[0067] Figure 3 shows a two-phase line 23 with a critical point Pc. In thermodynamics, the critical point Pc is the thermodynamic state of a substance, in this case hydrogen H2, characterized by the equalization of densities in the liquid and gas phases. The difference between the two condensation states disappears at the critical point Pc. In this case, hydrogen H2 is in its supercritical state. At the critical point Pc, hydrogen H2 has a critical pressure pc of 12.3 bara and a critical temperature Tc of -239.9°C. The supply pressure p4 of load 4 is approximately 6 bara.

[0068] Gaseous hydrogen H2 is initially located in the adjustment tank 13A. The adjustment tank 13A can be depressurized by exhausting it into either the low-pressure system or the storage container 5. For this purpose, valves V1A, V2A, and V4A are closed and valve V3A is opened. The gaseous hydrogen H2 is introduced into the gaseous region 9 via lines 17A and 18A. Alternatively, valves V1A, V3A, and V4A can be closed and valve V2A can be opened. In this case, the gaseous hydrogen H2 is introduced into the liquid region 10 via lines 17A and 19A. The liquid hydrogen H2 in the storage container 5 then cools the supplied gaseous hydrogen H2, thereby causing the gaseous hydrogen H2 to condense at least partially.

[0069] Next, the adjustment tank 13A is filled with liquid hydrogen H2 via line 15A. For this purpose, valves V2A, V3A, and V4A are closed, and valve V1A is opened. Since the storage container 5 is positioned above the adjustment tank 13A with respect to the direction of gravity g, the liquid hydrogen H2 flows automatically into the adjustment tank 13A due to static pressure. The storage container 5 is completely or partially filled with liquid hydrogen H2. For example, the liquid hydrogen H2 in the storage container 5 or the adjustment tank 13A has a pressure p of 1 bara, a temperature T of -253°C, and a density ρ of 71 kg / m³. 3 Point A is the intersection of the two-phase line 23 and the one-bar line 24.

[0070] Next, the adjustment tank 13A is separated from the storage container 5 by closing valve V1A. Valves V2A, V3A, and V4A remain closed. Heat W is introduced into the liquid hydrogen H2 by the heating element 14A, increasing the pressure p in the adjustment tank 13A. This is shown in Figure 3 by the transition from point A to point B. At point B, the pressure p is 14 bara, the temperature T is -251°C, and the density ρ is 71 kg / m³. 3 Therefore, the pressure p is higher than the critical pressure pc.

[0071] The temperature T increases by 2°C during the transition from point A to point B. The hydrogen H2 in the regulating tank 13A is now in a supercritical state. Since there is no phase boundary in the supercritical state, movement of the regulating tank 13A, for example, at sea, does not have adverse effects. At point B, valve V4A is opened, and hydrogen H2 is supplied to load 4. The hydrogen H2 is vaporized using vaporizer 22 and supplied at a temperature T of 10-25°C and a supply pressure p4.

[0072] The initial filling of the adjustment tank 13A is simply a function of temperature T. Measurement of the filling level can be omitted. As previously mentioned, hydrogen H2 is discharged to load 4 by opening valve V4A. The pressure p in the adjustment tank 13A is simultaneously maintained at a pressure of 14 bara by further supply of heat W. The degree of filling is purely a function of temperature T. While the adjustment tank 13A is emptied and simultaneously heated, the density ρ of hydrogen H2 in the adjustment tank 13A steadily decreases through the process of emptying the adjustment tank 13A. The hydrogen H2 remains in a supercritical state, as before. This means that the hydrogen H2 in the adjustment tank 13A is single-phase.

[0073] Therefore, excellent, stable control of the hydrogen flow rate or hydrogen H2 flow rate from the regulating tank 13A is possible. When the regulating tank 13A is empty, single-phase process control prevents the formation of a two-phase gas-liquid mixture within the regulating tank 13A, which, in principle, is caused by a pressure drop within the regulating tank 13A. If a gas-liquid mixture is formed within the regulating tank 13A while it is being emptied, this could result in a discontinuous supply of hydrogen H2 to the load 4. This discontinuous supply of hydrogen H2 to the load 4 is caused, for example, by sloshing of the generated liquid phase, depending on whether the discharge nozzle of the regulating tank 13A is immersed in the gas phase or the liquid phase of hydrogen H2. However, this undesirable discontinuous supply of hydrogen H2 is reliably avoided or at least significantly reduced by single-phase process control.

[0074] The purely single-phase process control described above is shown in Figure 3 by the transition from point B to point C. At point C, the pressure p is 14 bara, the temperature T is -230°C, and the density ρ is 9.8 kg / m³. 3 Therefore, valve V4A remains open during the transition from point B to point C.

[0075] A temperature T is selected such that a significant decrease in density ρ occurs between point B and point C. This allows for maximum utilization of hydrogen H2. The temperature T reached at point C is a compromise between maximum utilization of hydrogen H2 and heat input to the storage container 5. Once a certain temperature T is reached, the transfer of hydrogen H2 to the load 4 is stopped. The temperature T is maintained, a certain pressure drop is allowed, and the adjustment tank 13A is further emptied.

[0076] Alternatively, the introduction of heat W can be stopped, and the temperature T in the adjustment tank 13A can be reduced by the expansion of supercritical hydrogen H2. This makes it possible to maximize the use of hydrogen H2. This is shown in Figure 3 by the transition from point C to point D. At point D, the hydrogen H2 has a supply pressure p4 of 6 bara, a temperature T of -242°C, and a density ρ of 6.2 kg / m³. 3 At point D, valve V4A is closed, and the hydrogen H2 is depressurized by being exhausted into the storage container 5 as described in the introduction. 92% hydrogen H2 utilization can be achieved.

[0077] As already mentioned above, the transport units 12A and 12B can be operated intermittently, so that, for example, the first transport unit 12A transports hydrogen H2 to the load 4, while the adjustment tank 13B of the second transport unit 12B is filled, for example. This intermittent operation makes it possible to continuously supply hydrogen H2 to the load 4 at the required supply pressure p4.

[0078] The advantages of the conveying device 8 or conveying units 12A and 12B are summarized below. Hydrogen H2 in the storage container 5 can be maintained in its equilibrium state, resulting in a long retention time for hydrogen H2. For purely mechanical reasons, it is sufficient to prevent sloshing using conventional partitions or walls. As a result, the storage container 5 can be constructed more easily. This results in a higher absorption capacity for hydrogen H2.

[0079] The storage container 5 can be operated within a suitable pressure range of 1 to 6 bara. The density ρ of saturated liquid hydrogen H2 is pressure-dependent. It is desirable that the storage container 5 operate at the lowest possible pressure p. For example, the density ρ is 71 kg / m³ when the pressure p is 1 bara. 3 , 60 kg / m³ when pressure p is 6 bara 3 When pressure p is 12 bara, the pressure is 28 kg / m³. 3 Except for valves V1A, V1B, V2A, V2B, V3A, V3B, V4A, and V4B, the conveying device 8 has no moving parts. Therefore, the conveying device 8 is very resistant to failure.

[0080] The hydrogen H2 in the regulating tanks 13A and 13B can be maintained in equilibrium. Walls or partitions to prevent sloshing are only required when the regulating tanks 13A and 13B are operating at a pressure p of less than 0.8*pc, preferably less than 0.9*pc. Hydrogen H2 can be removed from the regulating tanks 13A and 13B as a single-phase medium. The conveying device 8 can be used even under harsh conditions, such as rough seas, because no phase transition between the gas phase and liquid phase can occur, which could interfere with the operation of the load 4.

[0081] Since hydrogen H2 can be removed from the adjustment tanks 13A and 13B as a single-phase medium, stable and interference-free operation of the load 4 is possible. For example, since the stop temperature can be set at point C where the supply to the load 4 is stopped, the packing level control of the adjustment tanks 13A and 13B can be omitted. A simple pressure-temperature control scheme is possible using heating elements 14A and 14B. Since gaseous hydrogen H2 can be directly introduced into liquid hydrogen H2 via lines 19A and 19B, an equilibrium state can be quickly achieved in the storage container 5.

[0082] Figure 4 shows a schematic block diagram of an embodiment of a method for transporting hydrogen H2 using a transport device 8. In step S1, hydrogen H2 is introduced from the storage container 5 into the adjustment tanks 13A and 13B. For this purpose, valves V1A and V1B are opened. Valves V2A, V2B, V3A, V3B, V4A and V4B are closed. The hydrogen H2 is introduced into the adjustment tanks 13A and 13B due to the static pressure of the hydrogen H2 contained in the storage container 5. For this purpose, the storage container 5 is positioned above the adjustment tanks 13A and 13B with respect to the direction of gravity g.

[0083] In step S2, the hydrogen H2 contained in the adjustment tanks 13A and 13B is brought to a supercritical state. For this purpose, valves V1A and V1B are closed. Heat W is introduced into the adjustment tanks 13A and 13B by heating elements 14A and 14B. The pressure p in the adjustment tanks 13A and 13B rises until it reaches a supercritical state.

[0084] In process S3, hydrogen H2 is introduced from adjustment tanks 13A and 13B to load 4, and the hydrogen H2 contained in adjustment tanks 13A and 13B is maintained in a supercritical state during process S3. For this purpose, heat W is continuously introduced into adjustment tanks 13A and 13B during process S3. Valves V1A and V1B are open.

[0085] Although the present invention has been described with reference to exemplary embodiments, the present invention can be modified in various ways. [Explanation of Symbols]

[0086] 1 Vehicle 2 hull 3 Funabashi 4 load 5 Storage tanks 6. Axis of Symmetry 7 Support structure 8. Conveying device 9. Gas Region 10 liquid area 11 phase boundary 12A Transport Unit 12B Transport Unit 13A Adjustment Tank 13B Adjustment Tank 14A Heating element 14B heating element 15A line 15B Line 16A line 16B Line 17A Line 17B Line 18A Line 18B Line Line 19A 19B Line 20A Pressure Control Device 20B Pressure control device 21A Temperature control device 21B Temperature control device 22 Vaporizer 23 Two-phase line 24 1 bar line a Two-phase region Point A b. Gas phase Point B c Supercritical range Point C d liquid phase D point h enthalpy H2 Hydrogen / Cryogenic Agent p pressure PC critical pressure Pc critical point p4 Supply pressure S1 process S2 process S3 process T temperature Tc critical temperature V1A valve V1B valve V2A valve V2B valve V3A valve V3B valve V4A valve V4B valve W heat ρ density

Claims

1. A method for transporting a refrigerant (H2) from a storage container (5) to a load (4), wherein the method is: a) A step (S1) of introducing the cryogenic agent (H2) from the storage container (5) into the adjustment tanks (13A, 13B), wherein the cryogenic agent (H2) flows from the storage container (5) into the adjustment tanks (13A, 13B) solely due to the hydrostatic pressure of the cryogenic agent. b) A step (S2) of bringing the cryogen (H2) contained in the adjustment tanks (13A, 13B) to a supercritical state. c) A step (S3) of discharging the cryogenic agent (H2) from the adjustment tanks (13A, 13B) to the load (4), wherein the cryogenic agent (H2) contained in the adjustment tanks (13A, 13B) is maintained in the supercritical state during step c), A method wherein the adjustment tanks (13A, 13B) are depressurized by exhausting into the load (4) until the supply pressure (p4) of the load (4) is reached.

2. The method according to claim 1, wherein, after step a), the adjustment tanks (13A, 13B) are separated from the storage container (5) via the valves (V1A, V1B) by closing the valves (V1A, V1B).

3. The method according to claim 1 or 2, wherein in step c), valves (V4A, V4B) provided between the adjustment tanks (13A, 13B) and the load (4) are opened.

4. The method according to any one of claims 1 to 3, wherein during step b), heat (W) is introduced into the adjustment tanks (13A, 13B) to bring the cryogen (H2) to the supercritical state.

5. The method according to any one of claims 1 to 4, wherein during step c), heat (W) is introduced into the adjustment tanks (13A, 13B) to maintain the cryogenic agent (H2) in the supercritical state.

6. The method according to any one of claims 1 to 5, wherein during step c), the density (ρ) of the cryogenic agent (H2) in the adjustment tanks (13A, 13B) decreases.

7. The method according to any one of claims 1 to 6, wherein the pressure (p) in the adjustment tanks (13A, 13B) is kept constant during step c).

8. The method according to any one of claims 1 to 7, wherein step c) is terminated after a predetermined temperature (T) has been achieved in the adjustment tanks (13A, 13B).

9. The method according to claim 1, wherein the adjustment tanks (13A, 13B) are depressurized by exhausting into the storage container (5) when the supply pressure (p4) is achieved.

10. The method according to any one of claims 1 to 9, wherein the first adjustment tank (13A) and the second adjustment tank (13B) are operated intermittently.

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