鼓泡塔中浮力驱动环流特征及反应器放大

BUOYANCY - DRIVEN CIRCULATION AND SCALE - UP IN BUBBLE COLUMNS

针对鼓泡塔一维流动模型,应用新分析方法首次给出环流特征参数（如速度转折点、最大Reynolds剪应力及其位置以及最大回流速度点）的具有明确物理含义的理论表达式,并比较了该关系式与既有结果的异同,分析了气含率分布与Reynolds剪应力的相互关系,提出一种基于流体动力学相似的鼓泡塔放大准则,即以所导出的最大Reynolds剪应力作为特征量,若几何尺寸不同的两个塔满足流体动力学相似,则该剪应力近似相等或具有相同的量级,对比分析表明,该准则对直径介于0.14～5.5m的鼓泡塔近似成立。

A new theoretical analysis and corresponding mathematical modeling of the widely used type of one dimensional flow models and related characteristic flow parameters such as reversion point of flow, Reynolds shear stress, reversion flow position, and so on, were presented to detail the buoyancy - driven two - phase turbulence flow structures in bubble columns. Different relations between the said flow parameters and design parameters were obtained and compared with other mathematical modeling results. Based on the above analysis,a scale - up rule of such reactors was derived from hydrodynamic similarity , that is, with the local maximum Reynolds shear as the characteristic force scale , that is estimated by a theoretical relation provided in the present work, two bubble columns with different scales would have the same or approximate flow patterns and velocity distributions when the two columns have the same or approximate maximum Reynolds shear values. The said rule is verified through a comparison of the prediction results with experimental data available in literature, and good agreements were obtained.