Patent Application
20140060003
The subject matter disclosed herein relates to the art of turbomachines and, more particularly, to a turbomachine having a flow monitoring system.
Many turbomachines include a compressor portion linked to a turbine portion through a common compressor/turbine shaft or rotor and a combustor assembly. The compressor portion guides compressed air flow through a number of sequential stages toward the combustor assembly. In the combustor assembly, the compressed air flow mixes with a fuel to form a combustible mixture. The combustible mixture is combusted in the combustor assembly to form hot gases. The hot gases are guided to the turbine portion through a transition piece. The hot gases expand through the turbine portion rotating turbine blades to create work that is output, for example, to power a generator, a pump, or to provide power to a vehicle. In addition to providing compressed air for combustion, a portion of the compressed airflow is passed through the turbine portion for cooling purposes.
According to one aspect of an exemplary embodiment, a turbomachine includes a turbine portion having a housing enclosing one or more turbine stages. Each of the one or more turbine stages includes a plurality of turbine buckets. The plurality of turbine buckets include an upstream portion and a downstream portion. A first sensor is mounted in the turbine portion at the upstream portion of plurality of turbine buckets and a second sensor is mounted in the turbine portion at the downstream portion of the plurality of turbine buckets. A controller is operatively coupled to the first and second sensors. The controller is configured and disposed to detect a change in flow between the upstream portion and the downstream portion and signal an alarm if the change in flow falls below a predetermined threshold value.
According to another aspect of an exemplary embodiment, a combined cycle power plant includes a gas turbomachine including a compressor portion, a turbine portion, and a combustor assembly fluidically connected to the compressor portion and the turbine portion. A heat recovery steam generator is fluidically connected to the turbine portion. A steam turbine is fluidically connected to the heat recovery steam generator. The steam turbine includes a housing enclosing one or more turbine stages. Each of the one or more turbine stages includes a plurality of turbine buckets. The plurality of turbine buckets includes an upstream portion and a downstream portion. A first sensor is mounted in the turbine portion at the upstream portion of plurality of turbine buckets. A second sensor is mounted in the turbine portion at the downstream portion of the plurality of turbine buckets. A controller is operatively coupled to the first and second sensors. The controller is configured and disposed to detect a change in flow between the upstream portion and the downstream portion and signal an alarm if the change in flow falls below a predetermined threshold value.
According to yet another aspect of an exemplary embodiment, a method of operating a turbomachine includes, sensing a first flow parameter upstream of a turbine bucket, sensing a second flow parameter downstream of the turbine bucket, calculating a difference between the first flow parameter and the second flow parameter, and initiating an alarm if the difference between the first flow parameter and the second flow parameter exceeds a predetermined threshold value.
These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.
The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.
With reference to
Steam turbine portion 20 includes a housing 22 that encloses a plurality of turbine stages 25. Turbine stages 25 include a first turbine stage 26, a second turbine stage 27, a third turbine stage 28, and a fourth turbine stage 29. First turbine stage 26 includes a first plurality of vanes or nozzles 33 and a first plurality of rotating components in the form of blades or buckets 34. Buckets 34 are mounted to a first rotor member (not shown) that is coupled to shaft 12. Second turbine stage 27 includes a second plurality of vanes or nozzles 37 and a second plurality of blades or buckets 38. Buckets 38 are coupled to a second rotor member (also not shown). Third turbine stage 28 includes a third plurality of vanes or nozzles 41 and a third plurality of blades or buckets 42 that are coupled to a third rotor member (also not shown). Fourth turbine stage 29 includes a fourth plurality of vanes or nozzles 45 and a fourth plurality of blades or buckets 46 that are coupled to a fourth rotor member (not shown). Buckets 46 represent last stage or aft-most buckets in steam turbine 20. Of course it should be understood that the number of turbine stages may vary. Steam turbine 20 is also shown to include a plurality of stationary turbine shrouds 86-89 supported to housing 22. Turbine shrouds 86-89 provide a desired clearance between an inner surface (not separately labeled) of housing 22 and tip portions (not separately labeled) of corresponding ones of buckets 34, 38, 42, and 46. Turbine shrouds 86-89 are arranged in a ring circumscribing corresponding ones of turbine stages 25-29.
In accordance with an exemplary embodiment, steam turbine 20 includes a first sensor 100 arranged upstream of buckets 46 and a second sensor 104 arranged downstream of buckets 46. Sensors 100 and 104 provide signals to a controller 110 that is programmed to determine flow across buckets 46. More specifically, controller 110 is programmed to calculate a pressure difference (ΔP) across tip portions 114 of buckets 46. Sensor 100 provides a signal representative of P1 and sensor 104 provides a signal representative of P2. Controller 110 is shown to include a central processor unit (CPU) 124 and a memory 125. Memory 125 may be configured to store pressure values obtained from sensors 100 and 104 over a period of time. As will become more fully evident below, controller 110 provides an output to an alarm 130 if ΔP falls below a predetermined threshold value. In accordance with an aspect of the exemplary embodiment, during normal operation of steam turbine portion 20, ΔP=P1−P2 should be a positive value. A positive value represents operation in a turbine mode, or a mode in which pressure decreases in a direction of flow of gases through steam turbine portion 20. If, however, ΔP falls below a predetermined value or trends toward a negative value, alarm 130 is activated to signal the presence of a condition of interest in steam turbine 20. The condition of interest represents operation in a compressor mode or a mode in which pressure increases in the direction of flow over tip portions 114. The condition of interest may result in blade flutter, vibrations due to flow instability, or the like.
Reference will now be made to
At this point it should be understood that the exemplary embodiments provide a system for monitoring flow characteristics through a turbomachine. Flow parameters monitored in accordance with the example embodiments have been found to be early indicators or warnings of potential vibrations or flutter in the turbine. Early warnings provided by the monitoring system of the exemplary embodiment allow operators to take corrective measures before vibrations/flutters reach undesirable levels. At this point it should be understood that while shown and described as monitoring pressures at the aft-most, or last stage turbine buckets, the exemplary embodiments may be positioned in other locations in the turbine. Further, while shown and described as being employed in connection with a steam turbine, the exemplary embodiments may be incorporated into a gas turbine and/or a compressor.
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
