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Etracker-OLM™
Etracker-OLM overcomes the universal data analysis problem which is the need to correct measured data to some consistent standard.
Etracker-OLM results, as presented to the user, are the deviation of the actual measured results, from those that would be expected if the plant were operating as designed and in its new-and-clean condition.
Etracker-OLM results are ready to be used for decision making.
The most significant results, generator output and heat rate deviation from expected, along with the uncertainty of the answers, are continuously displayed on the main computer screen. If desired, the user may quickly select individual trend curves from among approximately 30 standard measurements, or develop user defined trend curves for any of the parameters monitored by the program. A typical main screen result is shown next.
Note that the turbine cycle heat rate curve (blue) is drawing a steady horizontal line except for a drop in heat rate at about the middle of the screen. The generator output curve is also horizontal except for the sharp rise in the center of the screen. The curves should be horizontal if all is running well. The quick change in both heat rate and generator output, however, is an event the needs understanding.
The user may also define an event, either short term such as the one in the main screen illustration or long term, select any or all the possible parameter changes that might occur, and the program will produce an Operating Degradation Profile. This presents on one page, in the form of a columnar graph, all the parameters that have changed significantly, usually limited to more than 0.5%, from the beginning to the end of the defined event.
An Operating Degradation Profile for the event identified in the previous main screen, is shown next.
The six blue columns on the left are all changes in inlet and extraction pressures associated with the LP turbine. Clearly the incident does not involve anything associated with the HP or the IP turbine. The change was traced to a flow control valve for hot water, extracted from the boiler feed pump inlet to a glycol heater. It had been stuck in the fully opened position, bypassing significant quantities of hot water to the condenser. When it was finally closed the heat rate improved and the generator output increased.
All, typically 60 to 80, parameters are permanently stored on the computer hard drive, and may be stored in the users archive system. This facilitates application of the concept: Simplicity, until complexity is needed. i.e., if the output and heat rate are at expected levels there is little need to worry further about the unit. However, if undesirable changes have occurred the detailed historical data is readily available for analysis.
Each on-line monitoring interface program is specifically designed for one specific Etracker-Model. The program runs continuously, gathering data, performing calculations, and storing the results. The Etracker-Model is operated at the identical conditions to those imposed on the unit being monitored. The Etracker-Calculation-Module determines the expected performance, which is then compared with the measured values and the differences are reported and stored continuously. Differences are reported as a percentage, or an arithmetic difference, depending on which is most useful to the user.
Conditions on a continuously monitored unit are always changing at some rate, which makes it difficult to obtain a meaningful value for deviation of performance from best expected. Etracker-OLM addresses this problem by obtaining a set of operating data, calculating results, storing these results temporarily, and then repeating this process at least ten times. Mean values of differences and the standard deviation are then determined and mean values plus the uncertainty of the results (calculated from the standard deviation) are then reported, and permanently stored for future use. This gives the user the ability to select only the data with the lowest level of uncertainty for condition analysis.
Etracker-OLM provides accurate trending of unit performance, an extremely important feature.
It gives important diagnostic insights when degradation occurs. For example, a 2% change in output that occurs within fifteen or twenty minutes has much different implications than the same change occurring over a period of several weeks or months.
Since instruments tend to drift slowly, if at all, the bias errors are essentially eliminated for relatively short time changes, greatly improving the accuracy of identification of changes in performance by Etracker-OLM.
Reliability is an extremely important consideration for any plant manager. Trended performance information can be a very useful aid in diagnosing the significance of changes in mechanical condition, e.g., vibration levels, shell temperature, shell and rotor expansion measurements, etc.
Trending gives the ability to anticipate potentially serious impacts from initial indications.
Trending gives the ability to know the current cost of generating power and make you more competitive in the wholesale marketplace.
Information is provided that assists the plant manager in determining the time to schedule maintenance and the resulting performance recovery.