Experimental study of low concentration sand transport in wet gas flow regime in horizontal pipes

• This experimental study is the first study that investigates particle transport at very low liquid hold up flows.
• A comparison of the results shows that the critical velocity, increases with a decrease in gas flow rate.
• A comparison of the results shows that the critical velocity increases with an increase in particle concentration.
• A comparison of the results shows critical velocity increases with an increase in particle size and pipe size.
• Experimental data shows that the critical velocity for irregular shape particles is higher than spherical shape particles.

This paper examines the minimum flow rates of gas and liquid necessary to keep particles moving in a horizontal flow line with emphasis on flows with high gas–liquid ratios resulting in stratified wavy flow with small liquid hold-up. Experimental results are presented for flows in 0.05 m and 0.1 m diameter pipes varying particle size and shape. The types of particles used are sand and glass beads. Additionally, experiments are performed for two particle volume concentrations: 0.01 and 0.1 volume percent. Varying these physical parameters, the effects of particle concentration, particle shape, particle size and pipe size are experimentally investigated in this study. Finally, available models in the literature to predict sand transport critical velocity in multiphase flows is examined using the experimental data obtained in this study. The comparison shows none of the available models can predict critical velocity accurately in the stratified wavy flow regime at very small liquid hold-up.