Cocurrent Downflow Fluidized Bed Dryer: Experimental Equipment and Modeling

Abstract

ABSTRACT Product damage, high energy consumption, and nonhomogeneous final properties are present in typical drying operations such as pneumatic drying, fluidized-bed dryers, and upward circulating fluidized-bed dryers. The downer bed has been shown to be a good technique for this processes. The objective of this work is to test an experimental downflow dryer and model its operation. The equipment consists of a 5-m-high stainless steel duct with 0.17 m i.d. Gas velocity was varied between 0.3 and 8 m/s in co-current solid flow varying between 0 and 50 kg/m2s. Drying rates, pressures, and total flux for solid and gas are determined. Temperature profiles for gas and solid along the radial and axial directions are determined and tested with model predictions. The solid particles were previously dried turnip (Brassica napus) seeds. The equipment shows good operational conditions and facilities for parameter determination, but must be complemented with better equipment for particle concentration determinations. The model's predictions of pressure, gas velocity, solid concentration, and temperature are compared with our experimental values or those reported in the literature.