NON-STATIONARY DRYING KINETICS IN A BATCH PHARMACEUTICAL FLUIDIZED BED COATING PROCESS

ABSTRACT

In this paper a physically based mathematical model for the description of particle wetting, temperature and humidity characteristics during a non-stationary fluidized bed spray-drying of granules or during a non-stationary fluidized bed coating in a Hüttlin®-Kugelcoater HKC 05-TJ is introduced. Using this model it is possible to calculate the humidity and temperature of the air, the degree of particle wetting, the temperatures of both the liquid layer and the particles under consideration and the influence of the wall of the apparatus and its surroundings. The effects of start-up and shut-down processes on the results as well as the time dependence of the discontinuous process with varying process parameters such as the amount of liquid sprayed in and its temperature, the amount of fluidising air and its temperature are simulated and the results were compared with those obtained experimentally using a Hüttlin -Kugelcoater HKC 05-TJ. Furthermore, the growth of the bed and the increase of particle masses during a discontinuous coating and granulation processes were taken into account in a simplified manner.

Key Words and Phrases:

• Dynamic simulation
• Granulation
• Particle formation
• Mathematical model