天然气流速对集输管道加注缓蚀剂效能的影响

Influence of the Flow Rate of Natural Gas on the Performance of Corrosion Inhibitor Injection for Gathering and Transportation Pipelines

针对酸性油气田集输系统管材的腐蚀问题,设计了流动天然气状态下加注缓蚀剂的缓蚀效果模拟评价试验装置,采用失重法和扫描电子显微镜研究了天然气在3 m/s和7 m/s条件下,L360碳钢的腐蚀速率和腐蚀形貌,采用电化学分析方法分析了缓蚀剂缓蚀效果随时间变化的规律。结果表明:在CO_2分压为0.8 MPa的湿气管道中加注缓蚀剂后,3 m/s低流速天然气条件下缓蚀剂的缓蚀效率能达到80%以上,腐蚀速率比无缓蚀剂时降低90%以上;7 m/s高流速天然气条件下,缓蚀剂的缓蚀效率下降到70%,腐蚀速率比无缓蚀剂时下降75%以上,随着流速的增加腐蚀速率呈上升趋势,缓蚀效率呈下降趋势。该试验为缓蚀剂的最优加注量和时效性研究提供了参考。

In view of the corrosion problem of gathering and transportation pipelines in acid gas fields,the testing apparatus for the corrosion inhibition effect simulation evaluation of the corrosion inhibitor injection under flow natural gas is designed.The weight-loss method and the scanning electron microscope are employed to study the corrosion rate and the corrosion morphology of L360 carbon steel at the natural gas flow rate of 3 m/s and 7 m/s. The electrochemical method is employed to study the change law of the corrosion inhibition effect of the corrosion inhibitor along with time.The results indicate that for the wet gas pipeline with CO_2 differential pressure of 0.8 MPa,after the corrosion inhibitor is added,the corrosion inhibition efficiency reaches 80% and the corrosion rate declines by 90%compared with that without the corrosion inhibitor when the natural gas flow rate is as slow as 3 m/s,while the corrosion inhibition efficiency declines to 70% and the corrosion rate decreases by 75% when the natural gas flow rate is as fast as 7 m/s,and the corrosion inhibition efficiency decreases and the corrosion rate increases with the increasing flow rate.The test provides references for the study of the optimized injection amount and timeliness of the corrosion inhibitor.