Theoretical and experimental study of a direct contact thermal screw dryer for biomass residues

In the present study a one-dimensional model has been developed for the calculation and design of a direct contact thermal screw dryer for biomass residues. The model input data are inlet temperatures and the flow rates of gas and biomass (washed grape pomance). An experimental facility has been developed in order to measure the temperature inside the dryer along time. The results obtained indicated that Frössling correlation used for the development of the model provided a satisfactory fitting of the experimental data. An optimal dryer length of approximately 3 m has been calculated for an inner diameter of 0.22 m.