Abstract:
Systems for thermally regulating portions of a turbine are disclosed. In one embodiment, a turbine nozzle assembly includes: an outer diaphragm ring; a vane physically connected to the outer diaphragm ring; and an inner diaphragm ring physically connected to the vane, the inner diaphragm ring including a first axial tooth configured to interact and substantially form a seal with a second axial tooth disposed on a bucket shank.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject matter disclosed herein relates to turbines and, more particularly, to overlap seals for a turbine drum rotor cooling circuit. 
         [0002]    Some power plant systems, for example certain nuclear, simple cycle and combined cycle power plant systems, employ turbines in their design and operation. Some of these turbines are driven by a flow of high temperature steam which is directed over the buckets/blades of the turbine. This high temperature steam can have detrimental effects on the condition and longevity of certain components in the turbine such as a drum rotor. Repeated exposure of the drum rotor to high temperature steam may result in inefficient operation, corrosion, system damage, and a need for rotor repairs and/or rotor replacement. Some systems attempt to adapt the drum rotor to tolerate contact with high temperature steam in order to avoid shortening the lifespan of the drum rotor. In these systems, the drum rotor design and build process includes specific, temperature-resistant materials which are intended to allow the rotor to operate in contact with high temperature steam without significant degradation. However, these specific, temperature-resistant materials may be expensive, contributing to increased overall system cost. Further, use of these materials may complicate the design and build process. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0003]    Devices for shielding and cooling turbine components are disclosed. In one embodiment, a turbine nozzle assembly includes: an outer diaphragm ring; a vane physically connected to the outer diaphragm ring; and an inner diaphragm ring physically connected to the vane, the inner diaphragm ring including a first axial tooth configured to interact and substantially form a seal with a second axial tooth disposed on a bucket shank. 
         [0004]    A first aspect of the disclosure provides a turbine nozzle assembly including: an outer diaphragm ring; a vane physically connected to the outer diaphragm ring; and an inner diaphragm ring physically connected to the vane, the inner diaphragm ring including a first axial tooth configured to interact and substantially form a seal with a second axial tooth disposed on a bucket shank. 
         [0005]    A second aspect provides a turbine bucket including: a blade; and a bucket shank coupled to the blade, wherein the bucket shank includes a first axial tooth configured to extend toward a nozzle, substantially forming a seal with the nozzle. 
         [0006]    A third aspect provides a turbine including: a stator; a working fluid passage substantially surrounded by the stator; a drum rotor configured radially inboard of the working fluid passage; a cooling circuit fluidly connected to the drum rotor; and an overlap seal disposed between a nozzle coupled to the stator and a turbine bucket coupled to the drum rotor, the overlap seal substantially fluidly separating the working fluid passage and the cooling circuit, the overlap seal including: a first axial tooth disposed upon the nozzle; and a second axial tooth disposed upon the turbine bucket, the second axial tooth being configured to interact and substantially form a seal with the first axial tooth. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    These and other features of this invention will be more readily understood from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings that depict various embodiments of the invention, in which: 
           [0008]      FIG. 1  shows a partial cut-away schematic view of a turbine system according to an embodiment of the invention. 
           [0009]      FIG. 2  shows a partial cut-away schematic view of a turbine system according to an embodiment of the invention. 
           [0010]      FIG. 3  shows a partial cut-away schematic view of portions of a turbine system according to an embodiment of the invention. 
           [0011]      FIG. 4  shows a three-dimensional perspective view of a turbine bucket according to an embodiment of the invention. 
           [0012]      FIG. 5  shows a partial cut-away schematic view of portions of a turbine system according to an embodiment of the invention. 
           [0013]      FIG. 6  shows a partial cut-away schematic view of a nozzle and turbine bucket according to an embodiment of the invention. 
           [0014]      FIG. 7  shows a partial cut-away schematic view of an embodiment of a nozzle and turbine bucket in accordance with an aspect of the invention. 
           [0015]      FIG. 8  shows a partial cut-away schematic view of an embodiment of a nozzle and turbine bucket in accordance with an aspect of the invention. 
           [0016]      FIG. 9  shows a partial cut-away schematic view of an embodiment of a nozzle and turbine bucket in accordance with an aspect of the invention. 
           [0017]      FIG. 10  shows a schematic block diagram illustrating portions of a combined cycle power plant system according to embodiments of the invention. 
           [0018]      FIG. 11  shows a schematic block diagram illustrating portions of a single-shaft combined cycle power plant system according to embodiments of the invention. 
       
    
    
       [0019]    It is noted that the drawings of the disclosure are not necessarily to scale. The drawings are intended to depict only typical aspects of the disclosure, and therefore should not be considered as limiting the scope of the disclosure. In the drawings, like numbering represents like elements between the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    Some turbines include static nozzle assemblies that direct flow of a working fluid into turbine buckets connected to a rotating drum rotor. The turbine buckets include bucket shanks and blades (airfoils) and the nozzle assembly includes a plurality of nozzles, “vanes” or “airfoils” and is sometimes referred to as a “diaphragm” or “nozzle assembly stage.” Steam turbine diaphragms include two rings, the outer diaphragm ring and the inner diaphragm ring. These two rings are separated by and coupled to one another via a plurality of vanes. The nozzle assembly is typically comprised of two halves, one upper and one lower, each containing an inner ring, an outer ring, and a plurality of vanes. The upper and lower halves are assembled around the rotor. 
         [0021]    As indicated above, aspects of the invention provide for systems and devices configured to thermally protect portions of a turbine from damage due to contact with a turbine working fluid (e.g., high temperature steam) by using overlap seals and a cooling circuit. The cooling circuit supplies a cooling fluid (e.g., low temperature steam) to the drum rotor. The low temperature steam travels through the drum rotor via the cooling circuit which is defined in part by axial passages through the turbine buckets, and overlap seals which are disposed between nozzles and turbine buckets in the turbine. The overlap seals substantially blocking the axial gap between bucket platforms and nozzle root bands and restricting radially inward or outward flows. 
         [0022]    In the art of power generation systems (including, e.g., nuclear reactors, steam turbines, gas turbines, etc.), turbines driven by high temperature steam are often employed as part of the system. The high temperature steam is directed through multiple sets of turbine buckets, thereby rotating a drum rotor and converting thermal energy into mechanical energy. Typically, as the temperature of the steam is increased, so too is the efficiency of the overall power generation system. However, the high temperature steam may have negative effects on certain components of the turbine such as the drum rotor. The high temperature of the steam can cause material damage to the drum rotor, increasing the maintenance cost of the system and significantly reducing the lifespan of the drum rotor. 
         [0023]    Turning to the FIGURES, embodiments of a cooling circuit including overlap seals are shown, where the cooling circuit may impact the efficiency and increase the life expectancy of the drum rotor, the turbine and the overall power generation system by cooling the drum rotor and shielding the drum rotor from contact with a working fluid (e.g., high temperature steam). Each of the components in the FIGURES may be connected via conventional means, e.g., via a common conduit or other known means as is indicated in  FIGS. 1-11 . Specifically, referring to  FIG. 1 , a partial cross-sectional view of a turbine  100  is shown according to embodiments of the invention. Turbine  100  may include a drum rotor  10  (partially shown in  FIG. 1 ) and a stator  15  (partially shown in  FIG. 1 ) substantially surrounding drum rotor  10 . Drum rotor  10  may include at least one substantially circumferential dovetail slot  40  along its outer circumference. A turbine bucket  12  may be secured within at least one substantially circumferential dovetail slot  40  on drum rotor  10 . Drum rotor  10  may include a plurality of substantially circumferential dovetail slots  40  and a plurality of turbine buckets  12  secured therein as is known in the art. 
         [0024]    Stator  15  may include at least one nozzle  17  secured within a nozzle slot  19 . As seen in  FIG. 1 , stator  15  may include a plurality of nozzles  17  which define stages of the turbine and may be secured within nozzle slots  19 . Nozzles  17  and turbine buckets  12  may radially extend respectively from stator  15  and drum rotor  10 , such that nozzles  17  and turbine buckets  12  are interspersed along an axial length of turbine  100 . A working fluid, such as steam, may be directed to a downstream location  14 , along primary working fluid passage  5  through turbine buckets  12  and nozzles  17  to assist the rotation of drum rotor  10 . 
         [0025]    Turning to  FIG. 2 , a schematic partial cut-away side-view of a turbine  200  including an overlap seal  207  is shown according to embodiments. It is understood that elements similarly numbered between  FIG. 1  and  FIG. 2  may be substantially similar as described with reference to  FIG. 1 . Further, in embodiments shown and described with reference to  FIGS. 2-11 , 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. 1-11  and their accompanying descriptions may be applied to any embodiment described herein. 
         [0026]    Returning to  FIG. 2 , in this embodiment, turbine  200  may include a packing head  210 . A cooling fluid may be introduced into turbine  200  through a cooling circuit  7  via a snout  202  in packing head  210 . The fluid introduced through cooling circuit  7  may include steam or any other fluid as is known in the art. Snout  202  may be configured to supply fluid to an annulus  206  via coolant delivery passages  204 . In one embodiment, packing head  210  may include a plurality of snouts  202  configured to introduce cooling fluid into turbine  200  via cooling circuit  7 . In one embodiment, packing head  210  may include a single coolant delivery passage  204 . In one embodiment, coolant delivery passages  204  may be configured as straight radially extending passages. In another embodiment, coolant delivery passages  204  may be configured as a tortuous set of passages. In any event, cooling circuit  7  may direct a fluid to annulus  206  via snout  202  and coolant delivery passages  204 . From annulus  206 , cooling circuit  7  directs the fluid through drum rotor  10 . In drum rotor  10 , cooling circuit  7  is further defined by overlap seal  207  disposed between turbine bucket  12  and nozzle  17 . Overlap seal  207  is configured to shield drum rotor  10  from fluid and/or thermal contact with a working fluid passage  5  and to fluidly separate working fluid passage  5  and cooling circuit  7 . 
         [0027]    Turning to  FIG. 3 , a partial cut-away of an embodiment of a turbine  300  is shown having cooling circuit  7  partially defined by a plurality of overlap seals  207  and a set of axial passages  302  (shown in phantom) formed through turbine bucket shanks  502 . In this embodiment, axial passages  302  may be fluidly connected to cooling circuit  7 , allowing fluid to pass from annulus  206  through multiple stages of turbine  300  via axial passages  302 . The plurality of overlap seals  207  disposed on a turbine bucket shank  502  of turbine bucket  12  and an inner diaphragm ring  507  of nozzle  17 . Plurality of overlap seals  207  further defining cooling circuit  7 , shielding rotor  10  from working fluid passage  5  and separating working fluid passage  5  and cooling circuit  7 . In one embodiment, cooling circuit  7  may pass through a set of nozzle root seals  304  disposed between rotor  10  and nozzles  17 . In one embodiment, cooling circuit  7  may be pressurized such that a positive pressure differential is created relative to working fluid passage  5 . In another embodiment, working fluid passage  5  may be pressurized such that a positive pressure differential is created relative to cooling circuit  7 . In one embodiment, a fluid passing through cooling circuit  7  may be at a low temperature relative to a fluid passing through working fluid passage  5 . In one embodiment, after passing through a set of stages in turbine  300  via axial passages  302 , cooling circuit  7  may exhaust the cooling fluid into working fluid passage  5 . 
         [0028]    Turning to  FIG. 4 , a partial three-dimensional perspective of an environment  400  including an embodiment of a turbine bucket shank  502  is shown having a set of axial passages  302  there through. Axial passages  302  enable the passing of a fluid through a plurality of stages in a turbine. In one embodiment, axial passages  302  may be machined into bucket shank  502 . In another embodiment, axial passages  302  may be formed in bucket shank  502 . In another embodiment, axial passages  302  may be fluidly connected to cooling circuit  7 . 
         [0029]    Turning to  FIG. 5 , a partial cut-away of a portion of an embodiment of a turbine  500  is shown having axial teeth  508  disposed upon an inner diaphragm ring  507  of nozzle  17  and axial teeth  509  disposed upon a bucket shank  502  of turbine bucket  12 . In this embodiment, axial teeth  508  extend toward bucket shank  502  such that axial teeth  508  overlap and interact with axial teeth  509  which extend toward inner diaphragm ring  507 , thereby forming a plurality of overlap seals  207 . Plurality of overlap seals  207 , partially define cooling circuit  7  along with axial passage  302  (shown in phantom) and an axial passage  510  (shown in phantom). In this embodiment, turbine bucket  12  includes bucket shank  502  and a blade  504 . Nozzle  17  includes an outer diaphragm ring  505 , inner diaphragm ring  507  and a nozzle vane  503 . In this embodiment, overlap seals  207  substantially fluidly separate working fluid passage  5  and cooling circuit  7  which is radially inboard of working fluid passage  5  and passes below axial teeth  508  and  509 , and through axial passages  302  and  510 . In one embodiment, cooling circuit  7  may be exhausted into working fluid passage  5  via axial passage  510 . In one embodiment, nozzle vane  503  may have a height between about 1 inch and about 2 inches, and a width between about 1 inch and about 2 inches. In another embodiment, nozzle vane  503  may have a height between about 2 inches and about 3 inches, and a width between about 2 inches and about 3 inches. In one embodiment, nozzle vanes  503  may be circumferentially spaced between about 0.2 inches and about 0.7 inches relative one another. 
         [0030]    Turning to  FIG. 6 , a partial cut-away view of an embodiment of a nozzle  17  and set of turbine buckets  12  is shown having a plurality of axial teeth  508  and  509 . In this embodiment, two axial teeth  508  disposed on inner diaphragm ring  507  may be configured between two axial teeth  509  disposed on bucket shank  502  so as to interact and form overlap seals  207 . In one embodiment, overlap seal  207  may be comprised of any number of axial teeth  508  and  509 . Overlap seal  207  with axial passages  302 , partially defining cooling circuit  7  which may flow through nozzle root seals  304 . 
         [0031]    Turning to  FIG. 7 , a partial cut-away of an embodiment of a nozzle  17  and set of turbine buckets  12  is shown having axial teeth  508  configured relative to axial teeth  509  so as to form overlap seals  207 . In this embodiment, axial teeth  508  disposed on inner diaphragm ring  507  include a radially extending tip portion  808 . Radially extending tip portion  808  further reducing a clearance between axial teeth  508  and  509 , and substantially forming a seal there between. Turning to  FIG. 8 , a partial cut-away view of an embodiment of a nozzle  17  and set of turbine buckets  12  is shown having axial teeth  508  configured relative to axial teeth  509  so as to form overlap seals  207 . In this embodiment, axial teeth  509  disposed on bucket shanks  502  include a radially extending tip portion  809 . Radially extending tip portion  809  further reducing a clearance between axial teeth  508  and  509 , and substantially forming a seal there between. Turning to  FIG. 9 , a partial cut-away view of an embodiment of a nozzle  17  and set of turbine buckets  12  is shown having axial teeth  508  configured relative to axial teeth  509  so as to form overlap seals  207 . In this embodiment, axial teeth  508  include a radially extending tip portion  808  and axial teeth  509  include a radially extending tip portion  809 . Radially extending tip portions  808  and  809  further reducing a clearance between axial teeth  508  and  509 , and substantially forming a seal there between. 
         [0032]    Turning to  FIG. 10 , 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  902  operably connected to a generator  908 . Generator  908  and gas turbine  902  may be mechanically coupled by a shaft  907 , which may transfer energy between a drive shaft (not shown) of gas turbine  902  and generator  908 . Also shown in  FIG. 10  is a heat exchanger  904  operably connected to gas turbine  902  and a steam turbine  906 . Heat exchanger  904  may be fluidly connected to both gas turbine  902  and a steam turbine  906  via conventional conduits (numbering omitted). Gas turbine  902  and/or steam turbine  906  may be fluidly connected to cooling circuit  7  of  FIG. 3  or other embodiments described herein. Heat exchanger  904  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  904  may use hot exhaust from gas turbine  902 , combined with a water supply, to create steam which is fed to steam turbine  906 . Steam turbine  906  may optionally be coupled to a second generator system  908  (via a second shaft  907 ). It is understood that generators  908  and shafts  907  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. Common numbering of the generators and shafts is for clarity and does not necessarily suggest these generators or shafts are identical. In one embodiment (shown in phantom), cooling circuit  7  may receive a fluid from HRSG  904 . In another embodiment, cooling circuit  7  may receive a fluid from steam turbine  906 . In one embodiment of the present invention (shown in phantom), cooling circuit  7  receives a fluid from a fluid source  909 . Fluid source  909  may be a compressor, pressurized gas source or other fluid source as is known in the art. In another embodiment (shown in phantom), cooling circuit  7  may receive a fluid in the form of compressed air generated from the operation of gas turbine  902 . In another embodiment, steam turbine  906  may be fluidly integrated with cooling circuit  7 . In another embodiment, shown in  FIG. 11 , a single shaft combined cycle power plant  990  may include a single generator  908  coupled to both gas turbine  902  and steam turbine  906  via a single shaft  907 . Steam turbine  906  and/or gas turbine  902  may be fluidly connected to cooling circuit  7  of  FIG. 3  or other embodiments  200 ,  400 ,  500 ,  600 ,  700 ,  800  or  900  described herein. 
         [0033]    The overlap seals and cooling circuit of the present disclosure are not limited to any one particular turbine, 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 overlap seals and cooling circuit of the present invention may be used with other systems not described herein that may benefit from the thermal protection of the cooling circuit described herein. 
         [0034]    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. 
         [0035]    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.