ANALYSIS OF A ONE-DIMENSIONAL FLUID DYNAMIC MODEL FOR DILUTE GAS-SOLID FLOW IN A PNEUMATIC DRYER WITH A SPOUTED BED TYPE SOLID FEEDING SYSTEM

Abstract

ABSTRACT The pneumatic bed with a spouted bed type solid feeding system reported by Ferreira and Freire (1992) allows stable solids conveying in a wide range of solids flow rates. This is being developed with the aim to dry products with high initial moisture contents. A one-dimensional model based on continuity and momentum balances is used to describe non-accelerating gas-solids flow and to predict pressure gradient data. Experimental data were obtained for the transport of glass spheres (db=1.00 to 2.BS mm) in galvanized iron pipes of four different diameters (Dt53.4 to 149.0 mm). Good predictions for the pressure gradients were obtained from the model. Estimated values of the solid-fluid interaction forces and slip velocities, however, were often not physically consistent. This result leads to the conclusion thac the one-dimensional model does not provide a good description of the physical phenomena and flow pattern involved in dilute pneumatic vertical transport.