Patent Publication Number: US-9423136-B2

Title: Bundled tube fuel injector aft plate retention

Description:
FIELD OF THE INVENTION 
     The present invention generally involves a bundled tube fuel injector such as may be incorporated into a combustor of a gas turbine or other turbomachine. Specifically, the invention relates to the retention of an aft plate of the bundled tube fuel injector. 
     BACKGROUND OF THE INVENTION 
     Gas turbines are widely used in industrial and power generation operations. A typical gas turbine may include a compressor section, a combustion section disposed downstream from the compressor section, and a turbine section disposed downstream from the combustion section. A working fluid such as ambient air flows into the compressor section where it is progressively compressed before flowing into the combustion section. The compressed working fluid is mixed with a fuel and burned within one or more combustors of the combustion section to generate combustion gases having a high temperature, pressure, and velocity. The combustion gases flow from the combustors and expand through the turbine section to produce thrust and/or to rotate a shaft, thus producing work. 
     In a particular combustor design, the combustor includes one or more bundled tube fuel injectors that extend axially downstream from an end cover. The bundled tube fuel injector generally includes a fuel distribution module and a tube bundle having a plurality of pre-mix tubes that are in fluid communication with the fuel distribution manifold. The pre-mix tubes are arranged radially and circumferentially across the bundled tube fuel injector. The pre-mix tubes extend generally parallel to one another downstream from the fuel distribution manifold. 
     An outer shroud extends circumferentially around the pre-mix tubes downstream from the fuel distribution manifold. A support plate is disposed substantially adjacent to the fuel distribution manifold and the plurality of pre-mix tubes extends axially through the support plate towards an aft end of the bundled tube fuel injector. An aft plate or effusion plate extends radially and circumferentially across a downstream end of the outer shroud. A downstream or end portion of each pre-mix tube extends through the aft plate such that an outlet of each tube is downstream from a hot side surface of the aft plate, thus providing for fluid communication into the combustion chamber or zone. 
     In conventional bundled tube fuel injectors, the aft plate is connected to the bundled tube fuel injector by welding an outer perimeter of the aft plate to the downstream end of the outer shroud. In addition, a collar portion of the aft plate is welded or brazed to a cooling air flow sleeve that extends axially downstream from the support plate. The collar and the cooling air flow sleeve at least partially define a cartridge passage for inserting a fuel and/or air cartridge through the bundled tube fuel injector. 
     Although the weld joint formed at the collar and air flow sleeve joint is generally effective for retaining the aft plate to the bundled tube fuel injector, the weld joint is costly to manufacture due to various weld-prep operations required and may be generally difficult to weld due to a limited working area. In addition, removal of the aft plate for inspection, repair and/or replacement is time consuming and costly due to grinding, blending and/or other repair operations required to break the weld joint and prepare the parts for reassembly. Therefore, an improved bundled tube fuel injector would be useful. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Aspects and advantages of the invention are set forth below in the following description, or may be obvious from the description, or may be learned through practice of the invention. 
     One embodiment of the present invention is a bundled tube fuel injector. The bundled tube fuel injector includes a fuel distribution module, a tube bundle having a plurality of pre-mix tubes that extend in parallel downstream from the fuel distribution module and a support plate disposed substantially adjacent to the fuel distribution module. The plurality of pre-mix tubes extends through the support plate. A retention sleeve is coupled to the support plate at a first end. A second end of the retention sleeve includes a plurality of radially extending retention features that are circumferentially arranged around the second end. The bundled tube fuel injector also includes an aft plate having a retention collar. The retention collar is configured to engage with the retention features. The retention sleeve and the retention collar partially define a cartridge passage that extends through the bundled tube fuel injector. 
     Another embodiment of the present disclosure is a bundled tube fuel injector. The bundled tube fuel injector includes a fuel distribution module, a fluid conduit that is in fluid communication with the fuel distribution module and a tube bundle having a plurality of pre-mix tubes that extend in parallel downstream from the fuel distribution module. The fluid conduit partially defines a cartridge passage through the fuel distribution module. The bundled tube fuel injector further includes a retention sleeve that is aligned with the inner sleeve and circumferentially surrounded by the pre-mix tubes. The retention sleeve includes a first end that is proximate to the fuel distribution module and a second end that is distal from the fuel distribution module. The second end includes a plurality of radially extending retention features. An aft plate having a retention collar is aligned with the retention sleeve and is configured to engage with the retention features. 
     Another embodiment of the present disclosure includes a gas turbine. The gas turbine includes a compressor, a combustor disposed downstream from the compressor and a turbine that is disposed downstream from the combustor. The combustor includes an end cover that is coupled to an outer casing and a bundled tube fuel injector that extends downstream from the end cover. The bundled tube fuel injector includes a fuel distribution module, a fluid conduit that is in fluid communication with the end cover and the fuel distribution module and a tube bundle having a plurality of pre-mix tubes that extend in parallel downstream from the fuel distribution module. The fluid conduit comprises an inner sleeve that at least partially defines a cartridge passage through the fuel distribution module. A retention sleeve is aligned with the inner sleeve and includes a first end that is proximate to the fuel distribution module. A second end of the retention sleeve is distal from the fuel distribution module. The second end includes a plurality of radially extending retention features. An aft plate extends radially and circumferentially across an end portion of the bundled tube fuel injector. The aft plate includes a retention collar that is aligned with the retention sleeve and configured to engage with the retention features. 
     Those of ordinary skill in the art will better appreciate the features and aspects of such embodiments, and others, upon review of the specification. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present invention, including the best mode thereof to one skilled in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which: 
         FIG. 1  is a functional block diagram of an exemplary gas turbine that may incorporate various embodiments of the present invention; 
         FIG. 2  is a simplified cross-section side view of an exemplary combustor as may incorporate various embodiments of the present invention; 
         FIG. 3  is a cross section perspective view of an exemplary bundled tube fuel injector as may incorporate at least one embodiment of the present invention; 
         FIG. 4  is an enlarged cross sectional perspective view of a portion of the fuel injector as shown in  FIG. 3 , according to various embodiments of the present disclosure; 
         FIG. 5  is an enlarge cross section side view of an exemplary retention sleeve as shown in  FIG. 4 , according to one embodiment of the present invention; 
         FIG. 6  is a partially exploded cross section view of a portion of the fuel injector including the aft plate, according to one embodiment of the present invention; 
         FIG. 7  is an enlarged cross sectional view of the fuel injector including an exemplary retention sleeve and an exemplary aft plate, according to one embodiment of the present invention; 
         FIG. 8  is an enlarged cross sectional view of the fuel injector including an exemplary retention sleeve and an exemplary aft plate, according to one embodiment of the present invention 
         FIG. 9  is an enlarged cross sectional view of the fuel injector as shown in  FIG. 7  including an exemplary cartridge, according to one embodiment of the present invention; 
         FIG. 10  is an enlarged cross sectional view of the fuel injector as shown in  FIG. 9 , according to one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention. As used herein, the terms “first”, “second”, and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terms “upstream” and “downstream” refer to the relative direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows. The term “radially” refers to the relative direction that is substantially perpendicular to an axial centerline of a particular component, and the term “axially” refers to the relative direction that is substantially parallel to an axial centerline of a particular component. 
     Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope or spirit thereof. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
     Although exemplary embodiments of the present invention will be described generally in the context of a bundled tube fuel injector incorporated into a combustor of a gas turbine for purposes of illustration, one of ordinary skill in the art will readily appreciate that embodiments of the present invention may be applied to any combustor incorporated into any turbomachine and are not limited to a gas turbine combustor unless specifically recited in the claims. 
     Referring now to the drawings, wherein identical numerals indicate the same elements throughout the figures,  FIG. 1  provides a functional block diagram of an exemplary gas turbine  10  that may incorporate various embodiments of the present invention. As shown, the gas turbine  10  generally includes an inlet section  12  that may include a series of filters, cooling coils, moisture separators, and/or other devices to purify and otherwise condition a working fluid (e.g., air)  14  entering the gas turbine  10 . The working fluid  14  flows to a compressor section where a compressor  16  progressively imparts kinetic energy to the working fluid  14  to produce a compressed working fluid  18 . 
     The compressed working fluid  18  is mixed with a fuel  20  from a fuel source  22  such as a fuel skid to form a combustible mixture within one or more combustors  24 . The combustible mixture is burned to produce combustion gases  26  having a high temperature, pressure and velocity. The combustion gases  26  flow through a turbine  28  of a turbine section to produce work. For example, the turbine  28  may be connected to a shaft  30  so that rotation of the turbine  28  drives the compressor  16  to produce the compressed working fluid  18 . Alternately or in addition, the shaft  30  may connect the turbine  28  to a generator  32  for producing electricity. Exhaust gases  34  from the turbine  28  flow through an exhaust section  36  that connects the turbine  28  to an exhaust stack  38  downstream from the turbine  28 . The exhaust section  36  may include, for example, a heat recovery steam generator (not shown) for cleaning and extracting additional heat from the exhaust gases  34  prior to release to the environment. 
       FIG. 2  provides a simplified cross section of an exemplary combustor  24  as may incorporate a bundled tube fuel injector  40  configured according to at least one embodiment of the present disclosure. As shown, the combustor  24  is at least partially surrounded by an outer casing  42 . The outer casing  42  at least partially forms a high pressure plenum  44  around the combustor  24 . The high pressure plenum  44  may be in fluid communication with the compressor  16  or other source for supplying the compressed working fluid  18  to the combustor  24 . In one configuration, an end cover  48  is coupled to the outer casing  42 . The end cover  48  may be in fluid communication with the fuel supply  22 . 
     As shown in  FIG. 2 , the bundled tube fuel injector  40  extends downstream from the end cover  48 . The bundled tube fuel injector  40  may be fluidly connected to the end cover  48  so as to receive fuel from the fuel supply  22 . For example, a fluid conduit  52  may provide for fluid communication between the end cover  48  and/or the fuel supply  22  and the bundled tube fuel injector  40 . One end of an annular liner  54  such as a combustion liner and/or a transition duct surrounds a downstream end  56  of the bundled tube fuel injector  40  so as to at least partially define a combustion chamber  58  within the combustor  24 . The liner  54  at least partially defines a hot gas path  60  for directing the combustion gases  26  from the combustion chamber  58  through the combustor  24 . For example, the hot gas path  60  may be configured to route the combustion gases  26  towards the turbine  28  and/or the exhaust section. 
     In operation, the compressed working fluid  18  is routed towards the end cover  48  where it reverses direction and flows through one or more of the bundled tube fuel injectors  40 . The fuel  20  is provided to the bundled tube fuel injector  40  and the fuel  20  and the compressed working fluid  18  are premixed or combined within the bundled tube fuel injector  40  before being injected into a combustion chamber  58  for combustion. 
       FIG. 3  is a perspective view of an exemplary bundled tube fuel injector  100  herein referred to as “fuel injector” as may be incorporated into the combustor  24  as described in  FIG. 2 , according to various embodiments of the present disclosure.  FIG. 4  is an enlarged cross sectional perspective view of a portion of the fuel injector  100  as shown in  FIG. 3 , according to various embodiments of the present disclosure. In one embodiment, as shown in  FIGS. 3 and 4 , the fuel injector  100  includes a fuel distribution module  102 , a tube bundle  104  including a plurality of pre-mix tubes  106  arranged radially and circumferentially across the fuel injector  100  and an outer shroud  108  that extends circumferentially around the tube bundle  104  axially away from the fuel distribution module  102 . 
     In various embodiments, as shown in  FIG. 3 , an aft or effusion plate  110  extends radially and circumferentially across a downstream or end portion  112  of the fuel injector  100 . The aft plate  110  may include a plurality of cooling holes  114  to allow cooling or purge air to pass therethrough, thereby providing at least one of film, convective or conductive cooling to the aft plate  110 . A plurality of pre-mix tube passages  116  are defined by the aft plate  110 . A downstream or end portion of each pre-mix tube  106  extends axially through the aft plate  110 , thereby providing for fluid communication between the pre-mix tubes  106  and the combustion chamber  58 . 
     In one embodiment, as shown in  FIG. 4 , the fuel distribution module  102  is at least partially defined by a first plate  118  and a second plate  120 . The first and second plates  118 ,  120  extend radially and circumferentially across the fuel injector  100  with respect to an axial centerline  122  of the fuel injector  100 . The second plate  120  is axially separated from the first plate  118  with respect to the axial centerline  122  of the fuel injector  100 , In one embodiment, an outer band  124  extends circumferentially around and between the first and second plates  118 ,  120 . The fuel distribution module  102  further includes a fuel plenum  126 . In one embodiment, the fuel plenum  126  is at least partially defined by the first plate  118 , the second plate  120  and the outer band  124 . 
     In particular embodiments, the fluid conduit  52  provides for fluid communication between the fuel supply  22  ( FIG. 2 ) and the fuel distribution module  102 . For example, in one embodiment, the fluid conduit  52  provides for fluid communication between the fuel supply  22  and the fuel plenum  126 . In one embodiment, as shown in  FIG. 4 , the fluid conduit  52  comprises an outer sleeve  128  that is radially separated from an inner sleeve  130  and a fuel passage  132  that is defined therebetween. The fuel passage  132  provides for fluid communication between the fuel supply  22  and the fuel plenum  126 . In one embodiment, the inner sleeve  130  at least partially defines a cartridge passage  134  that extends axially through the fuel distribution module  102  with respect to the axial centerline  122 . 
     As shown in  FIG. 4 , the pre-mix tubes  106  extend generally parallel to one another coaxially with or parallel to the axial centerline  122  of the fuel injector  100 . The pre-mix tubes  106  extend downstream from the fuel plenum  126  towards the aft plate  110  ( FIG. 3 ). The pre-mix tubes  106  may be formed from a single continuous tube or may be formed from two or more coaxially aligned tubes fixedly joined together. Although generally illustrated as cylindrical, the pre-mix tubes  106  may be any geometric shape, and the present invention is not limited to any particular cross-section unless specifically recited in the claims. In addition, the pre-mix tubes  106  may be grouped or arranged in circular, triangular, square, or other geometric shapes, and may be arranged in various numbers and geometries. 
     An exemplary pre-mix tube  106 , as shown in  FIG. 4 , generally includes an inlet  136  defined upstream from the fuel plenum  126  and/or the first plate  118 . The inlet  136  may be in fluid communication with the high pressure plenum  44  ( FIG. 2 ) and/or the compressor  16  ( FIG. 1 ). A downstream or end portion  138  is defined downstream from the fuel plenum  126 . One or more fuel ports  140  may provide for fluid communication between the fuel plenum  126  and a corresponding pre-mix tube  106 . 
     In operation, the compressed working fluid  18  is routed through the inlet  136  of each pre-mix tube  106  upstream from the fuel distribution module  102 . Fuel is supplied to the fuel plenum  126  through the fluid conduit  52  and the fuel is injected into the pre-mix tubes  106  through the fuel ports  140 . The fuel and compressed working fluid  18  mix inside the pre-mix tubes  106  before flowing out of the end portion  138  and into the combustion chamber or zone  58  for combustion. 
     In particular embodiments, the fuel injector  100  includes a support plate  142 . In one embodiment, the support plate  142  extends radially and circumferentially across the fuel injector  100  with respect to the axial centerline  122 . The support plate  142  is disposed substantially parallel and/or substantially adjacent to the fuel distribution module  102 . The pre-mix tubes  106  extend axially through the support plate  142 . The support plate  142  may provide radial support for the pre-mix tubes  106  and/or may align the pre-mix tubes with the aft plate  110 . In one embodiment, the outer shroud  108 , the aft plate  110  and the support plate  142  define a cooling or purge air plenum  144  that surrounds a portion of the tube bundle  104 . 
     In particular embodiments, the fuel injector  100  includes a retention sleeve  146 .  FIG. 5  provides an enlarge cross section side view of an exemplary retention sleeve  146  as shown in  FIG. 4 , according to one embodiment of the present invention. In one embodiment, the retention sleeve  146  is coupled to the support plate  142  at a first end  148 . The first end is disposed generally proximate to the fuel distribution module  102 , particularly the second plate  120 . In one embodiment, the first end  148  may be coupled directly to the support plate  142 . In one embodiment, the retention sleeve  146  is coupled to the support plate  142  via an air sleeve  150 . The air sleeve  150  may be coaxially aligned with the retention sleeve  146 , In one embodiment, the retention sleeve  146  and/or the air sleeve  150  at least partially define the cartridge passage  134 . For example, as shown in  FIG. 4 , the air sleeve  150  and the retention sleeve  146  may be substantially coaxially aligned with the fluid conduit  52 . In an alternate embodiment, the air sleeve  150  and/or the retention sleeve  146  may be coupled to the fuel distribution module  102 . 
     In one embodiment, as shown in  FIGS. 4 and 5 , the retention sleeve  146  comprises a second end  152  having a profile which defines a plurality of retention features  154 . The retention features  154  are circumferentially arranged around the second end  152  and extend generally radially outwardly. In one embodiment, the retention features  154  are at least partially defined by the retention sleeve  146 . In one embodiment, a portion of each retention feature  154  extends radially outwardly with respect to an outer surface  156  of the retention sleeve. In one embodiment, a portion of each retention feature  154  extends radially inwardly with respect to an inner surface  158  of the retention sleeve. 
     In one embodiment, the retention sleeve  146  is slotted  160  from the second end  152  towards the first end  148  in the axial direction to allow for radial movement of the retention features  154  with respect to centerline  122 . In particular embodiments, the slots  160  define spring arms or members  162  of the retention sleeve  146 . In one embodiment, the retention sleeve  146  is tapered radially outwardly along the axial centerline  122  from the first end  148  towards the second end  152 . In this manner, the slots  160  provide a radially outward spring or retention force to the retention features  154 . In one embodiment, the retention sleeve is tapered radially inwardly along the axial centerline  122  from the first end  148  towards the second end  152 . 
       FIG. 6  provides a partially exploded cross section view of a portion of the fuel injector  100  including the aft plate  110 , according to one embodiment of the present invention. As shown, the aft plate  110  includes a retention collar  164 . In particular embodiments, the retention collar  164  is coaxially aligned with the retention sleeve  146 . The retention collar  164  and the air sleeve  150  at least partially define the cartridge passage  130 . 
       FIGS. 7 and 8  are enlarged cross sectional views of the fuel injector  100  including the retention sleeve  146  and the aft plate  110  according to one embodiment of the present invention. In one embodiment, as shown in  FIGS. 7 and 8 , the retention collar  164  is configured to receive and/or engage with the retention features  154  of the retention sleeve  146 . For example, an inner surface  166  of the retention collar  164  may define and/or include an engagement feature  168  such as a slot, groove or undercut that extends at least partially circumferentially along the inner surface  166 . The engagement feature  168  may define an axial stop feature  170  such as a ledge. 
     As shown in  FIG. 8 , the engagement feature  168  may have a profile that is complementary to a profile of the retention features  154 . In one embodiment, the retention features  154  are seated into the engagement feature  168 . In this manner, the retention sleeve  146  locks or retains the aft plate  110  to the fuel injector  100 . The retention features  154  may be held in position by the radial spring force exerted by the spring arms  162 . 
       FIGS. 9 and 10  are enlarged cross sectional views of the fuel injector  100  including the retention sleeve  146  and the aft plate  110  according to one embodiment of the present invention. In one embodiment, as shown in  FIGS. 9 and 10 , the fuel injector  100  includes a cartridge  172 . In particular embodiment, the cartridge  172  may comprise a fuel cartridge, an air cartridge or a blank cartridge. The cartridge  172  includes a downstream or aft end  174 . 
     During installation, as shown in  FIG. 9 , the cartridge  172  is inserted generally axially through the cartridge passage  134 . As shown in  FIG. 10 , the downstream end  174  of the cartridge  172  is inserted and/or disposed within the retention sleeve  146 . In one embodiment, the cartridge  172 , particularly the downstream end  174  is configured to engage with the inner surface  158  of the retention sleeve  146  proximate to the retention features  154 , thereby locking the retention features  154  into the engagement feature  168  of the retention collar  164 . For example, in one embodiment the downstream end  174  of the cartridge  172  may have an outer diameter  176  that is the same or greater than an inner diameter  178  of the retention sleeve  146 , thereby exerting a radially outward force to the retention features  154 . 
     The various embodiments provided herein, provide various technical advantages over existing bundled tube fuel injector assemblies. For example, the lack of a weld joint between the aft plate  110  and the retention sleeve  146  reduces assembly time and costs. In addition, the lack of a weld joint between the aft plate  110  and the retention sleeve  146  decreases cost to repair and/or inspect by decreasing or eliminating secondary machining operations currently required to break a weld joint and to prepare the components for reassembly. In addition, the retention features provide a reliable retention system for the aft plate, thus increasing the overall reliability of the fuel injector  100 . 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.