Patent Publication Number: US-8984730-B2

Title: System and method for rotating a turbine shell

Description:
FIELD OF THE INVENTION 
     The present invention generally involves a system and method for rotating a turbine shell. 
     BACKGROUND OF THE INVENTION 
     Turbines are widely used in industrial and commercial operations. For example, a typical commercial steam or gas turbine used to generate electrical power includes a turbine shell or casing that generally surrounds alternating stages of rotating blades and stationary vanes to contain high temperature and pressure steam or combustion gases flowing through the turbine. The turbine shell may weigh several hundred thousand pounds and often includes multiple pieces bolted together to facilitate manufacture, installation, maintenance of the turbine. 
     Removal of the turbine shell for maintenance or repairs requires heavy duty equipment and space around the turbine that may not always be available. For example, one or more cranes equipped with slings or hooks may be required to lift the turbine shell above the turbine and rotate the turbine shell to facilitate access to the underside of the turbine shell for maintenance or repairs. Oftentimes, the rotation of the turbine shell entails multiple, iterative steps of partially rotating the turbine shell, disconnecting some of the crane hooks, re-connecting the crane hooks to the partially rotated turbine shell, and rotating the turbine shell further. In addition to being time-consuming, the awkward rotation of such a heavy component while being suspended from cranes creates a substantial risk of damage to personnel and equipment. Therefore, an improved system and method for rotating a turbine shell that reduces the required time and/or risk to personnel and/or equipment would be useful. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Aspects and advantages of the invention are set forth below in the following description, or may be obvious from the description, or may be learned through practice of the invention. 
     One embodiment of the present invention is a system for rotating a turbine shell. The system includes a first platform and a first trunnion rotatably connected to the first platform, wherein the first trunnion is adapted to connect to a first portion of the turbine shell. A second platform is separated from the first platform, and a second trunnion is separated from the first trunnion and rotatably connected to the second platform, wherein the second trunnion is adapted to connect to a second portion of the turbine shell. The system further includes means for rotating the first trunnion. 
     Another embodiment of the present invention is a system for rotating a turbine shell that includes a first platform, a first roller on the first platform, and a first trunnion rotatably engaged with the first roller, wherein the first trunnion is adapted to connect to a first portion of the turbine shell. A second platform is separated from the first platform, with a second roller on the second platform. A second trunnion separated from the first trunnion is rotatably engaged with the second roller, wherein the second trunnion is adapted to connect to a second portion of the turbine shell. A first motor is operably connected to rotate the first trunnion. 
     The present invention may also include a method for rotating a turbine shell that includes connecting a first trunnion to a first portion of the turbine shell, wherein the first trunnion is rotatably connected to a first platform. The method further includes connecting a second trunnion to a second portion of the turbine shell, wherein the second trunnion is rotatably connected to a second platform and wherein the second trunnion is separated from said first trunnion, and rotating the first trunnion to rotate the turbine shell. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present invention, including the best mode thereof to one skilled in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which: 
         FIG. 1  is a perspective view of an exemplary turbine shell; 
         FIG. 2  is a perspective view of a system for rotating a turbine shell according to one embodiment of the present invention; 
         FIG. 3  is an enlarged perspective view of a portion of the platforms shown in  FIG. 2 ; 
         FIG. 4  is a flow diagram of a method for rotating a turbine shell according to one embodiment of the present invention; 
         FIG. 5  is a perspective view of the turbine shell shown in  FIG. 1  connected to the trunnions shown in  FIG. 2 ; 
         FIG. 6  is a perspective view of the turbine shell and trunnions shown in  FIG. 5  placed on the platforms shown in  FIG. 2 ; and 
         FIG. 7  is a perspective view of the turbine shell shown in  FIG. 1  being rotated by the system shown in  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention. As used herein, the terms “first”, “second”, and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. In addition, the terms “upstream” and “downstream” refer to the relative location of components in a fluid pathway. For example, component A is upstream from component B if a fluid flows from component A to component B. Conversely, component B is downstream from component A if component B receives a fluid flow from component A. 
     Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope or spirit thereof. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
     Various embodiments of the present invention include a system and method for rotating a turbine shell. The system generally includes a pair of trunnions rotatably connected to associated platforms. The trunnions are adapted to connect to separate portions of the turbine shell so that rotation of the trunnions rotates the turbine shell. In particular embodiments, the system and method may include means for determining the orientation of the platforms and/or aligning the platforms with respect to one another. Although exemplary embodiments of the present invention will be described generally in the context of a turbine shell for purposes of illustration, one of ordinary skill in the art will readily appreciate that embodiments of the present invention are not limited to rotating a turbine shell unless specifically recited in the claims. 
       FIG. 1  provides a perspective view of an exemplary turbine shell  10  for illustrating various embodiments of the present invention. The turbine shell  10  generally extends along a length of a turbine and conforms to the outer perimeter of repeating stages of rotating blades and stationary vanes contained therein. In addition, the turbine shell  10  generally includes a circumferential flange  12  that may be used to connect multiple turbine shell  10  sections together to fully enclose the turbine. For example, the exemplary turbine shell  10  shown in  FIG. 1  may be placed on top of the turbine, and bolts  14  may be inserted through the circumferential flange  12  to engage with a complementary turbine shell (not shown) underneath the turbine. During maintenance, the bolts  14  may be removed, and a crane, davit, or other lifting device may be used to lift the turbine shell  10  away from the turbine. As shown in  FIG. 1 , the turbine shell  10  includes an axial center of gravity  16  along the longitudinal axis of the turbine shell  10 . 
       FIG. 2  provides a perspective view of a system  20  for rotating a turbine shell, such as the exemplary turbine shell  10  shown in  FIG. 1 , according to one embodiment of the present invention. The system  20  generally includes independent platforms, independent trunnions, and means for rotating one or more of the trunnions. The platforms are physically separated from one another to provide independent locations for each trunnion, and each trunnion is rotatably connected to a separate platform. In addition, each trunnion is configured for or adapted to fixedly connect to a particular portion of the turbine shell. For example, each trunnion may include one or more clamps, bolts, pins, or other structures for fixedly connecting to the turbine shell  10 . Once connected to the turbine shell  10 , a motor, chain fall, geared connection, or other suitable means may be used to rotate one or more of the trunnions as desired to rotate the turbine shell  10 . 
     In the particular embodiment shown in  FIG. 2 , for example, a first platform  22  is physically separated from a second platform  24 . The platforms  22 ,  24  may include one or more trusses  26  constructed from suitable materials for supporting the combined weight of the turbine shell  10 , trunnions, and associated components. In addition, the platforms  22 ,  24  may be variously sized to accommodate different sized turbine shells. First and second independent trunnions  30 ,  32  may be rotatably connected to the first and second platforms  22 ,  24 , respectively. Each trunnion  30 ,  32  has an axis of rotation  34  so that once the trunnions  30 ,  32  are connected to the turbine shell  10 , rotation of the trunnions  30 ,  32  will rotate the turbine shell  10 . 
     One or both of the platforms  22 ,  24  may include means for rotating the trunnions  30 ,  32 . The means may include, for example, a rotatable connection between each trunnion  30 ,  32  and its associated platform  22 ,  24  and an electric, pneumatic, or hydraulic motor or other gearing arrangement operably connected to rotate one or both of the trunnions  30 ,  32 . For example, as shown in  FIG. 2 , a roller  36  between each trunnion  30 ,  32  and its associated platform  22 ,  24  may provide the rotatable connection between each trunnion  30 ,  32  and its associated platform  22 ,  24 . In particular embodiments, the roller  36  may be fixedly attached to each platform  22 ,  24  and may include one or more wheels  38  to support the trunnions  30 ,  32  on the platforms  22 ,  24 . In addition, a motor  40  fixedly connected to one or both platforms  22 ,  24  may be drivingly engaged with the trunnions  30 ,  32  and/or rollers  36  to rotate the trunnions  30 ,  32 . In the particular embodiment shown in  FIG. 2 , the system  20  further includes a remote actuator  42  operably connected to the motor  40  so that an operator may remotely operate the motor  40  to rotate one or both trunnions  30 ,  32 . 
     One of ordinary skill in the art will readily appreciate that the orientation and/or alignment of the platforms  22 ,  24  with respect to one another directly affects the support provided to the trunnions  30 ,  32  and the amount of force required to rotate the turbine shell  10 . For example, the distance between the platforms  22 ,  24  must suitably align the rollers  36  under the trunnions  30 ,  32  so that the rollers  36  can adequately support the trunnions  30 ,  32 . In addition, if the first platform  22  is canted with respect to the second platform  24 , the rollers  36  may in turn be angled with respect to the trunnions  30 ,  32 , resulting in an unbalanced load applied by the trunnions  30 ,  32  on the rollers  36 . The unbalanced load on the rollers  36  will in turn require additional force to rotate the trunnions  30 ,  32  and/or rollers  36 . 
       FIG. 3  provides an enlarged perspective view a portion of the platforms  22 ,  24  shown in  FIG. 2 . As shown, the system  20  may further include means for determining a relative orientation between the platforms  22 ,  24 . The function of the means may include, for example, determining a distance between the platforms  22 ,  24  and/or an axial alignment of one platform  22  with respect to the other  24 . The structure for the means may include any mechanical, sonic, optic, magnetic, or geo-positioning device known to one of ordinary skill in the art for accurately measuring a distance, aspect, or location of an object. For example, the structure for determining the relative orientation between the platforms  22 ,  24  may include a retractable measuring tool, a sonic probe, a laser, a compass, or a geo-positioning system. In the particular embodiment shown in  FIG. 3 , a laser  50  is fixedly attached to the first platform  22 , and the laser transmits an optic pulse which is reflected off the second platform  24  back to the laser  50 . In this manner, the laser  50  may determine the distance between the platforms  22 ,  24  and/or angular position between the platforms  22 ,  24 . Alternately, or in addition, a reflector  52  fixedly attached to the second platform  24  may enhance the reflection back to the laser  50 , thereby increasing the precision and/or accuracy of the laser  50 . 
     The system  20  may further include means for aligning the platforms  22 ,  24  with respect to one another. The function of the means may include, for example, moving one or both platforms  22 ,  24  in one or more dimensions. For example, the means may raise or lower one or both platforms  22 ,  24 , may move one or both platforms  22 ,  24  linearly with respect to one another, and/or may rotate one or both platforms  22 ,  24 . The structure for the means may include jacks, wheels, or other devices suitable for supporting and/or moving one or more of the platforms  22 ,  24 . In the particular embodiment shown in  FIG. 3 , for example, a plurality of jacks  54  and wheels  56  may be operably connected to each platform  22 ,  24  to allow each platform  22 ,  24  to be raised, lowered, and moved in any direction. For example, the jacks  54  may be retracted so that the wheels  56  support the platforms  22 ,  24 . The platforms  22 ,  24  may then be manually positioned as desired to align the first platform  22  with respect to the second platform  24 . Once at the desired position, the jacks  54  may be extended as desired to lift one platform  22 ,  24  with respect to the other and/or to balance or level an individual platform. 
       FIG. 4  provides a flow diagram of a method for rotating a turbine shell according to one embodiment of the present invention, and  FIGS. 5-7  provide perspective views of the turbine shell  10  shown in  FIG. 1  being rotated by the system  20  shown in  FIG. 2 . At block  60 , the turbine shell  10  is disconnected from and removed from the turbine. For example, the bolts  14  may be removed from the flange  12 , and a crane, davit, or other device may be used to lift the turbine shell  10  away from the turbine. At block  62 , the trunnions  30 ,  32  are connected to the turbine shell  10 . As shown in  FIG. 5 , for example, the first trunnion  30  may be connected to a first portion  80  of the turbine shell  10 , and the second trunnion  32  may be connected to a second portion  82  of the turbine shell  10 . The trunnions  30 ,  32  may be aligned with the turbine shell  10  so that the axial center of gravity  16  of the turbine shell  10  substantially coincides with an axis of rotation  34  for each trunnion  30 ,  32 . In this manner, the weight of the turbine shell  10  will be evenly distributed to each trunnion  30 ,  32  as the turbine shell  10  rotates. 
     At block  64 , the trunnions  30 ,  32  are placed on the platforms  22 ,  24 , as shown in  FIG. 6 . At block  66 , the orientation of the platforms  22 ,  24  may be determined, and at block  68 , the platforms  22 ,  24  may be aligned with respect to one another as previously described and illustrated with respect to  FIG. 3  to suitably align the rollers  36  under the trunnions  30 ,  32 . One of ordinary skill in the art can readily appreciate that the steps described by blocks  66  and  68  may be performed before the trunnions  30 ,  32  are placed on the platforms  22 ,  24 . For example, by knowing the particular dimensions of the turbine shell  10  and the trunnions  30 ,  32 , the platforms  22 ,  24  may be oriented and aligned before the trunnions  30 ,  32  are placed on the platforms  22 ,  24 . In this manner, the weight of the platforms  22 ,  24  will be substantially less than after the trunnions  30 ,  32  are placed on the platforms  22 ,  24 , reducing the forces required to align the platforms  22 ,  24 . In addition, if desired, the orientation and alignment of the platforms  22 ,  24  may be repeated after the trunnions  30 ,  32  are placed on the platforms  22 ,  24 . 
     At block  70 , the motor  40  is energized to rotate the trunnions  30 ,  32 , and thus the turbine shell  10 , as shown in  FIG. 7 . 
     One of ordinary skill in the art will readily appreciate that the systems and methods described herein will reduce the time required to rotate turbine shells while also reducing the dangers inherent in manipulating such heavy components. Specifically, the systems and methods described herein reduce the time-consuming operations associated with cranes and/or installing and removing scaffolding that might otherwise be required to rotate the turbine shell  10 , thus reducing the required time to accomplish the desired maintenance or repairs. 
     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 include 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.