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.
