Patent Application
20170159446
The subject matter disclosed herein relates generally to turbine engines and more particularly, to a methods and systems for determining rotor blade wear in turbine engines.
At least some known turbines have a defined flow path that includes, in serial-flow relationship, an inlet, a turbine, and an outlet. At least some known turbines also include a plurality of stationary stators that direct a fluid flow towards a rotor assembly that includes at least one row of turbine buckets (blades) that are circumferentially-spaced about a rotor disk. The fluid flow channeled to the rotor assembly from the stationary stators impacts airfoils of the turbine buckets to induce rotation of the rotor assembly.
During operation of a gas turbine engine, a turbine blade can tilt or expand due to creep from exposure to a high temperature fluids and centrifugal forces. When a tip of the turbine blade contacts a casing of the gas turbine engine, the tip can wear over time. At least some known turbine blades are able to withstand a certain amount of wear before requiring replacement. Typically, to inspect a turbine for quantitative wear of the turbine blades, the turbine is disassembled and the blades are removed and taken to a service center. Precise instrumentation is then used at the service center to measure various parameters of the turbine blades to qualitatively determine an amount of wear on the blades and also a determination of the remaining service lifetime of the blade. Such inspection methods require a significant amount of turbine outage time and also increased maintenance and service costs associated with turbine disassembly and measurement equipment usage.
In one aspect, a turbine engine system is provided. The turbine engine system includes a component positioned such that the component is subject to wear. The component includes an outer surface configured to be subjected to wear and a wear indication feature formed in the outer surface. The wear indication feature includes a first dimension at the outer surface and a second dimension at an inward location relative to the outer surface. The second dimension is different from the first dimension.
In another aspect, a method of servicing a turbine engine is provided. The method includes forming at least one wear indication feature on a component of the turbine engine, wherein the at least one wear indication feature includes a first dimension. The method also includes operating the turbine engine such that the component is subjected to wear. The wear indication feature is then measured to determine a second dimension of the wear indication feature. A wear condition of the component is then determined based on the second dimension.
In yet another aspect, a wear indication system is provided. The wear indication system includes a stationary component and a rotating component positioned proximate the stationary component. The rotating component includes a radially outer surface configured to contact the stationary component. The wear indication system also includes a wear indication feature formed in the radially outer surface. The wear indication feature includes a first dimension at the radially outer surface and a second dimension at a radially inward location of the radially outer surface. The second dimension is different from the first dimension.
The exemplary apparatus and methods described herein overcome at least some disadvantages of known systems and methods for use in determining an amount of wear of an internal component of a turbine. Moreover, the apparatus and methods described herein enable a reliable quantitative determination of the amount of wear of the internal component of the turbine to be determined. More specifically, the embodiments described herein each include at least one wear indication feature formed on a radially outer surface of an internal component of the turbine, such as a bucket tip cover. The wear indication feature includes a first dimension at the radially outer surface. When wear occurs, the radially outer surface is worn down such that the wear indication feature includes a second dimension radially inward of the initial radially outer surface. Without removing the buckets from the turbine engine, the second dimension can be measured and compared to the first dimension to determine the wear condition associated with the remaining service lifetime of the component. Although the illustrated apparatus and methods described herein are directed toward a steam turbine, the present disclosure is not limited to steam turbines. Thus, the scope of the present disclosure encompasses other types of turbines, including, but not limited to, gas and water turbines.
As used herein, the term “turbine bucket” is used interchangeably with the term “bucket” and thus can include any combination of a bucket that includes a platform and a dovetail, and/or a bucket that is integrally formed with a rotor disk, either embodiment of which may include at least one airfoil segment.
An annular divider 54 extends radially inwardly between HP section 18 and IP section 20 from central section 34 towards rotor assembly 16. More specifically, divider 54 extends circumferentially about rotor assembly 16 between HP steam inlet 36 and IP steam inlet 38.
During operation, steam is channeled to turbine 12 from a steam source, for example, a power boiler (not shown), wherein steam thermal energy is converted to mechanical rotational energy by turbine 12, and subsequently electrical energy by generator 14. More specifically, steam is channeled through HP section 18 from HP steam inlet 36 to impact rotor assembly 16 positioned within HP section 18 and to induce rotation of rotor assembly 16 about axis 42. Steam exits HP section 18 and is channeled to a boiler (not shown) that increases a temperature of the steam to a temperature that is approximately equal to a temperature of steam entering HP section 18. Steam is then channeled to IP steam inlet 38 and to IP section 20 at a reduced pressure than a pressure of the steam entering HP section 18. The steam impacts the rotor assembly 16 that is positioned within IP section 20 to induce rotation of rotor assembly 16.
In the exemplary embodiment, each rotor disk assembly 60 includes a plurality of turbine buckets 74 that are each coupled to a rotor disk 76. Rotor disk 76 includes a disk body 78 that extends between a radially inner portion 80 and a radially outer portion 82. Radially inner portion 80 defines a central bore 84 that extends generally axially through rotor disk 76. Disk body 78 extends radially outwardly from central bore 84, and extends generally axially between an upstream member 86 to an opposite downstream member 88. Rotor disk 76 is coupled to an adjacent rotor disk 76 such that upstream member 86 is coupled to an adjacent downstream member 88.
Each turbine bucket 74 is coupled to rotor disk outer portion 82 such that buckets are circumferentially-spaced about rotor disk 76. Each turbine bucket 74 extends radially outwardly from rotor disk 76 towards casing 58. Adjacent rotor disks 76 are coupled together such that a gap 90 is defined between each axially-adjacent row 91 of circumferentially-spaced turbine buckets 74. Nozzles 64 are spaced circumferentially about each rotor disk 76 between adjacent rows 91 of turbine buckets 74 to channel steam downstream towards turbine buckets 74. A steam flow path 92 is defined between turbine casing 58 and each rotor disk 76.
In the exemplary embodiment, each turbine bucket 74 is coupled to an outer portion 82 of a respective rotor disk 76 such that each turbine bucket 74 extends into steam flow path 92. More specifically, each turbine bucket 74 includes an airfoil 94 that extends radially outwardly from a dovetail 96. Each dovetail 96 is inserted into a dovetail groove 98 defined within an outer portion 82 of rotor disk 76 to enable turbine bucket 74 to be coupled to rotor disk 76.
In the exemplary embodiment, turbine engine 10 also includes a wear indication system 100 having a stationary component, such as but not limited to casing 58 and carrier 62. The stationary component is positioned proximate a rotating component, such as but not limited to turbine bucket 74, and more specifically, a tip cover (not shown in
In the exemplary embodiment, tip cover 126 includes a bottom surface 128, a top surface 130, and an exemplary wear indication feature 200. Feature 200 is used to quantitatively determining an amount of wear on tip cover 126 and an associated remaining service lifetime of tip cover 126 or bucket 74. In the exemplary embodiment, during certain operating modes of turbine engine 10 (shown in
As shown in
Alternatively, as shown in
In the exemplary embodiment, wear indication feature 200 is tapered inward as it extends into tip cover 126. More specifically, wear indication feature 200 includes a first dimension D1 at radially outer surface 130 and a second dimension D2 at endwall 204 that is smaller than first dimension D1. As described above, because wear indication feature 200 is frustoconical in shape, first and second dimensions D1 and D2 are diameters of associated circles at outer surface 130 and at endwall 204, respectively. In the embodiment shown in
In operation, wear indication feature 200 is formed in outer surface 130 of tip cover 126 and includes first dimension D1 at outer surface 130. When turbine 10 rotates, outer surface 130 of tip cover 126 contacts carrier 62 and thickness T of tip cover 126 decreases over time as radially outer surface 130 is worn away towards inner surface 128. After a predetermined period of operation, carrier 62 is removed to expose tip covers 126 for visual inspection. Without removing buckets 74 from turbine engine 10, a service operator is able to measure the diameter of wear indication feature 200 at a radially inward location of radially outer surface 130, for example, at location 132. The service operator then compares the measured second diameter D2 at radially inward location 132 to the initial first diameter D1 of wear indication feature 200 at radially outer surface 130 to determine a wear condition of the tip cover 126 such that the wear condition is based on the second diameter D2. Knowing the wear condition, the remaining service lifetime of tip cover 126 and/or bucket 74 is determined using a reference table or chart that associates the determined wear condition with corresponding remaining service lifetimes. As such, the remaining service lifetime of tip cover 126 and/or bucket 74 can be determined by simple visual inspection and a single measurement of wear indication feature 200 without requiring tip cover 126 and/or bucket 74 to be removed from turbine 10 and taken to a service center for analysis.
In this embodiment, wear indication feature 400 is tapered outward as it extends into tip cover 126. More specifically, wear indication feature 400 includes a third dimension D3 at radially outer surface 130 and a fourth dimension D4 at endwall 404 that is larger than third dimension D3. As described above, because wear indication feature 400 is frustoconical in shape, third and fourth dimensions D3 and D4 are diameters of associated circles at outer surface 130 and at endwall 204, respectively.
Although the wear indication system is shown and described herein as including a stationary component and a rotating component having a wear indication feature, other embodiments of the wear indication system are contemplated. For example, in one embodiment, the above-described wear indication feature is formed on a stationary component that contacts a rotating component. In another embodiment, the wear indication is formed on one or more stationary components that contact each other due to vibrations in the turbine engine. In yet another embodiment, the wear indication feature is formed on either a stationary or a rotating component that is subject to wear. For example, the wear indication feature is formed on the airfoil portion of a turbine blade, or any other component that does not contact another component in operation, and is subject to wear due to impingement from the flow of high speed, high temperature combustion gases flowing thereby.
The exemplary apparatus and methods described herein overcome at least some disadvantages of known systems and methods for use in determining an amount of wear of an internal component of a turbine. Moreover, the apparatus and methods described herein enable a reliable quantitative determination of the amount of wear of the internal component of the turbine to be determined. More specifically, the embodiments described herein each include at least one wear indication feature formed on a radially outer surface of an internal component of the turbine, such as a bucket tip cover. The wear indication feature includes a first dimension at the radially outer surface. When wear occurs, the radially outer surface is worn down such that the wear indication feature includes a second dimension radially inward of the initial radially outer surface. Without removing the buckets from the turbine engine, the second dimension can be measured and compared to the first dimension to determine the wear condition associated with the remaining service lifetime of the component. As such, the remaining service lifetime of tip cover and/or bucket can be determined by simple visual inspection and a single measurement of wear indication feature without requiring tip cover and/or bucket to be removed from turbine and taken to a service center for analysis.
Furthermore, the wear indication feature described herein includes any feature that is visibly distinct from the surrounding structure. For example, the wear indication feature includes a different color material that is exposed after a predetermined amount of wear. Moreover, the wear indication feature includes other surface characteristics such as texture and profile that are visibly distinct from the surrounding structure even after turbine engine system has been in operation, in order easily identify and measure the indicator.
The above-described wear inspection system and method of use provides a cost-effective and reliable method for inspecting internal components of a turbine for wear. In particular, the above-described wear inspection methods facilitate improving the quantitative assessment of determining the amount of wear of an internal component of the turbine, such as bucket tip covers. As such, the wear inspection methods permit an engineering evaluation that shortens the turbine outage time and further facilitates improving the efficiency of the turbine.
Exemplary embodiments of turbine buckets having wear indication features and methods of servicing the same are described above in detail. The methods and systems are not limited to the specific embodiments described herein, but rather, components of systems and/or steps of the method may be utilized independently and separately from other components and/or steps described herein. For example, the methods and systems may also be used in combination with other rotary engine systems and methods, and are not limited to practice with only the steam turbine engine as described herein. Rather, the exemplary embodiment can be implemented and utilized in connection with many other rotary system applications, for example gas turbine engines.
Although specific features of various embodiments of the disclosure may be shown in some drawings and not in others, this is for convenience only. Moreover, references to “one embodiment” in the above description are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. In accordance with the principles of the invention, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.
This written description uses examples for disclosure, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure 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.
