Abstract:
Methods and apparatus for a machine casing component carrier configured to support a machine component such that the longitudinal axis of the machine component is adjustable with respect to a longitudinal axis of a rotatable member of the machine are provided. The carrier includes a support member configured to fixedly engage the machine component, an outwardly radially extending flange configured to engage a complementary receptacle formed in the turbine casing such that the weight of the carrier is supported at least partially by the receptacle, and a selectably adjustable shim member positionable within the receptacle configured to control an alignment of the longitudinal axis of the machine component with respect to the longitudinal axis of the rotatable member.

Description:
BACKGROUND OF THE INVENTION 
   This invention generally relates to assembling rotatable machinery. More specifically, the invention is directed to alignment of components within a stationary casing. 
   At least some known steam turbine designs include static nozzle segments that direct a flow of steam into rotating buckets coupled to a rotatable member. The nozzle airfoil construction is typically called a diaphragm stage. When more than one nozzle is supported by an outer structure or ring the construction is generally referred to as a nozzle carrier for a “drum construction” flowpath. The nozzle carrier is supported vertically by several methods at a horizontal joint between an upper carrier half and a lower carrier half. Typically the vertical supports include support bars, pins or flanges welded to the turbine casing. The flanges may also be cast as part of the turbine casing if using a cast construction for the nozzle carrier. Alignment of turbine components during assembly may take several shifts or days to adjust, as both the carrier and the rotor must be removed to make the adjustment. 
   At least some known casings support the nozzle carrier using blocks under the carrier horizontal supports. The rotor and/or the nozzle carrier must be removed to make modification to the vertical position of the carrier. Typically the support blocks are bolted to the casing or carrier. The adjusting blocks have to be removed for machining (grinding) to achieve the proper casing vertical position relative to the turbine centerline. The blocks are then re-installed and the carrier and rotor replaced to check if proper alignment was achieved. The sequence is then repeated to verify the position and repeated if necessary. This process is both time consuming and costly. 
   BRIEF DESCRIPTION OF THE INVENTION 
   In one embodiment, a machine casing component carrier includes a support member configured to fixedly engage the machine component, an outwardly radially extending flange configured to engage a complementary receptacle formed in the turbine casing such that the weight of the carrier is supported at least partially by the receptacle, and a selectably adjustable shim member positionable within the receptacle configured to control an alignment of the longitudinal axis of the machine component with respect to the longitudinal axis of the rotatable member. The carrier is configured to support a machine component such that the longitudinal axis of the machine component is adjustable with respect to a longitudinal axis of a rotatable member of the machine. 
   In another embodiment, a method of assembling a rotatable machine includes coupling a plurality of nozzle airfoils to an arcuate carrier including a radially outwardly extending flange, supporting the carrier by the flange in the casing receptacle, and adjusting a vertical position of the carrier with respect to the casing longitudinal axis using a shim positioned between the flange and the receptacle. 
   In yet another embodiment, a turbine includes a casing including an upper half shell and a lower half shell configured to couple together along a mating joint, a component cater configured to support a turbine component such that the longitudinal axis of the turbine component is in substantial alignment with a longitudinal axis of a rotatable member of the turbine, the carrier including, a support member configured to fixedly engage the turbine component, an outwardly radially extending flange configured to engage a complementary receptacle formed in the turbine casing such that the weight of the carrier is supported at least partially by the receptacle, and a selectably adjustable shim member positionable within the receptacle configured to control an alignment of the longitudinal axis of the turbine component with respect to the longitudinal axis of the rotatable member. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic illustration of an exemplary opposed-flow steam turbine; 
       FIG. 2  is a perspective view of a nozzle carrier assembly configured to retain a plurality of nozzles of a turbine; 
       FIG. 3  is a schematic illustration of a portion of a nozzle carrier that may be used with the turbine shown in  FIG. 1 ; 
       FIG. 4  is a schematic side view of a portion of the turbine engine shown in  FIG.1 ; 
       FIG. 5  is a schematic illustration of a portion of a nozzle carrier that may be used with the turbine shown in  FIG. 1 ; 
       FIG. 6  is a plan view of the nozzle carrier taken along lines  5 - 5  shown in  FIG. 6 ; and 
       FIG. 7  is a perspective view of a portion of the nozzle carrier. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  is a schematic illustration of an exemplary opposed-flow steam turbine  10 . Turbine  10  includes first and second low pressure (LP) sections  12  and  14 . As is known in the art, each turbine section  12  and  14  includes a plurality of stages of diaphragms (not shown in  FIG. 1 ). A rotor shaft  16  extends through sections  12  and  14 . Each LP section  12  and  14  includes a nozzle  18  and  20 . A single outer shell or casing  22  is divided along a horizontal plane and axially into upper and lower half sections  24  and  26 , respectively, and spans both LP sections  12  and  14 . A central section  28  of shell  22  includes a low pressure steam inlet  30 . Within outer shell or casing  22 , LP sections  12  and  14  are arranged in a single bearing span supported by journal bearings  32  and  34 . A flow splitter  40  extends between first and second turbine sections  12  and  14 . 
   It should be noted that although  FIG. 1  illustrates a double flow low pressure turbine, as will be appreciated by one of ordinary skill in the art, the present invention is not limited to being used with low pressure turbines and can be used with any double flow turbine including, but not limited to intermediate pressure (IP) turbines or high pressure (HP) turbines. In addition, the present invention is not limited to being used with double flow turbines, but rather may be used with single flow steam turbines as well, for example. 
   During operation, low pressure steam inlet  30  receives low pressure/intermediate temperature steam  50  from a source, for example, an HP turbine or IP turbine through a cross-over pipe (not shown). The steam  50  is channeled through inlet  30  wherein flow splitter  40  splits the steam flow into two opposite flow paths  52  and  54 . More specifically, the steam  50  is routed through LP sections  12  and  14  wherein work is extracted from the steam to rotate rotor shaft  16 . The steam exits LP sections  12  and  14  and is routed to a condenser, for example. 
     FIG. 2  is a perspective view of a nozzle carrier assembly  210  configured to retain a plurality of nozzles  212  of a turbine, for example, a steam turbine. Carrier  210  includes upper and lower carrier halves  214  and  215 , respectively, which are joined one with the other along a horizontal joint face  216 . Nozzles  212  are arranged in an annular array thereof at axially spaced locations along carrier  210 . Each array of nozzles  212  includes a plurality of discrete nozzles  212  stacked one against the other. When a rotor (not shown) is positioned within lower carrier half  215  and carrier halves  214  and  215  are secured one to the other at the joint interface  216 , nozzles  212 , together with airfoils or buckets on the rotor, form multiple stages of a turbine. 
     FIG. 3  is a schematic illustration of a portion of a nozzle carrier  300  that may be used with turbine  10  (shown in  FIG. 1 ). Nozzle carrier  300  includes an upper half  302  and a lower half  304 . Upper half  302  includes a first radially outwardly extending flange  306  and lower half  304  includes a second radially outwardly extending flange  308 . Each flange  306  and  308  are configured to mate along a mating joint  310 . In various embodiments, flange  306  is not used, for example, based on the weight of upper half  302 . A plurality of nozzle airfoils  312  are configured to couple to nozzle carrier  300  in a circumferentially spaced arrangement. A pocket  314  is formed in the turbine casing or turbine shell structure  316  at a joint  318  between an upper shell  320  and a lower shell  322 . Extending flanges  306  and  308  are configured to be received in pocket  314  such that lower half  304  is vertically supported by shell structure  316 . In the exemplary embodiment, pocket  314  includes a recess  324  configured to receive a shim  326 , which is “trapped” in a fixed position in recess  324 . Accordingly, shim  326  is removable from recess  324  without removing nozzle carrier  300  or the turbine rotor from shell structure  316 . Rather, carrier  300  is only lifted slightly at the associated side to allow the “trapped” shim to release from pocket  314 . In an alternative embodiment, shim  326  is fabricated as a “shim pack” in which small thicknesses of shim layers are removable to adjust the thickness of shim  326  such that machining of shim  326  is reduced or eliminated. A second shim is positioned opposite shim  326  between upper shell  320  and extending flange  306  to limit the lifting of casing  316  if the torque applied to carrier  300  is greater that the assembled weight of carrier  300  on the associated side. 
     FIG. 4  is a schematic side view of a portion of turbine engine  10  (shown in  FIG. 1 ). Turbine engine  10  includes an upper half casing  400  that is bolted to a lower half casing (not shown) when turbine engine  10  is fully assembled. A nozzle carrier  402  mates to radially inner surfaces of casing  400 . Such mating facilitates maintaining nozzle carrier  402  in a relatively fixed position with respect to a rotatable member  404 , such as a turbine rotor. Nozzle carrier  402  includes a radial projection  406  that is configured to mate with a complementary groove  408  in casing  400 . A shim  410  is insertable between projection  406  and groove  408  to limit the vertical movement of the casing. The aerodynamic forces on the nozzles causes a circumferential force on the carrier that could cause lifting off of the lower casing shelf on one side. In the exemplary embodiment, shim  410  is a round shim that is slightly recessed in projection  406 . A similar configuration in the lower half casing and lower nozzle carrier segment may also be used. 
     FIG. 5  is a schematic illustration of a portion of a nozzle carrier  500  that may be used with turbine  10  (shown in  FIG. 1 ).  FIG. 6  is a plan view of nozzle carrier  500  taken along lines  5 - 5  (shown in  FIG. 6 ).  FIG. 7  is a perspective view of a portion of nozzle carrier  500 . In the exemplary embodiment, a turbine casing  502  includes a pocket  504  configured to receive an outwardly radially extending flange  506  of a carrier support member  508 . Carrier support member  508  includes a vertically extending body  509  coupled to flange  506  at a first end  510  and radially inwardly extending flange  512  coupled to a second opposing end  514 . Flange  512  is configured to engage nozzle carrier  500  such that a weight of nozzle carrier  500  is transferred through carrier support member  508  to casing  502 . In the exemplary embodiment, inwardly extending flange  512  is received in a recess  516  formed in a radially outward periphery of nozzle carrier  500 . 
   Outwardly radially extending flange  506  includes a vertically oriented hole  520  configured to receive a selectably adjustable shim member, such as an adjustment screw  522 . In the exemplary embodiment, threads  524  on adjustment screw  522  engage complementary threads  526  cut into hole  520 . In an alternative embodiment, threads  524  on adjustment screw  522  engage a locking nut  528 . Adjustment screw  522  is further configured to transfer the weight of carrier  500  to a wear pad  530 . Adjustment screw  522  is utilized to adjust a position of carrier  500  with respect to casing  502 . Wear pad  530  is fabricated from a sacrificial material and protects casing  502  and adjustment screw  522  from mutual wear during an adjustment procedure. A locking plate  532  is used to lock adjustment screw  522  into a fixed position when the adjustment procedure is completed. 
   The above-described trapped shim carrier system is a cost-effective and highly reliable method for adjusting a vertical position of rotatable machine components without having to completely disassemble the machine. 
   While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.