THE EFFECT OF VISBREAKING CONDITIONS ON THE STABILITY OF SOME IRAQI LONG RESIDUES

ABSTRACT A study has been done to investigate the change in the stability of residue during thermal process (visbreaking) at different cracking severity using flocculation ratio method. For this purpose, three long residues (350°C+) of different crude oils were used. The obtained results were discussed as a function of reaction temperature and residence time. Moreover, the stability was correlated with the nature and chemical composition of the feedstock.We observed that the intermediate paraffinic base feedstock (type A) was more stable than the other two asphaltenic base (Types B & C) when visbreaking temperature was 460°C. At higher temperatures, a sudden and large decrease in the stability of type A visbroken products was observed while only a gradual decrease in the stability of the other two products was noticed when visbreaking process was carried out at the same operating conditions.