The effect of gas injection on the hydraulic transport of slurries in horizontal pipes

Abstract

The hydraulic transport of solid particles in a horizontal pipe is a well known practice in chemical plants and mining industry. The injection of gas into the flowing slurry results in a variety of flow patterns that affect the pressure gradient of the three-phase mixture in comparison with solid–liquid slurry flow. Furthermore, it may reduce or increase the pressure gradient relative to the conventional hydraulic transport of solids. This study constitutes the first attempt to formulate one-dimensional hydrodynamic models for evaluating the pressure gradients for stationary and moving solid beds overlaid by three-phase slug flow and for fully suspended three-phase slug flow of non-settling suspensions. The models for slug flow over stationary and moving beds are formulated by coupling the solid–liquid two-layer models of Doron et al. [1987. Slurry flow in horizontal pipes—experimental and modeling. International Journal of Multiphase Flow 13, 535–547] with a three-phase slug flow model. The proposed model for fully suspended three-phase slug flow constitutes an extension of the simple model for gas–liquid slug flow in horizontal pipes of Orell [2005. Experimental validation of a simple model for gas–liquid slug flow in horizontal pipes. Chemical Engineering Science 60, 1371–1381]. The proposed models, that are applicable to Newtonian slurries, were tested against the experimental data available in the literature over a wide range of operating conditions. In general, a good agreement was obtained between the predicted and experimental results.