Study of Flow Modification and Inclusion Removal in Slab Tundish Due to Bottom Gas Injection

Abstract

In order to quantify inclusion removal the role of flow pattern inside the tundish is assessed. Also mathematical models of inclusion separation including the influence of inclusion coalescence are discussed. This analysis suggest that as far as small size inclusions are concerned, operational parameters such as piston flow fraction are not important since for them the probability of separation is negligible. However, techniques such as gas curtains are to be considered for better inclusion control. Mathematical and physical modeling results are presented considering association of a porous dam and a ring shaped injection plug positioned around the strand. The results confirm the theoretical expectations as the flow modification, revealed by the mathematical simulation, allows the imprisonment of particles in the reactor and so the fraction of small inclusions leaving the tundish stays under 3% for the gas-assisted strand. Keywords: Tundish; Inclusion removal; Fluid flow; Gas curtain. ESTUDO DE MODIFICAÇÃO DE FLUXO E REMOÇÃO DE INCLUSÕES EM UM DISTRIBUIDOR DE LINGOTAMENTO DE PLACAS DEVIDO A INJEÇÃO DE GÁS PELO FUNDO ResumoCom o intuito de quantificar o papel da remoção de inclusões, avalia-se o padrão de fluxo no interior do distribuidor. Modelos matemáticos de separação de inclusão, incluindo a influência da coalescência de inclusões também são discutidos. A presente análise sugere que no tocante a inclusões de pequenas dimensões, parâmetros operacionais como fração de fluxo pistonado deixam de ser críticos, uma vez que a probabilidade de separação é desprezível. Entretanto, técnicas como o uso de cortina de gás são relevantes para melhor controle do conteúdo de inclusão. Resultados de modelamento físico e matemático são apresentados considerando a associação de uma barreira porosa e um plugue anelar de injeção posicionado ao redor do veio. Os resultados confirmam as expectativas já que a modificação de fluxo, exposta pela simulação matemática, permite que inclusões fiquem retidas no reator, registrando valores de saída abaixo de 3% no caso do veio com aspersão de gás. Palavras-chave: Distribuidor; Remoção de inclusão; Fluxo de fluido; Cortina de gás.

Synthesis of a CFD Benchmark Exercise: Examining Fluid Flow and Residence-Time Distribution in a Water Model of Tundish

“…Current work is noted as User 12 in order to correspond with the published Benchmark I [ 12 ]. The detailed model settings for all participants are described in Table 3 .…”

“…CFD codes contain plenty of physical models for describing the turbulent flow, heat transfer, multi-phase interaction, and chemical reactions. In recent years, there have been a number of research works focusing on the CFD model application of the flow phenomena in tundish, such as residence time distribution [ 6 , 7 , 8 ], flow control device [ 9 , 10 , 11 ], inclusion behavior [ 12 , 13 ], and thermal status [ 14 , 15 , 16 ]. A series of CFD modelling studies have been recently published by the author through international collaborations [ 17 , 18 , 19 , 20 , 21 ].…”

A Simulation-Based Digital Design Methodology for Studying Conjugate Heat Transfer in Tundish

“…To analyze heat transfer of molten steel in the study, CFD models are applied. The studied phenomena of the CFD model include residence time distribution [8][9][10], flow control device [11][12][13], inclusion behavior [14,15] and thermal status [16][17][18]. A series of CFD modelling studies have recently been published by the author and co-workers with the focus on developing a simulation-based digital design methodology to optimize the tundish geometry and process parameters during the casting process [19][20][21][22][23][24][25].…”

Mathematical Modelling of Multiphase Flow and Inclusion Behavior in a Single-Strand Tundish

“…A large number of modelling studies have been carried out to predict and realize the best performance of the tundish in the steelmaking, including: (i) the study of configuration (e.g., FCD); (ii) the study of gas media (e.g., flow rate, bubble size and injection position); (iii) the study of inclusion particles (e.g., size, density and mass flow rate); and iv) the study of simulation models (e.g., fluid, turbulence, particle dispersion, isothermal/thermal, steady/transient). Table 1 lists the published modelling studies that consider gas bubbling and flow control in the tundish [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. It shows that Computational Fluid Dynamics (CFD) has become a very useful and promising tool that can potentially predict accurately many phenomena of practical interest in the tundish.…”