Experimental investigation on drying performance of pharmaceutical granules in a pulsation-assisted fluidized bed dryer

Fluidized bed drying has been widely employed in pharmaceutical manufacturing processes. Due to the considerable cohesiveness of wet pharmaceutical granules, channelling phenomena pose significant challenges to fluidization and drying. In this work, the drying performance of pharmaceutical granules in a pulsation-assisted fluidized bed dryer was experimentally investigated. The drying rate and energy efficiency were investigated with representative pharmaceutical powders, including active pharmaceutical ingredients (APIs). It is found that the pulsed airflow is effective in enhancing the drying rate at higher superficial gas velocity. A lower pulsation frequency is more favourable to improve the drying rate. During the constant rate period, energy efficiency is between 60% and 45% for the drying process, while the energy efficiency decreases to 10% during the falling rate period. A pulsed fluidized bed dryer has shown a higher energy efficiency than a conventional one with a constant air flow. Among nine thin-layer drying models examined in this work, the Midilli and Kucuk model has shown the best agreement between the experimental data and the predicted results.