Abstract: A residual oil hydrotreating unit in SINOPEC Changling Company successfully ran for four cycles. The first cycle ran for 426 days, processing residue with high content of iron and calcium; the 2nd cycle was up to 471 days. Due to the overhaul, the 3rd cycle only worked for 326 days. By optimizing catalysts grading, blending LCO and decreasing VR ratio, the fourth cycle was even longer, as long as 693 days. Compared with the second cycle, the total amount of feed and VR processed, utilization efficiency of the catalyst, and the impurities removal rate in the fourth cycle were all higher, thought the blending ratio of VR was less than in the former.

Key words: residue hydrotreating, super long-term, catalyst grading, LCO, VR