Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 30178
Identification of the Main Transition Velocities in a Bubble Column Based on a Modified Shannon Entropy

Authors: Stoyan Nedeltchev, Markus Schubert

Abstract:

The gas holdup fluctuations in a bubble column (0.15 m in ID) have been recorded by means of a conductivity wire-mesh sensor in order to extract information about the main transition velocities. These parameters are very important for bubble column design, operation and scale-up. For this purpose, the classical definition of the Shannon entropy was modified and used to identify both the onset (at UG=0.034 m/s) of the transition flow regime and the beginning (at UG=0.089 m/s) of the churn-turbulent flow regime. The results were compared with the Kolmogorov entropy (KE) results. A slight discrepancy was found, namely the transition velocities identified by means of the KE were shifted to somewhat higher (0.045 and 0.101 m/s) superficial gas velocities UG.

Keywords: Bubble column, gas holdup fluctuations, Modified Shannon entropy, Kolmogorov entropy.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1111919

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1144

References:


[1] S. Nedeltchev, “A new method for identification of the main transition velocities in multiphase reactors based on information entropy theory”, Chem. Eng. Sci., vol. 100, pp. 2–14, 2013.
[2] R. Krishna and J. Ellenberger, “Gas holdup in bubble column reactors operating in the churn-turbulent flow regime”, AIChE Journal, vol. 42, pp. 2627–2634, 1996.
[3] P. M. Wilkinson, A. P. Spek and L. L. Van Dierendonck, “Design parameters estimation for scale-up of high-pressure bubble columns”, AIChE Journal, vol. 38, pp. 544–554, 1992.
[4] I. G. Reilly, D. S. Scott, T. J. W. De Bruijn and D. MacIntyre, “The role of gas phase momentum in determining gas holdup and hydrodynamic flow regimes in bubble column operations”, Can. J. Chem. Eng., vol. 72, pp. 3–12, 1994.
[5] S. Nedeltchev, U. Hampel and M. Schubert, “Experimental study on the radial distribution of the main transition velocities in bubble columns”, WIT Transactions on Engineering Sciences, vol. 89, pp. 127–138, 2015.
[6] S. Nedeltchev, “New methods for flow regime identification in bubble columns and fluidized beds”, Chem. Eng. Sci., vol. 137, pp. 436–446, 2015.
[7] S. Nedeltchev, S. Rabha, U. Hampel and M. Schubert, “A new statistical parameter for identification of the main transition velocities in bubble columns”, Chem. Eng. & Techn., vol. 38, pp. 1940–1946, 2015.
[8] W. Zhong, X. Wang, Q. Li, B. Jin, M. Zhang, R. Xiao and Y. Huang, “Analysis on chaotic nature of a pressurized spout-fluid bed by information theory based Shannon entropy”, Can. J. Chem. Eng., vol. 87, pp. 220–227, 2009.
[9] C. M. Van den Bleek and J. C. Schouten, “Deterministic chaos: a new tool in fluidized bed design and operation”, Chem. Eng. J., vol. 53, 75–87, 1993.
[10] J. C. Schouten, F. Takens and C. M. Van den Bleek, “Maximum-likelihood estimation of the entropy of an attractor”, Physical Review E, vol. 49, pp. 126–129, 1994.
[11] H. M. Letzel, J. C. Schouten, R. Krishna and C. M. Van den Bleek, “Characterization of regimes and regime transitions in bubble columns by chaos analysis of pressure signals”, Chem. Eng. Sci., vol. 52, pp. 4447–4459, 1997.
[12] E. Olmos, C. Gentric, S. Poncin and N. Midoux, “Description of flow regime transitions in bubble columns via laser Doppler anemometry signals processing”, Chem. Eng. Sci., vol. 58, pp. 1731–1742, 2003.
[13] E. Olmos, C. Gentric and N. Midoux, “Numerical description of flow regime transitions in bubble column reactors by a multiple gas phase model”, Chem. Eng. Sci., vol. 58, pp. 2113–2121, 2003.