Reducing energy consumption in spray drying by monodisperse droplet generation: modelling and simulation

The possibilities of reducing energy consumption in spray drying by monodisperse droplet generation have been explored. From heat/mass balances and droplet travel dynamics in a single-stream spray dryer, correlations have been established for the drying gas temperatures that satisfy given outlet product moisture contents for droplet streams of different diameters-with skimmed milk as a case study. The results suggest that energy consumption can be reduced by up to 90%, compared to what obtains in a conventional system that produces droplet sizes up to 10 times the desired size. An experimental single-stream monodisperse droplet dryer, based on piezoelectric atomisation has been constructed, with an imaging system for future validation studies.