LAUSR

Abstract Fixed-bed reactors are widely used for large-scale, heterogeneously-catalyzed gas-phase reactions, such as steam reforming, selective hydrogenations and partial oxidations. These reactions have strong heat effects; exothermic reactions can exhibit “hot-spots”, while endothermic reactions require a large supply of heat. Steady-state reactor analysis does not give the whole picture; when dynamics are considered then hot-spots, extinction waves and “wrong-way” behavior (increased downstream temperature following inlet feed temperature decrease) can result. We investigate here the interactions between the local pellet-scale dynamic responses, and the bed-scale global fields, using computational fluid dynamics (CFD). This method allows detailed simulation of the fluid around the catalyst, coupled to transport and reaction inside it. To date, reactor dynamics have been based on simplified reactor models. We have developed a methodology to use 3D detailed models to investigate local dynamic hot-spot formation and wrong-way responses to inputs and their connections to bed-scale flow and transport.