催化裂化气提水中A_3钢的腐蚀研究

Corrosion of A_3 Steel in FCC Stripper Water

采用电化学测试技术,以实验室制备的高酸原油催化裂化气提水为腐蚀介质,研究了常温条件下该腐蚀介质对A_3钢的腐蚀行为。研究表明,初始阶段A_3钢的噪声电流和噪声电位曲线均无明显波动,随着浸泡时间延长,电化学电流及电位噪声曲线均出现明显波动,此时腐蚀反应显著发生。噪声曲线时域分析表明,腐蚀反应发生后,噪声电阻迅速降低,同时点蚀指数增大,说明A_3钢发生明显腐蚀,且点蚀强烈。动电位极化曲线研究表明,A_3钢的腐蚀电位逐渐负移,同时腐蚀电流增大,未观察到钝化区域,说明A_3钢在试验腐蚀环境中生成的腐蚀产物对金属的进一步腐蚀不具备保护性。在腐蚀介质中对A_3钢片进行了40 h的挂片腐蚀试验,经过失重分析计算得到的腐蚀结果与动电位极化测试的计算结果有较好的吻合。

Electrochemical methods were applied to investigate the corrosion of A3 steel in FCC stripper water prepared in the laboratory. All experiments were conducted under ambient temperature. In the initial stage, there was no obvious fluctuation in potential and current noise signals of A3 steel. With the extension of emersion time, apparent fluctuations of electrochemical noise （ECN） signal and potential noise signal were observed, indicating that serious corrosion has occurred. The analysis of noise curve in respect of time and area demonstrates that, after occurrence of corrosion, the noise resistance falls down and pit corrosion index increases,indicating that obvious corrosion has developed, especially pit corrosion. It is found in the study of the potential polarity curve that, the corrosion potential of A3 steel gradually moves to the negative pole, the corrosion current is increased and no passivafion area is observed. All these explain that the corrosion products of A3 steel produced in the corrosive testing environment provides no protection to steel＇s further corrosion. In the 40 hours＇coupon test of A3 steel in corrosive media,the calculated results of weight - loss analysis fits well with the calculated results of dynamic potential polarity testing.