CFD Modeling and Experimental Validation of Top-Submerged-Lance Gas Injection in Liquid Metal

Abstract

In the present work, the dynamics of a downward gas injection into a liquid metal bath is studied using a numerical modeling approach, and validated with experimental data. As in a top-submerged-lance (TSL) smelter, gas is injected through the lance into the melt. By this means, the properties of the liquid are closer to the actual industrial process than the typically used water/glycerol–air/helium systems. The experimental activity was carried out in a quasi-2D vessel $$(144\times 144\times 12\,{\hbox {mm}}^{3})$$ ( 144 × 144 × 12 mm 3 ) filled with GaInSn, a metal alloy with eutectic at room temperature. Ar was used as the inert gas. The structure and behavior of the gas phase were visualized and quantitatively analyzed by X-ray radiography and high-speed imaging. Computational Fluid Dynamics (CFD) was applied to simulate the multiphase flow in the vessel and the Volume Of Fluid (VOF) model chosen to track the interface using a geometric reconstruction of the interface. Three different vertical lance positions were investigated, applying a gas flow rate of $$Q_{\text {gas}}=6850\,{\hbox {cm}}^{3}/{\hbox {min}}.$$ Q gas = 6850 cm 3 / min . The CFD model is able to predict the bubble detachment frequency, the average void fraction distributions, and the bubble size and hydrodynamic behavior, demonstrating its applicability to simulate such complex multiphase systems. The use of numerical models also provides a deep insight into fluid dynamics to study particular phenomena such as bubble break-up and free surface oscillations.

CFD Investigation of Rotational Sloshing Waves in a Top-Submerged-Lance Metal Bath

“…In a recent publication, the authors presented a numerical and experimental study of TSL gas injection in a liquid metal bath. [15] The work offers a detailed insight into the multiphase flow generated by the top injection of Ar gas into a liquid metal bath and proves the reliability of the Volume of Fluid (VOF) modeling approach for complex fluid systems. The ternary alloy GaInSn was used as a fluid model, whose eutectic point at room temperature facilitates the measurement procedure.…”

“…The present work is intended to be an extension of that study, [15] and investigates top gas injection in 3D cylindrical vessels by means of CFD modeling. This allows eventual sloshing phenomena to be tracked and examined.…”

Dynamics of Rising Bubbles in a Quiescent Slag Bath with Varying Thermo-Physical Properties

“…In some cases, for example in the TSL furnace, the interactions are so strong that two or more bubbles may collide, break or coalesce. [35] In the presence of thermal gradients, depending on which kind of bubble interaction takes place, the gas is exposed to different physical properties distributions, which might lead to stronger deviations than those observed with one single rising bubble. Figures 22, 23, and 24 show the status of the bubbles at t = 0.75 s, for all the configurations analyzed.…”

“…This behavior was observed in previous works focused on TSL gas injection. [34,35] Because of the acceleration, the two bubbles collide and coalesce, continuing the ascent as a single bubble with double the volume. Only when constant slag properties are used does the first coalesced bubble break into four main smaller structures, which rise up separately.…”

“…Bubble dynamics have also been investigated in molten metal systems, [26][27][28][29][30][31][32][33][34] which require sophisticated apparatus, such as X-ray radiography and ultrasound velocimetry, to measure the flow and provide data to validate numerical investigations, as in the previous work of the author. [35] In the present study, the authors focus on the motion of bubbles in the fayalitic slag, typical of smelting processes in the non-ferrous metallurgy. In addition to the metals' high density and surface tension, liquid slags are heavily viscous fluids, with values in the range of 0.1 to 1 PaÁs.…”