Analysis of flow regimes and volumetric phase fraction of vertical upward gas–liquid–solid three-phase flow

Gas–liquid–solid flows are important in many industrial productions and processes. The hydrodynamic of gas–liquid–solid three-phase vertical upward flows and how the presence of solid particles may affect the two-phase flow system properties are less investigated and understood compared to gas–liquid two-phase flow. The present study is an attempt to bridge this gap in vertical pipe through an experimental investigation of flow regimes and volumetric holdup with solid particles less dense than liquid phase, similar to hydrates. The experiments are carried out using air–water and polypropylene pellets solid particles and a 30 mm ID vertical pipe. Three solid volumetric concentrations (5%, 10%, and 20%) were investigated, and the results are compared with those obtained with gas–liquid two-phase flow. In the conditions of experimental measurements carried out, four flow regimes, namely cap bubble-to-slug, slug, churn, and dispersed bubble flows, were reported. These flow regimes were observed on both two-phase and three-phase flow conditions. Meanwhile, the injection of solids induced a shift of slug-to-churn flow transition. The study allows notably to prove that the existing predictive models of flow transition and liquid holdup developed for two-phase flow can be extended to three-phase flow by considering the gas–liquid–solid three-phase as gas–slurry two-phase flow.