Abstract:
A rotor and wheel cooling assembly for a steam turbine system includes a rotor operably connected to a plurality of rotating buckets. Also included is a flow diverting member having an inner radius and operably coupled to at least one nozzle stage, wherein the flow diverting member directs flow in at least one direction within the steam turbine system. Further included is a cooling flow dispenser disposed radially outwardly of a portion of the rotor and having at least one aperture, wherein the cooling flow dispenser is operably coupled to the inner radius of the flow diverting member.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject matter disclosed herein relates to steam turbine systems, and more particularly to an assembly for cooling a rotor therein. 
         [0002]    Steam turbines typically include static nozzle assemblies that direct steam into rotating buckets that are connected to a rotor. A plurality of diaphragm stages or nozzle assembly stages is included and each stage is assembled around the rotor. Select sections of the steam turbine system have double flow configurations, in which inlet steam is typically split for flow into two axially opposite directions. The stage that divides the flow is referred to as a flow splitter or tub. Upon splitting the inlet steam, the steam flows axially in opposite directions through nozzle and bucket stages on each side of the flow splitter. 
         [0003]    Flow splitter stages with relatively “hot” bowl temperatures require rotor cooling. Such a temperature will depend on the particular application of use, but 1,000° F. is an example of a common bowl temperature that may require rotor cooling. A common arrangement employed for rotor and wheel cooling includes passing cooling flow into a flow splitter cavity through an external pipe and taking lower temperature steam from high pressure (HP) stages or any other external source. Packing rings on flow splitter flanges impart pressure that diverts the flow into the turbine and generator end. Often, insufficient flow circulation persists, creating windage heating of the flow splitter, thereby causing windage interaction with the rotor and wheel resulting in reduced turbine output. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0004]    According to one aspect of the invention, a rotor and wheel cooling assembly for a steam turbine system includes a rotor operably connected to a plurality of rotating buckets. Also included is a flow diverting member having an inner radius and operably coupled to at least one nozzle stage, wherein the flow diverting member directs flow in at least one direction within the steam turbine system. Further included is a cooling flow dispenser disposed radially outwardly of a portion of the rotor and having at least one aperture, wherein the cooling flow dispenser is operably coupled to the inner radius of the flow diverting member. 
         [0005]    According to another aspect of the invention, a rotor and wheel cooling assembly for a steam turbine system includes a rotor operably connected to a plurality of rotating buckets. Also included is a cooling flow conduit for transferring a cooling substance. Further included is a flow diverting member having an inner radius, wherein the flow diverting member includes a ridge for directing flow in at least one direction within the steam turbine system. Yet further included is a cooling flow dispenser disposed radially outward of a portion of the rotor and having at least one aperture, wherein the cooling flow dispenser is operably coupled to the inner radius of the flow diverting member. Also included is a gap disposed between the inner radius of the flow diverting member and the cooling flow dispenser for receiving the cooling substance from the cooling flow conduit. 
         [0006]    According to yet another aspect of the invention, a rotor and wheel cooling assembly for a steam turbine system includes a rotor operably connected to a plurality of rotating buckets and a wheel disposed between the rotor and a turbine bucket. Also included is a cooling flow conduit for transferring a cooling substance. Further included is a flow diverting member having an inner radius and fixedly connected with at least one nozzle stage by at least one hook assembly. Yet further included is a cooling flow dispenser disposed radially outward of a portion of the rotor and having a plurality of apertures, wherein the cooling flow dispenser is operably coupled to the inner radius of the flow diverting member. Also included is a gap disposed between the inner radius of the flow diverting member and the cooling flow dispenser for receiving the cooling substance from the cooling flow conduit. 
         [0007]    These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0008]    The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0009]      FIG. 1  is a schematic, cross-sectional view of a typical double flow steam turbine system having a flow splitter; 
           [0010]      FIG. 2  is a perspective view of a portion of a steam turbine system having an operable connection to a nozzle assembly; 
           [0011]      FIG. 3  is a side, cross-sectional view of a rotor cooling assembly having a first operable connection to the nozzle assembly; 
           [0012]      FIG. 4  is a cross-sectional view of a flow cooling dispenser taken along line IV-IV of  FIG. 3 ; 
           [0013]      FIG. 5  is a side, cross-sectional view of the rotor cooling assembly having a second operable connection to the nozzle assembly; and 
           [0014]      FIG. 6  is a side, cross-sectional view of the rotor cooling assembly having the flow splitter with a flat outer region. 
       
    
    
       [0015]    The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    Referring to  FIGS. 1 and 2 , a steam turbine is generally referred to with the numeral  10 . The illustrated steam turbine  10  is of a double flow configuration and includes an outer casing  12 , an inner casing  14  and a plurality of nozzles and buckets forming plural stages on each of the axially spaced sides of the steam turbine  10 . The turbine  10  also includes a rotor  16  mounted to the buckets. The rotor  16  extends through opposite axial ends of the steam turbine  10  and within a flow splitter  18  that is annularly configured, which may also be referred to as a tub. The flow splitter  18  is located centrally of the steam turbine  10  and receives steam through a steam inlet  20  for flow to the various turbine stages on the axially opposite sides of the flow splitter  18 . Specifically, the flow splitter  18  includes opposite halves, which are typically mirror images of each other, and therefore only one half is illustrated and described. The opposite halves are referred to as a top half  22  and a bottom half (not shown), which are each of a semi-circular geometry. The top half  22  is disposed radially outward of the rotor  16 , which extends axially through the steam turbine  10 . 
         [0017]    Referring now to  FIG. 3 , a cross-sectional view of a rotor cooling assembly  24  is illustrated. The rotor cooling assembly  24  comprises the previously described flow splitter  18  and a cooling flow dispenser  26 . The flow splitter  18  extends circumferentially around the rotor  16  and a wheel  17  and is operably coupled to at least one nozzle assembly  28  via one or more fasteners or bonding agents. Alternatively, a hook configuration or other mechanical fasteners may be employed, as described below. The wheel  17  is disposed between the rotor  16  and a turbine bucket and is also cooled by the rotor cooling assembly  24 . The flow splitter  18  includes an inner radius  30  and an outer surface  32  that forms a ridge  34  that is centrally located on the outer surface  32 , with respect to the axial direction of the steam turbine  10 . The ridge  34  biases incoming steam flow in multiple directions, as described above. The flow splitter  18  includes a hollowed core  36  for receiving a cooling flow conduit  38 . The cooling flow conduit  38  is configured to transfer a cooling substance. The cooling substance may be comprised of various substances, provided the cooling substance is of a sufficiently low temperature to achieve the intended rotor cooling function to a sufficient degree. 
         [0018]    The cooling flow dispenser  26  extends circumferentially around the rotor  16  and is operably coupled to the inner radius  30  of the flow splitter  18 . The coupling between the cooling flow dispenser  26  and the flow splitter  18  may be facilitated via welding, for example, but it is to be appreciated that various other mechanical or chemical fastening approaches may be taken to provide the operable coupling. A gap  40  is present between at least a portion of the cooling flow dispenser  26  and the inner radius  30  of the flow splitter  18 . The gap  40  is configured to receive the cooling substance from the cooling flow conduit  38 . The cooling flow dispenser  26  includes at least one first aperture  42  extending radially inward toward the rotor  16  and in a first plane  44 . The first plane  44  is defined by loci of points and axes located in a single axial location of the steam turbine  10 . In other words, the at least one first aperture  42  directs the cooling substance radially inward toward the rotor  16  to provide a cooling effect. Additionally, the cooling flow dispenser  26  includes at least one second aperture  46  extending radially inward, but also at an angle from the at least one first aperture  42 , and therefore at an angle from the first plane  44 . Specifically, the at least one second aperture  46  is configured to direct the cooling substance radially inward toward the rotor  16 , but also toward locations upstream or downstream of the steam turbine  10 . The precise angle that the at least one second aperture  46  is disposed from the first plane  44  may vary, but in one contemplated embodiment the angle may be about 30 degrees from the first plane  44  in either the upstream or downstream direction. It is also to be understood that either or both of the at least one first aperture  42  and the at least one second aperture  46  may comprise a plurality of apertures. In the case of the at least one first aperture  42 , there may be a plurality of apertures spaced circumferentially from one another and all directed radially inward toward the rotor  16  and within the first plane  44  ( FIG. 4 ). As for the at least one second aperture  46 , there may be a plurality of apertures on either axial side of the at least one first aperture  42 , and disposed at an angle therefrom, and may also comprise a plurality of apertures extending circumferentially from one another around the cooling flow dispenser  26 . It is to be appreciated that one or all of the at least one first aperture  42  and/or all or one of the at least one second aperture  46  may be tapered to improve the degree of pre-swirl imposed on the cooling substance as it passes through the apertures. Although the alignments of the at least one first aperture  42  and the at least one second aperture  46  are described above, it is to be understood that the at least one first aperture  42  may be disposed at an angle, either alone or in combination with the at least one second aperture  46 . 
         [0019]    In operation, the cooling substance travels through the cooling flow conduit  38  and is expelled in the gap  40  defined between at least a portion of the cooling flow dispenser  26  and the inner radius  30  of the flow splitter  18 . Further direction of the cooling substance is facilitated through the at least one first aperture  42  and the at least one second aperture  46 . The at least one first aperture  42  directs the cooling substance radially inward within the first plane  44  and toward the rotor  16  for a cooling effect. The at least one second aperture  46  directs the cooling substance radially inward, but at an angle to induce a pre-whirl of the cooling substance, thereby reducing friction with the rotor  16  and windage interaction with the rotor  16 . 
         [0020]    Referring now to  FIG. 5 , the rotor cooling assembly  24  is illustrated and is similar in construction to that illustrated in  FIG. 3 , however, includes an alternative attachment structure between the flow splitter  18  and the at least one nozzle assembly  28 . In the illustrated embodiment, at least one hook joint assembly  50  facilitates an operable connection between the flow splitter  18  and the at least one nozzle assembly  28 . The at least one hook joint assembly  50  includes a hook component  52  and a receiving component  54 . 
         [0021]    Referring now to  FIG. 6 , the rotor cooling assembly  24  is illustrated and is similar in construction to that illustrated in  FIG. 3 , however, the flow splitter  18  includes a relatively flat surface  60  that defines the outer surface  32 . This is in contrast to the flow splitter  18  that includes a ridge  34  for splitting incoming flow. 
         [0022]    Advantageously, the cooling flow dispenser  26  provides the required cooling of the rotor  16  and reduces windage with the rotor  16  and reduces or eliminates excessive components that increase raw material cost and complicate the assembly process. 
         [0023]    While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.