【摘要】 在射流流化床与提升管耦合的多段分级转化流化床冷态实验装置上,采用PC6D型颗粒体积分数测量仪,系统研究了提升管中局部固体体积分数径向分布及其轴向发展规律。结果表明:固体体积分数的径向分布为中心区固体体积分数较稀、分布均匀,边壁区为体积分数高、分布陡峭的环核流动结构。提升管中径向颗粒体积分数的轴向发展为:提升管底部,中心区和边壁区固体体积分数随轴向高度的增加而减小,边壁区固体体积分数的减小趋势明显高于中心区;提升管的发展段,边壁区固体体积分数随高度的增加而减小,而中心区固体体积分数几乎不变。提升管所有截面上各径向位置的固体体积分数随表观气速ur,g的减小或固体循环量G S的增加而增大,边壁区固体体积分数受操作条件影响的敏感程度明显高于中心区和过渡区。拟合得到了升管不同径向区域内固体体积分数与截面平均固体体积分数的关系式,误差分析表明该表达式的计算值和实验值吻合较好。更多还原

【Abstract】 The axial and radial solids volume fraction profiles were experimentally investigated by a PC6D fiber-optic probe on nine axial levels in the riser of multi-stage conversion fluidized bed( MFB) which couples jetting fluidized bed with riser cold model apparatus. The experimental results show that the radial solids volume fraction in the riser is dilute and flat in the central region while dense and steep in the wall region. The axial development of radial solids volume fraction is that at the bottom of riser,the solids volume fraction in the center region rapidly decreases while slowly decreases in the wall region; in the developed region,the solids volume fraction rapidly decreases in the center region while the solids volume fraction in the wall region decreases slightly or remains constant along the riser. Both the radial and axial solids volume fractions increase with the decrease of superficial gas velocities and /or the increase of solids volume fraction rates,and the effects of operating conditions on the solids volume fraction in the wall region are greater than those in the center region. An empirical correlation was therefore developed to describe the variation of solids volume fraction in different radial regions with cross-sectional average solids volume fraction,which reveals a favorable agreement between predicted and experimental data by means of error analysis.更多还原