Characterization of particulate materials in respect to drying

This article reviews experimental methods for the determination of single-particle drying kinetics. Four such techniques (conventional microbalance, acoustic levitator, and drying tunnel, as known from the literature, and a novel method involving the use of a magnetic suspension balance) are discussed and compared. The magnetic suspension balance enables single-particle experiments within the widest range of process parameters with very good resolution and accuracy. Kinetics and/ or equilibria for adsorption, desorption, or drying can be determined. To complete characterization, a simple method for measurement of packed bed thermal conductivity is presented on the basis of experiments with wet zeolites. The derivation of particle or crystallite properties from the data is critically discussed.