基于电阻层析成像技术的气升式内循环鼓泡反应器流体力学研究

来源期刊:中南大学学报(自然科学版)2016年第11期

论文作者:靳海波 连以诚 刘鑫 林金芝 杨索和 何广湘

文章页码:3935 - 3940

关键词:气升式内循环反应器;电阻层析成像;气含率;时间序列流动结构

Key words:airlift inner-loop reactor; electrical resistance tomography; gas holdup; flow structure with time series

摘    要:采用电阻层析成像(ERT)技术,对高为1 024 mm、直径为165 mm,导流筒高为590 mm、直径为80 mm的气升式内循环反应器进行流体力学参数的测量。考察表观气速对上升区和下降区内等3个截面处气含率的影响以及反应器内流型的变化情况。研究结果表明:在上升区,气含率随表观气速的变化与普通鼓泡塔情况一样,而在下降区,一部分气泡由于气液湍动被带入下降区;随着表观气速的增加,液体的循环速度逐渐增大,更多的气泡被拖曳到下降区,下降区内气含率增加明显。通过对ERT图像时间序列的叠加,可以清晰得出在上升区低气速下气泡离散式上升,随着表观气速的增加,以气泡群的方式流动且气泡聚并明显,并出现气泡群的摆动;在下降区,随着液体循环速度增加,下降区气液层消失,气含率逐渐增大。

Abstract: The hydrodynamic parameters are studied in an airlift inner-loop reactor (height 1 024 mm, diameter 165 mm) with draft tube (height 590 mm, diameter 80 mm) using electrical resistance tomography (ERT) technology. The influence of gas superficial velocity on gas holdup of three cross sections was presented and the transformation of flow structure was also discussed. The results show that gas holdups in the rise area increased with the increase of the superficial gas velocity. In addition, liquid circulation velocity increases gradually and a part of bubbles drops into down-comer zone due to the gas-liquid turbulent with the increase of superficial gas velocity, and the gas holdup in down-comer zone increases significantly. Moreover, the transformation of flow structure in the reactor can be seen clearly with the result of composition of ERT time series images. Bubbles in the rising area increase with the discrete type under the low gas velocity, and the bubble swarms rise with the spiral escalation due to the rising bubble coalescence with the increase of superficial gas velocity. Meanwhile, this technique offers the possibility for noninvasive and nonintrusive visualization of flow fields in the reactor and provides a foundation for the future research.

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