目前中国的炼油厂换热器多采用碳钢材质，换热器是石化设备中失效最快、损失最严重的设备之一，尤其是水相换热器的腐蚀更为严重。水相介质中通常含有一定量的S2-、Cl-、Ca2+和Mg2+，关于碳钢在含硫介质中的腐蚀行为，国内多数研究方向是应力情况下硫化物引起的应力腐蚀开裂问题，无应力状态下碳钢在含硫介质中的腐蚀行为研究得比较少。本文针对兰州石化某常减压装置换热器管束（主要材质10#碳钢）在使用过程中的腐蚀问题，采用高温高压釜实验和电化学测试方法，研究壳程介质中S2-浓度对10#碳钢在含盐污水中腐蚀行为的影响，利用宏观照片和X 射线衍射仪XRD 表征腐蚀产物的形貌和相结构组成。实验结果表明，在测试区间内，随着腐蚀介质中S2-含量的增加，试样表面生成的FeS 使得碳钢的均匀腐蚀速率逐渐降低，当介质中S2-含量升高到250 mg/L 时，碳钢换热器管束的腐蚀程度由严重腐蚀转变为中度腐蚀，XRD 分析结果显示腐蚀产物为Fe3O4、CaCO3和FeS；同时，当腐蚀介质中S2-含量小于100 mg/L 时，由于介质中侵蚀性Cl-存在，溶液中的Cl-更容易穿过疏松的腐蚀产物膜层到达膜与基体界面处腐蚀基体，使得碳钢表面出现明显的点蚀现象，且介质中S2-含量越低，试样抗点蚀性能越差。
The corrosion of a refinery heat exchanger, especially a water-phase heat exchanger, is a serious issue. The corrosion perforation and scaling of tubes are the main causes for the heat exchanger failure due to the existence of plenty of S2-, Cl-, Ca2+ and Mg2+ in the corrosion medium. Based on the experience of corrosion of refinery heat exchanger tubes (10# carbon steel) in their operation processes, the corrosion behaviors of 10# carbon steel in saline wastewater with different S2-concentrations are investigated by means of the immersion test and the electrochemical methods. The surface photographs and the compositions of corrosion products are taken and determined by digital camera and X-ray diffraction spectrometer. The experiment results indicate that the uniform corrosion rates of 10# steel decrease gradually with the increase of the S2-concentration in the corrosion medium within the scope of the test. The corrosion degree of 10# carbon steel comes down to a moderate corrosion from a heavy corrosion when the S2-concentration in the medium is higher than 250 mg/L. XRD results show that the main compositions of the corrosion products are Fe3O4, CaCO3 and FeS. Meanwhile, Cl- in the corrosion medium can penetrate the corrosion product to accumulate and produce the pit corrosion on the surface of 10# carbon steel because of the existence of Cl-when the S2-concentration in the medium was less than 100 mg/L. And the pitting corrosion resistance becomes worse with the decrease of the S2-concentration.
[1] 曾勇. 8Mt/a常减压蒸馏装置冷换设备选材分析[J]. 石油化工腐蚀与 防护, 2006, 23(4): 57-60. Zeng Yong. Material selection for the heat exchange equipment of 160, 000 BPSD atmospheric-vacuum distillation unit[J]. Corrosion & Protection in Petrochemical Industry, 2006, 23(4): 57-60.
[2] 谷其发, 李文戈. 炼油厂设备腐蚀与防护图解[M]. 北京: 中国石化出 版社, 2000. Gu Qifa, Li Wenge. Diagram of refinery equipment corrosion and protection[M]. Beijing: China Petrochemical Press, 2000.
[3] 李奇峰. 常减压装置塔顶换热器管束腐蚀及选材[J]. 石油化工腐蚀与 防护, 2009, 26(3): 41-42. Li Qifeng. Corrosion of atmospheric-vacuum distillation unit's overhead heat exchanger tube bundles and material selection[J]. Corrosion & Protection in Petrochemical Industry, 2009, 26(3): 41-42.
[4] Turissini R L, Bruno T V, Dahlberg E P, et al. Prevent corrosion failures in plate heat exchangers[J]. Chemical Engineering Progress, 1997, 93(9): 44-50.
[5] 刘建华. 高硫高酸原油常减压装置的腐蚀与防护[J]. 石油化工腐蚀与 防护, 2007, 24(3): 36-39. Liu Jianhua. Corrosion of atmospheric-vacuum distillation unit processing high-sulfur high-acidity crude oils and protection[J]. Corrosion & Protection in Petrochemical Industry, 2007, 24(3): 36-39.
[6] 宋义全, 武俊伟, 李晓刚, 等. 常压塔顶316L不锈钢换热器管束的腐 蚀失效分析[J]. 腐蚀科学与防护技术, 2004, 16(5): 334-336. Song Yiquan, Wu Junwei, Li Xiaogang, et al. Corrosion of heat exchanger pipe bundle of 316L stainless steel for distillation tower overhead[J]. Corrosion Science and Protection Technology, 2004, 16(5): 334-336.
[7] Polley G T, Wilson D I, Yeap B L, et al. Use of crude oil fouling threshold data in heat exchanger design[J]. Applied Thermal Engineering, 2002, 22(7): 763-776.
[8] 崔正丹. 炼油厂水相换热器碳钢材料的腐蚀与防护措施研究[D]. 长 沙: 湖南大学, 2009. Cui Zhengdan, Corrosion and anti-corrosion of carbon steel of the aqueous phase heat-exchanger in refineries [D]. Changsha: Hunan University, 2009.
[9] Starosvetskya D, Armonb R, Yahaloma J, et al. Pitting corrosion of carbon steel caused by iron bacteria[J]. International Biodeterioration & Biodegration, 2001, 47(2): 79-87.
[10] 徐秀清, 魏丹, 俞莹滢, 等. Cl-浓度对含盐污水中10#碳钢腐蚀性能的 影响[J]. 表面技术, 2013, 42(4): 59-61. Xu Xiuqing, Wei Dan, Yu Yingying, et al. The influence of Clconcentration on the corrosion resistance of refinery heat exchanger tubes[J]. Surface Technology, 2013, 42(4): 59-61.
[11] 曹华珍, 张九渊, 郑国渠, 等. 碳钢在含硫介质中的极化行为[J]. 腐蚀 科学与防护技术, 2002, 23(10): 427-429. Cao Huazhen, Zhang Jiuyuan, Zheng Guoqu, et al. Polarization behavior of carbon steel in sulfur-bearing solution[J]. Corrosion Science and Protection Technology, 2002, 23(10): 427-429.
[12] 冯拉俊, 马小菊, 雷阿利. 硫离子对碳钢腐蚀性的影响[J]. 腐蚀科学 与防护技术, 2006, 18(3): 180-182. Feng Lajun, Ma Xiaoju, Lei Ali. Influence of sulfide on corrosion of carbon steel[J]. Corrosion Science and Protection Technology, 2006, 18 (3): 180-182.
[13] 朱锦伟. 钢制油管防腐蚀涂料[J]. 上海涂料施工与应用, 2000(4): 32-35. Zhu Jinwei. Steel pipe anticorrosion coating[J]. Shanghai Coating Construction and Application, 2000(4): 32-35.
[14] 刘永辉, 张佩芬. 金属腐蚀学原理[M]. 北京: 航空工业出版社, 1993. Liu Yonghui, Zhang Peifen. Principles of metal erosion[M]. Beijing: Aviation Industry Press, 1993.
