Dense phase vertical pneumatic conveying

Vertical pneumatic conveying was studied in a 3-in. I.D. line, nineteen feet in length. Experiments were performed in both the empty line and in the line containing screen packing. Whereas in the conventional empty line choking occurs as the gas velocity is decreased, stable operation was possible in the screen packed line from the dilute conveying region down through the dense phase conveying region to the fluidizing region. A theoretical treatment proposed by Leung et al. to describe vertical transport of solids by liquids was used to predict the pressure drop/gas velocity relationship reasonably well for the screen packed line. Indications were obtained that the same equations may also be applied to conventional vertical pneumatic conveying in an empty line.