Diagnostic criteria for heat transport limitations in fixed bed reactors

Dimensionless criteria are derived for evaluating the significance of interphase and interparticle temperature gradients in fixed bed catalytic reactors. Comparison of the criteria reveals that the magnitudes of the heat transport resistances are generally in the order: interparticle > interphase > intraparticle. The criteria show the critical importance of decreasing the diameters of the reactor and the catalyst particles to minimize transport limitations. Dilution of the bed with inert solids is shown to be advantageous only at Reynolds numbers sufficiently low that the effective thermal conductivity of the bed is insensitive to the flow rate.