The Sensor Validation Tool is a valuable addition to sensor preventative maintenance. It monitors the performance of pulp and paper sensors and is used to identify opportunities to maintain or improve sensor performance.
- Trends of quality measurements, software sensor predictions, and software sensor offsets. Trends of daily average offset, daily offset standard deviation, and average sample-to-sample measurement change help identify arising problems. Increased offset or measurement variability from sample to sample can indicate sensor measurement or sampling problems. Drifts in offset magnitude can indicate sensor drift.
- X-Y plots of various sensor measurements (e.g. freeness vs. fibre length), allow the user to compare different time periods and identify changes in interrelationships between process measurements. Different colors identify different time ranges.
- Valmet Factor Network Analysis Tool (Valmet FactNet) data reconciliation across the TMP mill uses online Valmet FactNet models to identify sensor problems. The individual sensor measurements compared to their FactNet predictions. The daily average deviation from prediction and the daily standard deviation of the measurement minus prediction are trended. This allows the user to identify quality measurements which are inconsistent with the common variability in the data set, and potentially identify calibration and sampling problems.
- Sensor alarms are shown in list form for each sampling point with the ability to sort for specific alarm types. Graphs of alarm frequency per day for specific alarm types allow the user to identify arising problems.
- Sampling condition monitoring allows the user to identify sampling problems. This includes monitoring sample consistency, latency chest temp, latency chest residence time, white water flow, white water consistency.
- Sensor Validation provides a status flag for each measurement that can be used for several purposes:
- Stored in PMIS systems (PI, WinMOPS, Info+21 , PHD, IMAS etc.) for monitoring.
- Used as a trigger to select alternate measurement, such as a software sensor, or modify control and optimization settings to exclude the given measurement.
- Sensor Validation can be configured to provide alternate measurements, software sensors, if sensor based measurement is questionable.
- Lab test results, similar to quality sensors and automated laboratory tests, can be monitored using the Sensor Monitoring Tool. For lab tests, it will be more common to identify problems with a specific measurement as opposed to systematic errors that occur with sensors such as sensor drift. Problems with lab tests can be reported in very similar fashion to the quality sensor signals.
- Sensor validation improves information accuracy and reliability and decision making processes, resulting in higher availability of advanced control applications and reduced maintenance costs.