Abstract: Based on both vacuum gas oil hydrotreating unit operating data and the spent catalysts analysis result, the key factors affecting the long-term stable operation of the vacuum gas oil hydrotreating units are analyzed and discussed. The results show that the asphaltene content in the feedstock is the key factor affecting the long-term stable operation of heavy oil hydrotreating unit. By designing the reasonable catalysts grading system and operating condition for the different feedstocks, the coke deposited on the catalysts surface could reach the dynamic equilibrium and the hydrotreating unit catalysts could not deactivate in the whole cycle length. Based on the VGO hydrotreating unit operating experience, the countermeasures to realize long-term stable operation of heavy oil and diesel fraction hydrotreating unit are put forward.

Key words: VGO hydrogtreating, catalyst deactivation, asphaltene, long-term