Modeling of Vortex Flows in Direct Current (DC) Electric Arc Furnace with Different Bottom Electrode Positions
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THE problem of electrovortex flow control in direct current (DC) electric arc furnaces (EAFs) with the bottom electrode is a current important issue in modern metallurgy.[1–5] As compared with alternating current (AC) EAFs, these furnaces consume 10 to 15 pct less electric energy, 20 to 30 pct less refractory materials, 1.5 to 2.0 pct less feedstock, and 20 to 60 pct less alloying addition. Environmental safety is an essential advantage of this furnace type, as the dust production diminishes 8 to 10 times (from 52.5 to 6.3 kg/h), and the noise level goes down from 105 to 85 dB when this furnace type is operated. The industrial practice has shown that DC EAFs have higher efficiency, low heat loss, lower components wear, and higher quality of steel produced.[3] This furnace type allows using the steel quality control, as well as analyzing and improving the composition with the help of alloying addition in the metal smelting process. The exploitation of these furnaces has shown a high rate of fettle wear near the bottom electrode.[5] The reason for the increased wear is connected with vortex flows of liquid metal caused by spatial homogeneity of electromagnetic fields and temperature. However, mixing liquid metal in the bath during smelting processes is necessary for the homogenization of alloying components and temperature throughout the liquid metal volume. Therefore, the most important objective is to estimate the intensity of vortex flows as an effect of different factors. There are many scientific works that focus on physical processes in DC EAFs.[1,2,6–8] In the earlier works, all general magnetohydrodynamics processes in liquid metal are described and a mathematical model of heat
transfer is presented. In the modern works, a threedimensional model of magnetohydrodynamics processes in DC EAF of cylindrical shape is developed.[2] At the current stage of studying, the processes in liquid metal (both task-specific software packages and general purpose ones with special preferences and selection method of solution) are used.[1,2] In several articles, the arc column is studied as well as the effect of arc column on liquid metal movement and heat transfer from plasma region throughout all the volume of liquid metal.[7,8] Some works deal with the possibility of the molten metal movement operation. For example, some scientists propose to operate the molten metal movement using bath lancing.[7,8] However, these problems have been understudied so far and are important because solving them will make it possible to increase the furnace durability, to cut down the product unit cost, and to reduce the energy consumption and environment pollution. The current article describes the physical processes and mathematical statement of vortex flow in DC EAFs. During the liquid period, the impact of different factors is estimated with the help of the similarity criteria. The algorithm of numerical modeling of proceeding processes by standard software packages is developed. The numerical modeling for the working period of DC EAF with differe
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