Browsing by Author "Stanulov K."

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    EFFECT OF COMMERCIAL ADDITIVES TO REDUCE SEDIMENT FORMATION IN THE EBULLATED BED VACUUM RESIDUE H-OIL HYDROCRACKING
    (2020-01-01) Toteva V.; Stratiev D.; Shishkova I.; Nikolaychuk E.; Stanulov K.; Yordanov D.
    Ten H-Oil residual oils and eleven commercial additives inhibiting the asphaltene agglomeration were explored in this work by employing two tests: hot filtration test (HFT) and asphaltene dispersant test (ADT). It was found that the tendency to form sediments from the asphaltenes in the H-Oil residual oils was different for the distinct feed blends processed in the LNB H-Oil vacuum residue hydrocracker. The performance of the additives was found to be specific to the alloyed H-Oil residual oils. The additive based on the polyisobuthylene succinimide was found to be capable of reducing the sediment content in the H-Oil residual oils produced from all feedstock blends studied in this work. The efficiency of its performance however was different for the studied residual oils being the highest for the residual oil obtained from the feedstock blend 70 % Urals/30 % El Bouri (with the highest tendency to form sediment). This additive has also good efficiency against the H-Oil residual oil obtained from the feed 100 % Urals (with lower tendency to form sediment) but diluted with the high aromatic heavy cycle oil from fluid catalytic cracking.
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    Gas chromatography-mass spectrometry for characterization of liquid products from pyrolysis of municipal waste and spent tyres
    (2015-12-01) Pavlova A.; Stratiev D.; Mitkova M.; Stanulov K.; Dishovsky N.; Georgiev K.
    Liquid products produced from two different types of waste pyrolysismunicipal wastes and spent tyre wastes are investigated using gas chromatography- mass spectrometry. This method has been applied for detailed identification of composition of the samples. The components were characterized in terms of their Kovts retention indices on a PONA capillary column. The obtained analytical data were successfully used for the characterization of the samples. More than three hundred compounds were detected. The liquid products were complex mixtures, composed mainly of C4-C12 compounds. The examination of the selected m/z values very clearly indicates the existence of the different groups of compounds. With a lot of olefins content (31.9%), followed by aromatics (20.0%), paraffins (17.3%), and naphthenes (7.5%), it is described as the liquid product from pyrolysis of municipal solid wastes. The aromatic compounds in liquid product from pyrolysis of spent tyre wastes have the highest concentration (33.5%), and they are followed by naphthenes (28.6%), olefins (19.2%), and paraffins compounds (7.0%). The present study has shown that the pyrolysis of municipal waste and spent tyres can be used as a means for reduction of environmental pollution and production of liquid product which could be used as a fuel source.
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    OPTIMIZATION OF THE OXIDATIVE DESULPHURIZATION OF HEAVY GAS OIL
    (2020-01-01) Toteva V.; Stanulov K.; Shishkova I.; Stratiev D.
    The investigation of production and application of environmentally friendly fuels has intensified because of the legislation requiring an increased control of the greenhouse gas emissions. Stringent rules have been introduced to decrease the sulphur content of the liquid fuels to an ultra-low level, which in turn makes the desulphurization technologies development an important research goal. The hydrodesulphurization (HDS) is the current industrial method for fuels sulphur removal. The objective of the present study is to decrease the sulphur content of heavy gas oil by oxidation-extraction desulphurization which is one of the alternative methods which are aimed at. An adequate mathematical model is developed on the ground of a planned experiment approach which describes the effect of a number of factors (a temperature, contact time, and a peroxide-to-formic acid molar ratio) on the rate of sulphur content decrease. The optimal values of the variables are found to provide sulphur decrease in the heavy gas oil raffinates of up to 87 %. The process is monitored by FTIR and NMR spectroscopy, and gas chromatography equipped with sulphur chemiluminescence detector (SCD).