Fluidized regimes fluidizing velocity

FIGURE 11.9 Fluidization regimes in a batch fluidized bed at low multiples of the minimum fluidization velocity. 

As discussed earlier, fluidized bed granulators normally operate in a bubbling bed regime. The operating superficial gas velocity is above the minimum fluidization velocity and below the onset velocity for a turbulent bed. The preferred method for... 

The minimum bubbling velocity is usually greater than the minimum fluidization velocity. Therefore, the fluidized bed dryer should be operated at superficial gas velocity that is greater than the minimum fluidization velocity, wmf, but less than the onset velocity to turbulent regime, uc. 

Figure 5. The dependence of the transition from the slow to fast bubble regime on bubble diameter dg and minimum fluidization velocity umf.

Figure 11.9 Fluidization regimes in batch fluidized bed at low multiples of minimum fluidization velocity (a) packed bed (b) incipient fluidization (c) bubbling fluidization (d) slugging fluidization (c) pneumatic transport.

Results of the METSIM heat and mass balance provided the basis for sizing of the equipment. Based on the particle size distribution of the feed as well as particle and gas properties, a fluidization velocity of 0.7 m/s was selected to ensure complete fluidization in the bubbling regime, while minimizing solids elutriation to the cyclone. 

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