Viscosity of characterized visbroken heavy oils

Márquez, Andrés L.; Schoeggl, F. F.; Taylor, Shawn D.; Hay, Grant; Yarranton, Harvey W.

doi:10.1016/j.fuel.2020.117606

Cited by 15 publications

(30 citation statements)

References 70 publications

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“…Densities of the WC-B-A3 and WC-B-B2(2) bitumens were measured elsewhere. , Densities of the WC-B-B2(1) bitumen and for mixtures of each bitumen from Table with n -heptane and n -pentane were measured in this study at 21 °C and atmospheric pressure using an Anton Paar DMA 4500M density meter. The procedure for the density measurements is reported elsewhere .…”

Section: Experimental Methodsmentioning

confidence: 99%

Settling of Asphaltene Aggregates inn-Alkane Diluted Bitumen

et al. 2019

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The settling rate of asphaltene aggregates is a key design parameter for partial deasphalting processes, and yet few data and models are available for these systems. The settling rates of asphaltene aggregates were measured in two Western Canadian bitumens diluted with n-heptane or n-pentane at 21 °C and atmospheric pressure. The density and viscosity of the mixtures, the size distributions of the aggregates, and the fractal dimensions of the aggregates were also measured. The asphaltene aggregates settled as a zone, that is, all aggregates settled at the same rate. The settling rates increased with increasing n-alkane content, reached a maximum at approximately 75 wt % n-alkane and then decreased at higher dilutions. The maximum settling rate corresponded to the maximum aggregate diameter and fractal dimension. The maximum settling rate in n-pentane diluted bitumen was 2 orders of magnitude greater than in the same bitumen diluted with n-heptane. The difference was attributed to the lower density and viscosity of the medium, larger aggregates, and higher fractal dimensions in n-pentane versus n-heptane. The settling rates were modeled with Stokes' law modified to include the fractal dimension of the aggregates. Since zone settling was observed, the settling rate was determined from a single average diameter applied to all of the aggregates. The Sauter mean diameter was found to provide the most consistent results for the diluted bitumen systems in this study. No other form of hindering was required to match the data. The model matched the measured settling rates to within 20% of the maximum settling rate. The model is sensitive to the fractal dimension of the aggregates, and therefore precise determination of the fractal dimension is critical or it must be tuned to match the settling data.

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Section: Experimental Methodsmentioning

confidence: 99%

Settling of Asphaltene Aggregates inn-Alkane Diluted Bitumen

et al. 2019

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“… a VR visbreaking without additives was not carried out due to the inability of the pump to pump such a high-viscosity feed into the reactor. b Coke on the reactor walls. c Conversion was calculated based on ref . …”

Section: Resultsmentioning

confidence: 99%

“…The coking tendencies of various vacuum residues during visbreaking, which depend on the time and temperature of exposure, have been the subject of several studies. ,− An increase in the harshness of the visbreaking conditions speeds up the conversion. It leads to the formation of carbon structures without hydrogen, which enter into condensation and polymerization reactions generating insoluble polycondensed structures, ultimately leading to coke formation.…”

Section: Introductionmentioning

confidence: 99%

Application of Ethylene Tar as an Additive in Visbreaking of Petroleum Vacuum Residue

et al. 2021

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The byproduct of ethylene tar has a high content of mono-, bi-, and polycyclic aromatic compounds, as well as cycloalkenes, including aromatic cycloalkenes. This paper evaluates the prospects of using ethylene tar as an additive in the visbreaking process of vacuum residue. A series of experiments on visbreaking of vacuum residue with additives of various refinery streams and ethylene tar were performed in a laboratory flow reactor. As a result of a comparative study of the composition of vacuum residue visbreaking products by different methods, it was shown that the use of ethylene tar compared with kerosene, light cycle oil, and heavy cycle oil allows an increased yield of the target product with a higher proportion of aromatic hydrocarbons. A comparative analysis of the characteristics of asphaltenes and resins of visbreaking products indicates a general trend of changes in the process of visbreaking vacuum residue with refinery streams and ethylene tar. A comparison of the colloidal instability index showed that the use of ethylene tar allows attainment of a more stable visbreaking product concerning refinery streams as additives.

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“…The densities and viscosities of the oil samples at 20 °C provided in Table were measured previously and are reported elsewhere. − The C7-asphaltene ( n -heptane insoluble asphaltenes) and C5-asphaltene ( n -pentane insoluble) contents of the oil samples were determined using the gravimetric method described by Alboudwarej et al and are reported in Table . Asphaltene and solid compositions of the WC-B-A0 sample were originally reported by Alboudwarej et al…”

Section: Methodsmentioning

confidence: 99%

Effect of Air on the Kinetics of Asphaltene Precipitation from Diluted Crude Oils

et al. 2019

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The kinetics of asphaltene precipitation was investigated for five crude oils diluted with n-heptane at 21 °C in air and nitrogen atmospheres. The onset of precipitation, defined as the precipitant (n-heptane) content at which detectable asphaltene particles first appear, was measured in air at different contact times using optical microscopy and a gravimetric method. Asphaltene yields (mass asphaltene/mass oil) were measured in air over time gravimetrically. The data were compared with yields and "yield onsets" previously measured for the same mixtures in a nitrogen atmosphere. 1 In a nitrogen atmosphere, the yields increased and the onsets decreased over approximately 50 h but then reached plateau values, indicating that an equilibrium condition existed. In an air atmosphere, the yields and onsets were the same as in nitrogen for the first 50 h, but then the yields gradually increased for the duration of the experiments. The onsets shifted to lower values over time, and there was no equilibrium onset condition. Hence, precipitation data collected in air below 50 h can be used for kinetic modeling as is; however, data collected in air over longer times overstates asphaltene yields under anaerobic conditions and requires correction. It is hypothesized that the oxygen in the air catalyzes or participates in reactions that alter the asphaltenes and other crude oil components over time so that they become less soluble. The oxidation rate appears to correlate approximately with the asphaltene content of the oil. The population balance first developed by Maqbool et al., Modeling the Aggregation of Asphaltene Nanoaggregates in Crude Oil-Precipitant Systems. Energy Fuels, 25 (4), 2011, 1585-1596, and later modified by Duran et al., Kinetics of Asphaltene Precipitation/Aggregation from Diluted Crude Oil. Fuel, 255, 2019, 115859, was further adapted to account for the increase in yield over time due to oxygen by introducing a term for the generation of unstable asphaltene primary particles. The proposed model matched the precipitation yield data from this study and from the literature with an average absolute deviation of less than 2 wt %.

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Viscosity of characterized visbroken heavy oils

Cited by 15 publications

References 70 publications

Settling of Asphaltene Aggregates inn-Alkane Diluted Bitumen

Settling of Asphaltene Aggregates inn-Alkane Diluted Bitumen

Application of Ethylene Tar as an Additive in Visbreaking of Petroleum Vacuum Residue

Effect of Air on the Kinetics of Asphaltene Precipitation from Diluted Crude Oils

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