苯甲酸蒸馏塔内件腐蚀失效分析和防护对策

摘要

用化学方法、金相显微镜和扫描电镜等对失效后的苯甲酸蒸馏塔塔内件(支撑圈和降液板)进行了分析,结果表明,支撑圈的腐蚀失效模式为严重的P、Si偏析所引起的非敏化态晶间腐蚀造成的晶粒脱落直至穿孔,并伴有晶间和穿晶混合型应力腐蚀开裂.折流板的失效模式是晶间型的应力腐蚀开裂,其拉应力是由温差带来的.最后提出了相应的防护措施.%The chemical, metallurgical microscope and scanning electron microscopy were utilized to analyze the failed internals (support ring and the downcomer plate) in benzoic acid distillation column. The results showed that,the corrosion failure modes of support ring is that grain loss and perforation, due to the severe P, Si segregation caused non-sensitized state intergranular corrosion. Accompanied by intergranular and transgranular stress corrosion cracking. The failure mode of baffles is intergranular stress corrosion cracking. The tensile stress was caused by temperature.