Dicho Stratiev

Prof. Dr. Dicho Stratiev

1. LUKOIL Neftohim Burgas, 8104 Burgas, Bulgaria
+1
orcid

Research Focus & Metrics

Academic Career Length

13Years (2014-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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20 October 2022 in Energies
Verified
Journal Article
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ISIvelina Shishkova
Ivelina Shishkova
Dicho StratievDicho Stratiev
Dicho Stratiev
IKIliyan V. Kolev
Iliyan V. Kolev
SNSvetoslav Nenov
Svetoslav Nenov
DNDimitar Nedanovski
Dimitar Nedanovski
SRSimeon Ribagin
Simeon Ribagin
252 literature sources and about 5000 crude oil assays were reviewed in this work. The review has shown that the petroleum characterization can be classified in three categories: crude oil assay; SARA characterization; and molecular characterization. It was found that the range of petroleum property variation is so wide that the same crude oil property cannot be measured by the use of a single standard method. To the best of our knowledge for the first time the application of the additive rule to predict crude oil asphaltene content from that of the vacuum residue multiplied by the vacuum residue TBP yield was examined. It was also discovered that a strong linear relation between the contents of C5-, and C7-asphaltenes in crude oil and derived thereof vacuum residue fraction exists. The six parameter Weibull extreme function showed to best fit the TBP data of all crude oil types, allowing construction of a correct TBP curve and detection of measurement errors. A new SARA reconstitution approach is proposed to overcome the poor SARA analysis mass balance when crude oils with lower density are analyzed. The use of a chemometric approach with combination of spectroscopic data was found very helpful in extracting information about the composition of complex petroleum matrices consisting of a large number of components.

3 December 2015 in Energy & Fuels
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Journal Article
Closed access
Dicho StratievDicho Stratiev
Dicho Stratiev
ISIvelina Shishkova
Ivelina Shishkova
ANAngel Nedelchev
Angel Nedelchev
KKKiril Kirilov
Kiril Kirilov
ENEkaterina Nikolaychuk
Ekaterina Nikolaychuk
Krassimir AtanassovKrassimir Atanassov
Krassimir Atanassov

19 February 2015 in Energy & Fuels
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Journal Article
Closed access
Dicho StratievDicho Stratiev
Dicho Stratiev
IMIvaylo Marinov
Ivaylo Marinov
RDRosen Dinkov
Rosen Dinkov
ISIvelina Shishkova
Ivelina Shishkova
IVIlian Velkov
Ilian Velkov
NRNikolay Rudnev
Nikolay Rudnev

1 April 2016 in Fuel
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Journal Article
Closed access
Dicho StratievDicho Stratiev
Dicho Stratiev
ISIvelina Shishkova
Ivelina Shishkova
TTTania Tsaneva
Tania Tsaneva
MMMagdalena Mitkova
Magdalena Mitkova
DYDobromir Yordanov
Dobromir Yordanov

12 March 2021 in ACS Omega
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Journal Article
Open access
Dicho StratievDicho Stratiev
Dicho Stratiev
ISIvelina Shishkova
Ivelina Shishkova
MIMihail Ivanov
Mihail Ivanov
RDRosen Kotzev Dinkov
Rosen Kotzev Dinkov
BGBorislav Georgiev
Borislav Georgiev
ESEvdokia Sotirova
Evdokia Sotirova
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.

14 December 2020 in ACS Omega
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Journal Article
Open access
Dicho StratievDicho Stratiev
Dicho Stratiev
SNSvetoslav Nenov
Svetoslav Nenov
ISIvelina Shishkova
Ivelina Shishkova
BGBorislav Georgiev
Borislav Georgiev
GAGeorgi Argirov
Georgi Argirov
KAKrassimir Atanassov
Krassimir Atanassov
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.