AN IMPROVED 2 LAYER MODEL FOR HORIZONTAL SLURRY PIPELINE FLOW

A model for predicting head losses for coarse-particle or settling slurries has been obtained. Experimental data for isothermal flows of sand, gravel and coarse coal slurries in pipes of industrial scale have been used to obtain the correlations in the model. The model differs from previous versions in the way it deals with the concentration of the lower layer and in the role ascribed to the finest (-74-mu-m) particles. The fraction of contact load, which contributes sliding friction at the pipe wall, is found to be primarily a function of the ratio of the mean flow velocity to the settling velocity of the mass median particle size in the (+74-mu-m) fraction. The correlations are restricted to mixtures containing less than 35% (+74-mu-m) particles by volume.