Effect of Baffle on the distribution of Liquid sprayed in a fluidized bed
In the oil refining industry where Fluid Cokers have a major role to play, efficient and uniform liquid feed distribution enhances the coker liquid yield and also its operability span by reducing agglomeration. A promising method would be to utilize baffles connected downwardly and radially inwards from the reactor wall to improve liquid distribution and avoid fouling.
This research aims to study the impact of a baffle and of the large bubbles formed at its tip, on the interaction of injected liquid and solid particles in a gas-solid fluidized bed. The proposed research includes three sections:
1. Effect of baffle on distribution of liquid into a fluidized bed at lab-scale:
A Plexiglas unit has been employed to show how the baffle promotes agglomerate break-up using a conductance technique. It was observed that positioning the nozzle tip above the tip of the baffle yields good results while positioning the nozzle tip at the bed wall leads to the formation of an undesirable wet sand deposit on the baffle surface. The next step would be to determine the best position of nozzle, for which agglomerate break-up would be maximized while avoiding deposits. In addition to “conductance”, a new method called “Arabic Gum” will be employed to verify the results obtained from the conductance and provide more detailed information on the beneficial effect of the baffle. Experiments will also be conducted in the turbulent fluidization regime to further verify the effect of baffle on agglomerate break-up. In addition a sparger shall be located at the same position as the baffle tip, without the baffle, to further study the effect of air bubbles released from the sparger on the jet cavity and its subsequent impact on agglomerate break-up. As a final research, the size of the baffle shall be reduced by 50% and assembled at the same angle as the previous baffle to compare its effect with the previous baffle.
2. Effect of baffle with flux-tube in small unit
A flux-tube also called a flow down-comer is a vertical tube located in the center of the baffle providing a flow passage through the baffle for descending solids. This may well avoid solid deposit formation on the baffle corners, even when the nozzle is positioned near the bed wall.Its impact will be investigated and also the optimum position of the nozzle for agglomerate break-up shall be determined for ta baffle equipped with a flux-tube.
Based on the best results from the first paper the most effective methods used in the previous study, will be employed with the aim of evaluating the effect of baffles with flux-tubes on enhancing the amount of agglomerate break-up in a small fluidized bed.
3. Effect of Baffle with or w/o flux-tubes with a commercial-scale spray nozzle
The results achieved from the lab-scale units will be scaled up to perform replicates of experiments in an industrial scale unit.This unit, which has already been used for other studies, will be adapted to perform experiments with baffles.
Sponsors: NSERC – Syncrude – ExxonMobil
Keywords: Fluid Coker, Gas-solid fluidized bed, Bubble formation, Baffle, Injection Nozzle, Agglomeration