Effect of pipe inclination on flow behaviour of fine-grained settling slurry

Institute of Hydrodynamics of Czech Academy of Sciences, v. v. i., Pod Patankou 30/5, 160 00, Prague 6, Czech Republic

^* Corresponding author: vlasak@ih.cas.cz

Published online: 28 June 2019

Abstract

The effect of flow parameters of fine-grained settling slurry on the pressure drop-velocity relationship, deposition limit velocity and local concentration distribution was studied in an experimental pipe loop of inner diameter D = 100 mm with inclinable pipe sections for pipe inclination ranging from – 45^° to +45^°. The slurry consisted from water and narrow particle size distribution glass beads of mean diameter d₅₀ = 0.18 mm. The concentration distribution was studied with application of a gamma-ray densitometry. The deposition velocity was defined as the flow velocity at which stationary deposit started to be formed at the pipe invert. The study revealed the stratified flow pattern of the studied slurry in inclined pipe sections, for slurry velocities below to the deposition limit sliding or stationary bed were created in ascending pipe sections. For low pipe inclination (α < ± 25^°) the effect of inclination on local concentration distribution was not significant. Mean transport concentration for descending flow was lower than that for the ascending flow Deposition limit in inclined pipe was slightly lower than that in horizontal pipe. Frictional pressure drops in ascending pipe were higher than that in descending pipe, the difference decreased with increasing velocity and inclination.