Thermophysical characterization of oil sands. 2. Acoustic properties

Propagation characteristics of shear (S) and compressional (P) waves are investigated for oil sands from the Athabasca, P.R. Spring, N.W. Asphalt Ridge and Circle Cliffs deposits. These studies are oriented towards applications of acoustic techniques in characterization, diagnostics and control of in-situ extraction methods currently envisaged for oil sand bitumen. The magnitude of the temperature dependence of S and P wave velocities is directly related to the bitumen content of the oil sand. The origin of the pronounced changes in Sand P wave velocities (or travel times) in the temperature regions 24–200 °C and 425–500 °C is traced to the thermal decomposition of oil and sand bitumen. The S and P wave velocities generally decrease with increasing bitumen content. Other variables that are studied, such as moisture content and bulk density, have relatively minor effects on the magnitude of the measured S and P wave velocities.     

Measurements of specific heat,thermal conductivity and thermal diffusivity of Utah tar sands

A constant applied heat flux method has been used to measure the specific heat and thermal conductivity of large samples of Utah (North-west Asphalt Ridge) tar sands as a function of temperature. Independent measurements of density allowed for the calculation of thermal diffusivity. Constituent analysis of the tar sand samples also permitted the calculation of bitumen and sand specific heats. Specific heat of the bitumen was found to increase with temperature from 1.85 to 3.9 kJ kg^?1 K^?1 for temperatures between 300 and 480 K. Specific heat of the sand matrix increased only slightly, from 0.85 to 1.0 kJ kg^?1 K^? for the same range of temperature. Corresponding thermal diffusivities for tar sand were found to decrease with temperature, and had a range of 5 · 10^?7–9 · 10^?7 m² s^?1 over the measured temperatures. It was concluded that the latent heat of both bitumen and water have a strong influence on the apparent overall specific heat of tar sand.     

Enthalpies of pyrolysis and oxidation of Athabasca oil sands

Thermal degradation of Athabasca oil sands, bitumen, and its fractions have been investigated in N₂and in air, at 25–600 °C and at pressures up to 6.9 MPa, using thermogravimetry (TG) and high pressure differential scanning calorimetry (PDSC). These conditions are likely to occur during in-situ recovery of bitumen by underground combustion processes. Two regions of weight loss are detected using both gases. The endothermic low temperature volatilization reactions (150–400 °C) absorbed +26 mJ mg^?1 for oil sand to +2319 mJ mg^?1 for medium oil. The heats of reaction for high-temperature cracking and volatilization reactions (400–550 °C) were similar. The heats of reaction for the low-temperature oxidation reactions (150–375 °C) were ?405 mJ mg^?1 for oil sand to ?30200mJ mg^?1 for medium oil. Values for the high-temperature oxidation reactions (400–550 °C) were slightly higher. Increasing the pressure of nitrogen and air caused an increase in the endothermicity and exothermicity of the respective reactions.     

Thermophysical properties of Devonian shales

A detailed study of the thermophysical properties of Devonian shales from the central and eastern United States has been carried out. Thermal conductivity, thermal diffusivity, specific heat and dielectric constant data are presented. A Michigan shale sample with an oil yield of 28 litres per metric ton (1 t^?1) and a Kentucky shale (oil yield: 52 l t^?1) were selected. The specific heats of these shales are in the range 0.20–0.30 cal gm^?1 °C^?1, and increase with increasing temperature. The thermal conductivity (κ) of the two shale samples are comparable (ca. 1 W m^?1 °C^?1). The κ values show only a weak temperature dependance. The thermal diffusivity (α) of these shales range from 0.3–0.5 × 10^?2 cm² s^?1 and tend to decrease with increasing temperature. The dielectric constants show anomalously high values at temperatures above 200 °C. This effect is indicative of interfacial polarization mechanisms presumably arising from loss of water and onset of pyrolysis of the shale organic matter. Comparison of the trends in thermophysical behaviour of Devonian shales with data obtained previously on Green River oil shales is presented. The importance of thermophysical measurements in on-field applications in oil shale technology is highlighted.     

Determination of specific heats of coal powders by differential scanning calorimetry

Specific heats (C_p) of bituminous and subbituminous coals were investigated in the temperature range 300–360K by differential scanning calorimetry (DSC). To establish the validity of the procedure, specific heats of glass beads and graphites in powdered and bulk form were determined. Good agreement was obtained with the values for the specific heats of glass and graphites in the literature, and it was established that the specific heats were not dependent on the degree of diminution of these materials. Specific heats of coal samples were found to depend upon mesh size, temperature, rank, moisture content and whether the coal powder was wet- or dry-screened. However, there were only minor differences in C_p between bituminous and subbituminous coals.     

Composition of oils produced during an echoing, in-situ combustion of a Utah tar sand

The Laramie Energy Technology Center (DOE) has completed its second in-situ combustion experiment (TS-2C), which was carried out in the Northwest Asphalt Ridge tar sand deposit near Vernal, Utah. During the experiment (183 days) 92 m³ (580 barrels) of oil was produced, 25% of the original oil in place. The in-situ process utilized is best described as a series of reverse- and forward-combustion phases or echoes traversing the 405 m² (0.1 acre) pattern. Several of the chemical and physical properties of the oil produced are significantly altered with respect to the original bitumen. These include pour point, specific gravity, average molecular weight, wax and nickel content, and the percentage of residue boiling at >538 °C (1000 °F). These and other changes effected on the bitumen during this experiment result in a product oil that closely resembles a heavy fuel oil.     

Isolation and f.i.m.s. analysis of saturated hydrocarbons from tar sand bitumens

Saturated hydrocarbons in two Utah tar sand bitumens were determined via compound-type isolation and mass spectral analyses. Four analytical methods for isolating saturated hydrocarbons were evaluated:

• 1.1) dewaxing,
• 2.2) modified deasphaltening,
• 3.3) adsorption and complexation chromatography,
• 4.4) desorptive Soxhlet extraction followed by complexation chromatography.

The latter method was preferred for concentrating the greatest amount of saturated hydrocarbons without overlap from aromatic or heteroatom-containing species. Field ionization mass spectrometry (f.i.m.s.) adequately profiled these hydrocarbons by molar mass (m/z) and by Z-series type. The sample of Northwest Asphalt Ridge bitumen was comprised of a wax of mostly acyclic and monocycloalkanes; whereas, the saturates from the sample of Asphalt Ridge bitumen were mostly tetracyclo- and penatcycloalkanes. Based upon a comparison of the saturate distributions in the samples of bitumen, the sample from the Northwest Asphalt Ridge deposit was found to have undergone less biodegradation. This wax-like sample of bitumen may have migrated to the deposit at a later time than the major bitumen generation and/or resulted from physicochemical segregation of waxy organic matter in the reservoir.     

Supercritical fluid extraction of bitumens from Utah oil sands

The supercritical fluid extraction (SFE) of bitumens from four major Uinta Basin (Utah) oil sand deposits was studied with propane solvent. The deposits studied included Whiterocks, Asphalt Ridge, PR Spring and Sunnyside. The bitumens from these deposits differed widely in physical and chemical properties. The volatilities (components with boiling point <811 K) were 46.6, 53.5, 45.4 and 40.9 wt.%; the molecular weights were 653, 426, 670 and 593 kg/kg mol; and the asphaltene contents (n-pentane insolubles) were 2.9, 6.8, 19.3 and 23.6 wt.% for the Whiterocks, Asphalt Ridge, PR Spring and Sunnyside bitumens, respectively. The SFE experiments were carried out at five conditions, combinations of three different pressures (5.6 MPa, 10.4 MPa, and 17.3 MPa) and three temperatures (339 K, 380 K and 422 K). The cumulative extraction yield increased with increase in solvent density at all operating conditions for the four bitumens. A maximum yield of 45 wt.% was obtained at the highest solvent density with the Whiterocks bitumen. The extraction products were significantly upgraded liquids relative to the bitumens. Comparatively lighter fractions were extracted in the earlier stages of extraction for all the four bitumens, whereas heavier extracts were obtained at higher extraction-solvent densities. The asphaltene contents of the residual fractions were significantly higher than the asphaltene contents predicted on a prorated basis for all four bitumens. This trend was due to the extraction of cosolubilizing components that kept the asphaltenes in suspension in the bitumen. It was concluded that solute polarity played a significant role in the extraction yields of the four bitumens. The Whiterocks bitumen, which was the least polar bitumen based on asphaltenes content, gave higher extraction yields compared to the bitumens from the other three deposits at all five operating conditions. The Sunnyside bitumen with the highest asphaltene content gave the lowest extraction yield at all five conditions. The Asphalt Ridge and PR Spring bitumens with intermediate polarity (based on asphaltene content) gave intermediate extraction yields with the Asphalt Ridge bitumen extraction yields higher than the PR Spring bitumen. Preliminary modeling of the extraction process using the Peng–Robinson cubic equation of state and a pseudocomponent lumping scheme provided a reasonable match with the experimental data for Whiterocks and PR Spring bitumens.     

Comparison of the chemical structure of coal hydrogenation products,athabasca tar sand bitumen and Green River shale oil

Coal hydrogenation products, Athabasca tar sand bitumen, and Green River shale oil produced by retorting were analyzed by the Brown—Ladner method and the Takeya et al. method on the basis of elemental analysis and ¹H-NMR data, by ¹³C-NMR spectroscopy and by FT-IR spectroscopy. Structural characteristics were compared.The results show that the chemical structure of oils from Green River shale oil and Athabasca tar sand bitumen, and the oils produced in the initial stage of hydrogenation of Taiheiyo coal and Clear Creek, Utah, coal is characterized as monomers consisting of units of one aromatic ring substituted highly with C_3–6 aliphatic chains and heteroatom-containing functional groups. The chemical structure of asphaltenes from Green River shale oil and Athabasca tar sand bitumen is characterized by oligomers consisting of units of 1–2 aromatic rings substituted highly with C_3–5 aliphatic chains and heteroatom-containing functional groups. The chemical structure of asphaltenes from coal hydrogenation is characterized by dimers and/or trimers of unit structures of 2 to 5 condensed aromatic rings, substituted moderately with C_2–5 aliphatic chains and heteroatom-containing functional groups.The close agreement between fa(¹H-NMR) and fa(¹³C-NMR) for Green River shale oil derivatives and Athabasca tar sand derivatives indicates that the assumption of 2 for the atomic H/C ratio of aliphatic structures is reasonable. For coal hydrogenation products, a value of 1.6–1.7 for the H/C ratio of aliphatic structures would be more reasonable.     

Synthesis,Surface Activities and Toluene Solubilization by Amine-oxide Gemini Surfactants

A series of amine-oxide gemini surfactants featuring amide groups [N, N’-dimethyl-N, N’-bis(2-alkylamideethyl)-ethylenediamine oxide (alkyl = C₁₁H₂₃, C₁₃H₂₇, C₁₅H₃₁, C₁₇H₃₅)] have been synthesized via a three-step synthetic route, and their chemical structures were confirmed by mass spectra, FTIR and ¹H-NMR spectra. The surface activities of these compounds have been measured. The results show that these synthesized amine-oxide gemini surfactants reduced the surface tension of water to a minimum value of approximately 26.91 mN m^?1 at a concentration of 2.92 × 10^?5mol L^?1. Furthermore, their critical micelle concentration (CMC) values and solubilization of toluene decrease with an increase of the hydrophobic chain length from 12 to 18. Isoelectric point measurements revealed that their pI values range from 4.0 to 10.5.     

Enhanced piezoelectric properties and electrical resistivity in W/Cr co-doped CaBi2Nb2O9 high-temperature piezoelectric ceramics

W/Cr co-doped Aurivillius-type CaBi₂Nb_2-x(W_2/3Cr_1/3)_xO₉ (CBN) (x?=?0.025, 0.050, 0.075, 0.100, and 0.150) piezoelectric ceramics were prepared by the conventional solid-state reaction method. The crystal structure, microstructure, dielectric properties, piezoelectric properties, and electrical conductivity of these ceramics were systematically investigated. After optimum W/Cr modification, the CBN ceramics showed both high d₃₃ and T_C. The ceramic with x?=?0.1 showed a remarkably high d₃₃ value of ~15 pC/N along with a high T_C of ~931?°C. Moreover, the ceramic also showed excellent thermal stability evident from the increase in its planar electromechanical coupling factor k_p from 8.14% at room temperature to 11.04% at 600?°C. After annealing at 900?°C for 2?h, the ceramic showed a d₃₃ value of 14?pC/N. Furthermore, at 600?°C, the ceramic also showed a relatively high resistivity of 4.9?×?10⁵ Ω?cm and a low tanδ of 9%. The results demonstrated the potential of the W/Cr co-doped CBN ceramics for high-temperature applications. We also elucidated the mechanism for the enhanced electrical properties of the ceramics.     

Thermoelectric properties of plasma sprayed of calcium cobaltite (Ca2Co2O5)

The thermoelectric properties of calcium cobaltite deposits produced by the plasma spray process are investigated from room-temperature to 873 K. Synthesis of Ca₃Co₂O₆ and Ca₂Co₂O₅ powders were prepared by the solid-state reaction from CaO and CoO_x starting powders. During their subsequent plasma spray Ca particles experience preferential evaporation within the plasma, resulting in a complex interplay among process conditions, stoichiometry, and resultant phases. The as-sprayed material predominantly contains amorphous and secondary phases. Upon annealing, the deposits show sensitivity to phase evolution and therefore thermoelectric properties. Through screening studies, optimal annealing conditions were identified which show a p-type Seebeck coefficient value of 180 μV K^?1, electrical conductivity of 1.09 × 10⁴ S m^?1, thermal conductivity of 1.16 W m^-1 K^-1 at 873 K. The resultant figure of merit value reached 0.266 for this combination of processing and thermal treatment and is in line with data reported from other techniques for this system.     

Effect of controlled-release fertilizer on nitrous oxide emission from a winter wheat field

A 2-year field experiment was conducted to study effects of application rate of controlled-release fertilizer (CRF) and urea on N₂O emission from a wheat cropping system. Two kinds of N fertilizers, CRF and urea, and four application rates (0, 100, 200 and 270?kg?N?ha^?1) were used. Results indicate that the application of either urea or CRF, increased total N₂O emission during the wheat growing period linearly from 32 to 164?%, with increasing N rate (p?<?0.05), compared to the zero N control, and the increase was less significant in CRF than urea treatments. Compared with urea, CRF significantly reduced N₂O emission by 25?C56?% during the wheat growing period (p?<?0.05), and the effect was more significant when N rate was higher. Grain yield increased in a power pattern from 24 to 43?% in urea treatments and from 30 to 45?% in CRF treatments with increasing N rate (p?<?0.05). Specific N₂O emission (N₂O emission per unit of yield) increased linearly from 31 to 114?% in urea treatments (p?<?0.05), and from 2 to 50?% in CRF treatments (p?<?0.05), with increasing N rate. Compared with urea, CRF significantly inhibited specific N₂O emission (p?<?0.05), and the effect increased with increasing N rate. Peaks of N₂O emission did not occur immediately after fertilization, but did immediately after rainfall events. CRF released fertilizer-N slowly, prolonging nitrogen supply and reducing peaks of N₂O fluxes stimulated by rainfall. The application rate of CRF could be reduced by 26?C50?% lower than that of urea for mitigating N₂O emission without sacrificing grain yield. We would not risk any significant loss of wheat yield while achieving economic and environmental benefits by reducing urea or CRF application rate from 270?kg to 200?kg?N?ha^?1.     

The conductance of 1:1 electrolytes in sulfolane in the presence of proton donors at 30°C

The molar conductances of LiCl, LiNO₃, KCHCl₂COO and Na p-(NO₂)C₆H₄O in sulfolane, in the presence of HCl, CH₃COOH, CHCl₂COOH and p-(NO)₂C₆H₄OH have been determined. The data were analysed by the full Pitts equation and interpreted in terms of the ionic association constant (K_A) of the salts K⁺A^? and K⁺RHA^?, and the heteroconjugation constant (K_f) of RHA^?. Values of K_f have been calculated from the ratio of association constant K_A(K⁺A^?)/K_A(K⁺RHA^?).     

Electrochemical impedance spectroscopy for in situ petroleum analysis and water-in-oil emulsion characterization

The measurement of electrochemical impedance spectroscopy used in situ is a suitable technique for the characterization of oil and water-in-oil emulsions. Nyquist diagrams for dehydrated oils are characterized by the formation of one semi-circle. The equivalent circuit proposed for the dehydrated oil is a resistance and capacitor (R_OC_O) in parallel. The resistance and conductivity of the oil calculated by impedance were 2.96 Gohm and 486 nS m^?1, respectively. Nyquist diagrams for the system composed of water emulsions in oil are mainly characterized by two semi-circles with different relaxation for oil and water-in-oil emulsions. The equivalent circuit is formed by R_O and CPE_O in parallel and in series with the arrangement of R_W/O and CPE_W/O in parallel, where R_O and CPE_O represents the oil, and R_W/O and CPE_W/O represents water-in-oil emulsions. The resistance of oil (R_O) and water-in-oil (R_W/O) emulsions increase with the increasing amount of water in the preparation. The increase in resistance shows that the emulsions become more stable with the addition of water. This result is consistent with the formation of rigid films on water–oil interfaces. The impedance measurements were applied to the analysis of the demulsification of the water-in-oil emulsions under an electrostatic field.     

Chloride-sulphate exchange on anion resins — kinetic investigation,IX. Direct,isotopic and reverse exchange

Experimental kinetics of direct, isotopic and reverse Cl^?/SO⁼₄ exchange on different anion resins are presented.At very low concentration (C = 6 × 10^?3 N) extremely high resin selectivity toward sulphates occurs (separation factors ranging from 52 to 589). Consequently chemical interaction of interdiffusing species within the resin seems to influence the rate determining step, exception made for isotopic exchange. Application of model equations from Nernst-Planck and SN₂ rate theories is discussed.     

Thermophysical properties of laboratory-prepared corn/wheat dried distillers grains and dried distillers solubles dehydrated with superheated steam and hot air

The objective of this study was to dry–wet distillers grains and centrifuged solubles and to examine the effect of two different drying media, superheated steam and hot air, at different drying temperatures (110, 130, and 160°C), moisture contents (5–30% wb), and percentages of solubles’ presence (0 or 100%) on some thermophysical properties of laboratory-prepared corn/wheat dried distillers co-products, including geometric mean diameter (d_g), particle density (ρ_p), bulk density (ρ_b), bulk porosity (?_b), specific heat (C), effective thermal diffusivity (α_eff), and bulk thermal conductivity (λ_b). The values of d_g of corn/wheat dried distillers co-products ranged from 0.358 ± 0.001 to 0.449 ± 0.001 mm. Experimental values of ρ_p, ρ_b, and ?_b varied from 1171 ± 6 to 1269 ± 3 kg m^?3, from 359 ± 7 to 605 ± 5 kg m^?3, and from 0.54 ± 0.01 to 0.71 ± 0.01 kg m^?3, respectively. The values of α_eff were between 0.58 × 10^?7 and 0.93 × 10^?7 m² s^?1. The calculated values of C ranged from 1887 ± 11 to 2599 ± 19 J kg^?1 K^?1, and the values of λ_b of corn/wheat dried distillers co-products ranged from 0.06 ± 0.01 to 0.09 ± 0.01 W m^?1 K^?1. Multiple linear regression prediction models were developed to predict the changes in d_g, ρ_p, ρ_b, ?_b, C, α_eff, and λ_b of laboratory-prepared corn/wheat dried distillers co-products with different operational factors.     

Specific energy dissipation rate for super‐high‐rate anaerobic bioreactor

BACKGROUND: Specific energy dissipation rate (?) is an important performance parameter of the super‐high‐rate anaerobic bioreactor (SAB) and is closely linked with power matching and operation optimization. The ? value was investigated for a SAB using anaerobic granular sludge and simulating gas production. The ? models for separation, reaction and water distribution units were established. RESULTS: Experimental results showed that the model predictions agreed well with the experimental data and, thus, they may be used for power matching and operation optimization of similar high‐rate anaerobic bioreactors. The ? value for the separation unit was so low as to be neglected. The maximum ? values for the reaction unit during nonfluidization, granular sludge agglomeration, liquid‐solid two‐phase fluidization and gas‐liquid‐solid three‐phase fluidization states were 0.143 W m^?3, 4.449 W m^?3, 2.173 W m^?3 and 11.132 W m^?3, respectively. The maximum ? value for the water distribution unit was 8.37 W m^?3. ? for the reaction unit was significantly influenced by ρ_p, u_l and V_p, u_g and d_p. CONCLUSION: The maximum ? value of 11.132 W m^?3 was the basic parameter for power matching for the SAB. Some measures were introduced to reduce the ? values based on parametric sensitivity analyses. The present investigation will further assist in optimizing the operation and design of SABs. Copyright © 2011 Society of Chemical Industry     

Phase transitions in mesophase macromolecules: The transitions of poly(p-acryloyloxybenzoic acid)

Poly(p-acryloyloxybenzoic acid) has been obtained in twelve single and two-phase physical states, which include the amorphous glassy and liquid states, the mesomorphic glassy and the mesomorphic liquid states and in addition eight two-phase semicrystalline states (crystal forms I and II). Using mainly differential scanning calorimetry, the transition temperatures, energies and heat capacity changes at the glass transitions have been studied. The time dependency of the glass transition has also been determined. The strongly heating rate dependent amorphous glass transition occurs at 348K (20k min^?1 heating rate, ΔC_p = 39 JK^?1 mol^?1), the mesophase glass transition, at 408K (also at 20k min^?1, ΔC_p = 43 JK^?1 mol^?1). The latter is less heating rate dependent. The amorphous to mesophase transition occurs between 375 and 475K (ΔH = ?4.5 KJ mol^?1); the peaks of melting transitions, which are also strongly heating rate dependent, were observed at 573K and 553K (20 K min^?1 heating rate) for crystal forms I and II, respectively. The heat of fusion of crystal form I is estimated to be 22 KJ mol^?1. There seems to be no partially amorphous-partially mesomorphic state.     

Etude voltamperometrique de la n-acetyl l-tyrosine amide sur electrode a pate de graphite en milleux aqueux I—comportement dans les domaines de balayage superieurs a 0,5 v/enh

Graphite paste electrode allows to determine elementary processes of the electrochemical oxidation in aqueous media of an electrochemical probe such as: N-acetyl L-tyrosine amide. Mathematical analysis of voltammograms gives the following EC mechanism: R?C₆H₅OH?R?C₆H₅O^. + H⁺ + e 2 R?C₆H₅O^. → R?C₆H₅O⁺ + R?C₆H₅O^?, R?C₆H₅O^? + H⁺ → R?C₆H₅OH, R?C₆H₅O⁺ → [R?C₆H₄O]^.. + H⁺, n[R?C₆H₄O]^.. → ?[R?C₆H₄O]^?_n.