Water content of light n‐alkanes: New measurements and cubic‐plus‐association equation of state modeling

Light hydrocarbon gases such as methane, ethane, propane, and butane or other so called gaseous solvents have been suggested as steam additives to improve bitumen recovery and energy efficiency. The water content of these gases is one of the key requirements in the simulation and design of solvent‐aided thermal heavy oil recovery processes. In this work, we present new experimental data for the water content of these gases at high temperatures (up to 493.15 K) and moderate pressures (P < 6 MPa). The experimental data was regenerated using the cubic‐plus‐association equation of state. The Soave–Redlich–Kwong equation of state is used to treat the physical interactions. The association interactions are captured using Wertheim's first‐order thermodynamic perturbation theory. A set of binary interaction parameters is proposed to calculate the water content of methane, ethane, propane, and n‐butane at the operating conditions of the thermal heavy oil and bitumen recovery processes. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1384–1389, 2017     

On the determination of diffusivities of volatile hydrocarbons in semi‐solid bitumen

Residual volatile hydrocarbons in bitumen constitute a potential source of air pollution. Diffusivities of volatile components in bitumen are needed to assess the extent of environmental damages that could result from bitumen spill or working loss of vapour to the atmosphere. Knowledge of solvent dispersion is also required in the recovery of viscous bitumen by solvent displacement. This paper discussed the de‐coupled transfer model developed by Tang and Zhang and its limiting solution. Fu and Phillips' diffusion data were re‐interpreted based on the limiting solution with delay time correction. The diffusion coefficients of hexane iso‐hexane, cyclo‐hexane and toluene at 25°C were found to be 8.6 × 10^?8 cm²/s, 6.3 × 10^?8 cm²/s, 2.4 × 10^?8 cm²/s and 6.8 × 10^?8 cm²/s, respectively. Improper use of the limiting solution could lead to 25% over‐estimates of diffusion coefficients.     

Application of taylor dispersion technique to measure mutual diffusion coefficient in hexane + bitumen system

A novel approach with fewer technical and analytic limitations in liquid solvent‐bitumen diffusion studies is used in this article. The Taylor dispersion technique was selected for its convenient short run time experiments and reliable data analysis to find mutual diffusion coefficients in a hexane + bitumen mixture. For the first time, the infinite‐dilution molecular diffusion coefficients of bitumen in hexane were measured in both the presence and relative absence of asphaltene particles in the solution at atmospheric pressure and temperatures of 303.15, 310.15, and 317.15 K. The polydisperse nature of bitumen was clearly revealed. Results were compared with common predictive tools. Also, the asphaltene surface charge in the hexane precipitating solvent was demonstrated. Through concentration dependency investigations at atmospheric pressure and 303.15 K, it was determined that the mutual diffusion coefficients monotonically decrease as the viscosity of mixture increases within the studied 0–34% volumetric concentration of bitumen. The Taylor dispersion technique shows great potential for diffusion studies of liquid solvent‐bitumen systems. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2670–2682, 2014     

Modeling the solubility of ternary mixtures of ethylene,iso‐pentane,n‐hexane in semicrystalline polyethylene

The coabsorptions of ethylene and iso‐pentane, and ethylene and n‐hexane were measured by the use of a pressure decay method. The solubility data of ethylene‐iso‐pentane and ethylene‐n‐hexane in semicrystalline polyethylene (PE) of crystallinity of 48.6% were obtained at temperatures 70, 80, and 90 °C, and the total pressure 2 MPa, iso‐pentane partial pressure 80–190 KPa, n‐hexane partial pressure 20–90 KPa. The presence of iso‐pentane or n‐hexane in the corresponding ternary system leads to increase the solubility of ethylene, while the solubility of iso‐pentane or n‐hexane remains unchanged with an increase of the ethylene partial pressure, even slightly decreases. Assumed that the presence of iso‐pentane or n‐hexane decreases the crystallinity of the polymer sample, a coabsorption model was built to model the solubility of each gas in the ternary systems. The relative root mean square errors of the coabsorption model for ethylene‐iso‐pentane‐PE system and ethylene‐n‐hexane‐PE system are 5.13% and 4.64%, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3654–3662, 2007     

Application of the rotating disk method to the study of bitumen dissolution into organic solvents

The rotating disk system is demonstrated as a tool for performing studies of the dissolution rate of bitumen into organic solvents. Mass transfer coefficients to the rotating disk are constant in position and time can be made comparable to coefficients for sand particles in agitated liquids by adjusting the rotation rate. Data is presented for bitumen dissolution into pentane, hexane, heptane, toluene and oleic acid. Increasing the level of dissolved bitumen in the solvent decreases the bitumen dissolution flux primarily due to the increase in solvent viscosity.     

Solvent screening for non‐aqueous extraction of Alberta oil sands

Non‐aqueous extraction of bitumen from oil sands has the potential to reduce fresh water demand of the extraction process and eliminate tailings ponds. In this study, different light hydrocarbon solvents, including aromatics, cycloalkanes, biologically derived solvents and mixtures of solvents were compared for extraction of bitumen from Alberta oil sands at room temperature and ambient pressure. The solvents are compared based on bitumen recovery, the amount of residual solvent in the extracted oil sands tailings and the content of fine solids in the extracted bitumen. The extraction experiments were carried out in a multistage process with agitation in rotary mixers and vibration sieving. The oil sands tailings were dried under ambient conditions, and their residual solvent contents were measured by a purge and trap system followed by gas chromatography. The elemental compositions of the extraction tailings were measured to calculate bitumen recovery. Supernatants from the extraction tests were centrifuged to separate and measure the contents of fine solid particles. Except for limonene and isoprene, the tested solvents showed good bitumen recoveries of around 95%. The solvent drying rates and residual solvent contents in the extracted oil sands tailings correlated to solvent vapour pressure. The contents of fine solids in the extracted bitumen (supernatant) were below 2.9% for all solvents except n‐heptane‐rich ones. Based on these findings, cyclohexane is the best candidate solvent for bitumen extraction, with 94.4% bitumen recovery, 5 mg of residual solvent per kilogram of extraction tailings and 1.4 wt% fine solids in the recovered bitumen. © 2012 Canadian Society for Chemical Engineering     

Analysis of Solvent‐Diluted Bitumen from Oil Sands Froth Treatment Using NIR Spectroscopy

Process control and optimization of bitumen froth treatment during oil sands processing require rapid analysis of asphaltene content in bitumen, solvent‐tobitumen ratio (S/B), and the density of solvent‐diluted bitumen. NIR spectroscopy was employed to meet this requirement. The NIR system comprised a spectrometer with no moving parts coupled with a double‐pass transflectance probe via a fiber‐optic cable. Quantitative calibration models were established using partial leastsquares regression in latent variables. The standard errors of calibration were 0.20 wt% for 0 to 20 wt% asphaltenes in bitumen, 1.1 wt% for 20 to 100 wt% asphaltenes in bitumen, 0.1 for S/B of solvent‐diluted bitumen, and 0.0017 g/mL for density of solvent‐diluted bitumen. It was shown that the process conditions could be monitored through the spectral scores from principal component analysis.     

Water‐Based Bitumen Recovery from Diluent‐Conditioned Oil Sands

Important process development aspects leading to more efficient bitumen recovery from diluent‐conditioned oil sands by water‐based methods are discussed. Bitumen viscosity of 0.5–2 Pa·s is required at the processing temperature and can be reduced to this level by bitumen dilution with an organic solvent. Oil sand porosity, however, poses a restriction on the amount of diluent that can be accepted by the oil sand. Also oil sand‐diluent conditioning time is an important process parameter and can vary from a few minutes for oil sands with low‐viscosity bitumen to several hours if viscosity of the bitumen is high. Additionally, the bitumen separation efficiency during digestion and flotation can be enhanced by reducing the bitumen/water interfacial tension through addition, for example, of tripolyphosphate to the aqueous phase.     

印尼油砂沥青的净化工艺

溶剂萃取法分离油砂制得油砂沥青中含大量机械杂质,影响沥青的品质及后期加工利用。通过XRD和激光粒度仪表征了机械杂质的矿物组成和粒度分布等特性。针对机械杂质的特性,开发了复配试剂,通过稀释剂降黏沥青、复配试剂净化沥青、稀释剂回收再生及循环利用3个操作单元对油砂沥青进行了脱杂净化实验,并分析了净化机理。结果表明：降黏过程,温度70℃、时间10min、稀释剂与沥青比0.3g/g,稀释沥青70℃黏度为3.2Pa·s;净化过程,6%盐酸与稀释沥青比0.2mL/g、CaCl₂与稀释沥青比0.01g/g,温度70℃,混合时间10min,沉降时间20min,机械杂质脱除率可达到93.5%;回收及循环过程,稀释剂回收率为98%,循环使用5次,机械杂质脱除率仍92%以上。该工艺具有沉降时间短、机械杂质脱除彻底的优点。     

The impact of chaotic advection on the microstructure of polymer‐modified bitumen

Owing to the high viscosity of the materials involved, mixing is often a critical step when processing polymer‐modified bitumen (PMB), directly influencing the microstructure and the stability of final products. We provide experimental evidence suggesting that laminar chaotic advection may prove a valuable strategy for obtaining a homogeneous and finely interdispersed polymer‐bitumen mixture in affordable time. As a case study, we investigate the mixing performance of a lab‐scale flat‐bottomed cylindrical vessel stirred by a radial impeller, either located symmetrically or eccentrically with respect to the vessel axis. The same geometries with a flat‐disk impeller are also considered for comparison. The Mix‐Norm is used in combination with image analysis as an objective measure of mixing performance. Results of mixing performance are independently validated by rheological tests. The experiments pinpoint kinematic chaos as the fundamental transport mechanism enhancing both the dispersion process and the microstructural quality of the resulting PMBs mixture. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1870–1879, 2014     

Capillary Curves for Ex‐situ Washing of Oil‐Coated Particles

The oil removal efficiency for the ex situ extraction of bitumen from oil sands, or ex situ washing of oil‐contaminated sand and related processes is determined by the balance of forces at the oil/water and solid/fluid interfaces. The objective of this work is to estimate the balance of forces at the interface using dimensionless numbers, and their use in evaluating and engineering ex situ soil washing processes. To this end, bitumen was removed from bitumen‐coated sand particles using a two‐step process. In the first step, the particles were mixed with a suitable solvent (toluene) used, primarily, to reduce the viscosity of bitumen. The particles were then mixed with water or an aqueous surfactant solution capable of producing low interfacial tensions with the solvent‐bitumen mixture. The fraction of oil retained after washing was evaluated as a function of interfacial tension, solvent/bitumen ratio, mixing time, mixing velocity, and particle size. These ex situ washing conditions were normalized using dimensionless film and particle‐based Weber and Capillary numbers. The fraction of oil retained by the particles was plotted against these dimensionless numbers to generate capillary curves similar to those used in enhanced oil recovery. These curves reveal the existence of a critical film‐based Weber number and a particle‐based Capillary number that can be used in the design or evaluation of soil washing processes. The film‐based Weber number also explained literature data that associates interfacial tension with the removal of oil from oil‐based drill cuttings, as well as field observations on the role that particle size plays on the removal of oil in soil washing operations.     

Displacement of bitumen from reconstituted oil sands by aqueous solutions

A simple method has been developed for modelling the recovery of bitumen from packed beds of oil sand by water or caustic solution displacement. Batches of reconstituted oil sand were prepared by intimately mixing predetermined amounts of sand, water, and bitumen, thereby permitting the composition of the oil sand to be controlled and varied within a wide range. Dilution of the bitumen with hexadecane facilitated the mixing process and allowed experiments to be performed at low temperatures while maintaining oil-water viscosity ratios comparable to those prevailing at the higher temperatures encountered during hot water or steam displacements in the field. The effects of a wide range of compositional and operational variables were studied using a two-level fractional factorial design technique and the findings are discussed. Of particular interest are the observations that the density and initial connate water saturation of the oil sand exert significantly more effect on bitumen recovery efficiency for the case of water displacement than for caustic solution displacement.     

Application of microbial enhanced oil recovery technology in water‐based bitumen extraction from weathered oil sands

When using the water‐based extraction processes (WBEPs) to recover bitumen from the weathered oil sands, very low bitumen recovery arisen from the poor liberation of bitumen from sand grains is always obtained. Application of microbial enhanced oil recovery (MEOR) technology in WBEPs to solve the poor processability of the weathered ore was proposed. It was found that processability of the microbial‐treated weathered ore was greatly improved. The improved processability was attributed to the biosurfactants production in the culture solution, alteration of the solids wettability, degradation of the asphaltene component, and the decrease of the bitumen viscosity, which collectively contributed to the bitumen liberation from the surface of sand grains. Although it still has many issues to be solved for an industrial application of the MEOR technology in oil sands separation, it is believed that the findings in this work promote the solution to the poor processability of the weathered ore. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2985–2993, 2014     

Preparation of bitumen from oil sand by ultracentrifugation

Ultracentrifugation was investigated as a means to obtain solvent-free bitumen from oil sand. The bitumen from three oil sands of varying grades was separated by placing the sands in specially designed tubes and centrifuging for 2 h at 198 000 at 20 °C. For all grades of oil sand, approximately 70% of the bitumen was recovered. The recovered bitumen was compared to the residual remaining on the sand, and to that extracted by the conventional Soxhlet technique. The ultracentrifuged bitumen contained some emulsified water and a small amount of fine solids. The solvent-extracted material was water-free, but contained a small amount of residual solvent and fine solids. The ultracentrifuge caused some fractionation of the bitumen, resulting in a product slightly enriched in asphaltene components compared to the solvent-extracted material. The residual bitumen remaining on the sand was correspondingly slightly depleted in asphaltenes. However, as evidenced by gas Chromatographic simulated distillation data, ultracentrifugation did retain the light (180–220 °C) components of the bitumen which were lost during the solvent removal step following solvent extraction. Other analyses such as density, viscosity and elemental composition verified that ultracentrifugation resulted in some fractionation of bitumen components.     

Waste polyvinyl chloride‐modified bitumen

Polyvinyl chloride (PVC) pipe wastes have been employed as a soft filler up to a level of 11 wt % in making bituminous products for paving applications. The PVC wastes were homogenously mixed with bitumen in the molten state. The viscoelastic properties of the bitumen blends such as storage modulus, loss modulus, and dynamic viscosity were studied and compared with those of neat bitumen. These properties were studied using an ARES‐Rheometer (Rheometric Scientific, Co.) under nitrogen atmosphere. The results indicate that the incorporation of the waste PVC into bitumen enhances the dynamic mechanical moduli and viscosity of the bitumen. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1501–1505, 2006     

Polymer‐modified bitumen of recycled LDPE and maleated bitumen

Maleated bitumen was prepared by the reaction of penetration grade bitumen (80/100) with maleic anhydride at 150°C for 2 h under nitrogen atmosphere. The effectiveness of maleation was assessed in bitumen–recycled low‐density polyethylene (LDPE) blends in terms of their softening point and elastic recovery. It was observed that the softening point and elastic recovery of the blends increased after maleation of the base bitumen owing to the formation of an asphaltene‐linked‐LDPE system. To obtain the desired elasticity, a recoverable composition was worked out with the help of maleated bitumen, recycled LDPE and styrene–butadiene–styrene. The storage stability of the blends was assessed in terms of their difference in softening points, rheological parameters, and microstructure of the top and bottom portions of test tube samples. The difference in softening point of the recoverable maleated bitumen blend was 5°C as compared to 60°C for the base bitumen blend. The phase angle was also reduced to 7.4° at 70°C compared with the 44.30° for the base bitumen blend. Scanning electron micrographs indicate that polymers existed in both the top and the bottom portions of the aged test tube maleated blend samples. The stability of the blend was further improved when LDPE is colloidal milled with maleic anhydride in the blend preparation. Roofing bitumen was also made with maleated bitumen containing 9 wt % recycled LDPE content. Based on the rheological data, it was found that the maleated bitumen–LDPE blend exhibited superior time‐/temperature‐dependent response and higher creep recovery compared with the base bitumen blend. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2013     

Effect of Operating Temperature on Water‐Based Oil Sands Processing

Operating temperature is one of the most important controlling parameters in oil sands processing. Considering the massive energy consumption and green house gas emission, lowering the processing temperature is highly desirable. To achieve such an ambitious goal requires a comprehensive understanding on the role of temperature in oil sands processing. This paper provides an overview of major findings from existing studies related to oil sands processing temperature. The relation between temperature and bitumen recovery is discussed. The effect of temperature on the physiochemical properties of oil sand components, such as bitumen viscosity, bitumen surface tension and surface potentials of bitumen and solids, is analyzed. The interactions between bitumen and solids and between bitumen and gas bubbles as a function of temperature are recounted. Also discussed is the role of chemical additives in oil sand processing. It has been found that temperature affects nearly all properties of oil sands among which bitumen viscosity and bitumen‐solids adhesion impose a prominent impact on bitumen recovery. The use of selected chemical additives can reduce bitumen viscosity and/or the bitumen‐solids adhesion, and thus provide a possible way to process oil sands at a low temperature while maintaining a high bitumen recovery.     

Phase behavior,density, and crystallization of polyethylene in n‐pentane and in n‐pentane/CO2 at high pressures

The phase behavior and volumetric properties of polyethylene (PE) in solutions of n‐pentane and n‐pentane/CO₂ were studied in a temperature (T) range of 370–440 K at pressures up to 60 MPa. Measurements were conducted with a variable‐volume view‐cell system equipped with optical sensors to monitor the changes in the transmitted light intensity as the P or the T of the system was changed. Lower‐critical‐solution‐temperature‐type behavior was observed for all of the liquid–liquid (L–L) phase boundaries, which shifted to higher pressures in solutions containing CO₂. The solid–fluid (S–F) phase boundaries were investigated over a P range of 8–54 MPa and took place in a narrow T range, from 374 to 378 K in this P interval. The S–F phase boundary showed a unique feature in that the demixing temperatures showed both increasing and decreasing trends with P depending on the P range. This was observed in both the PE/n‐pentane and PE/n‐pentane/CO₂ mixtures. The density of these solutions were measured as a function of P at selected temperatures or as a function of T at selected pressures that corresponded to the paths followed in approaching the phase boundaries (S–F or L–L) starting from a homogeneous one‐phase condition. The data showed a smooth variation of the overall mixture density along these paths. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2201–2209, 2003     

Viscosity of cold lake bitumen and its fractions

New data are presented for the effect of temperature on the viscosity of bitumen fractions, which were obtained by vacuum distillation of a large Cold Lake bitumen sample. The viscosity of these fractions differs by several orders of magnitude; from 4.3 mPa?s for Cut 1 to 430 000 mPa?s for Cut 4 at 30°C. Cut 5 is a glass-like solid at room temperature with a softening temperature of about 100°C, and has a viscosity of 800 000 mPa?s at 120°C. The effect of temperature on the viscosity of each bitumen fraction is modelled very well with a two-parameter correlation that was shown to be valid generally for Alberta bitumens. The results of bitumen viscosity calculations, based on a simple liquid-mixture viscosity formula, are presented and compared with the bitumen viscosity data.     

Miscibilities of polymers in bitumen and tall oil pitch under different mixing conditions

The miscibilities of the most important types of waste plastics were studied both by mixing them directly in bitumen and by using tall oil pitch as a dispersing agent. The results are presented as triangular diagrams based on softening points. The mixes containing PE-LD or PP become softer when 5–30 wt% bitumen is replaced by tall oil pitch. Two different mixing procedures were studied; so-called substrate mixing was found to yield better results than direct mixing. To be successful, substrate mixing requires a sufficiently high blending temperature and intensive agitation. Finally, a substrate can be diluted with suitable base bitumen according to use.