流场径向分割对鼓泡塔液相返混特性的影响

Effect of Radial Division of Flow Field on Backmixing of the Liquid Phase in a Bubble Column

在直径为50 cm,总高为550 cm的鼓泡塔中,采用脉冲示踪技术考察了流场径向分割对鼓泡塔内液相返混特性的影响。实验中气液两相分别为空气和水,气相流速为3.0~8.6 cm/s,液相流速为0.30~1.00 cm/s。实验结果表明:在考察条件下,随着表观液速的增加,停留时间分布曲线的拖尾情况得到改善,鼓泡塔内液相返混程度随之减小。而表观气速的增加会加剧鼓泡塔内的液相返混程度,但不如表观液速影响显著。通过与空塔进行对比,发现流场径向分割将液相返混程度降低了22%。最后拟合得到了等效全混釜串联级数关联式,实验值与计算值的偏差在±5%之内。

Based on the method of radial division of flow field,liquid backmixing characteristics were investigated using pulse tracing technique in a bubble column of 50 cm in height and 550 cm in diameter.Air and water were used as the gas and liquid phases.The superficial gas velocity ranged from 3.0 to 8.6 cm/s,while the liquid velocity ranged from 0.30 to 1.00 cm/s.The experimental results showed that each residence time distribution curve demonstrated obvious long tail phenomenon,with the increase of the superficial liquid velocity,the long tail phenomenon was improved,which implied that the degree of liquid backmixing decreased,while the increase of the superficial gas velocity aggravated long tail phenomenon,but it was not as significant as the effect of superficial liquid velocity.By comparing with the hollow bubble column,the improvement of backmixing in the bubble column with radial division was increased by up to 22%.Finally,according to experimental results,the calculation formula for predicting the degree of liquid phase backmixing was obtained,most of the variances of the predicted model were within 5%of their experimental values.