三效连续蒸发结晶装置中TA10换热器的失效分析  

Failure Analysis of TA10 Heat Exchangers in the Three-effect Continuous Evaporation and Crystallization Device

作　　者：陈兵[1] 阮英浩 姜楠 

机构地区：[1]西安石油大学机械工程学院,西安710065 [2]中国石油长庆石化分公司,陕西咸阳712000

出　　处：《表面技术》2016年第6期180-185,共6页Surface Technology

摘　　要：目的针对国内某化工厂氯化铝生产线上三效连续蒸发装置中换热器发生的换热管束泄漏事故,进行相应的失效分析,找出其原因,以避免相似的腐蚀失效事故再次发生。方法采用宏观检测方法确定发生腐蚀的位置及腐蚀的宏观形貌,由全浸试验确定TA10合金在管、壳程工况下的耐蚀性,通过电镜扫描观察表面腐蚀的微观形貌,最后借助能谱分析和X射线衍射的方法确定腐蚀产物的成分。结果换热器中挡流板被腐蚀,其表面金属发生大面积不规则剥落,换热管束外侧发生严重腐蚀,金属大面积剥落,管程出口处只有焊缝处发生明显腐蚀。TA10合金在管程工况下不会发生腐蚀,而在壳程工况下,会发生较为严重的腐蚀,腐蚀表面呈现出多层状结构,且表面形状无规则,生成的腐蚀产物为Ti H2。结论 TA10合金在壳程工况下,并不能达到良好的耐蚀效果,现有工艺条件下,露点的产生使换热管外侧有高浓度盐酸产生,其会和TA10合金发生严重的吸氢反应,从而导致氢致开裂以及吸氢脆化,伴随气体的冲刷,便出现了金属大面积剥落现象,换热管与管板在连接处发生缝隙腐蚀,缝隙内钛作为阳极发生溶解。最后针对性地提出了防腐蚀建议。Objective In order to avoid similar corrosion failure accidents, the failure analysis of the heat exchanger tube bundle leakage occurred in the three-effect continuous evaporation and crystallization device was carried out to find the cause of failure. Methods The macro morphology of corrosion and the location of corrosion were determined by using macro detection method. The corrosion resistance of TA10 alloy in tube and shell was determined by full immersion test. Microscopic morphology of surface corrosion was observed by SEM. Finally, the components of the corrosion products were determined by the methods of EDS and XRD. Results In the heat exchanger, the baffle plate was corroded, and irregular flaking occurred to its metal surface. Severe corrosion occurred outside the tube bundle, and the corrosion of the tube exit only occurred in the Weld line; The corrosion behavior of TA10 alloy did not happen under the condition of the tube pass, but it happened under the condition of the shell pass. The corrosion surface had a multi-layer structure, and the surface shape was irregular, The corrosion product was Ti H2. Conclusion TA10 alloy could not achieve good corrosion resistance in shell side. Under the existing technological conditions, the generation of the dew point led to generation of a high concentration of hydrochloric acid outside the heat exchanger tube, which would react with the TA10 alloy resulting in severe hydrogen absorption and consequently hydrogen induced cracking and absorbing hydrogen embrittlement. With the erosion of gas, a large area of metal peeling phenomenon appeared. The crevice corrosion occurred in the connecting place of the heat exchange tube and the tube plate, and Titanium was dissolved as an anode in the crevice. Finally, some suggestions were put forward to prevent corrosion.

关 键 词：换热器 腐蚀 失效分析 TA10 全浸试验 能谱分析 X射线衍射 

分 类 号：TG172[金属学及工艺—金属表面处理]