Compressible supports for turbine engines   

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to turbine engines and, more specifically, to assembly, support, and alignment of components of the turbine engines.

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.

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.

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.

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.

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.

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.

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

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:

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;

FIG. 2 is a perspective view of a turbine standard and a turbine shell in accordance with an embodiment of the present invention;

FIG. 3 is a schematic front view of a turbine support feature in accordance with an embodiment of the present invention;

FIG. 4 is a stress/strain curve of a metal foam in accordance with an embodiment of the present invention;

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

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

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\' 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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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 90A may be inserted between one side of the gib 86 and the protrusion 88, and a second metal foam shim 90B 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.

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.

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\'s modulus. As will be appreciated, both the yield strength and the Young\'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/in2) 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\'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.

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.

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.

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.

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.

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.