多级鼓泡塔内液体速度分布的实验研究

Experimental study on liquid velocity distribution in multi-stage bubble column

液体循环流动是多级鼓泡塔重要流体力学特征之一,文中在内径为282 mm,高2 000 mm的鼓泡塔内,采用不同类型的筛板将普通鼓泡塔分割成双级气液鼓泡塔。采用Pavlov管测液速的方法考察了不同筛板、不同表观气速下该鼓泡塔中上下二侧的液体速度分布。根据实验结果得出了液体速度在塔中心处最大,且与表观气速有关,随着表观气速的增大而增大;气液鼓泡塔内液速分布呈半抛物线状,在量纲一径向位置0.7左右处,液体速度方向发生改变;加入筛板后,径向速度区发生改变,转折点的位置与筛板的类型有关;同时筛板的加入对鼓泡塔的湍流会有一定程度的抑制,筛板对鼓泡塔上侧液速径向分布的影响明显大于对鼓泡塔下侧液速径向分布的影响。

The characteristic of liquid circulation flow is an important feature of hydrodynamics in multi-stage bubble columns.A bubble column of 282 mm in diameter and 2 000 mm in height was selected,and various kinds of sieve plates were introduced to divide a conventional gas-liquid column into a two-stage gas-liquid bubble column.The effects of sieve plate and superficial gas velocity on the liquid velocity distribution in the upper and the lower of the multi-stage gas-liquid bubble column were studied by the method of Pavlov tube.The experimental results show that the maximum liquid velocity appears in the center of the bubble column,and increases with an increase of superficial gas velocity.The curves of liquid velocity distribution are half-parabolic in a gas-liquid bubble column,and liquid velocity direction is changed at around 0.7 of dimensional-one radial direction.Meanwhile,the introduction of sieve plate suppresses the liquid turbulent flow,and affects the inversion point of liquid velocity.Moreover,the value of inversion point changes with the difference of sieve plate structure.The radial distribution of liquid velocity on the upper of sieve plate is significantly greater than that on the lower of sieve plate.