Patent Publication Number: US-8118549-B2

Title: Gas turbine transition duct apparatus

Description:
FIELD OF THE INVENTION 
     The present invention is directed to a gas turbine transition duct having a collar with at least one notched section, a seal apparatus for sealing a relief opening defined between opposing first and second transition ducts and a gas turbine transition duct apparatus comprising first and second transition ducts and a seal apparatus. 
     BACKGROUND OF THE INVENTION 
     A conventional combustible gas turbine engine includes a compressor, a combustor, including a plurality of combustor units, and a turbine. The compressor compresses ambient air. The combustor units combine the compressed air with a fuel and ignite the mixture creating combustion products defining a working gas. The working gases are routed to the turbine inside a plurality of transition ducts. Within the turbine are a series of rows of stationary vanes and rotating blades. The rotating blades are coupled to a shaft and disc assembly. As the working gases expand through the turbine, the working gases cause the blades, and therefore the disc assembly, to rotate. 
     Each transition duct may comprise a generally tubular main body and a collar coupled to an exit of the main body. The transition ducts may be positioned adjacent to one another. The ducts may include brush seals held via holders coupled to the collars, metallic seal strips trapped in slots within the collars or labyrinth seals welded to or formed as part of the collars so as to prevent hot gases from passes between adjacent transition ducts. 
     The working gases produced by the combustor units are hot and under a pulsating pressure. The transition ducts are exposed to these high temperature gases and pulsating pressures, and vibrations can cause deflections in various locations of the tubular main bodies and collars. The transition duct is attached to the turbine engine at two points. The first attachment is at the top of the transition duct collar and an internal casing ring. The second attachment is at the inlet ring of the transition duct and the engine case pressure shell. Due the nature of holding a component in a dynamic flow condition with temperature gradients, stress failures may occur, for example, in corner portions of the tubular main bodies. 
     SUMMARY OF THE INVENTION 
     In accordance with a first aspect of the present invention, a gas turbine transition duct is provided comprising a generally tubular main body having first and second ends, the first end being adapted to be positioned adjacent to a combustor unit and the second end being adapted to be positioned adjacent to a turbine and a collar coupled to the main body second end. The collar may have upper, lower and side portions. At least one of the side portions may be provided with a notched section. 
     The notched section may be generally centered along the one side portion. 
     The notched section may extend between about 30% and about 70% of a length of the one side portion. 
     In accordance with a second aspect of the present invention, a gas turbine transition duct apparatus is provided comprising a first turbine transition duct, a second turbine transition duct, and seal apparatus. The first turbine transition duct may comprise a first generally tubular main body having first and second ends and a first collar coupled to the main body second end. The first collar may have a first upper portion, a first lower portion and first side portions. At least one of the first side portions may be provided with a first notched section. The second turbine transition duct may comprise a second generally tubular main body having third and fourth ends and a second collar coupled to the main body fourth end. The second collar may have a second upper portion, a second lower portion and second side portions. At least one of the second side portions may be provided with a second notched section. The one first side portion may be positioned adjacent to the one second side portion such that the first and second notched sections are located adjacent to one another. The first and second notched sections may define a relief opening between them. The seal apparatus may comprise a plug associated with the relief opening. 
     The seal apparatus may comprise a plug plate comprising the plug and support structure integral with the plug, wherein the support structure comprises first and second end portions. 
     The one first side portion may further comprise upper and lower first recessed sections and the one second side portion may further comprise upper and lower second recessed sections. The support structure first end portion may be received in the upper first and second recessed sections and the support structure second end portion may be received in the lower first and second recessed sections. 
     The seal apparatus may further comprise a side seal device including a support member comprising a main body and first and second locking tabs. The support member may be adapted to be positioned adjacent to and engage the plug plate. 
     The one side portion may further comprise first and second slotted sections including respectively first and second slots and the one second side portion may further comprise third and fourth slotted sections including respectively third and fourth slots. The first locking tab may be received in the first and third slots and the second locking tab may be received in the second and fourth slots. 
     The side seal device may further comprise spring structure coupled to the support member and in engagement with first and second landings on the first and second collars and the first and second generally tubular main bodies so as to retain the support member in position against the plug plate. 
     The spring structure may comprise first and second spring clips. Each of the first and second spring clips may comprise slots. 
     In accordance with a third embodiment of the present invention, a seal apparatus is provided and adapted to seal a relief opening defined between opposing first and second transition ducts. The seal apparatus may comprise a plug plate and a side seal device. The plug plate may comprise a plug and an integral support structure. The plug may be positioned within the relief opening. The side seal device may include a support member and spring structure. The support member may be adapted to be positioned adjacent to and engage the plug plate. The spring structure may be associated with the support member and adapted to engage the first and second transition ducts to maintain the support member in engagement with the plug plate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a plurality of gas turbine transition duct apparatuses constructed in accordance with the present invention; 
         FIG. 2  is an exploded view of a portion of a gas turbine transition duct apparatus; 
         FIG. 3  is a view of a portion of a gas turbine transition duct apparatus; 
         FIG. 4  is a view taken along view line  4 - 4  in  FIG. 3 ; 
         FIG. 5  is a view taken along view line  5 - 5  in  FIG. 3 ; 
         FIG. 6  is a view taken along view line  6 - 6  in  FIG. 3 ; 
         FIG. 7  is a view taken along view line  7 - 7  in  FIG. 3 ; and 
         FIGS. 8 and 9  are perspective views of a side seal device of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following detailed description of the preferred embodiment, reference is made to the accompanying drawings that form a part hereof, and which is shown by way of illustration, and not by way of limitation, a specific preferred embodiment in which the invention may be utilized and that changes may be made without departing from the spirit and scope of the present invention. 
     A conventional combustible gas turbine engine (not shown) includes a compressor (not shown), a combustor (not shown), including a plurality of combustor units (not shown), and a turbine (not shown). The compressor compresses ambient air. The combustor units combine the compressed air with a fuel and ignite the mixture creating combustion products defining a working gas. The working gases are routed from the combustor units to the turbine inside a plurality of transition ducts  10 , see  FIGS. 1-3 . The working gases expand in the turbine and cause blades coupled to a shaft and disc assembly to rotate. 
     In accordance with the present invention, a plurality of gas turbine transition duct apparatuses  20  are provided, each comprising an adjacent pair  30  of the transition ducts  10  and a seal apparatus  40 . Each of the gas turbine transition duct apparatuses  20  may be constructed in the same manner. Hence, only a single gas turbine transition duct apparatus, labeled  20 A in the drawings, will be described in detail herein. 
     The gas turbine transition duct apparatus  20 A comprises an adjacent transition duct pair  30 A including a first transition duct  10 A and a second transition duct  10 B (only the second transition duct  10 B is shown in  FIG. 2 ). The gas turbine transition duct apparatus  20 A further comprises a seal apparatus  40 A. 
     The first turbine transition duct  10 A comprises a first generally tubular main body  100  having first and second ends  102  and  104  and a first collar  106  coupled to the main body second end  104 . The first collar  106  may be formed integrally with the first main body  100  or as a separate element which is welded to the first main body  100 . The first collar  106  comprises a first upper portion  106 A, a first lower portion  106 B and first and second side portions  106 C and  106 D. The first side portion  106 C is provided with a first notched section  206 C and the second side portion  106 D is provided with a second notched section  206 D. The first notched section  206 C is generally centered along the first side portion  106 C and may extend between about 30% and 70% and, preferably, about 50% of the length of the first side portion  106 C. The second notched section  206 D is generally centered along the second side portion  106 D and may extend between about 30% and 70% and, preferably, about 50% of the length of the second side portion  106 D. The first tubular main body  100  and the first collar  106  may be formed from a superalloy such as Inconel 617. 
     The second turbine transition duct  10 B comprises a second generally tubular main body  110  having third and fourth ends  112  and  114  and a second collar  116  coupled to the main body fourth end  114 . The second collar  116  may be formed integrally with the second main body  110  or as a separate element which is welded to the second main body  110 . The second collar  116  comprises a second upper portion  116 A, a second lower portion  116 B and third and fourth side portions  116 C and  116 D. The third side portion  116 C is provided with a third notched section  216 C and the fourth side portion  116 D is provided with a fourth notched section  216 D, see  FIGS. 1 and 2 . The third notched section  216 C is generally centered along the third side portion  116 C and may extend between about 30% and 70% and, preferably, about 50% of the length of the third side portion  116 C. The fourth notched section  216 D is generally centered along the fourth side portion  116 D and may extend between about 30% and 70% and, preferably, about 50% of the length of the fourth side portion  116 C. The second tubular main body  110  and the second collar  116  may be formed from a superalloy such as Inconel 617. 
     The first collar second side portion  106 D is located next to the second collar third side portion  116 C, see  FIGS. 1 and 3 , such that the second and third notched sections  206 D and  216 C are located adjacent to one another. The second and third notched sections  206 D and  216 C define a relief opening  300  between them, see  FIGS. 1 and 3 . The second and third notched sections  206 D and  216 C allow the first and second transition ducts  10 A and  10 B to expand and contract during operation of the gas turbine engine so as to reduce the likelihood that stress failures may occur, for example, in corner portions of the tubular main bodies  100  and  110 . 
     The seal apparatus  40 A comprises, in the illustrated embodiment, a plug plate  402  comprising a plug  404  and a support structure  406  integral with the plug  404 , see  FIGS. 2 and 6 . The plug plate  402  may be formed from a superalloy, such as Inconel 617 or Hanyes 230, an oxide ceramic matrix composite or a non-oxide ceramic matrix composite. The plug  404  has, in the illustrated embodiment, a generally oval shape, which shape substantially corresponds to the shape of the relief opening  300 , but is sized so as to be slightly smaller than the relief opening  300 . For example, the plug  404  may have a width W P  of about 26 mm, while the relief opening  300  may have width W RO  of about 32 mm, see  FIG. 3 . Hence, there is about a 3 mm gap G between side edges  405 A and  405 B of the plug  404  and the second and third notched sections  206 D and  216 C defining the relief opening  300  so as to allow the second and third side portions  106 D and  116 C sufficient room to expand during operation of the gas turbine engine without contacting/damaging the plug  404 . While not illustrated in the drawings, it is contemplated that the plug  404  may include cooling holes extending completely therethrough. 
     The support structure  406  has, in the illustrated embodiment, a width W SS  less than the width W P  of the plug  404 , see  FIG. 6 . Further, the support structure  406  comprises first and second end portions  406 A and  406 B, which extend beyond ends  404 A and  404 B of the plug  404 , see  FIG. 2 . 
     In the illustrated embodiment, the second side portion  106 D further comprises upper and lower second recessed sections (only the upper second recessed section  406 D is illustrated, see  FIG. 5 ). The third side portion  116 C further comprise upper and lower third recessed sections  416 C and  516 C, respectively, see  FIGS. 5 and 7 . The first end portion  406 A of the support structure  406  is axially received in the upper second and third recessed sections  406 D and  416 C, while the second end portion  406 B of the support structure  406  is axially received in the lower second and third recessed sections so as to accurately position the plug  404  axially, radially and circumferentially relative to the relief opening  300 . When the plug  404  is properly positioned relative to the relief opening  300 , the plug  404  functions to substantially block compressed air, generated by the compressor, from passing through the relief opening  300 . 
     In the illustrated embodiment, the seal apparatus  40 A further comprises a side seal device  500  including a support member  510  comprising a main body  512 , first and second locking tabs  514  and  516  and a support rib  518 , see  FIGS. 5 ,  8  and  9 . The main body  512 , the first and second locking tabs  514  and  516  and the support rib  518  may be integrally formed from Inconel 617 or Inconel 718. As will be discussed further below, a front side  512 A of the main body  512  is adapted to engage the plug plate support structure  406  so as to maintain the plug plate  402  in proper position axially relative to the first and second collars  106  and  116 , see  FIG. 5 . 
     The side seal device  500  further comprises a spring structure  520  coupled to the support member  510 . The spring structure  520  comprises, in the illustrated embodiment, first and second spring clips  522  and  524 , which may be formed from Inconel 617 or Inconel 718. The spring clips  522  and  524  are coupled to opposing sides of the main rib  518  of the side seal device support member  510  via welding or brazing, wherein welding or brazing material  618  is illustrated in  FIGS. 5 and 8 . Each of the first and second spring clips  522  and  524  may comprise slots  522 A and  524 B. 
     In the illustrated embodiment, the second side portion  106 D further comprises upper and lower second slotted sections including respectively upper and lower second slots (only the upper second slot  606 D is illustrated, see  FIG. 4 ). The third side portion  116 C further comprise upper and lower third slotted sections including respectively upper and lower third slots  616 C and  716 C, respectively, see  FIGS. 4 and 7 . The first locking tab  514  is received in the upper second and third slots  606 D and  616 C, while the second locking tab  516  is received in the lower second and third slots. 
     During assembly of the seal apparatus  40 A to the first and second transition ducts  10 A and  10 B, the plug plate  402  is first axially moved toward the first and second collars  106  and  116  such that the first end portion  406 A of the support structure  406  is received in the upper second and third recessed sections  406 D and  416 C of the second and third side portions  106 D and  116 C, while the second end portion  406 B of the support structure  406  is axially received in the lower second and third recessed sections of the second and third side portions  106 D and  116 C. Thereafter, the side seal device  500  is radially positioned relative to the first and second collars  106  and  116  such that the first locking tab  514  is inserted into the upper second and third slots  606 D and  616 C, while the second locking tab  516  is inserted into the lower second and third slots of the of the second and third side portions  106 D and  116 C. Once the side seal device  500  is properly inserted, the front side  512 A of the main body  512  engages the plug plate support structure  406  so as to maintain the plug plate  402  in proper position relative to the first and second collars  106  and  116 , see  FIGS. 5 and 7 . Further, the spring clips  522  and  524  engage first and second landings  708  and  718 , see  FIG. 5 , on the first and second collars  106  and  116  and the first and second generally tubular main bodies  100  and  110  so as to retain the support member  510  in position against the plug plate  402 , see  FIG. 5 . 
     It is also noted that the slots  522 A and  524 B provided in the spring clips  522  and  524  allow the spring clips  522  and  524  to expand and contract as the first and second transition ducts  10 A and  10 B expand and contract during operation of the gas turbine engine. The slots  522 A and  524 B also define metering slots through which compressed air from the compressor is able to pass through the side seal device  500  and the gaps G between the side edges  405 A and  405 B of the plug  404  and the second and third notched sections  206 D and  216 C. The compressed air passing through the gaps G acts to cool outer surfaces of the upper, lower and side portions of the collars  106 ,  116 , which outer surfaces are located downstream from the tubular main bodies  100 ,  110  as well as the entire region downstream from the collars  106 ,  116  and prior to the turbine. 
     An inner seal ring  800  is provided for engaging the second locking tab  516  so as to limit axial movement of the second locking tab  516 , see  FIG. 7 . A plurality of restraining tabs  802  are coupled via bolts  804 A and nuts  804 B to the collars  106  and  116  so as to limit axial movement of the inner seal ring  800 . 
     An outer seal ring  810  is provided for engaging the first locking tab  514  so as to limit radial movement of the first locking tab  514 , see  FIG. 7 . A support structure  812  is provided for limiting radial movement of the seal ring  810 . 
     While a particular embodiment of the present invention has been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.