吹气管长度对脉冲萃取柱柱重瞬间压降信号测量的影响

本文从理论和实验两方面对吹气法测量中吹气管长度的影响问题进行系统研究，主要包括吹气管长度对柱重压力波动幅值测量的影响和对柱重压力波动的相位延迟作用两个方面。结果表明，在吹气管长度不大于17 m时，柱重压力波动幅值的变化可忽略，而大于17 m时，则有明显的衰减，需通过模型计算的衰减系数进行实际波动幅值的计算；吹气管长度对压力波动的相位有明显的延迟作用，延迟时间随吹气管长度的增大而增大，这个延迟作用在压差测量中如果吹气管长度不一致，会对测量结果有很大影响。理论计算的气体流速为吹气杯体积的估算提供了一个重要方法，计算表明，本实验中50 mL的吹气杯可满足吹气法要求。本文的理论与实验结果为吹气法的设计应用提供了基础。

Effect of Tube Length on Measurement of Instantaneous Pressure Drop of Column Weight in Pulsed Extraction Column

The theoretical and experimental study on the purge tube length effect in the air purge method was carried out. Two problems including the effect of the purge tube length on the pressure amplitude and on the pressure phase delay were mainly investigated. The results show that the tube length has little effect on the pressure amplitude when it is no bigger than 17 m. Obvious attenuation is found out when the tube length is bigger than 17 m and the attenuation coefficient calculated by the theoretical model shall be used to calculate the real pressure amplitude. The tube length has obvious delay effect on the pressure wave. The delay time increases with the tube length. The pressure wave delay has big effect in a pressure difference measurement when the lengths of the two purge tubes are not equal. The gas velocity in the purge tube calculated by the theoretical model provides a good method for the evaluation of the purge cup volume. A purge cup with volume of 50 mL could satisfy the requirement of the air purge method. The theoretical and experimental results in this article provide fundamental for the application of the air purge method.