Abstract: Factors affecting vacuum deep cut of residue oil were analyzed. A technology for vacuum deep cut based on heating vacuum residue (VR) by molten salt was introduced and put into practice on a newly built pilot plant device of a refinery. Results of pilot plant tests showed that by molten salt heating the temperature of VR could reach the required temperature for conducting vacuum deep cut, furthermore, the heating by molten salt was uniformed and the temperature difference between tube surface and VR was only a little. Under the conditions of a vacuum column feed inlet temperature of 415 ℃, column bottom temperature of 380 ℃, top temperature of 355 ℃, top absolute pressure of 0.90-0.92 kPa, the distillate yield of VR (from said refinery) by deep distillation reached 35%.

Key words: molten salt, vacuum deep cut, vacuum residue