Local transport and reaction rates in a fixed bed reactor tube: Exothermic partial oxidation of ethylene

Particle-resolved 3-D computational fluid dynamics (PRCFD) simulations of highly exothermic ethylene partial oxidation in a fixed bed were made to evaluate heterogeneous pseudo continuum reaction engineering models. The ethylene oxidation results were compared to a previous study (Dixon, Chem. Eng. Sci., 168,156-177 (2017)) of endothermic steam methane reforming (SMR). The 1-D pseudo continuum reactor model predicted too high a reaction rate compared to the PRCFD simulations. Unlike the endothermic SMR, manipulation of the fluid-particle heat and mass transfer coefficients did not improve agreement. For the 2-D pseudo continuum reactor model, agreement was not helped by the inclusion of radial voidage and velocity profiles, but was improved by the radial heat transfer model, again in contrast to SMR. These results arose from the differences between heating from the strong heat flux applied to the tube wall, and from the weaker heat source supplied by reaction in the main fixed bed. (C) 2020 Elsevier Ltd. All rights reserved.