Flow of a moderately cohesive FCC catalyst in two pilot-scale rotary calciners: Residence time distribution and bed depth measurements with and without dams

Powder flow and heat transfer in rotary calciners are difficult to predict, which can result in reduced product quality. This work attempts to improve our understanding of powder flow in a rotary calciner. We compare experimental results to existing models. In this study, a moderately cohesive fluid catalytic cracking (FCC) powder was passed through two pilot plants rotary calciners with and without dams. Residence time distributions were measured, and the resulting mean residence times and axial dispersion coefficients were compared to predictive models. It observed that increasing the calciner incline and speed of rotation resulted in decreased mean residence time (MRT) and feed rate only had a small effect on MRT and axial dispersion. Increasing the height of dams increases the mean residence time and lowers the dispersion coefficient. Bed depth profiles at various operating conditions and geometries, with and without dams, were also determined and compared to available models.