2004 Volume 44 Issue 5 Pages 801-808
Injection of hydrogen bearing matters into blast furnace has been attracting technical and scientific interests aimed to improve the furnace performance through enhancing hydrogen reduction. In this study, the operations of humidified blasting, natural gas and waste plastics injections are numerically examined in comparison with all-coke operation by means of multi-fluid blast furnace model. The model evaluations are carried out under constant raceway conditions and hot metal temperature throughout all tested cases. Since the injection of hydrogen bearers changes raceway conditions, the blast conditions that are used for model computation as tuyere inlet boundary condition, including blast rate, oxygen enrichment, temperature and humidity, are suitably adjusted to maintain raceway temperature and bosh gas flow rate. The model simulations reveal that in-furnace temperature level lowers while the enhancement of hydrogen reduction reduces the ratio of direct reduction with hydrogen bearer injection. The productivity improves, and coke rate shows a little increase in humidified blasting operation while it obviously decreases in the injections of natural gas and waste plastics. The other two cases, namely, natural gas and waste plastics injections, show remarkable improvement of furnace efficiency. The decrease in heat demands by direct reduction, solution loss and silicon transfer reactions contributes to the improvement of blast furnace efficiency with respect to hydrogen bearer injection.