摘要
考虑内扩散和化学反应联合控制时的情况,将单一固体颗粒的综合速率方程推广到微元体,导出了化学反应项的更适用形式,建立了一维对流-扩散-非线性反应数学模型,求出了该模型的数值解,并以铁矿石的间接还原为例,讨论了不同条件下的反应转化进程. 结果表明,颗粒大小、对流是影响反应转化的重要因素,其影响程度可用Thiele数和传质Pe*数衡量. 由于Thiele数y与反应器长度的平方成正比,而传质Pe*与反应器长度成正比,因此反应器长度也是影响其自身性能的重要因素. 当比值y/Pe*增大时,对流作用下降,气体转化率增高.
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*.
出处
《过程工程学报》
EI
CAS
CSCD
北大核心
2004年第6期490-495,共6页
The Chinese Journal of Process Engineering
基金
国家自然科学基金重点资助项目(编号:50136020)
教育部重点资助项目(编号:01056)
关键词
微元体动力学
线性化学反应
对流
扩散
多孔介质
overall rate of representative-element volume
non-linear chemical reaction
convection
diffusion
porous medium
