Abstract: Coke drum is the core equipment of delayed coking unit the refinery. With the continuous expansion of the plant scale, the manufacturing technology of heat-resistant steel 1.25Cr0.5MoSi for large-scale coke drum has been promoted. The new forging, as the connection transition section between coke drum cylinder and vertebral body, basically solves the problems of weld crack and cylinder swelling in the transition section of the coke drum. But in recent years, cracks have appeared in the welding seam of cone section of large coke drum of several enterprises. The analysis shows that temperature difference from the normal temperature to 495 ℃ within 20 hours has a strong load impact on the coke drum by alternating thermal stress, the metallographic structure pearlite nodularizing of weld cracks caused by high temperature sulfur-containing oil and gas environment, the temper brittleness characteristics of the material itself, the influence of new energy-saving technology on the coke drum, and the overload production of the unit also accelerates the failure speed of the weld, the interaction of the above factors leads to weld cracking. According to the analysis results, the precautions in the daily operation of the coke drum and some suggestions for maintenance and inspection are put forward.

Key words: coke drum, cone section, weld crack, pearlite nodularizing, temper brittleness, alternating thermal stress

摘要： 焦炭塔是炼油厂延迟焦化装置的核心设备,装置规模的不断扩大,催生了用耐热钢1.25Cr0.5MoSi为材质的大型焦炭塔制造技术。新型锻件作为焦炭塔筒体和椎体连接过渡段,基本解决了焦炭塔过渡段焊缝裂纹和筒体鼓胀变形等问题,但是近年来几家企业的大型焦炭塔在锥段部位的焊缝陆续又出现了裂纹。经分析,焦炭塔在20 h内从常温到495 ℃温差变化对焦炭塔产生强烈的交变热应力载荷冲击,高温含硫油气环境导致的焊缝裂纹部位金相组织珠光体球化,材料本身的回火性脆化特性,装置新型节能技术对焦炭塔的影响,装置超负荷生产加快了焊缝的失效速度,以上多种因素的相互作用,导致了焊缝开裂。提出了焦炭塔日常操作运行中的注意事项,对维护检测工作提出了相关建议。

关键词: 焦炭塔, 锥段, 焊缝裂纹, 珠光体球化, 回火脆性, 交变热应力