Figure 7. Comparisons of the predictions of modified Wammes model with experimental data in the three-phase moving bed
To get a better understanding of the transition phenomenon, the dynamic liquid holdup at each point of the trickle-to-pulse transition(hD, tr ) for various solid flow rates in the three-phase moving bed was acquired, as shown in Figure 8. It can be seen from Figure 8 that at a constant gas mass flow rate the dynamic liquid holdup required for the transition from trickle flow to pulse flow increases with the increasing solid flow rate. An explanation for this effect is given as follows: (1) an increase in the solid flow rate results in a higher bed porosity and larger interstices between the particles, (2) the larger the solid flow rate, the more liquid pockets or plugs will be destroyed by the movement of particles. Moreover, at relatively higher gas mass flow rate a lower liquid holdup is necessary to initiate the pulses.