Navodia, Sahil Suleman. Measurement of the residence time distribution of FCC catalyst in rotary kilns. Retrieved from https://doi.org/doi:10.7282/T3SQ93M6
DescriptionContinuous rotary kilns are among the most widely used solid handling equipment for industrial applications such as drying, incineration, mixing, pre-heating, humidification, calcining, and gas-solid reactions. Longer residence times prove beneficial in ensuring that all particles have been treated sufficiently, but this can lead to large material and energy costs. As a result, efficient calcination will require shorter residence time and lower axial dispersion. The purpose of this research is to contribute towards a better understanding of these mass transfer mechanisms in rotary kilns, using industrially relevant equipment and operating conditions directed towards large-scale catalyst manufacturing. In this work, the residence time distribution and axial dispersion coefficient for a free flowing fluid cracking catalyst (FCC) powder is measured in pilot-scale kilns using a tracer study developed by Danckwerts (1952). The tracer study was used to determine residence time distributions for different sets of operating parameters, which were successfully matched to the Taylor fit of the axial dispersion model and the Sullivan prediction for mean residence time. It was found that the mean residence time and axial dispersion coefficient varied inversely with rotary speed of the kiln. The bed depths corresponding to respective flow regimes in such a calcination system were not previously reported. The predictive models showed accuracy for the system considered, even at fill levels <1% which was not the case in previously reported studies with cohesive powders.