Instrumentation to Monitor Transient Periodic Developing Flow in Non-Newtonian Slurries

Staff at Pacific Northwest National Laboratory have conducted mixing and mobilization experiments with both transparent and opaque non-Newtonian slurries that poses a yield stress and exhibit Bingham plastic and shear thinning behavior. This paper describes measurement techniques applied to identify the interface between flowing (i.e. mobilized) and stationary regions of non-Newtonian slurries that are subjected to transient, periodic, developing flows. Techniques were identified or developed to determine the mobilized and stagnant regions of a vessel, characteristic mixing times, and characteristic velocities of the flow field and mixing process. Instruments and techniques included electromagnetic (EM) and Doppler velocity probes, camera wells, radio frequency tags, dye tracers, and core sampling. Testing focused on mixing vessels using intermitent jet mixers oriented vertically downward. Descriptions of the instruments and instrument performance are presented. These techniques were an effective approach to characterize mixing phenomena, determine mixing energy required to fully mobilize vessel contents and to determine mixing times for process evaluation.