聚丙烯多区反应器阻隔液棒断裂失效分析

FRACTURE FAILURE ANALYSIS OF BARRIER FLUID BAR FOR POLYPROPYLENE REACTOR

通过对某聚丙烯反应器阻隔液棒断裂失效试样的化学成分分析、力学性能测试、金相检验以及断裂宏微观形貌观察,全面研究了该阻隔液棒的失效原因及改进措施。试验结果表明:阻隔液管的碳含量偏高,断后伸长率偏低;阻隔液棒的失效,是在自重、流体诱导振动、焊接残余应力的联合作用下所形成的多源性疲劳断裂;为预防阻隔液棒的破坏事故,一方面,可以根据其固有振动疲劳特性,选择韧塑性较好的材料;另一方面,改进结构以降低截面突变位置的应力集中。此外,支承结构方面,增大接触面积、减小支承间距,进而增加支承刚度亦有助于避免类似断裂事故的再次发生。

This paper makes a comprehensive study on the causes for the fracture failure of a barrier fluid bar in the polypropylene reactor and the improvement measures through chemical composition analysis,mechanical performance testing,metallographic examination and fracture morphology observation of the fracture failure sample of the barrier fluid bar.The experimental results show that the carbon content in the barrier fluid pipe is higher compared to the standard value and its elongation is lower after fracture;the failure of the barrier fluid bar is fatigue fracture of multiple sources produced by the joint action of the dead weight,fluid-induced vibration and welding residual stress.In order to prevent destroy accident of barrier fluid bar,on one hand,the materials with good plasticity and ductility shall be chosen,on the other hand,the structure of the barrier fluid bar shall be improved to reduce the stress concentration caused by the abrupt change of cross-section.In addition,increasing the contact area,reducing the distance between the supports and thus increasing the stiffness would also help to avoid the occurrence of similar rupture accidents.