Abstract:

Residence time is a key parameter for the cyclones accompanied by heat and mass transfer or reaction process. The mean residence time of liquid phase in a gas-liquid cyclone was studied in a cold apparatus using the hold-up method. The results showed that the liquid residence times obviously decreased with the increase of the droplets loading, and less decreased with increasing inlet gas velocity. The main reason for the less effect of inlet velocity on the liquid residence time was that the gas-liquid interfacial shear stress was far less than the gravity of liquid film. A new model was developed to estimate the mean residence time of liquid phase in the gas-liquid cyclone based on a force balance on the liquid film. The predicted residence times were in good agreement overall with the measured values. However, the predicted residence times were higher than the measured values within the liquid film Reynolds number Re_l < 1200. The relationship between the model deviation and flow pattern of liquid film was discussed.

Key words: gas-liquid cyclone, separation, liquid phase, residence time, model

摘要：

旋流设备内伴有传热、传质或反应过程时,介质停留时间是其关键参数。在冷模实验装置上,采用持液量法,对气液旋流器内液相平均停留时间进行了研究。结果表明,液相停留时间随入口含液率增大明显降低,随入口气速增大降低较小。气液界面剪切力远小于液相重力是入口气速对液相停留时间影响较小的主要原因。基于液膜受力平衡,建立了气液旋流器内液相平均停留时间模型。模型预测停留时间与实测值总体吻合良好,在液膜Reynolds数Re_l< 1200范围内,模型预测停留时间偏大,讨论了模型预测偏差与液膜流型的关系。

关键词: 气液旋流, 分离, 液相, 停留时间, 模型