Patent Publication Number: US-10309653-B2

Title: Bundled tube fuel nozzle with internal cooling

Description:
FIELD OF THE TECHNOLOGY 
     The present invention generally involves a bundled tube fuel nozzle for a gas turbine combustor. More specifically, the invention relates to a bundled tube fuel nozzle with internal cooling. 
     BACKGROUND 
     Gas turbines are widely used in industrial and power generation operations. A gas turbine generally includes, in serial flow order, a compressor, a combustion section and a turbine. The combustion section may include multiple combustors annularly arranged around an outer casing. In operation, a working fluid such as ambient air is progressively compressed as it flows through the compressor. A portion of the compressed working fluid is routed from the compressor to each of the combustors where it is mixed with a fuel and burned in a combustion chamber or zone to produce combustion gases. The combustion gases are routed through the turbine along a hot gas path where thermal and/or kinetic energy is extracted from the combustion gases via turbine rotors blades coupled to a rotor shaft, thus causing the rotor shaft to rotate and produce work and/or thrust. 
     Particular combustion systems utilize bundled tube type fuel nozzles for premixing a gaseous fuel with the compressed air upstream from the combustion zone. An aft plate of the bundled tube fuel nozzle is disposed at a downstream end of the bundled tube fuel nozzle. A “hot side” of the aft plate is positioned proximate to outlets of each tube of the bundle tube fuel nozzle. As such, the hot side of the aft plate is exposed to extreme heat from the combustion gases. 
     BRIEF DESCRIPTION OF THE TECHNOLOGY 
     Aspects and advantages are set forth below in the following description, or may be obvious from the description, or may be learned through practice. 
     One embodiment of the present disclosure is a bundled tube fuel nozzle. The bundled tube fuel nozzle includes a forward plate, a first intermediate plate and an outer sleeve defining a fuel plenum therebetween. A second intermediate plate is axially spaced from the first intermediate plate and the first intermediate plate, the second intermediate plate and the outer sleeve define a purge air plenum therebetween. An aft plate is axially spaced from the second intermediate plate. The second intermediate plate, the aft plate and the outer sleeve define a cooling air plenum therebetween. A plurality of tubes extends through the forward plate, the fuel plenum, the first intermediate plate, the purge air plenum, the second intermediate plate, the cooling air plenum and the aft plate. An annular wall extends from the second intermediate plate to the aft plate and defines a cooling flow channel. A plurality of apertures is defined proximate to a cool side of the aft plate. The plurality of apertures provide for fluid communication between the cooling flow channel and the cooling air plenum. 
     Another embodiment of the present disclosure is a combustor. The combustor includes an end cover coupled to an outer casing and a bundled tube fuel nozzle disposed within the outer casing and coupled to the end cover via one or more fluid conduits. The bundled tube fuel nozzle comprises a forward plate, a first intermediate plate and an outer sleeve that define a fuel plenum therebetween. The fuel plenum is in fluid communication with the fluid conduit. A second intermediate plate is axially spaced from the first intermediate plate. The first intermediate plate, the second intermediate plate and the outer sleeve define a purge air plenum therebetween. An aft plate is axially spaced from the second intermediate plate. The second intermediate plate, the aft plate and the outer sleeve define a cooling air plenum therebetween. A plurality of tubes extends through the forward plate, the fuel plenum, the first intermediate plate, the purge air plenum, the second intermediate plate, the cooling air plenum and the aft plate. An annular wall extends from the second intermediate plate to the aft plate and defines a cooling flow channel within the bundled tube fuel nozzle. A plurality of apertures is defined proximate to a cool side of the aft plate. The plurality of apertures provide for fluid communication between the cooling flow channel and the cooling air plenum. 
     Another embodiment includes a combustor. The combustor includes an end cover coupled to an outer casing and a bundled tube fuel nozzle disposed within the outer casing and coupled to the end cover via a plurality of fluid conduits. The bundled tube fuel nozzle comprises a plurality of bundled tube fuel nozzle assemblies annularly arranged about a center fuel nozzle of the combustor. Each bundled tube fuel nozzle assembly comprises a forward plate, a first intermediate plate and an outer sleeve defining a fuel plenum therebetween. The fuel plenum is in fluid communication with at least one fluid conduit of the plurality of fluid conduits. A second intermediate plate is axially spaced from the first intermediate plate. The first intermediate plate, the second intermediate plate and the outer sleeve define a purge air plenum therebetween. An aft plate is axially spaced from the second intermediate plate. The second intermediate plate, the aft plate and the outer sleeve define a cooling air plenum therebetween. A plurality of tubes extends through the forward plate, the fuel plenum, the first intermediate plate, the purge air plenum, the second intermediate plate, the cooling air plenum and the aft plate. An annular wall extends from the second intermediate plate to the aft plate and defines a cooling flow channel within the bundled tube fuel nozzle. A plurality of apertures is defined proximate to a cool side of the aft plate. The plurality of apertures provides for fluid communication between the cooling flow channel and the cooling air plenum during operation of the combustor. 
     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 of various embodiments, 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 disclosure; 
         FIG. 2  is a simplified cross-section side view of an exemplary combustor as may incorporate various embodiments of the present disclosure; 
         FIG. 3  is an upstream view of an exemplary bundled tube fuel nozzle according to one or more embodiments of the present disclosure; 
         FIG. 4  is an enlarged cross sectional perspective view of a portion of the bundled tube fuel nozzle taken along section lines  4 - 4  as shown in  FIG. 3 , according to at least one embodiment of the present disclosure; 
         FIG. 5  is an enlarged view of a portion of the bundled tube fuel nozzle as shown in  FIG. 4 , according to at least one embodiment of the present disclosure; and 
         FIG. 6  is an operational diagram of the bundled tube fuel nozzle as shown in  FIG. 4 , according to at least one embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to present embodiments of the disclosure, 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 disclosure. 
     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 and/or coaxially aligned to an axial centerline of a particular component. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     Each example is provided by way of explanation, not limitation. In fact, it will be apparent to those skilled in the art that modifications and variations can be made 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 disclosure covers such modifications and variations as come within the scope of the appended claims and their equivalents. Although exemplary embodiments of the present disclosure will be described generally in the context of a bundled tube fuel nozzle for a land based power generating gas turbine combustor for purposes of illustration, one of ordinary skill in the art will readily appreciate that embodiments of the present disclosure may be applied to any style or type of combustor for a turbomachine and are not limited to combustors or combustion systems for land based power generating gas turbines unless specifically recited in the claims. 
     Referring now to the drawings,  FIG. 1  illustrates a schematic diagram of an exemplary gas turbine  10 . The gas turbine  10  generally includes an inlet section  12 , a compressor  14  disposed downstream of the inlet section  12 , at least one combustor  16  disposed downstream of the compressor  14 , a turbine  18  disposed downstream of the combustor  16  and an exhaust section  20  disposed downstream of the turbine  18 . Additionally, the gas turbine  10  may include one or more shafts  22  that couple the compressor  14  to the turbine  18 . 
     During operation, air  24  flows through the inlet section  12  and into the compressor  14  where the air  24  is progressively compressed, thus providing compressed air  26  to the combustor  16 . At least a portion of the compressed air  26  is mixed with a fuel  28  within the combustor  16  and burned to produce combustion gases  30 . The combustion gases  30  flow from the combustor  16  into the turbine  18 , wherein energy (kinetic and/or thermal) is transferred from the combustion gases  30  to rotor blades (not shown), thus causing shaft  22  to rotate. The mechanical rotational energy may then be used for various purposes such as to power the compressor  14  and/or to generate electricity. The combustion gases  30  exiting the turbine  18  may then be exhausted from the gas turbine  10  via the exhaust section  20 . 
     As shown in  FIG. 2 , the combustor  16  may be at least partially surrounded an outer casing  32  such as a compressor discharge casing. The outer casing  32  may at least partially define a high pressure plenum  34  that at least partially surrounds various components of the combustor  16 . The high pressure plenum  34  may be in fluid communication with the compressor  14  ( FIG. 1 ) so as to receive the compressed air  26  therefrom. An end cover  36  may be coupled to the outer casing  32 . In particular embodiments, the outer casing  32  and the end cover  36  may at least partially define a head end volume or portion  38  of the combustor  16 . In particular embodiments, the head end portion  38  is in fluid communication with the high pressure plenum  34  and/or the compressor  14 . One or more liners or ducts  40  may at least partially define a combustion chamber or zone  42  for combusting the fuel-air mixture and/or may at least partially define a hot gas path  44  through the combustor for directing the combustion gases  30  towards an inlet to the turbine  18 . In particular embodiments, as shown in  FIG. 2 , the combustor  16  includes a center fuel nozzle  46  coupled to the end cover  36  and extending axially towards the combustion chamber  42  with respect to an axial centerline  48  of the combustor  16 . 
     In various embodiments, the combustor  16  includes a bundled tube fuel nozzle  100 . As shown in  FIG. 2 , the fuel nozzle  100  is disposed within the outer casing  32  downstream from and/or axially spaced from the end cover  36  with respect to axial centerline  48  of the combustor  16  and upstream from the combustion chamber  42 . In particular embodiments, the bundled tube fuel nozzle  100  is in fluid communication with a gas fuel supply  50 . In one embodiment, the bundled tube fuel nozzle  100  is in fluid communication with the gas fuel supply  50  via one or more fluid conduits  102 . In particular embodiments, the fluid conduit(s)  102  may be fluidly coupled and/or connected at one end to the end cover  36 . 
       FIG. 3  provides an upstream view of an exemplary bundled tube fuel nozzle  100  according to at least one embodiment of the present disclosure.  FIG. 4  provides a cross sectioned downstream perspective view of a portion of the bundled tube fuel nozzle  100  taken along section line  4 - 4  as shown in  FIG. 3 , according to at least one embodiment of the present disclosure. Various embodiments of the combustor  16  may include different arrangements of the bundled tube fuel nozzle  100  and is not limited to any particular arrangement unless otherwise specified in the claims. For example, in particular configurations as illustrated in  FIG. 3 , the bundled tube fuel nozzle  100  includes multiple wedge shaped bundled tube fuel nozzle assemblies  104  annularly arranged with respect to centerline  48 . In particular embodiments, the bundled tube fuel nozzle  100  forms an annulus or fuel nozzle passage about a portion of the center fuel nozzle  46  ( FIG. 1 ). 
     In at least one embodiment, as shown in  FIG. 4 , the bundled tube fuel nozzle  100  and/or each bundled tube fuel nozzle assembly  104 , includes, in sequential order, a forward plate  106 , a first intermediate plate  108  axially spaced from the forward plate  106 , a second intermediate plate  110  axially spaced from the first intermediate plate  108 , an aft plate  112  axially spaced from the second intermediate plate  110  and an outer shroud or sleeve  114  that extends about an outer perimeter or peripheral edge of the forward plate  106 , the first intermediate plate  108 , the second intermediate plate  110  and the aft plate  112 . In at least one embodiment, the forward plate  106 , first intermediate plate  108 , second intermediate plate  110  and the aft plate  112  are wedge shaped with arcuate inner and outer sides. 
     In at least one embodiment, the forward plate  106 , the first intermediate plate  108  and the sleeve  114  at least partially define a fuel plenum  116  within the bundled tube fuel nozzle  100 . The forward plate  106  may define an opening  118  to the fuel plenum  116 . The opening  118  may be fluidly coupled to the fluid conduit  102  ( FIG. 2 ). The first intermediate plate  108 , the second intermediate plate  110  and the sleeve  114  at least partially define a purge air plenum  120  within the bundled tube fuel nozzle  100 . The second intermediate plate  110  defines a hole or passage  122 . In particular embodiments the passage  122  may be substantially aligned with the opening  118  of the forward plate  106 . An annular wall  124  extends axially from the second intermediate plate  110  to the aft plate  112  and is aligned with the passage  122 . The passage  122  and the wall  124  at least partially form a cooling flow channel  126  within the bundled tube fuel nozzle  100 . The second intermediate plate  110 , the aft plate  112 , the wall  124  and the outer sleeve  114  at least partially define a cooling air plenum  128  within the bundled tube fuel nozzle  100  and/or the bundled tube fuel nozzle assembly  104 . 
     As shown in  FIG. 4 , the bundled tube fuel nozzle  100  and/or the bundled tube fuel nozzle assembly  104  includes a plurality of tubes  130  that extends through the forward plate  106 , the fuel plenum  116 , the first intermediate plate  108 , the purge air plenum  120 , the second intermediate plate  110 , the cooling air plenum  128  and through the aft plate  112 . Each tube  130  includes an inlet  132  defined at or upstream from an upstream side  134  of the forward plate  106  and an outlet  136  defined at or downstream from a downstream or hot side  138  of the aft plate  112 . Each tube  130  defines a premix flow passage  140  through the bundled tube fuel nozzle  100  and/or the bundled tube fuel nozzle assembly  104 . One or more of the tubes  130  includes at least one fuel injection port  142  which provides for fluid communication between the fuel plenum  116  and the respective premix flow passage  140 . In at least one embodiment, as shown in  FIG. 4 , the plurality of tubes  130  is annularly arranged around the opening  118  in the forward plate  106 . 
       FIG. 5  is an enlarged cross sectional side view of a portion of the bundled tube fuel nozzle  100  or one of the bundled tube fuel nozzle assemblies  104  as shown in  FIGS. 3 and 4 , including a portion of the aft plate  112 , a portion of wall  124  and a portion of the cooling air plenum  128  according to at least one embodiment of the present disclosure. As shown in  FIGS. 4 and 5 , a downstream end portion  146  of the wall  124  and/or a cool side  148  of the aft plate  112  which is axially spaced from the downstream or hot side  138  of the aft plate  112  defines a plurality of apertures  150  circumferentially spaced thereabout. As shown in detail in  FIG. 5 , each aperture  150  includes an inlet  152  defined along an inner surface  154  of the wall  124  and/or along the cool side  148  of the aft plate  112 , and an outlet  156  defined along an outer surface  158  of the wall  124  and/or along the cool side  148  of the aft plate  112 . In at least one embodiment, one or more of the inlets  152  is disposed proximate or adjacent to the cool side  148  of the aft plate  112 . In at least one embodiment, one or more of the outlets  156  is oriented towards the cool side  148  of the aft plate  112 . During operation, the apertures  150  provide for fluid communication from the cooling flow channel  126  to the cooling air plenum  128 . 
       FIG. 6  provides an operational flow diagram of the bundled tube fuel nozzle  100  according to at least one embodiment of the present disclosure. During operation, as shown in  FIG. 6 , compressed air  200  such as the compressed air  26  from the compressor  14  enters the respective inlet  132  of each tube  130 . Fuel  202  flows into and pressurizes the fuel plenum  116  via the fluid conduit  102  ( FIG. 2 ). The fuel  202  is injected into the premix flow passage  140  of one or more of the tubes  130  via fuel injection port(s)  142 . The fuel  202  and compressed air  200  mix or blend together within the respective premix flow passages  140  to form a combustible fuel-air mixture  204  which exits the respective tube outlets  136  and is burned in the combustion chamber  42 . 
     An inert gas  206  such as compressed air  26  is injected or flows into the purge air plenum  120  via at least one inlet port  160  defined along the outer sleeve  114 . The inert gas  206  flows across a portion of the tubes  130  that extends through the purge air plenum  120 , thus providing cooling to the tubes  130  and/or the outer sleeve  114 . The inert gas  206  may also purge any fuel which may have leaked from the fuel plenum  116  into the purge air plenum  120 . A pressure differential between the purge air plenum  120  and the cooling air plenum  128  causes the inert gas  206  to travel through the cooling flow channel  126 , towards the cold side  148  of the aft plate  112 , into the respective inlets  152  of each aperture  150  and into the cooling air plenum  128 . 
     As shown in  FIGS. 5 and 6  collectively, one or more of the outlets  156  of the apertures  150  may be oriented so as to direct the inert gas  206  across the cold side  148  of the aft plate  112  and/or around the tubes  130  within the cooling air plenum  128 , thereby providing impingement, convection and/or conductive cooling of the aft plate  112  and/or the portion of tubes  130  disposed within the cooling air plenum  128 . The inert gas  206  may be exhausted from the cooling air plenum  128  via exhaust ports defined along the outer sleeve  114 . In particular embodiments, one or more exhaust ports  162  are defined along an outer band  164  portion of the outer sleeve  114 . In particular embodiments, one or more exhaust ports  166  are defined along an inner band portion  168  of the outer sleeve  114 . The inner band portion  168  of the outer sleeve  114  may extend at least partially around the center fuel nozzle  46 . As such, the exhaust ports  166  may provide cooling to a portion of the center fuel nozzle  46  and or may form a fluid seal between the inner band portion  168  and the center fuel nozzle  46 . 
     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.