Measurement of Minimum Fluidization Velocity

An amount of powder should be charged to the column, sufficient to give a gently-settled bed about 0.6 m deep. 

The result should be compared with one of the empirical correlations available. Geldart65 found that the Baeyens correlation gives consistently the most reliable prediction overall for Group A solids (see section 3.2), but even so, any one value could be 60% of the predicted value. 

A typical equilibrium cracking catalyst (60 microns, pp = 1500 kg/m3) may have a minimum fluidization velocity in the range from 0.1 to 0.2 cm/s. If much higher values are measured, a leak in the air line or below the distributor should be suspected. 

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Figu re 1.22 Richardson-Zaki plot measurement of minimum fluidizing velocity for particulate fluidization. 

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