Abstract:

Detecting impurities of droplets in natural gas pipelines is challenging, and conventional off-line detection methods suffer from serious lag. In response, a two-parameter on-line measurement method of droplet concentration based on microwave resonance principle was studied. The simulation model of microwave resonance measurement sensor was established by COMSOL numerical simulation. Through parametric scanning, it is determined that with the diameter of the resonant probe R_C of 6mm, the maximum electric field intensity in the center area of the measurement pipeline could reach 14100V/m, and the average current density j_avg(x) was 1015.48. The maximum current density deviation I_max(x) was 0.95, indicating that the microwave resonant measurement sensor has reached the optimal structure parameter. The influence of droplet concentration changes on the microwave resonance measurement system was also studied. Experimental results showed that the method aligned well with the off-line weighing method. The shift of resonant frequency and the effective increment of response amplitude of the sensor were sensitive to the change of droplet concentration and showed a linear correlation trend. The repetition rate of the sensor fluctuated around 0.25%, demonstrating the good stability of the microwave resonance method. This research provides a new perspective and guidance for the on-line measurement of droplet concentrations in high pressure natural gas pipelines.

Key words: liquid drop, microwave measurement, multiphase flow, natural gas, optimal design, simulation

摘要：

针对天然气管道内液滴杂质难以直接检测，常规离线检测方法滞后性严重的问题。本文研究了基于微波谐振原理的液滴浓度双参数在线测量方法，利用COMSOL数值模拟建立了微波谐振测量传感器模型，通过参数化扫描确定了当谐振探针直径R_C=6mm时，传感器测量管道中心区域的电场强度最大值可达14100V/m，电流密度平均值 j_avg(x)为1015.48，电流密度最大偏差 I_max(x)为0.95，表明微波谐振测量传感器达到最优结构参数。开展了液滴浓度变化对微波谐振测量传感器影响的实验。实验结果表明，该方法与离线称重法具有良好的一致性。传感器谐振频率偏移变化量和响应幅值有效增量对液滴浓度变化敏感，并呈线性相关趋势。传感器重复率在0.25%左右波动，展现了微波谐振方法良好的稳定性。这将为高压天然气管道内液滴浓度在线测量提供一种新的指导和研究思路。

关键词: 液滴, 微波测量, 多相流, 天然气, 优化设计, 模拟