Models Based on the Core-Annular Flow Structure

2 Models Based on the Core-Annular Flow Structure 

Considering an element of dz in the riser, the mass balance of the solids in the core region gives 

On the other hand, in terms of the mass balance across a cross section of the riser, the upward solids flow rate We can also be evaluated from 

Equation (10.30) implies that the particle downward flow rate along the wall decays exponentially with the bed height. The deposition coefficient, kd, can be related to the amplitude of the gas velocity fluctuations as [Pemberton and Davidson, 1986 Bolton and Davidson, 1988] (Problem 10.8) 

Once We and Ww are known, the cross-sectional averaged solids holdup, ap, can be calculated by using the following equation 

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