Patent Application
20180231500
The field of this disclosure relates generally to inspection systems and, more particularly, to systems for use in inspecting cylindrical members, such as but not limited to shafts.
At least some cylindrical members, such as but not limited to rotor shafts, require inspections to identify incipient structural defects. For example, because of their exposure to high temperatures and/or pressures, inspection of turbine rotor components and shafts is necessary to ensure these components remain operational for the duration of their expected useful life. At least some inspections of components have been performed by coupling at least one inspection probe to an outer surface of the component, and then manually manipulating and positioning the at least one inspection probe to scan the component to identify structurally weakened areas. For example, a single inspection probe is used in a pulse-echo configuration, in which the inspection probe transmits a signal into the component and receives a reflected signal from a discontinuity or other structurally weakened area within the component. For another example, at least two inspection probes are used in a pitch-catch configuration, in which one probe transmits a signal into the component, and another probe is positioned to receive a reflected signal from a discontinuity or other structurally weakened area within the component.
Inspections using such systems may be time consuming and laborious. For example, manual manipulation and positioning of the probes may require a significant amount of time due to the small positional increments that are required to scan the component. Depending on the type of inspection and the inspection apparatus, the positional accuracy required between probes for the movement may be as small as thousandths of an inch. Although moving the system for such a short distance may not be difficult, accumulation of small positioning errors over each of a series of moves may create issues when moving the system by hand or when using a non-rigid inspection system.
In one aspect, an inspection system for a cylindrical member is provided. The inspection system includes at least one retention member positionable about at least a portion of a circumference of the cylindrical member. The inspection system also includes a positioning system and at least one housing. The at least one housing is coupleable to the at least one retention member at each of a series of circumferential inspection locations. The at least one housing includes at least one probe. The positioning system cooperates with the at least one retention member to position the at least one probe at each of the circumferential locations. The at least one probe is configured to send and receive a signal through an interior of the cylindrical member.
In another aspect, a method of inspecting a cylindrical member is provided. The method includes positioning at least one retention member about at least a portion of a circumference of the cylindrical member, and coupling at least one housing to the at least one retention member. The at least one housing includes at least one probe. The method also includes positioning the at least one housing at a series of circumferential inspection locations along the retention member, and activating the at least one probe at each of the circumferential inspection locations to send and receive a signal through an interior of the cylindrical member.
The following detailed description illustrates inspection systems and methods for cylindrical members by way of example and not by way of limitation. Exemplary inspection systems are described herein as being useful for inspecting turbine rotor shafts. However, it is contemplated that the shaft inspection systems and methods have general application to a broad range of inspection systems for cylindrical members used in a variety of fields other than only such turbines, such as but not limited to rolling members used in paper manufacturing or steel manufacturing.
During operation of power plant 100, steam 108 flowing through turbine 104 impinges rotor blades 114 or buckets and causes rotor 112 to rotate (i.e., causes rotor blades 114 and rotor shaft 116 to rotate). Rotation of rotor 112 causes generator drive shaft 122 to rotate, thus, enabling generator 106 to generate electricity. Rotor 112 generally is subjected to high levels of thermal and mechanical stresses during operation. As such, it is commonplace to periodically test the structural integrity of rotor 112 by inspecting the coupling of rotor blades 114 to rotor shaft 116, and/or by inspecting the structural continuity of an interior of rotor shaft 116 using, for example, at least one probe (not shown) coupled to rotor shaft 116 on shaft outer surface 128. However, shaft outer surface 128 may include steps or other contours, and/or rotor 112 may have other design features along shaft 116, such as rotor wheels and/or seals, that make it difficult to position such probes in a location that provides a clear internal signal path to each region of interest within rotor shaft 116. As such, the inspection system disclosed herein is configured to securely, accurately, and relatively quickly position such probes relative to shaft outer surface 128 at a plurality of circumferential positions at each accessible axial station of rotor shaft 116.
In the exemplary embodiment, inspection system 400 includes at least one housing 402. Each housing 402 includes at least one probe 406 operable to inspect shaft 116. More specifically, probe 406 is positioned adjacent a surface 404 of housing 402 adjacent shaft 116, such that probe 406 is positionable against shaft 116. In the exemplary embodiment, each probe 406 includes an ultrasonic transducer (UT). For example, each probe 406 includes a suitable phased array UT transducer having a plurality of separately controllable elements. For another example, each probe 406 includes a single UT element. In alternative embodiments, each probe 406 is any suitable probe that enables system 400 to function as described herein.
In the exemplary embodiment, system 400 includes a pair of housings 402 configured to selectively operate probes 406 in a pitch-catch configuration, in which probe 406 of one housing 402 transmits a signal into shaft 116, and probe 406 of the other housing 402 receives a reflection of the signal from a discontinuity or other structurally weakened area within an interior of shaft 116. Suitable processing of the signals to precisely locate flaws within shaft 116 requires probes 406, and thus housings 402, to be precisely positioned relative to shaft 116, for example within a first tolerance. Moreover, suitable processing of the signals to precisely locate flaws within shaft 116 requires probes 406, and thus housings 402, to maintain precise positioning with respect to each other, for example within a second tolerance, while probes 406 are active. In addition, in the exemplary embodiment, system 400 is configured to selectively operate probe 406 of at least one housing 402 independently in pulse-echo configuration, in which the single probe 406 transmits a signal into shaft 116 and receives a reflection of the signal from a discontinuity or other structurally weakened area within the interior of shaft 116. For example, at some axial stations of shaft 116, pitch-catch signal transmission may be blocked by structural features defined in shaft 116 and/or additional features of rotor 112, necessitating a use of pulse-echo instead. Suitable processing of the pulse-echo signals to precisely locate flaws within shaft 116 again requires the single probe 406, and thus the corresponding housing 402, to be precisely positioned relative to shaft 116, for example within a first tolerance. In some embodiments, the first tolerance for operation in pulse-echo configuration differs from the first tolerance in pitch-catch configuration.
Inspection system 400 also includes at least one retention member 408 positionable about at least a portion of a circumference of shaft 116. Each housing 402 is coupled to, and traversable along, at least one retention member 408 at an axial station of shaft 116. More specifically, each housing 402 includes a positioning system 420 that cooperates with at least one retention member 408 to position respective probe 406 circumferentially at each of a series of indexed, discrete locations with respect to shaft outer surface 128. System 400 is configured to activate probe 406 to scan the corresponding interior region of shaft 116 while housing 402 is stopped at each indexed circumferential location. System 400 facilitates maintaining a position of each probe 406 to within the required tolerance at each indexed circumferential location, and thus facilitates accurate identification of a location of structural weaknesses within shaft 116, without any need for continuous scanning and/or rotation of shaft 116 during inspection.
Each retention member 408 is positioned circumferentially around shaft outer surface 128 at a respective axial station of shaft 116 selected to facilitate inspection of a corresponding interior region of shaft 116. For example, in the embodiment illustrated in
In first embodiment 200 of inspection system 400, the at least one retention member 408 is at least one belt loop 208, and positioning system 420 is embodied as a respective wheel system 220 coupled to each housing 402. Each wheel system 220 cooperates with a respective belt loop 208. In
In the exemplary embodiment, each belt loop 208 is formed from a belt strip adjustably coupled to itself and tightened to form a loop corresponding approximately to the circumference of shaft outer surface 128. Thus, belt loops 208 are adjustable to couple to shafts 116 having a range of diameters. In certain embodiments, remaining slack in each belt loop 208 is taken up by wheel system 220, as will be described herein.
Wheel system 220 is operable to automatically traverse each housing 402, including respective probe 406, along the corresponding belt loop 208. For example, in the exemplary embodiment, each wheel system 220 includes a plurality of wheels 210 that engage the corresponding belt loop 208. At least one wheel 210, designated as driving wheel 212, drivingly engages with belt loop 208, such that a preselected amount of rotation of the at least one driving wheel 212 traverses housing 402 a corresponding preselected distance along belt loop 208 and, thus, a preselected distance along the circumference of shaft outer surface 128. In alternative embodiments, wheel system 220 is operable to automatically traverse each housing 402 along the corresponding belt loop 208 in any suitable fashion that enables system 400 to function as described herein.
Moreover, in the exemplary embodiment, the at least one driving wheel 212 is operably coupled to a suitable controller 202, located for example within housing 402. Controller 202 is configured to command rotation of the at least one driving wheel 212, and to receive feedback from the at least one driving wheel 212 regarding an amount of rotation of, and thus a distance traveled by, the at least one driving wheel 212. More specifically, controller 202 is configured to automatically traverse housing 402 along belt loop 208 to the series of indexed circumferential inspection locations along shaft outer surface 128 to within the first tolerance. In some embodiments, controller 202 is further configured to receive commands from, and/or provide data to, an operator interface (not shown), such as, but not limited to, in real time.
In the exemplary embodiment, controller 202 also is operably coupled to probe 406, such that controller 202 is operable to automatically activate and deactivate probe 406 at each circumferential inspection location. In alternative embodiments, controller 202 is configured to activate probe 406 in response to a user command.
In some embodiments, wheel system 220 facilitates movement of housing 402 along belt loop 208 without slippage of the at least one driving wheel 212 with respect to belt loop 208, and without slippage of belt loop 208 with respect to shaft outer surface 128. For example, a pair of wheels 210, designated tensioning wheels 214, are configured to engage belt loop 208 and drivingly rotate oppositely to each other, such that slack in belt loop 208 around outer surface 128 is taken up by tensioning wheels 214. More specifically, slack is taken up until resistance from belt loop 208 indicates a preselected tension is being maintained in belt loop 208. The preselected tension is sufficient to inhibit slippage of the at least one driving wheel 212 with respect to belt loop 208, and to inhibit slippage of belt loop 208 with respect to shaft outer surface 128.
In certain embodiments, controller 202 is operably coupled to tensioning wheels 214, such that controller 202 is operable to drive tensioning wheels 214 to automatically maintain the preselected tension in belt loop 208. Additionally, or alternatively, at least one wheel 210 is biased against belt loop 208, such by a mechanical spring coupled between the at least one wheel 210 and housing 402, to facilitate maintaining the preselected tension in belt loop 208. In alternative embodiments, wheel system 220 inhibits slippage of the at least one driving wheel 212 with respect to belt loop 208, and/or slippage of belt loop 208 with respect to shaft outer surface 128, in any suitable fashion that enables system 400 to function as described herein.
In certain embodiments, additional wheels 209 that do not engage belt loop 208 are coupled to housing bottom surface 404 to facilitate travel of housing 402 along shaft outer surface 128.
In some embodiments, an accuracy of inspection by probes 406 further depends upon a preselected pressure of probes 406 against shaft outer surface 128 being maintained while probes 406 are active. For example, each probe 406 must be positioned against shaft outer surface 128 at the preselected pressure to facilitate acoustic coupling between probes 406 and shaft 116 during inspection. In certain embodiments, wheel system 220 facilitates maintaining probe 406 in contact with shaft outer surface 128 at the preselected pressure during an inspection, by maintaining the preselected tension in belt loop 208 such that housing 402, and thus probe 406 adjacent bottom surface 404 of housing 402, is urged towards shaft outer surface 128. Additionally, or alternatively, the preselected pressure of probe 406 against shaft outer surface 128 is maintained by a mechanical spring coupled between probe 406 and housing 402, or in any other suitable fashion that enables inspection system 400 to function as described herein.
In some embodiments, first embodiment 200 of system 400 further includes a housing link 418 coupled between housings 402. Housing link 418 facilitates maintaining a relative position between probes 406 to within the second tolerance while probes 406 are active. For example, housing link 418 is a rigid mechanical member that couples pair of housings 402 together at a fixed spacing. In some embodiments, housing link 418 also may be used as a handle to carry housings 402 and/or position housings 402 with respect to shaft 116 during set-up of system 400. Additionally, or alternatively, positioning system 420 facilitates maintaining probes 406 in position relative to each other to within the second tolerance, simultaneously with positioning each probe 406 with respect to shaft outer surface 128 to within the first tolerance, as described above. Additionally, or alternatively, a circumferential position of each probe 406 relative to shaft 116, and/or a relative position of probes 406, is determined and/or maintained by controller 202 at least partially using feedback from additional sensors, such as from respective inclinometers (not shown) coupled to each housing 402.
In the exemplary embodiment, inspection system 400 also includes at least one axially extending spacer arm 419 coupled to at least one housing 402. Spacer arm 419 is configured to bear against a portion of rotor 112, such as but not limited to packing teeth or a rotor wheel face (not shown), that is axially adjacent to the axial station of shaft 116 being inspected, to further facilitate maintaining housings 402 at the axial station during movement along belt loop 208 between circumferential inspection locations. Alternatively, spacer arm 419 is configured to bear against an inspection guide surface (not shown) coupled to shaft 116 axially adjacent to the axial station of shaft 116 being inspected. In alternative embodiments, inspection system 400 does not include spacer arm 419.
First embodiment 200 of inspection system 400 is portable, light weight, and relatively easy to set-up such that the inspection of rotor shaft 116, for example, can be performed by only one operator, and with no need to rotate shaft 116. Additionally, inspection system 400 need only be configured once initially at each axial station to perform an automatic inspection of the regions of shaft 116 corresponding to the entire axial station. As such, the operator is not required to continuously interact with and/or monitor inspection system 400 during inspection of each axial station, thus increasing a speed of the inspection process. Inspection system 400 also facilitates reduction or elimination of errors which may occur as the result of repeated manual positioning at each station during an inspection. Furthermore, wheel system 220 in cooperation with belt loop 208 accommodates a range of diameters of shaft 116, without any need to measure or otherwise predetermine the diameter. Moreover, belt loop 208 can be easily manipulated, lifted, and flexed over rotor shaft 116 by a single operator, even at, for example, elevated working heights.
Each strong-back 308 is a rigid structure that extends circumferentially around at least a portion of shaft outer surface 128 at a selected axial station of shaft 116 selected to facilitate inspection of a corresponding interior region of shaft 116. In the exemplary embodiment, each strong-back 308 includes two semicircular portions coupled together to facilitate coupling strong-back 308 around shaft 116. In alternative embodiments, strong-back 308 is formed in any suitable fashion that enables second embodiment 300 of system 400 to function as described herein. At least one housing 402 is coupled to each strong-back 308 and is circumferentially traversable along strong-back 308. More specifically, indexing system 320 is configured to retain housing 402 at each of a series of indexed circumferential inspection locations along strong-back 308, and thus along the circumference of shaft outer surface 128, to within the first tolerance.
For example, in the embodiment illustrated in
In certain embodiments, indexing system 320 is actuatable to releasably retain the respective housing 402 at each circumferential inspection location. In the exemplary embodiment, indexing system 320 cooperates with a plurality of notches 310 defined on strong-back 308. More specifically, notches 310 are spaced circumferentially around strong-back 308, and each notch 310 corresponds to a preselected circumferential inspection location around shaft 116. Indexing system 320 includes an actuatable projection 312 configured to be received by each of notches 310 to lock each housing 402, and thus each probe 406, at the corresponding circumferential location to within the first tolerance. Moreover, projection 312 is retractable, such as by manual operation of a suitable trigger mechanism (not shown) on housing 402 or housing link 418, to disengage from notch 310 after completion of probe activation, such that housings 402 may be advanced to the next notch location.
In some embodiments, plurality of notches 310 includes pairs of notches 310 circumferentially spaced around strong-back 308 on opposing surfaces 309 and 311 of strong-back 308, and indexing system 320 of each housing 402 includes a respective actuatable projection 312 configured to be received by one of each pair of notches 310. Thus, each housing 402 locks separately to, and is separately releasable from, strong-back 308. In other embodiments, plurality of notches 310 includes notches 310 circumferentially spaced around a radially outer surface 313 of strong-back 308, and indexing system 320 is a single actuatable projection 312 coupled to housing link 418. Thus, housings 402 lock, and are releasable from, strong-back 308 together as a pair. Although notches 310 and indexing system 320 are shown in both locations in
In certain embodiments, strong-back 308 does not include notches 310, and indexing system 320 is configured to couple housings 402 directly to at least one of surfaces 309, 311, and 313 of strong-back 308. For example, indexing system 320 is actuatable to reduce an axial spacing 315 between pair of housings 402 coupled to a single strong-back 308, such that housings 402 securely couple against opposing surfaces 309 and 311 in a friction fit when indexing system 320 is actuated. For another example, indexing system 320 securely couples to at least one of surfaces 309, 311, and 313 using magnetism. For another example, indexing system 320 securely couples to at least one of surfaces 309, 311, and 313 using vacuum suction.
In some embodiments, indexing system 320 includes an encoder (not shown), such as on bottom surface 404 of housing 402, such that a circumferential location of housings 402 along shaft 116 is trackable by indexing system 320 as housings 402 are moved along strong-back 308. Additionally, or alternatively, at least one of surfaces 309, 311, and 313 includes precisely located tracking features, such as inscribed lines (not shown), and each housing 402 includes a sensor (not shown) to detect movement past the tracking features, such that a circumferential location of housings 402 along shaft 116 is trackable by indexing system 320 as housings 402 are moved along strong-back 308.
In the exemplary embodiment, housing link 418 again facilitates maintaining a relative circumferential position between probes 406 to within the second tolerance while probes 406 are active, as described above. Additionally, or alternatively, a relative position of probes 406 is again determined at least partially using feedback from additional sensors, such as inclinometers (not shown) coupled to each housing 402.
In alternative embodiments, indexing system 320 includes any suitable structure that enables second embodiment 300 of system 400 to function as described herein.
In the exemplary embodiment, each strong-back 308 is positioned with respect to a datum (not shown) on rotor 112 that defines a coordinate system of rotor 112. Thus, a position of housings 402, and therefore probes 406, at each location on each strong-back 308 is translatable to a position with respect to the rotor coordinate system. In alternative embodiments, a position of probes 406 at each location may be translated to the rotor coordinate system in any suitable fashion.
In the exemplary embodiment, housings 402, strong-backs 308, and indexing system 320 are sized and configured such that the preselected pressure of probe 406 against shaft outer surface 128 is maintained when housings 402 are locked at each circumferential inspection location. Moreover, in certain embodiments, a radial position of each housing 402 with respect to strong-back 308 is adjustable, such that housings 402 in cooperation with strong-back 308 accommodate a range of diameters of shaft 116, without any need to measure or otherwise predetermine the diameter. Additionally, or alternatively, the preselected pressure of probe 406 against shaft outer surface 128 is maintained by a mechanical spring coupled between probe 406 and housing 402, or in any other suitable fashion that enables inspection system 400 to function as described herein.
In some embodiments, each housing 402 is configured to be retained by strong-back 308 during circumferential traversal along strong-back 308 between each circumferential inspection location. For example, strong-back 308 includes circumferentially extending grooves (not shown) defined in surfaces 309 and/or 311, and each housing 402 includes a tongue (not shown) configured for retention in the groove. For another example, strong-back 308 includes a circumferentially extending groove (not shown) defined in radially outer surface 313, and housing link 418 includes a tongue (not shown) configured for retention in the groove. For another example, each housing 402 includes a magnetic portion that facilitates retaining housings 402 on strong-back 308. In other embodiments, pair of housings 402 is not configured to be retained by strong-back 308 during traversal between circumferential inspection locations. For example, housings 402 are solely manually supported during traversal between the circumferential inspection locations.
Second embodiment 300 of inspection system 400 is portable, light weight, and relatively easy to set-up, and the inspection of rotor shaft 116, for example, can be performed by only one operator, with no need to rotate shaft 116. Additionally, inspection system 400 need only be configured once initially at each axial station to perform an inspection of the regions of shaft 116 corresponding to the entire axial station. As such, the operator is not required to continuously interact with and/or monitor inspection system 400 during inspection, thus increasing a speed of the inspection process. Inspection system 400 also facilitates reduction or elimination of errors which may occur as the result of repeated manual positioning at each station during an inspection. Moreover, in certain embodiments, housings 402 in cooperation with strong-back 308 accommodate a range of diameters of shaft 116, without any need to measure or otherwise predetermine the diameter. Furthermore, second embodiment 300 requires fewer motorized components and less complex control features than first embodiment 200 of inspection system 400.
Some embodiments involve the use of one or more electronic or computing devices, such as controller 202. Such devices typically include a processing device such as a general purpose central processing unit (CPU), a graphics processing unit (GPU), a microcontroller, a reduced instruction set computer (RISC) processor, an application specific integrated circuit (ASIC), a programmable logic circuit (PLC), a field programmable gate array (FPGA), a digital signal processing (DSP) device, and/or any other circuit or processing device capable of executing the functions described herein. The methods described herein may be encoded as executable instructions embodied in a computer readable medium, including, without limitation, a storage device and/or a memory device. Such instructions, when executed by the controller or processing device, cause the controller or processing device to perform at least some of the method steps described herein. The above examples are exemplary only, and thus are not intended to limit in any way the definition and/or meaning of the terms controller and processing device.
Embodiments of the systems and methods described herein for inspecting a cylindrical member, such as, for example, a turbine rotor shaft, provide advantages over at least some known systems and methods for inspecting cylindrical members. For example, the embodiments described herein facilitate non-invasive inspection of a cylindrical member from around the outer circumference of the cylindrical member, without any need to rotate the cylindrical member. Specifically, the embodiments described herein facilitate positioning of at least one inspection probe at a series of indexed circumferential inspection locations around the cylindrical member, thereby reducing a need for manual positioning of the probe at each circumferential location, which reduces a time required for, and a potential for errors in, probe positioning. Also, specifically, the embodiments described herein facilitate an ease of transportation and initial set-up of the inspection system. Thus, the embodiments described herein facilitate reducing the number for people required to set up the system and perform the inspection. For example, in some embodiments, only one operator is required. Further, in some embodiments, the probe is automatically traversed around the cylindrical member without manual intervention after the initial set-up. The embodiments thus facilitate reducing an amount of time associated with an inspection, which for example reduces a cost associated with inspecting a rotor of a turbine. In some cases, the embodiments described herein reduce an amount of revenue lost by a power plant because of a turbine rotor inspection process.
Exemplary embodiments of cylindrical member inspection systems and methods are described above in detail. The systems and methods described herein are not limited to the specific embodiments described herein, but rather, components of the systems and methods may be utilized independently and separately from other components described herein. For example, the systems and methods described herein may have other applications not limited to practice with turbines, as described herein. Rather, the systems and methods described herein can be implemented and utilized in connection with various other industries.
While the disclosure has been described in terms of various specific embodiments, those skilled in the art will recognize that the disclosure can be practiced with modification within the spirit and scope of the claims.
