Browsing by Author "Ivanov M."
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Item Alternative Options for Ebullated Bed Vacuum Residue Hydrocracker Naphtha Utilization(2023-12-01) Stratiev D.; Shishkova I.; Ivanov M.; Dinkov R.; Toteva V.; Angelova D.; Kolev I.; Tavlieva M.; Yordanov D.The vacuum residue hydrocracker naphtha (VRHN) is a chemically unstable product that during storage changes its colour and forms sediments after two weeks. It cannot be directly exported from the refinery without improving its chemical stability. In this research, the hydrotreatment of H-Oil naphtha with straight run naphtha in a commercial hydrotreater, its co-processing with fluid catalytic cracking (FCC) gasoline in a commercial Prime-G+ post-treater, and its co-processing with vacuum gas oil (VGO) in a commercial FCC unit were discussed. The hydrotreatment improves the chemical stability of H-Oil naphtha and reduces its sulphur content to 3 ppm. The Prime-G+ co-hydrotreating increases the H-Oil naphtha blending research octane number (RON) by 6 points and motor octane number (MON) by 9 points. The FCC co-cracking with VGO enhances the blending RON by 11.5 points and blending MON by 17.6 points. H-Oil naphtha conversion to gaseous products (C1–C4 hydrocarbons) in the commercial FCC unit was found to be 50%. The use of ZSM 5 containing catalyst additive during processing H-Oil naphtha showed to lead to FCC gasoline blending octane enhancement by 2 points. This enabled an increment of low octane number naphtha in the commodity premium near zero sulphur automotive gasoline by 2.4 vol.% and substantial improvement of refinery margin. The processing of H-Oil naphtha in the FCC unit leads also to energy saving as a result of an equivalent lift steam substitution in the FCC riser.Item COMMERCIAL AND LABORATORY EXPERIENCE WITH CATALYTIC CRACKING OF STRAIGHT RUN HYDROTREATED VACUUM GAS OIL AND H-OIL GAS OILS(2022-01-01) Stratiev D.; Shishkova I.; Ivanov M.; Petrov I.; Atanassova V.; Ribagin S.; Atanassov K.; Toteva V.; Stratiev D.This study presents for the first time an investigation of fluid catalytic cracking of 100 % H-vacuum gas oil at a commercial FCC unit. 100 % straight run hydrotreated vacuum gas oil (HTSRVGO) and 100 % H-vacuum gas oil have been cracked in the commercial LUKOIL Neftohim Burgas fluid catalytic cracking and in a laboratory confined ebbulated bed ACE catalytic cracking unit. The relations between the operating conditions of the commercial FCC unit and conversion level in both cases 100 % HTSRVGO and its blends with H-Oil VGO were investigated using intercriteria analysis. Multiple regressions were developed to quantify the effect of the operating conditions as well as quantity and quality of H-Oil VGO on conversion level in the commercial FCC unit. ACE laboratory tests with feed containing about 20 % H-Oil VGO at different catalyst-to-oil ratios and reaction temperature were performed and the results are discussed.Item Commercial Ebullated Bed Vacuum Residue Hydrocracking Performance Improvement during Processing Difficult Feeds(2023-03-01) Georgiev B.E.; Stratiev D.S.; Argirov G.S.; Nedelchev A.; Dinkov R.; Shishkova I.K.; Ivanov M.; Atanassov K.; Ribagin S.; Nikolov Palichev G.; Nenov S.; Sotirov S.; Sotirova E.; Pilev D.; Stratiev D.D.The Urals and Siberian vacuum residues are considered difficult to process in the ebullated bed hydrocracking because of their increased tendency to form sediments. Their achievable conversion rate reported in the literature is 60%. Intercriteria analysis was used to assess data from a commercial vacuum residue hydrocracker during processing blends from three vacuum residues: Urals, Siberian Light, and Basra Heavy. The analysis revealed that the main contributors to conversion enhancement is hydrodemetallization (HDM) and the first reactor ΔT augmentation. The increase of HDM from 40 to 98% and the first reactor ΔT (ΔT(R1)) from 49 to 91 °C were associated with a vacuum residue conversion enhancement of 62.0 to 82.7 wt.%. The developed nonlinear regression prediction of conversion from HDM and ΔT(R1) suggests a bigger influence of ΔT(R1) enhancement on conversion augmentation than the HDM increase. The intercriteria analysis evaluation revealed that the higher first reactor ΔT suppresses the sediment formation rate to a greater extent than the higher HDM. During processing Basrah Heavy vacuum residue, a reduction in hydrodeasphaltization (HDAs) from 73.6 to 55.2% and HDM from 88 to 81% was observed. It was confirmed that HDM and HDAs are interrelated. It was found that the attainment of conversion of 80 wt.% and higher during processing Urals and Siberian Light vacuum residues is possible when the HDM is about 90% and LHSV ≤ 0.19 h−1.Item Influence of carbon black structure and specific surface area on the mechanical and dielectric properties of filled rubber composites(2011-01-01) Al-Hartomy O.A.; Al-Solamy F.; Al-Ghamdi A.; Dishovsky N.; Ivanov M.; Mihaylov M.; El-Tantawy F.Natural rubber based composites have been prepared using various amounts of two fillers: conventional Corax N220 carbon black or electrically conductive carbon black Printex XE-2B which has a very high specific surface area. The composites have been studied by dynamic mechanical thermal analysis, dielectric thermal analysis and SEM. It has been established that all vulcanizates investigated are in the glass state in the -80°C to -40°C interval. The storage modulus increases with the increasing filler content in the -40°C to +80°C interval when the vulcanizates are in the highly elastic state. DETA shows that the increase in filler content leads to an increase in the dielectric permittivity (ε′). ε′ also increases with temperature increasing. Higher frequency causes a decrease of ε′ values which becomes more pronounced with the increasing filler content. Obviously, when the content of Printex XE-2B carbon black in the vulcanizates is higher than 7.5 phr, the percolation threshold is reached and the ε′ values increase up to 102-104. The ε′ values for the vulcanizates comprising 20 and 50 phr Corax N220 carbon black are measurable with those for the vulcanizates comprising 5 and 10 phr Printex XE-2B carbon black respectively. The results obtained could be explained by the difference in the structure and specific surface area of the two types of carbon black - Printex XE-2B and Corax N220. Copyright © 2011 Omar A. Al-Hartomy et al.Item Influence of carbon black structure and specific surface area on the mechanical and dielectric properties of filled rubber composites(2011-01-01) Al-Hartomy O.A.; Al-Solamy F.; Al-Ghamdi A.; Dishovsky N.; Ivanov M.; Mihaylov M.; El-Tantawy F.Natural rubber based composites have been prepared using various amounts of two fillers: conventional Corax N220 carbon black or electrically conductive carbon black Printex XE-2B which has a very high specific surface area. The composites have been studied by dynamic mechanical thermal analysis, dielectric thermal analysis and SEM. It has been established that all vulcanizates investigated are in the glass state in the -80°C to -40°C interval. The storage modulus increases with the increasing filler content in the -40°C to +80°C interval when the vulcanizates are in the highly elastic state. DETA shows that the increase in filler content leads to an increase in the dielectric permittivity (ε′). ε′ also increases with temperature increasing. Higher frequency causes a decrease of ε′ values which becomes more pronounced with the increasing filler content. Obviously, when the content of Printex XE-2B carbon black in the vulcanizates is higher than 7.5 phr, the percolation threshold is reached and the ε′ values increase up to 102-104. The ε′ values for the vulcanizates comprising 20 and 50 phr Corax N220 carbon black are measurable with those for the vulcanizates comprising 5 and 10 phr Printex XE-2B carbon black respectively. The results obtained could be explained by the difference in the structure and specific surface area of the two types of carbon black - Printex XE-2B and Corax N220. Copyright © 2011 Omar A. Al-Hartomy et al.Item Role of Catalyst in Optimizing Fluid Catalytic Cracking Performance during Cracking of H-Oil-Derived Gas Oils(2021-03-23) Stratiev D.; Shishkova I.; Ivanov M.; Dinkov R.; Georgiev B.; Argirov G.; Atanassova V.; Vassilev P.; Atanassov K.; Yordanov D.; Popov A.; Padovani A.; Hartmann U.; Brandt S.; Nenov S.; Sotirov S.; Sotirova E.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% Δcoke 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.Item Roles of Catalysts and Feedstock in Optimizing the Performance of Heavy Fraction Conversion Processes: Fluid Catalytic Cracking and Ebullated Bed Vacuum Residue Hydrocracking(2024-09-01) Stratiev D.; Shishkova I.; Argirov G.; Dinkov R.; Ivanov M.; Sotirov S.; Sotirova E.; Bureva V.; Nenov S.; Atanassov K.; Stratiev D.; Vasilev S.Petroleum refining has been, is still, and is expected to remain in the next decades the main source of energy required to drive transport for mankind. The demand for automotive and aviation fuels has urged refiners to search for ways to extract more light oil products per barrel of crude oil. The heavy oil conversion processes of ebullated bed vacuum residue hydrocracking (EBVRHC) and fluid catalytic cracking (FCC) can assist refiners in their aim to produce more transportation fuels and feeds for petrochemistry from a ton of petroleum. However, a good understanding of the roles of feed quality and catalyst characteristics is needed to optimize the performance of both heavy oil conversion processes. Three knowledge discovery database techniques—intercriteria and regression analyses, and artificial neural networks—were used to evaluate the performance of commercial FCC and EBVRHC in processing 19 different heavy oils. Seven diverse FCC catalysts were assessed using a cascade and parallel fresh catalyst addition system in an EBVRHC unit. It was found that the vacuum residue conversion in the EBVRHC depended on feed reactivity, which, calculated on the basis of pilot plant tests, varied by 16.4%; the content of vacuum residue (VR) in the mixed EBVRHC unit feed (each 10% fluctuation in VR content leads to an alteration in VR conversion of 1.6%); the reaction temperature (a 1 °C deviation in reaction temperature is associated with a 0.8% shift in VR conversion); and the liquid hourly space velocity (0.01 h-1 change of LHSV leads to 0.85% conversion alteration). The vacuum gas oil conversion in the FCC unit was determined to correlate with feed crackability, which, calculated on the basis of pilot plant tests, varied by 8.2%, and the catalyst ΔCoke (each 0.03% ΔCoke increase reduces FCC conversion by 1%), which was unveiled to depend on FCC feed density and equilibrium FCC micro-activity. The developed correlations can be used to optimize the performance of FCC and EBVRHC units by selecting the appropriate feed slate and catalyst.Item Validation of Diesel Fraction Content in Heavy Oils Measured by High Temperature Simulated Distillation and Physical Vacuum Distillation by Performance of Commercial Distillation Test and Process Simulation(2022-11-01) Stratiev D.; Shishkova I.; Ivanov M.; Dinkov R.; Argirov G.; Vasilev S.; Yordanov D.A gas chromatography high temperature simulation distillation (HTSD: ASTM D 7169), and physical vacuum distillation (ASTM D 1160) were employed to characterize H-Oil vacuum distillates, straight run vacuum distillates, and hydrotreated vacuum distillates with the aim to determine their content of diesel fraction and evaluate the possible higher extraction of diesel fraction from the heavy oils. The ASTM D 7169 reported about six times as high diesel fraction content in H-Oil heavy distillates as that reported by the ASTM D 1160 method. Performing a commercial distillation column test along with a simulation of the column operation using data of both ASTM methods and a software process simulator revealed that the HTSD is the more valid method for proper determination of the diesel fraction content in heavy oils. The software process simulation of the commercial distillation column operation suggests that the HTSD could be considered as a true boiling point distillation method for heavy oils. The separation of the diesel fraction from the H-Oil heavy distillates quantified by the HTSD could deliver oil refining profit improvement in the amount of six digits USD per year.