Paraffin is mainly composed of n?alkanes, small amounts of i?alkanes, cycloalkanes, aromatic hydrocarbons and trace amounts of S,N,O compounds. Under the action of ultraviolet light and heat, those compounds containing elements S,N,O,aromatic and unstable elements of alkene aromatic can be oxidated,resulting in a darker color and lower paraffin light stability.In order to explore the reasons for the deterioration of the paraffin light stability,the effects of internal factors such as nitrates,sulfides and oil content on the paraffin light stability were investigated.Orthogonal experiments were carried out to investigate the effects of ultraviolet absorbers,hindered amine light stabilizers,antioxidants and its compounding agent on the improvement of the paraffin light stability.The results showed that the best paraffin light stability was achieved when the additive amounts of UV absorbers, hindered amine light stabilizers and antioxidants in the compound were 300 μg/g, 300 μg/g and 300 μg/g, respectively.

To prevent accidents like the "3?12" explosion and fire incident in the hydrogenation unit of a petrochemical enterprise in Jiujiang, Jiangxi Province, this study proposes the application of Hazard and Operability Analysis (HAZOP) and Safety Integrity Level (SIL) classification in the basic design phase of the emergency cut?off function hazards control project for a refining and chemical enterprise. HAZOP analysis adopts a workflow based on the parameter preference method while SIL classification is based on the LOPA (Layers of Protection Analysis) method, following the ALARP (As Low As Reasonably Practical) principle. HAZOP & SIL classification was carried out for a coking steam kerosene hydrorefining unit, a hydrogenation combined diesel hydrorefining unit and an ethylbenzene unit in a refining enterprise. A total of 12 accident scenarios were identified and 6 recommended measures were put forward. The results demonstrate that HAZOP & SIL classification can effectively assist the refining and chemical enterprise in managing the risks of intermingling pressures, maintaining control over safety production, reducing intermingling pressure risks to an acceptable level, or eliminating them promptly, thereby preventing accidents caused by intermingling pressures and ensuring the inherent safety of the refining and chemical enterprise.