多相流动状态下CO_2分压对X70钢CO_2腐蚀的影响

Effect of CO_2 Partial Pressure on CO_2 Corrosion of X70 Steel at Multiphase Flow

应用自制实验装置,模拟起伏管路段塞流动条件下X70钢CO2腐蚀问题,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,研究了多相流动状态下CO2分压对X70钢CO2腐蚀速率的影响。结果表明,CO2分压对X70钢CO2腐蚀存在正反两方面的影响:随着CO2分压的增加,一方面腐蚀介质酸性增强,加快腐蚀;另一方面,CO2-3的浓度升高,与Mg2+、Ca2+、Fe2+等阳离子在腐蚀挂片表面形成了一层腐蚀产物膜,降低了腐蚀速度;CO2分压对X70钢CO2腐蚀的影响与温度息息相关,随着温度的升高,腐蚀速率达到最高值的CO2分压越来越低,CO2分压对X70钢基体的保护作用大过腐蚀作用的CO2分压越来越低。

The corrosion of X70 steel was simulated at plug flow using the homemade experimental apparatus.The effect of CO2 partial pressure on CO2 corrosion of X70 steel was studied by analysis of the bolt surface morphology,corrosion rate,and online coupon corrosion situation using electronic microscope,bolt and electrochemical corrosion online monitoring.The results showed there was two effect of the pros and cons on of CO2 partial pressure on CO2 corrosion of X70 steel.On the one hand,enhances of corrosive medium acidity accelerated the corrosion rate,on the other hand,CO2-3combined with Mg2＋,Ca2＋and Fe2＋and a layer of corrosion product film was formed which reduced the corrosion rate when concentration of CO2-3increased.The effect of CO2 partial pressure on CO2 corrosion of X70 steel was closely related to the temperature.The CO2 partial pressure reduced when the corrosion rate achieved the highest point and protection role was greater than corrosion role for X70 steel substrate with the increasing of temperature.