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The effects of asphaltenes from two heavy oil residues on the sedimentation stability of residual marine fuels were assessed and compared. As base components of residual marine fuels, the vacuum residue (VacRes) and visbreaking residue (VisRes) were taken. The heptane-insoluble fractions (HI-fractions), including asphaltenes, isolated from vacuum residue and visbreaking residue, were analyzed to determine the elemental composition (XRF) and cluster parameters (XRD). The results of the analysis of the parameters of the asphaltene cluster (HI-fraction) for vacuum residue and visbreaking residue showed that dγ – 6.1 and 5.9 Å, Lc – 26.72 and 20.78 Å, and La – 7.68 and 7.20 Å. The sedimentation stability of residual marine fuel was determined according to the ISO 10307-1-2009 (TSA) method and described using ternary phase diagrams. The ratio of stable compositions to the total number of possible compositions (with a step of 10 wt%) was 65/66 or 98.5% for residual marine fuel comprising a mixture VacRes/ULSD/LCGO (vacuum residue/ultra-low sulphur diesel/light catalytic gas oil). Meanwhile, the ratio of stable compositions to the total number of possible compositions was 38/66 or 57.6% for residual marine fuel comprising a mixture VisRes/ULSD/LCGO (visbreaking residue/ultra-low sulphur diesel/light catalytic gas oil).

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This paper includes the results of studies of the temperature effect in the range of 480–510 °C at an excess pressure of 0.35 MPa, as well as the effect of excess pressure from 0.15 to 0.55 MPa at a temperature of 500–510 °C, during the delayed coking of a decant oil obtained from a mixture of West Siberian oils and subsequent calcination in an inert atmosphere of nitrogen at 1100 °C on the microstructure and properties of the needle coke. Properties such as absolute density, volatile-matter yield, ash, sulfur, and trace element contents were analyzed to evaluate the quality of the “green” and calcined coke. The microstructure of the obtained coke was analyzed by means of X-ray diffraction, for which the evaluation criteria were the interplanar spaces d 002 and d 100, as well as the crystallite sizes L c and L a. The scanning electron microscopy method was used to confirm the results of the formed structure of petroleum coke analysis obtained earlier. The calcined samples were assigned to needle cokes with stringy-circular flow domain anisotropy.

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