Physical and Numerical Modelling on the Mixing Condition in a 50 t Ladle

Abstract

The bubbly flow and mixing conditions for gas stirring in a 50t ladle were investigated by using physical modelling and mathematical modelling. In the physical modelling, the effect of the porous plugs’ configurations on the tracer homogenization was studied by using a saturated NaCl solution to predict the mixing time and a color dye to show the mixing pattern. In the mathematical modelling, the Euler–Lagrange model and species transport model were used to predict the flow pattern and tracer homogenization, respectively. The results show that, for a ±5% homogenization degree, the mixing time with dual plugs using a radial angle of 180° is shortest. In addition, the mixing time using a radial angle of 135° decreases the most with an increased flow rate. The flow pattern and mixing conditions predicted by mathematical modelling agree well with the result of the physical modelling. For a ±1% homogenization degree, the influence of the tracer’s natural convection on its homogenization pattern cannot be neglected. This is especially true for a ‘soft bubbling’ case using a low gas flow rate. Overall, it is recommended that large radial angles in the range of 135°~180° are chosen for gas stirring in the present study when using dual porous plugs.

Effect of Side Blowing on Fluid Flow and Mixing Phenomenon in Gas-Stirred Ladle

“…) [41]. A large number of studies [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] on fluid flow in a gas-stirred ladle were conducted with physical modeling based on the geometric similarity and flow similarity. In the studies, the molten steel was represented by water, and the argon gas was represented by the air or nitrogen gas.…”

“…Physical modeling was usually adopted to study the hydrodynamics and mixing phenomena in gas-stirred ladles with bottom plugs. The probe measurements of pH and conductivity were widely used to measure the mixing time of the tracer in a model ladle [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. Some researchers [10,15,17] recognized that the mixing time is influenced by the addition position of the tracer and the probe positions in water modeling.…”

“…The high flow rate contributed to reducing the mixing time in the ladle with bottom plugs [19,20]. Some studies [17,[21][22][23] discussed the influences of plugs' configurations, such as plug number, plug radial position, and separation angle of dual plugs on the mixing time. Gómez et al [23] recognized that a separation angle of 60 • provides the best mixing efficiency.…”

Effect of the Location of Tracer Addition in a Ladle on the Mixing Time through Physical and Numerical Modeling

“…20) In most of the previously mentioned papers, the location of the tracer addition has minor importance within the analyzed variables and use a single addition location which, in most of the cases it is located in the slag eye opening. However, various works have been reported in literature with contrasting conclusions, such as the investigations carried out by Krishna Murthy and his colleagues [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] in which the authors conclude that the measurements obtained of the mixing time do not depend on the location neither on the tracer amount released with which the conductivity technique is performed. On the other hand, various authors conclude that not only the location of the sensors 22) affects the mixing time measurements but also the location of the tracer addition [23][24][25] is a variable that considerably affects the time required to reach a homogeneity degree of 95%.…”

“…The degree of mixing at 95% is usually accepted, although the degree of mixing at 99% has also been used, which is more rigorous. 3) The mixing phenomenon has been widely investigated and various works have been reported in literature on the main operation variables that considerably affects mixing time measurements, such as gas flow, [4][5][6][7][8][9][10][11][12][13][14] number and location of injections, [15][16][17][18] as well as properties 19) and thickness of slag. 20) In most of the previously mentioned papers, the location of the tracer addition has minor importance within the analyzed variables and use a single addition location which, in most of the cases it is located in the slag eye opening.…”