Numerical Simulation of Gas and Liquid Two-Phase Flow in the RH Process
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ahl–Heraeus (RH) degasser is widely used for the production of the ultralow-carbon steel. It plays an extremely important role in the refining process for decarburization, deoxidization, desulfurization, temperature control, inclusion removal, and composition homogenization. The above-mentioned operations are closely related to the gas–liquid flow behavior in the RH degasser. Thus, understanding the gas–liquid flow behavior in the RH degasser is of great importance for improving refining efficiency. Due to the limitations of high temperature, multiphase system, and vacuum conditions, the numerical simulation is considered as an effective way to simulate the fluid flow in the RH degasser. Currently, the modeling approaches mainly involve the quasi-single-phase model,[1,2] the Eulerian–Lagrangian approach,[3] and the
HAITAO LING is with the School of Metallurgical Engineering, Anhui University of Technology, Ma’anshan, 243002 Anhui, China. Contact e-mail: [email protected] LIFENG ZHANG is with the Beijing Key Laboratory of Green Recycling and Extraction of Metals (GREM) and the School of Metallurgical and Ecological Engineering of University of Science and Technology Beijing (USTB), Beijing 100083, China. Manuscript submitted December 8, 2018. Article published online May 29, 2019. METALLURGICAL AND MATERIALS TRANSACTIONS B
Eulerian–Eulerian approach.[4–8] Furthermore, the discrete phase (DPM) and volume of fraction (VOF) models are employed in conjunction to model the multiphase flow in the RH degasser.[9–11] The interfacial behavior between the molten steel and the gas phase, and the motion of gas bubbles can be simultaneously tracked and predicted. Due to the phase interaction, there exists momentum exchange between the molten steel and gas bubbles, which significantly affect the characteristics of circulation and mixing in the RH degasser. Obviously, descriptions of the phase interaction and of momentum exchange between the two phases depend on correct calculation of the interphase forces acting on the gas bubbles. The interphase forces can be divided into the drag force and non-drag forces. The latter include the lift force, the virtual mass force, the pressure gradient force, etc. The effects of interphase forces on the fluid flow and gas phase distribution are extensively investigated in gas-stirred ladles.[12–15] However, these valuable results obtained in gas-stirred ladles may not be appropriate for gas–liquid two-phase flow in the RH degasser. For the RH system, gas bubbles are injected into the up-leg snorkel horizontally, and they can penetrate the liquid up to a certain depth, and then rise up. Due to the change of movement direction of gas bubbles, the directions of interphase forces are frequently changed. Nevertheless, for gas-stirred ladles gas bubbles enter the
VOLUME 50B, AUGUST 2019—2017
liquid from the bottom tuyeres, and then move upwards along the vertical direction. The directions of interphase forces are relatively fixed. Although some researchers have tried to evaluate the importance of interphase forces a
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