石油学报(石油加工) ›› 2021, Vol. 37 ›› Issue (1): 148-156.doi: 10.3969/j.issn.1001-8719.2021.01.015

• 研究报告 • 上一篇    下一篇

316L不锈钢在污水汽提塔顶循环系统的腐蚀特性

吕文超1, 偶国富2, 刘骁飞2, 许恒晖2   

  1. 1. 江苏航运职业技术学院 轮机工程学院, 江苏 南通, 226010;
    2. 浙江理工大学 流动腐蚀研究所,浙江 杭州 310018
  • 收稿日期:2019-10-21 修回日期:2020-01-04 出版日期:2021-01-25 发布日期:2021-01-12
  • 通讯作者: 吕文超,男,工程师,博士,从事多相流动腐蚀机理与防控研究,E-mail:2008lvwenchao@163.com E-mail:2008lvwenchao@163.com
  • 基金资助:
    国家重点研发计划项目(2017YFF02100403)和国家自然科学基金项目(51806198)资助

Corrosion Characteristics of 316L Stainless Steel in the Top Circulation System of Sewage Stripping Tower

LV Wenchao1, OU Guofu2, LIU Xiaofei2, XU Henghui2   

  1. 1. The School of Marine Engineering, Jiangsu Shipping College, Nantong 226010, China; 2. The Flow Accelerated Corrosion Institution, Zhejiang Sci-Tech University, Hangzhou 310018, China
  • Received:2019-10-21 Revised:2020-01-04 Online:2021-01-25 Published:2021-01-12

摘要: 设计、搭建了循环流动实验装置,模拟污水汽提装置塔顶循环系统腐蚀环境,采用电化学测试方法和表面分析技术,对316L不锈钢(316L SS)在污水介质中的腐蚀行为和特性进行了研究。实验结果表明,316L SS在污水介质中的腐蚀形态为局部点腐蚀,腐蚀表面具有弥散分布的点蚀坑。污水介质中NH4Cl含量和介质流速是影响 316L SS 腐蚀速率的关键因素。当污水介质中NH4Cl质量分数小于4.0%时,腐蚀体系阻抗较大,316L SS的阳极极化曲线表现为典型的溶解、钝化和点蚀过程;当NH4Cl质量分数大于4.0%时,极化曲线不具有明显的钝化区,且此时体系的阻抗半径急剧减小,表明316L SS表面未形成完整的钝化膜,材料耐蚀性降低。当污水中NH4Cl质量分数为4.0%、介质流动速率大于1.0 m/s时,316L SS腐蚀速率急剧升高。

关键词: 污水汽提;316L不锈钢;NH4Cl含量;介质流速;电化学测试;电镜扫描(SEM), 能谱分析(EDS)

Abstract: A circulation loop experimental rig was built to simulate the corrosion environment in the top system of the sewage stripping tower. The corrosion behaviors of 316L stainless steel (316L SS) in the top system of sewage stripping unit were studied by electrochemical test method and surface analysis. Experimental results of scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) show that the corrosion pattern of 316L SS in the top system of sewage medium is local pitting corrosion. The corrosion rate of 316L SS is affected by NH4Cl content in the sewage solution and the medium flowrate. Through the results of polarization resistance, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS), it can be concluded that, when the mass fraction of NH4Cl in the sewage medium is less than 4.0%, the impedance of the corrosion system is large and the anodic polarization curves of 316L SS show typical dissolution, passivation and pitting characteristics. However, when the mass fraction of NH4Cl is greater than 4.0%, the distinct passivation zone can not be found in the polarization curve and the impedance radius decreases sharply, which indicates that the passivation film on 316L SS surface is destroyed and its corrosion resistance reduces. It is found that, when the mass fraction of NH4Cl contained in the sewage is 4.0%, the corrosion rate of 316L SS increases sharply when the medium flow velocity is higher than 1.0 m/s.

Key words: sewage stripping, 316L stainless steel, NH4Cl content, medium flow rate, electrochemical test, scaning electron microscope (SEM); energy disperisve spectrometer(EDS)

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