(133b) Study of FCC Riser Hydrodynamics Using CFD Tools
World Congress on Particle Technology
Thursday, April 26, 2018 - 1:48pm to 2:06pm
Results of the cold flow studies were used to select and validate the best CFD modeling approach. Predictions of several models developed within the Eulerian-Eulerian and Eulerian-Lagrangian frameworks were compared with the experimental solids flux profiles in the cold riser operating at commercially-relevant velocities. Both model classes showed good agreement with experiment in the ânormalâ riser operation. The Eulerian-Lagrangian approach showed better predictions of experiment when the riser was âpushedâ in terms of velocity and solids flux.
The general trends of riser hydrodynamics, per CFD predictions, were identified as follows. Lower vapor velocity, larger riser diameter and higher solids flux through the riser all contribute to hydrodynamic non-idealities, such as catalyst downflow at the wall and vapor channeling through the core of the riser. In practice, these ânon-idealitiesâ lead to undesirable shifts in conversion (under-conversion in the core) and selectivity (overcracking in the annulus) of the riser.