Aiming at the corrosion problem inside air cooler at the top of fractionator in 200 Mt/a FCC unit in Yan'an refinery, on-site sampling and testing were carried out, and then simulated solution was prepared, and influence of chloride ions on the corrosion was studied by taking 10#steel, 20#steel and 304 type stainless steel as the experimental materials. The polarization curves and electrochemical impedance analysis show that the corrosion mechanism of chloride ion on 10# steel and 20# steel is the same. With the addition of chloride ions, the pitting corrosion will occur, and the corrosion rate will be increased when the ion concentration increases. With the increase of chloride concentration, pitting corrosion potential drop of 304 type stainless steel is not obvious, and the passive film becomes unstable. In contrast, the corrosion resistance of 304 type stainless steel is better than that of 10# steel, the corrosion resistance of 10# steel is better than that of 20# steel, but 10# steel is more sensitive to chloride ion change.%针对延安炼油厂年产量200万t催化裂化装置分馏塔顶空冷器内侧腐蚀问题,进行现场取样检测,配制模拟溶液,研究氯离子单一因素的变化对腐蚀结果的影响,选用了空冷管束常用的10钢、20钢和304不锈钢三种材料进行腐蚀试验.通过对试验的极化曲线和电化学阻抗的分析,得到氯离子对10#钢和20#钢的腐蚀机理相同;三种材料都会随着氯离子的加入,出现局部腐蚀点蚀,且随着氯离子浓度的增大都有腐蚀加剧的趋势;304钢随着氯离子浓度的变大,点蚀电位下降不明显,钝化膜变的不稳定.综合对比,304钢抗腐蚀性表现优于10#钢,10#钢优于20#钢,但10#钢对于氯离子变化更敏感.
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