Experimental investigation of the axial discharging velocity of particles from rotary kilns

The axial discharging velocity of the particles was experimentally investigated at the discharge end of two rotary kilns with 400 and 250 mm internal diameter, respectively. Sand, glass beads and clinker were used as experimental materials. A physical method without using imaging technology was developed to measure the axial discharging velocity based on the discharge behavior. The mass flow and the rotational speed of kiln were changed in a wide range. The axial discharging velocity can be directly determined by the volume flow rate of solid bed divided by the whole cross section area of the bed at the kiln discharge end. The axial discharge velocity can be nominally expressed as the function of the axial transport velocity, if the kiln is fully loaded by the materials and the radial rotational velocity of the cylinder. Clinker among other two materials presents a higher difference of the extreme discharge velocities because of the wider particle size difference.