Fuel regulation and injection device for a combustion chamber

Abstract

An apparatus for injecting fuel into an air passage in which an airflow is directed toward a combustion chamber, the apparatus potentially having a fuel conditioning module configured to receive fuel. The fuel conditioning module defines a reactor chamber in which fuel is exposed to heat to at least partially decompose. A heat source is configured to exchange heat with the fuel in the reactor chamber to provide said heat to the fuel. A fuel injector module is in fluid communication with the fuel conditioning module and is located downstream of the reactor chamber, the fuel injector module having injection orifices leading to the air passage. The fuel injected into the air passage is at least partially decomposed. A method for operating a burner is also provided.

Description

Technical Field

[0001] This disclosure relates to a combustion chamber used in a gas turbine engine or a piston engine. More specifically, this disclosure relates to a fuel injection and fuel conditioning system for a combustion chamber. Background Technology

[0002] Gas turbines will be widely used in air transport due to their superior power density and reliability. While electrification is seen as a possible way to decarbonize passenger vehicles, heavy-duty and off-highway applications may continue to require piston engines due to the high energy density of liquid fuels. Gas turbines and piston engines will continue to evolve towards higher efficiency to mitigate their impact on climate change. Progress will also be made in the use of alternative fuels, such as biofuels, synthetic fuels, ammonia, and hydrogen, to further reduce greenhouse gas emissions. While these fuels may potentially provide net-zero carbon dioxide (CO2) emissions, nitrogen oxides (NOx) will still be emitted and represent gases harmful to humans and the environment.

[0003] It has been recognized that improving the efficiency of gas turbines can be achieved by increasing the pressure ratio (PR) for simple cycle gas turbines or the turbine inlet temperature (TIT) for regenerative gas turbines. Regenerative gas turbines are known to offer relatively high efficiency. Increasing the pressure ratio and / or using a regenerative cycle can result in a higher combustor inlet temperature (CIT), which precludes the use of lean-burn premixed low-NOx combustors, as detailed below. For piston engines, it should be recognized that improving their efficiency can be achieved by operating under lean-burn conditions. However, for spark-ignition (SI) engines, this is difficult without causing incomplete combustion, which can lead to high levels of unburned hydrocarbons (UHC) and carbon monoxide (CO) emissions, as well as lower engine efficiency. Compression-ignition (CI) engines can operate safely under lean-burn conditions due to their use of non-premixed combustion, but they produce relatively high levels of NOx and soot emissions.

[0004] Low NOx emissions are possible when using lean-burn premixed combustion systems, where fuel and air are uniformly mixed at a lean equivalence ratio before combustion. This allows for minimizing localized peak temperatures of the gas in the combustor, resulting in low NOx emissions due to the exponential effect of temperature on NOx formation. However, such combustors can suffer from undesirable effects (such as autoignition and / or flashback) if the mixing time is too long (leading to autoignition of the mixture) or the velocity is too low (leading to flame flashback upstream of the premixing unit). These undesirable effects can occur in the premixing section of the combustor. These problems can be exacerbated by: for reactive fuels (e.g., hydrogen), due to their rapid reaction time; for liquid fuels (e.g., diesel, methanol), due to delays associated with vaporization and liquid mixing; or at high combustor inlet temperatures (e.g., temperatures encountered by high compression ratios or regenerative gas turbines, e.g., combustor inlet temperatures above 900 K). Flame extinction (e.g., misfire) can also occur under lean-burn conditions, leading to a loss of efficiency.

[0005] As discussed earlier, lean combustion and high inlet temperatures are expected to emerge in future high-efficiency, fuel-flexible gas turbine and piston engines. For applications requiring very stable combustion under all operating conditions and with all fuels, premixed combustion may not be reliably used to provide low NOx and high-efficiency combustion systems. It should also be recognized that non-premixed (i.e., diffusion) combustion can offer greater stability and fuel flexibility, but at the cost of high NOx emissions, as combustion primarily occurs under stoichiometric (i.e., high-temperature) conditions within the fuel jet. Non-premixed combustion can also produce high particulate (i.e., soot) emissions, especially for liquid fuels, due to the pyrolysis of fuel droplets during combustion. Aftertreatment of exhaust gases using selective catalytic reduction (SCR) and particulate filters (PF) can be used to reduce NOx and soot emissions, but significant weight, performance losses, capital costs, and the use of additional consumables (urea) may make this technology impractical for aerospace or low-cost piston engines.

[0006] It has been shown that NOx emissions for non-premixed flames are proportional to the size of the fuel injector, meaning that NOx can be reduced when multiple miniaturized flames are used instead of several large flames. Systems using such miniaturized non-premixed flames (hereinafter referred to as micromixing combustion) have demonstrated premixed levels of NOx emissions under various fuel conditions and at high inlet temperatures (e.g., US 6,267585,B1, US 10,775,047 B2), making this approach attractive for applications requiring low NOx emissions and high reliability. In some cases, these systems may suffer from combustion instabilities in the form of miniaturized flame quenching due to increased strain rates at these smaller scales (e.g., when using low-reactive fuels or low combustor inlet temperatures). These results indicate a trade-off between NOx emissions and combustion stability for micromixing, where reducing the flame size results in lower NOx but is more prone to quenching. Although micromixing injectors can be designed to suppress these instabilities at the engine's design point, safe operation of the combustor may always be a trade-off with NOx emissions, especially when considering off-design operating margins. Furthermore, micromixing is limited to the use of gaseous fuels due to the delays associated with the mixing and vaporization of liquid fuels with air, and because liquids are several orders of magnitude denser than gases. If unvaporized liquid fuels are used, their high density can lead to lower injection velocities, resulting in poor mixing, long vaporization delays, and increased UHC, CO, and soot emissions. Finally, because micromixer injectors are designed to be small-scale, the micromixing flame is always located near the fuel injector and has a large specific surface area, resulting in significant heat transfer from the flame towards the fuel injector, requiring thermal management strategies to prevent damage.

[0007] Chemically decomposing fuel before mixing with air can produce favorable combustion characteristics because it forms dissociated matter (such as hydrogen), which increases the overall reactivity of the fuel. Previous micromixing systems (e.g., US 10,775,047B2) protected the injectors by using a thermal barrier coating (TBC) and carefully designed internal passages to use fuel for shock cooling. While this approach allows for “preheating” the fuel, these systems may not fully utilize the proximity of the fuel injector to the combustion gases. Other systems have sought to generate dissociated matter directly from the engine’s primary fuel source to improve operability and reduce emissions from gas turbine combustors. In some systems (e.g., US 6,453,660B1; US ​​2010 / 0300110A1), plasma generation devices or plasma reformers are used to generate dissociated matter directly from the engine’s primary fuel source; however, the electronics required for these systems introduce complexity and reliability issues. Other systems (e.g., US 5,165,224 A; US 5,207,053 A) use catalysts to induce fuel decomposition, which allows for increased fuel cooling capacity and reduced coking, but requires careful thermal management to avoid catalyst deactivation. Other systems (e.g., US 8,931,283 B2) use catalytic partial oxidation to generate highly reactive gases. However, catalytic partial oxidation is exothermic and requires thermal management to avoid catalyst deactivation, and it uses multiple fuel streams. All of these systems can be considered relatively complex, potentially leading to increased reliability issues.

[0008] Therefore, there is a need for a reliable combustor that can potentially reduce NOx emissions and provide relatively stable combustion under both design and non-design operating conditions of high-efficiency, high-power-density, and fuel-flexible gas turbine and piston engines. Attached Figure Description

[0009] Figure 1 A fully stirred reactor simulation is shown, which simulates the effect of preheated fuel on thermal decomposition into hydrogen and the resulting effect on improving flameout.

[0010] Figure 2 A longitudinal cross-sectional perspective view of a gas turbine combustor according to one aspect of the present disclosure is shown, illustrating possible embodiments of the fuel conditioning module, micro-mixing injection module, and heat transfer module according to the present disclosure;

[0011] Figures 3 to 10 These are schematic longitudinal cross-sectional views of various embodiments of this disclosure, including different embodiments of the fuel conditioning module, the micro-mixed fuel injector module, and the heat transfer module; and

[0012] Figure 11A cross-sectional view of a piston engine according to one aspect of this disclosure is shown, illustrating possible embodiments of a fuel conditioning module, a micro-hybrid module, and a heat transfer module. Summary of the Invention

[0013] According to a first aspect of this disclosure, an apparatus is provided for injecting fuel into an air passage in which an airflow is directed toward a combustion chamber. The apparatus includes: a fuel conditioning module configured to receive fuel, the fuel conditioning module defining a reactor chamber in which the fuel is exposed to heat for at least partial decomposition; a heat source configured to exchange heat with the fuel in the reactor chamber to provide said heat to the fuel; and a fuel injector module in fluid communication with the fuel conditioning module and located downstream of the reactor chamber, the fuel injector module having an injection orifice leading to the air passage; thereby, the fuel injected into the air passage is at least partially decomposed.

[0014] Further according to the first aspect, for example, the apparatus according to claim 1, wherein the heat source is a heat transfer module configured to be heated in the combustion chamber and release heat in the fuel conditioning module.

[0015] Furthermore, according to the first aspect, for example, the heat transfer module includes a heat transfer fluid.

[0016] Furthermore, according to the first aspect, for example, the injection orifice is located on an annular surface of the fuel injector module, which defines a portion of the air passage.

[0017] Furthermore, according to the first aspect, for example, the central axes of the plurality of injection orifices are radially oriented relative to the central axis of the annular surface.

[0018] Furthermore, according to the first aspect, for example, the air passage defines a flow area intercepted in a plane orthogonal to the vector of the direction of airflow, and wherein the surface density of the injection orifice is 5,000 to 500,000 holes per square meter of flow area, including endpoint values.

[0019] Furthermore, according to the first aspect, for example, the multiple injection orifices have a maximum cross-sectional dimension ranging from 0.1 to 1.0 mm, including endpoint values.

[0020] Furthermore, according to the first aspect, for example, the largest cross-sectional dimension is the diameter.

[0021] Furthermore, according to the first aspect, for example, an insulating gap is defined between the reactor chamber and the fuel injector module.

[0022] Furthermore, according to the first aspect, for example, the fuel injector module has a fuel manifold including an annular chamber, with the injection orifice in fluid communication with the annular chamber.

[0023] Furthermore, according to the first aspect, for example, the device includes at least two fuel injector modules, and the air passage between the two fuel injector modules is annular in shape.

[0024] Furthermore, according to the first aspect, for example, the device includes a fuel conditioning module for each of the fuel injector modules.

[0025] Furthermore, according to the first aspect, for example, the air passage is annular, and the cyclone blades are located in the air passage.

[0026] Furthermore, according to the first aspect, for example, the air mixer is in fluid communication with the fuel conditioning module to inject air or oxygen-containing gas into the fuel conditioning module.

[0027] Furthermore, according to the first aspect, for example, the air mixer is in fluid communication with the reactor chamber to inject air or oxygen-containing gas into the reactor chamber.

[0028] Furthermore, according to the first aspect, for example, at least one of the fuel conditioning module, heat source, and fuel injector module has an additively manufactured body to define an internal cavity in which the additively manufactured body receives fuel.

[0029] According to a second aspect of this disclosure, a method for operating a burner is provided, the method comprising: supplying fuel to a fuel conditioning module; exposing the fuel in the fuel conditioning module to heat to at least partially decompose the fuel; injecting the at least partially decomposed fuel into an air stream; and igniting a mixture of air and the at least partially decomposed fuel for combustion in a combustion chamber.

[0030] Further according to the second aspect, for example, the supply of fuel includes the supply of pure hydrogen, ammonia, methanol, ethanol, kerosene, gasoline, diesel, biofuel, or any other compound that is at least partially composed of the chemical element hydrogen.

[0031] Furthermore, according to the second aspect, for example, exposing the fuel in the fuel conditioning module to heat includes absorbing heat in the combustion chamber and releasing heat in the fuel conditioning module.

[0032] Furthermore, according to the second aspect, for example, supplying fuel includes supplying liquid fuel, and wherein exposing the fuel to heat includes vaporizing the liquid fuel.

[0033] Furthermore, according to the second aspect, for example, exposing the fuel to heat includes exposing the fuel to heat such that the fuel reaches a temperature of at least 600 K and up to 1500 K (including endpoint values).

[0034] Furthermore, according to the second aspect, for example, exposing the fuel in the fuel conditioning module to heat includes exposing the fuel to resistance heating, infrared heating, and / or induction heating.

[0035] Furthermore, according to the second aspect, for example, air or oxygen-containing gas can be injected into the fuel conditioning module to induce a partial oxidation reaction.

[0036] Furthermore, according to the second aspect, for example, the fuel can be preheated using heat recovered from engine components associated with the burner. Detailed Implementation

[0037] Figure 1 Exemplary results from simulations of the quench limit of preheated fuel in a fully stirred reactor (WSR) are shown. The results indicate that preheating the fuel (dashed line) improves the quench limit. When thermal decomposition of the fuel is taken into account, the quench limit decreases further, and thus combustion stability improves, depending on the fuel residence time at a given temperature. The fuel used in these simulations is propane, but similar results are likely for other hydrogen-containing fuels such as methane, methanol, gasoline, diesel, jet fuel, ammonia, etc. The results also show that at very high equivalence ratios (10 here), partial oxidation (POX) of the fuel can further improve the quench limit. These simulations can serve as a starting point when designing fuel conditioning modules to ensure sufficient residence time and temperature. The role of thermal decomposition is highlighted by showing the difference in quenching when thermal decomposition effects are considered (colored line) or ignored (black dashed line). The effect of thermal partial oxidation (POX) of the fuel at high equivalence ratios (10 here) is also shown.

[0038] Figure 2 A rendering of a longitudinal cross-sectional view of an apparatus according to this disclosure is shown. In one variation, the apparatus can be described as a gas turbine combustor, and thus the apparatus may be referred to herein as a gas turbine combustor, although the combustor may be used in other applications. The apparatus may also be referred to as a fuel conditioning and injection device. Furthermore, due to the different modules of the apparatus, it may be referred to as a fuel conditioning and injection device, a fuel conditioning and injection system. The expression “module” as used herein may be replaced by other expressions such as “apparatus”, “unit”, etc. The apparatus includes a fuel conditioning module 10, a micro-mixing injector module 20, and a heat source (e.g., a heat transfer module 30), which will... Figure 3Further description follows. This specific embodiment may also optionally include fins 32 that act as enhanced heat transfer surfaces to increase heat exchange from combustion products to fuel circulating in channel 31. Here, channel 31 may be part of reactor 13, where the fuel undergoes preheating and pyrolysis. Other embodiments described below may also have a specific shell that acts as a pyrolysis reactor.

[0039] Figure 3A schematic diagram of an embodiment of the apparatus according to this disclosure is shown. Fuel F is allowed to enter the conditioning module 10 of the burner via a fuel supply line 1 (e.g., pipe, conduit, etc.). Fuel F is then injected into airflow A via a micro-mixing injector module 20 to produce a non-premixed flame 100, which generates hot combustion products P in the main combustion zone 200 for use in power-generating machines (e.g., gas turbines or piston engines). The conditioning module 10 is heated by the combustion products P using a heat source (e.g., heat transfer module 30). Fuel F can be any hydrogen-containing compound, such as pure hydrogen, ammonia, ethanol, methanol, kerosene, gasoline, diesel, etc. Fuel F first enters a preheating chamber 11, where, if the fuel is liquid, it can be partially or completely evaporated, or if the fuel is already gaseous, it can be preheated. In the illustrated embodiment, the heat required for the preheating chamber 11 can be supplied by heat transfer from the combustion products P of fuel F and air A. The preheating chamber 11 is optional. In alternative embodiments, heat may be provided by hot air discharged from the compressor or regenerator, hot exhaust gas located at the outlet of the piston engine or regenerator or turbine rotor, and / or heat loss from other components of the gas turbine engine or piston engine. As an example, heat may optionally be provided by two or more of these heat sources (including product P), i.e., heat recovered from engine components. In such embodiments, at least a portion of the preheating chamber 11 may be physically located away from the remainder of the regulating module 10, but may still be considered part of the module 10. To initiate combustion in the device, an ignition injector 12 may be used, for example, with unregulated fuel. The ignition injector 12 may be defined by an orifice for gaseous fuel or a simple injector for liquid fuel and can be activated by controlling the ignition fuel supply pressure. Once the regulating module 10 is sufficiently hot, fuel F can be supplied to the regulating module 10, and the ignition injector 12 can be shut off. The resulting gaseous fuel can then flow through the heat transfer module 30. Although the term "transfer" is used, other terms can also define module 30, such as heat recovery, heat recirculation, heat regeneration, heat capture, and heat exchange. The heat transfer module 30 can consist of heat-conducting channels 31 (e.g., arranged as coils, loops, etc.) directly exposed to the combustion products P. This can be in the form of a radiator, utilizing the thermal conductivity of a material (e.g., a metal). The heat transfer module 30 can also include a heat transfer fluid circulating therein. In both cases, heat is absorbed at the combustion products P and then released to the fuel F in the fuel conditioning module 10. The inner and outer surfaces of these channels can contain heat transfer enhancements (e.g., fins 32). Figure 2However, as an example, it may also include pins, corrugated structures, and / or high-roughness surfaces, or different combinations of these features, to increase the convective heat transfer coefficient and heat transfer surface area. Channel 31 may also have a relatively high specific surface area, which can increase the heat exchange contact area between combustion products P and fuel F, and can reduce the residence time within channel 31. These effects can increase heat transfer from combustion products P to fuel F while reducing deposit formation (i.e., coking) in the small channels due to the shortened residence time. Fuel F can be heated to a temperature at which thermal decomposition begins, for example, depending on the fuel composition, this temperature can range from about 600 K to up to about 1500 K. Thermal decomposition may occur outside this range, depending on the composition. Fuel F returns to regulating module 10, where it can be allowed to undergo thermal decomposition in reactor 13, within its chamber (i.e., reactor chamber). Reactor 13 can allow sufficient residence time for fuel F to achieve a reasonably high degree of thermal decomposition completeness. This can occur continuously to produce a stream of thermally decomposed fuel, rather than a batch process. Reactor 13 can be constructed with a relatively large flow path to mitigate the negative effects of coking that may occur due to longer residence times. Because higher temperatures are required, reactor 13 can be in thermal contact only with the combustion products P and is thermally isolated from the airflow A via gap 14 to avoid unnecessary heat loss. Gap 14 can be annular. Gap 14 can be an insulated gap and can be filled with fluid, foam, etc. The regulated fuel can then be delivered to the micro-mixer injector module 20.

[0040] In embodiments used in a gas turbine combustor, the micro-mixing injector module may include an internal fuel distribution manifold 21 and an external distribution manifold 22, each having an injection orifice 23 at its downstream end. An annular passage 24 for air A may be defined between the internal fuel distribution manifold 21 and the external distribution manifold 22 of the micro-mixing injector module 20. (Illustrative) Figures 3 to 10 In the illustration, for an apparatus having an internal fuel distribution manifold 21 and an external fuel distribution manifold 22, a single fuel conditioning module 10 and a single heat transfer module 30 are shown, with conditioned fuel shared by manifolds 21 and 22, for example, via suitable piping. However, each of the internal fuel distribution manifold 21 and the external fuel distribution manifold 22 may have its own dedicated fuel conditioning module 10 and dedicated heat transfer module 30. Furthermore, although the annular passage 24 is defined by a pair of manifolds (i.e., 21 and 22), the apparatus may have a single manifold, and the annular passage 24 may be located between a manifold (e.g., 21 and 22) and a housing or similar annular wall.

[0041] The injection orifices 23 can be arranged in a single row, multiple rows, etc. In one variation, such as from... Figure 2 As observed, orifice 23 is a simple opening located in the annular walls of manifolds 21 and 22 (if both are present). Optionally, the central axis of injection orifice 23 may be oriented transversely to the central axis of the annular passage 24 (shown as a dashed line in the figure). For example, the central axis of injection orifice 23 may lie in a common plane to which the vector of the central axis of the annular air passage 24 is orthogonal. The central axis of injection orifice 23 may optionally be oriented radially. This could result in fuel F being injected transversely into airflow A, potentially forming a micro-unmixed flame 100. In an alternative embodiment, the axis of injection orifice may be tilted at an angle varying between -45° and +45° relative to the plane orthogonal to the vector of the central axis of the annular air passage 24. In other words, the central axis of injection orifice 23 may lie in a virtual cone. Different orientations may also exist for different injection orifices 23. The fuel regulation module 10, the micro-mixer injector module 20, and the heat transfer module 30 can be located radially inside the annular air passage 24 and connected to the internal fuel distribution manifold 21, such as... Figure 3 As shown, this is one possibility. The fuel regulation module 10, the micro-mixer injector module 20, and the heat transfer module 30 can alternatively be located radially outside the annular air passage 24 and connected to the external fuel distribution manifold 22, as shown. Figure 4 As shown. Alternatively, the fuel conditioning module 10, micro-mixing injector module 20, and heat transfer module 30 can be located radially inward and radially outward of the air circulation passage 24 (not shown). For simplicity, the following figures will only show the radially inward configuration, but such embodiments can also be modified to a radially outward or a dual arrangement of radially inward and outward. A swirler section 25 (e.g., in the form of a blade) can optionally be used to induce a recirculation flow 101 downstream of the micro-mixing injector module 20, which can enhance the heat transfer between the hot combustion products P and the fuel in the heat transfer module 30, and thus increase the total amount of heat transferred to the fuel in the conditioning module 10. The combustion products P can also help stabilize the unmixed flame 100. The size of the injection orifice 23 can range from 0.1 to 1.0 mm, including the endpoint values, i.e., 0.1 to 1.0 mm is the maximum cross-sectional dimension (e.g., diameter). The surface density of the injection orifice 23 can range from 5,000 to 500,000 holes per square meter of air crossflow area, including the endpoint values. The cross-flow area (i.e., the flow area) is defined here as the total area of ​​the air passage 24, measured at a plane orthogonal to a vector coinciding with the central axis, located at the orifice 23. Alternatively, this vector can be said to define the primary direction of airflow within the air passage 24. Therefore, in Figures 2 to 10In this embodiment, the air crossflow area is annular due to the annular feature of the air passage 24. However, the air crossflow area does not necessarily have to be annular, as shown below for... Figure 11 A variation of the description. Furthermore, although... Figures 2 to 10 The annular shape for air passage 24 is shown, but Figures 2 to 10 The burner or device can have a hollow cylindrical air passage 24, whereby the cross-flow area of ​​the air will be circular. Because the hot air is very close to the small injection orifice, any coking that might occur there can be burned off.

[0042] Figure 5 An alternative embodiment is shown in which, in addition to the heat transfer module 30, the fuel F can also be preheated using a resistance heater 15. Other means of heating the fuel may be infrared heating, induction heating, or any other heating source other than capturing heat from the combustion products P, and these heating sources can be used in conjunction with capturing heat from the combustion products P. This allows for a further increase in the temperature of the fuel F in the fuel conditioning module 10 and its reactor 13, thereby further increasing the thermal decomposition of the fuel F and thus further improving combustion stability. This effect can also be used... Figure 6 , Figure 7 , Figure 8 and Figure 9 The illustrated embodiment achieves this by mixing oxygen or gas with fuel to obtain a more fuel-rich fuel-air mixture, which undergoes a partial oxidation reaction, increasing the reactivity of the fuel-air mixture. Figure 6 In this process, a mixing device 40 can be used, in which pressurized fuel is mixed with a relatively small amount of air A and enters the regulating module 10 to produce a more fuel-rich mixture 41 of fuel and air (which can undergo partial thermal oxidation in reactor 13), producing a reactive gas mixture (which can then be injected using the micro-mixed fuel injector module 20). Figure 7 As shown, in lean combustion, the same effect can be achieved using combustion products P that may still contain a large amount of oxygen. Figure 7 In this context, device 40 may be referred to as an ejector, but any other device that allows a relatively small and controlled amount of airflow A or combustion products P to mix with fuel F may be used. In the case of liquid fuel, mixing device 40 may also be located after fuel preheating chamber 11 but before reactor 13 to allow mixing of now vaporized fuel F with air A (e.g., ...). Figure 8 (as shown) or a mixture with combustion product P (such as...) Figure 9(As shown) Improvement. An additional benefit of mixing air A or combustion products P with fuel F before injection in the main combustion zone 200 can be a further reduction in NOx emissions, because the time in the fuel jet is reduced and mixing is faster due to the higher velocity of the fuel jet and the lower stoichiometric air-fuel ratio under stoichiometric conditions.

[0043] Specifically, for liquid fuels, such as Figure 10 As shown, by using the pressure control orifice 50 between the fuel conditioning module 10 and the micro-mixing injector module 20, the fuel can be kept in a supercritical state (i.e., above its critical pressure and temperature). By keeping the liquid fuel in a supercritical state, the flow stability problems associated with two-phase boiling flow can be avoided, as the fuel may not boil in a supercritical state, resulting in a stable fuel flow into the combustion chamber.

[0044] exist Figures 3 to 10 In the longitudinal cross-sectional view, the modules, which may be annular, are shown in a simplified manner. Therefore, the image may have been presented as separated by the central axis of the device (represented by the dashed line). The actual position of the central axis may not be exactly as shown. Therefore, at least some portions of the fuel regulating module 10, the micro-mixing injector module 20, and the heat transfer module 30 may be annular, in a manner consistent with... Figure 2 The device is similar.

[0045] Figure 11 A rendering of a longitudinal cross-sectional view of an apparatus according to this disclosure is shown, which in one variation can be described as a piston engine combustor. Similar to... Figure 2 The device, a piston engine combustor, includes a fuel conditioning module 10, a micro-mixing injector module 20, and a heat transfer module 30. The piston engine may further include an intake valve 51, a combustion product exhaust valve 52, and a piston 53 for compressing air A and / or expanding combustion products P. The engine may have multiple... Figure 11 The piston engine combustor. Similar to the previous configuration, fuel F is allowed to enter the combustor's regulating module 10 via a fuel supply line. Fuel F is then injected through a micro-mixing injector module 20, thereby forming a non-premixed flame 100, which produces heated combustion products P in the main combustion zone 200. As shown, the micro-mixing injector module 20 may consist of an internal fuel distribution manifold 21 or an external fuel distribution manifold 22, or both. The fuel regulating module 10 is heated by exposing itself to the combustion products P through a heat transfer module 30, which may be located after the exhaust valve 52, such as... Figure 11As shown. The heat transfer module 30 can have a configuration similar to that described above, such as having a heat-conducting channel 31 in direct contact with the combustion products P. In any of the embodiments described herein, the fuel F can circulate in the heat transfer module 30, for example, in the heat-conducting channel 31 extending into the combustion chamber, or a coolant can be used to transfer heat from the combustion products P to the fuel F. Other embodiments can be configured such that the heat transfer module 30 can be located before the exhaust valve 52 and thus exposed to the combustion products P in the main combustion zone 200. The heat transfer module 30 can also use an auxiliary heating system 15 (e.g., Figure 5 (The illustrated embodiments) and / or using, for example Figures 6 to 9 The mixing device 40 shown is used to form a more fuel-rich mixture of fuel F and air A or combustion products P that still contain oxygen, the fuel-rich mixture undergoing partial oxidation. Furthermore, other possible embodiments of this disclosure include two-stroke piston engines, four-stroke piston engines, spark-ignition piston engines, compression-ignition piston engines, rotary engines, opposed piston engines, split-cycle engines, or any other internal combustion engine that generates work by expanding hot gases in a closed volume, the expanding hot gases generating forces on moving surfaces such as pistons.

[0046] Therefore, to address the problems associated with the prior art, this disclosure improves the NOx stability trade-off of micro-mixed combustion by recycling, capturing, or recovering heat from the combustion zone or any other waste heat source and transferring that heat to the fuel, while allowing the use of liquid fuels, thereby synergistically utilizing the proximity of the flame and fuel injectors in the micro-mixed combustion system. Due to their small size (high specific surface area), the various micro-mixing injector modules 20 and heat transfer modules 30 described herein can transfer a significant amount of heat back to the fuel conditioning module 10, allowing for a non-negligible degree of fuel preheating. In one embodiment, such a system can be used in gas turbine engines with high combustor inlet temperatures (e.g., high-pressure-ratio simple-cycle gas turbines, regenerative-cycle gas turbines, or reheat-cycle gas turbines), where the combustor inlet temperature is above the auto-ignition temperature of the fuel used (e.g., > 900 K), and premixed combustion cannot be reliably used to reduce NOx emissions. In another embodiment, such a system can be used in pre-combustion chamber igniters for SI piston engines that operate under very lean combustion conditions, under which misfires are typically possible. In another embodiment, such a system can be used as a primary fuel injector for CI engines, allowing for reductions in NOx and soot emissions associated with non-premixed combustion in such engines. In another embodiment, such a system can be used in regenerative split-cycle piston engines, where combustion occurs outside or inside the expanding piston, benefiting from rapid mixing due to the short time available for combustion. The device can also be used in other applications requiring hot combustion gases, low emissions, high combustion stability, and high reliability. This disclosure can also be used with hydrogen-carrying fuels, which are any fuels containing hydrogen chemical compounds, such as pure hydrogen, natural gas, propane, gasoline, diesel, kerosene, methanol, ethanol, ammonia, etc. (e.g., hydrogen-containing fuels such as NH3, CH4, C8H18, CH3OH, etc.).

[0047] The following description represents embodiments of this disclosure.

[0048] This disclosure includes a micro-mixed fuel injector module comprising a plurality of injection orifices with a maximum cross-sectional size ranging from about 0.1 mm to 1 mm (inclusive). The term “micro” is used herein to refer to these injection orifices, but in one variation, the dimensions given herein may replace the designation “micro.” The fuel injection orifices are positioned and oriented such that fuel is injected into an airflow directly adjacent to or located within the main combustion zone, where the fuel is allowed to react with air to produce hot combustion products. The location of the fuel injection orifices and their relatively small size allow for rapid mixing of fuel, air, and combustion products. Swirlers can be used to enhance the recirculation of combustion products toward the flame, thereby improving combustion stability. Because there is no premixing conduit, this approach may be inherently safer than fully premixed combustion by avoiding backfire and autoignition of the mixture, while achieving similar NOx levels due to the small-scale flame. The fuel injection module may also include internal passages and manifolds designed to distribute fuel and heat to a large number of fuel injection orifices 23, which may be referred to as micro. Multiple fuel injector modules 20 can operate independently within a single combustor, allowing for optimized fuel distribution (fuel staging) within the combustor under varying load conditions. For example, a complete combustor may include three fuel injector modules 20, with only one or two operating at partial load, while all three operate at full load. Another example is the independent operation of an internal fuel distribution manifold 21 or an external fuel distribution manifold 22, where one or both can operate under different load conditions to optimize fuel distribution within the combustor. This also mitigates coking when using carbon-based fuels by allowing air to flow within unused fuel injector modules while the engine is operating, allowing carbon deposits that can form within the injectors due to their high temperatures to be burned off.

[0049] This disclosure may include a fuel conditioning module having means for fully vaporizing and preheating liquid fuel, hereinafter referred to as a vaporizer. The vaporizer can be used to heat the liquid fuel above its boiling point to produce gaseous fuel that can be used in a micro-mixing injector module. To achieve this effect, the vaporizer can utilize waste heat from engine components such as compressors, turbines, bearings, burners, etc. The vaporizer can also extract heat from burner inlet air heated by compression in a high-pressure-ratio single-cycle gas turbine, or by a regenerator in a regenerative gas turbine cycle, or by a compression piston in a piston engine. The vaporizer can also extract heat from exhaust gas at the turbine outlet in a single-cycle engine, or from exhaust gas at the regenerator outlet in a regenerative cycle engine, or from exhaust gas at the exhaust manifold in a piston engine. The vaporizer can also be directly integrated into the fuel injector module 20 to extract heat from the main combustion zone and provide cooling to the injector module 20. The vaporizer may also include a throttling device that allows the liquid fuel to be kept at pressures and temperatures above its critical point, producing a supercritical fluid that is less susceptible to two-phase flow instabilities and is fully vaporized once throttled. Once the fuel is vaporized, or if the fuel is already a gas, the fuel conditioning module 10 may also include a continuous-flow, small-scale reactor (e.g., reactor 13), optionally referred to as a microreactor, which allows the fuel to begin thermal decomposition at high temperatures before being injected into the burner, further improving the combustion stability of the micro-mixing injector compared to simply preheating the fuel. Since the thermal decomposition of the fuel requires high temperatures, the reactor may be integrated into the fuel injector and the proximity of the fuel injector module 30 to the hot main combustion zone may be used to provide cooling for the device and to increase the fuel temperature to a level where thermal decomposition occurs, depending on the fuel composition, but typically in the range of >600 K to <1500 K. This integration of the reactor can synergistically utilize the small features required for micromixing combustion, allowing for high volumetric heat transfer rates and / or low residence times. This can be crucial for achieving high thermal decomposition rates of the fuel and / or mitigating the potential for coking of carbon-based fuels at these high temperatures by limiting contact time in narrow pathways at high temperatures. The fuel conditioning module 10 may also include a mixing device (e.g., an ejector, hereinafter referred to as a mixer) that allows the mixing of air or combustion products still containing oxygen (i.e., oxygen-containing gas) with the fuel to initiate partial oxidation, further increasing the fuel's reactivity. The mixer is designed to incorporate only a small amount of air, producing a fuel-rich mixture with a high equivalence ratio (typically >5) to avoid excessively high temperatures due to partial oxidation of the fuel. The effect of the fuel conditioning module (i.e., increasing fuel reactivity) may only be beneficial for, for example, non-premixed or partially premixed combustion systems as proposed in this disclosure.Increasing the reactivity of fuel used in a fully premixed combustion system can lead to undesirable effects, such as auto-ignition or backfire within the premixing tube.

[0050] This disclosure may include a heat transfer module that increases the heat flow returning from the main combustion zone to the fuel conditioning module to increase the rate of fuel vaporization and / or thermal decomposition. The module may include enhanced heat transfer surfaces, such as fins, pins, corrugated structures, high surface roughness, swirlers, or any features that enhance convective heat transfer. The module may also include a fluid passage from the fuel conditioning system to the main combustion zone, thereby increasing the thermal contact area between the fuel and combustion products and allowing for increased advection heat transfer from combustion products to the fuel conditioning module. This heat transfer enhancement system may be positioned to also promote the recirculation of products toward module 30 and to serve as a thermal ignition surface for the fuel jet, both of which further increase combustion stability.

[0051] The apparatus disclosed herein can be used in conjunction with a controller. The controller may have a processing unit and a non-transitory computer-readable storage device communicatively coupled to the processing unit and including computer-readable program instructions executable by the processing unit for operating the apparatus as explained above. For this purpose, the controller may be connected to valves, pumps, and electrical systems to ignite a flame and control the flow of air and fuel, thereby regulating and injecting fuel in the manner described above.

[0052] To withstand the high temperatures involved, the device of this disclosure can be made of high-temperature corrosion resistant superalloys (such as Inconel 625 or Haynes 230, etc.), refractory metals and their alloys (such as tungsten, molybdenum and / or tantalum, etc.), ceramics (such as alumina, silicon carbide or silicon nitride, etc.), or any other material capable of withstanding high temperatures and corrosive environments, or any combination thereof. Materials with high thermal conductivity can provide further benefits by increasing the possible heat flux to the fuel; significant materials for high temperature and corrosion resistance are silicon carbide or molybdenum coated with an environmental barrier coating (EBC). This disclosure can also benefit from the capabilities of additive manufacturing, where complex fluid pathways and features can be readily fabricated, particularly the very large number (1000) of small (<1 mm) pores and internal flow pathways required by this disclosure. The high surface roughness of this process can also be used to increase the heat transfer rate. In one variant, the fuel conditioning module 10, the fuel injector module 20, and / or the heat transfer module 30 each have an additively manufactured body (e.g., a single body, a recessed component of a body, etc.) that at least defines an internal cavity (in which fuel circulates). To fabricate the additively manufactured body, additive manufacturing methods (e.g., 3D printing, laminated object fabrication, etc.) can be used to efficiently manufacture the aforementioned complex internal pathways and manifolds. Therefore, additive manufacturing methods (e.g., 3D printing, laminated object fabrication, etc.) can be used to generate high surface area ratio features to increase heat transfer, thereby increasing the conversion rate from fuel to hydrogen, and thus further improving combustion stability.

[0053] The scope of this disclosure is not limited to the embodiments described above, and may cover alternative embodiments, such as: using multiple independently supplied fuel devices to optimize fuel distribution (fuel grading) according to engine load; using an electric heater instead of an ignition injector to start the burner under cold conditions; allowing air to be injected into the device for the purpose of cleaning or generating a fuel-air mixture that may undergo thermal partial oxidation in a conditioning module; or any other embodiment of the proposed arrangement of a fuel conditioning module, a micro-mixed fuel injector module, and a heat transfer module for the purpose of conditioning fuel (vaporization and / or thermal decomposition) at high temperatures, and injecting said fuel into an airflow through micro-injection orifices for the purpose of generating thermal combustion products for a power generation engine (such as a gas turbine engine or a piston engine).

Claims

1. An apparatus for injecting fuel into an air passage, wherein an airflow is directed toward a combustion chamber in the air passage, the apparatus comprising: A fuel conditioning module configured to receive fuel, the fuel conditioning module defining a reactor chamber in which the fuel is exposed to heat to at least partially decompose; A heat source configured to exchange heat with the fuel in the reactor chamber to provide the heat to the fuel; A fuel injector module, which is in fluid communication with the fuel conditioning module and is located downstream of the reactor chamber, has injection orifices leading to the air passage; As a result, the fuel injected into the air passage is at least partially decomposed.

2. The apparatus according to claim 1, wherein, The heat source is a heat transfer module, which is configured to be heated in the combustion chamber and release heat in the fuel conditioning module.

3. The apparatus according to claim 2, wherein, The heat transfer module includes a heat transfer fluid.

4. The apparatus according to any one of claims 1 to 3, wherein, The injection orifice is located on the annular surface of the fuel injector module, and the annular surface defines a portion of the air passage.

5. The apparatus according to claim 4, wherein, The central axes of the multiple injection orifices are radially oriented relative to the central axis of the annular surface.

6. The apparatus according to any one of claims 1 to 5, wherein, The air passage defines a flow area intercepted in a plane orthogonal to the vector of the direction of the airflow, and wherein the surface density of the injection orifice is 5,000 to 500,000 holes per square meter of flow area, including endpoint values.

7. The apparatus according to any one of claims 1 to 6, wherein, Multiple injection orifices have a maximum cross-sectional dimension ranging from 0.1 to 1.0 mm, including endpoint values.

8. The apparatus according to claim 7, wherein, The maximum cross-sectional dimension is the diameter.

9. The apparatus according to any one of claims 1 to 8, wherein, A thermal insulation gap is defined between the reactor chamber and the fuel injector module.

10. The apparatus according to any one of claims 1 to 9, wherein, The fuel injector module has a fuel manifold including an annular chamber, and the injection orifice is in fluid communication with the annular chamber.

11. The apparatus according to claim 1, wherein, The device includes at least two fuel injector modules, and the air passage is located between the two fuel injector modules and is ring-shaped.

12. The apparatus according to claim 11, wherein, The device includes a fuel conditioning module for each of the fuel injector modules.

13. The apparatus according to any one of claims 1 to 12, wherein, The air passage is annular, and the cyclone blades are located in the air passage.

14. The apparatus according to any one of claims 1 to 13, wherein, The air mixer is in fluid communication with the fuel conditioning module to inject air or oxygen-containing gas into the fuel conditioning module.

15. The apparatus according to claim 14, wherein, The air mixer is in fluid communication with the reactor chamber to inject air or oxygen-containing gas into the reactor chamber.

16. The apparatus according to any one of claims 1 to 15, wherein, At least one of the fuel conditioning module, the heat source, and the fuel injector module has an additively manufactured body defining an internal cavity in which the fuel is received.

17. A method for operating a burner, the method comprising: Supply fuel to the fuel regulation module; The fuel in the fuel conditioning module is exposed to heat to at least partially decompose the fuel; The fuel, which is at least partially decomposed, is injected into the air stream; as well as A mixture of air and at least partially decomposed fuel is ignited to burn in a combustion chamber.

18. The method according to claim 17, wherein, The supply of fuels includes the supply of pure hydrogen, ammonia, methanol, ethanol, kerosene, gasoline, diesel, biofuels, or any other compound that is at least partially composed of the chemical element hydrogen.

19. The method according to claim 17 or 18, wherein, Exposing the fuel in the fuel conditioning module to heat includes absorbing heat in the combustion chamber and releasing heat in the fuel conditioning module.

20. The method according to any one of claims 17 to 19, wherein, Supplying fuel includes supplying liquid fuel, and wherein exposing the fuel to heat includes vaporizing the liquid fuel.

21. The method according to any one of claims 17 to 20, wherein, Exposing the fuel to heat includes exposing the fuel to heat such that the fuel reaches a temperature of at least 600 K and up to 1500 K, including endpoint values.

22. The method according to any one of claims 17 to 21, wherein, Exposing the fuel in the fuel conditioning module to heat includes exposing the fuel to resistance heating, infrared heating, and / or induction heating.

23. The method according to any one of claims 17 to 22, further comprising injecting air or oxygen-containing gas into the fuel conditioning module to induce a partial oxidation reaction.

24. The method according to any one of claims 17 to 23, further comprising using heat recovered from engine components associated with the burner to preheat the fuel.

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