Control of mean residence time difference for particles with wide size distribution in fluidized beds

Abstract

For non-catalytic gas-solid reactions, it is desirable to match the mean residence time (MRT) of a particle and its complete conversion time (τ) in fluidized beds. In this study, the MRTs of the particles with wide size distribution (WSD) were characterized and tuned in a continuous fluidized bed by varying the gas velocity and by the introduction of baffle. For the WSD particles with maximum diameter ratio of 4, the MRT ratio of the coarse to the fine particles increases from the 1.1 up to 1.7 with only changing the gas velocity. By introducing baffles into the fluidized bed under a relatively high gas velocity, the MRT difference for the different size particles becomes more prominent. With four layers of baffle, the MRT ratio of the coarse to the fine particles can reach 5.5. This study provides a new way to adjust the MRT difference for particles with WSD.