Simeon Ribagin

Dr. Simeon Ribagin


Research Focus & Metrics

Academic Career Length

12Years (2015-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
Open access
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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.


22 July 2021 in Resources
Verified
Journal Article
Open access
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ISIvelina Shishkova
Ivelina Shishkova
Dicho StratievDicho Stratiev
Dicho Stratiev
MTMariana P. Tavlieva
Mariana P. Tavlieva
RDRosen Kotzev Dinkov
Rosen Kotzev Dinkov
Dobromir Ivanov YordanovDobromir Ivanov Yordanov
Dobromir Ivanov Yordanov
SNSvetoslav Nenov
Svetoslav Nenov
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.

9 July 2021 in Resources
Verified
Journal Article
Open access
PDF file
Dicho StratievDicho Stratiev
Dicho Stratiev
ISIvelina Shishkova
Ivelina Shishkova
RDRosen Kotzev Dinkov
Rosen Kotzev Dinkov
IPIvan P. Petrov
Ivan P. Petrov
IKIliyan V. Kolev
Iliyan V. Kolev
KZKamen Zlatanov
Kamen Zlatanov
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.

27 May 2021 in Processes
Verified
Journal Article
Open access
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Dicho StratievDicho Stratiev
Dicho Stratiev
ISIvelina Shishkova
Ivelina Shishkova
RDRosen Kotzev Dinkov
Rosen Kotzev Dinkov
IPIvan Petrov Petrov
Ivan Petrov Petrov
IKIliyan V. Kolev
Iliyan V. Kolev
SNSvetoslav Nenov
Svetoslav Nenov
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.

20 July 2021
Verified
Book Chapter
Closed access
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SRSimeon Ribagin
Simeon Ribagin
VLVelislava Lyubenova
Velislava Lyubenova