Through analyzing the compositions and dew points of FCC flue gases, and the sulfur and nitrogen contents in feeds and on catalysts, it was pointed out that the operating condition was the key factor affecting the flue gas composition and dew point. Excess oxygen in the flue gases of single-stage regenerator and the 2nd stage of two-stage regenerator was high, which caused SO3 forming and resulted in high dew points (120-150 ℃), so stress corrosion and stress fracture were occurred easily. The excess oxygen in the 1st stage was low and free of SO3, and the flue gas also contained significant amount of NH3, so its dew point was low (50-65 ℃), and stress corrosion and stress fracture were hardly occurred. There was no remarkable relation between the sulfuritrogen content of the feed and the stress corrosion/fracture occurred in the regenerator. Some suggestions were made to prevent the stress corrosion/fracture.%通过分析已发生和未发生应力腐蚀开裂的催化裂化装置的烟气组分和露点， 以及原料油和催化剂中的硫、 氮含量， 指出操作条件是影响烟气组成和露点的关键因素。单段再生器及两段再生器的二再烟气中过剩氧含量较高， 含有 SO3气体， 故露点较高(120～150 ℃)， 易发生应力腐蚀开裂；两段再生器的一再烟气中过剩氧含量较低， 不含 SO3而含有大量的 NH3， 故烟气的露点较低(50～65 ℃)， 不易发生应力腐蚀开裂。原料油中硫、 氮含量的高低与设备是否发生应力腐蚀开裂无明显关系。对预防应力腐蚀开裂提出了建议。
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