Enhanced flow characteristics of coal-water slurry: rheological and pressure drop analysis of an anionic surfactant mixture in pipeline transport

The effect of a cost-effective blend of anionic surfactants comprising STPP:PAA:SS with proportions of 0.4:0.4:0.2, added at concentrations of 0.25 and 0.5 wt% (relative to dry solids), on the improved transportation of coal-water slurry through pipeline was investigated in two stages. Initially, the rheology properties of the CWS, including apparent viscosity, yield stress, and flow behavior were analyzed at a shear rate range of 8−317s−1 with dry solid contents of 50, 55, and 60 wt%. Subsequently, the impact of this anionic mixture on the pressure drop of the CWS, with a dry solids content of 30 wt% was evaluated across three sections of a laboratory-scale closed-loop pipeline under six flow velocities (0.99, 1.32, 1.64, 1.97, 2.3, and 2.63 m/s). The incorporation of the anionic mixture was found to significantly improve the rheological characteristics of the CWS regardless of the dry solids concentration, resulting in a reduction of the apparent viscosity ranging between 44.42% and 60.82%, and a decrease of the yield stress ranging between 19.24% an 88.41% at an additive concentration of 0.5 wt% of dry solids. Under the same additive concentration, the overall pressure drop of the CWS was reduced by an average of 16.82%, while a more pronounced reduction of the pressure drop by 24.31% was recorded at the U-bend section of the pipeline.