Patent Description:
Gas turbine systems are used in a wide variety of applications to generate power. In operation of a gas turbine system ("GT system"), air flows through a compressor, and the compressed air is supplied to a combustion section. Specifically, the compressed air is supplied to one or more combustors each having a number of fuel nozzles, i.e., burners, which use the air in a combustion process with a fuel. The compressor includes an array of inlet guide vanes (IGVs), the angle of which can be controlled to control an air flow to the combustion section, and thus a combustion temperature. The combustion section is in flow communication with a turbine section in which the combustion gas stream's kinetic and thermal energy is converted to mechanical rotational energy. The turbine section includes a turbine that rotatably couples to and drives a rotor. The compressor may also rotatably couple to the rotor. The rotor may drive a load, like an electric generator.

In some embodiments, the combustion section includes a number of combustors that can be used to control the load of the GT system, e.g., a plurality of circumferentially spaced combustor 'cans. ' A header (or end cover) combustion stage may be positioned at an upstream end of the combustion region of each combustor. The header combustion stage includes a number of fuel nozzles or burners that act to introduce fuel for combustion in a combustion chamber defined by a respective liner.

In an annular combustion system, a plurality of burners is circumferentially arranged along a combustor dome upstream of a shared combustion chamber. Each burner includes a premix burner and a pilot burner. The premix burner includes a swirler that premixes fuel and air. The swirler includes a plurality of swirl vanes that impart rotation to the entering air and a plurality of fuel spokes that distribute fuel in the rotating air stream. The fuel and air then mix in an annular passage, referred to as a mixing tube, within the burner before reacting within a combustion zone in the combustion chamber.

A combustor must be able to address a range of operating conditions, such as applied load, combustion stability, combustion quality, firing temperature requirements, etc. Pilot burners are used to provide better control of the combustion process, for example, to provide improved combustion stability. For example, at low operating loads, the pilot burner may be operated to create fuel-rich zones ensuring the combustion flame does not extinguish. At higher operating loads, the pilot burner's fuel-air injection may be lowered to reduce pollutants. Pilot burners may be used in a variety of alternative settings to control the combustion process, also. In some instances, a pilot burner includes a lance extending longitudinally upstream of the mixing tube to inject a mixture including two fuels and air into the mixing tube. The structure to provide two fuels and air in a lance is complicated by the need to cool the pilot burner to address thermal expansion and contraction. In other instances, the pilot burner may introduce fuel and air radially near an end of the mixing tube, but this arrangement is not ideal for operational control of the combustion process.

<CIT> describes a pilot burner for a combustor of a gas turbine engine.

All aspects, examples, and features mentioned below can be combined in any technically possible way.

An aspect of the disclosure provides a burner for a combustion chamber of a combustor, the burner comprising: a swirl generator defining a first portion of a burner interior; a mixing tube downstream of the swirl generator and defining a second portion of the burner interior, the mixing tube having an outlet opening in fluid communication with the combustion chamber; and a pilot lance extending along a longitudinal axis and extending into the burner interior, the pilot lance including a pilot burner having a single fuel conduit for supplying a fuel, and an air conduit for supplying air.

Another aspect of the disclosure includes any of the preceding aspects, and a longitudinal position of the pilot lance and the pilot burner downstream of a combustor end of the swirl generator is adjustable.

Another aspect of the disclosure includes any of the preceding aspects, and the single fuel conduit includes an inner conduit for supplying the fuel, and the air conduit as an outer conduit concentric with the inner conduit for supplying air, and wherein the pilot burner further includes: an inner wall defining an inner plenum; a partition wall radially outward of the inner wall and defining an intermediate plenum with at least a portion of the inner wall, the inner wall including a plurality of exit passages for fluidly coupling the inner plenum to the intermediate plenum; an outer wall defining an outer plenum with at least a portion of the partition wall; a crossover section including a first plurality of passages fluidly coupling the inner conduit to the outer plenum and a second plurality of passages fluidly coupling the outer conduit to the inner plenum; and an end plate including a plurality of openings in fluid communication with the burner interior, the plurality of openings including a set of fuel exit openings in fluid communication with the outer plenum, a set of air exit openings adjacent the set of fuel exit openings and in fluid communication with the intermediate plenum, and a set of cooling openings in fluid communication with the inner plenum.

Another aspect of the disclosure includes any of the preceding aspects, and further comprising a throat section in the outer plenum, the throat section constricting flow of fuel through the outer plenum.

Another aspect of the disclosure includes any of the preceding aspects, and the throat section includes a radially outward protrusion on the partition wall and an opposing, radially inward protrusion on the outer wall, the radially outward protrusion and the radially inward protrusion defining a throat passage having a first cross-sectional area, and wherein the partition wall and the outer wall define a plenum passage upstream and downstream of the protrusions having a second cross-sectional area that is greater than the first cross-sectional area.

Another aspect of the disclosure includes any of the preceding aspects, and the outer wall is radially flexible, and the crossover section and the end plate are less flexible than the outer wall.

The herein claimed invention as set out in the appended claims provides a pilot burner for a combustor, the pilot burner comprising: an inner conduit configured to deliver a fuel; an outer conduit concentric with the inner conduit and configured to deliver air; an inner wall defining an inner plenum; a partition wall radially outward of the inner wall and defining an intermediate plenum with at least a portion of the inner wall, the inner wall including a plurality of exit passages for fluidly coupling the inner plenum to the intermedia plenum; an outer wall defining an outer plenum with at least a portion of the partition wall; a crossover section in fluid communication with the inner and outer conduit, the crossover section including a first plurality of passages fluidly coupling the inner conduit to the outer plenum and a second plurality of passages fluidly coupling the outer conduit to the inner plenum; and an end plate including a plurality of openings in fluid communication with a burner interior, the plurality of openings including a set of fuel exit openings in fluid communication with the outer plenum, a set of air exit openings adjacent the set of fuel exit openings and in fluid communication with the intermediate plenum, and a set of cooling openings in fluid communication with the inner plenum.

Another aspect of the disclosure includes any of the preceding aspects, and the inner conduit is coupled to an elongated fuel conduit of a pilot lance, and the outer conduit is coupled to elongated air conduit of the pilot lance.

An aspect of the disclosure provides a gas turbine (GT) system, comprising: a compressor; a combustion section operatively coupled to the compressor and including an annular combustor, the annular combustor including a burner for a combustion chamber of the annular combustor, the burner including: a hood; a swirl generator operatively coupled to the hood and defining a first portion of a burner interior; a mixing tube downstream of the swirl generator and defining a second portion of the burner interior, the mixing tube having an outlet opening in fluid communication with the combustion chamber; and a pilot lance extending along a longitudinal axis and extending from the hood into the burner interior, the pilot lance including a pilot burner having a single fuel conduit for supplying a fuel, and an air conduit for supplying air; and a turbine operatively coupled to the combustion section.

Two or more aspects described in this disclosure, including those described in this summary section, may be combined to form implementations not specifically described herein.

Other features, objects, and advantages will be apparent from the description and drawings and from the claims.

The drawings are intended to depict only typical aspects of the disclosure and therefore should not be considered as limiting the scope of the disclosure.

As an initial matter, in order to clearly describe the subject matter of the current disclosure, it will become necessary to select certain terminology when referring to and describing relevant machine components within a gas turbine system or a combustor thereof. To the extent possible, common industry terminology will be used and employed in a manner consistent with its accepted meaning. Unless otherwise stated, such terminology should be given a broad interpretation consistent with the context of the present application and the scope of the appended claims. Those of ordinary skill in the art will appreciate that often a particular component may be referred to using several different or overlapping terms. What may be described herein as being a single part may include and be referenced in another context as consisting of multiple components. Alternatively, what may be described herein as including multiple components may be referred to elsewhere as a single part.

In addition, several descriptive terms may be used regularly herein, and it should prove helpful to define these terms at the onset of this section. These terms and their definitions, unless stated otherwise, are as follows. As used herein, "downstream" and "upstream" are terms that indicate a direction relative to the flow of a fluid, such as the combustion gases in a combustor, the flow of air through the combustor, or coolant through one of the turbine's component systems. The term "downstream" corresponds to the direction of flow of the fluid, and the term "upstream" refers to the direction opposite to the flow (i.e., the direction from which the flow originates). The terms "forward" and "aft," without any further specificity, refer to directions, with "forward" referring to the front or compressor end of the engine, and "aft" referring to the rearward section of the turbomachine.

It is often required to describe parts that are disposed at different radial positions with regard to a center axis. The term "radial" refers to movement or position perpendicular to an axis. For example, if a first component resides closer to the axis than a second component, it will be stated herein that the first component is "radially inward" or "inboard" of the second component. If, on the other hand, the first component resides further from the axis than the second component, it may be stated herein that the first component is "radially outward" or "outboard" of the second component. The term "axial" refers to movement or position parallel to an axis. Finally, the term "circumferential" refers to movement or position around an axis. It will be appreciated that such terms may be applied in relation to the center axis of the turbine.

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 terminology used herein is for describing particular embodiments only and is not intended to be limiting of the disclosure. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. "Optional" or "optionally" means that the subsequently described event or circumstance may or may not occur or that the subsequently described component or element may or may not be present, and that the description includes instances where the event occurs or the component is present and instances where it does not or is not present.

Where an element or layer is referred to as being "on," "engaged to," "connected to," or "coupled to" another element or layer, it may be directly on, engaged to, connected to, or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly engaged to," "directly connected to," or "directly coupled to" another element or layer, there are no intervening elements or layers present.

As indicated above, the disclosure provides a burner and, in particular, a pilot burner for a combustor. The pilot burner includes an inner conduit for delivering a fuel, and an outer conduit concentric with the inner conduit for delivering air. An inner wall defines an inner plenum, and a partition wall radially outward of the inner wall defines an intermediate plenum with at least a portion of the inner wall. The inner wall includes a plurality of exit passages for fluidly coupling the inner plenum to the intermediate plenum. An outer wall defines an outer plenum with at least a portion of the partition wall. A crossover section is in fluid communication with the inner and outer conduit. The crossover section includes a first plurality of passages fluidly coupling the inner conduit to the outer plenum and a second plurality of passages fluidly coupling the outer conduit to the inner plenum. An end plate includes a plurality of openings in fluid communication with a burner interior. The plurality of openings includes a set of fuel exit openings in fluid communication with the outer plenum, a set of air exit openings adjacent the set of fuel exit openings and in fluid communication with the intermediate plenum, and a set of cooling openings for the end plate in fluid communication with the inner plenum. The pilot burner can be used with a single fuel and air and can be selectively positioned within a burner interior to provide, inter alia, improved combustion stability, quality and firing temperature control.

<FIG> shows a cross-sectional view of an illustrative gas turbine system application for a burner according to embodiments of the description. As will be recognized, a burner as described herein has a number of alternative applications, such as but not limited to: jet engines, blast furnaces, etc. In <FIG>, gas turbine (GT) system <NUM> includes an intake section <NUM> and a compressor <NUM> downstream from intake section <NUM>. Compressor <NUM> feeds air to a combustion section <NUM> that is coupled to a turbine section <NUM>. Compressor <NUM> may include one or more stages of inlet guide vanes (IGVs) <NUM>. As understood in the art, the angle of stages of IGVs <NUM> can be adjusted dynamically to control an air flow volume to combustion section <NUM> and thus parameters such as the combustion temperature of section <NUM>. Combustion section <NUM> includes an annular combustor <NUM>. Exhaust from turbine section <NUM> exits via an exhaust section <NUM>. Turbine section <NUM> drives compressor <NUM> and a load <NUM> through a common shaft or rotor connection. Load <NUM> may be any one of an electrical generator and a mechanical drive application and may be located forward of intake section <NUM> (as shown) or aft of exhaust section <NUM>. Examples of such mechanical drive applications include an electric generator, a compressor for use in oil fields, and/or a compressor for use in refrigeration. When used in oil fields, the application may be a gas reinjection service. When used in refrigeration, the application may be in liquid natural gas (LNG) plants. Yet another load <NUM> may be a propeller as may be found in turbojet engines, turbofan engines and turboprop engines.

Referring to <FIG> and <FIG>, combustion section <NUM> may include annular combustor <NUM>, or a circular array of a plurality of circumferentially spaced combustors. <FIG> shows a partial cross-sectional side view of an illustrative annular combustor <NUM>. A fuel/air mixture is burned in combustor <NUM> to produce the hot energetic combustion gas flow, which flows through the downstream end of combustor <NUM> to turbine nozzles <NUM> of turbine section <NUM> (<FIG>). For purposes of the present description, only a portion of combustor <NUM> is illustrated, it being appreciated that the annular combustor <NUM> is symmetrical about the longitudinal axis of GT system <NUM>. It is contemplated that the present disclosure may be used in conjunction with other combustor systems, including and not limited to can annular combustor systems.

Referring now to <FIG>, there is shown generally a portion of combustor <NUM> for GT system <NUM> (<FIG>) including a combustion or reaction zone <NUM>. An inner liner <NUM> and an outer liner <NUM> collectively define a combustion plenum <NUM> through which hot combustion gas flows to turbine nozzles <NUM> and the turbine blades (not shown). Combustor <NUM> may include a casing <NUM> (mounting cone), a hood <NUM> (or end cover) to which burners <NUM> are mounted, a plurality of burners <NUM>, a front panel <NUM> (or cap assembly), and an outer sleeve <NUM> surrounding one or both of inner liner <NUM> and outer liner <NUM> of combustion plenum <NUM>. An ignition device(s) (not shown) is/are provided and may include an electrically energized spark plug.

Combustion in combustion zone <NUM> occurs between inner liner <NUM> and outer liner <NUM>. Combustion air is directed within combustion plenum <NUM> defined by combustion liners <NUM>, <NUM> via sleeve <NUM> and may enter combustion liner <NUM>, <NUM> through burners <NUM> and, optionally, through a plurality of openings formed in front panel <NUM>. The air enters combustion liner <NUM>, <NUM> under a pressure differential and mixes with fuel from start-up burners (not shown) and/or plurality of burners <NUM> disposed circumferentially around front panel <NUM>. Consequently, a combustion reaction occurs within combustion zone <NUM> releasing heat for the purpose of driving turbine section <NUM> (<FIG>). High-pressure air for combustion zone <NUM> may enter outer sleeve <NUM> from an annular plenum <NUM> defined by casing <NUM>. Compressor <NUM> (<FIG>) supplies high-pressure air for this purpose and other applications relative to burners <NUM>.

<FIG> shows a cross-sectional view of a burner <NUM> for combustion chamber <NUM> of combustor <NUM>, in accordance with embodiments of the disclosure. Burner <NUM> may be coupled to hood <NUM>, e.g., using a mounting flange <NUM>. Hood <NUM> and mounting flange <NUM> may include any structural element for mounting and/or positioning one or more burners <NUM>. Mounting flange <NUM> may position each burner <NUM> for fuel and/or air supply conduit coupling, electrical connections and any other operability features, any of which may occur outside hood <NUM>.

Burner <NUM> also includes a swirl generator <NUM> axially spaced from and operatively coupled to hood <NUM>. Swirl generator <NUM> defines a first portion <NUM> of a burner interior <NUM>. Swirl generator <NUM> may include any now known or later developed structure for mixing an oxidizer (e.g., air) and a fuel (e.g., liquid or gaseous fuel) into a swirling gaseous flow in burner interior <NUM>. For example, swirl generator <NUM> may include a plurality of swirl vanes <NUM> that impart rotation to the entering air and a plurality of fuel spokes <NUM> that distribute fuel in the rotating air stream. The fuel and air then mix in an annular passage, referred to as a mixing tube <NUM>, within burner <NUM> before reacting within combustion zone <NUM> of combustion chamber <NUM>. An inlet flow conditioner (IFC) sleeve <NUM> may surround swirl generator <NUM>. In many cases, swirl generator has a frusto-conical shape that enlarges as it progresses towards combustion chamber <NUM>.

Burner <NUM> also includes mixing tube <NUM> downstream of swirl generator <NUM>, such that mixing tube <NUM> defines a second portion <NUM> of burner interior <NUM>. Mixing tube <NUM> has an outlet opening <NUM> in fluid communication with combustion zone <NUM> of combustion chamber <NUM>. Outlet opening <NUM> may be in, or part of, front panel <NUM>, which may position a number of burners <NUM> relative to a common combustion chamber <NUM>.

As shown in <FIG> and in the cross-sectional view of <FIG>, burner <NUM> also includes a pilot lance <NUM> extending along a longitudinal axis LA of burner <NUM> and extending from hood <NUM> into burner interior <NUM>. Pilot lance <NUM> includes a pilot burner <NUM> including a single fuel conduit <NUM> for supplying a fuel, which is surrounded by an air conduit <NUM> for supplying air. Single fuel conduit <NUM> of pilot burner <NUM> couples to an elongated fuel conduit <NUM> of pilot lance <NUM> and extending through hood <NUM> to couple to a fuel supply line <NUM>. The fuel can be liquid, e.g., oil, or gas, e.g., natural gas. Air conduit <NUM> of pilot burner <NUM> couples to an elongated air conduit <NUM> of pilot lance <NUM>, which extends concentrically for at least part of the length of elongated fuel conduit <NUM>.

Elongated air conduit <NUM> may include one or more inlets <NUM> through which high pressure air may enter. As noted, high-pressure air for combustion zone <NUM> may enter outer sleeve <NUM> (<FIG>) from an annular plenum <NUM>. Compressor <NUM> (<FIG>) supplies this high-pressure air to plenum <NUM> (<FIG>) of casing <NUM>. The high pressure air may also be routed in a wide variety of ways from hood <NUM> to elongated air conduit <NUM>. Pilot lance <NUM> includes only single fuel conduit <NUM>, i.e., no more than one fuel is supplied by pilot lance <NUM>.

<FIG> and <FIG> show two cross-sectional views of pilot burner <NUM>. As will be described in more detail, <FIG> shows a cross-sectional view through: a) a plurality of passages <NUM> allowing crossover of fuel from an inner position to an outer position, and b) a plurality of cooling passages <NUM> in an end plate or heat shield <NUM> of pilot burner <NUM>. In contrast, <FIG> shows a cross-sectional view through: a) a plurality of passages <NUM> allowing crossover of air from an outer position to an inner position, and b) end plate <NUM> of pilot burner <NUM> where cooling passages <NUM> (<FIG> and <FIG>) are not existent. In <FIG> and <FIG>, arrows for showing the flow of fluids, i.e., fuel and air, are shown in dashed lines where the passage in which the fluid is flowing is at least partially hidden and perhaps entirely hidden, and the arrows are in solid lines where the passage is visible. Air is shown with thinner lined arrows, and fuel is shown with thicker lined arrows.

In pilot burner <NUM>, single fuel conduit <NUM> includes an inner conduit <NUM> for supplying the fuel, and air conduit <NUM> includes an outer conduit <NUM> for supplying air. Outer conduit <NUM> may be concentric with inner conduit <NUM>. Inner conduit <NUM> of pilot burner <NUM> is in fluid communication with elongated fuel conduit <NUM>, and outer conduit <NUM> of pilot burner <NUM> is in fluid communication with elongated air conduit <NUM>. The conduits can be physically coupled using any now known or later developed technique, e.g., welding, press fits, etc..

Pilot burner <NUM> includes an inner wall <NUM> defining an inner plenum <NUM>. Pilot burner <NUM> may also include a partition wall <NUM> radially outward of inner wall <NUM> and defining an intermediate plenum <NUM> with at least a portion of inner wall <NUM>. As shown best in <FIG>, inner wall <NUM> includes a plurality of exit passages <NUM> for fluidly coupling inner plenum <NUM> to intermediate plenum <NUM>. Any number of exit passages <NUM> may be provided. Pilot burner <NUM> also includes an outer wall <NUM> defining an outer plenum <NUM> with at least a portion of partition wall <NUM>.

Pilot burner <NUM> includes a crossover section <NUM> (highlighted by a box in <FIG> and <FIG>). Crossover section <NUM> allows transition of fuel and air in a manner to allow cooling of pilot burner <NUM>. Crossover section <NUM>, which is in fluid communication with the inner and outer conduits <NUM>, <NUM>, includes passages <NUM> fluidly coupling inner (fuel) conduit <NUM> to outer plenum <NUM> and passages <NUM> fluidly coupling outer (air) conduit <NUM> to inner plenum <NUM>. As best shown in <FIG>, plurality of passages <NUM> fluidly couple inner conduit <NUM> (for fuel) to outer plenum <NUM>. Passages <NUM> start in fluid communication with inner conduit <NUM> and terminate in fluid communication with outer plenum <NUM>. Any number of passages <NUM> may be used. As best shown in <FIG>, crossover section <NUM> also includes plurality of passages <NUM> fluidly coupling outer conduit <NUM> (air) to inner plenum <NUM>. Passages <NUM> start in fluid communication with outer conduit <NUM> and terminate in fluid communication with inner plenum <NUM>. Any number of passages <NUM> may be used. Crossover section <NUM> also couples the various walls <NUM>, <NUM>, <NUM> to the walls of conduits <NUM>, <NUM>.

Pilot burner <NUM> also includes an end plate <NUM>, also sometimes referred to as a heat shield, including a plurality of openings in fluid communication with burner interior <NUM> (<FIG>). <FIG> shows an end view of end plate <NUM>. (<FIG> also shows the cross-sectional view lines <NUM>-<NUM> and <NUM>-<NUM> for <FIG> and <FIG>, respectively. ) As shown in <FIG>, end plate <NUM> is a disc-like structure coupled to inner wall <NUM>. End plate <NUM> is not coupled to partition wall <NUM> and outer wall <NUM>. In this manner, end plate <NUM> allows for some relative motion of inner portions (e.g., inner wall <NUM> and interconnected structure) relative to the stiffer outer portions (e.g., partition wall <NUM>, outer wall <NUM> and interconnected structure) that direct fuel through pilot burner <NUM>.

End plate <NUM> acts as a terminus of pilot burner <NUM>. End plate <NUM> includes plurality of openings therethrough to direct the fluids (fuel and air) into combustion zone <NUM>. The openings may include a set of fuel exit openings <NUM> in fluid communication with outer plenum <NUM> (<FIG> and <FIG>), which holds fuel. The openings may also include a set of air exit openings <NUM> adjacent set of fuel exit openings <NUM> and in fluid communication with intermediate plenum <NUM> (<FIG> and <FIG>), which holds pressurized air. The openings may also include a set of cooling openings <NUM> in fluid communication with inner plenum <NUM>, i.e., via cooling passages <NUM> (shown in <FIG> and by dashed lines in <FIG>), which holds pressurized air. In this manner, fuel exits via fuel exit openings <NUM> and is mixed with air exiting air exit openings <NUM>. Air also exits cooling openings <NUM> passing radially through end plate <NUM> to cool end plate <NUM>.

As shown in <FIG>, a set of air exit openings 262A may be adjacent fuel exit openings <NUM>, and another set of air exit openings 262B may be radially outward of cooling openings <NUM>. <FIG> shows how sets of air exit openings 262A, 262B may collectively form a generally circumferentially extending opening in pilot burner <NUM>. The fuel and air pressures can be controlled by the sources of fuel (e.g., pump) and source of pressurized air (e.g., compressor bleed), and also by the size of openings <NUM>, <NUM>, <NUM>. Any number of the openings <NUM>, <NUM>, <NUM> may be used to cool end plate <NUM> and create the desired fuel/air mixture for pilot combustion within mixing tube <NUM>. In particular, any number of cooling passages <NUM> may be used within end plate <NUM>.

In certain embodiments, as shown in <FIG> and <FIG>, outer plenum <NUM> may also include a throat section <NUM> to constrict flow of fuel through outer plenum <NUM>. The restriction on flow of fuel in outer plenum <NUM> acts to smooth flow distribution from fuel exiting passages <NUM> into fuel exit openings <NUM>. Throat section <NUM> may also result in increased cooling of crossover section <NUM>. Accordingly, the stiffness of crossover section <NUM> can be greater than adjacent sections because it does not experience extensive thermal expansion and contraction. Throat section <NUM> may include a radially outward protrusion <NUM> on partition wall <NUM> and an opposing, radially inward protrusion <NUM> on outer wall <NUM>. Radially outward protrusion <NUM> and radially inward protrusion <NUM> define a throat passage <NUM> having a first cross-sectional area. In contrast, partition wall <NUM> and outer wall <NUM> define a plenum passage <NUM> upstream and downstream of protrusions <NUM>, <NUM> (that is, to both sides of protrusions <NUM>, <NUM>) having a second cross-sectional area that is greater than the first cross-sectional area. The sizing of first cross-sectional area thus creates a controllable restriction in flow of fuel through outer plenum <NUM> that can be employed to smooth flow distribution of air exiting passages <NUM> into fuel exit openings <NUM>, and control cooling of, for example, crossover section <NUM>.

Pilot burner <NUM> may be made of any metal or metal alloy appropriate for the environmental conditions in burner <NUM>. As noted, crossover section <NUM> is relatively inflexible compared to adjacent sections. More particularly, outer wall <NUM> may be radially flexible, whereas crossover section <NUM> and end plate <NUM> are less flexible than outer wall <NUM>. In at least one embodiment, pilot burner <NUM> may be produced using additive manufacturing techniques and equipment (such as direct metal laser sintering or direct metal laser melting), which facilitates the formation of various intricate features within pilot burner <NUM>.

Referring to <FIG> and <FIG>, pilot lance <NUM> and pilot burner <NUM> are positioned in an operative position downstream of a combustor end <NUM> of swirl generator <NUM> in burner interior <NUM>. That is, pilot burner <NUM> is downstream of swirl generator <NUM>. A longitudinal position of pilot burner <NUM> downstream of combustor end <NUM> of swirl generator <NUM> may be adjustable. More particularly, a longitudinal position of pilot lance <NUM> and pilot burner <NUM> can be user selected. Pilot lance <NUM> is coupled near hood <NUM>, for example, to a stationary fuel input member <NUM> that couples fuel supply line <NUM> to elongated fuel conduit <NUM>. In one non-limiting example, the longitudinal position of pilot lance <NUM> can be controlled by selecting a size and/or a number of spacer(s) <NUM> between a mount member <NUM> of pilot lance <NUM> and fuel input member <NUM> or other stationary structure near hood <NUM>. The larger the collective dimensions of spacer(s) <NUM>, the less pilot lance <NUM> extends into burner interior <NUM>. Spacer(s) <NUM> include openings (not shown) through which fasteners <NUM>, such as bolts, can fasten mount member <NUM> to, for example, fuel input member <NUM>.

<FIG> shows an embodiment with no spacers <NUM>. Consequently, pilot lance <NUM> is as far into burner interior <NUM> as possible with a given length of elongated fuel conduit <NUM> and elongated air conduit <NUM>. <FIG> shows a number of spacers <NUM> positioning the same pilot lance <NUM> as in <FIG> farther upstream in burner interior <NUM>. While a particular structure has been illustrated to allow different longitudinal positioning of pilot lance <NUM> and pilot burner <NUM>, it will be recognized that a wide variety of alternative structures may be employed. In some instances, the extent of how far pilot burner <NUM> extends into burner interior <NUM> can be automated, e.g., using linear actuators under control of a burner controller. A length of elongated fuel conduit <NUM> and elongated air conduit <NUM> can also be user selected to control the positioning of pilot burner <NUM> in burner interior <NUM>.

As described herein, embodiments of the disclosure provide a burner and a pilot burner for a combustor that uses a single fuel and air and that can be selectively positioned within a burner interior to provide, inter alia, improved combustion stability, quality and firing temperature control.

Accordingly, a value modified by a term or terms, such as "about," "approximately" and "substantially," are not to be limited to the precise value specified. Here and throughout the specification and claims, range limitations may be combined and/or interchanged; such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. "Approximately," as applied to a particular value of a range, applies to both end values and, unless otherwise dependent on the precision of the instrument measuring the value, may indicate +/- <NUM>% of the stated value(s).

The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present disclosure has been presented for purposes of illustration and description but is not intended to be exhaustive or limited to the disclosure in the form disclosed.

Claim 1:
A pilot burner (<NUM>) for a combustor (<NUM>), the pilot burner (<NUM>) comprising:
an inner conduit (<NUM>) configured to deliver a fuel;
an outer conduit (<NUM>) concentric with the inner conduit (<NUM>) and configured to deliver air;
an end plate (<NUM>) including a plurality of openings (<NUM>, <NUM>, <NUM>) in fluid communication with a burner interior (<NUM>);
an inner wall (<NUM>) defining an inner plenum (<NUM>);
a partition wall (<NUM>) radially outward of the inner wall (<NUM>) and defining an intermediate plenum (<NUM>) with at least a portion of the inner wall (<NUM>), the inner wall (<NUM>) including a plurality of exit passages (<NUM>) for fluidly coupling the inner plenum (<NUM>) to the intermediate plenum (<NUM>);
an outer wall (<NUM>) defining an outer plenum (<NUM>) with at least a portion of the partition wall (<NUM>);
a crossover section (<NUM>) in fluid communication with the inner and outer conduit (<NUM>, <NUM>), the crossover section (<NUM>) including a first plurality of passages (<NUM>) fluidly coupling the inner conduit (<NUM>) to the outer plenum (<NUM>) and a second plurality of passages (<NUM>) fluidly coupling the outer conduit (<NUM>) to the inner plenum (<NUM>); and wherein
the plurality of openings (<NUM>, <NUM>, <NUM>) of the end plate (<NUM>) include a set of fuel exit openings (<NUM>) in fluid communication with the outer plenum (<NUM>), a set of air exit openings (262A, 262A-B) adjacent the set of fuel exit openings (<NUM>) and in fluid communication with the intermediate plenum (<NUM>), and a set of cooling openings (<NUM>) in fluid communication with the inner plenum (<NUM>).