气-液两相鼓泡塔反应器液体流速分布的实验研究

用示踪剂电子电极法对气-液两相鼓泡塔反应器液体的轴径向速度进行了测量。测试结果表明,塔中心处的液速最大,靠近塔壁处最小。且当表观气速增大,初始流体流动处于由均匀流型向过渡流型的转变,轴向液体速度在径向的梯度非常小;当表观气速继续增大,平均液体速度有明显的增加,轴向液体速度的径向分布呈线性关系,表明流体的流动进入非均匀流型;进一步增加表观气速,平均液体速度无明显增加。另外,应用3种不同结构的气体分布器考察了其对反应器中心线处轴向液体速度的影响。实验发现,环状气体分布器的反应器底部存在一个回流区。

Study on Distribution of Liquid Velocity for Gas-Liquid Two-Phase Bubble Columns

The local liquid velocities in a gas-liquid two-phase bubble column were measured using electrolyte tracer technique. It was indicated that the profiles of the liquid velocities had a maximum at the centre of the bed, and a minimum near the wall of the bed. With increasing of superficial gas velocities,the liquid flow regime was changed from homogeneous to transitional and radial gradient of axial liquid velocity was rather small. A further increase of superficial gas velocity yielded a significant increase of mean liquid velocity marking the onset of the heterogeneous flow regime, and the radial profile of the axial velocity became linear rather than parabolic. Further increase of the superficial gas velocity could not yield an additional increase in mean liquid velocity. A good impression of the liquid velocity over the whole reactor height being influenced by the distributor geometry could be gained from an evaluation of the central axial velocities. It was shown that there was a down-flow region at the bottom of the reactor of ring distributor.