Modified correlation for minimum fluidization velocity of low-density particles in inverse liquid–solid fluidized beds

The minimum fluidization velocity (Umf) is a key parameter for the scale-up of inverse liquid–solid fluidized beds. Theoretical predictions using common correlations were compared against experimental minimum fluidization velocity measurements of low density (28–638 kg/m3), 0.80–1.13 mm Styrofoam particles in a fluidized bed with a height of 4.5 m and 0.2 m diameter. The average absolute relative deviation for the predicted minimum fluidization velocity for particles below 300 kg/m3 was above 40% using the studied common correlations. A modified Wen and Yu correlation was thus proposed based on novel and past measurements with low-density and small-diameter particles, expanding the range for predicting Umf. The new correlation predicted Umf with deviations below 15% for ST028, ST122 and ST300. This modified correlation also improved Umf predictions for comparable particles from a previous study, demonstrating its validity for a larger range of low-density particles.