Patent Application
20170268962
Embodiments of the present invention relate generally to wear monitoring systems and more particularly to a system and method for monitoring fretting wear of a combustor.
A combustor of a gas turbine generates hot combustion gases which drives a turbine. The turbine, in turn, drives a compressor that provides compressed air for combustion in the combustor. In addition, the turbine produces usable output power. In one example, a combustor for a gas turbine may be configured as a circular array of cylindrical combustion chambers to receive compressed air from the compressor, mix the compressed air and fuel for generating a combustion reaction, and generate hot combustion gases.
A liner of the combustor operates in a high temperature environment. Liner stoppers and casing stoppers are provided to prevent tangential, radial, and translational motion of the liner due to combustion dynamics Heat and vibration from the combustion processes, as well as other mechanical loads and stresses from the gas turbine may shake, rattle and otherwise vibrate the liner. Specifically, liner stoppers and casing stoppers are mounted around the liner within a combustion flow sleeve.
During operation, various components of the combustor may rub against each other resulting in fretting wear. For example, the liner stopper may rub against the casing resulting in fretting wear followed by a crack in the liner stopper or the liner. Typically, defects in the combustor can be detected by disassembling the combustor which results in shutdown of the gas turbine.
Accordingly, there is a need for a method and system that predict and determine defects in a combustor without disassembling the combustor.
In accordance with one embodiment, a system is presented. The system includes a casing, a combustor disposed within the casing, and a sensing device located on the casing and configured to sense a plurality of acoustic emission waves and generate an electrical signal based on the sensed plurality of acoustic emission waves. The system further includes a processing subsystem operationally coupled to the sensing device and configured to determine one or more features based on the electrical signal, and determine a presence or an absence of fretting wear in the combustor based at least on the one or more features.
In accordance with another embodiment, a method for determining fretting wear in a combustor is presented. The method includes sensing a plurality of acoustic emission waves, generating an electrical signal based on the sensed plurality of acoustic emission waves, determining one or more features based on the electrical signal, and determining a presence or an absence of the fretting wear in the combustor based at least on the one or more features.
These and other features and aspects of embodiments 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:
Embodiments of the present system and method disclose monitoring the fretting wear of a combustor based on acoustic emission waves. For example, the embodiments of the present system and method disclose monitoring the fretting wear of a combustor based on acoustic emission waves transmitted through a casing of the combustor. Specifically, embodiments of the present system and method disclose determining whether fretting wear exists in the combustor by processing the acoustic emission waves.
The compressor 16 is configured to pressurize the atmospheric air 22 to provide pressurized air 26 to the combustor 12. The system 10 further includes a fuel source 28 that is configured to supply a fuel 30 to the combustor 12. The fuel 30 is mixed with the pressurized air 26 and combusted in the combustor 12 to generate combustion gases 32 carrying heat energy (not shown). The combustion gases 32 are directed from the combustor 12 to the turbine 18. The combustion gases 32 flow through between turbine blades (not shown) located in the turbine 18 resulting in expansion of the combustion gases 32. The turbine 18 drives the compressor 16 via the shaft(s) 20. Further, the turbine 18 drives a generator 24 to generate electric power.
In the illustrated embodiment, the combustor 12 is disposed within a casing 36. One or more sensing devices 38 are located on the casing 36. In one embodiment, the one or more sensing devices 38 may be located on an inner surface of the casing 36. In another embodiment, the one or more sensing devices 38 may be located on an outer surface of the casing 38. In yet another embodiment, the one or more sensing devices 38 may be located on one or more perforations in the casing 36. The one or more sensing devices 38, for example, may include an acoustic emission sensor, an accelerometer, a static pressure sensor, a dynamic pressure sensor or the like.
The one or more sensing devices 38 are configured to sense a plurality of acoustic emission waves 37 generated from the combustor 12, for example. The one or more sensing devices 38, for example, are configured to sense the acoustic emission waves 37 characterized by a frequency range of 100 kHz to 1.5 MHz. In one embodiment, the one or more sensing devices 38 are configured to sense the acoustic emission 37 waves transmitted through the casing 36 of the combustor 12. The one or more sensing devices 38 are further configured to generate an electrical signal 40 based on the sensed acoustic emission waves 37.
The system 10 further includes a processing subsystem 42 operationally coupled to the gas turbine engine 14 and the one or more sensing devices 38. In particular, the processing subsystem 42 is operationally coupled to the one or more sensing devices 38. The processing subsystem 42, for example may be a digital signal processor, a microprocessor, a microcomputer, a microcontroller, and/or any other suitable device. The processing subsystem 42 is configured to receive the electrical signal 40 from the gas turbine engine 14. Particularly, the processing subsystem 42 is configured to receive the electrical signal 40 from the one or more sensing devices 38.
In the illustrated embodiment, the processing subsystem 42 includes a filtering device 44, an amplifying device 46, and a sampler 48. The amplifying device 46 is operationally coupled to the one or more sensing devices 38 and is configured to receive the electrical signal 40 from the one or more sensing devices 38. The one or more sensing devices 38 may generate the electrical signal 40 characterized by high impedance that is unsuitable for transmission over cables. Hence, the amplifying device 46 transforms the electrical signal 40 characterized by high impedance to a low impedance electrical signal 50. Furthermore, in certain embodiments, the amplifying device 46 may amplify the electrical signal 40 characterized by high impedance to a voltage range that is suitable for the processing subsystem 42 and/or the filtering device 44. It should be noted herein that although the amplifying device 46 is shown as a part of the processing subsystem 42, the amplifying device 46 may be separate from the processing subsystem 42. The amplifying device 46, for example, may be electronic equipment, an electronic device, an electronic circuit or a module of the processing subsystem 42.
The processing subsystem 42 may further include the filtering device 44. The filtering device 44, for example, may be a module, a microprocessor, a microcomputer, a microcontroller, and/or any other suitable device, a module or a software code. In one embodiment, the filtering device 44 is operationally coupled to the amplifying device 46. The filtering device 44 is configured to filter the low impedance electrical signal 50 to generate a filtered electrical signal 52. In one embodiment, the filtering device 44, for example may include a band pass filter.
The sampler 48 is operationally coupled to the filtering device 44 and is configured to receive the filtered electrical signal 52. The sampler 48, for example, may be a module of the processing subsystem 42. The sampler 48 is configured to sample the filtered electrical signal 52 to generate a discrete electrical signal 54.
The processing subsystem 42 is configured to monitor the fretting wear of the combustor 12 based on the electrical signal 40. In one embodiment, the processing subsystem 42 is configured to monitor the fretting wear of the combustor 12 based on the discrete electrical signal 54. In one embodiment, the processing subsystem 42 is configured to determine one or more features based on the electrical signal 40 or the discrete electrical signal 54. The one or more features, for example, include a burst amplitude, a burst energy, a burst count, or the like. As used herein, the term “burst amplitude” refers to a maximum amplitude of an electrical signal generated for a determined time period. As used herein, the term “burst count” refers to a determined number of times, an electrical signal exceeds a predetermined voltage threshold. The burst energy, for example may be proportional to an area of the electrical signal 40 or the discrete electrical signal 54. The processing subsystem 42 is further configured to determine a presence or an absence of fretting wear in the combustor 12 based on the one or more features. In one embodiment, the processing subsystem 42 is further configured to determine the presence or the absence of the fretting wear in the combustor 12 based on a load of the gas-turbine engine 14 and the one or more features. The determination of fretting wear, for example, is explained in greater detail with reference to
The combustion liner 206 has an inlet end 216 aligned with a fuel injection nozzle 218 and an exhaust end 220 coupled to the combustion gas exhaust duct 207. A cylindrical wall 222 of the combustion liner 206 defines the combustion zone 208. The cylindrical wall 222 includes air apertures 224 to allow the compressed air 26 to flow into the combustion zone 208 for combustion and cooling. Fuel is fed to the fuel injection nozzle 218 through a fuel inlet port 226. Compressed air 26 flows from the compressor 16 (see
Acoustic emission waves, for example, are generated due to fretting wear between the combustion liner 206 and the liner stoppers 232, and/or fretting wear between the casing stoppers 236 and the casing 36 of the combustor 12. The acoustic emission waves, for example may also be generated due to fretting wear between the liner stoppers 232 and the flow sleeve 204, and/or the fretting wear between the casing stoppers 236 and the flow sleeve 204. For example, fretting wear may result in changes in the structure of the combustion liner 206, the liner stoppers 232 and the flow sleeve 204, resulting in generation of the acoustic emission waves.
Furthermore, at block 304, one or more features may be determined based on the electrical signal. The features, for example may include one or more of burst amplitude, burst energy, and burst count. An example of determination of features is shown with reference to
Furthermore, at block 306, a presence or an absence of the fretting wear may be determined based on one or more of the features. For example, one or more of the features may be correlated to a threshold value to determine the presence or the absence of the fretting wear in the combustor. For example, burst amplitude A may be compared to a respective threshold value T1. If the burst amplitude A exceeds the threshold value T1, it may be determined that fretting wear exists in the combustor. Similarly, burst count may be compared to a respective threshold value T2. If the burst count exceeds the threshold value T2, it may be determined that the fretting wear exists in the combustor. Similarly, when the burst energy exceeds a threshold value T3, it may be determined that the fretting wear exists in the combustor.
In certain embodiments, at block 308 wear volume in one or more components of the combustor may be determined. As used herein, the term “wear volume” refers to an amount of wear caused in one or more components of the combustor due to fretting wear. For example, the amount of wear-volume may be determined based on the features. Particularly, the amount of wear-volume may be determined based on an amount of deviation of the features from respective thresholds. Subsequently at step 310, when the fretting wear exists in the combustor, an operator or user may repair the combustor by replacing or repairing one or more components of the combustor.
Furthermore, at block 404 the electrical signal is amplified to generate a low impedance electrical signal. The amplification, for example, may be executed by an electronic equipment, an electronic device, an electronic circuit or a module of a processing subsystem. At block 406, the low impedance electrical signal is filtered to generate a filtered electrical signal. Subsequently, at block 408, the filtered electrical signal is sampled to generate a discrete electrical signal.
Additionally at block 410, one or more features are determined based on the discrete electrical signal. The features, for example, may include one or more of a burst amplitude, a burst energy, and burst count. Subsequently, at block 412, a presence or absence of the fretting wear may be determined based on one or more of the features. For example, one or more of the features is correlated to a threshold value to determine the presence or the absence of the fretting wear in the combustor. Subsequently at step 414, if the fretting wear exists in the combustor, an operator or user may repair the combustor by replacing or repairing one or more components of the combustor.
Embodiments of the present system and method disclose monitoring the fretting wear of a combustor without dismantling the gas turbine engine. Further, embodiments of the present system and method disclose an online estimate of wear in a combustor or one or more components of the combustor including liner stopper, casing, casing topper, or the like, thereby preventing early failures and unscheduled outages.
While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.
