CFD Predictions of Sufficient Suspension Conditions in Solid-Liquid Agitated Tanks
-
A. Tamburini
and
M. Ciofalo
Abstract
Most research efforts on mechanically agitated solid-liquid contactors have been devoted to the assessment of the minimum impeller speed for complete off-bottom suspension, Njs. Actually, many industrial vessels are operated at impeller speeds slightly lower than Njs (Oldshue, 1983; Rieger et al., 1988). This suggests that the sufficient suspension condition, which is quantitatively specified in this paper by introducing a suitably defined quantity Nss, may represent a valid alternative to that of complete suspension.
In the present work time-dependent RANS simulations were carried out with the aim of predicting the achievement of sufficient suspension conditions. The Eulerian-Eulerian Multi Fluid Model along with the Sliding Grid algorithm were employed. The Unsuspended Solids Criterion (USC) (Tamburini et al., 2011a) was adopted to distinguish the suspended particles from the unsuspended ones.
The experimental suspension curves (mass fraction of suspended particles versus impeller speed, i.e. xsusp vs N) collected by Tamburini et al. (2011a) and the relevant Nss values were predicted by the present CFD simulations and a very good agreement was found, with maximum discrepancies of about 4%.
Moreover, CFD results were used to test the ability of some Njs assessment methods proposed in the literature to predict sufficient suspension conditions.
©2012 by De Gruyter
Articles in the same Issue
- Frontmatter
- On Time-Averaged CFD Modeling of Circulating Fluidized Beds
- Eulerian-Eulerian Simulations of Segregating Binary Gas-Solid Fluidized Beds
- A Study on Application of Smoothed Particle Hydrodynamics to Multi-Phase Flows
- Three-Phase CFD-Model for Trickle Bed Reactors
- Non-Modal Instability of Core-Annular Flow
- On the Mutual Effect of the Turbulent Dispersion Model and Thermophoresis on Nanoparticle Deposition
- CFD Predictions of Sufficient Suspension Conditions in Solid-Liquid Agitated Tanks
Articles in the same Issue
- Frontmatter
- On Time-Averaged CFD Modeling of Circulating Fluidized Beds
- Eulerian-Eulerian Simulations of Segregating Binary Gas-Solid Fluidized Beds
- A Study on Application of Smoothed Particle Hydrodynamics to Multi-Phase Flows
- Three-Phase CFD-Model for Trickle Bed Reactors
- Non-Modal Instability of Core-Annular Flow
- On the Mutual Effect of the Turbulent Dispersion Model and Thermophoresis on Nanoparticle Deposition
- CFD Predictions of Sufficient Suspension Conditions in Solid-Liquid Agitated Tanks
