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Twelve crude oil blends prepared from seven individual crude oils and an imported atmospheric residue were characterized through a true boiling point (TBP) distillation analysis and their density. When comparing the measured TBP fraction yields with those estimated through the application of the additive blending rule, it was found that, for four crude oil blends, the additive blending rule was valid, while for the remaining eight crude oil blends, deviations of the measured TBP yields from the estimated ones were bigger than the TBP analysis’s repeatability limits. By the use of intercriteria analysis evaluation of the data for the deviation of the TBP yields from the additive blending rule and the molar excess volume of the crude oil blends, statistically meaningful relations between the delta TBP yields of light and heavy naphtha, as well as vacuum residue with the molar excess volume, were found. The higher the magnitude of the crude oil blend’s molar excess volume, the bigger the deviations of the TBP yields of naphtha and vacuum residue are. The bigger the deviation of the crude oil blend’s behavior from that of the regular solution, as quantified by the molar excess volume, the bigger the deviations of the TBP yields of naphtha and vacuum residue are.

The production of heavy fuel oil from hydrocracked vacuum residue requires dilution of the residue with cutter stocks to reduce viscosity. The hydrocracked residue obtained from different vacuum residue blends originating from diverse crude oils may have divergent properties and interact with the variant cutter stocks in a dissimilar way leading to changeable values of density, sediment content, and viscosity of the obtained fuel oil. H-Oil hydrocracked vacuum residues (VTBs) obtained from different crude blends (Urals, Siberian Light (LSCO), and Basrah Heavy) were diluted with the high aromatic fluid catalytic cracking (FCC) light cycle, heavy cycle, and slurry oil, and the low aromatic fluid catalytic cracking feed hydrotreater diesel cutter stocks and their densities, sediment content, and viscosity of the mixtures were investigated. Intercriteria analysis evaluation of the data generated in this study was performed. It was found that the densities of the blends H-Oil VTB/cutter stocks deviate from the regular solution behavior because of the presence of attractive and repulsive forces between the molecules of the H-Oil VTB and the cutter stocks. Urals and Basrah Heavy crude oils were found to enhance the attractive forces, while the LSCO increases the repulsive forces between the molecules of H-Oil VTBs and those of the FCC gas oils. The viscosity of the H-Oil VTB obtained during hydrocracking of straight run vacuum residue blend was established to linearly depend on the viscosity of the H-Oil vacuum residue feed blend. The applied equations to predict viscosity of blends containing straight run and hydrocracked vacuum residues and cutter stocks proved their good prediction ability with an average relative absolute deviation (%AAD) of 8.8%. While the viscosity was found possible to predict, the sediment content of the blends H-Oil VTBs/cutter stocks was recalcitrant to forecast.

The exactitude of petroleum fluid molecular weight correlations affects significantly the precision of petroleum engineering calculations and can make process design and trouble-shooting inaccurate. Some of the methods in the literature to predict petroleum fluid molecular weight are used in commercial software process simulators. According to statements made in the literature, the correlations of Lee–Kesler and Twu are the most used in petroleum engineering, and the other methods do not exhibit any significant advantages over the Lee–Kesler and Twu correlations. In order to verify which of the proposed in the literature correlations are the most appropriate for petroleum fluids with molecular weight variation between 70 and 1685 g/mol, 430 data points for boiling point, specific gravity, and molecular weight of petroleum fluids and individual hydrocarbons were extracted from 17 literature sources. Besides the existing correlations in the literature, two different techniques, nonlinear regression and artificial neural network (ANN), were employed to model the molecular weight of the 430 petroleum fluid samples. It was found that the ANN model demonstrated the best accuracy of prediction with a relative standard error (RSE) of 7.2%, followed by the newly developed nonlinear regression correlation with an RSE of 10.9%. The best available molecular weight correlations in the literature were those of API (RSE = 12.4%), Goosens (RSE = 13.9%); and Riazi and Daubert (RSE = 15.2%). The well known molecular weight correlations of Lee–Kesler, and Twu, for the data set of 430 data points, exhibited RSEs of 26.5, and 30.3% respectively.

Forty-eight crude oils with variations in specific gravity (0.782 ≤ SG ≤ 1.002), sulphur content (0.03 ≤ S ≤ 5.6 wt.%), saturate content (23.5 ≤ Sat. ≤ 92.9 wt.%), asphaltene content (0.1 ≤ As ≤ 22.2 wt.%), and vacuum residue content (1.4 ≤ VR ≤ 60.7 wt.%) were characterized with HTSD, TBP, and SARA analyses. A modified SARA analysis of petroleum that allows for the attainment of a mass balance ≥97 wt.% for light crude oils was proposed, a procedure for the simulation of petroleum TBP curves from HTSD data using nonlinear regression and Riazi’s distribution model was developed, and a new correlation to predict petroleum saturate content from specific gravity and pour point with an average absolute deviation of 2.5 wt.%, maximum absolute deviation of 6.6 wt.%, and bias of 0.01 wt.% was developed. Intercriteria analysis was employed to evaluate the presence of statistically meaningful relations between the different petroleum properties and to evaluate the extent of similarity between the studied petroleum crudes. It was found that the extent of similarity between the crude oils based on HTSD analysis data could be discerned from data on the Kw characterization factor of narrow crude oil fractions. The results from this study showed that contrary to the generally accepted concept of the constant Kw characterization factor, the Kw factors of narrow fractions differ from that of crude oil. Moreover, the distributions of Kw factors of the different crudes were different.

Ten gas oils and one deasphalted hydrocracked vacuum residue obtained from ebullated-bed vacuum residue hydrocracking have been cracked in a laboratory advanced catalyst evaluation unit on a commercial fluid catalytic cracking (FCC) catalyst. It was found that the eleven secondary heavy oils obey second-order reaction kinetics. The relations between gas oil properties and FCC conversion, product yields, and quality were evaluated by means of intercriteria analysis. It could be stated that the FCC conversion strongly correlates with the gas oil Kw characterization factor. The product yields were established to depend on the secondary gas oil carbon atoms number, aromatic ring index, paraffinic and aromatic carbon content, and the total aromatics content.

Four straight run vacuum residual oils (SRVRO) and five H-Oil hydrocracked vacuum residual oils (H-Oil VTB) and their blends were oxidized in a laboratory autoclave reactor. It was found that the a...

The intercriteria analysis developed on the base of intuitionistic fuzziness and index matrices was applied to evaluate processing data of the LUKOIL Neftohim Burgas H-Oil ebullated bed vacuum residue hydrocracker with the aim of revealing the reasons for increased fouling registered during the 3rd cycle of the H-Oil hydrocracker. It was found that when the ratio of the ΔT of the 1st reactor to the ΔT of the 2nd reactor gets lower than 2.0, an excessive H-Oil equipment fouling occurs. The fouling was also found to be favored by processing of lower Conradson carbon content vacuum residual oils and increased throughput and depressed by increasing the dosage of the HCAT nanodispersed catalyst. The fouling in the atmospheric tower bottom section is facilitated by a lower aromatic content in the atmospheric tower bottom product. The addition of FCC slurry oil not only increases aromatic content but also dissolves some of the asphaltenes in the atmospheric residual hydrocracked oil and decreases its colloidal instability index. The fouling in the vacuum tower bottom section is facilitated by a higher saturate content in the VTB. Surprisingly, it was found that the asphaltene content in the VTB depresses the fouling rate. No relation was found of the sediment content in the hydrocracked residual oils measured by hot filtration tests and by the centrifuge method to the equipment fouling of the H-Oil hydrocracker.

The performance of both ebullated bed H-Oil vacuum residue (VR) hydrocracking and fluid catalytic cracking (FCC) of vacuum gas oils (VGO) is interrelated. The increase of H-Oil unit reaction temper...

Four nonlinear regression techniques were explored to model gas oil viscosity on the base of Walther’s empirical equation. With the initial database of 41 primary and secondary vacuum gas oils, four models were developed with a comparable accuracy of viscosity calculation. The Akaike information criterion and Bayesian information criterion selected the least square relative errors (LSRE) model as the best one. The sensitivity analysis with respect to the given data also revealed that the LSRE model is the most stable one with the lowest values of standard deviations of derivatives. Verification of the gas oil viscosity prediction ability was carried out with another set of 43 gas oils showing remarkably better accuracy with the LSRE model. The LSRE was also found to predict better viscosity for the 43 test gas oils relative to the Aboul Seoud and Moharam model and the Kotzakoulakis and George.

This study highlights the importance of the condition of the catalytic system in the ebullated bed vacuum residue hydrocracker on the performance of the unit, proving that not only feedstock qualit...

Thirty crude oils, belonging to light, medium, heavy, and extra heavy, light sulfur, and high sulfur have been characterized and compatibility indices defined. Nine crude oil compatibility indices have been employed to evaluate the compatibility of crude blends from the thirty individual crude oils. Intercriteria analysis revealed the relations between the different compatibility indices, and the different petroleum properties. Tetra-plot was employed to model crude blend compatibility. The ratio of solubility blending number to insolubility number was found to best describe the desalting efficiency, and therefore could be considered as the compatible index that best models the crude oil blend compatibility. Density of crude oil and the n-heptane dilution test seem to be sufficient to model, and predict the compatibility of crude blends.

Inter-criteria analysis was employed in VGO samples having a saturate content between 0.8 and 93.1 wt.% to define the statistically significant relations between physicochemical properties, empirical structural models and vacuum gas oil compositional information. The use of a logistic function and employment of a non-linear least squares method along with the aromatic ring index allowed for our newly developed correlation to accurately predict the saturate content of VGOs. The empirical models developed in this study can be used not only for obtaining the valuable structural information necessary to predict the behavior of VGOs in the conversion processes but can also be utilized to detect incorrectly performed SARA analyses. This work confirms the possibility of predicting the contents of VGO compounds from physicochemical properties and empirical models.

Three H-Oil gas oils, heavy atmospheric gas oil (HAGO), light vacuum gas oil (LVGO), heavy vacuum gas oil (HVGO), and two their blends with hydrotreated straight run vacuum gas oils (HTSRVGOs) were cracked on two high unit cell size (UCS) lower porosity commercial catalysts and two low UCS higher porosity commercial catalysts. The cracking experiments were performed in an advanced cracking evaluation fluid catalytic cracking (FCC) laboratory unit at 527 °C, 30 s catalyst time on stream, and catalyst-to-oil (CTO) variation between 3.5 and 7.5 wt/wt The two high UCS lower porosity catalysts were more active and more coke selective. However, the difference between conversion of the more active high UCS lower porosity and low UCS higher porosity catalysts at 7.5 wt/wt CTO decreased in the order 10% (HAGO) > 9% (LVGO) > 6% (HVGO) > 4% (80% HTSRVGO/20% H-Oil VGO). Therefore, the catalyst performance is feedstock-dependent. The four studied catalysts along with a blend of one of them with 2% ZSM-5 were examined in a commercially revamped UOP FCC VSS unit. The lower UCS higher porosity catalysts exhibited operation at a higher CTO ratio achieving a similar conversion level with more active higher UCS lower porosity catalysts. However, the higher UCS lower porosity catalysts made 0.67% Δ coke that was higher than the maximum acceptable limit of 0.64% for this particular commercial FCC unit (FCCU), which required excluding the HVGO from the FCC feed blend. The catalyst system containing ZSM-5 increased the LPG yield but did not have an impact on gasoline octane. It was found that the predominant factor that controls refinery profitability related to the FCCU performance is the FCC slurry oil (bottoms) yield.

The thermal stability and decomposition kinetics of the ionic liquid pyridinium nitrate was investigated by non-isothermal thermogravimetric analysis in an inert atmosphere (nitrogen). For the kinetic experiments, the thermal behavior of the sample was studied in the temperature interval from 360 up to 600 K at different heating rates (5, 10, 15 and 20 K/min). The kinetic parameters of decomposition including activation energy and pre-exponential factor under nitrogen atmosphere were evaluated by menace of two model-free methods – Friedman and Kissinger-Akahira-Sunose. Depending on the used calculation model, the obtained activation energy and pre-exponential factor values with respect to the degree of sample conversion during the kinetic experiment for method ranged in the intervals of 76.36–112.56 kJ/mol and 1.72×105–1.42×1010 min–1, respectively. Based on the attained kinetic parameter values it was established that the process of pyridinium nitrate decomposition occurred as a first-order reaction. Considering the calculated kinetic parameters, a decomposition mechanism for pyridinium nitrate was proposed.

In relation to the constant requirement for reduction of sulfur level and low demand for fuel oil, this study presents an approach for utilization of unconverted vacuum tower bottom (UVTB) from the ebullated bed hydrocracking process, H-Oil technology, in bitumen production. The kinetic study shows a slower softening point increase for crude blend 70% Urals and 30% Middle Eastern than other feeds in the air-blowing process. Also, penetration values for straight run vacuum residue feeds decrease quicker than the increase in their softening point values. UVTB softening point increase at high temperature is faster and penetration decrease is slower than LNB SRVR. Air blowing is shown to improve the penetration index of UVTB to a greater extent than the SRVR one. The bottleneck of this new application of UVTB is its low resistance to hardening, determined by using a rolling thin film oven (RTFO), which limits its quantity up to 20–30% in blends.

The catalytic behavior of three Brønsted acidic ionic liquids: pyridinium hydrogen sulfate ([H–Pyr]+[HSO4]−), pyridinium dihydrogen phosphate ([H–Pyr]+[H2PO4]−) and pyridinium nitrate ([H–Pyr]+[NO3]−) in the esterification of acetic acid with n-butanol was compared in the current paper. The alteration in the values of acetic acid conversion and esterification rate were investigated as a function of the process parameters: catalyst nature, catalyst loading, initial molar ratio n-butanol:acetic acid and reaction temperature. The anion variety modified the acidity of the obtained samples and effected their catalytic activity as follows: [H–Pyr]+[NO3]− < [H–Pyr]+[H2PO4]− < [H–Pyr]+[HSO4]−. The increasing of both catalyst loading and reaction temperature led to higher values of acetic acid conversion and esterification rate. The existence of a positive linear relationship between the esterification rate and acetic acid concentration was observed. The increasing of the n-butanol concentration negatively affected the rate of esterification. The acetic acid conversion was improved as the initial molar ratio n-butanol-to-acetic acid was raised.

The gasoline blending prediction models available in the open literature: Linear method, Ethyl method, Stewart method, Zahed method, and Twu method were tested on 25 gasoline blends prepared from 14 components used by LUKOIL Neftohim Burgas (LNB) refinery to produce commercial gasoline grades. The performed tests with these models showed prediction accuracy outside of the acceptable ASTM D 2699 and ASTM D 2700 reproducibility limits. However, the LNB-modified regression model of Zahed method turned out to predict RON and MON of studied gasoline blends with accuracy equivalent to the reproducibility of the standard methods for measurement of RON and MON.

This paper passes over the literature for residual oil characterization. The methods for residual oil characterization are classified in: characterization based on physical and chemical bulk properties; characterization based on saturates, aromatics, resins, asphaltenes (SARA) analysis; and characterization based on the molecular modeling processes. The upper and lower limits of the values for physical and chemical bulk properties of the vacuum residual oils around the world are outlined. A variation of the physical and chemical bulk properties of SARA fractions originating from different vacuum residual oils is discussed. Correlations between refractive index and density, and between the vapor pressure osmometry (VPO) molecular weight of saturates and aromatics were found. A ratio between the lowest and the highest molecular weight of the vacuum residual oil saturate and aromatic fraction of 2.4 was found showing that the molecular weights of these SARA fractions are not fixed and can vary between 360 and 880 g/mole for the saturates, and 450 and 1080 g/mole for the aromatics. Assuming the same ratio in variation of molecular weights (MW) of the fractions resins and asphaltenes for the reviewed 41 vacuum residual oils suggests that the resins MW could vary in the range 800 ÷ 1800 g/mole and the asphaltenes MW may vary between 1000 and 3000 g/mole. The application of sophisticated analytical techniques showed a very big diversity in the species building the vacuum residual oils and different distribution of these species even for the same SARA fraction depending on the residual oil origin. The different approaches for “molecular reconstruction” of residual oils Monte Carlo (MC), Quadrature algorithm (QA), Entropy maximization (EM), quantitative structure-property relationship (QSPR), structure-oriented lumping (SOL), molecular type homologous series (MTHS) matrix, artificial neural network (ANN) and multiple linear regression (MLR) are reviewed. A conclusion is made that the advanced analytical and computational techniques are still an obligor to the chemical engineers working at the commercial residual oil conversion units who aim to optimize the conversion process performance.

This work presents characterization data and viscosity of 34 secondary vacuum gas oils (H-Oil gas oils, visbreaker gas oils, and fluid catalytic cracking slurry oils) with aromatic content reaching up to 100 wt.%. Inter-criteria analysis was employed to define the secondary VGO characteristic parameters which have an effect on viscosity. Seven published empirical models to predict viscosity of the secondary vacuum gas oils were examined for their prediction ability. The empirical model of Aboul-Seud and Moharam was found to have the lowest error of prediction. A modification of Aboul-Seoud and Moharam model by separating the power terms accounting for the effects of specific gravity and average boiling point improves the accuracy of viscosity prediction. It was discovered that the relation of slope of viscosity decrease with temperature enhancement for the secondary vacuum gas oil is not a constant. This slope increases with the average boiling point and the specific gravity augmentation, a fact that has not been discussed before.

This paper evaluates the influence of crude oil (vacuum residue) properties, the processing of fluid catalytic cracking slurry oil, and recycle of hydrocracked vacuum residue diluted with fluid catalytic cracking heavy cycle oil, and the operating conditions of the H-Oil vacuum residue hydrocracking on the quality of the H-Oil liquid products. 36 cases of operation of a commercial H-Oil® ebullated bed hydrocracker were studied at different feed composition, and different operating conditions. Intercriteria analysis was employed to define the statistically meaningful relations between 135 parameters including operating conditions, feed and products characteristics. Correlations and regression equations which related the H-Oil® mixed feed quality and the operating conditions (reaction temperature, and reaction time (throughput)) to the liquid H-Oil® products quality were developed. The developed equations can be used to find the optimal performance of the whole refinery considering that the H-Oil liquid products are part of the feed for the units: fluid catalytic cracking, hydrotreating, road pavement bitumen, and blending.

H-Oil vacuum gas oils obtained during hydrocracking of vacuum residual oils originated from the crudes Russian Export Blend, Basrah light, and Heavy Kazakh were cracked in a mixture with a hydrotreated vacuum gas oil in the LUKOIL Neftohim Burgas commercial fluid catalytic cracking (FCC) unit. Some of the H-Oil vacuum gas oils were also cracked in a laboratory FCC (ACE) unit. The results from the commercial and the laboratory tests showed that the laboratory FCC experiments in an ACE unit can be used to evaluate the effect of feed quality on the commercial FCC unit performance. The assumption that the conversion of a vacuum gas oil (VGO) blend in the fluid catalytic cracking could be considered as a linear combination of the conversion of the individual components made by other researchers was also confirmed in this study. The higher the hydrogen content in the vacuum residual oil of a crude is the higher the FCC conversion of the H-Oil VGO, obtained during hydrocracking of that high saturate vacuum residual oil, will be expected.

This work summarizes the results of multiple experiments performed in the LUKOIL Neftohim Burgas Research Laboratory related to the issue of high values of hot filtration test (HFT) of the residue H-Oil hydrocracking residual oil products. After the start-up of the new residue H-Oil hydrocracker in the LUKOIL Neftohim Burgas refinery during the second half of 2015 the values of the HFT of the vacuum tower bottom product varied between 0.01 and 8.7%. It was found that the vacuum residual oil feed source has a profound effect on the processes of sedimentation in the H-Oil hydrocracker. The processing of vacuum residual oils from Arab medium, Arab heavy, and Basrah light crudes reduced the sedimentation and allowed achievement of a higher conversion. The H/C ratios of asphaltenes from all studied feeds decreased after hydrocracking. However, the decrease of the H/C ratio was the least pronounced with the Basra light asphaltenes, while the H/C ratios of asphaltenes from the vacuum residual oils originating fr...

Data from assays of 244 crude oils (condensates, extra light, light, intermediate, and heavy crudes) were processed by the InterCriteria Analysis with the aim to investigate the relationships between bulk properties and fraction properties of the crude oils and the degree of similarity between them. It was found that except the crude bulk properties sulfur, Conradson carbon, and metals content all other studied crude bulk properties exhibited lack of statistically meaningful relations or presence of weak statistically meaningful relations with the crude fraction properties. The use of the InterCriteria Analysis showed that crudes with very similar properties could be identified when a large crude database is available. In this way based on a previous experience in oil refining a selection of potentially beneficial new crudes for processing in a refinery could be made.

Five empirical methods toestimate the content of aromatic, naphthenic, and paraffinic carbon and hydrogen content and the bulk properties were tested for prediction of aromatic structures content of 95 vacuum gas oils. The density demonstrated the highest correlation with the aromatic structures content among all other studied bulk properties and empirical parameters. The aromatic structures content could be predicted by a second order power law dependence on density with accuracy commensurable with the reproducibility of SARA analysis. The poly-nuclear aromatic structures content was also found to depend on the density and can be expressed by a linear function.

During start-up operations of the new residue ebullated bed H-Oil hydrocracking unit in the LUKOIL Neftohim Burgas refinery oil incompatibility was registered in the process of production of heavy fuel oil. Тhat was the reason for obtaining high sediment off-spec heavy fuel oil product. The oil incompatibility was observed in the process of blending of high saturate, low asphaltene, high colloidal stability H-Oil unconverted vacuum residue with the high aromatic, and relatively high asphaltene visbroken residue. The use of antifouling additive was found to decrease the sediment level in the heavy fuel oil. However, it was not capable of reducing the heavy fuel oil sediment content after chemical and thermal artificial aging of the fuel oil. Considerable amount of high aromatic fluid catalytic cracking heavy cycle oil was needed to reduce the off-spec heavy fuel oil sediment content to the specified max. limit of 0.1% sediments. After deasphaltization of the visbroken residue with n-heptane and blending of the visbroken deasphalted oil with the H-Oil unconverted vacuum residue in a ratio of 1:1 the sediment content of the heavy fuel oil blend dropped from 2.5% to 0.01%. This suggests that the lower solubility of the visbroken residue asphaltenes in the high saturate H-Oil unconverted vacuum residue was the reason for the oil incompatibility during the production of off-spec heavy fuel oil in the LUKOIL Neftohim Burgas refinery when both the H-Oil residue hydrocracker and the visbreaker were in operation.

Sixteen petroleum crudes and an imported atmospheric residue originating from Russia, Azerbaijan, Greece, Italy, Kuwait, Iraq, Iran, Saudi Arabia, Tunisia, and the USA have been processed in the LUKOIL Neftohim Burgas (LNB) refinery, and their effect on the ebullated bed vacuum residue H-Oil hydrocracking (EBVRHC) performance has been evaluated. The vacuum residue conversion in the LNB H-Oil EBVRHC varied between 55% and 82% depending on the crude blend processed in the LNB refinery. It has been established that among all vacuum residue SARA fractions during EBVRHC, the resins have the highest conversion, followed by the naphtheno-aromatics while the saturates show the lowest conversion. Depending on the petroleum crude origin the behaviour of the most problematic VR asphaltene fraction has been found to be different suggesting distinct propensity of the asphaltenes from the different petroleum crudes to participate in radical recombination reactions leading to the formation of additional amounts of core-condensed asphaltenes.

A rapid and simple method for the determination of benzene and oxygenates in petroleum by heart-cutting gas chromatography is reported. Experimental design was used to optimize the chromatographic resolution with a short analysis time by improving the injection volume, split ratio, oven temperature, and oven ramps, with seven Deans’ switching heart-cutting applications. The analyses were performed by internal standardization and seven oxygenates and benzene were determined within 20 min. The calibration curves were linear across the tested ranges. The developed method was validated; the precision and accuracy were lower than 2.0 and 2.8%, respectively. The uncertainty was between ±0.012 and ±0.04%.