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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).

This paper includes the problem statement of obtaining environmentally friendly high-viscosity marine fuels, as well as a possible technological solution consisting in sequential oil processing in an atmospheric-vacuum unit, processing of the vacuum residue with or without preliminary deasphalting in a delayed coking unit, and subsequent compounding of middle and heavy distillates from the delayed coking unit with low-sulfur fractions. The research targets were tar and asphalt, which had been obtained from tar in the process of propane deasphalting. These residues were subjected to coking at 500 °C and a pressure of 0.15−0.35 MPa. Physical properties, chemical composition, and quantitative group hydrocarbon and trace-metal compositions (including vanadium and nickel) were determined for the feed and the obtained middle and heavy distillates. The possibility of applying the maximum amount of coking distillates to obtain environmentally friendly compositions of marine fuel with a sulfur content of up to 0.5 wt % was evaluated.

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.

The results of experimental investigations on the coking of decanted heavy gasoil of catalytic cracking with polystyrene in a certain concentration range to obtain petroleum needle coke with the most developed string-base anisotropic structure and a microstructure point of at least 6.2 corresponding to the super-premium grade are presented. Certain regularities have been established to improve the structural quality index of the resulting needle coke from the optimal content of polystyrene in the base raw material, including the extreme dependence of the quality indices of needle coke on the polystyrene content (10 wt %). The decrease in the quality indices of the obtained carbon material is a consequence of uncontrolled changes toward an increase in the system viscosity performance (the viscosity increases 2.7 times). The experimentally obtained coefficient of thermal expansion (CTE) of needle coke-synthesized samples within the temperature range of 40–500 °C showed a reducing trend in CTE depending on the polymer additive proportion in the feedstock; for example, at 300 °C, the CTE decreases to 5.732 × 10–6 °C–1.

Paper studies the effect of excess pressure during delayed coking of asphalt, obtained by propane deasphaltization of tar, on yield and physical and chemical properties of hydrocarbon fuels' components and solid-phase product – petroleum coke. Asphalt was coked at a temperature of 500 °C and excess pressure of 0.15-0.35 MPa in a laboratory unit for delayed coking of periodic action. Physical and chemical properties of raw materials and components of light (gasoline), medium (light gasoil), and heavy (heavy gasoil) distillates obtained during experimental study were determined: density, viscosity, coking ability, sulfur content, iodine number, pour points, flash points, fluidity loss and fractional composition. Quantitative group hydrocarbon and microelement compositions and properties of obtained samples of petroleum coke (humidity, ash content, volatiles' yield, sulfur content, etc.) were also studied. Comparative assessment of their quality is given in accordance with requirements of GOST 22898-78 “Low-sulfur petroleum coke. Specifications”. In addition, patterns of changes in excess coking pressure on yield and quality indicators of distillate products and petroleum coke were revealed. With an increase in excess pressure of coking process from 0.15 to 0.35 MPa, content of paraffin-naphthenic hydrocarbons in light and heavy gasoils of delayed coking  decreases. Common pattern in asphalt coking is an increase in yield of coke and hydrocarbon gas with an increase in excess pressure from 0.15 to 0.35 MPa.

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Coke producers often face a shortage of valuable grades of coals, i.e. coking coals. This paper examines the possibility to obtain a coking additive by applying delayed coking to various types of heavy petroleum residues. The paper also gives a comparative description. Five types of heavy petroleum residue from the KINEF oil refinery were used in the experiments that aimed to produce carbon material. They included vacuum residue ELOU-AVT-6, vacuum residue S-1000 resultant from the hydrocracking process, visbreaker bottoms from the S-3000 unit, and two mixtures of the ELOU-AVT-6 unit products: a mixture of vacuum residue and third vacuum cut; and a mixture of vacuum residue, third vacuum cut and atmospheric residue. The carbon material obtained from all the above types of raw materials was analyzed for quality; an X-ray diffraction analysis was carried out; and the interplanar spacings d002 and d110 were calculated, as well as the linear sizes of Lc and La crystallites. The coking additive obtained instead of the typical petroleum coke was found to meet the specification. Thus, the volatile matter content in it is within the range from 15 to 25 wt%. This additive can be used in steel production instead of coking coal. The coking additive from a mixture of vacuum residue, third vacuum cut and atmospheric residue has the highest content of volatile matter (19.30%), while the coking additive from the visbreaking residue from the S-3000 has the lowest volatile matter content (16.15%). The latter is due to the fact that the primary petroleum material was subjected to light thermal cracking. It is shown that as the composition of the heavy petroleum residue changes, so do the properties of the resultant coking additive: a higher fraction of the low-boiling components in the feedstock is associated with a higher volatile matter content; the carbon materials produced from vacuum residue have a higher microhardness; the coking product produced from the visbreaker bottoms has a lower porosity compared with the product obtained from the vacuum residue. This research was carried out as part of a governmental assignment of the Ministry of Education and Science of the Russian Federation in the framework of the following research project: 0792-2020-0010 “Fundamentals of innovative processing techniques to obtain environmentally-friendly motor fuels and innovative carbon materials with variable macro- and microstructure of the mesophase from heavy hydrocarbon materials”. The research was carried out at the laboratory of the Shared Knowledge Centre of the Saint Petersburg Mining University.