以玻璃微珠、流化床裂化催化剂颗粒、褐煤和聚氯乙烯颗粒为实验物料,开展粉体流动性表征与料仓下料实验。研究发现,不同粉体的流动性差异较大,相应的料仓重力下料结果也不同;实验所用粉体的下料流率远低于传统Brown and Richards模型的...以玻璃微珠、流化床裂化催化剂颗粒、褐煤和聚氯乙烯颗粒为实验物料,开展粉体流动性表征与料仓下料实验。研究发现,不同粉体的流动性差异较大,相应的料仓重力下料结果也不同;实验所用粉体的下料流率远低于传统Brown and Richards模型的预测值。分析表明,颗粒间相互作用导致的粉体黏附团聚是阻碍细颗粒粉体下料流动的主要原因。基于上述分析,利用剪切测试结合摩尔应力圆理论获得床层拉伸应力,并借助Rumpf方程构建的颗粒间相互作用与粉体床层应力之间的模型来获得不同粉体的颗粒间作用力;继而采用Bond数对粉体床层空隙率进行修正,揭示了颗粒间相互作用对粉体床层结构的影响,并在此基础上建立了粉体下料流率预测模型。新建立的耦合颗粒间作用力的粉体流率模型,有效改善了传统模型对细颗粒粉体流率预测值偏高的弊端,显著降低了流率预测偏差。展开更多
Local slip velocity is an important factor in mass,momentum and heat transfer of riser reactors.Based on the EMMS model, the qualitative and quantitative analysis is made for local slip velocity and its components (th...Local slip velocity is an important factor in mass,momentum and heat transfer of riser reactors.Based on the EMMS model, the qualitative and quantitative analysis is made for local slip velocity and its components (the slip velocity in the dense phase (cluster), the slip velocity in the dilute phase and the slip velocity between dense phase and dilute phase).It is found that the slip velocity between dense phase and dilute phase makes the most contribution to the local slip velocity and clusters lead to the high local slip velocity, from which the correlation of local slip velocity with local voidage is derived.Using this correlation, the local gas-solids slip velocities in gas-solids up-risers are predicted.Calculation results are well consistent with experimental data. Furthermore, the effects of operating conditions on local slip velocities are discussed. It is concluded that local slip velocity increases with the increase of solids circulating rate and decreases with the increase of superficial gas velocity.展开更多
文摘以玻璃微珠、流化床裂化催化剂颗粒、褐煤和聚氯乙烯颗粒为实验物料,开展粉体流动性表征与料仓下料实验。研究发现,不同粉体的流动性差异较大,相应的料仓重力下料结果也不同;实验所用粉体的下料流率远低于传统Brown and Richards模型的预测值。分析表明,颗粒间相互作用导致的粉体黏附团聚是阻碍细颗粒粉体下料流动的主要原因。基于上述分析,利用剪切测试结合摩尔应力圆理论获得床层拉伸应力,并借助Rumpf方程构建的颗粒间相互作用与粉体床层应力之间的模型来获得不同粉体的颗粒间作用力;继而采用Bond数对粉体床层空隙率进行修正,揭示了颗粒间相互作用对粉体床层结构的影响,并在此基础上建立了粉体下料流率预测模型。新建立的耦合颗粒间作用力的粉体流率模型,有效改善了传统模型对细颗粒粉体流率预测值偏高的弊端,显著降低了流率预测偏差。
基金国家重点基础研究发展规划 (No G19990 2 2 10 3)国家自然科学基金 (No 2 99360 90 )资助项目~~
文摘Local slip velocity is an important factor in mass,momentum and heat transfer of riser reactors.Based on the EMMS model, the qualitative and quantitative analysis is made for local slip velocity and its components (the slip velocity in the dense phase (cluster), the slip velocity in the dilute phase and the slip velocity between dense phase and dilute phase).It is found that the slip velocity between dense phase and dilute phase makes the most contribution to the local slip velocity and clusters lead to the high local slip velocity, from which the correlation of local slip velocity with local voidage is derived.Using this correlation, the local gas-solids slip velocities in gas-solids up-risers are predicted.Calculation results are well consistent with experimental data. Furthermore, the effects of operating conditions on local slip velocities are discussed. It is concluded that local slip velocity increases with the increase of solids circulating rate and decreases with the increase of superficial gas velocity.
