Patent Publication Number: US-2015078892-A1

Title: Eccentric coupling device and method for coupling mating casings in a turbomachine

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims filing benefit of U.S. Provisional Patent Application Ser. No. 61/878,770 having a filing date of Sep. 17, 2013, which is incorporated by reference herein in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present disclosure relates generally to turbomachines, such as gas turbine systems, and more particularly to methods and apparatus for coupling mating casings, such as turbine casings and exhaust casings, of turbomachines together. 
     BACKGROUND OF THE INVENTION 
     Turbomachines are widely utilized in fields such as power generation. For example, a conventional gas turbine system includes a compressor section, a combustor section, and at least one turbine section. The compressor section is configured to compress air as the air flows through the compressor section. The air is then flowed from the compressor section to the combustor section, where it is mixed with fuel and combusted, generating a hot gas flow. The hot gas flow is provided to the turbine section, which utilizes the hot gas flow by extracting energy from it to power the compressor, an electrical generator, and other various loads. 
     Various casings are typically utilized to encase and protect the various components of a turbomachine such as a gas turbine system. For example, a turbine casing may surround at least a portion of the turbine section of a gas turbine system, and an exhaust casing may surround at least a portion of the exhaust section of a gas turbine system. These casings are typically coupled together through the use of bolts which are extended through mating flanges of the casings. 
     However, the use of typically known coupling apparatus can present various disadvantages when coupling such sections together. For example, in some cases, it can be discovered during initial assembly of the turbine casing and exhaust casing, or other mating casings, that the respective alignment bore holes (which could be original bolt holes or additional aligment holes) defined in the respective flanges do not align. Such misalignment may also occur after initial assembly during reassembly after, for example, routine maintenance, repair or replacement activities. 
     Currently, when such misalignment occurs, new aligning bore holes must be drilled into the flanges for the bolts to be extended through. Such practice, however, is time-consuming and can weaken the respective flanges. 
     Accordingly, improved methods and apparatus for coupling mating casings of a turbomachine are desired in the art. In particular, methods and apparatus that can compensate for misalignments between the respective casings would be advantageous. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention. 
     In one embodiment, the present disclosure is directed to a coupling device for coupling a first casing and a second casing together. The first casing and second casing include mating bore holes defined in mating flanges thereof, which may be misaligned. The coupling device may include a bushing insertable and positionable within one of the mating bore holes, and a pin insertable and positionable within the bushing and the other of the mating bore holes. The bushing and pin may each include eccentric features which may facilitate insertion into the mating bore holes when the bore holes are misaligned, thus coupling the first casing and second casing together. 
     In another embodiment, the present disclosure is directed to a turbomachine. The turbomachine may include a first casing and an second casing, and may further include one or more coupling devices as disclosed herein for coupling the first casing and second casing together. 
     In another embodiment, the present disclosure is directed to a method for coupling a first casing and a second casing together. The method may include inserting a bushing into a bore hole defined in a flange of the first casing or the second casing, rotating the bushing to align with a mating bore hole defined in a flange of the other of the first casing or the second casing, inserting a pin into the bushing, rotating the pin to align with the mating bore hole defined in a flange of the other of the first casing or the second casing, and inserting the pin into the mating bore hole. The bushing and pin may each include eccentric features which may facilitate insertion into the mating bore holes when the bore holes are misaligned, thus coupling the first casing and second casing together. 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which: 
         FIG. 1  is a schematic view of a gas turbine system according to one embodiment of the present disclosure; 
         FIG. 2  is a side view of a gas turbine system according to one embodiment of the present disclosure; 
         FIG. 3  is a cross-sectional view of a coupling device coupling a first casing flange and an second casing flange together according to one embodiment of the present disclosure; 
         FIG. 4  is a bottom view of a bearing of a coupling device according to one embodiment of the present disclosure; and 
         FIG. 5  is a side cross-sectional view of a bearing of a coupling device according to one embodiment of the present disclosure; 
         FIG. 6  is a bottom view of a pin of a coupling device according to one embodiment of the present disclosure; and 
         FIG. 7  is a side view of a pin of a coupling device according to one embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. 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 various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with 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. 
       FIG. 1  is a schematic diagram of a turbomachine, which in the embodiment shown is a gas turbine system  10 . It should be understood that the turbomachine of the present disclosure need not be a gas turbine system  10 , but rather may be any suitable turbine system or other turbomachine, such as a steam turbine system or other suitable system. The system  10  as shown may include a compressor section  12 , a combustor section  14  which may include a plurality of combustors  15  as discussed below, and a turbine section  16 . The compressor section  12  and turbine section  16  may be coupled by a shaft  18 . The shaft  18  may be a single shaft or a plurality of shaft segments coupled together to form shaft  18 . The shaft  18  may further be coupled to a generator or other suitable energy storage device, or may be connected directly to, for example, an electrical grid. An inlet section  19  may provide an air flow to the compressor section  12 , and exhaust gases may be exhausted from the turbine section  16  through an exhaust section  20  and exhausted and/or utilized in the system  10  or other suitable system. Exhaust gases from the system  10  may for example be exhausted into the atmosphere, flowed to a steam turbine or other suitable system, or recycled through a heat recovery steam generator. 
     Referring now to  FIG. 2 , a side view of a gas turbine system  10  is illustrated. The gas turbine  10  system as shown is mounted to a base. As illustrated, gas turbine  10  includes various casings. For example, a turbine casing  32  is illustrated, which surrounds at least a portion of the turbine section  16 . Turbine casing  32  is generally cylindrical, and may be formed from one or more sections. For example, in exemplary embodiments, a turbine casing  32  may include an upper casing portion and a lower casing portion. The upper casing portion may typically be uncoupled from the lower casing portion for access to the turbine section  16 , etc. Alternatively, the turbine casing  32  may be formed from one, three, four or more components. Turbine casing  32  may further include a flange  38  disposed at a generally downstream end (with respect to a general direction of flow through the gas turbine system  10 ). The flange  38  may be generally cylindrical, and may include a plurality of bore holes  40  defined therein and spaced annularly around the flange  38 . Each bore hole  40  may extend generally along a longitudinal axis or centerline  42  that is generally parallel to a longitudinal axis  45  of the gas turbine system  10 . 
     Further, an exhaust casing  52  is illustrated, which surrounds at least a portion of the exhaust section  20 . Exhaust casing  52  is generally cylindrical, and may be formed from one or more sections. For example, in exemplary embodiments, an exhaust casing  52  may include an upper casing portion and a lower casing portion. The upper casing portion may typically be uncoupled from the lower casing portion for access to the exhaust section  20 , etc. Alternatively, the exhaust casing  52  may be formed from one, three, four or more components. Exhaust casing  52  may further include a flange  58  disposed at a generally upstream end (with respect to a general direction of flow through the gas turbine system  10 ). The flange  58  may be generally cylindrical, and may include a plurality of bore holes  60  defined therein and spaced annularly around the flange  58 . Each bore hole  60  may extend generally along a longitudinal axis or centerline  62  that is generally parallel to a longitudinal axis  45  of the gas turbine system  10 . 
     Other various casings are illustrated in  FIG. 2 . For example, an inlet casing  80 , compressor casing  82 , and compressor discharge casing  84  are illustrated. Similarly to the turbine casing  32  and exhaust casing  52 , such casings may be generally cylindrical and formed from one or more sections. Further, each casing  80 ,  82 ,  84  may include upstream and/or downstream flanges, which may abut with flanges of other casings to couple to casings together. For example, a downstream flange of inlet casing  80  may abut with an upstream flange of compressor casing  82 , a downstream flange of compressor casing  82  may abut with an upstream flange of compressor discharge casing  84 , and a downstream flange of compressor discharge casing  84  may abut with an upstream flange of turbine casing  32 . 
     As further illustrated in  FIGS. 2 and 3 , respective bore holes  40 ,  60  of the turbine casing  32  and the exhaust casing  52  may mate together to couple the turbine casing  32  and exhaust casing  52  together. For example, the respective flanges  38 ,  58  may abutted together, with the desire that the bore holes  40 ,  60  are generally aligned. As discussed above, in some cases, when the flanges  38 ,  58  are abutted together, bore holes  40 ,  60  may be slightly offset, such that the bore holes  40  are not aligned. For example, as illustrated in  FIG. 3 , bore holes  40 ,  60  may be misaligned such that the respective longitudinal axes  42 ,  62  of the bore holes  40 ,  60  are not co-axial. In these events, it may still be desirable, however, to couple the turbine casing  32  and exhaust casing  52  together. 
     Accordingly, and referring now to  FIGS. 3-7 , the present disclosure is further directed to coupling devices  100  for coupling first casings  32  and second casings  52  of turbomachines together. It should be understood that, while the present disclosure illustrates and describes embodiments wherein the turbine casing and exhaust casing are the first and second casings  32 ,  52 , any suitable turbomachine casings which include generally vertically extending flanges and axially extending bore holes are within the scope and spirit of the present disclosure. As shown in  FIG. 3 , a coupling device  100  extends through the mating bore holes  40 ,  60  of the flanges  38 ,  58  of the first casing  32  and second casing  52  when the flanges  38 ,  58  are abutted together. As shown, the longitudinal axes  42 ,  62  may not be co-axial, such that the bore holes  40 ,  60  are misaligned. Thus, a coupling device  100  according to the present disclosure may include eccentric features that facilitate extending the coupling device  100  through both mating bore holes  40 ,  60  to couple the first casing  32  and second casing  52  together, even when misaligned. 
     It should be noted that in exemplary embodiments, the bore holes  40 ,  60  have different widths (or diameters)  70 ,  72  and cross-sectional areas. For example, as shown, the width  70  of bore hole  40  is larger than the width  72  of bore hole  60 . Alternatively, the width  72  of bore hole  60  may be larger than the width  70  of bore hole  40 . Such relative widths may, in conjunction with the eccentric features as discussed herein, facilitate coupling the flanges  38 ,  58  together when misaligned. 
     As shown in  FIGS. 3-7 , coupling device  100  may include a bushing  102  and a pin  104 . The bushing  102  may generally fit within one of the mating bore holes  40 ,  60 , such as the first casing bore hole  40  as illustrated. Bushing  102  may thus include an outer surface  110  which, when engaged in a bore hole  40 ,  60 , is proximate or in contact with an inner surface  112  of the bore hole. Bushing  102  may further include a bore hole  114  extending therethrough along a longitudinal axis or centerline  116 . Advantageously, the bore hole  114  may be eccentrically positioned within the bushing  102 . For example, as shown, the longitudinal axis  116  of the bore hole  114  may be purposefully misaligned, and thus not co-axial with, a longitudinal axis or centerline  118  of the bushing  102 . As shown, the axes  116 ,  118  may be generally parallel but spaced apart and not-coaxial. Thus, when the bushing  102  is initially positioned within the bore hole  40 ,  60 , the bushing  102  can be rotated, such as about the longitudinal axis  118 , until the other mating bore hole  40 ,  60 , is roughly aligned with bore hole  114 . In this rough alignment, as illustrated in  FIG. 3 , the generally entire periphery of the other mating bore hole  40 ,  60 , is longitudinally contained in alignment within the bore hole  114 , such that pin  104  can be extended through bushing  102  and into bore hole  114 . 
     Pin  104  may generally fit within bushing  102 , such as the bore hole  114  thereof, as well the other mating bore hole  40 ,  60 , such as the second casing bore hole  60  as illustrated. For example, pin  104  may include a first portion  130  and a second portion  132 . The first portion  130  may generally fit within the bushing  102 , such as within the bore hole  114  thereof, while the second portion  130  may generally extend through the bushing  102  and generally fit within the other mating bore hole  40 ,  60 . The first portion  130  may thus include an outer surface  134  which, when engaged in the bore hole  114  of the bushing  102 , is proximate or in contact with an inner surface  136  of the bore hole  114 . The second portion  132  may include an outer surface  138  which, when engaged in the other mating bore hole  40 ,  60 , such as the second casing bore hole  60  as illustrated, is proximate or in contact with an inner surface  140  of the other mating bore hole  40 ,  60 . 
     Accordingly, in exemplary embodiments as illustrated, the second portion  132  may have a width and cross-sectional area that is less than a width and cross-sectional area of the first portion  130 . Further and advantageously, the second portion  132  may be eccentrically positioned relative to the first portion  130 . For example, as shown, a longitudinal axis or centerline  142  of the first portion  130  may be purposefully misaligned, and thus not co-axial with, a longitudinal axis or centerline  144  of the second portion  132 . As shown, the axes  142 ,  144  may be generally parallel but spaced apart and not-coaxial. Thus, when the pin  104  is initially being positioned within and/or relative to the bore hole  114  of the bushing  102 , the pin  104  can be rotated, such as generally about the longitudinal axis  142 , until the second portion  132  is aligned with the other mating bore hole  40 ,  60 . Once aligned, the second portion  132  can be extended into the other mating bore hole  40 ,  60 , with the first portion  130  thus positioned within the bore hole  114  of the bushing  102 . 
     Positioning and engagement of the pin  104  within the bushing  102  may thus couple the first casing  32  and second casing  52  together. Further, in some exemplary embodiments, the pin  104  and bushing  102  may be fixedly connected to the first casing  32  and/or second casing  52 , such as to the flanges  38 ,  58  thereof, once engaged in the bore holes  40 ,  60 . For example, the bushing  102  may be welded, brazed, bonded, affixed with an adhesive, or otherwise fixidly connected to the one of the bore holes  40 ,  60  that the bushing  102  is disposed within. The pin  104  may be welded, brazed, bonded, affixed with an adhesive, or otherwise fixidly connected to the bushing  102 . Such fixed connection may further facilitate coupling of the first casing  32  and second casing  52  by the coupling device  100 . 
     The present disclosure is further directed to method for coupling first casings  32  and second casings  52  together. A method may include, for example, abutting mating flanges  38 ,  58  of the first casing  32  and second casing  52  together. The method may further include inserting an eccentric bushing  102  into a bore hole  40 ,  60  defined in one of the mating flanges  38 ,  58 , and rotating the bushing  102  about a longitudinal axis  118  to align a bore hole  114  of the bushing  102  with a bore hole  40 ,  60  defined in the other of the mating flanges  38 ,  58 . The method may further include inserting an eccentric pin  104  into the bushing  102 , and rotating the pin  104  to align a portion thereof with the bore hole  40 ,  60  defined in the other of the mating flanges  38 ,  58 . The method may further include inserting the portion of the pin  104  into the other bore hole  40 ,  60 . It should be noted that in some embodiments, the pin  104  may be inserted and rotated after rotation of the bushing  102 , while in other embodiments, the pin  104  and bushing  102  may be rotated generally simultaneously. For example, in some embodiments, both the bushing  102  and pin  104  may be initially inserted. Both the bushing  102  and pin  104  may then be rotated into proper alignment. The portion of the pin  104  may then be inserted. 
     In some embodiments, a method according to the present disclosure may further include fixidly connecting the bushing  102  and the pin  104 , such as to the flange  38  and/or  58 . 
     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.