Computational Investigation of Swirling Supersonic Jets Generated Through a Nozzle-Twisted Lance
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ern metal smelting processes, supersonic gas jet(s) lance is usually employed to deliver gas for enhancing the unit performance and achieving the necessary process functions. A prominent example of such process is the basic oxygen furnace (BOF) steelmaking, where high-pressure oxygen is efficiently transformed into supersonic jets through a hanging water-cooled lance with multiple convergent–divergent nozzles, and the jets provide a considerable oxygen-supplying efficiency to refining the pig iron.[1] Furthermore, the oxygen jets play an extremely significant role in forming major process phenomena such as splashing, cratering, stirring, slagging, and producing and maintaining the slag foam. However, it is found that the oxygen jets are also responsible for some undesirable in-furnace phenomena, such as ‘‘spitting’’ and the consequent low metallic recovery, wearing of refractories as well as skulling on the mouth of the vessels and
MINGMING LI, Ph.D. Student, QIANG LI, Associate Professor, and ZONGSHU ZOU, Professor, are with the Laboratory of Multiphase Transport and Reaction Engineering, Department of Ferrous Metallurgy, School of Metallurgy, Northeastern University, P.O. Box 312, 3-11 Wenhua Road, Heping District, Shenyang 110819, Liaoning Province, P.R. China. Contact e-mail: [email protected] XIZHONG AN, Professor, is with the Department of Ferrous Metallurgy, School of Metallurgy, Northeastern University. Manuscript submitted May 22, 2016. Article published online November 14, 2016. METALLURGICAL AND MATERIALS TRANSACTIONS B
lances, which generally cause operational problems and low benefits.[2,3] Therefore, a carefully designed lance is imperative to control the dynamics of the jets and to ultimately achieve high reactor efficiency and stable process operation in BOF. In the past decades, the oxygen lance used in BOFs has evolved from single-nozzle arrangement to multi-nozzle ones in which each nozzle has an appropriate angle with the lance geometrical axis. Detailed knowledge with respect to the dynamics under various conditions for jets generated by this so-called conventional ‘‘normal lance’’ is constantly accumulating and has made important contributions to the process optimization and technological innovation.[4–19] Nevertheless, with increasing requirement for higher production efficiency and lower cost, these normal lances are not qualified to provide a satisfactory solution to the further optimization of the units, since they have inherent features and some limitations in few operational factors controlling the behaviors of the produced jets in addition to the nozzle dimension and inclination angle of the lance. Such issues have led to the consideration of new schemes for improving the performance of the jets. The most popular solutions are to modify or design a new type of lance, such as the double-parameter lance,[20] and the multi-nozzle lance with one central subsonic nozzle.[21,22] Another important innovative design, referred as the ‘‘nozzle-twisted lance,’’[23] was also developed, initially aiming to sup
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