Abstract
Particle image velocimetry (PIV) system was adopted to investigate the relationship between the mixing phenomenon and the flow field of a 210 t RH degasser by a 1:4 scale water model. The results of mixing simulation experiments indicated that the mixing time decreased with the increase of gas blowing rate. However, with the increase of Snorkel immersion depth (SID), the mixing time presented a decreasing rend firstly and then increased. The measurement of flow fields of RH ladle by PIV system can explain the phenomenon above. According to the characteristics of the flow field in RH ladle, the flow field can be divided into the mixing layer, the transition layer, and the inactive layer. On the one hand, the stirring power in RH ladle and vacuum chamber both increases with more gas blowing rate, leading to the decrease of mixing time. On the other hand, with SID increases from 400 mm to 480 mm, the gas blowing depth increase results in the mixing power increases, and the mixing time decreases at the beginning. Because of too much-molten steel in the vacuum chamber and the expanding of the inactive layer in RH ladle, however, the utilization rate of the gas driving force begins to decrease. Therefore, the mixing time started to increases with the increase of SID.
Highlights
As the the world economy develops and evolves, the pursuits of the steel products quality are gradually increasing, leading to the improvement requirements on the refining
When the Snorkel immersion depth (SID) is 400 mm, the mixing time significantly decreases with the increase of gas flow rate
For the case of 480 mm and 560 mm SID, the mixing time decreases fast when the gas flow rate is less than 1200 L/min; the mixing time decreases slowly when the gas flow rate is higher than 1200 L/min
Summary
As the the world economy develops and evolves, the pursuits of the steel products quality are gradually increasing, leading to the improvement requirements on the refining. The development of continuous casting requires the matching of high refining efficiency. It has been proven [1,2,3,4,5] that Ruhrstahl–Heraeus (RH) vacuum refining, an important technology to improve product quality, reduce cost, and expand variety, has become the most widely used refining equipment in the world. Mixing time is an important index to measure the refining efficiency of RH, and it reflects the effect of mixing of the molten steel in the RH degasser [6,7,8,9,10]. To understand and master the relationship between the mixing time and the process parameters is significant to the design and optimization of the RH equipment and refining process.
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