气固反应多孔填充床反应特性的多尺度模拟  

Multi-scale Simulation of the Reactive Characteristics in a Porous Packed Bed with Gas Solid Reactions

作　　者：李明春[1] 张进[1] 吴玉胜[1] 曲彦平[1] 

机构地区：[1]f沈阳工业大学材料科学与工程学院,辽宁沈阳110023

出　　处：《过程工程学报》2013年第5期855-861,共7页The Chinese Journal of Process Engineering

基　　金：国家自然科学基金资助项目(编号:51004071;51164015);工信部重大专项基金资助项目(编号:2012ZX04007-021);辽宁省高等学校优秀人才支持计划资助项目(编号:LJQ2013012)

摘　　要：采用孔隙网络方法建立了颗粒堆积多孔填充床内细观孔隙结构、微观气固反应及宏观传输过程交互耦合的多尺度孔道网络数学模型.以铁矿石间接还原反应为例,计算分析了床层孔道结构特征及颗粒孔结构对传递过程和反应特性的影响规律.结果表明,床层孔道结构特征对流动气体浓度分布和固体物料转化程度影响显著,正态分布的孔结构孔径沿气体流动方向降低时,床层各横截面的平均固体转化率最高,与均匀分布的孔结构计算结果的最大相对误差为29.5%;计算粒级分布范围较窄的颗粒物料时,可采用均匀分布孔结构近似代替实际正态分布孔结构.颗粒孔结构变化引起的转化率最大相对误差随反应进行持续增大,固体转化率为0.5时,颗粒两种孔结构分布的最大相对误差达14.6%.A mathematical model describing the coupled interaction of meso-level pore structure, micro gas-solid chemical reactions and macro transfer processes in a porous packed bed of pellets was established by applying pore network method. Taking the indirect reduction of iron ore as a case, the effects of pore structure pattern of the bed and structure variation of the pellets on the reaction characteristics and transfer in the bed were analyzed. The results show that the pore structure pattern of the bed has obvious effect on the gas concentration felid and the solid fractional conversion rate. For the normal distribution of pore structure, the average solid conversion rate on each cross section of the bed is the highest when the pore size decreases along the direction of gas flow. The maximum relative error between the average solid conversion rate calculated under the conditions of normal and uniform distributions is 29.5%. The actual normal distribution of commonly particulate materials screened narrowly could be approximate with uniform pore size distribution in the calculation. The maximum relative error of the solid conversion rate caused by the pore structure change of solid particles is demonstrated numerically to increase gradually with the reaction time, which reaches 14.6% at the solid conversion rate of 0.5.

关 键 词：多孔填充床 双重孔隙 孔隙网络 气固反应 传递过程 

分 类 号：TF01[冶金工程—冶金物理化学]