Abstract: The 1.8 Mt/a VGO hydrotreating unit was modified and used as a LTAG hydrotreating unit in SINOPEC Maoming Company. The modification effect and the problems and solutions during the operation were introduced. The industrial operation results indicated that by using the new generation catalyst system developed by RIPP，under the conditions of lower reaction temperature and hydrogen partial pressure，low sulfur and low nitrogen refining wax oil can be produced (sulfur 0.1% and nitrogen 560 μg/g). After mixing 35 t/h (about 14% of the total feed) catalytic cracking diesel, the hydrogenated diesel with a high content of monocyclic aromatic hydrocarbons and a mass fraction of polycyclic aromatic hydrocarbons less than 15% can be produced and used as LTAG process feed. The composite catalysts exhibit good activity and excellent comprehensive performance. When the feedstock is composed of mixture of LCO and VGO， the inlet temperature and average temperature of the reactor are decreased，while the reactor temperature and hydrogen consumption increased，and the comprehensive energy consumption is similar to that of pure VGO feed. During the start-up of the device, problems such as too many light fractions, large fluctuation of the fractionation system, and insufficient liquid in cold high pressure separator were encountered, leading the inability to further improve the process capacity. These problems were solved by taking measures to ensure the normal production of the plant.

Key words: VGO hydrotreating, LCO, LTAG, modification