کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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159228 | 457031 | 2005 | 10 صفحه PDF | دانلود رایگان |
A model has been developed for the prediction of the axial dispersion coefficient in the riser of an external-loop airlift reactor. It takes into account both radial velocity and gas hold-up profiles as a function of flow regime, but also the two-phase turbulence. It is based on the mixing length model developed by [Vial et al., 2002. Chem. Eng. Sci. 57, 4745–4762] for the flow field prediction and uses a turbulent diffusion coefficient to estimate the influence of two-phase turbulence on mixing. The relations established using experimental data from an airlift reactor have been validated experimentally using a second reactor. A comparison with theoretical dispersion coefficients deduced from CFD calculations and correlations from the literature is also provided. The results show that in all the hydrodynamic regimes, dispersion stems from bubble-induced turbulence, despite the presence of a nearly parabolic liquid velocity profile in the homogeneous regime and marked liquid hold-up profiles in churn-turbulent flow.
Journal: Chemical Engineering Science - Volume 60, Issue 22, November 2005, Pages 5945–5954