Physical and mathematical modeling of inclusion behavior in a tundish with gas curtain

Gisele Márcia De Souza,Alexandre De Freitas Gomes De Mendonça,Roberto Parreiras Tavares

doi:10.1590/0370-44672020730010

Gisele Márcia De Souza, Alexandre De Freitas Gomes De Mendonça + Show 1 more

Open Access

https://doi.org/10.1590/0370-44672020730010

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Abstract

Gas injection in the tundish has been considered as an alternative to optimizing inclusion removal from steels. In the present study, physical and mathematical modeling were used to investigate the effect of gas injection in the tundish on the inclusion removal efficiency. The physical model is a 1/3 reduced scale of an industrial two-strand tundish of 40 tons. The inclusion removal efficiency was quantified using the APS III probe, which counts particles leaving the tundish during the test. Different locations for the gas injection plug were evaluated. Additionally, a mathematical model was developed using commercial CFD software CFX. The predictions of the mathematical model were validated by the physical model results, comparing the efficiency of inclusion removal. The proposed model includes a new boundary condition to describe the behavior of the particles at the free surface, implemented by a special subroutine. The model enabled the identification of appropriate conditions: plugs located at 0.56 or 0.84m from the tundish inlet with gas injection with the flow rate of 3NL/min.

Highlights

The increasing demand for highquality steels requires continuous improvement and strict control of the process by the steel companies
The appropriate project and operation of a tundish are essential to obtain cleaner steels. Flow modifiers such as dams and weirs have been introduced into the tundish
Regarding the mesh independence test, the chosen one was the mesh with 142000 nodes in which there was no more variation in Residence Times Distribution (RTD) curves

Summary

Introduction

The increasing demand for highquality steels requires continuous improvement and strict control of the process by the steel companies. The last metallurgical vessel through which molten steel flows before solidification in the continuous casting mold is the tundish. The appropriate project and operation of a tundish are essential to obtain cleaner steels. Flow modifiers such as dams and weirs have been introduced into the tundish. These devices are designed to direct the steel flow toward the top surface and to increase the effective residence time of steel in the tundish. Both effects intensify inclusion flotation (Sahai, 2016; Chen et al, 2014; Chattopadhyay et al, 2010). In addition to the flow modifiers, the injection of inert gas has been considered (Chang et al, 2016; Zhang et al, 2006)

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