Study On The Bubble Size And Distribution In Tundish By Numerical Simulation

With the increasing quality requirements for steel products, many of cleanliness requirements of high-performance steel are also increasing. reducing harmful inclusions, especially 3~20μm tiny inclusions in steel-making process has become one important issues need to be solved. At present, Through setting the flow control device in tundish and using of air brick, ventilation plugs argon gas can be relatively easy way to remove the size of 50μm or more inclusions, inclusion of size 20 ~ 50μm can also be good removal, but for small inclusion is also difficult to remove. Through analysis of previous studies found that the use of adhesion collision bubble method to remove tiny inclusions is more feasible method, But The key problem with this method is the presence of bubbles of relatively small size in tundish to increase the probability between bubbles and inclusion. Therefore, the study of the size and distribution of bubbles in tundish has great significance.First of all, This paper use DPM discrete phase model to study the relationship between the size of the bubble in the tundish and its floating. The results show that: when the size of bubbles in tundish is larger than 0.5mm, Bubbles can completely rely on their own buoyancy float, and only distributed near the injection flow area in tundish, When the bubble size is less than to 0.1mm, Bubbles is more dispersed in the tundish.Secondly, we analysis the bubbles in the liquid broken and coalescence mechanism and bubbles floating in tundish. This paper introduces considering bubbles broken and coalescence of PBM population balance model, and analysis of the model is validated by throughing the water model experiments and the use of discrete interval method, Lehr’s broken and Luo’s coalescence model of numerical simulation of the model results PBM comparative.Simulation analysis the injection of different sizes from shroud for tundish impact bubble size and its distribution. The results show that: bubbles size and its distribution in tundish between the injection of bubbles has a great relationship. When injecting smaller bubbles, Bubbles has a greater magnitude grow in the shroud and the impact depth with the tundish flow is increasing. Note flow area larger than the size of the outer edge of the bubble inside a bubble stream. Bubble volume is exponentially lower with distance away from the main area increases. When the bubble size in tundish is larger, Bubbles near the tundish’s note flow area inverted umbrella distribution, its flow is influented weakened by steel stocks, not as liquid steel flows into the depths of the tundish. bubbles has a more low volume ratio in other area of tundish(except injection flow zone). The bubble volume reaches -9e above the exit.Finally, this paper simulates bubbles size and its distribution with a turbulator by numerical Simulation, and analysis the effect of different turbulator structure for bubbles size and its distribution. The results shows: When bubbles out shroud is smaller,turbulator is able to bind the turbulent kinetic energy, slow the flow of bubbles in the injection zone length substantially; but it is not able to broke bubbles. Turbulator’s top edge should not be too long, nor too short, When the roof rafters too long,note bubble with molten steel flow is blocked out of turbulator, causing a lot of size is relatively large bubbles distribute at top of the turbulator, it’s easy to make liquid steel exposed, contaminated liquid steel. The edge turbulence easy diversion hole is too large, When pore size is too large, turbulent kinetic energy released from the bottom of turbulence, Also not achieve bound turbulent kinetic energy and slow bubble growth.