SCALE-UP OF CHAOTIC FLUIDIZED-BED HYDRODYNAMICS

This paper focuses on scale-up of the dynamic behavior of gas-solids f luidized bubbling reactors. An empirical approach is followed that is based on the observation that the non-linear, hydrodynamic behavior of bubbling fluidized beds is of a chaotic nature. The degree of chaos i s quantified by the Kolmogorov entropy, which is a measure of the rate of loss of information in the system (expressed in bits of informatio n per second). The basic idea of the 'chaos scale-up methodology' prop osed in this paper is that the rate of information loss should be kept similar when scaling up a bubbling bed from the small scale to the la rger scale, in order to ensure dynamic (i.e. chaotic) similarity betwe en the scaled beds. For a set of Geldart-B and -D particle systems, an d for a range of bed diameters (from 0.1 m ID up to 0.8 m ID), an empi rical correlation (Equation 4 in the paper) is derived that relates Ko lmogorov entropy to main bubbling bed design parameters, viz. (i) flui dization conditions (superficial gas velocity, settled bed height), (i i) particle properties (minimum fluidization velocity), and (iii) bed size (diameter). It is illustrated by numerical examples how this corr elation might be used in scaling up the chaotic dynamics of bubbling f luidized reactors. It is further shown that a similar type of correlat ion for Kolmogorov entropy can also be derived theoretically (Equation s 1 and 5 in the paper).