CFD Simulation of Two-Phase Flow in a Hybrid Pulsed Sieve-Plate Solvent Extraction Column: Prediction of Holdup and Axial-dispersion Coefficients

ABSTRACT

Two-phase computational fluid dynamics (CFD) models for a hybrid pulsed sieve-plate solvent extraction column, as well as a standard pulsed sieve-plate column, have been developed with commercial software ANSYS FLUENT. Hydrodynamic performance including two-phase distribution and velocity fields are generated with the models and comparisons are made between two columns. Important parameters including holdup and axial-dispersion coefficients are studied systematically, and CFD successfully predicts the higher holdup and lower axial-dispersion coefficients for the hybrid pulsed sieve-plate column as measured in the experiments. CFD also gives reasonable predictions for the effect of pulsation intensity, dispersed-phase velocity, and continuous-phase velocity on holdup, except for the effect of pulsation intensity in low pulsation region, and the cause has been discussed from the perspective of droplet breakage and coalescence. Comparison with literature data shows that CFD underestimates the holdup of hybrid pulsed sieve-plate column and standard pulsed sieve-plate column by 23.3% and 31.4%, respectively, and the cause has been discussed from the perspective of drag law. CFD gives good prediction of axial-dispersion coefficients for the hybrid pulsed sieve-plate column and the standard pulsed sieve-plate column with ARD of 12.0% and 14.3%, respectively. This study shows CFD to be a useful tool to predict performance for the novel hybrid pulsed sieve-plate column as well as the standard pulsed sieve-plate column.

Abbreviations: CFD: computational fluid dynamics; RDC: rotating-disc contactor; ARD: average relative deviation

KEYWORDS:

• CFD
• hybrid pulsed sieve-plate column
• hydrodynamics
• axial dispersion
• solvent extraction

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Acknowledgments

The authors would like to acknowledge the funding provided by the Australian Research Council through Linkage grant LP130100305, and would also like to thank the Particulate Fluids Processing Centre for the resources provided for this project.