Patent Application
20160010496
1. Field of the Invention
The invention relates to turbine engine, such as industrial gas turbine engine or steam turbine engine blade deflection monitoring systems, utilizing an optical camera to capture time-based images of blade position, such as blade tip position. Changes in blade position over time are correlated to blade deflection, which in turn is used by the monitoring system to alarm or stop turbine engine operation if the correlated parameter is out of a permissible operating parameter range.
2. Description of the Prior Art
Industrial turbine engines, such as steam or combustion turbine engines, utilize shaft mounted rotating turbine blades to generate mechanical work, such as for driving an electric generator in a power generation plant and/or compressing air for combustion in a combustion turbine. The compressor or turbine section blades are susceptible to deflection during turbine engine operation, for example due to inlet compression or combustion gas transients or steam backpressure. Permissible blade deflection parameters are often established by turbine engine manufacturers and operators in order to reduce risk of engine damage. An engine blade deflection monitoring system is often employed during new or serviced engine validation to confirm that the engine is operating within permissible blade deflection parameters. In some engine installations a blade deflection monitoring system remains online during some or all engine operation.
Some known turbine engine blade deflection monitoring systems utilize vibration sensors coupled to the engine housing and/or turbine shaft structure to monitor frequency and/or amplitude, which is indirectly attributed to blade deflection. Other known turbine engine blade deflection monitoring systems directly monitor deflection amplitude of one or more individual blades. In some known systems individual blades incorporate strain gauges that measure blade deflection. Other known systems utilize proximity-type sensors that determine one or more blade positions relative to one or more of the proximity sensors. Changes in relative blade position over time are correlated to blade deflection amplitude. Proximity sensors incorporated in individual blade vibration and deflection monitoring systems have included ultrasonic, eddy current, laser and capacitive modality sensors. Individual blade monitoring proximity-type sensors are mounted within the turbine engine internal cavities, where they are exposed to hostile high pressure steamed or combustion gas environments. Exposure of internal sensors to the engine interior's hostile environment increases likelihood that the monitoring system may not remain operational during the entire operating cycle between scheduled maintenance cycles.
Exemplary embodiments of the invention are directed to an optical image based system and method for monitoring turbine engine (such as industrial combustion or steam turbine engine) blade deflection during engine operation. An optical camera is coupled the exterior of an engine inspection port, with its optical image gathering lens components oriented so that its field of view is oriented within the engine and captures images of a rotating turbine blade, such as the blade tip. The camera's image capture or sampling rate matches blade rotation speed, so that successive temporal images of one or more blades taken at the same rotational position within the engine are directed to a blade deflection monitoring system (BDMS) controller. The controller correlates changes in a blade's captured image position within the camera field of view between successive temporal images taken at the same blade rotational position with blade deflection. The BDMS controller alarms or trips engine operation if the monitored blade deflection falls outside permissible operation parameters. By mounting the camera outside the engine, fewer monitoring system components are exposed to the hostile operating environment within the engine, increasing likelihood that the system will remain operational until the next scheduled maintenance cycle.
Some exemplary embodiments of the invention feature a method for monitoring turbine blade deflection during turbine engine operation by establishing an optical camera field of view within an operating turbine engine that captures optical images of at least a portion of a turbine blade at a rotational position. A first image of the turbine blade portion in the field of view is captured at the rotational position. A second image of the turbine blade portion in the field of view is captured at the same rotational position at a later time. Change in relative position of the turbine blade portion within the field of view between the first and second images is determined. The determined change in the turbine blade portion relative position is correlated with the turbine blade deflection.
Other exemplary embodiments of the invention feature an operating turbine engine blade deflection monitoring system, including an optical camera having a field of view. The camera is adapted for coupling to an operating turbine engine, so that its field of view captures optical images of at least a portion of a turbine blade at a rotational position within the turbine engine. The camera is capable of capturing a first image of the turbine blade portion in the field of view at the rotational position and capturing a second image of the turbine blade portion in the field of view at the same rotational position at a later time. A blade deflection monitoring system controller is coupled to the camera, for receiving the first and second images and determining change in relative position of the turbine blade portion within the field of view between the first and second images. The controller correlates the determined change in the turbine blade portion relative position with the turbine blade deflection.
Additional exemplary embodiments of the invention feature a turbine engine, having a housing defining an inspection port; a rotating shaft in the housing, having an array of turbine blades; and a turbine engine blade deflection monitoring system. The blade deflection monitoring system includes an optical camera having a an optical tube, coupled to the inspection port, so that a field of view through the optical tube generates images of at least a portion of a turbine blade at a rotational position within the turbine engine housing, with image capture components of the camera remaining outside the engine. The camera is capable of capturing a first image of the turbine blade portion in the field of view at the rotational position and capturing a second image of the turbine blade portion in the field of view at the same rotational position at a later time. A blade deflection monitoring system controller is coupled to the camera, for receiving the first and second images and determining change in relative position of the turbine blade portion within the field of view between the first and second images. The controller correlates the determined change in the turbine blade portion relative position with the turbine blade deflection.
The respective features of the invention may be applied jointly or severally in any combination or sub-combination by those skilled in the art.
The teachings of the present invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which:
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures.
After considering the following description, those skilled in the art will realize that the teachings of the embodiments of the invention can be readily utilized in compressor or turbine blade deflection monitoring systems for steam or combustion industrial turbine engines. Image analysis of relative position of the blade within the monitoring system camera's field of view taken at one time at a blade rotation position is compared with one or more images taken at different times at the same blade rotation position during turbine engine operation. Changes of relative blade position within the same field of view orientation between successive temporal images (and/or optionally the rate of change of blade deflection between successive temporal images) are correlated with blade deflection by a blade deflection monitoring system (BDMS) controller. The controller alarms or trips the engine if monitored blade deflection falls outside permissible operation parameters.
In
The optical camera 34 captures optical, visible images in the infra-red and/or visible light spectra, and is preferably capable of capturing images at least at the blade rotational speed or multiples of the rotation speed. The camera 34 and optical tube 32 comprise parts of the blade deflection monitoring system (BDMS) 35 that also includes a BDMS controller 36 coupled to the camera, for storing captured camera images of blade tips 22 in the field of view (FOV) and for controlling the camera image capture sampling rate, so that the blade tip is at the same rotational position in each image. An exemplary BDMS controller 36 may comprise an industrial programmable logic controller (PLC), a processor based architecture personal computer or tablet computing device or a networked server that respectively execute program instruction sets for performing the BDMS 35 functions described herein. The camera 34 image capture sample rate and timing are designated by the BDMS controller 36 to generate a data set of temporal optical images captured at different sampling times for designated turbine blade tips 22 at the same rotational position. The camera 34 image capture sample rate can also be selected to generate respective data sets of temporal optical images captured at different sampling times for multiple respective designated turbine blade tips 22. Image data sets are generated and stored in the BDMS controller 36 and/or data storage device 38. An exemplary known human machine interface (HMI) 40, which may comprise a viewing monitor, keypad and/or mouse, allows operators to view one or more camera images, monitor the BDMS 35 operation, or reconfigure the BDMS. The BDMS controller 36 has a communications interface 42 for communicating with other known engine 10 and power plant monitoring and control systems.
The BDMS controller 36 controls the camera 34 image capture sample rate and timing with assistance of shaft position/speed sensor 46. The sensor 46 determines rotational position of one or more blades and/or shaft 14 rotational speed γ (such as in cooperation with a known shaft-mounted position encoder) and routes that sensor determined information directly or indirectly to the BDMS controller 36. The sensor 46 and/or the BDMS controller 36 are alternatively incorporated within the engine 10 general monitoring and control system (not shown) that is used to operate one or more engines in a power plant facility.
The Blade deflection monitoring system 35 advantageously determines engine blade 20 deflection during online operation of the turbine engine 10. Placing heat and pressure sensitive camera 34 and other electronic components of the BDMS 35 outside the engine interior, with only a heat resistant optical tube within the engine, increases likelihood that the BDMS can monitor blade deflection throughout all or most of an engine's power generation service cycle without system failure. The optical tube 32 is insertable into existing engine 10 service ports 28, 30 or any other port that allows establishment of the camera 34 field of view within a sweep path of one or more blade 20 rows of interest.
Although various embodiments that incorporate the teachings of the present invention have been shown and described in detail herein, those skilled in the art can readily devise many other varied embodiments that still incorporate these teachings. The invention is not limited in its application to the exemplary embodiment details of construction and the arrangement of components set forth in the description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.
