苯甲酸蒸馏塔内件腐蚀失效分析和防护对策

Failure Analysis and Prevention Measures of the Internals in Benzoic Acid Distillation Column

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 uti- lized to analyze the failed internals （support ring and the downcomer plate） in benzoic acid distil- lation 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 tem- perature.