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This paper summarises the experience gained in LUKOIL Neftohim Burgas refinery with the production of road asphalt from blends containing straight run and hydrocracked vacuum residues. The effect of diluting of the bitumen blends with fluid catalytic cracking gas oils and H-Oil heavy vacuum gas oil (HVGO) and straight run vacuum gas oil (SRVGO) is discussed. The influence of sulphur treatment of the bitumen blends on oxidative ageing and H2S release is argued. The impact of bitumen softening point on the oxidation rate was found to be described by a power function. [ABSTRACT FROM AUTHOR]

Data from 26 vacuum residue hydrocracking (VR HC) laboratory and commercial experiments were used to model VR HC selectivity curves employing empirical functions and boundary conditions and applying the non-linear least-squares methods. It was found that VR HC products: gas, naphtha, and kerosene can be very well modelled as stable primary and secondary products. The VGO can be modelled as an unstable primary product, while the atmospheric gas oil is best modelled as an unstable primary and secondary product. The diesel yield in laboratory and commercial VR HC conditions is very well modelled as a stable primary and secondary product. The proposed empirical functions and the non-linear least-squares method could be used to test whether a VR HC product is a result of primary and secondary reactions and whether this product further participates in secondary reactions with the progress of the hydrocracking process. [ABSTRACT FROM AUTHOR]

Evolution of ebullated bed industrial hydrocracking atmospheric and vacuum tower bottoms from 2015 (start-up) until now is analysed in terms of applicability of residue for production of road pavement bitumen. Increased conversion in this money-maker (cheap vacuum residue feed and marginal naphtha and gasoil products) unit is in line with the driving force for increased refinery profitability. Another advantage of higher conversion is the lower content of residue, which is the main source for hardly trade off fuel oil. Together with positive effects, conversion reveals some disadvantages in terms of VTB properties. Residue becomes harder and it was found that penetration depends from softening point through the whole conversion range of 65-93%, obtained at industrial H-Oil unit, in the following exponential dependence: Penetration at 25oC = 6964.6e-0.093×Softening point. Deterioration of Fraass breaking point of VTB (Vacuum tower bottom from hydrocracking of vacuum residue unit) is directly related to the higher VTB density at increased conversion. [ABSTRACT FROM AUTHOR]

Sodium content in the vacuum residue was found an issue in the LUKOIL Neftohim Burgas refinery because it led to an increased level of Na on the ebullated bed vacuum residue H-Oil hydrocracking catalyst and embarrassed the use of molecularly dispersed nano catalyst HCAT. It was found that the sodium content in the vacuum residue depended on the efficiency of crude oil desalting unit and on the NaOH injection rate to the desalting crude oil to control the level of chlorides on the top of the distillation columns in the crude distillation unit. Maintaining crude oil desalting efficiency of about 90% and optimisation of NaOH injection can provide vacuum residue sodium content in the acceptable level of 15-20 ppm. [ABSTRACT FROM AUTHOR]

Rheological property viscosity of H-Oil Unconverted hydrocracked vacuum residue (HCVR) has been followed from the start-up of the H-Oil hydrocracker in LNB refinery in 2015 till June of 2020. It has varied by a factor of ten while the vacuum residue conversion has varied between 58 and 88%. Increasing H-Oil vacuum residue conversion is associated by increasing of the unconverted hydrocracked vacuum residue viscosity, softening point and Fraass breaking point. The addition of Fluid catalytic cracking slurry oil (FCC SLO) to the HCVR decreases the Fraass breaking point but worsens oxidative ageing and increases the loss of mass. The addition of sulphur in amount of 1.5% to the blends HCVR-FCC SLO-OSRVR (Oxidised straight run vacuum residue) decreases the oxidative ageing rate and increases the softening point of the treated bitumen blends due to C7 asphaltene content increasing. The effect of sulphur addition to the bitumen blends on oxidative ageing rate decreasing and softening point augmentation linearly diminishes with amplification of the OSRVR content in the road bitumen blend. [ABSTRACT FROM AUTHOR]

The restrictive factor for maximisation of Unconverted vacuum tower bottom (UVTB) from ebullated bed hydrocracking process - H-Oil technology in bitumen production is its low resistance to hardening, determined by using a Rolling thin film oven (RTFO). The limitation in LUKOIL Neftohim Burgas (LNB) industrial production is up to 37% UVTB in blends with air blown straight run vacuum residue (SRVR). The intention to increase UVTB content in bitumen blend passes through a dedicated evaluation of available approaches for their effectiveness and contribution for redirecting hydrocracking residue from low cost, hard to produce, high sulphur fuel oil to more valuable bitumen production. Several chemical components are tested and neither Heavy vacuum gas oil (HVGO) from hydrocracking of vacuum residue, nor slurry oil from Fluid catalytic cracking (FCC), nor asphaltene fraction from solvent deasphalting, nor antioxidant can inhibit softening point (SP) measured by the ring and ball (R&B) method increase due to resistance to hardening at 163°C test. A slightly positive result is assigned to SRVR addition but even that it can not lower the SP increase of UVTB to bellow specification required value of 9°C. Two substances reveal significant reduction in UVTB SP increase: 8% atactic polypropylene (aPP) is capable to obtain 5.4°C and elemental sulphur - 6°C with only 0.23% additionally bonded sulphur. [ABSTRACT FROM AUTHOR]

Little is published about the crackability of the heavy oils derived from the ebullated bed vacuum residue hydrocracking. That is why eight heavy oils derived from a commercial H-Oil hydrocracker and from laboratory residual oil hydrocracking units were catalytically cracked on a commercial Fluid catalytic cracking (FCC) catalyst in a laboratory Advanced cracking evaluation (ACE) unit. The cracking experiments were performed at Catalyst-to-oil (CTO) ratio variation between 3.5 and 7.5 wt./wt. at a reaction temperature of 527°C. Along with the H-Oil derived heavy oils virgin Vacuum gas oils (VGOs) and a blend of virgin VGO and H-Oil VGO were also cracked. It was found that the dominant factor controlling the FCC feed crackability is the nitrogen content. It was also found that the reaction order of the FCC feedstocks can vary between 1.35 and 2.15. The lower reactive high nitrogen containing H-Oil derived VGO exhibits a lower reaction order and higher conversion dependence on the CTO ratio alteration. While the conversion was found to depend on the nitrogen content, the coke on the catalyst was found to correlate with the density of the studied 12 FCC feedstocks. [ABSTRACT FROM AUTHOR]

26 vacuum residual oils (VROs) were characterised and hydrocracked in the LUKOIL Neftohim Burgas H-Oil ebullated bed unit. The VRO properties: contents of saturates, sulphur, nitrogen, and asphaltenes were found to affect both feed reactivity and its propensity to form sediments during hydrocracking. The saturates, nitrogen and asphaltenes contents negatively affected feedstock reactivity and increased the feedstock propensity to form sediments. The sulphur content had a positive effect on both conversion increase and sediment content decrease. The observed results are in line with the reports from other researchers concerning the effect of saturates, nitrogen and asphaltenes contents on reactivity and sediment formation propensity. [ABSTRACT FROM AUTHOR]

This work deals with reactivity of heavy oil SARA (saturates, aromatics, resins, asphaltenes) fractions during thermal and catalytic cracking, and the relations of heavy oil SARA composition to conversion level in both thermal and catalytic cracking. It was found that reactivity decreases in the order: saturates ˃ aromatics ˃ resins ˃ asphaltenes. The highest reactivity of the heavy oil saturate fraction was due to its lowest activation energy. During thermal cracking based processes, a definite order in the reactivity of the different SARA fractions was not observed. The reason for the disorder in the thermal reactivity of the different SARA fractions might be rooted in the lack of order in the content of the free radical accelerators naturally presenting in the different heavy oil SARA fractions. We suppose that in the presence of free radical accelerators like peroxides for example the higher hydrogen content heavy oils and oil fractions would achieve a higher thermal conversion. [ABSTRACT FROM AUTHOR]

The modern heavy oil conversion technologies are generally based on two processes: catalytic cracking and thermal cracking. They are the backbone of the modern refining business. Considering that the feedstock quality is the single variable that most affects the heavy oil conversion unit performance, and that the heavy oils are very complex mixtures, consisting of myriad components we have focused on the published results about catalytic and thermal cracking of individual hydrocarbons (n-alkanes, cycloalkanes, alkyl aromatics and polynuclear aromatics). The catalytic cracking proceeds through carbocation chain reactions, while the thermal cracking based processes proceed via free radical chain reactions. The reactivity of different hydrocarbon classes in terms of catalytic and thermal cracking increase with enlargement of molecular weight and follows the order: n-alkanes (alkanes) ˂ cyclic alkanes (naphthenes) ˂ alkylbenzenes ˂ naphtheno-aromatics. The polynuclear aromatic hydrocarbons are the least reactive individual hydrocarbons. [ABSTRACT FROM AUTHOR]

This work presents a study to detect potential source of contamination of cooling water in the refinery plants by applying the methods of gas chromatography. This study is conducted to analyse the cooling water heat exchange equipment performance of two refinery units, bound in a common cooling water system and the water supply unit. Main pollutants of cooling water are C6-C12 arenes, C8-C17 n-alkanes and iso-C15-iso-C18 hydrocarbons. The concentration of individual contaminants varied from < 0.1 to 31 mg/l. It was found that the total pollutants concentrations were equal to 420 mg/l. Characteristic parameters benzene/toluene, benzene/xylenes, toluene/ethylbenzene, Σ (odd alkanes)/Σ (even alkanes), iso-C15/n-C14 and iso-C16/n-C15 were the most important ratios and they were used for identification of the source of the contamination of cooling water system. Comparing chromatographic profiles and interpreting quantitative results, the source of contamination of cooling water system was identified. [ABSTRACT FROM AUTHOR]

Liquid product from pyrolysis of used tyres has been fractionated in naphtha and residual fraction in a rectification column with 15 theoretical trays. Gas chromatographic analysis of the naphtha indicated that it consisted of: normal + iso paraffins = 7.1%; normal + iso olefins = 8.9%; normal + iso di-olefins = 7.0%; cyclic paraffins = 11.7%; cyclic olefins = 18.6%; cyclic di-olefins = 1.4%; aromatics = 35.6%. The naphtha sulphur was 0.48% from which 0.2% was mercaptane sulphur and the remaining was thiophene sulphur. The most abundant individual hydrocarbon in naphtha was found to be limonene (7.65%). The naphtha research octane number was 93.6, and the motor octane number was 80.0. The physical and chemical properties (sp.gr.=0.937, gross calorific value = 41.4 MJ/kg) of the residual fraction indicated that it can be used as a low sulphur fuel oil (0.81% sulphur) or marine oil. [ABSTRACT FROM AUTHOR]

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 Δ T of the 1st reactor to the Δ T 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., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

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., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

The LUKOIL Neftohim Burgas vacuum residue hydrocracking has increased the vacuum residue conversion from 55 to 93% as a result of a proper feed selection, optimal catalyst condition, and the use of a Mo nanodispersed catalyst. It was found that the feed colloidal instability index estimated from the feed saturates, aromatics, resins, and asphaltenes (SARA) data negatively correlated with the conversion. Correlations based on the use of the nonlinear least-squares method, which relates the density to the aromatic structure contents for the straight run and hydrocracked vacuum residues, were developed. Intercriteria analysis was applied to evaluate the relations between the different properties of the straight run and the hydrocracked vacuum residual oils. The density of the hydrocracked vacuum residue measured by dilution with toluene was found to strongly correlate with the conversion, Conradson carbon content, softening point, and Fraasss breaking point., Competing Interests: The authors declare no competing financial interest., (© 2020 American Chemical Society.)

A microcoulometric method is described for the determination of organic-halide pollutants at 2-2000 microg/L in natural, drinking, waste, and treated waters. The conditions for the adsorption of organic halides, using a microcolumn with activated charcoal-and for the desorption of inorganic halides-as well as for the pyrolysis process, were optimized for the successful determination of priority organic halide pollutants. An appropriate criterion was proposed to stop the desorption step. The mean recovery was 100.3%, and the mean relative standard deviation was 9.9%. The detection limit based on 3 times the standard deviation of the blank sample was 2 microg/L.