The increasing use of rotary kilns as incinerators or pyrolyser of municipal solid wastes (MSW) has stimulated extensive research efforts to further characterize the bed dynamics of such irregular materials. Experiments concerning the influences of operational variables on the transport process of MSW as well as homogenous sand are conducted in a continuous technical--scale rotary kiln. The results indicate the residence time of particulates is not a certain value

but a function approximately subjected to normal distribution. The irregular MSW has a longer mean residence time (MRT) and a lower material volumetric flow (MVF) than sand

because of its higher θ d.The increment of both rotating rate and kiln slope monotonously reduces MRT and increases MVF.The exit dam has a significant effect on MRT

while the influence of internal structure consisting of various longitudinal ribs and circular ribs is mainly dependent on the height of circular ribs.The roughness of wall also has an effect on MRT through changing the motion regime of bed.