气液固三相逆流化床内气泡行为的实验研究

Experimental Research on Bubble Properties in a Three-phase Inverse Fluidized Bed

应用自行开发的微电导探针技术,对气液固三相逆流化床内的气泡尺寸、气泡上升速度和气泡频率等气泡特性进行了系统研究,考察了床内气泡特性的轴径向分布规律及气液表观速度、液体黏度、固体加入量、颗粒密度及表面活性剂的加入等对气泡特性的影响规律。结果发现,随距离气体分布板的轴向距离增加或由床器壁向中心区域的距离增加,气泡大小和频率都增加,前者分布从窄变宽,后者相反。气泡上升速度与气泡大小的轴径向分布很相似。随固体加入量、颗粒密度增加或水中乙醇的加入,气泡大小和上升速度减小,气泡频率增加;随表观气速增加,三者都增加;随表观液速增加,气泡大小和频率增加,气泡上升速度减小;随液体黏度增加,气泡大小和上升速度增加,气泡频率减小。利用操作变量和流体物性对各气泡特性进行了关联。

Bubble properties such as size,rising velocity and frequency were measured and investigated in a three-phase inverse fluidized bed using a self-made conductivity probe method.The distribution of bubble properties at axial and radial directions and effects of gas and liquid superficial velocity,liquid viscosity,surfactant,solids loading and particle density on bubble properties were determined.Both the bubble size and frequency increase with the axial distance from the gas distributor as well as the radial distance from the wall to the center of the bed increasing.The distribution of bubble size varies from narrow to wide,but opposite to the frequency.The distributions of bubble rising velocity is the same as that of size in the bed.The bubble size and rising velocity decrease and the bubble frequency increases with solids loading,particle density increasing and the addition of ethanol to water,respectively.All the three parameters increase with superficial gas velocity increasing.The bubble size and frequency increase and the bubble rising velocity decrease with superficial liquid velocity increasing,and the bubble size and rising velocity increase and the bubble frequency decreases with liquid viscosity increasing.The values of bubble properties have been well correlated with operating variables and fluid properties.