Abstract: In chemical production processes, many operations such as oxidation and hydrogenation rely on the mass transfer efficiency of stirred tanks in terms of gas dispersion. Therefore, optimizing gas dispersion characteristics is a key issue. This study aimed to investigate the effects of impeller type, impeller position, and operating parameters on gas-liquid dispersion in a stirred tank by means of porous tube aeration, where two typical wide hydrofoil (WH) and half-elliptical disk turbine (HEDT) impellers were used to investigate the influence of impeller position and rotational speed on the gas dispersion. The critical rotational speed for complete gas dispersion, agitation power consumption, and overall gas holdup were clarified. It was found that for both HEDT and WH impellers, the critical Froude number (Fr) decreased significantly with increasing gas flow number (FlG). Under the same gassing rate, the critical complete dispersion Froude number of the HEDT impeller was generally higher than that of WH impeller, and also the agitation power required for complete dispersion was greater. Additionally, relative power demand (RPD) decreased as FlG increased, and this decreasing trend accelerated at higher L/D ratios. At different impeller positions, the relative power demand of the HEDT impeller was higher than that of the WH impeller, indicating that the agitation power of the HEDT impeller was less affected by the gas than the WH impeller. Notably, the impeller installation height had an obvious impact on gas holdup and power consumption. When the ratio of the vertical distance between the impeller center and the upper edge of the porous distributor (L) to the impeller diameter (D) was 0.75, a higher gas holdup and lower power comsuption were observed. This work provides crucial theoretical and data support for optimizing the design of gas-liquid stirred tanks with gas sparging. It holds clear engineering application value for enhancing mass transfer efficiency and energy-saving operation in chemical processes.

Key words: stirred tank, porous tube, distributed gas sparging, gas-liquid dispersion

摘要： 气-液搅拌槽在氧化、加氢等化工过程中具有广泛应用，其气体分散状态直接影响生产效率，而搅拌桨型、桨叶安装高度及进气结构是气液分散的重要影响因素。本工作在具有多孔直管进气结构的气液搅拌槽中考察了宽叶翼型搅拌(WH)桨和半椭圆管涡轮(HEDT)桨的桨叶安装位置和转速等条件对气液分散特性的影响规律。结果表明，多孔直管进气结构可实现较好的气泡分散均匀性，HEDT桨适用于较高转速下的气液分散操作，而WH桨在相对较低的转速下即表现出较好的气液分散效果。对于两种搅拌桨，L/D=0.75均为较优的安装高度。本研究结果可为气-液搅拌槽性能优化和设计提供方法参考，具有显著的实际应用价值。

关键词: 搅拌槽, 多孔管, 分布式进气, 气液分散