Patent Application
20140030083
The present invention relates generally to turbomachinery, and more particularly relates to an article of manufacture configured for use with turbomachines.
A conventional gas turbine generally operates on the principle of compressing air within a compressor, and then delivering the compressed air to a combustion chamber where fuel is added to the air and ignited. Afterwards, the resulting combustion mixture is delivered to the turbine section of the engine, where a portion of the energy generated by the combustion process is extracted by a turbine to drive the compressor via a shaft.
In multi-stage compressor sections, stators vanes are placed at the entrance and exit of the compressor section, as well as between each compressor stage, for purposes of properly directing the airflow to each successive compressor stage. As a result, stator vanes are able to enhance engine performance by appropriately influencing air flow and pressure within the compressor section.
Each stator stage generally consists of an annular array of airfoils, or vanes. A stator stage is typically formed in segments as stator vane units consisting of one or more airfoils supported by the base. These stator vane units are then individually mounted to the compressor casing to form an annular array, so that the airfoils project radially between an adjacent pair of rotor stages.
Stator vanes in an industrial gas turbine compressor are loaded and unloaded during start-stop cycles. In addition, the vanes are subject to small pressure fluctuations during operation. These result in relative motion between the vane base and the casing in which the vanes are assembled. The relative motion results in wear of both the vane base and casing, which, in turn, results in loose vanes. The loose vanes become more susceptible to relative motion and begin to chatter. Repair or replacement of the vanes may be required. Similar problems exist between stator ring segments, which hold a plurality of stator vanes, the stator ring segments being mounted in slots of the compressor casing.
Each stator vane 25 has an airfoil 40 that extends upwards from a base 45 and radially inward towards the shaft of the compressor rotor (not shown). The airfoil 40, and stator vanes 25, are interposed between the rotor blades (not shown). Certain stator stages of a compressor may mount stator vanes directly in a slot in the casing. Other stator stages mount stator vanes in ring segments, which are then mounted in slots of the casing.
The stator vanes 25 for an individual stage are sequentially placed in the slot 70 of the casing 15 until the full circumferential run of the slot has been filled with a designated number of stator vanes.
Other stages of stator vanes may be attached to the casing using ring segment assemblies. The ring segment assembly includes a ring segment and one or more stator vanes. Ring segments typically hold a plurality of stator vanes. After the ring segments have been loaded with stator vanes, the ring segments are slid into circumferential slots in the turbine/compressor casing and are butted against each other to sequentially fill the circumferential slots. Blades that are larger and have more forces placed on them may be assembled using this vane and ring segment assembly to provide a stiffer base mount.
The ring segment 90 slides into the circumferential slot 70 of the casing 15. The sidewalls 105 of the ring segment 90 are supported axially by the sidewalls 110 of the slot 70 when the ring segment 90 is within the slot 70. The square base dovetail 115 of the ring segment 90 fits into the grooves 120 of the circumferential slot 70, thereby retaining the ring segments 90 in the circumferential slot 70. Ring segments 90 are sequentially placed in the slot 70 of casing 15 until the slot 70 is filled with the design number of ring segment assemblies.
During initial assembly of turbomachine components, or subsequent repair and replacement of turbomachine components, a large number of components must be installed in specific locations of the turbomachine. For example, a stage one stator vane must be installed in the correct position in a stage one stator case. A typical turbomachine may have many stages with many corresponding components, so a high probability exists that a component for a specific stage may get installed in an incorrect stage (e.g., a stage five stator vane might get installed in a stage six stator slot). The negative implications of this event lead to machine malfunction or inefficiency and increase outage or construction time due to the need to remove and correctly install the specific components. Accordingly, a need still exists for an improved system for installing turbomachine components that reduces the probability for errors during installation.
According to one aspect of the present invention, an article of manufacture is provided having a first component configured for use with a stator of a turbomachine. The first component is configured for attachment to a second component. The second component is also configured for use with the stator of the turbomachine. The first component is configured to substantially reduce the possibility of installation in an undesired stage of the stator by modification of at least one characteristic of the first component. The second component is configured to substantially reduce the possibility of installation in an undesired stage of the stator by modification of at least one characteristic of the second component.
According to another aspect of the present invention, an article of manufacture is provided having a first component configured for use with a stator of a turbomachine. The first component is configured for attachment to a second component, and the second component is configured for use with the stator of the turbomachine. A third component is configured for use with the stator of the turbomachine, and the third component is configured for attachment to the second component. The first component is configured to substantially reduce the possibility of installation in an undesired stage of the stator by modification of at least one characteristic of the first component. The second component is configured to substantially reduce the possibility of installation in an undesired stage of the stator by modification of at least one characteristic of the second component. The third component is configured to substantially reduce the possibility of installation in an undesired stage of the stator by modification of at least one characteristic of the third component.
According to yet another aspect of the present invention, an article of manufacture configured for use with a turbomachine is provided. The article of manufacture includes a stator having an upper half and a lower half. The upper half has one or more upper half locker segments and a plurality of upper half pack segments. The plurality of upper half pack segments are located circumferentially between the one or more upper half locker segments. The lower half has one or more lower half locker segments and a plurality of lower half pack segments. The plurality of lower half pack segments are located circumferentially between the one or more lower half locker segments. At least one characteristic of the upper half is different than at least one characteristic of the lower half.
These and other features and improvements of the present invention should become apparent to one of ordinary skill in the art upon review of the following detailed description when taken in conjunction with the several drawings and the appended claims.
One or more specific aspects/embodiments of the present invention will be described below. In an effort to provide a concise description of these aspects/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 machine-related, 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. Any examples of operating parameters and/or environmental conditions are not exclusive of other parameters/conditions of the disclosed embodiments. Additionally, it should be understood that references to “one embodiment”, “one aspect” or “an embodiment” or “an aspect” of the present invention are not intended to be interpreted as excluding the existence of additional embodiments or aspects that also incorporate the recited features. A turbomachine is defined as a machine that transfers energy between a rotor and a fluid or vice-versa, including but not limited to gas turbines, steam turbines and compressors.
Referring now to the drawings,
The compressor rotor blades 502 impart kinetic energy to the airflow and therefore bring about a desired pressure rise. Directly following the rotor blades 502 is a stage of stator vanes 504. However, in some designs the stator vanes 504 may precede the rotor blades 502. Both the rotor blades 502 and stator vanes 504 turn the airflow, slow the airflow velocity (in the respective airfoil frame of reference), and yield a rise in the static pressure of the airflow. Typically, multiple rows of rotor/stator stages are arranged in axial flow compressors to achieve a desired discharge to inlet pressure ratio. Each rotor blade and stator vane includes an airfoil, and these airfoils can be secured to rotor wheels or a stator case by an appropriate attachment configuration, often known as a “root,” “base” or “dovetail”. In addition, compressors may also include inlet guide vanes (IGVs) 506, variable stator vanes (VSVs) 508 and exit or exhaust guide vanes (EGVs) 510. All of these blades and vanes have airfoils that act on the medium (e.g., air) passing through the compressor flow path 500.
Exemplary stages of the compressor 501 are illustrated in
The rotor blades 502 and stator vanes 504 herein of the compressor 501 are merely exemplary of the stages of the compressor 502 within the scope of the invention. In addition, each inlet guide vane 506, rotor blade 502, stator vane 504, variable stator vane 508 and exit guide vane 510 may be considered an article of manufacture. Further, the article of manufacture may comprise a stator vane and/or a stator casing and/or a ring segment configured for use with a compressor.
Aspects of the present invention provide a collection of strategically defined geometric features incorporated on the stator vanes, ring segments (also referred to as stator vane attachments), and casing slots for a unique configuration of the stator vane assembly. This unique configuration prevents mis-assembly due to assembly errors. Assembly errors occur when a stator vane or ring segment is installed in the wrong stage or the wrong half of the casing. For example, a stator vane or ring segment may be designed for an upper half of the compressor, but assembly error leads to installion in the lower half of the compressor. Further, this unique configuration provides a physical method of mis-assembly proofing where the wrong method of installion may not be visually apparent. For example, it would be difficult to place a stage five stator vane in a stage thirteen stator slot, however, it would be very easy to interchange (and install incorrectly) a stage eleven stator vane with a stage twelve stator vane. Adjacent stages may have very similarly sized components, and even though these sizes may look visually insignificant (or hard to detect), the improper installation of components can lead to severe machine damage and loss of efficiency.
It is to be understood that the invention is not to be limited to only the examples shown, and that the invention also includes embodiments where the aft groove has a smaller radial height than the forward radial groove, the forward and aft radial grooves have different axial depths, the forward and aft radial grooves have different geometrical cross-sectional shapes and/or the forward and aft radial grooves have different radial heights or are located at different radial heights. It is also to be understood that the invention also includes embodiments where the forward sidewall has a larger radial height than the aft sidewall.
Ring segments may also be installed backwards when the cross-sectional profile of the ring segment is symmetrical. When this happens, machine efficiency is reduced and damage may occur. According to another aspect of the present invention, the ring segment 720 has a generally trapezoidal or quadrilateral cross-sectional profile. The radial height 740 of the forward sidewall/surface 732 is configured to be different than the radial height 742 of the aft sidewall/surface 734, and these heights may be measured from the base of the respective sidewalls or from the bottom surface of the ring segment. The radial height 740 is shown to be smaller than radial height 742, but it is to be understood that the radial height 740 could also be configured to be larger than radial height 742.
In addition, the radial height 744 of the forward projection 736 may be configured to be smaller than the radial height 746 of the aft projection 738. As one example only, the radial height 744 of the forward projection 736 may be about 0.25 inches while the radial height 746 of the aft projection 738 may range between about 0.30 inches and about 0.50 inches. The purpose of the difference in radial heights (between forward and aft projections) is to ensure that the ring segment 720 is not installed backwards in the stator casing slot. Further, adjacent or nearby stages may have different radial heights for the aft projection (and/or different radial heights for the forward projection) to further error-proof installation.
A lower half 902 may include a lower half left half locker segment 921, a lower half right half locker segement 922, and a plurality of m-pack segments 923-929. However, it is to be understood that more or less m-pack segments could be used as desired in the specific application, as long as there are a different number of n and m pack segments. Each of the m-pack segments span an angle of θm and have a circumferential length or arc length of ARCm. θm may be referred to as the span angle. The lower half m-segments may be referred to collectively as the m-Pack.
According to an aspect of the present invention, and to aid in fool proofing installation of stator components, the stator has a different number of n-pack segments than m-pack segments. As shown, there are fewer n-pack segments than m-pack, but this could be reversed to have more m-pack segments than n-pack segments as desired in the specific application. The angle of θn is also configured to be different than the angle θm, and in the example shown θn is greater than θm. However, it is to be understood that in some applications it may be desirable to have θm be greater than θn. The difference in angles also leads to a difference in segment arc length, as the arc length ARCn is greater than the arc length ARCm. However, it is to be understood that in some applications it may be desirable to have ARCm be greater than ARCn.
According to an aspect of the present invention, an article of manufacture configured for use with a turbomachine has a stator 900 having an upper half 901 and a lower half 902. The upper half 901 has one or more upper half locker segments 911, 912 and a plurality of upper half pack segments 913-916. The upper half pack segments 913-916 are located circumferentially between the one or more upper half locker segments 911, 912. The lower half 902 has one or more lower half locker segments 921, 922 and a plurality of lower half pack segments 923-929. The lower half pack segments 923-929 are located circumferentially between the lower half locker segments 921, 922. At least one characteristic of the upper half 901 is different than at least one characteristic of the lower half 902. The characteristics of both the upper half 901 and lower half 902 are chosen from one, all or a portion of, the number of pack segments, the pack segment span angle θn or m, and pack segment arc length ARCn or ARCm.
The various features of the stator, according to an aspect of the present invention, are used to fool proof installation of stator components. It can be seen that by physically changing the stator segments so that the number of n-pack segments are different from the number of m-pack segments, configuring the angle θn to be different from the angle θm and by configuring the arc length ARCn to be different than the arc length ARCm, that it is now extremely difficult, if not impossible, to improperly install the stator components.
Aspects of the present invention provide, an article of manufacture comprising a first component (e.g., stator vane 800) configured for use with a stator of a turbomachine. The first component (e.g., stator vane 800) is configured for attachment to a second component (e.g., ring segment 720) also configured for use with the stator of the turbomachine. The first component (e.g., stator vane 800) is configured to substantially reduce the possibility of installation in an undesired stage of the stator by modification of at least one characteristic of the first component. The second component (e.g., ring segment 720) is configured to substantially reduce the possibility of installation in an undesired stage of the stator by modification of at least one characteristic of the second component.
The characteristic of the stator vane 800 may be chosen from one, all, or a portion of, the radial height 821 of a forward sidewall 811, the radial height 822 of an aft sidewall 812, and an axial length 850. The characteristic of the ring segment 720 may be chosen from one, all, or a portion of, the radial height 740 of a forward surface 732, the radial height 742 of an aft surface 734, the radial height 744 of a forward projection 736, the radial height 746 of an aft projection 738, and an axial length 730.
The article of manufacture may also include a third component (e.g., stator casing slot 604) configured for use with the stator of the turbomachine. The third component is also configured for attachment to the second component (e.g., ring segment 720). The third component (e.g., stator casing slot 604) is configured to substantially reduce the possibility of installation in an undesired stage of the stator by modification of at least one characteristic of the third component. The characteristic of the stator casing slot 604 may be chosen from one, all, or a portion of, the radial height 620 of a forward sidewall 606, a radial height 630 of an aft sidewall 607, a radial height of a forward groove 612, a radial height of an aft groove 613, and an axial length 605 or 610.
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 languages of the claims.
