Using the Box-Behnken experimental design to optimise operating parameters in pulsed spray fluidised bed granulation.

In this work, the influence factors of pulsed frequency, binder spray rate and atomisation pressure of a top-spray fluidised bed granulation process were studied using the Box-Behnken experimental design method. Different mathematical models were developed to predict the mean size of granules, yield, relative width of granule distribution, Hausner ratio and final granule moisture content. The study has supported the theory that the granule size can be controlled through the liquid feed pulsing. However, care has to be taken when the pulsed frequency is chosen for controlling the granule size due to the nonlinear quadratic relation in the regression model. The design space of the ranges of operating parameters has been determined based on constraints of the mean size of granules and granule yield. High degree of prediction obtained from validation experiments has shown the reliability and effectiveness of using the Box-Behnken experimental design method to study a fluidised bed granulation process.