脱硫贫胺液冷却器开裂机理探讨

Analysis of Mechanisms of Crackings in Methyl Diethanol Amine( MDEA) Coolers

某炼油厂脱硫装置溶剂再生单元的甲基二乙醇胺(MDEA)贫胺液冷却器出现焊缝部位严重开裂,通过外观、拉伸、冲击、金相、化学、微观和能谱分析,以及对工艺操作条件进行数据跟踪,发现16MnR壳体焊缝金属冲击韧性下降明显,断口形貌特征为块状疏松物质,主要成分为铁的氧化物;对工艺运行数据分析,发现总体上贫液的运行数据是正常的,偶尔有超标现象发生。通过对腐蚀机理进行分析,得出了焊缝部位严重开裂是碱应力腐蚀开裂(ASCC)引起的。提出了设备需控制板材质量、整体热处理、工艺降低温度操作等措施和建议。

Severe weld cracks occurred in the lean solvent （MDEA） coolers of the solvent regeneration system of a desulfurization plant. The cracks were analyzed and tested by visual inspection, tensile and impingement tests, metallographic analysis, chemical analysis, fracture microslructure analysis and energy spectrum analysis. The process conditions were tracked, which found that the impact toughness of 16MnR casing weld metal had been significantly reduced, and the fracture morphology was the loose material whose main component is iron oxide. The study of process operating data found that the unit is generally in normal operation with only occasional off - specification of lean solvent. The analysis of corrosion mechanisms of weld cracks concluded that the cracks were alkali stress corrosion cracks （ASCC）. Effective measures are recommended such as controlling the quality of the plate, implementing the heat treatment of the entire equipment and reducing the process temperature.