关键词: 微元体动力学, 非线性化学反应, 对流, 扩散, 多孔介质

Abstract: Considering that the overall rate of a single pellet is co-dominated by intra-particle diffusion and chemical reaction, the overall rate of representative-element volume was derived from that of a single pellet. Then, the convection-diffusion-nonlinear reaction equation was established, and solved numerically. Taking the indirect reduction of iron ores as a case, the mass transfer, reaction and conversion process occuring within one-dimensional fixed bed was discussed. The results show that the size of pellets and convection velocity influence notably reaction and conversion process. Their influence can be measured by the Thiele module and Peclet module respectively. Because the Thiele module depends on L2 positively, and Pe* does on L positively, the length of reactor L is an important factor to influence the performance of reactor itself. The effect of convection on reaction and conversion descends, and gaseous conversion increases with increasing ratio of y/Pe*.

Key words: overall rate of representative-element volume, non-linear chemical reaction, convection, diffusion, porous medium