Abstract:
A method of removing a bucket from a turbomachine rotor wheel includes exposing a base portion of the bucket, positioning a pulling device radially outwardly of the base portion, connecting the base portion of the bucket to the pulling device through a linking rod, exerting an axially outwardly directed force on the linking rod through the pulling device, and removing the base portion from the rotor wheel.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject matter disclosed herein relates to the art of turbomachines and, more particularly, to a method of removing a rotor bucket from a turbomachine rotor wheel. 
         [0002]    Steam turbines typically include rotating buckets or blades and stationary nozzles. Steam is passed through a number of turbine stages. Each stage includes a row of stationary nozzles and rotating blades mounted to a rotor wheel. Steam expands through the number of turbine stages to rotate rotor wheel creating work. 
         [0003]    The buckets are typically mounted to the rotor wheel through a dovetail attachment. The rotor wheel may include an internal, circumferential dovetail. Each bucket or blade has a corresponding dovetail that cooperates with the internal, circumferential dovetail. Generally, each rotor wheel features a loading position or gate opening configured to receive each bucket. Each bucket is mounted to the rotor wheel and manipulated into place about the outer diametric surface. Once all buckets are mounted, a closure bucket is installed in the loading portion and secured to the rotor wheel to prevent bucket liberation. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0004]    According to one aspect of an exemplary embodiment, a method of removing a bucket from a turbomachine rotor wheel includes exposing a base portion of the bucket, positioning a pulling device radially outward of the base portion, connecting the base portion of the bucket to the pulling device through a linking rod, exerting a radially outwardly directed force on the linking rod through the pulling device, and removing the base portion from the rotor wheel. 
         [0005]    According to another aspect of an exemplary embodiment, a method of removing a bucket from a rotor wheel includes positioning a ram radially outward of the base portion, connecting the base portion of the bucket to a ram, exerting a radially outwardly directed force on the base portion, and removing the base portion from the rotor wheel. 
         [0006]    These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0007]    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: 
           [0008]      FIG. 1  is schematic view of a turbomachine shown in the form of a steam turbine in accordance with the prior art 
           [0009]      FIG. 2  is a perspective view of a rotor wheel of the turbomachine of  FIG. 1 ; 
           [0010]      FIG. 3  is a perspective view of a closure bucket spaced from the rotor wheel of  FIG. 2 ; 
           [0011]      FIG. 4  is a perspective view of the closure bucket of  FIG. 3  installed in the rotor wheel; 
           [0012]      FIG. 5  is a perspective view of a bucket portion of the closure bucket removed, in accordance with an exemplary embodiment; 
           [0013]      FIG. 6  is a perspective view of a threaded opening formed in a base portion of the closure bucket of  FIG. 5 , in accordance with an exemplary embodiment; 
           [0014]      FIG. 7  is a perspective view of a pulling device coupled to the base portion of the closure bucket of  FIG. 6 , in accordance with an exemplary embodiment; 
           [0015]      FIG. 8  is a perspective view of the base portion of the closure bucket being removed from the rotor wheel by the pulling device, in accordance with an aspect of an exemplary embodiment; and 
           [0016]      FIG. 9  is a perspective view of the base portion of the closure bucket being removed in pieces, in accordance with another aspect of an exemplary embodiment. 
       
    
    
       [0017]    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 
       [0018]    A turbomachine is illustrated generally at  2  in  FIG. 1 . Turbomachine  2  is shown in the form of a steam turbine  4  having a turbine housing  16  that encloses a number of turbine stages three of which are indicated at  20 ,  21  and  22 . Of course, it would be appreciated by one of ordinary skill in the art that the number of turbine stages could vary. Each turbine stage  20 - 22  includes a corresponding plurality of stationary airfoil members or nozzles, such as indicated at  24  in connection with stage  22 , arranged upstream from a plurality of rotating airfoil members or buckets, such as shown at  26 . Rotating airfoil members  26  are mounted to a rotor wheel  30  within steam turbine  4 . 
         [0019]    With this arrangement, steam from a boiler or similar arrangement (not shown) is directed into steam turbine  4 . The steam expands through stages  20 - 22  creating work that is used to power an external component  34 . External component  34  may take on a variety of forms including a generator or a pump or other mechanically driven systems. That is, steam turbine  4  could also be used as a power source for a vehicle. 
         [0020]    In accordance with the exemplary embodiment illustrated in  FIG. 2 , rotor wheel  30  includes a rotor wheel body  40  having a first face  42  and an opposing, second face  43  that are joined by an outer diametric surface  45 . A bucket receiving slot  60  is formed in outer diametric surface  45 . Bucket receiving slot  60  supports plurality of rotating airfoil members  26  about outer diametric surface  45 . Bucket receiving slot  60  includes a bucket mounting opening  63  and interior cavity  66  formed in rotor wheel body  40 . Each of the plurality of rotating airfoil members  26  includes a base portion  72  ( FIG. 3 ) that supports an airfoil portion  73  and a mounting member or dovetail  74 . Airfoil portion  73  includes a ring element  75  that forms part of a circumferentially extending rotor ring  76 . Dovetail  74  is shaped to nest within bucket receiving slot  60 . Each of the plurality of rotating airfoil members  26  is guided into bucket receiving slot  60  and manipulated into position. Once all buckets are installed, a closure bucket  80  is installed into bucket receiving slot  60  and held in place by mechanical fasteners or grub screws  82  and  84 , such as shown in  FIG. 4   
         [0021]    Over the course of time, steam turbine  4  may be taken offline for maintenance and/or repair. Maintenance includes an inspection of the buckets. During operation a bucket(s) may become damaged. The damaged bucket(s) is removed and replaced. Removing the damaged bucket first requires removal of the closure bucket  80  which may, itself, be damaged. In accordance with an aspect of an exemplary embodiment, removal of a damaged closure bucket  80  includes removing grub screws  82  and  84  and airfoil portion  73 , as shown in  FIG. 5 , to expose an upper surface  90  of base portion  72 . After removing airfoil portion  73 , a bore  96  is formed in closure bucket  80 , as shown in  FIG. 6 . Bore  96  extends radially inwardly into base portion  72 . A plurality of threads  100  are formed in base portion  72  along bore  96 . 
         [0022]    After forming threads  100 , a pulling device  110  is arranged radially outward of closure bucket  80 , as shown in  FIG. 7 . Pulling device  110  includes a base  112  supported by rotor ring  76  and a ram  114 . Pulling device  110  may rely upon air pressure, hydraulic pressure, or electrical current to operate ram  114 . Ram  114  is connected to base portion  72  through a linking rod  120 . Linking rod  120  includes a plurality of threads (not separately labeled) that engage with threads  100  in base portion  72 . Ram  114  is actuated to exert a radially outwardly directed force on base portion  72  through linking rod  120 . The radially outwardly directed force may cause base portion  72  to release from rotor wheel  30 , as shown in  FIG. 8 . At this point, the remaining buckets may be circumferentially shifted to bucket mounting opening  63  and removed from rotor wheel  30  for inspection and/or replacement. 
         [0023]    At this point it should be understood that the exemplary embodiments describe a method for removing a closure bucket from a rotor wheel. In the event that the closure bucket may does not release from rotor wheel, base portion and pin may be broken up into a plurality of pieces, indicated generally at  140 , and removed, as shown in  FIG. 9 . At this point, the remaining buckets may be circumferentially shifted to bucket mounting opening  63  and removed. If the additional buckets resist removal efforts, all airfoil portions may be removed and corresponding base portions broken up into pieces  140  to enable removal. It should also be understood that while described in terms of removing a bucket from a rotor wheel in a steam turbine, the method may also be employed to remove buckets from rotor wheels arranged in other turbomachine systems including compressors and gas turbines. Further, it should be understood that the method may be used to remove the closure bucket without requiring that the rotor wheel be separated from other rotor wheels or removed from the turbine rotor. The destruction of a single bucket, in situ, reduces downtime and overall maintenance costs associated with the steam turbine  4 . 
         [0024]    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.