Further theoretical studies on rotary drying processes represented by distributed systems

Mathematical tools for studying particle transport in rotary drying and cooling processes are developed in this paper. In contrast to conventional approaches aimed at deriving empirical or semi-empirical correlations, a rigorous mathematical analysis which employs differential calculus and analytical geometry is emphasised in the current research. These developments allow accurate computations of solid flowrate, retention time and particle holdup in rotary dryers with arbitrary flight configurations. Consequently, optimal dryer configuration design in terms of drum dimension, flight number and geometry can be achieved through a better understanding of the mathematical insight of rotary drum performance. Techniques developed using this method are applied to the distributed parameter model established earlier by the authors (Wang et al., 1993) to replace out-dated correlations for the determination of retention time and solid holdup. As a result of the new developments, the distributed parameter approach to the dynamics of rotary drying processes becomes more general and more reliable