Aircraft fuel conditioning system including a purge circuit, associated purge method

Abstract

A fuel conditioning system (SC) supplying at least one aircraft turbomachine (T) with fuel (Q) from a cryogenic tank (RC), the conditioning system (SC) comprising a fuel circuit (CQ) connected inlet to the cryogenic tank (RC) and outlet to the turbomachine (T), a purge circuit (CP) comprising an inlet connected to a purge point (PP) and an outlet connected to an external environment (EXT) of the aircraft, the purge circuit (CP) comprising at least one purge tank (RP) configured to store the fuel flow present in the portion to be purged (PAP) during a purge and at least one supply branch (B1), connecting the purge tank (RP) to the fuel circuit (CQ) or to a fuel-consuming device. Abstract Figure: Figure 2

Description

Title of the invention: Aircraft fuel conditioning system comprising a purge circuit, associated purge method technical field

[0001] The present invention relates to the field of aircraft comprising turbomachines powered by fuel stored in a cryogenic tank.

[0002] Climate change is a major concern for many legislative and regulatory bodies worldwide. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by various states. In particular, an ambitious standard applies to both new types of aircraft and those already in service, requiring the implementation of technological solutions to bring them into compliance with current regulations. Civil aviation has been actively working for several years now to contribute to the fight against climate change.

[0003] Technological research efforts have already led to very significant improvements in the environmental performance of aircraft. The Applicant takes into account the factors impacting all phases of design and development in order to obtain aeronautical components and products that are less energy-intensive, more environmentally friendly, and whose integration and use in civil aviation have moderate environmental consequences, with the aim of improving the energy efficiency of aircraft.

[0004] Consequently, the Applicant is constantly working to reduce its negative climate impact by using methods and operating virtuous development and manufacturing processes that minimize greenhouse gas emissions to the minimum possible in order to reduce the environmental footprint of its activity.

[0005] This sustained research and development work focuses on new generations of aircraft engines, the weight reduction of aircraft, in particular through the materials used and lighter on-board equipment, the development of the use of electrical technologies to provide propulsion, and, as essential complements to technological progress, aviation biofuels.

[0006] It is known to store fuel, particularly hydrogen, in liquid form to limit the size and mass of aircraft tanks. For example, fuel is stored at a temperature of around 20 to 22 Kelvin (-253 to -251°C) in a cryogenic tank on the aircraft.

[0007] In order to be injected into the combustion chamber of a turbomachine, the fuel must be conditioned, i.e., pressurized and heated, to allow for optimal combustion. Conditioning is necessary, for example, to reduce the risk of icing / solidification of the water vapor contained in the air circulating in the turbomachine, particularly at the turbomachine's fuel injectors. With reference to [Fig. 1], a prior art conditioning system SC AA is shown, comprising a fuel circuit CQ connected at its inlet to a cryogenic tank RC and at its outlet to the combustion chamber CC of a turbomachine T. A fuel flow Q circulating from upstream to downstream in the fuel circuit CQ passes successively through a mechanical pump 101 and a heating module 102.The heating module 102 is configured to supply calories to the fuel stream Q in order to warm it so that it can be injected into the turbomachine T.

[0008] As is known, in order to perform maintenance or respond to a malfunction, it is necessary to quickly purge at least a portion of the fuel circuit, referred to as the "purge portion PAP." The purge portion PAP includes a purge point PP to which a purge circuit CP is connected. Conventionally, the purge circuit CP connects the purge point PP to the external environment EXT so as to allow the rapid expulsion of fuel Q from the purge portion PAP. Such a CP purge circuit has the disadvantage of wasting a significant quantity of fuel Q, which affects profitability and, above all, is not environmentally friendly.

[0009] The invention thus aims to eliminate at least some of these drawbacks by proposing a new purge circuit for a cryogenic fuel conditioning system. PRESENTATION OF THE INVENTION

[0010] The invention relates to a fuel conditioning system supplying at least one aircraft turbomachine with fuel from a cryogenic tank, the conditioning system comprising: • a fuel circuit connected at the inlet to the cryogenic tank and at the outlet to the turbomachine, a fuel flow circulating from upstream to downstream in the fuel circuit and at least one heat exchanger, mounted in the fuel circuit, configured to transfer heat to the fuel flow, • the fuel circuit including at least one section to be purged, including a bleed point, • a purge circuit comprising an inlet connected to the purge point and an outlet connected to an external environment of the aircraft, • the purge circuit comprising at least one purge tank configured to store the fuel flow present in the portion to be purged during a purge and at least one supply branch, connecting the purge tank to the fuel circuit and / or to a fuel consumption equipment.

[0011] Advantageously, the purge circuit allows the purge volume to be stored This is a temporary measure to reuse the fuel and avoid waste. Advantageously, the purge circuit always includes an outlet to the outside environment to allow for rapid evacuation for safety reasons.

[0012] According to one aspect, the purging circuit includes a filtration device configured to remove at least one purging fluid mixed with the fuel flow. This makes it possible to purify the fuel that may be mixed with a purging fluid during a purging operation.

[0013] According to one aspect, the filtration device is configured to remove at least one purge fluid selected from argon (Ar), helium (He), carbon dioxide (CO2) or preferably nitrogen (N2).

[0014] According to one aspect, the fuel circuit includes a shut-off valve that delimits the portion to be purged downstream. The supply branch is connected downstream of the shut-off valve to the fuel circuit. This allows the purged volume to be directly reintroduced into the fuel circuit, which is advantageous. Any waste is avoided.

[0015] According to one aspect, the fuel circuit is connected at its outlet to a fuel consumption device that is nominally powered from the fuel circuit. The supply branch of the purge circuit is connected to the fuel consumption device. This allows electricity to be generated from the purge volume. The aircraft's energy efficiency is thus optimized.

[0016] According to one aspect, the power supply branch is configured to supply the fuel consumption equipment independently of the fuel circuit. This provides a parallel power supply to generate electricity in the event of a malfunction.

[0017] According to one aspect, the fuel consumption equipment is a fuel cell or an auxiliary turbomachine.

[0018] In one aspect, the fuel is liquid hydrogen, which is particularly advantageous for powering a fuel cell.

[0019] According to one aspect, the fuel is liquid methane or liquefied natural gas in particular to power an auxiliary turbomachine, for example, of the APU type for "Auxiliary Power Unit".

[0020] According to one aspect, the fuel circuit includes a portion to be purged that can be purged independently. Preferably, the fuel circuit includes a shut-off valve so as to close off the downstream fuel supply.

[0021] Also shown is an aircraft comprising a turbomachine and a fuel conditioning system as previously shown for supplying the turbomachine with fuel from a cryogenic tank.

[0022] The invention relates to a method for purging a portion to be purged from a fuel circuit of a fuel conditioning system as shown, the portion to be purged being isolated from the fuel circuit, the method comprising steps consisting of: • Open the bleed valve to purge the section of the fuel system to be bled and • Store the fuel flow from the portion to be purged in the purge tank.

[0023] Preferably, the method includes a step of supplying the fuel circuit or fuel consumption equipment with the fuel stream stored in the purge tank. PRESENTATION OF THE FIGURES

[0024] The invention will be better understood upon reading the following description, 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.

[0025] Fig. 1 is a schematic representation of a fuel conditioning system according to the prior art.

[0026] Figure 2 is a schematic representation of a conditioning system fuel according to an embodiment of the invention to supply the fuel circuit from the purge tank.

[0027] Fig. 3 is a schematic representation of a fuel conditioning system according to one embodiment of the invention for supplying a fuel cell from the purge tank.

[0028] Figure 4 is a schematic representation of a variant of the system of conditioning of the [Fig.3].

[0029] Fig. 5 is a schematic representation of a fuel conditioning system according to one embodiment of the invention for supplying the fuel circuit and a fuel cell from the purge tank.

[0030] It should be noted that the figures set out the invention in detail to implement the invention, said figures being of course able to serve to better define the invention where appropriate. DETAILED DESCRIPTION OF THE INVENTION

[0031] With reference to [Fig. 2], a fuel conditioning system SC is shown, configured to supply an aircraft turbomachine T with fuel Q from a cryogenic tank RC. The turbomachine T is configured to provide propulsion for the aircraft, in particular by driving at least one propulsion unit (not shown in [Fig. 2]). In this example, the fuel is liquid hydrogen, but the invention applies to other types of fuel, for example, liquid methane or liquefied natural gas. The invention is particularly advantageous with liquid hydrogen.

[0032] With reference to [Fig.2], the conditioning system SC includes a fuel circuit CQ connected inlet to the cryogenic tank RC and outlet to the combustion chamber CC of the turbomachine T. The conditioning system SC also includes a pump 1, preferably high pressure, configured to circulate a flow of fuel Q from upstream to downstream in the fuel circuit CQ.

[0033] With reference to [Fig.2], the conditioning system SC includes a heat exchanger 2 mounted in the fuel circuit CQ to transfer calories to the fuel stream Q in order to warm it up to allow its optimal injection into the turbomachine T. It is understood that the conditioning system SC could include a plurality of heat exchangers supplied with hot sources of the same or different natures.

[0034] The CQ fuel circuit includes a PAP purge portion that is configured to be purged independently. In this example, the CQ fuel circuit includes a shut-off valve VF delimiting the PAP purge portion downstream. The PAP purge portion is delimited upstream by pump 1 as illustrated in [Fig. 2]. It is understood, however, that the PAP purge portion could be positioned differently. In this example, the PAP purge portion contains liquid fuel Q and is thermally insulated.

[0035] The portion to be purged PAP must be purged under various conditions, for example, in the event of maintenance or malfunction. For example, in the event of a malfunction downstream of the shut-off valve VF, the fuel flow is purged to allow time for pump 1 to stop. As another example, if the fuel is deemed unfit, it can also be purged.

[0036] With reference to [Fig. 2], the conditioning system SC includes a purge circuit CP comprising an inlet connected to a purge point PP of the fuel circuit CQ. The purge point PP belongs to the portion to be purged PAP as illustrated in [Fig. 2].

[0037] The CP purge circuit includes an external outlet connected to an external environment EXT of the aircraft. This allows any fuel flow Q to be discharged in case of a risk to operational safety. For this purpose, the CP purge circuit includes a VP purge valve moving at least between an open position allowing purging and a closed position preventing purging.

[0038] With reference to [Fig. 2], the purge circuit CP includes a purge tank RP configured to store the fuel flow Q from the portion to be purged PAP during a purge. For example, the purge tank RP has a volume between 100 L and 200 L. Thus, the purge tank RP can store several successive purges, thereby maximizing the use of purge volumes. The fuel in the purge tank RP can be gaseous or liquid. The purge tank RP is separate from the fuel tank RC.

[0039] In this example, with reference to [Fig. 2], the purge circuit CP includes a supply branch Bl, B2, connecting the purge tank RP to the fuel circuit CQ ([Fig. 2]) or to a fuel consumption device 3 (Figures 3 and 4). It is understood that the fuel circuit could include several supply branches ([Fig. 5]).

[0040] With reference to Figure 2, the purge circuit CP includes a supply branch Bl, connecting the purge reservoir RP to the fuel circuit CQ so as to subsequently reintroduce the purge volume into the fuel circuit CQ. In this example, the supply branch Bl is connected to the fuel circuit CQ downstream of the shut-off valve VF so as to allow reintroduction when the shut-off valve VF is in the closed position following a purge.

[0041] Preferably, the supply branch Bl includes a supply valve 51 for controlling the circulation of fuel in the supply branch BL. The supply branch Bl further includes a supply pump 52 for pressurizing the fuel flow Q from the purge tank RP so as to inject it with the optimal pressure into the fuel circuit CQ.

[0042] As illustrated in [Fig.2], the outlet of the purge tank RP is connected to the external environment EXT. Preferably, a valve VE is provided to control the purge to the external environment EXT.

[0043] According to one aspect, as illustrated in [Fig. 2], the purge circuit CP includes a filtration device 6 configured to remove from the fuel flow Q at least one purge fluid mixed with the fuel flow Q. Indeed, a purge device 7 can be connected to the portion to be purged PAP in order to inject a purge fluid to facilitate the complete and safe removal of the fuel flow Q. The purge fluid is preferably an inert gas.

[0044] Preferably, the filtration device 6 is configured to remove a purge fluid selected from argon (Ar), helium (He), carbon dioxide (CO2), or preferably nitrogen (N2). The filtration device 6 is configured to preferred method in the form of a catalytic device, in particular, known by its English designation CFS for "catalytic filtration system".

[0045] As shown in [Fig. 2], the filtration device 6 is preferably positioned upstream of the purge tank RP so as to store a filtered fuel flow Q suitable for direct use. Thus, the fuel flow Q in the purge tank RP is purified.

[0046] With reference to [Fig. 3], the purge circuit CP comprises a supply branch B2, connecting the purge tank RP to a fuel-consuming device 3, in particular, to a fuel cell. It is understood that the invention applies to other fuel-consuming devices, for example, an auxiliary turbomachine.

[0047] In this example, the fuel circuit CQ is connected at its output to the turbomachine T and also to a fuel cell. The fuel cell is nominally supplied with fuel Q from the cryogenic tank RC via the fuel circuit CQ. The fuel cell generates electrical energy to power loads L, for example, electric propulsion motors, turbomachine equipment, an aircraft power supply network, etc.

[0048] As illustrated in [Fig. 3], the B2 supply branch of the CP purge circuit is connected to the fuel cell to supply it. Preferably, the B2 supply branch is configured to supply the fuel cell independently of the CQ fuel circuit. This increases redundancy by providing a backup power supply.

[0049] With reference to [Fig. 3], the supply branch B2 is connected to the outlet of the purge tank RP, in particular, by a multiport valve 8 in order to direct the fuel flow Q to the external environment EXT or to the fuel cell. Similarly to the above, the purge circuit CP may include a filtration device 6 as illustrated in [Fig. 4].

[0050] With reference to [Fig. 5], a mixed case is shown with a first supply branch B1 to the fuel circuit CQ and a second supply branch B2 to the fuel cell. It is understood that the number of supply branches could be greater. This allows for several different solutions to optimize the use of purge volumes.

[0051] An example of the implementation of a purging process for the portion to be purged PAP of a CQ fuel circuit will henceforth be presented with reference to the SC conditioning system of [Fig.5].

[0052] The portion to be purged (PAP) is first isolated from the rest of the fuel circuit (CQ) by controlling the shut-off valve (VF) to the closed position. The purge volume, That is to say, the volume of fuel between pump 1 and the shut-off valve VF can be advantageously purged. The purge volume can also be upstream of the pumps if there are low-pressure pumps in the cryogenic tank RC.

[0053] The purging process then includes a step of opening the purge valve VP so as to circulate the purge volume from the portion to be purged PAP into the purge circuit CP in order to fill the purge tank RP.

[0054] Preferably, when the purge valve VP is open, the purging process includes a step of admitting a purge fluid into the portion to be purged PAP by the purge device 7 so as to ensure optimal cleaning while avoiding any risk of explosion.

[0055] The purging process includes a step of removing the purging fluid mixed with the fuel stream Q by the filtration device 6. This advantageously allows a purified fuel stream Q to be stored in the purging tank RP, ready for rapid use.

[0056] The method includes a step of determining the opening of the valves so as to direct the fuel flow Q from the purge tank RP to: • To the external environment (EXT) in case of maintenance, malfunction, or critical event, • Towards the CQ fuel circuit, the Q fuel flow from the RP purge tank is then compressed to be reintroduced into the CQ fuel circuit to supply the turbomachine T, • Towards the fuel cell which can thus be powered independently, which improves redundancy and therefore operational safety.

[0057] Thanks to the invention, the purged fuel flow Q can advantageously be used for consumption in a turbomachine T or in fuel consumption equipment, such as a fuel cell, thereby reducing waste and reducing the environmental impact during a purge.

Claims

Demands

1. Fuel conditioning system (SC) supplying at least one aircraft turbomachine (T) with fuel (Q) from a cryogenic tank (RC), the conditioning system (SC) comprising: • a fuel circuit (CQ) connected inlet to the cryogenic tank (RC) and outlet to the turbomachine (T), a fuel flow (Q) circulating upstream to downstream in the fuel circuit (CQ) and at least one heat exchanger (2), mounted in the fuel circuit (CQ), configured to transfer heat to the fuel flow (Q), • the fuel circuit (CQ) comprising at least one purge portion (PAP) including a purge point (PP), • a purge circuit (CP) comprising an inlet connected to the purge point (PP) and an outlet connected to an external environment (EXT) of the aircraft,• the purge circuit (PC) comprising at least one purge reservoir (PR) configured to store the fuel flow (Q) present in the portion to be purged (PAP) during a purge and at least one supply branch (B1, B2), connecting the purge reservoir (PR) to the fuel circuit (CQ) and / or to a fuel consumption device (3).

2. Fuel conditioning system (SC) according to claim 1, wherein the purge circuit (CP) includes a filtration device (6) configured to remove at least one purge fluid mixed with the fuel stream (Q).

3. Fuel conditioning system (SC) according to claim 2, wherein the filtration device (6) is configured to remove at least one purge fluid selected from argon (Ar), helium (He), carbon dioxide (CO2) or, preferably, nitrogen (N2).

4. Fuel conditioning system (SC) according to any one of claims 1 to 3, wherein the fuel circuit (CQ) includes a shut-off valve (VF) delimiting downstream the portion to be purged (PAP), the supply branch (Bl) is connected downstream of the shut-off valve (VF) to the fuel circuit (CQ).

5. Fuel conditioning system (SC) according to any one of claims 1 to 4, wherein, the fuel circuit (CQ) being connected at the output to a fuel consumption equipment (3) nominally supplied from the fuel circuit (CQ), the supply branch (B2) of the purge circuit (CP) is connected to the fuel consumption equipment (3).

6. Fuel conditioning system (SC) according to claim 5, wherein the supply branch (B2) is configured to supply the fuel consumption equipment (3) independently of the fuel circuit (CQ).

7. Fuel conditioning system (SC) according to any one of claims 1 to 4, wherein the fuel consuming equipment (3) is a fuel cell or an auxiliary turbomachine.

8. Aircraft comprising a turbomachine (T) and a fuel conditioning system (SC) according to any one of claims 1 to 6 for supplying the turbomachine (T) with fuel (Q) from a cryogenic tank (RC).

9. A method for purging a portion to be purged (PAP) of a fuel circuit (CQ) of a fuel conditioning system (SC) according to any one of claims 1 to 7, the portion to be purged (PAP) being isolated from the fuel circuit (CQ), the method comprising steps of: • Opening the purge circuit (CP) so as to purge the portion to be purged (PAP) from the fuel circuit (CQ) and • Storing the fuel flow (Q) from the portion to be purged (PAP) in the purge tank (RP).

10. Purge method according to claim 9, comprising a step of supplying the fuel circuit (CQ) or fuel consumption equipment (3) with the fuel stream (Q) stored in the purge tank (RP).

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