Fuel oxygen reduction unit with horizontal control device

Abstract

A fuel oxygen reduction unit for an engine is provided. The fuel oxygen reduction unit includes a contactor that includes a fuel inlet for receiving an inlet fuel stream and a stripping gas inlet for receiving an inlet stripping gas stream, the contactor being configured to form a fuel / gas mixture; a separator that receives the fuel / gas mixture, the fuel oxygen reduction unit defining a recycle gas flow path from the separator to the contactor; and a level control device that controls the level of the fuel / gas mixture inside the separator by adjusting the inlet fuel stream to the contactor.

Description

Technical Field

[0001] The present subject matter generally relates to a fuel oxygen reduction unit for an engine and a method of operating the same. Background Art

[0002] Typical aircraft propulsion systems include one or more gas turbine engines. A gas turbine engine generally includes a turbine that includes, in a series flow order, a compressor section, a combustion section, a turbine section, and an exhaust section. In operation, air is provided 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 burned within the combustion section to provide combustion gases. The combustion gases are conveyed from the combustion section to the turbine section. The flow of combustion gases through the turbine section drives the turbine section and is then conveyed through the exhaust section, e.g., to the atmosphere.

[0003] Certain operations and systems of gas turbine engines and aircraft may generate a relatively large amount of heat. Fuel has been identified as an effective heat sink to receive at least some of such heat during operation, at least in part due to its heat capacity and the increased efficiency that may result from burning higher temperature fuels during combustion operations.

[0004] However, heating the fuel without proper regulation may cause the fuel to "coke", or form solid particles that may clog certain components 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 an unacceptable amount. Summary of the Invention

[0005] Aspects and advantages of the present disclosure will be set forth in part in the following description, or may be obvious from the description, or may be learned by practice of the present disclosure.

[0006] In an exemplary embodiment of the present disclosure, a fuel oxygen reduction unit for an engine is provided. The fuel oxygen reduction unit includes a contactor that includes a fuel inlet for receiving an inlet fuel stream and a stripping gas inlet for receiving an inlet stripping gas stream, the contactor being configured to form a fuel / gas mixture; a separator that receives the fuel / gas mixture, the fuel oxygen reduction unit defining a recycle gas flow path from the separator to the contactor; and a level control device that controls the level of the fuel / gas mixture inside the separator by regulating the inlet fuel stream to the contactor.

[0007] In an exemplary aspect of the present disclosure, a method for operating a fuel delivery system of an engine is provided. The method includes receiving an inlet fuel stream in a contactor of a fuel oxygen reduction unit for reducing the amount of oxygen in the inlet fuel stream using a stripping gas stream through a stripping gas flow path; separating a fuel / gas mixture into an outlet stripping gas stream and an outlet fuel stream via a separator; and controlling the level of the fuel / gas mixture inside the separator by adjusting the inlet fuel stream to the contactor.

[0008] In another exemplary embodiment of the present disclosure, a leveling system for a fuel oxygen reduction unit is provided, the fuel oxygen reduction unit having a contactor and a separator, the contactor including a fuel inlet for receiving an inlet fuel stream and a stripping gas inlet for receiving an inlet stripping gas stream, the separator receiving a fuel / gas mixture from the contactor. The leveling system includes a level control device configured to be positioned in fluid communication with a fuel flow path to the contactor, the level control device including a spool movably disposed within the level control device, the level control device being configured to control the level of the fuel / gas mixture inside the separator by adjusting the inlet fuel stream to the contactor.

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

[0010] A complete and enabling disclosure of the present disclosure, including the best mode thereof, for the ordinary skill in the art, is set forth in the specification, which makes reference to the accompanying drawings, in which:

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

[0012] Figure 2 is a schematic view of a fuel oxygen reduction unit with a level control device in accordance with an exemplary embodiment of the present disclosure.

[0013] Figure 3 is a schematic view of a level control device in accordance with an exemplary embodiment of the present disclosure.

[0014] Figure 4 is a schematic view of a level control device in accordance with another exemplary embodiment of the present disclosure.

[0015] Figure 5 is a schematic view of a separator of a fuel oxygen reduction unit in accordance with an exemplary embodiment of the present disclosure.

[0016] Figure 6 is a flowchart of a method for operating a fuel delivery system of an engine according to an exemplary aspect of the present disclosure.

[0017] Figure 7A is a cross-sectional view of a control device fuel outlet according to an exemplary embodiment of the present disclosure.

[0018] Figure 7B is a cross-sectional view of a control device fuel outlet according to another exemplary embodiment of the present disclosure.

[0019] Figure 7C is a cross-sectional view of a control device fuel outlet according to another exemplary embodiment of the present disclosure.

[0020] Corresponding reference numerals indicate corresponding parts in several views. The examples listed herein illustrate exemplary embodiments of the present disclosure, and these examples should not be construed as limiting the scope of the present disclosure in any way. Detailed Description

[0021] Reference will now be made in detail to the current embodiments of the present disclosure, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and alphabetical reference numerals to refer to features in the drawings. Identical or similar reference numerals have been used in the drawings and description to refer to identical or similar parts of various embodiments.

[0022] The following description is provided to enable a person skilled in the art to make and use the embodiments contemplated for implementing the present disclosure. However, various modifications, equivalents, variations, and alternatives will be apparent to a person skilled in the art. Any and all such modifications, variations, equivalents, and alternatives are intended to fall within the scope of the present disclosure.

[0023] As used herein, the term "exemplary" means "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as more preferred or advantageous than other embodiments. Furthermore, unless otherwise expressly stated, all embodiments described herein are to be considered exemplary.

[0024] For the purposes of the following description, the terms "up," "down," "right," "left," "vertical," "horizontal," "top," "bottom," "lateral," "longitudinal," and derivatives thereof shall relate to the embodiment oriented in the accompanying drawings. However, it should be understood that the present disclosure may assume various alternative variations, unless otherwise expressly stated to the contrary. It should also be understood that the specific devices illustrated in the drawings and described in the following specification are merely exemplary embodiments of the present disclosure. Accordingly, specific dimensions and other physical characteristics related to the embodiments disclosed herein should not be considered limiting.

[0025] As used herein, the terms "first", "second", and "third" may be used interchangeably to distinguish one component from another, and are not intended to denote the position or importance of the individual components.

[0026] The terms "upstream" and "downstream" refer to the relative direction with respect to the flow of fluid in a fluid path. For example, "upstream" refers to the direction from which the fluid flows, and "downstream" refers to the direction towards which the fluid flows.

[0027] Unless otherwise specified herein, the terms "coupled", "fixed", "attached to", etc. refer to direct coupling, fixing, or attachment, as well as indirect coupling, fixing, or attachment through one or more intermediate components or features.

[0028] Unless the context clearly dictates otherwise, the singular forms "a", "an", and "the" include plural references.

[0029] Throughout the specification and claims, approximating language is applied to modify any quantitative representation that can vary without resulting in a change in its associated basic function. Thus, 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 instances, the approximating language may correspond to the precision of the instrument used to measure the value, or the precision of the method or machine used to construct or manufacture the component and / or system. For example, the approximating language may refer to within a margin of 1%, 2%, 4%, 10%, 15%, or 20%. These approximating margins may be applied to a single value, either endpoint of a defined numerical range, both endpoints, and / or the margin of a range between the endpoints.

[0030] Herein and throughout the specification and claims, range limitations are combined and interchanged, and unless the context or language indicates otherwise, such ranges are identified and include all subranges subsumed therein. For example, all ranges disclosed herein include the endpoints, and the endpoints may be combined independently of one another.

[0031] The fuel oxygen reduction unit of the present disclosure includes a level control device that controls the level of the fuel / gas mixture inside the separator by adjusting the inlet fuel flow provided to the contactor. In an exemplary embodiment, the level control device of the present disclosure utilizes the active liquid or fuel level inside the separator, such as the pressure of the fuel or liquid inside the separator, to adjust the inlet fuel flow. For example, the level control device in at least one embodiment utilizes a first reference pressure at the center of the separator and a second reference pressure at the edge of the separator to adjust the inlet fuel flow. The self-regulating level control device of the present disclosure ensures the continuous availability of an adequate amount of fuel inside the separator and to the downstream system. In this way, the level control device also prevents the spillage of fuel or liquid inside the separator. The connection to the reference pressure can be direct or indirect to improve the responsiveness of the system. The level control device of the present disclosure can be completely self-sufficient and may not require any external components or external control to operate the system.

[0032] In a fuel oxygen reduction system, the mixing of the stripping gas with the liquid fuel results in a foam composition, which can cause the amount of fuel inhaled by the engine to lose continuity. This can cause the inlet fuel flow to supply too much fuel or too little fuel to the system, resulting in fuel spilling out of the separator or insufficient fuel in the separator. The level control device of the present disclosure eliminates these problems and ensures more continuous availability of an adequate amount of fuel inside the separator and to the downstream system.

[0033] Now referring to the drawings, where like numerals represent like elements in all the drawings, Figure 1 A 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 aeroengine incorporated into an aircraft. However, alternatively, the engine can be any other suitable type of engine for any other suitable vehicle.

[0034] For the depicted embodiment, the engine is configured as a high bypass turbofan engine 100. As Figure 1 shown, the turbofan engine 100 defines an axial direction A (extending parallel to the longitudinal centerline or axis 101 provided for reference), a radial direction R, and a circumferential direction (extending around the axial direction A; Figure 1 not depicted in the figures). Generally, the turbofan engine 100 includes a fan section 102 and a turbine 104 disposed downstream of the fan section 102.

[0035] The exemplary turbine 104 depicted generally includes a generally tubular outer casing 106 that defines an annular inlet 108. The outer casing 106 surrounds, in a series flow relationship, a compressor section that includes a booster or low pressure (LP) compressor 110 and a high pressure (HP) compressor 112; a combustion section 114; a turbine section that includes a high pressure (HP) turbine 116 and a low pressure (LP) turbine 118; and an exhaust nozzle section 120. The compressor section, combustion section 114, and turbine section together at least partially define a core air flow path 121 that extends from the annular inlet 108 to the exhaust 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 that drivingly connects the HP turbine 116 to the HP compressor 112, and a low pressure (LP) shaft or spool 124 that drivingly connects the LP turbine 118 to the LP compressor 110.

[0036] For the depicted embodiment, the fan section 102 includes a fan 126 that has a plurality of fan blades 128 coupled to a disk 130 in a spaced-apart manner. The fan blades 128 and the disk 130 are rotatable together about a longitudinal axis 101 via the LP shaft 124. The disk 130 is covered by a rotatable front hub 132 that has an aerodynamic profile to facilitate air flow through the plurality of fan blades 128. Additionally, an annular fan casing or nacelle 134 is provided that circumferentially surrounds the fan 126 and / or at least a portion of the turbine 104. The nacelle 134 is supported relative to the turbine 104 by a plurality of circumferentially spaced outlet guide vanes 136. A downstream section 138 of the nacelle 134 extends over the exterior of the turbine 104 so as to define a bypass air flow path 140 therebetween.

[0037] Still referring to Figure 1 , the turbofan engine 100 additionally includes an accessory gearbox 142, a fuel oxygen reduction unit 144, and a fuel delivery system 146. For the illustrated embodiment, the accessory gearbox 142 is located within the cowling / outer casing 106 of the turbine 104. Additionally, it should be understood that although not schematically depicted in Figure 1 , the accessory gearbox 142 can be mechanically coupled to one or more shafts or spools of the turbine 104 and can rotate with one or more shafts or spools of the turbine 104. For example, in at least some exemplary embodiments, the accessory gearbox 142 can be mechanically coupled to the HP shaft 122 and can rotate with the HP shaft 122. Notably, as used herein, the term “fuel oxygen reduction” generally refers to a device capable of reducing the free oxygen content of fuel.

[0038] In addition, 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 a fuel flow through the fuel delivery system 146 to the combustion section 114 of the turbine 104 of the turbofan engine 100.

[0039] However, it should be understood that Figure 1 the exemplary turbofan engine 100 depicted in is provided only as an example. In other exemplary embodiments, any other suitable engine may be used with aspects of the present disclosure. For example, in other embodiments, the engine may be any other suitable gas turbine engine, such as a turboshaft engine, a turboprop engine, a turbojet engine, etc. In this manner, it will be further understood that in other embodiments, the gas turbine engine may have any other suitable configuration, such as any other suitable number or arrangement of shafts, compressors, turbines, fans, etc. Additionally, although Figure 1 the exemplary gas turbine engine depicted in is schematically shown as a direct drive, fixed pitch turbofan engine 100, in other embodiments, the gas turbine engines of the present disclosure may be geared gas turbine engines (i.e., including a gearbox between the fan 126 and the shaft driving the fan (such as the LP shaft 124)), may be variable pitch gas turbine engines (i.e., including a fan 126 having a plurality of fan blades 128 that are rotatable about their respective pitch axes), etc. Additionally, although not shown herein, in other embodiments, the gas turbine engine may be any other suitable type of gas turbine engine, such as an industrial gas turbine engine incorporated into a power generation system, a marine gas turbine engine, etc. Additionally, still in alternative embodiments, aspects of the present disclosure may be incorporated into or otherwise used with any other type of engine, such as a reciprocating engine.

[0040] In addition, it should be understood that although for the depicted embodiment, the turbofan engine 100 includes a fuel oxygen reduction unit 144 located within the turbine 104, i.e., within the housing 106 of the turbine 104, in other embodiments, the fuel oxygen reduction unit 144 may be located at any other suitable location. For example, in other embodiments, the fuel oxygen reduction unit 144 may alternatively be positioned away from the turbofan engine 100. Additionally, in other embodiments, the fuel oxygen reduction unit 144 may be additionally or alternatively driven by other suitable power sources (such as an electric motor, a hydraulic motor, or an independent mechanism coupled to the HP or LP shaft).

[0041] Now referring to Figure 2, a schematic view of a fuel oxygen reduction unit or oxygen transfer assembly 200 for a gas turbine engine in accordance with an exemplary aspect of the present disclosure is provided. In at least some exemplary embodiments, the depicted exemplary fuel oxygen reduction unit 200 may be incorporated into, for example, the exemplary turbofan engine 100 described above with reference to Figure 1 (e.g., may be the fuel oxygen reduction unit 144 depicted and described above in Figure 1 ).

[0042] As will be understood from the discussion herein, in an exemplary embodiment, the fuel oxygen reduction unit 200 generally includes a contactor 202, a separator 204, and a level control device 206. In one exemplary embodiment, the separator 204 may be a dual separator pump, as described in more detail below and as Figure 5 shown. In other exemplary embodiments, other separators may be used with the fuel oxygen reduction unit 200 of the present disclosure.

[0043] In some exemplary embodiments, the fuel oxygen reduction unit 200 may further include a gas booster pump 208, a catalyst 210, and a preheater 212. Additionally, the exemplary fuel oxygen reduction unit 200 generally defines a recirculating gas flow path 205 from the separator 204 to the contactor 202, and for the Figure 2 depicted embodiment, the preheater 212, catalyst 210, and gas booster pump 208 are positioned within the recirculating gas flow path 205 or otherwise fluidly connected to the recirculating gas flow path 205.

[0044] In an exemplary embodiment, the contactor 202 may be configured in any suitable manner to substantially mix the received gas and liquid streams. For example, in certain embodiments, the contactor 202 may be a mechanically driven contactor (e.g., having blades for mixing the received streams), or alternatively may be a passive contactor that is configured to mix the received streams using at least in part the pressure and / or flow rate of the received streams. For example, a passive contactor may include one or more turbulators, venturi mixers, etc.

[0045] In an exemplary embodiment, the contactor 202 includes a contactor fuel inlet 250 that receives an inlet fuel stream 226 and a contactor stripping gas inlet 252 that receives a stripping gas stream 220. As described herein, the contactor 202 is configured to form a fuel / gas mixture 228.

[0046] In addition, the exemplary fuel oxygen reduction unit 200 includes a stripping gas line 207, and more specifically, a plurality of stripping gas lines 207 that together at least partially define a recycle gas flow path 205 extending from the separator 204 to the contactor 202. In certain exemplary embodiments, the recycle gas flow path 205 may be formed by any combination of one or more conduits, pipes, tubes, etc., in addition to the structures or components within the plurality of stripping gas lines 207 and the recycle gas flow path 205.

[0047] It should be understood that the fuel oxygen reduction unit 200 generally provides a flow of stripping gas 220 through the plurality of stripping gas lines 207 and the gas flow path 205 during operation. It should be understood that the term "stripping gas" is used herein as a convenient term to refer to a gas that is generally capable of performing the functions described herein. The stripping gas 220 flowing through the stripping gas flow path / recycle gas flow path 205 may be the actual stripping gas for stripping oxygen from the fuel within the contactor, or alternatively may be an injection gas for foaming the liquid fuel to reduce the oxygen content of such fuel. For example, the stripping gas 220 may be an inert gas such as nitrogen or carbon dioxide (CO 2 ), a gas mixture composed of at least 50% by mass of inert gas, or some other gas or gas mixture having a relatively low oxygen content.

[0048] For the illustrated embodiment, the gas booster pump 208, the catalyst 210, and the preheater 212 are each arranged in series flow within the recycle gas flow path 205. In addition, the gas booster pump 208 is configured as a rotary gas pump that is mechanically coupled to and driven by the fuel gas separator 204. In this way, the gas booster pump 208 can rotate together with the fuel gas separator 204. However, in other embodiments, the gas booster pump 208 may be configured in any other suitable manner. For example, in other embodiments, the gas booster pump 208 may be mechanically disconnected from the fuel gas separator 204 and may rotate independently of the fuel gas separator 204. For example, in certain embodiments, the gas booster pump 208 and / or the separator 204 may be independently coupled to an accessory gearbox, or may be an electric pump electrically coupled to a suitable power source, such as a permanent magnet alternator (PMA), which may also provide power to a full authority digital engine controller (FADEC). In embodiments where the gas booster pump 208 is coupled to a power source independent of the separator 204, the gas booster pump 208 may rotate at a different rotational speed than the fuel gas separator 204.

[0049] Still referring to Figure 2, in an exemplary embodiment, the separator 204 generally includes a stripping gas outlet 214, a fuel outlet 216, and an inlet 218. It should also be understood that the depicted exemplary fuel oxygen reduction unit 200 can operate with a fuel delivery system 146, such as the fuel delivery system 146 of a gas turbine engine that includes the fuel oxygen reduction unit 200 (see, for example Figure 1 ). The exemplary fuel delivery system 146 generally includes a plurality of fuel lines, particularly an inlet fuel line 222 and an outlet fuel line 224. The inlet fuel line 222 is fluidly connected to the contactor 202 via a level control device 206 for providing a liquid fuel stream or an inlet fuel stream 226 (e.g., from a fuel source 225, such as a fuel tank) to the contactor 202, and the outlet fuel line 224 is fluidly connected to the fuel outlet 216 of the separator 204 for receiving a deoxygenated liquid fuel stream or an outlet fuel stream 227.

[0050] In addition, during typical operation, a stripping gas stream 220 flows from the stripping gas outlet 214 of the separator 204 through a recycle gas flow path 205 to the contactor 202. More specifically, during typical operation, the stripping gas 220 flows from the stripping gas outlet 214 of the separator 204 through a preheater 212 (configured to add thermal energy to the gas flowing therethrough), through a catalyst 210, and to / through a gas booster pump 208, where the pressure of the stripping gas 220 is increased to provide a stripping gas 220 stream through the recycle gas flow path 205. The relatively high-pressure stripping gas 220 (i.e., relative to the pressure upstream of the booster pump 208 and the fuel entering the contactor 202) is then provided to the contactor 202, where the stripping gas 220 is mixed with the inlet fuel 226 stream from the inlet fuel line 222 to produce a fuel / gas mixture 228. The fuel / gas mixture 228 generated within the contactor 202 is provided to the inlet 218 of the separator 204.

[0051] Generally, it should be understood that during operation of the fuel oxygen reduction unit 200, the inlet 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 inlet fuel 226 is mixed with the stripping gas 220, producing a fuel / gas mixture 228. As a result of this mixing, a physical exchange may occur such that at least a portion of the oxygen in the inlet fuel 226 is transferred to the stripping gas 220, such that the fuel component of the mixture 228 has a relatively low oxygen content (compared to the inlet fuel 226 provided via the inlet fuel line 222) and the stripping gas component of the mixture 228 has a relatively high oxygen content (compared to the inlet stripping gas 220 provided to the contactor 202 via the recycle gas flow path 205).

[0052] Within the separator 204, the relatively high-oxygen-content stripping gas 220 then separates from the relatively low-oxygen-content fuel and returns to the respective flows of the outlet stripping gas 220 and the outlet fuel 227.

[0053] In one exemplary embodiment, the separator 204 can be a dual-separator pump as shown in Figure 5 For example, briefly referring to Figure 5 , a dual-separator pump such as separator 204 defines a central axis 230, a radial direction R, and a circumferential direction C extending around the central axis 230. Additionally, the dual-separator pump, such as separator 204, is configured as a mechanically driven dual-separator pump, or more specifically as a rotary / centrifugal dual-separator pump. Thus, the dual-separator pump, such as separator 204, includes an input shaft 232 and a single-stage separator / pump assembly 234. The input shaft 232 is mechanically coupled to the single-stage separator / pump assembly 234, and the two components can rotate together around the central axis 230. Additionally, the input shaft 232 can be mechanically coupled to and driven by, for example, an accessory gearbox (such as the exemplary accessory gearbox 142 of Figure 1 ). However, in other embodiments, the input shaft 232 can be mechanically coupled to any other suitable power source, such as an electric, hydraulic, pneumatic, or other power source. As will be understood, the single-stage separator / pump assembly 234 can simultaneously separate the mixture 228 into the flows of the outlet stripping gas 220 and the outlet fuel 227 from the mixture 228 and increase the pressure of the separated outlet fuel 227 (as will be discussed in more detail below).

[0054] Furthermore, the depicted exemplary single-stage separator / pump assembly 234 generally includes an internal gas filter 236 disposed along the central axis 230 and a plurality of vanes 238 positioned radially outward of the internal gas filter 236 in the radial direction R. During operation, the rotation of the single-stage separator / pump assembly 234 around the central axis 230, and more specifically, the rotation of the plurality of vanes 238 around the central axis 230 (i.e., in the circumferential direction C), can generally force the heavier liquid fuel 226 outward along the radial direction R and force the lighter stripping gas 220 inward along the radial direction R through the internal gas filter 236. In this manner, the outlet fuel 227 can exit through the fuel outlet 216 of the dual-separator pump (such as separator 204), and the outlet stripping gas 220 can exit through the stripping gas outlet 214 of the dual-separator pump (such as separator 204), as indicated.

[0055] In addition, it should be understood that with this configuration, the outlet fuel 227 exiting the dual separator pump (e.g., separator 204) through the fuel outlet 216 can be at a higher pressure than the inlet fuel 226 provided through the inlet fuel line 222, and further higher than the fuel / gas mixture 228 provided through the inlet 218. This may be at least partially attributed to the centrifugal force applied to the inlet fuel stream 226 and the rotation of the plurality of vanes 238. In addition, it should be understood that for the depicted embodiment, the liquid fuel outlet 216 is located radially outward of the inlet 218 (i.e., the fuel gas mixture inlet) along the radial direction R. This can also contribute to increasing the pressure of the outlet fuel 227 provided through the fuel outlet 216 of the separator 204.

[0056] For example, it should be understood that for such an exemplary embodiment, the separator 204 of the fuel oxygen reduction unit 200 can generate a pressure increase in the fuel stream during operation. As used herein, the term "pressure increase" refers to the net pressure difference between the pressure of the outlet fuel 227 stream provided to the fuel outlet 216 of the separator 204 (i.e., the "liquid fuel outlet pressure") and the pressure of the inlet fuel 226 provided to the contactor 202 through the inlet fuel line 222. In at least some exemplary embodiments, the pressure increase of the inlet fuel 226 can be at least about sixty (60) pounds per square inch ("psi"), such as at least about ninety (90) psi, such as at least about one hundred (100) psi, such as up to about seven hundred and fifty (750) psi. With this configuration, it should be understood that in at least some exemplary embodiments of the present disclosure, the liquid fuel outlet pressure can be at least about seventy (70) psi during operation. For example, in at least some exemplary embodiments, the liquid fuel pressure drop can be at least about one hundred (100) psi during operation, such as at least about one hundred and twenty-five (125) psi during operation, such as up to about eight hundred (800) psi during operation.

[0057] In addition, it should be understood that the outlet fuel 227 provided to the fuel outlet 216 has interacted with the stripping gas 220 and can have a relatively low oxygen content, so that a relatively high amount of heat can be added to it, thereby reducing the risk of fuel coking (i.e., a chemical reaction occurs to form solid particles that may clog or damage components within the fuel flow path). For example, in at least some exemplary aspects, the outlet fuel 227 provided to the fuel outlet 216 can have an oxygen content of 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.

[0058] In addition, now returning to reference Figure 2, as will be appreciated, the depicted exemplary fuel oxygen reduction unit 200 recycles and re-uses the stripping gas 220 (i.e., the stripping gas 220 operates in a substantially closed loop). However, the stripping gas 220 exiting the separator 204 has interacted with the inlet fuel 226 and has a relatively high oxygen content. Thus, in order to re-use the stripping gas 220, the oxygen content of the stripping gas 220 at the stripping gas outlet 214 from the separator 204 needs to be reduced. For the depicted embodiment, and as described above, the stripping gas 220 flows through the pre-heater 212, through the catalyst 210, where the oxygen content of the stripping gas 220 is reduced, and through the gas booster pump 208, where the pressure of the stripping gas 220 is increased to provide a flow of the stripping gas 220 through the recycle gas flow path 205.

[0059] More specifically, within the catalyst 210, the relatively oxygen-rich stripping gas 220 reacts to reduce its oxygen content. It should be understood that the catalyst 210 can be configured in any suitable manner to perform these functions. For example, in some embodiments, the catalyst 210 can be configured to combust the relatively oxygen-rich stripping gas 220 to reduce its oxygen content. However, in other embodiments, the catalyst 210 can additionally or alternatively include geometries of catalytic components through which the relatively oxygen-rich stripping gas 220 flows to reduce its oxygen content. In one or more of these embodiments, the catalyst 210 can be configured to reduce the oxygen content of the stripping gas 220 to less than about five percent (5%) by mass of oxygen (O 2 ), such as less than about two percent (2) (3%) of oxygen (O 2 ), such as less than about one percent (1%) of oxygen (O 2 ).

[0060] The resulting relatively low oxygen content gas is then provided through the remainder of the recycle gas flow path 205 and returned to the contactor 202 so that the cycle can be repeated. In this manner, it will be appreciated that the stripping gas 220 can be any suitable gas capable of undergoing the above-described chemical transformation. For example, the stripping gas can be air from, 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 ).

[0061] However, in other embodiments, the stripping gas can alternatively be any other suitable gas, such as an inert gas, such as nitrogen or carbon dioxide (CO 2 ), a gas mixture composed of at least 50% by mass of an inert gas, or some other gas or gas mixture having a relatively low oxygen content.

[0062] However, it should be understood that the above-exemplary fuel oxygen reduction unit 200 is provided only as an example. In other embodiments, the fuel oxygen reduction unit 200 may be configured in any other suitable manner. For example, in other embodiments, the fuel oxygen reduction unit 200 may have any other suitable separator 204, its components may be arranged in any other suitable flow order, it may not include each of the depicted components, it may include components configured in any other suitable manner, or it may include other components not depicted or described herein.

[0063] In other embodiments, the stripping gas 220 may not flow through the recycle gas flow path 205, and alternatively, the fuel oxygen reduction unit 200 may include an open-loop stripping gas flow path that is in fluid communication with a suitable stripping gas source (such as an exhaust gas source) and is configured to discharge such air into the atmosphere downstream of the fuel gas separator 204.

[0064] Still referring to Figure 2 And now also referring to Figure 3 , the fuel oxygen reduction unit 200 further includes a level control device 206 that controls the level of the fuel / gas mixture 228 within the separator 204 by regulating the inlet fuel stream 226 provided to the contactor 202.

[0065] In an exemplary embodiment, the level control device 206 utilizes the active liquid or fuel level inside the separator 204, such as the pressure of the fuel or liquid within the separator 204, to regulate the inlet fuel stream. For example, the level control device 206 utilizes a reference pressure at the center of the separator 204 and a second reference pressure at the edge of the separator 204 to regulate the inlet fuel stream. The self-regulating level control device 206 of the present disclosure ensures the continuous availability of a sufficient amount of fuel within the separator 204 and downstream systems. In this way, the level control device 206 can also prevent the fuel or liquid inside the separator 204 from overflowing.

[0066] The connection to the reference pressure can be direct or indirect to improve the responsiveness of the system. The level control device 206 of the present disclosure is fully self-sufficient and does not require any external components or external control to operate the system.

[0067] In a fuel oxygen reduction system, the mixing of an inert gas with a liquid fuel results in a foam composition, which may cause the amount of fuel inhaled by the engine to lose continuity. This may cause the inlet fuel stream to supply too much fuel or too little fuel to the system, resulting in fuel overflowing from the separator or insufficient fuel in the separator. The level control device 206 of the present disclosure eliminates these problems and ensures the continuous availability of a sufficient amount of fuel within the separator 204 and downstream systems.

[0068] In an exemplary embodiment, a level control device 206 is provided upstream of the contactor 202 and controls the amount of inlet fuel flow 226 provided to the contactor 202. In an exemplary embodiment, the level control device 206 generally includes a control device fuel inlet 302, a control device fuel outlet 304, a spool 306, a fuel / gas mixture pressure reference section 308, a separator edge pressure reference section 310, and a spring 312 (see, in particular Figure 3 ).

[0069] Still referring to Figure 2 and 3 , in an exemplary embodiment, the control device fuel inlet 302 is in communication with the fuel source 225, and the control device fuel outlet 304 is in communication with the contactor fuel inlet 250 of the contactor 202. As Figure 3 more clearly depicted in

[0070] , the spool 306 includes a first spool end 320 and a second spool end 322. The spool 306 is movably disposed within the level control device 206 such that the spool 306 can be switched between positions to control the amount of inlet fuel flow 226 exiting the control device fuel outlet 304.

[0071] The level control device 206 includes a fuel / gas mixture pressure reference section 308 that communicates with the fuel / gas mixture pressure 324 (e.g., a reference pressure in the central portion of the separator 204) and the first spool end 320. In an exemplary embodiment, it is contemplated that the central portion of the separator 204 includes a portion within, for example, the middle 50% of the separator 204 between the inlet 218 and the fuel outlet 216. In other exemplary embodiments, it is contemplated that the central portion of the separator 204 can include a portion within, for example, the middle 25% of the separator 204 between the inlet 218 and the fuel outlet 216. In an exemplary embodiment, it is contemplated that the central portion of the diverter 204 can include a portion within, for example, the middle 50% of the diverter 204 based on the diameter of the diverter 204 relative to the centerline of the diverter 204. In other exemplary embodiments, it is contemplated that the central portion of the diverter 204 can include a portion within, for example, the middle 25% of the diverter 204 based on the diameter of the diverter 204 relative to the centerline of the diverter 204.

[0071] The level control device 206 further includes a separator edge pressure reference section 310 that communicates with the separator edge pressure 326 and the second spool end 322. Referring to Figure 3 , in an exemplary embodiment, the spring 312 communicates with the first spool end 320.

[0072] The separator edge pressure 326 refers to the fluid pressure at the outer edge inside the separator 204, asFigure 2 as indicated by the separator edge pressure arrow 326 in Figure 2 . The separator edge pressure 326 is communicated to the level control device 206 via Figure 3 the separator edge pressure conduit labeled 326 in Figure 3 and is referred to herein by the reference numeral 326 for convenience.

[0073] Specifically referring back to Figure 2 , the fuel / gas mixture pressure 324 is communicated to the fuel / gas mixture pressure reference section 308 of the level control device 206 via the fuel / gas mixture pressure supply circuit 330. In this way, the fuel / gas mixture pressure 324 of the fuel / gas mixture 228 downstream of the contactor 202 is used to operate the level control device 206 as described herein.

[0074] The fuel / gas mixture pressure 324 refers to the pressure of the fuel / gas mixture 228 downstream of the contactor 202, as Figure 2 indicated by the fuel / gas mixture pressure arrow 324 in Figure 2 . The fuel / gas mixture pressure 324 is communicated to the level control device 206 via Figure 3 the fuel / gas mixture pressure conduit labeled 324 in Figure 3 and is referred to herein by the reference numeral 324 for convenience.

[0075] The separator edge pressure 326 is the liquid pressure within the separator 204 and at the separator edge 260. Due to the separator 204 rotating very fast, the centrifugal force of the separator 204 generates a higher pressure in these edge regions. For example, the pressure of the separator edge pressure 326 is higher than the pressure of the inlet fuel stream 226.

[0076] The separator edge pressure 326 is communicated to the separator edge pressure reference section 310 of the level control device 206 (see Figure 3 ) via the separator edge pressure supply circuit 340. In this way, the separator edge pressure 326 within the separator 204 is used to operate the level control device 206 as described herein.

[0077] Referring back again to Figure 3, during operation, as the separator edge pressure 326 increases, the spool 306 is moved to compress the spring 312 and close a portion of the control device fuel outlet 304, thereby reducing the amount of inlet fuel flow 226 to the contactor 202. For example, as the separator edge pressure 326 increases, this higher pressure exerts a force on the second spool end 322, causing the spool 306 to move towards the spring 312, thereby compressing the spring 312. As the spool 306 moves towards the spring 312, a portion of the second spool end 322 also moves to block a portion of the control device fuel outlet 304, thereby reducing the amount of inlet fuel flow 226 that can leave the control device fuel outlet 304. The higher the separator edge pressure 326 increases, the more the spool 306 compresses the spring 312 and the more the second spool end 322 blocks the control device fuel outlet 304.

[0078] An increase in the fuel / gas mixture 228 received by the separator 204 causes an increase in the separator edge pressure 326. In this way, the increase in the separator edge pressure 326 causes the second spool end 322 to block a portion of the control device fuel outlet 304 as described herein, thereby reducing the amount of inlet fuel flow 226 to the contactor 202. This causes a decrease and balance in the amount of fuel / gas mixture 228 entering the separator 204.

[0079] , during operation, as the separator edge pressure 326 decreases, the spring 312 exerts a force on the spool 306, and the spool 306 is moved to open a portion of the control device fuel outlet 304, thereby increasing the amount of inlet fuel flow 226 to the contactor 202. For example, as the separator edge pressure 326 decreases, the force exerted by the spring 312 on the first spool end 320 now overcomes the separator edge pressure 326 acting on the second spool end 322, which causes the spool 306 to move towards the separator edge pressure reference portion 310.

[0080] As the spool 306 moves towards the separator edge pressure reference portion 310, the second spool end 322 moves downward and away from blocking a portion of the control device fuel outlet 304, thereby increasing the amount of inlet fuel flow 226 that can leave the control device fuel outlet 304. The more the separator edge pressure 326 decreases, the more the spring 312 moves the second spool end 322 away from blocking any portion of the control device fuel outlet 304.

[0081] The reduction of the fuel / gas mixture 228 received by the separator 204 reduces the separator edge pressure 326. In this way, the reduction of the separator edge pressure 326 causes the spring 312 to apply any force as described herein that moves the second spool end 322 away from the blocked control device fuel outlet 304, thereby increasing the amount of inlet fuel flow 226 to the contactor 202. This causes an increase and balance in the amount of fuel / gas mixture 228 entering the separator 204.

[0082] Reference Figures 7A - 7C , shows a variety of different geometric configurations of the control device fuel outlet 304 ( Figure 3 ). For example, reference Figure 7A , in some exemplary embodiments, the control device fuel outlet 700 has a linear geometry. Reference Figure 7B , in another exemplary embodiment, the control device fuel outlet 702 has a triangular geometry. Reference Figure 7C , in another exemplary embodiment, the control device fuel outlet 704 has a logarithmic geometry.

[0083] In an exemplary embodiment, the control device fuel outlet 304 can have a non-linear geometry. For example, in an exemplary embodiment, for a control device fuel outlet 304 having a linear geometry, for each 1 mm increment of downward movement of the spool 306, the amount of area of the open control device fuel outlet 304 is also linear. However, in some embodiments, it may be desirable for the control device fuel outlet 304 to open a non-linear amount of area for each 1 mm of downward movement of the spool 306. In such an embodiment, the control device fuel outlet 304 having a non-linear geometry allows the spool 306 to move away from the control device fuel outlet 304 and disengage from the contact control device fuel outlet 304 for each increment, such non-linear opening of the control device fuel outlet 304.

[0084] In an exemplary embodiment, the level control device 206 of the present disclosure ensures the continuous availability of a sufficient amount of fuel within the separator 204 and downstream systems during changes in engine operating states (e.g., during each of an engine idle state, an engine takeoff state, an engine high speed state, an engine low speed state, and any other desired engine state).

[0085] Return reference Figure 2, in other exemplary embodiments, the fuel oxygen reduction unit 200 may further include other components. For example, the fuel oxygen reduction unit 200 may include a removal device 270 located between the contactor 202 and the separator 204. In an exemplary embodiment, the removal device 270 can be used to eliminate any excess foam in the fuel / gas mixture 228. In some exemplary embodiments, the fuel oxygen reduction unit 200 may further include an intermediate device 280. For example, the intermediate device 280 may be positioned along a portion of the fuel / gas mixture pressure supply circuit 330 and / or along a portion of the separator edge pressure supply circuit 340. Such an intermediate device 280 may include sensing components and / or other monitoring devices that can be used to enhance the sensing capabilities of the fuel oxygen reduction unit 200.

[0086] It is also contemplated that the level control device 206 of the present disclosure is compatible with a hydrogen fuel source. For example, the level control device 206 may operate as described herein to control the flow in a hydrogen fuel system.

[0087] Alternatively, the device 206 of the present disclosure may additionally or alternatively be compatible with a hydrocarbon-based fuel source.

[0088] Figure 4 Another exemplary embodiment is shown. Figure 4 The illustrated embodiment of the level control device 400 includes components similar to those of Figure 2 and Figure 3 the illustrated embodiment of the level control device 206. For the sake of brevity, these similar components and the similar steps of using the level control device 400 ( Figure 4 ) and the level control device 206 ( Figure 2 and Figure 3 ) will not all be discussed in conjunction with Figure 4 the illustrated embodiment.

[0089] Referring to Figure 4 , in other exemplary embodiments, the level control device 400 may use a first reference pressure 402 and a second reference pressure 404 to control the flow as described herein. For example, in an exemplary embodiment, the first reference pressure 402 may include the separator edge pressure and the second reference pressure 404 may include the metered liquid pressure. The level control device 400 further includes a control device fuel outlet 406.

[0090] Now referring to Figure 6 , exemplary aspects of the present disclosure will now be discussed.

[0091] For Figure 6Exemplary aspects of the method 600 generally include receiving, at (602), an inlet fuel stream in a contactor of a fuel oxygen reduction unit for reducing the amount of oxygen in the inlet fuel stream using a stripping gas stream through a stripping gas flow path, as described in detail above with reference to Figures 1 to 5 The method 600 further includes separating, at (604), the fuel / gas mixture into an outlet stripping gas stream and an outlet fuel stream via a separator, and controlling, at (606), the level of the fuel / gas mixture inside the separator by adjusting the inlet fuel stream to the contactor, as described in detail above with reference to Figures 1 to 5 The method 600 further includes separating, at (604), the fuel / gas mixture into an outlet stripping gas stream and an outlet fuel stream via a separator, and controlling, at (606), the level of the fuel / gas mixture inside the separator by adjusting the inlet fuel stream to the contactor, as described in detail above with reference to

[0092] Further aspects of the present disclosure are provided by the subject matter of the following clauses:

[0093] 1. A fuel oxygen reduction unit for an engine, comprising: a contactor including a fuel inlet for receiving an inlet fuel stream and a stripping gas inlet for receiving an inlet stripping gas stream, the contactor being configured to form a fuel / gas mixture; a separator that receives the fuel / gas mixture, the fuel oxygen reduction unit defining a recycle gas flow path from the separator to the contactor; and a level control device that controls the level of the fuel / gas mixture inside the separator by adjusting the inlet fuel stream to the contactor.

[0094] 2. The fuel oxygen reduction unit according to any one of the preceding clauses, wherein the level control device is located upstream of the contactor and controls the amount of the inlet fuel stream to the contactor.

[0095] 3. The fuel oxygen reduction unit according to any one of the preceding clauses, wherein the level control device includes: a control device fuel inlet in communication with a fuel source; a control device fuel outlet in communication with the fuel inlet of the contactor; and a spool having a first spool end and a second spool end, the spool being movably disposed within the level control device.

[0096] 4. The fuel oxygen reduction unit according to any one of the preceding clauses, wherein the level control device further includes: a fuel / gas mixture pressure reference portion in communication with the fuel / gas mixture pressure and the first spool end; a separator edge pressure reference portion in communication with the separator edge pressure and the second spool end; and a spring in communication with the first spool end.

[0097] 5. The fuel oxygen reduction unit according to any one of the preceding clauses, wherein as the separator edge pressure increases, the spool is moved to compress the spring and close a portion of the control device fuel outlet, thereby reducing the amount of the inlet fuel stream to the contactor.

[0098] 6. The fuel oxygen reduction unit according to any one of the preceding clauses, wherein as the separator edge pressure decreases, the spring applies a force to the spool and the spool is moved to open a portion of the fuel outlet of the control device, thereby increasing the amount of inlet fuel flow to the contactor.

[0099] 7. The fuel oxygen reduction unit according to any one of the preceding clauses, wherein an increase in the fuel / gas mixture received by the separator increases the separator edge pressure.

[0100] 8. The fuel oxygen reduction unit according to any one of the preceding clauses, wherein a decrease in the fuel / gas mixture received by the separator decreases the separator edge pressure.

[0101] 9. The fuel oxygen reduction unit according to any one of the preceding clauses, wherein the separator includes an inlet, a fuel outlet, and a stripping gas outlet, the inlet being in fluid communication with a contactor that receives the fuel / gas mixture, wherein the separator is configured to separate the fuel / gas mixture into an outlet stripping gas stream and an outlet fuel stream, and to provide the outlet stripping gas stream to the stripping gas outlet and the outlet fuel stream to the fuel outlet.

[0102] 10. The fuel oxygen reduction unit according to any one of the preceding clauses, wherein the outlet fuel stream has a lower oxygen content than the inlet fuel stream, and wherein the outlet stripping gas stream has a higher oxygen content than the inlet stripping gas stream.

[0103] 11. The fuel oxygen reduction unit according to any one of the preceding clauses, further comprising a catalyst disposed downstream of the separator, wherein the catalyst receives and processes the outlet stripping gas stream, and wherein the inlet stripping gas stream exits the catalyst.

[0104] 12. The fuel oxygen reduction unit according to any one of the preceding clauses, wherein the fuel source includes hydrogen fuel.

[0105] 13. A method for operating a fuel delivery system for an engine, comprising: receiving an inlet fuel flow in a contactor of a fuel oxygen reduction unit for reducing the amount of oxygen in the inlet fuel flow using a stripping gas flow through a stripping gas flow path; separating the fuel / gas mixture into an outlet stripping gas stream and an outlet fuel stream via a separator; and controlling the level of the fuel / gas mixture inside the separator by adjusting the inlet fuel flow to the contactor.

[0106] 14. The method according to any one of the preceding clauses, wherein separating the fuel / gas mixture includes using a separator that receives the fuel / gas mixture from the contactor.

[0107] 15. The method according to any one of the preceding clauses, wherein controlling the amount of the inlet fuel flow includes using a level control device including a spool and a spring.

[0108] 16. The method according to any one of the preceding clauses, wherein controlling the level of the fuel / gas mixture inside the separator by adjusting the inlet fuel flow to the contactor includes: as the separator edge pressure increases, the spool is moved to compress a spring and close a part of the fuel outlet of the control device, thereby reducing the amount of the inlet fuel flow to the contactor.

[0109] 17. The method according to any one of the preceding clauses, wherein controlling the level of the fuel / gas mixture inside the separator by adjusting the inlet fuel flow to the contactor includes: as the separator edge pressure decreases, the spring exerts a force on the separator and the spool is moved to open a part of the fuel outlet of the control device, thereby increasing the amount of the inlet fuel flow to the contactor.

[0110] 18. The method according to any one of the preceding clauses, wherein an increase in the fuel / gas mixture received by the separator raises the separator edge pressure.

[0111] 19. The method according to any one of the preceding clauses, wherein a decrease in the fuel / gas mixture received by the separator lowers the separator edge pressure.

[0112] 20. A leveling system for a fuel oxygen reduction unit, the fuel oxygen reduction unit having a contactor and a separator, the contactor including a fuel inlet for receiving an inlet fuel flow and a stripping gas inlet for receiving an inlet stripping gas flow, the splitter receiving a fuel / gas mixture from the contactor, the leveling system including: a level control device configured to be positioned in fluid communication with the fuel flow path to the contactor, the level control device including a spool movably disposed within the level control device, the level control device being configured to control the level of the fuel / gas mixture inside the separator by adjusting the inlet fuel flow to the contactor.

[0113] The method according to any one of the preceding clauses, wherein the outlet fuel flow has a lower oxygen content than the inlet fuel flow, and wherein the outlet stripping gas flow has a higher oxygen content than the inlet stripping gas flow.

[0114] This written description uses examples to disclose various aspects of the present disclosure, including the best mode, and also enables any person skilled in the art to practice various aspects of the present disclosure, including making and using any device or system and performing any incorporated method. The patent scope of the present disclosure 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 are identical to the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims, then they are intended to be within the scope of the claims.

[0115] While the present disclosure has been described with an exemplary design, the present disclosure may be further modified within the scope of the present disclosure. Accordingly, this application is intended to cover any variations, uses, or adaptations of the present disclosure using its general principles. In addition, this application is intended to cover departures from the present disclosure that are known or customary in the art to which the present disclosure pertains and that fall within the limitations of the appended claims.

Claims

1. A fuel oxygen reduction unit for an engine, characterized in that, comprising: a contactor, the contactor including a fuel inlet for receiving an inlet fuel stream and a stripping gas inlet for receiving an inlet stripping gas stream, the contactor being configured to form a fuel / gas mixture; a separator, the separator receiving the fuel / gas mixture, the fuel oxygen reduction unit defining a recycle gas flow path from the separator to the contactor; and a level control device, the level control device including: a control device fuel inlet, the control device fuel inlet being in communication with a fuel source; a control device fuel outlet, the control device fuel outlet being in communication with the fuel inlet of the contactor; a spool, the spool being movably disposed within the level control device and having a first spool end and a second spool end, a fuel / gas mixture pressure reference portion, the fuel / gas mixture pressure reference portion being in communication with the fuel / gas mixture pressure and the first spool end; a separator edge pressure reference portion, the separator edge pressure reference portion being in communication with the separator edge pressure and the second spool end; and a spring, the spring being in communication with the first spool end; wherein the level control device controls the level of the fuel / gas mixture inside the separator by adjusting the inlet fuel stream to the contactor.

2. The fuel oxygen reduction unit according to claim 1, characterized in that, wherein, the level control device is located upstream of the contactor and controls the amount of the inlet fuel stream to the contactor.

3. The fuel oxygen reduction unit according to claim 1, characterized in that, wherein, as the separator edge pressure increases, the spool is moved to compress the spring and close a portion of the control device fuel outlet, thereby reducing the amount of the inlet fuel stream to the contactor.

4. The fuel oxygen reduction unit according to claim 3, characterized in that, wherein, as the separator edge pressure decreases, the spring exerts a force on the spool and the spool is moved to open a portion of the control device fuel outlet, thereby increasing the amount of the inlet fuel stream to the contactor.

5. The fuel oxygen reduction unit according to claim 4, characterized in that, wherein, an increase in the fuel / gas mixture received by the separator increases the separator edge pressure.

6. The fuel oxygen reduction unit according to claim 5, characterized in that, wherein, a decrease in the fuel / gas mixture received by the separator decreases the separator edge pressure.

7. The fuel oxygen reduction unit according to claim 1, characterized in that, wherein, the separator includes an inlet, a fuel outlet, and a stripping gas outlet, the inlet being in fluid communication with the contactor that receives the fuel / gas mixture, wherein the separator is configured to separate the fuel / gas mixture into an outlet stripping gas stream and an outlet fuel stream, and provide the outlet stripping gas stream to the stripping gas outlet and the outlet fuel stream to the fuel outlet.

8. The fuel oxygen reduction unit according to claim 7, wherein, wherein, the outlet fuel stream has a lower oxygen content than the inlet fuel stream, and wherein the outlet stripping gas stream has a higher oxygen content than the inlet stripping gas stream.

9. The fuel oxygen reduction unit according to claim 8, wherein, further comprising: a catalyst disposed downstream of the separator, wherein the catalyst receives and processes the outlet stripping gas stream, and wherein the inlet stripping gas stream exits the catalyst.

10. The fuel oxygen reduction unit according to claim 1, wherein, wherein, the fuel source includes hydrogen fuel.

11. A method for operating a fuel delivery system for an engine by using the fuel oxygen reduction unit for an engine according to claim 1, wherein, comprising: receiving an inlet fuel stream in a contactor of the fuel oxygen reduction unit for reducing the amount of oxygen in the inlet fuel stream by using a stripping gas stream through a stripping gas flow path; separating the fuel / gas mixture into an outlet stripping gas stream and an outlet fuel stream via a separator; and controlling the level of the fuel / gas mixture inside the separator by adjusting the inlet fuel stream to the contactor.

12. The method according to claim 11, wherein, wherein, separating the fuel / gas mixture includes using the separator that receives the fuel / gas mixture from the contactor.

13. The method according to claim 12, wherein, wherein, controlling the level of the fuel / gas mixture inside the separator by adjusting the inlet fuel stream to the contactor includes using a level control device including a spool and a spring.

14. The method according to claim 13, wherein, wherein, controlling the level of the fuel / gas mixture inside the separator by adjusting the inlet fuel stream to the contactor includes: as the separator edge pressure increases, the spool is moved to compress the spring and close a part of the control device fuel outlet, thereby reducing the amount of the inlet fuel stream to the contactor.

15. The method according to claim 14, wherein, wherein, controlling the level of the fuel / gas mixture inside the separator by adjusting the inlet fuel stream to the contactor includes: as the separator edge pressure decreases, the spring exerts a force on the spool and the spool is moved to open a part of the control device fuel outlet, thereby increasing the amount of the inlet fuel stream to the contactor.

16. The method according to claim 15, wherein, wherein, an increase in the fuel / gas mixture received by the separator increases the separator edge pressure.

17. The method according to claim 16, wherein, wherein, a decrease in the fuel / gas mixture received by the separator decreases the separator edge pressure.

18. A leveling system for a fuel oxygen reduction unit, wherein the fuel oxygen reduction unit includes a contactor and a separator, the contactor includes a fuel inlet for receiving an inlet fuel stream and a stripping gas inlet for receiving an inlet stripping gas stream, and the separator receives a fuel / gas mixture from the contactor, characterized in that, the leveling system includes: a level control device, and the level control device includes: a control device fuel inlet, which is in communication with a fuel source; a control device fuel outlet, which is in communication with the fuel inlet of the contactor; a spool, which is movably arranged in the level control device and has a first spool end and a second spool end, a fuel / gas mixture pressure reference part, which is in communication with the fuel / gas mixture pressure and the first spool end; a separator edge pressure reference part, which is in communication with the separator edge pressure and the second spool end; and a spring, which is in communication with the first spool end; wherein, the level control device is configured to control the level of the fuel / gas mixture inside the separator by adjusting the inlet fuel stream to the contactor.

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