燃气涡轮工程手册 Gas Turbine Engineering Handbook 3(41)

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Implementation of advanced performance degradation models， necessit-ate the inclusion of advanced instrumentation and sensors such as pyrom-eters for monitoring hot section components， dynamic pressure transducers for detection of surge and other flow instabilities such as combustion espe-cially in the new dry low ..x combustors. To fully round out a condition monitoring system the use of expert systems in determining fault and life cycle of various components is a necessity.
The benefits of total performance based planned maintenance not only ensure the best and lowest cost maintenance program but also that the plant is operated at its most efficient point. An important supplementary effect is that the plant will be operating consistently within its environmental con-straints.
The new purchasing mantra for the new utility plants is ..life cycle cost.. and to properly ensure that this is achieved a ..total performance condition monitoring.. strategy is unsurpassed.
To avoid excessive downtime and maintain availability， a turbine should be closely monitored and all data analyzed for major problem areas.
To achieve effective monitoring and diagnostics of turbomachinery， it is necessary to gather and analyze both the mechanical and aerothermal oper-ating data from the machines. The instrumentation and diagnostics mustalso be custom tailored to suit the individual machines in the system， and also to meet the requirements of the end users. The reasons for this are that there can be significant differences in machines of the same type or manu-facturer because of differences in installation and operation.
.e.uirements for an Effective .iagnosti. System
1.  The system must produce diagnostic and failure prediction informa-tion in a timely manner before serious problems occur on the machines monitored.

2. When
equipment shutdown becomes necessary， diagnostics must be precise enough to accomplish problem identification and rectification with minimal downtime.

3.  The system should be useable and understood well enough by produc-tion personnel so that an engineer is not always necessary when urgent decisions need to be made.

4.  The system should be simple and reliable and cause negligible down-time for repairs， routine calibration， and checks.

5.  The system must be costeffective; namely， it should cost less to operate and maintain than the expenses resulting from loss of produc-tion and machinery repairs that would have resulted if the machinery was not under monitoring and predictive surveillance.

6.  System flexibility to incorporate improvements in the state of the art is desirable.

7.  System expansion capabilities to accept projected increases in installed machinery or increases in the number of channels must be considered.

8.  The use of excess capacity in a computer system available at the plant can result in considerable equipment cost savings. System components that mate with theexisting computer systemmay， therefore， be a necessary prerequisite.

A condition monitoring system designed to meet these needs must be comprised of hardware and software designed by engineers with experiencein machinery and energy systemdesign， operation， and maintenance. Each system needs to be carefully tailored to individual plant and machinery requirements. The systems must obtain real-time data from the plant DCS and if required from the gas and steam turbine control systems. Dynamic vibration data is taken in from the existing vibration analysis system into a data acquisition system. The system can comprise of several high-perform-ance networked computers depending on plant size and layout. The data must be presented using a Graphic User Interface (GUI) and include the following:
1.  Aerothermal analysis: This pertains to a detailed thermodynamic ana-lysis of the full power plant and individual components. Models arecreated of individual components， including the gas turbine， steamturbine heat exchangers， and distillation towers. Both the algorithmic and statistical approaches are used. Data is presented in a variety ofperformancemaps， bar charts， summary charts， and baseline plots.
　
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