机动管线气顶排空过程持液率特性的实验研究

摘要

根据钢质机动管线的结构特点，利用空气和水具有不同介电常数的性质，设计制作了双丝电容探针持液率检测装置，并用该装置对排空过程中管内的持液率进行了实测。实验发现，双丝电容探针对钢制机动管线的持液率变化敏感，可用于管线截面持液率的测量，并可通过持液率判断排空过程的主要流型。另外，管内的持液率与排气量和气压力密切相关，排气量越大，管内越容易形成段塞，且段塞内部的持液率较低，管内的平均含气率较高。相反，排气压力越大，管内出现段塞的频率和数量越少，且段塞内部的持液率较高，说明较大的排气压力可以提高管内的平均持液率，有利于接力泵的连续工作，提高排空速度。%According to the structure of the steel mobile pipeline,a suit of liquid holdup de-tecting device with two capacitance probes is designed and manufactured based on the different permittivity values between the water and the gas.The device was applied to measure the liquid-holdup during mobile pipeline draining.Some results are found.First,the device is sensitive to the variation of liquid-holdup,so it can be used to measure the liquid-holdup during the draining online continuously,and the gas-liquid two phase flow pattern could also be j udged by analyzing the liquid holdup variation.In addition,the liquid-holdup in the draining process is closely related to the gas pressure and flow rate.The higher the flow rate is,the more likely the slug flow occurs,the liquid-holdup is relatively low,and the gas percentage in the pipe is relatively high. On the contrary,the higher the pressure is,the lower the frequency and quantity of the slug flow occurrence are,and the liquid-holdup in the slug flow is relatively high.It shows that high pres-sure can increase the average liquid-holdup of the pipe,which is beneficial for keeping the pump working continuously and saving the time of draining.