A NEW POLICY FOR THE ESTIMATION OF THE COURSE OF SUPERSATURATION IN BATCH CRYSTALLIZATION

A continuing effort is being made in the development of on-line sensor s for the monitoring and control of crystallization processes. Applied on-line calorimetry provides an estimate of the instantaneous heat re lease due to crystallization advancement. Two approaches to the implem entation of such ''soft sensors'' are described and difficulties arisi ng in the case of on-line multipurpose non-isothermal applications art outlined. Off-line estimates of concentration and supersaturation pro files during typical batch evaporative crystallizations are reported. Particular attention is paid to the detection of second, late nucleati on bursts occurring in cases of poor crystal growth and rapid temperat ure decay.