Gas phase conversions and product selectivities predicted by the single-bubble-class and modified two-bubble-class models of bubble column reactors are compared for a multistep gas-liquid reaction involving series/parallel steps. A situation is considered where the first reaction step is fast and occurs in the interfacial region while the other reaction steps are slow and occur only in the liquid bulk. Equivalent hydrodynamic and transport parameters provide a common basis for the comparison. The differences in the gas phase conversions predicted by these models are insignificant. However, the two models predict very different values of selectivities for the intermediate products. This analysis enables us to judge the range of applicability of the single-bubble-class model in design and scale-up of bubble column reactors.

Effects of various operational parameters, such as draft tube superficial air velocity and solid inventory and design parameters such as jet diameter and clearance between perforated plate and draft tube bottom on the solid circulation rate of a recirculating fluidized bed are studied. A simple butterfly valve arrangement was used for the direct measurement of the solid circulation rate.

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