The flow characteristics of dense solid-gas mixtures transported through horizontal pipes were studied with glass beads and coal powders of various sizes (0.0028 to 0.0297 in.) in 1/2-, 3/4- and 1-in. glass pipes and a 1/4-in. steel pipe. Fluidized-bed feeders were utilized, thus permitting solid-gas ratios considerably higher (range 80 to 750) than those possible with conventional pneumatic transport. When such high solid-gas ratios are used, the flow of mixtures in transport lines is characterized by a large amount of slippage between gas and solids. The flow pattern is dicussed on the basis of visual observation through glass pipes.
A simple and interesting velocity relationship was noted, namely that the average gas velocity is about twice as large as the average solid-particle velocity. The solid-particle velocities and solid loadings in the pipe line were found to be primary factors affecting pressure drops, and the particle sizes and shapes, on the other hand, exerted a very slight effect on the pressure drops. This is apparently due to the fact that the solids move predominantly in the bottom of the pipes as agglomerated masses rather than as individually suspended particles. A pressure-drop correlation for the dense solid-gas mixtures is proposed, and applications and limitations of the correlation are shown.
