IN-CHAMBER BLENDING OF MALTODEXTRIN AND SALT IN A SMALL-SCALE SPRAY DRYER

Abstract

The technique of in-chamber blending in practice has been investigated, by altering the configuration of a Buchi B290 small-scale spray dryer having a two-fluid nozzle, through adding extra pipes (long and short) into the chamber to feed dry particles in order to increase the particle numbers per unit volume. Experiments were performed whereby long or short pipes were used to estimate the shift in the particle size distribution due to differing amounts of agglomeration. Maltodextrin (DE18) particles were fed into the chamber with 20% salt solution sprayed through the atomizer. The longer pipe allowed higher particle concentrations near the atomizer, and therefore more agglomeration than the short pipe configuration, which gave lower number concentrations. On average, one salt droplet collided with an average of 5.5 maltodextrin particles for the short-pipe configuration and 4.1 maltodextrin particles for the long-pipe configuration. There was also a significantly greater shift in cumulative particle sizes for the long pipe configuration (2.7% in mean size) compared with the short pipe case (2.1%).