Abstract:
A system is provided that includes a first turbine alignment component for a turbine engine; and a shim comprises a metal foam. The shim mounts between a first surface of the first turbine alignment component and a second surface of a second turbine alignment component.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject matter disclosed herein relates to turbine engines and, more specifically, to assembly, support, and alignment of components of the turbine engines. 
         [0002]    In certain applications, turbines may include various sections designed to be assembled during installation. Each turbine may be encased by a turbine shell and its bearings supported by a “standard” (also referred to as a “pedestal) or exhaust frame. The turbine shells may include arms or other extensions that may be supported by the standard, such as through a vertical support on the standard itself. The turbine shells may also be vertically supported by legs that attach to ground. 
         [0003]    A bearing housing generally covers and protects the bearings of the turbine. During installation, the bearing housing is positioned such that the rotor is concentric with the turbine shell to avoid interference with the other components. Supports on the exhaust frame may engage a support part on the bearing housing to vertically and/or horizontally align and support the bearing housing. Clearances may increase or decrease during operation depending on the support of the exhaust frame and the bearing housing support part. These changes in clearance may introduce uncertainty in the position of the bearing relative to the stationary components and may result in rubbing or interference between such components. 
         [0004]    The turbine shell generally covers and protects the rotary components of the turbine. During installation, the turbine shell is generally aligned with rotary components to avoid interference with the components. Supports to ground may engage a support part on the turbine shell to vertically and/or horizontally align and support the turbine shell. Achieving desired clearances may be difficult due to thermal expansion of the support part and/or the support of the standards. For example, clearances may increase or decrease during operation depending on the configuration of the support of the standard and the support part. These changing clearances may introduce uncertainty in the position of the turbine shell relative to the rotary components and may eventually result in rubbing or interference between such components. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0005]    Certain embodiments commensurate in scope with the originally claimed invention are summarized below. These embodiments are not intended to limit the scope of the claimed invention, but rather these embodiments are intended only to provide a brief summary of possible forms of the invention. Indeed, the invention may encompass a variety of forms that may be similar to or different from the embodiments set forth below. 
         [0006]    In a first embodiment, a system includes a turbine engine having a turbine shell, a support assembly configured to support the turbine engine, wherein the support assembly comprises a keyway defined by at least first and second protrusions, a gib extending from the turbine shell and configured to mate with the keyway and a first shim disposed between the gib and one of the first protrusion, wherein the first shim comprises a metal foam. 
         [0007]    In a second embodiment, a system a first turbine alignment component for a turbine engine and a shim comprising a metal foam, wherein the shim mounts between a first surface of the first turbine alignment component and a second surface of a second turbine alignment component. 
         [0008]    In a third embodiment, a system includes a support feature for a turbine engine having a keyway having a bottom, a first side, and a second side opposite from the first side; a key configured to insert in the keyway and provide lateral alignment of a turbine shell of the turbine engine, and a first shim disposed in the keyway between the key and the first side, and a second shim disposed between the key and the second side, wherein the first shim and the second shim comprise a metal foam. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
           [0010]      FIG. 1  is a schematic flow diagram of an embodiment of a combined cycle power generation system having a gas turbine, a steam turbine, and a heat recovery steam generation (HRSG) system; 
           [0011]      FIG. 2  is a perspective view of a turbine standard and a turbine shell in accordance with an embodiment of the present invention; 
           [0012]      FIG. 3  is a schematic front view of a turbine support feature in accordance with an embodiment of the present invention; 
           [0013]      FIG. 4  is a stress/strain curve of a metal foam in accordance with an embodiment of the present invention; 
           [0014]      FIG. 5  is a perspective view of a keyway protrusion of the turbine support feature of  FIG. 3  in accordance with an embodiment of the present invention; and 
           [0015]      FIG. 6  is a perspective view of a keyway protrusion of the turbine support feature of  FIG. 3  in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
         [0017]    When introducing elements of various embodiments of the present invention, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. 
         [0018]    Embodiments of the present invention include a compliant shim (e.g., a metal foam shim) for aligning turbine components, e.g., turbine shells, of a steam or gas turbine, that are supported on a turbine support, e.g., a standard. The metal foam shim may be installed as a shim between a keyway of a turbine component and a gib of a turbine support. During operation, the metal foam shim may compress in response to thermal expansion of the hot turbine component to ensure that the desired clearances remain between the keyway and the gib. In some embodiments, a wear pad, e.g., a stellite wear pad, may be provided between the metal foam shim and the keyway to support any shear load exerted by the gib and/or the keyway. In certain embodiments, the thickness, relative density, and material for the metal foam shim may be chosen to ensure that the metal foam shim provides desired linear elasticity and long operating life. 
         [0019]      FIG. 1  is a schematic flow diagram of an embodiment of a combined cycle power generation system  10  having a gas turbine  12 , a steam turbine  22 , and a heat recovery steam generation (HRSG) system  32 . System  10  may employ one or more support features to align various components in the gas turbine  12 , the steam turbine  22 , and/or the HRSG  12 . As discussed below, the support features include one or more compliant shims (e.g., metal foam shims) to maintain suitable clearances despite thermal expansion of hot turbine components. 
         [0020]    The system  10  may include the gas turbine  12  for driving a first load  14 . The first load  14  may, for instance, be an electrical generator for producing electrical power. The gas turbine  12  may include a turbine  16 , a combustor or combustion chamber  18 , and a compressor  20 . The system  10  may also include the steam turbine  22  for driving a second load  24 . The second load  24  may also be an electrical generator for generating electrical power. However, both the first and second loads  14 ,  24  may be other types of loads capable of being driven by the gas turbine  12  and steam turbine  22 . In addition, although the gas turbine  12  and steam turbine  22  may drive separate loads  14  and  24 , as shown in the illustrated embodiment, the gas turbine  12  and steam turbine  22  may also be utilized in tandem to drive a single load via a single shaft. In the illustrated embodiment, the steam turbine  22  may include one low-pressure section  26  (LP ST), one intermediate-pressure section  28  (IP ST), and one high-pressure section  30  (HP ST). However, the specific configuration of the steam turbine  22 , as well as the gas turbine  12 , may be implementation-specific and may include any combination of sections. 
         [0021]    Each section of the steam turbine  22 , e.g., the low pressure section  26 , the intermediate pressure section  28 , and the high-pressure section  30 , may be generally supported and separated by mid standards  29  (e.g., pedestals). Similarly, end standards  31  (e.g., pedestals) may be generally support the ends of the high pressure section  30  and the low pressure section  26 . The standards  29  and  31  may be disposed along the axis of the turbine  22 , and may include various components such as supports, pickups, and piping between the turbine sections  26 ,  28 , and  30 . As described in detail below, the standards  29  and  31  may also provide for lateral (i.e., horizontal) alignment of the turbine shells of the sections  26 ,  28 , and  30 , though engagement of a gib and keyway. The engagement between the gib and the keyway may be adjusted through the use the metal foam shims described herein. It should be appreciated that the gas turbine  12  may also include a similar arrangement of one or more sections and standards, and the gas turbine  12  may also utilize a gib, keyway, and metal foam shims for lateral alignment, as discussed below. 
         [0022]    The system  10  may also include the multi-stage HRSG  32 . The components of the HRSG  32  in the illustrated embodiment are a simplified depiction of the HRSG  32  and are not intended to be limiting. Rather, the illustrated HRSG  32  is shown to convey the general operation of such HRSG systems. Heated exhaust gas  34  from the gas turbine  12  may be transported into the HRSG  32  and used to heat steam used to power the steam turbine  22 . Exhaust from the low-pressure section  26  of the steam turbine  22  may be directed into a condenser  36 . Condensate from the condenser  36  may, in turn, be directed into a low-pressure section of the HRSG  32  with the aid of a condensate pump  38 . 
         [0023]    The condensate may then flow through a low-pressure economizer  40  (LPECON), a device configured to heat feedwater with gases, which may be used to heat the condensate. From the low-pressure economizer  40 , a portion of the condensate may be directed into a low-pressure evaporator  42  (LPEVAP) while the rest may be pumped toward an intermediate-pressure economizer  44  (IPECON). Steam from the low-pressure evaporator  42  may be returned to the low-pressure section  26  of the steam turbine  22 . Likewise, from the intermediate-pressure economizer  44 , a portion of the condensate may be directed into an intermediate-pressure evaporator  46  (IPEVAP) while the rest may be pumped toward a high-pressure economizer  48  (HPECON). Steam from the intermediate-pressure evaporator  46  may be sent to the intermediate-pressure section  28  of the steam turbine  22 . Again, the connections between the economizers, evaporators, and the steam turbine  22  may vary across implementations as the illustrated embodiment is merely illustrative of the general operation of an HRSG system that may employ unique aspects of the present embodiments. 
         [0024]    Finally, condensate from the high-pressure economizer  48  may be directed into a high-pressure evaporator  50  (HPEVAP). Steam exiting the high-pressure evaporator  50  may be directed into a primary high-pressure superheater  52  and a finishing high-pressure superheater  54 , where the steam is superheated and eventually sent to the high-pressure section  30  of the steam turbine  22 . Exhaust from the high-pressure section  30  of the steam turbine  22  may, in turn, be directed into the intermediate-pressure section  28  of the steam turbine  22 . Exhaust from the intermediate-pressure section  28  of the steam turbine  22  may be directed into the low-pressure section  26  of the steam turbine  22 . 
         [0025]    An inter-stage attemperator  56  may be located in between the primary high-pressure superheater  52  and the finishing high-pressure superheater  54 . The inter-stage attemperator  56  may allow for more robust control of the exhaust temperature of steam from the finishing high-pressure superheater  54 . Specifically, the inter-stage attemperator  56  may be configured to control the temperature of steam exiting the finishing high-pressure superheater  54  by injecting cooler feedwater spray into the superheated steam upstream of the finishing high-pressure superheater  54  whenever the exhaust temperature of the steam exiting the finishing high-pressure superheater  54  exceeds a predetermined value. 
         [0026]    In addition, exhaust from the high-pressure section  30  of the steam turbine  22  may be directed into a primary re-heater  58  and a secondary re-heater  60  where it may be re-heated before being directed into the intermediate-pressure section  28  of the steam turbine  22 . The primary re-heater  58  and secondary re-heater  60  may also be associated with an inter-stage attemperator  62  for controlling the exhaust steam temperature from the re-heaters. Specifically, the inter-stage attemperator  62  may be configured to control the temperature of steam exiting the secondary re-heater  60  by injecting cooler feedwater spray into the superheated steam upstream of the secondary re-heater  60  whenever the exhaust temperature of the steam exiting the secondary re-heater  60  exceeds a predetermined value. 
         [0027]    In combined cycle systems such as system  10 , hot exhaust gas  34  may flow from the gas turbine  12  and pass through the HRSG  32  and may be used to generate high-pressure, high-temperature steam. The steam produced by the HRSG  32  may then be passed through the steam turbine  22  for power generation. In addition, the produced steam may also be supplied to any other processes where superheated steam may be used. The gas turbine  12  cycle is often referred to as the “topping cycle,” whereas the steam turbine  22  generation cycle is often referred to as the “bottoming cycle.” By combining these two cycles as illustrated in  FIG. 1 , the combined cycle power generation system  10  may lead to greater efficiencies in both cycles. In particular, exhaust heat from the topping cycle may be captured and used to generate steam for use in the bottoming cycle. 
         [0028]      FIG. 2  is a perspective view of a turbine standard  70 , e.g., a mid standard  29  or end standard  31 , supporting a turbine shell  72 , e.g., a shell of the low pressure section  26 , the intermediate pressure section  28 , or the high-pressure section  30 . The standard  70  may include an upper half  74  and a lower half  76 , and the turbine shell  72  may include an upper half turbine shell  78  or a lower half turbine shell  80 . The turbine shell  72  may be generally supported and aligned by a support feature disposed on the standard  70 , such as in the region indicated by arrow  79 . The support feature may laterally align and support the turbine shell  72  along the x-axis, such as in the directions indicated by arrows  81 , through engagement of a gib and keyway and adjustment of one or more metal foam shims. As noted above, the gas turbine  12  may also use a support feature to laterally align one or shells of the gas turbine with standards in a similar manner. 
         [0029]      FIG. 3  is a schematic view of a turbine support feature  82  in accordance with an embodiment of the present invention. As shown in  FIG. 3 , the turbine support feature  82  may include a keyway  84  on the standard  70  and a protrusion, e.g., gib  86  (also referred to as a “key”), extending from the lower turbine shell half  80 . They keyway  84  may be defined by protrusions  88  extending from the standard  70 . The space  83  between the protrusions  88  may define the keyway  84 . In some embodiments, the protrusions may be machined from the standard  70 , welded onto the standard  70 , or manufactured by any suitable technique. The gib  86  is configured to mate with the keyway  84  and provide alignment and support of the turbine shell  72  along the x-axis. 
         [0030]    The clearance between the keyway  84  and the gib  86  may be set during “cold” conditions, e.g., when the turbine section is not in operation and is below operating temperatures. For example, some lateral clearance may be provided between the protrusions of the keyway  84  and the gib  86  to prevent damage to the gib  86 . During operation, as the turbine section and the turbine shell  72  heat, the gib  86  may thermally expand inside the keyway  84 . To ensure the desired fit between the gib  86  and the keyway  84 , one or more compliant shims (e.g., metal foam shims)  90  may be disposed between the gib  86  and each protrusion  88  that define the keyway  84 . For example, as shown in  FIG. 3 , a first metal foam shim  90 A may be inserted between one side of the gib  86  and the protrusion  88 , and a second metal foam shim  90 B may be inserted between a second side of the gib  86  and the protrusion  88 . As the turbine shell  70  heats and the gib  86  grows within the keyway  84 , the metal foam shims  90  may be compressed to maintain the desired clearances between the gib  86  and the sides of the keyway  84 . 
         [0031]    As described further below, the metal foam shims  90  may include FeCrAlY foams, stainless foams, copper foams, Inconel foams, nickel foams, aluminum foams, or any suitable foam, and the thickness, relative density, and material for the metal foam may be selected to ensure that the metal foam maintains linear elasticity in response to the forces exerted by the expanding gib  86 . Further, the metal foam shims  90  may be compliant enough to prevent damage to the gib  86  and/or the keyway  84  during thermal expansion of gib  86 , yet retain enough stiffness to maintain a desired lateral alignment between the gib  86  and the keyway  84  and, thus, maintain alignment of the turbine shell  70 . Advantageously, the metal foam enables adjustment of the support feature when cold to provide easier assembly. Additionally, the metal foam shim  90  in the support feature eliminates or minimizes any cold or hot lateral position uncertainty and enables achievement of tighter clearances between static and rotating parts of the turbine. 
         [0032]    As mentioned above, the metal foam may be selected to provide the desired linear elasticity, such as by selecting a metal foam having a desired yield strength or Young&#39;s modulus. As will be appreciated, both the yield strength and the Young&#39;s modulus may be a function of the relative density.  FIG. 4  depicts a stress/strain curve  94  for an exemplary metal foam, e.g., an FeCrAlY metal foam having a 15% relative density. As shown in  FIG. 4 , the y-axis corresponds to the stress (lbf/in 2 ) of the metal foam for a given strain (in/in) on the x-axis. The linear region  96  corresponds to those portion of the stress/strain curve of the FeCrAlY metal foam that exhibit a linear elasticity. For example, in the linear region depicted in  FIG. 4 , the Young&#39;s modulus of a FeCrAlY metal foam may be approximately 61259 psi. Other regions may include a plateau region  98  in which the stress of the metal foam does not change with respect to the strain, and a densification region  99  in which the metal foam increases in density and stress rapidly increases in response to strain. 
         [0033]    Thus, when selecting a metal foam for use as a shim in the manner described above, the metal foam may be selected to ensure that the metal foam provides linear elasticity up to the strain expected to be induced in the metal foam shim during operation of the turbine and expansion of the turbine shell  70 . As mentioned above, the metal foam may include FeCrAlY foams, stainless foams, copper foams, Inconel foams, nickel foams, aluminum foams, or any suitable metal foam. Further, the metal foam may be include open cell metal foams or closed cell metal foams. Additionally, the metal foams used may have a relative density of greater than about 5%, such as at least approximately 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, or greater. 
         [0034]    For example, referring to the gib  86  and keyway  84  described above in  FIG. 3 , for a gib  86  having a width of approximately 6 inches, a height of approximately 8 inches, and a length of approximately 20 inches, and for a steady-state gib temperature of 600° F. and 300° F., the stress generated in a 15% relative density FeCrAlY metal foam, is about 860 psi and within the linear elastic region  96  depicted in  FIG. 4 . In addition, for such an embodiment, the total lateral force generated on the metal foam is 137,600 lbf. 
         [0035]    In some embodiments, the metal foam shim  90  may be used with additional components.  FIG. 5  depicts a perspective view of an embodiment of the keyway protrusion  88  having a wear pad  100  and a keeper plate  102 , and  FIG. 6  depicts a perspective view of the keyway protrusion  88  without the keeper plate  102 . As shown in  FIG. 5 , the wear pad  100  may absorb some or all of the shear load, indicated by arrow  104 , exerted by the gib  86  on the keyway protrusion  88 . As shown in  FIG. 6 , the wear pad  100  may be disposed between the metal foam shim  90  and the gib  86 . In some embodiments, the wear pad  100  may be stellite, steel, or any other suitable material or combination thereof. The keeper plate  102  may be used to retain the metal foam shim  90  and the wear pad  100  in alignment with the keyway protrusion  88 . For example, the keeper plate  102  may retain the wear pad  100  against any shear load exerted on the pad in the direction illustrated by arrow  104 . As also shown in  FIGS. 5 and 6 , the wear pad  100  may be mechanically secured to the metal foam shim  90  by one or more fasteners  106 , such as nails, screws, bolts, rivets, or any other suitable fastener. In other embodiments, the wear pad  100  may be joined to the metal foam shim  90  with a braze, a weld, an adhesive, or any other suitable process. Thus, in some embodiments, the wear pad  100  and metal foam shim  90  may be joined together to form a single component, while in other embodiments the wear pad  100  may be a separate component from the metal foam shim  90 . In other embodiments, the wear pad  100  may be omitted and the metal foam shim  90  may be the only component disposed between the gib  86  and the keyway protrusion  88 . Similarly, the keeper plate  102  may be mechanically secured to the keyway protrusion  88  by one or more fasteners  108 , such as nails, screws, or any other suitable fastener. As also shown in  FIG. 6 , the protrusion  88  may include a recess  110  configured to position and/or receive the shim  90  in a specific area of the protrusion  88 . This recess  110  may be defined by one or more indentations in or extensions of the inner surface of the protrusion  88 . In some embodiments, one or more protrusions  88  defining the keyway  84  may include a recess. 
         [0036]    It should be appreciated that in other embodiments, the keyway may be located on the turbine shell  70  and the gib  86  may be located on the turbine standard. In such embodiments, the metal foam shim  90  may be used to provide desired clearances between the gib and keyway in the manner described above. Further, it should be appreciated that the compliant shims (e.g., metal foam shims) described above may be used in other support features having, for example, a first and second alignment feature, male and female alignment features, etc. 
         [0037]    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 have 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 language of the claims.