Numerical simulation of a commercial FCC regenerator using Multiphase Particle-in-Cell methodology
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Catalyst regeneration process has recently been the subject of comprehensive research investigations focusing mainly on the chemistry of the regeneration while overlooking the bed hydrodynamics and its effects on the regeneration performance. For this purpose, an industrial Fluid Catalytic Cracking (FCC) regenerator is simulated using a Multi-Phase Particle-In-Cell (MP-PIC) approach. The simulation is performed using a three-dimensional regenerator design with complex internals in order to study bed hydrodynamics, thermal effects, and chemical kinetics. The numerical model is then used to study typical industrial issues linked to the operation of industrial regenerators such as erosion areas, standpipe drainage, and CO emission levels. It is noticed that total outlet gas flow exceeds total inlet flow due to the formation of coke combustion products, an undersized standpipe, and inefficient placement of the air distributor rings. Highest erosion occurs in the feed line and plate. A low-temperature column exists in the center of the unit, and the highest temperatures are outside of the diplegs in the periphery of the freeboard. Elevated CO levels are present in the outlet gas because of poorly designed air distributor rings and lower than optimal temperatures in the unit. These simulation results show the numerous modeling capabilities of the MP-PIC approach to identify possible performance and reliability issues of an industrial process. Some redesign proposals have been made to enhance the FCC regenerator operations.