ANALYSIS OF ACTUAL BLAST-FURNACE OPERATIONS AND EVALUATION OF STATIC LIQUID HOLDUP EFFECTS BY THE 4-FLUID MODEL

The purpose of this paper is to extend and validate a previously prese nted model of the blast furnace shaft. This model uses conservative di fferential equations to analyse simultaneous four phase motion, heat t ransfer 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. Th e calculated temperature fields show good agreement with two dimension al fields measured by descending probes at both medium and high rates of PC injection. Finally, the third section considers the effect of in cluding static liquid holdup on the model predictions. Three correlati ons 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 liqu id by the solid. Further, as static holdup reduces the volume availabl e for gas flow, the gas velocity increases causing greater gas-solid h eat transfer. This increases the rates of direct reduction and solutio n loss, resulting in increased predicted production rates and decrease d hot metal and top gas temperatures. Finally, for correlations that p redict large static holdup in the raceway region, silicon transfer to hot metal is increased due to increased liquid metal residence times.