Tracer dispersion in trickle beds under tilts and roll motions – CFD study and experimental validation.

• Tracer dispersion in trickle beds was studied numerically under marine conditions. • Eulerian two-fluid CFD model was able to describe tracer mixing and RTD. • Column tilts and roll motions were responsible for widening of tracer signals. • Variation of flow structures with roll motion caused different mixing behaviors. A wire-mesh sensor was used to measure the liquid residence time distribution (RTD) and tracer dispersion in trickle beds subjected to stationary tilts and roll motions. The measured tracer characteristics were confronted to three-dimensional transient Euler-Euler CFD simulations to expose the role of inclined and oscillating porous media. The simulation results satisfactorily reproduced the widening tracer signals with increased bed inclination reflecting in asymmetric RTDs prompted by permanent gravity-driven stratified flow zone through the packing. Similarly, tracer dispersion was predicted to increase for rolling beds by increasing tilt angle and motion period. While an increase of tilt angle shortened RTD breakthrough time due to the faster tracer stream evolving in the liquid-rich lower-most zones, tracer elution tended to slow-down with increasing the rolling period. In addition, it was revealed that with altering the column angular position during roll motions the fluid flow structures inevitably varied inside the packing leading to different mixing behaviors and residence time distributions. [ABSTRACT FROM AUTHOR]