AIR-FLOW OPTIMIZATION IN A FIELD-SCALE ROTARY KILN

This paper describes a computational modelling study of a full-scale r otary kiln using the commercial CFD-code PHOENICS. A steady state mode is assumed in which solid waste (a mixture of cellulose and toluene) is volatilised and burned. The focus of the model is on the gas phase fluid dynamics. Buoyancy is accounted for, turbulence is modelled with the k-epsilon model, radiative transfer is in a first step modelled w ith the composite flux model of radiation and combustion is modelled u sing the SCRS-model for diffusive, mixing limited reacting flows. The volatilisation model makes use of a first order Arrhenius-type reactio n rate, that takes the volatilisation properties of both toluene and c ellulose into account. The goal of this study is to screen various air inlet designs for their mixing characteristics and residence time dis tribution. This is translated in the destruction efficiency of selecte d compounds. The actual air inlet configuration in an existing full sc ale incinerator is chosen as a reference for comparison. Alternative d esigns are analysed. The methodology and usefulness of the approach is fully demonstrated and typical design results are reported.