The lime quality and overall thermal efficiency of a kiln is strongly affected by the effectiveness of heat transfer from freeboard gases and the wall as well as the bed motion. A three-dimensional model to predict the temperature and CaCO3-CaO concentration distributions within the solids bed was developed. The model couples the axial flow data from a one dimensional bed model and bed velocity data from a two dimensional model to solve the bed energy and concentration transport equations. Significant transverse variation in the temperature and concentration distribution was observed during calcination, which could affect lime quality. A stand-alone one-dimensional bed model, validated using experimental data collected at Metso Minerals Test Facility, Danville, PA, was also developed which predicts the average bed temperature and concentration along the length of the kiln. The model offers a useful tool to analyze the effect of operating parameters and optimize kiln design.
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