Abstract Visbroken products from a Western Canadian bitumen were generated at five different reaction conditions (temperature and residence time) in an in-house lab-scale continuous reactor unit. Visbroken products from a second Western Canadian bitumen and an Arabian vacuum bottoms were obtained from other sources. Densities and viscosities were measured for the whole oil, the maltenes, the distillates, the distillation residue, and the SARA (saturates, aromatics, resins and asphaltenes) cuts of the residue. The Expanded Fluid (EF) viscosity model was adapted to predict the viscosity of visbroken heavy oils characterized into pseudo-components corresponding to the distillate fraction and the residue SARA cuts. Using data from the first bitumen, the EF model parameters and densities for the cuts (an input for the EF model) were correlated to conversion and the feedstock cut densities and model parameters. The correlated cut properties were then recombined to obtain the whole oil density and viscosity using previously established mixing rules. The proposed approach matched the density and viscosity of all the visbroken products from the first bitumen with average absolute deviations of 1.1 kg/m3 and 8%, respectively. It predicted the product properties from the second bitumen with average absolute deviations of 2.4 kg/m3 and 17%, respectively, but was not accurate for the chemically dissimilar Arabian oil. A generalized methodology to predict visbroken product viscosity was provided for Western Canadian bitumens. The required inputs are the composition (distillate content and residue SARA assay) of the feed and visbroken oils, pressure, temperature, and conversion.
Abstract The modified regular solution (MRS) model for asphaltene precipitation was extended to visbroken bitumen products based on data from an Athabasca bitumen that was thermally cracked in a lab-scale flow-through visbreaker at five different temperatures and residence times. The thermal conversion for each visbroken product was calculated based on SimDist data. The feed and each product were characterized into 5 pseudo-components (distillates, saturates, aromatics, resins, and asphaltenes) ...
Abstract The molecular weight, density, and solubility parameter of the crude oil medium are inputs to regular solution based models for asphaltene precipitation. For native oils, these properties can be determined from a SARA (saturate, aromatic, resin, asphaltene) assay and existing correlations for each SARA component. However, thermo- and hydrocracking alter these properties and these changes must be accounted for when modeling the solubility of reacted oils. The effect of cracking on asphal...
#2Murray R. Gray(U of A: University of Alberta)H-Index: 63
Abstract Thermal cracking processes such as visbreaking are used in the petroleum industry to reduce the viscosity of heavy feedstocks, such as atmospheric and vacuum residues, without forming coke or unstable asphaltenes. Thermal cracking offers a potential method to reduce the viscosity of heavy oils and bitumen, enabling their pipeline transportation with less solvent addition. Viscosity is the most important property for transportation of crude oils, but this property also has a highly non-l...
Abstract In order to improve heavy oil characterizations for modeling crude oils in refinery processes, an in-house Deep Vacuum Fractionation Apparatus (DVFA) was recently modified to provide reproducible extended distillation data for heavy oils. In addition, an interconversion method was developed to obtain the Normal Boiling Points (NBP) of the distillation fractions. In the current contribution, the physical properties of the distillation cuts collected using the DVFA (the development datase...
A methodology has been developed to predict the viscosity of crude oils and their fractions from a distillation-based oil characterization. The maltenes were characterized as a set of pseudo-components with properties determined from established generalized correlations. The asphaltene fraction was characterized as a single component and its properties were measured. The viscosities of the pseudo-components, asphaltenes, whole oils, and their fractions were determined with the Expanded Fluid (EF...
Abstract Asphaltenes self-associate and their molecular weight, density, and solubility parameter distributions are factors in asphaltene precipitation. Thermo- and hydrocracking alter these distributions and these changes must be accounted for when modeling solubility. To determine these distributions for reacted asphaltenes, heptane extracted asphaltenes from native, thermo-cracked, and hydrocracked crude oils were fractionated into solubility cuts. The asphaltenes were dissolved in toluene an...
The expanded fluid (EF) viscosity model was recently developed for petroleum applications. While petroleum fluids can be modeled as a single-component fluid, process calculations often require that the fluid be treated as a mixture of pseudo-components. For mixtures, the EF model mixing rules require binary interaction parameters, αij, between each component pair in the mixture, which are fitted to experimental data. In this study, a generalized correlation is developed for these interaction par...
Distillation assays provide the most widely used characterization data for modeling crude oils in refinery processes but can only define a relatively small fraction of the boiling curve for heavy oils. One way to extend the distillation range for heavy oils is to lower the distillation pressure while still avoiding thermal cracking temperatures. A vacuum distillation apparatus (DVFA-I) that was previously used to measure the vapor pressure of heavy components was modified to fractionate heavy oi...
A novel methodology was extended for modeling the detailed composition of petroleum heavy vacuum resid fractions. The resid molecules were organized in terms of basic structural attributes: cores, intercore linkages, and side chains. The identities of the structural attributes were determined both from the extrapolation of chemical characteristics of light petroleum and the analysis of detailed mass spectrometric measurement of heavy resid fragmentation products. A building block library was con...
#2Zhaomin Li(China University of Petroleum)H-Index: 10
Last. Teng Lu(China University of Petroleum)H-Index: 8
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This paper combined experiments with a theoretical model to simulate the behavior between a foam and heavy oil during contact pressing, separation, and adsorption. We discuss the changes in the elasticity and adsorption forces during the pressing and adsorption of the two fluids. The influence of the changes in temperature and pressure, the concentration of the sodium dodecyl sulfate surfactant, the heavy oil viscosity, and the addition of partially hydrolyzed polyacrylamide and hydrophobic SiO2...
The kinetics of asphaltene precipitation was investigated for five crude oils diluted with n-heptane at 21oC 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 ...
