Drying behavior of uniform and binary mixture of solids in a batch fluidized bed dryer

Abstract

The drying behavior of solids has been studied in a batch fluidized bed dryer using different uniformly sized solids and various binary mixtures of solids at different dilutions in falling rate periods one and two. To predict the drying behavior in falling rate periods one and two, correlations were developed for uniformly sized particles and for binary mixture of solids. The mixing index has been incorporated to develop the correlations for two types of falling rate periods. The average moisture content has been taken to predict the effect of various parameters on drying behavior. The correlations for average moisture content have been developed by considering the effect of various parameters such as air velocity, initial moisture content of solids, temperature, initial bed height and particle diameter for uniformly sized particles. The effect of various parameters on drying behavior has been investigated for different binary mixture of solids. To predict the drying behavior of binary solid mixtures, mixing index has been incorporated with other parameters in correlation development. The mixing index has been found to decrease with increase in the dilution of fine particles with coarse particles. The drying behavior of binary mixture of solids has been found to be similar to the uniformly sized particles. Effect of dilution on drying has been investigated, where in it is noticed that 10% diluted binary mixture gave highest drying rate and no improvement in drying behavior is found for dilution beyond 30%. The work finds importance in practice, as it involves the use of solid mixtures. The experimental results were compared with the predicted values and are found to be in good agreement.