Abstract:
A first aspect of the invention provides an axially faced seal system for a radial tip of a turbine component, the system comprising: a stationary turbine component; a rotating turbine component; and a seal ring mounted to the stationary turbine component, the seal ring extending axially to the rotating turbine component and engaging the rotating turbine component on a side surface, wherein the side surface of the rotating turbine component is on a continuous, rotating mating ring having a 360 degree arc.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Embodiments of the invention relate generally to turbine components for power generation applications, and, more specifically, to axially faced seal systems configured to radially seal rotating and stationary turbine components (e.g., turbine buckets, turbine nozzles, etc.). 
         [0002]    Some power plant systems (e.g., certain nuclear, simple cycle, and combined cycle power plant systems) employ turbines in their design and operation. Some of these turbines include turbine components with airfoil shaped sections (e.g., turbine blades such as buckets and nozzles) which during operation are exposed to fluid flows, portions of which may leak radially over the tips of these components (e.g., between a blade tip and stator of the turbine, through the blade clearance gap, etc.), impacting fluid flow and reducing turbine efficiency. Some power plant systems include radial sealing systems disposed on the stator and/or turbine components which are configured to reduce this leakage by radially sealing this gap (e.g., by reducing and/or eliminating the gap between the component tip and the stator). However, the radial length of these turbine components may be susceptible to thermal expansion and rotor excursions and, as a result, radial steampath rubs may occur between these radial sealing systems and turbine components, resulting in component wear and/or damage. Besides, these radial seal systems may have pressure and/or temperature limitations which limit system applications, design considerations, and/or overall performance of the power generation system. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0003]    A first aspect of the invention provides an axially faced seal system for a radial tip of a turbine component, the system comprising: a stationary turbine component; a rotating turbine component; and a seal ring mounted to the stationary turbine component, the seal ring extending axially to the rotating turbine component and engaging the rotating turbine component on a side surface, wherein the side surface of the rotating turbine component is on a continuous, rotating mating ring having a 360 degree arc. 
         [0004]    A second aspect of the invention provides a rotor comprising: at least one rotating turbine component having a plurality of blades and a radial-extending mating ring attached to the plurality of blades; and at least one axially faced seal system forming a face seal with the at least one rotating turbine component, the at least one axially faced seal system comprising a seal ring extending axially to the at least one rotating turbine component and sealing against a side surface of the mating ring, wherein the mating ring forms a 360 degree continuous arc. 
         [0005]    A third aspect of the invention provides a turbine comprising: at least one rotating turbine component having a plurality of blades attached to a rotor; a ring element next to the plurality of blades; at least one stationary turbine component having a radial tip; and at least one axially faced seal system forming a face seal with the at least one rotating turbine component and the at least one stationary turbine component, the at least one axially faced seal system comprising: a sealing ring mounted to the radial tip of the at least one stationary turbine component, extending axially to the rotating turbine component and sealing against a side surface of the ring element, wherein the rotating ring element is a 360 degree arc. 
         [0006]    These and other aspects, advantages and salient features of the invention will become apparent from the following detailed description, which, when taken in conjunction with the annexed drawings, where like parts are designated by like reference characters throughout the drawings, disclose embodiments of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The above and other aspects, features and advantages of the invention will be better understood by reading the following more particular description of the invention in conjunction with the accompanying drawings. 
           [0008]      FIG. 1  shows a three-dimensional partial cut-away perspective view of a portion of a turbine according to an embodiment of the invention. 
           [0009]      FIG. 2  shows a turbine component in accordance with embodiments of the invention. 
           [0010]      FIG. 3  shows a stationary or rotating turbine component formed as one body is shown with an inner seal surface and an outer seal surface in accordance with one embodiment of the invention. 
           [0011]      FIG. 4  shows a portion of a set of stationary or rotating turbine components including a set of axially faced seal systems in accordance with one embodiment of the invention. 
           [0012]      FIG. 5  shows a two-dimensional graphical representation of a seal system connected to a stationary or rotating turbine component in accordance with one embodiment of the invention. 
           [0013]      FIG. 6  shows a portion of a turbine including an axially faced seal system connected to a set of stationary or rotating turbine components in accordance with one embodiment of the invention. 
           [0014]      FIG. 7  shows a two-dimensional graphical representation respectively of axially faced seal system connected to a stationary or rotating turbine component in accordance with one embodiment of the invention. 
           [0015]      FIG. 8  shows a perspective view respectively of axially faced seal system connected to a stationary or rotating turbine component in accordance with one embodiment of the invention. 
           [0016]      FIG. 9  shows a schematic block diagram illustrating portions of a combined cycle power plant system according to embodiments of the invention. 
           [0017]      FIG. 10  shows a schematic block diagram illustrating portions of a single-shaft combined cycle power plant system according to embodiments of the invention. 
       
    
    
       [0018]    It is noted that the drawings of the invention are not necessarily to scale. The drawings are intended to depict only typical aspects of the invention, and therefore should not be considered as limiting the scope of the invention. It is understood that elements similarly numbered between the FIGURES may be substantially similar as described with reference to one another. Further, in embodiments shown and described with reference to  FIGS. 1-10 , like numbering may represent like elements. Redundant explanation of these elements has been omitted for clarity. Finally, it is understood that the components of  FIGS. 1-10  and their accompanying descriptions may be applied to any embodiment described herein. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    Aspects of the invention provide for seal systems shaped to axially seal radial tips of turbine components. These axially faced seal systems reduce seal clearances between components and improve turbine and/or power generation system efficiency and operation. 
         [0020]    Turning to the drawings, embodiments of systems and devices are shown, which are configured to reduce tip leakage losses in a turbine by providing an axially faced seal system disposed proximate to a radial extent/tip of a turbine component. Each of the components in the drawings may be conventionally connected, e.g., via a common conduit or other known device or apparatus as is indicated in  FIGS. 1-10 . Referring to the drawings,  FIG. 1  shows a perspective partial cut-away illustration of a steam turbine  10 . Turbine  10  includes a rotor  12  that includes a rotating shaft  14  and a plurality of rotor wheels  18  spaced along an axial length A of rotating shaft  14 . A plurality of rotating blades  20  are mechanically coupled to each rotor wheel  18 . More specifically, blades  20  are arranged in rows that extend circumferentially around each rotor wheel  18 . A plurality of stationary vanes  22  extend circumferentially around shaft  14 , and the vanes are axially positioned between adjacent rows of blades  20 . Stationary vanes  22  cooperate with blades  20  to form a stage and to define a portion of a flow path through turbine  10 . 
         [0021]    In operation, fluid such as steam  24  enters an inlet  26  of turbine  10  and is channeled through stationary vanes  22 . Vanes  22  direct steam  24  against blades  20 . Steam  24  passes through the remaining stages imparting a force on blades  20  causing shaft  14  to rotate. At least one end of turbine  10  may extend axially away from rotating shaft  12  and may be attached to a load or machinery (not shown) such as, but not limited to, a generator, and/or another turbine. 
         [0022]    In one embodiment, turbine  10  may include five stages. The five stages are referred to as L 0 , L 1 , L 2 , L 3  and L 4 . Stage L 4  is the first stage and is the smallest (in a radial direction, r) of the five stages. Stage L 3  is the second stage and is the next stage in an axial direction. Stage L 2  is the third stage and is shown in the middle of the five stages. Stage L 1  is the fourth and next-to-last stage. Stage L 0  is the last stage and is the largest (in a radial direction). It is to be understood that five stages are shown as one example only, and each turbine may have more or fewer than five stages. Also, as will be described herein, the teachings of the invention do not require a multiple stage turbine. 
         [0023]    Turning to  FIG. 2 , a schematic cut-away view of a portion of a turbine  100  is shown including a set of first axially faced seal systems  110  and a set of second axially faced seal systems  170  disposed on radial tips of a set of rotating turbine components  130  (e.g., a turbine blade, a bucket, a blade, etc.) and a set of stationary turbine components  120  (e.g., a vane, a nozzle, etc.) in accordance with embodiments of the invention. Stationary turbine components  120  may be connected to a stator  140  of turbine  100  and may extend within a working fluid passage  107 . Rotating turbine components  130  may be connected to a rotor  150  of turbine  100  and may rotate through working fluid passage  107  and between set of stationary turbine components  120 . In one embodiment, a set of first axially faced seal systems  110  may be connected to a bucket tip (or bucket shroud)  132  of rotating turbine components  130  and may be mounted to stator  140 . First axially faced seal system  110  may include a first seal ring  180  which is mounted to stator  140  via a first secondary seal  186  in a seal housing  142  and extends axially toward a mating ring  135  on the bucket tip  132  so as to form a face seal at sealing face  138 . Seal ring  180  may include a first anti-rotation element  184  and a stop flange  188 , which may extend radially toward stator  140  to limit movement of seal ring  180 . Seal ring  180  and secondary seal  186  may be segmented rings, i.e., composed of separate arcuate members which, together, form a 360° arc. Mating ring  135  forms a 360° arc to provide a substantially flat, smooth sealing face  138 , while bucket tip (or shroud)  132  may be an integral part of individual rotating turbine component  130  and therefore be segmented. In one embodiment, seal housing  142  may define a channel  144  shaped to accommodate secondary seal  186 . Seal housing  142  can be an integral part of stator  140  or a separate component assembled onto stator  140 . 
         [0024]    In one embodiment, a set of second axially faced seal systems  170  may be connected to a root ring element  152  of rotating turbine components, as shown in  FIG. 2 . Second axially faced seal system  170  may include a second seal ring  190  which is mounted to a stationary tip cover  122  and extends axially toward sealing surface  138  on root ring element  152 . Seal ring  190  may include a second secondary seal  194  and a second anti-rotation element  196  which may extend radially to interlock with stationary tip cover  122 . Seal ring  190  and second secondary seal  194  may be segmented rings. The ring element  152  acts as a mating ring to the seal ring  190 . Mating ring  152  forms a 360° arc to provide a flat, smooth sealing face  138 . Mating ring  152  may be an integral part of rotor  150  or a separate component assembled on rotor  150 . In one embodiment, a seal housing  124  may define a channel  128  shaped to accommodate second secondary seal  194 . In some embodiments, mating rings  135 ,  152  of first and second axially-faced seal systems  110 ,  170 , respectively, may be formed as a portion of rotating turbine components  130  and/or rotor  150 . That is, mating ring  135  and rotating turbine components  130  may be unitary (e.g., shaped from a single piece of stock material, formed as a uniform body, etc.). Similarly, mating ring  152  and rotor  150  may be unitary. In other embodiments, mating rings  135 ,  152  may be connected (e.g., bolted, welded, etc.) to rotating turbine components  130 ,  150 . 
         [0025]    Turning to  FIG. 3 , a stationary or rotating turbine component  240  formed as one body is shown with an inner seal surface  292  and an outer seal surface  290  in accordance with embodiments of the invention. In one embodiment, stationary or rotating turbine component  240  defines a rotor bore  222  and a plurality of airfoils  230  which comprise a stage of a turbine. During assembly, a rotor may be passed through rotor bore  222  so as to locate and/or orient stationary or rotating turbine component  240  relative to other stationary or rotating turbine components to define working fluid flow passage  107  ( FIG. 2 ). Inner seal surface  292  and outer seal surface  290  may act as sealing surfaces  138  ( FIG. 2 ) and complement seal surfaces of adjacent stationary or rotating turbine components to form a set of axially faced seals radially inward and radially outward of plurality of airfoils  230  and working fluid flow passage  107  ( FIG. 2 ). 
         [0026]    Turning to  FIG. 4 , a portion of a set of stationary or rotating turbine components  330  including a set of axially faced seal components  390  are shown in accordance with embodiments of the invention. As shown, axially faced seal components  390  may be segmented with a lock element  334  to limit relative axial movement. Axially faced seal components  390  may be located at a radial tip of turbine components  330  and may include a radial flange  392  which extends radially outward from a base (shroud)  394 . In the case that turbine components  330  are rotating buckets, flanges  392  serve as the rotating mating ring and side surface  398  is the seal surface to receive a seal ring  180  ( FIG. 2 ). In the case that turbine components  330  are stationary nozzles, flange  392  serves as the seal housing to hold a seal ring  190  ( FIG. 2 ). In one embodiment, axially faced seal components  390  may include a set of circumferential edges  396  shaped to complement adjacent axially faced seal components  390  and form a substantially continuous axial surface extending either radially outward from rotating blades or radially inward from stationary nozzles. Circumferential edges  396  may be patterned. In one embodiment, circumferential edges may be shaped to form a set of lock elements  334 . 
         [0027]    Turning to  FIG. 5 , a tangential view of a seal system  420  connected to a stationary or rotating turbine component  430  is shown according to embodiments of the invention. In this embodiment, axially faced seal system  420  includes a 360° arc ring  480  which is shaped to connect to a tip  432  of a set of stationary or rotating turbine components  430 . Arc ring  480  may include a key member  484  which may complement a cell  434  formed in tip  432 , thereby securing arc ring  480  to stationary or rotating turbine component  430 . In an embodiment, arc ring  480  may include a radial flange  482  to form a seal surface  488  shaped to form a portion of a mating face seal. In one embodiment, a caulking band  486  may further secure arc ring  480  to tip  432 . 
         [0028]    Turning to  FIG. 6 , a portion of a turbine  500  is shown including an axially faced seal system  590  connected to a set of stationary or rotating turbine components  530  in accordance with embodiments of the invention. In an embodiment, axially faced seal system  590  may include a circumferential base  592  which substantially surrounds the set of stationary or rotating turbine components  530  radially outward of working fluid flow passage  507  which passes through/between set of stationary or rotating turbine components  530 . Circumferential base  592  may be secured to the set of stationary or rotating turbine components  530  by one or more peens  536  and may include a radial flange  596  which extends radially outward from circumferential base  592  to form a seal surface  588  shaped to form a portion of a face seal mating ring. 
         [0029]    Turning to  FIGS. 7 and 8 , a two-dimensional graphical representation and perspective view, respectively, of axially faced seal system  620  connected to a stationary or rotating turbine component  630  is shown according to embodiments of the invention. In an embodiment, a circumferential base  680  of axially faced seal system  620  may be connected via a set of welds  670  to a radial tip  632  of stationary or rotating turbine component  630 . In one embodiment, circumferential base  680  may include a radial flange  682  which extends radially outward from circumferential base  680  to form a seal surface  688  shaped to form a portion of a mating face seal. As can be seen in  FIG. 8 , seal system  620  may be welded to stationary or rotating turbine components  630  at an interface between radial flange  682  and circumferential base  680 . In one embodiment, circumferential base  680  and radial flange  682  may be welded at discrete locations  670  while allowing individual covers to move relative to each other along interface  608 , resulting in less distortion of radial flange  680 . 
         [0030]    Turning to  FIG. 9 , a schematic view of portions of a multi-shaft combined cycle power plant  900  is shown. Combined cycle power plant  900  may include, for example, a gas turbine  980  operably connected to a generator  970 . Generator  970  and gas turbine  980  may be mechanically coupled by a shaft  915 , which may transfer energy between a drive shaft (not shown) of gas turbine  980  and generator  970 . Also shown in  FIG. 9  is a heat exchanger  986  operably connected to gas turbine  980  and a steam turbine  992 . Heat exchanger  986  may be fluidly connected to both gas turbine  980  and a steam turbine  992  via conventional conduits (numbering omitted). Gas turbine  980  and/or steam turbine  992  may include seal system ( 110  of  FIG. 2 ) or other embodiments described herein. Heat exchanger  986  may be a conventional heat recovery steam generator (HRSG), such as those used in conventional combined cycle power systems. As is known in the art of power generation, HRSG  986  may use hot exhaust from gas turbine  980 , combined with a water supply, to create steam which is fed to steam turbine  992 . Steam turbine  992  may optionally be coupled to a second generator system  972  (via a second shaft  917 ). It is understood that generators  970  and  972  and shafts  915  and  917  may be of any size or type known in the art and may differ depending upon their application or the system to which they are connected. In another embodiment, shown in  FIG. 10 , a single shaft combined cycle power plant  910  may include a single generator  970  coupled to both gas turbine  980  and steam turbine  992  via a single shaft  915 . Steam turbine  992  and/or gas turbine  980  may include first and/or second axially faced seal system ( 110 ,  170  of  FIG. 2 ) or other embodiments described herein. 
         [0031]    The apparatus and devices of the present disclosure are not limited to any one particular turbine, generator, power generation system or other system, and may be used with other power generation systems and/or systems (e.g., combined cycle, simple cycle, nuclear reactor, etc.). Additionally, the apparatus of the present invention may be used with other systems not described herein that may benefit from the increased reduced tip leakage and increased efficiency of the systems, apparatus, and devices described herein. 
         [0032]    The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. 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 
         [0033]    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 have 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.