Abstract:
A liner stop for retaining a liner within a sleeve of a combustion system, includes: a female component including a saddle, the female component adapted for coupling to one of the liner and the sleeve; a male component including a tab for insertion into the saddle, the male component adapted for coupling to an opposite one of the liner and the sleeve; and an insert adapted for being attached to the tab and ensuring dampening of vibration when the tab is disposed within the saddle. A method and a system are also disclosed.

Description:
BACKGROUND OF INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to combustion chambers in gas turbine engines, and in particular, the invention relates to mounting and alignment of combustion liners within the combustion chambers of gas turbines. 
         [0003]    2. Description of the Related Art 
         [0004]    The combustion system of a gas turbine generates hot gases to drive a turbine. The turbine, in turn, drives a compressor that provides compressed air for combustion in the combustion system. In addition, the turbine produces usable output power. A combustion system for a gas turbine may be configured as a circular array of combustion chambers arranged to receive compressed air from the compressor, inject fuel into the compressed air to create a combustion reaction, and generate hot combustion gases for the turbine. Each cylindrical combustion chamber includes one or more fuel nozzles, a combustion zone within the combustion liner, a flow sleeve surrounding and radially spaced from the liner, and a gas transition duct between the combustion chamber and turbine. 
         [0005]    The combustion zone is a volume within the combustion liner in which the fuel/air mixture combusts to generate the hot gases. Compressed air flows from the compressor to the combustion zone through an annular gap between the combustion liner and flow sleeve. Air flowing through this gap cools the outer surface of the liner and flows into the combustion zone through holes in the combustion liner. Compressor air flows between the liner and flow sleeve in a first direction, reverses direction as it enters the combustion liner, and flows as a hot gas in an opposite direction out of the liner and combustor, and to the turbine. 
         [0006]    The combustion liner operates in a high temperature environment in which a roaring combustion process generates a stream of high-velocity hot gases that flow through the liner and to the turbine. Heat and vibration from the combustion processes, as well as other mechanical loads and stresses from the gas turbine shake, rattle and otherwise vibrate the combustion liner, flow sleeve and the other components of the combustion chamber. Accordingly, the combustion liner should be mounted in the flow sleeve to withstand the heat, vibration and loads imposed by the combustion of gases and other forces that act on the combustion chamber. 
         [0007]    Liner stops mount the combustion liner concentrically within the combustion flow sleeve. Three liner stops are typically arranged around on the outer surface of the combustion liner, and bridge a gap between the liner and flow sleeve. Each liner stop on the combustion liner mates with a matching liner stop on an inside surface of the flow sleeve. The liner stops align the liner within the flow sleeve, and with respect to the fuel nozzles and other components of the combustion chamber. 
         [0008]    Prior liner stops have had difficulty in aligning the combustion liner in the flow sleeve, especially during assembly of the combustion system. During assembly, the combustion liner is inserted into the cylindrical flow sleeve. The liner is held into place by three liner stops and a hula seal. The liner stops on the combustion liner fit into the matching liner stops in the flow sleeve. When the combustion liner is assembled into the flow sleeve the hula seal engages before the liner stop on the combustion liner can be inserted into the matching liner stops on the flow sleeve. As a result the stops are not allowed to self align as the liner is inserted into the flow sleeve. A misalignment between the liner and flow sleeve often resulted in the liner stops being non-uniformly loaded. This requires the liner to be adjusted after being installed into the flow sleeve, which is difficult and time consuming given the liner is held into place by the hula seal. In addition, the potential for misalignment between the combustion liner and flow sleeve has resulted in a relatively-high number of defects in combustion systems. 
         [0009]    The liner stops support the liner during the extreme vibration and heat that result from combustion within the combustion liner. Vibration and thermal deformations due to the combustion process cause the liner, flow sleeve, and other components of the combustor to vibrate and otherwise move with respect to each other. In particular, the combustion liner thermally deforms and vibrates with respect to the flow sleeve and fuel nozzle. Accordingly, the liner stops should maintain the alignment between the liner, sleeve and flow nozzle despite the vibration forces and deformation inherent in a combustion system. 
         [0010]    Prior combustion liner stops suffered from excessive wear of their contacting surfaces. The contact surfaces in liner stops are those surfaces of the male and female stops that are in rubbing contact when the liner is in the flow sleeve. The contacting surfaces in the liner stops support the weight of the combustion liner, and transfer vibration and other dynamic forces between the liner and flow sleeve. These contacting surfaces should also withstand the wear that results as these surfaces rub together. During operation of the combustion system, the liner stops may develop a wear cycle of increasing surface wear, which allows for greater vibratory movements between the liner stops, and which in turn causes even more surface wear. 
         [0011]    The vibration/wear cycle of the liner stops can continue until the contacting surfaces wear through and the liner stops fail. When liner stops wear through and fail, the wearing surfaces in the combustion chamber may shift away from the liner stops to other surfaces that are not intended to be in rubbing contact. Similarly, unintended contact between surfaces in the combustion chamber may result due to misalignment as the combustion liner is inserted into the flow sleeve. If the wearing surfaces in a combustor shift away from the liner stops, then the surfaces of, for example, the combustion liner and fuel nozzles may come into rubbing contact. The surfaces of the liner and fuel nozzle are not designed or intended to support the combustion liner or to withstand the rubbing wear that occurs during vibration. When the contacting surfaces shift from the liner stops to other combustor chamber components, the cycle of wear and vibration may continue rapidly until the combustor fails, or until a sufficient clearance develops between the new rubbing surfaces to give way and allow the rubbing surfaces to transfer back to the liner stops or other combustor component. Even when the rubbing contact shifts back to the liner stops, wear damage to the liner, nozzles or other combustion components may cause premature failure of the combustion chamber. 
         [0012]    Excessive wear between the liner stops, combustion liner and flow sleeves requires frequent maintenance inspections of the liners and stops and can lead to combustor failure. In the past, excessive wear of liner stops has necessitated that gas turbines be regularly shut down to inspect and replace worn combustion components and, in particular, liner stops. 
         [0013]    Accordingly, there is a need for combustion liner stops that allow for easy alignment of the combustion liner and flow sleeve during assembly, provide vibration resistant support for the sleeve and do not fail due to vibratory wear. Preferably, such liner stops are easy to install and maintain. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0014]    In one embodiment, a liner stop for retaining a liner within a sleeve of a combustion system, is disclosed and includes: a female component including a saddle, the female component adapted for coupling to one of the liner and the sleeve; a male component including a tab for insertion into the saddle, the male component adapted for coupling to an opposite one of the liner and the sleeve; and an insert adapted for being attached to the tab and ensuring dampening of vibration when the tab is disposed within the saddle. 
         [0015]    In another embodiment, a method for inserting a liner into a sleeve of a combustion system, is disclosed and includes: installing one of a male component and a female component onto an outer surface of the liner; installing an opposite one of the male component and the female component onto an inner surface of the sleeve; installing an insert onto a tab of the male component; and inserting the liner into the sleeve such that the tab becomes disposed within a saddle of the female component. 
         [0016]    In a further embodiment, a combustion system including a liner inserted into a sleeve, is disclosed and includes: a plurality of liner stops disposed between the liner and the sleeve, each liner stop including a female component including a saddle, the female component adapted for coupling to one of the liner and the sleeve; a male component including a tab for insertion into the saddle, the male component adapted for coupling to an opposite one of the liner and the sleeve; and an insert adapted for being attached onto the tab and ensuring retention of the liner within the sleeve and dampening of vibration when the tab is disposed within the saddle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  depicts a cross section of aspects of a combustion system; 
           [0018]      FIG. 2  provides a perspective view of a female component of the liner stop; 
           [0019]      FIG. 3  depicts a perspective view of the male component of the liner stop; 
           [0020]      FIG. 4  depicts a perspective view of an insert of the liner stop; 
           [0021]      FIG. 5  depicts a liner stop for securing a liner of the combustion system; 
           [0022]      FIG. 6  depicts a male component and an insert of the liner system; and, 
           [0023]      FIG. 7  is a flow chart providing an exemplary method for installing the liner of the combustion system. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    Disclosed is a liner stop that provides for at least one of installation and wear mitigation at the interfaces of a combustion liner and a flow sleeve within a combustion system, such as a gas turbine. The function may be provided by use of a plurality of liner stops which are generally disposed in an even distribution within the liner and the flow sleeve. The liner stop provides, as a result of the addition of an insert for increased damping of vibrations caused by rotor and combustion dynamics and increased ease of installation. 
         [0025]    Referring now to  FIG. 1 , there is shown a cross section of aspects of a combustion system  2 . The combustion system  2  generally includes a liner  5  and a flow sleeve  6 . The liner  5  and the flow sleeve  6  are positioned relative to each other during assembly by use of a plurality of liner stops  10 . In some embodiments, the combustion system  2  is generally cylindrical, and includes three liner stops  10 , each liner stop  10  being about 120 degrees from the other liner stops  10 , in order to provide for relatively even alignment of the liner  5  and the flow sleeve  6 . One skilled in the art will recognize that any number of liner stops  10  and distribution of the liner stops  10  may be used. 
         [0026]    With reference to  FIG. 2  through  FIG. 4 , the liner stop  10  generally includes three components. A first component, shown in  FIG. 2 , is a female component  20 . A second component, shown in  FIG. 3 , is a male component  30 . A third component, shown in  FIG. 4  is an insert  40 . Each one of these components is now described in greater detail. 
         [0027]    Referring to the embodiment depicted in  FIG. 2 , the female component  20  generally includes a machined cutout or “saddle”  25 . In this embodiment, the saddle  25  includes orthoganally disposed walls. The orthoganally disposed walls include a first sidewall  21 , an orthoganally disposed floor  24 , an orthoganally disposed second sidewall  23  and an orthoganally disposed backwall  22 . In this embodiment, the first sidewall  21  and the second sidewall  23  are generally parallel to each other, and form the saddle therebetween. The female component  20  typically include mounting features  26  for mounting to the flow sleeve  6  (or the liner  5 , as the case may be). In various embodiments, the female component  20  is fabricated from materials that withstand thermal, environmental and mechanical stress during operation of the combustion system  2 . Exemplary materials include, without limitation, a cobalt super-alloy, a nickel super-alloy, an iron super-alloy, stainless steel and carbon steel. 
         [0028]    Referring to the embodiment depicted in  FIG. 3 , the male component  30  includes a design for cooperation with the female component  20 . That is, the male component  30  also includes a plurality of walls adapted for fitting into the saddle  25 . For example, in this embodiment, the male component  30  includes a tab  35  of dimensions that correlate to the saddle  25 . The tab  35  includes a top side  34 , an orthoganally disposed first sidewall  33 , an orthoganally disposed bottom side  37 , and an orthoganally disposed second sidewall  31  (that is also orthoganally disposed to the top side  34 ). The first sidewall  33  and the second sidewall  31  are generally parallel to each other, while the top side  34  and the bottom side  37  are generally parallel to each other. Between the parallel walls ( 31 ,  33 ) and sides ( 34 ,  37 ) lies the material that forms the tab  35 . The tab  35  includes a face  32  that is generally mateable with the backwall  22  of the saddle  25 . The male component  30  typically include mounting features  36  for mounting to the liner  5 . In this example, the mounting features  26  include an arcuate backside to allow the stop  10  to fit tightly against liner welding surface for welding to the liner  5 . In various embodiments, the male component  30  is fabricated from materials that withstand thermal, environmental and mechanical stress during operation of the combustion system  2 . Exemplary materials include, without limitation, a cobalt super-alloy, a nickel super-alloy, an iron super-alloy, stainless steel and carbon steel. 
         [0029]    Referring to the embodiment depicted in  FIG. 4 , the insert  40  includes a design that allows the embodiment to be attached to the male component  30 . In this embodiment, the insert  40  includes a first springwall  41 , an orthoganally disposed bottom member  44 , and an orthoganally disposed second springwall  43 . In this embodiment, the first springwall  41  and the second springwall  43  include a design providing a leaf spring in each springwall  41 ,  43 . The insert  40  is generally formed from a continuous piece of metal suited for use in the insert  40 . Exemplary materials include, without limitation, forms and alloys of hardened steel and various types of composite materials. The insert  40  may include one or more layers of material. In some embodiments, the insert  40  is a double layered leaf spring. In general, the insert  40  is flexible. 
         [0030]    The insert  40  may include a coating, such as a wear coating for wear mitigation. 
         [0031]    During initial assembly of the liner stop  10 , at least one female component  20  is coupled to the flow sleeve  6 . Corresponding male components  30  are coupled to the liner  5 . (Of course, the components  20 ,  30  may be reversed). In exemplary embodiments, the components  20 ,  30  are welded to the respective portion of the combustion system  2 . 
         [0032]    In some embodiments, once the male component  30  is installed, the insert  40  is attached onto the male component  30 . In one embodiment, the insert  40  is attached by welds to the tab  35 . For example, at least one weld may be disposed, along the bottom member  44 . In some other embodiments, the insert  40  may be clamped onto the male component  30  prior to installation of the male component  30 . Reference may be had to  FIG. 5 . 
         [0033]    In  FIG. 5 , the insert  40  is shown as disposed over the male component  30 . 
         [0034]    Once the male component  30  and the female component  20  are installed and ready for assembly of the combustion system  2 , the liner  5  is inserted into the flow sleeve  6 . The male components  30  and the female components  20  are aligned such that progressive insertion of the liner  5  results in the tab  35  being disposed into the saddle  25 . Reference may be had to  FIG. 6 . 
         [0035]    With the presence of the insert  40 , the force needed to install the tab  35  grows progressively in accordance with a spring force provided by each insert  40 . Once installed, the spring force provided by each insert  40  provides retention and alignment of the liner  5  and the flow sleeve  6 . 
         [0036]    Referring now to  FIG. 7 , a method  70  for installing the liner generally calls for installing a first component  71  (one of the male component  30  and the female component  20 ) onto the liner  5 , installing a second component  72  onto the sleeve  6 , attaching the insert  73 , and then aligning and inserting the liner  74 . Of course, one skilled in the art will recognize a variety of limitations may be had, for example, in the performance of these tasks, as well as the use of the various components. Accordingly, this method  70  is merely exemplary and is not limiting of the teachings herein. 
         [0037]    Compensation for wear between the female component  20  and the male component  30  is greatly reduced because vibratory motion between components  20  and  30  is dampened as a result of the insert  40 . That is, the insert  40  absorbs a portion of the vibratory energy, decreases the wear causing relative motion between the female component  20  and the male component  30 . 
         [0038]    Use of the liner stop  10  provides for liner retention in the x-direction and y-direction, as seen in  FIG. 2 . When the male component  30  is seated in the female component  20 , the spring walls  41  and  43  of the insert  40  apply a force on the first and second sidewalls  21  and  23  of the female component  20 . This spring force suspense the male and female components  30  and  20  in position relative to each other in the y-direction with a relatively small amount of motion. In the x-direction, the male and female components  30  and  20  are held in position relative to each other by friction between the spring walls  41  and  43  of the insert  40  and the first and second sidewalls  21  and  23  of the female component  20  imposed by the spring force applied by spring walls  41  and  43 . Movement is limited to the insertion direction (x-direction). The contacting surface area is also beneficial for distributing the vibration and other dynamic forces that are transferred between the flow sleeve  6  and the combustion liner  5 . 
         [0039]    One skilled in the art will recognize that the male component  30  and the female component  20  may include more or fewer surfaces, and that the insert  40  may be designed to cooperate with these other embodiments. Accordingly, the embodiment provided herein is merely exemplary and is not limiting of the teachings herein. 
         [0040]    While the invention has been described with reference to an exemplary embodiment, it will be understood that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.