ACOUSTIC EMISSION MONITORING OF WOOD CHIP REFINERS
By measuring the energy and frequency of acoustic emission from wood chips and fibers being broken down into mechanical pulp between opposing refiner discs, one is able to determine the physical parameters of the refined pulp, observe if rot is present, observe the degree of sulphonation and determine species of wood being refined. The apparatus comprises an acoustical transducer positioned to produce a signal representative of acoustical energy and frequency of wood chips between refiner discs, a filter for filtering out frequencies of the signal below about 25 kHz and a display device to display acoustical energy and frequency from the signal.