TABLE OF CONTENTS In contrast to fluids which are transferred almost ' exclusively through pipelines with pumps or blowers, a greater variety of equipment is employed for moving solids to and from storage and between process equipment. Most commonly, solids are carried on or pushed along by some kind of conveyor. Solids in granular form also are transported in pipelines as slurries in inert liquids or as suspensions in air or other gases.
In short process lines slurries are readily handled by centrifugal pumps with open impellers and large clearances. When there is a distribution of sizes, the fine particles effectively form a homogeneous mixture of high density in which the settling velocities of larger particles are less than in clear liquid. Turbulence in the line also helps to keep particles in suspension. It is essential, however, to avoid dead spaces in which solids could accumulate and also to make provisions for periodic cleaning of the line. A coal-oil slurry used as fuel and acid waste neutralization with lime slurry are two examples of process applications.
Many of the studies of slurry transfer have been made in connection with long distance movement of coal, limestone, ores, and others. A few dozen such installations have been made, in length from several miles to several hundred miles.
Coal-water slurry transport has been most thoroughly investigated and implemented. One of the earliest lines was 108 miles long, 10 in. dia, 50 60wt % solids up to 14 mesh, at velocities of 4.5 5.25 ft/sec, with...
