Modelling of a rotary kiln for the pyrolysis of aluminium waste

This paper deals with the mathematical modelling of a rotary kiln, which is used for the recycling of aluminium waste. This model is mainly based on the coupling between "a bed model" describing the processes occurring within the bed of aluminium waste flowing inside the kiln, "a kiln model" describing heat transfer within the kiln itself, "a gas model" describing processes occurring within the gaseous phase held inside the furnace. The "bed model" is mainly based on the plug flow of particles of aluminium inside the kiln. Mass balances as well as energy balances allow for the prediction of the fraction of the organic material within the particles of aluminium as well their temperature. Relevant equations for the "kiln model" include heat conduction and heat exchange with solid and gaseous materials. The equations for the "gas model" are mainly based on fluid mechanics equations coupled with turbulence, radiation, and combustion. The software Fluent (TM) Will be used in order to solve this last model. In this paper, some insight will be given on the description of the "bed model" and "the kiln model" and on the procedure used for the coupling of these models. Exchange variables as well as solving procedure will also be included. Numerical results will be compared to experimental ones, obtained from the pilot scale rotary kiln at Pechiney's research centre. (c) 2005 Elsevier Ltd. All rights reserved.