Browsing by Author "Tavlieva M."

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    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.
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    Correlations of HTSD to TBP and Bulk Properties to Saturate Content of a Wide Variety of Crude Oils
    (2023-02-01) Stratiev D.; Dinkov R.; Tavlieva M.; Shishkova I.; Nikolov Palichev G.; Ribagin S.; Atanassov K.; Stratiev D.D.; Nenov S.; Pilev D.; Sotirov S.; Sotirova E.; Simeonov S.; Boyadzhieva V.
    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.
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    INHIBITING SEDIMENT FORMATION IN AN EXTRA LIGHT CRUDE OIL AND IN A HYDROCRACKED ATMOSPHERIC RESIDUE BY COMMERCIAL CHEMICAL ADDITIVES
    (2022-01-01) Stratiev D.; Shishkova I.; Tavlieva M.; Kirilov K.; Dinkov R.; Yordanov D.; Yankova L.; Toteva V.; Nikolova R.
    Extra light crude oil from Kazahstan and hydrocracked atmospheric residue from a commercial ebullated bed vacuum residue hydrocracker were investigated to reduce their sediment formation rate by employing 13 commercial chemical additives. Ten of the studied additives were based on the organic acid derivatives. Asphaltene dispersion test was applied in this study to define the most appropriate chemical additive and the optimum treating rate. The additives demonstrated different performance with the distinct oils. All organic acid derivative additives were capable of suppressing the sedimentation in the hydrocracked atmospheric residue, while not all of them were effective in decreasing the sediment formation in the extra light petroleum. The phosphoric acid and poly-iso-butylene succinimide based additives were effective in suppressing the sedimentation in the hydrocracked atmospheric residue while they promoted the formation of sediments in the extra light petroleum. The additive based on 1,2,4-trimethylbenzene was ineffective in decreasing the sedimentation in the hydrocracked atmospheric residue and slightly effective in the suppression of sediment formation in the extra light petroleum.