| The DC electric arc furnace is gradually replacing the AC electric arc furnace as the smelting equipment used in the industrial silicon production process.During the smelting process,a variety of physical changes and chemical reaction processes are involved in the furnace.The environment is very harsh,and the experimental monitoring is difficult and the cycle is long.The use of numerical simulation methods can effectively solve the problems in the experiment,efficiently and in-depth study of various physical phenomena in the industrial silicon smelting process furnace,and further deepen the understanding of the arc starting,partial arc and smelting process of the DC electric arc furnace.The change law of the DC arc shape and the heat transfer process in the electric arc furnace have certain practical guiding significance.Based on the theory of magnetohydrodynamics(MHD),this paper established a flow-heat transfer-electromagnetic coupling model of industrial silicon smelting equipmentsingle-electrode DC electric arc furnace,and studied the distribution of temperature field,flow field and electromagnetic field in the furnace during arc starting.And the influence of arc length and arc input current parameters on heat transfer in the furnace.Electric arc furnaces generally have a multi-electrode structure.Based on the basic model,a multi-electrode arc flow-heat transfer-electromagnetic coupling model is further established.Starting from the two-dimensional model,a two-dimensional twoelectrode electric arc furnace model is established,and then a three-dimensional twoelectrode model is further established,The effects of multi-electrode arc interaction,electrode spacing and input current mismatch on arc instability and heat transfer process in the furnace were studied.The simulation results of the single-electrode arc starting process show that when the input current is 2160 A,the maximum arc temperature reaches 20000 K,and the maximum jet velocity reaches 1600m/s;the jet form of the arc from the cathode to the anode presents asymmetrical and unstable phenomenon of spiral deflection.The temperature field and flow field distribution changes drastically in time and space,which are not available in the two-dimensional axisymmetric DC arc model.The reduction of the arc length makes the arc column more compact and localized,and the degree of turbulence is reduced,which is beneficial to the arc starting of the electric arc furnace.The greater the input current of the arc furnace,the greater the peak velocity of the arc jet,and the more concentrated the jet.At the same time,the arc column has a wider high temperature area,which strengthens the heat transfer in the furnace.The simulation results of the multi-electrode interaction show that the interaction between the arcs in the multi-arc system is deflected,and the mutual attraction further strengthens the heat transfer process.The high-temperature region is obviously wider,but the arc becomes more unstable.When the electrode distance is reduced,the arc stability increases,and the arcs merge into a larger jet column;when the electrode distance is increased,the arc interaction is not obvious,the arc stability is weakened,the arcs are separated from each other,and the flow field is abnormally turbulent.The deflection of the low-current arc is more serious than that under the higher current.The low-current arc column has undergone a transition from steady state to dynamic behavior,and the temperature field distribution under symmetrical current conditions is more uniform.In the case of multiple arcs attracting each other,reducing the distance between the electrodes is beneficial to the stability of the arc,strengthens the heat transfer effect in the furnace,and provides a certain basis for the design of the electric arc furnace;the symmetrical distribution of the input current can make the furnace The temperature is uniformly distributed,and the symmetrical distribution of current is necessary in the actual production process. |
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