Refiner plate clash detection using an embedded force sensor

Plate clash in disc refiners continues to detract from the efficiency of mills, reducing plate life and affecting production. The work presented here examines the potential of a piezoelectric-based force sensor for clash prediction. Four sensors were installed in an operational reject refiner over a three-month period at the Catalyst Paper mill in Port Alberni, B.C., Canada. Signals from these sensors were processed for prediction of plate clash and the results were compared to the accelerometer-based plate protection system currently in use at the mill. The force sensors consistently gave advanced warning of a clash event, many seconds before the accelerometer. A sensitivity study showed that the new system was able to outperform the accelerometer system over a range of detection settings, and that the accelerometer could not be tuned to match the performance of the new system.