SIMULATION-MODELS ACCOUNTING FOR RADIAL VOIDAGE PROFILES IN FIXED-BED REACTORS

Momentum, heat and mass transfer in fixed-bed reactors were modeled by incorporating the structural nonuniformities of the bed into the respective conservation equations. A pseudohomogeneous and a heterogeneous model with porosity and velocity profiles (2D-HOM-PVP and 2D-HET-PVP, respectively) were thus developed. In the region extending up to a distance of two particle diameters from the wall bounding surface, the flow oscillates in a strongly damped fashion with peak velocities at locations of higher voidage. The effect of the nonuniformity of flow on the heat and mass transport processes is more accurately described when a distinction is made between the fluid and the solid phase in the fixed bed.