| The particle size distribution (PSD) was found to play a larger role at higher gas velocities than at lower velocities. At low gas velocities ;For reactors of wide PSD, the performance can be improved significantly by operating in the turbulent or fast fluidization regime, while for particles of narrow size distribution, the benefit of operating at high gas velocity is slight at best.;The PSD influence should be considered in modelling fluidized bed reactors. The "Two-Phase Bubbling Bed Model" has been modified to account for PSD effects. For the reactor of wide particle size distribution operated at high gas velocities, a single-phase axial dispersion model with closed inlet and open outlet boundary conditions appears to be suitable to predict the performance.;It was also found that a high pressure drop across the gas distributor was not sufficient to maintain good performance of the distributor. The reactor efficiency in the entry region was higher for a distributor with a greater number of orifices, even though it had a lower pressure drop, than for a distributor plate with fewer larger holes. (Abstract shortened by UMI.).;When the superficial gas velocity exceeded 0.1 m/s, the bed with the wide size distribution usually gave the highest particle concentration inside the voids, the smallest bubble size and the greatest dense phase expansion at the same operating conditions. There is evidence that there is a greater proportion of "fines" present in the voids than in the overall particle size distribution. |
