Fluidized beds unbounded analysis

All the just-mentioned analyses focus more or less on fluidized beds and under unbounded conditions. The analysis of all these investigators concentrated on whether a periodic disturbance in the axial direction grows with respect to time, leading to instability, or decays with time, indicating a stable system. The treatment is strictly for axial direction and the axial nonuniformities are the source of transition. Analyses such as these have the limitation that the real fluidized bed is not of infinite extent, and that some account must be taken of the boundaries at the upper and lower surface of a bed, the finite depth, and also the walls that bound the beds laterally. Further, the one-dimensional unbounded description does not generally explain all the experimental observations at transition. Shnip et al (1992) have used the theory of hnear stabihty for the analysis of bounded beds. 

Comparison of Experimental Results of Gibilaro etal. (1986) with Unbounded Analysis Solid-Liquid Fluidized Beds... 

Table IX comparies model predictions with experimental values for solid-liquid fluidized beds. As mentioned earlier, in fluidized beds of very flne heavy particles, transition occurs because of radial nonuniformity. Further, almost all reported data on fluidized beds have mentioned that the sparger resistance was very large. Therefore, the comparison is made for the limiting case of the model, i.e., Eq. (183). Also, to bring out the limitation of the unbounded analysis, the same system data are compared. The comparison is favorable using the model of the present work. Table X shows the comparison for gas-solid fluidized beds. Again, fairly good agreement can be seen between the model predictions and the experimental observations.

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