Pipeline flow of coarse particle slurries

Abstract

The horizontal pipeline flow of coarse-particle slurries has been examined. The study includes an evaluation of previous work, an experimental investigation and a presentation of improved modelling techniques for determining pipeline design parameters.

The experimental investigation was carried out to obtain an improved database for modelling the flow of coarse-particle slurries. Tests were conducted using sand slurries and coal slurries in pipes of industrial scale. Frictional headlosses, delivered solids concentrations, concentration distributions and velocity distributions were measured as functions of in situ solids concentration and mean velocity. Solids deposition velocities were determined visually using transparent pipe sections.

The experimental results were used to develop an improved two layer model for estimating frictional headlosses, a force balance model for concentration distributions and a method for predicting deposition velocities. The fraction of contact load, which contributes sliding friction at the pipe wall, was found to be primarily dependent on the ratio of the mean flow velocity to the settling velocity of the mass median coarse (+0.074 mm) particle size.

The models contain empirical correlations which incorporate a wide range of experimental conditions but are restricted to mixtures containing less than 35% coarse particles by volume. The correlations were tested using carrier fluids which were essentially Newtonian with viscosities less than 4 mPa.s.