Optimization of a continuous through‐circulation dryer

A mathematical model of a through-circulation packed bed dryer is presented in this paper. The semitheoretical model treats the case of constant rate drying in a deep bed of granular solids under initially uniform drying conditions. Experimental data for drying in superheated steam, mixtures of superheated steam and air, and air alone showed good agreement with predictions of the model. Based on the model, a static optimization method is developed for optimal operation of a continuous through-circulation dryer subject to the inequality constraints of maximum permissible air-horsepower per unit bed area and maximum permissible local final moisture content in the bed. A nonlinear capacity function is defined in terms of the independent drying variables and is maximized under the above nonlinear restraints.