AN RTD STUDY FOR THE FLOW OF LIGNITE PARTICLES THROUGH A PILOT ROTARY DRYER PART II: FLIGHTED DRUM CASE

In Part II of this work a flighted pilot rotating cylindrical drum, intended to be used as either a dryer or calciner ( kiln) has been used to investigate the flow, through it, of pulverized moist lignite. Tracer pulse input - response experiments have been performed. Residence Time Distribution ( RT) data have been deduced for three types of flight geometry, namely: Rectangular ( RA) Equal Angular Distribution ( E.A.D.) and Equal Horizontal Distribution ( E.H.D) For each flight shape, mean residence time t¯ has been correlated with drum operating conditions. The sequence ⩾ t¯ EAD t¯ EAD has been validated. A comparison between the residence time predictions for the flighted and the bare drum has indicated that t for the former may be higher by up to 3.5 times than that for the latter. Exceptionally high solids hold-up values ( Z= 0.13− 0.42) have been observed and compared to theoretical predictions. Particle size segregation during lignite flow through the flighted drum was not confirmed.