Cyclone separators calculation, example

A ratio of in the range 5 to 10 will usually be more than sufficient to ensure a well-mixed product. As equation (4.14) shows, short turnover times in deep beds require high gas velocities, and this may result in excessive entrainment of the finer particles. Procedures for calculating entrainment are beyond the scope of this chapter, and the reader should consult Reference 7, in which a worked example is given. Entrainment is roughly proportional to the gas velocity to the fourth power and can be drastically reduced by increasing the cross-sectional area of the column above the bed level. Alternatively, blow-back filters or gas cyclone separators can be fitted to the system, inside or outside the column, and the entrained material returned to the bed. 

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