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为解决某大型石化企业乙烯装置中急冷油/稀释蒸汽换热器列管产生的表面凹陷与穿孔破裂等失效问题,本文采用多种表征测试手段,对列管材质、换热介质、破口形貌等进行了详细的分析和研究。确定了工艺水介质pH值的剧烈波动是造成管子失效的主要原因,而工艺水中因除杂不彻底引入的Cl-则进一步加剧了腐蚀程度。在试验结果及现有点蚀、碱脆理论基础上,首次提出了酸/碱交替腐蚀机理及其四级反应过程。最后根据实际情况,给出了相应的解决方案和预防措施。
In order to solve the failure problems such as surface sag and perforation rupture caused by the quench oil / dilution steam heat exchanger tubes in ethylene plant of a large-scale petrochemical enterprise, a variety of characterization test methods were used in this paper to analyze the material quality, heat transfer medium, Appearance, etc. conducted a detailed analysis and research. It was confirmed that the violent fluctuation of the pH value of the process water medium was the main cause of the tube failure. However, the Cl - in the process water, which was not introduced thoroughly, further aggravated the corrosion. Based on the experimental results and the existing pitting corrosion and alkali-brittle theory, the alternating acid / alkali corrosion mechanism and the four-stage reaction process are proposed for the first time. Finally, according to the actual situation, gives the corresponding solutions and preventive measures.