Device for regulating the pressure of aircraft cryogenic fuel tanks

Abstract

Device (2) for regulating the pressure in an onboard tank (3) for storing cryogenic fuel intended to supply a combustion chamber (10) of an aircraft turbine engine (1), comprising: a tank (3); a mixing chamber (100); a first line (41) for supplying liquid fuel and a second line (42) for supplying gaseous fuel, the first and second lines connecting the tank (3) to the mixing chamber (100), the mixing chamber being configured to be connected to the combustion chamber (10); a recirculation line (43) connecting the lower part of the tank (3) to the upper part of the tank, the line being equipped with a first heat exchanger (430) enabling the cryogenic fuel to be transformed from the liquid state to the gaseous state; a pressure sensor (5) for the pressure in the tank (3); a central control unit (7) receiving data from the pressure sensor (5) and controlling the circulation of the flows in the aforementioned lines as a function of the pressure data on the pressure in the tank (3).

Description

Technical Field

[0001] The invention belongs to the field of aircraft turbomachines whose combustion chambers are supplied with cryogenic fuel.

[0002] The invention relates more particularly to a device for regulating the pressure in a storage tank for cryogenic fuel, such as natural gas, partly in liquid form and partly in gaseous form, which fuel supplies the combustion chambers of aircraft turbines.

[0003] The invention also relates to an aircraft comprising at least one on-board cryogenic fuel tank and at least one turbine provided with a combustion chamber operated with said cryogenic fuel, and equipped with a pressure regulating device as described above.

[0004] The invention also relates to an assembly for regulating the pressure in such a tank, comprising an aircraft and an airport installation as described above.

[0005] The present invention finally relates to a method for regulating the pressure in an onboard cryogenic fuel storage tank, the method being performed using the regulating device or the regulating assembly described above. Background Art

[0006] Cryogenic fuels are commonly used in space propulsion due to their improved thermodynamic efficiency. However, their application in aviation and large-scale industrial use has necessitated the resolution of several technical challenges, particularly regarding their storage.

[0007] An example of a cryogenic fuel is, for example, liquefied natural gas (GNL).

[0008] Liquid cryogenic fuel stored in tanks tends to heat up, change state, and thereby vaporize, which causes the pressure within the tanks containing the liquid cryogenic fuel to increase.

[0009] In the absence of a means of satisfactorily regulating the pressure within storage tanks for this type of fuel, it is customary to size the tanks so that they can absorb significant pressure variations. This results in an increase in the thickness of the tank walls, which makes the tank heavier, and generally limits the tanks to cylindrical or spherical shapes.

[0010] However, a continuing problem in the field of aviation is to reduce as much as possible the weight of the equipment contained in the aircraft.In addition, due to the location of the tank, it may be advantageous for the tank to have a shape other than a cylindrical or spherical shape.

[0011] A device for regulating the pressure in an onboard cryogenic fuel storage tank, intended to supply the combustion chambers of an aircraft turbine, is known from document US 2014 / 174106.

[0012] The device comprises a recirculation line connecting a pump located at the lower part of the onboard tank to the upper part of the tank and equipped with a regulating valve and a heat exchanger enabling the cryogenic fuel to be transformed from a liquid state to a gaseous state.

[0013] The device also comprises pipelines connecting the tank to the combustion chamber and a central control unit which controls the opening or closing of the various regulating valves and the starting or stopping of the pump.

[0014] However, this document does not describe or suggest other features of the present invention. Summary of the Invention

[0015] The present invention aims to propose a device that makes it possible to regulate the pressure inside an onboard storage tank for cryogenic fuel in order to keep the pressure inside the onboard storage tank within a lower pressure range than that existing in the state of the art, without having to increase the mechanical strength of the tank and thus reducing the weight of the tank.

[0016] To this end, the invention relates to a device for regulating the pressure in an onboard storage tank for cryogenic fuel, for example natural gas, part of which is liquid and another part of which is gaseous, intended to supply the combustion chambers of an aircraft turbine.

[0017] According to the present invention, the device comprises:

[0018] - an onboard tank, which is used to store cryogenic fuel and supply cryogenic fuel to the combustion chamber, and the tank includes a boost pump, which is located at the lower part of the onboard tank,

[0019] - a mixing chamber configured to be connected to the combustion chamber,

[0020] a first line connecting the onboard tank to the mixing chamber so as to be able to supply it with liquid cryogenic fuel, this first line being provided with at least one pressure pump and a first regulating valve, the mixing chamber itself being connected to the combustion chamber,

[0021] a second line connecting the onboard tank to the mixing chamber so as to be able to supply the mixing chamber with cryogenic fuel in a gaseous state, this second line being provided with at least one compressor and a first control valve,

[0022] a recirculation line connecting the booster pump to the upper part of the tank, this recirculation line being equipped with a second regulating valve and a first heat exchanger enabling the cryogenic fuel to be transformed from the liquid to the gaseous state,

[0023] -Pressure sensor, which detects the pressure inside the onboard tank,

[0024] a central control unit which receives the pressure data from the pressure sensor and controls the complete or partial opening or closing of the different regulating valves and the first control valve, as well as the start or stop of the pressure pump, the boosting pump and the compressor, depending on the value of the setpoint pressure in the onboard tank.

[0025] Due to these features of the present invention, the pressure inside the onboard tank is maintained at a lower value than in the prior art. The liquid / gas equilibrium is maintained at a lower pressure and therefore at a lower temperature, which increases the density of the liquid. Consequently, for the same mass of onboard cryogenic fuel, the tank size can be reduced.

[0026] Furthermore, since the pressure is kept low, it is no longer necessary to use structural reinforcements on the tank, which guarantees benefits in terms of the quality of the tank and greater freedom in the choice of the shape of the tank.

[0027] Finally, the pressure management mode makes it possible to reduce the need to heat the cryogenic fuel before using it in the combustion chamber. Therefore, it is no longer necessary to provide an additional energy source to heat the cryogenic fuel, and a simple heat exchange with the hot fluid present inside the aircraft is sufficient.

[0028] Other advantageous and non-limiting features according to the invention, taken alone or in combination:

[0029] -The regulating device includes a buffer tank and a second control valve, the buffer tank is arranged on the recirculation line and downstream of the first heat exchanger, the second control valve is arranged on the recirculation line, and the second control valve is arranged between the buffer tank and the upper part of the onboard storage tank, and a first three-way valve is arranged on the second line so that the inlet passage of the first three-way valve is connected to the downstream of the compressor, one of the outlet passages of the first three-way valve is connected to the mixing chamber, and the other of the outlet passages of the first three-way valve is connected to the buffer tank through a bypass line. The second control valve and the first three-way valve are controlled by the central control unit, the first three-way valve being capable of being arranged in a first position, a second position, or a plurality of intermediate positions, wherein in the first position, the first three-way valve connects the tank only to the mixing chamber, and in the second position, the first three-way valve connects the tank only to the buffer tank, so that the buffer tank can be filled with gaseous cryogenic fuel compressed by the compressor, and in the plurality of intermediate positions, the first three-way valve connects the tank to the mixing chamber and the buffer tank, while allowing a more or less significant flow to flow to the mixing chamber or the buffer tank, depending on the intermediate position in which the first three-way valve is located;

[0030] a second heat exchanger is arranged on the first pipeline and between the first regulating valve and the mixing chamber to vaporize the liquid cryogenic fuel before it enters the mixing chamber;

[0031] - the first regulating valve and the second regulating valve are only one second three-way valve, which is arranged on the first pipeline and downstream of the booster pump, such that an inlet passage of the second three-way valve is connected to the booster pump, one of the outlet passages of the second three-way valve is connected to the mixing chamber, and the other of the outlet passages of the second three-way valve is connected to the recirculation line upstream of the first heat exchanger, the second three-way valve being controlled by the central control unit to be arranged in a first position, a second position, or a plurality of intermediate positions, in which the second three-way valve connects the tank only to the mixing chamber, in the second position, in which the second three-way valve connects the tank only to the first heat exchanger, and in a plurality of intermediate positions, in which the second three-way valve connects the tank to both the mixing chamber and the first heat exchanger, while enabling a more or less significant flow to flow to the mixing chamber or the first heat exchanger depending on the intermediate position in which the second three-way valve is located;

[0032] - the device comprises a valve arranged at the upper part of the onboard tank, the valve being calibrated at a safety pressure which is higher than atmospheric pressure and higher than the set point pressure, and which allows the release of gaseous cryogenic fuel from the onboard tank if the pressure inside the onboard tank exceeds the safety pressure;

[0033] at least one of the first and second heat exchangers is an aircraft exchanger for a low-temperature fuel / thermal fluid selected from: air from outside the aircraft, cabin air, or exhaust gases of a gas turbine;

[0034] - the device comprises a gas discharge line, which opens to the upper part of the onboard tank and connects the onboard tank to an outlet fitting of the aircraft, the outlet fitting of the aircraft opening to the outside of the aircraft, the gas discharge line being provided with a monitoring valve, the opening and closing of which is controlled by the central control unit, the outlet fitting of the aircraft being configured to be connectable to the gas suction device via a suction line;

[0035] - the device comprises a spraying device for spraying liquid cryogenic fuel, the spraying device being arranged inside the onboard tank and in the upper part of the onboard tank, the spraying device being connected to a liquid supply line, the liquid supply line being provided with an aircraft inlet fitting, the aircraft inlet fitting leading to the outside of the aircraft, the liquid supply line being provided with a monitoring valve, the opening and closing of which is controlled by the central control unit, the aircraft inlet fitting being configured to be connectable via an inlet line to an external cryogenic fuel storage tank at an airport and a pumping device, so as to supply the liquid cryogenic fuel to the spraying device;

[0036] - The device comprises a filling line, which opens to the lower part of the onboard tank, is provided with a monitoring valve, the opening and closing of which is controlled by the central control unit, and is further provided with an inlet fitting, which opens to the outside of the aircraft and is configured to be connectable via an inlet line to an external cryogenic fuel storage tank and a pumping device at an airport, so as to supply the onboard tank with liquid cryogenic fuel.

[0037] The present invention also relates to an aircraft comprising at least one onboard storage tank for cryogenic fuel, such as natural gas, and at least one turbine equipped with a combustion chamber for operating with the cryogenic fuel in liquid and gaseous form. According to the invention, the aircraft comprises a pressure regulating device as described above.

[0038] The invention also relates to an assembly for regulating the pressure in an onboard storage tank for a cryogenic fuel in liquid or gaseous form, such as natural gas.

[0039] According to the present invention, the assembly comprises:

[0040] - aircraft and airport facilities,

[0041] an aircraft comprising said onboard tank and at least one turbine provided with a combustion chamber supplied with said cryogenic fuel and with a device for regulating the pressure as described above,

[0042] The airport facility comprises at least one external cryogenic fuel storage tank, at least one suction line provided with a gas suction device and connected to a suction fitting, the suction fitting being configured to be connectable to an outlet fitting of an aircraft, and / or at least one inlet line provided with a pumping device and connected to the external tank and the inlet fitting, the inlet fitting being configured to be connectable to an inlet fitting of an aircraft.

[0043] The invention also relates to a method for regulating the pressure in an onboard storage tank for a cryogenic fuel in liquid or gaseous form, such as natural gas, which is located in an aircraft and which includes a device for regulating the pressure as described above, and which supplies the combustion chamber of a turbine of said aircraft.

[0044] According to the present invention, the method comprises the following steps:

[0045] - detecting the pressure inside the onboard tank using the pressure sensor,

[0046] - compare this pressure to the set point pressure,

[0047] - and when the pressure in the onboard tank is lower than the set point pressure, opening the second regulating valve and possibly the second control valve of the recirculation line and starting the boost pump to convert the liquid cryogenic fuel into gaseous cryogenic fuel in the first heat exchanger and re-injecting the gaseous cryogenic fuel into the upper part of the onboard tank.

[0048] Advantageously, the method comprises the following steps:

[0049] - detecting the pressure inside the onboard tank using the pressure sensor,

[0050] - compare this pressure to the set point pressure,

[0051] - and when the pressure in the onboard tank is lower than the set point pressure, opening the second control valve to transfer the compressed gaseous cryogenic fuel contained in the buffer tank to the onboard tank until the pressure in the onboard tank is equal to the set point pressure.

[0052] Preferably, the method is performed using the above-mentioned assembly and, when the aircraft is stopped and connected to the airport facility, the method comprises the following steps:

[0053] - detecting the pressure inside the onboard tank using the pressure sensor,

[0054] - compare this pressure to the set point pressure,

[0055] - If the pressure in the onboard tank is lower than the set point pressure, the monitoring valve of the liquid supply line is opened, and the pumping device of the airport facility is opened to suck liquid cryogenic fuel from the external tank and introduce the liquid cryogenic fuel into the onboard tank, and if the pressure in the onboard tank is higher than the set point pressure, the monitoring valve of the gas discharge line is opened, and the gas suction device of the airport facility is opened to suck gaseous cryogenic fuel located in the onboard tank.

[0056] It should be noted that in practice this situation rarely occurs because when the aircraft is stopped, the aircraft's engines are shut down and the gas is not consumed. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Other features, objects and advantages of the present invention will appear from the following description, which is entirely illustrative and non-limiting and should be read in conjunction with the accompanying drawings, in which:

[0058] [ Figure 1 ] is a schematic diagram showing a first embodiment of an assembly for regulating the pressure within an onboard cryogenic fuel storage tank for supplying a combustion chamber of an aircraft turbine.

[0059] [ Figure 2 ] is a schematic diagram showing a second embodiment of the above-mentioned components.

[0060] [ Figure 3 ] is a schematic diagram showing possible locations of onboard cryogenic fuel storage tanks on the outside of the fuselage of an aircraft.

[0061] Throughout the drawings, the same elements are denoted by the same reference numerals. DETAILED DESCRIPTION

[0062] From the prior art there is known an aircraft 1 equipped with a turbine, the combustion chamber 10 of which is supplied with a cryogenic fuel, such as natural gas.

[0063] According to the invention, the aircraft 1 comprises a device 2 for regulating the pressure in an onboard storage tank 3 for said cryogenic fuel. When the liquid has evaporated after a phase change, the cryogenic fuel is partly in the liquid state (in the lower part of the tank) and partly in the gaseous state (so that the cryogenic fuel partially accumulates in the top of the tank).

[0064] An "airborne tank" is a tank that is configured to be embedded in an aircraft or fixed to the outside of an aircraft 1 (e.g., Figure 3 and at the same time meet safety standards.

[0065] The pressure regulating device 2 according to the present invention specifically comprises:

[0066] a first line 41 connecting the onboard tank 3 (in particular the tapping fitting 31 situated in its lower part) to the mixing chamber 100 so as to be able to supply it with liquid cryogenic fuel,

[0067] a second line 42 connecting the onboard tank 3 (in particular the tapping fitting 32 situated in the top of the onboard tank) to the mixing chamber 100 so as to be able to supply the mixing chamber with cryogenic fuel in the gaseous state,

[0068] A recirculation line 43 connecting the lower part of the tank 3 to its upper part, in particular to the tapping fitting 33 situated in the top of said onboard tank 3 .

[0069] Preferably, a pump 35, for example a boost pump, is immersed in the tank 3. This pump is connected to the first line 41 and enables the desired fuel flow to be introduced into this line without the pressure in this line increasing significantly.

[0070] Preferably, the first pipeline 41 is further provided with a boosting pump 412, which is arranged downstream of the boosting pump 35 and upstream of the first valve (called a "regulating" valve) relative to the flow direction of the liquid cryogenic fuel in the pipeline 41. Figure 1 In the embodiment shown in FIG, the first regulating valve is a two-way valve, which is marked as 410. Figure 2 In the embodiment shown in FIG, the first regulating valve is a three-way valve, referenced 411. A pump 412 makes it possible to increase the pressure of the liquid cryogenic fuel circulating in the first line 41.

[0071] Finally, for reasons of consistency with the terminology used in the claims, the three-way valve 411 will be referred to hereinafter as the "second three-way valve."

[0072] The recirculation line 43 is equipped with an aircraft heat exchanger 430 for the first liquid cryogenic fuel / hot fluid. This heat exchanger 430 enables the liquid cryogenic fuel to be changed in state to become gaseous in order to be reintroduced into the top of the tank 3.

[0073] Furthermore, advantageously, an on / off valve 431 is arranged on the recirculation line 43 , downstream of the heat exchanger 430 , in order to allow or not allow the passage of gas towards the tank 3 .

[0074] Line 43 can:

[0075] - is directly connected to the lower part of the tank 3 through the tap fitting 34 and this line is provided with a second regulating valve 432, while the first line 41 is provided with a first regulating valve 410 (see Figure 1 ),

[0076] - or connected to the second three-way valve 411 located on the first pipeline 41 (see Figure 2 Therefore, the second three-way valve 411 replaces the first regulating valve and the second regulating valve.

[0077] Optionally, an aircraft heat exchanger 413 for a second liquid cryogenic fuel / thermal fluid is arranged between valve 410 or 411 and mixing chamber 100. This exchanger 413 enables vaporization of the liquid fuel before it enters mixing chamber 100, which thus contains only fuel in gaseous state.

[0078] The three-way valve 411 comprises an inlet connected to the pressure pump 412 and two outlets respectively connected to the second exchanger 413 (and therefore to the mixing chamber 100 ) and to the recirculation line 43 upstream of the exchanger 430 .

[0079] The second three-way valve 411 can have a first position, a second position or multiple intermediate positions. In the first position, the second three-way valve connects the tank 3 only to the mixing chamber 100, and in the second position, the second three-way valve connects the tank 3 only to the first heat exchanger 430. In multiple intermediate positions, the second three-way valve connects the tank 3 to the mixing chamber 100 and the first heat exchanger 430, while allowing a more or less significant flow to flow to the mixing chamber or the first heat exchanger depending on the intermediate position in which the second three-way valve is located.

[0080] Preferably, the second pipeline 42 is provided with a first control valve 420 (e.g., a two-way valve) and a compressor 421. Relative to the flow direction of the gaseous cryogenic fuel in the second pipeline 42, the first control valve is arranged downstream of the tank, and the compressor is arranged downstream of the valve 420.

[0081] Among the different hot fluids of the aircraft that can be used for the heat exchanger 413 or 430 , mention may be made, for example, of air from outside the aircraft (the temperature of the air from outside the aircraft being higher than that of the cryogenic fuel), air from the cabin or exhaust gases from a gas turbine.

[0082] The mixing chamber 100 receives a mixture of cryogenic fuel in both liquid and gaseous states from the two lines 41 and 42 and is connected to the combustion chamber 10 via a line 101. An injector (not shown in the figures) arranged at the inlet of the combustion chamber 10 makes it possible to introduce the gaseous cryogenic fuel into the combustion chamber 10.

[0083] At least one pressure sensor 5 is arranged in the tank 3 to detect the pressure in the tank. The sensor is arranged in the upper part of the tank 3, above the level of the fuel in the liquid state.

[0084] Advantageously, the onboard tank 3 further includes a safety valve 6 disposed at the upper portion of the onboard tank. The valve is calibrated at a safety pressure that is higher than atmospheric pressure and higher than a set point pressure. The safety valve has the function of releasing gaseous cryogenic fuel from the onboard tank 3 if the pressure within the onboard tank 3 exceeds the safety pressure.

[0085] According to the present invention Figure 1 In a first simplified alternative embodiment shown in , the recirculation line 43 is connected directly to the tap fitting 33 downstream of the on / off valve 431 .

[0086] According to the present invention Figure 2 In the second alternative embodiment shown in FIG, the recirculation line 43 is connected to the tapping fitting 33 via a gas buffer tank 433 (or "capacity tank"), which is located downstream of the on / off valve 431. This buffer tank 432 contains gas at a higher pressure than the pressure in the onboard tank 3. The buffer tank is used to keep this tank 3 under pressure.

[0087] In this case, a second control valve 434 is arranged on the recirculation line 43, downstream of the buffer tank 433. Finally, a three-way valve 422 (hereinafter referred to as the first three-way valve) is arranged on the second line 42, downstream of the compressor 421. The three-way valve comprises an inlet passage connected to the compressor 421, and two outlet passages, respectively connected to the mixing chamber 100 and to the buffer tank 433 via the bypass line 44. The valve 422 can have a first position, in which the valve connects the tank 3 only to the mixing chamber 100, a second position, in which the valve connects the tank 3 only to the buffer tank 433, or a plurality of intermediate positions, in which the valve connects the tank 3 to both the mixing chamber 100 and the buffer tank 433, while enabling a more or less significant flow to the mixing chamber or the buffer tank, depending on the intermediate position in which the valve is located.

[0088] Finally, although not shown in the drawings, it should be noted that it is possible to have Figure 2 The buffer tank 433 in FIG. 1 is shown, but the recirculation line 43 is the same as in FIG. Figure 1 The connector shown in FIG. 4 is connected to valves 432 and 410 .

[0089] At least one central unit 7 (e.g., a computer or processor) receives information, in particular from the pressure sensor 5, and controls the operation of valves 410, 431, 432, 434, and 420, the operation of three-way valves 411 and 422, the on / off operation of the booster pump 35 and the pressure pump 412, and the on / off operation of the compressor 421 based on the information (as described below).

[0090] To this end, the computer comprises a memory having stored therein a computer program comprising code instructions enabling the machine to perform the method steps.

[0091] The buffer tank 433 can be supplied in two ways.

[0092] When the second three-way valve 411 is in the first position (or when the first regulating valve 410 is open and the second regulating valve 432 is closed), for example, when the aircraft takes off and when the mixing chamber 100 is supplied with liquid fuel, the first three-way valve 422 is arranged in the second position, and the buffer tank 433 is supplied with gaseous cryogenic fuel, which comes from the upper part of the tank 3, is then compressed by the compressor 421 and introduced through the bypass line 44. At the same time, the second control valve 434 is closed.

[0093] Conversely, when the flow rate of gaseous (i.e., vaporized) fuel is sufficient to supply the mixing chamber 100, the first three-way valve 422 is placed in the first position. However, the first three-way valve can also be placed in an intermediate position, so that the buffer tank 433 is supplied with gaseous fuel discharged from the compressor 421 and the valve 434 is closed.

[0094] The cache tank 433 is filled in particular when the internal pressure of the cache tank becomes lower than a predetermined threshold pressure, which is itself higher than the working pressure of the tank 3 .

[0095] The buffer tank 433 is sized to maintain the pressure in the tank 3, the time during which the recirculation line 43 is supplied with liquid fuel, and the time during which the carburetor 430 begins to produce gas. Thus, the response time for regulating the pressure in the tank 3 is shortened compared to the first alternative embodiment without the buffer tank 433.

[0096] The regulating device 2 operates as follows:

[0097] As soon as the pressure sensor 5 returns information to the central unit 7 that the pressure in the onboard tank 3 is equal to the set point pressure or is within the range of the set point value, the central unit 7 closes the valves 431, 432 and / or controls the three-way valves 411 and 422 (according to an alternative embodiment) so that neither the recirculation line 43 nor the buffer tank 433 (if present) is connected to the lines 41 and 42. In addition, the central unit controls the pumps 35 and 412 as well as the valve 420 and the compressor 421 so that, depending on the flight phase of the aircraft, the mixing chamber 100 is supplied with liquid cryogenic fuel and gaseous cryogenic fuel according to the ratio obtained by the needs of the aircraft 1.

[0098] If the pressure in the onboard tank 3 detected by the pressure sensor 5 is lower than the set point pressure (or lower than the lower limit of the range of set point values), and as long as the pressure in the onboard tank remains this way, the second regulating valve 432 is opened or the second three-way valve 411 is arranged in the second position, the second control valve 434 (if present) is opened, and the liquid cryogenic fuel passes through the heat exchanger 430, changes phase and returns to the gaseous state and into the upper part of the tank 3. This gas entry causes the pressure in the tank 3 to increase. If the buffer tank 433 is present, it functions as previously described.

[0099] On the contrary, if the pressure detected by the pressure sensor 5 is greater than the set point pressure or greater than the upper limit of the set point value range, the flow rate of the gas flowing out of the second pipeline 42 is increased by accelerating the compressor 421 (so that the valve 420 is opened), and the flow rate of the liquid circulating in the first pipeline 41 is reduced by controlling the valve 410 or 411, so that the flow rate of the (liquid and gaseous) low-temperature fuel reaching the engine always corresponds to the engine demand.

[0100] Finally, if the pressure in the tank 3 becomes higher than the safety pressure, the valve 6 opens and releases gas out of the tank 3 to return the pressure in the tank to below the safety pressure value.

[0101] Advantageously, the pressure regulating device 2 according to the invention can be completed by an additional facility making it possible to regulate the pressure in the onboard tank 3 during phases when the aircraft 1 is parked on the ground, for example at night.

[0102] To this end, the device 2 comprises a line 81 for discharging gas, which opens into the upper part of the tank 3 at a tapping fitting 810. This line enables the tank 3 to be connected to an outlet fitting 11 of the aircraft leading to the outside. This discharge line 81 is provided with a monitoring valve 82, the opening and closing of which is controlled by the central control unit 7.

[0103] Furthermore, the outlet fitting 11 is configured to be connectable via a suction line 91 to a gas suction device 92 that enables gas to be extracted and conveyed to a reliquefaction device installed, for example, in an airport.

[0104] The suction line 91 may be connected to the fitting 11 , for example, via a fitting 96 .

[0105] Advantageously, pressure regulating device 2 also includes a device 83 for spraying cryogenic fuel in liquid form, which is arranged inside onboard tank 3, in its upper part. This spraying device 83 is connected to a liquid supply line 84 provided with an inlet fitting 12 leading to the outside of aircraft 1. Line 84 is provided with a monitoring valve 85, the opening and closing of which is controlled by central control unit 7.

[0106] Preferably, the spraying device 83 is used when the tank 3 is hot. Thus, the gas accumulated in the upper part of the tank is also hot and promotes the vaporization of the liquid sprayed by the device 83. This spraying device also makes it possible to standardize the filling of the liquid and avoid the creation of cold spots in the structure of the tank 3 that could make it fragile.

[0107] The inlet fitting 12 is configured to be connectable to an external cryogenic fuel storage tank 93 at the airport via an inlet line 94 in order to supply the device 83 with fuel in a liquid state.

[0108] The inlet line 94 is provided with a pumping device 95 and a fitting 97 configured to mate with the inlet fitting 12 .

[0109] Finally, the onboard tank 3 may also be provided with a liquid filling line 86 opening into its lower part, this line 86 being connectable to the line 84 downstream of the valve 85 or to an inlet fitting of the aircraft not shown in the figures.

[0110] Thanks to this additional facility, when the aircraft 1 is stopped, the suction line 91 and the introduction line 94 are connected to the aircraft 1, and if the pressure sensor 5 detects that the pressure in the tank 3 is below the setpoint pressure (or below the lower limit of the range of setpoint values), and as long as the pressure in the tank remains this way, the central control unit 7 keeps valves 420, 432, 410 and 411 closed (if the engine is not started and the aircraft is connected to the airport, these valves are always closed, with the possible exception of valve 432, which can be used to increase the pressure). In addition, the unit 7 controls the opening of the monitoring valve 85 and the activation of the pumping device 95 to suction the cryogenic fuel in the external tank 93 and introduce it into the onboard tank 3.

[0111] Furthermore, if the pressure in the tank 3 detected by the sensor 5 exceeds the set point pressure or the upper limit of the range of set point values, the central control unit 7 opens the monitoring valve 82 and turns on the gas suction device 92 so that the gaseous cryogenic fuel is discharged to the airport facilities.

[0112] Furthermore, as described before, if the pressure in the tank 3 becomes higher than the safety pressure, the valve 6 opens.

[0113] Finally, when the liquid fuel level drops below a predetermined threshold (measured by a sensor), fuel is added to the tank.

[0114] The spraying device 83 is used when the tank is "hot", that is, at ambient temperature and when there is no cryogenic liquid in the tank 3. This spraying device 83 makes it possible to spray the droplets without causing thermal shock to the metal of the tank 3, which would occur if the flow were directly dumped using the line 86. If the onboard tank 3 is already "cold", the line 86 with a higher flow rate is used.

Claims

1. A pressure regulating device (2) for regulating the pressure in an onboard storage tank for cryogenic fuel, part of which is in liquid form and another part of which is in gaseous form, intended to supply a combustion chamber (10) of a turbine of an aircraft (1), characterized in that The pressure regulating device comprises: - an onboard tank (3), the onboard tank being used to store cryogenic fuel and supply cryogenic fuel to the combustion chamber (10), the tank (3) comprising a boost pump (35), the boost pump being located at the lower part of the onboard tank (3), - a mixing chamber (100), the mixing chamber being configured to be connected to the combustion chamber, - a first pipeline (41) connecting the onboard tank (3) to the mixing chamber (100) so as to be able to supply the mixing chamber with liquid cryogenic fuel, the first pipeline (41) being provided with at least one pressure pump (412) and a first regulating valve (410, 411), the mixing chamber (100) itself being connected to the combustion chamber (10), - a second line (42) connecting the onboard tank (3) to the mixing chamber (100) so as to be able to supply the mixing chamber with cryogenic fuel in a gaseous state, the second line (42) being provided with at least one compressor (421) and a first control valve (420), - a recirculation line (43) connecting the booster pump (35) to the upper part of the tank (3), the recirculation line (43) being equipped with a second regulating valve (432, 411) and a first heat exchanger (430) enabling the cryogenic fuel to be transformed from a liquid state to a gaseous state, - a pressure sensor (5) which detects the pressure inside the onboard tank (3), - a central control unit (7) which receives pressure data from the pressure sensor (5) and controls the complete or partial opening or closing of the different regulating valves (410, 411, 432) and the first control valve (420), as well as the start or stop of the pressure pump (412), the boost pump (35) and the compressor (421) according to the value of the set point pressure in the onboard tank (3).

2. The pressure regulating device according to claim 1, characterized in that: The pressure regulating device includes a buffer tank (433) and a second control valve (434), the buffer tank is arranged on the recirculation line (43) and downstream of the first heat exchanger (430), the second control valve is arranged on the recirculation line (43), and the second control valve is arranged between the buffer tank (433) and the upper part of the onboard storage tank (3), a first three-way valve (422) is arranged on the second line (42), so that the inlet passage of the first three-way valve is connected to the downstream of the compressor (421), one of the outlet passages of the first three-way valve is connected to the mixing chamber (100), and the other outlet passage of the first three-way valve is connected to the buffer tank (433) through a bypass line (44), and the second The control valve (434) and the first three-way valve (422) are controlled by the central control unit (7), and the first three-way valve (422) can be arranged in a first position, a second position or a plurality of intermediate positions, in which, in the first position, the first three-way valve connects the tank (3) only to the mixing chamber (100), and in the second position, the first three-way valve connects the tank (3) only to the cache tank (433) so that the cache tank can be filled with gaseous cryogenic fuel compressed by the compressor (421), and in the plurality of intermediate positions, the first three-way valve connects the tank (3) to the mixing chamber (100) and the cache tank (433), while allowing a more or less significant flow to flow to the mixing chamber or the cache tank depending on the intermediate position in which the first three-way valve is located.

3. The pressure regulating device according to claim 1, characterized in that A second heat exchanger (413) is arranged on the first pipeline (41) and between the first regulating valve (410, 411) and the mixing chamber (100) to vaporize the liquid cryogenic fuel before it enters the mixing chamber (100).

4. The pressure regulating device according to claim 1, characterized in that The first regulating valve and the second regulating valve are only a second three-way valve (411), which is arranged on the first pipeline (41) and downstream of the boosting pump (412), so that the inlet passage of the second three-way valve is connected to the boosting pump (412), one of the outlet passages of the second three-way valve is connected to the mixing chamber (100), and the other outlet passage of the second three-way valve is connected to the recirculation pipeline (43) upstream of the first heat exchanger (430), and the second three-way valve (411) is controlled by the central The unit (7) is controlled to be arranged in a first position, a second position or a plurality of intermediate positions, in which the second three-way valve connects the tank (3) only to the mixing chamber (100), in which the second three-way valve connects the tank (3) only to the first heat exchanger (430), and in which the second three-way valve connects the tank (3) to the mixing chamber (100) and the first heat exchanger (430), while allowing a more or less significant flow to flow to the mixing chamber or the first heat exchanger depending on the intermediate position in which the second three-way valve is located.

5. The pressure regulating device according to claim 1, characterized in that: The pressure regulating device comprises a valve (6) arranged at the upper part of the onboard tank (3), the valve being calibrated at a safety pressure which is higher than atmospheric pressure and higher than the set point pressure, and the valve enabling the release of gaseous cryogenic fuel from the onboard tank (3) if the pressure in the onboard tank exceeds the safety pressure.

6. The pressure regulating device according to claim 3, characterized in that: At least one of the first heat exchanger (430) and the second heat exchanger (413) is an aircraft exchanger for a low-temperature fuel / hot fluid, the hot fluid being selected from: air from outside the aircraft, cabin air, or exhaust gas from a gas turbine.

7. The pressure regulating device according to claim 1, characterized in that: The pressure regulating device comprises a gas discharge line (81), which leads to the upper part of the onboard tank (3) and connects the onboard tank to the outlet fitting (11) of the aircraft, the outlet fitting of the aircraft leading to the outside of the aircraft (1), the gas discharge line (81) is provided with a monitoring valve (82), the opening and closing of the monitoring valve is controlled by the central control unit (7), and the outlet fitting (11) of the aircraft is configured to be connectable to a gas suction device (92) via a suction line (91).

8. The pressure regulating device according to claim 1, characterized in that: The pressure regulating device comprises a spraying device (83) for spraying liquid cryogenic fuel, the spraying device being arranged in the onboard tank (3) and connected to a liquid supply line (84) in the upper part of the onboard tank, the liquid supply line being provided with an inlet fitting (12) of the aircraft, the inlet fitting of the aircraft leading to the outside of the aircraft (1), the liquid supply line (84) being provided with a monitoring valve (85), the opening and closing of which is controlled by the central control unit (7), the inlet fitting (12) of the aircraft being configured to be connected to an external cryogenic fuel storage tank (93) and a pumping device (95) of an airport via an inlet line (94) to supply liquid cryogenic fuel to the spraying device (83).

9. The pressure regulating device according to claim 1, characterized in that: The pressure regulating device comprises a filling line (86), which leads to the lower part of the onboard tank (3), and is provided with a monitoring valve (85), the opening and closing of which is controlled by the central control unit (7). The filling line (86) is also provided with an inlet fitting (12), which leads to the outside of the aircraft (1), and is configured to be connected to an external cryogenic fuel storage tank (93) and a pumping device (95) at an airport via an introduction line (94) to supply liquid cryogenic fuel to the onboard tank (3).

10. The pressure regulating device according to claim 1, characterized in that: The low-temperature fuel is natural gas.

11. An aircraft (1) comprising at least one onboard storage tank (3) for cryogenic fuel and at least one turbine, said at least one turbine being provided with a combustion chamber (10) operating with said cryogenic fuel in liquid and gaseous state, characterized in that The aircraft comprises a pressure regulating device (2) according to any one of claims 1 to 10.

12. The aircraft (1) according to claim 11, characterized in that The low-temperature fuel is natural gas.

13. An assembly for regulating the pressure in an onboard storage tank (3) for liquid or gaseous cryogenic fuel, characterized in that The components include: - aircraft (1) and airport facilities (9), The aircraft (1) comprises the onboard tank (3) and at least one turbine provided with a combustion chamber (10) supplied with the cryogenic fuel and a pressure regulating device according to any one of claims 1 to 6, The pressure regulating device comprises a gas discharge line (81), which leads to the upper part of the onboard tank (3) and connects the onboard tank to the outlet fitting (11) of the aircraft, the outlet fitting of the aircraft leading to the outside of the aircraft (1), the gas discharge line (81) is provided with a monitoring valve (82), the opening and closing of the monitoring valve are controlled by the central control unit (7), and the outlet fitting (11) of the aircraft is configured to be connectable to a gas suction device (92) via a suction line (91). The pressure regulating device comprises a spraying device (83) for spraying liquid cryogenic fuel, the spraying device being arranged in the onboard tank (3) and connected to a liquid supply line (84) in the upper part of the onboard tank, the liquid supply line being provided with an inlet fitting (12) of the aircraft, the inlet fitting of the aircraft leading to the outside of the aircraft (1), the liquid supply line (84) being provided with a monitoring valve (85), the opening and closing of which is controlled by the central control unit (7), the inlet fitting (12) of the aircraft being configured to be connected to an external cryogenic fuel storage tank (93) and a pumping device (95) at an airport via an introduction line (94) to supply the liquid cryogenic fuel to the spraying device (83), The pressure regulating device comprises a filling line (86) which leads to the lower part of the onboard tank (3), the filling line (86) being provided with a monitoring valve (85), the opening and closing of which is controlled by the central control unit (7), the filling line (86) being further provided with an inlet fitting (12) which leads to the outside of the aircraft (1), the inlet fitting (12) being configured to be connected to an external cryogenic fuel storage tank (93) and a pumping device (95) at an airport via an introduction line (94) to supply liquid cryogenic fuel to the onboard tank (3), The airport facility (9) comprises at least one external cryogenic fuel storage tank (93), at least one suction line (91) and / or at least one inlet line (94), wherein the suction line (91) is provided with a gas suction device (92) and is connected to a suction fitting (96), wherein the suction fitting is configured to be connectable to an outlet fitting (11) of the aircraft, and the inlet line (94) is provided with a pumping device (95) and is connected to the external cryogenic fuel storage tank (93) and an inlet fitting (97), wherein the inlet fitting is configured to be connectable to an inlet fitting (12) of the aircraft.

14. The assembly according to claim 13, wherein The low-temperature fuel is natural gas.

15. A pressure regulating method for regulating the pressure in an onboard storage tank (3) for liquid or gaseous cryogenic fuel, the onboard tank (3) being located in an aircraft (1) and comprising a pressure regulating device according to any one of claims 1 and 3 to 10, the cryogenic fuel supplying the combustion chamber (10) of a turbine of the aircraft, characterized in that The pressure regulation method comprises the following steps: - detecting the pressure in the onboard tank (3) using the pressure sensor (5), - compare this pressure to the set point pressure, - and when the pressure in the onboard tank (3) is lower than the set point pressure, opening the second regulating valve (432, 411) of the recirculation line (43) and, if a second control valve (434) of the recirculation line (43) is present, opening the second control valve (434), and starting the boost pump (35) to convert the liquid cryogenic fuel into gaseous cryogenic fuel in the first heat exchanger (430) and re-injecting the gaseous cryogenic fuel into the upper part of the onboard tank (3).

16. The pressure regulating method according to claim 15, wherein the aircraft (1) comprises a pressure regulating device according to claim 2, characterized in that: The pressure regulation method comprises the following steps: - detecting the pressure in the onboard tank (3) using the pressure sensor (5), - compare this pressure to the set point pressure, - and when the pressure in the onboard tank (3) is lower than the set point pressure, opening the second control valve (434) to transfer the compressed gaseous cryogenic fuel contained in the buffer tank (433) to the onboard tank (3) until the pressure in the onboard tank (3) is equal to the set point pressure.

17. The pressure regulating method according to claim 15 or 16, characterized in that: The pressure regulation method is performed with the assembly according to claim 13 and comprises the following steps when the aircraft (1) is stopped and connected to the airport facility (9): - detecting the pressure in the onboard tank (3) using the pressure sensor (5), - compare this pressure to the set point pressure, - If the pressure in the onboard tank (3) is lower than the set point pressure, the monitoring valve (85) of the liquid supply line (84) is opened, and the pumping device (95) of the airport facility (9) is opened to suck liquid cryogenic fuel from the external cryogenic fuel storage tank (93) and introduce the liquid cryogenic fuel into the onboard tank (3), and if the pressure in the onboard tank (3) is higher than the set point pressure, the monitoring valve (82) of the gas discharge line (81) is opened, and the gas suction device (92) of the airport facility (9) is opened to suck gaseous cryogenic fuel in the onboard tank (3).

18. The pressure regulating method according to claim 15, characterized in that: The low-temperature fuel is natural gas.

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