Abstract: The feeds of VRDS units in refineries along the Yangtze River are characterized by high nitrogen, low sulfur, high Ni/V ratio and large Fe,Ca content. A series of solutions were developed by Research Institute of Petroleum Processing and commercialized successfully. A crude decalcification facility was added and a guard catalyst with higher capability for FeS and CaS deposition was developed to solve the problem of high Ca content. Meanwhile a catalyst with higher HDCCR conversion for the low sulfur and high nitrogen content feed was applied. For realizing a longer cycle-length, a suitable catalyst grading technology, a high efficient flow distribution technology and the RICP process in some refineries were practiced. The results show that coke-make decreases dramatically, which is beneficial to the longer cycle-length.

Key words: residue hydrotreating, long cycle-length, operation, optimization, solution