Study on mass transfer process and multiphase flow behavior in converter molten bath based on central-hole oxygen lance

The layout of the oxygen lance nozzle holes directly determines the stirring capacity of the jet on the molten bath, thereby influencing the flow characteristics and mass transfer rate of the molten bath. To enhance the converter smelting efficiency, this study investigates the slag-metal mass transfer rate and flow characteristics of the central-hole oxygen lance in the smelting process. Specifically using physical experiments, this study systematically investigates the influence of operating parameters on the morphology of the emulsified layer, the volumetric mass transfer coefficient (KA), and the top-blowing stirring power (ε t ). Meanwhile, the numerical simulation method is employed to analyze the slag-metal mixing index (I m ) and the velocity distribution in the molten bath. The results demonstrate that the KA exhibits a unimodal distribution as the lance height increases, peaking at lance height H = 40d e . Furthermore, the KA of the central-hole oxygen lance is also 11.8% to 18.2% higher than that of the traditional oxygen lance under the same conditions. In addition, increasing gas flow rate significantly raises KA. When the rate increases from 20.1 Nm 3 ·h⁻¹ to 25.2 Nm 3 ·h⁻¹, KA for the traditional and the central-hole oxygen lance increase by 93% and 110%, respectively. Notably, the average velocities of the central-hole oxygen lance at depths of 0.2D, 0.4D, and 0.6D from the molten bath surface are 35.4%, 30.6% and 39.4% higher than those of the traditional oxygen lance, respectively. Overall, this study provides a theoretical basis and data support for optimizing the converter smelting process.