Behaviour of Bubbles at Gas Blowing into Liquid Wood's Metal.

Xie, Yongkun; Orsten, Stefan; Oeters, Franz

doi:10.2355/isijinternational.32.66

Cited by 81 publications

(66 citation statements)

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“…The removal efficiency of small bubbles (2 mm) on inclusion is higher than that of large bubbles (10 mm). But generally, the diameter of bubbles generated through tuyeres in gas stirring ladle is at range of 10 to 20 mm, 38) so removal efficiency of inclusion by bubble adhesion is very low. In this case, it is essential to develop a new method to generate smaller bubbles to improve inclusion removal efficiency in gas stirring ladle.…”

Section: Effect Of Different Growth Mechanisms On Collision Frequencymentioning

confidence: 99%

Mathematical Model for Growth and Removal of Inclusion in a Multi-tuyere Ladle during Gas-stirring

et al. 2005

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A three-dimensional mathematical model has been developed to predict the growth and removal of inclusions during gas stirring in a multi-tuyere ladle. In the model, the efficiency of inclusions removal have been investigated under three different collision mechanisms of Brownian collision, turbulent collision and Stokes collision. Importance of the three approaches of wall adhesion, Stokes flotation and bubbles adhesion to remove inclusions has been analyzed. The results indicated that inclusions growth resulting from turbulent collision is most important and that effect of Stokes collision is remarkable as size of inclusions and difference in size of two particles increase, while inclusion growth resulting from Brown collision is negligible. Removal by Stokes flotation is main manner for large inclusions, while inclusion removal by wall adhesion is negligible. The smaller bubbles contribute the higher efficiency of inclusion removal.KEY WORDS: mathematical model; inclusion growth; inclusion removal; multi-tuyere ladle; gas stirring; bubble flotation. iors of molten steel and inclusion are different in gas stirring ladle with one tuyere and two tuyeres. The object of this paper is to develop a current three-dimensional mathematical model to predict inclusion growth and removal in gas stirring ladle with multi-tuyere and investigate the factor of this process. Flow of molten steel and transfer behavior of inclusion have been studied in this model by use of CFD software package, CFX. Calculation of inclusion growth and removal were carried out by amending transport equation using FORTRAN code. As an application of this model, the distribution of alumina particle in a ladle with different position of tuyere has been calculated. Mathematical Model AssumptionsThe mathematical model of inclusion growth and removal in this investigation is based on the following assumptions: Assumptions concerning the molten steel:1 the liquid steel inside the ladle is incompressible Newtonian fluid and flow fluid is transient. 2 the effect of slag at top surface of molten steel on flow was not considered. 3 injected gas overflows the top surface of molten steel which was set as free surface, and gravitation and fluctuation of free surface are negligible. 4 the molten steel in a ladle is steady at initial time. 5 the effect of nature convection on flow of molten steel is negligible. 6 the flow of molten steel in a ladle is turbulence flow. 7 the heat flux values of 12 500 W/m 2 21) and 36 000 W/m 2 22) were respectively used for refractory bricks used in a ladle and free surface of molten steel. Assumptions concerning bubbles: 8 the bubbles generated at tuyere have the same sizes, and the frequency of bubbles can be calculated by conversation of volume. 9 the generated bubbles are spherical and rigid. 10 interactions of bubbles are negligible. Assumptions concerning inclusions:11 inclusions are spherical and uniformly distributed in molten steel at initial time. 12 the size of inclusion particles is so small that the effect of inclusio...

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Section: Effect Of Different Growth Mechanisms On Collision Frequencymentioning

confidence: 99%

Mathematical Model for Growth and Removal of Inclusion in a Multi-tuyere Ladle during Gas-stirring

et al. 2005

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“…. ; B, iron/argon 13) ; C, mercury/air 14) ; D, wood's metal/nitrogen 15) ; E, water/air 11) ; F, water/air 12) ; G, water/air 16) ; H, water/air 17) ; I, water/air 18) ; J, water/air. ; B, iron/argon 13) ; C, wood's metal/nitrogen 15) ; D, wood's metal/helium 19,20) ; E, water/air 11) ; F, water/air 12) ; G, water/air 17) ; H, water/air.…”

Section: Verification Against Experimental Dataunclassified

A Unified Approach to the Fluid Dynamics of Gas–Liquid Plumes in Ladle Metallurgy

Krishnapisharody

Irons

2010

ISIJ Int.

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The paper focuses on the fundamental aspects of the fluid mechanics of unconstrained gas-liquid plumes relevant to Ladle Metallurgy Practice. A mathematical model previously proposed by the authors is justified by comparison with Eulerian-Lagrangian models. Further, a unified analytical framework is proposed to describe the fluid dynamic and similarity characteristics of two-phase plumes. Despite the apparent complexity of the system, the analysis demonstrates that the plume cross-sectional area, void fraction and gas and liquid velocities can be quantified in terms of two parameters: a dimensionless gas flow rate and the normalized axial height. The analysis clarifies the proper form of the Froude number similarity which is important for process design and scale-up.KEY WORDS: gas-liquid plume; ladle metallurgy; mathematical model; similarity analysis. above equations properly capture available experimental data. An additional outcome of the work is that this analysis is linked with dimensional analysis to provide a unified framework for gas-liquid plumes relevant to Ladle Metallurgy practice. Dimensionless Representation of Two-phase PlumesThe analysis starts by considering all the possible variables which can be broadly categorized as geometric factors (ladle diameter, height, and porous plug/lance location), physical properties (densities and viscosities) and external factors (gas flow rate and gravity). Some of these variables can be eliminated from the analysis, as discussed below.The diameter of the ladle has been shown in a survey of previous work 5,6) to be large enough to not affect plume dynamics. Furthermore, the plug is usually located far enough from the wall, so as not to interact with it, so the plume is free-rising. 7,8) It has been shown elsewhere that ladle flows are typically Froude dominated and viscous effects have only a secondary effect on the plume and bulk flows, 9,10) so the viscosity can be neglected. The gas and liquid densities drop out of the analysis, as explained in Appendix A. Interfacial tension is not considered because bubbles in water models as well as liquid metal systems are generally in the spherical-cap regime in which shape and velocity are determined by drag and buoyancy. Figure 2 shows schematically that the remaining independent variables: gas flow rate Q, metal height H, vertical position z and gravitational acceleration g influence the dependent plume variables: crosssectional area, A p , void fraction, ā, and liquid and gas velocities, Ū l and Ū g . The overbar indicates that these quantities are averaged over the plume cross sectional area.It is now convenient to introduce two dimensionless quantities that contain only the independent variables: Mathematical AnalysisThe present model (Eqs. (1) to (4)) is essentially a onedimensional model in which the variables change over the height of the bath, but are averaged over the cross-section of the plume. The conventional Eulerian-Lagrangian models are usually solved in 2 or 3 dimensions with computational fluid dynami...

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“…Therefore, in order to understand the steel CCC process of round billets, mathematical modeling of the fluid flow phenomena is a feasible choice. Many turbulent models and multiphase models have been used for the fluid flow in gas-stirred steel refining processes [10][11][12] and steel continuous casting processes [13][14][15][16][17][18][19][20][21][22][23] , as summarized in Table I. However, so far very few investigations on CCC process were reported.…”

Section: Introductionmentioning

confidence: 99%

Modeling on Fluid Flow and Inclusion Motion in Centrifugal Continuous Casting Strands

Wang

Zhang

Sridhar

2016

Metall Mater Trans B

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In the current study, a three-dimensional multi-phase turbulent model was established to study the transport phenomena during centrifugal continuous casting process. The to 18° and rotation speed from 40 to 80 revolutions per minute favored to decrease the total volume of entrained bubbles, while the increase of distance of nozzle moving left and casting speed had reverse effects. The trajectories of inclusions in the mold were irregular, and then rotated along the strand length. After penetrating a certain distance, the inclusions gradually moved to the center of billet and gathered there. To discuss the heat transfer, solidification and inclusions entrapment during centrifugal continuous casting, more work will be performed.

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Behaviour of Bubbles at Gas Blowing into Liquid Wood's Metal.

Cited by 81 publications

References 0 publications

Mathematical Model for Growth and Removal of Inclusion in a Multi-tuyere Ladle during Gas-stirring

Mathematical Model for Growth and Removal of Inclusion in a Multi-tuyere Ladle during Gas-stirring

A Unified Approach to the Fluid Dynamics of Gas–Liquid Plumes in Ladle Metallurgy

Modeling on Fluid Flow and Inclusion Motion in Centrifugal Continuous Casting Strands

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