材料期刊网

目的 研究常减压装置高温原油馏分及塔顶水相中氯离子、硫离子含量对316 L不锈钢和Monel合金(镍基合金)腐蚀的影响. 方法 通过腐蚀挂片实验,获得316 L不锈钢和Monel合金在含不同浓度氯离子和硫离子的水相、油相中的腐蚀速率变化规律. 利用扫描电子显微镜,研究316 L和Monel合金表面腐蚀后的微观形貌,探讨两种离子对316 L不锈钢和Monel合金腐蚀的影响规律. 结果 在酸值较高的脱后原油中,316 L不锈钢和Monel合金的腐蚀速率分别为0 . 0091 ,0 . 0248 mm/a;在酸值较低的常二段馏分中,316 L不锈钢和Monel合金的腐蚀速率分别为0 . 0078 ,0 . 0031 mm/a. 在常二段馏分中,加入600 mg/L氯离子和30 mg/L硫化钠时,316 L不锈钢和Monel合金的腐蚀速率分别为0 . 1755 ,0 . 1707 mm/a.在相同条件的脱后原油中,316L不锈钢的腐蚀速率为0. 0545 mm/a,Monel合金的腐蚀速率为0. 1281 mm/a. 结论 油相中氯离子含量较低时,环烷酸腐蚀占主导因素;而氯离子含量达到较高水平后,氯离子对腐蚀的影响占主导作用. 316 L不锈钢和Monel合金的腐蚀速率都随氯离子含量的增加而增加,并且硫离子的存在对腐蚀也有一定的促进作用. 在塔顶水相中,氯离子和硫离子均对Monel合金腐蚀的影响不大.

Objective To investigate the influences of contents of chloride and sulfur ions on corrosion rates of 316L stainless steel and nickel-based alloy Monel in crude oil fractions and overhead aqueous phase of crude oil unit. Methods The corrosion rates of 316L stainless steel and Monel alloy in aqueous phase and oil phase containing different concentrations of chloride ions and sulfur ions were obtained by corrosion coupon experiment. SEM ( scanning electron microscope) was used to observe the surface microstructure of corroded 316L and Monel alloys. The influence of two kinds of ions on the corrosion of 316L stainless steel and Monel alloy was discussed. Results The corrosion rates of 316L stainless steel and Monel alloy in highly acidic desalted crude oil were 0. 0091 mm/a and 0. 0248 mm/a, respectively. And in weak acidic second fraction, the corrosion rates were 0. 0078 mm/a and 0. 0031 mm/a, respectively. In second fraction, after addition of 600 mg/L of chlorine ion and 30 mg/L of sodium sulfide, the corrosion rates of 316L stainless steel and Monel alloy were 0. 1755mm/a and 0. 1707 mm/a, respectively. Meanwhile, in the de-salted crude oil with the same concentrations of chloride ions and sulfide ions, the corrosion rate of 316L stainless steel was 0. 0545 mm/a and that of Monel alloy was 0. 1281 mm/a. Conclusion The results indicated that the naphthenic acid corrosion was the dominant factor when there was little chloride in oil phase and the chloride corrosion turned into the major factor if the content of chloride in oil was at high levels. The corrosion rates of the 316L stainless and Monel alloy raised with the increase of chloride ion concentration in oil phase. Furthermore, the existence of sulfur ions could accelerate corrosion in oil phase. In contrast, chloride and sulfur ions did not have apparent impact on the corrosion of Monel alloy in aqueous phase.