(425c) Entrainment Review – Review of Existing Correlations | AIChE

(425c) Entrainment Review – Review of Existing Correlations

Authors 

Hrenya, C. M. - Presenter, University of Colorado at Boulder
Chew, J. W., Nanyang Technological University
Cocco, R., Particulate Solid Research, Inc. (PSRI)



Despite the abundance of entrainment correlations made available in the past few decades1-6, the discrepancy between empirical prediction and experimental data is up to a hundredfold in some cases6. Hence, a comprehensive review of the available correlations is warranted, with the goal of extracting the underlying physics giving rise to the disparities, and thereby providing insights towards enhanced understanding of elutriation. Using lognormal Geldart Group A particle size distribution (PSD) as a base case, comparisons of the correlations reveal a difference of up to 21 orders of magnitude difference among the total entrainment flux predicted for a wide PSD. Further probing indicates qualitative discordance on the shapes of the elutriated PSDs, the most notable of which is the non-physical anomaly whereby larger particles are predominantly elutriated. Furthermore, whether a particular correlation was developed for a specific Geldart Group or for monodisperse and/or polydisperse systems seems inconsequential, since correlations largely overlap in the same range. These observations underscore the need for more physically-based models to enable a more accurate prediction of the elutriation phenomenon.

References

1.         Leva M, Wen CY. Elutriation. In: Davidson JF, Harrison D, eds. Fluidization. New York, N.Y.: Academic Press Inc.; 1971:627-650.

2.         Geldart D. Elutriation. In: Davidson JF, Clift R, Harrison D, eds. Fluidization. London: Academic Press; 1985:383-411.

3.         Kunii D, Levenspiel O. Fluidization Engineering. 2nd ed. Newton, MA: Butterworth-Heinemann; 1991.

4.         Fan LS, Zhu C. Principles of Gas-Solid Flows. New York, NY: Cambridge University Press; 1998.

5.         Rhodes MJ. Introduction to Particle Technology. 1st ed. West Sussex, England: John Wiley & Sons Ltd.; 1998.

6.         Tasirin SM, Geldart D. Entrainment of FCC from fluidized beds - a new correlation for the elutriation rate constants K-i infinity*. Powder Technology. Mar 1998;95(3):240-247.