INTERMITTENT DRYING OF CORN KERNELS IN A FLOTATION FLUIDIZED-BED - EXPERIMENTAL-STUDY AND MODELING

This work concerns the drying of maize in a flotation fluidized bed by intermittent blowing of hot air. The aim of the study was on the one hand to determine the effect of this drying technique not only on the energy consumption, but also on the grain quality, and on the other ha nd to develop a mathematical model which simulates the observed phenom ena. The effect of the conditions of intermittent drying as the durati on of aeration and rest periods, respectively, t(a) and t(r) has been examined. The ratio t(r)/t(a) does not affect the drying kinetics for values greater than 2. Besides, intermittent drying consumes less ener gy than drying with a continuous air flow because it reduces the actua l drying duration by 50%. However, for the operating conditions of thi s study, this technique did not allow an improvement in the wet-millin g quality. A mathematical model adapted to intermittent drying has bee n developed. This model leads to very good predictions on the evolutio n of air humidity, dryer temperature, grain moisture content and tempe rature, but also the variation of maize wet-milling and proteic qualit ies. This model can be used for the control of drying process under op timal conditions. Copyright (C) 1996 Elsevier Science Ltd.