Fuel supply system and method for aircraft turbomachinery

Abstract

A fuel supply system (1) configured to supply an aircraft turbomachine (M), the fuel being a first hydrogenated fuel (Q1), the fuel supply system (1) comprising: a storage tank (2) configured to store the first hydrogenated fuel (Q1), in liquid form, at a storage pressure (P1) and a storage temperature (T1) above a predetermined cryotemperature threshold (Tcr); a fuel circuit (3), connected inlet to the storage tank (2) and configured to be connected outlet to the turbomachine (M); a catalyst device (4), configured to separate the first hydrogenated fuel (Q1) into at least a second hydrogenated fuel (Q2) and an auxiliary component (A);a compressor (5) configured to raise the pressure of at least the second hydrogenated fuel (Q2) to an injection pressure (P2) higher than the storage pressure (P1), so as to allow the injection of at least the second fuel (Q2) into the turbomachine (M). Abstract figure: Figure 2;

Description

Title of the invention: Fuel supply system and method for an aircraft turbomachine Technical field

[0001] The present invention relates to the field of aircraft comprising turbo-machines powered by fuel stored in the liquid state.

[0002] It is known to supply an aircraft turbomachine with fuel, in particular hydrogen, stored in liquid form to limit the size of the aircraft tanks.

[0003] In the prior art, with reference to [Fig. 1], a system 100 for supplying fuel Q, in particular hydrogen supply, to an aircraft comprises a fuel circuit CQ connected at the inlet to a cryogenic tank R and at the outlet to a combustion chamber of a turbomachine M. A flow of fuel Q circulates from upstream to downstream in the fuel circuit CQ.

[0004] To be liquid, the fuel Q is stored in the cryogenic tank R at a temperature of the order of -253 to -251°C (20 to 22 Kelvins). Such a temperature is lower than the known cryotemperature threshold of the order of -150°C (120K).

[0005] In order to be injected into the combustion chamber of the turbomachine M, the fuel Q must be conditioned, i.e. pressurized and heated, in order to allow optimal combustion. Conditioning is, for example, necessary to reduce the risk of icing / solidification of the water vapor contained in the air circulating in the turbomachine M, in particular, at the fuel injectors of the turbomachine M.

[0006] Also, as shown in [Fig.l], the supply system 100 known from the prior art comprises a conditioning system SC mounted on the fuel circuit CQ between the cryogenic tank R and the turbomachine M. Such a conditioning system SC comprises in a known manner a mechanical pump P for circulating the fuel flow Q in the fuel circuit CQ and one or more heat exchanger(s) EC for providing calories to the fuel flow Q in order to heat it so that it can be injected into the turbomachine M.

[0007] However, such a SC conditioning system has a significant mass and bulk, which can be a disadvantage in an aircraft. In addition, the quantity of fuel carried in the cryogenic tanks remains limited and has a significant mass.

[0008] To reduce the size and mass of fuel on board a vehicle (or increase its quantity), it is known to store the fuel in the form of ammonia (NH3), corresponding to a nitrogen derivative (N2) of hydrogen (H2). Ammonia is in a liquid state at room temperature and under a pressure higher than atmospheric pressure, or under atmospheric pressure and at a low non-cryogenic temperature, which facilitates its storage and its transport from the tank to the combustion chamber of a turbomachine. In addition, for an equivalent volume, the mass of hydrogen on board is greater in the form of ammonia than in the form of liquid hydrogen. For example, ammonia NH3 is commonly used in the space sector for the propulsion of space shuttles. However, the combustion of such a fuel requires very significant energy, which cannot be provided by an aircraft turbomachine without significant modifications.

[0009] Incidentally, a fuel cell is known in which a fuel in the form of hydrogenated polysilanes (corresponding to a hydrogen-based mixture) is fed to a catalyst to separate the hydrogen from the other components. The hydrogen is then brought into contact with a membrane to react with oxygen in the fuel cell and form an electrochemical reaction. However, in such a fuel cell, it is necessary for all of the fuel to be dissociated to ensure that only hydrogen is fed to the membrane and thus avoid any risk of the undissociated hydrogenated polysilane damaging said membrane. Also, it is necessary to use a high-performance catalyst to ensure that all of the fuel components are properly separated.Such a very complex catalyst cannot be integrated into an aircraft, since it would be too bulky to separate the volume of fuel necessary for the aircraft's propulsion.

[0010] The invention thus aims to eliminate at least some of these drawbacks by proposing a fuel supply system for an aircraft which is simple and compact and which makes it possible to store a source of liquid fuel while limiting the mass of the fuel tank. PRESENTATION OF THE INVENTION

[0011] The invention relates to an aircraft fuel supply system, the supply system being configured to supply an aircraft turbomachine, the fuel being a first hydrogenated fuel, the supply system comprising • at least one storage tank configured to store the first hydrogenated fuel, in the liquid state, at a storage pressure and at a storage temperature above a predetermined cryotemperature threshold, • a fuel circuit, connected at the inlet to the storage tank and configured to be connected at the output to the turbomachine, • a catalyst device, mounted on the fuel circuit, configured to separate the first hydrogenated fuel into at least a second hydrogenated fuel and an auxiliary component, • a compressor, mounted on the fuel circuit between the catalyst device and the turbomachine, the compressor being configured to raise the pressure of at least the second hydrogenated fuel to an injection pressure higher than the storage pressure, so as to allow the injection of at least the second fuel into the turbomachine.

[0012] The supply system according to the invention makes it possible to store the first hydrogenated fuel in a non-cryogenic storage tank, which is simpler than cryogenic tanks. In addition, the supply system advantageously does away with a conditioning system, since it is not necessary to heat the fuel significantly, which allows for a lighter and less bulky supply system.

[0013] In addition, the fuel circuit comprises simpler and less bulky pipes since they do not need to withstand cryogenic temperatures and therefore do not need to be reinforced in any particular way.

[0014] Preferably, the predetermined cryotemperature threshold is of the order of -150°C (120K).

[0015] In one embodiment, the catalyst device is configured to separate the first hydrogenated fuel into at least one second hydrogenated fuel, an auxiliary component and at least one residue of the first hydrogenated fuel, the compressor being configured to raise the pressure of the second hydrogenated fuel and the residue of the first hydrogenated fuel to the injection pressure to allow the injection of the second fuel and the residue of the first hydrogenated fuel into the turbomachine.

[0016] The fuel system thus makes it possible to dispense with the use of a high-performance catalyst, since the second hydrogenated fuel and a residue of the first fuel can enter and be burned together in the combustion chamber. The catalyst device is thus simple, compact and inexpensive.

[0017] In a first embodiment, the auxiliary component is dispersed.

[0018] In a second embodiment, the auxiliary component is recovered and reused, for example by reassembling it with residues of the second fuel to reform the first fuel.

[0019] In an alternative embodiment, the compressor is configured to raise the pressure of the second hydrogenated fuel, the residue of the first hydrogenated fuel and the auxiliary component to the injection pressure to enable injection of the second fuel, the residue of the first hydrogenated fuel and the auxiliary component in the turbomachine. Thus, it is not necessary to recover the auxiliary component, since it can be introduced and burned in the combustion chamber of the turbomachine without risk of damaging it. The catalyst device can thus be simplified.

[0020] Preferably, the storage temperature is between -40 and 20°C (233 and 293 K).

[0021] Preferably, the storage pressure is between 1 and 10 bar (1000 and 10000 hPa).

[0022] In a first embodiment, the storage temperature is of the order of 20°C, corresponding to ambient temperature and the storage pressure is of the order of 10 bar (10000 hPa), making it possible to store the first fuel in liquid form without having to resort to thermal management in the fuel circuit.

[0023] In a second embodiment, the storage temperature is of the order of -35°C and the storage pressure is of the order of 1 bar (1000 hPa), corresponding to atmospheric pressure, making it possible to avoid the use of high-pressure pipe connections for the refueling phases, for example.

[0024] In a preferred embodiment, the first hydrogenated fuel is a hydrogen-carrying organic liquid, which has the advantage of being a chemical component whose catalysis conditions are compatible with an aeronautical environment.

[0025] Preferably, the first hydrogenated fuel is chosen from: ammonia (NH3), ethanol (CH3OH), methanol (C2H5OH) and methylcyclohexane (CH3C6H11). Such components are available in large quantities and their use is known.

[0026] Preferably, the second hydrogenated fuel is dihydrogen (H2).

[0027] In one embodiment, the auxiliary component is nitrogen (N2) or carbon dioxide (CO2).

[0028] The invention also relates to an aircraft comprising a turbomachine and a power supply system as described previously for powering the turbomachine.

[0029] Finally, the invention relates to a method for supplying an aircraft turbomachine by means of a supply system as described previously, the first fuel being initially stored in the first storage tank at the storage pressure and at the storage temperature above the predetermined cryotemperature threshold, the method comprising the steps of: • transport the first fuel from the storage tank to the catalyst device, • separating, in the catalyst device, the first fuel into at least a second hydrogenated fuel and an auxiliary component, • route at least the second hydrogenated fuel to the compressor, and compressing at least the second hydrogenated fuel in the compressor to the injection pressure, so as to allow the injection of at least the second fuel into the turbomachine.

[0030] Alternatively, the invention also relates to a method for supplying an aircraft turbomachine by means of a supply system as described previously, the first fuel being initially stored in the first storage tank at the storage pressure and at the storage temperature above the predetermined cryotemperature threshold, the method comprising the steps of: convey the first fuel from the storage tank to the catalyst device, separating, in the catalyst device, the first fuel into at least a second hydrogenated fuel, an auxiliary component and a residue of the first hydrogenated fuel, conveying at least the second hydrogenated fuel and the residue of the first hydrogenated fuel to the compressor, and compressing the second hydrogenated fuel and the residue of the first hydrogenated fuel in the compressor to the injection pressure, so as to allow the injection of the second fuel and the residue of the first hydrogenated fuel into the turbomachine. PRESENTATION OF FIGURES

[0031] The invention will be better understood on reading the description which follows, given by way of example, and referring to the following figures, given by way of non-limiting examples, in which identical references are given to similar objects.

[0032] [Fig.l] is a schematic representation of a power supply system according to the prior art.

[0033] [Fig.2] is a schematic representation of a power supply system according to a first embodiment of the invention.

[0034] [Fig.3] is a schematic representation of a power supply system according to a second embodiment of the invention.

[0035] It should be noted that the figures set out the invention in detail to illustrate implements the invention, said figures being able of course to serve to better define the invention where appropriate. DETAILED DESCRIPTION OF THE INVENTION

[0036] With reference to [Fig. 2], there is shown a fuel supply system 1 configured to be mounted in an aircraft and to supply a turbomachine M of the aircraft. The turbomachine M is configured to provide propulsion for the aircraft, in particular, by driving at least one propulsion organ (not shown in [Fig.2]).

[0037] The supply system 1 according to the invention comprises a fuel storage tank 2, a fuel circuit 3, connected at the inlet to the storage tank 2 and at the outlet to the turbomachine M, a catalyst device 4 and a compressor 5, mounted on the fuel circuit 3.

[0038] In a preferred embodiment, the storage tank 2 comprises a first hydrogenated fuel Q1 in the liquid state. The first hydrogenated fuel Q1 is initially in the storage tank 2 at a storage pressure PI and at a storage temperature T1 above a predetermined cryotemperature threshold Ter. By definition, a cryotemperature is a very low temperature, below -150°C (120K). In other words, the cryotemperature threshold Ter is of the order of -150°C and the storage temperature T1 is strictly above -150°C. Preferably, the storage temperature T1 is between -40 and 20°C (233 and 293 K).

[0039] In other words, the storage tank 2 of the supply system 1 according to the invention is a non-cryogenic tank, unlike the tanks of the systems of the prior art in which fuels are stored in the liquid state, such as liquid hydrogen (commonly designated by the acronym LH2) for example.

[0040] Preferably, the storage pressure PI is between 1 and 10 bar (1000 and 10000 hPa).

[0041] In a first embodiment, the storage is said to be “under pressure”. In this embodiment, the storage temperature T1 is of the order of 20°C, corresponding to ambient temperature, and the storage pressure PI is of the order of 10 bar (10000 hPa), to put the fuel Q1 under pressure in the storage tank 2.

[0042] In a second embodiment, the storage is said to be “at low temperature”. In this embodiment, the storage temperature T1 is of the order of -35°C and the storage pressure PI is of the order of 1 bar (1000 hPa), corresponding to atmospheric pressure.

[0043] Preferably, the first hydrogenated fuel Q1 is an organic hydrogen-carrying liquid known by the acronym LOHC, meaning “Liquid organic hydrogen carriers” in English, the catalysis conditions of which are compatible with an aeronautical environment. Such an organic hydrogen-carrying liquid advantageously comprises a mass of gaseous dihydrogen greater than the mass of dihydrogen contained in liquid hydrogen for an equivalent volume. More preferably, the first hydrogenated fuel Q1 is chosen from: ammonia NH3, ethanol CH3OH, methanol C2H5OH and methyl cyclohexane. CH3C6H11. Such hydrogenated fuels are known, which facilitates their use in the aviation industry.

[0044] According to the invention, with reference to [Fig.2], the catalyst device 4 is mounted on the fuel circuit 3 and is configured to separate the first hydrogenated fuel Q1 into a second hydrogenated fuel Q2 and an auxiliary component A.

[0045] Such a catalyst device 4 is for example a reformer, in which a chemical component is heated to a high temperature of the order of 400° to 600°C and brought into contact with a catalyst (for example Nickel (Ni)) to generate a chemical reaction and separate the species which form the chemical component. The first fuel Q1 is configured to be in the liquid state upon entering the catalyst device 4. The second hydrogenated fuel Q2 and the auxiliary component A are then configured to be in the gaseous state upon leaving the catalyst device 4. Such a reformer is known to those skilled in the art and its operation will not be described in more detail in this document. An example is presented in which the catalyst is Nickel (Ni), however it goes without saying that the catalyst may be different, for example Calcium imide (CaNH) which would make it possible to lower the reaction temperature to 100°C.

[0046] In a first embodiment, in which the storage of the first fuel Q1 is under pressure, the operating temperature of the catalyst device 4 is of the order of 600°C to allow the separation of the first fuel QL

[0047] In a second embodiment, in which the storage of the first fuel Q1 is at low temperature, the operating temperature of the catalyst device 4 is of the order of 400°C to allow the separation of the first fuel QL

[0048] At the outlet of the catalyst device 4, the second fuel Q2 is in the gaseous state and is configured to be conveyed to the compressor 5 and the turbomachine M so as to supply it. According to one aspect of the invention, the second fuel Q2 is stored in the gaseous state in order to be available to supply the turbomachine M.

[0049] In a preferred embodiment, the second hydrogenated fuel Q2 is dihydrogen (H2). Preferably, the first hydrogenated fuel Q1 is ammonia (NH3) and the auxiliary component A is dinitrogen (N2).

[0050] Similarly, at the outlet of the catalyst device 4, the auxiliary component A is configured to be either dispersed, or recovered and reused, for example by reassembling it with second fuel Q2 which has been stored, to reform first fuel Q1, or to also be conveyed to the compressor 5 and the turbomachine M to be consumed there.

[0051] Alternatively, auxiliary component A is carbon dioxide (CO2) in the case of a mixture of water (H20) and methanol (CH30H) or water (H2O) and ethanol (C2H5OH) for example.

[0052] According to the invention, the compressor 5 is mounted on the fuel circuit 3 between the catalyst device 4 and the turbomachine M. The compressor 5 is configured, in this example, to raise the pressure of the second hydrogenated fuel Q2 from the storage pressure PI to an injection pressure P2 greater than the storage pressure PI, so as to allow its injection into the turbomachine M.

[0053] Preferably, the injection pressure P2 is between 40 and 60 bar (40000 and 60000 hPa). More preferably, the injection pressure P2 is equal to 60 bar (60000 hPa), corresponding to the pressure in the combustion chamber of the turbomachine M.

[0054] In this example, the supply system 1 according to the invention makes it possible to store ammonia in the liquid state at a temperature above cryotemperatures, which makes it possible to dispense with the installation of a conditioning system. The fuel supply system is thus simpler, while making it possible to carry a larger quantity of dihydrogen than in the systems of the prior art, for an equivalent volume. Alternatively, the system makes it possible to carry an equivalent quantity of dihydrogen to be burned in the combustion chamber in a smaller volume, which allows a significant saving of space in the aircraft.

[0055] In one embodiment, shown in [Fig. 3], the supply system 1 comprises a turbine 6, preferably centripetal, mounted on the fuel circuit 3 upstream of the catalyst device 4.

[0056] In the case of pressurized storage, the turbine 6 allows the first hydrogenated fuel Q1 to be expanded to an intermediate pressure Pib of 1 bar (1000 hPa) to allow the first hydrogenated fuel Q1 to enter the catalyst device 4.

[0057] In the case of low temperature storage, the turbine 6 makes it possible to expand the first hydrogenated fuel Q1 to avoid the need to raise the temperature of the catalyst device 4.

[0058] Preferably, the turbine 6 is mechanically connected to the compressor 5 so as to enable the compressor 5 to be driven by the expansion of the first hydrogenated fuel Q1 in the turbine 6.

[0059] In an alternative embodiment, with reference to [Fig. 3], the catalyst device 4 is configured to separate the first hydrogenated fuel Q1 into a second hydrogenated fuel Q2, an auxiliary component A and a residue of the first hydrogenated fuel Qls. The second hydrogenated fuel Q2 and the residue of the first hydrogenated fuel Qls are then configured to be conveyed together to the combustion chamber of the turbomachine M, without this representing a any risk of damage. In other words, thanks to the invention, it is not necessary to install a high-performance catalyst in the fuel system 1, as was the case in the systems of the prior art. Indeed, residues of the first hydrogenated fuel Q1s can be consumed directly in the turbomachine M with the second hydrogenated fuel Q2 without risk of deterioration. Indeed, the small quantity of first fuel Q1 allows combustion without requiring very high temperatures.

[0060] A catalyst device 4, of simple, light and inexpensive design, can advantageously be used.

[0061] The compressor 5 is then configured to raise the pressure of the second hydrogenated fuel Q2 and the residue of the first hydrogenated fuel Qls to the injection pressure P2 to allow the injection of the second fuel Q2 and the residue of the first hydrogenated fuel Qls into the turbomachine M.

[0062] In a second alternative embodiment (not shown), the second hydrogenated fuel Q2, the auxiliary component A and the residue of the first hydrogenated fuel Qls are configured to be conveyed together to the combustion chamber of the turbomachine M. The compressor 5 is then configured to raise the pressure of the second hydrogenated fuel Q2, of the residue of the first hydrogenated fuel Qls and of the auxiliary component A up to the injection pressure P2, to allow the injection of the second fuel Q2, of the residue of the first hydrogenated fuel Qls and of the auxiliary component A together into the turbomachine M.

[0063] A method for supplying fuel to a turbomachine M according to an embodiment of the invention will now be presented, with reference to [Fig. 3]. In this example, the first fuel Q1 is ammonia NH3 and is stored in the liquid state in the storage tank 2. In this example, the first fuel Q1 is initially at a storage temperature T1 of the order of 20°C and at a storage pressure PI of the order of 10 bar (10000 hPa).

[0064] The method comprises a first step E1 of conveying the first fuel Q1 from the storage tank 2 to the catalyst device 4. The first fuel Q1 passes, in a step E2, through the turbine 6 to be expanded to an intermediate pressure Pib of 1 bar (1000 hPa).

[0065] The first fuel Q1, then at room temperature and atmospheric pressure, is then separated by catalysis in the catalyst device 4, in a step E3. The first fuel Q1 is separated into a second hydrogenated fuel Q2, an auxiliary component A and a residue of first fuel Q1s.

[0066] The second hydrogenated fuel Q2 and the first fuel residue Qls exit the catalyst device 4 and are conveyed, in a step E4, to the compressor 5. In this step E4, the auxiliary component A is dispersed outside the system power supply 1.

[0067] In a step E5, the second hydrogenated fuel Q2 and the residue of the first fuel Qls are then compressed in the compressor 5 to the injection pressure P2, in this example 60 bar (60000 hPa), and are conveyed, in a step E6, to the turbomachine M to be burned and consumed.

Claims

Claims

1. Fuel supply system (1) for an aircraft, the supply system (1) being configured to supply an aircraft turbomachine (M), the fuel being a first hydrogenated fuel (Ql), the supply system (1) comprising: • at least one storage tank (2) configured to store the first hydrogenated fuel (Ql), in the liquid state, at a storage pressure (PI) and at a storage temperature (Tl) greater than a predetermined cryotemperature threshold (Ter), • a fuel circuit (3), connected at the inlet to the storage tank (2) and configured to be connected at the outlet to the turbomachine (M), • a catalyst device (4), mounted on the fuel circuit (3), configured to separate the first hydrogenated fuel (Ql) into at least one second hydrogenated fuel (Q2) and an auxiliary component (A), • a turbine (6), mounted on the fuel circuit (3) upstream of the catalyst device (4),the turbine (6) being configured to lower the pressure of the first hydrogenated fuel (Q1) before it enters the catalyst device (4), and • a compressor (5), mounted on the fuel circuit (3) between the catalyst device (4) and the turbomachine (M), the compressor (5) being configured to raise the pressure at least of the second hydrogenated fuel (Q2) to an injection pressure (P2) higher than the storage pressure (PI), so as to allow the injection of at least the second fuel (Q2) into the turbomachine (M).,

2. The fuel system (1) of claim 1, wherein the catalyst device (4) is configured to separate the first hydrogenated fuel (Ql) into at least one second hydrogenated fuel (Q2), an auxiliary component (A) and at least one residue of the first hydrogenated fuel (Qls), the compressor (5) being configured to raise the pressure of the second hydrogenated fuel (Q2) and the residue of the first hydrogenated fuel (Qls) to the injection pressure (P2) for allow the injection of the second fuel (Q2) and the residue of the first hydrogenated fuel (Qls) into the turbomachine (M).

3. A power system (1) according to claim 2, wherein the compressor (5) is configured to raise the pressure of the second hydrogenated fuel (Q2), the residue of the first hydrogenated fuel (Qls) and the auxiliary component (A) to the injection pressure (P2) to enable the injection of the second fuel (Q2), the residue of the first hydrogenated fuel (Qls) and the auxiliary component (A) into the turbomachine (M).

4. Power supply system (1) according to one of claims 1 to 3, wherein the storage temperature (Tl) is between -40 and 20°C (233 and 293 K).

5. Supply system (1) according to one of claims 1 to 4, wherein the storage pressure (PI) is between 1 and 10 bar (1000 and 10000 hPa).

6. A fuel system (1) according to one of claims 1 to 5, wherein the first hydrogenated fuel (Ql) is an organic hydrogen-carrying liquid (LOHC).

7. A fuel system (1) according to claim 6, wherein the first hydrogenated fuel (Ql) is selected from: ammonia (NH3), ethanol (CH3OH), methanol (C2H5OH) and methyl cyclohexane (CH3C6H11).

8. A fuel system (1) according to one of claims 1 to 7, wherein the second hydrogenated fuel (Q2) is dihydrogen (H2).

9. Aircraft comprising a turbomachine (M) and a power system (1) according to one of claims 1 to 8 for powering the turbomachine (M).

10. Method for supplying an aircraft turbomachine (M) by means of a supply system according to one of claims 1 to 8, the first fuel (Ql) being initially stored in the first storage tank (2) at the storage pressure (PI) and at the storage temperature (Tl) above the predetermined cryotemperature threshold (Ter), the method comprising the steps of: • conveying the first fuel (Ql) from the storage tank (2) to the catalyst device (4), • separating, in the catalyst device (4), the first fuel (Ql) into at least one second hydrogenated fuel (Q2) and a auxiliary component (A), convey at least the second hydrogenated fuel (Q2) to the compressor (5), and compressing at least the second hydrogenated fuel (Q2) in the compressor (5) up to the injection pressure (P2), so as to allow the injection of at least the second fuel (Q2) into the turbomachine (M).

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