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

Pavel Vlasak,Zdenek Chara,Jiri Konfrst,Mikolas Kesely,Vaclav Matousek,P Dančová,J Novosad

doi:10.1051/epjconf/201921302094

Pavel Vlasak, Zdenek Chara + Show 5 more

Open Access

https://doi.org/10.1051/epjconf/201921302094

Copy DOI

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.

Highlights

Pipeline systems used in different industrial, mining, transport and technological applications often contain inclined sections
This paper focuses on experimental investigation of the effect of pipe inclination on settling slurry concentration distribution, pressure drops, and deposition limit velocity
Frictional pressure gradient was higher in the ascending pipe than that in the descending pipe, the difference decreases with increasing velocity and pipe inclination angle

Summary

Introduction

Pipeline systems used in different industrial, mining, transport and technological applications often contain inclined sections. The stratification is dependent on the pipeline system and transported material parameters, mainly on pipe dimension and roughness, material size and density, the flow velocity, slurry concentration, and affects both the pressure drops and the operational velocity. Wilson [12] proposed a two-layer model for settling slurries with fully stratified flow pattern in horizontal pipes. Shook and Roco [6] adapted force balance equations of a two-layer model for a partially stratified slurry in inclined pipe section. Friction losses of settling slurries flow are strongly dependent on the concentration distribution, the experimental data containing measured solids distributions, and especially in vertical and inclined pipes, are extremely scarce in the literature [1, 16, 17]. This paper focuses on experimental investigation of the effect of pipe inclination on settling slurry concentration distribution, pressure drops, and deposition limit velocity. The experimental data can be used for predictive models that will deals with effect of pipe inclination on flow behaviour of fine-grained slurries

Experimental Equipment and Material

Pressure gradient

Local Concentration

Deposition limit velocity

Conclusions