Analysis of actual blast furnace operations and evaluation of static liquid holdup effects by the four fluid model

The purpose of this paper is to extend and validate a previously presented model of the blast furnace shaft. This model uses conservative differential equations to analyse simultaneous four phase motion, heat transfer and chemistry. First, the paper describes some enhancements to the model. After this, the model is validated against several sets of operational and descending probe data from various blast furnaces. The calculated temperature fields show good agreement with two dimensional fields measured by descending probes at both medium and high rates of PC injection. Finally, the third section considers the effect of including static liquid holdup on the model predictions. Three correlations for static liquid holdup were examined. For all correlations, when static liquid holdup was included in the calculations the net liquid flux towards the raceway increased due to the transport of static liquid by the solid. Further, as static holdup reduces the volume available for gas flow, the gas velocity increases causing greater gas-solid heat transfer. This increases the rates of direct reduction and solution loss, resulting in increased predicted production rates and decreased hot metal and top gas temperatures. Finally, for correlations that predict large static holdup in the raceway region, silicon transfer to hot metal is increased due to increased liquid metal residence times.