Chaotic Analogies in the Operation of Churn–Turbulent Bubble Columns and Bubbling Fluidized Beds

The documented hydrodynamic analogies in the behavior of churn–turbulent bubble columns (BC) and bubbling fluidized beds are further supported by the existence of so-called chaotic analogies. It has been found that the Kolmogorov entropy (KE) values monotonously decreased in both reactors, corresponding to the growth of large bubbles. The KE values have been extracted from the absolute pressure fluctuations measured in three different BCs (0.19, 0.38 and 0.8 m i.d.) as well as gauge pressure fluctuations measured in a BC (0.44 m i.d.). In addition, the same declining KE trend has been derived from gamma-ray densitometry (GD) scans performed in a churn–turbulent BC (0.1 m i.d.). An air–water system was always used. Decreasing KE values derived from computed tomography scans in an air–therminol BC (0.162 m i.d.) are also presented. Gauge pressure fluctuations have also been performed in a bubbling fluidized bed (0.14 m i.d.) operated with an air–glass beads system. The same declining KE trend was obtained. Such a trend is also extracted from GD scans performed in a bubbling fluidized bed (0.44 m i.d.) operated with an air–polyethylene system and gas–solids riser (0.152 m i.d.) operated with an air–glass beads system.