Abstract:
A sealing arrangement for sealing between a first stage nozzle and a plurality of aft frames includes a first inner seal and a second inner seal which are circumferentially oriented and circumferentially aligned. A side seal is radially disposed between the first inner seal and the second inner seal. The side seal includes a first portion that is axially offset from the first inner seal and the second inner seal and a second portion abutting the first inner seal and the second inner seal. Also disclosed is an aft frame having a forward face and an aft face. The aft frame includes at least one side seal slot that extends along a side portion. A first portion of the side seal slot is axially offset from the aft face. A second portion of the side seal slot is axially and radially offset from the first portion.

Description:
FIELD OF THE TECHNOLOGY 
       [0001]    The subject matter disclosed herein relates to a combustor for a gas turbine. More specifically, the disclosure is directed to a sealing arrangement for the interface of one or more combustor transition ducts with one or more inlets of a first stage nozzle of a gas turbine. 
       BACKGROUND 
       [0002]    Gas turbines typically comprise several interconnected discrete parts. A gas turbine generally includes an inlet section, a compression section, a plurality of combustors, a turbine section, and an exhaust section. The inlet section may include a series of filters, cooling coils, moisture separators, and/or other devices to purify and otherwise condition a working fluid (e.g., air) entering the gas turbine. The working fluid flows downstream from the inlet section to a compressor section where kinetic energy is progressively imparted to the working fluid to produce a compressed working fluid at a highly energized state. The compressed working fluid is mixed with a fuel from a fuel supply to form a combustible mixture within one or more combustors. The combustible mixture is burned to produce combustion gases having a high temperature and pressure. The combustion gases flow through a turbine of a turbine section wherein energy (kinetic and/or thermal) is transferred from the combustion gases to rotor blades, thus causing a shaft to rotate and produce work. For example, the rotation of the turbine shaft may drive the compressor to produce the compressed working fluid. Alternately or in addition, the shaft may connect the turbine to a generator for producing electricity. Exhaust gases from the turbine flow through an exhaust section that connects the turbine to an exhaust stack downstream from the turbine. The exhaust section may include, for example, a heat recovery steam generator for cleaning and extracting additional heat from the exhaust gases prior to release to the environment. 
         [0003]    The combustors of a gas turbine are generally connected to the inlets of a first stage nozzle of the turbine section via transition ducts. Typically, each transition duct has an aft frame downstream of the combustor which connects to an inlet of the turbine section. The aft frame will usually have two arcuate portions which are typically referred to as inner and outer portions, being inner and outer in the radial direction with respect to the centerline axis of the turbine. The inner and outer portions of the aft frame are interconnected by radially extending linear portions, often referred to as side portions. Inner and outer circumferential seals are used to seal between the inner and outer portions of the aft frame and the corresponding inlet of the turbine section. Radially oriented side seals can be disposed between adjacent aft frames to substantially close and seal off the circumferential gaps between the side portion of one aft frame and the next aft frame. 
         [0004]    The radially oriented side seals between circumferentially adjacent aft frames are axially offset (with reference to the turbine axis) from the inner and outer seals between each aft frame and the inlet. Because of this axial offset, gaps remain between the inner and outer seals and the side seals. Gas turbines usually burn hydrocarbon fuels and produce air polluting emissions such as oxides of nitrogen (NOx) and carbon monoxide (CO). Thus, gaps between the inner and outer seals and the side seals may lead to escape of working fluid (e.g., compressed air and/or combustion gases) flowing through the transition duct from the combustor to the first stage nozzle, which can cause lower performance and a shift in the emission of air pollutants. 
       BRIEF DESCRIPTION OF THE TECHNOLOGY 
       [0005]    Aspects and advantages are set forth below in the following description, or may be obvious from the description, or may be learned through practice. 
         [0006]    Improved sealing connections between the various parts of the gas turbine are desired in the art. In particular, gas turbines and associated sealing arrangements which facilitate a reduction or elimination of working fluid lost to the ambient atmosphere and/or emissions escaping to the ambient atmosphere would be advantageous. 
         [0007]    One embodiment of the present disclosure is directed to a sealing arrangement for sealing between a first stage nozzle and a plurality of aft frames. The arrangement includes a first inner seal which is circumferentially oriented. The first inner seal comprises a forward surface and an aft surface. The arrangement also includes a second inner seal adjacent to the first inner seal. The second inner seal comprises a forward surface and an aft surface. The second inner seal is circumferentially oriented and circumferentially aligned with the first inner seal. The first inner seal and the second inner seal are axially aligned. A side seal is radially disposed between the first inner seal and the second inner seal. The side seal includes a first portion that is axially offset from the first inner seal and the second inner seal and a second portion abutting the first inner seal and the second inner seal. The first portion of the side seal is radially offset from the first inner seal and the second inner seal. 
         [0008]    Another embodiment of the present disclosure is directed to a sealing arrangement wherein one or more of the first inner seal and the second inner seal comprises a frame and a guide tab. The one or more guide tabs abuts a forward surface of the second portion of the side seal and biases the side seal axially towards the forward surface of the first inner seal and the forward surface of the second inner seal such that an aft surface of the second portion of the side seal engages with the forward surface of the first inner seal and the forward surface of the second inner seal. 
         [0009]    Another embodiment of the present disclosure is directed to a sealing arrangement wherein the first portion of the side seal is parallel to the first inner seal and the second inner seal. 
         [0010]    Another embodiment of the present disclosure is directed to a sealing arrangement wherein the second portion of the side seal is oblique to the first inner seal and the second inner seal. 
         [0011]    Another embodiment of the present disclosure is directed to a sealing arrangement wherein the side seal further comprises an intermediate portion between the first portion and the second portion and the intermediate portion of the side seal is oblique to the first inner seal and the second inner seal. 
         [0012]    Another embodiment of the present disclosure is directed to a sealing arrangement wherein the side seal comprises a rigid material and said first, second, and intermediate portions are pre-formed. 
         [0013]    Another embodiment of the present disclosure is directed to a sealing arrangement wherein one or more of the first inner seal and the second inner seal comprises a frame and a guide tab, and the side seal is sufficiently flexible to form the first, second, and intermediate portions upon interacting with the guide tab without undergoing plastic deformation. 
         [0014]    Another embodiment of the present disclosure is directed to an aft frame for a gas turbine combustor transition duct. The aft frame includes a forward face, an aft face, an inner portion radially separated from an outer portion, and a pair of opposing side portions that extend radially between the inner portion and the outer portion. At least one of the side portions defines a side seal slot that extends along the side portion between the inner portion and the outer portion of the aft frame. A first portion of the side seal slot is axially offset from the aft face. A second portion of the side seal slot adjacent to one of the inner portion or the outer portion is axially and radially offset from the first portion. 
         [0015]    Another embodiment of the present disclosure is directed to an aft frame further comprising an inner seal disposed on the inner portion and an outer seal disposed on the outer portion; wherein the second portion of the side seal slot is defined by a tab on one of the inner seal or the outer seal. 
         [0016]    Another embodiment of the present disclosure is directed to an aft frame wherein the side seal slot comprises a protrusion which extends axially toward the aft face and defines the second portion of the side seal slot. 
         [0017]    Another embodiment of the present disclosure is directed to an aft frame wherein the first portion of the side seal slot is oblique to the aft face. 
         [0018]    Another embodiment of the present disclosure is directed to an aft frame wherein the first portion of the side seal slot is parallel to the aft face. 
         [0019]    Another embodiment of the present disclosure is directed to an aft frame wherein the second portion of the side seal slot is parallel to the aft face and the side seal slot further comprises an intermediate portion between the first portion of the side seal slot and the second portion of the side seal slot. The intermediate portion of the side seal slot is oblique to the aft face. 
         [0020]    Another embodiment of the present disclosure is directed to an aft frame wherein the side seal slot further comprises a third portion adjacent to the other of the inner portion and the outer portion, which is axially and radially offset from the first portion. 
         [0021]    Another embodiment is directed to a gas turbine. The gas turbine includes a compressor, a turbine and a combustor disposed downstream from the compressor and upstream from the turbine. The combustor includes an upstream end, a downstream end, and a transition duct which defines a flow path from the compressor to the turbine. Also included is an aft frame that circumferentially surrounds the downstream end, the aft frame having a forward face and an aft face. The aft frame further comprises an inner portion radially separated from an outer portion and a pair of opposing side portions that extend radially between the inner portion and the outer portion. At least one of the side portions defines a side seal slot that extends along said side portion between the inner portion and the outer portion of the aft frame. A first portion of the side seal slot is axially offset from the aft face of the aft frame and a second portion of the side seal slot adjacent one of the inner portion of the aft frame or the outer portion of the aft frame is axially and radially offset from the first portion. 
         [0022]    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 
         [0023]    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: 
           [0024]      FIG. 1  illustrates a schematic diagram of an exemplary gas turbine that may incorporate various embodiments of the present disclosure; 
           [0025]      FIG. 2  illustrates a section view of a transition duct between a combustor and an inlet according to at least one embodiment; 
           [0026]      FIG. 3  is a perspective view of circumferentially adjacent aft frames; 
           [0027]      FIG. 4  is a side view of an aft frame with an inner seal disposed thereon; 
           [0028]      FIG. 5  is a perspective view of an aft frame with inner and outer seals disposed thereon; 
           [0029]      FIG. 6  is a perspective view of an aft frame and seals disposed thereon; 
           [0030]      FIG. 7  is an enlarged view of circumferentially adjacent aft frames; 
           [0031]      FIG. 8  is an enlarged view in a radial direction of circumferentially adjacent aft frames with circumferential and radial seals; 
           [0032]      FIG. 9  is an enlarged side view of a side seal slot near a corner of an aft frame; 
           [0033]      FIG. 10  is an enlarged view in a radial direction of a side seal slot near a corner of an aft frame; 
           [0034]      FIG. 11  is an enlarged view of a side seal slot near a corner of an aft frame; and 
           [0035]      FIG. 12  is an enlarged side view of a side seal slot near a corner of an aft frame. 
       
    
    
     DETAILED DESCRIPTION 
       [0036]    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. 
         [0037]    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” (or “forward”) and “downstream” (or “aft”) 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, the term “axially” refers to the relative direction that is substantially parallel and/or coaxially aligned to an axial centerline of a particular component and the term “circumferentially” refers to the relative direction that extends around the axial centerline of a particular component. 
         [0038]    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. 
         [0039]    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 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. 
         [0040]    Referring now to the drawings,  FIG. 1  illustrates a schematic diagram of an exemplary gas turbine  10  that may incorporate various embodiments of the present invention. As shown, the gas turbine  10  generally includes an inlet section  12 , 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 . 
         [0041]    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 . 
         [0042]    As illustrated in  FIG. 2 , the combustor  16  may be connected to the turbine  18  via a transition duct  32  including an aft frame  100 . The transition duct  32  defines a flow path P. Also shown in  FIG. 2  is the central axis A of turbine  18 , which defines an axial direction that is substantially parallel to and/or coaxially aligned with axis A, a radial direction perpendicular to axis A, and a circumferential direction extending around axis A. 
         [0043]    Referring now to  FIG. 3 , a pair of circumferentially arranged transition ducts  32  are illustrated, each having an aft frame  100  that surrounds its respective downstream end. As illustrated in  FIG. 3 , in some embodiments, the aft frame may have an inner portion  102  and an outer portion  104 , with a pair of opposing side portions  106  and  108  that extend radially between the inner and the outer portions  102  and  104 . Also illustrated in  FIG. 3  is an inner seal  200  and an outer seal  300  respectively disposed on the inner portion  102  and outer portion  104  of each aft frame  100 . In the exemplary embodiment illustrated in  FIG. 3 , inner seal  200  and outer seal  300  are circumferentially oriented, each inner seal  200  is circumferentially aligned with the other inner seal  200  on the adjacent aft frame  100 , and each outer seal  300  is circumferentially aligned with the other outer seal  300  on the adjacent aft frame  100 . As illustrated in  FIGS. 3 through 5 , the aft frame  100  may include a forward face  110  and an aft face  112 . The intersections of side portions  106  and  108  with inner portion  102  define inner corners  120  and  122 , and the intersections of side portions  106  and  108  with outer portion  104  define outer corners  130  and  132 . A radially oriented side seal  400  is disposed between the aft frames  100  and the inner and outer seals  200  and  300  disposed thereon. In the description herein, certain features of the aft frame  100  and seals,  200 ,  300 , and  400  will be described with reference to one or both inner corners  120  and  122 , nonetheless, it should recognized by one of ordinary skill in the art that such features can be associated with any or all of inner corners  120 ,  122  or outer corners  130 ,  132 . 
         [0044]    As  FIG. 4  illustrates, some embodiments may have a frame  210  and guide tab  212  on inner seal  200 , and one or both of inner seal  200  and outer seal  300  may have a similar frame and a guide tab thereon. As illustrated in  FIGS. 5 and 9 , in such embodiments the guide tab  212  biases the side seal  400  axially towards aft frame  100  and/or forward surface  202  of inner seal  200 . 
         [0045]    As shown in  FIG. 4 , in some embodiments the aft frame  100  may have a side seal slot  150 . Although the side seal slot  150  will be generally described with reference to one side portion  106  the for clarity, it should recognized by one of ordinary skill in the art that either or both of the opposing side portions  106  and  108  of the aft frame  100  may include a side seal slot  150  as described herein. The side seal slot  150  may include a first portion  152  axially offset from the aft face  112  and a second portion  156  axially and radially offset from the first portion  152 . In some embodiments, the side seal slot  150  may also include an intermediate portion  154 . As illustrated in, e.g.,  FIG. 5 , in some embodiments side seal slot  150  is configured for receiving side seal  400  such that a first portion  406  of side seal  400  is radially and axially offset from the inner and outer seals  200  and  300 , and for example as illustrated in  FIG. 6 , second portion  410  of side seal  400  is radially and axially offset from the first portion  406  and abuts the inner seal  200 . 
         [0046]    As illustrated in  FIG. 5 , in some embodiments, the side seal  400  may have a first portion  406  that is oblique to the inner seal  200 . As illustrated in  FIG. 6 , in some embodiments, the second portion  410  may be substantially parallel to the inner seal  200 , and there may be an intermediate portion  408  between the first portion  406  and the second portion  410  which is oblique to the inner seal  200 . 
         [0047]    As illustrated in  FIG. 7 , an aft surface  404  of side seal  400  abuts forward surfaces  202  of inner seals  200 . As can be seen in  FIGS. 6-8 and 12 , the aft surface  404  of side seal  400  partially overlaps the inner seals  200  in both the radial and circumferentail directions. As illustrated in  FIG. 8 , a tab  212  is provided on one inner seal  200  which abuts forward surface  402  and biases the side seal  400  axially toward the inner seal  200 . Tab  212  could also be provided on both inner seals  200  or one or both outer seals  300  separately or in combination with the tab  212  illustrated in  FIG. 8 . 
         [0048]    As illustrated in  FIGS. 9 and 12 , some embodiments may include a side seal slot  150  having a first portion  152  parallel to the aft face  112 . It will be recognized by one of ordinary skill in the art that side seal  400  is generally congruent to the side seal slot  150 , e.g., in embodiments where first portion  152  of side seal slot  150  is parallel to aft face  112 , a side seal  400  may also be provided, and if so the side seal  400  would also have its first portion  406  parallel to aft face  112 . 
         [0049]    As illustrated in  FIGS. 4 and 9 , some embodiments may include a second portion  156  of the side seal slot  150  that is parallel to the aft face  112  and an intermediate portion  154  that is oblique thereto. Further, in such embodiments, e.g., as illustrated in  FIGS. 5 and 6 , the side seal  400  will have a second portion  410  parallel to the inner seal  200  and an intermediate portion  408  that is oblique thereto. In other embodiments, for example as illustrated in  FIG. 12 , the second portion  410  can be oblique to the aft face  112 . 
         [0050]    As illustrated in  FIG. 10 , in some embodiments first portion  152  of the side seal slot  150  may be oblique to the aft face  112 . As illustrated in  FIG. 11 , in some embodiments, side seal slot  150  may have a second portion  156  substantially parallel to the aft face  112 , and there may be an intermediate portion  154  between the first portion  152  and the second portion  156  which is oblique to the aft face  112 . As illustrated in  FIG. 12  , in some embodiments, first portion  152  of side seal slot  150  may be parallel to the aft face  112 . The second portion may be defined by a protrusion  158 , as illustrated in  FIG. 12 , or guide tab  212 , as illustrated in  FIG. 9 . As illustrated in  FIG. 12 , in some embodiments, side seal  400  may have a first portion  406  that is parallel to the inner seal  200  and a second portion  410  may be oblique to the inner seal  200 . 
         [0051]    In any of the foregoing embodiments, the side seal  400  may be composed of a relatively rigid material with the first ( 406 ), second ( 410 ), and/or intermediate ( 408 ) portions pre-formed, or may be sufficiently flexible to form said first, second, and/or intermediate portions upon insertion into the side seal slot  150  (e.g., interacting with the guide tab  212  or protrusion  158 ) without undergoing plastic deformation. 
         [0052]    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. For example, the exemplary description in the foregoing pertaining to the inner corners of the aft frame can also be implemented at one or more outer corners of the aft frame as well as or instead of the inner corner(s). 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.