ROTARY FURNACE - DYNAMIC-MODEL OF THE MOT IONS OF A BED

The motions of the granular bed inside a rotary furnace are governed b y complex dynamics consisting of two modes. The axial velocity of the active layer on top of the bed represents the fast mode, while the ove rall velocity in the bed follows a slower mode. The proposed nonlinear model focuses on the dynamics of the slow mode. The difficulties of a n analytic solution are avoided by a numerical method that employs sev eral correlations. The model can reproduce the experimental transient responses. It is concluded that rotary furnaces respond better to smal l amplitude excitations than to large ones; consequently, closed-loop control is well suited for this type of furnace.