Hydro-donated Hydrovisbreaking Of Inferior Vacuum Residue

The high density and viscosity of heavy crude oil made it difficult to transporation. Thermal upgrading method was adopted to process the heavy crude oil before transporation in this paper. The upgrading effect of the four kinds of thermal conversion of the two vacuum residues(>420℃) from Venezuelan synthetic crude oil(SCO) and oil sand bitumen were systematically investigated in autoclaves. The influence of reaction conditions on the products from each thermal process was analyzed and the roles of hydrogen and hydrogen donor during the thermal conversion were revealed. Simplified reaction model of vacuum residue was employed to explain the test phenomenon from the point of reaction kinetics. At the end, blending tests of products from each kinds of thermal processes were carried out to select the suitable reaction conditions, under which the processed crude oil could meet the basic requirements of ship transportation. Specific results were as follows.In hydrovisbreaking(HVB) and hydro-donated visbreaking(HDVB) and hydro-donated hydrovisbreaking(HHVB) of vacuum residues, the results showed that hydrogen and hydrogen donor employ in these processes were both able to slow down reaction rate, increase reaction apparent activation energy, reduce the conversion ratio of vacuum residue compared to visbreaking(VB) processes under the same conditions; the presence of hydrogen and hydrogen donor could play the roles of inhibiting the growth of asphaltene and coke, lengthening the coke induction period and lowering coke yield in these thermal processes; compared with the gas-to-liquid hydrogen transfer of hydrogen, hydrogen donor was more effective to give their hydrogen free radicals to the vacuum residue because of their coexistence in liquid phase; meanwhile, the addition of hydrogen donor was able to reduce the density and viscosity by its solvent dilution effect for residue system.The conversion ratio of vacuum residue reached the maximum when the reaction time was the coke induction period in each thermal process; the maximum conversion ratio of Venezuelan vacuum residue in the four thermal processes were 42.60(HHVB), 40.55(HDVB), 37.78(HVB) and 34.34%(VB) at 420℃, respectively. The corresponding coke induction period were 16, 14, 11 and 9 min, respectively. The roles of hydrogen and hydrogen donor were revealed further by the difference of maximum conversion ratio and coke induction period.The two vacuum residues were processed under the selected suitable thermal reaction conditions and then blended to obtain the upgrading oils. The density and viscosity of these upgrading oil was lower than the crude oils; to be specific, °API was greater than 12, viscosity measured at 50℃ was smaller than 380 mm2/s, the spot test rated no more than NO.2, which all met the basic requirements of ship transportation. Compared with Venezuelan SCO, the sulfur content of the upgrading oil was significantly reduced, nitrogen content remained about the same, asphaltene content was increased; at the same reaction condition, the sulfur content of the upgrading oil derived from HHVB process had the most reduction while its asphaltene content increased least.