(592f) Effect of Particle Mixing On Stripping Efficiency of FCC Strippers

Effective stripping of spent catalyst in Fluid Catalytic Cracking (FCC) strippers has always been recognized as critical to maximizing FCC unit profitability. The mixing of catalyst particles has great effects on the stripping efficiency. The CFD technique was applied to simulate the flow behavior in the FCC strippers with and without internals by FLUENT software. The residence time distribution (RTD) of the catalyst particles in FCC strippers was obtained by coupling the tracer technology. The dead volume model was applied to analyze the RTD curves of catalyst particles. The fractions of dead, plug and well-mixed volume in different strippers were compared. In the V-baffled stripper, the fraction of dead volume is about 10%, and the fraction of plug volume is above 40%. In the empty cylinder stripper, the fraction of dead volume accounts for 15-35%, and the fraction of plug volume 15-25%. The comparison of simulated results demonstrates that the stripping space in the V-baffled stripper is better utilized and the back-mixing of catalyst particle is weaker than that in the empty cylinder stripper, resulting in that the V-baffled stripper has a higher stripping efficiency.