Flow in Fluidized Beds

  • Octave Levenspiel


Suppose we progressively increase the velocity of fluid which is flowing upward through a batch of solids. The frictional resistance increases, and eventually a point is reached where the resistance just equals the weight of solids. At this point the solids become suspended—in other words, they
$$ {A}_t{L}_m\left(1-{\varepsilon}_m\right)={A}_t{L}_{mf}\left(1-{\varepsilon}_{mf}\right)={A}_t{L}_f\left(1-{\varepsilon}_f\right) $$
become “fluidized”—and the superficial velocity of fluid needed to just fluidize the solids is called the minimum fluidizing velocity u mf . As the flow rate of fluid is increased beyond this point, a liquid fluidized bed keeps expanding, while a gas bed expands only slightly. This progression is shown in Fig. 7.1. The fluidized state has many desirable liquid-like properties. For example, we can easily move solids about just by pumping or by gravity flow.


Outlet Pressure Superficial Velocity Cold Model Minimum Fluidizing Velocity Distributor Plate 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


  1. D.C. Chitester et al., Characteristics of fluidization at high pressure. Chem. Eng. Sci. 39(253) (1984)Google Scholar
  2. D. Kunii, O. Levenspiel, Fluidization Engineering, 2nd edn, Chap. 3, (Butterworth, Boston, 1991)Google Scholar
  3. C.Y. Wen, Y.H. Yu, A generalized method for predicting the minimum fluidization velocity. AIChE J. 12(610) (1966)Google Scholar

Copyright information

© Springer Science+Business Media New York 2014

Authors and Affiliations

  • Octave Levenspiel
    • 1
  1. 1.Department of Chemical EngineeringOregon State UniversityCorvallisUSA

Personalised recommendations