Abstract
The performance of a multistage fluidized-bed reactor was investigated. The system was studied using the ozone decomposition reaction over alumina catalyst. A 7.8 cm ID PVC fluidized-bed reactor was designed and constructed. Bubble frequency measurements were made using a differential pressure probe in conventional (unbaffled) and baffled fluidized beds with or without a downcomer with no reaction. The longitudinal concentration profile was measured in each of the systems. The results showed the occurrence of a unique minimum, which provided evidence of gas backmixing in the bed. The overall conversion in the baffled fluidized bed was higher than that in the conventional bed. Within the operating conditions used in this study, it was found that the number and location of baffles significantly affect the overall conversion. In contrast, the use of a 1.1 cm ID downcomer did not affect the conversion level in the baffled fluidized beds. A modified countercurrent backmixing model was used to predict the overall conversion and concentration profiles in the fluidized beds. The model included three-regimes: bubble, transition, and slugging; and three-phases: bubble or slug, wake, and emulsion. The model accounted for the effect of reversed flow of emulsion gas. The bubble diameter in the fluidized bed was calculated using the experimentally measured bubble frequency. The model showed the potential of predicting the experimentally observed overall conversion and concentration profile of the ozone gas in both the conventional and baffled fluidized bed with or without downcomer.
Published Version
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