Drying kinetics of sawdust in conical spouted beds: Influence of geometric and operational factors

Drying of sawdust is important to manufacture particleboards and pellets as well as to improve efficiency of energy valorization. The study started with drying performance of sawdust, with high moisture of 60 wt% (db) and tendency to agglomerate, in conical spouted beds and time evolution of sawdust moisture content and of air humidity was obtained. An operability regime map was obtained for sawdust with different moisture content. The influence of air temperature and velocity, bed mass and the geometric factors of the dryer on drying kinetics was determined. A new drying model was proposed to predict the drying behavior of beds consisting of sawdust in conical spouted beds dryers by fitting experimental data of time evolution of sawdust moisture ratio. Suitable fitting parameters of the model were expressed as function of the operating conditions and of the dryer geometric factors and the goodness of the model was assessed by the statistics parameters. Drying rate and drying time to equilibrium moisture content ranges were determined. On the basis of the experimental drying study, the most suitable design geometric factors of the dryer (cone angle and gas inlet diameter) were proposed, as well as the most suitable process conditions for high drying capacity. [Display omitted] •Drying kinetics and drying rate of beds made up of sawdust were determined.•The influence of geometric factors and operating conditions on drying was evaluated.•Conical spouted bed dryer promotes shorter drying time than other dryers.•A novel model based on dimensionless moduli was proposed to simulate sawdust drying.