Patent Publication Number: US-2017350321-A1

Title: Bundled Tube Fuel Nozzle Assembly with Tube Extensions

Description:
FIELD OF THE TECHNOLOGY 
     The present disclosure is directed to a bundled tube fuel nozzle assembly for a gas turbine combustor. More particularly, the present disclosure is directed a bundled tube fuel nozzle assembly with tube extensions. 
     BACKGROUND 
     Particular combustion systems for gas turbine engines utilize combustors having bundled tube type fuel nozzle assemblies for premixing a gaseous fuel with a compressed air upstream from a combustion zone. A bundled tube fuel nozzle assembly generally includes multiple tubes that extend through a fuel plenum which is at least partially defined between a forward plate, an axially spaced aft plate and an outer sleeve. Each tube extends through a respective tube hole defined in the forward plate and a corresponding tube hole defined in the aft plate. During operation, compressed air flows into an inlet portion of each tube. Fuel from the fuel plenum is injected into each tube via a respective fuel port where it premixes with the compressed air before it is routed into the combustion zone. 
     In order to seal the fuel plenum, a first braze or weld joint is formed between each tube and the respective tube hole defined in the forward plate and a second braze or weld joint is formed between the tube and the corresponding tube hole defined in the intermediate plate. In various configurations, bundled tube fuel nozzle assemblies may include a large number of closely packed tubes. As such, hundreds of braze joints may be required to effectively seal the fuel plenum. Each braze joint provides a potential fuel leak point and may be generally difficult to form due to the close proximity of the tubes. Therefore, an improved bundled tube fuel nozzle assembly would be useful. 
     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 assembly. The bundled tube fuel nozzle assembly includes a fuel plenum body defining a forward wall, an aft wall, an outer band, a fuel plenum defined within the fuel plenum body and a plurality of tubular passages that extends from the forward wall, through the fuel plenum and to the aft wall, wherein the fuel plenum body is formed as a singular body. The bundled tube fuel nozzle assembly further includes a plurality of tube extensions that extends downstream from the plurality of tubular passages. At least one tube extension of the plurality of tube extensions includes an upstream end that extends axially into a respective outlet of a respective tubular passage of the plurality of tubular passages. 
     One embodiment of the present disclosure is directed to a bundled tube fuel nozzle assembly. The bundled tube fuel nozzle assembly includes a fuel plenum body defining a forward wall, an aft wall, an outer band, a fuel plenum defined within the fuel plenum body and a plurality of tubular passages that extends from the forward wall, through the fuel plenum and to the aft wall. The fuel plenum body is formed as a singular body. A plurality of tube extensions extends downstream from the plurality of tubular passages. Each tube extension of the plurality of tube extensions is coaxially aligned with a respective outlet of a respective tubular passage of the plurality of tubular passages. Each tube extension includes a respective upstream end that is fixedly connected to the fuel plenum body. 
     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 assembly disposed within the outer casing and fluidly coupled to the end cover via one or more fluid conduits. The bundled tube fuel nozzle assembly includes a fuel plenum body that defines a forward wall, an aft wall, an outer band, a fuel plenum defined within the fuel plenum body and a plurality of tubular passages that extends from the forward wall, through the fuel plenum and to the aft wall. The fuel plenum body is formed as a singular body. A plurality of tube extensions extends downstream from the plurality of tubular passages. At least one tube extension of the plurality of tube extensions includes an upstream end that extends axially into a respective outlet of a respective tubular passage of the plurality of tubular passages. 
     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 a cross sectioned side view of an exemplary bundled tube fuel nozzle assembly according to various embodiments of the present disclosure; and 
         FIG. 4  is an enlarged cross sectioned side view of a portion of the exemplary bundled tube fuel nozzle assembly as shown in  FIG. 3  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 assembly 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 through the combustor as indicated by arrow  44 , for directing the combustion gases  30  towards an inlet to the turbine  18 . 
     In various embodiments, the combustor  16  includes at least one bundled tube fuel nozzle assembly  100 . As shown in  FIG. 2 , the bundled tube fuel nozzle assembly  100  is disposed within the outer casing  32  downstream from and/or axially spaced from the end cover  36  with respect to axial centerline  46  of the combustor  16  and upstream from the combustion chamber  42 . In particular embodiments, the bundled tube fuel nozzle assembly  100  is in fluid communication with a gas fuel supply  48  via one or more fluid conduits  50 . In particular embodiments, the fluid conduit(s)  50  may be fluidly coupled and/or connected at one end to the end cover  36 . 
       FIG. 3  provides a partially exploded cross sectioned side view of an exemplary bundled tube fuel nozzle assembly  100  according to various embodiments of the present disclosure. In various embodiments, as shown in  FIG. 3 , the bundled tube fuel nozzle assembly  100  includes a fuel plenum body  102  and a plurality of tube extensions  104 . The fuel plenum body  102  defines an upstream or forward wall  106 , a downstream or aft wall  108  and an outer band or sleeve  110  that extends between the forward wall  106  and the aft wall  108 . The fuel plenum body  102  is not limited to any particular shape unless otherwise recited in the claims. For example, in particular embodiments, the fuel plenum body  102  may be disk shaped or may be wedge shaped. 
     As shown in  FIG. 3 , the bundled tube fuel nozzle assembly  100  further defines a fuel plenum  112  defined within the fuel plenum body  102  and a plurality of tubes or tubular passages  114  that extends from the forward wall  106 , through the fuel plenum  112  and to the aft wall  108 . In at least one embodiment, the fuel plenum  112  is at least partially defined between the forward wall  106 , the aft wall  108  and the outer band  110 . Each tubular passage  114  defines a respective flow passage or premix flow passage  116  through the fuel plenum body  102 . In particular embodiments, one or more of the premix flow passages  116  is in fluid communication with the fuel plenum  112  via one or more fuel ports  118  defined in one or more of the tubular passages  114 . Each tubular passage  114  includes a respective inlet  120  defined along the forward wall  106 . Each tubular passage  114  also includes a respective outlet  122  defined along the aft wall  108 . 
     In at least one embodiment, the fuel plenum body  102  is formed as a singular body. In other words, the forward wall  106 , the aft wall  108 , the outer band  110 , the tubular passages  116  and the fuel plenum  112  may all be formed as a singular body. For example, in particular embodiments, the fuel plenum body  102  is formed via an additive manufacturing process. The terms additive manufacturing or additively manufactured as used herein refers to any process which results in a useful, three-dimensional object and includes a step of sequentially forming the shape of the object one layer at a time. Additive manufacturing processes may include three-dimensional printing (3DP) processes, laser-net-shape manufacturing, direct metal laser sintering (DMLS), direct metal laser melting (DMLM), plasma transferred arc, freeform fabrication, etc. 
     As shown in  FIG. 3 , the plurality of tube extensions  104  extends axially outwardly or downstream from the aft wall  108  and downstream from the plurality of tubular passages  114 . In at least one embodiment, each tube extension  104  may be coaxially aligned with a respective tubular passage  114 . Each tube extension  104  of the plurality of tube extensions  104  includes an upstream end or tube extension inlet  124  that is axially spaced from a downstream end or tube extension outlet  126 . 
       FIG. 4  provides a cross sectioned side view of a portion of the bundled tube fuel nozzle assembly  100  as shown in  FIG. 3  with one tube extension  104  assembled to the fuel plenum body  102  and with one tube extension  104  exploded away from the fuel plenum body  102 , according to at least one embodiment of the present disclosure. In various embodiments, the upstream end  124  of each tube extension  104  is fixedly connected to and/or at least partially sealed against the fuel plenum body  102 . For example, the upstream end  124  of each tube extension  104  may be brazed, welded or otherwise fixedly connected to the fuel plenum body  102 . In at least one embodiment, each tube extension  104  is in fluid communication with a corresponding tubular passage  114  such that the tubular passage  114  and the respective tube extension  104  form a continuous premix flow passage  116  that extends from the respective tubular passage inlet  120  ( FIG. 3 ) defined along the forward wall  106  of the fuel plenum body  102  to the tube extension outlet  126  of the corresponding tube extension  104 . 
     In at least one embodiment, as shown in  FIG. 4 , the outlet  122  of at least one respective tubular passage  114  and/or the aft wall of the fuel plenum body  102  is counterbored  128 . The counterbore  128  facilitates insertion into and/or alignment of each tube extension  104  with a respective outlet  122  of a respective tubular passage  114 . In particular embodiments, a rim portion  130  of the outlet  122  of at least one respective tubular passage  114  is tapered or converges radially inwardly from the aft wall  108  towards the forward wall  106  ( FIG. 3 ). 
     In particular embodiments, as shown in  FIG. 4 , the upstream end  124  of at least one tube extension  104  of the plurality of tube extensions  104  extends axially into and/or is seated within a respective outlet  122  of a corresponding tubular passage  114 . In particular embodiments, as shown in  FIG. 4 , at least one tube extension  104  of the plurality of tube extensions  104  has a reduced outer diameter  132  at or proximate to the upstream end  124  when compared to the outer diameter of the same tube at or proximate to the respective downstream end or outlet  126  to allow for installation into the corresponding outlet  122  and to reduce or minimalize the required diameter of the corresponding outlet  122 . 
     In operation, compressed air  26  from the high pressure plenum  34  flows into the tubular passages  116  via inlets  122 . Fuel is supplied to the fuel plenum  112  via one or more of the fluid conduits  50 . The fuel is then injected into each premix flow passage  116  via fuel ports  120 . The fuel and compressed air mix within the tubular passages  116  and the tube extensions  104  before flowing out of the tube extension outlets  128  into the combustion zone  42  where it is burned to produce the combustion gases  30 . 
     The bundled tube fuel nozzle assembly  100  shown and described herein provides various technical benefits over existing bundled tube fuel nozzle assemblies. For example, forming the fuel plenum body  102  as a singular component significantly reduces the likelihood of a fuel leak from the fuel plenum by decreasing the number of braze joints normally required to seal the fuel plenum. Brazing the tube extensions  104  into the respective outlets  122  forms continuous surfaces between the fuel plenum body  102  and the tube extensions, thereby allowing for a wider fuel range capability when compared to particular known bundled tube fuel nozzle assembly configurations. By brazing in the tube extensions  104 , flame-holding capability of the bundled tube fuel nozzle assembly  100  is increased significantly. With the brazed in tube extensions  104 , the fuel plenum body  102  may accept a wide range of fuel types. 
     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.