Prediction of the Minimum Fluidization Velocity for Fine Particles of Various Degrees of Cohesiveness

Based on the well-known Ergun equation and the force balance of a particle bed under fluidization bringing into account the interparticle forces, a new correlation for prediction of the minimum fluidization velocity (umf ) for fine particles of various degrees of cohesiveness has been derived. For the first time, a general correlation of the minimum fluidization voidage (ϵmf ) versus particle size is obtained from various sets of experimental data. The newly derived umf correlation combined with the one for ϵmf proves to be superior to the traditional ones proposed by Leva (1959 Leva , M. ( 1959 ). Fluidization, 69, McGraw-Hill, New York . [Google Scholar]) and Wen and Yu (1966 Wen , C. Y. and Yu , Y. H. ( 1966 ). A generalized method for predicting the minimum fluidization velocity , AIChE J. , 12 , 610 – 612 .[Crossref], [Web of Science ®] , [Google Scholar]), especially for the cases where very fine or very large particles are employed in fluidization. The correlations of Leva (1959 Leva , M. ( 1959 ). Fluidization, 69, McGraw-Hill, New York . [Google Scholar]) and Wen and Yu (1966 Wen , C. Y. and Yu , Y. H. ( 1966 ). A generalized method for predicting the minimum fluidization velocity , AIChE J. , 12 , 610 – 612 .[Crossref], [Web of Science ®] , [Google Scholar]), both disregarding the cohesive-force effect and the effect of particle size on ϵmf , result in noticeable errors in umf prediction for very fine (Geldart groups C and C/A) and very large (Geldart group D) particles, although they work satisfactorily for small-to-medium size particles (Geldart groups B and A). In contrast, the prediction with the new correlation shows good agreement with the experimental data for various types of particles ranging from Geldart group C to group D.