Effect of operating conditions on the drying of fine and ultrafine sand in a fountain confined conical spouted bed

Abstract

A study has been carried out on the influence process conditions and design parameters have on the drying in a conical spouted bed. Optimum parameters have been determined for the draft tube and the fountain confiner. Drying time is reduced when the spout region is enlarged. A distance between the bed surface and the lower end of the confiner in the 0.10–0.15 m range and a confiner of 0.5–0.9 m length minimize the drying time. Longer distances do not avoid entrainment, and shorter distances lead to higher pressure drop and minimum spouting velocity. Longer fountain confiners do not reduce significantly the drying time. Draft tubes with a reduced aperture ratio lead to longer drying times due to their adverse effect on the gas–solid contact. Aperture ratios above 60% cause a decrease in the efficiency of the process due to the higher gas flow rates required to achieve spouting regime.