HYDROGEN CAPABLE FUEL INJECTOR

Description

FEDERALLY SPONSORED RESEARCH

This invention was made with government support under contract number DE-FE0032173 awarded by the Department of Energy. The U.S. government may have certain rights in the invention.

FIELD

The present disclosure relates generally to fuel injectors for gas turbine combustors.

BACKGROUND

Turbomachines are utilized in a variety of industries and applications for energy transfer purposes. For example, a gas turbine engine generally includes a compressor section, a combustion section, a turbine section, and an exhaust section. The compressor section progressively increases the pressure of a working fluid entering the gas turbine engine and supplies this compressed working fluid to the combustion section. The compressed working fluid and a fuel (e.g., natural gas) mix within the combustion section and burn in a combustion chamber to generate high pressure and high temperature combustion gases. The combustion gases flow from the combustion section into the turbine section where they expand to produce work. For example, expansion of the combustion gases in the turbine section may rotate a rotor shaft connected, e.g., to a generator to produce electricity. The combustion gases then exit the gas turbine engine via the exhaust section.

In some combustors, the generation of combustion gases occurs at two or more axially spaced stages. Such combustors are referred to herein as including an axial fuel staging (“AFS”) system, which delivers fuel and an oxidant to one or more fuel injectors downstream of the head end of the combustor. In a combustor with an AFS system, a primary fuel nozzle at an upstream end of the combustor injects fuel and air (or a fuel/air mixture) in an axial direction into a primary combustion zone, and an AFS fuel injector located at a position downstream of the primary fuel nozzle injects fuel and air (or a second fuel/air mixture) as a cross-flow into a secondary combustion zone downstream of the primary combustion zone. The cross-flow is generally transverse to the flow of combustion products from the primary combustion zone.

Traditional gas turbine engines include one or more combustors that burn a mixture of natural gas and air within the combustion chamber to generate the high pressure and temperature combustion gases. As a byproduct, oxides of nitrogen (NOx), carbon dioxide (CO₂), and other pollutants are created and expelled by the exhaust section. Regulatory requirements for low emissions from gas turbines are continually growing more stringent, and environmental agencies throughout the world are now requiring even lower rates of emissions of NOx and other pollutants from both new and existing gas turbines.

Burning a blend of natural gas and high amounts of hydrogen and/or burning pure hydrogen instead of natural gas within the combustor would significantly reduce or eliminate the emission of CO₂. However, because hydrogen burning characteristics are different than those of natural gas, traditional combustion systems, including traditional AFS fuel injectors, are not capable of burning high levels of hydrogen and/or pure hydrogen without issue. For example, burning high levels of hydrogen and/or pure hydrogen within a traditional combustion system could promote flashback or flame holding conditions in which the combustion flame migrates towards the fuel being supplied by the injector, possibly causing severe damage to the injector in a relatively short amount of time.

As such, a fuel injector capable of delivering alternative fuels (such as hydrogen) and air to a secondary combustion zone, without causing flame holding or flashback issues, is desired in the art.

BRIEF DESCRIPTION

Aspects and advantages of fuel injectors and combustors in accordance with the present disclosure will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the technology.

In accordance with one embodiment, a fuel injector for a combustor of a gas turbine is provided. The fuel injector includes an annular main body extending from a first end to a second end. The annular main body defines a centerline axis extending from the first end to the second end and at least a portion of a fuel circuit extends along the centerline axis. A first plurality of fluid inlets is disposed about the fuel circuit, and a second plurality of fluid inlets is disposed about the first plurality of fluid inlets. The fuel circuit includes a fuel inlet and a fuel outlet in fluid communication with the fuel inlet. An exterior surface of the fuel outlet forms a fuel outlet angle relative to the centerline axis.

In accordance with another embodiment, a combustor is provided. The combustor includes at least one fuel nozzle, a combustion liner extending downstream of the at least one fuel nozzle and defining a combustion chamber, an outer sleeve spaced apart from and surrounding the combustion liner such that an annulus is defined therebetween, and a fuel injector disposed downstream of the at least one fuel nozzle and in fluid communication with the combustion chamber. The fuel injector includes an annular main body extending from a first end to a second end. The annular main body defines a centerline axis extending from the first end to the second end and a fuel circuit extends along the centerline axis. A first plurality of fluid inlets is positioned about the fuel circuit, and a second plurality of fluid inlets is positioned about the first plurality of fluid inlets. The fuel circuit includes a fuel inlet and a fuel outlet in fluid communication with the fuel inlet. An exterior surface of the fuel outlet forms a fuel outlet angle relative to the centerline axis.

These and other features, aspects and advantages of the present fuel injectors and combustors will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the technology and, together with the description, serve to explain the principles of the technology.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present fuel injectors and combustors, including the best mode of making and using the present systems and methods, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

FIG. 1 is a schematic illustration of a turbomachine, in accordance with embodiments of the present disclosure;

FIG. 2 illustrates a schematic view of a combustor as may be employed in the turbomachine of FIG. 1, in accordance with embodiments of the present disclosure;

FIG. 3 is a transparent perspective view of a fuel injector as may be employed in the combustor of FIG. 2, in accordance with embodiments of the present disclosure;

FIG. 4 is a bottom, detailed view of a main body of the fuel injector of FIG. 3, in accordance with embodiments of the present disclosure;

FIG. 5 is a detailed, cross-sectional view of a central portion of the fuel injector of FIG. 3, in accordance with embodiments of the present disclosure;

FIG. 6 is a schematic, cross-section view of the fuel injector of FIG. 3, in accordance with embodiments of the present disclosure;

FIG. 7 is a schematic illustration of a fuel and air mixture as may be produced by the fuel injector of FIG. 3, in accordance with embodiments of the present disclosure;

FIG. 8A is a schematic illustration of a first stage of the fuel and air mixture of FIG. 7, in accordance with embodiments of the present disclosure;

FIG. 8B is a schematic illustration of a second stage of the fuel and air mixture of FIG. 7, in accordance with embodiments of the present disclosure; and

FIG. 8C is a schematic illustration of a third stage of the fuel and air mixture of FIG. 7, in accordance with embodiments of the present disclosure.

DETAILED DESCRIPTION

Reference now will be made in detail to embodiments of the present fuel injectors and combustors, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation, rather than limitation of, the technology. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present technology without departing from the scope or spirit of the claimed technology. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present disclosure covers such modifications and variations as come within the scope of the appended claims and their equivalents.

The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations. Additionally, unless specifically identified otherwise, all embodiments described herein should be considered exemplary.

The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the subject technology. As used herein, the terms “first,” “second,” and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components.

The term “fluid” may refer to a gas or a liquid. The term “fluid communication” means that a fluid is capable of flowing or being conveyed between the areas specified.

As used herein, the terms “upstream” (or “forward”) and “downstream” (or “aft”) refer to the relative direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows. The term “radially” refers to the relative direction that is substantially perpendicular to an axial centerline of a particular component; the term “axially” refers to the relative direction that is substantially parallel and/or coaxially aligned to an axial centerline of a particular component; and the term “circumferentially” refers to the relative direction that extends around the axial centerline of a particular component.

Terms of approximation, such as “about,” “approximately,” “generally,” and “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value, or the precision of the methods or machines for constructing or manufacturing the components and/or systems. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value or the precision of the methods or machines for constructing or manufacturing the components and/or systems. For example, the approximating language may refer to being within a 1, 2, 4, 5, 10, 15, or 20 percent margin in either individual values, range(s) of values, and/or endpoints defining range(s) of values. When used in the context of an angle or direction, such terms include within five degrees greater or less than the stated angle or direction. For example, “generally vertical” includes directions within ten degrees of vertical in any direction, e.g., clockwise or counter-clockwise.

The terms “coupled,” “fixed,” “attached to,” and the like refer to both direct coupling, fixing, or attaching, as well as indirect coupling, fixing, or attaching through one or more intermediate components or features, unless otherwise specified herein. The terms “directly coupled,” “directly fixed,” “directly attached to,” and the like indicate that a first component is joined to a second component with no intervening structures. As used herein, the terms “comprises,” “comprising,” “includes,” “including.” “has,” “having” or any other variations thereof, are intended to cover a non-exclusive inclusion, For example, a process, method, article, or apparatus that comprises a list of features is not necessarily limited only to those features but may include other features not expressly listed or inherent to such process, method, article, or apparatus.

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

As used herein, the term “premix” may be used to describe a component, passage, or cavity upstream of a respective combustion zone within which mixing of two (or more) fluids occurs. For example, “premix” may be used to describe a component, passage, or cavity in which two fluids (such as fuel and air) are mixed together prior to being ejected from such component, passage, or cavity (e.g., into a combustion zone).

Referring now to the drawings, FIG. 1 illustrates a schematic diagram of an exemplary embodiment of a turbomachine, which in the illustrated embodiment is a gas turbine engine 10. Although an industrial or land-based gas turbine is shown and described herein, the present disclosure is not limited to an industrial or land-based gas turbine engine unless otherwise specified in the claims. For example, the technology as described herein may be used in any type of turbomachine including but not limited to a steam turbine, an aircraft gas turbine, or a marine gas turbine.

As shown, the gas turbine engine 10 generally includes an inlet section 12, a compressor section 14 disposed downstream of the inlet section 12, a plurality of combustors 17 (shown in FIG. 2) within a combustion section 16 disposed downstream of the compressor section 14, a turbine section 18 disposed downstream of the combustion section 16, and an exhaust section 20 disposed downstream of the turbine section 18. Additionally, the gas turbine engine 10 may include one or more shafts 22 coupled between the compressor section 14 and the turbine section 18. The shaft 22 may be coupled to a generator, not shown, for producing electricity.

The compressor section 14 may generally include a plurality of rotor disks 24 (one of which is shown) and a plurality of rotor blades 26 extending radially outwardly from and connected to each rotor disk 24. Each rotor disk 24 in turn may be coupled to or form an upstream portion of the shaft 22 that extends through the compressor section 14. The compressor section 14 further includes a plurality of stationary vanes (not shown), which are arranged in stages with the rotor blades 26 and which direct the flow against the rotor blades 26.

The turbine section 18 may generally include a plurality of rotor disks 28 (one of which is shown) and a plurality of rotor blades 30 extending radially outwardly from and being interconnected to each rotor disk 28. Each rotor disk 28 in turn may be coupled to or form a downstream portion of the shaft 22 that extends through the turbine section 18. The turbine section 18 further includes an outer casing 31 that circumferentially surrounds the downstream portion of the shaft 22 and the rotor blades 30, thereby at least partially defining a hot gas path 32 through the turbine section 18. The turbine section 18 further includes a plurality of stationary vanes (not shown), which are arranged in stages with the rotor blades 30 and which direct the flow against the rotor blades 30.

During operation, a working fluid such as air flows through the inlet section 12 and into the compressor section 14 where the air is progressively compressed by multiple compressor stages of rotating blades 26 and stationary vanes, thus providing compressed air 15 to the combustors 17 of the combustion section 16. The compressed air 15 is mixed with fuel and burned within each combustor 17 to produce combustion gases 34. The combustion gases 34 flow through the hot gas path 32 from the combustion section 16 into the turbine section 18, in which energy (kinetic and/or thermal) is transferred from the combustion gases 34 to the rotor blades 30, causing the shaft 22 to rotate. The mechanical rotational energy may then be used to power the compressor section 14 and/or to generate electricity. The combustion gases 34 exiting the turbine section 18 may then be exhausted from the gas turbine engine 10 via the exhaust section 20.

FIG. 2 is a schematic representation of the combustor 17 as may be included in the combustion section 16 of the gas turbine engine 10. The combustion section 16 may be a can annular combustion system. In a can annular combustion system, a plurality of combustors 17 (e.g., 8, 10, 12, 14, 16, or more) are positioned in an annular array about the shaft 22.

As shown in FIG. 2, the combustor 17 may define a cylindrical coordinate system. The cylindrical coordinate system may define an axial direction A (e.g., a downstream direction) substantially parallel to and/or along an axial centerline 170 of the combustor 17, a radial direction R perpendicular to the axial centerline 170, and a circumferential direction C extending around the axial centerline 170.

The combustor 17 includes a combustion liner 46 that defines a combustion chamber 70 within which combustion occurs. The combustion liner 46 may be positioned within (i.e., circumferentially surrounded by) an outer sleeve 48, such that an annulus 47 is formed therebetween. The combustion liner 46 may contain and convey combustion gases to the turbine section 18. As shown in FIG. 2, the combustion liner 46 may extend between fuel nozzles 40 and an aft frame 118. The combustion liner 46 may have a generally cylindrical liner portion and a tapered transition portion that is separate from the generally cylindrical liner portion, as in many conventional combustion systems. Alternately, the combustion liner 46 may have a unified body (or “unibody”) construction, in which the generally cylindrical portion and the tapered portion are integrated with one another. Thus, any discussion of the combustion liner 46 herein is intended to encompass both conventional combustion systems having a separate liner and transition piece and those combustion systems having a unibody liner. Moreover, the present disclosure is equally applicable to those combustion systems in which the transition piece and the stage one nozzle of the turbine section 18 are integrated into a single unit (without aft frame 118), sometimes referred to as a “transition nozzle” or an “integrated exit piece.”

FIG. 2 illustrates a combustor 17 having both fuel nozzles 40 and a fuel injection assembly 80 (also referred to as an axial fuel staging (“AFS”) system), as discussed further herein. The at least one fuel nozzle 40 may be positioned at the forward end of the combustor 17. Fuel may be directed through fuel supply conduits 38, which extend through an end cover 42, and into the fuel nozzles 40. The fuel nozzles 40 convey the fuel and compressed air 15 into a primary combustion zone 72, where combustion occurs. In some embodiments, the fuel and compressed air 15 are combined as a mixture prior to reaching the primary combustion zone 72 (i.e., are “premixed”).

The combustion liner 46 may be surrounded by the outer sleeve 48, which is spaced radially outward of the combustion liner 46 to define the annulus 47 through which the compressed air 15 flows to a head end of the combustor 17. For example, compressed air 15 may enter the annulus 47 through the outer sleeve 48 (e.g., through impingement holes proximate the aft frame 118) and travel towards the end cover 42, such that the compressed air 15 within the annulus 47 flows opposite the direction of combustion gases 172 (34 in FIG. 1) within the combustion liner 46. Heat is transferred convectively from the combustion liner 46 to the compressed air 15, thus cooling the combustion liner 46 and warming the compressed air 15.

In some exemplary embodiments, the outer sleeve 48 may include a flow sleeve and an impingement sleeve coupled to one another. The flow sleeve may be disposed at the forward end, and the impingement sleeve may be disposed at the aft end. Alternately, the outer sleeve 48 may have a unified body (or “unisleeve”) construction, in which the flow sleeve and the impingement sleeve are integrated with one another in the axial direction. As before, any discussion of the outer sleeve 48 herein is intended to encompass both conventional combustion systems having a separate flow sleeve and impingement sleeve and combustion systems having a unisleeve outer sleeve.

The forward casing 50 and the end cover 42 of the combustor 17 define the head end air plenum 122, which includes the one or more fuel nozzles 40. The fuel nozzles 40 may be any type of fuel nozzle, such as bundled tube fuel nozzles or swirler nozzles (often referred to as “swozzles”). The fuel nozzles 40 may be positioned within the head end air plenum 122 defined at least partially by the forward casing 50. In many embodiments, the fuel nozzles 40 may extend from the end cover 42. For example, each fuel nozzle 40 may be coupled to an aft surface of the end cover 42 via a flange (not shown). As shown in FIG. 2, the at least one fuel nozzle 40 may be partially surrounded by the combustion liner 46. The aft, or downstream ends, of the fuel nozzles 40 extend through or collectively define a cap plate 44 that defines the upstream end of the combustion chamber 70.

The fuel nozzles 40 may be in fluid communication with a first fuel supply 150 configured to supply a first fuel 158 to the fuel nozzles 40. In many embodiments, the first fuel 158 may be a fuel mixture containing natural gas (such as one or more of methane, ethane, propane, or other suitable natural gas) and hydrogen. In some embodiments, the hydrogen may be a majority component (e.g., more than 50%) of the fuel mixture. In other embodiments, the first fuel 158 may be pure natural gas or pure hydrogen (e.g., 100% hydrogen, which may or may not contain some trace amount of contaminants), such that the first fuel is not a mixture of multiple fuels. In exemplary embodiments, the first fuel 158 and compressed air 15 may mix together within the fuel nozzles 40 to form a first mixture of compressed air 15 and the first fuel 158 before being ejected (or injected) by the fuel nozzles 40 into the primary combustion zone 72.

The forward casing 50 may be fluidly and mechanically connected to a compressor discharge casing 60, which defines a high-pressure plenum 66 around the combustion liner 46 and the outer sleeve 48. Compressed air 15 from the compressor section 14 travels through the high-pressure plenum 66 and enters the combustor 17 via apertures (not shown) in the downstream end of the outer sleeve 48 (as indicated by arrows near the aft frame 118). Compressed air travels upstream through the annulus 47 and is turned by the end cover 42 to enter the fuel nozzles 40 and to cool the head end. In particular, compressed air 15 flows from high-pressure plenum 66 into the annulus 47 at an aft end of the combustor 17, via openings defined in the outer sleeve 48. The compressed air 15 travels upstream from the aft end of the combustor 17 to the head end air plenum 122, where the compressed air 15 reverses direction and enters the fuel nozzles 40.

In the exemplary embodiment shown in FIG. 2, the fuel injection assembly 80 is provided to deliver a second fuel/air mixture to a secondary combustion zone 74 downstream from the primary combustion zone 72. For example, a second flow of fuel and air may be introduced by one or more fuel injectors 200 to the secondary combustion zone 74.

The primary combustion zone 72 and the secondary combustion zone 74 may each be portions of the combustion chamber 70 and therefore may be defined by the combustion liner 46. For example, the primary combustion zone 72 may be defined from an outlet of the fuel nozzles 40 to the fuel injector 200, and the secondary combustion zone 74 may be defined from the fuel injector 200 to the aft frame 118. In this arrangement, the forwardmost boundary of the fuel injector 200 may define the end of the primary combustion zone 72 and the beginning of the secondary combustion zone 74 (e.g., at an axial location where a second flow of fuel and air are introduced).

Such a combustion system having axially separated combustion zones is described herein as an axial fuel staging (“AFS”) system. The fuel injection assemblies 80 may be circumferentially spaced apart from one another on the outer sleeve 48 (e.g., equally spaced apart in some embodiments). In some example embodiments, the combustor 17 may include four fuel injection assemblies 80 circumferentially spaced apart from one another and configured to inject a second mixture of fuel and air into a secondary combustion zone 74 via the fuel injector 200. In other example embodiments, the combustor 17 may include any number of fuel injection assemblies 80 (e.g., 1, 2, 3, or up to 10).

As shown in FIG. 2, each fuel injection assembly 80 may include a fuel injector 200. The fuel injector 200 may be coupled to the outer sleeve 48. For example, the fuel injector 200 may couple to a radial outer surface of the outer sleeve 48 and extend radially through the annulus 47 between the outer sleeve 48 and the combustion liner 46.

A fuel supply conduit 102 may fluidly couple to each fuel injector 200. The fuel injector 200 may be in fluid communication with a second fuel supply 152 configured to supply a second fuel 160 to the fuel injector 200 via the fuel supply conduit 102. The second fuel supply 152 may be the same as or different from the first fuel supply 150, such that the fuel injector 200 may be supplied with the same fuel or a different fuel than the fuel nozzles 40. In many embodiments, the second fuel 160 may be a fuel mixture containing natural gas (such as one or more of methane, ethane, propane, or other suitable natural gas) and hydrogen. In some embodiments, the hydrogen may be a majority component (e.g., more than 50%) of the fuel mixture. In other embodiments, the second fuel 160 may be pure natural gas or pure hydrogen (e.g., 100% hydrogen, which may or may not contain some trace amount of contaminants), such that the second fuel is not a mixture of multiple fuels. In exemplary embodiments, the second fuel 160 and compressed air 15 may mix together within the fuel injector 200 to form a mixture of compressed air 15 and the second fuel 160 before being injected into the secondary combustion zone 74.

FIG. 3 is a transparent perspective view of the fuel injector 200 as may be employed in the combustor 17 of FIG. 2, in accordance with embodiments of the present disclosure.

In at least one example embodiment, the fuel injector 200 includes an annular main body 300 extending along a centerline axis 303 between a first end 301 and a second end 302. The annular main body 300 may include a first end wall 305 adjacent the first end 301, a second end wall 310 adjacent the second end 302, and an annular sidewall 315 between the first end wall 305 and the second end wall 310. The annular sidewall 315 may extend about a perimeter of the first end wall 305 and the second end wall 310.

At least a portion of a fuel circuit 320 extends along the centerline axis 303. For example, the first end wall 305 of the annular main body 300 may define an opening 325 for receiving at least a portion of the fuel circuit 320. The fuel circuit 320 may include a fuel inlet nozzle 322, a fuel inlet 324, and a fuel outlet 330. The fuel inlet nozzle 322 may be in fluid communication with the fuel supply conduit 102 and configured to receive fuel, such as the second fuel 160, from the second fuel supply 152. The fuel inlet 324 is in fluid communication with the fuel inlet nozzle 322 and the fuel outlet 330. Accordingly, the fuel inlet 324 is configured to deliver the fuel from the fuel inlet nozzle 322 to the fuel outlet 330. The fuel outlet 330 may be disposed in the second end wall 310 of the annular main body 300 and extend along the centerline axis 303. The fuel outlet 330 may be configured to receive the fuel from the fuel inlet 324 and deliver the fuel to a mixing chamber 335 downstream of the fuel outlet 330, as will be discussed in greater detail below.

In at least one exemplary embodiment, the fuel injector 200 defines a first plurality of fluid inlets 345 and a second plurality of fluid inlets 350 disposed in at least a portion of the second end wall 310. The first plurality of fluid inlets 345 and the second plurality of fluid inlets 350 may be in fluid communication with one or both of the high-pressure plenum 66 and the annulus 47. For example, the first plurality of fluid inlets 345 and the second plurality of fluid inlets 350 may be configured to receive air, such as the compressed air 15 (FIG. 2), from the high-pressure plenum 66 and/or the annulus 47. The first plurality of fluid inlets 345 and the second plurality of fluid inlets 350 may deliver the compressed air 15 to the mixing chamber 335 for mixing with the fuel 160 such that a fuel-air mixture is formed. In such example embodiments, the fuel-air mixture may be delivered from the mixing chamber 335 to the secondary combustion zone 74 (shown in FIG. 2).

With reference to FIG. 3, the second end wall 310 of the annular main body 300 may include an interior wall portion 355 adjacent the centerline axis 303 and an exterior wall portion 360 extending radially from the interior wall portion 355. For example, the exterior wall portion 360 may be between the interior wall portion 355 and the annular sidewall 315 such that the annular sidewall 315 extends about a periphery of the exterior wall portion 360. In at least one exemplary embodiment, the interior wall portion 355 extends at an angle relative to the exterior wall portion 360, as shown in FIG. 3 (the angle of the interior wall portion 355 also being shown in FIG. 5, where the exterior wall portion 360 is omitted). In other example embodiments, the interior wall portion 355 and the exterior wall portion 360 are parallel or continuous. Moreover, the interior wall portion 355 of the second end wall 310 may define the fuel outlet 330, the first plurality of fluid inlets 345, and the second plurality of fluid inlets 350, as shown in FIG. 3.

In at least one example embodiment, components of the fuel injector 200 described herein may be integrally formed as a single component. That is, each of the subcomponents, such as the annular main body 300, the fuel inlet nozzle 322, the fuel inlet 324, the fuel outlet 330, the mixing chamber 335, the first plurality of fluid inlets 345, and the second plurality of fluid inlets 350, may be manufactured together as a single body (e.g., by additive manufacturing). In other exemplary embodiments, one or more of the annular main body 300, the fuel inlet nozzle 322, the fuel inlet 324, the fuel outlet 330, the mixing chamber 335, the first plurality of fluid inlets 345, and the second plurality of fluid inlets 350 may be separate components.

FIG. 4 is a bottom, detailed view of the main body 300 of the fuel injector 200 of FIG. 3, in accordance with embodiments of the present disclosure.

In at least one exemplary embodiment, the first plurality of fluid inlets 345 are positioned about the fuel circuit 320. More specifically, the first plurality of fluid inlets 345 are positioned about the fuel outlet 330. The second plurality of fluid inlets 350 are positioned about and spaced radially outward from the first plurality of fluid inlets 345. For example, as shown in FIG. 4, the first plurality of fluid inlets 345 define a first ring 400 surrounding the fuel outlet 330, and the second plurality of fluid inlets 350 define a second ring 405 surrounding the first ring 400 of the first plurality of fluid inlets 345. Accordingly, the first ring 400 of the first plurality of fluid inlets 345 is between the fuel outlet 330 and the second ring 405 of the second plurality of fluid inlets 350.

In at least one exemplary embodiment, the first ring 400 of the first plurality of fluid inlets 345 and the second ring 405 of the second plurality of fluid inlets 350 are coaxial with the centerline axis 303 (that is, the centerline axis 303 defines a center of a first imaginary circle extending through the first ring 400 and of a second imaginary circle extending through the second ring 405). The first plurality of fluid inlets 345 may be equally spaced about the centerline axis 303, and the second plurality of fluid inlets 350 may be equally spaced about the centerline axis 303. Additionally, the second plurality of fluid inlets 350 may be offset circumferentially from the first plurality of fluid inlets 345. For example, each of the second plurality of fluid inlets 350 may be positioned between adjacent ones of the first plurality of fluid inlets 345, as shown in FIG. 4. In other example embodiments, the first plurality of fluid inlets 345 and/or the second plurality of fluid inlets 350 may be unequally spaced about the centerline axis 303.

In at least one exemplary embodiment, a number of the first plurality of fluid inlets 345 may be the same as a number of the second plurality of fluid inlets 350. For example, as shown in FIG. 4, there may be four of the first plurality of fluid inlets 345 and four of the second plurality of fluid inlets 350. It should be understood, however, that there may be any number of the first plurality of fluid inlets 345 and the second plurality of fluid inlets 350. For example, there may be two or more of the first plurality of fluid inlets 345 and two or more of the second plurality of fluid inlets 350. Moreover, the number of the first plurality of fluid inlets 345 may be different from the number of the second plurality of fluid inlets 350 in other example embodiments.

FIG. 5 is a detailed, cross-sectional view of a central portion of the fuel injector 200 of FIG. 3, in accordance with embodiments of the present disclosure. More particularly, FIG. 5 illustrates a cross-sectional view of the fuel outlet 330.

In at least one example embodiment, the fuel outlet 330 extends along the centerline axis 303 from the fuel inlet 324 towards the second end 302 of the fuel injector 200. Moreover, the fuel outlet 330 extends from the second end wall 310 and into the mixing chamber 335. The fuel outlet 330 may have a conical shape in some example embodiments. For example, as shown in FIG. 5, an exterior surface of the fuel outlet 330 tapers from the first end 301 towards the second end 302. Additionally, the exterior surface of the fuel outlet 330 may define a fuel outlet angle 500 relative to the centerline axis 303. In at least one example embodiment, the fuel outlet angle 500 may be greater than or equal to 5° and less than or equal to 30°. For example, the fuel outlet angle 500 may be about 10°.

In other example embodiments, the fuel outlet 330 may have a cylindrical shape.

In at least one exemplary embodiment, a mixing structure, such as a delta wing 505, may be disposed in one or more of the first plurality of fluid inlets 345. The delta wing 505 may accelerate mixing of the fuel and air in the mixing chamber 335.

FIG. 6 is a schematic, cross-sectional view of the fuel injector 200 of FIG. 3, in accordance with embodiments of the present disclosure.

With reference to FIG. 6, each of the first plurality of fluid inlets 345 and the second plurality of fluid inlets 350 may have a cylindrical shape (also shown in FIGS. 3-4). For example, the first plurality of fluid inlets 345 and the second plurality of fluid inlets 350 may be defined by a plurality of tubes and/or conduits. In at least one example embodiment, the first plurality of fluid inlets 345 and the second plurality of fluid inlets may have a diameter greater than or equal to 0.05 inches and less than or equal to 0.50 inches. In other example embodiments, each of the first plurality of fluid inlets 345 and the second plurality of fluid inlets 350 includes a conical shape.

Each of the first plurality of fluid inlets 345 extends along an axis, indicated by first inlet arrow 600. Each of the first plurality of fluid inlets 345 defines a first fluid inlet angle 610 relative to the centerline axis 303 and the first inlet arrow 600. The first fluid inlet angle 610 may be the same as the fuel outlet angle 500. For example, the first plurality of fluid inlets 345 may extend parallel to the exterior surface of the fuel outlet 330. In at least one example embodiments, the first fluid inlet angle 610 may be greater than or equal to 5°and less than or equal to 30°. For example, the first fluid inlet angle 610 may be about 10°.

Each of the second plurality of fluid inlets 350 also extends along an axis, indicated by second inlet arrow 605. Each of the second plurality of fluid inlets 350 defines a second fluid inlet angle 615 relative to the centerline axis 303 and the second inlet arrow 605. The second fluid inlet angle 615 may be greater than one or both of the first fluid inlet angle 610 and the fuel outlet angle 500. In at least one example embodiment, the second fluid inlet angle 615 may be greater than or equal to 10° and less than or equal to 60°. For example, the second fluid inlet angle 615 may be about 20°.

In at least one exemplary embodiment, introducing air, such as the compressed air 15, into the mixing chamber 335 via the first plurality of fluid inlets 345 at the first fluid inlet angle 610 and the second plurality of fluid inlets 350 at the second fluid inlet angle 615 creates a vortex structure that enhances mixing of the fuel and the air. For example, the fuel flows from the fuel inlet 324, through the fuel outlet 330, and into the mixing chamber 335 along a fuel flow line 620. As shown in FIG. 6, the fuel flow line 620 extends along the centerline axis 303. A first portion of air, such as a first portion of the compressed air 15, flows through the first plurality of fluid inlets 345 at the first fluid inlet angle 610 and is discharged into the mixing chamber 335, as indicated by the first inlet arrow 600. A second portion of the air, such as a second portion of the compressed air 15, flows through the second plurality of fluid inlets 350 at the second fluid inlet angle 615 and is also discharged into the mixing chamber 335, as indicated by second inlet arrow 605. Because the second fluid inlet angle 615 is greater than the first fluid inlet angle 610, the second portion of the air (indicated by second inlet arrow 605) intersects the first portion of the air and the fuel (indicated by first inlet arrow 600 and the fuel flow line 620, respectively). The second portion of the air moves inward towards the centerline axis 303, as indicated by arrows 625, and the first portion of the air and the fuel is pushed outward away from the centerline axis 303, as indicated by arrows 630. Accordingly, a double vortex is formed (shown in FIGS. 8B-8C) that promotes mixing of the air and the fuel to form the air-fuel mixture within the mixing chamber 335.

In at least one example embodiment, one or more mixing structures may be disposed in the first plurality of fluid inlets 345 to promote mixing of the air with the fuel. For example, the one or more mixing structures may be coupled to and extend from an interior surface of the first plurality of fluid inlets 345. The one or more mixing structures may introduce turbulence into the air flowing through the first plurality of fluid inlets 345 to promote mixing prior to introducing the fuel into the air, which prevents flame holding conditions. In at least one example embodiment, the one or more mixing structures may include a delta wing (such as the delta wing 505 shown in FIG. 5) or a chevron.

FIG. 7 is a schematic illustration of a fuel and air mixture as may be produced by the fuel injector 200 of FIG. 3, in accordance with embodiments of the present disclosure. FIG. 8A is a schematic illustration of a first stage 710 of the fuel and air mixture of FIG. 7, in accordance with embodiments of the present disclosure. FIG. 8B is a schematic illustration of a second stage 715 of the fuel and air mixture of FIG. 7, in accordance with embodiments of the present disclosure. FIG. 8C is a schematic illustration of a third stage 720 of the fuel and air mixture of FIG. 7, in accordance with embodiments of the present disclosure.

As discussed above with respect to FIG. 6, the fuel injector 200 promotes mixing of air and fuel prior to injecting the fuel-air mixture into the secondary combustion zone 74 of the combustor 17 (FIG. 2). The fuel enters the mixing chamber 335 via the fuel outlet 330 and the air enters the mixing chamber 335 via the first plurality of fluid inlets 345 and the second plurality of fluid inlets 350. For example, the fuel and air enters the mixing chamber 335 at a first stage 710. Referring to FIG. 8A, the fuel flows along the fuel flow line 620 (shown in FIG. 6) and enters the mixing chamber 335, defining a fuel zone 700 coaxial with the centerline axis 303. Additionally, the first portion of the air enters the mixing chamber 335 from the first plurality of fluid inlets 345, indicated by the first inlet arrow 600 in FIG. 6, and defines a plurality of first fluid inlet zones 800. A number of the first fluid inlet zones 800 may correspond with the number of the first plurality of fluid inlets 345. For example, there may be four of the plurality of first fluid inlet zones 800 and four of the first plurality of fluid inlets 345. Moreover, the second portion of the air enters the mixing chamber 335 from the second plurality of fluid inlets 350, indicated by the second inlet arrow 605 in FIG. 6, and defines a plurality of second fluid inlet zones 805 at the first stage 710. A number of the second fluid inlet zones 805 may also correspond with the number of the second plurality of fluid inlets 350. For example, there may be four of the plurality of second fluid inlet zones 805 and four of the second plurality of fluid inlets 350.

Referring now to FIGS. 7 and 8B, the mixing chamber 335 defines a second stage 715 downstream from the first stage 710. For example, the vortex structure discussed above with respect to FIG. 6 is shown. More specifically, a plurality of double vortexes 810 is shown. The plurality of double vortexes 810 may be formed when the second portion of the air moves inward toward the centerline axis 303, as indicated by arrows 625 in FIG. 6, and the first portion of the air and the fuel is pushed outward away from the centerline axis 303, as indicated by arrows 630 in FIG. 6. A number of the plurality of double vortexes 810 may correspond with the number of the first plurality of fluid inlets 345 and the number of the second plurality of fluid inlets 350. For example, each of the plurality of double vortexes 810 may be formed by a pair of one of the first plurality of fluid inlets 345 and one of the second plurality of fluid inlets 350. In at least one example embodiment, the fuel injector 200 includes four of the first plurality of fluid inlets 345 and four of the second plurality of fluid inlets 350, thereby forming four of the plurality of double vortexes 810, as shown in FIG. 8B.

The plurality of double vortexes 810 create a flow that promotes mixing of the air with the fuel within the mixing chamber 335. With reference to FIGS. 7 and 8C, a third stage 720 downstream of the second stage 715 includes the plurality of double vortexes 810. As the fuel and air travels from the first end 301 towards the second end 302, the fuel within the fuel zone 700 is further mixed with the air within a perimeter region 705 of the mixing chamber 335. Accordingly, the fuel injector 200 may create a more uniform mixture of the air and the fuel prior to injecting the fuel-air mixture into the secondary combustion zone 74 while also preventing flame holding within the fuel injector 200. When operating on fuels including natural gas, such mixing within the mixing chamber 335 promotes complete combustion and reduces the formation of emissions within the secondary combustion zone 74.

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

Further aspects of the invention are provided by the subject matter of the following clauses:

• • A fuel injector for a combustor of a gas turbine, the fuel injector comprising: an annular main body extending from a first end to a second end, the annular main body defining a centerline axis extending from the first end to the second end, at least a portion of a fuel circuit extending along the centerline axis, a first plurality of fluid inlets disposed about the fuel circuit, and a second plurality of fluid inlets disposed about the first plurality of fluid inlets; and wherein the fuel circuit comprises a fuel inlet and a fuel outlet in fluid communication with the fuel inlet, an exterior surface of the fuel outlet forming a fuel outlet angle relative to the centerline axis.

The fuel injector of one or more of these clauses, wherein the fuel outlet angle is about 10°.

The fuel injector of one or more of these clauses, wherein: the second plurality of fluid inlets is radially spaced from the first plurality of fluid inlets, relative to the centerline axis; and the first plurality of fluid inlets is disposed between the fuel outlet and the plurality of second fluid inlets.

The fuel injector of one or more of these clauses, wherein: the first plurality of fluid inlets is equally spaced about the centerline axis; and the second plurality of fluid inlets is equally spaced about the centerline axis.

The fuel injector of one or more of these clauses, wherein the second plurality of fluid inlets is circumferentially offset from the first plurality of fluid inlets.

The fuel injector of one or more of these clauses, wherein: each of the first plurality of fluid inlets forms a first fluid inlet angle relative to the centerline axis, the first fluid inlet angle equal to the fuel outlet angle; and each of the second plurality of fluid inlets forms a second fluid inlet angle relative to the centerline axis, the second fluid inlet angle being greater than the first fluid inlet angle.

The fuel injector of one or more of these clauses, wherein: the first fluid inlet angle is about 10°; and the second fluid inlet angle is about 20°.

The fuel injector of one or more of these clauses, wherein: the first plurality of fluid inlets comprises four fluid inlets; and the second plurality of fluid inlets comprises four fluid inlets.

The fuel injector of one or more of these clauses, further comprising a mixing chamber downstream of and in fluid communication with the fuel outlet, the first plurality of fluid inlets, and the second plurality of fluid inlets.

The fuel injector of one or more of these clauses, wherein the exterior surface of the fuel outlet tapers from the first end to the second end.

The fuel injector of one or more of these clauses, wherein the first plurality of fluid inlets and the second plurality of fluid inlets are cylindrical.

The fuel injector of one or more of these clauses, further comprising one or more mixing structures disposed in the first plurality of fluid inlets, wherein the one or more mixing structures includes a delta wing.

A combustor comprising: at least one fuel nozzle; a combustion liner extending downstream of the at least one fuel nozzle and defining a combustion chamber; an outer sleeve spaced apart from and surrounding the combustion liner such that an annulus is defined therebetween; and a fuel injector disposed downstream of the at least one fuel nozzle and in fluid communication with the combustion chamber, the fuel injector comprising: an annular main body extending from a first end to a second end, the annular main body defining a centerline axis extending from the first end to the second end, a fuel circuit extending along the centerline axis, a first plurality of fluid inlets positioned about the fuel circuit, and a second plurality of fluid inlets positioned about the first plurality of fluid inlets, wherein the fuel circuit comprises a fuel inlet and a fuel outlet in fluid communication with the fuel inlet, an exterior surface of the fuel outlet forming a fuel outlet angle relative to the centerline axis.

The combustor of one or more of these clauses, wherein the fuel inlet of the fuel circuit is in fluid communication with a fuel supply conduit and is configured to receive fuel from a fuel supply.

The combustor of one or more of these clauses, wherein the fuel supply supplies a fuel containing pure hydrogen or a fuel mixture of hydrogen and natural gas, where hydrogen is a majority component of the fuel mixture.

The combustor of one or more of these clauses, wherein the first plurality of fluid inlets and the second plurality of fluid inlets are in fluid communication with the annulus.

The combustor of one or more of these clauses, wherein: each of the first plurality of fluid inlets forms a first fluid inlet angle relative to the centerline axis, the first fluid inlet angle equal to the fuel outlet angle; and each of the second plurality of fluid inlets forms a second fluid inlet angle relative to the centerline axis, the second fluid inlet angle being greater than the first fluid inlet angle.

The combustor of one or more of these clauses, wherein: the fuel outlet angle is about 10°; the first fluid inlet angle is about 10°; and the second fluid inlet angle is about 20°.

The combustor of one or more of these clauses, wherein: the second plurality of fluid inlets is radially spaced from the first plurality of fluid inlets, relative to the centerline axis; and the first plurality of fluid inlets is disposed between the fuel outlet and the plurality of second fluid inlets.

The combustor of one or more of these clauses, wherein: the first plurality of fluid inlets is equally spaced about the centerline axis; the second plurality of fluid inlets is equally spaced about the centerline axis; and the second plurality of fluid inlets is circumferentially offset from the first plurality of fluid inlets.