Effect of Separation Angle and Nozzle Radial Position on Mixing Time in Ladles with Two Nozzles

Abstract

Chemical, thermal and mechanical homogenization of both slag and steel during the ladle furnace process depends on the design of the gas injection system in gas bottom stirred ladles. In the past, a large number of variables have been investigated, nevertheless due to the importance of the slag layer during the process, it has been incorporated in water modeling studies in more recent investigations. In large industrial size ladles is common to use two porous plugs. The configuration of the injection system with two porous plugs requires optimization of both nozzle radial position and nozzle separation angle. In this work the effect of nozzle radial position, nozzle separation angle, gas flow rate and slag thickness on mixing time has been investigated using a water model. The effect of tracer concentration on mixing time was also explored. It is shown that a separation angle of 60 degrees provides the best mixing efficiency.

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

“…This is because two stirring rotations can increase the surface of the tracer diffusion. In most of the previous works [5,8,9,[12][13][14]16], NaCl or KCl solutions were used as the tracers to determine the mixing time by monitoring the conductivity in the physical modelling trials. Nevertheless, the tracer's density is larger than that of normal water.…”

“…In terms Bold terms are the controlling parameters of each term in mathematical modelling. Moreover, for the ladles with various weights, the optimal radial positions and separation angles of the plugs were collected in previous works [5,[7][8][9][11][12][13][14]16,19,20], as shown in Figure 15. In terms of the mixing condition, an optimal range of plug's radial location is mainly off-centered for a single plug injection at values ranging from 0.72R to 0.75R.…”

“…In the physical modelling, the criteria for dynamic similarity [3,4] in gas-stirred ladles were investigated both theoretically and experimentally. For the alloy homogenization in the physical experiment, the mixing time and flow pattern in the ladle was affected by plug numbers, plugs' positions in the radial direction, and dual plugs' angles, and these were studied the most [5][6][7][8][9][10][11][12][13][14]. Moreover, the conducting materials are usually used as tracer additions for the electrical conductivity sensors [5,15].…”

“…A dual plugs' configuration was recommended at the mid-radius position and diametrically opposite position. Also, the effects of separation angles, radial locations, and slag layer thicknesses on the mixing time were analyzed by Gómez et al [14]. In an up-to-date study, Duan et al [20] gave the effects of plugs' radial positions and separation angles on the turbulent dissipation and mixing conditions.…”

A Review of Physical and Numerical Approaches for the Study of Gas Stirring in Ladle Metallurgy

“…Mixing and homogenization in ladles are fundamentally important in metallurgical processes. Concerning this research, the following aspects have been studied: how the mixing time and flow pattern in the ladle are affected by the plug configuration with bottom blowing or top blowing [8,[12][13][14][15][16][17][18][19][20] (that is, the plug number, plug location in the radial direction, and separation angle of dual plugs), the tracer injection point, [8,21] and the sensor monitoring point. [8] In addition, the mixing time defined by two degrees (95 and 99 pct) has been discussed in some works.…”