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.