Comparison of Bottom Blowing Element Based on the Characteristics of Gas Stream and Stirring Ability in 120t Converter

Abstract

The bottom blowing element is critical for ensuring the effectiveness of top and bottom blowing in converter steelmaking process. Investigating the influence of different bottom blowing elements on the stirring properties of molten bath contributes to the optimization of the bottom blowing system. The effects of structural variations in dispersive, circular seam and straight cylinder types of bottom blowing elements on molten bath fluid dynamics, turbulent kinetic energy and multiphase flow properties of gas-slag-metal were investigated through numerical simulations. In addition, physical simulations were used to measure the mixing time of molten bath, observe changes in the flow field, and validate and analyze the results of the numerical simulations. The results show that the dispersive type element has a wider dispersion range of the flow jets, while the straight cylinder type has the smallest dispersion range. When the bottom blowing intensity is below 0.05 Nm³/t·min, the dispersive type has the longest mixing time, while the circular seam type has the shortest mixing time. Conversely, at more than 0.08 Nm³/t·min, the dispersive type shows the shortest mixing time and the straight cylinder type shows the longest. The dispersive type significantly influences the bottom flow field and disperses tracers from the interior of molten bath. The circular seam type mainly affects the middle flow field and directs tracers along the central area. The straight cylinder type, on the other hand, has a significant influence on the surface flow field and directs tracers along the pool surface.