Effect of Partial Processes of Drying on Inert Particles on Product Quality

Particulate materials of high moisture content (suspensions, pulps) can be advantageously dried in the mechanically spouted bed (MSB)-dryer with inert packing. Due to the flow characteristics the partial processes of the inert bed drying (coating, drying, wearing of the dried coat) can be well controlled. The particle size of the product, which is one of the most important quality requirement is controlled e.g. by the wearing time in the inner conveyor screw, that is by its rotation speed and conveying length. However, this latter can be increased only simultaneously with the spouted bed height together with pressure drop increase. To avoid this drawback a modified MSB-dryer was developed. By this way the particle-size can be controlled in vider range, independently from the bed height. The results were demonstrated by drying tests carried out with microwave pretreated potato pulp.