The Choking Velocity in Vertical Transport

We will see in Section 8.1.4 that the pressure drop across a length of transport line has in general six components  

It is not possible to theoretically predict the conditions for choking to occur. However, many correlations for predicting choking velocities are available in the literature. Knowlton (1986) recommends the correlation of Punwani et al. (1976), which takes account of the considerable effect of gas density. This correlation is presented below  

Equation (8.1) represents the solids velocity at choking and includes the assumption that the slip velocity UsUp is equal to Uj (see Section 8.1.4 below for definition of slip velocity). Equations (8.1) and (8.2) must be solved simultaneously by trial and error to give ecu and LZch- 

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