稠环芳烃在蜡油加氢裂化装置分布规律研究

Research on the distribution of polycyclic aromatic hydrocarbons in wax oil hydrocracking unit

加氢裂化尾油用作蒸汽裂解制乙烯原料的比例在逐渐增大,其性能通常用芳烃指数(BMCI值)来表征。稠环芳烃(PAHs)广泛存在于重质油中,通常尾油中的PAHs质量分数不大于70 mg/g。蒽及三亚苯等三环或四环芳烃在气相中比例基本不超过10%,而晕苯及卵苯等七环及以上芳烃几乎全部富集在油相中。97%(质量分数,下同)的三亚苯富集在煤油中,99%的蒽富集在柴油中,67%的卵苯富集在柴油中,99%的晕苯富集在尾油中。通过提高汽提蒸汽量使塔内油气分压变小,该措施对芳环数较少的PAHs汽提效果比较明显,对晕苯等PAHs汽提效果有限。

The proportion of hydrocracked tail oil used as raw material for steam cracking to ethylene is gradually increasing.Its performance is usually characterized by BMCI value.Polycyclic aromatic hydrocarbons(PAHs)are widely present in heavy oils as a major coking precursor.The content of fused aromatic rings in tail oil usually is not more than 70 mg/g.The proportion of anthracene,triphenylene and other tricyclic or tetracyclic aromatic hydrocarbons in the gas phase is not more than 10%,while heptacyclic and above aromatic hydrocarbons such as coronene and ovalene are almost all enriched in the oil phase.Among them,97%(mass fraction)of trimethylene is enriched in kerosene,99%of anthracene is accumulated in diesel,99%of coronene is almost all in tail oil,67%of ovalene is enriched in diesel oil,and 33%of ovalene is stored in tail oil.The reduction of the oil and gas partial pressure in the tower by increasing the amount of stripped steam has a more obvious effect on PAHs with fewer aromatic rings,and the effect of stripping on PAHs such as coronene is limited.