Abstract
A multiphase numerical simulation of the steel-slag flow was established by using the volume of fluid (VOF) model to study the effect of different turbulence inhibitors on the improvement of the steel-slag flow in the tundish. The steel-slag interface fluctuation was studied by vorticity magnitude and transient fluctuation change. A prediction model of residence time distribution (RTD) curve was established based on mathematical simulation and the error of prediction model can be controlled below 6% by comparing with the hydraulic results. The results show that jet flow into the tundish generated very different flow patterns. Case 1 produced a double-roll flow pattern and case 2 produced a four-roll flow pattern in the impact area. The ratio of vorticity magnitude above 1.00 s−1 near the ladle shroud was 2.60% in case 1 and the ratio of vorticity magnitude above 1.00 s−1 near the ladle shroud was 13.15% in case 2, which indicates case 2 increased the possibility of slag entrainment via the upward flow mechanism and shear layer instability. Surface velocity fluctuations in case 2 were much more severe near the ladle shroud. The thickness of the slag layer was 60 mm, the interface fluctuation towards surface in case 2 was close to 20 mm. Meanwhile, case 1 involved very small volume-fraction contours near interface. The turbulence inhibitor with internal ripples (case 1) showed a better optimization effect and the results could provide a theoretical basis for the selection of a suitable turbulence inhibitor for the 66-ton T-type tundish.
Highlights
Tundish, as the last procedure before solidification of molten steel, plays an important role for the removal of macro-inclusions, distribution of molten steel and homogenous of molten steel during continuous casting process
The flow state of molten steel was evaluated by comparing the actual mean residence time (t), the standard deviation (S) of the response time of each strand, the proportion of dead zone volume, etc. under different flow control devices
As the object of this experiment is a large-capacity tundish, the actual average residence time of molten steel is long, and the proportion of dead zone volume is small, which are not used as a criterion in this experiment
Summary
As the last procedure before solidification of molten steel, plays an important role for the removal of macro-inclusions, distribution of molten steel and homogenous of molten steel during continuous casting process. Tundish usually adopts many flow control devices, such as turbulence inhibitor, dam and weir, diversion wall, argon blowing and electromagnetic stirring, etc. The turbulence inhibitor installed in the impact area of tundish can eliminate eddies, reduce scour and alleviate injection flow impact. Turbulence inhibitors can improve the flow state of molten steel, mainly in the following aspects [8,9,10]: turbulence inhibitors can (1) relieve the impact of molten steel on the bottom of tundish and reduce the involvement of gas and slag; (2) extend the average residence time of molten steel in tundish and reduce the dead area of flow; (3) reduce the erosion of molten steel on the bottom and wall of tundish and prolong the service life of tundish; (4) slow down the formation of confluence vortex and optimize the flow of molen steel. [11,12,13], Metals 2020, 10, 1111 and for most of steel plants, the proportion of impact area of tundish maintained generally 20–30%.
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