Study On Fcc Diesel Hydrofining-dewaxing Composite Technology

For protecting environment we depend on, the specification on diesel is getting more and more strict, The quality of Qianguo Petrochemical Company's FCC (Fluid Catalytic Cracking) diesel is low, in which the Sulfur contents exceeds 0.13w%, oxidation stability exceeds 10mg/100mL, These have influenced the production quality of Qianguo Refinery.Hydrotreating is the best way to improve the quality of FCC diesel. At present, the mature domestic diesel hydrotreating technologies are hydrofining, hydroupgrading and hydrodewaxing. The FC-20 catalyst which Fushun Research Institute had developed has excellent hydrogenation and isomerization-hydrocracking function. Arranging FH-98 hydrofining catalyst and FC-20 catalyst tandem in one stage is a new style. The hydrofining effect of this technology is fine, and using it we can produce low pour point diesel with more advantage. It was studied further in this paper. First, experimental study was conducted in a pilot hydrocracking equipment in order to evaluate the effect of catalytic hydrotreating and isodewaxing on QianGuo RFCC diesel. Experiments were carried out at various reaction conditions, and the experimental results turn up trumps. Second, The technology has been put into use in the 20×10⁴ t/a hydrotreating unit of Qianguo Refinery. The effect of hydrofining is stabilized during carrying out hydrofining project. In the output diesel, the oxidation stability is less than 2.0mg/100mL and the Sulfur content is smaller than 100μg/g. The product is accord with national specification GB/T19147-2003. When performs the isodewaxing project in winter, with the reaction temperature of 387.7℃, pressure of 7.2MPa and dewaxing stage liquid hourly space velocity of 1.45h^-1, the pour point of output diesel falls from -3℃to -20℃, the cetane index increases by 1 units, the density decreases 15kg/m³, the T95 drops 17℃, Sulfur contents under 25μg/g. The liquid yield is 97.86% and the diesel yield is 92.11%.The result of experiments and industry application shows that the activity of FH-98 and FC-20 catalyst is fit for each other and can be arranged in the single stage. The technology is effective both in hydrofining and isodewaxing. It can produce diesel with low pour point, ultra-low sulfur, low density, low T95 and high cetane number. The successful industry application offers a new route to produce clean diesel, and it is suitably for north refinery's demand.