Search Results (2)

The pulverized lime/limestone injection by top oxygen blowing lance during the basic oxygen furnace (BOF) process has gained much interest in recent years due to its advantages in helping slag formation and consequently in promoting refining reactions such as dephosphorization. In this pneumatic process, understanding the motion behavior and distribution of the powder particles in the furnace is of importance for regulating and designing this refining system reliably and efficiently. In this study, limestone powder top blowing through a novel nozzles-twisted oxygen lance during a BOF process is proposed and the process is simulated by establishing a multi-fluid flow model. The coupled fluid flow of gaseous oxygen and liquid steel is predicted by the volume of fluid (VOF) method, and the motion of the limestone particles is tracked by the discrete phase model (DPM). The results show that the powder injection has little effect on cavity depth of the oxygen-powder mixture jets of the nozzles-twisted lance, but decreases cavity width. During the blowing process, most of the powder particles gather around hot spots while the rest are taken out of the furnace by the reflecting oxygen stream or penetrate into the molten bath. The generated swirling flow of the nozzles-twisted oxygen lance enables a decrease in the amount of the powder particles carried by the reflecting stream and going into the molten bath, through changing the motion paths of the powder particles. As a result, the concentration distribution of the powder particles in the molten bath varies. It could be suggested that for the limestone powder injection the preferred nozzle twist angle of the oxygen lance is 10° due to the favorable conditions for dephosphorization. Full article

Basic oxygen furnace (BOF) steelmaking is widely used in the metallurgy field. The slagging reaction is a necessary process that oxidizes C, Mn, Si, P, S, and other impurities and therefore directly affects the quality of the resultant steel. Relevant research has suggested that intensifying the stirring effect can accelerate the slagging reaction and that the dynamic characteristics of the top blow are the key factor in exploring the related complex physical and chemical phenomena. To address the issue, the standard k-$\omega$ turbulence model and level-set method were adopted in the present work and a fluid dynamics model was developed for a BOF. Accordingly, the slag–metal–gas emulsion interaction and stirring effect were investigated, and the interference mechanism of a multi-nozzle supersonic coherent jet was revealed. Finally, a self-adjustment method based on fuzzy control is proposed for the oxygen lance. The results indicate that the transfer efficiency of jet kinetic energy at the gas–liquid interface is the critical factor for the slagging reaction and that multi-nozzle oxygen lances with a certain twisted angle have important advantages with respect to stirring effects and splashing inhibition. The fuzzy control method predicts that the optimal nozzle twist angle is within the range of 7.2° to 7.8°. The results presented herein can provide theoretical support and beneficial reference information for BOF steelmaking. Full article