The study of heat-mass transfer characteristics and optimization on electric arc furnace with the novel fence electrode

In this paper, a fence electrode design was proposed to optimize energy allocation in the EAF. The fence electrode includes a cylindrical main electrode (M-electrode) and circular smaller cylindrical assisted electrodes (A-electrodes). Five working parameters affecting the smelting performance were determined afterward, which include the height diameter ratio ψ, electrode immersion ratio χ, main electrode voltage parameter υm, assisted electrode voltage parameter υa, and smelting time parameter τ. Furthermore, the orthogonal analysis method was used to investigate the synergetic mechanism of operating parameters on four indicators. The four indicators consisting of liquid volume fraction β, energy efficiency η, temperature rise index ς, and temperature uniformity index ξ. The optimal fence electrode electric arc furnace (F-EAF) operating parameters were then automatically given by the back propagation (BP) neural network predicting model and non-dominated sorting genetic algorithm II (NSGA-II), and compared with the optimal traditional single electrode electric arc furnace (S-EAF). The fence electrode design was finally verified by industrial experiments. The results show that the fence electrode can effectively homogenize the energy distribution and provide arc heat directly to the side zone in EAF. Increasing A-electrode voltage has a significant advantage in terms of increasing the smelting rate, but it also significantly raises the overall temperature, which is not conducive to smelting safety. In the case of ψ = 0.75 and χ = 0.4, υa increases from 0.1 to 0.3, τmax and ηmax decrease by 34.2 and 8.0%, respectively. By correlation analysis, it can be known that the A-electrode is an important factor for the F-EAF adjustment ability. Compared with the S-EAF, the F-EAF smelting performance is improved significantly. After multi-objective optimization, F-EAF τmax and ςmax reduce by 8.9 and 0.6%, respectively. At the same time, ηmax and ξave have increased by an average of 1.4 and 2.6%, respectively. The industrial experiments reveal that the fence electrode design can not only effectively homogenize the EAF energy supply, but also can overcome the shortcoming of arc deflection, making the smelting process more stable. In conclusion, F-EAF contributes to the EAF smelting performance evaluation, and this new proposal opens up novel ideas for the future development of EAF design.