Modeling and Optimization of a Rotary Dryer in a Manufacturing Plant

Abstract

The aim of this thesis is to predict the effects of reducing excess air levels and fuel burned in a rotary dryer being operated in a mining facility in North Carolina. The dryer is now being operated at very high excess combustion air levels, resulting in high stack losses and low thermal efficiency. Reducing the excess air entering the burner and the amount of fuel burned would result in energy and cost savings. However, experimental data to confirm that drying rates can be maintained at the required level by simultaneously increasing the combustion air temperature and reducing the air flow are unavailable. This work attempts to predict the dryer performance at variable air flows from a computer model. The modeling involves an analysis of the heat and mass transfer that occurs in the drying process. The model is validated by comparing predicted performance to actual performance at present operating condition. The excess air levels and the fuel burned are then adjusted to obtain the best efficiency. It is expected that the model prediction will encourage the mining facility to experiment with combustion air flow.