Method and system for detecting plate clashing in disc refiners

A refiner plate clash detection system comprising:

• (a) means for receiving a first signal having a significant increase in level at at least one distinct predetermined frequency related to the clash, the number of segments at a given radius of a single disc and the rotational rates of the discs,
• (b) filter means having a passband matched to pass said distinct frequency of said signal to provide a filtered output signal,
• (c) means for smoothing said filtered signal,
• (d) means for establishing a threshold level,
• (e) comparator means for receiving said smoothed signal and for comparing it with said threshold level and for providing an output signal of predetermined form, upon said smoothed signal's exceeding said threshold level, and
• (f) means for receiving said output signal for generating an alarm operation signal in response thereto.

A method of detecting plate clashing in disc refiners which comprises:

• determining the frequency at which a significant increase in signal level occurs during a plate clash, by the formula
• f.sub.o =n .sup..SIGMA..sub.R
• wherein
• f.sub.o =a clash frequency (expressed in Hertz)
• n=the number of segments, at a given radius per single disc and
• .SIGMA..sub.R =the sum of the rotation rates (expressed in Hertz) of two adjacent discs enclosing a given volume,
• monitoring the acoustic or vibration frequencies of the disc refiner;
• continuously determining the signal level of the acoustic or vibration frequencies;
• continuously comparing the signal level at said determined frequency with a predetermined threshold signal prior to the plate clash;
• and
• automatically signalling when the signal level exceeds the threshold level.

A method of detecting plate clashing in disc refiners which comprises:

• determining the frequency at which a significant increase in signal level occurs during a plate clash, which distinct frequency is related to the clash, the number of segments at a given radius of a single disc and the rotational rates of the discs;
• monitoring the acoustic or vibration frequencies of the disc refiner;
• continuously determining the signal level of the acoustic or vibration frequencies;
• continuously comparing the signal level at said determined frequency with a predetermined threshold signal prior to the plate clash;
• and automatically signalling when the signal level exceeds the threshold level.