Xia Lu, Xiuqing Lu, Kai Yang, Xiaotao Zheng, Shixian Wang
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引用次数: 0
摘要
本文研究了循环液体速度对外循环气举反应器气泡尺寸分布(BSD)和湍流特性的影响。利用粒子图像测速仪(PIV)研究了立管中的瞬时速度和时间平均速度,并利用基于机器学习的数字图像分析技术测量了 BSD。然后通过速度场计算湍流动能(TKE)和能量耗散率(EDR)。结果表明,随着循环液体速度的增加,BSD 的峰值从近 6 mm 快速下降到约 2 mm。液体的径向速度逐渐减小并改变方向,最终再次增大。TKE 先减小后增大。与 BSD 峰值为 2-6 mm 的气泡流相比,BSD 峰值为 2 mm 的气泡流的 TKE 更大。气泡的径向运动对湍流特性有很大影响。这项研究表明,选择适当的循环液速可以减小气泡直径,同时获得更大的 TKE,从而提高外循环气提反应器(EL-ALR)的传质和反应效率。
Experimental study on the effect of circulating liquid velocity on bubble size distribution and turbulence characteristic in an external loop airlift reactor
The influence of circulating liquid velocity on bubble size distribution (BSD) and turbulence characteristics of an external loop airlift reactor was studied in this paper. The instantaneous and time-averaged velocity in the riser were studied using particle image velocimetry (PIV), and BSDs were measured by digital image analysis technique based on machine learning. Then turbulence kinetic energy (TKE) and energy dissipation rate (EDR) were calculated through the velocity field. The results indicate that as the circulating liquid velocity increased, the peak value of BSD rapidly decreased from nearly 6 mm to approximately 2 mm. The radial velocity of the liquid gradually decreased and changed direction, eventually increasing again. TKE first decreased and then increased. Compared with bubble flow with a BSD peak of 2–6 mm, bubble flow with a BSD peak of 2 mm had larger TKE. The radial movement of bubbles had great influence on the turbulence characteristics. This study demonstrates that selecting an appropriate circulating liquid velocity can reduce the diameter of bubbles while obtaining greater TKE, thereby improving the mass transfer and reaction efficiency in external loop airlift reactors (EL-ALR).
期刊介绍:
Asia-Pacific Journal of Chemical Engineering is aimed at capturing current developments and initiatives in chemical engineering related and specialised areas. Publishing six issues each year, the journal showcases innovative technological developments, providing an opportunity for technology transfer and collaboration.
Asia-Pacific Journal of Chemical Engineering will focus particular attention on the key areas of: Process Application (separation, polymer, catalysis, nanotechnology, electrochemistry, nuclear technology); Energy and Environmental Technology (materials for energy storage and conversion, coal gasification, gas liquefaction, air pollution control, water treatment, waste utilization and management, nuclear waste remediation); and Biochemical Engineering (including targeted drug delivery applications).