The transition to turbulent fluidization : Chemical reaction engineering

Pressure fluctuation data have often been utilized to infer hydrodynamic regime transitions in gas fluidized beds, but there have been wide variations in how the measurements have been carried out and interpreted. It is shown that careful pressure fluctuation measurements, in which limitations of previous studies are avoided, do show changes in the hydrodynamic character between different regimes. For the system studied, sand particles of mean diameter 148 μm fluidized by ambient air in a column of diameter 152 mm, the turbulent regime corresponded to a region of intermittency between bursts of slug-like behaviour and bursts of fast-fluidization-like motion, the latter becoming dominant as the gas velocity was increased. Care is required in interpreting pressure fluctuations in terms of hydrodynamic behaviour if regimes are to be correctly inferred