Search

Liquid products produced from two different types of waste pyrolysismunicipal wastes and spent tyre wastes are investigated using gas chromatography—mass spectrometry. This method has been applied for detailed identification of composition of the samples. The components were characterized in terms of their Kovats retention indices on a PONA capillary column. The obtained analytical data were successfully used for the characterization of the samples. More than three hundred compounds were detected. The liquid products were complex mixtures, composed mainly of C4—C12 compounds. The examination of the selected m/z values very clearly indicates the existence of the different groups of compounds. With a lot of olefins content (31.9%), followed by aromatics (20.0%), paraffins (17.3%), and naphthenes (7.5%), it is described as the liquid product from pyrolysis of municipal solid wastes. The aromatic compounds in liquid product from pyrolysis of spent tyre wastes have the highest concentration (33.5%), and they a...

Nine vacuum residual oils were characterized and eight blends of them were processed in the LUKOIL Neftohim Burgas commercial visbreaker unit. It was found that at constant content of about 8 vol.% of the fraction boiling up to 360 °C (diesel cut) in the visbroken residue the visbroken residue viscosity correlated with the vacuum residual oil visbreaker feed viscosity with a squared correlation coefficient R 2 > 0.98. By application of correlation analysis and intercriteria analysis the vacuum residual oil feedstock parameters which have statistically meaningful impact on conversion to product boiling below 360 °C were found to be vacuum residual oil sulfur and hydrogen content, and solubility power of maltenes. The results obtained in this work are consistent with those obtained from other groups, even for other types of vacuum residue processing like ebullated bed hydrocracking. The vacuum residual oils which contained more resinous-asphaltenic materials formed more asphaltenes in the process of thermal conversion. The vacuum residual oil viscosity increment with increasing of asphaltene content for the straight run vacuum residual oils can be described by a second order polynomial. The secondary vacuum residual oils — the visbroken vacuum residual oils exhibited a lower than straight run residual oil dependence of the residue viscosity increment on increasing of the asphaltene content.

Kinetic data for hydroperoxide formation in a commercial biodiesel, produced from 50% sunflower oil and 50% rapeseed oil were obtained by using rapid, higher than standard temperature procedure with sufficient oxygen solubility in the samples. Three different mathematical methods for processing the data and shelf life determination of the studied biodiesel are compared. The applicable methodologies are hydroperoxide concentration abrupt increase graphical determination and Q rule. The calculation shows that shelf life of the studied stabilized Bulgarian biodiesel amounts between 1.17 and 1.27 years. It was also found that peroxide value for induction period at 15 °C is 71.8 meq O 2 /kg biodiesel.

The geometry, electronic structure and chemical reactivity of a pyridinium-based ionic liquid, pyridinium hydrogen sulfate ([H–Pyr] + [HSO 4 ] − ), have been discussed on the basis of quantum chemical density functional theory calculations using B3LYP/6-311+G(d,p) and B3LYP/6-311++G(2d,2p) approaches. The calculations indicated that [H–Pyr] + [HSO 4 ] − exists in the form of an ion pair. A large electropositive potential was found on the pyridinium ring, while the regions of a negative electrostatic potential is linked with the lone pair of electronegative oxygen atoms in hydrogen sulfate anion ([HSO 4 ] − ). Electron transfer both within the anion, and between the anion and cation of an ion pair were described using natural bond orbital theory. The energy values of −7.1375 and −2.8801 eV were related to HOMO and LUMO orbitals, respectively.

The thermal conversion of fifteen vacuum residual oils (VROs) having different properties was investigated in a modified high-temperature–high-pressure batch autoclave reactor. It was found that the sediment level (toluene insoluble) in the unconverted residual oil demonstrated a behavior typical for presence of induction period. The sediment level at the end of the induction period was mostly influenced by feedstock colloidal stability. The rate of sediment formation after the induction period was mostly influenced by VRO resin content. The results in this study do not support the assumption that the more aromatic VROs generate more coke-like sediments during thermal conversion. The higher density and aromatic VROs generated less sediment. The addition of high aromatic fluid catalytic cracking (FCC) slurry oil to a VRO decreased the thermal reactor surface deposit. The effect of this coke-like reactor sediment reduction is attributed to improvement in VRO asphaltene solubility by the high aromatic FCC slurry oil and a possible hydrogen donating properties of this gas oil. The use of a synthetic dispersant was found to improve the asphaltene solubility limit and extend the period of conversion without forming coke-like deposit in the thermal cracking reactor. The FCC slurry demonstrated a stronger inhibition effect on sediment formation than the synthetic dispersant probably because it is a stronger solvent and/or because it possesses hydrogen donating properties.

Lukoil Neftohim Burgas (LNB), the single refinery currently operating in Bulgaria, constructed and put into operation a new high pressure diesel hydrotreater in 2010. Since its start-up, the unit has operated smoothly by hydrotreating a heavy diesel fraction (200–360 °C) with sulfur content of 0.8% and density at 20 °C of 0.860 g/cm 3 and producing hydrotreated diesel with sulfur content of 6 ppm and density at 20 °C of 0.847 g/cm 3 . However, in 2013 a sudden increase of the pressure of the treating gas compressor at the hydrotreater scheme was registered and the unit had to be switched off in emergency. Sediments formed in the tubes of the heat-exchanger, used for heat transfer between the hydrotreater product and hydrogen treating gases, were found. This study presents the results from the determination of the composition and the origin of the deposit, as well as the technological solutions to prevent its formation. According of the data from different analytical techniques applied, the following composition of the deposit was supposed: 46.6% ammonium chloride, 9.6% nitrates, 13.6% organic chlorides and about 30% water, organic impurities (carbonic acids and naphthenic hydrocarbons) and corrosion products. Numerical investigation of the temperature field in the area of the deposits is also presented.

Thirteen vacuum residual oils originating from Russia, Middle East, Asia, and South America were thermally cracked in a modified high-temperature–high-pressure batch autoclave reactor. It was found that the colloidal stability of the vacuum residual oils expressed by S-value was the dominant factor that affected the residue thermal reactivity. SARA analysis data of the residual oils were confirmed to contain insufficient information about residue thermal reactivity and colloidal stability. It was found that the higher the colloidal stability of a residual oil the lower residue thermal reactivity and the steeper colloidal stability reduction during thermal conversion. The asphaltene solubility was found to linearly decrease with the increase of the thermal conversion, while the maltene solubility power did not always decrease with the increase of the thermal conversion for the studied residual oils. Having in mind that the ebullated bed residue hydrocraking H-Oil process is also based on thermal conversion the properties of commercial straight run Urals vacuum residue (UVR), visbreaker residue obtained by thermal cracking of UVR (UVBR), and ebullated bed hydrocracking (H-Oil) unconverted residue were investigated. It was found that asphaltene solubility lowered linearly with increasing of conversion regardless of the process: visbreaking or ebullated bed hydrocracking. The maltene fraction average molecular weight seems to decrease with the increase of the residue thermal conversion processes visbreaking and ebullated hydrocracking as the asphaltene average molecular weight does for the same processes. It was found that the atmospheric gas oil fraction from visbreaker has no negative effect on residual oil colloidal stability while the vacuum gas oil fraction has negative impact on residue stability in both visbreaker and H-Oil unconverted residual oils. The data generated in this work study suggest that the asphaltene solubility has a bigger impact on the residual oil colloidal stability than the maltene solubility power.

The possibility to apply the intercriteria analysis over normalized data is discussed. An example, related to evaluation of crude oil data, is given.

Evaluation of opportunity to raise Euro V diesel production by increasing fluid catalytic cracking (FCC) light cycle oil (LCO) production was carried at the Lukoil Neftochim Bourgas, Bulgaria (LNB) refinery. The FCC LCO (IBP-360 °C) production was investigated in the FCC conversion range between 69 and 83 wt.% and LCO initial boiling point (IBP) between 177 and 210 °C. It was found that the LCO yield increased from 16.0 up to 20.7 wt.% by decreasing conversion from 83 to 69 wt.%. At constant conversion in the FCC unit of 79.7 wt.% the LCO yield increased from 17.8 to 24.8 wt.% by decreasing the IBP from 210 to 177 °C. A further 3.5 wt.% LCO yield increase and meeting the diesel flash point specification of 55 °C can be achieved by lowering the LCO IBP down to 163 °C. It was found that during hydrotreatment of a blend of the LNB middle distillates and LCO in a high pressure (70 bars) hydrotreater employing Co-Mo catalyst the maximum LCO (IBP = 210; FBP = 300 °C) content that allows meeting the EN specifications is 10 wt.%. If the LCO IBP is reduced to 177 °C then the maximum LCO content in the feed can reach 20 wt.%. The limitation of density not higher than 0.845 g/cm3 in the hydrotreated product at 15 °C is the restriction for further increase of LCO content in hydrotreater feed. Replacing the Co-Mo catalyst by Ni-Mo and noble metal catalysts in the high pressure hydrotreater can allow more than double increase of LCO content in hydrotreater feed. Hydrogen chemical consumption in that case, however is also more than twofold.

Cold flow properties and oxidation stability of near zero sulfur diesel from Ural crude oil and fatty methyl esters (FAME) from different origin and their blends were studied in this work. It was found that undercutting the petroleum diesel to obtain arctic diesel deteriorates its oxidation stability and anti-oxidant addition is required to keep the oxidation stability within acceptable limits. The addition of commercially available FAMEs, produced from 100% rape seed oil; 70% soya and 30% palm oil; 50% rape seed oil and 50% sunflower oil, to the petroleum diesel depresses the cold filter plugging point (CFPP). The depressing effect on the conventional diesel CFPP of the FAME depends on the petroleum diesel and the FAME properties. The Honeywell software RPMS model used to predict cloud points (CP) of blends of different conventional middle distillates was found to be capable of predicting cloud points of blends of petroleum diesel and FAME. The highest class 4 of arctic diesel according to EN 590 (CP = −34 °C; CFPP = −44 °C) can be produced by blending petroleum diesel with the 100% rape seed FAME treated with cold flow improver in concentration up to 10%. The addition of the synthetic anti-oxidant ionol (BHT) to petroleum diesel with high unsaturated hydrocarbon level and to the blends petroleum diesel/FAME seems to inhibit the secondary reactions of peroxides decomposition to acids to a greater extent than the oxidative polymerization.

This paper investigates the effect of fluid catalytic cracking (FCC) feed hydrotreatment and its severity increase on product yields and quality obtained in a commercial and a laboratory MAT FCC units. The hydrotreatment of Ural heavy vacuum gas oil reduces not only sulfur, nitrogen, Conradson carbon and metals content in the FCC feed but also increases the mononuclear aromatic hydrocarbons content by 8% absolute at almost no change in the total aromatics content. Regardless of this 8% increase of the mononuclear aromatics in the hydrotreated FCC feed the conversion increase in both commercial and laboratory MAT units was only 2%. The severity increase in the FCC feed hydrotreater leads to a higher conversion in the FCC, higher hydrogen transfer rate that results in higher isobutane/butylenes ratio, lower gasoline olefins content, and higher gasoline motor octane number. The hydrotreatment of the Ural heavy vacuum gas oil exhibited the same changes in FCC catalyst selectivities: lower coke and LCO selectivities and higher gasoline selectivity in both commercial riser FCC unit that has between 2 and 3 s time on stream, and the fixed bed reactor MAT unit, that has 30 s time on stream.

Hydrotreated vacuum gasoil from straight-run distillation of a Russian export mixture (GRES) and the same gasoil after treatment with sulfuric acid (OGRES) so that nitrogen-containing compounds were totally removed and the hydrocarbon composition was almost unchanged were investigated as catalytic feedstock. Cracking was conducted on a MAT laboratory setup with different catalyst and feedstock ratios, constant reactor temperature of 527°C, and feedstock contact time with catalyst of 30 sec. Elimination of nitrogen-containing compounds from GRES increased the yield of cyclic hydrocarbons in the naphtha cut with lower aromatization and decreased the yield of macromolecular aliphatic hydrocarbons with lower olefination. In the absence of basic nitrogen, the activity and selectivity of the catalyst for the naphtha and light cyclic petroleum products increased. The naphtha obtained from OGRES, in comparison to the naphtha obtained from GRES, contains more cycloalkanes and less alkanes and alkenes and has lower research and motor octane numbers.

Six H-Oil-based residual fuel oils, two H-Oil atmospheric tower bottom products, two H-Oil vacuum tower bottom products, one visbreaker-based residual fuel oil, and three different straight run vacuum residual oils were studied in this work. The colloidal stability parameters S-value (ASTM D7157), and separability number (ASTM D7061), along with SARA-based colloidal instability index, and the solubility parameters of asphaltene and maltene fractions of the studied residual oils were tested to correlate with the residual oil sediment content. It was found that none of the colloidal stability parameters correlated with the residual oil sediment content, while correlations were found between the different colloidal stability parameters. This study has shown that only the residual oil samples whose S-value has been at minimum of 1.375 kept their sediment contents without change with the course of time. [Received: August 1, 2016; Accepted: December 4, 2016]

This study focuses on investigating the conversion behaviour of vacuum residue and blends with heavy VGO (480-540°C) and atmospheric residue (340°C+), three fractions originating from the same Russian export blend crude oil (REBCO), in a laboratory ebullated bed hydrocracking pilot plant unit and in the LUKOIL Neftohim Burgas commercial H-OilRC hydrocracker. It was found that the vacuum residue conversion was 1.7 times as high as that of the VGO at the same operating conditions in both laboratory and in the commercial H-OilRC hydrocracking unit. No increase in the sediment content of the atmospheric residue product, obtained during hydrocracking of the lighter feeds, was observed. It was found that the vacuum residue H-Oil hydrocracking is best described by 1.5 order kinetics. This study showed that co-processing of distillate material (mainly vacuum gas oil) is an option to increase capacity of an existing H-OilRC residue hydrocracker while also improving the VGO product quality without adversely impacting sediment levels in the unconverted residue product. [Received: February 2, 2017; Accepted: September 21, 2017]

Industrial experiments on the addition of H2S to the fluid catalytic cracking (FCC) feed (hydrotreated vacuum gas oil) were carried out in the commercial FCC unit at Lukoil Neftochim, Bulgaria. It was found that during cracking of pure hydrotreated vacuum gas oil to which was added about 550 ppm H2S that the FCC gasoline contained about 12 ppm more sulfur than the nonspiked feed. Both gasolines obtained from the pure feed and the H2S-spiked feed contained the same type of sulfur compounds: mercaptans, thiophenes, and benzothiophenes. In the case of the H2S-spiked feed, the additional FCC gasoline sulfur formed was about 1.2% of the sulfur in the H2S added to the feed. The FCC gasoline sulfur formed from the pure FCC feed, on the other hand, was about 2.5% of the sulfur in the feed. The higher percent of sulfur conversion of the pure FCC feed relative to the conversion of the H2S suggests that both reaction of H2S with olefins or diolefins (from the catalytic cracking of the hydrocarbons of the feed) and t...

Calculations are made of the heat balance of the vacuum column K-101 of the VDM-2 plant of LUKOIL Neftokhim Burgas AD, which made it possible to disclose the reasons for decline in heavy vacuum gas oil yield with increase in plant load and to discard the hypothesis that the reason for this is perforating of the plate from which the gas oil is withdrawn. It is shown that the reflux yield cannot be increased and the heat required for condensation of the heavy vacuum gas oil contained in the residual fuel oil cannot be removed if there is hydraulic resistance in the lower circulating reflux line.

The main obstacle in biodiesel/conventional diesel blends acceptance worldwide seems to be its poor oxidative stability. Low resistance towards oxygenation is due to the fatty constituent in the blend. Even low concentrations of biodiesel (5%, 10% and 20%) can contribute to sticky, viscous and polymeric deposits formation after several months of storage. Two correlations were derived concerning insolubles formed in both stabilized and not stabilized blends, stressed under conditions of ASTM D2274. For treated with antioxidant additive: Total insol. = 0.6561 + 80.1213 ∗ Δ TAN - 114.27 ∗ Δ PC - 2.6073 ∗ Δ IV For not stabilized samples: Total insol. = - 229.348338 - 13.2360978 ∗ Δ TAN + 968.531862 ∗ Δ Visc. - 25.0335999 ∗ Δ IV The correlations’ precision is described by the high value of R 2 = 1.0000. Present work proves that it is possible to stabilize such a blend even the fatty component is aged for a period of three months.

Application of the Topsoe Aroshift Technology in the Lukoil Neftochim, Bulgaria (LNB), fluid catalytic cracking (FCC) unit was studied in this work. The hydrotreated vacuum gas oil (HTVGO), feed for the LNB FCC unit, was treated in the Topsoe Aroshift pilot plant. The HTVGO and Aroshifted HTVGO were cracked in a laboratory fluid bed catalytic cracking unit (FCC advanced catalytic evaluation unit). The Aroshift treatment of the HTVGO increased the mononuclear aromatics content by 3%, which resulted in 3% higher FCC conversion and higher gasoline selectivity. The octane number of gasoline, produced from the Aroshifted HTVGO, was about 0.5 lower than that of gasoline, obtained by HTVGO cracking. The economic benefit of the Aroshift process application in the LNB FCC unit at a feed rate of 185 t/h was evaluated to be $6.78 million U.S./year.

In catalytic cracking of vacuum gasoils, the yields of products are correlated with their hydrogen content. A correlation that allows predicting the yields of products of this process was elaborated based on the results of cracking of 11 gasoils of different origin and data on their density, refractive index, and 50% distillation temperature. However, it is not possible to predict the octane number of the naphtha obtained in cracking with the group hydrocarbon composition of the feedstock.

Twenty-two crude oils around the world, from which 19 are processed in the LUKOIL Neftohim Burgas (LNB) refinery, were characterized in the LNB research laboratory by measuring 67 properties. These 22 crude oils included light low sulfur, light sulfur, intermediate low sulfur, intermediate sulfur, intermediate high sulfur, heavy high sulfur, and extra heavy extra high sulfur crudes. A new mathematical approach—the intercriteria analysis—was employed to study the relations between the petroleum properties. It was found that the petroleum properties, density, and sulfur content, along with the crude oil simulated distillation, seem to be capable of providing the same information as that from the full assay of a crude oil. Crude oils containing insoluble asphaltenes (self-incompatible oils) were found to have a high content of low aromaticity naphtha and kerosene. It was found that the asphaltene solubility correlated with the asphaltene hydrogen content. The oil solubility power was found to correlate with ...

High temperature simulated distillation (HTSD) of residual oils is not only faster but also more precise than the physical vacuum distillation (ASTM D-5236). However, the HTSD ASTM D-7169 method could report wrong results if it is not performed properly. A verification of the correctness of the HTSD analysis could be accomplished by comparison of the HTSD curve with the one of the physical vacuum distillation methods (ASTM D-1160 or ASTM D-5236). The calibration blend, design of the liner, the GC inlet temperature, and the concentration of heavy oil sample in CS2 were found to have a considerable impact on the correctness of the reported results. The conversion of HTSD in ASTM D-5236 developed in this work is able to predict the distillation curve of the ASTM D-5236 vacuum distillation with almost the same precision as its repeatability of the method. [Received: January 25, 2016; Accepted: June 23, 2016]

A database of 140 diesel fuels having cetane numbers in the range of 10–70 points; densities at 15 °C; and distillation characteristics according to ASTM D-86 T10%, T50%, and T90% was used to develop new procedures for predicting diesel cetane numbers by application of the least-squares method (LSM) using MAPLE software and an artificial neural network (ANN) using MATLAB. The existing standard methods of determining cetane-index values, ASTM D-976 and ASTM D-4737, which are correlations of the cetane number, confirmed the earlier conclusions that these methods predict the cetane number with a large variation. The four-variable ASTM D-4737 method was found to better approximate the diesel cetane number than the two-variable ASTM D-976 method. The developed four cetane-index models (one LSM and three ANN models) were found to better approximate the middle-distillate cetane numbers. Between 4% and 5% of the selected database of 140 middle distillates were samples with differences between their measured cetane numbers and the cetane-index values predicted by the four new procedures was higher than the specified reproducibility limit in the standard for measuring cetane number, ASTM D-613. In contrast, the cetane-index values calculated in accordance with standards ASTM D-976 and ASTM D-4737 demonstrated that 18% and 16% of the selected database of 140 middle distillates, respectively, were samples with differences between their measured cetane numbers and predicted cetane-index values higher than the specified reproducibility limit in standard ASTM D-613. The ASTM D-4737 method, LSM, and three ANN models were tested against 22 middle distillates not included in the database of 140 diesel fuels. The LSM cetane index showed the best cetane-number prediction capability among all of the models tested.

Thirty-four heavy oils originating from the four main groups of crude oils around the world—I group: light, low sulfur (30–400 API; S ≤ 0.5% mass); II group: light sulfur (30–400 API; S = 0, 5–1.5% mass); III group: heavy, high sulfur (15–300 API; S = 1.5, 3.1% mass); IV group: extra heavy, high sulfur (150 API, S ≥ 3% mass)—were investigated for distribution of boiling point and molecular weight. The three-parameter distribution model of Riazi and the four-parameter Webull extreme distribution function were tested to approximate the distribution of the heavy oil properties mentioned. It was found that the Weibull extreme more accurately approximates the heavy oil boiling point distribution up to temperatures of 750°C, and molecular weight distribution up to 955 g/mol. To approximate distribution of higher values extrapolation is needed. Riazi's distribution model was found to be more precise in the extrapolation than the Weibull extreme.