A METHOD FOR PROCESS MONITORING AND DETERMINATION OF OPERATIONAL END-POINT BY FREQUENCY-ANALYSIS OF POWER-CONSUMPTION IN AGITATION GRANULATION

Power consumption was measured and analyzed in order to develop a new method for process monitoring and controlling granule growth by wet gr anulation in a high speed mixer. It was shown that the power spectral density function obtained by fast Fourier transform analysis of power consumption had two patterns of peaks. The effects of the operational variables on the frequency of these peaks and on behavior of these pea ks at every moment of granulation were investigated. It was found that the principal peak was specific to the granulation and had its origin in the collision of the granule particles with the agitator blade. Th e other peaks, however, were judged to be caused by the electrical cha racteristics of the motor drive and irrelevant to the granulation. Qua ntitative relations between the change in the intensity of the specifi c peak and the granule growth were investigated to demonstrate that th e process monitoring and control of the granule growth could be realiz ed by tracing the behavior of the specific peak. Determination of the operational end-point by means of this method was also discussed.