Fuel oxygen reduction unit

Abstract

A fuel oxygen reduction unit is provided for reducing the oxygen content of a liquid fuel stream flowing to an engine. The fuel oxygen reduction unit comprises: a stripping gas supply line for providing a stream of stripping gas; a contactor defining a liquid fuel inlet, a stripping gas inlet and a fuel / gas mixture outlet, a stripping gas supply line in gas flow communication with the stripping gas inlet; means for regulating a stream of stripping gas through the stripping gas supply line; and a controller operable with the means for regulating the stream of stripping gas through the stripping gas supply line to regulate the stream of stripping gas through the stripping gas supply line in response to an engine operability parameter.

Description

[0001] This application is a divisional application of the invention patent application with application number 202210430248.6 filed on April 22, 2022 and invention name “Fuel Oxygen Reduction Unit”. Technical Field

[0002] The present disclosure relates to a fuel oxygen reduction unit, such as a fuel oxygen reduction unit for an aircraft gas turbine engine, and a method of operating the same. Background Art

[0003] A typical aircraft propulsion system includes one or more gas turbine engines. A gas turbine engine typically comprises a turbine, which includes a compressor section, a combustion section, a turbine section, and an exhaust section arranged in series. In operation, air is supplied to the inlet of the compressor section, where one or more axial compressors gradually compress the air until it reaches the combustion section. Fuel is mixed with the compressed air and combusted within the combustion section to provide combustion gases. From the combustion section, the combustion gases are transported to the turbine section. The combustion gases flowing through the turbine section drive the turbine section and are then directed through the exhaust section, for example, to the atmosphere.

[0004] Certain operations and systems of gas turbine engines and aircraft can generate relatively large amounts of heat. Fuel has been identified as an effective heat sink, absorbing at least some of this heat during operation, due at least in part to its heat capacity and the increased efficiency in combustion operations that can result from burning higher temperature fuels.

[0005] However, heating the fuel without properly conditioning it can cause it to "coke," or form solid particles that can clog certain parts of the fuel system, such as fuel nozzles. Reducing the amount of oxygen in the fuel can effectively reduce the likelihood of fuel coking beyond unacceptable levels. Fuel oxygen conversion systems have been proposed for this purpose.

[0006] Certain fuel oxygen conversion systems mix the fuel with a stripping gas that has a relatively low oxygen content.The inventors of the present disclosure have discovered that improvements in this aspect of fuel oxygen conversion systems would be useful. Summary of the Invention

[0007] Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

[0008] In one exemplary embodiment of the present disclosure, a fuel oxygen reduction unit is provided for reducing the oxygen content of a liquid fuel flow to an engine. The fuel oxygen reduction unit includes: a stripping gas supply line for providing a stripping gas flow; a contactor defining a liquid fuel inlet, a stripping gas inlet, and a fuel / gas mixture outlet, the stripping gas supply line being in gaseous communication with the stripping gas inlet; a device for regulating the flow of stripping gas through the stripping gas supply line; and a controller operable in conjunction with the device for regulating the flow of stripping gas through the stripping gas supply line to regulate the flow of stripping gas through the stripping gas supply line in response to an engine operability parameter.

[0009] These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims.The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] A full and effective disclosure of the invention, including the best mode thereof, to one of ordinary skill in the art is set forth in the specification with reference to the accompanying drawings, in which:

[0011] Figure 1 is a schematic cross-sectional view of a gas turbine engine according to an exemplary embodiment of the present disclosure.

[0012] Figure 2 is a schematic diagram of a fuel oxygen reduction unit according to an exemplary embodiment of the present disclosure.

[0013] Figure 3 is a flow chart of a method for operating a fuel oxygen reduction unit. DETAILED DESCRIPTION

[0014] Reference will now be made in detail to the present embodiments of the present invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. The same or similar reference numerals in the drawings and the description have been used to refer to the same or similar parts of the invention.

[0015] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations. Furthermore, all embodiments described herein are to be considered exemplary unless expressly stated otherwise.

[0016] As used herein, the terms “first,” “second,” and “third” may be used interchangeably to distinguish one component from another, and are not intended to indicate the position or importance of each component.

[0017] The terms "front" and "rear" refer to relative positions within a gas turbine engine or vehicle and refer to the normal operating attitude of the gas turbine engine or vehicle. For example, for a gas turbine engine, front refers to a position closer to the engine inlet, while rear refers to a position closer to the engine nozzle or exhaust.

[0018] The terms "upstream" and "downstream" refer to relative directions of fluid flow in a fluid path. For example, "upstream" refers to the direction from which the fluid is flowing, and "downstream" refers to the direction to which the fluid is flowing.

[0019] The terms “coupled,” “fixed,” “attached,” and the like refer to both direct coupling, fixing, or attachment, as well as indirect coupling, fixing, or attachment through one or more intermediate components or features, unless otherwise indicated herein.

[0020] The singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise.

[0021] Approximate language, as used throughout the specification and claims, is applied to modify any quantitative expression that can be permitted to vary without resulting in a change in the basic function to which it is related. Therefore, a value modified by one or more terms such as "about," "approximately," and "substantially" is not limited to the precise value specified. In at least some cases, approximate language may correspond to the precision of an instrument used to measure the value, or the precision of a method or machine used to construct or manufacture a component and / or system. For example, approximate language may refer to being within 1%, 2%, 4%, 10%, 15%, or 20%. These approximate margins may apply to a single value, to one or both endpoints of a numerical range, and / or to the margin of a range between the endpoints.

[0022] Here and throughout the specification and claims, range limitations are combined and interchanged, and unless context or language indicates otherwise, such ranges are identified and include all sub-ranges contained therein. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other.

[0023] The present disclosure generally relates to a fuel oxygen reduction unit that is configured to receive a fuel stream from, for example, a fuel tank, reduce the oxygen content of the fuel stream (producing a deoxygenated fuel stream), and provide the deoxygenated fuel stream to a gas turbine engine for combustion. Prior to combustion, the deoxygenated fuel stream can serve as a heat sink for various engine and / or aircraft systems. The amount of heat transferred to the deoxygenated fuel stream can vary based on one or more engine parameters. For example, during high power conditions (e.g., takeoff or climb), a relatively large amount of heat may need to be transferred to the fuel, while during low power conditions (e.g., taxiing or descent), a relatively small amount of heat may need to be transferred to the fuel. The oxygen content of the deoxygenated fuel stream can determine how much heat the deoxygenated fuel stream can accept before, for example, coking.

[0024] The inventors of the present disclosure have recognized that for certain fuel oxygen reduction units that utilize a contactor and a separator to mix a stripping gas and a liquid fuel and subsequently separate the stripping gas and liquid fuel mixture, the amount of stripping gas used relative to the amount of liquid fuel directly impacts the final oxygen content of the deoxygenated fuel stream, as well as the temperature increase of the liquid fuel stream flowing through the fuel oxygen reduction unit. Generally, the deoxygenated fuel stream is preferably at a lower temperature to promote more efficient heat transfer. Accordingly, the inventors of the present disclosure have discovered that controlling the mass flow rate of the stripping gas stream relative to the mass flow rate of the liquid fuel stream provided to the fuel oxygen reduction unit can allow the system to achieve a desired amount of oxygen reduction in the liquid fuel stream while minimizing the temperature increase in the liquid fuel stream.

[0025] For example, in at least some exemplary aspects, the fuel oxygen reduction unit can include a device for regulating a stripping gas flow through a stripping gas supply line (e.g., a variable speed gas boost pump, a valve, a vent line, or a recirculation line) and a controller operable with the device for regulating a stripping gas flow through the stripping gas supply line to regulate the stripping gas flow through the stripping gas supply line in response to an engine operability parameter. The engine operability parameter can be any suitable parameter indicative of a desired oxygen content of the deoxygenated fuel stream to be provided to the engine.

[0026] In this manner, the controller may operate the fuel oxygen reduction unit at an efficiency less than 100% in response to an engine operability parameter indicating that a higher oxygen content in the deoxygenated fuel stream is acceptable to provide a desired amount of oxygen reduction in the deoxygenated fuel stream while minimizing a temperature increase in the liquid fuel stream flowing through the fuel oxygen reduction unit.

[0027] Referring now to the drawings, in which like numerals represent like elements throughout, Figure 1A schematic cross-sectional view of an engine according to an exemplary embodiment of the present disclosure is provided. The engine can be incorporated into a vehicle. For example, the engine can be an aircraft engine incorporated into an aircraft. However, alternatively, the engine can be any other suitable type of engine for any other suitable aircraft or vehicle.

[0028] For the depicted embodiment, the engine is configured as a high-bypass turbofan engine 100. Figure 1 As shown, the turbofan engine 100 defines an axial direction A (extending parallel to a longitudinal centerline 101 for reference), a radial direction R, and a circumferential direction (extending about the axial direction A; Figure 1 Generally, the turbofan 100 includes a fan section 102 and a turbine 104 arranged downstream of the fan section 102 .

[0029] The depicted exemplary turbomachine 104 generally includes a substantially tubular outer casing 106 defining an annular inlet 108. Outer casing 106 encloses, in series flow relationship, a compressor section comprising a boost or low-pressure (LP) compressor 110 and a high-pressure (HP) compressor 112; a combustion section 114; a turbine section comprising a high-pressure (HP) turbine 116 and a low-pressure (LP) turbine 118; and an ejection nozzle section 120. The compressor section, combustion section 114, and turbine section together at least partially define a core air flow path 121 extending from annular inlet 108 to ejection nozzle section 120. The turbofan engine further includes one or more drive shafts. More specifically, the turbofan engine includes a high-pressure (HP) shaft or spool 122 drivingly connecting HP turbine 116 to HP compressor 112, and a low-pressure (LP) shaft or spool 124 drivingly connecting LP turbine 118 to LP compressor 110.

[0030] For the depicted embodiment, fan section 102 includes a fan 126 having a plurality of fan blades 128 coupled to a disk 130 in a spaced-apart manner. Fan blades 128 and disk 130 are rotatable together about longitudinal axis 201 via LP shaft 124. Disk 130 is covered by a rotatable forward hub 132 having an aerodynamic profile to facilitate airflow through the plurality of fan blades 128. Additionally, an annular fan casing or outer nacelle 134 is provided that circumferentially surrounds fan 126 and / or at least a portion of turbine 104. Nacelle 134 is supported relative to turbine 104 by a plurality of circumferentially spaced outlet guide vanes 136. A downstream section 138 of nacelle 134 extends over the exterior of turbine 104 to define a bypass airflow passage 140 therebetween.

[0031] Still refer to Figure 1, the turbofan engine 100 further includes an accessory gearbox 142, a fuel oxygen reduction unit 144, and a fuel delivery system 146. For the embodiment shown, the accessory gearbox 142 is located within the cowling / outer casing 106 of the turbine 104. Additionally, it should be understood that although Figure 1 14. Although not schematically depicted, the accessory gearbox 142 may be mechanically coupled to and rotatable with one or more shafts or spools of the turbine 104. For example, in at least certain exemplary embodiments, the accessory gearbox 142 may be mechanically coupled to and rotatable with the HP shaft 122. Additionally, for the illustrated embodiment, a fuel oxygen reduction unit 144 is coupled to an accessory or otherwise rotatable with the accessory gearbox 142. In this manner, it should be understood that the exemplary fuel oxygen reduction unit 144 is driven by the accessory gearbox 142. Notably, as used herein, the term "fuel oxygen reduction unit" generally refers to a device capable of reducing the free oxygen content of a fuel.

[0032] Furthermore, the fuel delivery system 146 generally includes a fuel source 148, such as a fuel tank, and one or more fuel lines 150. The one or more fuel lines 150 provide fuel flow through the fuel delivery system 146 to the combustion section 114 of the turbine 104 of the turbofan engine 100. Figure 2 A more detailed schematic diagram of a fuel delivery system according to an exemplary embodiment of the present disclosure is provided.

[0033] Furthermore, it should be understood that although for the depicted embodiment, the turbofan engine 100 includes an accessory gearbox 142 and a fuel oxygen reduction unit 144 that are positioned within the turbine 104, i.e., within the outer casing 106 of the turbine 104, in other embodiments, the accessory gearbox 142 and / or the fuel oxygen reduction unit 144 may be positioned at any other suitable location. For example, Figure 1 , in other embodiments, the accessory gearbox 142 and / or the fuel oxygen reduction unit 144 may be located within the nacelle 134 of the turbofan engine 100. Alternatively, in other embodiments, the accessory gearbox 142 may be located with the turbofan engine 100, and the fuel oxygen reduction unit 144 may be located remotely from the turbofan engine 100, such as near or within a fuel tank 148 of a fuel delivery system 146. Furthermore, in other embodiments, the fuel oxygen reduction unit 144 may additionally or alternatively be driven by other suitable power sources, such as an electric motor, a hydraulic motor, or a separate mechanical coupling to the HP or LP shaft. For example, when the accessory gearbox 142 is driven by an electric motor, the electric motor may be configured to receive power from an electric motor / generator driven by the engine, such as the engine's LP or HP system.

[0034] Now refer to Figure 2 , provides a schematic diagram of a fuel oxygen reduction unit 200 for a gas turbine engine according to exemplary aspects of the present disclosure. In at least some exemplary embodiments, Figure 2 The exemplary fuel oxygen reduction unit 200 depicted in FIG. 2 may be incorporated into, for example, the fuel oxygen reduction unit 200 described above with reference to FIG. Figure 1 The exemplary engine 100 described (e.g., may be in Figure 1 The fuel oxygen reduction unit 144 depicted in and described above).

[0035] Alternatively, fuel oxygen reduction unit 200 may be incorporated into any other suitable exemplary engine, fuel delivery assembly for any suitable exemplary engine, or the like.

[0036] From the discussion in this article, we can understand that Figure 2 The fuel oxygen reduction unit 200 generally includes a contactor 202 and a fuel / gas separator 204. The depicted exemplary contactor 202 can be configured in any suitable manner to effectively mix the received gas and liquid streams, as described below. For example, in certain embodiments, the contactor 202 can be a mechanically driven contactor (e.g., having paddles for mixing the received streams), or can be a passive contactor for mixing the received streams, at least in part using the pressure and / or flow rate of the received streams.

[0037] Furthermore, the exemplary fuel oxygen reduction unit 200 includes a stripping gas supply line 205 for providing a stripping gas stream 220, and more specifically, for providing the stripping gas stream 220 to the contactor 202. For the illustrated embodiment, the exemplary fuel oxygen reduction unit 200 more specifically includes a plurality of stripping gas supply lines 205 arranged in series to together at least partially define a recycle gas flow path 206 extending from the fuel / gas separator 204 to the contactor 202. In certain exemplary embodiments, in addition to the plurality of stripping gas supply lines 205 and structures or components within the recycle gas flow path 206, the recycle gas flow path 206 may be formed by any combination of one or more conduits, tubes, pipes, etc.

[0038] It should be understood that the term "stripping gas" is used herein as a convenient term to refer to a gas generally capable of performing the functions described herein. The stripping gas 220 flowing through the stripping gas flow path / circulating gas flow path 206 can be the actual stripping gas used to strip oxygen from the fuel within the contactor, or it can be a sparging gas that is bubbled through the liquid fuel to reduce the oxygen content of such fuel. For example, as will be discussed in more detail below, the stripping gas 220 can be an inert gas, such as nitrogen or carbon dioxide (CO2), a mixture of inert gases, or some other gas or gas mixture having a relatively low oxygen content.

[0039] In addition, for Figure 2 , the fuel oxygen reduction unit 200 further includes a gas booster pump 208, a gas oxygen reduction unit 210 (which is a catalyst for the illustrated embodiment), and a preheater 212. For the illustrated embodiment, the gas booster pump 208, the gas oxygen reduction unit 210, and the preheater 212 are each arranged in a series flow arrangement within the recycle gas flow path 206. The gas booster pump 208 is generally operable to increase the pressure of a stripping gas stream 220 through the stripping gas supply line 205, and more specifically, through the recycle gas flow path 206. The operation of the gas booster pump 208, the gas oxygen reduction unit 210, and the preheater 212 will be further explained below.

[0040] Still refer to Figure 2 In the exemplary embodiment, it will be appreciated that the fuel / gas separator 204 generally defines a gas outlet 214, a liquid fuel outlet 216, and an inlet 218, and that the contactor 202 generally defines a liquid fuel inlet 232, a stripping gas inlet 234, and a fuel / gas mixture outlet 236. It will also be appreciated that the depicted exemplary fuel oxygen reduction unit 200 may be operated with a fuel delivery system 146, such as a fuel delivery system 146 of a gas turbine engine that includes the fuel oxygen reduction unit 200 (see, e.g., FIG. 1 ). Figure 1 The exemplary fuel delivery system 146 generally includes a plurality of fuel lines, specifically an inlet fuel line 222 and an outlet fuel line 224. The inlet fuel line 222 is fluidly connected to a liquid fuel inlet 232 of the contactor 202 for providing a liquid fuel stream 226 to the contactor 202 (e.g., from a fuel source, such as a fuel tank), and the outlet fuel line 224 is fluidly connected to a liquid fuel outlet 216 of the fuel / gas separator 204 for receiving the deoxygenated liquid fuel stream 226 and providing this liquid fuel stream to, for example, one or more engines.

[0041] Furthermore, during typical operation, a stripping gas stream 220 flows from the gas outlet 214 of the fuel / gas separator 204 through the recycle gas flow path 206 to the stripping gas inlet 234 of the contactor 202. More specifically, during typical operation, the stripping gas 220 flows from the gas outlet 214 of the fuel / gas separator 204, passes through the preheater 212 (configured to add thermal energy to the gas flowing therethrough), passes through the gas oxygen reduction unit 210, and to / through the gas booster pump 208, where the pressure of the stripping gas 220 is increased to provide the stripping gas stream 220 through the recycle gas flow path 206. The relatively high pressure stripping gas 220 (i.e., relative to the pressure upstream of the booster pump 208 and optionally the fuel entering the contactor 202) is then provided to the stripping gas inlet 234 of the contactor 202, where the stripping gas 220 is mixed with the liquid fuel stream 226 from the inlet fuel line 222 to produce the fuel / gas mixture 228. The fuel / gas mixture 228 produced within the contactor 202 is provided to the inlet 218 of the fuel / gas separator 204 through the fuel / gas mixture outlet 236 of the contactor 202. Within the fuel / gas separator 204, the fuel / gas mixture 228 can be separated back into a liquid fuel stream 226 and a stripping gas stream 220.

[0042] However, it should be understood that Figure 2 The arrangement depicted in FIG2 is provided as an example only, and in other embodiments, the fuel oxygen reduction unit 200 may alternatively be arranged in any other suitable manner. For example, the fuel oxygen reduction unit 200 may include a gas booster pump 208 immediately downstream of the separator 204 and upstream of the preheater 212. In this manner, the gas booster pump 208 may operate with a lower temperature gas flow, which may reduce wear on the gas booster pump 208.

[0043] In general, it should be understood that during operation of the fuel oxygen reduction unit 200, the liquid fuel 226 provided to the contactor 202 via the inlet fuel line 222 can have a relatively high oxygen content. The stripping gas 220 provided to the contactor 202 can have a relatively low oxygen content or other specific chemical structure. Within the contactor 202, the liquid fuel 226 mixes with the stripping gas 220 to produce a fuel / gas mixture 228. As a result of this mixing, physical exchange can occur, whereby at least a portion of the oxygen in the fuel 226 is transferred to the stripping gas 220, resulting in a fuel component of the mixture 228 having a relatively low oxygen content (compared to the fuel 226 provided via the inlet fuel line 222) and a stripping gas component of the mixture 228 having a relatively high oxygen content (compared to the stripping gas 220 provided to the contactor 202 via the recycle gas flow path 206). The fuel / gas separator 204 separates the stripping gas 220, which has a higher oxygen content, from the fuel 226, which has a lower oxygen content.

[0044] Furthermore, it should be appreciated that the liquid fuel 226 provided to the liquid fuel outlet 216, having interacted with the stripping gas 220, can have a relatively low oxygen content, thereby allowing for the addition of relatively high heat thereto with a reduced risk of fuel coking (i.e., chemically reacting to form solid particles that can clog or damage components within the fuel flow path). For example, in at least some exemplary aspects, the oxygen content of the fuel 226 provided to the liquid fuel outlet 216 can be less than about five (5) parts per million ("ppm"), such as less than about three (3) ppm, such as less than about two (2) ppm, such as less than about one (1) ppm, such as less than about 0.5 ppm.

[0045] Furthermore, as will be appreciated, the depicted exemplary fuel oxygen reduction unit 200 recycles and reuses the stripping gas 220 (i.e., the stripping gas 220 operates in a substantially closed loop). However, the stripping gas 220 exiting the fuel / gas separator 204 has already interacted with the liquid fuel 226 and may have a relatively high oxygen content. Therefore, in order to reuse the stripping gas 220, it may be necessary to reduce the oxygen content of the stripping gas 220 at the outlet 214 of the fuel / gas separator 204. For the depicted embodiment, and as described above, the stripping gas 220 flows through the preheater 212, through the gas oxygen reduction unit 210, where the oxygen content of the stripping gas 220 is reduced, and through the gas booster pump 208. In certain exemplary embodiments, the gas oxygen reduction unit 210 may be configured as a catalyst. With such a configuration, the relatively oxygen-rich stripping gas 220 reacts within the catalyst to reduce its oxygen content.

[0046] However, it should be understood that the gas oxygen reduction unit 210 can be configured in any suitable manner to perform these functions (i.e., remove oxygen from the recycled stripping gas 220). For example, in certain embodiments, the gas oxygen reduction unit 210 can be configured to react oxygen present in the oxygen-rich stripping gas 220 with fuel vapor to reduce the total level of free oxygen in the stripping gas 220. However, in other embodiments, the gas oxygen reduction unit 210 can additionally or alternatively include a geometry of catalytic components through which the relatively oxygen-rich stripping gas 220 flows to reduce its oxygen content. In one or more of these configurations, a byproduct, such as water, can be produced, which can be transported away from the gas oxygen reduction unit 210 via a pipeline. Additionally or alternatively, any other suitable configuration can be provided to reduce the oxygen content of the stripping gas 220.

[0047] However, it is noted that in other embodiments, any other suitable gas oxygen reduction unit may be provided to reduce the oxygen content of the stripping gas 220. For example, in addition or as an alternative, the gas oxygen reduction unit may utilize a membrane oxygen reduction system, a combustion reduction system, a plasma reduction system, etc.

[0048] In one or more of these embodiments, the gas deoxygenation unit / gas deoxygenation unit 210 can be configured to reduce the oxygen content of the stripping gas 220 to less than about five percent (5%) by mass oxygen (O2), such as less than about two percent (2%) by mass oxygen (O2), such as less than about one percent (1%) by mass oxygen (O2).

[0049] The resulting relatively low oxygen content gas is then provided through the remainder of the recycle gas flow path 206 and returned to the contactor 202 so that the cycle can be repeated. In this manner, it will be understood that the stripping gas 220 can be any suitable gas capable of undergoing the chemical transformation described above. For example, the stripping gas can be air from an air source 260. The air source 260 can be, for example, the core air flow path of a gas turbine engine including the fuel oxygen reduction unit 200 (e.g., compressed air discharged from the HP compressor 112; see Figure 1 ). However, in other embodiments, the stripping gas may alternatively be any other suitable gas, such as an inert gas (e.g., nitrogen or carbon dioxide (CO2)), an inert gas mixture, or some other gas or gas mixture having a relatively low oxygen content. In this manner, it should be understood that in certain exemplary embodiments, the air from air source 260 may be deoxygenated air (or, more precisely, deoxygenated gas), or may be a gas defining a normal or relatively high oxygen content, which oxygen content is reduced by gas deoxygenation unit 210.

[0050] As also shown, valve 261 provides flow communication between the gas source 260 and the recycle gas flow path 206. Valve 261 can control the mass flow rate of air to the recycle gas flow path 206. In this way, valve 261 can help regulate the mass flow rate of the stripping gas 220 flowing through the stripping gas flow path / recycle gas flow path 206.

[0051] However, it should also be understood that the exemplary fuel oxygen reduction unit 200 described above is provided as an example only. In other embodiments, the fuel oxygen reduction unit 200 can be configured in any other suitable manner. For example, in other embodiments, the stripping gas 220 may not flow through the recycle gas flow path 206. Instead, the fuel oxygen reduction unit 200 may include an open-loop stripping gas flow path that is in communication with a suitable stripping gas source 260 (e.g., a bleed air source) and further configured to exhaust air from the fuel / gas separator 204, for example, to the atmosphere downstream of the fuel / gas separator 204.

[0052] Still refer to Figure 2It should be understood that the fuel oxygen reduction unit 200 further includes a means for regulating the flow of stripping gas 220 through the stripping gas supply line 205 and a controller 246 operable with the means for regulating the flow of stripping gas 220 through the stripping gas supply line 205. As will be explained in greater detail below, the controller 246 is operable with the means for regulating the flow of stripping gas 220 through the stripping gas supply line 205 to regulate the flow of stripping gas 220 through the stripping gas supply line 205 in response to engine operability parameters.

[0053] For the embodiment shown, the device for regulating the stripping gas flow 220 through the stripping gas supply line 205 is a gas booster pump 208. More specifically, for the embodiment shown, the gas booster pump 208 is configured as a variable speed gas booster pump. For example, in the exemplary embodiment shown, the gas booster pump 208 is configured as a rotary gas pump and is coupled to and driven by an electric power source 209, which can be a variable speed motor. In this way, the gas booster pump 208 can increase or decrease its speed to increase or decrease the stripping gas flow 220 through the stripping gas supply line 205 (i.e., increase or decrease the mass flow rate of the stripping gas 220 through the stripping gas supply line 205 to the contactor 202).

[0054] Alternatively, however, the variable speed gas boost pump 208 can be configured in any other suitable manner and can be coupled to and driven by any other suitable electric power source. For example, the gas boost pump 208 can be coupled to a fixed speed power source or a power source that cannot change its speed based on the needs of the fuel oxygen reduction unit 200 (e.g., an accessory gearbox). With this configuration, the device can further include one or more features for varying the speed of the gas boost pump 208 relative to the power source 209. For example, the gas boost pump 208 can be coupled to the power source 209 via a variable speed transmission or the like.

[0055] However, it should be understood that the means for regulating the flow of stripping gas 220 through the stripping gas supply line 205 may additionally or alternatively include other suitable components. For example, in the illustrated embodiment, the means for regulating the flow of stripping gas 220 through the stripping gas supply line 205 may additionally or alternatively include a fluid control valve 238 configured to vary the amount of stripping gas 220 flowing through the stripping gas supply line 205 (i.e., vary the mass flow rate of the stripping gas 220 flowing through the stripping gas supply line 205). For the illustrated embodiment, the fluid control valve 238 is located upstream of the gas booster pump 208, more specifically, upstream of the gas booster pump 208 and downstream of the gas deoxygenation unit 210, proximate the gas booster pump 208 relative to the gas deoxygenation unit 210.

[0056] However, if Figure 2 As shown by the dashed line in FIG, in other embodiments, the fluid control valve 238 may additionally or alternatively be located downstream of the gas booster pump 208.

[0057] The fluid control valve 238 may be any suitable variable throughput valve capable of varying the stripping gas flow 220 through the stripping gas supply line 205 (i.e., capable of varying the mass flow rate of the stripping gas flow 220 through the stripping gas supply line 205). For example, the fluid control valve 238 may be configured as a ball valve, a butterfly valve, a throttle valve, a diaphragm, a piston valve, a plug valve, a solenoid valve, a slide valve, a pressure reducing valve, or the like.

[0058] However, it should be understood that in other exemplary embodiments, any other suitable means for regulating the stripping gas flow 220 through the stripping gas supply line 205 may be provided. For example, in other embodiments, the means for regulating the stripping gas flow 220 through the stripping gas supply line 205 may include a recirculation conduit in flow communication with the stripping gas supply line 205 via a three-way valve configured to withdraw a portion of the stripping gas flow 220 through the stripping gas supply line 205 at a location upstream of the contactor 202 and provide the portion of the stripping gas 220 to the recycle gas flow path 206 at a location downstream of the separator 204 and, for example, upstream of the gas deoxygenation unit 210. Additionally or alternatively, the means for regulating the stripping gas flow 220 through the stripping gas supply line 205 may include a vent passage in flow communication with the stripping gas supply line 205 through a three-way vent valve that vents a portion of the stripping gas flow 220 through the stripping gas supply line 205 to, for example, the atmosphere, to regulate the stripping gas flow 220 through the stripping gas supply line 205. Other suitable means are also contemplated.

[0059] Furthermore, it should also be understood that for the illustrated embodiment, the means for regulating the stripping gas flow 220 through the stripping gas supply line 205 is generally located upstream of the contactor 202 and downstream of the gas deoxygenation unit 210. However, in other embodiments, the means for regulating the stripping gas flow 220 through the stripping gas supply line 205 may additionally or alternatively be located upstream of the gas deoxygenation unit and downstream of the separator 204, or alternatively, for an open-loop configuration, may be located at any other suitable location upstream of the contactor 202.

[0060] Still refer to Figure 2As briefly mentioned above, the exemplary fuel oxygen reduction unit 200 further includes a controller 246 operable in conjunction with the means for regulating the flow of stripping gas 220 through the stripping gas supply line 205 to regulate the flow of stripping gas 220 through the stripping gas supply line 205 in response to engine operability parameters.

[0061] More specifically, it will be appreciated that the controller 246 can be configured to ensure that the oxygen content of the deoxygenated liquid fuel stream 226 provided to the engine from the fuel oxygen reduction unit 200 is sufficiently low to accommodate the desired amount of heat transfer to the deoxygenated liquid fuel stream 226 prior to combustion. The controller 246 can accomplish this by varying the stripping gas stream 220 provided to the contactor 202 using a device for regulating the stripping gas stream 220 through the stripping gas supply line 205. Generally, the higher the ratio of stripping gas 220 to liquid fuel 226 provided to the contactor 202, the lower the resulting oxygen content within the liquid fuel stream 226 from the fuel oxygen reduction unit 200.

[0062] The controller 246 may determine the amount of stripping gas 220 required to provide a desired amount of oxygen reduction to the liquid fuel flow 226 based at least in part on the engine operability parameters.

[0063] The engine operability parameter is generally any parameter that indicates a desired oxygen content of the liquid fuel flow 226 from the fuel oxygen reduction unit 200 to the engine (e.g., an oxygen content setpoint, a desired oxygen reduction amount for the liquid fuel flow 226, a temperature that the liquid fuel 226 is expected to reach or may need to be conditioned to). In this manner, it should be understood that the engine operability parameter may indicate a maximum temperature that the liquid fuel flow 226 from the fuel oxygen reduction unit 200 will reach (or is estimated to reach, or is required to be able to reach) at a location downstream of the fuel oxygen reduction unit 200 before being combusted by the engine. For example, the engine operability parameter may indicate a flight mode operating condition of the engine (e.g., an idle operating condition, a takeoff / climb operating condition, a cruise operating condition, a taxi operating condition) or a power output operating mode of the engine (e.g., a low power operating condition, a high power operating condition, a rated speed operating condition, etc.). Further, the engine operability parameter may indicate or otherwise take into account other factors that may affect the maximum temperature that the liquid fuel flow 226 from the fuel oxygen reduction unit 200 can reach (or is estimated to reach, or is required to have the ability to reach), such as ambient conditions (e.g., temperature, pressure), the temperature and / or operating mode of auxiliary systems of the gas turbine engine (e.g., the engine oil lubrication system), etc. Moreover, in other exemplary embodiments, the engine operability parameter may be a maximum allowable oxygen content of the liquid fuel flow 226, such as determined by the controller 246 based on, for example, one or more of the above-mentioned conditions.

[0064] However, it should be understood that the process of reducing the oxygen content of the liquid fuel stream 226 provided to the fuel oxygen reduction unit 200 may increase the temperature of the liquid fuel stream 226. Specifically, the stripping gas 220 may generally be at a relatively high temperature, for example, by way of the gas oxygen reduction unit 210 (which may be a catalyst or a burner) and the preheater 212, such that, by mixing the liquid fuel stream 226 with the stripping gas stream 220 within the contactor 202, the temperature of the deoxygenated liquid fuel stream 226 through the outlet fuel line 224 is higher than the temperature of the liquid fuel stream 226 through the inlet fuel line 222. Furthermore, the higher the ratio of stripping gas 220 to liquid fuel 226 provided to the contactor 202, the higher the temperature of the liquid fuel 226 is increased.

[0065] It will be appreciated that in order to allow the liquid fuel stream 226 provided to the engine via the outlet fuel line 224 to more efficiently receive heat prior to combustion, it may be desirable to minimize the amount of temperature increase of the liquid fuel stream 226 within the fuel oxygen reduction unit 200, e.g., from the inlet fuel line 222 to the outlet fuel line 224. In this manner, the controller 246 can be configured to regulate the stripping gas flow 220 via the stripping gas supply line 205 in response to engine operability parameters to provide the contactor 202 with precisely the amount of stripping gas 220 (or precisely the amount of stripping gas 220 plus some buffer) such that the fuel oxygen reduction unit 200 provides the desired amount of oxygen reduction to the liquid fuel stream 226 without unnecessarily increasing the temperature of the liquid fuel stream 226 in the process.

[0066] In at least some exemplary aspects, in order for the controller 246 to ensure that a desired amount of oxygen reduction of the liquid fuel flow 226 is achieved, the controller 246 can be configured to determine data indicative of an amount of oxygen reduction of the liquid fuel flow passing through the fuel oxygen reduction unit 200, such as data indicative of a current amount of oxygen reduction achieved by the fuel oxygen reduction unit 200. The data indicative of the amount of oxygen reduction can be data indicative of an oxygen content of the liquid fuel flow 226 from the fuel oxygen reduction unit 200, data indicative of a reduction in oxygen content in the liquid fuel flow 226 from the fuel oxygen reduction unit 200 (e.g., paired with data indicative of a known or estimated starting oxygen content of the liquid fuel 226), etc.

[0067] In at least some exemplary aspects, the controller 246 can be configured to determine data indicative of an amount of oxygen reduction of the liquid fuel flow through the fuel oxygen reduction unit 200 based on the mass flow rate of the stripping gas 220 and the mass flow rate of the liquid fuel 226 to the contactor 202. In this manner, the controller 246 can be configured to determine data indicative of the mass flow rate of the stripping gas flow 220 provided to the stripping gas inlet 234 of the contactor 202, the mass flow rate of the liquid fuel flow 226 provided to the liquid fuel inlet 232 of the contactor 202, or both. In certain exemplary embodiments, such as the depicted exemplary embodiment, it will be appreciated that the fuel oxygen reduction unit 200 further includes a gas inlet temperature sensor 240 for sensing data indicative of the temperature of the stripping gas stream 220 provided to the stripping gas inlet 234 of the contactor 202, a fuel inlet temperature sensor 242 for sensing data indicative of the temperature of the liquid fuel stream 226 provided to the fuel inlet 232 of the contactor 202, and an outlet temperature sensor 244 for sensing data indicative of the temperature of the fuel / gas mixture stream from the fuel / gas mixture outlet 236 of the contactor 202. The controller 246 can be configured to determine data indicative of the mass flow rate of the stripping gas stream 220 provided to the stripping gas inlet 234 based on the data indicative of the temperature of the stripping gas stream 220 provided to the stripping gas inlet 234, the data indicative of the temperature of the fuel / gas mixture stream from the fuel / gas mixture outlet 236, the data indicative of the temperature of the liquid fuel stream 226 provided to the liquid fuel inlet 232, or a combination thereof.

[0068] However, it should be understood that in other embodiments, the controller 246 can be configured to determine the mass flow rate of the stripping gas flow 220 through the stripping gas supply line 205 to the stripping gas inlet 234 of the contactor 202 in any other suitable manner. For example, in other exemplary embodiments, the gas inlet temperature sensor 240 can alternatively be configured as a flow sensor to sense data indicative of the mass flow rate of the stripping gas flow 220 provided to the stripping gas inlet 234 of the contactor 202. Additionally or alternatively, the controller 246 can be configured to determine data indicative of the amount of oxygen reduction of the liquid fuel flow through the fuel oxygen reduction unit 200 in any other suitable manner. For example, the controller 246 can determine data indicative of the amount of oxygen reduction of the liquid fuel flow through the fuel oxygen reduction unit 200 using a fuel oxygen sensor or a sensor configured to sense some other parameter indicative of the oxygen content of the fuel downstream of the fuel oxygen reduction unit 200.

[0069] In the depicted exemplary aspect, the controller 246 can be further configured to regulate the stripping gas flow 220 (e.g., the mass flow rate of the stripping gas 220 and / or the liquid fuel 226 ) through the stripping gas supply line 205 in response to data indicating an amount of oxygen reduction of the liquid fuel flow through the fuel oxygen reduction unit 200 .

[0070] In this manner, it will be appreciated that the controller 246 can be configured to increase or decrease the stripping gas flow 220 through the stripping gas supply line 205 in response to engine operability parameters and further in response to data indicative of an amount of oxygen reduction of the liquid fuel flow passing through the fuel oxygen reduction unit 200. In this manner, the fuel oxygen reduction unit 200 can provide a desired amount of oxygen reduction to the liquid fuel flow 226 provided to the fuel oxygen reduction unit 200 without increasing the temperature of such liquid fuel flow 226.

[0071] For example, the controller 246 can be configured to increase the stripping gas flow 220 through the stripping gas supply line 205 to the contactor 202 in response to an engine operability parameter indicating that a lower fuel oxygen content is desired (e.g., the liquid fuel flow 226 from the fuel oxygen reduction unit 200 will need to be acclimated to a relatively high temperature prior to combustion), and further can be configured to decrease the stripping gas flow 220 through the stripping gas supply line 205 to the contactor 202 in response to an engine operability parameter indicating that a higher fuel oxygen content is acceptable (e.g., the liquid fuel flow 226 from the fuel oxygen reduction unit 200 will only need to be acclimated to a relatively low temperature prior to combustion).

[0072] In this manner, the controller 246 may operate the fuel oxygen reduction unit 200 at less than 100% efficiency to provide a desired amount of oxygen reduction to the deoxygenated fuel stream 226 while minimizing a temperature increase of the liquid fuel stream 226 flowing through the fuel oxygen reduction unit 200 in response to engine operability parameters indicating that a higher oxygen content within the deoxygenated fuel stream 226 is acceptable.

[0073] For example, it will be appreciated that by regulating the stripping gas flow 220 to the stripping gas supply line 205, the controller 246 can effectively reduce the stripping gas flow 220 through the stripping gas supply line 205 to the contactor 202 by at least 10%, such as at least 15%, such as at least 25%, such as at least 35%, such as at least 45%, such as up to 90%, of the maximum amount (based on the stripping gas flow 220 not reduced by the device for regulating the stripping gas flow 220). This can allow the fuel oxygen reduction unit 200 to provide a desired amount of oxygen reduction (based on engine operability parameters and determined data indicative of the current oxygen reduction amount) to the liquid fuel flow 226 without unnecessarily heating the liquid fuel flow 226 passing through the fuel oxygen reduction unit 200.

[0074] By way of further example, it will be appreciated that by regulating the stripping gas flow 220 to the stripping gas supply line 205, the controller 246 can operate the fuel oxygen reduction unit 200 to provide a fuel oxygen content to the liquid fuel flow 226 exiting the fuel oxygen reduction unit 200 that is at least 10% higher than if the stripping gas flow 220 through the stripping gas supply line 205 to the contactor 202 were not restricted by the means for regulating the stripping gas flow 220. For example, the controller 246 can operate the fuel oxygen reduction unit 200 to provide a fuel oxygen content to the liquid fuel flow 226 exiting the fuel oxygen reduction unit 200 that is at least 20% higher, e.g., at least 30% higher, e.g., at least 40% higher, e.g., at least 50% higher, e.g., at least 100% higher, e.g., as much as 10,000% higher, than if the stripping gas flow 220 through the stripping gas supply line 205 to the contactor 202 were not restricted by the means for regulating the stripping gas flow 220. Similarly, this may allow the fuel oxygen reduction unit 200 to provide a desired amount of oxygen reduction to the liquid fuel flow 226 (based on engine operability parameters and determined data indicative of the current oxygen reduction amount) without unnecessarily heating the liquid fuel flow 226 passing through the fuel oxygen reduction unit 200 .

[0075] Particularly for the illustrated embodiment, controller 246 is configured as part of a control system. Controller 246 and the control system may be standalone controllers 246 and control systems, or alternatively, may be integrated into, for example, a controller for a gas turbine engine, a controller for an aircraft, or the like. The control system may further include, or be in operable communication with, the aforementioned sensors 240, 242, 244, as well as one or more sensors of the gas turbine engine, the aircraft, or both. The one or more sensors of the gas turbine engine, the aircraft, or both may provide data indicative of engine operability parameters. For example, the one or more sensors of the gas turbine engine, the aircraft, or both may include: one or more speed sensors configured to sense data indicative of the rotational speed of one or more shafts of the gas turbine engine; one or more temperature sensors configured to sense data indicative of temperatures at one or more locations within the gas turbine engine (e.g., compressor outlet temperature, turbine inlet temperature, combustor temperature, exhaust gas temperature), and the like.

[0076] The depicted exemplary controller 246 includes one or more processors 248 and one or more memory devices 250. The one or more processors 248 may include any suitable processing device, such as a microprocessor, a microcontroller 246, an integrated circuit, a logic device, and / or other suitable processing device. The one or more memory devices 250 may include one or more computer-readable media, including but not limited to non-transitory computer-readable media, RAM, ROM, a hard drive, a flash drive, and / or other memory devices.

[0077] The one or more memory devices 250 may store information accessible to the one or more processors 248, including computer-readable instructions 252 that may be executed by the one or more processors 248. The instructions 252 may be any set of instructions that, when executed by the one or more processors 248, cause the one or more processors 248 to perform operations. In some embodiments, the instructions 252 may be executed by the one or more processors 248 to cause the one or more processors 248 to perform operations, such as configuring any operations and functions of the computing system and / or controller 246, operations for operating the fuel oxygen reduction unit 200 as described herein (e.g., method 300), and / or any other operations or functions. The instructions 252 may be software written in any suitable programming language or may be implemented in hardware. Additionally and / or alternatively, the instructions 252 may be executed in logically and / or virtually separate threads on the processors 248. The memory device 250 may further store data accessible by the processors 248 (e.g., data from the sensors 240, 242, 244).

[0078] The depicted exemplary controller 246 also includes a network interface 254 for communicating with components of the fuel oxygen reduction unit 200 (e.g., via a network, or more specifically, for the illustrated embodiment, via a wireless communication network 256). The network interface 254 may include any suitable components for interfacing with one or more networks, including, for example, transmitters, receivers, ports, controllers, antennas, and / or other suitable components.

[0079] However, the inherent flexibility of computer-based systems and controller 246 allows for a wide variety of possible configurations, combinations, and divisions of tasks and functions between and within components. For example, the processes discussed herein can be implemented using a single computing device or multiple computing devices working in combination. Databases, memories, instructions, and applications can be implemented on a single system or distributed across multiple systems. Distributed components can operate serially or in parallel.

[0080] Now refer to Figure 3, a method 300 of operating a fuel oxygen reduction unit according to an exemplary aspect of the present disclosure is provided. The exemplary fuel oxygen reduction unit can be configured to provide a liquid fuel flow to an engine and, therefore, can be configured in a manner similar to one or more of the exemplary fuel oxygen reduction units described above. However, in other embodiments, the method 300 can be used to operate any other suitable fuel oxygen reduction unit.

[0081] Method 300 generally includes, at (302), receiving data indicative of an engine operability parameter of an engine. The engine operability parameter may indicate an amount of oxygen reduction desired in a liquid fuel stream. For example, the engine operability parameter may indicate a temperature that the liquid fuel stream from a fuel oxygen reduction unit will reach downstream of the fuel oxygen reduction unit. For example, in certain exemplary aspects, receiving data indicative of an engine operability parameter of an engine at (302) may include, at (304), determining a fuel oxygen set point for the liquid fuel stream flowing to the engine. The fuel oxygen set point may be an oxygen level within the liquid fuel stream required to accommodate a temperature that the liquid fuel stream is expected to reach prior to combustion, a desired amount of heat transfer to the liquid fuel stream, and the like. For example, the fuel oxygen set point may vary between five (5) parts per million ("ppm") and 0.5 ppm (or some other suitable range) based on the engine operability parameter.

[0082] Still refer to Figure 3 The exemplary method 300 further includes, at (306), regulating a stripping gas flow from a stripping gas supply line to the fuel oxygen reduction unit to a contactor of the fuel oxygen reduction unit in response to the data received at (302).

[0083] For the exemplary aspect shown, regulating the flow of stripping gas to the stripping gas supply line at (306) includes varying the speed of a variable speed gas pump in communication with the stripping gas supply line at (307).

[0084] However, it should be understood that in other exemplary aspects, the stripping gas flow to the stripping gas supply line can be regulated in any other suitable manner, such as by one or more valves, a recirculation conduit, a vent conduit, and the like.

[0085] More specifically, for Figure 3 In the exemplary aspect depicted in FIG, method 300 further includes determining data indicating an amount of oxygen reduction of the liquid fuel flow passing through the fuel oxygen reduction unit at (308). The data indicating the amount of oxygen reduction can be data indicating an oxygen content of the liquid fuel flow from the fuel oxygen reduction unit, data indicating a reduction in oxygen content in the liquid fuel flow from the fuel oxygen reduction unit (e.g., paired with data indicating a known or estimated starting oxygen content of the liquid fuel), etc.

[0086] Furthermore, for the exemplary aspect shown, regulating the stripping gas flow to the stripping gas supply line at (306) includes regulating the stripping gas flow to the stripping gas supply line at (310) in response to data indicating an amount of oxygen reduction of the liquid fuel flow passing through the fuel oxygen reduction unit at (308).

[0087] More specifically, for the depicted exemplary aspect, determining data indicative of an amount of oxygen reduction of the liquid fuel flow through the fuel oxygen reduction unit at (308) includes determining data indicative of a mass flow rate of the stripping gas flow to the stripping gas supply line at (312), and determining data indicative of a mass flow rate of the liquid fuel flow to the fuel oxygen reduction unit at (314). Furthermore, for such exemplary aspect, regulating the stripping gas flow through the stripping gas supply line at (306) more specifically includes regulating the stripping gas flow to the stripping gas supply line at (316) in response to the data indicative of the mass flow rate of the stripping gas flow to the stripping gas supply line determined at (312), and includes regulating the stripping gas flow to the stripping gas supply line at (318) in response to the data indicative of the mass flow rate of the liquid fuel flow to the fuel oxygen reduction unit determined at (314).

[0088] However, in other exemplary aspects, the method may determine the oxygen reduction of the liquid fuel flow in any other suitable manner (eg, directly sensing the oxygen content), and the method 300 may adjust the stripping gas flow in response to the information.

[0089] In this manner, it will be appreciated that the method 300 can provide a desired amount of oxygen reduction within the liquid fuel stream provided to the engine while minimizing a temperature increase across the contactor of the fuel oxygen reduction unit. For example, by adjusting the flow of stripping gas to the stripping gas supply line in response to received data indicative of an engine operability parameter and further in response to determined data indicative of an amount of oxygen reduction in the liquid fuel stream, the method 300 can provide only the amount of stripping gas to the contactor necessary to achieve the desired amount of oxygen reduction in the liquid fuel stream to allow the liquid fuel stream to accommodate a desired temperature increase prior to combustion.

[0090] In this manner, it should be understood that in certain example aspects, regulating the stripping gas flow to the stripping gas supply line at (306) may include, at (320), reducing the stripping gas flow to the stripping gas supply line in response to the data received at (302) and optionally further in response to the data determined at (308). For example, the data received at (302) may indicate a reduction in the maximum temperature that the liquid fuel flow from the fuel oxygen reduction unit will need to be conditioned to downstream of the fuel oxygen reduction unit prior to combustion. For example, reducing the stripping gas flow to the stripping gas supply line at (318) may include, at (320), reducing the oxygen content of the liquid fuel flow to an oxygen content equal to or within a threshold value below the fuel oxygen set point determined at (304) to minimize a temperature increase of the liquid fuel flow passing through the contactor. The threshold value may be 10% or less of the fuel oxygen set point, such as 8% or less of the fuel oxygen set point, such as 5% or less of the fuel oxygen set point. For example, if the fuel oxygen set point is 5 ppm, and the threshold is 10%, reducing the oxygen content at (320) may include reducing the oxygen content to between 4.5 ppm and 5 ppm.

[0091] Furthermore, in this manner, it should be understood that regulating the stripping gas flow to the stripping gas supply line at (306) may include reducing the stripping gas flow through the stripping gas supply line to the contactor at (322) by at least 10% of a maximum amount (based on the mass flow rate of the stripping gas without the reduction), such as at least 15%, such as at least 25%, such as at least 35%, such as at least 45%, such as up to 90%. This may allow the method 300 to provide a desired oxygen reduction to the liquid fuel flow (based on engine operability parameters and the data determined at (308)) without unnecessarily heating the liquid fuel flow.

[0092] Furthermore, it should be understood that regulating the stripping gas flow to the stripping gas supply line at (306) may include operating the fuel oxygen reduction unit at (324) to provide the fuel flow exiting the fuel oxygen reduction unit with a fuel oxygen content that is at least 10% higher, such as at least 20% higher, such as at least 30% higher, such as at least 40% higher, such as at least 50% higher, such as at least 100% higher, such as up to 10,000% higher, than if the stripping gas flow through the stripping gas flow path to the contactor were unrestricted. Similarly, this may also allow the method 300 to provide a desired amount of oxygen reduction to the liquid fuel flow (based on engine operability parameters and data determined at (308)) without unnecessarily heating the liquid fuel flow.

[0093] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. If such other examples include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims, they are intended to be within the scope of the claims.

[0094] Further aspects are provided by the subject matter of the following clauses:

[0095] A fuel oxygen reduction unit for reducing the oxygen content of a liquid fuel flow to an engine, the fuel oxygen reduction unit comprising: a stripping gas supply line for providing a stripping gas flow; a contactor defining a liquid fuel inlet, a stripping gas inlet, and a fuel / gas mixture outlet, the stripping gas supply line being in gaseous communication with the stripping gas inlet; means for regulating the flow of stripping gas through the stripping gas supply line; and a controller operable with the means for regulating the flow of stripping gas through the stripping gas supply line to regulate the flow of stripping gas through the stripping gas supply line in response to an engine operability parameter.

[0096] The fuel oxygen reduction unit of one or more of these clauses, wherein the engine operability parameter is indicative of an amount of oxygen reduction required for the liquid fuel flow provided to the liquid fuel inlet of the contactor.

[0097] A fuel oxygen reduction unit according to one or more of these clauses, wherein the controller is configured to determine data indicative of a mass flow rate of a stripping gas flow provided to a stripping gas inlet of the contactor, a mass flow rate of a liquid fuel flow provided to a liquid fuel inlet of the contactor, or both, and wherein the controller is further configured to regulate the stripping gas flow through the stripping gas supply line in response to the data indicative of the mass flow rate of the stripping gas flow, the data indicative of the mass flow rate of the liquid fuel flow, or both.

[0098] The fuel oxygen reduction unit of one or more of these clauses, wherein the controller is further configured to regulate the stripping gas flow through the stripping gas supply line in response to data indicative of the mass flow rate of the stripping gas flow and data indicative of the mass flow rate of the liquid fuel flow.

[0099] The fuel oxygen reduction unit according to one or more of these clauses, further comprising: a gas inlet temperature sensor for sensing data indicative of the temperature of the stripping gas flow provided to the stripping gas inlet of the contactor; and an outlet temperature sensor for sensing data indicative of the temperature of the fuel / gas mixture flow from the fuel / gas mixture outlet, and wherein the controller is configured to determine data indicative of the mass flow rate of the stripping gas flow provided to the stripping gas inlet based on the data indicative of the temperature of the stripping gas flow provided to the stripping gas inlet and the data indicative of the temperature of the fuel / gas mixture flow.

[0100] The fuel oxygen reduction unit according to one or more of these clauses, further comprising a flow sensor for sensing data indicative of a mass flow rate of a stripping gas flow provided to the stripping gas inlet of the contactor.

[0101] The fuel oxygen reduction unit of one or more of these clauses, wherein the controller is configured to increase stripping gas flow through the stripping gas supply line in response to an engine operability parameter indicating a need for lower fuel oxygen content.

[0102] The fuel oxygen reduction unit of one or more of these clauses, wherein the controller is configured to reduce stripping gas flow through the stripping gas supply line in response to an engine operability parameter indicating that a higher fuel oxygen content is acceptable.

[0103] The fuel oxygen reduction unit according to one or more of these clauses, wherein the controller is configured to reduce the stripping gas flow through the stripping gas supply line by at least 10% of a maximum amount in response to an engine operability parameter.

[0104] The fuel oxygen reduction unit according to one or more of these clauses, wherein the means for regulating the flow of stripping gas through the stripping gas supply line comprises a variable speed gas booster pump in flow communication with the stripping gas supply line.

[0105] The fuel oxygen reduction unit according to one or more of these clauses, wherein the means for regulating the stripping gas flow through the stripping gas supply line comprises a fluid control valve configured to vary the amount of stripping gas flow through the stripping gas supply line.

[0106] A method of operating a fuel oxygen reduction unit configured to provide a liquid fuel flow to an engine, the method comprising: receiving data indicative of an engine operability parameter of the engine, the engine operability parameter indicative of an amount of oxygen reduction desired for the liquid fuel flow; and regulating a stripping gas flow through a stripping gas supply line of the fuel oxygen reduction unit to a contactor of the fuel oxygen reduction unit in response to the received data.

[0107] A method according to one or more of these clauses, wherein the engine operability parameter is indicative of a temperature to which the liquid fuel flow from the fuel oxygen reduction unit will reach downstream of the fuel oxygen reduction unit.

[0108] The method according to one or more of these clauses, wherein regulating the stripping gas flow through the stripping gas supply line comprises reducing the stripping gas flow through the stripping gas supply line in response to the received data.

[0109] A method according to one or more of these clauses, wherein the received data is indicative of a reduction in temperature to which the liquid fuel flow from the fuel oxygen reduction unit will reach downstream of the fuel oxygen reduction unit.

[0110] A method according to one or more of these clauses, wherein receiving data indicative of an engine operability parameter of the engine comprises determining a fuel oxygen set point for a liquid fuel flow to the engine, and wherein reducing the stripping gas flow through the stripping gas supply line in response to the received data comprises reducing the oxygen content of the liquid fuel flow to within a threshold of the fuel oxygen set point to minimize a temperature increase of the liquid fuel flow across the contactor.

[0111] The method according to one or more of these clauses, wherein regulating the stripping gas flow through the stripping gas supply line comprises varying the speed of a variable speed gas booster pump in flow communication with the stripping gas supply line.

[0112] The method according to one or more of these clauses, further comprising: determining data indicative of a mass flow rate of a stripping gas flow through a stripping gas supply line; wherein regulating the stripping gas flow through the stripping gas supply line further comprises regulating the stripping gas flow through the stripping gas supply line in response to the data indicative of the mass flow rate of the stripping gas flow through the stripping gas supply line.

[0113] The method according to one or more of these clauses, further comprising: determining data indicative of a mass flow rate of the liquid fuel flow to the fuel oxygen reduction unit; wherein regulating the stripping gas flow through the stripping gas supply line further comprises regulating the stripping gas flow through the stripping gas supply line in response to the data indicative of the mass flow rate of the liquid fuel flow to the fuel oxygen reduction unit.

[0114] The method of one or more of these clauses, wherein regulating the stripping gas flow to the stripping gas supply line comprises operating the fuel oxygen reduction unit to provide a fuel oxygen content to the fuel flow exiting the fuel oxygen reduction unit that is at least 10% higher than if the stripping gas flow through the stripping gas flow line to the contactor were unrestricted.

Claims

1. A method of operating a fuel oxygen reduction unit configured to provide a liquid fuel flow to an engine, characterized in that: The method comprises: receiving data indicative of an engine operability parameter of the engine, the engine operability parameter indicative of an amount of oxygen reduction desired for the liquid fuel flow; sensing gas inlet data indicative of a temperature of a stripping gas stream provided to a stripping gas inlet of the contactor using a gas inlet temperature sensor; sensing fuel inlet data indicative of a temperature of a liquid fuel flow provided to a fuel inlet of the contactor using a fuel inlet temperature sensor; sensing mixture data indicative of a temperature of a fuel / gas mixture flow from a fuel / gas mixture outlet of the contactor using an outlet temperature sensor; determining data indicative of a mass flow rate of the stripping gas flow through a stripping gas supply line based on the gas inlet data, the fuel inlet data, and the mixture data; and In response to the data received and in response to the data indicating the mass flow rate of the stripping gas flow through the stripping gas supply line, an amount of stripping gas through the stripping gas supply line of the fuel oxygen reduction unit to the contactor of the fuel oxygen reduction unit is adjusted.

2. The method according to claim 1, characterized in that in, Adjusting includes increasing the stripping gas flow through the stripping gas supply line to the contactor in response to the engine operability parameter indicating a need for a lower fuel oxygen content in the liquid fuel flow.

3. The method according to claim 1, characterized in that in, Adjusting includes reducing the stripping gas flow through the stripping gas supply line to the contactor in response to the engine operability parameter indicating that a higher fuel oxygen content in the liquid fuel flow is acceptable.

4. The method according to claim 1, wherein Further included determining a fuel oxygen set point for the liquid fuel flow to the engine.

5. The method according to claim 4, characterized in that Further comprising reducing the oxygen content of the liquid fuel stream to an oxygen level equal to the fuel oxygen set point.

6. The method according to claim 4, characterized in that Further comprising reducing the oxygen content of the liquid fuel stream to within a threshold below the fuel oxygen set point to minimize a temperature increase of the liquid fuel stream passing through the contactor.

7. The method according to claim 1, characterized in that in, Adjusting includes varying the speed of a variable speed gas booster pump in flow communication with the stripping gas supply line.

8. A method of operating a fuel oxygen reduction unit configured to provide a liquid fuel flow to an engine, characterized in that: The method comprises: receiving data indicative of an engine operability parameter of the engine, the engine operability parameter indicative of an amount of oxygen reduction desired for the liquid fuel flow, wherein the engine operability parameter indicative of a temperature to be reached by the liquid fuel flow from the fuel oxygen reduction unit downstream of the fuel oxygen reduction unit; and In response to the received data, a stripping gas flow through a stripping gas supply line of the fuel oxygen reduction unit to a contactor of the fuel oxygen reduction unit is reduced by adjusting a control valve, wherein reducing the stripping gas flow through the stripping gas supply line includes changing a speed of a variable speed gas booster pump in fluid communication with the stripping gas supply line, wherein all of the stripping gas in the stripping gas supply line flows through the variable speed gas booster pump and into the contactor.

9. The method according to claim 8, characterized in that Further included determining a fuel oxygen set point for the liquid fuel flow to the engine.

10. The method according to claim 9, characterized in that Further comprising reducing the oxygen content of the liquid fuel stream to an oxygen level equal to the fuel oxygen set point.

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