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.