Influence of excess air number and coke fraction on lime quality in mixed feed shaft kilns

摘要

A mathematical model has been developed to simulate the lime burning process in mixed feed shaft kilns. The model ncludes the particle size distribution of coke and limestone and their individual material properties. Because this type of kiln is operated near the stoichiometric case also the so-called Boudouard Reaction is considered. In this study it is shown how the sensitivity of the location of the combustion zone depends on the air volume flow. It is also shown how a small increase of the coke ratio can drastically increase the lime temperature which has a strong influence on the lime reactivity. The location of the combustion zone also influences the residual CO_2-content and the specific energy consumption.