Handling \"heavy\" materials as if they were light: composition and properties of sludge in the slurry bed process of oil refining

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Slurry-bed oil residue is the residue resulting from the hydroprocessing of vacuum residue in a slurry bed; due to its semi-oil, semi-coke nature, it is referred to as “oil + residue”. Similar to oil-coal slurry made from coal, it tends to settle and separate into phases, undergo coking, and solidify at low temperatures. Oil residues contain medium oil that failed to be distilled due to liquefaction, as well as unconverted heavy oil ； Ashes such as solidified asphalt cores, reaction coke, and metal sulfides. I. Softening point: A softening point of over 150°C; the pipes are heated using tape-type heating elements, while storage in tanks is accomplished through heating with heat transfer oil ； II. Viscosity: The viscosity at 150°C is 110–150 CP; it is significantly lower compared to the viscosity of the 540°C+ components in residue, as a result of reduced hydrogenation at the molecular level and noticeable viscosity reduction ； III. Oil in the cycle: The content of the oil phase fractions at temperatures below 500°C ranges from 28% to 35%; this value depends mainly on the efficiency of separation in the vacuum distillation tower, and it tends to increase over time due to blockages in the filler material of the tower ； IV. Unconverted heavy oil: The oil phase that can dissolve in **furan at temperatures above 500°C; it consists mainly of aromatic compounds with five or more rings, and is rich in C-N non-basic nitrogen atoms ； V. Semi-coke: **furan-insoluble substances, liquid residual coke, and reaction coke powder ； VI. Ash: Hydrodesulfurization products, reaction catalysts, and inorganic substances, mainly including nickel, vanadium, molybdenum, silicon, sodium, and catalytic cracking catalysts, etc. These characteristics determine that the flow velocity in the oil sludge pipeline must be high, the flow path must be free of dead corners, the pipeline can only be installed at an upward slope, and there must be no air pockets or liquid pockets ； Storage in the tank requires continuous side-stream stirring at 200–220°C, a feed inlet at the bottom of the tank via an inclined transfer pump, and continuous circulation by the transfer pump.