Computational Fluid Dynamics Simulation of Solid Suspension in a Gas−Liquid−Solid Mechanically Agitated Contactor

Abstract

In the present study, computational fluid dynamics (CFD) simulations have been carried out to characterize a solid suspension in a gas−liquid−solid mechanically agitated contactor using the Eulerian multifluid approach with a standard k−ε turbulence model. A steady state method of multiple frame of reference (MFR) has been used to model the impeller and tank region. The CFD model predictions are compared qualitatively with the literature experimental data (Guha et al. Chem. Eng. Sci. 2007, 62, 6143; Spidla et al. Chem. Eng. J. 2005, 113, 73; Aubin et al. Exp. Therm. Fluid Sci. 2004, 28, 447) and quantitatively with our experimental data. Also the effect of different types of impellers (disk turbine and pitched blade turbine with downward pumping), impeller speed, particle size (125−230 μm), and gas flow rate (0−1 vvm) on the critical impeller speed for solid suspension in a gas−liquid−solid mechanically agitated contactor is investigated. The values predicted by CFD simulation agree well with experimental data for various operating conditions.

Study of sparger location on solid suspension in a triple‐impeller stirred vessel

“…Correlation of just suspended speed, N jsg Figure 3 shows the effects of gas sparging from ring sparger on N jsg at different sparger locations. Findings of several researchers [27,[38][39][40][41][42][43] are shown by plotting the empirical equation N jsg À N js = kQ g . In the present work, little difference in N jsg was observed at very low Q g for all three sparger locations tested.…”

“…Reference Coefficient value Number of impellers Present work k = 3.67 3 ΔN js = N jsg À N js = kQ g [38] k = 0.94 1 [39] k = 0.65 1 [40] k = 2.03 1 [27] k = 3.75 3* [41] k = 0.85 1 [42] k = 1.53, CFD 1 [43] where the sparger was placed at a distance of D/3 below the top, middle and bottom impeller, named as L 1 , L 2 and L 3 respectively. Just suspended condition was recorded based on Zwietering's criterion.…”

“…Reference Coefficient value Number of impellers Present work k = 3.67 3 ΔN js = N jsg À N js = kQ g [38] k = 0.94 1 [39] k = 0.65 1 [40] k = 2.03 1 [27] k = 3.75 3* [41] k = 0.85 1 [42] k = 1.53, CFD 1 [43] k = 0.94, μ = 0.001 Pa 1 k = 1.78, μ = 0.01 Pa k = 1.65, μ = 0.1 Pa N jsg N js ≡1 þ mNa js n where Na js ¼ Q g N js D 3 [46] m = 2.6, and n = 0.7 1…”

Models and Applications for Simulating Turbulent Solid–Liquid Suspensions in Stirred Tanks

“…This value is valid for different impeller designs and is applicable over a wide range of particle sizes and solids loadings. Panneerselvam et al (2008Panneerselvam et al ( , 2009) combined the standard deviation method and cloud height criteria (i.e., the cloud height is equal to 0.9 times the liquid height) and found the latter to be determinant. Hosseini et al (2010) calculated the N js via a CFD model by using the tangent intersection method.…”

Numerical analysis of flow in a highly efficient flotation column

“…To date, parameters at mesoscopic level in 3D space remain unclear, and systematical studies on distribution of local gas holdup, turbulence intensity, turbulent kinetic energy, and velocity magnitude are still lacking. With the development of high-performance calculation, computational fluid dynamics (CFD) [11][12][13][14][15][16][17][18][19] 19 is considered an effective tool for studying fluid dynamic parameters at mesoscopic level. Therefore, in this study, CMFA is analyzed with CFD; such analysis could be useful as guide or reference for future numerical studies.…”