Experimental study of residence time in a direct rotary dryer

Prediction of residence time in rotary dryers is useful for equipment design as well as for the right selection of operation conditions in order to obtain the optimal unit functioning. An empirical relationship for residence time estimation that may be applied when the dryer slope is zero or different from it is presented in this work. It was derived from experimental testing carried out with biological origin particulated solids (fish and soya meal, sawdust) and from mineral origin (sand) in a pilot rotary dryer. The fitting degree of the experimental data to those predicted by reported equations was also established here.