Ventilation system for a vehicle with liquefied natural gas cryogenic tanks

Abstract

Venting arrangement (20) for a vehicle (1) with a fuel system powered by liquefied natural gas, wherein the vehicle (1) has a pair of cryogenic tanks (10, 10') for storing the liquefied natural gas, which are mounted on the chassis (4) of the vehicle (1), and wherein the venting arrangement (20) has a venting pipe (16) configured for venting the cryogenic tanks (10, 10') and which is connected to the respective cryogenic tanks (10, 10'), and wherein the venting pipe (16) has a vent connector (15) with a shut-off valve (25) configured for releasing vapor from the cryogenic tanks (10, 10') into the atmosphere, wherein each of the cryogenic tanks (10, 10') is connected to the vent connector (15) via the venting pipe (16), which comprises a pair of hand valves (14, 14') each connected to an associated cryotank (10, 10') and between the associated cryotank (10,10') and the vent connector (15), wherein the vent pipe (16) further comprises a pair of shut-off valve devices (17, 17'), each of which shut-off valve devices (17, 17') is arranged between the associated hand valve (14, 14') and the vent connector (15) and is configured to allow a flow of steam out of the cryogenic tank (10, 10') at a first predetermined pressure and to allow a flow of steam into the cryogenic tank (10, 10') at a second predetermined pressure, wherein the first predetermined pressure is less than the second predetermined pressure.

Description

TECHNICAL AREA

[0001] The present invention relates to a venting arrangement for a vehicle with a fuel system which is operated with liquefied natural gas (LNG), and it relates to a vehicle with the arrangement according to the definitions in the attached claims. STATE OF THE ART

[0002] Natural gas, which consists mainly of methane, can be used as a fuel for vehicles, such as heavy-duty vehicles like trucks or buses. The vehicle has a fuel system designed to use natural gas either in compressed natural gas (CNG) or as liquefied natural gas (LNG). LNG is stored at low temperatures, around -120°C, inside a cryogenic tank mounted on the vehicle's chassis. The cryogenic tank contains both the liquid and gaseous phases of the LNG, and a pressure of 10-16 bar is maintained within the tank. Instead of a pump, the vapor pressure is primarily used to supply the engine with fuel.

[0003] A cryogenic tank is a thermally insulated system consisting of two containers: an inner and an outer container. The inner container is surrounded by the outer container, and a low-conductivity ceramic material is placed between them to provide insulation, creating a vacuum between the containers. Storing methane as liquefied natural gas (LNG) in a cryogenic tank increases the fuel's density. LNG is less dense than petroleum-based fuels such as diesel. Therefore, two LNG cryogenic tanks are frequently used in heavy-duty vehicles, one on each side of the chassis. With two cryogenic tanks, the LNG fuel is sufficient for a range of approximately 1000 km.

[0004] To protect the cryogenic tank and maintain a set pressure, vapor is released from it. Releasing gas in its vapor phase from the storage vessel is called venting (ventilation). (The term "venting" here is used metaphorically and refers to the release of gaseous natural gas.) The rate of pressure build-up depends on the quality of the insulation and the amount of liquefied natural gas in the cryogenic tank; for example, the pressure builds up more slowly with a higher fuel content. The cryogenic tanks are exposed to ambient air, and the warmer the ambient temperature, the more heat is transferred to the cryogenic tank. This heat transfer warms the liquefied natural gas, causing it to vaporize and thus increasing the pressure inside the storage vessel. The vaporized natural gas resulting from this heating is also called exhaust gas.To prevent excessive pressure buildup in the storage vessel when the vehicle engine is not running, the cryogenic tank is equipped with a venting unit consisting of a primary and a secondary relief valve. The primary relief valve opens when the pressure in the storage vessel exceeds a lower initial threshold, for example, at approximately 16 bar, to release natural gas in its vapor phase and thus reduce the pressure. The secondary relief valve opens when the pressure in the storage vessel exceeds a higher second threshold, for example, at approximately 24 bar, to release vapor, such as exhaust gas, from the storage vessel if the primary relief valve malfunctions.

[0005] To fill the cryogenic tanks, a fuel hose is connected to one of the tanks, and liquid fuel is injected. The cryogenic tanks can be interconnected via fuel lines. The cryogenic tank pressure should preferably be around 9-10 bar when filling begins. As the cryogenic tank fills, the pressure increases, and the filling process is stopped at 16 bar. If the pressure is higher than 9-10 bar, a venting connector can be used to reduce the pressure in the cryogenic tanks. The filling and venting connectors can have a shut-off valve that is activated when the connection is made. Therefore, if a venting connector is equipped with a shut-off valve, the valve, which normally prevents vapor from escaping into the atmosphere, can be activated to allow venting of the cryogenic tanks via the venting connector.The filling connector may additionally have a shut-off valve downstream of a connector, which prevents fuel from leaking from the cryogenic tank in the event of a connector malfunction. The venting connector, however, may not have an additional shut-off valve, as this would block the flow from the cryogenic tank. Instead, a manually operated vent valve is fitted to each cryogenic tank, which must be opened manually. During normal operation, if both manually operated valves are open, the vapor in the cryogenic tanks is in direct contact with each other. If the cryogenic tanks are separated, i.e., if the manually operated valves are closed, the pressure in the empty cryogenic tank drops, and liquid is drawn from the other cryogenic tank, which is the desired operation of the fuel system.

[0006] The manually operated valves serve as a safety device for the fuel system, which uses liquefied natural gas as fuel; however, there is still a need to improve the safety and usability of venting systems.

[0007] The subsequently published EP 3 470 252 A1 relates to a tank system for a vehicle, with at least two tanks for holding a cryofluid, wherein a vent line is connected to each tank, which is fitted with a shut-off valve at its tank-side end and is led to a vent coupling common to all tanks for the connection of a suction hose, wherein the vent lines are led to the common vent coupling via a changeover valve. BRIEF DESCRIPTION OF THE INVENTION

[0008] Existing venting systems have problems, and this is especially true for manually operated valves used with them. For example, when filling cryogenic tanks, manually operated valves (hereinafter referred to as "manual valves") must be opened in conjunction with both cryogenic tanks to vent them. After filling is complete, the manual valves must be closed. Thus, the manual valves must be operated both before and after the filling process, and this also applies to every maintenance task, increasing the workload. Furthermore, each filling process requires walking from one side of the vehicle to the other twice, which is an additional step and makes filling cryogenic tanks more labor-intensive compared to diesel vehicles. Manual valves can also become dirty and are sometimes difficult to access.

[0009] If the valves are not closed after filling, a steam line between the cryogenic tanks remains open. This poses a risk of pressure loss in the fuel system, for example, if steam is only to be drawn from an empty cryogenic tank. With an open connection, there is also access to the steam from the other cryogenic tank. This means there is a risk that the overall system pressure will be reduced instead of switching from the empty cryogenic tank to the other one.

[0010] Since the valves are opened and closed manually, there is a risk that the operator / technician will forget to close them, which in turn significantly increases the risk of malfunctions. If the cryogenic tank is overfilled, liquid can become trapped between the manual valves. If the manual valves are then closed, there is a risk that a pipe connecting the cryogenic tanks will burst.

[0011] If, during work in a workshop, a technician forgets to open one or both manual valves to remove and / or vent steam, the steam is released through the "normal" duct, i.e., via a vent outlet, which may be located behind the vehicle's cab. The venting / removal does not occur via a venting device that can be connected to a vent connector during refueling or maintenance. This results in the release of primarily methane inside the workshop, which is highly undesirable.

[0012] The above problems are overcome by the solution given here according to the attached patent claims.

[0013] The present invention relates to a venting arrangement for a vehicle having a liquefied natural gas (LNG) fuel system. The vehicle has a pair of cryogenic tanks for storing LNG, which are mounted on the vehicle's chassis. The venting arrangement has a vent pipe for venting the cryogenic tanks, wherein the vent pipe is connected to the respective cryogenic tanks, and wherein the venting arrangement has a vent connector with a shut-off valve configured to discharge vapor from the cryogenic tanks to the atmosphere. Each of the cryogenic tanks is connected to the vent connector via the vent pipe, wherein the vent pipe has a pair of manual valves connected to the respective cryogenic tank and arranged between the respective cryogenic tank and the vent connector.The venting line further comprises a pair of shut-off valves, each valve being positioned between its respective hand valve and the vent connector. These valves allow the flow of gas in the vapor phase from the cryogenic tank at a first predetermined pressure and the flow of gas in the vapor phase into the cryogenic tank at a second predetermined pressure, where the first predetermined pressure is lower than the second. The first predetermined pressure can be in the range of 0-1 bar, but there is no limitation in this respect. The second predetermined pressure can be, for example, in the range of 7-8 bar, but is also not limited to this range. For instance, the second predetermined pressure can be 5-9 bar higher than the first predetermined pressure.

[0014] The venting system ensures simple and robust venting of the cryogenic tanks, minimizing the risk of malfunctions caused by incorrectly adjusted manual valves. It also minimizes the risk of sudden pressure drops in the cryogenic tanks, resulting in a more stable fuel supply to the gas-powered engine. If the cryogenic tanks are overfilled, no pipes are under pressure. Furthermore, the system provides additional redundancy for the pressure relief valves.

[0015] The shut-off valve assembly can have two shut-off valves, one configured to allow the flow of gas in the vapor phase from the cryogenic tank, while the other configured to allow the flow of gas in the vapor phase into the cryogenic tank. This provides a simple and robust assembly. The shut-off valves can be passive. In this case, no electrical control is required, so the assembly functions even when no electrical power is available in the vehicle. Alternatively, the shut-off valves can be electrically actively controlled. The active shut-off valves can be connected to and configured for control by the vehicle's control system. This provides a more precise and adaptable shut-off valve assembly.

[0016] The manual valves can be configured for opening / closing using a tool specifically designed for this purpose. This reduces the risk of the valves being left in an incorrect position. The manual valves can also be configured to be in an open position when the vehicle is in operation, while they are in a closed position when work is being carried out on the vehicle's vent connector. This eliminates the need to activate the valves during normal operation and when filling the cryogenic tanks, thus reducing the workload of the venting system.

[0017] The present invention also relates to a vehicle with a ventilation arrangement as described above.

[0018] Further features and advantages are described in more detail below with reference to the attached figures. BRIEF DESCRIPTION OF THE FIGURES Fig. Figure 1 schematically shows a vehicle with a ventilation arrangement according to the present description in side view; Fig. Figure 2 schematically shows the functional diagram of the venting arrangement according to the present description; and Fig. Figure 3 schematically shows a hand valve and a tool for opening the valve. DESCRIPTION OF DETAILS

[0019] An example of a vehicle 1 is according to Fig. 1 A heavy-duty truck with a fuel system powered by liquefied natural gas (LNG). The vehicle 1 has a chassis 4, which is configured at the front to support a driver's cab 5 and at the rear to support a loading device (not shown). The vehicle 1 is equipped with a gas engine 2, which drives the vehicle's driven wheels 8 via a gearbox 6 and a driveshaft 7. The engine 2 is powered by liquefied natural gas fuel, which is supplied from a cryogenic tank 10. The cryogenic tank has a storage container 11 in which liquefied natural gas is stored and used as fuel for the engine.

[0020] The vehicle can carry at least two cryotanks of 10.10' (see Fig. 2) each have one on each side of the chassis 4, to which the cryogenic tanks 10, 10' are attached by means of suitable fastening means 9, which may, for example, be metal straps, but there is no restriction in this respect. The cryogenic tanks 10, 10' are provided with a venting arrangement 20, which is connected to the cryogenic tanks 10, 10', which have storage containers 11, 11'.

[0021] The storage tanks further comprise a primary relief valve (not shown) and a secondary relief valve (not shown). The primary relief valve opens when the pressure in storage tank 11 exceeds a lower first threshold, for example, at approximately 16 bar, to release exhaust gas, i.e., natural gas in the vapor phase, which is produced when the temperature in storage tank 11 rises. This releases the vaporous gas from storage tank 11, thus reducing the pressure in the tank. The secondary relief valve opens when the pressure in storage tank 11 exceeds a higher second threshold, for example, in the range of 24 bar, to release exhaust gas from storage tank 11 in a situation where the primary relief valve malfunctions.The cryogenic tanks 10, 10' are connected to a vent outlet 13, which is connected to the primary relief valve, whereby exhaust gas released from the storage container 11 via the first relief valve leaves the cryogenic tank 10 via this vent outlet 13, which may be located behind the cabin 5 of the vehicle.

[0022] The vehicle also has a venting arrangement 20 as described herein, in which a manual valve 14, 14' is provided for each cryogenic tank 10, 10'. A manual valve is understood here to be a valve that is operated manually or by means of a tool, i.e., a valve that is not automatically or electrically operated. The manual valves 14, 14' are connected to the cryogenic tanks 10, 10', for example, via a valve adapter 12. The manual valves are to be opened to vent the cryogenic tanks during filling and / or maintenance work (to remove vapor / gas). The venting arrangement also has a vent connector 15 with a shut-off valve 25 (see Fig. 2) The vent connector 15 is arranged in a vent pipe 16 between the hand valves 14, 14' and it is used to vent the cryotanks, for example when filling the cryotanks.

[0023] To fill the cryogenic tanks 10, 10', a fuel connection (not shown) can be connected to one of the cryogenic tanks, and liquid fuel is forced into the tank. The cryogenic tanks are connected to each other via lines and are therefore filled simultaneously. The cryogenic tank pressure can be, for example, around 9-10 bar when the filling process begins and will increase as the tank fills, stopping at around 16 bar. If the pressure is higher than 9-10 bar, the vent connector 15 can be used to reduce the pressure in the cryogenic tanks. The vent connector 15 can be used to close the shut-off valve 25 (see Fig. 2) which is activated when connected to a venting tool for venting. The fuel connection may additionally have a second shut-off valve which prevents fuel from leaking from the cryogenic tank if the connector malfunctions. By connecting the venting tool, the venting (release) of gas in the vapor phase can be carried out in a controlled manner via the venting connector.

[0024] Fig. Figure 2 shows the venting arrangement 20 according to the present invention in further detail. The venting arrangement 20 has the aforementioned vent connector 15, which includes the shut-off valve 25. During normal operation, the shut-off valve 25 is closed, thus providing redundancy with respect to the escape of exhaust gas via the vent connector. However, exhaust gas can be vented via the vent outlet 13 when the temperature in the cryogenic tanks rises. For example, during filling of the cryogenic tank and / or maintenance work, the shut-off valve 25 can be activated by attaching a connector or a connecting tool (not shown), which corresponds to the shut-off valve. This activates the shut-off valve 25, causing it to open and allowing steam to be released from the cryogenic tanks 10 and 10'.

[0025] To vent the cryogenic tanks, for example during maintenance work, the manual valves 14, 14' connected to each cryogenic tank 10, 10' are opened, thus reducing the pressure inside the cryogenic tanks if desired. The manual valves are normally closed during vehicle operation and are opened for maintenance. If both manual valves 14 are left open during normal operation after maintenance, there is a risk of vaporous gas in the cryogenic tanks coming into direct contact with each other. This poses a risk of a pressure drop in the fuel system, which can lead to fuel supply problems. If the cryogenic tanks are separated, i.e., the manual valves are closed, the pressure in the empty cryogenic tank drops, and fluid can be drawn from the other cryogenic tank. This is the intended function of the fuel system without a pump.

[0026] In operation, liquid is drawn off via a liquid pipe 29, 29' inside the respective associated cryogenic tank 10, 10', with said pipe located at the bottom, while steam pipes 28, 28' and filling pipes 26, 26' are positioned in the upper part of the cryogenic tank. The cryogenic tanks supply liquid fuel to the engine 33 downstream of the cryogenic tanks when the pressure is below 10 bar, while steam is supplied when the pressure is above 10 bar. This ensures that the pressure in the cryogenic tanks does not drop too low, which would lead to torque limitations or, if the pressure falls below a minimum pressure, to a "vehicle off the road" (VOR) condition, i.e., a shutdown of the vehicle. Each cryogenic tank 10, 10' is connected to an adjusting valve 27 or 27', respectively.The control valve can, for example, be a synchronized economizer, and it controls whether liquid or vapor is supplied from the respective cryogenic tank 10 according to the cryogenic tank pressure. If liquid is drawn from the cryogenic tank and the cryogenic tank is emptied, then vapor is drawn off instead. The cryogenic tanks 10, 10' can also have a liquid level sensor, and the fuel supply can be additionally or alternatively based on the liquid level in the respective cryogenic tank 10, 10'. The liquid level sensors can be connected to a control unit of the vehicle, and the control valves can be controlled based on the detected liquid level. Fig. 2. When cryogenic tank 10 is nearly empty and the liquid level 22 is below a value at which the liquid pipe 29 extends into the liquid natural gas, steam is supplied to the engine supply 33 via supply line 30. If the pressure falls below a predetermined pressure value, e.g., 9 bar, which can be measured by a pressure sensor 31 in the engine supply line 33, the automatic shut-off valve downstream of the control valve 27 interrupts the flow from cryogenic tank 10. Instead, fuel is supplied from cryogenic tank 10' on the right, which has a higher level of liquid natural gas, via supply line 30'. The shut-off valve and the control valves can be active valves, i.e., electronically controllable by a vehicle control unit. The control unit can control the automatic shut-off valve based on a pressure value measured by a pressure sensor 31.Therefore, if the pressure of the cryogenic tank 10 falls below a predetermined value, e.g. 9 bar, the control system is set up to generate a signal to the shut-off valve to close the shut-off valve 23, thereby supplying liquid natural gas from the cryogenic tank 10'.

[0027] Fuel should ideally be drawn evenly from each cryogenic tank. However, since the pipe lengths of the cryogenic tanks vary and the valves have certain tolerances, in practice one of the cryogenic tanks is often used more frequently than the other and is therefore emptied first, after which the other cryogenic tank is emptied. If the vehicle is in a workshop for maintenance or repair purposes, it should be ensured that exhaust gas is not vented into the workshop. To prevent gas from entering the workshop, a venting tool can be adapted to the venting connector 15, allowing the venting to take place at a desired time and location. The hand valves must then be open so that the tool can release gas from the cryogenic tanks 10 and 10' via the venting assembly 20.

[0028] The present invention reduces problems associated with the use of manual valves by means of the venting arrangement 20 described herein. Each of the cryogenic tanks 10, 10' is connected to the common venting connector 15 via a venting pipe 16, the venting pipe 16 being configured to vent the cryogenic tanks 10, 10' and being connected to the respective cryogenic tank. The venting pipe 16 extends between the cryogenic tanks 10, 10' and connects the cryogenic tanks 10, 10' and their storage containers 11, 11', and it has the venting connector 15 between the cryogenic tanks. The venting connector 15 has the shut-off valve 25, which is configured to discharge gas in the vapor phase, i.e., the vapor phase of the natural gas, from the cryogenic tanks at the point where the cryogenic tanks are filled.The shut-off valve 25 can be actuated to release steam by attaching a tool (not shown) adapted for actuating the shut-off valve 25, thus opening the shut-off valve 25. The vent pipe 16 has a pair of manual valves 14, 14', as described above, which are connected to the respective cryogenic tanks 10, 10' and which are positioned between the respective cryogenic tank and the vent connector 15, e.g., in the valve adapter 12 (see figure). Fig. 1 and Fig. 3) The vent pipe 16 further comprises a pair of shut-off valve assemblies 17, 17', each of which is arranged between its respective associated manual valve 14 or 14' and the vent connector 15. This arrangement allows gaseous natural gas to flow out of the cryogenic tank at a first predetermined pressure, while gaseous natural gas can flow into the cryogenic tank at a second predetermined pressure, the first being lower than the second. With this venting arrangement, the manual valves do not need to be operated during normal vehicle operation, including refueling of the cryogenic tanks, because the manual valves can always remain in the open position. Therefore, when refueling the cryogenic tanks, the operator never needs to activate the manual valves, making the fuel system less prone to failure.The risk of malfunctions or shutdowns due to incorrect manual valve positions is considerably reduced. The manual valves only need to be closed when the vent connector 15 requires maintenance and has been removed. In this case, the valves in the valve assemblies 17, 17' must also be closed.

[0029] The first preset pressure can be set as desired, but it should ideally be in the range of 0-1 bar, although there is no further restriction. The second preset pressure is higher than the first, but can be set so that the pressure difference between the cryogenic tanks does not become too large; for example, it can be in the range of 7-8 bar, although again there is no further restriction. Thus, the shut-off valve that opens for flow out of the cryogenic tank is set to open at a very low back pressure to ensure proper venting. The shut-off valve that opens for flow into the cryogenic tank, however, is set higher, for example, to approximately 7-8 bar, which means that the pressure difference between the cryogenic tanks cannot exceed 7-8 bar.Therefore, if one cryogenic tank empties first, the pressure difference between the tanks decreases, and consequently, no flow occurs. If one cryogenic tank runs dry, the other only reduces its pressure to 7-8 bar but does not empty further. Even if this happens, the fuel system remains capable of delivering full power. The shut-off valves provide double redundancy with respect to the pressure relief valves, as the relief valves of the other cryogenic tank are used despite an increased pressure difference of 7-8 bar due to the shut-off valve. With the current state of the art, if the primary relief valve fails to function and does not open, there is no redundancy with respect to the cryogenic tank. By adding the shut-off valves described above, at 24 bar, where the secondary relief valve should open, the primary valve of the other cryogenic tank is also close to the open position (24 - 8 = 16 bar).At 32 bar, the secondary pressure relief valve of the other cryogenic tank opens if both primary pressure relief valves and one secondary pressure relief valve are not functioning.

[0030] Fig. Figure 2 shows an example of the shut-off valve assembly 17, 17'. Each shut-off valve assembly 17, 17' has two shut-off valves 171, 172 and 171', 172', respectively. The first shut-off valves 171, 171' are configured to allow steam to flow out of the cryogenic tank, while the second shut-off valves 172, 172' are configured to allow steam to flow into the cryogenic tank. The first shut-off valves 171, 171' are configured to allow steam to flow out of the cryogenic tank at a first predetermined pressure, which can be between 0 and 1 bar. The second shut-off valves 172, 172' are configured to allow steam to flow into the cryogenic tank at a second predetermined pressure, which can be between 7 and 8 bar. Thus, the first specified pressure is lower than the second specified pressure, which allows venting of the cryotanks while maintaining a high pressure difference between the cryotanks.Each of the shut-off valves 171, 172; 171', 172' is configured to open at the first and / or second predetermined pressure. Each of the shut-off valves 171, 172; 171', 172' may, for example, incorporate a spring or another mechanical solution, such as a pressure-sensitive diaphragm, as long as the valve opens at the desired pressure. These shut-off valves are passive valves, which are simple and robust. Alternatively, the shut-off valves 171, 172; 171', 172' can also be electrically controlled, i.e., so-called active valves. The electrically controlled shut-off valves can be connected to a vehicle control unit, and the inlet / outlet vapor pressure can be measured by means of a pressure sensor located upstream or downstream of the shut-off valve assembly.The double shut-off valves 171, 172; 171', 172' ensure that expansion of the heating fuel is not prevented in the event of overfilling. Furthermore, they ensure that no pipes are under excessive pressure, which could cause malfunctions or even a vehicle stoppage.

[0031] The hand valves 14, 14' can be configured to be opened / closed by means of a tool 141, which is adapted for opening / closing the valves, as shown schematically in Fig.Figure 3 illustrates this. For example, a wheel 142 of the manual valves 14, 14' can be designed so that a suitable tool can grip the respective wheel precisely. The tool and the manual valves can thus be designed to ensure a fit between the engaging parts, allowing the tool to rotate the wheel of the manual valve. This reduces the possibility of unintentional closure of the manual valve. As described above, the manual valves are in an open position when the vehicle is in operation, while they are in a closed position during maintenance work on the vehicle's vent connector. Only when maintenance work on the vent connector is required is it necessary to close the manual valves 14, 14' or the valves of the shut-off valve assemblies 17, 17'.This also means that the risk of exhaust gas being discharged into the workshop via the vent outlet 13 behind the driver's cab is reduced, since the hand valves are already open.

[0032] The above description of the present invention serves illustrative and explanatory purposes. It is not exhaustive, nor does it limit the invention to the described variants; rather, the limits of the invention are defined by the scope of the accompanying claims. Many modifications and alterations are obvious to a person skilled in the art. The exemplary embodiments were chosen and described in detail to best illustrate the fundamentals of the invention and its practical applications, thus enabling a person skilled in the art to understand the invention and its various embodiments with the possible modifications according to the intended use.

Claims

[1] Venting arrangement (20) for a vehicle (1) with a fuel system powered by liquefied natural gas, wherein the vehicle (1) has a pair of cryogenic tanks (10, 10') for storing the liquefied natural gas, which are attached to the chassis (4) of the vehicle (1), and wherein the venting arrangement (20) has a venting pipe (16) which is configured to vent the cryogenic tanks (10, 10') and which is connected to the respective cryogenic tanks (10, 10'), and wherein the venting pipe (16) has a vent connector (15) with a shut-off valve (25) which is configured to release vapor from the cryogenic tanks (10, 10') to the atmosphere, wherein each of the cryogenic tanks (10, 10') is connected to the vent connector (15) via the venting pipe (16), which is a pair of hand valves (14, 14') each connected to an associated cryotank (10, 10') and between the associated cryotank (10,10') and the vent connector (15), wherein the vent pipe (16) further comprises a pair of shut-off valve devices (17, 17'), each of which shut-off valve devices (17, 17') is arranged between the associated hand valve (14, 14') and the vent connector (15) and is configured to allow steam to flow out of the cryogenic tank (10, 10') at a first predetermined pressure and to allow steam to flow into the cryogenic tank (10, 10') at a second predetermined pressure, wherein the first predetermined pressure is less than the second predetermined pressure. [2] Venting arrangement (20) according to claim 1, characterized by that the first specified pressure is in the range of 0-1 bar. [3] Venting arrangement (20) according to one of claims 1 or 2, characterized by that the second specified pressure is in the range of 7-8 bar. [4] Venting arrangement (20) according to one of the preceding claims, characterized by , that each of the shut-off valve arrangements (17, 17') has two shut-off valves (171, 172; 171', 172'), wherein one shut-off valve (171, 171') is configured to allow a flow of steam out of the cryogenic tank (10, 10'), while the other shut-off valve (172, 172') is configured to allow a flow of steam into the cryogenic tank (10, 10'). [5] Venting arrangement (20) according to claim 4, characterized by , that the shut-off valves (171, 172; 171', 172') are passive valves. [6] Venting arrangement (20) according to claim 4, characterized by , that the shut-off valves (171, 172; 171', 172') are electrically controllable active valves. [7] Venting arrangement (20) according to one of the preceding claims, characterized by, that the hand valves (14, 14') are set up to be opened / closed by means of a tool (141), wherein the tool (141) is adapted for opening / closing the valves (14, 14'). [8] Venting arrangement (20) according to one of the preceding claims, characterized by , that the hand valves (14, 14') are set up for an open position during operation of the vehicle (1) and for a closed position during maintenance work on the vent connector (15) of the vehicle (1). [9] Vehicle (1) with the ventilation arrangement (20) according to any one of the preceding claims 1 to 8.

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