A new mechanistic perspective on the prediction of deposition velocity in turbulent liquid-solids pipe flow

Abstract

Multiple problems are associated with the formation of stationary solids deposits in pipes transporting liquids such as plugging, and concerns related to under deposit microbial activity and electrochemical degradation of metallic pipe walls. The latter is of importance when assessing internal corrosion risk in pipelines transporting hydrocarbon products along with small amounts of mineral sediment. In this context, operational experience and experimental observations have suggested that critical deposition velocities in turbulent flow tend to increase with the viscosity of the carrier fluid. Although some discussion on potential explanations of this phenomenon is available in the literature, no explicit analytical model has been offered yet to correctly contemplate this effect on the prediction of deposition velocities. This study introduces a new mechanistic approach for the problem of deposition velocity. Two analytical approximations for deposition velocity in turbulent liquid-solids pipe flow are derived for heterogeneous and homogeneous solids transport with low solids concentrations (e.g., < 10 %). The new model shows very good performance against experimental data in a wide range of pipe diameters, solids concentrations, solids densities and mean sizes, and liquid densities and viscosities, and provide new insights into the effect of the latter parameter.