The Effect of Configuration of Tuyeres on Mixing
For the sake of comparison, the mean value of measured mixing time was obtained from water model experiment of the different arrangement of tuyeres as shown in Fig. 3. Figure clearly indicates that the shortest mixing time was obtained in the case of single tuyere placed at 2/3R off center (Case C). Under the circumstance of two-tuyere, Case D was found to be the best arrangement that two tuyere were opposite placed at half radii in the ladle. Case H was found to be the worst.
The Effect of Gas Flowrate on Mixing
According to Eqs. 3 and 6, H0 represented the nondimensionalized mixing time and Fr' were dimensionless value that have a relationship with gas flowrate. As could be seen from Fig. 4, H0 as a function of the Fr'/10-4 appeared growing trend.
The tendency for predicted mixing time to change with the different gas flowrate was shown in Fig. 5. In general, it could be concluded that the mixing time decrease with increasing gas flowrate. Especially in the case of small gas flowrate, mixing time drastically decreased when the gas flowrate increased. However, the effect was not impressive when the gas flowrate was above 80L/h. This may be due to some reversed flows.
Compared Figs. 4 and 5, when the flowrate increased, H0 became larger and the mixing time became shorter. The reason for this phenomenon was that the magnitude of the gas flowrate varied much larger than the change of the mixing time.
Fig. 3 Relationship between tuyere configuration and the mixing time
Fig. 4 Relationship between H0 and Fr'
Fig. 5 Effect of flowrate on mixing time
The Effect of Aspect Ratio on Mixing Time
Measured values of mixing time for different aspect ratios(H/D) were shown in Figs. 6 and 7 represented the tendency for H0 to change with different aspect ratios (H/D). When the aspect ratio increased, the depth of molten pool increased, and the buoyancy of bubbles would be with the greater potential energy. What’s more, it benefited for increasing the mixing power of the gas. But, the increasing depth of molten pool led to increasing quality of molten steel, decreasing the unit stirring power and making the mixing became longer.
Fig. 6 Relationship between H0 and aspect ratio
Fig. 7 Effect of aspect ratio on mixing time