Patent Publication Number: US-2012036857-A1

Title: Combustion liner stop blocks having insertable wear features and related methods

Description:
FIELD OF THE INVENTION 
     The present subject matter relates generally to combustion liner stops of gas turbine combustors and particularly to combustion liner stop blocks having insertable wear features and related methods. 
     BACKGROUND OF THE INVENTION 
     Gas turbines typically include a compressor section, a combustion section, and a turbine section. The compressor section pressurizes air flowing into the turbine. The pressurized air discharged from the compressor section flows into the combustion section, which is generally characterized by a plurality of combustors disposed around an annular array about the axis of the gas turbine. Each of the plurality of combustors includes a combustion liner, which defines the combustion chamber of the combustor. As such, air entering each combustor is mixed with fuel and combusted within the combustion liner. Hot combustion gases flow from the combustion liner through a transition piece to the turbine section of the gas turbine to drive the turbine and generate power. 
     The combustion liner of a gas turbine combustor is typically concentrically located within a flow sleeve of the combustor and radially inwardly spaced therefrom. The forward end of the combustion liner is generally provided with a plurality of circumferentially spaced liner stop tabs (i.e., male liner stops) which cooperate and/or mate with a corresponding number of liner stop blocks (i.e., female liner stops) secured to the flow sleeve or, in some embodiments, the combustion casing. As such, when the combustion liner is installed within the flow sleeve, the liner stops ensure proper radial and axial location of the combustion liner within the flow sleeve and also prevent the combustion liner from moving in an axially downstream direction (i.e., towards the transition piece). 
     The combustion liner stops generally support the combustion liner during the extreme vibration and heat produced by the combustion process occurring within the combustor. Often, vibration and thermal deformations resulting from combustion cause the combustion liner, the flow sleeve and other components of the combustor to vibrate and otherwise move with respect to one another. In particular, the combustion liner typically thermally deforms and vibrates with respect to the flow sleeve. As such, wear is often exhibited on the liner stops as a result of such deformation and/or vibration. This can lead to failure of the liner stop tab and/or the liner stop block, thereby resulting in misalignment of the combustion liner within the flow sleeve and/or damage to the combustion liner or flow sleeve. 
     To prevent such failure, it has been disclosed that the entire liner stop block of a combustor may be formed from a hardened alloy designed to reduce the amount of wear occurring between the liner stop block and the liner stop tab. However, to include such a liner stop block within an existing combustor, the pre-existing liner stop block must be removed from the flow sleeve, which can present several problems. In particular, removal of the existing liner stop block requires that a maintenance worker drill out the liner stop block from the flow sleeve, which can be a very labor intensive and timing consuming process. Moreover, removal of the original stop block effectively eliminates any of the locating features that were incorporated into the original design for aligning the liner stop block to the flow sleeve. As such, installation of the new liner stop block is often more difficult and can lead to misalignment of the liner stop block to the flow sleeve. Furthermore, both the existing and replacement liner stop blocks are often formed from relatively expensive alloys. As such, completely replacing a liner stop block can result in increased material costs. 
     Accordingly, a combustion liner stop block having insertable wear features and a method for installing such features within a liner stop block would be welcomed in the technology. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention. 
     In one aspect, the present subject matter discloses methods for installing wear features within a combustion liner stop block. The methods may generally include enlarging a slot defined in the liner stop block to form a cavity, locating an insert block in the cavity and providing at least one wear feature associated with the insert block. 
     In another aspect, the present subject matter discloses a combustion liner stop block for a combustor. The liner stop block may generally include an outer block defining a cavity and an insert block disposed in the cavity. The insert block may define a channel configured to receive a mating component of the liner stop block. Additionally, the liner stop block may include at least one wear feature associated with the insert block. 
     In a further aspect, the present subject matter discloses a combustor including a combustion casing, a flow sleeve and a combustion liner substantially concentrically arranged within the flow sleeve. The combustor may also include at least one liner stop tab secured to one of i) the flow sleeve ii) the combustion liner and iii) the combustion casing and at least one liner stop block secured to one other of i) the flow sleeve, ii) the combustion liner and iii) the combustion casing. The liner stop block may generally be configured to engage the liner stop tap. Additionally, the liner stop block may include an outer block defining a cavity, an insert block disposed in the cavity and at least one wear feature associated with the insert block. 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which: 
         FIG. 1  illustrates a cross-sectional side view of an embodiment of a gas turbine combustor; 
         FIG. 2  illustrates a perspective view of embodiments of a combustion liner stop block and a combustion liner stop tab; 
         FIG. 3  illustrates a flow chart providing one embodiment of a method for installing wear features within a combustion liner stop block in accordance with aspects of the present subject matter; 
         FIG. 4  illustrates a perspective view of embodiments of a combustion liner stop block and an insert block that may be inserted into the liner stop block in accordance with aspects of the present subject matter; 
         FIG. 5  illustrates a perspective view of the embodiments of the combustion liner stop block and the insert block shown in  FIG. 4 , particularly illustrating the insert block defining an elongated channel and being secured within the liner stop block in accordance with aspects of the present subject matter; 
         FIG. 6  illustrates a perspective view of an embodiment of a wear feature that may be inserted into an embodiment of an insert block in accordance with aspects of the present subject matter; and 
         FIG. 7  illustrates a perspective view of one embodiment of an assembled combustion liner stop block including insertable wear features in accordance with aspects of the present subject matter. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. 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 various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with 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. 
     The present subject matter is generally directed to a combustion liner stop block including insertable wear features and a method for installing such wear features within a liner stop block. For example, the disclosed liner stop block generally includes an insert block having one or more associated wear features configured to reduce the amount of wear occurring between the liner stop block and the liner stop tab. By associating such wear features with the disclosed insert block, the need to replace the original liner stop block is eliminated. In particular, a cavity may be formed within the original stop block which is configured to receive the insert block and associated wear features. Accordingly, the costs associated with removing the liner stop block, such as labor and material costs, can be eliminated. Additionally, by utilizing the original liner stop block, the precise location of the stop block achieved during original installation may be maintained. Moreover, the insert block of the present subject matter may be configured to have a standardized size and/or shape such that it may be used in a wide range of different gas turbines having liner stop blocks including varying sizes, shapes and/or configurations. 
     Referring now to the drawings,  FIG. 1  illustrates a cross-sectional side view of an embodiment of a gas turbine combustor  20 . The combustor  20  may generally include a substantially cylindrical combustion casing  22  secured to a portion of a gas turbine casing  24 , such as a compressor discharge casing or a combustion wrapper casing. The combustor  20  may also include an internal flow sleeve  26  and a combustion liner  28  substantially concentrically arranged within the flow sleeve  26 . Both the flow sleeve  26  and the combustion liner  28  may extend, at their downstream ends, to a double walled transition duct, including an impingement sleeve  30  and a transition piece  32  disposed within the impingement sleeve  30 . However, it should be appreciated that some gas turbines may only include a single-wall transition duct. Additionally, the impingement sleeve  30  and the flow sleeve  26  may be provided with a plurality of air supply holes  34  over a portion of their surfaces, thereby permitting pressurized air from the compressor section of a gas turbine to enter the radial space between the combustion liner  28  and the flow sleeve  26 . 
     The combustion liner  28  of the combustor  20  may generally define a substantially cylindrical combustion chamber  36 , wherein fuel and air are injected and combusted to produce hot gases of combustion. Additionally, the combustion liner  28  may be coupled at its downstream end to the transition piece  32  such that the combustion liner  28  and the transition piece  32  generally define a flow path for the hot gases of combustion flowing from each combustor  20  to the turbine section of a gas turbine. 
     The combustion liner  28  may also include one or more male liner stop tabs  38  configured to mate with or otherwise engage one or more female liner stop blocks  40  secured to the flow sleeve  26  or, in some embodiments, the combustion casing  22 . In particular, the liner stop tabs  38  may be adapted to slide into an elongated slot  52  ( FIG. 2 ) defined within the liner stop blocks  40  as the combustion liner  28  is installed in the combustor  20  so as to ensure proper circumferential alignment of the liner  28  within the flow sleeve  26 . Additionally, the liner stops  38 ,  40  may be also utilized to indicate the proper installation depth of the combustion liner  28  as well as prevent rotation and/or axial movement of the liner  28  during operation of the combustor  20 . It should be appreciated that, in alternative embodiments, the liner stops tabs  38  may be disposed on the flow sleeve  26  or the combustion casing  22  while the liner stop blocks  40  may be disposed on the combustion liner  28 . 
     Referring now to  FIG. 2 , perspective views of embodiments of a combustion liner stop tab  38  and combustion liner stop block  40  are illustrated. Generally, the liner stop block  40  may be secured to an inner surface  42  of the flow sleeve  26 . However, as indicated above, in some embodiments, the liner stop block  40  may be secured to an inner surface of the combustion casing  22 . Additionally, the liner stop tab  38  may be secured to an outer surface  44  of the combustion liner  28 . It should be appreciated that the liner stop block  40  and stop tab  38  may be secured to the flow sleeve  26  and combustion liner  28 , respectively, using any suitable means known in the art. For example, as shown in  FIG. 2 , the liner stop block  40  may be welded to the inner surface  42  of the flow sleeve  26 . The liner stop block  40  may also include a pin, rod or other mounting feature (not illustrated) extending through the flow sleeve  26  to provide a further attachment mechanism between the stop block  40  and the flow sleeve  26 . Similarly, the liner stop tab  38  may be welded to the outer surface  44  of the combustion liner  28 . However, it should be appreciated that, in alternative embodiments, the liner stops  38 , 40  may be secured to their respective combustor components using a suitable attachment mechanism, such as by using screws, bolts or any other known mechanical fastener. 
     In general, it should be appreciated that the liner stop block  40  and the liner stop tab  38  may be designed to have any suitable shape and/or configuration that enables the liner stop tab  38  to mate and/or engage with the liner stop block  40  so as to facilitate installation of the combustion liner  28  and/or to properly align the combustion liner  28  within the flow sleeve  26  (or combustion casing  22 ) and/or to prevent rotation and/or axial movement of the liner  28  during operation of the combustor  20 . For example, in the embodiment illustrated in  FIG. 2 , the liner stop block  40  may comprise a substantially planar or flat end  46 , a rounded or curved end  48 , and a pair of side walls  50  extending between the flat end  46  and the curved end  48 . The liner stop block  40  may also define an elongated slot  52  configured to receive the liner stop tab  38 . The elongated slot  52  may generally be defined from the flat end  46  of the liner stop block  40  and may extend in the direction of the curved end  48 . Additionally, as shown in  FIG. 2 , the liner stop tab  38  may generally comprise a base  54  and a substantially rectangular protrusion  56  extending from the base  54  such that the liner stop tab  38  may slide into and engage the liner stop block  40  as the combustion liner  28  is installed within the flow sleeve  26 . It should be appreciated that, although a single set of liner stops  38 , 40  is illustrated in  FIG. 2 , two, three or more sets of liner stops  38 , 40  may be included within each combustor  20 . 
     As indicated above, the present subject matter is generally directed to a liner stop block having insertable wear features and a method for installing wear features within a liner stop block. Thus, one embodiment of the disclosed method will generally be described with reference to  FIG. 3  and will be explained in greater detail with reference to  FIGS. 4-7 . Additionally, various embodiments of the disclosed liner stop block will also be described with reference to  FIGS. 4-7 . 
     Thus, referring to  FIG. 3 , one embodiment of a method for installing wear features within a combustion liner stop block is illustrated. Generally, the method includes enlarging a slot defined in the liner stop block to form a cavity  302 , locating an insert block in the cavity  304  and providing at least one wear feature associated with the insert block  306 . As indicated above, the disclosed method may generally permit wear features to be installed within a liner stop block without necessitating the removal of the existing stop block. As such, the method will generally be described herein with reference to installing wear features into new and used liner stop blocks that were not originally designed to include such features. However, it should be appreciated that the disclosed method may also be used to quickly and efficiently install new wear features into liner stop blocks that did, in fact, initially include one or more wear features. It should also be appreciated that, although the various elements  302 ,  304 ,  306  of the disclosed method are illustrated in a particular order in  FIG. 3 , the elements may generally be performed in any sequence and/or order consistent with the disclosure provided herein. 
     Referring now to  FIG. 4 , there is illustrated perspective views of embodiments of a liner stop block  40  attached to a portion of a flow sleeve  26  of a combustor  20  ( FIG. 1 ). In particular,  FIG. 4  illustrates embodiments of the liner stop block  40  before and after it has been enlarged to define a cavity  60  in accordance with aspects of the present subject matter. Thus, initially, the liner stop block  40  may generally define an elongated slot  52  which, as indicated above, may be configured to accommodate a corresponding liner stop tab  38  ( FIG. 2 ). However, as shown in  FIG. 4 , an enlarged cavity  60  may be formed within the liner stop block  40  by machining or otherwise removing material from the stop block  40  in the area adjacent to the elongated slot  52 . Accordingly, in one embodiment, the cavity  60  may define a larger volume than the volume defined by the elongated slot  52 . In general, the cavity  60  may be formed in the liner stop block  40  such that an insert block  62  may be inserted into or otherwise disposed within the cavity  60 . As such, the liner stop block  40  may generally serve as an outer block  64  for receiving the insert block  62 . It should be appreciated that the cavity  60  may be formed using any suitable means known in the art. For example, various known machining processes, such as milling processes, drilling processes, other precision machining processes and the like, may be utilized to form the cavity  60  within the liner stop block  40 . 
     In general, the insert block  62  and cavity  60  may be designed to have any suitable shape and/or configuration that permits such components to function as described herein. For example, in one embodiment, the insert block  62  may be configured substantially similar to that of the liner stop block  40 . Thus, in the illustrated embodiment, the insert block  62  may include a substantially planar or flat end  66 , a rounded or curved end  68 , and a pair of side walls  70  extending between the flat end  66  and the curved end  68 . Additionally, as shown in  FIG. 4 , the cavity  60  may define a corresponding shape so that the insert block  62  may be received therein. However, in alternative embodiments, it should be appreciated that the insert block  62  and corresponding cavity  60  may be substantially rectangular in shape or may otherwise define any other suitable shapes and/or cross-sections. It should also be appreciated that the insert block  62  may generally be formed from any suitable material. However, in a particular embodiment, the insert block  62  may be formed from a relatively inexpensive metal, such as carbon steel. 
     Referring still to  FIG. 4 , the insert block  62  may also be configured to be secured within the cavity  60  using any suitable means known in the art. For example in one embodiment, the insert block  62  may be configured to be welded to the liner stop block  40 . In such an embodiment, the insert block  62  may define one or more weld preparation features configured to aid in welding the insert block  62  to the liner stop block  40 . For instance, as shown, the insert block  62  may define a chamfered or beveled edge  72  along portions of its outer perimeter. Other suitable weld preparation features may include grooves, ridges, notches, and the like. In alternative embodiments, the insert block  62  may be configured to be secured within the cavity  60  using mechanical fasteners, such as by using bolts or screws, or using any other suitable attachment mechanisms and/or processes known the art. Additionally, it should be appreciated that, when inserted into the liner stop block  40 , the insert block  62  need not be configured as a blank (e.g., a solid block of material) as is illustrated in  FIG. 4 . For example, in alternative embodiments, the insert block  62  may include machined features, such as the channel  74  and/or recessed area  76  described with reference to  FIGS. 5 and 6 , and/or may include one or more wear features prior to being inserted into the liner stop block  40 . 
     Referring now to  FIG. 5 , there is illustrated a perspective view of one embodiment of the insert block  62  secured within the cavity  60  of the liner stop block  40 . In particular, the insert block  62  is shown as being welded to the liner stop block  40  along the beveled edge  72  defined at the interface of the insert block  62  and the liner stop block  40 . Moreover, as shown in  FIG. 5 , a channel  74  may be formed within the insert block  62  such that the liner stop tab  38  ( FIG. 2 ) of the combustion liner  28  may be received within the channel  74  as the combustion liner  28  is installed within the flow sleeve  26 . In general, it should be appreciated that the channel  74  may be formed within the insert block  62  so as to define any suitable shape and/or cross-section. However, in a particular embodiment of the present subject matter, the channel  74  may define the same size, shape and/or dimensions as the elongated slot  52  ( FIG. 4 ) defined within the liner stop block  40 . 
     It should be appreciated that the channel  74  may be formed using any suitable means. For example, various known machining processes, such as milling processes, drilling processes, other precision machining processes and the like, may be utilized to form the channel  74  within the insert block  62 . Additionally, as indicated above, the channel  74  may be formed before or after the insert block  62  is inserted into and/or secured to the liner stop block  40 . For example, the insert block  62  may be pre-machined or otherwise formed (e.g., by a molding process) so that the channel  74  is defined within the insert block  62  prior to the block  62  being inserted into the liner stop block  40 . 
     Referring now to  FIG. 6 , there is illustrated one embodiment of a wear feature that may be included within the insert block  62  in accordance with aspects of the present subject matter. As shown, the wear feature comprises a wear shim or wear strip  78  that may generally be configured to reduce the amount of wear occurring between the liner stop block  40  and the liner stop tab  38 . In particular, the wear strip  78  may be formed from any suitable wear-resistant material capable of preventing or reducing wear between the liner stop block  40  and the liner stop tab  38 . For example, suitable materials that may be used to form the wear strip  78  may include cobalt-based alloys, such as FSX-14 and L-605, nickel-based alloys, other hardwearing/hardfacing materials, and the like. 
     In an alternative embodiment, it should be appreciated that the wear feature of the present subject matter may comprise a wear resistant coating that may be applied to the surface of the channel  74  defined in the insert block  62  using any suitable process, such as by welding, metal spraying, thermal spraying, diffusion processes, and the like. Suitable wear resistant coatings may include, but are not limited to, coatings comprising one or more of the following materials: chromium carbide, tungsten, cobalt, STELLITE 6 alloy, any suitable hardwearing/hardfacing material, and/or any other materials that, when applied to the channel  74 , may increase the wear resistance of the insert block  62 . In another embodiment, the entire insert block  62  may be formed from a wear resistant material. In such an embodiment, the insert block  62 , itself, may serve as the wear feature of the present subject matter. Suitable wear resistant materials may include cobalt-based alloys, such as FSX-14 and L-605, nickel-based alloys, other hardwearing/hardfacing materials, and the like. 
     Referring still to  FIG. 6 , in embodiments in which the wear feature comprises a wear strip  78 , the wear strip  78  may generally be configured to have any suitable shape and/or configuration that permits the strip  78  to be inserted into or otherwise disposed within the insert block  62 . The wear strip  78  may also be configured so as to define an elongated opening  80 . For example, in one embodiment, the opening  80  may be substantially shaped, sized and/or dimensioned similarly to the channel  74  defined within the insert block  62  and/or the slot  52  ( FIG. 4 ) defined within the liner stop block  40 . As such, it should be appreciated that the opening  80  may be adapted to engage with or otherwise receive the liner stop tab  38  ( FIG. 2 ) of the combustion liner  28  as the combustion liner  28  is installed within the flow sleeve  26 . Accordingly, the wear strip  78  may generally serve as the interface between the insert block  62  and the liner stop tab  38  and, thus, may reduce the amount of wear occurring between the liner stop block  40  and the liner stop tab  38  during operation of the combustor  20 . 
     Moreover, in one embodiment, a recessed area  76  may be defined within the channel  74  of the insert block  62  and may be configured to accommodate the wear strip  78 . Thus as shown in  FIG. 6 , a recessed area  76  may be formed within the insert block  62  by machining or otherwise removing material from the insert block  62  such that at least a portion of the channel  74  is enlarged or otherwise widened. In one embodiment, the recessed area  76  may generally be shaped, sized or otherwise configured to have substantially the same shape, size and/or dimensions of the wear strip  78 . For example, as shown in  FIG. 7 , the recessed area  76  may be formed so that, when the wear strip  78  is inserted into insert block  62 , the wear strip  78  is positioned substantially flush with the portion of the channel  74  not enlarged or otherwise widened by the formation of the recessed area  76 . It should be appreciated that the recessed area  76  may be formed using any suitable means. For example, various known machining processes, such as milling processes, drilling processes, other precision machining processes and the like, may be utilized to form the recessed area  76  within the insert block  62 . It should also be appreciated that, in alternative embodiments, a recessed area  76  need not be defined within insert block  62 . For example, the channel  74  may be formed within the insert block  62  so as to define appropriate dimensions for receiving the wear strip  78 . 
     Referring now to  FIG. 7 , there is illustrated one embodiment of an assembled combustion liner stop block  40  having insertable wear features in accordance with aspects of the present subject matter. As shown, the combustion liner stop block  40  generally includes an outer block  64 , an insert block  62  and a wear strip  78 , each of which may generally be configured as described above. Thus, the outer block  64  may be configured to be secured to a portion of the flow sleeve  26 , or, as the case may be, the combustion casing  22  of a combustor  20  ( FIG. 1 ). Additionally, the outer block  64  may generally define a cavity  60  ( FIG. 4 ) for receiving the insert block  62 . As shown, the insert block  62  may generally include a recessed area  76  ( FIG. 6 ) within a channel  74  for receiving the wear strip  78 . Further, the wear strip  78  may be configured to fit within the recessed area  76  and may define an elongated opening  80  configured to receive the liner stop tab  38  ( FIG. 2 ) of the combustion liner  28 . As such, the wear strip  78  may serve as the interface between the liner stop block  40  and the liner stop tab  38  and, thus, may reduce the amount of wear occurring between such components. 
     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 languages of the claims.