Pneumatic Transport of Fine Granular Material

Abstract

Investigations show that production efficiency of foundries is influenced strongly by the nature and the use of means of transport. An important aspect of foundry transport is that of moulding sand. Impressive gains in space, as well as a decrease in capital investment may be had by applying pneumatic transport of moulding sand. The paper presents a basic approach to the nature of pneumatic transport of sand in a horizontal and circular tube, and indicates an approach to the calculation of the pressure gradient to be overcome. Although the analysis of the transport in a stationary laminar flow is interesting, it appears that sand is carried through a narrow sector of the tube, symmetrical to the vertical plane, and below the horizontal plane [1]. In the actual case of sand transport in a turbulent air current through a tube with a rough inner wall, sand is carried through the boundary layer at the complete circumference of the tube. It is easily seen how to generalize the approach for sand transport in a turbulent air current through a tube at an inclination to the horizontal, up to the vertical, and how to increase sand transport by injecting air which increases the turbulence of the boundary layer carrying the sand. After the various parameters for the stationary transport have been deduced, it appears to be possible to analyze the introduction of the sand grains into the air current as well as their acceleration to stationary motion [1].