Determination of Cavity Dimensions Induced by Impingement of Gas Jets onto a Liquid Bath
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THE impingement of a high-speed jet onto a deformable liquid surface is commonly encountered in many industrial engineering applications.[1–6] The resulting interaction between the jet and liquid surface is often of critical importance to the transfer of mass, kinetic, and thermal energy in the process units involved and thus determines their performance.[7,8] However, it is yet a challenge to reliably predict such an interaction and associated phenomena in many applications. This situation is particularly true for the steelmaking BOF which is a key metallurgical reactor used in the modern steel industry.[9,10] In a steelmaking BOF, the top-blown oxygen gas jets from a multi-hole lance create a cavity on the surface of the liquids bath consisting of immiscible metal (heavier) and slag (lighter with much less volume) phases, and simultaneously cause ‘‘spitting’’ or ‘‘splashing’’ of different-sized droplets (Figure 1). The cavity represents one of the main sites where the key refining reactions (e.g., decarburization) occur. It is established that cavity dimensions, which are mainly affected by variables related to gas flow rate and lance MINGMING LI, Ph.D. Student, QIANG LI, Associate Professor, and ZONGSHU ZOU, Professor, are with the School of Materials and Metallurgy, Northeastern University, Heping District, 3-11 Wenhua Road, Heping District, P. O. Box 312, Shenyang 110819, Liaoning, P.R. China, and also with the Key Laboratory of Ecological Utilization of Multi-metallic Mineral of Education Ministry, Northeastern University, Heping District, Shenyang, 110819, P.R. China. Contact e-mail: [email protected] SHIBO KUANG, Research Fellow, is with the Department of Chemical Engineering, Monash University, Clayton, VIC, 3800, Australia. Manuscript submitted May 7, 2015. METALLURGICAL AND MATERIALS TRANSACTIONS B
height, determine the mixing of the bath and control the most of chemical reactions and slag formation. For example, the larger the surface of cavity, the higher is the rate of oxidation for decarburization.[11] Therefore, study on the cratering process in a gas–liquid(s) flow systems corresponding to BOF steelmaking, especially the cavity characteristics is beneficial for improving the BOF performance, which can ultimately lead to significant economic benefits because of the large-scale production in practice. In the early 1960s, Banks and Chandrasekhara[12] studied the impingement of a gas jet onto a liquid surface and established the first fundamental relationship between the jet momentum and the penetration depth: M p h0 h0 2 1þ ¼ ; ½1 ql gH3 2K2 H H where M is the gas momentum flow rate, ql is the density of liquid, h0 is the maximum depth of the cavity, and H is the lance distance to the liquid surface. Equation [1] is dimensionless and somewhat general. Following the work of Banks and Chandrasekhara,[12] extensive experimental studies[13–20] were also carried out to investigate the dimensions of the cavity induced by the jet impinging onto the surface of liquid. However, the value of K in Eq. [1] determin
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