In continuous casting tundish steelmaking, old ladle is replaced by new one to ensure continuous supply of steel from tundish to mold. Bath height changes in case of ladle change-over. To bring the bath height level to normal height, the flow rate of liquid steel from the new ladle is increased. This has a direct bearing on the fluid flow pattern and resultant intermixed amount formed. In the present work, assessment of Reynoldsaveraged Navier-stokes (RANS) equations based standard k-ε, Renormalization group (RNG) k-ε, Realizable k-ε standard k-ω, and Shear-stress transport (SST) k-ω turbulence models have been carried out for prediction of free surface level of steel in tundish during ladle change-over and the intermixed amount formed. Coupled Level-Set Volume of Fluid (CLSVOF) method was used for free surface tracking in the three dimensional, multi-phase numerical model. Physical investigations were carried on water model setup of reduced scale tundish. Inflow rate of steel into the tundish from second ladle was varied due to which free-surface height of water varied and grade mixing in tundish was analyzed. Results obtained through physical investigations were compared with that of numerical investigations. The predictions revealed that RNG k-ε model have good approximation of F-curves as well as the interface between the two phases. Predictions made by all models except SST k-ω model have shown a satisfactory approximation with the experimental values. Free-surface interface profiles predicted by variants of k-ε models were seen to closely match with experimental data.
The intermixing of dissimilar grades of steel in tundish during the ladle change-over is a problem of growing interest. During sequential casting of different grades, it is important that the intermixing of the grades is kept to a minimum. Present work deals with computational and water model studies of the three-dimensional turbulent fluid flow in a multi-strand tundish during ladle change-over process. The physical investigation has been carried out by conducting experiment on a 1:4 scale model of tundish. The numerical simulations have been carried out with the help of educational version of ANSYS Fluent, using the Volume of Fluid (VOF) method and incorporating standard k-ɛ turbulence model. The numerical model has been validated with the results of physical investigation and is found to be in good agreement. Further, the numerical model is used to study the ladle change-over process considering effect of inflow rate on grade mixing and interface positions, i.e., different bath height positions in tundish with and without advance pouring box (APB). It has been observed that the use of APB is not helpful in reducing the intermixed time while increase in flow rate of new grade steel decreases the intermixed amount.
The first-ever use of halloysite nanotube (HNT), a relatively low-cost nanomaterial abundantly available with minor toxicity for removing brilliant green dye from aqueous media, is reported. The factors affecting adsorption were studied by assessing the adsorption capacity, kinetics, and equilibrium thermodynamic properties. All the experiments were designed at a pH level of around 7. The Redlich-Peterson isotherm model fits best amongst the nine isotherm models studied. The kinetic studies data confirmed a pseudo model of the second order. Robotic investigations propose a rate-controlling advance being overwhelmed by intraparticle dispersion. The adsorbent features were interpreted using infrared spectroscopy and electron microscopy. Process optimization was carried out using Response Surface Methodology (RSM) through a dual section Fractional Factorial Experimental Design to contemplate the impact of boundaries on the course of adsorption. The examination of fluctuation (ANOVA) was utilized to consider the joined impact of the boundaries. The possibilities of the use of dye adsorbing HNT (“sludge”) for the fabrication of the composites using plastic waste are suggested.
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