Numerical Study of Fluid Flow and Mixing in the Argon Oxygen Decarburization (AOD) Process

Abstract

A three-dimensional (3D) model has been developed based on the Eulerian multiphase flow approach to investigate the fluid flow behavior and mixing efficiency in the multi-tuyere AOD process. The interphase forces, including drag force, lift force, virtual force, turbulent dispersion force, and wall lubrication force, were incorporated into this model. The model was used to simulate six-tuyere and seven-tuyere AOD processes. The phenomena of multi-jet penetration, bubble plume merging, 3D turbulent flow and mixing characteristics were considered. The results indicate that the bubble plume merging occurs in the upper part of the liquid bath, forming a typical plume cluster. The predicted penetration length for a single tuyere jet agrees well with the previous work. For the multi-jet system, the side jets penetrate deeper than the inside ones. The six-tuyere AOD has a good flow condition in the center of the liquid bath, while the seven-tuyere AOD has a better flow pattern in the sidewall region and the lower bath. Overall, the seven-tuyere AOD performs better in mixing efficiency than the six-tuyere AOD under the same gas flow rate. These findings increase the understanding of the AOD process, allowing further optimization of process parameters. This model can be further extended to incorporate the thermochemical reactions into the modeling of the AOD reactor.

The Importance of Mixing Time in Intensely Stirred Metallurgical Reactors: Applied on Decarburization Reactions

“…The findings revealed that lower gas flow rates induced a clockwise circulation of the steel bath, with the vortex located in the upper region of the converter. Remarkably, this flow pattern aligned with the observations reported by other side-blowing models [2][3][4][5]8,9]. However, higher flow rates exhibited a more localized counterclockwise circulation behind and below the gas plume.…”

“…These results suggest that the location of the injection point is important when determining the mixing time, as Points 1, 4, 5, 8, and 9 clearly show a faster mixing of the tracer. These injection points are located in the trajectory of the commonly reported [2][3][4][5][6]8,9] large circulation which appears in side-blowing models. In such side-blowing processes, the convective contribution to the mixing is very high, as seen in Figure 8, where a large portion of the bath is affected by strong currents.…”

“…Interestingly, these findings contradict the observations in Refs. [3,9], where the horizontal gas jet penetration did not exceed past the vessel's midpoint. In general, the above-mentioned studies collectively contribute to our understanding of mixing and flow dynamics in gas-stirring converters such as the AOD converter, highlighting the importance of various parameters such as fill level, injection methods, nozzle configuration, and gas flow rates.…”

“…Thus, the main numerical modeling challenges are fluid transport and high temperature chemical reactions. CFD is a popular choice for modeling fluid mass transport [1][2][3][4][5][6][7][8][9], see Table 1. Zhu et al [2] presented an early side-blowing model by implementing a plume model to predict mixing and turbulence behavior in 3D.…”

“…In addition, they found an increase in mixing time when the tracer was injected at lower depths compared to near the bath surface. However, a separate numerical model study [9] that investigated an AOD converter of the same size reported a mixing time range of 100-116 s with six nozzles and 60-120 s with seven nozzles. It is important to note that these results were not validated against any industry or water model data.…”