Methods of repairing tubes in bundled tube fuel injectors

Abstract

To provide methods of repairing tubes in bundled tube fuel injectors.MEANS FOR SOLVING THE PROBLEM: A method of repairing a fuel injector (100) including a plurality of pre-mix tubes (118) that each extend from a fuel plenum (120) to an outlet portion (144) includes steps of: removing the outlet portion from at least one pre-mix tube to define an exposed end portion (204), and machining an inner surface (158) of the at least one pre-mix tube at the exposed end portion to form an increased inner diameter (D2) relative to an inner diameter (D1) of the pre-mix tube upstream from the exposed end portion, ;and coupling a tube tip (156) to the exposed end portion.SELECTED DRAWING: Figure 12

Description

[Background technology]

[0001] The field of the disclosure relates generally to bundled tube fuel injectors for use in rotary machines, and more particularly to a method of repairing one or more pre-mix tubes of a bundled tube fuel injector.

[0002] Gas turbine engines are widely used in industrial and power generation applications. A conventional gas turbine engine includes a compressor section, a combustor section downstream of the compressor section, and a turbine section downstream of the combustor section. A working fluid, such as ambient air, enters the compressor section and is compressed before entering the combustor section. The compressed working fluid is mixed with fuel and combusted in the combustor section to generate combustion gases that expand through the turbine section to rotate a power generating shaft.

[0003] In at least some known gas turbine engines, the combustion section includes one or more combustors spaced annularly between the compressor section and the turbine section. At least some known combustor designs include one or more axially extending bundle tube fuel injectors upstream of the combustion chamber. The fuel injectors facilitate mixing of the fuel and compressed working fluid before the mixture is channeled toward the combustion chamber. The bundle tube fuel injectors typically include a number of premix tubes arranged radially and circumferentially across the fuel injector. The premix tubes extend generally parallel to one another between a fuel distribution module of the bundle tube fuel injector and the combustion chamber.

[0004] During operation, compressed working fluid is routed from the compressor section through the inlets of each premix tube upstream of the fuel distribution module. Fuel is supplied to the fuel distribution module and is injected into the premix tubes through one or more fuel ports. The fuel and compressed working fluid are mixed in the premix tubes before being channeled into the combustion chamber. The downstream ends of the premix tubes are exposed to extreme temperatures due to their close proximity to the combustion chamber and / or combustion flame, which can cause damage to the downstream ends of the premix tubes over time. Often this damage is the result of thermal stresses and oxidation, requiring periodic inspection and possibly repair of the bundle tube fuel injector.

[0005] However, existing methods for repairing bundle tube fuel injectors are limited. For example, in some cases, a damaged downstream end portion is typically removed and replaced by a tube tip that is joined to the remainder of the premix tube by known techniques including brazing, welding, adhesive cladding, and the like. However, material (e.g., brazing or weld filler) used to connect the tube tip to the remainder of the premix tube may accumulate within the premix tube. Additionally and / or alternatively, due to manufacturing tolerances, an axial offset may exist between the pre-mix tip and the corresponding tube tip. Material accumulated within the axial offset between the pre-mix tube and the corresponding tube tip may impede or restrict the flow of the fuel / working fluid mixture therethrough. As a result, an opportunity for the combustion flame to be interrupted may result in reduced combustor performance, efficiency, and / or life.

[0006] Thus, a need exists for an improved method of repairing damaged tubes in bundle tube fuel injectors. In particular, it is desirable to repair bundle tube fuel injectors without significantly reconfiguring or redesigning existing premix tubes, and in a manner that facilitates reducing or eliminating the opportunity for tube tip connections to disrupt combustion flame holding within the combustor. Summary of the Invention

[0007] In one aspect, a method of repairing a fuel injector including a plurality of premix tubes each extending from a fuel plenum to an outlet portion is provided that includes removing an outlet portion from at least one premix tube to define an exposed end portion, machining an interior surface of the at least one premix tube at the exposed end to form an increased inner diameter relative to an inner diameter of the premix tube upstream from the exposed end, and bonding a tube tip to the exposed end.

[0008] In another aspect, a method is provided for repairing a fuel injector having a plurality of premix tubes each extending downstream from a fuel plenum to an outlet portion, the method including removing an outlet portion from the premix tube to define an exposed end, machining an inner surface of the premix tube at the exposed end to produce an inwardly tapered machined surface having an inner diameter at the exposed end that is larger than an inner diameter upstream from the exposed end, and bonding a tube tip to the exposed end to form a junction between the tube tip and the exposed end, the tube tip having an inwardly tapered machined surface extending between the junction and the inner surface of the tube tip, the inwardly tapered machined surface of the tube tip complementing the inwardly tapered machined surface to define the larger inner diameter at the junction.

[0009] In another aspect, a method of repairing a fuel injector including a plurality of premix tubes each extending from a fuel plenum to an outlet portion is provided, the method including removing outlet portions from the plurality of premix tubes along cut lines to define exposed ends of the plurality of premix tubes, machining an inner surface of each premix tube at the exposed end to form an increased inner diameter relative to an inner diameter of the premix tube upstream from the exposed end, and coupling a tube tip to each exposed end. [Brief description of the drawings]

[0010] These and other features, aspects, and advantages of the present disclosure will become better understood from the following detailed description taken in conjunction with the accompanying drawings. [Figure 1] 1 is a schematic diagram of an exemplary gas turbine system. [Diagram 2] FIG. 2 is a simplified cross-sectional side view of an exemplary combustor included in the gas turbine engine of FIG. 1. [Diagram 3] 3 is a perspective view of an example bundle tube fuel injector included in the combustor of FIG. 2. [Figure 4] FIG. 3 is a rear perspective view of the fuel injection device shown in FIG. 2. [Diagram 5] FIG. 3 is a side view of the fuel injection device shown in FIG. 2. [Figure 6] FIG. 3 is a schematic cross-sectional side view of the fuel injection device shown in FIG. 2. [Figure 7] FIG. 2 is an enlarged cross-sectional side view of an exemplary tube tip fixedly joined to a remaining portion of a premix tube of a fuel injector after removal and machining operations. [Figure 8] 13 is an enlarged cross-sectional side view of yet another exemplary tube tip fixedly joined to a remaining portion of the premix tube after removal and machining operations; FIG. [Figure 9] 1 is an enlarged cross-sectional side view of a further exemplary tube tip fixedly joined to a remaining portion of the premix tube after removal and machining operations; FIG. [Figure 10] FIG. 10 is an enlarged view of a portion C(1) indicated by a dotted line in FIG. [Figure 11] 13 is an enlarged cross-sectional side view of yet another exemplary tube tip fixedly joined to a remaining portion of the premix tube after removal and machining operations; FIG. [Figure 12] 6 is an exemplary method 600 for repairing a fuel injector including multiple premix tubes.

[0011] Corresponding reference characters used throughout the drawings indicate corresponding parts.

[0012] Unless otherwise indicated, the drawings provided herein are intended to illustrate features of embodiments of the present disclosure. These features are believed to be applicable in a wide variety of systems that include one or more embodiments of the present disclosure. As such, the drawings are not intended to include all conventional features known by those skilled in the art to be necessary for the implementation of the embodiments disclosed herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Embodiments described herein relate to a method of repairing a bundle tube fuel injector used in a combustor of a rotary machine (e.g., a gas turbine engine). An exemplary fuel injector includes a plurality of premix tubes extending between a fuel plenum and an outlet section. Fuel is injected into each premix tube in the fuel plenum, where the fuel mixes with a compressed working fluid in the premix tube to form a combustible mixture. The outlet sections of the premix tubes define an outlet through which the combustible mixture is channeled toward a combustion chamber. The outlet sections of the premix tubes are exposed to extreme temperatures and high mechanical loads during combustion that can result in damage to the outlet sections, for example, by thermal stresses and oxidation. The method described herein includes removing one or more damaged outlet sections of the premix tubes and replacing each removed outlet section with a tube tip to repair or refurbish the one or more premix tubes.

[0014] The connections formed between the tube tips and the premix tubes may facilitate impeding or restricting the flow of the combustible mixture that may disrupt the combustion flame in the combustion chamber and / or reduce flame retention in the combustor. For example, the tube tips may be bonded to the premix tubes via brazing, welding, adhesive cladding, etc., and the filler material used to bond the components may undesirably accumulate within the premix tubes and / or tube tips. The accumulated material may impede or restrict the flow or cause flow disturbances of the combustible mixture. Additionally, due to manufacturing tolerances, the premix tubes and tube tips may operate with a slight offset in the axial alignment therebetween, which may impede, restrict, or cause flow disturbances of the combustible mixture.

[0015] An exemplary method described herein includes, after removing the damaged outlet portion, machining the exposed end portion of the premix tube to create a suitable configuration of the premix tube that facilitates reducing or eliminating the opportunity for the connection between the premix tube and the tube tip to impede or restrict the flow of the combustible mixture therethrough. For example, at the exposed end where the tube tip is attached, the premix tube may be machined to a larger diameter that provides additional interior space for the filler material used in the connection between the tube tip and the premix tube to accumulate, without the accumulation becoming an impediment to the premix tube and the combustible mixture flowing through the tube tip. The larger diameter also facilitates reducing or eliminating the adverse effect that the axial alignment offset between the premix tube and the tube tip has on the flow of the combustible mixture therethrough. In this manner, the premix tube may be repaired or refurbished along with the corresponding tube tip in a manner that maintains the performance, efficiency, and / or life of the combustor.

[0016] When introducing elements of various embodiments disclosed herein, the articles "a," "an," "the," and "said" are intended to mean one or more of the element and include plural references unless the context clearly indicates otherwise. "Optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and the description includes cases where the event occurs and cases where it does not occur. Furthermore, references to "one embodiment" are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Furthermore, unless expressly stated to the contrary, the terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0017] Unless otherwise indicated, approximation words such as "generally," "substantially," "approximately," and "about" used herein indicate that the term so modified may apply only to an approximate degree as would be recognized by one of ordinary skill in the art, and not to an absolute or complete degree. Thus, a value modified by a term such as "about," "approximately," or "substantially" is not intended to be limited to the exact value specified. In at least some instances, the approximation may correspond to the precision of an instrument for measuring the value.

[0018] Unless otherwise indicated, the terms "first," "second," etc. are used herein merely as labels and are not intended to impose any order, position, or hierarchical requirements on the items to which they refer. Moreover, reference to, for example, a "second" item does not require or exclude the presence of, for example, a "first" or lower-numbered item, or a "third" or higher-numbered item.

[0019] The terms "upstream" and "downstream" refer to relative directions with respect to fluid flow in a fluid pathway. For example, "upstream" refers to the direction in which the fluid flows, and "downstream" refers to the direction in which the fluid flows. Directional terms such as "radial," "axial," "circumferential," "forward," and "aft" are used for ease of description only and are not intended to limit a particular direction unless the context clearly indicates otherwise.

[0020] Referring now to the drawings, Figure 1 is a schematic cross-sectional view of an exemplary gas turbine engine 10. The gas turbine engine 10 includes a compressor section 12 including an inlet 14 defined at an upstream end 15 of the gas turbine engine 10 and a casing 16 at least partially surrounding the compressor section 12. The gas turbine engine 10 also includes a combustion section 18 including a combustor 20 downstream from the compressor section 12, and a turbine section 22 downstream from the combustion section 18. An outer casing 17 at least partially surrounds the turbine section 22. A rotor shaft 24 extends axially within the gas turbine engine 10. The combustion section 18 may include a plurality of combustors 20.

[0021] In operation of the gas turbine engine 10, a working fluid (e.g., air) 26 is drawn into the inlet 14 of the compressor section 12 and progressively compressed to provide a compressed working fluid 28 to the combustion section 18. The compressed working fluid 28 enters the combustion section 18 and is mixed with fuel 29 in the combustor 20 to form a combustible mixture. The combustible mixture is combusted in the combustor 20, thereby generating hot gases 30 which pass from the combustor 20 across a turbine nozzle 34 and a first stage 32 of turbine blades 36 into the turbine section 22. The hot gases 30 are coupled to a turbine nozzle 34 and a first stage 32 of turbine blades 36 along an axial centerline C of the shaft 24. LThe hot gas flows along the axial direction of the shaft 24 and rapidly expands through alternating stages (e.g., a first stage 32 and a second stage 33 downstream of the first stage 32) of turbine blades 36 and turbine nozzles 34 coupled within the turbine section 22. Thermal and / or kinetic energy is transferred from the hot gas to each stage of the turbine blades 36, which rotates the shaft 24 and produces mechanical work. The shaft 24 may be coupled to a load, such as a generator (not shown), to produce electricity. The shaft 24 may also be used to drive the compressor section 12 of the gas turbine engine 10.

[0022] FIG. 2 is a simplified cross-sectional side view of a combustor 20 included in the gas turbine engine 10 (FIG. 1). The combustor 20 includes an exemplary bundle tube fuel injector 100. The combustor 20 is at least partially surrounded by an outer casing 38. The outer casing 38 at least partially defines a high pressure plenum 40 around the combustor 20. The high pressure plenum 40 may be in fluid communication with the compressor section 12 (FIG. 1) or other source for supplying the compressed working fluid 28 to the combustion section 18. An end cover 42 is coupled to the outer casing 38. The end cover 42 may be in fluid communication with a fuel supply 44 that channels the fuel 29 toward the combustion section 18.

[0023] The bundle tube fuel injector 100 may extend downstream from and be in fluid communication with the end cover 42. The fuel injector 100 receives fuel 29 from a fuel supply 44, and a fluid conduit 46 may fluidly couple the end cover 42 and / or the fuel supply 44 to the bundle tube fuel injector 100. One end of an annular liner 48, such as a combustion liner and / or transition duct, surrounds a downstream end 102 of the bundle tube fuel injector 100 and at least partially defines a combustion chamber 50 within the combustor 20. The liner 48 at least partially defines a hot gas path 52 that directs the hot gases 30 from the combustion chamber 50 through the combustor 20. The hot gas path 52 may channel the hot gases 30 toward the turbine section 22.

[0024] In operation of the combustor 20, the compressed working fluid 28 is channeled toward the end cover 42 where it reverses direction to flow through one or more bundle tube fuel injectors 100. Fuel 29 is supplied to the bundle tube fuel injectors 100, where the fuel 29 and the compressed working fluid 28 are premixed or mixed into a combustible mixture that is injected into the combustion chamber 50 for combustion.

[0025] With reference to Figures 3-6, various views of an exemplary bundle tube fuel injector 100 are shown. The fuel injector 100 is shown in a simplified manner in Figures 3-6 for ease of illustration and explanation. Figure 3 is a perspective view of the fuel injector 100 coupled to a fluid conduit 46. Figure 4 is a rear perspective view of the fuel injector 100. Figure 5 is a side view of the fuel injector 100, and Figure 6 is a schematic cross-sectional side view of the fuel injector 100.

[0026] In the exemplary embodiment, fuel injector 100 extends axially between upstream end 104 and downstream end 102 and defines an axial centerline 106. Fuel injector 100 includes a fuel inlet 108 at upstream end 104 that provides fluid communication between fuel supply 44 ( FIG. 2 ) and a fuel distribution module 110 via fluid conduit 46. Fuel distribution module 110 includes a shroud 112 that defines a fuel plenum 120 (shown in FIG. 6 ) therein. Fluid conduit 46 and fuel inlet 108 provide fluid communication between fuel supply 44 ( FIG. 2 ) and fuel plenum 120. Fuel injector 100 also includes a support plate 114 upstream of shroud 112. For simplicity, support plate 114 is omitted from FIGS. 4 and 5 . Support plate 114 provides a plurality of inlet tubes 116 extending axially outwardly from support plate 114 on an opposite side from shroud 112. Each inlet tube 116 is substantially axially aligned with one of a bundle of premix tubes 118 that extend axially outwardly through the shroud 112 on the side opposite the support plate 114 .

[0027] As shown in FIG. 6, the shroud 112 includes a pair of axially spaced apart first and second plates 122 and 124 extending circumferentially generally radially outward relative to the axial centerline 106 of the fuel injector 100. The first and second plates 122 and 124 define a fuel plenum 120 therebetween. An outer band 126 extends axially between the first and second plates 122 and 124 and circumferentially surrounds the fuel plenum 120. Each of the first and second plates 122 and 124 includes tube passages 128 and 130 defined therein, respectively. Each tube passage 128 defined in the first plate 122 is axially aligned with a tube passage 130 defined in the second plate 124 to allow a portion of one of the bundles of premix tubes 118 to extend therethrough. The fuel inlets 108 extend axially outward from the first plate 122. The second plate 124 includes a central nozzle passage 132 extending axially therethrough. The fuel inlets 108 and the central nozzle passage 132 are axially aligned along the axial centerline 106 of the fuel injector 100. The fuel inlets 108 provide access to the fuel plenum 120 through the first plate 122, and the central nozzle passage 132 provides access to the fuel plenum 120 through the second plate 124.

[0028] The support plate 114 extends radially outward and circumferentially relative to the axial centerline 106 of the fuel injector 100 and is adjacent to the first support plate 122 of the shroud 112 at the upstream end 104 of the fuel injector 100. The support plate 114 is shown axially spaced from the first plate 122 of the shroud 112 in FIG. 6 for ease of illustration. When the fuel injector 100 is assembled (as shown in FIG. 3 ), the support plate 114 may be adjacent to, in contact with, and / or coupled to the first plate 122. The support plate 114 may be coupled to the shroud first plate 122 via any suitable means (e.g., welding, brazing, mechanical fasteners, etc.). In certain embodiments, the support plate 114 is removably coupled to the first plate 122 (e.g., using fasteners).

[0029] The support plate 114 includes inlet tubes 116 extending from corresponding tube passages 134 defined in the support plate 114. Each inlet tube 116 includes an open inlet end 117 in communication with a corresponding tube passage 134. Each tube passage 134 defined in the support plate 114 is substantially axially aligned with a tube passage 128 defined in the first plate 122 to provide fluid communication between the inlet tube 116 and a corresponding premix tube 118. The support plate 114 also includes a central fuel inlet passage 136 extending axially therethrough. The central fuel inlet passage 136 is substantially axially aligned with and receives the fuel inlet 108. The fluid conduit 46 ( FIG. 3 ) may be coupled to the fuel inlet 108 and / or the central nozzle passage 132 to provide fluid communication between the end cover 42 and / or the fuel supply 44 ( FIG. 2 ) and the fuel plenum 120. The fuel inlet 108, the central nozzle passage 132 in the second plate 124, and the central nozzle passage 136 in the support plate 114 are each substantially axially aligned along the axial centerline 106 of the fuel injector 100. A fluid cartridge or fuel nozzle 138 may be coupled to the central nozzle passage 132 and extend axially outward from the shroud 112 toward the combustion chamber 50 ( FIG. 2 ).

[0030] The premix tubes 118 extend generally parallel to one another along or substantially parallel to the axial centerline 106 of the fuel injector 100. The premix tubes 118 extend axially from a first plate 122 through a second plate 124 of the shroud 112 toward the combustion chamber 50 ( FIG. 2 ). In particular, a first or inlet portion 140 of each premix tube 118 extends through the fuel plenum 120 between the first plate 122 and the second plate 124. Similarly, a second or middle portion 142 of each premix tube 118 extends axially outward from the second plate 124, and a third or outlet portion 144 of each premix tube 118 extends axially outward from the middle portion 142 toward the combustion chamber 50. Each premix tube 118 is disposed or seated within axially aligned tube passages 128 and 130 of the shroud 112. The intermediate and exit portions 142, 144 of the premix tubes 118 may "float," i.e., the tubes 118 may extend from the shroud 112 without additional support downstream from the shroud 112. In other embodiments, a downstream support plate (not shown) may support the tube passages that each receive the intermediate and / or exit portions 142, 144 of a corresponding premix tube 118 and limit their movement in response to vibrations and / or mechanical loads during operation of the combustor 20.

[0031] The premix tubes 118 may be formed from a single continuous tube or may be formed from two or more coaxially aligned tubes that are securely joined (e.g., by brazing, welding, or other suitable means). Although generally illustrated as cylindrical, the premix tubes 118 may be other geometric shapes, and the premix tubes 118 are not limited to having a particular cross-sectional shape unless the context clearly dictates otherwise. Additionally, the premix tubes 118 may be grouped or arranged in circles, triangles, squares, or other geometric shapes, and may be arranged in various numbers and geometric shapes.

[0032] The fuel injector 100 may include any number of premix tubes 118, and the premix tubes 118 may be arranged in any suitable arrangement. As shown in FIG. 4 , the premix tubes 118 are arranged in a number of rows 146. Each row 146 may include one or more premix tubes 118. In one embodiment, each row 146 is radially spaced apart from an adjacent row 146 relative to the axial centerline 106. At least some of the premix tubes 118 in the rows 146 may be arranged in an annular or arcuate arrangement relative to the axial centerline 106. Additionally and / or alternatively, at least some of the premix tubes 118 in the rows 146 may be arranged linearly and generally perpendicular to the axial centerline 106 of the fuel injector 100.

[0033] Each premix tube 118 includes an inlet 148 defined in the inlet portion 140 and upstream from the fuel plenum 120. The inlet is substantially axially aligned with a tube passage 128 of the shroud first plate 122, and thereby aligned with a corresponding tube passage 134 of the support plate 114 and the inlet tube 116. The inlet 117 of the inlet tube 116 provides fluid communication between the inlet 148 of the corresponding premix tube 118 and the high pressure plenum 40 (FIG. 2) and / or the compressor section 12 (FIG. 1). Each premix tube 118 also includes an outlet 150 defined in the outlet portion 144 and downstream from the fuel plenum 120. The outlet 150 of each premix tube 118 is in fluid communication with the combustion chamber 50 (FIG. 2). A tube channel 152 extends the distance between the inlet 148 and the outlet 150 of each premix tube 118. Each premix tube 118 is aligned along the inner diameter of the tube channel 152 (e.g., inner diameter D 2 shown in FIGS. 7-9 and 11 ). 1 ) and the outer diameter of the premix tube 118 (e.g., the outer diameter D 3 ) and an outer surface 160 defining an inlet 148 and an outlet 150. Opposite end surfaces 162, 164 of the premix tube 118 extend radially between and join the inner surface 158 and the outer surface 160 adjacent the inlet 148 and outlet 150, respectively.

[0034] In the exemplary fuel injector 100, the pre-mix tubes 118 are substantially axially coextensive with one another such that the end surfaces 164 are aligned substantially flush with each other at the downstream end 102 of the fuel injector 100. In other embodiments, the pre-mix tubes 118 may have different axial lengths and some of the end surfaces 164 may extend beyond the other end surfaces 164 at the downstream end 102. 1 , outer diameter D 3 may be substantially constant along the entire axial length of the premix tube 118 such that the end faces 162, 164 have approximately the same radial distance between the inner and outer sides 158, 160, respectively. 1 , and / or outer diameter D 3 , may vary along the axial length of the premix tube 118 such that each end face 162, 164 defines a different radial distance between the inner and outer surfaces 158, 160, respectively. The inlet portion 140 of each premix tube 118 has one or more fuel ports 154 defined therein downstream of the inlet 148. The fuel ports 154 extend radially through the inner and outer surfaces 158, 160 of the premix tube 118. The fuel ports 154 provide fluid communication between the fuel plenum 120 and the corresponding premix tube channels 152 within the premix tube 118.

[0035] During operation, the compressed working fluid 28 flows through the high pressure plenum 40 toward the upstream end 104 of the fuel injector 100 and into the inlets 117 of the inlet tubes 116. The compressed working fluid 28 flows through the inlet tubes 116 toward the inlets 148 of the premix tubes 118. Fuel 29 flows into the fuel plenum 120 via the fuel inlets 108. The fuel 29 in the fuel plenum 120 is injected into the premix tubes 118 through corresponding fuel ports 154. The compressed working fluid 28 and the fuel 29 mix within the tube channels 152, and the resulting combustible mixture exits each premix tube 118 via the outlets 150. The combustible mixture is then injected into the combustion chamber 50 for combustion. A portion of the fuel 29 entering the fuel plenum 120 may be channeled toward the combustion chamber 50 through the fuel nozzles 138 extending from the central nozzle passage 132. That is, by design, a portion of the fuel 29 supplied to the fuel injector 100 may bypass the premix tubes 118 and mix directly with the combustible mixture exiting the fuel injector 100 within the combustion chamber 50 .

[0036] The exit portion 144 of the premix tube 118 is generally exposed to higher temperatures and higher mechanical loads due to its proximity to the combustion chamber 50 and / or combustion flame compared to other portions of the premix tube 118. This may increase the likelihood that the exit portion 144 will be damaged over time, for example, by prolonged exposure to thermal stresses and oxidation. To repair or refurbish a damaged exit portion 144 of the premix tube 118, the damaged exit portion 144 may be at least partially removed using any suitable means that allows the tube to be cut or otherwise removed. For example, the damaged exit portion 144 of the premix tube 118 may be (at least partially) removed using scoring, electrical discharge machining (EDM), torch cutting, a cutting blade, or the like. In some embodiments, the outlet portions 144 of each of the premix tubes 118 may be at least partially removed in a single cutting operation in which the outlet portions 144 of the premix tubes 118 are at least partially removed along a cut line 166 (shown in FIG. 5 ) that is generally perpendicular to the axial length of the premix tubes 118 and the axial centerline 106 of the fuel injector 100. In other embodiments, one or some of the outlet portions 144 of the premix tubes 118 may be at least partially removed individually while the outlet portions 144 of other premix tubes 118 are not removed.

[0037] Removing the damaged outlet portion 144 and / or further machining the premix tube 118 during and / or after removing the damaged outlet portion 144 (discussed further below) may increase the risk of further damage to the premix tube 118 as a result of vibration and mechanical loads induced by the cutting and / or machining operations. As mentioned above, in some embodiments, the intermediate and outlet portions 142, 144 of the premix tube 118, respectively, may be floating and not supported by additional supports provided downstream from the shroud 112. A temporary support plate (not shown) having a tube passage sized to receive a portion or all of the premix tube 118 may be provided to provide temporary support to the intermediate and / or outlet portions 142, 144 of the premix tube 118, respectively, and to facilitate restraining the tube 118 from moving in response to vibration and / or mechanical loads during cutting and / or machining operations when repairing or refurbishing the premix tube 118. In embodiments in which the outlet portion 144 of each of the premix tubes 118 is at least partially removed in a single cutting operation along cut line 166 (FIG. 5), the temporary support plate may suitably include tube passages to receive and support all of the premix tubes 118.In embodiments where the outlet portions 144 of one or some, and less than all, the pre-mix tubes 118 are at least partially removed individually while the outlet portions 144 of other pre-mix tubes 118 are not removed, the temporary support plate may suitably include a limited number of tube passages that receive and support the pre-mix tubes 118 within a pre-defined or preselected vicinity of the pre-mix tubes 118 individually being cut and / or machined.

[0038] One or more of the removed outlet portions 144 of the premix tube 118 may then be replaced with a tube tip 156 (shown in FIGS. 4 and 5 ) to complete the repair or refurbishment of the premix tube 118. The tube tip 156 may be fixedly secured or bonded to the remainder of the premix tube 118 using any suitable means for joining tubes. For example, one or more of the tube tips 156 may be fixedly bonded to the remainder of the premix tube 118 using furnace brazing, induction brazing, orbital welding, laser welding, friction welding, electron beam welding, diffusion bonding, plasma spraying, thermally resistant adhesive, adhesive cladding, high velocity oxy-fuel coating spraying, and / or any combination thereof, and / or any other bonding technique that enables the tube 118 to be repaired as described herein. The premix tubes 118, including one or more tube tips 156, preferably extend the same axial length after repair as they did before removal of the damaged outlet portions 144. As noted above, in embodiments in which the premix tubes 118 are substantially coaxially aligned with one another, the tube tips 156 preferably retain a coaxial extent such that the tube tips 156 defining end faces are substantially flush with end faces 164 of the other (i.e., unrepaired) premix tubes 118. In embodiments in which the outlet portions 144 are collectively removed along cut lines 166 ( FIG. 5 ), the tube tips 156 replacing the removed outlet portions 144 may be substantially coplanar aligned and define end faces that are substantially coplanar with one another.

[0039] The one or more tube tips 156, like the remainder of the repaired or refurbished one or more premix tubes 118, may be made from dissimilar materials (e.g., dissimilar metals or metal alloys). In some examples, the one or more tube tips 156 may include at least one of nickel, cobalt, chromium, molybdenum, stainless steel, aluminum and / or titanium based alloys. The one or more tube tips 156 may be made from a metal or metal alloy that is suitably resistant to high temperatures. Because the one or more tube tips 156 form only a portion of the repaired or refurbished premix tube 118, the one or more tube tips 156 may be made from a relatively expensive material that is suitable for high or extreme temperatures and may not be practical and / or cost-effective to use to form the entire premix tube 118. In some embodiments, one or more of the tube tips 156 may comprise a metal or metal alloy similar to that used in manufacturing the remainder of the repaired or refurbished premix tube 118. For example, each of the tube tips 156 and the premix tubes 118 may be made from at least one of a nickel, cobalt, chromium, or tungsten based alloy. In some embodiments, each of the tube tips 156 and the premix tubes 118 comprises a cobalt-nickel-chromium-tungsten alloy, such as Haynes® 188 alloy.

[0040] The tube tip 156 may include a wear coating (not shown) that may provide or enhance the oxidation and corrosion performance of the tube tip 156. The wear coating may be applied to the tube tip 156 via plating, coating, etc. In some embodiments, the wear coating may be one of, but is not limited to, chrome, nickel, gel aluminide coating, aluminide coating, TBC, L605 and / or Stellite 6. The wear coating may be applied using any process and / or any method known to those of skill in the art, including, but not limited to, Electron Beam Physical Vapor Deposition (EBPVD), Air Plasma Spray (APS), High Velocity Oxygen Fuel (HVOF), Electrostatic Spray Assisted Vapor Deposition (ESAVD) and / or Direct Vapor Deposition (DVD).

[0041] The tube tips 156 can be formed using any suitable manufacturing technique. For example, the one or more tube tips 156 may be formed using casting, molding, cold-forming (e.g., cold-rolling), extrusion processing, powder metal manufacturing, additive manufacturing or 3D printing, and / or computer machining (e.g., computer numerical control machining). In certain embodiments, the one or more tube tips 156 may be additively manufactured as individual components. As used herein, the term "additively manufactured" or "additive manufacturing process" corresponds to various known 3D printing manufacturing methods, such as, but not limited to, extrusion deposition, wire, granular material bonding, powder bed and inkjet head 3D printing, lamination and photopolymerization.The various technologies related to the various 3D printing methods include but are not limited to unless recited in the claims, fused deposition modeling (FDM), electron beam free-from fabrication (EBF), direct metal laser sintering (DMLS), Electron Beam Melting (EBM), Selective Laser Melting (SLM), Selective Heat Sintering (SHS), Selective Laser Sintering (SLS), Plaster-based 3D Printing (PP), Laminated Object Manufacturing (LOM), Stereolithography (SLA), Digital Light Processing (DLP), etc. Laminated Object Manufacturing (LOM), Stereolithography (SLA) and Digital Light Processing (DLP).

[0042] FIG. 7 is an enlarged cross-sectional side view of an exemplary tube tip 200 fixedly coupled to a remainder 202 of a premix tube 118. The tube tip may be incorporated as one or more of the tube tips 156 shown in FIGS. 4 and 5. The remainder 202 is the portion of the premix tube 118 that remains within the combustor 20 after the damaged outlet portion 144 has been at least partially removed to initiate a repair or refurbishment of the premix tube 118. For ease of explanation, the remainder 202 of the premix tube 118 may also be referred to as the premix tube 202. The premix tube 202 includes an exposed end portion 204 to which the tube tip 200 is fixedly secured or coupled. The end portion 204 extends substantially axially from the intermediate portion 142 to an open end 206 of the premix tube 202. The tube channel 152 of the premix tube 202 extends between the inlet 148 and the open end 206 of the exposed end 204. Stated another way, the premix tube 202 extends substantially axially between the inlet portion 140 , the intermediate portion 142 , and the exposed end portion 204 .

[0043] As shown in FIG. 7, the premix tube 202 is spaced apart from the inner diameter D of the tube channel 152. 1 and an opposing outer surface 160 defining an inner diameter D 1 may be substantially constant along the axial length of the premix tube 118, i.e., between the inlet 148 and the outlet 150, before the outlet portion 144 is damaged and / or removed. In the premix tube 202, the exposed end 204 is adjacent the open end 206 and defines a radially-extending repair end surface 208 opposite the radially-extending end surface 162 adjacent the inlet 148. The end surface 208 extends radially inward from the outer surface 160 and extends from the inner surface 158 with an angled surface 210 that tapers inwardly toward the inner surface 158. The angled surface 210 is aligned with the inner diameter D of the tube channel 152. 1 is the inner diameter D of the open end 206 2Angled angle α relative to inner surface 158 so as to increase 1 The angle α 1 is the inner diameter D at the inner surface 158 1 The inner diameter D at the open end 206 2 For example, in one embodiment, the angle α 1 The outer surface 160 may have an outer diameter D at the open end 206. 3 Define the diameter D 3 may be substantially constant over the axial length of the premix tube 202, or may be substantially constant over the diameter D 3 may vary along the axial length of the premix tube 202.

[0044] The angled surface 210 may be formed by machining the inner surface 158 of the premix tube 202 at the open end 206. Suitable techniques for machining the inner surface 158 to form the angled surface 210 include, for example, electrical discharge machining (EDM), milling, hand grinding, and / or any other suitable machining technique. The inner surface 158 may be machined to form the angled surface 210 during and / or after removing the damaged outlet portion 144 to form the exposed end 204.

[0045] The tube tip 200 includes a mating end 212 and an opposite outlet end 214. The tube tip 200 is open at both ends 212 and 214 and defines a tube tip channel 216 extending therebetween. Similar to the detached outlet portion 144 of the premix tube 118, the tube tip 200 may extend from the intermediate portion 142 toward the combustion chamber 50 ( FIG. 2 ) when the fuel injector 100 is assembled with the tube tip 200 fixedly coupled or secured to the premix tube 202. In an exemplary embodiment, the mating end 212 of the tube tip 200 defines a socket 218 having an outer diameter D 120 having a diameter 120 mm or less that is sized and shaped to receive the exposed end 204 of the corresponding premix tube 202. For example, the socket 218 may have an outer diameter D 120 mm or less that is sized and shaped to receive the exposed end 204 of the corresponding premix tube 202 such that the end 204 of the premix tube 202 can be received in the socket 218. 3 Approximately equal to or outside diameter D 3 Slightly wider inner diameter D 4 2. The socket 218 extends axially across the end 204 relative to an axial centerline 220 of the premix tube 202 and / or tube tip 200. When the end 204 of the premix tube 202 is received in the socket 218, the tube channel 152 is axially aligned with the tube tip channel 216 along the axial centerline 220. The inlet 140 of the premix tube 202 is in fluid communication with the open outlet end 214 of the tube tip 200.

[0046] The tube tip channel 216 is defined by an inner surface 222 that extends axially substantially between the outlet end 214 and a collar 224 of the tube tip 200. The inner diameter D of the tube tip channel 216 is 5 extends across the inner surface 222. The inner diameter D of the tube tip channel 216 5 is the diameter D of the tube channel 152 1The collar 224 extends between the inner surface 222 and a collar surface 228 and provides an angled surface 226 that tapers inwardly from the collar surface 228 toward the inner surface 222. The collar surface 228 extends radially between the angled surface 226 and an inner socket surface 230. The radially extending end face 208 lies adjacent to and may abut the collar surface 228 when the end 204 of the premix tube 202 is received in the socket 218. The inner diameter D of the socket 218 is 4 is the outer diameter D of the end 204 3 , such that when socket 218 receives end 204 , outer periphery 160 of end 204 abuts and / or contacts inner socket surface 230 .

[0047] The angled surface 226 of the collar 224 is angled at an oblique angle α relative to the inner surface 222. 2 This results in an inner diameter D of the tube tip 200. 5 is the inner diameter D at the radially inner end of the collar surface 228 2 The angle α 2 is the inner diameter D at the inner surface 222 of the tube tip channel 216 5 From inner diameter D 2 The angle can be any suitable oblique angle that increases the angle α 2 may be between about 5° and about 60°, between about 5° and about 30°, between about 5° and about 20°, between about 5° and about 10°, between about 10° and about 30°, between about 10° and about 20°, between about 20° and about 60°, between about 20° and about 45°, between about 20° and about 30°, between about 30° and about 60°, between about 30° and about 45°, or between about 45° and about 60°. 5 , inner diameter D of tube channel 152 1 If the angle α of the angled surfaces 210 and 226 is approximately equal to 1 and α 2 are approximately the same for each of the inner surfaces 158 and 222.

[0048] 7, when the end portion 204 of the premix tube 202 is received in the socket 218, the angled surfaces 210 and 226 complement one another and form a substantially mirror image taper at the junction 232 of the end face 208 and collar surface 228. In particular, at the junction 232, the inner diameter D of the fixedly joined or secured premix tube 202 and tube tip 200 is substantially equal to the inner diameter D of the fixedly joined or secured premix tube 202 and tube tip 200. 2 is the inner diameter D of the tube channel 152 1 and then increases to an inner diameter D 5 In other words, the tapered surfaces 210 and 226 reduce the increased inner diameter D of the fixedly joined premix tube 202 and tube tip 200 at the junction 232 of the end face 208 and collar face 228. 2 (Stated differently, the tapered surfaces 210 and 226 provide the increased inner diameter D2 of the fixedly coupled pre-mix tube 202 and tube tip 200 at the junction 232 of the end surface 208 and the collar surface 228).

[0049] The inner diameter D of the premix tube 202 and tube tip 200 fixedly joined or secured at the joint 232 2to facilitate reducing or eliminating the possibility that the connection between the premix tube 202 and the tube tip 200 may impede or restrict the flow of the combustible mixture therethrough, which may disrupt the combustion flame in the combustion chamber 50 ( FIG. 2 ) and / or reduce flame holding in the combustor 20. For example, the technique used to fixedly secure the tube tip 200 to the premix tube 202 (e.g., furnace brazing, induction brazing, orbital welding, laser welding, friction welding, electron beam welding, diffusion bonding, plasma spraying, heat resistant adhesives, adhesive cladding, high velocity oxy-fuel coating spraying, and / or any other known technique that enables the premix tube 202 to function as described herein) may introduce and undesirably accumulate filler material used to join the components within the tube channel 152 and / or tube tip channel 216. The accumulated material may otherwise impede, restrict, or otherwise cause disturbances in the flow of the combustible mixture. However, the increased diameter D at the joint 232 2 provides additional space within the tube channel 152 and / or tube tip channel 216 for such material to accumulate, facilitating reducing or eliminating the adverse effect of the accumulated material on the flow of the combustible mixture through the tube 218.

[0050] Additionally, due to manufacturing tolerances, the shape of the end 204 of the pre-mix tube 202 and the collar 224 of the tube tip 200 adjacent the end 204 when received in the socket 218 may not be perfectly aligned which may cause an offset in the axial alignment between the pre-mix tube 202 and the tube tip 200. An offset in axial alignment between the pre-mix tube 202 and the tube tip 200 may otherwise impede or restrict flow or otherwise create flow perturbations of the combustible mixture. However, the increased diameter D at the junction 232 may cause the pre-mix tube 202 to bend or sag. 2 facilitates reducing or eliminating adverse effects that an offset in axial alignment between the premix tubes 202 and the tube tips 200 may have on the flow of the combustible mixture therethrough. In this manner, one or more premix tubes 202 may be repaired or refurbished with a corresponding tube tip 200 while maintaining the performance, efficiency, and / or life of the combustor 20.

[0051] FIG. 8 is an enlarged cross-sectional side view of another exemplary tube tip 300 fixedly coupled or secured to a remaining portion 302 of the premix tube 118. The remaining portion 302 of the premix tube 118 is also referred to as the premix tube 302. The tube tip 300 includes similar features and components to the tube tip 200, which includes similar features and components to the premix tube 202 described above with reference to FIG. 7. Corresponding reference characters are used in FIGS. 7 and 8 to indicate corresponding parts. In this embodiment, the inner surface 158 of the premix tube 302 is machined to include a concave surface 310 that extends between the end face 208 and the inner surface 158 and interfaces with the inner surface 158. Similar to the angled surface 210 of the premix tube 202, the concave surface 310 is machined to include a concave surface 310 that is aligned with the inner diameter D of the tube channel 152. 1 The inner diameter D of the open end 206 2 to 306. The concave surface 310 may be formed by machining the inner surface 158 of the premix tube 302 at the open end 206. Suitable techniques for machining the inner surface 158 to form the concave surface 310 include, for example, electrical discharge machining (EDM), milling, hand grinding, and / or any other suitable machining technique. The inner surface 158 may be machined to form the concave surface 310 during and / or after removing the damaged outlet portion 144 to form the exposed end 204.

[0052] The collar 224 of the tube tip 300 provides a concave surface 326 that joins the inner surface 222 and the collar surface 228. Similar to the angled surface 226 of the tube tip 200, the concave surface 326 is aligned with the inner diameter D of the tube tip 300. 5 is the inner diameter D at the radially inner end of the collar surface 228. 2 When the end 204 of the premix tube 302 is received in the socket 218 of the tube tip 300, the concave surfaces 310 and 326 complement each other and increase in radius R 1In particular, at junction 332, the fixedly joined or secured premix tube 302 and tube tip 300 form a substantially semicircular shape having an inner diameter D 2 is the inner diameter D of the tube channel 152 1 and then increases to an inner diameter D 5 In other words, concave surfaces 310 and 316 reduce the increased inner diameter D of fixedly joined premix tube 302 and tube tip 300 at junction 332. 2 As mentioned above, the increased diameter D at the junction 332 2 facilitates reducing or eliminating the opportunity for a connection between the premix tube 302 and the tube tip 300 to impede or restrict the flow of the combustible mixture therethrough, and allows for repair or refurbishment of one or more premix tubes 302 with corresponding tube tips 300 while maintaining the performance, efficiency, and / or life of the combustor 20 ( FIG. 2 ).

[0053] FIG. 9 is an enlarged cross-sectional side view of another exemplary tube tip 400 secured or coupled to a remaining portion 402 of the premix tube 118. The remaining portion 402 of the premix tube 118 is also referred to as the premix tube 402. The tube tip 400 includes similar features and components as the tube tip 200, and the premix tube 402 includes similar features and components as the premix tube 202 described above with reference to FIG. 7. Corresponding reference characters are used in FIGS. 7 and 9 to indicate corresponding parts. In this embodiment, the inner surface 158 of the premix tube 402 is machined to include an angled surface 410 that extends between and joins the inner surface 158 and a second inner surface 434 adjacent the radially extending end face 408 at the open end 206. The second inner surface 434 is substantially flat. Similar to the angled surface 210 of the premix tube 202, the angled surface 410 extends beyond the increased inner diameter D at the open end 206. 2The angled surface 410 and the second inner surface 434 may be formed by machining the inner surface 158 of the premix tube 402 at the open end 206. Suitable techniques for machining the inner surface 158 to form the angled surface 410 and the second inner surface 434 include, for example, electrical discharge machining (EDM), milling, hand grinding, and / or any other suitable machining technique. The inner surface 158 may be machined to form the angled surface 410 and the second inner surface 434 during and / or after removing the damaged outlet portion 144 to form the exposed end 204.

[0054] The collar 224 of the tube tip 400 provides an angled surface 426 adjacent the radially extending collar surface 428 that joins the inner surface 222 to a second inner surface 436. The second inner surface 436 is substantially flat. Similar to the angled surface 226 of the tube tip 200, the angled surface 426 has an increased inner diameter D at the radially inner end of the collar surface 428. 2 to provide.

[0055] When the end 204 of the premix tube 402 is received in the socket 218 of the tube tip 400, the angled surfaces 410 and 426 and corresponding second inner surfaces 434 and 436 complement one another to form a substantially mirror image taper at the junction 432 of the end face 408 and the collar surface 428. In particular, at the junction 432, the inner diameter D of the fixedly joined premix tube 402 and tube tip 400 is 2 is the inner diameter D 1 Then, the inner diameter D 5 Alternatively, the angled surfaces 410 and 426 may reduce the increased inner diameter D of the fixedly joined premix tube 402 and tube tip 400 at the junction 432. 2As discussed above, the increased diameter at the joint 432 facilitates reducing or eliminating the opportunity for the connection between the premix tube 402 and the tube tip 400 to impede or restrict the flow of the combustible mixture therethrough, allowing for repair or refurbishment of one or more premix tubes 402 with corresponding tube tips 400 while maintaining the performance, efficiency, and / or life of the combustor 20 ( FIG. 2 ).

[0056] FIG. 10 is a cross section C of FIG. 9 shown by a dotted line. 1 10 illustrates in greater detail the interface 432 and corresponding features of the end face 408 of the premix tube 402 and the collar surface 428 of the tube tip 400. The angled surface 410 of the premix tube 402 is angled at an oblique angle α 3 2, and the angled surface 426 of the tube tip 400 is at an oblique angle α 4 The angle α 3 and α 4 are the inner diameters D at the inner surface 158, respectively. 1 and the inner diameter D at the inner surface 222 5 From the above, the inner diameter D at the joint 432 2 For example, the angle α 3 and α 4 can be between about 5° and about 60°, between about 5° and about 30°, between about 5° and about 20°, between about 5° and about 10°, between about 10° and about 30°, between about 10° and about 20°, between about 20° and about 60°, between about 20° and about 45°, between about 20° and about 30°, between about 30° and about 60°, between about 30° and about 45°, or between about 45° and about 60°. 5 is the inner diameter D of the tube channel 152 1 If the angle α of the angled surfaces 410 and 426 is approximately equal to 3 and α 4 is approximately the same for each of the inner surfaces 158 and 222.

[0057] As shown in FIG. 10, the end face 408 and collar surface 428 include corresponding centering features to facilitate centering of the end portion 204 of the premix tube 402 within the socket 218. The centering features described for the embodiment of FIGS. 9 and 10 may be included in any embodiment, such as the embodiment described with reference to FIGS. 7 and 8. The centering features of the premix tube 402 include a substantially flat step surface 438 formed on the end face 408 and extending radially from the surface 434, and a chamfer 440 joining the outer surface 160 and the step surface 438. The step surface 438 may be preferably formed during removal of the damaged end portion 144 from the premix tube 118. The chamfer 440 may be formed by machining the outer surface 160 of the premix tube 402 at the open end 206. Suitable techniques for machining the exterior surface 160 to form the chamfer 440 include, for example, electrical discharge machining (EDM), milling, hand grinding, and / or any other suitable machining technique. The exterior surface 160 may be machined to form the chamfer 440 during and / or after removing the damaged outlet portion 144 to form the exposed end 204.

[0058] The corresponding centering feature of the tube tip 400 includes a substantially planar step surface 442 formed in the collar surface 428 and extending radially from the surface 436, and a chamfer 444 joining the inner socket surface 230 and the step surface 442. The chamfers 440 and 444 preferably extend between the respective surfaces at approximately the same angle relative to the outer surface 160 and the inner socket surface 230. For example, the chamfers 440 can each extend at approximately the same angle within a range of between about 20° and about 75°, between about 20° and about 45°, between about 20° and about 30°, between about 30° and about 75°, between about 30° and about 60°, between about 30° and about 45°, between about 45° and about 75°, between about 45° and about 60°, or between about 60° and about 75°.

[0059] As described above, when the socket 218 receives the end 204, the inner diameter D of the socket 218 is 4 and the outer diameter D of the end 204 3 2, the end portion 204 may be configured such that the outer surface 160 of the end 204 is adjacent and / or abuts the inner socket surface 230. The centering features formed on the end face 408 and the collar surface 428 facilitate alignment of the end 204 within the socket 218 at the interface 432. In particular, when the socket 218 receives the end 204, the stepped surfaces 438 and 442 are adjacent and / or nearly abutting one another, and the chamfers 440 and 444 are adjacent and / or nearly abutting one another, facilitating radial and axial alignment of the end 204 within the socket 218. In this manner, the end portion 204 of the premix tube 402 may be centered within the socket 218, and the tube channel 152 and the tip tube channel 216 may be substantially axially aligned along the axial centerline 220.

[0060] FIG. 11 is an enlarged cross-sectional side view of another exemplary tube tip 500 secured or coupled to a remaining portion 502 of a premix tube 118. The remaining portion 502 of the premix tube 118 is also referred to as a premix tube 502. The tube tip 500 includes similar features and components as the tube tip 200, which includes similar features and components as the premix tube 202 described above with reference to FIG. 7. Corresponding reference characters are used in FIGS. 7 and 11 to indicate corresponding parts. In this embodiment, the open mating end 512 of the tube tip 500 does not include a socket 218. Instead, the mating end 512 defines a radially extending end face 528 that is complementary to and adjacent to the end face 208 of the premix tube 502. A coupling sleeve 506 circumferentially surrounds a junction 532 of the end faces 208 and 528. The coupling sleeve 506 may be fixedly coupled or secured to the premix tube 502 and / or tube tip 500 at the joint 532 by brazing, welding, adhesive cladding, or any suitable means and / or process for joining the two components.

[0061] As shown in FIG. 11, the end surface 528 of the mating end portion 512 is at an angle α 2 2. The angled surface 226 is joined to the inner surface 222 of the tube tip 500 by an angled surface 226 oriented at an end face 528 of the mating end 212, which has an increased inner diameter D 2 Angled surfaces 210 and 226 complement one another to form a substantially mirror image taper at junction 532 of end faces 208 and 528. In particular, at junction 532, the inside diameter D of fixedly joined premix tube 502 and tube tip 500 2 is the inner diameter D 1 Then, the inner diameter D 5Alternatively, the angled surfaces 210 and 226 provide for an increase in the inner diameter of the fixedly joined premix tubes 502 and tube tips 500 at the junction 532. As discussed above, the increased diameter at the junction 532 facilitates reducing or eliminating the opportunity for the connection between the premix tubes 502 and tube tips 500 to impede or restrict the flow of the combustible mixture therethrough, allowing for repair or refurbishment of one or more premix tubes 502 with corresponding tube tips 500 while maintaining the performance, efficiency, and / or life of the combustor 20 (FIG. 2).

[0062] The tube tips 156 that may be incorporated into the fuel injector 100 to repair and / or refurbish the premix tubes 118 may include any or each of the features of the exemplary embodiments illustrated and described herein as tube tips 200, 300, 400, and 500. In addition, the tube tips 156 may include a variety of other tube tip shapes or configurations, and the tube tips 156 should not be limited to the exemplary embodiments described herein. Furthermore, the exemplary features described herein for the tube tips 156 and the corresponding ends 204 of the premix tubes 118 (e.g., tube tips 200, 300, 400, and 500 and corresponding premix tubes 202, 302, 402, and 502) are applicable to any of the embodiments described herein, as well as various other shapes or configurations of the tube tips 156 and the corresponding ends 204 of the premix tubes 118 that are not illustrated. The illustrative embodiments are not intended to be limiting with respect to the shapes, geometries, or other configurations that may be suitably incorporated into the tube tips 156 and corresponding ends 204 to replace damaged exit sections 144 of the premix tubes 118 with the tube tips 156 and facilitate the advantages described herein.

[0063] FIG. 12 is an exemplary method 600 of repairing a fuel injector (e.g., fuel injector 100) including multiple premix tubes (e.g., premix tubes 118). Method 600 is described with further reference to the components illustrated in FIGS. 3-11. The premix tubes 118 extend substantially parallel to one another along or parallel to the axial centerline 106 of the fuel injector 100. Each premix tube 118 includes an inlet portion 140 extending through the fuel plenum 120, a middle portion 142 extending axially outward from the fuel plenum, and an outlet portion 144 extending axially outward from the middle portion 142 toward the combustion chamber 50 (FIG. 2). In operation of the fuel injector 100, the outlet portion 144 of the premix tube 118 is exposed to extreme temperatures and high mechanical loads due to its proximity to the combustion chamber 50 and / or combustion flame and may be damaged over time, for example, by thermal stresses and oxidation.

[0064] The method 600 includes removing 602 the outlet portion 144 from at least one premix tube 118 to define an exposed end 204. Removing 602 the outlet portion 144 may be performed using any suitable means for cutting or otherwise removing a tube. For example, removing 602 the outlet portion 144 may be performed using scoring, electrical discharge machining (EDM), torch cutting, a cutting blade, or the like. Additionally, removing 602 the outlet portion 144 may include removing 602 the entire outlet portion 144 of the premix tube 118 or removing only a portion of the outlet portion 144. For example, only a damaged area of ​​the outlet portion 144 may be removed 602. In some implementations of the method 600, the outlet portions 144 of each of the premix tubes 118 of the fuel injector 100 may be removed 602 in a single cutting operation in which the outlet portions 144 of the premix tubes 118 are removed along a cut line 166 ( FIG. 5 ) that extends generally perpendicular to the axial length of the premix tubes 118 and the axial centerline 106 of the fuel injector 100. In such implementations, after the removal 602, the exposed ends 204 defined in the premix tubes 118 are substantially coaxial and have end faces 208 that are substantially flush with one another. In other implementations, the outlet portions 144 of one or some of the premix tubes 118 are individually removed while the outlet portions 144 of other premix tubes 118 are not removed. In some implementations of the method 600, the removal 602 of the outlet portions 144 may be performed without removing a support plate or other fixture from the fuel injector 100.For example, the intermediate and outlet portions 142, 144 of the pre-mix tubes 118 may float or may extend freely outwardly from the fuel plenum 120 without any additional support plate or fixture provided downstream from the shroud 112, thus omitting a need to remove such a fixture prior to removing 602 the outlet portion 144.

[0065] The method 600 also includes measuring the inner surface 158 of the at least one premix tube 118 at the exposed end 204 to an inner diameter D of the premix tube 118 upstream from the exposed end 204. 1 Increased inner diameter D 2 The machining 604 may be performed using any suitable machining technique, such as, for example, electrical discharge machining (EDM), milling, hand grinding, etc. The machining 604 may include machining 604 an increased inner diameter D at the exposed end 204. 2 In some embodiments of the method 600, the machining 604 may produce any suitable shape of the end 204 that defines an increased inner diameter D at the exposed end 204. 27 and 11 , concave surface 310 shown in FIG. 8 , or angled surface 410 shown in FIG. 9 and 10 ) that defines an inner tapered surface. For example, exposed end 204 may include angled surface 210 ( FIG. 7 and 11 ) that extends obliquely between end face 208 and inner surface 158 and tapers inwardly toward inner surface 158. Exposed end 204 may alternatively include concave surface 310 ( FIG. 8 ) that extends between and joins end face 208 and inner surface 158. Exposed end 204 may alternatively include angled surface 410 ( FIG. 9 and 10 ) that extends obliquely between inner surface 158 and a second inner surface 434 adjacent end face 408. A support plate may be temporarily attached over the at least one premix tube 118 and the at least one other premix tube 118 during machining 604. For example, in embodiments of the method 600 in which the intermediate and outlet sections 142, 144 of the premix tubes 118 are free floating or extending outwardly from the fuel plenum 120 without additional support plates or fasteners provided downstream from the shroud 112, a support plate may be temporarily attached over the premix tube 118 being machined 604 along with the at least one other premix tube 118 (e.g., at least one adjacent premix tube 118) to facilitate limiting movement of the at least one premix tube 118 during machining 604.

[0066] The method 600 also includes securely coupling 606 the tube tip 156 to the exposed end 204. The coupling 606 between the tube tip 156 and the exposed end 204 may be performed by inserting the exposed end 204 into a socket 218 in the tube tip 156 and coupling the exterior surface 160 of the exposed end 204 to the interior surface 230 of the socket 218. The coupling between the tube tip 156 and the exposed end 204 may alternatively be performed by surrounding the junction between the tube tip 156 and the exposed end 204 with a coupling sleeve 506 and fixedly coupling or fastening the coupling sleeve 506 to the tube tip 156 and / or the exposed end 204. The tube tip 156 may be securely coupled 606 to the exposed end 204 using any suitable means for coupling tubes. For example, the tube tip 156 may be bonded 606 to the exposed end 204 by furnace brazing, induction brazing, orbital welding, laser welding, friction welding, electron beam welding, diffusion bonding, plasma spraying, heat resistant adhesives, adhesive cladding, high velocity oxy-fuel coating spraying, etc. In some embodiments, bonding 606 may include melting a filler material (e.g., a braze filler material or a weld filler material) to securely bond the tube tip 156 to the exposed end 204. The melted filler material forms an increased inner diameter D 2 2 , which facilitates reducing or eliminating the risk that the accumulated material will obstruct or restrict the flow of the combustible mixture therethrough while maintaining the performance, efficiency, and / or life of the combustor 20 ( FIG. 2 ).

[0067] After bonding 606 the tube tips 156 to the exposed ends 204, the premix tubes 118, including the tube tips 156, preferably extend the same axial length as they did before removing 602 the damaged outlet portions 144. In embodiments of the method 600 in which the premix tubes 118 are coaxial with one another and their outlet portions 144 are removed 602 in a single cutting operation along the cut line 166, the tube tips 156 bonded to the exposed ends 204 preferably retain a coaxial extent such that the tube tips 156 define one or more end faces at the outlet ends 214 that are substantially flush with one another. In embodiments 602 of the method 600 in which one or more outlet portions 144 of the premix tubes 118 are individually removed, the tube tips 156 replacing the removed outlet portions 144 may be flush with the remaining outlet portions 144 and define an end face at the outlet ends 214 that is substantially flush with the remaining end faces 164.

[0068] The bond 606 of the tube tip 156 to the exposed end 204 forms a junction between the tube tip 156 and the exposed end 204 (e.g., junction 232 in FIG. 7, junction 332 in FIG. 8, junction 432 in FIGS. 9 and 10, or junction 532 in FIG. 11). At the junction, the tube tip 156 has a larger inside diameter D than downstream from the junction. 2 That is, the tube tip 156 has an inner diameter D 5 and an inner diameter D of the tube tip 156 at the junction. 2 is the inner diameter D 5 In an exemplary method, the tube tip 156 and exposed end 204 have approximately equal inner diameters D 2In some embodiments of the method 600, the tube tip 156 has an interior surface configuration at the junction that complements the interior surface configuration of the exposed end 204. The tube tip may have an inwardly tapered surface (e.g., angled surface 226 shown in Figures 7 and 11, concave surface 326 shown in Figure 8, or angled surface 426 shown in Figures 9 and 10) that extends between the junction and the interior surface 222 of the tube tip 156 to define a larger inner diameter of the tube tip 156 at the junction and that complements the inwardly tapered machined surface of the exposed end 204 created by machining 604. For example, the tube tip 156 may include an angled surface 226 (Figures 7 and 11) that extends diagonally between the interior surface 222 and a radially extending surface (e.g., collar surface 228 in Figure 7 or end surface 528 in Figure 11) and tapers inwardly toward the interior surface 222. The tube tip 156 may alternatively include a concave surface 326 (FIG. 8) extending between the inner surface 222 and a radially extending surface (e.g., collar surface 228 in FIG. 8 or end face 528 in FIG. 11). The tube tip 156 may alternatively include an angled surface 426 (FIGS. 9 and 10) extending obliquely between the inner surface 222 and a second inner surface 436 adjacent the radially extending surface 442. In some implementations, the inner surface configurations of the tube tip 156 and exposed end 204 form mirror images and each have an inner diameter D within the tube channel 152 that may be approximately the same. 1 and the inner diameter D within the tube tip channel 216 5 Therefore, the inner diameter D at the joint is almost the same. 2 Increase the inner diameter until

[0069] In some embodiments of the method 600, the exposed end 204 and the tube tip 156 may include corresponding centering features to facilitate radially and / or axially aligning the exposed end 204 and the tube tip 156. The centering features may be formed in the exposed end 204 during machining 604. For example, in an embodiment of the method 600 in which the exposed end 204 is inserted into the socket 218 of the tube tip 156 during coupling 606, the machining 604 may include machining 604 a chamfer 440 ( FIG. 10 ) that extends between and couples with the outer surface 160 and the radially extending step surface 438 of the exposed end 204. The corresponding centering feature of the tube tip 156 may include a chamfer 444 that extends between and couples with the inner socket surface 230 and the step surface 442. When socket 218 receives end 204 during coupling 606, stepped surfaces 438 and 442 abut and / or abut one another and chamfers 440 and 444 abut and / or abut one another to facilitate radial and axial alignment of end 204 within socket 218.

[0070] An exemplary method described herein includes machining the exposed end of the premix tube after removing the damaged exit portion to produce a suitable configuration of the premix tube that facilitates reducing or eliminating the possibility or risk that the connection between the premix tube and the tube tip may impede or restrict the flow of the combustible mixture therethrough. For example, the premix tube may be machined to have an increased diameter at the exposed end where the tube tip is attached that provides additional interior space for material to accumulate without becoming an obstacle to the combustible mixture flowing through the premix tube and the tube tip. The increased diameter also facilitates reducing or eliminating the adverse effect that an axial alignment offset between the premix tube and the tube tip may have on the flow of the combustible mixture therethrough. In this manner, one or more premix tubes may be repaired or refurbished with the corresponding tube tip while maintaining the performance, efficiency, and / or life of the combustor.

[0071] Further aspects of the present disclosure are provided by the subject matter of the following clauses. [Embodiment 1] A method of repairing a fuel injector including a plurality of pre-mix tubes that each extend from a fuel plenum to an outlet portion, comprising: removing the outlet portion from at least one pre-mix tube to define an exposed end portion; machining an inner surface of the at least one pre-mix tube at the exposed end portion to form an increased inner diameter relative to an inner diameter of the pre-mix tube upstream from the exposed end portion; and coupling a tube tip to the exposed end portion. [Embodiment 2] 2. The method of claim 1, wherein coupling the tube tip to the exposed end portion creates a junction between the tube tip and the exposed end portion, and the tube tip has a greater inner diameter at the junction than downstream from the junction. [Embodiment 3] 3. The method of claim 2, wherein the increased inner diameter at the exposed end portion is approximately equal to the inner diameter of the tube tip at the junction. [Embodiment 4] The method of any preceding embodiment, wherein coupling the tube tip to the exposed end portion comprises melting a filler material to securely couple the tube tip to the exposed end portion, and the melted filler material accumulates along the inner surface of the junction at the increased inner diameter. [Embodiment 5] The method of claim 4, wherein coupling the tube tip to the exposed end portion comprises one of brazing and welding the tube tip to the exposed end portion using the filler material. [Embodiment 6] 13. The method of any preceding embodiment, wherein machining the inner surface to the increased inner diameter comprises at least one of electrical discharge machining and milling. [Embodiment 7] The method of any preceding embodiment, wherein coupling the tube tip to the exposed end portion comprises inserting the exposed end portion into a socket of the tube tip and coupling an outer surface of the exposed end portion to an inner surface of the socket. [Embodiment 8] 11. The method of any preceding embodiment, wherein coupling the tube tip to the exposed end portion creates a junction between the tube tip and the exposed end portion, the method further comprising surrounding the junction with a coupling sleeve and fixedly securing the coupling sleeve to at least one of the tube tip and the exposed end portion to thereby securely couple the tube tip to the exposed end portion. [Embodiment 9] The method of any preceding embodiment, further comprising the step of temporarily installing a support plate onto the at least one pre-mix tube and at least one other pre-mix tube to facilitate limiting movement of the at least one pre-mix tube during the machining. [Embodiment 10] A method of repairing a fuel injector having a plurality of pre-mix tubes that each extend downstream from a fuel plenum to an outlet portion, comprising: removing the outlet portion from a pre-mix tube to define an exposed end portion; machining an inner surface of the pre-mix tube at the exposed end portion to produce an inwardly-tapering machined surface that has a greater inner diameter at the exposed end portion than an inner diameter upstream from the exposed end portion; and coupling a tube tip to the exposed end portion to create a junction between the tube tip and the exposed end portion, wherein the tube tip has an inwardly-tapering surface that extends between the junction and an inner surface of the tube tip, and the inwardly-tapering surface of the tube tip complements the inwardly-tapering machined surface to define a larger inner diameter at the junction. [Embodiment 11] 11. The method of claim 10, wherein the inwardly-tapering machined surface includes a first angled surface that is oriented at a first oblique angle relative to the inner surface of the pre-mix tube and the inwardly-tapering surface of the tube tip includes a second angled surface that is oriented at a second oblique angle relative to the inner surface of the tube tip. [Embodiment 12] 12. The method of claim 11, wherein the inner surface of the pre-mix tube and the inner surface of the tube tip define approximately the same diameter, and the inner diameter at the exposed end portion defined by inwardly-tapering machined surface is approximately the same as the inner diameter of the tube tip at the junction defined by the inwardly-tapering surface. [Embodiment 13] 11. The method of claim 10, wherein the inwardly-tapering machined surface includes a first concave surface, and the inwardly-tapering surface of the tube tip includes a second concave surface, the first and second concave surfaces complement each other and create a substantially semi-circular shape at the junction. [Embodiment 14] 15. The method of any one of claims 10 to 14, further comprising the step of machining the exposed end portion to produce a centering feature that complements a corresponding centering feature formed in the tube tip and facilitates aligning the exposed end portion and the tube tip at the junction. [Embodiment 15] 15. The method of claim 14, wherein coupling the tube tip to the exposed end portion comprises inserting the exposed end portion into a socket of the tube tip, and the centering feature machined into the exposed end portion includes a first chamfer that abuts a second chamfer formed in the socket of the tube tip at the junction and facilitates aligning the exposed end portion within the socket. [Embodiment 16] A method of repairing a fuel injector including a plurality of pre-mix tubes that each extend from a fuel plenum to an outlet portion, comprising: removing the outlet portions from the plurality of pre-mix tubes along a cut line to define exposed end portions of the plurality of pre-mix tubes; machining an inner surface of each pre-mix tube at the exposed end portion to form an increased inner diameter relative to an inner diameter of the pre-mix tube upstream from the exposed end portion; and coupling a tube tip to each exposed end portion. [Embodiment 17] 17. The method of claim 16, wherein removing the outlet portions from the plurality of pre-mix tubes defines the exposed end portions that are coextensive and have end surfaces that are substantially flush with one another. [Embodiment 18] 18. The method of claim 17, wherein the tube tips coupled to the exposed end portions are coextensive and have end surfaces that are substantially flush with one another. [Embodiment 19] 19. The method of any one of embodiments 16 to 18, wherein the plurality of pre-mix tubes freely extend from the fuel plenum such that removing the outlet portions from the plurality of pre-mix tubes is performed without removing a support plate from the fuel injector. [Embodiment 20] 20. The method of any one of claims 16 to 19, wherein removing the outlet portions from the plurality of pre-mix tubes is performed using a single cutting operation.

[0072] The methods and systems described herein are not limited to the specific embodiments described herein. For example, each system component and / or each method step may be utilized independently and separately from other components and / or steps described herein. For example, the methods and systems may be used in combination with other turbine systems and are not limited to practice solely with the gas turbine engines described herein. Rather, the exemplary embodiments may be implemented and utilized in connection with many other turbine applications.

[0073] Although specific features of various embodiments of the present disclosure may be shown in some drawings and not in others, this is for convenience only, and in accordance with the principles of the present disclosure, any feature of a drawing may be referenced and / or claimed in combination with any feature of any other drawing.

[0074] This specification 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 the 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 have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that do not differ insubstantially from the literal language of the claims. [Explanation of symbols]

[0075] 10: gas turbine engine 12: compressor section 14: inlet 15: upstream end 16: casing 17: outer casing 18: combustion section 20: combustor 22: turbine section 24: rotor shaft 26: working fluid 28: compressed working fluid 29: fuel 30: hot gas 32: first stage 33: second stage 34: turbine nozzle 36: turbine blades 38: outer casing 40: high pressure plenum 42: end cover 44: fuel supply 46: fluid conduit 48: annular liner 50: combustion chamber 52: hot gas path 100: bundle tube fuel injector 102: downstream end 104: upstream end 106: axial centerline 108: fuel inlet 110: fuel distribution module 112: shroud 114: support plate 116: inlet tube 117: open inlet end 118, 202: premix tube 120: fuel plenum 122: first plate 124: second plate 126: outer band 128, 130, 134: tube passage 132: central nozzle passage 136: central fuel inlet passage 138: fluid cartridge / fuel nozzle 140: first section / inlet section 142: second section / middle section 144: third section / outlet section / damaged end section 146: row 148: inlet 150: outlet 152: tube channel 154: fuel port 156, 200, 300, 400, 500: tube tip 158: inner surface 160: outer surface 162, 164: end face 166: cut line 204: exposed end 206: open end 208: radially extending repair end / end face 210, 226, 410, 426: angled / tapered surface 212: mating end 214: opposite exit end 216: tube tip channel 218: socket 220: shaft centerline 222: inner surface 224: collar 228, 428: collar surface 230: inner socket surface 232: interface 302, 402, 502: remaining portion 310, 326: concave surface 332, 432, 532: interface 408, 528: end face 434, 436: second inner surface 438, 442: stepped surface 440, 444: chamfer 506: coupling sleeve 512: open mating end α1-α4: angle C1; cross section CL: shaft centerline D1, D2, D4, D5: inner diameter D3: diameter

Claims

1. A method of repairing a fuel injector (100) including a plurality of premix tubes (118) each extending from a fuel plenum (120) to an outlet portion (144), comprising the steps of: removing an outlet portion (144) from at least one premix tube (118) to define an exposed end (204); The inner surface (158) of the at least one premix tube (118) at the exposed end (204) is machined to reduce the inner diameter (D １ ) with respect to the increased inner diameter (D ２ ) forming a and coupling the tube tip (156) to the exposed end (204).

2. The tube tip (156) is joined to the exposed end (204) to form a junction (232) between the tube tip and the exposed end, and the tube tip has a larger inside diameter (D) at the junction than downstream from the junction. ２ 2. The method of claim 1 , comprising:

3. The increased inner diameter (D ２ ) is the inner diameter (D ２ 3. The method of claim 2, wherein the .lambda.

4. The step of bonding the tube tip (156) to the exposed end (204) includes melting a filler material to securely bond the tube tip to the exposed end, the molten filler material forming an increased inner diameter (D ２ 4. The method of claim 1, wherein the filler material accumulates along an inner surface (210, 226) of the joint (232) at a distance of 100 mm from the inner surface (210, 226) of the joint (232), and preferably the step of joining the tube tips to the exposed ends includes the step of brazing or welding the tube tips to the exposed ends using a filler material.

5. The inner surface (158) has an increased inner diameter (D ２ 2. The method of claim 1, wherein machining the first metal layer comprises at least one of electro-discharge machining and milling.

6. 2. The method of claim 1, wherein coupling the tube tip (156) to the exposed end (204) comprises inserting the exposed end into a socket (218) in the tube tip and coupling an outer surface (160) of the exposed end to an inner surface (230) of the socket.

7. 2. The method of claim 1, wherein a tube tip (156) is coupled to an exposed end (204) to form a joint (232) between the tube tip and the exposed end, the method including the step of securely coupling the tube tip to the exposed end by surrounding the joint with a coupling sleeve (506) and securing the coupling sleeve to at least one of the tube tip and the exposed end.

8. 10. The method of claim 1, further comprising temporarily attaching a support plate over the at least one premix tube (118) and the at least one other premix tube (118) to facilitate limiting movement of the at least one premix tube during processing.

9. The inner surface (158) of the premix tube (118) is machined at the exposed end (204) to provide an increased inner diameter (D ２ ) creating an inwardly tapered machined surface (210) having a and bonding the tube tip (156) to the exposed end (204) to form a joint (232) between the tube tip and the exposed end; The tube tip has an inwardly tapered surface (226) extending between the junction and the inner surface (222) of the tube tip, the inwardly tapered surface of the tube tip having an increased inner diameter (D ２ 2. The method of claim 1 , further comprising: a step of: providing a step of forming a first end of the groove in the first groove;

10. The inwardly tapered surface is at a first oblique angle (α ) relative to the inner surface (158) of the premix tube (118). １ ), and the inwardly tapered surface (226) of the tube tip (156) is oriented at a second oblique angle (α ２ 10. The method of claim 9, further comprising a second angled surface (222) oriented in a .

11. 10. The method of claim 9, wherein the inwardly tapered surface includes a first concave surface (310) and the inwardly tapered surface of the tube tip includes a second concave surface (326), the first and second concave surfaces complementing each other and forming a substantially semicircular shape at the junction (332).

12. 10. The method of claim 9, further comprising machining the exposed ends (204) to create centering features (438, 440) that complement corresponding centering features (442, 440) formed in the tube tips (156) and facilitate alignment of the exposed ends and the tube tips at the joint.

13. 13. The method of claim 12, wherein coupling the tube tip (156) to the exposed end (204) includes inserting the exposed end into a tube tip socket (218), and the centering features machined into the exposed end include a first chamfer (440) that generally abuts a second chamfer (444) formed in the tube tip socket at the junction (232) to facilitate aligning the exposed end within the socket.

14. removing an outlet portion (144) from each of the plurality of premix tubes (118) along cut lines (166) to define exposed ends (204) of the plurality of premix tubes; The increased inner diameter (D ２ machining an interior surface (158) of each premix tube at an exposed end to form a and b. coupling a tube tip (156) to each exposed end.

15. 15. The method of claim 14, wherein the plurality of premix tubes (118) extend freely from the fuel plenum (120) such that removal of the outlet portions (144) from the plurality of premix tubes is accomplished without removing the support plate from the fuel injector, and preferably, removal of the outlet portions (144) from the plurality of premix tubes is accomplished using a single cutting operation.

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