Steel flow and inclusion separation in continuous casting tundishes

Tacke, Karl-Hermann; Ludwig, J. C.

doi:10.1002/srin.198700877

Cited by 61 publications

(40 citation statements)

References 8 publications

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“…[11] The effect of thermal convection on the flow is accounted for with the Boussinesq approximation [11] , which accounts for thermal buoyancy forces via the last term in Eq. [2].…”

Section: A Fluid Flow and Heat Transfer Modelmentioning

confidence: 99%

Modeling of inclusion removal in a tundish

Miki¹,

Thomas

1999

Metall Mater Trans B

167

116

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Mathematical models have been developed to predict the removal of alumina inclusions from molten steel in a continuous casting tundish, including the effects of turbulent collisions, reoxidation, flotation, and removal on the inclusion size distribution. The trajectories of inclusion particles are tracked through the three-dimensional (3-D) flow distribution, which was calculated with the K-ε turbulence model and includes thermal buoyancy forces based on the coupled temperature distribution. The predicted distributions are most consistent with measurements if reoxidation is assumed to increase the number of small inclusions, collision agglomeration is accounted for, and inclusion removal rates are based on particle trajectories tracked through a non-isothermal 3-D flow pattern including Stokes flotation based on a cluster density of 5,000 kg/m 3 , and random motion due to turbulence. Steel samples should be taken from as deep as possible in the tundish near the outlet and several residence times after the ladle is opened, in order to best measure the Al 2 O 3 concentration entering the submerged entry nozzle to the mold. Inclusion removal rates vary greatly with size and with the presence of a protective slag cover to prevent reoxidation. The random motion of inclusions due to turbulence improves the relatively slow flotation of small inclusions to the top surface flux layer. However, it also promotes collisions, which slows down the relatively fast net removal rates of large inclusions. For the conditions modeled, the flow pattern reaches steady state soon after a new ladle opens, but the temperature and inclusion distributions continue to evolve even after 1.3 residence times. The removal of inclusions does not appear to depend on the tundish aspect ratio for the conditions and assumptions modeled. It is hoped that this work will inspire future measurements and the development of more comprehensive models of inclusion removal.These validated models should serve as powerful quantitative tools to predict and optimize inclusion removal during molten steel processing, leading to higher quality steel.

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“…[11] The effect of thermal convection on the flow is accounted for with the Boussinesq approximation [11] , which accounts for thermal buoyancy forces via the last term in Eq. [2].…”

Section: A Fluid Flow and Heat Transfer Modelmentioning

confidence: 99%

Modeling of inclusion removal in a tundish

Miki¹,

Thomas

1999

Metall Mater Trans B

167

116

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“…The top surface of the tundish was taken to be a free surface where zero shear stress condition was applied according to references. 6,29,39) The bottom of the tundish was treated as a wall where no slip conditions were used for the velocity. At the outlets a fixed pressure of 1 atm was applied.…”

Section: Boundary Conditionsmentioning

confidence: 99%

“…Even though a lot of studies on flow behavior in tundish has been carried out using physical modeling [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] as well as mathematical modeling, 16,[26][27][28][29][30][31][32] very little information is available on multi-strand billet & bloom casters taking the overall mixing phenomena in it as a whole. Madias et al 33) have studied the effect of APB on mixing in a multi-strand tundish in an experimental work.…”

Section: Introductionmentioning

confidence: 99%

Fluid Flow and Mixing in a Six Strand Billet Caster Tundish: A Parametric Study.

2001

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Mixing phenomena in a six strand billet caster tundish has been studied by numerically solving the Navier Stokes equations along with the species concentration equation in a boundary fitted coordinate system comprising the geometry of the tundish. The solution of the species concentration equation has been utilized to compute the mix, dead and plug volume of the tundish under different flow conditions. The numerical procedure and solution algorithm has been first verified by comparing the numerically obtained residence time distribution curve, which agree well with that of the experiments done for a single strand bare tundish by Singh and Koria. 44) It has been observed that the ratio of the mix to dead volume for the six strand tundish has a maximum value for a particular position of the outlets. At that particular position of the outlets (where mixing is best), an APB is placed on the bottom of the tundish surrounding the incoming inlet jet and the height of the APB has been varied to see the effect on mixing in the tundish. It has been observed that the ratio of mix to dead volume further increases with the use of APB and attains a peak value after which it decreases with the increase of the height of the APB signifying the existence of an optimum APB height. At this optimum height of the APB, the shroud immersion depth was made to change from 0 to 400 mm. It was also observed that there exists an optimum immersion depth of the shroud where the ratio of mix to dead volume still attains another peak signifying still better mixing. However, increasing the immersion depth to higher values spoils mixing significantly.KEY WORDS: billet caster tundish; mixing; mean residence time; advance pouring box; shroud immersion depth.benefit in terms of gaining better mixing in the tundish as discussed in Sec. 3.2 rather than putting dams and weirs. It should be noted here that fixing up dams and weirs in a tundish is a much involved job rather than changing outlet positions, which seem to be rather easier. Moreover on the leeward side of the dams and weirs, there will normally be dead zones which rather spoils mixing in the tundish. So this has been tried in the present work and in addition to this an Advanced Pouring Box (APB) has been put around the inlet jet where it impinges on the bottom plane so that the resulting flow may create better mixing in the tundish. The effect of the height of the APB brings in interesting variations to the flow field and also to the mixing in general. The effect of the shroud immersion depth makes the flow field still benign to mixing, which is normally not found in literature in the present form. So the present study is an effort in this direction. Physical Description of the ProblemThe geometry of the billet caster tundish is shown in Fig. 1a along with the three outlets. The tundish is shown half because of the symmetry about the inlet plane. The depth of the tundish and the bottom pad are 572 and 280 mm respectively with the size of the inlet as 25 mmϫ50 mm and all other dimensions a...

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“…[1][2][3][4][5][6][7][8] As an essential refining vessel, the continuous casting tundish shows markedly metallurgical functions for regulating the flow pattern of molten steel and inclusion removal. 6,[9][10][11][12][13][14][15][16][17][18][19][20] The generation and removal of inclusions in a practical tundish are the combination of multicomplicated physical and chemical processes. Nonmetallic inclusions mainly originate from reoxidation, slag entrainment, mechanical erosion of refractory, etc.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of the Growth and Removal of Inclusions in the Molten Steel of a Two-Strand Tundish

Ling

Zhang

2013

JOM

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In the current article, the growth of inclusions by turbulent collision and their removal in the molten steel of a two-strand tundish was calculated. The fluid flow was coupled with heat transfer and the concentration field of inclusions in the tundish. The weir and dam was effective to control the strong stirring energy within the inlet zone. The collision among inclusions in the inlet zone was far stronger than that in other zones. The rising velocity of 9.2-lm inclusions was far smaller than the flow velocity; thus, small inclusions followed the fluid flow well. The concentration of 4-lm, 5-lm, and 9.2-lm inclusions at the outlet were 9.9 ppm, 9.1 ppm, and 30.2 ppm, respectively. The concentration of other inclusions was within 2.0 ppm-6.0 ppm. The total oxygen of the molten steel at the outlet after reaching the steady state was 38.5 ppm assuming all inclusions were alumina. The removal fraction considering turbulent collision growth was 23.0% more than that without considering collision growth.

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Steel flow and inclusion separation in continuous casting tundishes

Cited by 61 publications

References 8 publications

Modeling of inclusion removal in a tundish

Modeling of inclusion removal in a tundish

Fluid Flow and Mixing in a Six Strand Billet Caster Tundish: A Parametric Study.

Numerical Simulation of the Growth and Removal of Inclusions in the Molten Steel of a Two-Strand Tundish

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