某连续重整装置反应器内构件螺母和螺柱积炭失效分析

Failure analysis of carbon deposition on nuts and studs of reactor internals in a continuous reforming unit

某连续重整装置第一反应器内催化剂输送管连接法兰处存在螺母破裂、螺柱断裂、法兰密封失效、催化剂跑损等问题。经过对失效螺母和螺柱的化验检测、金相检验和电镜分析,发现钢材的晶体内含有大量的碳元素,结合连续重整反应过程的生焦机理,显示出丝状碳在连接缝隙对螺母和螺柱进行了渗碳侵蚀,导致螺母破裂和螺柱断裂。采取措施:氢油摩尔比控制在1.5左右;原料干点小于180℃;硫质量分数尽量接近0.5μg/g,但是不要超过0.5μg/g;做好水氯平衡,循环气中的水质量分数保持在20~30μg/g;减少重整反应系统积炭的生成;升级螺母和螺柱材料等级。通过采取以上措施,保证了连续重整装置的长周期安全平稳运行。

There are some problems in the connecting flange of catalyst delivery pipe in the first reactor of a continuous reforming unit,such as nut fracture,stud fracture,flange seal failure,catalyst loss and so on.The connecting flange of the catalyst delivery pipe in the first reactor of a continuous reforming unit experienced nut breakage,bolt breakage,flange sealing failure,and catalyst loss.After laboratory testing,metallographic examination,and electron microscopy analysis of the failed nut and studs,it was found that there was a large amount of carbon in the crystal of the steel.Combined with the coke formation mechanism of the continuous reforming reaction process,it shown that filamentous carbon has carburized and corroded the nuts and studs in the conection gap,resulting in the fracture of the nut and stud.The following measures should be taken.The hydrogen oil ratio should be controlled at about 1.5.Dry point of raw material is less than 180℃.Sulfur content shall be as close as possible to 0.5μg/g,but not more than 0.5μg/g.Balance the water and chlorine,and keep the water mass fraction in the circulating gas at 20~30μg/g.Reduce the conditions of carbon deposition in the reforming reaction system.Upgrade nut and stud material grades.By taking the above measures,the long-term safe and stable operation of the continuous reforming unit was ensured.