AXIAL AND LATERAL DISPERSION OF FINE PARTICLES IN A BINARY-SOLID RISER

Axial and lateral mixing of fine particles in a binary-solid riser hav e been investigated using a phosphor tracer method. The measured bimod al residence time distribution (RTD) demonstrated two types of axial d ispersions of the fines: the dispersion of discrete particles and that of clusters. A proposed one-dimensional, bimodal dispersion model des cribes the bimodal RTDs very well. The axial Peclet number of the fine s is not sensitive to the fraction of coarse particles, gas velocity a nd solids circulation rate. Lateral solids dispersion was determined b y measuring the solids RTD at different radii using a point source tra cer injection. A two-dimensional dispersion model describes the measur ed RTDs satisfactorily. Lateral solids mixing decreased as coarse part icles were added into the riser. Correlations of the axial and lateral Peclet numbers obtained fit the experimental data well.