Numerical Investigations on the Effect of Gas Flow Rate in the Gas Stirred Ladle with Dual Plugs

Abstract

Ladle or secondary steelmaking is an essential metallurgy process in which the steel is adjusted to the chemical compositions required in the final product. The objective of this study was to predict 95% mixing time curve using CFD simulation in order to investigate the possibility to optimize the gas flow rate in gas stirred ladle systems. The commercial software, Flow-3D, was used in this study. This study was divided into three parts. The first two parts of the study was the investigation of the effects of bubble sizes and diffusion coefficient on the mixing time by setting constant-volume gas flow rate. The last part was the study of the effect of gas flow rate on the mixing time. The ladle geometry and operation condition from the example steel plant, Millcon Steel PLC were used in this study. The simulation results indicated that different sizes of bubble have minor effects on the mixing time. The investigation of the effect on the mixing time with and without diffusion coefficient showed that the diffusion coefficient has no significant influence on the mixing time but has significant effects on the characteristics of the plume regions and the velocity flow field. Finally, it was found that gas flow rate has significant effects on turbulent kinetic energy, the mixing time and the steel cleanliness. The results can support the example steel plant to optimize the mixing process concerning productivity and cleanliness quality of the liquid steel.