Prediction of conductive heating time scales of particles in a rotary drum


A. Cuitiño, B. J.Glasser, F.J. Muzzio, H. N. Emady, K. V. Anderson, W. G. Borghard




Chemical Engineering Science



Modeling conductive heat transfer from rotary drum walls to a particle bed via discrete element method simulations, three time scales were determined: 1) the characteristic heating time of the bed, τ; 2) the particle thermal time constant, τp; and 3) the contact time between a particle and the wall, τc. Results fall onto a monotonic curve of τ/τc vs. ϕ (τp/τc), with three heating regimes. At low ϕ, conduction dominates, and the system heats quickly as a solid body. At high ϕ, granular convection dominates, and the bed heats slowly at a nearly uniform temperature. At intermediate ϕ, the system heats as a cool core with warmer outer layers. The results of this work have important implications for improving the design and operation of rotary drums (e.g., energy-intensive calcination processes). By calculating τp and τc from material and operating parameters, the characteristic heating time, τ, can be predicted a priori.


Calcination, catalyst manufacture, Conduction, heat transfer, particle technology

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