Two dimensional fluidised bed reactor : performance of a novel multi-vortex distributor

Abstract

The influence of the distributor configuration on interphase mass transfer, gas axial dispersion and bubble size was studied in a 2-D fluidised bed reactor for two types of distributor configurations; a novel multi-vortex (MV) distributor with tuyéres directed vertically and horizontally at different heights and a standard perforated plate distributor (baseline). The linear inlet velocity (U0) ranged between 0.1 m/s and 0.35 m/s, with air as fluidising medium at ambient conditions. The ozone decomposition reaction over Fe2O3 impregnated FCC catalyst was used as an indirect measure of the performance of the FBR and it was found that the MV distributor causes a significant improvement (15% average) in the conversion efficiencies at all velocities tested. Bubble size measurements (using two separate techniques) indicated larger bubbles for the MV distributor, while the visual bubbling to turbulent transition boundary (Uc) for the MV distributor was found to be lower than the baseline distributor. The interphase bubble-emulsion mass transfer was quantified using the model derived by Thompson et al. (1999) and was found to be 52% higher for the MV distributor than the baseline distributor. In addition the MV distributor exhibited near plug flow characteristics at velocities exceeding Uc, while this was not the case for the baseline distributor.