Numerical Simulation And Optimization Of Multiphase Flow In The Reduction Furnace Of The Liquid Rich-Lead Slag

ABSTRACT:The reduction furnace of the liquid rich-lead slag is the main equipment of reduction process during directly smelting lead. It is obvious that the multiphase flow process among the high temperature melt, gas mixture and the coal particles has an impact on the operation process. The influences of multiphase flow process affected by the key structures and operating parameters of reduction furnace was investigated, which has important theoretical and practical significance to strengthen the smelting reduction reaction, improve the energy utilization efficiency, promote the direct reduction of high lead slag liquid technology.The reduction process of the rich-lead slag and furnace equipment was studied in the paper. Based on engineering thermodynamics, heat transfer and computational fluid dynamics theory, multiphase flow physical and mathematical model of the rich-lead slag liquid reduction process was constructed for the unsteady numerical simulation. By the comparison of the dimensionless diameter (bubble diameter/spray gun diameter) and the bubble frequency of spray gun root, the result of numerical simulation is agreed well with the water model experiment results, and the reliability of the model is verified.The gas-liquid physical field distribution of two-phase flow process in the reduction furnace and gas-liquid-solid three-phase distribution of pulverized coal particles in the molten pool were researched by numerical simulation. The results show that the overall pressure distribution is distributing as layers in the furnace; Gas phase is mainly concentrated in the melt nearby the region of the gun, with the molten pool gas holdup at a rate of1.2%, the average melt flow velocity of0.05m/s; The splash phenomena is exist in the process of bath agitation, and hang slag area is concentrated at the top wall of the spray gun; the pulverized coal particles injected are mainly distributed in the upper area of the molten pool and flue gas region. The single factor analysis method is used to determine the parameters, such as, the reduction furnace lance angle, the molten pool depth, the spray lance diameter and spacing and so on, for the optimal operating range:the spray lance angle of10°～20°and the molten pool depth of0.8m-l m, the spray lance diameter of40mm～60mm and the lance spacing of0.83～1.04m.The orthogonal experimental scheme design is designed, and the test results were discussed by the method of matrix analysis. The effect of the various factors on the process of liquid flow reduction furnace high lead slag were the spray gun diameter, the spray gun angle, the pool depth, the gun spacing in turn; The optimal conditions obtained by analysis is: C3B1A1D2, that is, with the spray lance diameter of60mm, spraying angle of10°, the molten pool depth of800mm, and spacing of950mm; Compared to standard conditions, the gas holdup optimized molten pool is increased by12.5%, the moving flow velocity in the molten pool increased by9.22%and the turbulent kinetic energy increased by9.89%on average.