连续重整干燥系统分离器开裂原因分析及应对措施

针对某炼油厂连续重整催化剂再生系统再生气体干燥器单元M301出口分离器DM301D发生开裂情况,从DM301开裂现场调查、查阅原设计参数、运行期间工艺监测和材料的失效分析四方面入手,查找开裂原因,制定应对措施。其中失效分析以开裂部位材料的金相观察、电镜扫描、能谱分析、材料化学分析为主。在对断口处母材进行电镜观察、能谱分析和材料化学分析时,对断口表面母材分为没有清洗和超声波清洗二种情况进行,最后确定导致DM301开裂的主要原因是氯离子造成的奥氏体不锈钢应力腐蚀开裂。为避免类似开裂的再次发生,对此类连续重整装置干燥器单元出口分离器运行工况进行分析,从设备方面结合国内外工业生产装置的使用经验,总结适合此类工况的材料,并综合相关因素,选择经济方便的碳钢材质,加大设计腐蚀裕量。后续对运行状况进行跟踪观察,确认了选材的合理性、正确性、经济性,对类似工况具有一定的指导性作用。

Analysis of cracking of separator in drying system of CCR and countermeasures

The outlet separator DM301D in the regenerator gas drying system of CCR cracked. The causes of cracking were analyzed by side investigation, checking of original design data, process monitoring in operation and failure analysis. The failure of cracked material was mainly studied by metallographic analysis, scanning electron microscope （SEM） energy dispersion spectrometry （EDS） and electro - chemical analysis. The analysis finally concluded that the main culprit for the cracking of DM301 was the stress corrosion cracking （SCC） of stainless steel under the effect of chlorine ions. In addition, the operating conditions of the outlet separator of the drying system were studied. To prevent the cracking from occurring again, the appropriate carbon steel was selected and the design corrosion allowance was increased based upon commercial operation experience and process conditions. The tracing observation of the operation has confirmed the rationality, correctness and economics of the material selection, which provides a good reference for the similar services.