Figure 8. Dynamic liquid holdup at the transition points for
various solid flow rates
The critical dynamic liquid holdup at which the local liquid blockages
form depends on both the gas mass flow rate and solid flow rate, as can
be concluded from Figure 8. Referring to the method of Wammes, these
hydrodynamic parameters governing the transition between the trickle
flow and the pulse flow are related into the equation (6) which
describes the conditions at the transition.
Three parameters were estimated by the multiple regression techniques
and the final form of the correlation was:
The fitting results are compared with experimental data in Figure 9. The
empirical correlation gives an average relative error of 1.67%. The
correlations show that, for the given material properties and solid flow
rate, the dynamic liquid holdup at the transition between the trickle
flow and the pulse flow decreases as the gas mass flow rate increases.
At a constant gas mass flow rate there is a shift towards higher dynamic
liquid holdup with an increase in the solid flow rate. The present model
is valid for the prediction of the trickle-pulse transition boundary in
the three-phase moving bed.