(19)
(11)EP 3 315 411 A1

(12)EUROPEAN PATENT APPLICATION

(43)Date of publication:
02.05.2018 Bulletin 2018/18

(21)Application number: 17199212.6

(22)Date of filing:  30.10.2017
(51)International Patent Classification (IPC): 
B64D 37/32(2006.01)
A62C 3/08(2006.01)
B64D 37/34(2006.01)
(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR
Designated Extension States:
BA ME
Designated Validation States:
MA MD

(30)Priority: 31.10.2016 US 201662414855 P

(71)Applicant: Hamilton Sundstrand Corporation
Windsor Locks, CT 06096-1010 (US)

(72)Inventors:
  • RHEAUME, Jonathan
    West Hartford, CT 06119 (US)
  • CORDATOS, Haralambos
    Colchesster, CT 06415 (US)

(74)Representative: Hughes, Andrea Michelle 
Dehns St Bride's House 10 Salisbury Square
London EC4Y 8JD
London EC4Y 8JD (GB)

  


(54)FUEL STABILIZATION CHAMBER


(57) A system for generating inert gas comprising includes a fuel tank (20) including an inner storage volume (24) containing a fuel. A fuel stabilization chamber (30) has an inner volume (32). The inner volume of said fuel stabilization chamber is arranged in fluid communication with the inner storage volume such that said fuel is movable from the inner storage volume to the inner volume. An inert gas device (62) is operably coupled to the inner volume of the fuel stabilization chamber. Inert gas output from the inert gas device interacts with a fuel in the inner volume to remove dissolved oxygen from the fuel in said inner volume.




Description

CROSS-REFERENCE TO RELATED APPLICATIONS



[0001] This application claims the benefit of Provisional Application Serial No. 62/414,855, filed October 31, 2016.

BACKGROUND OF THE INVENTION



[0002] This invention generally relates to the aircraft on-board systems, and more particularly, to a fuel stabilization system.

[0003] On-board Inert Gas Generating Systems (OBIGGS) are used to introduce an inert gas into the fuel tanks of a vehicle, such as an aircraft. The inert gas displaces potentially dangerous fuel and air mixtures, thereby reducing the risk of explosion or fire. Further, the dissolved oxygen within the fuel may react with fuel and form solids that block the flow of fuel along the fuel passage and that foul heat exchange surfaces. Inert gas can be used to remove dissolved oxygen from fuel. Typically, OBIGGS process air from an air source, such as bleed air taken from the engines of an aircraft. A deoxygenated air is typically generated by separating oxygen from local, ambient air and pumping the deoxygenated air into the ullage of the tank.

BRIEF DESCRIPTION OF THE INVENTION



[0004] According to one embodiment, a system for generating inert gas includes a fuel tank including an inner storage volume containing a fuel. A fuel stabilization chamber has an inner volume. The inner volume of said fuel stabilization chamber is arranged in fluid communication with the inner storage volume such that said fuel is movable from the inner storage volume to the inner volume. An inert gas device is operably coupled to the inner volume of the fuel stabilization chamber. Inert gas output from the inert gas device interacts with a fuel in the inner volume to remove dissolved oxygen from the fuel in said inner volume.

[0005] In addition to one or more of the features described above, or as an alternative, in further embodiments said fuel stabilization chamber is separate from said fuel tank.

[0006] In addition to one or more of the features described above, or as an alternative, in further embodiments said fuel stabilization chamber is integrally formed with said fuel tank, and said fuel in said inner storage volume and said fuel in said inner volume are separated by a dividing wall.

[0007] In addition to one or more of the features described above, or as an alternative, in further embodiments comprising a component fluidly coupled to said inner volume, wherein said inert gas device provides said inert gas to said fuel in said inner volume in response to a demand of said component.

[0008] In addition to one or more of the features described above, or as an alternative, in further embodiments said inert gas device converts pressurized air into an oxygen enriched air flow and an inert gas enriched air flow, said inert gas enriched air flow being provided to said inner volume as said inert gas.

[0009] In addition to one or more of the features described above, or as an alternative, in further embodiments said inert gas device includes at least one of an air separation module and an electrochemical device.

[0010] In addition to one or more of the features described above, or as an alternative, in further embodiments said inert gas device includes a stored supply of inert gas.

[0011] In addition to one or more of the features described above, or as an alternative, in further embodiments said interaction of said inert gas with said fuel in said inner volume performs a fuel tank inerting operation.

[0012] In addition to one or more of the features described above, or as an alternative, in further embodiments said dissolved oxygen is removed from said fuel in said inner volume and said fuel inerting operation occur simultaneously.

[0013] In addition to one or more of the features described above, or as an alternative, in further embodiments comprising: a first pump for moving said fuel from said inner storage volume to said inner volume and a second pump for providing said fuel from said inner volume to a downstream component.

[0014] In addition to one or more of the features described above, or as an alternative, in further embodiments said downstream component is at least one of an engine and a thermal management system.

[0015] In addition to one or more of the features described above, or as an alternative, in further embodiments said temperature of said inert gas provided to said fuel is less than or equal to about 80°C at sea level.

[0016] In addition to one or more of the features described above, or as an alternative, in further embodiments comprising a conduit extending from said inert gas device into said inner volume, said conduit being operable to expel said inert gas therefrom as a plurality of bubbles.

[0017] According to another embodiment, a method of eliminating dissolved oxygen from fuel to discourage the formation of solid deposits includes providing a portion of fuel from an inner storage volume of a fuel tank to an inner volume of a fuel stabilization chamber. A supply of inert gas is provided to the inner volume of the fuel stabilization chamber. The inert gas and the portion of fuel in said inner volume interact to remove dissolved oxygen from said fuel in said inner volume.

[0018] In addition to one or more of the features described above, or as an alternative, in further embodiments comprising supplying said fuel in said inner volume to a component in response to a demand by said component after said interaction.

[0019] In addition to one or more of the features described above, or as an alternative, in further embodiments said interaction between said portion of fuel in said inner volume and said inert gas inerts said fuel tank.

[0020] In addition to one or more of the features described above, or as an alternative, in further embodiments said inert gas-enriched air is supplied to said fuel at a temperature less than or equal to about 80°C at sea level.

[0021] In addition to one or more of the features described above, or as an alternative, in further embodiments comprising providing pressurized air to said inert gas device and separating said pressurized air into an oxygen-enriched air and an inert-gas enriched air, said inert-gas enriched air being provided to said inner volume as said supply of inert gas.

[0022] In addition to one or more of the features described above, or as an alternative, in further embodiments said portion of fuel is provided from said inner storage volume to said an inner volume in response to a demand from a component operably coupled to said fuel stabilization chamber.

[0023] According to yet another embodiment, a system for generating inert gas includes a fuel tank including an inner volume containing a fuel. An inert gas device is operably coupled to the inner volume of the fuel tank. The inert gas output from said inert gas device interacts with only a portion of said fuel in the inner volume to remove dissolved oxygen from said portion of fuel.

BRIEF DESCRIPTION OF THE DRAWINGS



[0024] The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a plan view of an example of an aircraft;

FIG. 2 is a schematic diagram of a portion of a fuel system of an aircraft;

FIG. 3 is a schematic diagram of an example of a fuel tank and fuel stabilization chamber according to an embodiment;

FIG. 4 is a schematic diagram of an example of a fuel tank and fuel stabilization chamber according to another embodiment;

FIG. 5 is a schematic diagram of deoxygenation system associated with a fuel stabilization chamber according to another embodiment;

FIG. 6 is a schematic diagram of a system for thermally conditioning a fuel according to an embodiment;

FIG. 7 is a schematic diagram of a system for stabilizing a fuel in multiple stages according to an embodiment; and

FIG. 8 is a schematic diagram of another system for stabilizing a fuel in multiple stages according to an embodiment.


DETAILED DESCRIPTION OF THE INVENTION



[0025] FIG. 1 is a plan view of an aircraft 2, such as a commercial airliner for example. The aircraft 2 includes a fuselage 4, a left and right wing 6, 6, and under-wing mounted engines 8. Arranged within an interior volume of the aircraft 2 is a fuel system having at least one fuel tank for storing aviation fuel. With reference to FIG. 2, the fuel tanks of a fuel system 10 having a three tank configuration are illustrated. As shown, the fuel system 10 includes a left wing tank 12, a right wing tank 16 and a center tank 14. The fuel system 10 additionally includes a ventilation system (not shown) for ventilating the ullage of each of the tanks 12, 14, 16. The fuel system 10 illustrated and described herein is intended as an example only, and other fuel systems having any number of tanks arranged in any configuration are also within the scope of the disclosure.

[0026] Referring now to FIGS. 3 and 4, an example of a tank 20 for use in a fuel system, such as fuel system 10 is illustrated. However, it should be understood that fuel systems configured for use in other applications, such as motor vehicle and marine applications for example, are also contemplated herein. The tank 20 is configured to store a quantity of fuel 22 therein. Although the tank 20 is generally shown as being rectangular in shape, a tank 20 having any shape is within the scope of the disclosure. The tank 20 defines an inner storage volume or inner cavity 24 within which liquid fuel 22 is received and stored. Gases typically fill the ullage 26 located above the surface of the fuel 22. In some embodiments, the fuel 22 within the tank 20 may have already been stabilized (i.e. by sparging, by membranes, or by other methods) to remove dissolve oxygen therefrom prior to filling the tank 20 with the fuel 22.

[0027] The inner storage volume 24 of the tank 20 is fluidly coupled to a fuel stabilization chamber 30. The fuel stabilization chamber 30 includes an inner volume 32 for storing a limited supply of fuel 34 received from the inner storage volume 24 of tank 20. The inner volume 32 of the fuel stabilization chamber 30 is generally smaller than the inner storage volume 24 of the tank 20; however, embodiments where the inner volume 32 is greater than or equal to the inner storage volume 24 are also contemplated herein. The fuel stabilization chamber 30 may be an enclosed volume in which case a provision or mechanism for the egress of gases is necessary. A gas release mechanism configured to remove gases from chamber 30 is envisioned. In an embodiment, the gas release mechanism is a degassing valve. The gas release mechanism may function in conjunction with a liquid-gas separation mechanism. In an embodiment, the flow path is outfitted with vanes to deflect bubbles towards the gas release mechanism. Vented gases from chamber 30 may be directed into inner storage volume 24 for the purpose of fuel tank-inerting or vented overboard.

[0028] For the purposes of this disclosure, it should be understood that the fuel stabilization chamber 30 may include any body containing a volume of fuel. In an embodiment, the volume of fuel is physically isolated from another volume of fuel, such as a collector cell within the inner storage volume 24. Accordingly, in an embodiment, a fuel line, pipe, or tube extending from the fuel tank 20, or even the fuel tank itself may be considered a fuel stabilization chamber 30 within this disclosure.

[0029] In an embodiment, best shown in FIG. 3, the fuel stabilization chamber 30 is a separate component from the tank 20 and is fluidly coupled to thereto with at least one fuel line 36 and is fluidly coupled to an engine or thermal management system, illustrated schematically at E, with one or more fuel lines 38. With such configurations, the tank 20 and the fuel stabilization chamber 30 may be located in the same area, or in different areas of a vehicle. For example, in an aircraft, the tank 20 may be located centrally within the fuselage 4, and the fuel stabilization chamber 30 may be positioned closer to an engine E, such as within a wing 6 of the aircraft 2. In another embodiment, illustrated in FIG. 4, the fuel stabilization chamber 30 is a compartment formed within the tank 20. In such embodiments, a dividing wall 40, such as a baffle for example, separates the fuel 22 within the inner storage volume 24 of the tank 20 from the fuel 34 within the inner volume 32 of the fuel stabilization chamber 30.

[0030] Fuel is supplied to an engine or thermal management system E from the inner volume 32 of the fuel stabilization chamber 30. A first pump 42, commonly referred to as a scavenge pump, is operable to move fuel from the inner storage volume 24 to the inner volume 32 of the fuel stabilization chamber 30 via one or more fuel lines 36. A second pump 44, sometimes referred to as a boost pump, is operable to provide fuel 34 from the inner volume 32 of the fuel stabilization chamber 30 to the engine E via at least one fuel line 38. In an embodiment, operation of the first pump 42 is dependent on operation of the second pump 44. For example, the first pump 42 may be powered by the high pressure flow generated during operation of the second pump 44.

[0031] One or more of the first pump 42, the second pump 44, and a portion of the engine E are operably coupled to a controller 50. In an embodiment, the controller 50 is configured to control operation of both the first pump 42 and the second pump 44 to maintain at least a minimum amount of fuel 34 in the inner volume 32 of the fuel stabilization chamber 30 at all times. The controller 50 may additionally operate the second pump 44 in response to the fuel demand of the engine E and operate the first pump 42 to provide a desired amount of fuel 22 to the fuel stabilization chamber 30. Alternatively, the first pump 42 may be configured to continuously pump fuel 22 from the inner storage volume 24 into the inner volume 32 of the fuel stabilization chamber 30.

[0032] Referring now to FIGS. 5-8, a system 60 for stabilizing fuel, by removing dissolved oxygen therefrom, may be associated with a portion of fuel system. Stabilizing the entirety of the inner storage volume 24 of the fuel tank 20 is impractical for fuel 22 that has not been partially or fully stabilized prior to introduction into fuel tank 20. This impracticality is due to the size of the equipment needed and the attendant fuel requirement for operation and transport of said equipment. In an embodiment, the system 60 is operably coupled to and is configured to remove dissolved oxygen from only a limited portion of fuel, such as the fuel 34 within the fuel stabilization chamber 30. The system 60 for stabilizing fuel includes at least one inert gas device 62. In an embodiment, the inert gas device 62 includes one or more pressure swing adsorption (PSA) devices. In an embodiment, the inert gas device 62 includes one or more air separation modules (ASM), each having at least one permeable membrane. Alternatively or in addition, the inert gas device 62 may include an electrochemical device or a stored supply of inert gas. An example of a suitable electrochemical device includes at least one proton exchange membrane device as described in U.S. Patent Application Serial No. 15/151,132, filed on May 10, 2016. Similarly, the inert gas device 62 may include a combination of devices, such as an air separation module and an electrochemical device, as described in U.S. Patent Application Serial No. 15/169,165, filed on May 31, 2016.

[0033] The size and inert gas generating capacity of the inert gas device may vary depending on the demands of an application. For example, in some embodiments the inert gas device 62 may be sized to handle fuel entering the fuel stabilization chamber 30 that is fully saturated in oxygen. Alternatively, the inert gas device 62 may be sized for use with a fuel that contains only a small concentration of dissolved oxygen, such as fuel in a "pre-stabilized" condition. In yet another embodiment, the inert gas device 62 may be sized based on a specific phase or flight condition during operation of the aircraft. For example, the inert gas device 62 may be sized for a climb phase in which gases including oxygen evolve from fuel stored in vented fuel tanks due to low ambient pressure. Alternatively, the inert gas device 62 may be sized for a descent phase in which outside air enters the ullage due to unequal pressure.

[0034] In embodiments where the inert gas device 62 includes a PSA device, an ASM, or an electrochemical device, the inert gas device 62 is configured to receive pressurized air A supplied from a pressurized air source 64. The pressurized air source 64 may include one or more engines, such as of an aircraft for example. In such embodiments, the pressurized air A may be bled from a compressor section of the engine E. However, embodiments where the pressurized air source 64 is not an engine are also contemplated herein. For example, the pressurized air source 64 may include a compressor (not shown) configured to pressurize ambient air as it passes there through. The compressor may be driven by a mechanical, pneumatic, hydraulic, or electrical input.

[0035] In an embodiment, the inert gas device 62 is configured to separate the pressurized air A into an oxygen-enriched permeate and an inert gas-enriched (oxygen-depleted) air, also referred to as retentate. Oxygen-enriched and water-enriched air permeate is released from the inert gas device 62 to the ambient atmosphere, and the dry, inert gas-enriched air is directed to a fuel stabilization chamber 30.

[0036] The system for stabilizing fuel 60 may additionally include one or more components commonly found in existing fuel inerting systems. For example, the pressurized air A may be configured to flow through one or more filters 66, such as a coalescing filter to separate liquid water from oil, and a particulate filter to remove particulate contaminants, and a carbon filter for removing hydrocarbons from the supply of pressurized air A before being provided to the inert gas device 62. Alternatively, or in addition, the system 60 may include an ozone conversion means 68 for reducing the ozone concentration of the pressurized air A. It should be understood that both the filter 66 and ozone conversion means 68 may be located at any relative position within the system 60, upstream from the inert gas device 62.

[0037] Further, because the pressurized air A from the pressurized air source 64 is generally hot, in an embodiment, the system 60 includes at least one cooling device 70 for cooling either temperature of the pressurized air A before it is provided to the inert gas device 62 and/or the fuel stabilization chamber. An example of a cooling device 70 includes a heat exchanger configured to arrange the pressurized air in a heat transfer relationship with a secondary cooling flow, such as fan bypass air from the pressurized air source 64 or ram air for example. In the illustrated, non-limiting embodiment, the cooling device 70 is arranged downstream of filter 66 and ozone conversion means 68; however, configurations in which cooling device 70 is located upstream of filter 66 and ozone conversion means 68 are also contemplated herein. Similarly, configurations where the cooling device 70 is located downstream of the inert gas device 62 are also contemplated herein.

[0038] In an embodiment, a backpressure regulator 72 is associated with the inert gas device 62 to ensure that a pressure necessary for operation of the inert gas device 62 is continuously maintained therein. Alternatively or in addition, a flow control device 74, such as a valve for example, configured to control the flow of pressurized air A through the system 60 may be disposed at any location along the fluid flow path between the source 64 of the pressurized air A and a final destination of the inert gas. In embodiments where the source 64 includes a compressor, the flow control device 74 may include a variable speed motor associated with the compressor. Although the flow control device 74 is illustrated as being disposed upstream of the inert gas device 62 in each of the embodiments, systems 20 where the flow control device 72 is arranged downstream from the inert gas device 62 are also contemplated herein. The controller 50 may be operably coupled to the flow control device to control the flow of pressurized air A to the inert gas device 62, and therefore the output of inert gas form the inert gas generating device in response to a demand of the engine E.

[0039] The inert gas or the inert gas-enriched air output from the inert gas device 62, both of which are incorporated in the term "inert gas" used hereinafter, is used to stabilize the fuel 34 within the fuel stabilization chamber 30 by removing dissolved oxygen therefrom. Although the system 60 is illustrated with respect to a single fuel stabilization chamber 30 in FIG. 5, embodiments of the system 60 where the inert gas from an inert gas device 62 is provided to more than one fuel stabilization chamber 30, as shown in FIG. 7, are also within the scope of the disclosure.

[0040] In such embodiments, the inert gas output from the inert gas device 62 has an oxygen content of less than about 18% by volume, and more specifically less than about 12%, less than about 10%, less than about 5%, and less than about 2% by volume. By using nearly pure gas in lieu of gas-enriched air, the total volume of gas necessary for inerting purposes is reduced. The inert gas described herein is generally referred to as nitrogen; however, it should be understood that the inert gas may contain other species in lower concentrations including non-inert species such as oxygen. In an embodiment, the inert gas should maintain this level of less than 2% oxygen by volume during all operating conditions of the vehicle, particularly during the period of operation having the highest inert gas demand. Alternatively or in addition, the ullage 35 of the fuel stabilization chamber 30 may be preloaded with highly oxygen-depleted inert gas prior to or during the period of operation having the highest inert gas demand to prevent the oxygen concentration from to exceeding a desired threshold.

[0041] In the illustrated, non-limiting embodiment, stabilization of the fuel 34 within the fuel stabilization chamber 30 is performed via a sparging operation. However, other methods of stabilizing the fuel by interacting the liquid fuel 34 with an inert gas are also contemplated herein. To sparge the fuel stabilization chamber 30, a conduit 76 extends from the inert gas device 62 or another upstream component, into the interior volume 32 of the fuel stabilization chamber 30. In some embodiments, maneuvers of the aircraft may cause conduit 76 not to be immersed in which case a plurality of conduits 76 may be co-located within the interior 32 of the fuel stabilization chamber 30 in various orientations and spatial locations with provisions to switch flow of inert gas there between. In an embodiment, conduit 76 may have a tortuous shape that will ensure that a portion of inert gas is submerged in fuel at all time. Preferentially, the inert gas interacts directly with the fuel 34 rather than being provided to the ullage 35 of the fuel stabilization chamber 30. The conduit 76 may include ports, nozzles, pores, or orifices 78 of a suitable size for injecting the inert gas into the fuel 34, thereby creating a bubbling effect, as illustrated. The bubbles of inert gas will rise toward the ullage 35, with a portion of the inert gas being dissolved into the fuel 34.

[0042] By supplying the inert gas to the fuel 34, the content of dissolved inert gas in the fuel 34 is increased and the content of dissolved oxygen is decreased according to Henry's Law. Therefore, the injection of the inert gas bubbles into the fuel 34 exposes the liquid fuel to a higher partial pressure of inert gas, such as nitrogen, and a considerably lower partial pressure of oxygen resulting in oxygen leaving the fuel 34. The fuel stabilization chamber 30 may be outfitted with baffles, turbulators, etc., to increase the residence time (contact time) between the inert gas and the fuel for improved oxygen removal. In addition, the ports, nozzles, pores, or orifices 78 associated with conduit 76 may be oriented such as to increase the residence time of inert gas within the inner volume 32. The system 20 is therefore effectively used to remove the dissolved oxygen in the fuel 34 within the fuel stabilization chamber 30 and to introduce inert gas.

[0043] Conventional inert gas generation systems thermally regulate the inert gas temperature to 80°C or less due to structural limits of fuel tank materials. The temperature of the inert gas provided to the fuel stabilization chamber 30 may be lower than the 80°C typically required in a normal fuel tank inerting system. A reduced temperature may be desirable to avoid vaporizing the volatile fractions of the fuel 34 within the fuel stabilization chamber 30. In an embodiment, the temperature of the inert gas provided to the fuel stabilization chamber 30 is less than the boiling point of the lightest volatile fraction commonly found in the fuel to avoid fractioning the fuel and changing the fuel composition. However, volatile fractions that would typically boil off during a standard day should be excluded when determining the maximum allowable temperature of the inert gas. In an embodiment, the inert gas is provided to the fuel stabilization chamber 30 at a temperature of less than or equal to about 25°C at sea level. However, it should be understood that the boiling point of the lightest volatile fraction, and therefore the maximum allowable temperature of the inert gas may vary with the altitude of the aircraft.

[0044] In an embodiment, the temperature of the inert gas may be thermally regulated, such as via a heat exchanger for example. An example of the implementation of such a heat exchanger is described in U.S. Patent Application Serial No. 15,639,587, filed on June 30, 3017, U.S. Patent Application Serial No. 14/969,398 filed on December 15, 2015, and U.S. Patent Application Serial No. 15/348,287 filed on November 10, 2016. Alternatively, the temperature of the inert gas provided to the fuel stabilization chamber 30 may be greater than the boiling point of the lightest volatile fraction commonly found in the fuel 34. In such embodiments, the fuel fractions that boil off locally may be recovered when they condense in the bulk fuel. Alternatively, escaped hydrocarbon fractions can be recovered by passing the ullage gases that contain fuel vapors through a reverse selective membrane as disclosed, for example, in U.S. Patent Application Serial No. 15/192,692, filed on June 24, 2016.

[0045] The temperature of the inert gas can be managed by bypassing cooling device 70 entirely or in part (not shown). For example, at altitude when fuel is exposed to cold temperatures over a protracted duration (a condition commonly referred to as "cold soak"), the temperature of the inert gas can be increased, such as beyond the boiling point of the lightest fractions for example, in order to transfer heat from the inert gases to the fuel 34. This action may help avoid problems associated with ice formation and with wax crystal formation in cold fuel. However, care must be taken to avoid excessively heating the fuel, which can lead to the evaporation and boiling of fuel species (fractional distillation). In an embodiment, the heat sink flow provided to a cooling device 70 is restricted or entirely blocked in order to regulate the temperature of inert gas.

[0046] Alternatively, or in addition, it may be desirable to thermally condition or regulate the fuel that enters the inner volume 32 of fuel stabilization chamber 30. As shown in the non-limiting embodiment of FIG. 6, the fuel within the fuel line 36 is arranged in a heat transfer relationship with another fluid flow within a heat exchanger 80 arranged before being released into the inner volume 32. The temperature of the fuel may be regulated to influence the deoxygenation process. Warmer fuel has improved kinetics for mass transport compared to a colder fuel which holds less dissolved oxygen. Several heat sources and heat sinks are available on the aircraft for regulating the temperature of the fuel before being interacting with an inert gas. Examples of such heat sources and sinks include, but are not limited to, engine oil, heated fuel, compressed air, ram air (when sufficiently cold), portions of the ECS, or dedicated equipment such as an air cycle machine for example.

[0047] Alternatively, or in addition, it may be desirable to thermally condition or regulate the fuel output from the inner volume 32. System 60 may employ a heat exchanger to establish a heat transfer relationship with another fluid located between fuel stabilization chamber 30 and engine E. In an embodiment, the system 60 may include a recuperating heat exchanger configured to adjust the temperature of the fuel 24 entering the fuel stabilization chamber 30 to a temperature of the fuel 34 output from the fuel stabilization chamber 30 to save energy. In addition, the fuel stabilization chamber or the fuel line 36 may be provisioned with heating elements, resistance coils, burners, catalytic oxidation units, thermoelectric coolers, etc, in order to regulate the temperature of the fuel 34.

[0048] Further, in some embodiments, it may be desirable to stabilize a fuel by removing the dissolved oxygen therefrom in multiple stages. With reference to FIG. 7, the system 60 for stabilizing a fuel 34 is operably coupled to both a first fuel stabilization chamber 30a and a second fuel stabilization chamber 30b. As shown, the inert gas from the inert gas device 62 is provided to the inner volume 32 of both fuel stabilization chamber 30a, 30b simultaneously. Further, the first fuel stabilization chamber 30a and the second fuel stabilization chamber 30b are arranged in series. As a result, at least a portion of the dissolved oxygen within the fuel 34a of the first fuel stabilization chamber 30a is removed before being provided to the interior volume 32b of the fuel stabilization chamber 30b. The additional fuel stabilization that occurs within the second fuel stabilization chamber 30b via the interaction between the inert gas and the liquid fuel 34b therein results in the removal of additional dissolved oxygen from the fuel 34b. Fuel 34b is then provided in response to a demand by an engine or thermal management system E operably coupled thereto. In an alternative embodiment, the passivating gases within the ullage 35b of the second fuel stabilization chamber 30b may be used as the inert gas for removing the oxygen from the fuel 34a within the inner volume 32a of the first fuel stabilization chamber 30a by transporting with a prime mover such as a blower fan, etc. (not shown).

[0049] Inclusion of an inert gas device 62 on board an aircraft 2, enables fuel stabilization, thereby allowing fuel 34 within a fuel stabilization chamber 30 associated with a fuel tank 20 to absorb more heat than currently possible without deposit formation. Further, because the inert gas passivates the ullage of the fuel stabilization chamber 30, a separate fuel tank inerting system is not necessary. In addition, the system 60 not only removes water from the fuel, but also addresses known problems of bacterial growth, freezing, and fuel degradation of conventional systems. Although the system 60 is illustrated and described herein with respect to an aircraft, it should be understood that such a system may be adapted for use in a variety of applications including motor vehicle and marine applications for example.

[0050] While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the scope of the invention as defined by the claims. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.


Claims

1. A system for generating inert gas comprising:

a fuel tank (20) including an inner storage volume (24) containing a fuel;

a fuel stabilization chamber (30) having an inner volume (32), said inner volume of said fuel stabilization chamber being arranged in fluid communication with said inner storage volume such that said fuel is movable from said inner storage volume to said inner volume;

an inert gas device (62) operably coupled to the inner volume of said fuel stabilization chamber, wherein inert gas output from said inert gas device interacts with a fuel in said inner volume to remove dissolved oxygen from said fuel in said inner volume.


 
2. The system of claim 1, wherein said fuel stabilization chamber (30) is separate from said fuel tank (20).
 
3. The system of claim 1, wherein said fuel stabilization chamber is integrally formed with said fuel tank, and said fuel in said inner storage volume and said fuel in said inner volume are separated by a dividing wall.
 
4. The system of any preceding claim, further comprising a component fluidly coupled to said inner volume, wherein said inert gas device (62) provides said inert gas to said fuel in said inner volume in response to a demand of said component.
 
5. The system of any preceding claim, wherein said inert gas device (62) converts pressurized air into an oxygen enriched air flow and an inert gas enriched air flow, said inert gas enriched air flow being provided to said inner volume as said inert gas.
 
6. The system of any preceding claim, wherein said inert gas device includes a stored supply of inert gas.
 
7. The system of any preceding claim, wherein said interaction of said inert gas with said fuel in said inner volume performs a fuel tank inerting operation.
 
8. The system of claim 1 further comprising:

a first pump (42) for moving said fuel from said inner storage volume to said inner volume; and

a second pump (44) for providing said fuel from said inner volume to a downstream component.


 
9. The system of any preceding claim, wherein said temperature of said inert gas provided to said fuel is less than or equal to 80°C at sea level.
 
10. The system of any preceding claim, further comprising a conduit (76) extending from said inert gas device (62) into said inner volume, said conduit being operable to expel said inert gas therefrom as a plurality of bubbles.
 
11. A method of eliminating dissolved oxygen from fuel to discourage the formation of solid deposits, comprising:

providing a portion of fuel from an inner storage volume of a fuel tank to an inner volume of a fuel stabilization chamber;

providing a supply of inert gas to said inner volume of said fuel stabilization chamber; and

interacting said inert gas and said portion of fuel in said inner volume to remove dissolved oxygen from said fuel in said inner volume.


 
12. The method according to claim 11, further comprising supplying said fuel in said inner volume to a component in response to a demand by said component after said interaction.
 
13. The method according to claim 11, wherein said inert gas-enriched air is supplied to said fuel at a temperature less than or equal to about 80°C at sea level.
 
14. The method according to claim 11, further comprising:

providing pressurized air to said inert gas device; and

separating said pressurized air into an oxygen-enriched air and an inert-gas enriched air, said inert-gas enriched air being provided to said inner volume as said supply of inert gas.


 
15. The method according to claim 11, wherein said portion of fuel is provided from said inner storage volume to said an inner volume in response to a demand from a component operably coupled to said fuel stabilization chamber.
 




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Cited references

REFERENCES CITED IN THE DESCRIPTION



This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

Patent documents cited in the description