SIMULATION OF QUANTITATIVE FAULT-DIAGNOSIS IN BACKFILL HYDROCYCLONES

A quantitive fault diagnosis system for backfill hydrocyclones using m odelling and parameter estimation was developed. The system was evalua ted using simulation, thereby allowing arbitrary process variable faul t levels and combinations of faults to be introduced into the system, as well as controlled levels of random noise in the process output mea surements. The fault diagnosis system determines that point in the sea rch space that minimises the difference between the measured process o utputs and the process outputs predicted by previously determined proc ess models by simultaneously adjusting the model parameters. At the mi nimum, estimates of the unmeasurable process variables are provided by the model parameters. A gradual increase in the feed - 75 micron frac tion was considered, as well as a simultaneous increase in both the vo rtex finder and spigot diameters. Faults could clearly be identified b y observing the trends in inferred variable values over time. Subjecti ve decisions as to the level of incipiency of faults can be reduced by performing quantitative alarm analysis on these values. Both non-para metric and parametric alarm analysis was evaluated and it was found th at a combination of these methods would enable timeous detection of bo th gradual and abrupt faults. The use of quantitative fault diagnosis to detect incipient faults in process parameters could be of great val ue in maintaining production levels, planning maintenance and optimisi ng system performance.