COMPUTER-SIMULATION OF FLUIDIZED-BED GRANULATION BY A 2-DIMENSIONAL RANDOM COALESCENCE MODEL

Computer simulation of granulation in a fluidized bed process was carr ied out using a two-dimensional random coalescence model. In this cont ribution, seed circles of two sizes were granulated by circular spray mist with radii obeying log-normal distribution on the basis of adhesi on probability, in which the adhesion force of spray mist was taken in to consideration. This simulation was then applied to fluidized bed gr anulation, in which a 7:3 weight ratio mixture of lactose and corn sta rch was granulated by an aqueous solution of hydroxypropylcellulose of several concentrations. Effects of moisture content and spray mist si ze on geometric median diameter of granules were investigated experime ntally and analytically. It was found that granulation phenomena, in w hich granule growth progressed with an increase in moisture content an d spray mist size, were very well simulated by the model proposed, the reafter, the mechanism of particle adhesion in fluidized bed granulati on was elucidated.