Abstract:

Through the measurement of high-speed cameras and pressure sensors, the generation mechanism of pulse flow, the influence of the number of sieve plates, the propagation velocity and frequency of liquid phase pulses have been systematically studied. It is found that the pulsed flow is a dynamic process in which the liquid phase fluctuation is superimposed and amplified in the downward propagation due to the action of gravity and airflow drag force, and is related to the flow rate of gas and liquid and the number of sieve plates. A minimum liquid flow rate is required for the pulse flow under a certain range of gas flow, and the increase of liquid flow can promote the generation of local pulses and increase the liquid pulse velocity and frequency. Above the minimum liquid flow rate, the disturbance of gas phase is enhanced with the increase of gas volume, and the local pulse is more likely to be generated, which leads to the increase of pulse propagation velocity and frequency. With the further increase of gas flow, the liquid pulse will be gradually dispersed, resulting in the decrease of pulse velocity and pulse frequency. Increasing the number of sieve plates is beneficial to increase the intensity of the pulse flow, which leads to a wider range of pulse flow. Pulse flow will not occur when the number of sieve plates is less than three. Finally, based on the analysis of the experimental results, the predictive correlations of pulse velocity and frequency were proposed.

Key words: sieve plate packing, pulse flow pattern, pulse characteristics, gas-liquid flow, hydrodynamics, flow

摘要：

通过高速摄像机和压力传感器测量，对脉冲流的产生机理、筛板数的影响、液相脉冲传播速度及频率进行了系统的研究。实验发现：脉冲流是重力和气流曳力作用下，孔口液相波动在向下传播过程中被叠加放大的动力学过程，且与气、液流量及筛板数密切相关；一定气量下，脉冲流的产生需要有一个最小（临界）液相流量，且增加液量可促进局部脉冲的产生，并使液相脉冲传播速度与频率均增大；临界液量之上，增大气量，气相的扰动作用增强，局部脉冲越容易产生，从而导致脉冲传播速度与频率均增大；进一步增大气量，液相脉冲会被逐渐分散，导致脉冲传播速度与脉冲频率均减小。增加筛板数，有利于增强脉冲流强度，从而导致脉冲流范围变宽，当筛板数少于三块时不会出现脉冲流。最后，基于实验结果分析，提出了脉冲传播速度及频率的预测关联式。

关键词: 堆叠筛板填料, 脉冲流型, 脉冲特性, 气液两相流, 流体动力学, 流动