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Bubble and bubble wake characteristics in a gas-liquid-solid fluidized bed.

机译：气液固流化床中的气泡和气泡唤醒特性。

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The hydrodynamics of a gas-liquid-solid fluidized bed were investigated by examining the behavior of bubbles and bubble wakes. Both single bubbles rising in a liquid-solid fluidized bed and individual bubbles in freely-bubbling beds were studied.; A light transmittance technique involving a dual optical fiber probe was used to measure the local solids holdup in a three-dimensional gas-liquid-solid fluidized bed. The bubble could be clearly identified in the same signal, thus permitting the simultaneous determination of the local solids holdup profile in the wake of a single bubble and the rise velocity and chord length of the bubble.; The solid holdup behavior was studied in the wake of single bubbles rising in a liquid-solid fluidized bed for different liquid velocities, particle sizes, and bubble sizes. The wake solids holdup was found to decrease with decreasing mean solids holdup in the bed, to be essentially independent of the bubble Reynolds number over the range investigated in this study (4000 {dollar}<{dollar} Re{dollar}sb{lcub}rm b{rcub}{dollar} {dollar}<{dollar} 8000), and to decrease with increasing particle size.; In freely bubbling beds at low gas holdups ({dollar}varepsilonsb{lcub}rm g{rcub}{dollar} {dollar}<{dollar} 0.03), both the solids holdup in the wake and the particulate phase solids holdup were measured. The light transmittance probe developed for the single bubble system was also used for these measurements. Axial variations in the particulate solids holdup indicated that the relative wake solids holdup increased with axial distance from the distributor. The best agreement between the single bubble measurements and the measurements in the freely bubbling bed occurred in the bubble formation region.; And finally, a simple model of the bubble wake was developed based on equations available in the literature for a spherical vortex to predict both the wake size and the relative wake solids holdup. The predictions showed good agreement with the experimentally observed values.
机译：通过检查气泡和气泡尾流的行为，研究了气液固流化床的流体力学。研究了在液固流化床中上升的单个气泡和在自由起泡床中的单个气泡。涉及双光纤探头的光透射技术用于测量三维气液固流化床中的局部固形物。可以在同一信号中清楚地识别出气泡，从而允许在确定单个气泡之后以及气泡的上升速度和弦长的同时确定局部固体滞留曲线。在单个气泡在液固流化床中上升后，针对不同的液体速度，粒径和气泡大小，研究了固体滞留行为。发现在该研究中，尾料固形物含量随床中平均固形物含量的减少而降低，在本研究范围内基本上与气泡雷诺数无关（4000 {dollar} <{dollar} Re {dollar} sb {lcub} rm b {rcub} {dollar} {dol} <{dollar} 8000），并且随着粒度的增加而降低。在低含气量的自由鼓泡床中，测量了尾流中的固含量和颗粒相固含量。为单气泡系统开发的透光探头也用于这些测量。颗粒固体滞留量的轴向变化表明，相对尾迹固体滞留量随与分配器的轴向距离而增加。单个气泡测量值与自由鼓泡床中的测量值之间的最佳一致性出现在气泡形成区域。最后，根据文献中提供的用于球面涡旋的方程式，开发了一个简单的气泡尾流模型，以预测尾流尺寸和相对尾流固体滞留量。这些预测表明与实验观察值具有很好的一致性。

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