| The oxidation stability of FCC diesel is a difficult problem that should be resolved by oil refining factory. Though the oxidation stability of FCC diesel can be partly increased by using catalytic hydrogenation method, the cost of this technology is too high. Both the contents of nitrogen and sulfur-containing compounds in Nanyang FCC diesel are relatively high, so the problem of its oxidation stability is more serious than the diesels in other factories. Because of the high cost of catalytic hydrogenation, it is very necessary to find a new economical and rational diesel refining technology. A new method and technology of solvent extraction is developed and applied to improve oxidation stability of FCC diesel. The results show that about 96% of nitrogen and more than 11% of sulfur are removed respectively. The yield of refined diesel is above 97%, and the deposit produced during the course of acceleration and oxidation is below 2.0. The chroma of the refined oil is less than 2.0, after three-month reservation it is still below 3.5. The research results indicate that the oxidation stability of Nan Yang FCC diesel is primarily affected by nitrogen. The most effective method for improving the oxidation stability of FCC diesel is the total removal of nitrogen inside the diesel. The optimal industrial running conditions are summarized as following: theoretical extraction times is 4, the ratio of solvent/oil is 0.25-0.4, the extraction temperature is 20-40℃,the solvent constitution is 94-96%, and the volumetric ratio is 6-12%. The industrial running results prove that the quality of the refined diesel can meet the requirements of GB252-2000 Standards.
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