多相流动状态下Cl^-对X70钢CO_2腐蚀的影响

Effect of Cl^- on CO_2 corrosion of X70 steel under multiphase flow state

用自制实验装置模拟起伏管路段塞流动条件下X70钢CO2腐蚀环境,通过电子显微镜、腐蚀挂片以及电化学在线监测等,对挂片表面形貌、腐蚀速率以及挂片在线腐蚀情况进行分析,采用实验与数值仿真研究了多相流动状态下Cl-对X70钢CO2腐蚀速率的影响,结果表明:在较低的Cl-浓度下,Cl-浓度对碳钢均匀腐蚀速率的影响存在一个临界浓度,超过临界浓度,碳钢均匀腐蚀速率大幅升高,继续增加Cl-浓度,对均匀腐蚀速率影响不大;在较高的Cl-浓度下,Cl-浓度对碳钢点蚀的影响也存在一个临界值,低于临界值,碳钢点蚀处在点蚀孔形成与钝化的动态平衡过程,高于临界值,这种平衡被打破。

CO2 corrosion of X70 steel at plug flow was simulated using a homemade experimental apparatus. The surface morphology, corrosion rate and corrosion situation online of coupons were studied by electronic microscope and online monitoring of electrochemical corrosion. The effect of Cl^- on CO2 corrosion rate of X70 steel under multiphase flow state was studied by experiment and numerical simulation. The results show that there is a critical Cl^- concentration in low Cl^- concentration range. When Cl^- concentration is higher than that critical value, the uni- form corrosion rate of carbon steel would increase largely. After that, Cl^- concentration continues to increase, there is a little of effect on the uniform corrosion rate of carbon steel. There is also a critical C1 concentration in high Cl^- concentration range. The pitting of carbon steel is under dynamic equilibrium of formation and passivation of pitting holes if Cl^-concentration is lower than the critical value. If Cl^- concentration is higher than the critical value, the balance would be broken.