HEAT-TRANSFER AND GRANULE GROWTH-RATE IN FLUIDIZED-BED GRANULATION

In this study, the mechanism of heat transfer between gas and granule in fluidized bed granulation was investigated, and the granule growth rate was predicted using heat transfer and moisture balance measuremen ts, First of all, the heat transfer coefficient between gas and granul es in a fluidized bed was measured using granules of four different si zes, and the experimental data obtained over a wide range of granule R eynolds number were found to be expressed as Nu(p) = 2 + 0.6Re(p)(1/2) Pr(1/3), where Nu(p), Re-p and Pr indicate granule Nusselt number, Rey nolds number and Prandtl number, respectively, Secondly, a model in wh ich the heat transfer and the moisture balance were taken into conside ration was proposed to predict the moisture content and granule growth rate during granulation, It was also confirmed that the experimental results at various binder (water) flow rates and inlet air temperature s were in good agreement with those predicted from the theory, As a re sult, the mechanism of the heat transfer was elucidated and the granul e growth rate during granulation could be predicted with high accuracy .