Investigation of Circulation Flow and Slag-Metal Behavior in an Industrial Single Snorkel Refining Furnace (SSRF): Appli
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he 1970s, the Single Snorkel Refining Furnace (SSRF) was originally exploited through the reformation of RH to improve refining efficiency for small capacity ladle in China,[1] and now it has been developed as a multifunctional vacuum refining equipment for the mass production of special steel.[2,3] Subsequently, a similar degasser named Revolutionary Degassing Activator (REDA) was independently developed by Nippon Steel Corporation in the 1990s, and now it has been steadily applied to the manufacture of ultra-low carbon steel.[4–8]
WEIXING DAI, GUOGUANG CHENG, and GUOLEI ZHANG are with the State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing, 100083, P.R. China. Contact e-mail: [email protected] ZHIDONG HUO and PEIXIAN LV are with the Zhejiang Hangzhen Energy Technology Co., Ltd, Hangzhou, 311121, P.R. China. YUNLONG QIU and WEIFEI ZHU are with the Zhongxing Energy Equipment Co., Ltd, Nantong, 226126, P.R. China. Manuscript submitted July 11, 2019.
METALLURGICAL AND MATERIALS TRANSACTIONS B
The circulation principle of SSRF can be depicted in Figure 1; the lifting gas is blown from the ladle bottom, and the hot metal is circulated between the ladle and vacuum chamber through a large-size snorkel. Owing to the large injection depth and the reduced pressure, a large bubble-activated surface can be obtained in the vacuum chamber,[9,10] which allows the molten steel to realize high-efficiency removals of carbon, hydrogen, and nitrogen from the molten steel. It is well known that the reasonable flow field is one of the important prerequisites for efficient refining. Concerning this topic, many cold experiments[11–13] and mathematical modeling[14–16] have been performed to investigate the effect of various parameters on the flow field in SSRF or REDA, including gas injecting position, gas flow rate, snorkel diameter, immersion depth, etc. Most of these researches focused on the optimization of the flow field of molten steel, while the flow behavior of the slag layer in ladle or vacuum chamber is rarely noticed. In practice, the ladle slag is usually covered above the molten steel, while the top slag in the vacuum chamber is controlled according to the needs of the process. For decarburization and degassing, the operation of slag-discharge is performed before vacuuming to avoid the ladle slag entering the vacuum chamber and thus reducing reaction
Fig. 1—The sketch diagram of the SSRF.
efficiency.[17,18] For desulfurization process, the desulfurizer is usually added from the vacuum chamber after slag-discharge. Just as RH reactor is widely applied to produce ultra-low sulfur steel,[17] the SSRF has the same advantages as RH for deep desulfurization, that is, strong steel circulation, getting rid of the effect of ladle top slag on the composition of desulfurizer, and avoiding absorption nitrogen because of the closed atmosphere. A lot of researchers have contributed to analyzing kinetic and thermodynamic conditions of RH desulphurization reaction combining with the practical proce
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