Patent Application
20110103930
The present invention relates to turbomachines, and more particularly to reducing a turbomachine's acoustic signature.
Turbomachines may produce noise from several fluid dynamic sources, including wake cutting, high velocity fluid dynamics, and turbulent flow fields. These noise sources may represent fluid energy that is not directed into the shaft of a turbomachine. The turbomachine's efficiency may be increased by transferring more fluid energy to the shaft. Valve sequencing is one method of transferring more fluid energy to the shaft.
Valve sequencing may also affect the acoustic signature of a turbomachine. In some instances, modifying valve sequencing for efficiency gains may increase the acoustic signature of a turbomachine. Thus, there is a need for a valve sequencing system for controlling a turbomachine's acoustic signature.
Embodiments of the present disclosure may provide a method of controlling a turbomachine having a plurality of valves, the method including selecting a desired operating load for the turbomachine, and identifying at least one arc of admission, wherein each of the plurality of valves is either completely closed or completely open when the arc of admission is achieved. Further, the method includes constructing a valve sequencing scheme configured to activate the identified arc of admission so as to minimize an acoustic signature of said plurality of valves during implementation of the desired operating load.
Embodiments of the present disclosure may further provide a turbomachine process control mechanism configured to implement a valve sequencing scheme to control a plurality of valves. The turbomachine process control mechanism includes a control system that is adapted to select a desired operating load for the turbomachine, and identify at least one arc of admission to achieve the desired operating load. In addition, the control system is further adapted to construct a valve sequencing scheme configured to activate the identified arc of admission so as to minimize an acoustic signature of said plurality of valves during implementation of the desired operating load.
Embodiments of the present disclosure may further provide a turbomachine, that includes a plurality of valves, and a turbomachine process control mechanism configured to implement a valve sequencing scheme to control the plurality of valves. The turbomachine process control mechanism includes a control system adapted to select a desired operating load for the turbomachine, and identify at least one arc of admission to achieve the desired operating load. The control system is further adapted to construct a valve sequencing scheme configured to activate the identified arc of admission so as to minimize an acoustic signature of said plurality of valves during implementation of the desired operating load.
The present disclosure is best understood from the following detailed description when read with the accompanying Figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.
a illustrates a graph of exemplary operating conditions of a turbomachine according to one or more aspects of the present disclosure.
b illustrates a graph of exemplary operating conditions of a turbomachine according to one or more aspects of the present disclosure.
It is to be understood that the following disclosure describes several exemplary embodiments for implementing different features, structures, or functions of the invention. Exemplary embodiments of components, arrangements, and configurations are described below to simplify the present disclosure, however, these exemplary embodiments are provided merely as examples and are not intended to limit the scope of the invention. Additionally, the present disclosure may repeat reference numerals and/or letters in the various exemplary embodiments and across the Figures provided herein. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various exemplary embodiments and/or configurations discussed in the various Figures. Moreover, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact. Finally, the exemplary embodiments presented below may be combined in any combination of ways, i.e., any element from an exemplary embodiment may be used in any other exemplary embodiment, without departing from the scope of the disclosure.
Additionally, certain terms are used throughout the following description and claims to refer to particular components. As one skilled in the art will appreciate, various entities may refer to the same component by different names, and as such, the naming convention for the elements described herein is not intended to limit the scope of the invention, unless otherwise specifically defined herein. Further, the naming convention used herein is not intended to distinguish between components that differ in name but not function. Further, in the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to.” All numerical values in this disclosure may be exact or approximate values unless otherwise specifically stated. Accordingly, various embodiments of the disclosure may deviate from the numbers, values, and ranges disclosed herein without departing from the intended scope.
The diaphragm 125 may include noise-reducing technology, which can include noise-reduction arrays. For example, the noise-reduction arrays may include resonator arrays. Additionally, or alternatively, noise-reduction arrays may be located proximal to the diaphragm 125. Exemplary embodiments of noise-reduction arrays include the technology described in U.S. Pat. Nos. 6,550,574; 6,601,672; 6,669,436; and 6,918,740.
The nozzle bowls 135a-e are configured to define one or more arcs of admission. An arc of admission describes those nozzle bowls 135 that receive process gas due to a configuration of one or more of the open valves 120. In other words, an arc or admission refers to a set of nozzles 140 receiving process gas. Because there are multiple sets of nozzles, there are multiple combinations of nozzles that could receive process gas at any one time. Each combination can be associated with a particular setting of valves 120. As such a particular arc of admission can be defined by a particular combination of open and closed valves 120. For example, a first arc of admission may include opening the valves 120a-c and closing the valves 120d-e, so that the nozzle bowls 135a, 135d, and 135e will receive the process gas, and nozzle bowls 135b and 135c will not receive the process gas. Partitions 130a-e prevent process gas from being transferred between the nozzle bowls 135a-e.
Each valve 120a-e is coupled to a lifting mechanism 150a-e, respectively. Each lifting mechanism 150 may include a cam coupled to a rod. In another exemplary embodiment, the lifting mechanism 150 may include an electromechanical actuator. In various other exemplary embodiments, the lifting mechanism 150 may be any type of linear actuator. Any combination of the foregoing may constitute a valve assembly. Other valve assemblies may include any device or mechanism configured to control the flow of a process gas to the nozzle bowls 135a-e.
In exemplary operation, the lifting mechanisms 150 lift the respective valves 120 to an open position. When any one of the valves 120 is open, it allows process gas to flow to the pipe 110a-e that is coupled to the respective valve 120. The process gas then flows to the respective nozzle bowls 135a-e that are fluidically coupled to the open valves 120, and across the nozzles 140 thereof.
Referring now to
According to an exemplary embodiment of the present disclosure, a valve sequencing scheme may be used to attenuate valve noise based on the timing of acoustic-sensitive events and/or transition events, as will be described in more detail below with respect to
As shown in
A valve 120 that is positioned at a completely open position (e.g., leaving the entrance to a pipe 110 substantially unobstructed) is said to be operating at a “valve point.” For example, in
When a valve 120 is neither completely closed nor completely open, it may be said to be operating at a “throttling position,” as illustrated in
Each valve produces an acoustic signature when gas flows therethrough. When a valve 120 is positioned at a throttling position, it generates a larger acoustic signature than when the valve 120 is operating at either a valve point or a closed position. The acoustic signature of the valves 120 operating in a throttling position is referred to as “valve screech” or “valve noise.” The acoustic signature of the valves 120 are a component of the acoustic signature of the turbomachine 100. To improve the performance of the turbomachine 100, and reduce valve noise, the operation sequence of the valves 120 may be configured to minimize the time that one or more of the valves 120 are operating at a throttling position. In addition to improving the efficiency of the turbomachine 100, minimizing the time that one or more of the valves 120 operates at a throttling position also has the added benefit of reducing valve noise during turbomachine 100 operation.
In an embodiment, two or more valves 120 may be moved simultaneously, rather than moving the valves 120 individually. For example, if the valves 120 are moved simultaneously from a completely closed position to a completely open position, or vice-versa, then the total amount of time that the valves spend at a throttling position is decreased as compared to consecutively moving each valve 120 one after the other. This also has the benefit of reducing the total amount of time that valve noise is produced.
Graphs 206a-e show a simplified relationship between entropy and enthalpy in the process gas flowing through each valve 120, and further illustrate the gains in efficiency achieved by minimizing throttling. The graphs 206a-c illustrate the entropy and enthalpy (i.e., energy) changes experienced in a process gas flow through the valves 120a-c, which are in the completely open position. As will be appreciated, the two lines in graphs 206a-c each indicate the inlet and exit pressure in the valve and nozzle bowl combination. Accordingly, as illustrated by the arrows, the process gas enters the valves 120a-c at a given, higher pressure. It then proceeds to the nozzle bowls 135a-e, where a portion of the potential energy stored in the flow as pressure is transferred into rotational mechanical energy, with a commensurate pressure drop experienced in the gas flow. In contrast, the valve 120d is only partially open. The graph 206d shows that the steam flow experiences two pressure drops: first, when flowing through the partially obstructed valve 120d, and second when transferring energy to the nozzles 140. This first pressure drop represents wasted potential energy that is dissipated in several forms, including valve noise. This increased valve noise represents loss of energy to the surroundings, and also an increase in a turbomachine's 100 acoustic signature.
Based on the foregoing, it can be seen that process gas passes through the valves 120a-c with minimal loss. In contrast, valve 120d experiences a comparatively greater throttling loss, will be noisier, and will require a higher process gas flow to achieve the same power output. The valve 120e is completely closed, so there is no flow and no loss.
If one or more of the valves 120 are only partly open, there is a larger pressure drop through the partly open valve(s) 120, and the steam exiting the partly open valves 120 has a lower pressure P01-Throt, which is lower than P01. This pressure drop is what restricts the flow through to the partly open valve(s) 120. When the steam from the partly open valve(s) 120 is expanded to the lower pressure through the respective set of nozzles 140, it reaches the P02 line at a different location. The smaller distance between the P01-Throt and the P02 line means there is less energy available to do work. The remaining energy has been dissipated in any of several forms, including noise.
Thus, one or more turbomachine 100 operating loads may be defined, and an operating load may be associated with an arc of admission. Valve sequencing may be used to control the activation of certain arcs of admission in accordance with associated operating loads. An arc of admission is “activated” by opening the valves 120 that are fluidically coupled to the nozzle bowls 135a-e that define the arc of admission, and closing the valves 120 and the nozzle bowls 135a-e that are fluidically coupled to the nozzle bowls 135a-e that are not part of the arc of admission. Further, valve sequencing may be used to attenuate valve noise in accordance with one or more of the turbomachine 100 operating loads. For example, in an exemplary embodiment, the valves 120 may be sequenced so that the turbomachine 100 is operating at an even valve point during one or more of the turbomachine 100 operating loads. In another exemplary embodiment, the valves 120 may be sequenced to minimize the time that valves 120 spend at a throttling position.
According to an exemplary embodiment, the method 500 begins at block 502, wherein one or more of the turbomachine operating loads are identified. One or more arcs of admission are defined at block 504, such that the arcs of admission minimize valve noise produced during the associated operating load. At block 506, an operating load is associated with the arc of admission. A valve sequencing scheme is defined at block 508. Optionally, the size of one or more of the valves 120 is defined at block 510 to minimize valve noise produced during the associated operating load.
Blocks 512 and 514 include operating the turbomachine 100 in accordance with the valve sequencing scheme. Block 512 includes activating the arc of admission, and block 514 may include initiating an operating load associated with the arc of admission.
According to an exemplary embodiment, an acoustic-sensitive event is an event that is scheduled to occur during operation of the turbomachine 100. For example, events such as start-up, reduced power, or maximum power, may be acoustic-sensitive events. Valve noise may be undesirable during such acoustic-sensitive events. Upon identifying one or more acoustic-sensitive events, a valve sequencing scheme may be implemented to attenuate the production of noise while the turbomachine is operating at an operating load associated with, or required by, the turbomachine during the acoustic-sensitive event.
In an exemplary embodiment, a valve sequencing scheme is implemented by defining the timing of valve 120 openings and closings so that an acoustic-sensitive event occurs before the next valve 120 in a sequence begins to open, and the valves 120 are configured to be at an even valve point during the acoustic-sensitive event. In some exemplary embodiments, a valve sequencing scheme designed to accommodate one or more acoustic-sensitive events may sacrifice turbine operation efficiency in order to obtain a desired acoustical target result.
An acoustic-sensitive event may include one or more transition events. A transition event includes an event where a first operating load transitions to a second operating load. During such transition events, valve noise may be undesirable. Upon identifying one or more transition events, a valve sequencing scheme is implemented to attenuate turbomachine 100 noise. In an exemplary embodiment, a valve sequencing system is configured to time the opening and closing of the valves 120 so that one or more transition events occur before the next valve 120 in a sequence begins to open. In some exemplary embodiments, a valve sequencing scheme designed to accommodate one or more transition events may sacrifice turbine operation efficiency in order to obtain a desired acoustical target result.
The foregoing has outlined features of several embodiments so that those skilled in the art may better understand the detailed description that follows. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the present disclosure.
