螺旋流和缓蚀剂协同作用抑制管道冲刷腐蚀

Erosion-corrosion Inhibition of Pipeline under the Synergistic Action of Swirling Flow and Inhibitor

目的探讨螺旋流和缓蚀剂协同作用下的减蚀机理,为开发基于螺旋流的新型冲刷腐蚀控制方法提供理论支撑。方法利用循环式管流冲刷腐蚀试验装置,结合失重测试法、电化学测试法、形貌分析、高速摄像和XPS腐蚀产物分析开展非螺旋流和螺旋流条件下加入水溶性咪唑啉缓蚀剂的管道冲刷腐蚀对比试验研究。结果失重法和电化学测量结果一致表明:在非螺旋流和螺旋流条件下缓蚀剂对20号钢冲刷腐蚀的纯冲刷速率、纯腐蚀速率、腐蚀促进冲刷速率和冲刷促进腐蚀速率均具有有效的抑制作用,但对纯冲刷的缓蚀率均小于对其他三者的缓蚀率。螺旋流和缓蚀剂协同作用对纯冲刷速率、纯腐蚀速率、腐蚀促进冲刷速率和冲刷促进腐蚀速率4个分量的协同缓蚀率均高于缓蚀剂单独作用对4个分量的缓蚀率。其中对冲刷促进腐蚀分量的缓蚀率最高,达到93.75%。高速摄像结果表明扭带产生的螺旋流使砂粒切向速度增大,产生砂粒悬浮效应,改善了砂粒的分布状态。从形貌观察来看,螺旋流和缓蚀剂协同作用下工作电极表面腐蚀产物层最为完整致密且蚀坑数量最少。XPS分析证明了螺旋流和非螺旋流条件下缓蚀剂在电极表面的吸附且螺旋流促进了氧气和缓蚀剂的传质。结论螺旋流产生的砂粒悬浮效应和传质增强效应进一步促进缓蚀剂对纯冲刷速率、纯腐蚀速率、腐蚀促进冲刷速率和冲刷促进腐蚀速率4个分量的抑制,更充分地发挥了缓蚀剂的缓蚀效果。螺旋流与缓蚀剂的协同作用在降低管道冲刷腐蚀方面具有潜在的优势。

The main purpose of this work is to explore the erosion-corrosion reduction mechanism under the synergistic action of swirling flow and inhibitor,and to provide theoretical support for the development of new erosion-corrosion control method based on swirling flow.The comparative experiments research of using inhibitor to inhibit pipeline erosion-corrosion under the conditions of liquid-solid non-swirling flow and swirling flow was carried out to evaluate the potential for the synergistic use of swirling flow and inhibitors by using a circulating loop system in combination with weight loss test,electrochemical test,morphology analysis,high-speed photography and XPS corrosion product analysis.The results of weight loss method and electrochemical measurement show that under non-swirling flow and swirling flow conditions,the inhibitor has an effective inhibitory effect on the four components(pure corrosion,pure erosion,corrosion-enhanced erosion,and erosion-enhanced corrosion)of No.20 steel erosion-corrosion,but the inhibition efficiency for pure erosion is less than the inhibition efficiencies for the other three components.The synergistic inhibition efficiencies of swirling flow and inhibitor on the four components of pure erosion,pure corrosion,corrosion-enhanced erosion and erosion-enhanced corrosion are higher than those of inhibitor on the four components alone.Among them,the synergistic action of swirling flow and inhibitor has the highest inhibition efficiency for erosion-enhanced corrosion component,reaching 93.75%.The results of high-speed camera show that swirling flow generated by the twist tape increases the tangential velocity of the sand and produces the sand particle suspension effect,which improves the distribution of sand particles.It is concluded by microstructural examination that the corrosion product layer on the working electrode surface is the most complete and compact and the number of corrosion pits is the least under the synergistic action of swirling flow and inhibitor.XPS analysis proves that the inhibitor is adsorbed on the electrode surface under swirling flow and non-swirling flow conditions,and swirling flow promotes the mass transfer of dissolved O_(2) and inhibitor to the electrode surface and the adsorption of inhibitor on the electrode surface.The potential fluid dynamics advantages of swirling flow produce the sand suspension effect and mass transfer enhancement effect which facilitate the adsorption of inhibitor on the working electrode surface and acting in conjunction with the oxide film to form a more complete and dense protective corrosion product layer.This furtherly promotes the inhibition on pure corrosion,pure erosion,corrosion-enhanced erosion,and erosion-enhanced corrosion,and give full play to the inhibition effect of the inhibitor.The synergistic action of swirling flow and inhibitor has potential advantages in reducing pipeline erosion-corrosion.