On the Use of a Powder Rheometer to Probe Defluidization of Cohesive Particles

Inter-particle cohesion plays an important role in various industrial unit operations. Recently, particle defluidization was identified as a bulk measurement that can be used to extract inter-particle cohesion (Liu et al., 2018). This method requires direct-coupling of experimental, "standard" defluidization curves (pressure-drop vs. gas velocity) with discrete-element-method (DEM) simulations; "standard" refers to defluidization without channeling. Hence, the method is not readily applicable to highly-cohesive (Group C) particles that exhibit channeling. In this work, we obtain standard-defluidization-curves for Group C particles using a rheometer with a rotating impeller. Then, we confirm that the measurements from the rheometer are system-size-independent, thereby ensuring the feasibility of direct-coupling of the experiments with smaller DEM simulations. Furthermore, we show that the torque required to rotate the impeller may provide an alternative to the pressure-drop to characterize particle defluidization. Finally, we show that the extracted characteristic-velocities from these experiments may provide a relative-gauge for particle-level cohesion.