乙烯裂解炉汽包接管裂纹产生原因分析及处理

Cause analysis and treatment of cracks of steam drum nozzle of ethylene cracking furnace

某石化公司乙烯裂解炉汽包首次检验时发现汽包46处接管焊缝存在33条裂纹。对汽包接管裂纹处进行宏观检查、硬度检测、材质分析、金相检测后,分析接管裂纹产生的原因主要存在于两个方面:一是汽包在制造过程中存在夹渣、气孔、未熔合等缺陷;二是焊后热处理未能达到理想的效果,焊缝硬度普遍偏高。查询汽包历史运行记录,汽包在投入运行后历次升降压速率均在允许升降压速率范围内。日常运行参数符合设计要求,运行平稳,不存在汽包异常运行产生的影响。通过对裂解炉汽包接管裂纹产生原因分析及裂纹处理方法的总结,提出裂解炉汽包在设计、制造及使用时应注意的事项。同时说明在汽包采购时需对制造厂家提出的技术关键点,从而使裂解炉汽包在投入使用后能安全运行,减少事故隐患的发生。

During the first inspection of the ethylene cracking furnace steam drum in a petrochemical company,33 cracks were found in the welds of the 46 nozzles of the steam drum.After conducting macroscopic inspection,hardness testing,material inspection,and metallographic testing on the crack area of the steam drum nozzles,it was analyzed that the main causes for the occurrence of nozzle cracks lie in two aspects.One is that there are defects such as slag inclusion,blowholes,and lack of fusion in the manufacturing process of the steam drum.Second,the postweld heat treatment did not achieve the desired effect,and the hardness of the weld was generally high.By querying the historical operation records of the steam drum,it was found that the historical pressure rise and fall rates of the steam drum were within the allowable range after the steam drum was put into operation.The daily operating parameters meet the design requirements,the steam drum operates smoothly,and there is no impact caused by abnormal operation of the steam drum.By analyzing the causes of cracks in the nozzles of the cracking furnace steam drum and summarizing the methods for crack treatment,precautions for the design,manufacturing and use of the cracking furnace steam drum were proposed.At the same time,the technical key points proposed by the manufacturer during the procurement of the steam drum were described,in order to ensure the safe operation of the cracking furnace steam drum after it is put into use and reduce the occurrence of accident hazards.