As stated in the Kunii and Levenspiel book, the bubble rise velocity in a dense bed can be calculated as
Wall effects can slow the rise of bubbles when \(d_b/d_t > 0.125\); as such, the rise velocity is calculated as
For conditions where \(d_b/d_t > 0.6\), the fluidized bed is considered to be slugging.
Rise velocity of single bubbles in a fluidized bed from Equations 5.3 and 5.4 in Kunii and Levenspiel book 1.
db (float) – Diameter of sphere having same volume as spherical cap bubble, referred to as the effective bubble diameter [m]
dt (float) – Bed or tube diameter [m]
ubr (float) – Rise velocity of single bubbles in fluidized bed [m/s]
>>> ubr(0.05, 0.6) 0.4979
Daizo Kunii and Octave Levenspiel. Fluidization Engineering. Butterworth-Heinemann, 2nd edition, 1991.