Patent Application
20080003095
Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
The invention is directed to systems and methods that utilize measured operation parameters to determine if a turbine is entering a region of undesired operation. If an undesired condition exists, the turbine control system initiates corrective action to avoid damage to parts. In an exemplary embodiment of the invention, steam pressure and bearing metal temperature sensors are used to monitor the operating conditions of a steam turbine through the use of a steam turbine control system programmed with steam turbine control system protection logic. Based on the information provided by the sensors, the steam turbine control system may initiate preemptive action to prevent excessive wear or damage to steam turbine components that typically occurs when a steam turbine component(s) has exceeded its threshold limit. More particularly, the steam turbine control system will detect when the steam turbine is entering an operational area of unacceptable risk (e.g., an undesirable flow unbalance mode of operation), which occurs before reaching a set limit associated with that particular steam turbine component. The control unit of the steam turbine control system will take the necessary measures to remove the steam turbine from this region of high risk operation before it exceeds the region of unacceptable risk and reaches a set limit threshold associated with that particular steam turbine component, thereby avoiding excessive wear to turbine components or turbine failure.
The present inventions now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the inventions are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.
The present invention is described below with reference to block diagrams of systems, methods, apparatuses and computer program products according to an embodiment of the invention. It will be understood that each block of the block diagrams, and combinations of blocks in the block diagrams, respectively, can be implemented by computer program instructions. These computer program instructions may be loaded onto a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions which execute on the computer or other programmable data processing apparatus create means for implementing the functionality of each block of the block diagrams, or combinations of blocks in the block diagrams discussed in detail in the descriptions below.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means that implement the function specified in the block or blocks. The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions that execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the block or blocks.
Accordingly, blocks of the block diagrams support combinations of means for performing the specified functions, combinations of steps for performing the specified functions and program instruction means for performing the specified functions. It will also be understood that each block of the block diagrams, and combinations of blocks in the block diagrams, can be implemented by special purpose hardware-based computer systems that perform the specified functions or steps, or combinations of special purpose hardware and computer instructions.
The inventions may be implemented through an application program running on an operating system of a computer. The inventions also may be practiced with other computer system configurations, including hand-held devices, multiprocessor systems, microprocessor based or programmable consumer electronics, mini-computers, mainframe computers, etc.
Application programs that are components of the invention may include routines, programs, components, data structures, etc. that implement certain abstract data types, perform certain tasks, actions, or tasks. In a distributed computing environment, the application program (in whole or in part) may be located in local memory, or in other storage. In addition, or in the alternative, the application program (in whole or in part) may be located in remote memory or in storage to allow for the practice of the inventions where tasks are performed by remote processing devices linked through a communications network. Exemplary embodiments of the present invention will hereinafter be described with reference to the figures, in which like numerals indicate like elements throughout the several drawings.
According to
Sensor devices may be used to monitor various parameters of the steam turbine components and its operation. The exemplary sensor devices shown in
A control unit 125 receives operating parameter data from the sensor devices (e.g., 130, 160 and 165) via monitor lines 135, 140 and/or 145 and may take corrective action if the operating parameter data detected indicates that the parameters are at undesirable operation values associated with unacceptable risk for a particular steam turbine component(s). Specifically, in the exemplary embodiment of
According to an exemplary embodiment of the invention, an undesirable condition that may be detected by the control unit 125 is an unbalanced thrust condition such as a thrust overload. A thrust overload may occur due to high flows in the high pressure steam turbine 105 and very low or no flow through the intermediate pressure turbine 110. For example, if the turbine system 100 is operating at full load (full flow) and the steam valve 150 closed and/or a intermediate pressure turbine bypass opens and flow is diverted around the intermediate pressure turbine 110, the intermediate pressure turbine bowl pressure will drop while the high pressure steam turbine bowl pressure stays at or near rated pressure. In the thrust overload condition, the thrust being generated by the high pressure steam turbine 105 is not being balanced by the intermediate pressure turbine 110, thereby overloading the thrust bearing 120.
The control unit 125 may detect such a thrust overload condition by use of sensor devices such as the steam pressure sensors 160 and 165 measuring the high pressure turbine bowl pressure and the intermediate pressure turbine bowl pressure, as well as the metal temperature sensor 130 measuring the overloading of the thrust bearing 120. The thrust bearing metal temperature monitored by the metal temperature sensor 130 is an added indication that there may be a problem with the thrust bearing 120 as a result of a thrust unbalanced state.
In an exemplary embodiment of the invention, the control unit 125 may detect thrust overload, as defined when the high pressure turbine bowl pressure is greater than a predetermined percentage of the rated pressure. For example, the predetermined percentage of the high pressure turbine bowl pressure may be 85% of its rated pressure and the intermediate pressure turbine bowl pressure may be less than 10% of its rated pressure. In alternative embodiments of the invention, various predetermined percentages of rated pressure may be used. In an exemplary embodiment of the invention, 10% is selected for the intermediate pressure turbine bowl pressure as an indicator that there is low flow (or no appreciable flow) passing through the intermediate turbine 110. In the exemplary embodiment of the invention, very low or no intermediate pressure turbine flow while the high pressure turbine bowl pressure is at 85% of its rated pressure or below is generally acceptable because below 85%, the high pressure turbine 105 does not generate enough thrust to overload the thrust bearing 120.
If a thrust overload condition is detected, the control unit 125 then takes the appropriate corrective measures to get out of a high thrust condition. In an exemplary embodiment of the invention, the control unit 125 adjusts the steam valves 150 and 155 to continuously runback the load reference until the high pressure turbine bowl pressure drops below 85% of rated pressure. In an exemplary embodiment of the invention the control unit 125 may continuously runback the load reference 20% per minute until such pressure drop is achieved. However, through use of the metal temperature sensor 130, while the control unit 125 continues to detect the high thrust condition, the control unit 125 monitors the thrust bearing metal temperature. In an exemplary embodiment of the invention, if the thrust bearing metal temperature rises to a temperature range associated with unacceptable risk to the thrust bearing or other components of the turbine system 100, then the turbine system 100 is tripped or shut down. Therefore, in such an exemplary embodiment, a system shutdown will occur if a thrust unbalanced condition and an unacceptable thrust bearing temperature thrust are detected.
Users communicate/control the control unit 125 via a user input device interface 240 in communication with user input device(s) 245 such as a keyboard, mouse, control panel, or any other devices capable of communicating digital data to the control unit 125 for configuration and/or control of the various components of the turbine system controlled by the control unit 125. The control unit 125 is in communication with the valves associated with the steam turbines, sensor devices (e.g., pressure or bearing temperature sensors) and, in some cases, external devices associated with the steam turbine system, via an I/O Interface 250. In an exemplary embodiment of the invention, the control unit 125 may be co-located or even integrated with a steam turbine system, though alternatively, it may be located remotely with respect to the steam turbine system. Further the control unit 125 and the programmed logic 215 implemented thereby may comprise software, hardware, firmware or any combination thereof.
At step 315, the control unit determines whether the operating parameters of the steam turbines have entered a range of unacceptable risk. If the steam turbines are operating within acceptable limits, then the control unit returns to its monitoring of operating parameters at step 310. If, however, the steam turbines are not operating within acceptable limits and have entered a range of operation that is associated with a particular risk level that is unacceptable, then the control unit will take corrective action, as indicated by step 320. According to an embodiment of the present invention, this corrective action in step 320 may be, for example, adjusting the steam valves associated with the inlet pipes. Control actions may include, but are not limited to setting off an alarm, transmitting an alarm signal, closing the steam valves, altering the temperature of the steam entering the steam turbines, altering the pressure of the steam entering the steam turbines, or shutting the system off altogether. Additionally, any triggered alarms or instances of a system operating outside of acceptable limits may be recorded in the memory of the control system. In other words, where at least one of the sensor devices detects one or more turbine components operating in a range of unacceptable risk such detected data may be recorded and stored in a database for future analysis.
In an exemplary embodiment of the invention, the control unit invokes step 405 to monitor the sensor devices such as the steam pressure sensors and measure the high pressure turbine bowl pressure and the intermediate pressure turbine bowl pressure, as well as the metal temperature sensor measuring the overloading of the thrust bearing. Next, the control unit invokes step 410 to determine if the high pressure turbine bowl pressure is greater than a predetermined percentage of the rated pressure. For instance, in the exemplary embodiment of
In an exemplary embodiment of the invention, 10% is selected for the intermediate pressure turbine bowl pressure as an indicator that there is low flow (or no appreciable flow) passing through the intermediate turbine. If intermediate pressure turbine bowl pressure is not less than 10% of its rated pressure, then the control unit continues to monitor the sensor devices at step 405. In the exemplary embodiment of the invention, very low or no intermediate pressure turbine flow while the high pressure turbine bowl pressure is at 85% of its rated pressure or below is acceptable because below 85% the high pressure turbine does not generate enough thrust to overload the thrust bearing. If the intermediate pressure turbine bowl pressure is less than 10% of its rated pressure then a thrust overload condition is detected and step 420 is invoked. In alternative embodiments of the invention, the percentages associated with the rated pressure values of the high pressure turbine bowl and the intermediate pressure turbine bowl may vary. Further, in other embodiments of the invention, the percentages associated with the rated pressure values of the high pressure turbine bowl and the intermediate pressure turbine bowl may be related (e.g., inversely proportional, etc.)
At step 420, the control unit begins to take the appropriate corrective measures to get out of a high trust condition. In an exemplary embodiment of the invention, the control unit adjusts the steam valves to continuously runback the load reference. In the exemplary embodiment of the invention, the control unit may runback the load reference at 20% per minute, though alternative runback rates may be implemented in other embodiments. Also at step 420, while the control unit continues to detect the high thrust condition, the control unit monitors the thrust bearing metal temperature through use of the metal temperature sensor as an added indicator that there is a problem with the thrust bearing as a result of a thrust unbalanced state.
Step 425 is then invoked to determine if the high pressure turbine bowl pressure drops below 85% of rated pressure. If the high pressure turbine bowl pressure drops below 85% of rated pressure, then the thrust overload condition has been alleviated and the control unit continues to monitor for the next undesirable condition at step 405. If the high pressure turbine bowl pressure does not drop below 85% of rated pressure, then the control unit continues to continuously runback the load reference (e.g., 20% per minute) until such pressure drop is achieved and invokes step 430 to determine if the thrust bearing metal temperature rises to a temperature range associated with unacceptable risk to the thrust bearing or other components of the turbine system. If such a temperature range has not been reached then the control unit continues to runback the load reference at step 420. If the thrust bearing metal temperature does rise to a temperature range associated with unacceptable risk then the turbine system is tripped or shut down at step 435. Therefore, in such an exemplary embodiment, a system shutdown will occur if a thrust unbalanced condition and an unacceptable thrust bearing temperature thrust are detected.
Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
