Estudo das variáveis fluidodinâmicas na secagem de polpa de acerola em leito de jorro convencional.

Abstract

This work deals with the study of the dynamics of the conventional spouted bed drier for the drying of West Indian cherry (Malpighia emarginata, DC) pulp. At first, the fluid dynamics parameters that allow a good quality of the spout when pulp is present in the bed, were established from the analysis of the characteristic curves. The local and average solid circulation, axial and radial profiles of pressure drop were measure for various operational conditions. The results show that as long as the pulp to inert particles mass ratio was increased, greater values of the maximum pressure drop and minimum spouting pressure drop are needed. On the contrary, the minimum spouting air rate was not significant, influenced by the percentage of pulp. It was also observed that the pulp in the bed reduces the solid circulation rate. The experimental fluid dynamics parameters were compared with the ones predicted by correlations obtained from literature. It was found that the maximum pressure drop, minimum spouting pressure drop and minimum spouting velocity are better predicted by the ASENJO et al. (1977), LEFROY & DAVIDSON (1969) and SAMPAIO (1978), and CHOI & MEISEN (1992) equations, respectivally. In general, the available correlations, developed for conventional beds without the presence of suspensions are not appropriated to describe the experimental data. It appear that empirical correlations including the effect of the suspension on the fluid dynamics of the spouted beds must be proposed in order to obtain good agreement with the experimental observations.