BEAN DRYING IN FIXED, SPOUTED AND SPOUT-FLUID BEDS - A COMPARISON ANDEMPIRICAL MODELING

In this work the drying of IAC-Carioca bean was analyzed experimentall y in fixed, spouted and spout-fluid beds. A laboratory scale, batch op erated apparatus was used. To obtain experimental data, a factorial de sign technique was used and the influences of the following variables on the process were evaluated: the solids load, initial grain moisture and drying air temperature. This analysis was done for each dryer by means of drying curves, evolution of grain temperature over time, dryi ng rate and statistical results obtained from factorial design. An ene rgy evaluation was also done and used as a means of comparison between the dryers studied. The three dryers operating under the same conditi ons showed very similar behavior and the fixed bed dryer showed a perf ormance slightly better. With this work the potential of using spouted bed grain dryerswas confirmed and the possibility of using the spout- fluid bed as a dryer was verified. Two empirical models were proposed and their parameters were correlated with experimental variables. A se nsory evaluation was also performed for the purpose of evaluating the effects that the high drying temperatures had on the grain's potential value as food.