Moisture content distribution in semibatch drying processes. I. Constant particle drying rate



Semibatch drying processes include a period of feeding wet particles during drying. This results in different residence times of particles in the dryer and thus generation of a moisture content distribution. Describing these processes in a model that takes this moisture content distribution into account can be complicated. Knowledge of minimum or maximum values of the moisture content distribution is often desired for subsequent process steps or end product quality. This article presents a model that not only describes the overall average moisture content in time during semibatch drying put also gives the evolution of the moisture content distribution in time. A novel solution strategy based on the “method of moments” and “method of characteristics” is presented that solves the resulting ordinary differential equations in a piecewise manner. Simulations for a semibatch fluidized bed drying process give results that are feasible and realistic. © 2012 American Institute of Chemical Engineers AIChE J, 2012