Instabilities in fixed bed reactors with downwards directed flow for the oligomerization of 1-butene

In this work instabilities in fixed bed reactors with downwards directed flows for the oligomerization of 1-butene were investigated. For very long residence times or very low velocities in combination with strong exothermic reactions, the buoyancy force can exceed the inertia force and the downwards directed liquid flow in the fixed bed becomes instable. These flow conditions might result in hotspots, the shift of the conversion towards unwanted by-products or even in a runaway of the reactor. Therefore, the detailed understanding of the transition between stable and instable flow conditions in fixed bed reactors is essential for a safe and reliable operation of the reactor. Various simulation methods and correlations were applied to predict instable conditions that were observed in an experimental setup. 3D CFD simulations could be used to predict instable flow conditions in fixed bed reactors.