Transverse Bed Motion

Chapter 2 Basic Description of Rotary Kiln Operation 

Seaman (1951) developed an approximation for the theoretical residence time of a shallow bed (lightly loaded kiln) and a theoretical relationship for the kiln volumetric flow rate for deep beds (heavily loaded kilns). Nonetheless, no clear definition has ever been given for the range of operation encompassed by the two cases of kiln loadings. Seaman s approximations led to the conclusion that kilns should be considered heavily loaded when the fractional cross sectional fill of solids exceeds approximately 5 percent. 

The active layer depth and bed flow properties depend on the coefficient of restitution of the material. The flow properties of interest include granular temperature, which is a measure of kinetic energy in random motion of particles, and dilation. Granular temperature was found to be high at regions of low concentration with high mean velocity. These experiments also characterize the shape of the active layer to 

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There are two types of solids motion in a horizontal rotary drum longitudinal (axial) and transverse (radial). For a horizontal drum without lifters, solids transport in the axial direction occurs as a result of the difference in the bed height at the inlet and outlet ends of the drum. Afacan and Masliyah discussed various models to predict dry solids transport in rotary drums as a result of the bed height axial gradient [16]. 

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