Experimental study on rheology and wall slip effect of high concentrated coal water slurry

Experimental researches were carried out to investigate slip and flow properties of highly concentrated coal water slurry (CWS) in a pilot-scale transportation system. Three concentration of CWS of 65.3%, 67.1% and 68.2%, and a series of straight pipelines with the inner diameters of 25, 32, 40 and 50 mm were used. A new method of finding slip velocity and true rheological behavior was derived according to the new slip model and flow structure of CWS flowing in a straight pipe. Using the new slip model, slip velocities and true rheological properties of three concentration of CWS flow in the pipes were gained. The results suggest that the slip model used is suitable for delineating slip properties of highly-loaded CWS flowing in the straight pipe; at a high concentration, experimental CWS exhibits true rheological behaviors of notable non-Newtonian behavior and the flow properties are strongly affected by slip at the wall; there are close connections between wall slip and true rheological behavior, and the two dominate the flow behavior of CWS.