Influence of Asphaltenes on the Low-Sulphur Residual Marine Fuels’ Stability

Abstract

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).

Effect of Ultrasound Irradiation on the Properties and Sulfur Contents of Blended Very Low-Sulfur Fuel Oil (VLSFO)

“…Despite the increasing availability of low sulfur alternative fuels [9][10][11], such as biodiesel, vegetable oils, and ammonia, they are mostly used in the road transportation sector and are in-compatible with marine engines [10]. Another alternative fuel, liquified natural gas (LNG), has been implemented mainly on LNG tankers and new dual-fuel ships [12]. There are three conventional methods for manufacturing VLSFO with a sulfur content of ≤0.5% [13]: (1) purifying low-sulfur crude oil (i.e., sweet oil), (2) using a desulfurization system for high sulfur fuel oil (HSFO), and (3) blending VLSFO with HSFO.…”

“…However, the characteristics of the resulting blend greatly depend on the origin of raw materials, the production time, and the refinery/purification processes. Improper blending results in unstable fuels, and thus causes excess sludge production, a decline in blending stability, and necessitates the use of additives [12,18]. Consequently, there are always incompatibility [19] and additives (e.g., cutter stock) issues [20].…”

Manifestation of incompatibility of marine residual fuels: a method for determining compatibility, studying composition of fuels and sediment

“…The main parameters of the structures of such crystallites are interplanar distances -d002, d110 and the sizes of coherent scattering regions in the direction of crystallographic axes с and а, Lc and La, respectively. For graphite, d002 and d110 are 3.354 and 1.232 Å, respectively, while for the turbostratic structure, d002 ranges from 3.37 to 3.60 Å and d110 from 1.215 to 1.230 Å [41]. The highest intensity (850 rel.…”

“…Structure of crystal lattice of sediment after thermal aging is controlled by pronounced peaks with maximum 2θ angle values of about 25 and 77° corresponding to reflexes 2θ002 and 2θ110. Angular position of reflexes (2θ002 and 2θ110) on X-ray pattern is determined by the corresponding interplanar spacing (d002 and d110) [41]. Results of diffraction analysis and calculated values for the sediment after aging: reflex (002) -2θ = 24.9800°, half-width -2.8400°, d002 -3.5618 Å, Lc -27.7648 Å; reflex (110) -2θ = 77.5000°, half-width -0.6000°, d110 -1.2307 Å, La -174.0710 Å.…”

“…Interplanar distance d002 is 3.5618 Å, and d110 -1.2307 Å. According to the results of X-ray phase analysis, the nature of microstructure of carbon materials can be presumed from the ratio of the average height Lc and average diameter La of crystallites [41,42]. In this case, Lc to La ratio is approximately 1 to 16, which indicates an oblate structure of crystallites pointing to the start of transition from the liquid phase to the amorphous solid state due to physical filtration process after heat treatment at 100 °C for 24 h.…”