【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,采用压力传感器和PV-6型颗粒速度测量仪,对提升管流动结构和边壁层厚度进行了系统研究。结果表明,一定的操作气速下,固体循环量增加使提升管中气固流动状态从稀相气力输送过渡到快速流态化区域。当提升管处于快速流态化区域时,一定固体循环量下,表观气速增加使提升管轴向各个位置的边壁层厚度减小;一定气速下,固体循环量增加使提升管各个截面的边壁层厚度增加,且低气速时提升管各个截面的边壁层厚度随固体循环量增加的程度明显高于高气速时。拟合得到了边壁层厚度与截面平均固体浓度的关系式,较好地预测了快速流态化区域内边壁层厚度随截面平均固体浓度的变化关系,该表达式的计算值和实验值吻合较好。更多还原

【Abstract】 The cold flow behavior and wall layer thickness of a gas riser which couples with a multi-stage jetting fluidized bed were studied experimentally with a pressure transducer and a PV-6 optical fiber probe.The experimental results show that flow in the riser transits from the dilute pneumatic conveying state to the fast fluidization state when the circulating solid increases while keeping a constant gas velocity in the riser.At the fast fluidization state,the wall layer thickness decreases with the increase of the riser gas velocity at a constant solid circulation rate,and it increases with the increase of the solid circulation rate at a constant riser gas velocity.The increase of the wall layer thickness is more prominent at the low gas velocity region.An empirical correlation was finally developed to describe the relationship between the wall layer thickness and the solid concentration at the fast fluidization state.A favorable agreement between the predicted results and experimental data were reached.更多还原