CN110065641B

CN110065641B - Fuel tank catalytic inerting device for aircraft

Info

Publication number: CN110065641B
Application number: CN201910068251.6A
Authority: CN
Inventors: E.苏劳斯基
Original assignee: Hamilton Sundstrand Corp
Current assignee: Hamilton Sundstrand Corp
Priority date: 2018-01-24
Filing date: 2019-01-24
Publication date: 2023-11-03
Anticipated expiration: 2039-01-24
Also published as: CN110065641A

Abstract

Tank inerting systems and methods for aircraft are provided. The system comprises: an oil tank; a first reactant source fluidly connected to the fuel tank, the first source being arranged to receive fuel from the fuel tank; a second reactant source; a catalytic reactor arranged to receive a first reactant from the first source and a second reactant from the second source to produce an inert gas, the inert gas being supplied to the tank to fill a ullage of the tank; and a cold air source arranged to supply cold air to the catalytic reactor to provide thermal control of reactions within the catalytic reactor, wherein the cold air is discharged from at least one of a cabin of the aircraft and an environmental control system of the aircraft.

Description

Fuel tank catalytic inerting device for aircraft

Background

The subject matter disclosed herein relates generally to aircraft tank inerting systems, and more particularly to tank inerting systems configured to supply inert gas in an aircraft.

In general, aircraft pneumatic systems are powered by engine bleed air, including air conditioning systems, cabin pressurization and cooling, and tank inerting systems. For example, charge air from an engine of an aircraft is provided to a cabin via a series of systems that alter the temperature and pressure of the charge air. To power this preparation of charge air, the energy source is, in general, the pressure of the air itself.

Air bled from the engine may be used in environmental control systems, such as for supplying air to cabins and to other systems within the aircraft. Additionally, air bled from the engine may be supplied to the inerting apparatus to provide inert gas to the tank. In other cases, the air may originate from compressed ram air.

Regardless of the source, air for tank inerting is typically passed through a bundle of porous hollow fiber membranes called an "air separation module". A downstream flow control valve is controlled or passively operated to apply back pressure to the air separation module to force a quantity of air through the membrane as opposed to flowing through the tube. Oxygen more readily passes through the membrane leaving only nitrogen-enriched air to continue through the flow control valve into the tank. Typically, the air separation module employs a dedicated ram air heat exchanger in combination with a bypass valve.

Disclosure of Invention

According to some embodiments, a tank inerting system for an aircraft is provided. The system comprises: an oil tank; a first reactant source fluidly connected to the fuel tank, the first source being arranged to receive fuel from the fuel tank; a second reactant source; a catalytic reactor arranged to receive a first reactant from the first source and a second reactant from the second source to produce an inert gas, the inert gas being supplied to the tank to fill a ullage of the tank; and a cold air source arranged to supply cold air to the catalytic reactor to provide thermal control of reactions within the catalytic reactor, wherein the cold air is discharged from a cabin of the aircraft.

In addition to or as an alternative to one or more features described herein, other embodiments of the tank inerting system may include the first source being an evaporator vessel.

In addition to or as an alternative to one or more features described herein, other embodiments of the tank inerting system may include the second source being at least one of a bleed port of an engine of an aircraft and the cabin of the aircraft.

In addition to or in lieu of one or more features described herein, other embodiments of the tank inerting system may include a heat exchanger disposed between the catalytic reactor and the tank and configured to at least one of cool and condense an output from the catalytic reactor to separate inert gas from byproducts.

In addition to or as an alternative to one or more features described herein, other embodiments of the tank inerting system may include a heating conduit thermally connected to the catalytic reactor and arranged in thermal communication with the first source to provide heat to the first source to produce the first reactant.

In addition to or as an alternative to one or more features described herein, other embodiments of the tank inerting system may include a syringe pump arranged to receive the first reactant and the second reactant and to supply a mixture of the first reactant and the second reactant to the catalytic reactor.

In addition to or in lieu of one or more features described herein, other embodiments of the tank inerting system may include an inert gas recirculation system downstream of the catalytic reactor and upstream of the tank, wherein the inert gas recirculation system is arranged to direct a portion of the inert gas to the catalytic reactor.

In addition to or as an alternative to one or more features described herein, other embodiments of the tank inerting system may include at least one additional tank, wherein the at least one additional tank is arranged to receive inert gas from the catalytic reactor.

In addition to or as an alternative to one or more features described herein, other embodiments of the tank inerting system may include a water separator located between the catalytic reactor and the tank and downstream of the catalytic reactor, the water separator being arranged to extract water from the reacted first and second reactants.

According to some embodiments, a tank inerting system for an aircraft is provided. The system comprises: an oil tank; a first reactant source fluidly connected to the fuel tank, the first source being arranged to receive fuel from the fuel tank; a second reactant source; a catalytic reactor arranged to receive a first reactant from the first source and a second reactant from the second source to produce an inert gas, the inert gas being supplied to the tank to fill a ullage of the tank; and a cold air source arranged to supply cold air to the catalytic reactor to provide thermal control of reactions within the catalytic reactor, wherein the cold air is discharged from an environmental control system of the aircraft.

In addition to or as an alternative to one or more features described herein, other embodiments of the tank inerting system may include the second source being at least one of a bleed port of an engine of an aircraft and a cabin of the aircraft.

In addition to or in lieu of one or more features described herein, other embodiments of the tank inerting system may include a heat exchanger disposed between the catalytic reactor and the tank and configured to condense an output from the catalytic reactor to separate inert gas from byproducts.

According to some embodiments, a method of supplying an inert gas to a fuel tank of an aircraft is provided. The method comprises the following steps: supplying fuel from a fuel tank to a first reactant source; generating a first reactant within the first reactant source; mixing the first reactant with a second reactant supplied from a second reactant source; catalytically mixing the first reactant and the second reactant in a catalytic reactor to produce an inert gas; supplying the inert gas to the tank to fill a head space of the tank; and supplying exhaust gas from at least one of a cabin of the aircraft and an environmental control system to the heat exchanger to enable cooling of an output from the catalytic reactor.

In addition to or as an alternative to one or more features described herein, other embodiments of the method may include at least one of cooling and condensing an output from the catalytic reactor by a heat exchanger disposed between the catalytic reactor and the tank to separate inert gas from byproducts.

In addition to or as an alternative to one or more features described herein, other embodiments of the method may include the byproduct being water.

In addition to or as an alternative to one or more features described herein, other embodiments of the method may include heating the first source using a heating conduit thermally connected to the catalytic reactor and arranged in thermal communication with the first source to provide heat from the catalytic reactor to the first source to produce the first reactant.

In addition to or as an alternative to one or more features described herein, other embodiments of the method may include mixing the first reactant with the second reactant and injecting using a syringe pump to supply the mixture of the first reactant and the second reactant to the catalytic reactor.

In addition to or as an alternative to one or more features described herein, other embodiments of the method may include recirculating a portion of the inert gas and supplying the recirculated portion to the catalytic reactor.

In addition to or as an alternative to one or more features described herein, other embodiments of the method may include supplying the inert gas from the catalytic reactor to at least one additional tank.

In addition to or as an alternative to one or more features described herein, other embodiments of the method may include extracting water from the reacted first and second reactants using a water separator located between the catalytic reactor and the tank and downstream of the catalytic reactor.

The foregoing features and elements may be non-exclusively combined in various combinations unless explicitly indicated otherwise. These features and elements, as well as the operation thereof, will become more apparent in light of the following description and accompanying drawings. However, it is to be understood that the following description and drawings are intended to be illustrative and illustrative in nature and not restrictive.

Drawings

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

FIG. 1A is a schematic illustration of an aircraft that may incorporate various embodiments of the present disclosure;

FIG. 1B is a schematic view of a bay section of the aircraft of FIG. 1A;

FIG. 2 is a schematic diagram of a tank inerting system according to an embodiment of the present disclosure;

FIG. 3 is a schematic diagram of a tank inerting system according to an embodiment of the present disclosure;

FIG. 4 is a schematic diagram of a tank inerting system according to an embodiment of the present disclosure;

FIG. 5 is a schematic diagram of a tank inerting system according to an embodiment of the present disclosure;

FIG. 6A is a schematic diagram of a tank inerting system according to an embodiment of the present disclosure;

FIG. 6B is a schematic illustration of a portion of the tank inerting system of FIG. 6A;

FIG. 7 is a schematic diagram of a tank inerting system according to an embodiment of the present disclosure;

FIG. 8 is a schematic diagram of a tank inerting system according to an embodiment of the present disclosure;

FIG. 9 is a schematic diagram of a tank inerting system according to an embodiment of the present disclosure;

FIG. 10 is a schematic diagram of a tank inerting system according to an embodiment of the present disclosure;

FIG. 11 is a schematic diagram of a tank inerting system according to an embodiment of the present disclosure;

FIG. 12 is a schematic diagram of a tank inerting system according to an embodiment of the present disclosure;

FIG. 13 is a schematic view of a tank inerting system according to an embodiment of the present disclosure; and is also provided with

Fig. 14 is a schematic diagram of a tank inerting system according to an embodiment of the present disclosure.

Detailed Description

As shown in fig. 1A-1B, aircraft 101 may include one or more compartments 103 under the center wing box. The compartment 103 may house and/or support one or more components of the aircraft 101. For example, in some configurations, aircraft 101 may include environmental control systems and/or fuel inerting systems within compartment 103. As shown in fig. 1B, the compartment 103 includes a compartment door 105 that enables installation and access to one or more components (e.g., environmental control systems, fuel inerting systems, etc.). During operation of the environmental control system and/or the fuel inerting system of the aircraft 101, air external to the aircraft 101 may flow into one or more environmental control systems within the compartment door 105 via one or more ram air inlets 107. The air may then flow through an environmental control system to be processed and supplied to various components or locations within the aircraft 101 (e.g., a passenger cabin, a fuel inerting system, etc.). Some of the air may be discharged via one or more ram air discharge openings 109.

Also shown in fig. 1A, aircraft 101 includes one or more engines 111. The engine 111 is typically mounted on the wing of the aircraft 101, but may be located in other locations, depending on the particular aircraft configuration. In some aircraft configurations, air may be bled from the engine 111 and supplied to an environmental control system and/or a fuel inerting system, as will be appreciated by those skilled in the art.

As noted above, typical air separation modules operate using differential pressure to achieve the desired air separation. Such systems require a high pressure pneumatic source to drive the separation process across the membrane. In addition, the size and weight of the hollow fiber membrane separators that are commonly used are relatively large, which is an important consideration with respect to aircraft (e.g., a reduction in the volume and weight of components may increase flight efficiency). Embodiments provided herein provide for reduced volume and/or weight characteristics of an inert gas or low oxygen supply system of an aircraft. In addition, embodiments provided herein may prevent humid air from entering an aircraft fuel tank, thus preventing various problems that may occur with some fuel system components. According to some embodiments of the present disclosure, a typical hollow fiber membrane separator is replaced with a catalytic system (e.g., a CO2 generation system), which may be, for example, smaller, lighter, and/or more efficient than a typical fiber membrane separator. That is, according to embodiments of the present disclosure, the use of a hollow fiber membrane separator may be eliminated.

The function of the tank flammability reduction system according to embodiments of the present disclosure is accomplished by reacting a small amount of fuel vapor (e.g., "first reactant") with a source of oxygen-containing gas (e.g., "second reactant"). The products of the reaction are carbon dioxide and water vapor. The source of the second reactant (e.g., air) may be bleed air or any other source of oxygen-containing air, including, but not limited to, a high pressure source (e.g., an engine), bleed air, cabin air, and the like. Catalyst materials are used to initiate chemical reactions including, but not limited to, noble metal materials. The carbon dioxide produced by the reaction is an inert gas mixed with nitrogen naturally present in fresh/ambient air and is directed back into the tank to create an inert environment within the tank, thus reducing the flammability of the vapor in the tank. Additionally, in some embodiments, the fuel tank flammability reduction or inerting system of the present disclosure may provide functionality such that water vapor from the atmosphere does not enter the fuel tank during the descent phase of the aircraft voyage. This may be accomplished by controlling the flow rate of inert gas into the tank such that a positive pressure is continuously maintained in the tank.

According to embodiments of the present disclosure, a catalyst is used to initiate a chemical reaction between oxygen (O2) and fuel vapor to produce carbon dioxide (CO 2) and water vapor. The source of O2 used in the reaction may be from any of a number of sources including, but not limited to, a pneumatic source on board the aircraft that supplies air at a pressure higher than ambient pressure. Fuel vapor is generated by discharging small amounts of fuel from an aircraft fuel tank into an evaporator reservoir. As shown and described in some embodiments of the present disclosure, the fuel may be heated to vaporize the fuel, such as by using an electric heater. In some embodiments, the fuel vapor is removed from the evaporator vessel by an ejector that may induce a suction pressure that draws the fuel vapor from the evaporator vessel. Such injectors may utilize the high pressure of a second reactant source (e.g., a pneumatic source) containing O2 to induce a secondary flow of the injector, which secondary flow originates from the evaporator vessel. As such, an injector may be used to mix the extracted fuel vapor with O2 from the second reactant source.

The mixed gas stream (fuel vapor and oxygen or air) is then introduced to a catalyst that initiates a chemical reaction that converts O2 and fuel vapor to CO2 and water vapor. Any inert gas species (e.g., nitrogen) present in the mixed stream will not react and therefore will pass over the catalyst unchanged. In some embodiments, the catalyst is in a dimensional profile for use as a heat exchanger. For example, in one non-limiting configuration, a plate-fin heat exchanger configuration is employed, wherein the hot side of the heat exchanger is to be coated with a catalyst material. In such an arrangement, the cold side of the catalyst heat exchanger may be fed with a source of cold air (such as ram air or some other source of cold air). The air passing through the cold side of the heat exchanger may be controlled such that the temperature of the hot mixed gas stream is hot enough to maintain the desired chemical reaction within or at the catalyst. In addition, cooling air may be used to maintain a sufficiently cool temperature to enable removal of heat generated by the exothermic reaction at the catalyst.

As noted above, the catalytic chemical reaction produces water vapor. It may be undesirable to have water (in any form) enter the main tank. Thus, according to embodiments of the present disclosure, water from the product gas stream (e.g., exiting the catalyst) may be removed by various mechanisms, including, but not limited to, condensation. The product gas stream may be directed into a heat exchanger downstream of the catalyst for cooling the product gas stream such that water vapor condenses and falls from the product gas stream. The liquid water may then be drained off. In some embodiments, an optional water separator may be used to enhance or provide separation of water from the product stream.

In some embodiments, the flow control valve measures the flow of inert gas (from which water vapor is removed) to a predetermined and/or controlled inert gas flow rate. Additionally, in some embodiments, an optional fan may be used to raise the inert gas stream pressure to overcome the pressure drop associated with the conduit and flow lines between the catalyst and the tank to which the inert gas is supplied. In some embodiments, a flame arrestor may be disposed at the inlet of the tank into which the inert gas enters to prevent any possible flame from propagating into the tank.

Independent of any aircraft flammability reduction system, aircraft fuel tanks are typically open to the environment. At high altitudes, the pressure inside the tank is very low and approximately equal to the ambient pressure. However, during descent, the pressure inside the tank needs to rise to be equal to the ambient pressure at sea level (or at any altitude at which the aircraft lands). Pressure changes require gas to enter the tank from the outside to equalize the pressure. As air enters the tank from the outside, water vapor is typically present therewith. Water may be trapped in the tank and cause problems. In accordance with embodiments of the present disclosure, to prevent water from entering the fuel tank, the fuel inerting system of the present disclosure may repressurize the fuel tank with dry inert gas generated as described above and below. The repressurization may be accomplished by controlling the flow of inert gas into the tank using a flow control valve such that a positive pressure is continuously maintained in the tank. The positive pressure inside the tank may prevent air from entering the tank from the outside during descent and thus water from entering the tank.

Fig. 2 is a schematic diagram of a flammability reduction or inerting system 200 that utilizes a catalytic reaction to produce an inert gas according to one embodiment of the present disclosure. As shown, the inerting system 200 includes a tank 202 having fuel 204 therein. As fuel 204 is consumed during one or more engine operations, a ullage 206 is formed within the fuel tank 202. To reduce the flammability risk associated with the gasified fuel that may form within the ullage 206, an inert gas may be generated and fed into the ullage 206.

According to embodiments of the present disclosure, inerted fuel 208 may be extracted from tank 202 into evaporator vessel 210. The amount of fuel 204 (i.e., the amount of inerted fuel 208) that is extracted into the evaporator tank 210 may be controlled by an evaporator tank valve 212, such as a float valve. Inerted fuel 208, which may be in liquid form when drawn from tank 202, may be vaporized within vaporizer container 210 using heater 214 (such as an electric heater) to produce first reactant 216. First reactant 216 is a vaporized portion of inerted fuel 208 located within vaporizer container 210. The first reactant 216 is mixed with a second reactant 218 that is derived from a second reactant source 220. The second reactant 218 is oxygen-containing air that is catalyzed by the first reactant 216 to produce inert gas that is to be supplied into the ullage 206 of the tank 202. The second reactant 218 may be from any source on the aircraft that is at a pressure greater than ambient pressure, including, but not limited to bleed air from an engine, cabin air, high pressure air extracted or bled from the engine, etc. (i.e., any second reactant source 220 may take on any number of configurations and/or arrangements). The first reactant 216 and the second reactant 218 within the evaporator vessel 210 may be directed into the catalytic reactor 222 by a mixer 224, which may be an eductor or a jet pump in some embodiments, and/or via the mixer 224. The mixer 224 will mix the first reactant 216 and the second reactant 218 into a mixed gas stream 225.

The catalyst 222 may be temperature controlled to ensure a desired chemical reaction efficiency such that inert gas may be efficiently generated from the mixed gas stream 225 by the inerting system 200. Accordingly, cooling air 226 may be provided to extract heat from catalytic reactor 222 to provide desired thermal conditions for chemical reactions within catalytic reactor 222. The cooling air 226 may originate from a source of cool air 228. The catalytic mixture 230 exits the catalytic reactor 222 and passes through a heat exchanger 232. The heat exchanger 232 acts as a condenser on the catalytic mixture 230 to separate the inert gas 234 from the byproducts 236. Cooling air is supplied into the heat exchanger 232 to achieve the condensing functionality. In some embodiments, as shown, the cooling air 226 may originate from the same source of cooling air 228 as is provided to the catalytic reactor 222, but in other embodiments the sources of cooling air for the two components may be different. The by-product 236 may be liquid water or water vapor, and thus in the current configuration shown in fig. 2, a water separator 238 is provided downstream of the heat exchanger 232 to extract liquid water or water vapor from the catalytic mixture 230, thus leaving only the inert gas 234 provided to the ullage 206 of the tank 202.

The inerting system 200 may include additional components including, but not limited to, a fan 240, a flame arrestor 242, and a controller 244. Various other components may be included without departing from the scope of the present disclosure. Additionally, in some embodiments, some of the included components may be optional and/or removed. For example, in some arrangements, the fan 240 and/or the water separator 238 may be omitted. The controller 244 may be in operative communication with one or more sensors 246 and valves 248 to enable control of the inerting system 200.

In one non-limiting example, flammability reduction is achieved by inerting system 200 by initiating a chemical reaction between oxygen (second reactant 218) and fuel vapor (first reactant 216) using catalytic reactor 222 to produce carbon dioxide (inert gas 234) and water in the vapor phase (byproduct 236). The source of the second reactant 218 (e.g., oxygen) used in the reaction may be from any source on the aircraft that is at a pressure greater than ambient pressure. The fuel vapor (first reactant 216) is generated by draining a small amount of fuel 204 from a fuel tank 202 (e.g., a main aircraft fuel tank) into the evaporator reservoir 210. An electric heater 214 is used to heat the inert fuel 208 within the evaporator vessel 210. In some embodiments, the first reactant 216 (e.g., fuel vapor) is removed from the vaporizer container 210 by using the mixer 224 to initiate a suction pressure that draws the first reactant 216 (e.g., fuel vapor) from the vaporizer container 210. In such embodiments, the mixer 224 utilizes the high pressure of the second reactant source 220 to induce a secondary flow within the mixer 224 that originates from the evaporator vessel 210. In addition, as noted above, a mixer 224 is used to mix the two streams of gas (first reactant 216 and second reactant 218) together to form a mixed gas stream 225.

The mixed gas stream 225 (e.g., fuel vapor and oxygen or air) is then introduced into the catalytic reactor 222, initiating a chemical reaction that converts the mixed gas stream 225 (e.g., fuel and air) into inert gas 234 and byproducts 236 (e.g., carbon dioxide and water vapor). Note that any inert gas species (e.g., nitrogen) present in the mixed gas stream 225 will not react and therefore will pass unchanged through the catalytic reactor 222. In some embodiments, catalytic reactor 222 is sized and shaped to function as a heat exchanger. For example, one non-limiting configuration may be a plate-fin heat exchanger, wherein the hot side of the heat exchanger is to be coated with a catalyst material. Those skilled in the art will appreciate that various types and/or configurations of heat exchangers may be employed without departing from the scope of the present disclosure. The cold side of the catalyst heat exchanger may be fed with cooling air 226 from a cold air source 228 (e.g., ram air or some other cold air source). The air passing through the cold side of the catalyst heat exchanger may be controlled such that the temperature of the hot mixed gas stream 225 is hot enough to maintain the desired chemical reaction within the catalytic reactor 222, but cold enough to remove the heat generated by the exothermic reaction, thus maintaining aircraft safety and keeping the materials from exceeding the maximum temperature limit.

As noted above, the chemical reaction process within catalytic reactor 222 may produce byproducts, including water in vapor form. It may be undesirable to have water (in any form) enter the tank 202. Thus, the water byproduct 236 may be removed from the product gas stream (i.e., inert gas 234) by condensation. To this end, the catalytic mixture 230 is passed into a heat exchanger 232 that is used to cool the catalytic mixture 230 so that byproducts 236 may be removed (e.g., most of the water vapor condenses and falls from the catalytic mixture 230). The by-product 236 (e.g., liquid water) may then be drained. An optional water separator 238 may be used to accomplish this function.

A flow control valve 248 downstream of the heat exchanger 232 and optional water separator 238 may measure the flow of inert gas 234 to a desired flow rate. An optional booster fan 240 may be used to raise the gas flow pressure of the inert gas 234 to overcome the pressure drop associated with the conduit between the outlet of the heat exchanger 232 and the discharge point of the inert gas 234 into the tank 202. Flame arrestor 242 at the inlet of tank 202 is arranged to prevent any possible flame from propagating into tank 202.

Generally, an aircraft fuel tank (e.g., fuel tank 202) needs to be in communication with the environment independent of any aircraft flammability reduction system. Thus, as shown in fig. 2, the tank 202 includes a vent 250. At high altitudes, the pressure inside the tank 202 is very low and approximately equal to ambient pressure. However, during descent, the pressure inside the tank 202 needs to rise to be equal to the ambient pressure at sea level (or at any altitude at which the aircraft lands). This requires gas to enter the tank 202 from the outside to equalize the pressure. As air enters the tank 202 from the outside, water vapor may be carried into the tank 202 by the ambient air. To prevent water/steam from entering tank 202, inerting system 200 may repressurize tank 202 with inert gas 234 generated by inerting system 200. This is accomplished through the use of valve 248. For example, one of the valves 248 may be a flow control valve 252 fluidly disposed downstream of the catalytic reactor 222. The flow of inert gas 234 into the tank 202 may be controlled using a flow control valve 252 so that a slight positive pressure is always maintained in the tank 202. Such positive pressure may prevent ambient air from entering the tank 202 from the outside during descent and thus prevent water from entering the tank 202.

As noted above, the controller 244 may be operably connected to various components of the inerting system 200, including but not limited to the valve 248 and the sensor 246. The controller 244 may be configured to receive input from the sensor 246 to control the valve 248 and thus maintain the appropriate level of inert gas 234 within the ullage 206. In addition, the controller 244 may be arranged to ensure a suitable amount of pressure within the tank 202 such that ambient air does not enter the ullage 206 of the tank 202 during descent of the aircraft.

In some embodiments, the inerting system 200 may supply inert gas to a plurality of fuel tanks onboard the aircraft. As shown in the embodiment of fig. 2, an inerting supply line 254 fluidly connects the tank 202 to the evaporator vessel 210. After the inert gas 234 is generated, as schematically shown, the inert gas 234 will flow through a tank supply line 256 to supply the inert gas 234 to the tank 202 and optionally to an additional tank 258.

Turning now to fig. 3, an embodiment of an inerting system 300 in accordance with the present disclosure is shown. The inerting system 300 may be similar to that shown and described above, and thus similar features may not be shown or discussed for simplicity. The inerting system 300 enables the removal of a heater for vaporizing the inerted fuel within the evaporator vessel.

As shown, the inerting system 300 includes a tank 302 having fuel 304 therein, wherein a ullage 306 is formed as the fuel 304 is consumed during use. As described above, the inerting supply line 354 fluidly connects the oil tank 302 to the evaporator vessel 310. The amount of fuel 304 (i.e., the amount of inerted fuel 308) extracted into the evaporator tank 310 may be controlled by operation of the evaporator tank valve 312 (such as a float valve) and/or the controller 344 and/or by control by the controller 344. The inerted fuel 308 is vaporized to produce a first reactant 316 for use within the catalytic reactor 322. As described above, the second reactant may be derived from the second reactant source 320. The first reactant and the second reactant react within the catalytic reactor 322 to produce an inert gas for supply into one or more fuel tanks (e.g., fuel tank 302).

In this embodiment, a source of cold air 328 (such as ram air) is provided to effect cooling of the catalytic reactor 322 and to effect a condensing function within the heat exchanger 332, as described above. As described above, the heat exchanger 332 acts as a condenser on the catalytic mixture to separate inert gas from byproducts. In this embodiment, the cooling air originates from the same source 328 of cool air as is provided to the catalytic reactor 322.

To provide thermal energy for vaporizing inerting fuel 308, thermal energy may be supplied from catalytic reactor 322 rather than using a heater element or device. That is, the hot air 360 generated by the exothermic reaction at the catalytic reactor 322 may be directed into and/or through the evaporator vessel 310 via the heating conduit 362. The heating conduit 362 may pass through the interior of the evaporator vessel 310, may wrap around the evaporator vessel 310, and/or may have another arrangement such that thermal energy within the hot air 360 may be transferred into the inerted fuel 308 to thereby vaporize the inerted fuel 308. Advantageously, such a configuration may reduce the weight of the system by eliminating the heater shown in fig. 2.

Various embodiments provided herein are directed to the removal of a heater (e.g., heater 214 shown in fig. 2). One arrangement is shown in fig. 3, using excess heat from the catalytic reactor. In other embodiments, as described below, direct injection of fuel from the fuel tank may be employed. Thus, such systems (such as those shown in fig. 4-7) may employ direct injection systems having various configurations. In such embodiments, the typical heater is removed and the first reactant is sourced directly from the oil tank or evaporator vessel.

Turning now to fig. 4, an embodiment of an inerting system 400 in accordance with the present disclosure is shown. The inerting system 400 may be similar to that shown and described above, and thus similar features may not be shown or discussed for simplicity. The inerting system 400 enables the removal of a heater for vaporizing the inerted fuel within the evaporator vessel.

As shown, inerting system 400 includes a tank 402 having fuel 404 therein, wherein a ullage 406 is formed as fuel 404 is consumed during use. As described above, the inerting supply line 454 fluidly connects the oil tank 402 to the evaporator vessel 410. The amount of fuel 404 (i.e., the amount of inerted fuel 408) that is extracted into the evaporator tank 410 may be controlled by operation of the evaporator tank valve 412 (such as a float valve) and/or the controller 444 and/or by control by the controller 444. Rather than vaporizing the inerted fuel 408 prior to feeding the inerted fuel 408 into the catalytic reactor 422, a portion of the inerted fuel 408 within the evaporator tank vessel 410 may be extracted in liquid form and subsequently injected into a gas stream where it is vaporized. In one such embodiment, as shown in fig. 4, a gravity supply line 464 may fluidly connect the vaporizer container 410 to a supply line of the second reactant source 420 supply line, as schematically shown. As the inerted fuel 408 enters the supply line, the fuel vaporizes to produce a first reactant. The first reactant and the second reactant react within the catalytic reactor 422 to produce an inert gas for supply into one or more fuel tanks (e.g., fuel tank 402). Similar to the previous embodiments, a source of cold air 428 (such as ram air) is provided to effect cooling of the catalytic reactor 422 and condensation within the heat exchanger 432, as described above. As described above, the heat exchanger 432 acts as a condenser on the catalytic mixture to separate inert gas from byproducts. In this embodiment, the cooling air originates from the same source 428 of cold air as is provided to the catalytic reactor 422. Because the inerted fuel 408 is gravity fed into and vaporized in the supply line of the second reactant 420, there is no need to install a heater within the vaporizer container 410 or to install a heater on the vaporizer container 410. That is, the inerted fuel 408 is injected directly into the second reactant to produce a composition that will react within the catalytic reactor 422.

Turning now to fig. 5, an embodiment of an inerting system 500 in accordance with the present disclosure is shown. The inerting system 500 may be similar to that shown and described above, and thus similar features may not be shown or discussed for simplicity. The inerting system 500 enables the removal of a heater for vaporizing the inerted fuel within the evaporator vessel.

As shown, the inerting system 500 includes a tank 502 having fuel 504 therein, wherein a ullage 506 is formed as the fuel 504 is consumed during use. As described above, the inerting supply line 554 fluidly connects the oil tank 502 to the evaporator vessel 510. The amount of fuel 504 (i.e., the amount of inerted fuel 508) that is extracted into the evaporator tank 510 may be controlled by operation of the evaporator tank valve 512 (such as a float valve) and/or the controller 544 and/or by control by the controller 544. Rather than vaporizing the inerted fuel 508 prior to feeding the inerted fuel 508 into the catalytic reactor 522, the inerted fuel 508 may be vaporized and injected using the injector pump 566, which also serves to mix the vaporized inerted fuel 508 (first catalyst) with the second reactant provided from the second reactant source 520. The first reactant and the second reactant react within catalytic reactor 522 to produce an inert gas for supply into one or more fuel tanks (e.g., fuel tank 502). Similar to the previous embodiments, a source of cold air 528 (such as ram air) is provided to effect cooling of the catalytic reactor 522 and condensation function within the heat exchanger 532, as described above. As described above, the heat exchanger 532 acts as a condenser on the catalytic mixture to separate inert gas from byproducts. Because inerted fuel 508 is vaporized as it passes through injector pump 566, there is no need to install a heater within evaporator tank 510 or to install a heater onto evaporator tank 510. That is, the inerted fuel 508 is injected directly into the second reactant to produce a composition that will react within the catalytic reactor 522.

In some embodiments, the syringe pump 566 includes two or more separate elements that provide specific functions. For example, as shown in fig. 5, the syringe pump 566 includes: a pump 566a arranged to pump inerted fuel 508 to a high pressure; and an injector/mixer 566b arranged to inject inerted fuel 508 into the gas stream from the second reactant source 520.

Turning now to fig. 6A-6B, an embodiment of an inerting system 600 in accordance with the present disclosure is shown. The inerting system 600 may be similar to that shown and described above, and thus similar features may not be shown or discussed for simplicity. The inerting system 600 enables the removal of a heater for vaporizing inerted fuel in the evaporator vessel.

As shown, the inerting system 600 includes a tank 602 having fuel 604 therein, wherein a ullage 606 is formed when fuel 664 is consumed during use. In contrast to the embodiments described above, the inerting supply line 654 fluidly connects the tank 602 directly to the catalytic reactor 622. In this embodiment, a fuel pump assembly 668 is mounted within or along an inerting supply line 654 for vaporizing inerted fuel oil (from fuel oil 604) and mixing with the second reactant from the second reactant source 620, wherein the mixture is supplied to the catalytic reactor 622 for catalysis. Operation of the fuel pump assembly 668 may be controlled by the controller 644.

Fig. 6B shows schematic details of the fuel pump assembly 668. As shown, fuel is pumped from the tank 602 using a fuel pump 668a that injects fuel into the high pressure air supply nozzle 668b. The high pressure gas supply nozzle 668b will vaporize the fuel 604 which is then mixed with the second reactant supplied from the second reactant source 620 in the mixing chamber 668 c. The mixture is then supplied to a catalytic reactor 622. In the configuration shown in fig. 6B, as schematically shown, a quantity of air from the second reactant source 620 will be supplied to the high pressure air supply nozzle 668B.

It will be appreciated that fig. 6B is merely illustrative, and that it is not limiting. Those skilled in the art will appreciate that the illustrative arrangement shown in fig. 6B is an example, and that other arrangements and/or configurations are possible without departing from the scope of the present disclosure. For example, a single stage pump/injector may be used, wherein all fuel (first source) is directly injected into all air (second source) in a single step.

Turning now to fig. 7, an embodiment of an inerting system 700 in accordance with the present disclosure is shown. The inerting system 700 may be similar to that shown and described above, and thus similar features may not be shown or discussed for simplicity. The inerting system 700 enables the removal of a heater for vaporizing inerted fuel in the evaporator vessel.

As shown, the inerting system 700 includes a tank 702 having fuel 704 therein, wherein a ullage 706 is formed as the fuel 704 is consumed during use. As described above, the inerting supply line 754 fluidly connects the oil tank 702 to the evaporator vessel 710. The amount of fuel 704 (i.e., the amount of inerted fuel 708) that is extracted into the evaporator tank 710 may be controlled by operation of an evaporator tank valve (such as a float valve) and/or a controller 744 and/or by control by the controller 744. The inerted fuel 708 is vaporized within the vaporizer container 710 to produce a first reactant for use within the catalytic reactor 722. As described above, the second reactant may be derived from the second reactant source 720. The first reactant and the second reactant react within the catalytic reactor 722 to produce an inert gas for supply into one or more fuel tanks (e.g., fuel tank 702).

In this embodiment, rather than using a heater element or device, thermal energy may be supplied from the second reactant source 720 in order to provide thermal energy for vaporizing the inerted fuel 708. That is, relatively warm air (such as bleed air from a turbine engine) may be directed into and/or through the evaporator vessel 710 via the heating conduit 770. The heating conduit 770 can pass through the interior of the evaporator vessel 710, can wrap around the evaporator vessel 710, and/or can have another arrangement such that thermal energy within the heating conduit 770 can be transferred into the inerted fuel 708 to thereby vaporize the inerted fuel 708.

While heat is provided to the inerted fuel to produce the first reactant (e.g., vaporization of the fuel), the catalyst of the system is exothermic and thus produces heat. Thus, it may be desirable to control the temperature so that the system does not overheat and/or so that a catalytically effective temperature for the first and second reactants may be maintained within the catalyst. To achieve such temperature control, various systems are provided herein.

Turning now to fig. 8, an embodiment of an inerting system 800 in accordance with the present disclosure is shown. The inerting system 800 may be similar to that shown and described above, and thus similar features may not be shown or discussed for simplicity. The inerting system 800 employs various sources of air to cool one or both of the catalytic reactor 822 and/or the heat exchanger 832. That is, the cold air source 828 may replace a typical ram air source.

As shown, the inerting system 800 includes a tank 802 having fuel 804 therein, wherein a ullage 806 is formed as the fuel 804 is consumed during use. As described above, the inerted supply line fluidly connects the oil tank 802 to the evaporator vessel 810. The amount of fuel 804 (i.e., the amount of inerted fuel 808) that is extracted into the evaporator tank 810 may be controlled by operation of the evaporator tank valve and/or controller 844 and/or by control by the controller 844. In this illustrative embodiment, heater 814 is used to vaporize inerted fuel 808 to produce a first reactant. The second reactant originates from the second reactant source 820 and the first reactant is mixed with the second reactant. The mixed first reactant and second reactant react within the catalytic reactor 822 to produce an inert gas for supply to one or more fuel tanks (e.g., fuel tank 802). The reactions occurring within the catalytic reactor 822 generate heat, with the hot catalytic products flowing into the heat exchanger 832. As noted above, the cooling used for the catalytic reactor 822 and/or the heat exchanger 832 (e.g., for cold air supply and heat transfer) is typically ram air.

In this embodiment, the cold air source 828 is not ram air, but is instead sourced from another location on the aircraft. For example, in some embodiments, the cold air source 828 may be vented from an environmental control system of the aircraft. The use of outlet air from the environmental control system may enable condensation of more water in the inert gas stream and prevent such water vapor from flowing into the oil tank 802. In another embodiment, the cold air source 828 may be vented from the cabin of the aircraft. In such embodiments, the use of cabin air may reduce ram air bleed and thus reduce aircraft drag. In either arrangement, a source of cold air 828 is provided to effect cooling of the catalytic reactor 822 and condensation within the heat exchanger 832, as described above. As described above, the heat exchanger 832 acts as a condenser on the catalytic mixture to separate inert gas from byproducts.

Another method of controlling the temperature within the fuel inerting system is to rearrange the catalyst and heat exchanger arrangement. For example, turning now to fig. 9, an embodiment of an inerting system 900 in accordance with the present disclosure is shown. The inerting system 900 may be similar to that shown and described above, and thus similar features may not be shown or discussed for simplicity. The inerting system 900 employs a modified arrangement of catalytic reactor 922 and heat exchanger 932. In this embodiment, the cold air source 928 may be a typical ram air source arrangement.

As shown, the inerting system 900 includes a tank 902 having fuel 904 therein, wherein a ullage 906 is formed as the fuel 904 is consumed during use. As described above, the inerted supply line fluidly connects the oil tank 902 to the evaporator vessel 910. The amount of fuel 904 extracted into the evaporator vessel 910 (i.e., the amount of inerted fuel 908) may be controlled by operation of the evaporator vessel valve and/or controller 944 and/or by control by the controller 944. In this illustrative embodiment, heater 914 is used to vaporize inerted fuel 908 to produce the first reactant. The second reactant originates from the second reactant source 920 and the first reactant is mixed with the second reactant. The mixed first reactant and second reactant react within catalytic reactor 922 to produce an inert gas for supply to one or more fuel tanks (e.g., fuel tank 902). Similar to the above, water vapor may be condensed from the catalyzed gas by passing it through a heat exchanger 932.

However, in the present embodiment, rather than the catalyst being adjacent to the heat exchanger so that the two components may be supplied with cooling air in succession to each other, the catalytic reactor 922 is disposed downstream of the heat exchanger 932. Thus, the cooling flow from the cold air source 928 may provide the coldest air to the heat exchanger 932, and the warmer air may flow out of the heat exchanger 932 into the catalytic reactor 922 and achieve temperature control within the catalytic reactor 922. Typically, the fuel tank is inerted using a catalyst cooled by ram air, which during cruising operation needs to be significantly reduced so that the temperature of the air exiting the cold side outlet of the catalyst may be too high. In the arrangement shown in fig. 9, the airflow through the ram circuit may be increased such that the exhaust gas on the cold side of the catalytic reactor 922 (after passing through the heat exchanger 932) may be maintained below 450°f.

Turning now to fig. 10, an embodiment of an inerting system 1000 in accordance with the present disclosure is shown. The inerting system 1000 may be similar to that shown and described above, and thus similar features may not be shown or discussed for simplicity. In this embodiment, the inerting system 1000 employs ambient air as the second reactant source 1020, as compared to typical bleed air sources used in several of the arrangements described above. Bleed air may supply pressurized air and oxygen to the inerting system 1000. However, it may be advantageous to reduce or remove the amount of bleed air in an aircraft system, as such a reduction may increase fuel efficiency and/or reduce the need to install ducting within the aircraft for supplying bleed air to the fuel inerting system.

As shown, the inerting system 1000 includes a tank 1002 having fuel 1004 therein, wherein a ullage 1006 is formed as the fuel 1004 is consumed during use. As described above, the inerted supply line fluidly connects the oil tank 1002 to the evaporator vessel 1010. The amount of fuel 1004 (i.e., the amount of inerted fuel 1008) that is drawn into the evaporator tank 1010 may be controlled by operation of the evaporator tank valve and/or controller 1044 and/or by control by the controller 1044. In this illustrative embodiment, heater 1014 is used to vaporize inerted fuel 1008 to produce a first reactant. The second reactant originates from a second reactant source 1020, which in this embodiment is ambient air. The first reactant is mixed with the second reactant and then reacted within catalytic reactor 1022 to produce an inert gas for supply to one or more fuel tanks (e.g., fuel tank 1002). In this embodiment, the second reactant source 1020 is not bleed air, but rather ambient air originating from outside the aircraft. In this arrangement, a blower or fan 1072 is disposed in or along the flow line of the second reactant source 1020 and ambient air can be drawn through the system, thus removing the use of bleed air.

Turning now to fig. 11, an arrangement of an inerting system 1100 in accordance with an embodiment of the present disclosure is shown. The inerting system 1100 may be similar to that shown and described above, and thus similar features may not be shown or discussed for simplicity. In this embodiment, the inerting system 1100 employs a back pressure restrictor 1174 located within or along the tank supply line 1156 downstream of the catalytic reactor 1122.

As shown, inerting system 1100 includes a tank 1102 having fuel 1104 therein, wherein a ullage 1106 is formed as fuel 1104 is consumed during use. An inerting supply line 1154 is fluidly connected to tank 1102 to supply inerting fuel and/or first reactant to catalytic reactor 1122. As shown, in this embodiment, a fuel pump assembly 1168 (e.g., similar to the fuel pumps shown and described in fig. 6A-6B) is mounted within or along the inerted supply line 1154. The second reactant is from a second reactant source 1120, wherein a mixture of the first reactant and the second reactant is supplied to a catalytic reactor 1122 for catalysis. Operation of the fuel pump assembly 1168 may be controlled by the controller 1144.

To condense and remove water vapor, the minimum condenser temperature within heat exchanger 1132 will be slightly above freezing. For condensation at atmospheric pressure, this temperature will result in about 0.6 mole percent water vapor in the saturated gas stream exiting heat exchanger 1132, since the saturated vapor pressure of H2O at temperatures just above freezing is about 0.6 kPa (and the atmospheric pressure is about 100 kPa). Because the H2O saturated vapor pressure is a function of temperature only (and not of total pressure), at higher total pressures the mole fraction of water vapor becomes smaller, i.e., the gas stream exiting heat exchanger 1132 dries out. For example, at a pressure of 10 atm (about 1000 kPa), the mole fraction of water vapor in the saturated gas stream exiting heat exchanger 1132 will be about 0.06%. Thus, higher pressure operation is advantageous in keeping the fuel system dry, as a drier air stream will be supplied to the ullage 1106 in the tank 1102. In addition, operating the catalytic reactor 1122 and heat exchanger 1132 at higher pressures will reduce the size required for these components, as the working fluid (gas) will become denser, and as the rate of heat transfer per unit surface area will increase with pressure (with working fluid density and reynolds number).

The embodiment of fig. 11 enables inerting system 1100 to operate at a higher pressure than the pressure within tank 1102. The increased pressure may enable a reduction in the desired size of catalytic reactor 1122 and/or heat exchanger 1132 and also provide a drier inert gas flow that is returned to tank 1102. To operate at higher pressures, liquid fuel from the fuel tank 1102 is pumped to higher pressures by the fuel pump assembly 1168 for delivery to the catalytic reactor 1122 and a high pressure second reactant source 1120 (such as from an aircraft engine) is provided to catalytically oxidize the fuel. A back pressure restrictor 1174 is provided to regulate the operating pressure of the inerting system 1100, particularly at the catalytic reactor 1122 and heat exchanger 1132. The back pressure restrictor 1174 may be configured to be actively controlled by the controller 1144 or may be a passive valve. In some embodiments, the back pressure restrictor 1174 may be a throttle valve, an electronically controlled valve (e.g., pneumatic control using feedback), a passive orifice or restrictor in the flow line, a mechanical valve, or other type of restrictor, as will be appreciated by those skilled in the art. In some embodiments, the controlled backpressure restrictor may be controlled in response to an operating condition of the aircraft.

The back pressure restrictor 1174 is arranged to maintain high pressure operation of the catalytic reactor 1122 and the heat exchanger 1132. The increased pressure provided by the backpressure restrictor 1174 enables more efficient removal of water from the inerting system 1100. As shown, the backpressure restrictor 1174 is located downstream of the catalytic reactor 1122 and the heat exchanger 1132, and in this embodiment downstream of the water separator 1138, but in some embodiments the water separator 1138 may be omitted. Additionally, in some embodiments including a water separator, a backpressure valve may be located downstream of the catalytic reactor 1122 and heat exchanger 1132 but upstream of the water separator 1138.

Turning now to fig. 12, an arrangement of an inerting system 1200 in accordance with an embodiment of the present disclosure is shown. The inerting system 1200 may be similar to that shown and described above, and thus similar features may not be shown or discussed for simplicity. In this embodiment, the inerting system 1200 employs an inert gas recirculation system 1276 that is located within or along the tank supply line 1256 downstream of the catalytic reactor 1222. As schematically shown in fig. 12, the catalytic reactor 1222 has a different dimensional profile than other embodiments shown and described herein. For example, as shown, the catalytic reactor is a simple monolithic structure.

As shown, the inerting system 1200 includes a tank 1202 having a fuel 1204 therein, wherein a ullage 1206 is formed when the fuel 1204 is consumed during use. An inerting supply line 1254 fluidly connects the tank 1202 to supply inerting fuel and/or first reactant to the catalytic reactor 1222. As described above, the reaction between the first reactant and the second reactant (e.g., air and fuel) in the catalytic reactor 1222 returns inert gas to the tank 1202 (with or without water condensation and removal). Ideally, the gas flow back to the tank 1202 will have zero or minimal O2 (to maximize inerting), which will require near stoichiometric reaction between the first reactant (e.g., fuel) and the second reactant (e.g., air).

Unfortunately, reactions of fuel under near stoichiometric conditions may result in significant heat release and overheating of the catalytic reactor 1222. In some embodiments, to prevent such overheating, a portion of the product stream exiting the catalytic reactor 1222 may be cooled and the cooled portion mixed with the first and second reactants before they react at the catalytic reactor 1222. That is, upstream of the catalytic reactor 1222, the recirculation system 1276 may supply a recirculated product stream into the mixture of the first reactant and the second reactant. In some embodiments, the recycled product may have the same composition as the gas exiting the catalytic reactor 1222. In other embodiments, if condensed water is first and removed (separated) from the existing gas, the recycled product supplied through the recycling system 1276 may have a different composition. Additionally, in some embodiments, if water is condensed and separated, the water itself may be recycled to the catalytic reactor 1222, or a water-free gas stream (e.g., containing CO2 and N2) may be recycled to the catalytic reactor 1222.

Although the recirculation system 1276 is shown in fig. 12 as being downstream or after the water separator 1238, in some embodiments the water separator may be downstream of the recirculation system. That is, in some embodiments, the water separator may be placed in a line leading to the tank, but after extraction of the recycle stream. Those skilled in the art will appreciate that the location of the extraction point of the recirculation system may be located anywhere along the fluid lines of the systems described herein. Such an arrangement may allow water to be recycled to the catalyst (to assist in cooling the catalyst) and allow water to be removed before delivering dry inert gas (or dry low oxygen gas) to the ullage of the tank. Additionally, in some embodiments, a portion of the extracted water may be added to the recycle stream (or directly delivered to the catalyst) wherever the water is removed from the line to help keep the catalyst cold.

Regardless of the source or composition of the recycled product, it is possible to operate the catalytic reactor 1222 at a safe temperature when the fuel and air are catalytically reacted at near stoichiometric conditions. For example, by cooling and recycling a portion of the product stream to act as a diluent during the reaction, the temperature rise associated with the reaction of fuel with air may be reduced. In addition, if desired, the recycle product stream (e.g., cold diluent) can be used as a sparging gas to deliver fuel vapor to the catalyst.

For example, turning now to fig. 13, an arrangement of an inerting system 1300 in accordance with an embodiment of the present disclosure is shown. The inerting system 1300 may be similar to that shown and described above, and thus similar features may not be shown or discussed for simplicity. In this embodiment, the inerting system 1300 employs an inert gas recirculation system 1376 located within or along a tank supply line 1356 downstream of the catalytic reactor 1322, but may supply the recirculated product stream to the evaporator vessel 1310.

As shown, the inerting system 1300 includes a tank 1302 having fuel 1304 therein, wherein a ullage 1306 is formed when the fuel 1304 is consumed during use. An inerting supply line 1354 fluidly connects the oil tank 1302 to the evaporator vessel 1310 to produce inerted fuel and/or first reactant for supply to the catalytic reactor 1322. As described above, the reaction between the first reactant and the second reactant (e.g., air and fuel) in the catalytic reactor 1322 returns inert gas to the tank 1302 (with or without water condensation and removal).

Similar to the embodiment shown in fig. 12, inerting system 1300 includes a recycling system 1376. In this case, the recirculation system 1376 deflects a portion of the product stream exiting the catalytic reactor 1322 away from the tank supply line 1356. The extracted product is supplied to an evaporator vessel 1310. As shown, the return line 1378 may be arranged to circulate a portion of the fuel within the evaporator reservoir 1310 back to the fuel tank 1302. In this embodiment, the recycle gas will flow through the recycle system 1376 and into the evaporator vessel 1310 to perform the injection. Thus, the recycle gas attributes the fuel vapor to the formed injection gas, and the injection gas/fuel vapor mixer will then mix with air and be delivered to the catalytic reactor 1322.

While the recirculation flow is all directed to and through the nebulizer (i.e., vaporizer container 1310) as shown herein, the disclosure is not so limited. For example, in some non-limiting embodiments, a portion of the recycle stream is directed through the sparger and the remainder of the recycle stream is directly fed to the catalyst (i.e., bypassing the sparger and being directly fed to catalyst 1322). That is, in some embodiments, two recirculation lines may be employed that combine the arrangements shown in fig. 12-13. In such embodiments, by allowing only a small portion of the recirculation flow through the nebulizer, the nebulizer flow rate can be adjusted as needed independent of the recirculation flow rate.

In any of the embodiments shown in fig. 12-13, the recycled product (e.g., inert gas) is recycled to the inlet of the catalytic reactor. The inert gas may act as a heat sink and no reaction takes place within the catalytic reactor. Because the recycled product will not react with the catalytic reactor (i.e., no chemical reaction), the portion of the gas flowing into and through the catalytic reactor will not generate heat. Thus, the fuel gas mixture of the first and second reactants will be diluted, which will thus reduce the temperature within the catalytic reactor.

In some embodiments, the recirculation system 1276, 1376 includes a pump or blower arranged to force a portion of the product stream back upstream of the respective catalytic reactor 1222, 1322. Additionally, one or more valves may be part of the recirculation system 1276, 1376 for controlling the volume of bleed product from tank supply lines 1256, 1356. In some embodiments, an ejector pump or injector pump may be located upstream of the catalytic reactor, with a flow line connected downstream of the catalytic reactor, the ejector pump or injector pump drawing the product back to an upstream location. In some embodiments, a blower may be disposed downstream of the catalytic reactor, wherein the blower is disposed to withdraw a portion of the product stream and blow a portion of the product stream back upstream of the catalytic reactor. In some embodiments, as described above, the controller may be arranged to control the amount of product stream recycled as compared to the amount supplied into the oil head space.

The recirculation system provided herein may be arranged to recirculate any given or predetermined ratio or percentage. For example, in a non-limiting example, there may be fifty parts of the reacted product stream that may be recycled for each part that is supplied into the oil head space. This is merely an example, and in some embodiments, up to 99% of the reacted product stream may be recycled, with only 1% being supplied into the oil head space. In contrast, on the other hand, a very low percentage (such as 5% or less) of the reacted product stream may be recycled, with 95% or more of the reacted product stream being supplied to the ullage.

Turning now to fig. 14, an arrangement of an inerting system 1400 in accordance with an embodiment of the present disclosure is shown. The inerting system 1400 may be similar to that shown and described above, and thus similar features may not be shown or discussed for simplicity. In this embodiment, the inerting system 1400 employs a fuel vaporization system 1480. The fuel vaporization system 1480 is arranged to transfer fuel 1404 from the aircraft fuel tank 1402 into a reservoir 1482 that is arranged to perform an injection. The amount of fuel 1404 entering the reservoir 1482 is measured by the reservoir valve 1412. Air is introduced from air source 1484 to a location below the fuel level within container 1482. Air introduction into the fuel may be accomplished through a nozzle or frit 1486 located within the reservoir 1482. Air will pass through the fuel in the form of bubbles and fuel vapor will vaporize into the bubbles. The combined fuel and air bubbles will be deposited in vapor space 1488 above the fuel level in container 1482, thus forming a vaporized fuel-air mixture in vapor space 1488. In some embodiments, the fuel-air mixture may be set by the temperature of the air entering the reservoir 1482 from the air source 1484 and/or controlled by the design of the nozzle or frit 1486. The fuel-air mixture within vapor space 1488 may then be used to feed catalytic reactor 1422. Additionally, as schematically illustrated, in some embodiments, a portion of the air from the air source 1484 may be directed to mix downstream of the vapor space 1488 prior to introduction (e.g., injection) into the catalytic reactor 1422. Downstream of the catalytic reactor 1422, the inerting system 1400 may be substantially similar to one or more of the embodiments described above.

Advantageously, embodiments of the present disclosure provide an efficient mechanism for generating inert gases and supplying such inert gases into the fuel tanks of an aircraft. Additionally, advantageously, embodiments provided herein may prevent ambient air (which may contain water) from entering an aircraft fuel tank. To prevent ambient air from entering the aircraft fuel tank, a controller of an inerting system as described herein may supply inert gas to the fuel tank to maintain a desired pressure (e.g., to provide a higher pressure within the fuel tank than ambient pressure). Such increased pressure may be employed within the tank to prevent the ingress of oxygen-enriched air (e.g., ambient air). This may be particularly useful when the ambient pressure increases with decreasing altitude during the descent phase of the aircraft voyage.

The use of the terms "a" and "an" and "the" and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The modifier "about" and/or "approximately" used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the particular quantity). All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other.

While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions, combinations, sub-combinations or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments.

Accordingly, the disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.

Claims

1. A tank inerting system for an aircraft, the system comprising:

an oil tank;

a first reactant source fluidly connected to the fuel tank, the first reactant source being arranged to receive fuel from the fuel tank;

a second reactant source;

a catalytic reactor arranged to receive a first reactant from the first reactant source and a second reactant from the second reactant source to produce an inert gas, the inert gas being supplied to the tank to fill a ullage of the tank; and

A source of cold air arranged to supply cold air to the catalytic reactor to provide thermal control of a reaction within the catalytic reactor, wherein the cold air is discharged from at least one of a cabin being the aircraft and an environmental control system of the aircraft.

2. The system of claim 1, wherein the first reactant source is an evaporator vessel.

3. The system of claim 1 or 2, wherein the second reactant source is at least one of a bleed port of an engine of an aircraft and the cabin of the aircraft.

4. The system of claim 1 or 2, further comprising a heat exchanger disposed between the catalytic reactor and the tank and configured to at least one of cool and condense an output from the catalytic reactor to separate inert gas from byproducts.

5. The system of claim 1 or 2, further comprising a heating conduit thermally connected to the catalytic reactor and arranged in thermal communication with the first reactant source to provide heat to the first reactant source to produce the first reactant.

6. The system of claim 1 or 2, further comprising a syringe pump arranged to receive the first reactant and the second reactant and to supply a mixture of the first reactant and the second reactant to the catalytic reactor.

7. The system of claim 1 or 2, further comprising an inert gas recirculation system downstream of the catalytic reactor and upstream of the oil tank, wherein the inert gas recirculation system is arranged to direct a portion of the inert gas to the catalytic reactor.

8. The system of claim 1 or 2, further comprising at least one additional tank, wherein the at least one additional tank is arranged to receive inert gas from the catalytic reactor.

9. The system of claim 1 or 2, further comprising a water separator located between the catalytic reactor and the tank and downstream of the catalytic reactor, the water separator being arranged to extract water from the reacted first and second reactants.

10. A method of supplying inert gas to an aircraft fuel tank, the method comprising:

Supplying fuel from a fuel tank to a first reactant source;

generating a first reactant within the first reactant source;

mixing the first reactant with a second reactant supplied from a second reactant source;

catalytically mixing the first reactant and the second reactant in a catalytic reactor to produce an inert gas;

supplying the inert gas to the tank to fill a head space of the tank; and

exhaust from at least one of a cabin of the aircraft and an environmental control system is supplied to a heat exchanger to enable cooling of an output from the catalytic reactor.

11. The method of claim 10, further comprising at least one of cooling and condensing an output from the catalytic reactor by the heat exchanger to separate inert gas from byproducts, the heat exchanger disposed between the catalytic reactor and the oil tank.

12. The method of claim 11, wherein the byproduct is water.

13. The method of any one of claims 10 to 12, further comprising heating the first reactant source using a heating conduit thermally connected to the catalytic reactor and arranged in thermal communication with the first reactant source to provide heat from the catalytic reactor to the first reactant source to produce the first reactant.

14. The method of any one of claims 10 to 12, further comprising mixing the first reactant with the second reactant and injecting using a syringe pump to supply the mixture of the first reactant and the second reactant to the catalytic reactor.

15. The method of any one of claims 10 to 12, further comprising recirculating a portion of the inert gas and supplying the recirculated portion to the catalytic reactor.

16. The method of any one of claims 10 to 12, further comprising using a water separator to extract water from the reacted first and second reactants, the water separator being located between the catalytic reactor and the tank and downstream of the catalytic reactor.