Novel method of measuring solids settling velocity in concentrated slurry under sheared conditions using electrical resistance tomography (ERT)

Studying solids settling under sheared conditions is important for designing and operating slurry transportation pipelines. Electrical resistance tomography (ERT) is used for the first time to determine solids settling velocity under sheared conditions in a rheometer. The settling velocity of glass particles descending in 90 vol% glycerol solution located in the annular space between the ERT rheometer cup and bob was evaluated from conductivity data tracking particles' downward movement. The shear rate was varied from 5 to 125 s−1 by changing the bob rotational speed. Solids concentration ranged from 5 to 25 vol%. Settling velocity decreased with increasing solids concentration, slurry viscosity and shear rate. An empirical settling velocity correlation was developed using a modified Richardson-Zaki model incorporating the effects of solids concentration, slurry viscosity and shear rate. This correlation could be adopted as the basis for determining solids settling velocity for slurry transport in laminar flow in a pipeline.